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Naucna i tehnoloska otkrica

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#1 Anduril

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Posted 18 October 2009 - 11:39

Na ovom topiku bi smo mogli diskutovati o najnovijim dostignucima kao i o vaznim poboljsanjima iz sveta nauke i tehnologije koje ce u buducnosti promeniti ili vec menjaju nas svakodnevi zivot.

Za pocetak dve vesti, jedna iz fizike a druga iz psihologije o agresivnosti inferiornih sefova:

First black hole for light created on Earth

* 17:13 14 October 2009 by Anil Ananthaswamy

An electromagnetic "black holeMovie Camera" that sucks in surrounding light has been built for the first time.

The device, which works at microwave frequencies, may soon be extended to trap visible light, leading to an entirely new way of harvesting solar energy to generate electricity.

A theoretical design for a table-top black hole to trap light was proposed in a paper published earlier this year by Evgenii Narimanov and Alexander Kildishev of Purdue University in West Lafayette, Indiana. Their idea was to mimic the properties of a cosmological black hole, whose intense gravity bends the surrounding space-time, causing any nearby matter or radiation to follow the warped space-time and spiral inwards.

Narimanov and Kildishev reasoned that it should be possible to build a device that makes light curve inwards towards its centre in a similar way. They calculated that this could be done by a cylindrical structure consisting of a central core surrounded by a shell of concentric rings.
There's no escape

The key to making light curve inwards is to make the shell's permittivity – which affects the electric component of an electromagnetic wave – increase smoothly from the outer to the inner surface. This is analogous to the curvature of space-time near a black hole. At the point where the shell meets the core, the permittivity of the ring must match that of the core, so that light is absorbed rather than reflected.

Now Tie Jun Cui and Qiang Cheng at the Southeast University in Nanjing, China, have turned Narimanov and Kildishev's theory into practice, and built a "black hole" for microwave frequencies. It is made of 60 annular strips of so-called "meta-materials", which have previously been used to make invisibility cloaks.

Each strip takes the form of a circuit board etched with intricate structures whose characteristics change progressively from one strip to the next, so that the permittivity varies smoothly. The outer 40 strips make up the shell and the inner 20 strips make up the absorber.

"When the incident electromagnetic wave hits the device, the wave will be trapped and guided in the shell region towards the core of the black hole, and will then be absorbed by the core," says Cui. "The wave will not come out from the black hole." In their device, the core converts the absorbed light into heat.
Quick work

Narimanov is impressed by Cui and Cheng's implementation of his design. "I am surprised that they have done it so quickly," he says.

Fabricating a device that captures optical wavelengths in the same way will not be easy, as visible light has a wavelength orders of magnitude smaller than that of microwave radiation. This will require the etched structures to be correspondingly smaller.

Cui is confident that they can do it. "I expect that our demonstration of the optical black hole will be available by the end of 2009," he says.

Such a device could be used to harvest solar energy in places where the light is too diffuse for mirrors to concentrate it onto a solar cell. An optical black hole would suck it all in and direct it at a solar cell sitting at the core. "If that works, you will no longer require these huge parabolic mirrors to collect light," says Narimanov.

Journal references: Applied Physics Letters (vol 95, p041106), and "An electromagnetic black hole made of metamaterials" by Tie Jun Cui and Qiang Cheng's (preprint archive)

It's official: Your bullying boss really is an idiot

* 14:28 15 October 2009 by Ewen Callaway
* For similar stories, visit the The Human Brain Topic Guide

Got a bullying boss? Take solace in new research showing that leaders who feel incompetent really do lash out at others to temper their own inferiority.

"Power holders feel they need to be superior and competent. When they don't feel they can show that legitimately, they'll show it by taking people down a notch or two," says Nathanael Fast, a social psychologist at the University of Southern California in Los Angeles, who led a series of experiments to explore this effect.

In one, Fast and his colleague Serena Chen, who is at the University of California, Berkeley, asked 90 men and women who had jobs to complete online questionnaires about their aggressive tendencies and perceived competence. The most aggressive of the lot tended to have both high-power jobs and a chip on their shoulder, Fast and Chen found.

To see if a bruised ego can actually cause aggression, the researchers manipulated people's sense of power and self-worth by asking them to write about occasions when they felt either empowered or impotent and then either competent or incompetent. Previous research has suggested that such essays cause a short-term bump or drop in feelings of power and capability, Fast says.
Feel-bad factor

Next, Fast and Chen asked their volunteers to select a punishment to be given to university students for wrong answers in a hypothetical test of learning. Volunteers chose between horn sounds that ranged from 10 decibels to a deafening 130 decibels.

The volunteers who felt the most incompetent and empowered picked the loudest punishments – 71 decibels on average. Workers who felt up to their jobs, selected far quieter punishments, between 55 and 62 decibels, as did those primed to feel incompetent yet powerless.

Flattery seems to temper the aggressive urges of insecure leaders. When Fast and Chen coaxed the egos of these volunteers by praising their leadership skills, their aggressive tendencies all but disappeared. This is proof that leaders are aggressive because of a hurt ego, not simply a threat to their power, Fast says.

This might also explain why leaders of organisations both big and small surround themselves with yes-men and women, he says.

Blind flattery may not be the best solution for the 54 million US citizens estimated to have experienced workplace bullying (PDF). But easing leaders into new positions of power, or telling them that it's natural to feel daunted, could prevent future outbursts, says Adam Galinsky , a social psychologist at Northwestern University's Kellogg School of Management in Evanston, Illinois.

Journal reference: Psychological Science, DOI: 10.1111/j.1467-9280.2009.02452.x

#2 Anduril

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Posted 10 January 2010 - 12:04

Optogenetics: controlling brain cells with lasers

* 17:37 07 January 2010 by Ewen Callaway
* For similar stories, visit the The Human Brain and Genetics Topic Guides

Brain cells can be switched on and off like light bulbs using newly identified microbial proteins that are sensitive to the colour of laser light.

The discovery is the latest in the fast-moving field of optogenetics, which has already given researchers unparalleled control over brain circuits in laboratory animals. The technology may lead to treatments for conditions such as epilepsy, Parkinson's disease and blindness. New Scientist explains the science and its promise.

How do scientists control brain cells with lasers?

Neurons fire when electrically charged atoms – ions – flood in and out of them, creating a tiny electric potential across their membranes. In 2005, a team at Stanford University in California reported that light-sensitive microbial proteins that also move ions can cause the same changes when they are genetically engineered into neurons.

One algal protein, channelrhodopsin-2, turns neurons on when bathed in blue light, while its foil, halorhodopsin, silences neurons under yellow light.

If these proteins are already around, what's new?

Channelrhodopsin-2 works swimmingly: it recently helped identify a brain circuit that, when activated, may ease symptoms of Parkinson's.

However, halorhodopsin has fallen short of hopes. The protein fails to fully silence neurons and grows sluggish after repeated cycles of light, says Ed Boyden, a neuroscientist who worked on both proteins at Stanford with his colleague Karl Deisseroth: "It didn't work very well and it hasn't found much of an application."

Now, Boyden's team at the Massachusetts Institute of Technology has discovered two new light-sensitive proteins that are up to the task, at last offering an on/off switch for brain cells. "We can do digital shutdown of neurons," he says.

Why is that useful?

For one, the new proteins give researchers the power to tease out how specific brain circuits underlie behaviour, Boyden says. They can be genetically engineered into specific kinds of neuron, such those involved in forming certain kinds of memories. These cells could then be turned off in laboratory animals to see how their behaviour changes.

Furthermore, one of the newly discovered proteins, called Mac, shuts off neurons under blue light instead of yellow. By expressing Mac in one cell type and a yellow-sensitive "off switch" protein in another, it would be possible to independently silence two sets of neurons that originate in a single area, such as the prefrontal cortex, but dart off to different parts of the brain.

Will optogenetics ever be used to treat diseases in humans?

It's hard to say. However, clinical trials may begin in the next decade, says Boyden, who is involved in a company, Eos, that aims to use optogenetics to treat blindness. Another fledgling firm is hoping to apply the technology to spinal cord injuries.

The success of these efforts will depend on the ability to safely and effectively send genes and light to neurons – no easy feat.

Even if human brains never come under the control of lasers – as those of fliesMovie Camera, mice and even monkeys now have – optogenetics will almost certainly lead to medical breakthroughs, Boyden contends.

If optogenetic research can establish the brain circuits disturbed in neurological and psychiatric illnesses, these cells could be targeted with drugs or more established technologies such as deep brain stimulation. "We can use these tools for real principles of treatment," he says.

Edited by Anduril, 10 January 2010 - 12:05.

#3 Prishtinasi

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Posted 23 November 2010 - 22:33

The following is an actual question given on a University of Washington chemistry mid-term.

Bonus Question: Is Hell exothermic (gives off heat) or endothermic (absorbs heat)?

Most of the students wrote proofs of their beliefs using Boyle's Law (gas cools when it expands and heats when it is compressed) or some variant.

One student, however, wrote the following:

First, we need to know how the mass of Hell is changing in time. So we need to know the rate at which souls are moving into Hell and the rate at which they are leaving. I think that we can safely assume that once a soul gets to Hell, it will not leave. Therefore, no souls are leaving. As for how many souls are entering Hell, let's look at the different religions that exist in the world today.

Most of these religions state that if you are not a member of their religion, you will go to Hell. Since there is more than one of these religions and since people do not belong to more than one religion, we can project that all souls go to Hell. With birth and death rates as they are, we can expect the number of souls in Hell to increase exponentially. Now, we look at the rate of change of the volume in Hell because Boyle's Law states that in order for the temperature and pressure in Hell to stay the same, the volume of Hell has to expand proportionately as souls are added.

This gives two possibilities:

1. If Hell is expanding at a slower rate than the rate at which souls enter Hell, then the temperature and pressure in Hell will increase until all Hell breaks loose.

2. If Hell is expanding at a rate faster than the increase of souls in Hell, then the temperature and pressure will drop until Hell freezes over.

So which is it?

If we accept the postulate given to me by Teresa during my Freshman year that, 'It will be a cold day in Hell before I sleep with you,' and take into account the fact that I slept with her last night, then number two must be true, and thus I am sure that Hell is exothermic and has already frozen over. The corollary of this theory is that since Hell has frozen over, it follows that it is not accepting any more souls and is therefore, extinct leaving only Heaven, thereby proving the existence of a divine being which explains why, last night, Teresa kept shouting 'Oh my God.'

#4 st.maurice

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Posted 10 April 2011 - 10:58

Čovjek će moći disati pod vodom bez pomagala

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ako još nisu proizveli umjetne škrge, bioinženjeri su pronašli način za boravak ljudi pod vodom i njihovo nesmetano disanje bez potrebe za korištenjem boca s kisikom.

Tvrde da bi to moglo biti moguće povezivanjem ljudske DNK s DNK koju posjeduju morske alge.
Kako bi to dokazali, izvršili su eksperiment na daždevnjacima.

Alge koje proizvode kisik povezali su s njihovim jajima, a da je simbioza bila uspješna, dokazuje činjenica da su i u nastavku života ta bića bila 'nerazdvojna'.

Spajanje DNK alge i daždevnjaka prvi je dokumentirani primjer uspješne simbioze biljke i kralježnjaka.

Znanstvenici se nadaju da će daljnjim proučavanjem i usavršavanjem ovaj proces biti primjenjiv i na ljudima.
On nas, na svu sreću, neće pretvoriti u alge, ali bi nam mogao pomoći da neke njihove sposobnosti koristimo pod vodom.
Alge bi tako mogle postati izvor kisika za mnoge kralježnjake, uključujući i čovjeka.

Ostvari li se bioinženjerima ovaj ambiciozni plan, za nekoliko desetljeća boce s kisikom za ronjenje postat će tek zanimljivi muzejski eksponati.


#5 SVEMIR.ba

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Posted 14 April 2011 - 16:54

Korak prema holodeku

Ukoliko ste ljubitelj Zvjezdanih staza sigurno ste upoznati s čarima holodeka – prostora u kojem se uz pomoć računara i svjetla kreiraju realistična okruženja. Naučnici još uvijek nisu dizajnirali ovaj nevjerojatan uređaj, no napravili su korak prema njemu.


#6 st.maurice

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Posted 25 April 2011 - 21:19

Pronađen Higsov bozon?

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U internom izveštaju, koji je procurio u javnost, navodi se da je jedan od detektora kolajdera Evropskog centra za nuklearna istraživanja (CERN), nedaleko od Ženeve, zabeležio signale koji bi mogli da ukažu na Higsov bozon za kojim naučnici već dugo tragaju.

Jedan od glavnih naučnih ciljeva ovog eksperimenta je upravo dokazivanje postojanja Higsovog bozona, teoretske čestice za koju se veruje da je stvorila celokupni univerzum nakon Velikog praska.

Čestica predstavlja ključni deo Standardnog modela koji se koristi u fizici da bi se opisao način na koji se grade čestice i atomi. Fizičari veruju da pronalazak Higsovog bozona može da objasni zašto objekti imaju masu.

Glasine da su naučnici CERN-a pronašli dokaz o postojanju Higsovog bozona počele su da kruže nakon što je sadržaj jednog internog izveštaja postavljen na Internet, prenosi londonski Telegraf.

Naučnici su, međutim, odmah pozvali na oprez, jer dobijeni rezultati nisu valjano provereni i mogli bi, kao mnogo puta do sada, da budu samo "lažna uzbuna".

Prema izveštaju koji se pojavio na Internetu, u poslednjem eksperimentu u Velikom hardonskom kolajderu zabaleženi su signali koji su masom i ostalim karakteristikama jednaki predviđanjima Higsa.

Neki od aspekata signala, međutim, ne odgovaraju predviđanjima, pa je tako brzina njegovog stvaranja nekoliko puta veća od očekivane, što bi, s druge strane, moglo da znači da je pronađena čestica o kojoj čak ne postoje ni teorije.

Džejms Džilis (James Gillies), zvanični portparol CERN-a, potvrdio je autentičnost izveštaja koji je delo četvoro naučnika koji rade na eksperimentu ATLAS Vekog hadronskog kolajdera.

On je, međutim, naveo da je to samo jedan od stotine izveštaja koji naučnici stalno dostavljaju i da je njegova provera u početnoj fazi.

"Previše je rano reći da li tu uopšte ima nečeg. Na eksperimentu ATLAS radi 3.000 naučnika koji međusobno dele analitički rad", kazao je Džilis, navodeći da svaki izveštaj mora da prođe kroz nekoliko nivoa provere pre objavljivanja kao zvaničnog rezultata celokupnog naučnog tima.


Edited by st.maurice, 26 April 2011 - 10:32.

#7 SVEMIR.ba

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Posted 10 May 2011 - 12:34

Evo jos nekih interesantnih stvari iz svemira:

#8 JazzyZez

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Posted 17 May 2011 - 14:51

Pronađen Higsov bozon?

U internom izveštaju, koji je procurio u javnost, navodi se da je jedan od detektora kolajdera Evropskog centra za nuklearna istraživanja (CERN), nedaleko od Ženeve, zabeležio signale koji bi mogli da ukažu na Higsov bozon za kojim naučnici već dugo tragaju.

Higsov bozon još uvek nije dokazan, mada ga jure i ovi u CERN-u i ovi od preko bare. Ko ga dokaže dobije Nobela, ali ne mogu da zamislim konfuziju koja bi nastala ako dokažu da on zapravo ne postoji. Pala bi koncepcija nuklearne a i astofizike koja je građena poslednjih 60 godina. Zapravo sve bi se vratilo na dve suprotstavljane istine a to je Ajnštajnova opšta teorija relativiteta i kvantna fizika principa neodređenosti. Hoću reći ne bi bilo pomaka prema ujedinjavanju ove dve teorije.

#9 SVEMIR.ba

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Posted 20 May 2011 - 09:38

Karakteristicni tragovi rovera Opportunity na površini Marsa


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Edited by SVEMIR.ba, 20 May 2011 - 09:40.

#10 st.maurice

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Posted 13 July 2011 - 07:51

First man ‘functionally cured’ of HIV

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Timothy Ray Brown suffered from both leukemia and HIV when he received a bone marrow stem cell transplant in Berlin, Germany in 2007. The transplant came from a man who was immune to HIV, which scientists say about 1 percent of Caucasians are. (According to San Francisco's CBS affiliate, the trait may be passed down from ancestors who became immune to the plague centuries ago. This Wired story says it was more likely passed down from people who became immune to a smallpox-like disease.)

What happened next has stunned the dozens of scientists who are closely monitoring Brown: His HIV went away.

"He has no replicating virus and he isn't taking any medication. And he will now probably never have any problems with HIV," his doctor Gero Huetter told Reuters. Brown now lives in the Bay Area, and suffers from some mild neurological difficulties after the operation. "It makes me very happy," he says of the incredible cure.

The development of anti-retroviral drugs in the 1990s was the first sign of hope in the epidemic, transforming the disease from a sudden killer to a more manageable illness that could be lived with for decades. But still, the miraculous cocktail of drugs is expensive, costing $13 billion a year in developing countries alone, according to Reuters. That figure is expected to triple in 20 years--raising the worry that more sick people will not be able to afford treatment.

Although Brown's story is remarkable, scientists were quick to point out that bone marrow transplants can be fatal, and there's no way Brown's treatment could be applied to the 33.3 million people around the world living with HIV. The discovery does encourage "cure research," according to Dr. Jay Levy, who co-discovered HIV thirty years ago, something that many people did not even think was possible years ago.

You can watch Brown talk about his cure in this CBS video report.

(Brown: Eric Risberg/AP)

#11 st.maurice

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Posted 13 August 2011 - 08:02

Pronadjen novi lek protiv raka?

Fantastično", „Uzbudljivo", „Veoma značajno"... Američka stručna javnost oduševljeno je dočekala otkriće naučnika sa Univerziteta u Pensilvaniji koristeći reči koje se retko mogu čuti u medicini. Ovo otkriće, kako navodi “Glas Amerike”, predstavlja revoluciju u borbi protiv raka i donosi nadu milionima obolelih širom planete.

Stručnjaci iz Pensilvanije otkrili su potpuno novu tehnologiju u borbi protiv raka, veštački ojačanje ćelije koje love kancerogene ćelije u telu i uništavaju ih, a na ovaj način, kako je saopšteno, već su izlečena dva pacijenta u poodmaklom stadijumu, dok se trećem kancer povlači.

Ovo je već drugo epohalno medicinsko otkriće u samo dva dana, s obzirom na to da je sa prestižnog Instituta za tehniku u Masačusetsu obelodanjeno da je otkriven lek koji usješno ubija čak 15 vrsta virusa, među kojima su gripa, herpes, HIV, boginje, besnilo... Najavljeno je da će se ovaj ilek za nekoliko godina, posle serije testova, naći u opštoj upotrebi, a vest je opisana kao najvažnija u medicini u poslednjih 100 godina, otkako je otkriven penicilin.

“Glas Amerike" navodi da su lekari pre dve večeri širom zemlje horski iskazivali neskriveno oduševljenje najavom da bi rak mogao izgubiti bitku. Nova tehnologija je isprobana na tri pacijenta obolela od leukemije u poodmakloj fazi.

“Eksperimentima smo stvorili armiju serijskih ubica malignih ćelija. Evo kako je to postignuto: svakom pacijentu je uzeta krv i iz nje su uklonjene T ćelije koje organizam koristi za borbu protiv bolesti. Zatim su naučnici u te ćelije ubacili modifikovanu, bezopasnu verziju HIV virusa, a potom su milioni tih genetski izmenjenih ćelija vraćeni u telo pacijenta.

Ideja je da se krvne ćelije samog pacijenta upotrebe za ubijanje kancerogenih. One su ih napale i ne samo da su uništile postojeći kancer, nego i novi čim se pojavio - objasnili su naučnici iz Pensilvanije.
Len Lihtenfeld iz Američkog udruženja za borbu protiv raka rekao je da se ova studija razrađuje decenijama.

“Ovo je studija koja izaziva oduševljenje. Primenjena je na pacijentima i proizvela je zaista važne rezultate. Tokom dve nedele pacijenti nisu osetili nikakvu promenu, ali im se onda stanje veoma pogoršalo i imali su simptome ekstremno teškog gripa. To je bio znak da terapija deluje. Godinu dana posle tretmana dva pacijenta i dalje nemaju rak, a stanje trećeg se poboljšava - navodi Lihtenfeld, i dodaje da je sada cilj da se utvrdi koliko traje remisija.

“Znamo da ove prerađene ćelije mogu neko vreme da pomažu, ali mogu da budu i štetne, tako da stvarno moramo više da saznamo pre nego što budemo mogli da kažemo da ovo može generalno da se koristi kod pacijenata sa rakom, pre svega s leukemijom.


#12 pixel

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Posted 13 August 2011 - 15:08

Američka stručna javnost oduševljeno je dočekala otkriće naučnika sa Univerziteta u Pensilvaniji koristeći reči koje se retko mogu čuti u medicini.

Evo i teksta sa njihovog sajta:

Genetically Modified "Serial Killer" T Cells Obliterate Tumors in Patients with Chronic Lymphocytic Leukemia, Penn Researchers Report

Još jedna vest, potencijalno VEOMA bitna:

NASA Researchers: DNA Building Blocks Can Be Made in Space

NASA-funded researchers have evidence that some building blocks of DNA, the molecule that carries the genetic instructions for life, found in meteorites were likely created in space. The research gives support to the theory that a "kit" of ready-made parts created in space and delivered to Earth by meteorite and comet impacts assisted the origin of life.

#13 st.maurice

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Posted 24 August 2011 - 09:36

Pronadjeni najstariji fosili na Zemlji?

Otkriveni fosili samo potvrdjuju da se zivot na Zemlji razvio iznenadjujuce rano u istoriji, cim mu se ukazala prilika (nakon poslednjeg bombardovanja asteroida koje je sterilisalo povrsinu)


#14 pixel

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Posted 24 August 2011 - 23:20

The natural world contains about 8.7 million species, according to a new estimate described by scientists as the most accurate ever.

Ukoliko se uzme u obzir podatak da je do danas nestalo 99,9% svih vrsta koje su ikada postojale, ovo postaje fascinantno, nepojmljivo čak. Nešto izuzetno.

Edited by pixel, 24 August 2011 - 23:24.

#15 Schrodinger

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Posted 25 August 2011 - 13:58

The natural world contains about 8.7 million species, according to a new estimate described by scientists as the most accurate ever.

Ukoliko se uzme u obzir podatak da je do danas nestalo 99,9% svih vrsta koje su ikada postojale, ovo postaje fascinantno, nepojmljivo čak. Nešto izuzetno.

Pazi, prvo verovatno nije iscezlo 99,9% nego 99,99+%. Ali zasto bi to bilo fascinantno i nepojmljivo? Pa istorija zivota na Zemlji traje 3,8 milijardi godina, a covecanstvo je tu potpuno zanemarljivo, civilizacija tokom koje belezimo stvari jos kraca, tako da je samo antropocentrizam i sebicnost verovati da je ono sto vidimo oko nas ista vise od zanemarljivo malog delica celokupne slike...