text:
Accessibility statement

The Lasso for High-Dimensional Regression with a Possible Change-Point

Wednesday 31 October 2012, 4.15PM to 5.45pm

Speaker(s): Myung Hwan Seo, LSE

Abstract

We consider a high-dimensional regression model with a possible change-point due to a covariate threshold and develop the Lasso estimator of regression coefficients as well as the threshold parameter. Under a sparsity assumption, we derive nonasymptotic oracle inequalities for both the prediction risk and the $\ell_1$ estimation loss for regression coefficients. Furthermore, we establish conditions under which the unknown threshold parameter can be estimated at nearly $n^{-1}$ when the number of regressors can be much larger than the sample size ($n$). We illustrate the usefulness of our proposed estimation method via Monte Carlo simulations and an application to real data.

The paper is also available to view at - http://arxiv.org/abs/1209.4875.

Location: Economics Staff Room (A/EC/202)

format: plain


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# Object distance and image distance

The object distance is the distance of the object to the centre line of the lens. This is denoted by the symbol do.

The image distance (sometimes confused with the focal length) is the distance of the image to the centre line of the lens. This is denoted by the symbol di.

With the principal focal length added this would look like:


text:
Hans Zwart (Corresponding Author), Birgit Jacob, Olof Staffans

17 Citations (Scopus)

## Abstract

Two conjectures on admissible control operators by George Weiss are disproved in this paper. One conjecture says that an operator $B$ defined on an infinite-dimensional Hilbert space $U$ is an admissible control operator if for every element $u \in U$ the vector $Bu$ defines an admissible control operator. The other conjecture says that $B$ is an admissible control operator if a certain resolvent estimate is satisfied. The examples given in this paper show that even for analytic semigroups the conjectures do not hold. In the last section we construct a semigroup example showing that the first estimate in the Hille-Yosida theorem is not sufficient to conclude boundedness of the semigroup.
Original language English 341-350 19 Systems and control letters 48 3-4 https://doi.org/10.1016/S0167-6911(02)00277-3 Published - 15 Mar 2003

## Keywords

• $C_0$-semigroup
• Conditional basis
• MSC-93C25
• Infinite-dimensional system


text:
A real number $x$ such that $x^n$ and $(x+1)^n$ are rational is itself rational

Let $x$ be a real number and let $n$ be a positive integer. It is known that both $x^n$ and $(x+1)^n$ are rational. Prove that $x$ is rational.

What I have tried:

Denote $x^n=r$ and $(x+1)^n=s$ with $r$, $s$ rationals. For each $k=0,1,\ldots, n−2$ expand $x^k\cdot(x+1)^n$ and replace $x^n$ by $r$. One thus obtains a linear system with $n−1$ equations with variables $x$, $x^2$, $x^3,\ldots x^{n−1}$. The matrix associated to this system has rational entries, and therefore if the solution is unique it must be rational (via Cramer’s rule). This approach works fine if $n$ is small. The difficulty is to figure out what exactly happens in general.

Answer

Here is a proof which does not require Galois theory.

Write
$$f(z)=z^n-x^n\quad\hbox{and}\quad g(z)=(z+1)^n-(x+1)^n\ .$$
It is clear that these polynomials have rational coefficients and that $x$ is a root of each; therefore each is a multiple of the minimal polynomial of $x$, and every algebraic conjugate of $x$ is a root of both $f$ and $g$. However, if $f(z)=g(z)=0$ then we have
$$|z|=|x|\quad\hbox{and}\quad |z+1|=|x+1|\ ;$$
this can be written as
$$\def\c{\overline} z\c z=x\c x\ ,\quad z\c z+z+\c z+1=x\c x+x+\c x+1$$
which implies that
$${\rm Re}(z)={\rm Re}(x)\ ,\quad {\rm Im}(z)=\pm{\rm Im}(x)=0\tag{*}$$
and so $z=x$. In other words, $f$ and $g$ have no common root except for $x$; so $x$ has no conjugates except for itself, and $x$ must be rational.

As an alternative, the last part of the argument can be seen visually: the roots of $f$ lie on the circle with centre $0$ and radius $|x|$; the roots of $g$ lie on the circle with centre $-1$ and radius $|x+1|$; and from a diagram, these circles intersect only at $x$. Thus, again, $f$ and $g$ have no common root except for $x$.

Observe that the deduction in $(*)$ relies on the fact that $x$ is real: as mentioned in Micah’s comment on the original question, the result need not be true if $x$ is not real.

Comment. A virtually identical argument proves the following: if $n$ is a positive integer, if $a$ is a non-zero rational and if $x^n$ and $(x+a)^n$ are both rational, then $x$ is rational.

Attribution
Source : Link , Question Author : Dan Ismailescu , Answer Author : David


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# [C++] Copy constructor optimization

This topic is 3759 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

The following code compiles without errors under Visual Studio 2005
class NoCopy
{
private:
NoCopy(const NoCopy&);

protected:
NoCopy() {}
~NoCopy() {}
};

class Foo : private NoCopy
{
public:
Foo(int) {}
~Foo() {}
};

int main()
{
Foo f(Foo(42));
}

Is the compiler allowed to optimize away the call to the copy constructor while calling the copy constructor is illegal?

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It shouldn't. I tested it under Borland Dev Studio 2006 and it outputs an error:
[C++ Error] Unit1.cpp(21): E2285 Could not find a match for 'Foo::Foo(Foo)'

VS 2008 doesn't output any errors.

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Because you did not specify a copy constructor for Foo, Foo has an implicit public copy constructor which is called. This copy constructor has to call NoCopy's copy constructor, respectively, which you declared private. So, no... the compiler shouldn't allow that.

Private copy constructor is something I've used in the past with gcc too, and I'm quite sure it worked as intended (i.e. it bailed out).

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Quote:
 Original post by samothBecause you did not specify a copy constructor for Foo, Foo has an implicit public copy constructor which is called. This copy constructor has to call NoCopy's copy constructor, respectively, which you declared private. So, no... the compiler shouldn't allow that.

But if I did specify a public copy constructor for Foo, the compiler would be allowed to optimize away the call to the copy constructor. So the question remains why the optimization isn't allowed in my example.

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I don't think the syntactic correctness of code should depend on compiler-specific optimizations.

Your attempt to use a private copy should be an error, even if the compiler would be later able to remove the copy altogether.

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I think the compiler is allowed to do it. The relevant section of the standard is:

When certain criteria are met, an implementation is allowed to omit the copy construction of a class object, even if the copy constructor and/or destructor for the object have side effects. In such cases, the implementation treats the source and target of the omitted copy operation as simply two different ways of referring to the same object, and the destruction of that object occurs at the later of the times when the two objects would have been destroyed without the optimization. This elision of copy operations is permitted in the following circumstances (which may be combined to eliminate multiple copies):

— in a return statement in a function with a class return type, when the expression is the name of a non-volatile automatic object with the same cv-unqualified type as the function return type, the copy operation can be omitted by constructing the automatic object directly into the function’s return value

— when a temporary class object that has not been bound to a reference (12.2) would be copied to a class object with the same cv-unqualified type, the copy operation can be omitted by constructing the temporary object directly into the target of the omitted copy

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In the following code the compiler is allowed by the standard to optimize away the call to the copy constructor. The optimization is not just a compiler specific optimization. Note that applying the optimization results in different behaviour.

#include <iostream>class Foo{public:	Foo(const Foo&) { std::cout << "Foo(const Foo&)" << std::endl; }	Foo(int) { std::cout << "Foo(int)" << std::endl; }	~Foo() {}};int main(){	Foo f(Foo(42));}

So why isn't the compiler allowed to do the same optimization in my first example?

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Quote:
 Original post by crocomireSo why isn't the compiler allowed to do the same optimization in my first example?

I think it is, which is why it compiles. :)

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I tried my example with the online Comeau C/C++ compiler:

Your Comeau C/C++ test results are as follows:

Comeau C/C++ 4.3.10.1 (May 29 2008 09:37:15) for ONLINE_EVALUATION_BETA1
MODE:strict errors C++ noC++0x_extensions

"ComeauTest.c", line 11: error: "NoCopy::NoCopy(const NoCopy &)" (declared at line
4) is inaccessible
class Foo : private NoCopy
^
detected during implicit generation of "Foo::Foo(const Foo &)" at
line 20

1 error detected in the compilation of "ComeauTest.c".

In strict mode, with -tused, Compile failed

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Quote:
 Original post by crocomireBut if I did specify a public copy constructor for Foo, the compiler would be allowed to optimize away the call to the copy constructor.
Yes, that's right, if your constructor doesn't initialize the base class, such as in:
Foo(const Foo&) {}

However, a "correct" copy constructor the way the compiler implements it would call the base constructor(s), somewhat like this:
Foo(const Foo&) : NoCopy() {}

Of course, NoCopy doesn't have any data members, and it's not meant to actually do anything, so it is silly to try to initialize something. However, that's because you know what's intended, the compiler doesn't know, to start with. The compiler can't just assume that it doesn't matter whether or not it initializes something just because it feels like it.

In the end, any decent compiler would finally decide that the constructor is useless and eliminate it, but access checking has to occur before any optimizations take place, because the first thing a compiler has to make sure is that a program is valid.

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# Homework Help: More limits, just a simple question this time

1. May 19, 2010

### Asphyxiated

1. The problem statement, all variables and given/known data

I just have a question about these two questions:

$$\lim_{y \to 3^{+}} \frac {y+1}{(y-2)(y-3)}$$

and

$$\lim_{y \to 3} \frac {y+1}{(y-2)(y-3)}$$

the solution to the first problem is infinity and the solution to the second is does not exist, is this because the first one is is approach 3 from the positive side so its basically 3.000000000000...1 and therefore infinity and the second is at 3 so the denominator is 0? If i am wrong please clarify this issue for me.

thanks!

2. May 19, 2010

### physicsman2

The first one is infinity because you're essentially dividing by a very small positive number since you're approaching 3 from the right. When applying the limit, you will get something like 4/(1 x 0^+), meaning your dividing 4 by a very very small number therefore the limit is infinity.

The second one does not exist because if you take the one sided limits, you will get +infinity when you approach 3 from the right and -infinity when you approach 3 from the left. Since the limits from both sides don't match, the limit as x approaches 3 DNE.

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text:
# Thread: Numbers on the blackboard

1. ## Numbers on the blackboard

To play the game FADEOUT, you begin by writing any set of 1994 numbers on the blackboard. You are then permitted to erase any pair of them, say a and b, and replace them by the number $(a+b)/4$. You continue this process 1993 times, after which only one number remains on the blackboard.

Suppose that at the beginning of the game, all 1994 numbers on the board are 1. Prove that the number left at the end will never be less than 1/1994.

2. Originally Posted by scipa
To play the game FADEOUT, you begin by writing any set of 1994 numbers on the blackboard. You are then permitted to erase any pair of them, say a and b, and replace them by the number $(a+b)/4$. You continue this process 1993 times, after which only one number remains on the blackboard.

Suppose that at the beginning of the game, all 1994 numbers on the board are 1. Prove that the number left at the end will never be less than 1/1994.
The problem describes a process (which I'll call an amalgamation process) whereby one starts with a set of numbers which are all equal to 1, and combines them together pairwise in a sequence of operations, until there is only one number remaining. I'll call this number the outcome of the amalgamation process. We want to show that if there are initially n 1s then the outcome must be at least 1/n.

At each stage of the process, two numbers are chosen from the set. Call them a and b. They are replaced by the single number (a+b)/4. If we look at the number a and trace back where it came from, we see that it is either one of the original 1s, or it the result of combining two other numbers. If we continue tracing these numbers back, we see that a is in fact the outcome of an amalgamation process starting with a subset of the original n 1s. If this subset contains p 1s then a is the outcome of an amalgamation process starting with p 1s. Similarly b is the outcome of an amalgamation process starting with q 1s.

The idea is to prove by induction that the outcome of an amalgamation process starting with n 1s is at least 1/n. This is trivially true for n=1. Suppose as a (strong) inductive hypothesis that it is true for all numbers less than n.

Take an amalgamation process starting with n 1s, and consider the final stage of this process, in which the two remaining elements a and b are combined to form the outcome c=(a+b)/4. Since a is the outcome of an amalgamation process starting with p 1s, it follows from the inductive hypothesis that a≥1/p. Similarly, b≥1/q. Also, since this is the final operation in the amalgamation process, p+q=n.

Therefore c ≥ ((1/p) + (1/q))/4 = (p+q)/4pq. We want to show that this is ≥1/(p+q). Equivalently, we must show that (p+q)^2≥4pq. But this follows from the fact that (p+q)^2–(p-q)^2 = 4pq. That completes the inductive proof. All that remains is to put n=1994.


text:
# A Ramp

• October 24th 2009, 01:27 AM
MathBane
A Ramp
The question:

Suppose a ramp is used to move a heavy object into a van. Suppose also that the van door is 18 inches off the ground.

(a) If the bottom of the ramp rests on the ground 3 feet from the van, what is the slope of the ramp? (Round your answer to two decimal places.)

(b) If the ramp cannot have a slope of more than 1.3 inches per foot, how far from the van should the ramp rest? (Round your answer to two decimal places.)

____ ft

I don't understand what it means... I got 11.53, but that's wrong.
• October 24th 2009, 01:42 AM
Gusbob
Which part did you not understand?

Using the concept that slope = $\frac{rise}{run}$

We can substitute our given values for slope (1.3 in/ft) and rise (18 inches) to find distance from van (x feet):

$1.3 = \frac{18}{x}$

$x = \frac{18}{1.3} \approx 13.846$ feet
• October 24th 2009, 02:07 AM
MathBane
Oh... I completely forgot to manipulate the formula. Silly me. Thanks for your help.


text:
# Sunday, March 19, 2017¶

I continued my avalanche of changes for #1596 and then released first to Vilma and then to Jane.

Funnily there was a problem on Jane which was not on Vilma:

AppRegistryNotReady: Apps aren't loaded yet.

I worked around it by partly undoing what I did yesterday: fields_list has not become more severe, it just issues a clearer error message when something has no name attribute.

TODO: adapt test suites to my changes.


text:
#### 2.17.7: no longer depends on nem; more models from MAGELLAN

ramon diaz-uriarte (at Phelsuma) authored on 30/01/2020 13:39:14
Showing 1 changed files
 ... ... @@ -84,7 +84,10 @@ sh. See \code{\link{allFitnessEffects}}} 84 84  input, as "restriction table" in \code{\link{allFitnessEffects}}. 85 85   86 86  } 87 -\author{Ramon Diaz-Uriarte} 87 +\author{Ramon Diaz-Uriarte. Code for transitive closure taken from the 88 + nem package, whose authors are Holger Froehlich, Florian Markowetz, 89 + Achim Tresch, Theresa Niederberger, Christian Bender, Matthias Maneck, 90 + Claudio Lottaz, Tim Beissbarth} 88 91   89 92  \examples{ 90 93  (a1 <- simOGraph(10))

#### version 2.7.2 Changes in version 2.7.2 (2017-09-27): - genot_to_adj_mat in C++. - fast_peaks (for no backmutation cases). - Better explanation and testing of peaks and valleys. - Clarified simOGraph transitive reduction. - Better handling of ti corner cases. - Magellan reading fuctions adapted to output of newer (as of 2017-07) version of Magellan. - sorting gene names in allGenotypes_to_matrix. - sampledGenotypes: genotype names with sorted gene names.

ramon diaz-uriarte (at Phelsuma) authored on 27/09/2017 10:23:50
Showing 1 changed files
 ... ... @@ -34,8 +34,9 @@ s = 0.1, sh = -0.1, typeDep = "AND") 34 34  \item{removeDirectIndirect}{ 35 35  Ensure that no two nodes are connected both directly (i.e., with an 36 36  edge between them) and indirectly, through intermediate nodes. If 37 - TRUE, the direct connections are removed from the graph starting from 38 - the bottom. 37 + TRUE, we return the transitive reduction of the DAG. 38 + %% the final DAG returned is the transitive reduction of thethe direct 39 + %% connections are removed from the graph starting from the bottom. 39 40  } 40 41  \item{rootName}{ 41 42  The name you want to give the "Root" node.

#### v.2.5.2 - Lots and lots of addition to vignette including benchmarks. - Diversity of sampled genotypes. - Genotyping error can be added in samplePop. - LOD and POM (lines of descent, path of maximum, sensu Szendro et al.). - simOGraph can also out rT data frames. - Better (and better explained) estimates of simulation error for McFL.

 ... ... @@ -7,8 +7,11 @@ 7 7  Simulate DAGs that represent restrictions in the accumulation of mutations. 8 8  } 9 9  \usage{ 10 -simOGraph(n, h = 4, conjunction = TRUE, nparents = 3, 11 -multilevelParent = TRUE, removeDirectIndirect = TRUE, rootName = "Root") 10 +simOGraph(n, h = ifelse(n >= 4, 4, n), conjunction = TRUE, nparents = 3, 11 +multilevelParent = TRUE, removeDirectIndirect = TRUE, rootName = "Root", 12 +geneNames = seq.int(n), out = c("adjmat", "rT"), 13 +s = 0.1, sh = -0.1, typeDep = "AND") 14 + 12 15  } 13 16   14 17  \arguments{ ... ... @@ -36,9 +39,27 @@ multilevelParent = TRUE, removeDirectIndirect = TRUE, rootName = "Root") 36 39  } 37 40  \item{rootName}{ 38 41  The name you want to give the "Root" node. 42 +} 39 43   44 +\item{geneNames}{ 45 + The names you want to give the the non-root nodes. 40 46  } 47 + 48 + 49 +\item{out}{Whether the ouptut should be an adjacency matrix or a 50 + "restriction table", as used in \code{\link{allFitnessEffects}}.} 51 + 52 +\item{s}{If using as output a restriction, the default value for s. See 53 +\code{\link{allFitnessEffects}}.} 54 + 55 +\item{sh}{If using as output a restriction, the default value for 56 +sh. See \code{\link{allFitnessEffects}}} 57 + 58 +\item{typeDep}{If using as output a restriction, the default value for 59 +"typeDep". See \code{\link{allFitnessEffects}}} 60 + 41 61  } 62 + 42 63  \details{ 43 64  This is a simple, heuristic procedure for generating graphs of 44 65  restrictions that seem compatible with published trees in the ... ... @@ -58,7 +79,9 @@ multilevelParent = TRUE, removeDirectIndirect = TRUE, rootName = "Root") 58 79   59 80  } 60 81  \value{ 61 - An adjacency matrix for a directed graph. 82 + An adjacency matrix for a directed graph or a data frame to be used as 83 + input, as "restriction table" in \code{\link{allFitnessEffects}}. 84 + 62 85  } 63 86  \author{Ramon Diaz-Uriarte} 64 87   ... ... @@ -66,6 +89,8 @@ multilevelParent = TRUE, removeDirectIndirect = TRUE, rootName = "Root") 66 89  (a1 <- simOGraph(10)) 67 90  library(graph) ## for simple plotting 68 91  plot(as(a1, "graphNEL")) 92 + 93 +simOGraph(3, geneNames = LETTERS[1:3]) 69 94  } 70 95   71 96  \keyword{ graphs }
 1 1 new file mode 100644 ... ... @@ -0,0 +1,72 @@ 1 +\name{simOGraph} 2 +\alias{simOGraph} 3 +\title{ 4 + Simulate oncogenetic/CBN/XMPN DAGs. 5 +} 6 +\description{ 7 + Simulate DAGs that represent restrictions in the accumulation of mutations. 8 +} 9 +\usage{ 10 +simOGraph(n, h = 4, conjunction = TRUE, nparents = 3, 11 +multilevelParent = TRUE, removeDirectIndirect = TRUE, rootName = "Root") 12 +} 13 + 14 +\arguments{ 15 + \item{n}{ 16 + Number of nodes, or edges, in the graph. Like the number of genes. 17 +} 18 + \item{h}{ 19 + Approximate height of the graph. See details. 20 + } 21 + \item{conjunction}{ 22 + If TRUE, conjunctions (i.e., multiple parents for a node) are allowed. 23 +} 24 +\item{nparents}{ 25 + Maximum number of parents of a node, when \code{conjunction} is TRUE. 26 +} 27 +\item{multilevelParent}{ 28 + Can a node have parents at different heights (i.e., parents that are 29 + at different distance from the root node)? 30 +} 31 + \item{removeDirectIndirect}{ 32 + Ensure that no two nodes are connected both directly (i.e., with an 33 + edge between them) and indirectly, through intermediate nodes. If 34 + TRUE, the direct connections are removed from the graph starting from 35 + the bottom. 36 +} 37 +\item{rootName}{ 38 + The name you want to give the "Root" node. 39 + 40 +} 41 +} 42 +\details{ 43 + This is a simple, heuristic procedure for generating graphs of 44 + restrictions that seem compatible with published trees in the 45 + oncogenetic literature. 46 + 47 + The basic procedure is as follows: nodes (argument \code{n}) are split 48 + into approximately equally sized \code{h} groups, and then each node 49 + from a level is connected to nodes chosen randomly from nodes of the 50 + remaing superior (i.e., closer to the Root) levels. The number of 51 + edges comes from a uniform distribution between 1 and \code{nparents}. 52 + 53 + The actual depth of the graph can be smaller than \code{h} because 54 + nodes from a level might be connected to superior levels skipping 55 + intermediate ones. 56 + 57 + See the vignette for further discussion about arguments.  58 + 59 +} 60 +\value{ 61 + An adjacency matrix for a directed graph. 62 +} 63 +\author{Ramon Diaz-Uriarte} 64 + 65 +\examples{ 66 +(a1 <- simOGraph(10)) 67 +library(graph) ## for simple plotting 68 +plot(as(a1, "graphNEL")) 69 +} 70 + 71 +\keyword{ graphs } 72 +\keyword{ datagen }


text:
# A Bayesian test of the equality of proportions

One problem with a p-value is that it is hard to interpret if you don’t know the sample size.  Andy Gelman talks about this problem on his blog.

Here I’ll contrast the message communicated by a p-value and a Bayesian test by looking at the following three tables:

Table A:  [32 18; 18 32]
Table B: [272 228; 228,272]
Table C: [2570 2430; 2430,2570]

Each of the tables has a Pearson chi-square value in the (7.4, 7.8) range and so each has (approximately) the same p-value.  But, following Gelman’s reasoning, the small p-value for the large sample size in Table C doesn’t have much significance and and the same p-value for Table A (small sample size) is more impressive.
Here is a reasonable Bayesian test of the equality of two proportions.  First, we define a class of priors indexed by the parameter K:
1.   are iid beta()
2.   has a uniform density
Testing H: , A: is equivalent to testing H: against (I’ll talk more about this in class.)
Chapter 8 in BCWR gives an expression for the Bayes factor in support of over .   In the LearnBayes package, suppose the data is a matrix of two columns where the first column contains the counts of successes of the two samples and the second column contains the sample sizes.  Then the Bayes factor (on the log scale) is computed by the single line
s=laplace(bfexch,0,list(data=data,K=1))$int Let’s illustrate using this for the three tables: > laplace(bfexch,0,list(data=cbind(c(32,18),c(50,50)),K=1))$int
[1] 0.9436246
> laplace(bfexch,0,list(data=cbind(c(272,228),c(500,500)),K=1))$int [1] -0.3035413 > laplace(bfexch,0,list(data=cbind(c(2570,2430),c(5000,5000)),K=1))$int
[1] -1.411366
So the Bayes factor against equality of proportions is exp(.94) = 2.56 for Table A, exp(-0.30) = 0.74 for Table B, and exp(-1.41) = 0.24 for Table C.  In contrast to the message communicated by a p-value, the Bayes factor calculation indicates that Table A is the most significant table.


text:
# Medicaid Dataset - Basic Data Analysis of Benefit Summary Data¶

CMS.gov has made available a synthetic dataset of Medicare/Medicaid claims data. The objective is to allow data enterpreneurs to figure out interesting ways to use the data.

As noted in the Data Codebook (PDF), the data has been heavily anonymized and imputed, so any conclusions drawn from this dataset may not be reliable.

In [1]:
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import os
import operator
import random
%matplotlib inline

We read the benefit summary data in. There are 59 files representing benefit summaries from 2008-2010. There are a total of 6,758,744 records. We copy these into a separate benefit_summary directory so all the files can be loaded into a single dataframe.

In [2]:
dfs = []
for csvfile in os.listdir("benefit_summary"):
df = pd.concat(dfs)
df.shape

Out[2]:
(6758685, 32)
In [3]:
# find the distribution of records by gender
df[["BENE_SEX_IDENT_CD"]].groupby("BENE_SEX_IDENT_CD").count()

Out[3]:
BENE_SEX_IDENT_CD
BENE_SEX_IDENT_CD
1 3002984
2 3755701
In [4]:
# find distribution of records by race
df[["BENE_RACE_CD"]].groupby("BENE_RACE_CD").count()

Out[4]:
BENE_RACE_CD
BENE_RACE_CD
1 5596084
2 719751
3 284654
5 158196

So it looks like the beneficiaries are split almost evenly by gender with men constituting about 45% of the dataset and the women constituting the other 55%.

Race-wise, whites constitute 83%, blacks 11%, other (asians, native americans, etc) 4% and hispanics 2%. This roughly reflects the race mix among older Americans.

In [5]:
# visualize incidence of diseases by gender
df_trunc = df[["BENE_SEX_IDENT_CD", "SP_ALZHDMTA", "SP_CHF",
"SP_CHRNKIDN", "SP_CNCR", "SP_COPD", "SP_DEPRESSN", "SP_DIABETES",
"SP_ISCHMCHT", "SP_OSTEOPRS", "SP_RA_OA", "SP_STRKETIA"]]
df_grouped = df_trunc.groupby("BENE_SEX_IDENT_CD").agg(lambda x: 100.0 * np.mean(x - 1))
df_grouped.transpose()

Out[5]:
BENE_SEX_IDENT_CD 1 2
SP_ALZHDMTA 81.597904 79.388801
SP_CHF 71.964619 69.425575
SP_CHRNKIDN 83.974040 82.471981
SP_CNCR 93.506725 93.474401
SP_COPD 87.954048 86.703974
SP_DEPRESSN 80.288973 77.570579
SP_DIABETES 65.798020 62.108698
SP_ISCHMCHT 59.353030 56.210438
SP_OSTEOPRS 84.587930 82.606789
SP_RA_OA 86.827069 85.115562
SP_STRKETIA 96.092187 95.756877

Men lead in the incidence of disease in almost all cases - they show higher incidence of Alzheimer's Disease, CHF, Depression, Diabetes, Ischemic Heart Disease, Osteoporosis and Rheumatoid/Osteo-Arthritis. Men and women seem to have an equal chance of contracting Chronic Kidney Disease, Cancer, COPD, and Stroke. The data is shown visually below:

In [6]:
df_grouped.plot(kind="bar", legend=False)

Out[6]:
<matplotlib.axes.AxesSubplot at 0x1f289bd0>
In [7]:
# visualize incidence of diseases by race
df_trunc = df[["BENE_RACE_CD", "SP_ALZHDMTA", "SP_CHF",
"SP_CHRNKIDN", "SP_CNCR", "SP_COPD", "SP_DEPRESSN", "SP_DIABETES",
"SP_ISCHMCHT", "SP_OSTEOPRS", "SP_RA_OA", "SP_STRKETIA"]]
df_grouped = df_trunc.groupby("BENE_RACE_CD").agg(lambda x: 100.0 * np.mean(x - 1))
df_grouped.transpose()

Out[7]:
BENE_RACE_CD 1 2 3 5
SP_ALZHDMTA 80.010754 81.348689 83.989334 82.127235
SP_CHF 69.962656 72.319316 75.970828 73.681383
SP_CHRNKIDN 82.826670 83.827324 86.614276 84.818200
SP_CNCR 93.244848 94.377639 95.212785 94.970796
SP_COPD 87.006378 87.860107 89.930231 88.671016
SP_DEPRESSN 78.489047 79.644210 81.982688 79.309211
SP_DIABETES 62.998876 66.469237 69.711650 67.132544
SP_ISCHMCHT 56.630261 61.178935 64.912490 62.750638
SP_OSTEOPRS 83.063121 85.223362 86.334287 85.459809
SP_RA_OA 85.466444 87.533744 88.788494 87.581228
SP_STRKETIA 95.832729 95.970690 96.892719 96.422160

As can be seen from the table above, the incidence of various diseases across different races seems to be fairly constant. The only exceptions are CHF which seems to be less prevalent among whites than other races, and Ischemic Heart Disease, which seem t obe more prevalent among whites than other races. The data is shown visually below:

In [8]:
df_grouped.plot(kind="bar", legend=False)

Out[8]:
<matplotlib.axes.AxesSubplot at 0x5c26690>

We now examine observed comorbidities in the population by calculating the correlation between different pairs of diseases. As can be seen from the top 10 pairs below, the correlation between diseases appears to be fairly weak.

In [8]:
colnames = [x for x in df.columns if x.startswith("SP_") and not x.endswith("STATE_CODE")]
colidxs = {x[1]:x[0] for x in enumerate(colnames)}
CM = np.zeros((len(colnames), len(colnames)))
comorbidities = []
for colname1 in colnames:
for colname2 in colnames:
i = colidxs[colname1]
j = colidxs[colname2]
if i == j:
CM[i,j] = 1.0
continue
if i < j:
CM[i,j] = np.corrcoef(df.ix[:, colname1], df.ix[:, colname2])[0,1]
CM[j,i] = CM[i,j]
comorbidities.append((colname1, colname2, CM[i,j]))
continue
sorted(comorbidities, key=operator.itemgetter(2), reverse=True)[0:10]

Out[8]:
[('SP_DIABETES', 'SP_ISCHMCHT', 0.47578541650029821),
('SP_CHF', 'SP_ISCHMCHT', 0.43615577919472531),
('SP_CHF', 'SP_DIABETES', 0.41850270374368082),
('SP_CHRNKIDN', 'SP_DIABETES', 0.39713288341420422),
('SP_CHF', 'SP_CHRNKIDN', 0.38213196506731339),
('SP_CHRNKIDN', 'SP_ISCHMCHT', 0.35058275391195598),
('SP_CHF', 'SP_COPD', 0.33059074013020173),
('SP_DEPRESSN', 'SP_DIABETES', 0.3199180438991816),
('SP_ALZHDMTA', 'SP_DIABETES', 0.31346118720405913),
('SP_CHRNKIDN', 'SP_COPD', 0.31327625784275792)]

The heatmap below summarizes the correlations between different chronic diseases graphically. Lighter colors indicate higher correlation. As expected, the lightest block is (7,8) which corresponds to SP_DIABETES and SP_ISCHMCHT.

In [10]:
fig = plt.figure()
plt.hot()
plt.pcolormesh(CM)
plt.colorbar()

Out[10]:
<matplotlib.colorbar.Colorbar instance at 0x1d8cad40>


text:
# What does a single vertical bar mean in ConditionalExpression? [closed]

I got the condition below as part of a ConditionalExpression. Those single vertical bars before and after $$\frac{1}{k1}$$ appear to be an absolute value but I don't recall seeing Mathematica ouput it like that. Also, I highlighted the character, pressed F1, and the program said that it could be Alternatives, Or, Nand, etc; but I did not see absolute value among the options. Which one is it?

• it is Alternatives. – kglr Feb 18 at 21:50
• @kglr does that mean that at least one of the three equations needs to be a part of the reals for the expression to be true? – Lucas Alanis Feb 18 at 22:01
• Lucas, Element[a|b|c, dom] means all members of {a,b,c} belong to dom. Also, Element[a|b|c, dom] is equivalent to Element[{a,b,c}, dom]. (see: Element>> Details in the docs) – kglr Feb 18 at 22:28


text:
# How Hermite Lattice reduced basis implies LLL reduced basis?

Hermite reduced basis is defined as

A basis $\{b_1,\dots,b_n\}$ is reduced if it satisfies

1. $|\mu_{i,j}| \le \frac{1}{2}$ and

2. $||\pi_i(b_i)|| \le ||\pi_i(b_j)||$ for $1\le i \le j \le n$

where $\pi_i(x)=\sum_{j=i}^{n}\frac{(x \cdot b_j^*)}{b_j^* \cdot b_j^*)}b_j^*$ i.e., component of $x$ orthogonal to $b_1,\dots,b_{i-1}$

Since the algorithm to find Hermite's reduced basis not known to be in polynomial time for varying dimension.

Lenstra $et\;al$ defined the reduced basis and an algorithm to find the reduced basis in polynomial time.

LLL reduced basis is defined as

1. $|\mu_{i,j}| \le \frac{1}{2}$ and

2. $||\pi_i(b_i)|| \le ||\pi_i(b_{i+1})||$

How the second condition of hermite reduced basis implies second condition of Lenstra $et\;al$ reduced basis. Second condition of Lenstra $et\;al$ reduced basis satisfies only some inequalities in second condition of hermite reduced basis. What about the other inequalities? Does other inequalities are satisfied? If not, how does it output nearly orthogonal basis?

• if you set $j=i+1$ to the second condition (of Hermite) then you get the 2nd condition of LLL. – 111 Jan 23 '17 at 22:09
• Hermite rediced basis is nearly orthogonal basis. if $j=i+1$, only some inequalities of hermite second condition is satisfied then what about the remaining inequalities? – preethi Jan 24 '17 at 4:02
• No. All the inequalities will be true. You just borrow the inequalities j=i+1, for i = 1,2,..,n-1, (where n=rank(L)). These inequalities tells you that the Hermite basis is (also) an LLL basis. – 111 Jan 24 '17 at 4:11
• consider, $\{b_1,b_2,b_3,b_4\}$ is the basis. According to hermite second condition $||b_1||^* \le ||\pi_1(b_1)||=||b_1^*||, ||b_1^*|| \le ||\pi_1(b_2)||=||b_2||, ||b_3^*|| \le ||b_3||, ||b_4^*|| \le ||b_4||$. For $i=2$, $||b_2^*||$ must be $\le ||b_3^*+\mu_{3,2}b_2^*|| \; and \; ||b_4^*+\mu_{4,2}b_2^*+\mu_{4,3}b_3^*||$. For $i=3$, $||b_3^*|| \le ||b_4^*+\mu_{4,3}b_3^*||$ where as in lll second condition for $i=1$, $||b_1^*|| \le ||b_2||$, for $i=2$: $||b_2^*|| \le ||b_3^*+\mu_{3,2}b_2^*$ are satisfied and it does not imply the other conditions for $i=1,2$. Please clarify, if I am wrong. – preethi Jan 24 '17 at 6:55

Ignoring the trivial case $j = i$, for which the second condition is automatically satisfied, the conditions for Hermite-reduced bases can be formally written as:

1. For all $1 < i \leq n$ and for all $1 \leq j < i$: $\qquad \quad \quad \ \ |\mu_{i,j}| \le \frac{1}{2}$.

2. For all $1 \leq i < n$ and for all $i + 1 \ {\color{red}\leq} \ j \leq n$: $\ \quad \|\pi_i(b_i)\| \le \|\pi_i(b_j)\|$.

The conditions for LLL-reduced bases can be slightly rewritten as:

1. For all $1 < i \leq n$ and for all $1 \leq j < i$: $\qquad \quad \quad \ \ |\mu_{i,j}| \le \frac{1}{2}$.

2. For all $1 \leq i < n$ and for all $i + 1 \ {\color{red}=} \ j\leq n$: $\ \quad \|\pi_i(b_i)\| \le \|\pi_i(b_j)\|$ .

The only difference in the definitions, highlighted in red, is on the values $j$ for which the second condition must hold; for Hermite-reduced bases it must hold for all $j \in \{i+1, \dots, n\}$ while for LLL-reduced bases it must hold for $j \in \{i + 1\}$ (provided $i + 1 \leq n$). Since $\{i + 1\} \subset \{i+1, \dots, n\}$ this means Hermite-reduction is a stronger notion than LLL-reduction. So Hermite-reduction implies LLL-reduction.

What about the other inequalities? Does other inequalities are satisfied? If not, how does it output nearly orthogonal basis?

For the case $n = 2$, the sets $\{i + 1, \dots, n\}$ and $\{i + 1\}$ are equal for $i = 1$, while for $i = 2 = n$ the second condition does not apply. So for $n = 2$, both notions of reducedness are equivalent. (Many other notions of reducedness also collapse to the same definition in case $n = 2$.)

For $n > 2$, setting $i = 1$ shows that the conditions are not necessarily equivalent. I am not sure whether already for $n = 3$ there are examples of LLL-reduced bases which are not Hermite-reduced, but certainly for larger $n$ there are many such examples - by the second condition, the vector $b_1$ of a Hermite-reduced basis must be a shortest non-zero vector of the lattice, while for LLL-reduced bases the vector $b_1$ is only known to be at most a factor $2^{O(n)}$ longer than a shortest non-zero vector in the lattice. In high dimensions, an LLL-reduced basis will look quite skewed compared to a Hermite-reduced basis, so in that sense it does not really output a "nearly orthogonal basis" - only a "somewhat orthogonal basis".


text:
# hardware engineer Tag

## Valve hardware engineer Ellsworth gets the shaft

Posted by Yolanda Green - 13 Feb 2013

Okay, so, maybe she didn’t really get completely screwed, but we wouldn’t know would we? Because after hardware engineer Jeri Ellsworth tweeted about getting fired, nothing has been said about why.


text:
## mail.app – How to display the number of unread emails in the Mail app in the Mac OS menu bar?

How best to display the number of unread emails in the Mail app on Mac OS? menu bar? (Bonus points, if I can use it to open the mail app.)

I do not really use the dock and got used to apps like Airmail and Fantastical that use the Mac OS menu bar to show information such as: the number of unread emails.

The best thing I could find after a quick search was https://www.macupdate.com/app/mac/22042/mail-unread-menu (from this thread), apparently it was not updated in ~ 6 years and may not work without also installing the MailPluginFix plugin. Is that really the best way to do that?

I use Mojave.

## html5 – ID, where the first character is a number, does not work if I enter css #[número de exemplo]

For example, if I entered the HTML code:

``` texto de teste ```

and I will put in CSS: `#1 {código de teste}`, does not recognize that `id=1`, Even if I set "class" instead of "id", or if I set a different tag or number. Is that a problem with my code? Or is it normal? Why is this happening?

## iCloud – iOS 12.3.2 Messages.app still associates a deleted / outdated phone number with a Contact.app listing: how do you fix the problem?

How do I fix # 4 in the following scenario?

Day 1: Contacts.app Entry X contains mobile phone numbers A and B.

Day 2: Contacts.app entry X contains the mobile number A.

Also on the 2nd day:

1. (good) macOS Contact.app no longer links B to entry X.
2. (good) macOS Messages.app no longer links B to X.
3. (good) iCloud.com Contacts no longer binds B to X.
4. (BAD) iOS 12.3.2 Messages.app still links B to Contacts.app entry X.

To fix # 4, I've tried (several times) to restart my iOS (an iPhone 8), reboot iOS Messages.app and Contacts.app, and even add a new Contacts.app listing with the old phone number (try to "redirect" B to another Contacts.app entry), which reflects everything in # 1, # 2 and # 3 well … but not # 4.

Considerations for the remedy?

I would like avoid Delete iOS Messages.app threads associated with B. And I am not sure if this would also lead to a correction. However, I did not try it because I want to keep the message threads / data / photos.

## Number theory – Find the field extension that corresponds to a subgroup of the Galois group of roots of the unit

Suppose I extend the rationals around all pth roots of the unit, where p is a prime number. The Galois group of this extension would be integers modulo p-1, there is a unique subgroup of index 2, which is generated by 2. I would like to find the corresponding field extension with degree two.

I could do the job if p = 5, but that's easy, since the only nontrivial element of the subgroup of index two is conjugation.

How do I do this task when p gets big, say 71? The generator of the multiplicative group is here 7, so I should look for x so that x ^ 7 = x, I have no idea how to go about it.

## olap – Maximum number of table columns in Clickhouse

I tried to test the bounds and found that for 5K columns in the table, one appears, even if only 2 columns are inserted
Obtained from 127.0.0.1:9000. DB :: Exception: memory limit exceeded (for query): would use 9.31 GiB

Is there a way to deal with an extremely large number of metrics?

## SQL Server – Number of MAX DATE, MIN DATE, and Active Counts

1. GLUSR_USR_ID
2. First meeting date (after each GLUSR ID)
3. Date of the last meeting (after each GLUSR_ID)
4.Total Meeting Count (after each GLUSR ID)
4. Date of the last meeting (after each GLUSR_ID)
5. Total meeting in the last 90 days (after each GLUSR_ID)
6.Total session in the last 180 days (after each GLUSR_ID)
7.Active status in the last 30 days (number of meetings)
I have attached the pictures as a reference

`

```````Select GLUSR_USR_ID,
( select  Count(1) from STS_DSR_SALES@mainr where
STS_DSR_SALES.FK_STS_COMPANY_ID=O.FK_STS_COMPANY_ID)S_COUNT,

(Select MAX(STS_DSR_SALES_DATE)
from STS_DSR_SALES@mainr where STS_DSR_SALES.FK_STS_COMPANY_ID=O.FK_STS_COMPANY_ID)MAX_DATE,

(Select min(STS_DSR_SALES_DATE)
from STS_DSR_SALES@mainr where STS_DSR_SALES.FK_STS_COMPANY_ID=FK_STS_COMPANY_ID)Min_DATE,

(Select count (1) STS_DSR_SALES_DATE from STS_DSR_SALES@mainr
where STS_DSR_SALES.FK_STS_COMPANY_ID= FK_STS_COMPANY_ID and trunc(STS_DSR_SALES_DATE)>SYSDATE-90)Active_90,

( select  Count(1) from STS_DSR_SALES@mainr where STS_DSR_SALES.FK_STS_COMPANY_ID=O.FK_STS_COMPANY_ID)S_COUNT,

(Select MAX(STS_DSR_SALES_DATE)
from STS_DSR_SALES@mainr where STS_DSR_SALES.FK_STS_COMPANY_ID=O.FK_STS_COMPANY_ID)MAX_DATE,

(Select min(STS_DSR_SALES_DATE)
from STS_DSR_SALES@mainr where STS_DSR_SALES.FK_STS_COMPANY_ID=FK_STS_COMPANY_ID)Min_DATE,

(Select count (1) STS_DSR_SALES_DATE from STS_DSR_SALES@mainr
where STS_DSR_SALES.FK_STS_COMPANY_ID= FK_STS_COMPANY_ID and trunc(STS_DSR_SALES_DATE)>SYSDATE-90)Active_90,

(Select count (1) STS_DSR_SALES_DATE from STS_DSR_SALES@mainr
where STS_DSR_SALES.FK_STS_COMPANY_ID= FK_STS_COMPANY_ID and trunc(STS_DSR_SALES_DATE)>SYSDATE-180)Active_180,

(Select Count (1)STS_DSR_SALES_DATE from STS_DSR_SALES@mainr
where STS_DSR_SALES.FK_STS_COMPANY_ID= S.FK_STS_COMPANY_ID and TRUNC(REPORT_DATE)>SYSDATE-30)ACTIVE_30

From
(select GLUSR_USR_ID,fk_sts_company_id,GLUSR_USR_CUSTTYPE_NAME from STS_DSR_SALES@mainr,GLUSR_USR@mainr
where  trunc(sts_dsr_sales_date) between '01-oCT-19' and '31-oCT-19')O,
(Select fk_sts_company_id, REPORT_DATE FROM GLUSR_CLCKSTRM_4HOTLEAD_ARCH@mainr,STS_DSR_SALES@mainr where TRUNC(REPORT_DATE)>SYSDATE-30)S
``````

Note

GLUSR_USR_ID is the employee ID
The total number of meetings can be retrieved with the total number. from (STS_DSR_SALES_DATE),
First meeting is Max Date
Last meeting is a minimum date
The total number of meetings in the last 90 days and 180 days equals the number of meetings in the previous days
active in 30 days is totally no. of the meeting
I get the wrong data because GLUSR_ID is matched by total meeting counts. That's wrong. I would like to format my data from picture 2 and 3 like picture 1.

## Number theory – summation elements in a two-dimensional arithmetic sequence

I have two matrices,

$$A = left ( begin {matrix} 5 & 10 & 15 & cdots \ 17 & 28 & 39 & cdots \ 35 & 52 & 69 & cdots \ vdots & vdots & vdots & ddots end {matrix} right)$$

$$B = left ( begin {matrix} 6 & 13 & 20 & cdots \ 18 & 31 & 44 & cdots \ 36 & 55 & 74 & cdots \ vdots & vdots & vdots & ddots end {matrix} right)$$
From where
begin {align *} a_ {i, j} & = 3i ^ 2 + (6j – 3) i – j \ b_ {i, j} & = 3i ^ 2 + (6j-3) i + (j-1) end {align *}
How to prove that the sum of two elements of $$A$$ and $$B$$ Must be equal to the sum of two numbers, both of which are not elements $$A$$ and $$B$$?

e. G.:

$$a_ {1,1} + b_ {1,1} = 5 + 6 = 11 = 8 + 3$$,both $$8.3$$ are not elements of A and B.
$$a_ {1,1} + b_ {1,2} = 5 + 13 = 18 = 14 + 4$$,both $$14.4$$ are not elements of A and B.

This question, which was asked 5 years ago at MSE, has no answer. That's why I put it here.

## At the moment I can only answer a call on the GM number

I have a Google Voice number associated with my iPhone number. How do I activate the GV number to make calls? At the moment I can only answer a call on the GM number


text:
# Definition:Generated Ring Extension/Evaluation of Polynomial Ring

## Definition

Let $S$ be a commutative rings with unity.

Let $R$ be a subring of $S$ with unity such that the unity of $R$ is the unity of $S$.

That is, $S$ is a ring extension of $R$.

Let $T \subseteq S$ be a subset of $S$.

Let $R \sqbrk {\set {X_t} }$ be the polynomial ring in $T$ variables $X_t$.

Let $\operatorname {ev} : R \sqbrk {\set {X_t} } \to S$ be the evaluation homomorphism associated with the inclusion $T \hookrightarrow S$.

The ring extension $R \sqbrk T$ generated by $T$ is $\map {\operatorname {Img}} {\operatorname {ev}}$, the image of $\operatorname {ev}$.

$T$ is said to be a generator of $R \sqbrk T$.


text:
## A, B and C are partners in a business. Their shares…

A, B and C are partners in a business. Their shares are in the proportion of $\Large\frac{1}{3}: \frac{1}{4}: \frac{1}{5}$ A withdraws half of his capital after 15 months and after…

## A is a active partner and B is a inactive partner..

A is a active partner and B is a inactive partner in business. A puts in Rs. 5000 and B puts in Rs. 6000. A received 15% of the profit…

## A, B and C are three partners in a business…

A, B and C are three partners in a business. The profit share of A is $\Large\frac{3}{16}$ of the total profit and B's share is $\Large\frac{1}{4}$ of the total profit.…

## Four milkmen rented a pasture. A grazed 15 cows..

Four milkmen rented a pasture. A grazed 15 cows for 4 months, B grazed 12 cows for 2 months, C grazed 18 cows for 6 months and D grazed 16…

## Nonad, Vikas and and Manav enter into a partnership..

Nonad, Vikas and and Manav enter into a partnership. Ninad invest some amount at the beginning. Vikas invest double the amount after 6 months and Manav invests thrice the amount…

## Two partners invested Rs. 125000 and Rs. 85000 respectively..

Two partners invested Rs. 125000 and Rs. 85000 respectively in a business. They distribute 60% of the profit equally and decide to distribute the remaining 40% as the interest on…

## A and B enter into partnership. At the end of 9 months..

A and B enter into partnership. At the end of 9 months B withdraws but A's capitals is used for one month more. If they receive profit in the ratio…

## The ratio of investments of two partners X and Y is..

The ratio of investments of two partners X and Y is 11 : 12 and the ratio of their profit is 2 : 3. If X invested the money for…

## Anu is a working partner and Bimla is..

Anu is a working partner and Bimla is a sleeping partner in a business. Anu puts Rs. 5000 and Bimla putes in Rs. 6000. Anu receives 12.5% of the profit…

## A, B and C started a business investing amounts..

A, B and C started a business investing amounts in the ratio of 5 : 6 : 8 respectively. After one year, C withdrew 50% of the amount and A…


text:
# Deterministic Inequalities for Smooth M-estimators

13 Sep 2018Arun Kumar Kuchibhotla

Ever since the proof of asymptotic normality of maximum likelihood estimator by Cramer (1946), it has been understood that a basic technique of the Taylor series expansion suffices for asymptotics of $M$-estimators with smooth/differentiable loss function. Although the Taylor series expansion is a purely deterministic tool, the realization that the asymptotic normality results can also be made deterministic (and so finite sample) received far less attention... (read more)

PDF Abstract

No code implementations yet. Submit your code now


text:
Questions Asked onFebruary 23, 2017

1. Social studies

Which of the following factors was most responsible for an unequal distribution of wealth? A There was an increase in business profits. B Wages were not keeping pace with profits of business owners. C Wages were not keeping pace with profits of business

asked by DAve
2. Science

1. The line on the graph below represents an object that is: A: Moving at a constant speed B: Increasing its speed C: Decreasing it's speed D: Not moving at all 2. To determine the acceleration of an object moving in a straight line, you must calculate the

asked by Reeces
3. Social studies

Which was the most important effect of the Bessemer process? It allowed the production of more steel It reduced better steel It made steel cheaper It allowed factory production of steel•• 2. Which was the immediate goal of the standard Oil Company when

asked by Tills
4. Science 6

during the process of photosynthesis, plants convert carbon dioxide and water into glucose. Covalent bonds hold the glucose molecules together. the energy stored in these covalent bonds is called? A:nuclear energy. B:thermal energy. C:electrical energy.

asked by Jaden
5. Language Arts

The arrow and the song poem 1 i shot an arrow into the air, 2 it fell to earth, i know not where; 3 for, so swiftly it flew, the sight 4 could not follow in its flight Part A Which form best describes the poem this excerpt is from A. lyric poem B. concrete

asked by SugarPie
6. Math. 10 Points.

The diameter of a tire is 2ft A. Find The Circumference of the tire B.About How Mant Times Will The Tire Have To Rotate To Travel One Mile (SHOW YOUR WORK)

asked by Kolton
7. Math

One of the sides of a parallelogram is 4.2 cm and the altitude to that side is 3.6 cm. Find the perimeter of the parallelogram if the altitude to the other side is 2.4 cm.

asked by Sara
8. Mathematics

1. The speed of a current in a river is 6 mph. A ferry operator who works that part of the river is looking to buy a new boat for his business. Every day, his route takes him 22.5 miles each way against the current and back to his dock, and he needs to

asked by Olivia N J
9. History

Hey! Just Want A Quick Check Over My Answers! 1. How Did The Zimmermann Note Lead The United States Closer To War? A. It Caused The United States To End Diplomatic Relations With Germany. * B. It Resulted In More U-Boat Attacks On American Ships. C. It

asked by Emma
10. Math

Need help Given the following values, which point would be considered an outlier? x1 ,2 ,3 ,4 ,5,6, 7 ,8 ,9 y1.2,4.3,2.8,5.2, 6,7.1,7.9,9.4

asked by Whaaaaaaaaaat
11. Chemistry

How much energy (in kj) is required to ionize 2.78 moles of hydrogen atoms the right answer is: 3.65x10^3 kj wondering how they got this answer.

asked by CL
12. economics

. Predicting Consequences Use the table below to predict what would happen if airlines and baseball stadiums priced all seats the same instead of using variable pricing. What would happen to the number of tickets sold? What would happen to the total

asked by Kristy
13. MAth

the two figures below are congruent. Find the measure of the angle that isn't labeled on either figure? Shows a 41, 86, degree on one, and the other one shows a 133 degree.

asked by URGENT HELP PLEASE
14. msth

the two figures below are congruent. Find the measure of the angle that isn't labeled on either figure?

asked by hi
15. Social Studies

In what way did the purchase of Alaska fit with Secretary of State William Seward’s foreign policy toward Asia? A. Seward thought the purchase of Alaska could protect the United States from Asian aggression. B. Seward thought that Alaska could be a

asked by JamesSk8
16. Math

When a class took a math test, 15% of the class failed, 25% made some mistakes (but didn’t fail), and 24 students got perfect scores. How many students were in the class?

asked by Sara
17. Math

What is a reasonable distance between two cities? 200km 200m ** 200cm 200mm

asked by Unknown
18. Trigonometry

A building 200 feet tall casts an 80 ft long shadow. If a person looks down from the top of the building which of the following is the measure of the angle between the end of the shadow and the vertical side of the building to the nearest degree? I

asked by Ben
19. applications of proportion math

Centerville's population decreased from 37,065 to 26,102. How do I find the percent of change?

asked by name
20. Math

I run 1 3/4 miles each day. my friend runs 4 times as far as I do. how far does she run ?

asked by Dee
21. Math

6. Jackson Made A Poster In The Shape of A Quadrilateral. Each pair of opposite sides of the poster are congruent and parallel. Which of the following names best describes the shape of jacksons poster, A. Parallelogram ~~~ B. Rhombus c. Rectangle D.

asked by Kolton
22. Social Studies

2. How did the American Expeditionary Forces help Allies win the war? A. They convinced German troops to rebel against their leaders. B. They had secret talks with the German kaiser, which eventually led to an armistice C. They assisted the French and

asked by JamesSk8
23. math

what is the sum of all proper fractions with denominators less than ten? help me plssss

asked by luisa
24. Social Studies

Which action is often viewed as the most serious attempt to undermine the independence of the judiciary? A President Franklin D. Roosevelt’s plan to reorganize the Supreme Court B appointment of Supreme Court justices to unlimited terms of office C

asked by DAve
25. math

Please check my math answers (and correct?)? I have some math questions, please check them, (they are multi choice, check if my answer is correct. if not, please say which is correct) 1. What is the simplified form of the expression –(10)–1? a -1/10 b

asked by weird equestrian
26. Social Studies

Which of the following best summarizes Hoover’s and Roosevelt’s policies? A. Hoover was most concerned about stabilizing the banks, while Roosevelt chose to provide jobs. B. Hoover believed in providing public works and welfare, while Roosevelt wanted

asked by Anonymous
27. Math

The area of a parallelogram with a side of 5.6 in is equal to the area of a rectangle with sides 7 in and 8 in. Find the altitude to the given side in the parallelogram.

asked by Sara
28. Liberal arts

Which terms and 45p4q have a GCF of 9p3? Check all that apply. *18p3r x27p4q x36p3q6 *63p3 x72p3q6 The ones with the stars next to them are the correct ones and the ones with the x next to them are the wrong ones. Does answer choice A make any sense to any

asked by christal
29. Math

Explain How To Construct A Perpendicular bisector

asked by John
30. Math

In triangle PQR, angle Q= 90 degrees, angle P= 60 degrees and angle R= 30 degrees. PR= 1 unit. Extend side QR to T such that PR= RT. Join PT. Calculate the exact measure of angle T. Determine the exact value of lengths needed to find tan T and then find

asked by Kausar
31. Chemistry

4.72 g of a compound of carbon, hydrogen, and silver was burned in an atmosphere of oxygen, yielding 7.95 g of CO2, 1.02 g of H2O and 3.02 g of a mixture of silver and silver oxide. Because the production of this mixture yielded an indeterminate value for

asked by CL
32. Math

What Is the measure of an angle that is complementary to a 47 degrees angles? A. 43 degrees B 53 degrees~~~ C. 153 Degrees D. 180 Degrees

asked by John
33. Social studies

Which of the following was most likely an effect of the Dust Bowl? A California developed millions of acres of new farmland. B The New Deal provided irrigation for the drought areas. C Oakies started down Route 66 toward possible work. D More of the New

asked by Doge
34. Math

The area of a parallelogram with a side of 5.6 in is equal to the area of a rectangle with sides 7 in and 8 in. Find the altitude to the given side in the parallelogram.

asked by Steve
35. algebra

a ladder is placed 5ft away from a house. the ladder comes up to 12ft on the side of the house. how long is the ladder?

asked by george
36. Social studies

Among the first laws passed by FDR was the Truth-in-Securities Act. How did it support his New Deal goals? A The law’s purpose was to make sure farmers’ investments were safe. B The law’s goal was to prevent another economic crash. C The law was

asked by Herambe
37. english

Which of the following statements describes a functional text? a. It provides a first-person account of a personal experience. b. The primary purpose is to provide information to perform a task. c. The primary purpose is to construct a logical argument. d.

asked by marie
38. Algebra

Use the coordinates of the two points that show male life expectancies for 1980 and 2000 to write a linear function that models life expectancy. E (x), for men born in this community x years after 1960 Coordinates are 1960-66.8 1970-67.5 1980-69.9

asked by Anonymous
39. Physics

a uniform beam 6.0m long and weighing 4kg rest support p and q place left and right 1.0m of beam of weight from each of the beam weight of mass 10kg and 8kg and are placed near p and q respectively on each of the beam. calculate the reaction of p and q

asked by Olalekan
40. Math

How do you write the product as a product of a whole number and a unit fraction of 3×4/5 equals

asked by Dee
41. computer programming

Create a Raptor Flowchart that calculates the amount a person would earn over a period of time if his or her salary were five cents the first day, ten cents the second day, and so on doubling each day. Your program should: 1. Request the number of days. 2.

asked by Morgan
42. Physics

Two forces are applied to a block of mass MM=12.0 kg that sits on a horizontal, frictionless table. One force F⃗ 1F→1 has a magnitude of 10.0 N and is directed at an angle θ1 equal to 37.0° from the xx direction as labeled in the figure below. As a

asked by Neam
43. Math

How many square feet of wrapping paper do you need . To wrap a package it is 3.5 feet long 18 inches wide and 2 feet high

asked by Rose carter
44. math

Find a nth term for this sequence 1/3,1/9,1/15,1/21,1/27..

asked by Damian
45. Math help please help!!

The angle θ lies in Quadrant II . sinθ=34 What is cosθ ? −√7/4 < MY CHOICE √7/4 3/4 −3/4

asked by Emma
46. Physics

a uniform beam 6.0m long and weighing 4kg rest support p and q place left and right 1.0m of beam of weight from each of the beam weight of mass 10kg and 8kg and are placed near p and q respectively on each of the beam. calculate the reaction of p and q

asked by Olalekan
47. physics

A rod 14.0 cm long is uniformly charged and has a total charge of -20.0 µC. Determine the magnitude and direction of the electric field along the axis of the rod at a point 36.0 cm from its center. N/C

asked by momen
48. Biology

What amino acid property makes proteins highly functional? I would assume it would be the structure and sequence, but are there additional properties?

asked by Aaron
49. Science

4.9 gm of H2SO4 is mixed with Water to form 5 litres of aqueous solution. Findits concentration. (Molecular weight of H2SO4 is 98 gm/mole)

asked by Shreyash
50. Precal

If sin (theta) = sqrt5 / 3 and cos (theta) = 2 / 3 which of the following is tan (theta)?

asked by Zack
51. Math

Create a Raptor Flowchart that calculates the amount a person would earn over a period of time if his or her salary were five cents the first day, ten cents the second day, and so on doubling each day. Your program should: 1. Request the number of days. 2.

asked by Morgan
52. Physics

A 77 kg man climbs the stairs to the fifth floor of a building, a total height of 15.2 m. What is his potential energy in Joules when he reaches the fifth floor? Round your answer to 1 decimal place.

asked by Colten
53. physics

A ball moving at a velocity of 10 meters/second has a momentum of 8.0 kilogram meters/second. What is its mass?

asked by Anonymous
54. Math

An angle theta satisfies the relation (csc theta)(cos theta)=-1 Give an example of information needed to determine a unique value for theta If sec theta is known to be negative, what is the csc theta value of theta?

asked by Saniya
55. Physics 202

In a lecture hall you sit 12 m directly in front of one of the two speakers on the front of the hall. The second speaker is 8m from the first in line with the front of the room, so that the speakers and you form a triangle with a 90° angle. What

asked by Alisa
56. High School Geometry

The figures in (a) and (b) below are made up of semicircles and quarter circles; the figure in (c) shows a quarter of a circle in a square. Find the area and the perimeter of each figure in terms of Ï€. since I can't put a URL to the pic I will try to

asked by Alexa
57. chemistry help, urgent!

Which of the following should you add to stabilize the pH of a solution? solute acid

asked by sammy
58. Math

I have to find the area of the trapezoid and the parallelogram by composing into rectangles or decomposing into triangles or shapes as needed. Show your work neatly and completely. The numbers are:18cm, 7 cm, 12cm and 10cm I am not sure how I can do this.

asked by Patrick
59. Maths

A path 3m wide surrounds a rectangular garden 15m wide and 18m long.What is the perimeter ?

asked by Kwadwo
60. math

PLEASE TELL ME THE ANSWER TO "blank 569 divided by 6 is about 400!!!!!!!!" WHAT IS THE BLANK?!!?!?!?

asked by Erika
61. Chemistry

A is a solution of hydrochloric acid containing 3.650g of HCl in 1dm3 of solution. B is a solution of impure sodium carbonate. 25cm3 of B require 22.7cm3 of A for complete reaction. Given that 5.00g of impure B was dissolved in1dm3 solution,what is the

asked by Victor
62. mathematics

The nth term of the sequence 5 8 11...is 383.find n

asked by Marian Awuah
63. math

at noon the temperature is .6.f but the temperature drops 2 degrees per hour for the next few hours?what is the temperature at 4 pm?

asked by lara
64. Science

Which material is the densest air,water,plastic,or iron

asked by John
65. Math

Find the $2 \times 2$ matrix $\bold{A}$ such that $\bold{A} \begin{pmatrix} 1 \\ 0 \end{pmatrix} = \begin{pmatrix} 1 \\ 2 \end{pmatrix}$ and $\bold{A} \begin{pmatrix} 0 \\ 1 \end{pmatrix} = \begin{pmatrix} -7 \\ 4 \end{pmatrix}.$

asked by Zheng
66. Math

Thank you Ms.Sue but how do you work it out?

asked by Dee
67. real estate

Let’s see if you can solve this puzzle. Billy and Elizabeth still work for the same brokerage. Billy is in a meeting with a buyer client in one room, while Elizabeth is in a meeting with the seller client in the next room. Elizabeth’s client is selling

asked by emma
68. math - proportions and ratios

A gardener found that he was able to plant 1/4 of a packet of flower seeds in 1/5 of a garden. At this rate, how much of the garden would he cover with the entire packet of seeds? A) 1/20 B) 4/5 C) 5/4 D) 9/2 I want to know how to set up the problem.

asked by name
69. Chem

Determine the boiling point of a sol'n containing 96.8 g MgBr2 in 2014 g of water.

asked by Ally
70. math

If the areas of three adjacent faces of a cuboid are 8 sq .cm and18 sq.cm and25 sq.cm . Then find the volume of cuboid

asked by sej
71. physics

What is the density of a fuel of relative density 0.72

asked by ogu
72. Chemistry Help

The most effective buffer solutions have equal concentrations of salt and acid (or base). Find the pH of a buffer solution with equimolar concentrations of: (a) HCOOH and NaCOOH (Ka = 3.5 x 10-4 for HCOOH) (b)CH3NH2 and CH3NH3Cl (Kb = 3.7 x 10-4 for

asked by Luke
73. Chemistry

Can geranium be used to detect infrared radiation emitted by a remote control device that has a wavelength of 902 nm? the work function (binding energy) of geranium is 7.61 x10^-19 J?

asked by CL
74. Calculus

An explosion causes debris to rise vertically with an initial velocity of 160 feet per second. In how many seconds does it attain maximum height? i know i need to use the formula: y(t)=-16t^2+Vot + yo Have: vo=160 Yo= is what i am trying to find and i dont

asked by Roger
75. Geometry

Three circles touch one another externally.Their centres form A triangle with sides 10cm,9cm and 7cm.Find the radii of the circles

asked by Gbotty
76. chemistry

already missed question so I just need help figuring out what I did. Small amounts of chlorine gas can be gener- ated in the laboratory from the reaction of manganese(IV) oxide with hydrochloric acid: 4 HCl(aq) + MnO 2 (s) → 2 H 2 O( ℓ ) + MnCl 2 (s) +

asked by Pat
77. Mechanical principles

A car initially at rest experiences uniform acceleration of 5 m/s2 for 6 sec. It maintains constant velocity for 14 sec and is then brought to rest in 5 sec by a uniform retardation. a) Using the formula, find out how far the car has travelled. b) Find the

asked by Bob
78. math

calculate the amount a person would earn over a period of time if his or her salary were a penny the first day, two cents the second day, and so on doubling each day. Day Pay =============== 1 0.01000 2 0.02000 3 0.04000 4 0.08000 5 0.16000 Your total pay

asked by Carlson
79. SS Help, FAST!!!!!

What does this graph suggest about the costs and benefits of balancing the budget? (Graph: Only with spending cuts: 20% Mostly with spending cuts: 30% Equally with spending cuts and higher taxes: 32% Mostly with higher taxes: 7% Only with higher taxes: 3%)

asked by Agala
80. Chemistry

Calculate the ionization energy (in kj) for a mole of hydrogen atoms, making the assumption that ionization is the transition from n=1 the correct answer is : 1.31x10^3 kJ

asked by CL
81. math

For his troops' popcorn fundraiser sale, Mike sold caramel corn for $10, buttered microwave popcorn for$8, and lightly buttered popcorn for $7. By the end of the fundraiser, he had sold 400 items and made$3,272. If he sold twice as many lightly buttered

asked by Rachel
82. English

Choose the correct form of the pronoun in parentheses in each of the following sentences. 1. Two witnesses claimed that the burglar was (him, he). 2. The volunteers must be them,they) 3.Is the last performer (she, her) 4.The next speaker will be (him, he)

asked by HAYDEN
83. Economics

For a monopolist allocating outputs in two different geographical markets Price 1/ P1=15-Q1, P2= 25-2Q2, TC=5+3(Q1+Q2). What are price, output, profits and MR, IF:a. The monopolist can price discriminate? b.The monopolist prohibited to price discriminate?

asked by chala Chiracho
84. history

What was the last christian city conquered by the Muslims.

asked by lynn
85. SS Help!

What does this graph suggest about the costs and benefits of balancing the budget? (Graph: Only with spending cuts: 20% Mostly with spending cuts: 30% Equally with spending cuts and higher taxes: 32% Mostly with higher taxes: 7% Only with higher taxes: 3%)

asked by Agala
86. Social Studies

The first immigrants to the United States were mainly from England, Scotland, Ireland, Germany, and A. Russia B. Italy C. Scandinavia D. Greece I think that the correct answer is C, Scandinavia, please correct me if I am wrong.

asked by I am amazing
87. Math

If a boat was 36' long and i built a model of it 18" long what scale would the model be

asked by Henry
88. Maths

Sum of 4 terms in GP is 312 . Sum of 1st and 4th term is 252. Find the numbers.

asked by Max

please if anyone could help me with this question: 1. A class paid $20 for a cake and$4 per child for one slice of cheese pizza. they paid $140. how many children are in the class? 2. Rajie want to divide 24 peanuts, 64 raisins, and 56 apricots evenly asked by Erika 90. trigonometry What is the single trigonometric function of (Cos 20 degrees) (Cos 30 degrees)-(Sine 20 degress) (Sin 30 degrees) asked by mac 91. Chemistry Determine the concentration for the following solutions 2.0g KOH is dissolved in water to make 200.0 ml of solution asked by Sara 92. Calculus Evaluate the integral. 1/2 integral e^(t/2) (I'm not sure what the 1/2 on the left of the integral symbol means.) asked by Anonymous 93. Geometry Three circles centre A,B and C with radii 4cm, 3cm, 2cm, respectively, touch one another externally.Calculate the lengths of the sides of triangle ABC asked by Gbotty 94. Geometry The circle touches the sides of triangle ABC at X,Y and Z. If BC=11cm, CA=10cm and AB=9cm,find AY and BX asked by Gbotty 95. Business finance Mr. X wants a fridge that cost 12000.He has arrange to borrow to borrow the total purchase price from a finance company at a simple interest rate of 12% .the loan require quarterly payment for a period of 3yrs.if the first payment is due 3months after asked by Ibra 96. Math -3 + n/2 = 9 asked by Kayla 97. Science Do light and sound travel at the same speed through solids, liquids, and gasses? What are the effects of light and sound traveling through different objects? asked by Ana 98. physics The index of refraction of water for a given monochromatic light in water is n=4/3. The wavelength of this light in water is 500nm. a) find the speed of this light in water. b) find the energy of one photon of this light . Does this enerdy change if this asked by vicky 99. Science Calculate the time needed for a net force of 5N to change the velocity of a 10kg mass by 2m asked by Navya 100. Chemistry the lead (II) nitrate in 25.49 ml of a 0.1338M solution reacts with all of the aluminum sulfate in 25.00 ml solution. What is the molar concentration of the aluminum sulfate in the original aluminum sulfate solution? For a question like this how do I find asked by CL 101. math Find the area of the segment cut off by a chord of length 10cm from a circle radius 13 cm. asked by tiara 102. Calcalus A population P is a function of time t that had 5000 when t=0 can be written P(t)= 5000+B(t)-D(t). B(t) is the number of births since t=0 and D(t0 is the number of deaths since t=0. suppose at a given instant B=800 and dB/dt=100, and D=1000 and dD/dt=85. asked by Lauren 103. Math The odds against an event are 48:42 what is the probability that the event will occur? asked by aniya 104. Trigonometry Consider angle C such that sin C= 7/25 Sketch a diagram to represent angle C in standard position if cos C is negative Find the co-ordinates of a point P on the terminal arm of angle C. asked by Saniya 105. MAth Darth Vader is designing a game that costs$20.  The game consists of pulling a colored rock out of a container.  When the rock is Red Darth Vader pays nothing, when the rock is Blue Darth Vader pays $40, and when the rock is White Darth Vader pays$100.

asked by Brianna
106. Math

A school is holding a Fixed Raffle, where only a certain number of raffle tickets can be sold.  The school sold 970 of these tickets for $10 each. One of the tickets will win$2910, two tickets will win $970, and 5 tickets will win$485.   What is the

asked by Brianna
107. Problems in three dimensions

A regular tetrahedron has sides of length s. Show that the surface area, A, of the tetrahedron can be determined using the formula A= square root of 3s^2

asked by Zara
108. Math

5 thousand 22 tens and 9 ones equals what number

asked by Anonymous
109. The Teacher Aide In Special Education Setting

A diagnosis of mental retardation means that a child A. Can't read or write at a functional level B. Needs serious learning support in mental ability and behaviour Please help. My answer is B.

asked by A student
110. SS

what impact did paper have on china? I am doing this for a paper, so can you leave some ideas?

asked by hi
111. Physics

A stone with a mass of 20kg and density of 20,000kg/m3 is immersed in water. Find its weight

asked by Victory
112. MATHS

Find a nth term for this sequence 1//1/3,1/9,1/15,1/21,1/27..

asked by Damian
113. Math

x y -2 -5 0 -1 1 1 2 3 A. Graph the ordered pairs. B. Is the function linear? Explain. C. Write a rule for the ordered pairs in terms of x and y. D. What is the value of y when x = 10?

asked by Anonymous
114. English

What does "your passages have been paid" from On the Pulse of Morning poem mean? "Here, root yourselves beside me. I am that Tree planted by the River, Which will not be moved I, the Rock, I the River, I the Tree I am yours, your passages have been paid."

asked by Acasia
115. Science

CeCl3 is having Ca conntent 12 g/L,If we try to pricipitate Ce2(CO3)by using 1.0M Na2CO3,what is the Ca impurity level in the fianl Ce carbonte and how much pH we have to maintain to control Ca imprurity in the final out put?

asked by Chiranjeevi
116. physics

The index of refraction of water for a given monochromatic light in water is n=4/3. The wavelength of this light in water is 500nm.  a) find the speed of this light in water.  b) find the energy of one photon of this light . Does this energy change if

asked by vicky
117. Chemistry

Calculate the molar mass of a molecular compound if a solution of 6.70 g of the compound in 22.60 g of water boils at 100.78 degrees C (at 760mmHg).

asked by chemwizard
118. math

Dallas was given a discount of 10 percent of the following items: 1/1/4 cartons of exercise books @ sh 42000 per cartons,ten cartons of pens sh 22000 each.How much did he pay all together after the discount of 10 percent? *I need anyone to help me please*

asked by kelvin
119. English

I don't understand this part of On the Pulse of Morning: History, despite its wrenching pain cannot be unlived, but if faced with courage, need not be lived again

asked by Acasia
120. math

Maya has 4 1/2m of ribbon. She uses 1 3/4m to wrap a present and 1/3m to make a bow. How much ribbon is left?

asked by Anonymous

You want to buy furniture which will cost N$20,000. You could take out a personal loan for N$20,000, which would charge you 9% p.a. interest compounded monthly. You also have N$20,000 in an investment account, where you earn interest of 12% p.a. asked by wilhel, 122. math there are 64 seventh graders at a middle school. This is 32% of the students at the school. The sixth graders comprise 38% of the school how many sixth graders attend the middle school asked by Anonymous 123. Math A sphere has a radius of 16 cm and a plane passes thru it at 9 cm below the center, what is the area of the intersection between the plane and the sphere? asked by Jj 124. Engineering Science N4 A box of books has a mass of 46kg and is being towed by a rope which is oriented at 15 degree to the horizontal at a point where it is tied into a knot. If the pulling force is increased until the box begins to slide, determine the box's initial asked by Paul 125. MAth The odds against Rainbow winning the race are 17:5. Brian bets$120 on Rainbow to win and Rainbow does win the race. How much money does Brian win? What was the probability that Rainbow was going to win the race?

asked by Brianna
126. English

What is the simple subject of the sentence? 1. The first ones on the scene were our neighbors and they. ones

asked by Hayden
127. Sequences Math

Find the function rule. X = -2, -1, 0, 1, 2. Y = 9, 4, -1, -6 -11. Help please this is too hard

asked by Zack
128. Calculus

Evaluate the integral: the integral of the cube root of x, dx. a. (3/4)x^(4/3)+C b. (3/2)x^(2/3)+C c. 1/(3x^(2/3))+C d. None of these I got (3x^(4/3)/4)+C. I was wondering if it would be D.

asked by Louis
129. Algebra

Give the interval(s) on which the function f is positive if f is defined as: f(x)=x(5−x)(2x−3)

asked by Anonymous
130. Math

Given: f(X)= 8-4x A. Find f(-2) B. Find x, when f(x)= 8 C. Graph the function. D. State the domain and range of the function. E. Use the graph to find x, when f(x) = 0 . Show details on the graph. F. Use the graph to find f(x)when x = 3. Show details on

asked by Anonymous
131. Algebra

Let f (x)= (x^2 + 3x - 4) and g(x)= (x + 4) a. Find f*g and state the domain b. Find f/g and state the domain

asked by Anonymous
132. maths

How many bacteria will there be in 4 second if there is 1 bacteria in 0 second,2 bacteria in 1 second and 4 bacteria in 2 seconds

asked by sino
133. math

the formula for the perimeter of a rectangle is 2l+2w, where l is the length and w is the width. How can you use distributive property to write an equivalent expression for 2l+2w?

asked by haily
134. math

why do people have weight of 100 pounds

asked by davon
135. math

Find the cost of buying 4 dozen of exercise books at sh 6000 per dozen,a half dozen of pencil at sh 2050 per dozen,5 dozen rulers at sh 3600 per dozen #i need anyone to help me please# and in case someone has such type of questions,i am kindly need for

asked by kelvin
136. physics

1. A cylinder tank is 30m deep,calculate the pressure extended at the bottom of the tank,when it is four-fifth filled with water (g=10mg-2,density of water =1000kgm-2) 2.a sample of air weighing 1.32*10^2N is confined in a room measuring

asked by ogu
137. CIVIC EDUCATION

WHAT ARE THE EXTERNAL LIMITAION OF HUMAN RITGH

asked by ANAS
138. math

Suppose an athlete earns \$3,600,000 for endorsing a few different products. If 2/3 of the earnings are for endorsing clothing, how many dollars does the athlete earn for endorsing clothing?

asked by Kurbria
139. Algebra

I am having trouble with these 2 questions. 1. 3x+7=-15 2. -2x-6=+12

asked by Canda
140. Ethics

The World Medical Association (WMA) states that FGM does not violate the principles of medical ethics, if FGM is part of the cultural tradition where the physician is practicing medicine. True False I say false

asked by Anonymous
141. SS Money Help....

What are 4-10 (or More) pros and cons Of Spending Cuts and Taxes?

asked by Agala
142. Social Studies

1750 BC–AD 200 how did paper impact people in ancient times.

asked by URGENT HELP
143. Physics

The lecturer with a monotone voice of 440 Hz and you are both 2m away from the long, smooth and tall wall. You will hear sound that comes directly to you from the lecturer along with sound that comes back from the wall on it’s way to reaching you. You

asked by kailey
144. Physics

A box (mass=34kg) is set on an incline (angle=36.5 degrees), attached to a string. The box is let go slowly with a tension of 205N on the string, and starts sliding down with an acceleration of 0.12m/s^2. What was the coefficient of kinetic friction

asked by Stephanie
145. Math ; Algebra

What is x for the following questions? -2x-6=-12 3x+7=-15

asked by Candence
146. website help(jiskha)

I submitted a link where do i go to see if it got answer i really need help on this thing

asked by Jakis
147. math

there were 825 pupils in a school. 52 percent were boys. more boys joined the school and the percentage of boys became 64 percent of the new total. how many boys joined the school?

asked by peter
148. Algebra

Factor each completely; 3n^2+21n 6n^2+18n not quite sure how to factor completely on problems with that format.

asked by Clove
149. math

the sum of two numbers is 20.one number is 3 time the other number . find the two numbers?

asked by Jo
150. math

-8x 20 is a tangent to f(x) x^3 x^2 bx 18 at x=1 calculate the values of a and b I tried the question but I failed

asked by Emily
151. chemistry

how can i determine via infrared spectrum whether the alcohol that was oxidized was primary or secondary? i did a lab experiment in which we oxidized a diol with bleach and i need to figure out which -OH group was oxidized into a C=O. What are the signs of

asked by Alexa
152. SS Help...

What are 4-10 (or More) pros and cons Of Spending Cut? PLZ Just Give Me A Few Suggestions, PLZ!

asked by Agala
153. math

f(x)=ax^3+bx^2+cx+d and f(0)=-18 determine the equation of f

asked by john
154. biology

If you were testing a reflex on your knee, why would that be slower than a conscious reflex (like if someone told you to grab something right when it falls) in your brain?

asked by homework
155. Geometry

A circle is drawn inside a triangle ABC to touch the sides BC,CA and AB at P,Q and R respectively.if A=56° and B=68°, find the angles of triangle PQR

asked by Gbotty
156. Math - Derivatives

Find the nth derivative of y=2x/(1-x^2) (Hint: Consider -[(1/(x-1))+(1/(x+1))].)

asked by Anonymous
157. Chemistry

what is the minimum uncertainty in the position of an electron moving at a speed of 4 x 10^6 m/s ± 1 %? I keep getting 1.44 x10^-11 m, but the right answer is 1x10^-9 m.

asked by CL
158. English

I'm asking many questions about the same poem "On the Pulse of Morning" because I have no thought on what it means stanza by stanza. Can someone explain it to me? I also don't understand this part: Take it into the palms of your hands. Mold it into the

asked by Acasia
159. Maths

The the cost of a plate is 4 times the cost of a cup write a linear equation in two variables to represent the statement

asked by Tejaswini khole
160. Math

There were 3 similar metal balls in the tank.if the 3 metal balls were out,the water in the tank would drop from 15 cm to 6 cm.find the volume of each metal ball.

asked by Peachie
161. Math

A die is thrown 240 times. What is the probability of getting fifty 2s. plss I have been stuck on this

asked by Favour
162. Math

How would I start both of these questions not sure. If h(x)=1/(x+3)^3 then determine a. f(x) and g(x) such that h(x)=(f of g)(x). b. r(x) and s(x)different from f(x) and g(x)such that h(x)=(r of s)(x)

asked by Mekhia
163. Chemistry

When 25g of ice lose 2092 J of heat at 0 degrees Celsius, what will be the new temperature of the ice? Calorimetry problem

asked by Evelin
164. Math

Consider the sequence t1=1, t2=-1, and that tn-tn-2(n-3)/(n-1), where n>2. Find the value of t1998. (1998 is the term, so is n, t1 and t2)

asked by Anonymous


text:
## § Normal operators: Decomposition into Hermitian operators

Given a normal operator $A$, we can always decompose it $A = B + iC$ where $B = B^{\dagger}$, $C = C^\dagger$, and $[B, C] = 0$. This means that we can define 'complex measurements' using a normal operator, because a normal operator has full complex spectrum. Since we can always decompose such an operator $A$ into two hermitian operators $B, C$ that commute, we can diagonalize $B, C$ simultaneously and thereby measure $B, C$ simultaneously. So extending to "complex measurements" gives us no more power than staying at "real measurements"

#### § Decomposing a normal operator

Assume we have a normal operator $A$. Write the operator in its eigenbasis $\{ |a_k \rangle \}$. This will allow us to write $A = \sum_k |a_k \rangle \langle a_k|$. with each $a_k = b_k + i c_k$. Now write this as:
\begin{aligned} & A = \sum_k (b_k + i c_k)|a_k \rangle \langle a_k| \\ & A = \sum_k b_k |a_k \rangle \langle a_k| + i c_k |a_k \rangle \langle a_k| \\ & A = B + iC \\ \end{aligned}
$B, C$ are simultaneously diagonalizable in the eigenbasis $\{ |a_k \rangle \}$ and hence $[B, C] = 0$.


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## In Nature this week

### April 13, 2007

1. Obituary to Knut Schmidt-Nielsen: McNeill Alexander recalls the man and his work; in the process he summarises the many important discoveries made by Schmidt-Nielsen:
• Kangaroo rats minimise water loss by producing very concentrated urine, cooling the air that they exhale in the nasal cavity, which was cooled in the first place while inhaling, and living in burrows during day and venturing out only at night;
• in contrast to kangaroo rats, dogs breathe in through the nose and breathe out through the mouth; thus, they let water vapour to evaporate helping them lose the extra heat generated by exercise;
• camels avoid water loss by increasing their body temperature as the day progresses, and by drying the air that they exhale using the hygroscopic surfaces of their nasal cavities;
• sea birds which drink sea water secrete droplets of concentrated salt solutions in their nostrils and shed them by the shake of their heads;
• unlike mammalian lungs, in the lungs of birds the air-flow is one-way–it enters at one end and leaves another, and the counter current flow of blood and air helps in high rate of oxygen absorption in the blood to power their flight;
• for a given body mass, swimming is cheaper than flight which is cheaper than running.
2. Amazing indeed!

3. Bending crystals by light: Michael McBride, in a news and views piece, writes about the recent experiments of Kobatake et al to use light induced chemical transformation to bend crystals–reversibly, so that they can be bent cyclically:

The authors grew crystal needles (about 200 $\mu$m long and 5 $\mu$m in diameter) by sublimation so as to be attached at one end to a microscope slide. When illuminated from the side by an ultraviolet laser pulse, the needles bent within a millisecond, displacing the free end by 50 $\mu$m. As a dramatic demonstration of this effect, the needles can launch a tiny gold sphere as if it were a tennis ball…The reversibility of this movement is particularly noteworthy — the needles can undergo 80 cycles of photochemical bending and straightening with no apparent damage to the crystal integrity, nor any diminution in displacement amplitude.

You can see the movies of the crystal moving gold balls as well as other light induced mechanical movement at the supplementary information page. Wow! is all I can say.

4. The quantum mechanical basis of photosynthesis: Roseanne Sension, in a News and Views piece, while commenting on the mapping of electronic states using two-dimensional Fourier transform spectroscopy in Fenna–Matthews–Olsen bacteriochlorophyll complex by Engel et al, indicates how energy transfer during photosynthesis is inherently quantum mechanical; she further feels that this discovery might be the key to designing artificial solar energy harvest systems. Considering the fact that

In higher plants and certain bacterial systems, the initial steps of natural photosynthesis harness light energy with an efficiency of 95% or more,

this certainly is a very important piece of information to have.

Have fun!

## Wobbling plate, Feynman and computer simulations

### April 1, 2007

Title: Feynman’s wobbling plate

Authors: Slavomir Tuleja, Boris Gazovic, Alexander Tomori and Jozef Hanc

Source: American Journal of Physics, Vol. 75, No. 3, pp. 240–244, March 2007

Abstract: In the book Surely You Are Joking,Mr. Feynman! Richard Feynman tells a story of a Cornell cafeteria plate being tossed into the air. As the plate spun, it wobbled. Feynman noticed a relation between the two motions. He solved the motion of the plate by using the Lagrangian approach. This solution didn’t satisfy him. He wanted to understand the motion of the plate by analyzing the motion of its individual particles and the forces acting on them. He was successful, but he didn’t tell us how he did it. We provide an elementary explanation for the two-to-one ratio of wobble to spin frequencies, based on an analysis of the motion of the particles and the forces acting on them. We also demonstrate the power of numerical simulation and computer animation to provide insight into a physical phenomenon and guidance on how to do the analysis.

Internet resources: Java applets and supplementary information


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How To Find Volume Of A Cube With Side Length. Since we know the volume already, we can reverse the. Apply cube function to the length to check volume.

Get the cube side length. The means to compute the volume of a shape utilizing the side length are, step 1: The only issue is how to calculate the area of the small piece.

### Volume Of Cube Using Edge Length.

V is the volume of a cube. Substitute the side length s with the measured value, in this example lets use a side length of 4. Add your answer and earn points.

### To Find The Volume Of A Cube From Its Surface Area, First Use The Formula For Surface Area To Find The Length Of One Side Of Your Cube.

Or any side cubed (s^3), since they are all the same. For example, in the given cube {eq}\overline {ab} = a {/eq}. Note the estimation of the side length of the shape.

### Due To Symmetry, You Can Restrict Your Calculations To One Quadrant.

The volume of the cube can be calculated using the expression, $$v =a^3$$. S = cbrt (v) where: Take the area of the piece outside the circle, multiply by the height of the cube, and by 4 (you have 4 identical pieces), and you get the volume.

### The Means To Compute The Volume Of A Shape Utilizing The Side Length Are, Step 1:

Suppose, the length of the edges of the cube is ‘a’. So, the volume of the cube formula is: How to find volume of a cube 2022.

Categories: how to make


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A doubt in gravitation

Dale
Mentor
2020 Award
I tried to think of a practical example of applying GPE where it could actually help to use anything other than Infinity - except for the obvious ones where we are starting off from earth and falling back again.
I think that the obvious example is a fine one. If you can do it in the obvious case, then you obviously can do it. Also, the obvious case you mention answers the OP's question since it would set the potential to 0 at the surface where the field is non-zero.

Also, you wouldn't necessarily use the mgh approximation, e.g. in launching a satellite or ICBM.

That could be why I come out in spots at the mention of gravitons - except when the person who introduces them is a BRAIN.
I agree. Gravitons are completely irrelevant to this discussion.

sophiecentaur
Gold Member
2020 Award
One other thing in favour of defining GPE relative to Infinity, of course, is the universality of it. We could have an excellent gravitational conversation with the scientists on the planet Zog, ten light years away and we'd all be talking the same language. We'd show them Hydrogen lines and a few other common phenomena to get our units agreeing and scaled up, then we would all know what we meant. The dimensions of the third rock from the Sun would probably not interest them very much, scientifically.
Not that it is a likely scenario for some while. Get a move on please, SETI..

I suppose we are all in agreement that the measurement of gravitational potential energy at the center earth as zero, assuming a reference of zero potential at an infinite distance form the earth.

OMG, what the heck was I thinking! Of course the logical location to assign zero potential gravity is at the surface of the earth and a maximum at infinity.

I became extremely flustered when Darwin flipped the Bozo switch on me, but that is just an excuse. I promised to say I am wrong when I am wrong, and brother was I wrong. Profuse apologies to all.

Until Gravitons have actually been found, it might be as well not to use them in discussions about well established gravity matters.

there is no self-consistent quantization of Gravity. That means, we have no reason to assume there is such a thing as a graviton.

Excellent, no gravitons.

our best non-classical description of gravity is GR, which doesn't have such a thing as gravitational field.

Wait a minute. Then what is meant by Einstein field equations of Einstein’s General Theory of Relativity?

From the Wikipedia article on the stress energy tensor.

"The stress–energy tensor is the source of the gravitational field in the Einstein field equations of general relativity, just as mass density is the source of such a field in Newtonian gravity."

Nugatory
Mentor
Wait a minute. Then what is meant by Einstein field equations of Einstein’s General Theory of Relativity?

From the Wikipedia article on the stress energy tensor.

"The stress–energy tensor is the source of the gravitational field in the Einstein field equations of general relativity, just as mass density is the source of such a field in Newtonian gravity."

That's wikipedia being a bit sloppy. It's not really "just as"; and MTW's position (that there are multiple mathematical objects involved in the description of gravitational effects, no one of which is so uniquely important as to be called "the" gravitational field) is generally clearer.

A.T.
MTW's position (that there are multiple mathematical objects involved in the description of gravitational effects, no one of which is so uniquely important as to be called "the" gravitational field) is generally clearer.
Wouldn't the metric describing space-time geometry qualify as "the gravitational field of GR"?

Dale
Mentor
2020 Award
Wouldn't the metric describing space-time geometry qualify as "the gravitational field of GR"?
Well, the metric doesn't really reduce to the Newtonian gravity field AFAIK.

I tend to think of the Christoffel symbols as being the most closely related to the Newtonian gravity field.

K^2
I tend to think of the Christoffel symbols as being the most closely related to the Newtonian gravity field.
But still, not really. Because I can take polar representation of Minkowski metric, which is flat and has no gravity, of course, modify it to be rotating at some angular velocity Ω, and now the Christoffel symbols represent centrifugal and Coriolis effects.

So Christoffel symbols are really whatever fictitious forces you happen to have. If you have curved space-time, then that includes gravity. But it still doesn't reduce to just gravity.

Dale
Mentor
2020 Award
So Christoffel symbols are really whatever fictitious forces you happen to have. If you have curved space-time, then that includes gravity. But it still doesn't reduce to just gravity.
Yes, but I personally think that including other fictitious forces in gravity is more or less justified by the equivalence principle. However, since there isn't general agreement on the topic and since my justification is admittedly pretty sketchy I certainly don't push my viewpoint.

That's wikipedia being a bit sloppy. It's not really "just as"; and MTW's position (that there are multiple mathematical objects involved in the description of gravitational effects, no one of which is so uniquely important as to be called "the" gravitational field) is generally clearer.

I agree with what you with what you are saying; that what has been called the gravitational field is not exactly the same sense as the electromagnetic, weak, and strong fields.

I have learned now, thanks to this forum, that there is no mediator of the "gravitational field", but still, doesn’t it seem useful to have a term for describing the intensity of gravitation? Would it be acceptable to speak of a “gravitational field” when referring to the values as given by the stress-energy tensor equations?

BruceW
Homework Helper
Nugatory has explained it very well. When wikipedia says: "The stress–energy tensor is the source of the gravitational field in the Einstein field equations of general relativity, just as mass density is the source of such a field in Newtonian gravity." This is only a loose analogy. The two relationships are not meant to be taken as literally identical.

Edit: Also, on this page: http://en.wikipedia.org/wiki/Einstein_field_equations They give a derivation of Newton's law of gravity from Einstein's field equations, under several limiting assumptions. So from looking at this derivation, you can see in what sense the stress-energy tensor in general relativity and the mass density in Newtonian gravity are similar.

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Yes, but I personally think that including other fictitious forces in gravity is more or less justified by the equivalence principle. However, since there isn't general agreement on the topic and since my justification is admittedly pretty sketchy I certainly don't push my viewpoint.

Hmm, I don't know much about Christofel symbols, but I was under the impression that fictitious forces in gravity are justified by the equivalence principle.

You say there isn't general agreement on this, so it would be interesting if you could please provide some references to those arguments.

Dale
Mentor
2020 Award
Hmm, I don't know much about Christofel symbols, but I was under the impression that fictitious forces in gravity are justified by the equivalence principle.
If you have a curvilinear coordinate system and you parallel transport a vector then its components will change, not due to any change in the vector itself, but due to the curving of the coordinates. The Christoffel symbols capture that effect.

You say there isn't general agreement on this, so it would be interesting if you could please provide some references to those arguments.
I think that MTW gives a good overview in "Gravitation". You should start around p 460-470 or so. Here is an online source: http://arxiv.org/abs/physics/0204044

Thanks Dale.


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# Data Science – 3 Key Aspects of Applying KMeans Algorithm for Clustering Tasks

This article represents key concepts around KMeans algorithm including key aspects and formula/R command when you are working on clustering tasks. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos.

• Key aspects of applying KMeans algorithm
• KMeans Algorithm – R Command

###### Key aspects of applying KMeans Algorithm

Key aspects of applying KMeans algorithm are following:

• Selecting a right combination of features set: On the data set on which you may observe some of the following:
• There are one or more features having non-numeric or character data sets. As KMeans requires a data frame containing only numeric data, the challenge is to define a numeric representation of character related features or exclude character-related features from analysis.
• There are one or more features having missing data. There are different techniques one use to take care of missing data. In case of numeric feature set, one may use technique such as finding means (sometimes using aggregate function) and assigning the missing values with mean. In case, the feature has nominal data, one could use dummy coding technique to come up with new set of variables.

Thus, it may so happen that you may use only a select set fo features from a given data set and do the analysis on those features set.

• Other key aspect which is common across different algorithm is to apply normalization to data set. One could use either min-max normalization or z-score standardization technique to achieve data normalization. Following is example representing scaling of data in the data frame, someDF. Pay attention to scale() function.
someDF_z <- as.data.frame(lapply(someDF, scale))

• Selecting an optimum number of clusters: Selecting an optimum of clusters (represents K) is the key. There are different perspectives around this and I shall talk about it in another blog.

###### KMeans Algorithm – R Commands

There is a kmeans() function in stats package in R. Note that stats package is included by default in R installation. If it is not there, you may want to install this package.
Following is the formulae:

# KMeans function applied on some data frame, someDF, where only a
# set of features having numeric values were selected; Notice 4:9
kmeansDF <- kmeans(someDF[4:9], 5)


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# Reducible curves on a surface

Suppose you have a surface (of general type if it helps), and it's embedded in a 3-fold. Naively, the intersection of divisors on the 3 fold and the surface, will be a divisor (a curve) in a surface. I want to know whether this curve is reducible or not, and if it is, then how should I write it in terms of the reducible ones on the surface.

Does anyone can help me to find some reference for it? Usually the textbooks assume that we have reduced irreducible curve, but they don't say how to check that in general. Is there any criterion for that in terms of intersection numbers etc?

Thanks very much. Mohsen

• I assume everything is smooth and projective (the latter is not absolutely necessary). If $X\subset Y$ are the surface and threefold and $H$ is a divisor on $Y$, then, $H\cdot X$ can be written as $\sum_{i=1}^r n_iD_i$, where $D_i$s are irreducible curves on $X$ and $n_i\in\mathbb{Z}$. For the latter question, search for Bertini's theorems- intersection numbers do not guarantee irreducibility. – Mohan Nov 1 '16 at 22:39
• Thanks Mohan, actually my question is about the $n_i$s and $r$ and the intersection number between the irreducible curves. Bertini's theorem tells me (if I'm right) that if $H$ is amble the $H\cdot X$ is irreducible, what if it's not irreducible? Are there anything else to give more information? – Mohsen Karkheiran Nov 1 '16 at 23:52
• No, Bertini does not say what you say. If $H$ is `general' then $H\cdot X$ is irreducible. If it is not irreducible (if $H$ is not general), then the intersection can be complicated, so it depends on what you want to get. Both $n_i,r$ can be as large in general as is allowed. – Mohan Nov 2 '16 at 1:14