Si chiama metil-butil-solfuro e potrebbe comparire nel prossimo libro del Guinness World Record. A che titolo? Come il più piccolo motore elettrico mai realizzato. Un gruppo di ricercatori della Tufts University del Massachusetts, guidati da E. Charles H. Sykes, è infatti riuscito per la prima volta a mettere in moto (non casuale) una singola molecola di metil-butil-solfuro grazie all’ energia elettrica trasmessa attraverso l’aiuto di un microscopio a effetto tunnel ( scanning tunnel microscope, un dispositivo usato generalmente per osservare fenomeni su scala atomica). Un’invenzione che oltre a guadagnare il primato mondiale potrebbe servire per il rilascio controllato di farmaci, o per lo sviluppo di circuiti elettrici su scala molecolare.
La macchina monomolecolare realizzata dagli scienziati (appena un nanometro di lunghezza, ossia un miliardesimo di metro), e presentata in uno studio apparso sulle pagine di Nature Nanotechnology, è così costituita: un atomo di zolfo, cinque atomi di carbonio e dodici atomi di idrogeno, fissata a un supporto di rame attraverso un legame con lo zolfo. Asimmetrica: più lunga da una parte (quella del butile) e più corta dall’altra (quella del metile). Nel corso dell’esperimento i ricercatori hanno usato dell’energia elettrica come carburante, iniettata nel motore attraverso la sottilissima punta del microscopio, grazie al quale poi gli scienziati hanno osservato la risposta della molecola.
Una volta trasmessa l’energia elettrica il motore della macchina si è acceso: la molecola ha cominciato a ruotare intorno all’atomo di zolfo, sia dall’una sia dall’altra parte, preferendo generalmente una direzione (quella oraria) all’altra (come dipendenza sia della conformazione della molecola sia delle caratteristiche della punta del microscopio, spiegano i ricercatori), a una velocità di circa 50 giri al secondo (valore misurabile solo grazie all’abbassamento della temperatura: fino a 5°Kelvin - circa -268°C - in modo da ridurne il moto e da poterlo osservare).
Come ha spiegato Sykes, rispetto ai motori molecolari realizzati in passato - come quelli alimentati da sostanze chimiche o accesi dall’interazione con la luce - il microscopio, attraverso l’energia elettrica, permette di operare più precisamente, interagendo con una singola molecola, che a sua volta, potrebbe essere utilizzata come sistema di ancoraggio per altri sistemi molecolari, che si mettano in moto di conseguenza.
O echipă de cercetători din St. Andrews, Glasgow si Edinburgh au descoperit modul în care nivelurile unei substante importante se modifică pe parcursul vietii reproductive a femeilor. Acest test ar putea dezvălui numărul de ovule rămase în corpul femeilor.
Descoperirea va permite femeilor să compare propriile niveluri hormonale cu media stabilită pentru vârsta lor, pentru a vedea, astfel, dacă au motive de îngrijorare referitoare la fertilitatea lor viitoare.
Testele vor indica dacă femeile vor avea o menopauză precoce sau una târzie, ceea ce le va permite să stie dacă e timpul să aibă un copil sau mai au timp să astepte.
Procesul va ajuta, de asemenea, femeile tinere care au urmat un tratament pentru boli precum cancerul, care ar fi putut afecta fertilitatea; astfel, vor afla dacă nivelul hormonilor a fost afectat. De asemenea, va veni în ajutorul femeilor mai în vârstă, care au ales să amâne momentul conceperii unui copil pentru a se concentra asupra carierei. În prezent, unul din cinci copii este născut de o femeie trecută de vârsta de 35 de ani.
Pentru ultimul studiu, academicienii scotieni au utilizat date ale studiilor anterioare si ultimele lor descoperiri referitoare la hormonul Anti-Müllerian (AMH), produs de foliculii ovarieni.
Ei au studiat modul în care nivelul de AMH variază în diferite momente ale vietii unei femei sănătoase, prin studierea a 3.200 de femei.
S-a constatat că nivelurile de AMH au atins punctul culminant în jurul vârstei de 24 de ani si s-au înjumatătit în jurul vârstei de 30 de ani. Odată ce femeile depăsesc vârsta de 40 de ani, nivelurile de AMH scad aproape de zero.
Nelson a adăugat că, dacă femeile de orice vârstă reproductivă ar face eforturi pentru a rămâne însărcinate, atunci informatiile ar putea fi folosite pentru a le indica acestora dacă nivelul lor de AMH este normal pentru vârsta lor sau este sub medie.
Acest lucru ar putea sugera cât de repede ar trebui să înceapă să se gândească la un tratament precum fertilizarea in vitro.
Cu toate acestea, profesorul Nelson a mentionat că nu ar recomanda femeilor trecute de 30 de ani să întârzie conceperea unui copil, deoarece testarea nivelului de AMH pare să arate că aceste femei nu mai au multi ani de fertilitate înaintea lor.
Computers are great at treating words as data: Word-processing programs let you rearrange and format text however you like, and search engines can quickly find a word anywhere on the Web. But what would it mean for a computer to actually understand the meaning of a sentence written in ordinary English -- or French, or Urdu, or Mandarin?
One test might be whether the computer could analyze and follow a set of instructions for an unfamiliar task. And indeed, in the last few years, researchers at MIT's Computer Science and Artificial Intelligence Lab have begun designing machine-learning systems that do exactly that, with surprisingly good results.
In 2009, at the annual meeting of the Association for Computational Linguistics (ACL), researchers in the lab of Regina Barzilay, associate professor of computer science and electrical engineering, took the best-paper award for a system that generated scripts for installing a piece of software on a Windows computer by reviewing instructions posted on Microsoft's help site. At this year's ACL meeting, Barzilay, her graduate student S. R. K. Branavan and David Silver of University College London applied a similar approach to a more complicated problem: learning to play "Civilization," a computer game in which the player guides the development of a city into an empire across centuries of human history. When the researchers augmented a machine-learning system so that it could use a player's manual to guide the development of a game-playing strategy, its rate of victory jumped from 46 percent to 79 percent.
Starting from scratch
"Games are used as a test bed for artificial-intelligence techniques simply because of their complexity," says Branavan, who was first author on both ACL papers. "Every action that you take in the game doesn't have a predetermined outcome, because the game or the opponent can randomly react to what you do. So you need a technique that can handle very complex scenarios that react in potentially random ways."
Moreover, Barzilay says, game manuals have "very open text. They don't tell you how to win. They just give you very general advice and suggestions, and you have to figure out a lot of other things on your own." Relative to an application like the software-installing program, Branavan explains, games are "another step closer to the real world."
The extraordinary thing about Barzilay and Branavan's system is that it begins with virtually no prior knowledge about the task it's intended to perform or the language in which the instructions are written. It has a list of actions it can take, like right-clicks or left-clicks, or moving the cursor; it has access to the information displayed on-screen; and it has some way of gauging its success, like whether the software has been installed or whether it wins the game. But it doesn't know what actions correspond to what words in the instruction set, and it doesn't know what the objects in the game world represent.
So initially, its behavior is almost totally random. But as it takes various actions, different words appear on screen, and it can look for instances of those words in the instruction set. It can also search the surrounding text for associated words, and develop hypotheses about what actions those words correspond to. Hypotheses that consistently lead to good results are given greater credence, while those that consistently lead to bad results are discarded.
Proof of concept
In the case of software installation, the system was able to reproduce 80 percent of the steps that a human reading the same instructions would execute. In the case of the computer game, it won 79 percent of the games it played, while a version that didn't rely on the written instructions won only 46 percent. The researchers also tested a more-sophisticated machine-learning algorithm that eschewed textual input but used additional techniques to improve its performance. Even that algorithm won only 62 percent of its games.
"If you'd asked me beforehand if I thought we could do this yet, I'd have said no," says Eugene Charniak, University Professor of Computer Science at Brown University. "You are building something where you have very little information about the domain, but you get clues from the domain itself."
Charniak points out that when the MIT researchers presented their work at the ACL meeting, some members of the audience argued that more sophisticated machine-learning systems would have performed better than the ones to which the researchers compared their system. But, Charniak adds, "it's not completely clear to me that that's really relevant. Who cares? The important point is that this was able to extract useful information from the manual, and that's what we care about."
Most computer games as complex as "Civilization" include algorithms that allow players to play against the computer, rather than against other people; the games' programmers have to develop the strategies for the computer to follow and write the code that executes them. Barzilay and Branavan say that, in the near term, their system could make that job much easier, automatically creating algorithms that perform better than the hand-designed ones.
But the main purpose of the project, which was supported by the National Science Foundation, was to demonstrate that computer systems that learn the meanings of words through exploratory interaction with their environments are a promising subject for further research. And indeed, Barzilay and her students have begun to adapt their meaning-inferring algorithms to work with robotic systems.
È successo tutto tra giugno e agosto: un hacker che si firma con il motto " Janam Fadaye Rahbar" (qualcosa che suona come " sono pronto a sacrificarmi per il mio leader") ha violato migliaia di account Google di utenti iraniani. Per farlo, ha sfruttato i server del provider olandese DigiNotar, attraverso cui ha generato dei certificati digitali fasulli di cui Wired.it vi ha già raccontato. Secondo l'agenzia di Internet security Fox-IT, l'attacco informatico avrebbe aggirato facilmente alcuni firewall colabrodo. Così, vista la sonora batosta, gli esperti della sicurezza hanno pensato bene di soprannominare l'operazione " Tulipano nero".
Come racconta PCWorld, l'hacker ha usato i server di DigiNotar per generare un certificato digitale targato *.google.com fasullo. Armato di questa chiave d'accesso, il pirata informatico ha forzato username e password di migliaia di account gmail registrati in Iran e ne ha assunto il controllo. Il volume di informazioni riservate potenzialmente sottratte sarebbe enorme: a partire dal 4 agosto, infatti, i server di BigG sono stati contattati da 300mila diversi IP, tutti iraniani e con passaporto olandese. Una situazione davvero insolita, che ha messo tardivamente in allarme Google. Il certificato è stato bloccato il 29 agosto, quando ormai il peggio era già successo.
Per capire cosa si sia verificato nel concreto, è utile dare uno sguardo al report stilato da Fox-IT, che ha ricostruito i dettagli dell'accaduto a partire da fine agosto. I primi movimenti sospetti hanno avuto luogo a metà giugno, quando il provider olandese ha identificato delle attività sospette sui propri server. Il 19 luglio, in seguito a un controllo più approfondito, DigiNotar ha scoperto l'esistenza di 128 certificati fasulli generati sfruttando alcune falle nel suo sistema di sicurezza. Nonostante il blocco immediato di questi dati, l'attacco hacker è andato avanti fino al 27 luglio, generando altri 204 certificati pirata, tutti indirizzati verso l'Iran.
Insomma, il provider dei Paesi Bassi ha capito subito di trovarsi di fronte a attività di hacking su larga scala che stavano bersagliando computer iraniani. Ma, a quanto pare, DigiNotar non è riuscita a bloccare tutte le chiavi d'accesso create dal pirata informatico. Primo fra tutti, il famoso certificato *.google.com - generato, per la precisione, il 10 luglio - che è sfuggito completamente ai controlli ed è rimasto operativo per quasi 50 giorni. In questo arco di tempo, il burattinaio di Tulipano nero aveva diretto accesso ai contenuti degli account gmail e di qualsiasi altro servizio BigG a cui fosse possibile accedere con le credenziali rubate.
Nessuno, tuttavia, sa ancora quale sia stata la reale portata di questo attacco. Google ha semplicemente invitato gli utenti iraniani a cancellare i vecchi cookies e a scegliere una nuova password per il login.
Le identità dei bersagli colpiti dall' hacker non sono ancora note, ma di sicuro l'accaduto non verrà preso alla leggera. Giusto per capire la portata dell'attacco, basti pensare che tra gli altri codici sospetti bloccati da DigiNotar c'erano anche protocolli fasulli per accedere direttamente ai server di Microsoft, Cia e Mossad, i servizi segreti israeliani.
Creierul este un organ cu adevărat fantastic. El ne controlează miscările si emotiile, dar ne-am întreabat vreodată cum reuseste să redea amintirile? O echipă de cercetători neurologi din cadrul Universitătii New York a identificat acea parte a creierului pe care o folosim să ne amintim succesiunea evenimentelor din cadrul unui întâmplări.
Cercetătorii au supus un număr de animale unui experiment centrat pe ordiniea formării amintirilor: erau prezentate doua imagini, iar subiectii trebuiau să si le amintească în ordinea prezentării lor, după un anumit interval de timp.
Pentru a îndeplini cerinta corespunzător, animalele trebuiau să-si amintească atât ce s-a întâmplat, cât si când a avut loc întâmplarea. În timpul experimentului, cercetătorii au monitorizat activitatea celulelor din lobul temporal medial (MTL).
Rezultatele au arătat că în acest proces sunt implicate două zone principale din cadrul MTL. Aceste zone sunt hipocampul si cortexul perirhinal. Zona hipocampica este cunoscută ca având un rol important într-o varietate mare de atributii ale memoriei. Ea emite semnale elementare de sincronizare între evenimente-cheie, oferind informatii despre cât timp a trecut de la ultimul eveniment de acest gen si, totodată, estimează timpul până la unul viitor.
Cortexul peririnal integrează informatii ce răspund la întrebările "ce?" si "când?" semnalizând dacă un element a fost arătat primul sau al doilea în cadrul unei serii. Descoperirile americanilor oferă o perspectivă asupra modelelor de activitate cerebrală care ne permit să ne amintim atât elementele-cheie care me marchează viata, cât si succesiunea în care acestea au survenit.
Storing the sun’s heat in chemical form — rather than converting it to electricity or storing the heat itself in a heavily insulated container — has significant advantages, since in principle the chemical material can be stored for long periods of time without losing any of its stored energy. The problem with that approach has been that until now the chemicals needed to perform this conversion and storage either degraded within a few cycles, or included the element ruthenium, which is rare and expensive.
Last year, MIT associate professor Jeffrey Grossman and four co-authors figured out exactly how fulvalene diruthenium — known to scientists as the best chemical for reversibly storing solar energy, since it did not degrade — was able to accomplish this feat. Grossman said at the time that better understanding this process could make it easier to search for other compounds, made of abundant and inexpensive materials, which could be used in the same way.
Now, he and postdoc Alexie Kolpak have succeeded in doing just that. A paper describing their new findings has just been published online in the journal Nano Letters, and will appear in print in a forthcoming issue.
The new material found by Grossman and Kolpak is made using carbon nanotubes, tiny tubular structures of pure carbon, in combination with a compound called azobenzene. The resulting molecules, produced using nanoscale templates to shape and constrain their physical structure, gain “new properties that aren’t available” in the separate materials, says Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering.
Not only is this new chemical system less expensive than the earlier ruthenium-containing compound, but it also is vastly more efficient at storing energy in a given amount of space — about 10,000 times higher in volumetric energy density, Kolpak says — making its energy density comparable to lithium-ion batteries. By using nanofabrication methods, “you can control [the molecules’] interactions, increasing the amount of energy they can store and the length of time for which they can store it — and most importantly, you can control both independently,” she says. Thermo-chemical storage of solar energy uses a molecule whose structure changes when exposed to sunlight, and can remain stable in that form indefinitely. Then, when nudged by a stimulus — a catalyst, a small temperature change, a flash of light — it can quickly snap back to its other form, releasing its stored energy in a burst of heat. Grossman describes it as creating a rechargeable heat battery with a long shelf life, like a conventional battery.
One of the great advantages of the new approach to harnessing solar energy, Grossman says, is that it simplifies the process by combining energy harvesting and storage into a single step. “You’ve got a material that both converts and stores energy,” he says. “It’s robust, it doesn’t degrade, and it’s cheap.” One limitation, however, is that while this process is useful for heating applications, to produce electricity would require another conversion step, using thermoelectric devices or producing steam to run a generator. While the new work shows the energy-storage capability of a specific type of molecule — azobenzene-functionalized carbon nanotubes — Grossman says the way the material was designed involves “a general concept that can be applied to many new materials.” Many of these have already been synthesized by other researchers for different applications, and would simply need to have their properties fine-tuned for solar thermal storage.
The key to controlling solar thermal storage is an energy barrier separating the two stable states the molecule can adopt; the detailed understanding of that barrier was central to Grossman’s earlier research on fulvalene dirunthenium, accounting for its long-term stability. Too low a barrier, and the molecule would return too easily to its “uncharged” state, failing to store energy for long periods; if the barrier were too high, it would not be able to easily release its energy when needed. “The barrier has to be optimized,” Grossman says.
Already, the team is “very actively looking at a range of new materials,” he says. While they have already identified the one very promising material described in this paper, he says, “I see this as the tip of the iceberg. We’re pretty jazzed up about it.”
Yosuke Kanai, assistant professor of chemistry at the University of North Carolina at Chapel Hill, says “the idea of reversibly storing solar energy in chemical bonds is gaining a lot of attention these days. The novelty of this work is how these authors have shown that the energy density can be significantly increased by using carbon nanotubes as nanoscale templates. This innovative idea also opens up an interesting avenue for tailoring already-known photoactive molecules for solar thermal fuels and storage in general.”
Berlusconi, who failed to secure a majority in a crucial vote on Tuesday, stepped down as prime minister after parliament passed a package of measures demanded by European partners to restore market confidence in Italy's strained public finances.
Former European Commissioner Mario Monti is expected to be given the task of trying to form a new administration to face a widening financial crisis which has sent Italy's borrowing costs to unmanageable levels.
More than a thousand demonstrators waving banners mocking Berlusconi flocked to the president's residence at the Quirinale Palace as the motorcade carrying the billionaire media entrepreneur, who has been Italy's longest serving prime minister, entered.
The crowd grew so unruly that Berlusconi was forced to leave secretly via a side entrance and return to his private residence.
Cheers broke out when they heard that Berlusconi had resigned and the square broke out into a party atmosphere. People sang, danced and some broke open bottles of champagne.
An orchestra near the palace played the Hallelujah chorus from Handel's Messiah. "We are here to rejoice," one said.
Demonstrators chanting "resign, resign, resign" also gathered outside the prime minister's office and parliament, heckling ministers as they walked between the two buildings.
A small group of pro-Berlusconi demonstrators gathered outside his residence but were hugely outnumbered by opponents.
After the resignation, hundreds shouting "Jail, Jail, Jail,"
moved from the presidential palace to Berlusconi's residence to continue the noisy celebrations below his windows.
"This is something that deeply saddens me," the Italian news agency Ansa quoted Berlusconi as telling aides.
President Giorgio Napolitano will begin consultations with political leaders at 5:00 a.m. EST on Sunday morning. He was expected to ask Monti for form a government on Sunday night.
Italy, the euro zone's third largest economy, came close to disaster this week when yields on 10-year bonds soared over 7.6 percent, the kind of level which forced Ireland, Portugal and Greece to seek international bailouts.
Berlusconi, who failed to secure a majority in a vote on Tuesday, promised to resign once parliament passed the package of economic reforms demanded by European partners to restore confidence in Italy's battered public finances.
Monti, named by Napolitano as a Senator for Life on Wednesday, is expected to appoint a relatively small cabinet of technocrat specialists to steer Italy through the crisis.
With the next election not due until 2013, a technocrat government could have about 18 months to pass painful economic reforms but will need to secure the backing of a majority in parliament and could fall before then.
With a public debt of more than 120 percent of gross domestic product and more than a decade of anemic economic growth behind it, Italy is at the heart of the euro zone debt crisis and would be too big for the bloc to bail out.
Financial markets have backed a Monti government and as prospects of Berlusconi going became firmer last week, yields dropped below the critical 7 percent level, although they remain close.
"We don't yet have a new government in Italy and we have to wait, but I'm sure if Mario Monti will be appointed he will do whatever is necessary in order to restore the confidence of the financial markets in Italy," Alessandro Profumo, former head of Unicredit, Italy's largest bank, told Reuters.
SIGNS OF OPPOSITION MOUNT
Berlusconi, fighting an array of scandals and facing trials on charges ranging from tax fraud to paying for sex with an under-aged prostitute, had been under pressure to resign for weeks as the market crisis threatened to spin out of control.
International leaders including U.S. President Barack Obama, French President Nicolas Sarkozy and the head of the International Monetary Fund Christine Lagarde have expressed hopes a new government can be in place quickly.
Talks with Italian political parties are expected to begin on Sunday with hopes that a new government can be in place in time for the opening of financial markets on Monday.
However, even as preparations for a transition begin, signs of opposition have appeared, with Berlusconi's PDL party split between factions ready to accept a Monti government and others deeply opposed.
Berlusconi had a working lunch with Monti before the vote, suggesting the outgoing government will not try to block a quick handover, but the attitude of the center-right as a whole remains unclear.
The PDL's main coalition ally, the regional pro-devolution Northern League, has declared it will go into opposition, underlining the risk that the new government will lack the broad parliamentary support it will need to pass deep reforms.
"The convulsions in the center-right at the prospect of a government led by Mario Monti signal a danger: that a divided coalition may be tempted to unload its divisions on the country," the daily Corriere della Sera said.
The center-left Democratic party and smaller centrist parties have pledged support to Monti. Italy's main business and banking associations and some of the moderate trade unions have also called for a government of national unity.
Source: Reuters - (Additional reporting by James Mackenzie and Paolo Biondi; Writing by Philip Pullella and James Mackenzie; Editing by Janet Lawrence and Andrew Heavens)
Se volete dirlo e scriverlo come avrebbero fatto Maya e Aztechi, sappiate che 6 settembre 2011, è il 12.19.18.12.8 per il calendario Maya Lungo Computo, il 16 Mol nello Haab, e il 13 Lamat nello Tzolkin. Non facile da ricordare, certo, ma potrebbe andar meglio con 13.0.0.0.0 (il 21 dicembre 2012, lasciando da parte il calendario Haab e il Tzolkin, rispettivamente il calendario solare e quello religioso), giorno in cui il Lungo Computo (il complesso calendario invece utilizzato per marcare gli eventi sul lungo periodo) terminerà il suo lunghissimo ciclo di 5126 anni circa (il quarto per i Maya), avuto inizio il 6 settembre 3114 a.C (secondo il calendario giuliano). E con lui il prossimo anno, almeno secondo le profezie, anche il mondo dovrebbe finire. O, nel migliore di casi, subire un cambiamento radicale, l’apertura verso una Nuova Era.
Ma come e da dove hanno avuto origine questa apocalittiche profezie? In Messico, precisamente nel sito archeologico di Tortuguero, grazie all’ormai famoso monumento VI, che riporta una misteriosa (quanto in larga parte non interpretabile perché incompleta e danneggiata) iscrizione che si riferisce alla fine del tredicesimo baktun del Lungo Computo (1 baktun equivale a un periodo di circa 144mila giorni), coincidente proprio con la data del solstizio d’inverno dell’anno che verrà, come una data da tenere sotto controllo. Quel giorno infatti qualcosa di imprecisato dovrebbe accadere in seguito all’avvento di Bolon Yokte K’uh, dio maya generalmente associato con la creazione, ma anche con gli inferi, i conflitti e la guerra. Di qui l’idea di un grande cambiamento, qualcosa che implichi distruzione, come appunto la fine del mondo. Oppure l’avvento di Bolon Yokte K’Hu potrebbe avere a che fare con una nuova creazione (una New Age per l’appunto) piuttosto che con un evento distruttivo.
Secondo alcuni studiosi della civiltà Maya, però, né l’una né l’altra profezia sembrerebbero avere un reale riscontro: la fine del calendario maya non sarebbe altro che la chiusura di un ciclo prima dell’inizio di una nuova era. Eppure, dal Monumento VI, quella scritta ne ha generate di paure e miscredenze. Alcune vogliono che il 21 dicembre 2012 coincida con l’impatto, in pieno stile Armageddon, di un asteroide con la Terra e con l’avvento di un’estinzione di massa senza precedenti. Secondo altri invece potrebbe verificarsi un terremoto straordinario, e un cambiamento del campo magnetico del nostro pianeta - indotto dal raro allinearsi con gli altri componenti del sistema solare lungo l’equatore galattico - così forte da determinare un’inversione della polarità della Terra. Quanto manca? Circa 471 giorni, come cita il countdown del sito ufficiale dell’apocalisse prevista per il prossimo anno del sito December 21 2012. Noi, in ogni caso, non tratterremo il fiato.
Câteva modificări minore, printre care se numără schimbarea locului în care luăm mesele si micsorarea dimensiunii farfuriilor din care mâncăm, pot ajuta la pierderea în greutate, sustin cercetătorii.
Cercetătorul american Brian Wansink, de la Universitatea Cornell, a declarat că unul dintre studiile sale a analizat modul în care cinefilii mănâncă floricele de porumb din recipiente mari si foarte mari.
Cei care aleg portiile mai mari mănâncă, în medie, cu 45% mai mult; chiar si atunci când floricelele nu mai sunt foarte proaspete, acestia mănâncă mai mult cu 34%.
Un alt studiu, realizat pe copii, a demonstrat că acestia au tendinta de a mai cere o portie de cereale atunci când mănâncă dintr-un castron mai mare, fată de cei care aleg să mănânce din castroane mai mici.
Dr. Wansink a declarat, la un congres al Asociatiei Americane de Psihologie, că oamenii au pierdut până la un kilogram prin simpla schimbare a mărimii farfuriilor din care mănâncă, prin evitarea alimentelor nesănătoase si luarea meselor fără prezenta televizorului.
De asemenea, dr. Wansink a declarat că ideea că stomacul nostru ne va anunta atunci când este plin este gresită. Rezultatele studiilor sale arată că senzatia de satietate e influentată de factori externi precum mărimea recipientelor si a portiilor si de atentia acordată actului de a mânca.
The technology amplifies any anthrax DNA present in the sample and can reveal the presence of just 40 microscopic cells of the deadly bacteria Bacillus anthracis.
B. anthracis, commonly known as anthrax, is a potentially lethal microbe that might be used intentionally to infect victims through contamination of food and water supplies, aerosolized particles, or even dried powders, such as those used in bioterrorist attacks in the USA. Detection is crucial to preventing widespread fatalities in the event of an anthrax attack. However, the complexity of the microbe's biology have so far made it difficult to build a portable system that can be employed quickly in the field. That said, there are several systems available that use PCR to amplify a particular component of the genetic material present in anthrax and then to flag this amplified signal. These systems are fast and sensitive but do not integrate sample preparation and so are not as convenient as a single detector unit would be.
A photomicrograph of Bacillus anthracis bacteria using Gram-stain technique. Anthrax is diagnosed by isolating B. anthracis from the blood, skin lesions, or respiratory secretions, or by measuring specific antibodies in the blood of persons with suspected cases. Photo: CDC
Writing in the International Journal of Biomedical Nanoscience and Nanotechnology this month, Nathaniel Cady of the College of Nanoscale Science and Engineering (CNSE) of the University at Albany and colleagues there and at Cornell University, New York, explain how they have constructed nanofabricated fluidic cartridges that can be used to carry out detection of anthrax. The device is a so-called "lab-on-a-chips" device, or more properly a 3D microfluidic network that contains nanofabricated pillar structures.
The device has fluidic inputs for adding sample and reagents, removing waste, for carrying out DNA purification, and critically an integrated chamber for amplifying only the target DNA in the sample using the polymerase chain reaction (PCR) system. The chip also contains a wave guide for the fluorescence-based identification of the amplified DNA and thus the target microbe. Importantly, the system works without manual intervention other than loading a droplet of sample into the detector.
"The average time required for DNA purification during these experiments was approximately 15 min, and when combined with real-time PCR analysis, this resulted in an average time to detection of 60 min," the team says. The system can detect as few as 40 B. anthracis cells. "Due to its small size and low power requirements, this system can be further developed as a truly portable, hand-held device," the researchers conclude.
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