With President Trump's Monday night speech, prospects for ending the Afghanistan war anytime soon have vanished. Whether that bodes well for U.S. national security is another matter.
Nearly 16 years after U.S. forces first entered Afghanistan, there they remain. Success, narrowly defined as creating Afghan institutions capable of preventing that nation from once more becoming a haven for terrorists, has proved elusive. Among those noting that absence of success was Trump himself. Prior to becoming president, he denounced the war as a "terrible mistake," a "total disaster," and a "complete waste." In 2013, he tweeted that "We should leave Afghanistan immediately."
Now in the most important foreign policy decision of his presidency so far, he has chosen to perpetuate and to expand the war. Acknowledging that Americans are "weary of war without victory," Trump promised to press on. "In the end," he insisted, "we will win." His commitment to that goal is unambiguous, even if his strategy for achieving it is devoid of specifics. Yet from this point forward, blaming President Obama for whatever happens in Kabul or Kandahar or the Hindu Kush won't work. Afghanistan is Trump's war now.
Furthermore, given the president's pronounced aversion to admitting error, his embrace of the Afghanistan conflict is almost certainly irreversible. Apparently, he will support a request from his field commander to send a few thousand additional U.S. troops into battle. Yet barring the prospect that a handful of reinforcements will suddenly turn the tide and "win"— an outcome that at this point only the naïve or the gullible will expect — America's war in Afghanistan is almost certain to continue for the duration of Trump's presidency. He will bequeath to his successor a conflict that is already the longest in our nation's history.
From this point forward, blaming President Obama for whatever happens in Kabul or Kandahar or the Hindu Kush won't work.
Trump's supporters will likely applaud his move. So too will the foreign policy establishment he once ridiculed. The establishment's success in turning Trump around on Afghanistan has implications that go far beyond that particular country.
At least implicitly, Trump now endorses the twin assumptions that since 9/11 have formed the basis for the larger war on terrorism: First, that sustained U.S. military action provides the most effective means of defeating terrorism; second, that the physical presence of U.S. forces in vulnerable Muslim-majority countries provides a means to render them inhospitable to terrorist entities.
In short, if we keep killing bad guys and persist in nation-building (an effort Trump derides at the same time he implicitly endorses it), the problem will eventually solve itself.
Little evidence exists to support those propositions. Indeed, the post-9/11 U.S. military experience not only in Afghanistan but also in Iraq and elsewhere points to precisely the opposite conclusion: The principal effect of the ongoing war on terrorism has been to exacerbate the problem that it purports to solve. The entire enterprise has been what Trump once understood it to be: a terrible mistake, a total disaster and a complete waste. Now, in effect, he has recanted.
A decision to stay the course in Afghanistan tells us nothing about what Trump may do next week or next month with regard to China or North Korea or Russia, not to mention truly momentous matters such as the threat posed by climate change. He remains utterly unpredictable. Yet his decision on Afghanistan does tell us one thing: Trump has abandoned what once ostensibly formed the foundation of his presidency — a commitment to "America first."
Whoever or whatever benefits by prolonging the war in Afghanistan, it certainly won't be the United States.
Andrew J. Bacevich is the author of "America's War for the Greater Middle East: A Military History."


text:
Dow Jones Newswires: IEA cuts demand forecast and says reserve release will help counter loss of Russian supplies
April 13, 2022 52 views0
By Will Horner
A move by the U.S. and its allies to release oil from their reserves should help counter the loss of Russia's vast supplies after its invasion of Ukraine, and should help ease an energy crisis that has sent oil prices rising, the International Energy Agency said Wednesday.
The IEA, which earlier this month helped coordinate the collective stock releases, said the move would help prevent supplies of crude from falling significantly behind demand, which has rebounded at a fast clip as pandemic-related lockdowns in most of the world have eased.
Steady increases in monthly oil output from members of the Organization of the Petroleum Exporting Countries and their allies–which include Russia–as well as weaker demand in China, due to a resurgence of Covid-19 cases there, would also contribute to easing the long-brewing supply crunch made worse by the outbreak of war in Ukraine, the IEA said.
The IEA cut its demand forecast for the year by 260,000 barrels a day due to a lockdown in Shanghai that has shut off the city of 25 million people. The Paris-based agency now expects total demand for the year to stand at 99.4 million barrels a day.
The IEA also cut its forecasts for supply as oil releases from its members are expected to temper the loss of Russian crude oil, which has been left stranded by Western sanctions and moves by banks, shipping firms and Western oil companies to shun Russian cargoes.
The total oil supply for the year is forecast at 99.3 million barrels a day, around 200,000 barrels a day less than was expected a month ago, the IEA said.
Up to 3 million barrels a day of Russian oil could be lost to global markets by next month as the country's oil companies–facing a dearth of customers and steep discounts for the oil they pump–shut in wells.
Write to Will Horner at william.horner@wsj.com
ETH/USD: Nervous Sentiment Swirls as Dangerous Range Builds – 13 April 2022
SHIB/USD: Price Range Rocked by Wild Speculative Volatility – 13 April 2022

redpajama_set_name: RedPajamaCommonCrawl


text:
{-
HAAP: Haskell Automated Assessment Platform

This module provides the @GHCJS@ plugin runs the _ghcjs_ Haskell-to-JavaScript compiler.

-}

{-# LANGUAGE EmptyDataDecls, TypeOperators, GeneralizedNewtypeDeriving, TypeFamilies, UndecidableInstances, FlexibleContexts, MultiParamTypeClasses, FlexibleInstances #-}

module HAAP.Compiler.GHCJS where

import HAAP.Core
import HAAP.Plugin
import HAAP.Shelly
import HAAP.IO
import HAAP.Web.Hakyll
import HAAP.Pretty
import HAAP.Log
import HAAP.Utils

import Data.Default
import Data.Proxy
import Data.String

import Control.Monad.Reader as Reader
import Control.Exception.Safe
import Control.Monad.Base
import qualified Control.Monad.Catch as E
import Control.Monad.Trans.Control
import Control.Monad.Trans.Compose
import Control.Monad.Morph

import Shelly (Sh(..))
import qualified Shelly as Sh

import System.FilePath
import System.Directory
import System.Process

import GHC.Stack

data GHCJS

instance HaapPlugin GHCJS where
    type PluginI GHCJS = GHCJSArgs
    type PluginT GHCJS = ReaderT GHCJSArgs
    type PluginO GHCJS = ()
    type PluginK GHCJS t m = (MonadIO m)

    usePlugin getArgs m = do
        args <- getArgs
        x <- mapHaapMonad (flip Reader.runReaderT args . getComposeT) m
        return (x,())

data GHCJSArgs = GHCJSArgs
    { ghcjsSafe :: Bool -- compile with the -XSafe extension
    , ghcjsArgs :: [String] -- additional flags
    , ghcjsIO :: IOArgs
    , ghcjsMake :: Bool -- --make flag
    }

instance Default GHCJSArgs where
    def = GHCJSArgs True [] def False

instance (HaapMonad m) => HasPlugin GHCJS (ReaderT GHCJSArgs) m where
    liftPlugin = id
instance (HaapStack t2 m) => HasPlugin GHCJS (ComposeT (ReaderT GHCJSArgs) t2) m where
    liftPlugin m = ComposeT $ hoist' lift m

useShGhcjs :: (HaapStack t Sh) => GHCJSArgs -> [FilePath] -> Haap t Sh IOResult
useShGhcjs args ins = usePlugin_ (return args) (shGhcjs ins)

shGhcjs :: (HasPlugin GHCJS t Sh) => [FilePath] -> Haap t Sh IOResult
shGhcjs ins = do
    args <- liftPluginProxy (Proxy::Proxy GHCJS) $ Reader.ask
    liftSh $ shGhcjsWith args ins

shGhcjsWith :: GHCJSArgs -> [FilePath] -> Sh IOResult
shGhcjsWith ghc ins = shCommandWith (ghcjsIO ghc) "ghcjs" $ addArgs (ghcjsArgs ghc) $ addSafe (ghcjsSafe ghc) $ addMake $ ins
    where
    addSafe True cmds = "-XSafe" : cmds
    addSafe False cmds = cmds
    addArgs xs ys = ys ++ xs
    addMake cmds = if ghcjsMake ghc then "--make":cmds else cmds

useIoGhcjs :: (HaapStack t m,MonadIO m) => GHCJSArgs -> [FilePath] -> Haap t m IOResult
useIoGhcjs args ins = usePlugin_ (return args) (ioGhcjs ins)

ioGhcjs :: (MonadIO m,HasPlugin GHCJS t m) => [FilePath] -> Haap t m IOResult
ioGhcjs ins = do
    args <- liftPluginProxy (Proxy::Proxy GHCJS) $ Reader.ask
    lift $ liftIO $ ioGhcjsWith args ins

ioGhcjsWith :: GHCJSArgs -> [FilePath] -> IO IOResult
ioGhcjsWith ghc ins = do
    ioCommandWith (ghcjsIO ghc) "ghcjs" (addArgs (ghcjsArgs ghc) $ addSafe (ghcjsSafe ghc) ins)
  where
    addSafe True cmds = "-XSafe" : cmds
    addSafe False cmds = cmds
    addArgs xs ys = ys ++ xs

runGhcjs :: (HasCallStack,MonadIO m,HasPlugin Hakyll t m,HasPlugin GHCJS t m) => FilePath -> FilePath -> Haap t m FilePath
runGhcjs hsFile hmtlPath = do
    hp <- getHakyllP
    ghcjs <- liftPluginProxy (Proxy::Proxy GHCJS) $ Reader.ask
    do
        tmp <- getProjectTmpPath
        -- compile files with ghcjs
        let io = ghcjsIO ghcjs
        let stack = maybe callStack id (ioCallStack io)
        (destdir,destfolder) <- do
                let exec = takeFileName hsFile
                let destdir = dropExtension (hmtlPath </> exec)
                let destfolder = addExtension destdir "jsexe"
                return (destdir,destfolder)

        res <- orIOResult $ runBaseShWith' (io) $ do
                let (dir,exec) = splitFileName hsFile
                let ghcjs' = ghcjs { ghcjsMake = True, ghcjsArgs = ghcjsArgs ghcjs ++ ["-o",dirToRoot dir </> tmp </> destdir], ghcjsIO = io }
                Sh.mkdir_p (fromString $ tmp </> destfolder)
                shCd dir
                shGhcjsWith ghcjs' [exec]

        if resOk res
            then addMessageToError (prettyText res) $ do
                hakyllFocus [tmp </> destfolder] $ hakyllRules $ do
                    match (fromGlob $ tmp </> destfolder </> "*.html") $ do
                        route   $ relativeRoute tmp `composeRoutes` funRoute (hakyllRoute hp)
                        compile $ getResourceString >>= hakyllCompile hp
                    let auxFiles = fromGlob (tmp </> destfolder </> "*.js")
                                   .||. fromGlob (tmp </> destfolder </> "*.externs")
                                   .||. fromGlob (tmp </> destfolder </> "*.webapp")
                                   .||. fromGlob (tmp </> destfolder </> "*.stats")
                    match auxFiles $ do
                        route   $ relativeRoute tmp
                        compile copyFileCompiler

                return (hakyllRoute hp $ destfolder </> "all.js")
            else throw $ HaapException stack $ prettyText res

redpajama_set_name: RedPajamaGithub


text:
package views.sicandcompliance

import forms.WorkersForm
import org.jsoup.Jsoup
import views.VatRegViewSpec
import views.html.sicandcompliance.workers

class WorkersViewSpec extends VatRegViewSpec {

  lazy val view = app.injector.instanceOf[workers]
  implicit val doc = Jsoup.parse(view(WorkersForm.form).body)

  object ExpectedContent {
    val heading = "How many workers does the business supply?"
    val title = s"$heading - Register for VAT - GOV.UK"
    val button = "Save and continue"
  }

  "Workers Page" should {
    "have the correct page title" in new ViewSetup {
      doc.title mustBe ExpectedContent.title
    }
    "have the correct heading" in new ViewSetup {
      doc.heading mustBe Some(ExpectedContent.heading)
    }
    "have a label that's the same as the heading" in new ViewSetup {
      doc.textBox("numberOfWorkers") mustBe Some(ExpectedContent.heading)
    }
    "have a primary action" in new ViewSetup {
      doc.submitButton mustBe Some(ExpectedContent.button)
    }
  }

}


text:
EnvironmentInsights And OpinionsMaking The ChangeOceanSustainabilityWildlife
Thank The Ocean For Every Breath That You Take
Does oxygen come from the Oceans?
Breathing comes quite naturally to you but have you ever thought about it in a deeper way?
Take a deep breath right now and reflect on it.
Read: Gulf Of Mexico Dead Zone: This No-Oxygen Region Is Getting Bigger And Badder
The main reason for us to breathe is to get oxygen. Oxygen makes up 21% of the Earth's atmosphere but all this gas comes from somewhere.
By now, you should be knowing about photosynthetic organisms like green plants but did you know that most of the oxygen comes from certain organisms in the oceans?
That's absolutely correct!
More than half of the oxygen that your body requires comes from marine photosynthesizers like phytoplankton and seaweed. Both these organisms use water, sunlight, and carbon dioxide to produce nutrition for themselves and release oxygen as a byproduct. In easier terms, they photosynthesize in the oceans.
What Are Phytoplanktons?
Phytoplanktons belong to the plankton community and are an integral part of the freshwater ecosystems. They obtain their energy with the help of photosynthesis and are distributed over a large surface area. These organisms also respond rapidly to changes in climate.
These organisms form the base of the marine and freshwater food chains and are important elements in the carbon cycle. The phytoplanktons account for half of the world's photosynthetic activity and oxygen production, even though they amount to only 1% of the global plant biomass.
These organisms are extremely diverse and vary from photosynthesizing bacteria to plant-like algae to armor-plated coccolithophores. Some of the important groups of phytoplankton are the diatoms, cyanobacteria, and dinoflagellates.
Read: Persistent Organic Pollutants: Among The Most Dangerous And Persistent Chemicals Released By Humans
Most of these organisms are too tiny to be seen with the naked eye but can be seen clearly when they are present in high numbers. They appear as colored patches on the surface of water bodies due to chlorophyll inside their cells. They also contain pigments like phycobiliproteins or xanthophylls.
Photosynthesizers In The Oceans
Photosynthetic organisms have been in the oceans for a long time. Terrestrial plants appeared in fossil records sometime around 470 million years ago, long before the advent of dinosaurs. The oceans had been producing oxygen for billions of years before such a thing happened.
The oldest known fossil came from a marine cyanobacterium, which is a tiny, blue-green photosynthetic organism that released oxygen 3.5 billion years ago.
So, in this way, we owe these organisms and the oceans for all the oxygen that comes from terrestrial plants. This is because land plants had evolved from green marine algae. If we consider a race that would put oxygen in the atmosphere, the oceans were a heck of a head start.
The long history of photosynthesis in the oceans matter very little for us, if not for the photosynthetic organism that lives in it today.
The most impressive photosynthesizer is a cyanobacterium called Prochlorococcus. This organism is estimated to be more abundant than any other photosynthesizer on the planet, and to be responsible for producing 20% of the oxygen in the atmosphere.
So, if we calculate, one in every five of your breaths is owed to the Prochlorococcus. This super-abundant and amazing organism were discovered in 1988, which is less than 30 years ago.
The Other Impressive Photosynthesizer
Sunlight is necessary for photosynthesis, which means that all marine photosynthetic organisms must like in the "photic zone". This is the layer at the top of the ocean which is illuminated by sunlight. This zone extends down to about 656 ft below the surface of the ocean. 886 ft below the surface, will be quite dark for you but a type of red algae called Corallinales photosynthesizes there.
The red color of this organism comes from a pigment that allows it to absorb blue and green light, which is the only thing that trickles down to such depths. This photosynthetic organism produces oxygen even though it receives the tiniest amount of sunlight.
Whether these organisms have evolved the earliest or dwell in the deepest part of the ocean or even photosynthesize the most, they are all crucial for our survival. If these organisms were not around, we would not have been breathing.
So, take some time out and remember the majestic oceans and their photosynthesizers. They are all helping you out with every breath that you take.
Previous articleYulan Magnolia Flowers Just Look Like Beautiful Birds
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Partisha is an enthusiastic single mother. Though it appears her husband has been away on some kind of spiritual journey for some time now, she keeps her head held high for her daughter, Renee. Renee is a young adult trying to figure out how she's going to start her life. Renee's newly acquired computer has allowed her to use the internet for continuing education. Partisha is especially interested in Renee learning the tricks of the 'business' trade in an online education program. Renee, however, does not feel the business courses are right for her. Renee has discovered an alternative educational program on the internet that seems to make more sense to her. Partisha becomes suspicious of Renee's online activity, so she hires a computer guy, Michigan Tim, to assist in blocking certain sites on Renee's computer. Despite Michigan Tim's effort, Renee is still able to watch her training videos. Renee's ultimate goal is to achieve what is called an "Advisory Implant". Said implant has different levels, which are achieved through logging more time on the website. The implants allegedly "allow you to think and have great friends".
ANDREW  - Duration: 9 minutes, 28 seconds.
A Weekend (a very good movie)  - Duration: 20 minutes.
The Rosselsons (a family movie)  - Duration: 37 minutes.
A Week Off (an even better movie)  - Duration: 30 minutes.
A Pregnancy (a very serious movie)  - Duration: 35 minutes.
surprise.  - Duration: 42 minutes.
The Rosselsons - Breakfast Gossip - Duration: 5 minutes, 51 seconds.
The Rosselsons - Baby Child - Duration: 6 minutes, 11 seconds.
The Rosselsons - New Love - Duration: 6 minutes, 10 seconds.
The Rosselsons - Educated Friends - Duration: 6 minutes, 29 seconds.
The Rosselsons - Left Field - Duration: 6 minutes, 40 seconds.
The Rosselsons - Hearty Casserole - Duration: 6 minutes, 24 seconds.
Volume 1: Nine and Ten - Duration: 9 minutes, 51 seconds.
Volume 2: Found - Duration: 6 minutes, 45 seconds.
Volume 3: Assault - Duration: 6 minutes, 38 seconds.


At the end of every year we publish a Case Docket that includes all the court cases we have been involved in that year. Take a look at the files below to learn more about what we have done.
As of 2014, the ACLU of Rhode Island no longer publishes an annual docket. To see the cases we've worked on over the years, please select an issue under Cases by Issue.


text:
PayPal Zettle
UK Competition & Markets Authority Provisionally Clears PayPal's Completed Acquisition of iZettle
SAN JOSE, Calif.--PayPal Holdings, Inc. (NASDAQ: PYPL) announced today that it welcomes the United Kingdom Competition and Markets Authority's (CMA) decision to provisionally clear its previously completed acquisition of iZettle. The CMA found that the merger of PayPal and iZettle does not raise competition concerns in the UK.
"We are pleased the CMA has provisionally cleared our transaction," said Dan Schulman, president and CEO, PayPal. "We look forward to adding iZettle's products and services to our platform to help small businesses access even more affordable tools to run their shops and compete against the retail giants."
The CMA has published these provisional findings on its website. Its final decision is expected by mid-June after collecting views on the provisional findings and assessing all evidence.
PayPal will continue to work closely with the CMA through the remainder of its review. PayPal's acquisition of iZettle was completed on September 20, 2018 and is not subject to review in any other country.
Fueled by a fundamental belief that having access to financial services creates opportunity, PayPal Holdings, Inc. (NASDAQ: PYPL) is committed to democratizing financial services and empowering people and businesses to join and thrive in the global economy. Our open digital payments platform gives PayPal's 277 million active account holders the confidence to connect and transact in new and powerful ways, whether they are online, on a mobile device, in an app, or in person. Through a combination of technological innovation and strategic partnerships, PayPal creates better ways to manage and move money, and offers choice and flexibility when sending payments, paying or getting paid. Available in more than 200 markets around the world, the PayPal platform, including Braintree, Venmo, Xoom and iZettle, enables consumers and merchants to receive money in more than 100 currencies, withdraw funds in 56 currencies and hold balances in their PayPal accounts in 25 currencies. For more information on PayPal, visit https://www.paypal.com/about. For PayPal Holdings, Inc. financial information, visit https://investor.paypal-corp.com.


text:
Expensive College QB Decisions
I wonder if Oklahoma quarterback Sam Bradford is re-thinking his decision to return to school for his senior year after sustaining a shoulder injury in the Sooners opening game 14-13 loss to Brigham Young.
Bradford, who threw for 50 touchdowns and only eight interceptions last season leading Oklahoma to the BCS Championship game, was considered a top five NFL pick in the 2009 draft. He appears to have left millions of dollars on the table.
Bradford's injury reminds me of when Miami Hurricanes quarterback Jim Kelly injured his shoulder in 1982 against Virginia Tech and was sidelined for the season. Kelly did rehabilitate his shoulder and had his own pro day in Coral Gables. He was drafted by the Buffalo Bills in the first round in 1983.
Meanwhile, USC Heisman Trophy Winner Matt Leinart was considered a top prospect in the 2005 NFL Draft after his Trojans won the national title with a 55-19 thrashing of Oklahoma in the Orange Bowl leading them to a 22-game winning streak. Leinart came back for another season. The Trojans reached the BCS title game and lost to Texas and Vince Young in the Rose Bowl. USC had a 35-game winning streak but Leinart dropped to 10th in the 2006 NFL Draft to the Arizona Cardinals. Young was drafted ahead of Leinart and was the third player selected going to the Tennessee Titans.
Leinart is currently the Cardinals backup behind Kurt Warner and like Bradford, his check book took a financial hit.
Detroit Lions quarterback Matthew Stafford cashed in on Bradford's decision to stay in school with a contract that guaranteed him $41.7 million (the most guaranteed to any player in NFL history) and the total value is $78 million. It's safe to say that if the former Georgia Bulldog wants to get his degree after leaving as a junior, he'll be able to pay his tuition. In any economy let alone a bad one, Stafford looks like a genius.
What makes Bradford's decision even more intriguing is if his thought process was to come back and win a national title after losing 24-14 to Florida on January 8, those hopes took a jolt at Cowboys Stadium in the Sooners loss to BYU.
I'll never criticize a player for going back to school but that can wait when there is plenty of money out there.
In Kelly's case, I don't recall an under graduate rule so the only options were the defunct USFL and the Canadian Football League. Before signing with Buffalo in 1986, Kelly did play for the USFL's Houston Gamblers for two seasons in Mouse Davis' run-and-shoot offense amassing 9,842 yards and 83 touchdowns winning the league MVP in 1984. By developing his game under Davis' tutelage, Kelly guided Buffalo to four straight Super Bowls and that led to his induction to the Pro Football Hall of Fame in 2002. I doubt Kelly would have left early playing for Howard Schnellenberger.
It will be interesting to see how Florida's Tim Tebow and Texas Colt McCoy fare in their senior seasons as they attempt to stay healthy as well as lead their teams to a national championship.
If both have excellent seasons they could become the next quarterback debate in the 2010 NFL draft.
Thus far, the move has backfired for Bradford unless he returns for the last half of the season and the Sooners get to a major bowl game plus he follows it up with a huge pro day following Kelly's example.
Labels: Buffalo Bills, Colt McCoy, Houston Gamblers, Howard Schnellenberger, Jim Kelly, Matt Leinart, Sam Bradford, Tim Tebow, USFL, Vince Young


Sculptural artist Massimiliano Pelletti lives and works in the Italian town of Pietrasanta. Born to an artisan family, Pelletti honed his skills in the processing of marble through lessons with his grandfather. Now, his practice has evolved into a contemporary contemplation of the material, and in this series of works, he fuses the classically formed marble busts with crystalline forms. Through this, Pelletti considers the tensions between careful craftsmanship and chance. His sculptures, as an end result of this experimentation, speak poignantly of new growth contrasted with decay, presenting a thoughtful interaction with iconic imagery of a bygone era.


Autumn is the perfect time to explore the estate at Hughenden. With open parkland, rolling hills and beech woodlands there are beautiful walks through unspoilt Chilterns countryside to enjoy.
There are four colour-coded waymarked walks with online maps that will help you enjoy Disraeli's forest and the native woodlands, with panoramic views the reward for the uphill climbs.


text:
RESEARCH ARTICLE| 01 October 1968
The Action of the Eyecup Muscles of the Crab, Carcinus, During Optokinetic Movements
M. Burrows,
M. Burrows *
Gatty Marine Laboratory and Department of Natural History
G. A. Horridge
Present address: Department of Biology, University of Oregon, Eugene, Oregon. 97403 U.S.A.
Copyright 1968 The Company of Biologists Ltd.
J Exp Biol (1968) 49 (2): 223–250.
https://doi.org/10.1242/jeb.49.2.223a
Version of Record 01 October 1968
M. Burrows, G. A. Horridge; The Action of the Eyecup Muscles of the Crab, Carcinus, During Optokinetic Movements. J Exp Biol 1 October 1968; 49 (2): 223–250. doi: https://doi.org/10.1242/jeb.49.2.223a
The actions of the nine eyecup muscles of the crab during horizontal optokinetic movements are described.
Each muscle includes a wide spectrum of fibre types, ranging from phasic, with sarcomere lengths of 3–4 μm., through intermediate, to tonic fibres with sarcomeres of 10–12 μm. Each muscle receives at least one slow and one fast motoneuron, but no inhibitory supply. The slow axons predominantly innervate the tonic muscle fibres while the fast axons innervate the phasic ones.
Slow movement and the position of the eyecup in space are controlled by the frequency of slow motoneuron discharges. All muscles collaborate at every position. The phasic system is recruited during rapid eyecup movements of large amplitude.
In optokinetic nystagmus the exact form of the impulse sequences are described for each muscle. They are the consequence of a visually driven central programme which takes no account of the movement which it generates. Movements in opposite directions involve different central programmes; the one is not merely the reverse of the other. There is no effective proprioceptive feedback from the eyecup joint or from muscle tension receptors.
In decapod Crustacea the compound eye lies upon a projecting eyecup which is moved by nine eyecup muscles about a flexible joint with the eyestalk. Three eyecup reflexes are distinguishable. First, a movement of the whole visual field causes an optokinetic response in which both eyecups follow the stimulus. In the horizontal, but not the vertical, plane there are nystagmus movements in which the eyecups periodically flick back and start the movement over again. Secondly, on tilting the animal, the eyecups tend to hold their absolute position in space. These two responses occur in any direction by a movement at the universal articulation of the eyecup upon the eyestalk. Thirdly, a noxious stimulus on or near an eyecup causes a unilateral withdrawal of that eyecup into its socket. The different movements and stimuli which cause these three reflexes are defined in Fig. 1.
Eyecup movements. A movement of the whole visual field in any plane causes an optokinetic following movement, which is stronger in the horizontal (A) than m the vertical plane. Nystagmus movements occur only in the horizontal plane. A mechanical stimulus to the carapace (shaded area in B) causes a unilateral withdrawal of the eyecup into its socket. Pitch (C) or roll (D) tilt cause compensatory movements, tending to preserve the absolute position of the eyecup in space. Appropriate movement of the visual field also causes movement m these planes. Only in vertical movements (C) do both eyecups move in the same direction relative to the midline.
Superimposed on these reflex movements are four other small amplitude movements which occur even when the visual field is stationary.
When the crab is surrounded by a blank visual field the eyecups show tremor at a frequency of 2–5 Hz. and amplitude of 0·05–0·2° peak-to-peak (Horridge & Sandeman, 1964). This tremor is sufficient to sharpen perception of contrasting edges (Horridge, 1966a). Its control is dealt with in a later paper (Horridge & Burrows, 1968).
Spontaneous flicks or saccades occur infrequently with an amplitude similar to tremor but with a fast initial phase and a slow return phase (Horridge, 1966b).
When a contrasting object is presented to a crab the eyecups often show scanning movements with an amplitude of 0·5–1° peak-to-peak (Horridge & Sandeman, 1964). In Carcinus these movements are infrequent but some crabs such as Pachy-graspus, show a regular oscillatory scan.
In the dark, or when seeing no contrasts, the eyecups drift from their original position. At all times there may be a very slow drift, over periods of minutes, back to a 'preferred' position near the centre of the orbit (Horridge & Sandeman, 1964; Horridge, 1966b).
Study of the control at the eyecup joint offers many advantages in that several different situations of natural stimulation are available, and it is possible to record the pattern of activity in about 25 motoneurons by intracellular electrodes in the muscle fibres to which they run. Such a system is especially favourable for analysis of how a crustacean uses its peripheral neuromuscular system. This paper is concerned with the action and control of the eyecup muscles during a normal optokinetic response.
The eyecup muscles were examined both unfixed and after fixation for 12 hr. in sea-water Bouin. The latter softens the exoskeleton and facilitates dissection of the now coloured and hardened muscles. For histological work the eyecup was perfused with a solution of 2·5% glutaraldehyde in cacodylate-buffered sea water at pH 7·4 and post-fixed in OsO4 in sea water. Transverse and longitudinal sections at 0·5μm. thick of each muscle were cut from Araldite blocks, and stained with toluidine blue. Attached pieces of exoskeleton enabled the muscles to be orientated, and the same fibres were identifiable in T.S. and L.S.
Motoneurons were demonstrated by staining with methylene blue, while the blood supply to the eyecup was revealed by injecting the main vessels as they leave the heart with indian ink from which shellac is removed (Gunther Wagner 'Pelikan' Cn (1431a) (Sandeman, 1967).
The intact crab was rigidly held at the lateral edges of its carapace by a clamp which prevented the legs touching the eyecups. The crab was arranged with its transverse axis horizontal and its longitudinal axis 15° above the horizontal at the anterior end, as in the resting posture.
Extracellular muscle action potentials and eyecup movements were recorded simultaneously from the freely moving right eyecup. To reach the muscles, holes were drilled with small entomological pins through the exoskeleton over the appropriate muscle. The end of a small coil of silver wire 50 μm. thick, insulated to the tip, was inserted into the muscle through the hole. Such an electrode leaves the eyecup free to move but is rarely dislodged, while it records potentials of 100–200 μV amplitude. After an experiment the electrode wire was cut at its entry into the eyecup, which was then removed and fixed for 12 hr. in sea-water Bouin. Subsequent dissection confirmed the placement of the electrode tip.
To measure eyecup movements, a 2 cm. L-shaped wand of 0·2 mm Nylon line was fixed with Eastman 910 adhesive to the medial side of the eyecup and extended over the carapace of the crab. The wand which carried a stable 40 KHz. 10 V. peak-to-peak signal moved between two metallic antennae which picked up the signal and fed it to a differential a.c.-coupled amplifier. The output of this amplifier was then compared with the original 40 KHz. signal and converted into a d.c. voltage. The system will measure eyecup movements linearly over a range of 30° with a sensitivity of 0·01°, and faithfully up to 10 Hz. (Sandeman, 1968).
A drum with vertical black and white stripes each subtending an angle of 150 at the crab's eye was used as the visual stimulus. Continuous drum movements were available at speeds ranging from 0·03°/sec. to 5°/sec.
Intracellular recordings from the eyecup muscles were made from the right eyecup, firmly cemented in its socket. To avoid interference from objects in the view of this eye, it was blinded by coating the cornea with quick-drying black paint. With this arrangement the right eyecup muscles are driven by the visual stimulation to the left eye. All experiments were performed with the crab in air.
Eye assembly
The complete eye assembly consists of five skeletal elements moved by thirteen pairs of muscles. The terminology is taken from Cochran (1935). Anterior to the brain is the median plate which is moved about the main body skeleton by three pairs of muscles not treated here. Attached to this plate are the elongated eyestalks which project laterally on either side. They are attached proximally to the exoskeleton by membranes along their anterior and posterior edges, and distally by muscle 18 which can move both eyestalks about their longitudinal axes. The eyestalks are completely enclosed by a fold of the carapace and only the eyecups, which attach to their proximal end, normally protrude. In the resting posture the eyecups point forward at an angle of 40–45° to the longitudinal body axis and at 40–45° to the vertical. In this position the rows of ommatidia are horizontal.
Movement of the eyecup upon the eyestalk is possible in all planes, allowing a total excursion of 30o in the horizontal plane (yaw), 70° in the vertical (pitch) and 50° when the crab is rotated about its longitudinal axis (roll). Superimposed photographs of the eyecup during a horizontal movement show that the apparent pivot continually shifts (Fig. 2). As the eyecup moves toward the mid-line the 'pivot point' moves back from near the centre of the eyecup to the distal edge of the eyestalk. This can occur because the joint has no fixed condyles but is surrounded by a flexible arthrodial membrane, and the eyecup is suspended upon its muscles. The arthrodial membrane is stiffened by three small sclerites which attach to the edge of the eyecup and tuck into the membrane (Fig. 3).
Tracings from photographs taken vertically above the crab as the right eyecup was moving towards the midline. Several exposures of the eyecup in successive positions were made on the same frame, and the camera was not moved between frames. The first position is shown by the solid line; the second by the dashed line. The 'pivot' point of the eyecup, as found by moving a 'cut-out' figure over the outlines, is not constant, but continually changes during movement.
Musculature of the eyecup and eyestalk in Carctnus. (A) Right eyecup dissected from the lateral side to show the medial muscles. (B) Dissection from the same side to show the lateral muscles. (C) Dorsal view with muscles 18, 19a, 20a and 20b omitted. The joint is surrounded by a continuation of the membrane which attaches the eyestalk to the main body skeleton. The membrane is stiffened by three sclerites near the attachment of the muscles to internal projections of the exoskeleton of the eyestalk.
Eyecup musculature
The nine eyecup muscles (Fig. 3) have their origins on internal projections of the eyestalk exoskeleton and insert on the eyecup at points which are recognizable externally by a different texture of the surface exoskeleton. The numbering of the muscles described by Cochran (1935) for the American blue crab, Callinectes sapidus, has been retained but her nomenclature has been abandoned as it implies certain functions which are not confirmed. According to Cochran's terminology, muscle 19, the oculi abductor and muscle 23, the oculi retractor medialis consist of two branches, a and b, while muscle 20, the oculi retractor dorsalis consists of three parts, a, b and c. The branches of these muscles are found to be separate physiological units but the numbering is retained implying that they have similar origins whatever their function. Muscle 19a, the largest in the eyecup, originates at the base of a lateral projection of the eyestalk and inserts on the lateral wall of the eyecup just behind the cornea. All the fibres are of the 'Fibrillenstruktur' type (later shown to be fast or phasic fibres) as described in vertebrates by Kruger (1949), Hess (1961) and in Crustacea by Cohen (1963). The Z-bands, often broken across the width of a fibre, are spaced 3–4μm. apart.
Muscle 19b originates beside 19a on the base of the same projection but runs medially and inserts on the ventral surface of the eyecup. The fibres are not uniform in appearance; some have Z-bands spaced 10–12μm. apart, as in 'Felderstruktur' fibres elsewhere. The other fibres have an intermediate structure with a sarcomere length of 6·8μm. Extreme 'Fibrillenstruktur' fibres are not present.
Muscle 20 a originates on the distal end of the lateral eystalk projection and inserts on the lateral wall of the eyecup behind muscle 19a. The majority of its twenty-five or so muscle fibres have sarcomere lengths of either 3·4 μm., or 10·12 μm., but a few are intermediate. The fibre types are intermingled.
Muscle 20b has the same origin as 20 a but runs vertically upwards to insert on the dorsal eyecup wall near its proximal edge. This small muscle, enclosed in a tight connective sheath, has approximately ten muscle fibres of which only three have sarcomere lengths of less than 4 μm., the rest being 10–12 μm.
Muscle 20c runs vertically downwards from its origin below 20 a and 20 b to insert on the ventral wall of the eyecup near its proximal edge. It is smaller than muscle 20 b, with about eight fibres, half of which have 'Fibrillenstruktur' and the other half 'Felderstruktur'. Sclerite 1 stiffens the membrane near the attachment of muscles 20a, b and c.
Muscle 21, small and compact, arises from a tendon attached to the medial edge of the eyestalk and inserts in a depression on the medial side of the eyecup. Fibres with 'Fibrillenstruktur' and 'Felderstruktur' are intermingled but few show extreme 'Felderstruktur'.
Muscle 22 runs diagonally across the eyecup from its origin, near sclerite 2 and a skeletal bar, to its insertion on the ventro-lateral wall of the eyecup. The skeletal bar runs in the arthrodial membrane from the sclerite to which muscle 18 attaches. The fibres are predominantly 'Felderstruktur' with sarcomere lengths of 8–10μm.
Muscle 23a has its origin on the medial edge of a prominent jointed projection of the dorsal surface of the eyestalk and inserts above muscle 21 on the dorso-medial surface of the eyecup. Histologically the fibres are a mixed population with the 'Felderstruktur 'fibres towards the dorsal surface.
Muscle 23b arises alongside muscle 23 a and inserts on the lateral side of the dorsal eyecup surface. The joint membrane is stiffened at the origin of these two muscles by the intucking of sclerite 3. The muscle fibres have sarcomere lengths of 6–12 μm.
Muscle 18 is the only muscle present in the eyestalk. It has its origin upon a sclerite which is fixed to the main body skeleton and it spreads to an insertion on the dorsal wall of the eyestalk which it rotates relative to the body. Its fibres are mixed in type.
Innervation of the muscles
After leaving the brain the oculomotor nerve branches before entering the eyestalk and a small purely sensory lower branch ramifies in connective tissue and supplies the carapace around the eyestalk. The upper branch, containing about thirty large axons, runs in the hollow of the eyestalk until, at the level of muscle 18, it branches profusely to the eyecup muscles. The optic tract branches at the same level and also supplies some of the eyecup muscles. The branches of both these nerve trunks are so interwoven that a complete picture, with anatomical origins and numbers of axons, for each muscle cannot be given. Methylene blue staining has been most successful for muscle 20 a, which receives four axons from the oculomotor nerve, and a large axon from the optic tract which also supplies muscles 19a and 19b.
Proprioceptive structures, although sought in methylene blue studies and in serial transverse and longitudinal sections of the eyecup, have not been found. However bipolar cells of unknown function but typical of many arthrodial membranes have been described in the membrane of the eyecup/eyestalk joint (Sandeman, 1964).
Blood supply to the eyecup
The eyecup is supplied by branches of two blood vessels. The optic artery which runs along the anterior edge of the eyestalk supplies the optic lobes (Sandeman, 1967) but also branches to supply muscles 20 a, b and c, 23 a and b and muscle 21. The oculomotor artery runs along the posterior edge of the eystalk and supplies the rest of the musculature but also muscle 21 as well. Visual reflexes fail soon after the blood vessels are damaged.
The optokinetic response
Continuous horizontal rotation of the vertically striped drum around the crab induces an optokinetic nystagmus. This consists of a slow forward phase, in which both eyecups follow the direction of the drum rotation but with an ever-increasing lag, and a fast return phase (flick-back) which returns the eyecups approximately to their original position, from which they repeat the cycle. The two eyecups move together, but in opposite directions relative to the midline of the crab. Drum speeds of 2·2°/sec have been used in most of the records figured here, but tonic responses are similar at drum speeds from 0·001°/sec to 5°/sec.
The slow phase
The eyecup response during the slow phase is not a simple representation of the drum movement. When the eyecup starts from rest after a previous flick-back it moves faster than the drum but soon slows to a uniform speed which is less than the drum speed (Fig. 4). Towards the end of the slow phase the eyecup slows down and frequently may stop some time before the next flick-back occurs. Neither the actual stimulus to the eye (the difference between drum speed and eyecup speed, which is termed the slip speed) nor the ratio of response velocity to actual stimulus velocity (termed the velocity gain of the system) is constant during a single slow phase. Furthermore, tremor of the eyecup is initially of a low frequency and amplitude, but about halfway through the slow phase it increases in both frequency and amplitude. Tremor is smaller in amplitude when the eyecup moves toward rather than away from the midline, and is smaller at lower drum speeds (Fig. 4). Tremor is correlated with the activity of fast motoneurons to two muscles subsequently to be described. The total extent of the slow phase can vary from 2 to 20° with a mean of 10°, and in a series of nystagmus movements by one eye its exact form sometimes shows great variation, even at a constant drum speed. Other animals, however, are remarkably consistent in performance over periods of hours. With opposite directions of drum rotation the slow phase occurs over different ranges of the orbit, with the fast phase in either direction restoring the eyecups to the same approximately central, position.
Nystagmus movements of the right eyecup of one crab recorded as it followed the continuous rotation of a striped drum moving at various speeds. In (A) the drum moved clockwise so that the slow-phase eyecup movement was away from the midline; in (B) the drum movement is reversed and the baseline is adjusted. The upper trace represents the d.c. component of the eyecup movement while the lower is a.c.-coupled at ten times the amplification to reveal tremor. During the course of a slow phase the tremor increases both in frequency and amplitude, but is less at lower drum speeds and when the eyecup moves toward the midline.
The fast phase
The eyecup movement during the fast phase is relatively uniform but is slightly decelerated towards the end. The movement is constant over the range of drum speeds used. This differs from the situation in the rabbit where there is a correlation between the speeds in the fast and slow phases (Koike, 1959).
Mechanics of horizontal movement
The mechanical characteristics of the eyestalk-eyecup joint during horizontal movement are required before it can be shown that the motor impulse frequency determines the eyecup position. Measurements were made on anaesthetized, blind and normal crabs. One group of crabs was blinded by coating both eyes with black paint, and other, untreated animals were surrounded by a black and white, vertically striped drum. Small weights were hung on the eyecup by means of a pulley system and the resulting angular deflexion of the eyecup was measured as described in the methods section. Over a range of 15° around the centre of the orbit the deflexion is proportional to the load, but towards the extremities the resistance to movement increases (Fig. 5). In the anaesthetized crabs a torque of 6 dyne-cm/deg. is required to move the eyecup in the central region of the orbit, corresponding to the passive resistance of the joint and muscles. In the blind crab, with background activity in the muscles, the torque needed rises to 20 dyne-cm/deg. and in the seeing eye it is greatest, at 40 dyne-cm/deg. The difference between the curves for blind and seeing crabs is caused by the visual feedback.
Graphs of load imposed on the eyecup and its resulting deflexion in anaesthetized, blind and normal crabs. The curve for anaesthetized crabs represents the force necessary to overcome the passive elements of the joint, while the difference between the curves for seeing and blind crabs represents the effectiveness of visual feedback. The inset shows the effect of applying a weak pulse by an electromagnet acting on a small piece of iron attached to the eyecup while stationary and while moving through the same point. The equality of the mechanical responses shows that the forces which oppose movement are similar in the resting and in the moving eyecup.
To test whether the relation between movement of the eyecup and tension in the muscles applies to the moving as well as to the stationary eyecup, a further check is necessary because the stationary eyecup is not characterized by inactive muscles. A light iron wand was attached to the eyecup and its movements were monitored as previously described. The output of the movement detector system triggered an electromagnet when the eyecup reached a given point, and a sudden impetus of 200 msec, duration at a just effective strength was then applied to the eyecup in the same direction as the eyecup movement. The rise time and amplitude of the resulting small additional deflexion proved to be independent of the position of the eyecup in the orbit or whether it was stationary or moving (Fig. 5). From this it is reasonable to conclude that the resistance of the eyecup joint to deflexion by its own muscles is not greatly increased or decreased by its own movement. Therefore measurements of the effective torques for the stationary eyecup apply to the moving eyecup. Therefore greater muscle tension, so long as it is not antagonized by other muscles, is the cause of greater deflexion of both stationary and moving eyecups.
Electrical activity of the muscles
Two types of responses are recorded from each muscle. The first is a steady tonic activity when the eyecup is stationary or moving, and could be caused by the discharge of a classical 'slow' axon. The second is a 'bursty' or phasic activity usually present only when the eyecup is moving, and which could be caused by the discharge of a classical 'fast' axon. Extracellular records showed that these two types of activity could sometimes be recorded from different parts of a muscle. For example, in muscle 23 b, tonic activity is recorded on the dorsal surface and is correlated with the distribution of 'Felderstruktur' fibres. These factors suggest that the fast and slow motor axons to each muscle tend to supply two separate groups of fibres.
Other differences between muscle fibres were noted when recording with intracellular electrodes. On the basis of their membrane properties and innervation patterns the muscle fibres can be somewhat arbitrarily grouped into three main classes, as in leg muscles (Atwood, 1963, 1965); phasic fibres which are supplied only by a fast axon; tonic fibres which are supplied only by a slow axon and intermediate fibres which are supplied by both types of axon.
Phasic muscle fibres have a resting potential between 65 and 80 mV., large junction potentials up to 20-30 mV., with a short rise time, and a time constant of decay of 20–50 msec. (Fig. 6A). The phasic junction potentials show marked facilitation and at high frequencies spikes may occur, although this shows some seasonal dependence correlated with the moult cycle, as has been found previously (Atwood, Hoyle & Smyth, 1965; Hoyle & Wiersma, 1958b).
Intracellular activity recorded from phasic (A) and tonic (B) fibres of muscle 20a of a right eyecup innervated respectively by fast and by slow motoneurones. The records show an optokinetic nystagmus elicited by the rotation of a striped drum, which begins as indicated by the arrows. Phasic activity is absent when the drum is stationary and begins only when the drum has moved a certain distance. The junction potentials then show a gradual increase in frequency with much facilitation. At high frequencies the firing becomes more irregular and active membrane events occur. Tonic activity is present when the drum is stationary and as the slow phase progresses there is an increase in frequency with little facilitation. At high frequencies the activity becomes more regular. All activity is inhibited centrally at the onset of a fast phase movement. (C) A fibre innervated by two slow axons often shows 'beats' caused by the slightly different frequencies of the two axons. As their firing frequency increases so does the 'beat' frequency. Scale: A: 40 mV., 200 msec.; B: 40 mV., 400msec. C: 10 mV., 500 msec.
Tonic muscle fibres usually have a smaller resting potential of 50–65 mV., smaller junction potentials of 5–15 mV., with a slower rise time, and a longer time constant of decay of 50–200 msec. (Fig. 6B). They show little facilitation and at high frequencies the amplitude of the individual junction potentials may decrease as a depolarization plateau is reached. At high firing frequencies fibres innervated by two slow axons often show a 'beat' frequency (Fig. 6C), which is the consequence of two slow axons firing at slightly different frequencies (Katz, 1936).
In intermediate fibres the junction potentials of the slow and fast axons can vary considerably from fibre to fibre. In some, the junction potential of the slow axon is larger than that of the fast axon; in others the situation is reversed as is found in leg muscles (Hoyle & Wiersma, 1958a; Atwood, 1963).
Individual muscle responses
Detailed data is presented in the illustrations which are chosen from many recordings to be representative of the action of the individual muscles.
This muscle does not directly control movement of the eyecup but governs the rotation of the eyestalk about the main body skeleton. However, a rotation of the eyestalk also results in a slight rotation of the extended eyecup.
During horizontal optokinetic movements of the eyecup tonic activity, due to the firing of a single slow axon, continues at a frequency of about 25 Hz. unaffected by the direction of movement or by the slow or fast phases of nystagmus.
The fast axon to this muscle runs in the optic tract and is active only during a withdrawal movement of the eyecup.
Muscle 19a
Many penetrations of fibres of muscle 19a, both with extracellular and intracellular electrodes, have failed to reveal any electrical activity during optokinetic movements. This muscle is, however, involved in withdrawal of the eyecup into its socket, and is dealt with under eyecup withdrawal in a later paper (Burrows & Horridge, 1968).
Muscle 19b
Tonic activity in muscle 19b caused by the discharge of a single slow axon occurs throughout optokinetic movements in the horizontal plane. During the slow phase of a response away from the midline the frequency declines very gradually from 20 Hz. (Fig. 7). At the onset of the fast return phase the frequency rises to 30 Hz. and stays at that frequency for the duration of the fast phase, declining again during the course of the next slow phase.
Tonic (upper) and phasic (lower) activity in muscle 19b during a slow-phase movement of the eyecup away from the midline and a fast return phase toward the midline. On this and subsequent figures each dot shows the instantaneous muscle potential frequency plotted on a logarithmic scale at the instant halfway between two potentials. The time scale for the fast phase is expanded and the inset shows the extent and direction of the slow phase. The lower traces on a different time scale, are the extracellular muscle potential records, from which the graphs were plotted, together with the concomitant eyecup movement. The tonic frequency of muscle 19b declines gradually during the slow phase but is raised during the fast. A burst of phasic activity precedes the fast phase but then gradually declines during the next slow phase.
During a slow phase towards the midline the tonic frequency increases slightly from 15 to 20 Hz. (Fig. 8). Just before and for the first 100 msec, of the fast return phase the activity is inhibited but then resumes at its previous frequency. Repeated probing with intracellular electrodes in this and the other eyecup muscles has failed to reveal any evidence of peripheral inhibitory axons. Moreover, records of oculomotor nerve discharges show that the firing of certain axons active in the slow phase of nystagmus is shut off during the fast phase. From this it is concluded that inhibition of the motor output to the eyecup muscles always occurs centrally.
Tonic (upper) and phasic (lower) activity in muscle 19b during a slow-phase movement toward the midline and a fast return phase away from the midline. Tonic activity increases toward the end of the slow phase and is inhibited centrally during the fast. Phasic activity increases to a peak of 20 Hz. midway through the slow phase and again is inhibited centrally during the fast phase. The phasic potentials show little growth in amplitude by facilitation.
Unlike the phasic potentials of other muscles those in muscle 19b caused by a single fast axon show little change in amplitude by facilitation, and with extracellular leads are always recorded together with the tonic potentials. This is correlated with the lack of extreme 'Fibrillenstruktur' muscle fibres and by a greater similarity in the discharge of the slow and fast axons.
About 100 msec, before the onset of a fast phase toward the midline there is a burst of phasic muscle potentials (Fig. 7). These reach a peak frequency of 60 Hz. before the fast phase movement begins, and then continue at an ever-declining frequency during the fast phase and the next slow phase.
During a slow phase movement toward the midline the phasic activity gradually increases to reach a peak frequency of 20 Hz. midway through the traverse of the eyecup (Fig. 8). This frequency is maintained until activity is centrally inhibited before the start of the fast return phase.
Two slow axons supply muscle 20a. The frequency of discharge of both depends on the position of the stationary eyecup in the horizontal plane. During a slow forward phase away from the midline the tonic muscle potentials increase evenly in frequency to a maximum of 50 Hz. about mid-way through the traverse of the eyecup (Fig. 9). This frequency is then maintained until 50 msec, before the next fast phase, for the duration of which the activity is inhibited centrally. After the fast phase the muscle potentials resume at three-quarters of their maximum amplitude and gradually increase to full amplitude as the frequency again builds up during the next slow phase.
Tonic (upper) and phasic (lower) activity in muscle 20a during a slow-phase nystagmus movement away from the midline and a fast return phase toward the midline. The tonic muscle potentials gradually increase in frequency with little growth in amplitude by facilitation, and at high frequencies the firing becomes more even. By contrast the phasic potentials facúltate greatly and at high frequencies the firing becomes more irregular. The doublets and groups of potentials are associated with tremor movement of the eyecup. Activity is inhibited centrally just before the fast phase. The group of phasic potentials which occur after the fast phase are associated with the initial spurt of the next slow-phase movement.
Two fast axons also supply muscle 20a so that in all this muscle receives at least five axons: four involved in optokinetic movements and one involved only in withdrawal of the eyecup. The two fast axon discharges are usually not recorded when the eyecup is stationary. During a slow phase away from the midline the phasic potentials begin only when tonic activity has reached a high level (Fig. 9). At this time the phasic muscle potentials are barely visible above noise, but as they increase in frequency, they also increase in amplitude. This is not due to the wire electrode being pulled closer to the active muscle fibre, but is due to neuromuscular facilitation, for there is a correlation between the interval between two potentials and the increment of the second potential. This relation is confirmed with intracellular recording (Fig. 6A). The maximum frequency of 100 Hz. is not reached until near the end of the slow phase. The phasic activity, like the tonic, is inhibited centrally just before and throughout the fast return phase.
After the fast phase a group of potentials may occur which are associated with the initial rapid movement of the eyecup as it sets off on the next slow phase. This unusually high frequency at the beginning of a slow phase can be related to the burst of speed at the beginning of an optokinetic response when a rotation of the drum is first started. Records from muscle 20a, taken with both eyecups clamped to eliminate visual feedback, reveal a temporary small increase in frequency at the beginning of the slow phase. Whatever its nature, which may be post-inhibitory rebound of some kind, this burst is therefore a part of the central programme. In freely moving eyes the effect is easier to demonstrate and can, in addition, be attributed to the latency in the visual feedback loop, before the eyecup movement gets under way. Small overshoots in eyecup-movement records therefore arise from at least two sources.
When they occur at high frequencies, the phasic potentials caused by a single fast axon show a marked temporal patterning, with an unusually high number of closely spaced groups and pairs of impulses. This tendency is shown in an increased relative variance at the higher frequencies and is in direct contrast to the tonic activity which becomes more uniform at higher frequencies (Fig. 9). The pattern of impulses is not without effect, for the marked grouping in the later part of a slow phase is accompanied by tremor of the eyecup which is as large as that known to influence the perception of contrasting objects (Fig. 9). When both eyecups are clamped the intracellular activity in muscle 20a corresponds exactly to that recorded in a freely moving eyecup, so that whether the eyecup actually moves or not has no effect on the central mechanism which governs either the average frequency of motor impulses and hence eyecup position, or their grouping which governs tremor. When the seeing eyecup is clamped, the slip speed is constant throughout so that the onset of the phasic activity and its progressive growth and patterning cannot depend on the visual stimulus at that time. Muscle stretch is of no importance because the eye can be clamped in any abnormal position without effect on the motor impulse pattern. There seems to be no alternative to the conclusion that all aspects of the phasic activity, including its onset, are governed by a completely central mechanism which is dependent solely on the velocity and extent of the visual input since the last fast phase. Such a mechanism also governs the frequency reached by the slow motor impulses to this muscle.
When the slow phase is toward the midline (Fig. 10) the tonic activity begins just before the start of the fast-phase movement and reaches a peak frequency of 50–100 Hz. during this phase, declining slowly during the first quarter of the next slow phase. Similarly, the phasic activity begins about 50 msec, before the start of the fast phase and reaches a peak frequency of 200 Hz. during this phase, but then declines abruptly (Fig. 10). The phasic activity can be directly linked to the fast-phase movement away from the midline, especially when this movement is jerky, and must be considered to be the prime cause of the movement.
Activity in tonic fibres (upper) and phasic fibres (lower) in muscle 20a during a slow-phase nystagmus movement towards the nudline and a fast return phase away from the midline. Activity in both fibres is confined to bursts which begin just before the fast phase. The tonic activity reaches a peak frequency of 50–100 Hz. and declines slowly, whereas the phasic activity reaches 200 Hz. but declines abruptly. That the latter is a mechanical cause of the fast-phase movement is seen at times when the movement is jerky (inset).
Muscles 20b and 20c
These muscles consist of only eight to ten fibres and are each supplied by a fast and a slow axon, but since they lie close to other eyecup muscles there was always the possibility that activity recorded with extracellular electrodes had spread from the larger neighbouring muscles. Intracellular recordings can be made, but only from a clamped eyecup. Activity is then related to inferred eyecup movement by recording simultaneously from another muscle whose activity has been linked previously to eyecup movement.
Tonic activity in muscles 20 b and 20 c occurs rather irregularly at a frequency of about 10 Hz. throughout optokinetic movements in the horizontal plane (Fig. 11A). Phasic activity is also irregular but that in muscle 20 b may show a slight increase in frequency during a slow-phase movement away from the midline and a corresponding decrease during movement towards the midline (Fig. 11B).
(A) Intracellular activity in muscle 20b (middle trace) recorded simultaneously with that in muscle 20a (lower trace) during optokinetic responses of the nght eyecup. Ramp movements of the drum (upper trace downwards is towards midline) cause no change in the tonic activity of 20b but that of 20a is changed. (B) Phasic responses of muscle 20a (upper trace) recorded with the phasic activity in 20b (lower trace) which changes relatively little during nystagmus.
Tonic activity in muscle 21 is present in the stationary eyecup at a frequency which depends on the horizontal position of the eyecup in space. During a slow-phase movement towards the midline the activity increases evenly to about 40 Hz. (Fig. 12) and is inhibited centrally just before and for the duration of the fast return phase. Afterwards the muscle potentials resume at their previous amplitude. Phasic activity begins only when the tonic activity has reached a high frequency and when more than half the slow-phase movement has occurred (Fig. 12). The facilitating potentials increase to a peak frequency of 200 Hz. but are inhibited centrally just before the start of the next fast phase. As for the phasic activity of muscle 20a during movement in the opposite direction, the muscle action potentials, caused by the dis-charge of a single fast axon, tend to occur in groups and doublets which are associated with tremor of the eyecup. At high frequencies the interval scatter increases. This is in direct contrast to intervals between tonic potentials, which become more uniform (Fig. 12).
Tonic (upper) and phasic (lower) activity recorded from muscle 21 during a slow forward-phase movement toward the midline. During the slow phase the tonic potentials show an even increase in frequency but are inhibited centrally during the fast phase. Phasic activity begins only when the eyecup movement is half completed and shows an erratic increase in frequency up to 200 Hz. Again it is inhibited centrally before the start of the fast phase. Scatter in the instantaneous frequency curve for phasic activity increases at the high frequencies, in contrast to that for the tonic activity which becomes more regular.
During a slow-phase movement away from the midline muscle 21 is inactive until just before the onset of a fast return phase towards the midline, when there is a burst of activity in the slow axon (Fig. 13). This reaches a frequency of 60 Hz. and declines gradually during the remainder of the fast phase and the first quarter of the next slow phase. Tonic activity is then completely absent until the start of the next fast phase.
Tonic (upper) and phasic (lower) activity in muscle 21 during a slow-phase movement away from the midline and a fast return phase toward the midline. Both types of activity occur as bursts before the onset of the fast phase. Tonic activity reaches a peak frequency of 60 Hz. and slowly declines while phasic activity, the prime cause of the movement, reaches a peak of 200 Hz. and declines abruptly.
Similarly, no phasic activity is recorded during the slow forward movement away from the midline until a burst occurs 50–100 msec, before the start of the fast return phase (Fig. 13). The frequency initially reaches 200 Hz. and is maintained briefly at 100 Hz. before declining rapidly. This activity is the main cause of the fast-phase movement.
During a slow-phase movement of the eyecup away from the midline the frequency of the slow axon discharge to muscle 22 increases only slightly from 10–20 to 20–25 Hz. (Fig. 14). Just before the fast return phase the activity is inhibited centrally but is suppressed for only the first 100 msec, of the 300 msec, long fast phase. During the last two-thirds of the fast phase a group of muscle potentials occur at a frequency of 25–30 Hz., which is higher than the maximum achieved during the slow phase.
Tonic (upper) and phasic (lower) activity in muscle 22 during a slow-phase movement away from the midline and a fast return phase toward the midline. The tome potentials gradually increase in frequency during the slow phase and are inhibited centrally during the fast. A burst of phasic activity begins 100 msec, before the start of the fast phase and reaches a peak of 50 Hz.
During a slow-phase movement towards the midline there is no change in tonic background activity of 10–20 Hz., but during a fast return phase the frequency is raised to 50 Hz. (Fig. 15). Phasic activity in muscle 22, due to the discharge of a single fast axon, is limited to a few potentials at a low frequency, during the greater part of slow-phase movements in either direction. However, about 100 msec, before a fast phase towards the midline a burst of potentials occurs which approaches a peak frequency of 50 Hz., lasts for the duration of the fast phase and declines during the first 200 msec, of the next slow phase (Fig. 14). There is also a burst of a few facilitating muscle potentials at a frequency of about 20 Hz. starting after a fast-phase movement away from the midline has been initiated, primarily by muscle 20 a (Fig. 15).
Tonic (upper) and phasic (lower) activity in muscle 22 during a slow-phase movement toward the midline and a fast return phase away from the midline. No trend is apparent in the tonic activity during the slow phase, but during the fast phase the frequency is raised. There 13 a burst of phasic activity at a low frequency only after the start of the fast phase.
Muscle 23 a
The discharge of the slow axon to muscle 23 a is more regular than that of the slow axon to muscle 22. Throughout a slow-phase movement away from the midline the frequency declines from 30 to 15 Hz. (Fig. 16). Activity then increases in amplitude and frequency to reach a peak of 60 Hz. during the fast return phase, but declines gradually once more during the next slow phase. Throughout a slow phase towards the midline a steady discharge at a frequency of 20–25 Hz. is maintained, but is inhibited centrally 100 msec, before the start of the fast phase, and suppressed for 150 msec, of this phase (Fig. 17). During the latter half of the fast phase the tonic frequency is raised to 50 Hz., but this then declines rapidly to 20 Hz. during the next slow phase.
Tonic (upper) and phasic (lower) activity in muscle 23 a during a slow-phase movement away from the midline and a fast return phase toward the midline. Tonic activity declines gradually during the slow phase but is raised in frequency during the fast. Phasic activity is limited to two short bursts at the beginning and end of the fast phase.
Tonic activity in muscle 23a during a slow-phase movement away from the midline and a fast return phase toward the midline. The activity is relatively constant at a frequency of 25–30 Hz. during the slow phase but is inhibited centrally during the first half of the fast phase. Phasic activity is absent.
Phasic activity in this muscle is completely absent during a slow phase in either direction but at the beginning and end of a fast phase towards the midline there is a short burst of facilitating potentials (Fig. 16).
Muscle 23 b
No change is apparent in the irregular slow axon discharge to this muscle of about 10 Hz. during slow-phase movements in either direction (Figs. 18,19). During a fast phase towards the midline the frequency is raised to 20–50 Hz., and correspondingly during the first half of a fast phase away from the midline the discharge is centrally inhibited. Apart from this, tonic activity is continuous in muscle 23 b throughout the whole cycle in either direction.
Tonic activity in muscle 23 b during a slow-phase movement away from the midline and a fast return phase toward the midline. The activity is irregular at 10 Hz but is raised in frequency during the fast phase. Phasic activity is absent.
Tonic (upper) and phasic (lower) activity in muscle 23b during a slow-phase movement toward the midline and a fast return phase away from the midline. Tonic activity occurs irregularly at 10 Hz. during the slow phase but is inhibited centrally during the fast. At the end of the fast phase there is a burst of phasic activity which may decelerate this movement.
Phasic activity occurs only as a burst of rapidly facilitating potentials at the end of a fast-phase movement away from the midline (Fig. 19). This burst usually consists of five potentials at a frequency of 20–30 Hz. at a time when the fast-phase movement is almost complete. No eyecup movement can be directly correlated with this activity which may, however, contribute towards the deceleration of fast-phase movement.
The activity of the various eyecup muscles during horizontal optokinetic movements is summarized in Fig. 20 and Tables 1 and 2. The illustrations cover the simultaneous activity of twenty motor axons in a normal response.
Slow-phase optokmetic movement away from midline
Slow-phase optokinetic movement towards midline
Summary of eyecup muscle activity during horizontal optokinetic movements; phasic p, tonic t. In (A) the slow-phase movement is toward the midline; in (B) away from the midline. The frequency of muscle activity is represented vertically on an approximate logarithmic scale. The time scale for the fast phase is expanded relative to that for the slow phase.
Eight of the nine muscles always collaborate in their tonic activity to form the suspension system which determines the resting position of the eyecup. Muscle 19 a is active only during withdrawal of the eyecup and when the eyecup is retained in its socket. In a stationary eyecup only the tonic fibres innervated by slow axons are active (except for a few phasic fibres in muscle 21 causing horizontal tremor). Each particular efferent pattern to eight of the nine muscles corresponds to only one eyecup position.
No movement is made without a change in activity of several muscles. Slow movements are brought about by changes in the frequency of the slow axons. For larger or faster movements the phasic system is recruited. This is the situation in a slow forward phase of nystagmus. Rapid movements, such as the fast return phase of nystagmus, are brought about primarily by the phasic system, which is also responsible for tremor. Some muscles show greater activity during visually controlled movements in particular directions. Slow horizontal movement towards the midline is correlated with increased activity in muscles 21 and 19b, and movement away from the midline by increased activity only in muscle 20a. With other movements, however, such as the fast flick-back in optokinetic nystagmus it is difficult to demonstrate which if any of the muscles is the chief cause of the movement, because several change their activity simultaneously. It is more correct to consider all the eyecup muscles as a group than to ascribe limited functions to individual muscles.
The optokinetic response clearly depends on a central programme for each stimulus situation. Moreover, the programmes for opposite directions of the optokinetic response in the horizontal plane are quite different, not merely mirror images of each other. There is a remarkable constancy in the general form of the central programme of nerve impulses when the same stimuli are applied to different crabs; the principal differences between crabs lie not in the occurrence of different impulse sequences in different axons, but in the frequency of the impulses in corresponding parts of the pattern. This is in agreement with behavioural observations which show that eyecup movements are consistent between animals, although the quantitative ratio of output to input, the velocity gain, and the region of the total possible traverse over which the nystagmus movements occur, vary over a wide range. It has been repeatedly confirmed that every position of each eyecup, and every movement, is the consequence of a patterned stream of motor impulses which depends solely upon the sensory stimulus, while the brain, in generating this pattern, is indifferent to the position or movement of the eyecup or even to its presence. Although cuticular mechanoreceptor sensilla are present on the eyecup and are abundant in the flexible joint membrane (Sandeman, 1964), and afferent fibres in the optic tract carrying mechanoreceptive and proprioceptive information from the eyecup region are reported (Waterman & Wiersma, 1963) all experiments have failed to reveal their utilization in the immediate control of any eyecup response. A change in the speed of the visual stimulus causes an appropriate change in the rate at which the central programme appears.
Muscle structure and function
The muscles in the eyecup of the crab consist of two basic types of fibre, 'Fibrillen-struktur' and 'Felderstruktur' but intermediate types are also present. The exact correlation of the structural with the functional observations must await the marking of individual fibres after electrical recording, and their subsequent histological identification, because the various types of muscle fibres are not clearly separated anatomically as they are, for instance, in the accessory flexor muscle of the meropo-dite of the leg (Dorai Raj & Cohen, 1964). Nevertheless, a good deal of evidence suggests adherence to the general rule found for other crustacean muscles that the fast axons supply the 'Fibrillenstruktur' fibres while the slow axons supply the 'Felderstruktur' ones. For example, in muscle 23b the tonic activity is only recorded from the superficial fibres which are known to be the 'Felderstruktur' fibres histologically. In muscle 19b, where there are intermediates but no extreme 'Fibrillenstruktur' fibres present, the phasic activity differs from that in other muscles. The phasic junction potentials of 19 b have a slower rise time, a longer time constant of decay and show little facilitation. This could be caused by the fast axon supplying the muscle fibres of intermediate type.
A feature of the detailed anatomy, as revealed by repeated probing of numerous muscle fibres in each preparation, is the diversity of the muscle fibres in a small space. Although all nine muscles occupy a region only a few cubic millimetres in extent, each muscle contains tonic and phasic fibres which merely represent the extremes of a wide spectrum of fibre types. The slow and fast motor axons are distributed in a pattern which imposes further diversity. There are twenty to thirty types of muscle fibres in the eyecup out of a total population of about 150. This diversity seems to be reasonably constant from crab to crab so far as the sampling technique with microelectrodes allows one to say; certainly the distribution of fast and slow axons is anatomically similar in all specimens.
The functional need for such diverse peripheral neuromuscular mechanisms appears to lie in the wide variety of eyecup movements, in different directions and at different speeds. With only a few motor axons to each eyecup muscle the gradation of contraction must depend more on frequency coding than on the recruitment of motor units. The existence of two muscle fibre types, phasic and tonic, provides a low-speed and a high-speed range over which the frequency code can act.
, (
Differences in muscle fibre properties as a factor in 'fast' and 'slow' contraction in Carcinus
Excitation and inhibition in crab muscle fibres
Jr. (
Mechanical and electrical responses of sigle innervated crab-muscle fibres
J. Physiol
https://doi.org/10.1113/jphysiol.1965.sp007712
Burrows
Horridge
Eye-cup withdrawal in the crab Carcinus and its interaction with the optokinetic response
The skeletal musculature of the blue crab, Callinectes sapidus, Rathbun
Smithsonian misc. Collns
Muscle fibres and efferent nerves in a crustacean receptor muscle
Q. Jl microsc. Sci
Dorai Raj
Structural and functional correlations in crab muscle fibres
The structure of slow and fast extrafusal muscle fibres in the extraocular muscles and their nerve endings in the guinea pig
J. cell. comp. Physiol
https://doi.org/10.1002/jcp.1030580108
Optokinetic memory in the crab, Carcinus
Perception of edges versus areas by the crab Carcinus
Tome and phasic systems in parallel in the eye-cup responses of the crab Carcinus
D. C.
Nervous control of the optokinetic responses in the crab Carcinus
Proc. Roy. Soc
C. A. G.
Excitation at neuromuscular junctions in Crustacea
Inhibition at neuromuscular junctions in Crustacea
Neuro-muscular transmission in crabs
An observation on the speed of nystagmus
Acta otolaryng., Stockh
Die Innervation der tetanischen und tonischen Fasem der quergestreiften Skelet-muskulatur der Wirbeltiere
Anat. Anz
Functional distinction between oculomotor and optic nerves in Caranus (Crustacea)
Nature, Land
The vascular circulation in the brain, optic lobes and thoracic ganglia of Caranus
Proc. Roy Soc. B
A sensitive position measuring device for biological systems
Electrical responses in Decapod Crustacean visual systems


The Billy the Kid Target Stand is perfect if you need to hold any size shooting target or multiple targets in windy environments.
Setup is easy with no tools required. Each base is equipped with a sharp 10-inch stake. Just push the stakes into soft to medium soil to create your base, spaced according to the width of your target or backer. Then insert a 1×2 wood strip into each base to create your frame. Attach your target to the frame and you're ready to shoot.
The stand collapses to a minuscule 0.12 square feet for storage and transport to the gun range. It weighs a measly 4.3 pounds. Its small footprint makes it one of the most portable stand designs that is easy to stash when not in use.
Using 1×2 wood strips as the framing material contributes many benefits to the overall function of the target stand: they are widely available, cheap to replace, safe to shoot, easy to staple or clamp to, resilient to any caliber of bullet, and light-weight.
Try it out for 100 days. If it is not the most functional, portable, and easy to use target stand, return it for a 100 percent refund.
The Billy the Kid Stand weighs in at only 4.3 pounds and can be easily carried in one hand. If you are looking for the most compact and portable stand, this is it.
Store it under your truck seat—right beside your gun—and you'll always be prepared for a shoot.
In optimal soil (soft to medium), the Billy the Kid Target Stand will provide a solid target base. Each base is equipped with a massive 10 inch stake. The stake is cut at a sharp 60-degree angle (with respect to the ground plane) so the point can be easily driven into the ground.
We do not recommend hammering the stand directly—you'll muck it up. Instead, insert a 6" 1×2 strip or a ¾ × 1-½ steel bar or tubing. You can then hammer on this buffer without damaging the stand. Depending on soil hardness, a 2–5 pound hammer may be needed.
First, insert a 1x2 strip into the auto-brace. This strip will act like your shovel handle. Next, step onto the stand's base like you would a spade shovel and work the stake into the ground.
After the stand is anchored 10" into the ground, it will not move no matter how much the wind blows. The 1x2 vertical frame strips will snap before the stand is ripped from the ground. If this happens, it is time to pack it up and seek shelter.
When properly staked, the Billy the Kid Stand will always out perform a surface-mount stand in high wind. The only caveat is that optimal soil density is required. But that is usually not a problem unless you are shooting in a rock pit.
If staked in soft soil, the frame may not be rigid enough to hold a large target or set of targets. Increasing the stand's stance may add stability. Simply slide a 1x2 strips through one or both bases. Additionally, you could stake or weight these extender strips as well for maximum stability.
Now you have your target base anchored 10 inches into the Earth—and it isn't going anywhere. But that won't do you any good if your vertical wood frame on top of your base is flopping around in the wind. A bullseye that is swaying left and right is not conducive to precision shooting.
This is where the Auto-Brace will save you frustration and time. It was designed by Target Meister. We make it standard on all of our steel stands because it is a huge improvement over other designs. If you're shooting from the hip, maybe you won't care. But Auto-Braces are a must-have for shooters who do not want their targets to move; especially competition shooters.
When testing your shotgun's pattern, it is often ideal to use a large target backing. When using a single large backer, multiple "spread" shots from varying distances can be quickly compared. The Billy the Kid Target Stand is ideal for holding a large backer for shotgun pattern testing.
Understanding your shotgun's pattern is an informative video demonstrating patterning at several distances using 00 buckshot. The close-range distances and large shot used in the demo pertain mostly to self-defense situations. Testing patterns using bird shot at 50 yards would require a much larger target.


text:
Harvard Business School Right arrow Executive Education Right arrow HBS Experience
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What is Executive Education?
Though it comes from within, transformation often requires a catalyst. For more than 200,000 business leaders, HBS Executive Education has been that catalyst. Here, you're fully immersed in a transformational living-learning experience, networking with executives from around the world, and engaging in programs led by experienced HBS faculty. It's a holistic experience that will enrich your career—and your life.
Many of our alumni and participants call HBS Executive Education a "life-changing experience." That's because in addition to building your expertise, you'll examine where you've been—and where you want to take your career and your organization.
From case study discussions and small group projects to simulations and dynamic lectures, you'll have ample opportunities to deepen your knowledge, broaden your skill set, and collaborate with your peers.
Our virtual programs bring an unparalleled learning experience to you, allowing opportunities to learn, contribute and socialize in a variety of ways.
During lively discussions with your living group, lunchtime conversations at the Chao Center, and evening excursions to Harvard Square, you'll make new connections and form lasting relationships with your colleagues.
Identify the program that is right for you.
Use our Program Finder, download our Program Calendar or contact a Program Advisor
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Yuyuan Garden is located near the City God Temple in Shanghai. It is a well-preserved old garden which took about 20 years to build since 1559 by a rich official Pan Yunduan during late Ming Dynasty.
Covering 20,000 skm, Yuyuan Garden is constructed with houses, pavilions, bridges, bonsais, old trees, stages etc. with typical Suzhou gardens style. No matter where you go, you can get a good photo in the garden. Water, buildings, flowers, plants formed an incredible landscape. Moreover,. there are exhibition halls to exhibit the history of the garden.
Outside Yuyuan Garden, it is bi bazaar where travellers can buy all sorts of souvenirs and taste typical Shanghai food, particularly Xiaolongbao here. It is also in the center of the Shanghai old town, travelleres can wander from Yuayuan Garden to view traditional Shanghai old houses, Shikumeng.
Entrance fee for the Yuyuyan Garden is CNY45.


text:
Q: Flash AS3 Clone, Drag & Drop I am a teacher and with the help of some of you, I managed to create very basic word game for kids where they are able to create words from letters. SWF | FLA
I have, however, been unable to continue to drag and drop the letters once they have been cloned from their originals on the side of the stage. Is anyone able to advise how I might be able to add this functionality to my existing code?
import flash.display.MovieClip;

for (var i=1; i<27; i++)
{
    this["object" + i].addEventListener(MouseEvent.MOUSE_DOWN, onStart);
    this["object" + i].addEventListener(MouseEvent.MOUSE_UP, onStop);
}

var sx = 0,sy = 0;

function onStart(e)
{
    sx = e.currentTarget.x;
    sy = e.currentTarget.y;
    e.currentTarget.startDrag();
}

function onStop(e)
{
    if (e.target.dropTarget != null &&
    e.target.dropTarget.parent == dest)
    {
        var objectClass:Class =
        getDefinitionByName(getQualifiedClassName(e.currentTarget)) as Class;
        var copy:MovieClip = new objectClass();
        this.addChild(copy);
        copy.x = e.currentTarget.x;
        copy.y = e.currentTarget.y;
    }

    e.currentTarget.x = sx;
    e.currentTarget.y = sy;
    e.currentTarget.stopDrag();
}

I would also love to include a 'bin' where kids can drag letters if they do not wish to have them on stage any more. Any ideas for how I could add this would be greatly appreciated.
Many thanks.

A: If you want similar behavior for dragged object (i.e after dragging, a copy is created)
add these line to your onStop(e) like so,
copy.addEventListener(MouseEvent.MOUSE_DOWN, onStart);
copy.addEventListener(MouseEvent.MOUSE_UP, onStop);

But if you want only dragging and prevent a copy, then either create another function say dragCopiedObject() and apply the logic of dragging and not copying in that new function
or
identify between copied or original object in the same onStop(e) function and prevent from copying.
If you don't get it then let me know I will explain it to you in detail.
For dropping copied objects inside a bin, after dragging is stopped, check collision with bin object. for more info see,
copiedObject.hitTestObject(binObject)
For e.g.
if(copiedObject.hitTestObject(binObject)) {

     removeChild(copiedObject);
}

UPDATE: To identify between copied objects use name property like so:
copy.name = "copy";
I have modified your code,
function onStop(e)
{
    if ( e.target.dropTarget != null &&
         e.target.dropTarget.parent == dest &&
         e.currentTarget.name != "copy"         ) //This is newly added
    {
        var objectClass:Class =
        getDefinitionByName(getQualifiedClassName(e.currentTarget)) as Class;

        var copy:MovieClip = new objectClass();
        copy.name = "copy"; //This is newly added
        this.addChild(copy);
        copy.x = e.currentTarget.x;
        copy.y = e.currentTarget.y;

        e.currentTarget.x = sx;
        e.currentTarget.y = sy;

        copy.addEventListener(MouseEvent.MOUSE_DOWN, onStart);
        copy.addEventListener(MouseEvent.MOUSE_UP, onStop);
    }

    e.currentTarget.stopDrag();
}

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It is the final week of August, our birthday and pledge month and we would like to say thanks to those who have pledged and donated to support the work of Bush Radio of Africa's oldest community radio station project.
There is still time to donate and help us to continue.
For more information contact Bush Radio on 021-448 5450.
How do you feel about South Africa?
We asked people how they feel about South Africa. Find out where they are getting their information by watching the "Where do you get your information?" VideoVox.


text:
Bruno da Cunha Araújo Pereira (Recife, 15 de agosto de 1980 – Atalaia do Norte, 5 de junho de 2022) foi um indigenista brasileiro e servidor de carreira da Fundação Nacional do Índio (Funai). Foi considerado uns dos maiores especialistas em indígenas isolados ou de recente contato do país e exímio conhecedor do Vale do Javari.

Infância e educação
Bruno nasceu no Recife e tinha dois irmãos. Ele era filho de um casal de paraibanos que veio morar na capital pernambucana.

Foi aluno do antigo colégio Contato, onde se formou no ensino médio em 1998, na unidade do bairro de Boa Viagem, na Zona Sul do Recife. Bruno começou a estudar jornalismo na Universidade Federal de Pernambuco (UFPE) em 2000, mas deixou o curso em 2003.

Carreira
Depois de desistir da faculdade, Bruno trabalhou por um período no Instituto Nacional do Seguro Social (INSS) no Recife. Após conseguir um trabalho no programa ambiental da Usina Hidrelétrica de Balbina, foi para a região da Amazônia.

Após alguns anos na hidrelétrica, foi aprovado no concurso da Fundação Nacional do Índio (Funai) e escolheu ir para o Vale do Javari, a terra indígena que tem a maior concentração de indígenas isolados do mundo. Em 2018, Pereira se tornou o coordenador-geral de Índios Isolados e de Recém Contatados da Funai, quando chefiou a maior expedição para contato com índios isolados.

Em 2019, ele liderou a maior expedição para contato com índios isolados dos últimos 20 anos. Entretanto, após pressão de setores ruralistas ligados ao Governo Jair Bolsonaro, foi exonerado do cargo em outubro daquele ano pelo então secretário executivo de Sergio Moro no Ministério da Justiça, Luiz Pontel.

De acordo com entidades indígenas, Bruno era constantemente ameaçado por garimpeiros, madeireiros e pescadores.

Bruno também coordenou um projeto para equipar indígenas visando à defesa de seu território, por meio de drones, computadores e treinamento. Bruno Pereira afirmava que os invasores se sentiam mais à vontade em decorrência da permissividade do poder público, tendo a vigilância passado por um processo de enfraquecimento contínuo.

Vida pessoal
Bruno era casado com a antropóloga Beatriz Matos, com quem teve dois filhos. Ele também teve um terceiro filho de outro relacionamento. Era torcedor do Sport Club do Recife.

Assassinato

Ver também

Chico Mendes
Dorothy Stang

Naturais do Recife
Alunos da Universidade Federal de Pernambuco
Ativistas dos direitos indígenas do Brasil
Brasileiros assassinados
Assassinados na década de 2020 no Brasil
Fundação Nacional dos Povos Indígenas
!Mais Teoria da História na Wiki (Povos originários)
Indigenistas

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Alexandria's first Taco Bell with mixed drinks, beer and wine is opening soon.
There is now an official opening date for Taco Bell Cantina, the only Taco Bell in the region that will sell beer and wine.
Taco Bell Cantina at 417 King Street in Old Town Alexandria will open Friday, Dec. 21.
Taco Bell Cantina will sell sangria and twisted freezes in addition to beer, wine, tacos, burritos and other traditional Taco Bell items.
Hours will be 7 a.m. to 2 a.m., with outdoor dining closing at 11 p.m.
The liquor license for this location is still pending, according to a report, so it is not clear if this Taco Bell Cantina will be selling liquor on its opening date.


SANTA CLARITA, Calif.—Shots America announced the manufacturer will host an In-House Trade Show to introduce more than 555 new products. The event is slated for Jan. 7-12 at the American offices in Santa Clarita, Calif., just 20 minutes from the ANME Founders Show in Burbank, Calif. For all the invited guests Shots arranges free transportation to the showroom and back from the hotel or location. Attendees can expect the following: • Upwards of 200 Items will be Sold at Below Cost on a first come, first served basis (This offer is only valid during their sales week, and you must attend in person to profit from these offers.) • Super in-house show promotions • Debut of new brands, including Bottom Line, Rich, brown leather Ouch! items, Vive, S-Line Dolls, 3D Dolls, Sono and RealRock Translucent and Extreme The show runs each day 8 a.m. to 6 p.m. Those unable to attend those hours can scheduled a personal appointment with their sales manager. To see the announced products, visit ShotsAmerica.com. If you don't have an online account yet you can apply trough ShotsAmerica.com/b2b where you will get drect access to all the prices for the products. Follow Facebook.com/shotsamerica and Twitter.com/shots_america for all the info during the trade show.