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Most scientist accept the RNA world hypothesis, which states that RNA was the first biological molecule due to its ability to copy itself and pass along genetic traits. However, Nicholas Hud, a chemist at the Georgia Institute of Technology, wasn’t convinced.
A recent article in WIRED, courtesy of Quanta Magazine, discusses Hud’s experiment with the building blocks of RNA. The experiment made a breakthrough with the discovery of a chemical recipe that points to the existence of a molecule that might pre-date RNA.
Quanta interviewed Stephen Freeland, director of UMBC’s interdiscipinary studies program, for the article. “In my opinion, nothing like this has been seen before,” Dr. Freeland said, before going on to say that the experiment leads to conceptual progress, even if it did not use the exact components of the unknown molecule.
Read the entire article at WIRED.com.
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Let's say there is a feature on your website that only gets used 5% of the time. That feature requires some HTML, CSS, and JavaScript to work. So you decide that instead of having that HTML, CSS, and JavaScript on the page directly, you're going to Ajax that stuff in when the feature is about to be used.
We'll need to make three Ajax requests. Since we don't want to show anything to the user until the feature is ready to go (plus they all kinda rely on each other to work right) we need to wait for all three of them to be complete before proceeding.
What's the best way to do that?
Ajax calls in jQuery provide callbacks:
$.ajax({
statusCode: {
url: "/feature",
success: function() {
// Ajax success
}
}
});Or the "Deferred" way, this time using a shorthand $.get() method:
$.get("/feature/").done(function() {
// Ajax success
});But we have three Ajax requests we're needing to perform, and we want to wait for all three of them to finish before doing anything, so it could get pretty gnarly in callback land:
// Get the HTML
$.get("/feature/", function(html) {
// Get the CSS
$.get("/assets/feature.css", function(css) {
// Get the JavaScript
$.getScript("/assets/feature.js", function() {
// All is ready now, so...
// Add CSS to page
$("<style />").html(css).appendTo("head");
// Add HTML to page
$("body").append(html);
});
});
});This successfully waits until everything is ready before adding anything to the page. So by the time the user sees anything, it's good to go. Perhaps that makes some of you feel nauseated, but I've done things that way before. At least it makes sense and works. The problem? It's slow.
One request ... wait to be done ... another request ... wait to be done ... another request ... wait to be done ... go.
It would be faster if we could do:
All three requests in parallel ... wait for all three to be done ... go.
We can use a bit of Deferred / Promises action to help here. I'm sure this is some JavaScript 101 stuff to some of you but this kind of thing eluded me for a long time and more complex Promises stuff still does.
In our simple use case, we can use jQuery's $.when() method, which takes a list of these "Deferred" objects (All jQuery Ajax methods return Deferred objects) and then provides a single callback.
$.when(
// Deferred object (probably Ajax request),
// Deferred object (probably Ajax request),
// Deferred object (probably Ajax request)
).then(function() {
// All have been resolved (or rejected), do your thing
});So our callback-hell can be rewritten like:
$.when(
// Get the HTML
$.get("/feature/", function(html) {
globalStore.html = html;
}),
// Get the CSS
$.get("/assets/feature.css", function(css) {
globalStore.css = css;
}),
// Get the JS
$.getScript("/assets/feature.js")
).then(function() {
// All is ready now, so...
// Add CSS to page
$("<style />").html(globalStore.css).appendTo("head");
// Add HTML to page
$("body").append(globalStore.html);
});My use-case example above is a 5% feature. Keep the page lighter for the 95% of users who don't use the feature, and have it be a relatively quick add-on for those that do.
Another situation might be a cut-the-mustard situation where you add in additional features or content to a page in certain situations, as you decide. Perhaps do a matchMedia test on some media queries and determine the device's screen and capabilities are such that you're going to include some extra modules. Cool, do it up with some parallel Ajax calls!
Multiple Simultaneous Ajax Requests (with one callback) in jQuery is a post from CSS-Tricks
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Is the death penalty slowly dying?
The United States is one of a dwindling number of nations that stills executes its citizens (thirty nine individuals in 2013). That job has recently gotten harder.
Since the death penalty was reinstated in 1976, the US has used a cocktail of three lethal drugs as its preferred method of execution.
However, since the Danish manufacturer of one of these drugs declared that it would no longer sell their product to US prisons, states have been scrambling for alternatives.
The Missouri State Department of Corrections chose to substitute another drug, compounded pentobarbital, but a Federal judge blocked the pharmaceutical company’s attempt to supply the drug. The lawsuit declared that execution by compounded pentobarbital would cause
“severe, unnecessary, lingering and ultimately inhumane pain.”
Faced with the same problem, Virginia attempted to make death by electric chair the default method of execution under state law. The bill failed earlier this week.
Finally, some states have abolished the death penalty altogether. Maryland outlawed the punishment last May, making it the eighteenth state to do so. Washington declared a state moratorium on Tuesday.
The death penalty inspires passion on both sides of the aisle, and with good cause.
Join the debate, and tell us: is it every okay for the government to kills its own citizens? And if somebody is going to die, does it matter how it happens?
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