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The Warriors need more of this Kevon Looney going forward

first_imgClick here if you’re unable to view the gallery on your mobile device.OAKLAND — DeMarcus Cousins crumbled in front of the Warriors bench just three and a half minutes into Game 2, clutching his left quad and wincing in pain.Kevon Looney watched from his seat, eerily familiar with what Cousins had just endured. After Cousins clawed back from ACL surgery this year only to suffer a likely season-ending torn quad early in the first quarter Monday night, his role will be filled in large part by …last_img read more

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Self-Correcting RNA: Is It a Missing Link?

first_imgA team of Russian scientists at Rutgers discovered a remarkable phenomenon: RNA that proofreads itself during its own synthesis.  The work was reported in Science1: “We show that during transcription elongation, the hydrolytic reaction stimulated by misincorporated nucleotides proofreads most of the misincorporation events and thus serves as an intrinsic mechanism of transcription fidelity.”  It has already been known that DNA transcription and translation includes a whole suite of error-correcting mechanisms, but this is the first instance of RNA self-correction.    The researchers did not comment on the evolution of this capability except to state that it “is likely evolutionarily conserved” (i.e., unevolved in all living organisms), and that in an RNA-protein world, a “proofreading and repair mechanism similar to the one described here could have allowed a large RNA genome of the last common universal ancestor to exist.”  This is because without an accurate proofreading mechanism even in an RNA world, duplication fidelity would have been too low for evolution: “the relatively low fidelity of RNAP-catalyzed synthesis could not have been sufficient for stable maintenance of large RNA genomes in the absence of cleavage factors.”    Patrick Cramer (Gene Center Munich), however, writing in the same issue of Science,2 launched their final, speculative paragraph into a story of how this RNA must be a missing link.  Starting with the admission that “Precision can be vital,” Cramer immediately invoked the E word: “cells have evolved processes for proofreading and correction to shut down the propagation of errors” in the DNA-to-protein pathway.  Referring to the work by Zenkin et al., he said, “This finding helps to explain the fidelity of gene transcription and suggests that self-correcting RNA was the genetic material during early evolution.”    But how, exactly, could that have come about?  In his missing-link story, notice how many times Cramer used speculation words like could, probably and suggests compared to the hard requirements of reality:The discovery of self-correcting RNA transcripts suggests a previously missing link in molecular evolution.  One prerequisite of an early RNA world (devoid of DNA) is that RNA-based genomes were stable.  Genome stability required a mechanism for RNA replication and error correction during replication, which could have been similar to the newly described RNA proofreading mechanism described by Zenkin et al.  If self-correcting replicating RNAs coexisted with an RNA-based protein synthesis activity, then an early RNA-based replicase could have been replaced by a protein-based RNA replicase.  This ancient protein-based RNA replicase could have evolved to accept DNA as a template, instead of RNA, allowing the transition from RNA to DNA genomes.  In this scenario, the resulting DNA-dependent RNA polymerase retained the ancient RNA-based RNA proofreading mechanism.    Whereas an understanding of RNA proofreading is only now emerging, DNA proofreading had long been characterized. DNA polymerases cleave misincorporated nucleotides from the growing DNA chain, but the cleavage activity resides in a protein domain distinct from the domain for synthesis.  The spatial separation of the two activities probably allowed optimization of two dedicated active sites during evolution, whereas RNA polymerase retained a single tunable active site.  This could explain how some DNA polymerases achieve very high fidelity, which is required for efficient error correction during replication of large DNA genomes.Of course, being only a “scenario” for how proofreading “could” have evolved, Cramer offered no evidence, lab or otherwise, for such a self-correcting RNA “missing link.”  For a discussion of problems with the RNA-world scenario, see the 07/11/2002 entry.1Zenkin, Yuzenkova and Severinov, “Transcript-Assisted Transcriptional Proofreading,” Science, 28 July 2006: Vol. 313. no. 5786, pp. 518 – 520, DOI: 10.1126/science.1127422.2Patrick Cramer, “Perspectives: Molecular Biology: Self-Correcting Messages,” Science, 28 July 2006: Vol. 313. no. 5786, pp. 447 – 448, DOI: 10.1126/science.1131205.Was blindness ever so dark as to look design in the eye, and attribute it to mindless chance?  The blind see naught but their own imaginations.  Cramer took an incredibly wondrous phenomenon (imagine! self-correcting code) and weaved a purely fictional tale about how it emerged from The Ancient Soup.  Yet this is the myth that our culture only allows to be heard by students in public schools, because any other explanation, such as design, is classified as “religion” (along with, presumably, rocket-launching Hezbollah terrorism).  In the same issue of Science was a very positive book review of a new work about Richard Dawkins, the rabidly atheistic Darwinist who subscribes to the Ancient Soup myth or something very like it: reviewer David C. Queller says, “Dawkins spills his own dirty, obscene secret, again no less powerful now that we have known it for 30 years.  All flesh is survival machinery, and the survival it promotes is that of our selfish genes.”    If this makes you angry, then it is time to take back science from the powers of darkness, obscenity, and selfishness that swept in like a flood after Darwin.  What would the original founders of the American Association for the Advancement of Science, like Joseph Henry, think of what has become of their honorable institution?(Visited 32 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more

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First Galaxies Fast and Compact

first_imgThe old picture: after the big bang, matter is diffuse.  Out of the darkness, stars slowly begin to form, as the first galaxies take shape.  Galaxies start out large and slowly grow more dense and structured over billions of years.  The new picture: the first galaxies are very compact and dense, spinning rapidly, with stars forming at a prodigious rate.  The compact galaxies spin twice as fast as “mature” galaxies closer to us.    This change in thinking was expressed by reports found on Science Daily and Space.com.  A look at the original paper in Astrophysical Journal Letters puts the surprises in context.1  Pieter van Dokkum et al made observations with the Hubble Space Telescope and the Keck Observatory at redshift z=2.3 in near-infrared light.  They found nine galaxies that seemed more compact than usual and did not find any of the large galaxies common at lower redshifts.  They deduced that the distant galaxies are 0.9 kiloparsecs in diameter (compared to 5 kpc for nearby galaxies), and that the compact galaxies rotate twice as fast.  They did, however, list 5 possible sources of error.  Their field of view was limited, for instance, and “the stellar ages and masses of the galaxies have large uncertainties.”  Most important, they said, studies at redshifts greater than 2 are “typically based on photometric redshifts, which are poorly calibrated for faint, red galaxies.”    Nevertheless, they felt confident that their survey rules out “monolithic” models of galaxy evolution (i.e., “in which early-type galaxies are assembled at the same time as their stars”).  They viewed their results as “the most direct evidence to date for an essentially hierarchical assembly history for massive galaxies.”    One of the unsolved problems in the paper was how to get large mature galaxies out of early compact ones.  How would a dense, compact object grow outward by a factor of six?  Galaxy mergers seem insufficient to do the trick.  Another problem is how they formed in the first place.  For that, the astronomers invoked one of their favorite fudge factors – dark matter:Van Dokkum speculated on how these small, crowded galaxies formed.  He said, one way could have involved an interaction in the emerging universe between hydrogen gas and dark matter — an invisible form of matter that accounts for most of the universe’s mass.  Shortly after the Big Bang, the universe contained an uneven landscape of dark matter.  He said that hydrogen gas could have been trapped in puddles of the invisible material which began spinning rapidly in dark matter’s gravitational whirlpool, forming stars at a furious rate.1.  van Dokkum et al, “Confirmation of the Remarkable Compactness of Massive Quiescent Galaxies at z~2.3: Early-Type Galaxies Did not Form in a Simple Monolithic Collapse,” Astrophysical Journal Letters,677:L5�L8, 2008 April 10, DOI: 10.1086/587874.You gotta love the imagination of some scientists.  Nobody has a clue what dark matter is, or whether it even exists.  This guy has the imaginary stuff forming puddles and whirlpools.  Let him connect his “mysterious unknown stuff” (02/28/2008) with empirical observations before telling us it will make stars form at a furious rate.    Claims like the ones in this paper should always be taken with a grain of salt.  Many laymen read such things on Science Daily or other popular news sources and have no idea what the astronomers are talking about, let alone what it means.  Something to watch for is the element of surprise.  Why were the astronomers surprised by what they found?  What did they actually find?    Measurements such as this are extremely difficult to make.  Astronomers are trying to interpret very faint objects near the limit of observability.  It becomes hard to establish where the noise stops and the signal begins.  The team was honest enough in the original paper to list five major sources of error that could invalidate the claims that these galaxies are unusually compact.  To us, each source of error seemed significant.    Another caution is that observations at cosmological distances are very much tied into the theories employed to make the observations.  What does an infrared blob with a redshift of 2.3 (inferred to represent something at a given distance and age) actually represent?  Why were they focusing on these things instead of other things?  In the 1920s, recall, Edwin Hubble thought that galaxies began as ellipticals and evolved into spirals.  In later years some astronomers reversed the sequence.  Lately astronomers have been finding more structure, more density, and more “maturity” the farther back they look.    It appears that this team was somewhat eager to substantiate the hierarchical model of galaxy evolution over the monolithic model.  But how do they know there are not other possibilities?  And how do they know other sources of error, unknown to us today, might confuse what they think they saw?  Consider that about 20 years ago, many astronomers were caught off guard by the discovery of gravitational lensing.  The bending of light by intervening galaxies, they realized, can seriously compromise the interpretation of distant objects.  It was something few had ever considered.  No one knows whether another phenomenon might be introducing systematic errors into the observations today.    That being said, let’s assume they are correct, and that these distant galaxies are in fact more compact than expected.  It is noteworthy that the astronomers were surprised to see tight and dense structures so close to the assumed big bang.  Simplistic models would have predicted otherwise.  Creation astronomers might want to consider how this survey might fit a “top-down” model for galaxy formation.  Humphreys’ “white hole cosmology” predicted, for example, that distant galaxies would appear from earth to be changing rapidly due to gravitational time dilation.  We’ll leave such considerations to those interested.  The lesson for our purposes is that different assumptions allow for different interpretations consistent with the very same empirical observations.  Things are not always what they seem.  Some cosmologists have their scientific method backward.  They work according to the inverted principle, “No observation should be considered legitimate until confirmed by theory.”    Observation should trump theory in science.  It may not be possible to observe something completely free of bias, but a good first step would be to state one’s biases up front as far as one is aware of them.(Visited 10 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more

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South Africa’s National Treasury

first_imgSouth Africa’s National Treasury seeks to advance economic growth and job creation through appropriate macro-economic, fiscal and financial policies.The Treasury supports the government’s macro-economic policy by determining macro limits on expenditure by departments, in line with affordability and sustainability of services. The departments include agriculture and small business development. (Image: Brand South Africa)Brand South Africa reporterSouth Africa’s National Treasury manages national economic policy, is responsible for managing South Africa’s national government finances and preparing the annual national budget.It falls in the portfolio of the Minister of Finance, as does the South African Revenue Service and Statistics South Africa.Its role is defined by the Constitution and in the Public Finance Management Act.Roles and responsibilitiesThe National Treasury plays a pivotal role in the management of government expenditure, setting financial management norms and standards for state departments, monitoring their performance and reporting any deviations to the Auditor-General.The Treasury also acts as a banker for national government departments; sets and maintains treasury norms and standards to ensure transparency and expenditure control in each sphere of government; and oversees logistical control of stocks and assets.The Treasury supports the government’s macro-economic policy by determining macro limits on expenditure by departments, in line with affordability and sustainability of services. These limits guide and are matched with departments’ budget proposals for the following financial year.Managing of public financesTransforming public-sector financial management is one of National Treasury’s key objectives. To this end, National Treasury has been implementing the Public Finance Management Act since April 2000.The Act has changed the approach to the way in which public funds are managed by introducing a less rigid environment for financial management, with a stronger emphasis on the prudent use of state resources, improved reporting requirements and the use of management information to enhance accountability.Find out moreVisit the National Treasury’s website, which includes information on the Ministry of Finance as well as the budget and links to important legislation.Read our article about South Africa’s Constitution.Sources: National Treasury, South African Revenue Services, Statistics South Africa, and Auditor-General South Africa.Would you like to use this article in your publication or on your website? See Using Brand South Africa materiallast_img read more

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Editing With Canon C300 Footage – Tips For When It All Goes Wrong

first_imgEditing Canon C300 MXF footage? Follow our tips to make video editing with C300 MXF footage go as smoothly as possible.Working with Canon C300 footage – which is XDCAM 422 50/Mbs footage in a .MXF wrapper – should ordinarily be quite straight forward. MXF files will work natively in Adobe Premiere and ingest quite happily through a free plugin in Final Cut Pro 7 and FCPX.  You can also bring this footage in through AMA into Avid Media Composer 6. AbelCine has an excellent step by step guide to importing C300 footage in Adobe Premiere CS6, Final Cut Pro X, FCP 7 and Avid Media Composer 6. You can check it out here.Everything will work seamlessly, that is, if your cards have been copied correctly to the hard drive with their entire folder structure intact. Without that folder structure you are effectively locked out of accessing your footage and an editing application like FCP7 will give you an error message like this one:How to Copy MXF Files CorrectlySo how do you copy cards correctly?Well first, and this may go without saying, but if you’re going to get an intern or producer to do it make sure they know what they’re doing. Essentially you must copy the entire card structure (preferably not through dragging and dropping in the finder).Sony and Canon both have free browser apps that will let you back up your media. Or you could invest in something like Shotput Pro to duplicate your cards to multiple drives simultaneously. You are backing them up as you go, right?If that’s not enough detail, just watch this great tutorial on a correct tapeless media workflow from Shane Ross. Although the tutorial winds up in Final Cut Pro 7, the initial principles are the same for any system. If you want even more tips, check out this great video from Chase Jarvis on his complete tapeless workflow.What To Do If Your C300 Card Structure Is BrokenIf for whatever reason your card structure doesn’t come across intact, what can you do?Depending on your NLE you have various options. If you’re in Adobe Premiere it doesn’t matter, as it will read the MXF files just fine.First, you can try to ‘fake it’ out by recreating the C300 card structure (which should look like the example below). In the past I’m sure I’ve gotten lucky with it but its a pretty slim chance of actually working.  FCPX needs a correct card structure so if you have to, transcoding in a 3rd party app is a feasible workaround.Free App For Converting C300 MXF FilesMiro is a great free app (one of the few free apps I found) that actually works and works well. Miro Video Converter will allow you to grab the .MXF files and transcode them into Pro Res 422, DNxHD and AVC Intra 1080p and 720p. You can batch transcode as many of them as you like and it works pretty quickly. The files look great and were a higher quality than files I created using the demo of MXF Converter for Mac from Pavtube. But as Miro is a free app, there are a few catches.First, you cannot specify the output folder and it defaults to your MacHD > User > Movies folder. So you need to have enough space on your boot drive to transcode the footage too. This is also a problem if you have multiple files with the same name, (which I had on this edit with a two camera shoot) as this means you have to transcode one set at a time and move them out of the folder so as not to overwrite them with the next batch. Annoying.Also the original camera footage I was working with had two audio tracks in it where as Miro would only export a single mono track. This was not helpful either as I needed to be able to mix each track individually.Paid Apps for Working With C300 MXF FilesAs I was editing on an FCP7 system I had to find a way to get my C300 MXF files to play nice with Final Cut Pro 7, while getting around the broken file structure. A cry for help on Twitter led to this great recommendation from Andy Mees who saved the day by suggesting I check out both MXF Import from Calibrated {Q} or MXF4Mac from Hamburg Pro Media. Both plugins essentially do the same thing which is to allow Quicktime (and any apps that make use of the Quicktime architecture) to work with MXF files, just like any other file.Calibrated{Q} MXF Import for OSX is a QuickTime Import component for NATIVE Importing and Editing of MXF Files within Final Cut Pro 6, 7, and X without using Log and Transfer.And you’re not just limited to Final Cut Pro, you can also natively import and work with MXF files in CatDV, Compressor, Motion, Sound Track Pro, QuickTime Player and Shake.You can download a free demo of MXF Import from Calibrated {Q} to test that it will work on your system. The demos only restriction is that it only allows you to view the first 30 seconds of the clip, other than that it’s the same as the full app. After installing the plugin I could drop the C300 MXF files directly onto the timeline in FCP7 and get editing – and with the dual audio tracks in the original files! Huzzah.Hopefully these tips will save you some time, effort and frustration with broken MXF file structures.  And next time you’ll just copy the cards structure correctly…and get to editing!last_img read more

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