"At the heart of this technology is a new generation of high-brightness light-emitting diodes," says Harald Haas from the University of Edinburgh, UK. "Very simply, if the LED is on, you transmit a digital 1, if it's off you transmit a 0," Haas says. "They can be switched on and off very quickly, which gives nice opportunities for transmitting data."
It is possible to encode data in the light by varying the rate at which the LEDs flicker on and off to give different strings of 1s and 0s. The LED intensity is modulated so rapidly that human eyes cannot notice, so the output appears constant.
More sophisticated techniques could dramatically increase VLC data rates. Teams at the University of Oxford and the University of Edinburgh are focusing on parallel data transmission using arrays of LEDs, where each LED transmits a different data stream. Other groups are using mixtures of red, green and blue LEDs to alter the light's frequency, with each frequency encoding a different data channel.
Li-Fi, as it has been dubbed, has already achieved blisteringly high speeds in the lab. Researchers at the Heinrich Hertz Institute in Berlin, Germany, have reached data rates of over 500 megabytes per second using a standard white-light LED. Haas has set up a spin-off firm to sell a consumer VLC transmitter that is due for launch next year. It is capable of transmitting data at 100 MB/s - faster than most UK broadband connections.
Once established, VLC could solve some major communication problems. In 2009, the US Federal Communications Commission warned of a looming spectrum crisis: because our mobile devices are so data-hungry we will soon run out of radio-frequency bandwidth. Li-Fi could free up bandwidth, especially as much of the infrastructure is already in place.
"There are around 14 billion light bulbs worldwide, they just need to be replaced with LED ones that transmit data," says Haas. "We reckon VLC is a factor of ten cheaper than Wi-Fi." Because it uses light rather than radio-frequency signals, VLC could be used safely in aircraft, integrated into medical devices and hospitals where Wi-Fi is banned, or even underwater, where Wi-Fi doesn't work at all.
"The time is right for VLC, I strongly believe that," says Haas, who presented his work at TED Global in Edinburgh last week.
But some sound a cautious note about VLC's prospects. It only works in direct line of sight, for example, although this also makes it harder to intercept than Wi-Fi. "There has been a lot of early hype, and there are some very good applications," says Mark Leeson from the University of Warwick, UK. "But I'm doubtful it's a panacea. This isn't technology without a point, but I don't think it sweeps all before it, either."
My studies took me in a completely unexpected direction. The epiphany (pun intended) was rather shocking. The evidence indicates that the personal god is a manifestation of the ego, which explains a plethora of theistic tendencies, including their typical dislike of atheists, who theists subconsciously perceive to be rejecting a part of themselves.
God is Tyler Durden; and the first rule of Jesus Club is you have to talk about Jesus Club. The second rule of Jesus Club is you have to talk about Jesus Club.
The team just unveiled a new photovoltaic energy conversion system that can be powered by heat, the sun’s rays, a hydrocarbon fuel, or a decaying radioisotope. The button-sized power generator that can also run three times longer than a lithium-ion battery of the same weight.
The science behind the device is not necessarily groundbreaking, as engineers have long used the surface of a material to convert heat into precisely tuned wavelengths of light. However MIT’s method to convert light and heat into electricity is much more efficient than previous versions.
Described in the journal Physical Review A, MIT’s breakthrough was enabled by a material with billions of nanoscale pits etched on its surface. When this pitted material absorbs heat, it radiates energy at precisely chosen wavelengths depending on the size of the pits. It is hoped that the technology may one day be used to generate power for spacecraft on long term missions where sunlight may not be available.
“Being able to convert heat from various sources into electricity without moving parts would bring huge benefits,” says Ivan Celanovic, research engineer in MIT’s Institute for Soldier Nanotechnologies (ISN), “especially if we could do it efficiently, relatively inexpensively and on a small scale.” Celanovic went on to say that he believes his team could triple the efficiency of their prototype, adding that “It’s a neat example of how fundamental research in materials can result in new performance that enables a whole spectrum of applications for efficient energy conversion.”
Considering that space firms are looking for new ways to power spacecraft efficiently now that the shuttle fleet has been retired, we imagine NASA will be among the many companies interested in this technology.
They are a daily essential for millions of Britons hoping to ward off ill-health. But despite the millions of pounds spent on vitamin pills, they do nothing for our health, according to a major study.
Researchers spent more than six years following 8,000 people and found that those taking supplements were just as likely to have developed cancer or heart disease as those who took an identical-looking dummy pill.
And when they were questioned on how healthy they felt, there was hardly any difference between the two groups.
Experts said the study – one of the most extensive carried out into vitamin pills – suggested that millions of consumers may be wasting their money on supplements. Many users fall into the category of the ‘worried well’ – healthy adults who believe the pills will insure them against deadly illnesses – according to Catherine Collins, chief dietician at St George’s Hospital in London.
She said: ‘It’s the worried well who are taking these pills to try and protect themselves against Alzheimer’s disease, heart attacks and strokes.
‘But they are wasting their money. This was a large study following people up for a long period of time assessing everything from their mobility and blood pressure to whether they were happy or felt pain.’
Multi-vitamin supplements have become increasingly popular as a quick and easy way of topping up the body’s nutrient levels. But a series of studies have indicated that, for some people, they could actually be harmful.
Two studies published last year suggested supplements could raise the risk of cancer.
One found pills containing vitamin E, ascorbic acid, beta-carotene, selenium and zinc increased the risk of malignant melanoma, the deadliest form of skin cancer, four-fold.
The other discovered women on a daily multi-vitamin pill increased their risk of breast cancer by up to 20 per cent.
While the evidence that vitamins can do harm is still limited, the latest study seems to confirm that many people are at the very least taking them unnecessarily.
A team of French researchers, led by experts at Nancy University, tracked 8,112 volunteers who took either a placebo capsule, or one containing vitamin C, vitamin E, beta-carotene, selenium and zinc, every day for just over six years.
They assessed the state of their health at the beginning and end of the trial, taking a quality of life survey designed to measure everything from mobility and pain to vitality and mental health.
When researchers analysed how many in each group had gone on to develop serious illnesses over the years, they found little difference.
In the supplement group, 30.5 per cent of patients had suffered a major health ‘event’, such as cancer or heart disease.
In the placebo group, the rate was 30.4 per cent.
There were 120 cases of cancer in those taking vitamins, compared to 139 in the placebo group, and 65 heart disease cases, against 57 among the dummy pill users.
In a report on their findings, published in the International Journal of Epidemiology, the researchers said: ‘The perception that supplementation improves general well-being is not supported by this trial.’
Miss Collins said the results of the study ‘reinforce the idea that if you’re worried about your health and start taking multi-vitamins, you will still be worried about it six years later’.
But the Health Supplements Information Service, which is funded by supplements manufacturers, said the finding that vitamins had no impact on how people perceived their health was ‘to be expected’.
Spokeswoman Dr Carrie Ruxton said: ‘The role of vitamin supplements is to prevent deficiencies and make sure people are receiving their recommended levels.
‘They won’t have a measurable impact on how you feel on a day-to-day basis but what they are doing is topping up your recommended levels to the right amount. They are not meant to be a magic bullet.’
Conform cercetarilor, creierul uman prefera gândurile pozitive, optimiste si vestile bune cu privire la viitor, în detrimentul gândurilor si emotiilor negative.
Cercetatorii din cadrul University College din Londra, declara ca aproximativ 80% din oameni sunt optimisti, chiar daca o buna parte din ei nu se recunosc sub aceasta etichetare.
În decursul experimentelor, oamenii de stiinta au testat nivelul optimismului a 14 persoane, ale caror creiere au fost scanate în acest scop.
Când noutatile au fost pozitive, s-a înregistrat mai multa activitate în cadrul lobilor frontali ai creierului, care sunt asociati si cu procesarea erorilor.
În cazul expunerilor la stiri sau evenimente negative, cele mai optimiste persoane înregistrau o activitate minima în lobii frontali, în timp ce subiectii predominant pesimisti prezentau activitate maxima în aceiasi lobi frontali, ca si cum creierul ar fi ales respingerea gândurilor si trairilor negative.
"Spre exemplu, anunturile conform carora fumatul ucide nu sunt eficiente asupra oamenilor care cred ca nu sunt supusi riscului de a face cancer. Rata divorturilor este de aproximativ 50%, dar oamenii nu cred ca vor ajunge vreodata în pragul despartirii. Creierul alege întotdeauna viziuni optimiste. Cu toate ca retelele neuronale sunt exterem de sofisticate, este cumva reconfortant sa vezi cum creierul alege raspunsuri gresite dar optimiste, în ciuda evidentei reale", declara dr. Chris Chambers si dr. Tali Sharot, cercetatorii care au supervizat experiementul.
Uno degli indicatori più usati per valutare la crisi italiana è lo “spread con i bund tedeschi”. Lo spread è considerato infatti un indicatore della capacità di un paese di restituire i prestiti.
Lo stato italiano, per esempio, ha moltissimi debiti, costituiti sostanzialmente da tutti i titoli di stato (Bot, btp ecc) emessi in cambio di soldi presi in prestito da cittadini, banche , altri paesi. Ma oggi l’italia è da questo punto di vista meno credibile (è stata recentemente degradata da due agenzie che valutano le capacità dei debitori di rendere i soldi) e per far acquistare i suoi bot deve offrire interessi sempre più alti.
E siccome lo spread è la differenza o “allargamento” (spread in inglese) di rendimento tra i titoli di Stato (come i btp) italiani e quelli tedeschi (“bund”), meno l’Italia è credibile, più alti sono gli interessi che deve pagare per avere prestiti e più aumenta lo spread con i titoli tedeschi, giudicati molto affidabili.
Pagare alti interessi può infine avere come conseguenza l'impossibilità di ridurre i debiti, il che farebbe di nuovo crollare l'affidabilità del paese, in una spirale sempre più inarrestabile.
Penn Fraser Jillette (born March 5, 1955) is an American magician, comedian, illusionist, juggler, bassist and a best-selling author known for his work with fellow illusionist Teller in the team Penn & Teller, and advocacy of atheism, libertarian philosophy, free-market economics, and scientific skepticism.
Jillette was born in Greenfield, Massachusetts. His mother, Valda R. Jillette (née Parks) (November 8, 1909—January 1, 2000), was a secretary, and his father, Samuel H. Jillette (March 14, 1912—February 14, 1999), worked at Greenfield's Franklin County Jail. Jillette became disenchanted with traditional illusionist acts that presented the craft as authentic magic, such as The Amazing Kreskin on The Tonight Show Starring Johnny Carson. At age eighteen, he saw a show by illusionist James Randi, and became enamored of his approach to magic that openly acknowledged deception as entertainment rather than a mysterious supernatural power. Jillette regularly acknowledges Randi as the one person on the planet he loves the most besides members of his family.
Jillette worked with high school classmate Michael Moschen in developing and performing a juggling act during the years immediately following their 1973 graduation. In 1974, Jillette graduated from Ringling Brothers and Barnum & Bailey Clown College. That same year, he was introduced to Teller by Weir Chrisimer, a mutual friend. The three then formed a three-person act called Asparagus Valley Cultural Society which played in Amherst, Massachusetts and San Francisco, California. In 1981, he and Teller teamed up as Penn & Teller, and went on to do a successful on- and Off Broadway show called "Penn & Teller" that toured nationally.
The device automatically produces classifications similar to those of a sommelier and can be useful in detecting defects during the elaboration of these wines.
Cava varies in type according to the amount of sugar added with the expedition liqueur after secondary fermentation (which produces carbonic gas). Therefore it is useful to know the exact amount of sugar added, since this is what determines the type of cava which will be produced. The resulting classifications are: Brut Nature (<3 g/L, no sugar added), Extra Brut (<6 g/L), Brut (<12 g/L), Extra Dry (12-17 g/L), Dry (17-35 g/L), Medium-Dry (33-50 g/L) and Sweet (>50 g/L).
In order to design the electronic tongue, researchers from the UAB Group of Sensors and Biosensors, led by professor Manel del Valle, identified different cava samples using voltammetric measurements. Thanks to a combination of chemical measurement systems and advanced mathematical procedures -- principal component analysis (PCA), discrete wavelet transform (DWT), and artificial neural network (ANN) -- researchers achieved to copy the human taste system and distinguish between different types of cava, thus obtaining a classification similar to that of a sommelier. Through the use of the second order standard addition method (SOSAM) it was possible to quantify the amount of sugar added in the cava production process, demonstrating the efficiency of these processing tools.
The electronic tongue currently can identify three types of cava: Brut, Brut Nature and Medium-Dry. However, with proper training it will be able to identify all types available on the market.
Researchers of the UAB Group of Sensors and Biosensors, considered one of the world's leading groups in its sector, has spent years working on the development of electronic tongues. It currently is working on perfecting the device through the incorporation of biosensors.
Electronic tongues are bio-inspired systems created with the aim of reproducing human perception senses. The device contains a sensor matrix (with differentiated, broad and complementary response) to obtain chemical information from samples as are obtained by the human senses. Next, the perception of taste is based on the generation of sensory patterns of the nerves activated by the brain and nerve print recognition; this last step is achieved with the use of computerised systems which interpret data obtained by the sensor matrix. As in biological mechanisms, a learning and training process is needed so that the electronic tongue can be capable of recognising the properties that must be identified.
Guma de mestecat fara zahar, dulciurile si bauturile racoritoare, comercializate drept alternative sanatoase la produsele zaharoase, pot deteriora dintii si cauza probleme gastrice.
De asemenea, este foarte putin probabil ca aceste alimente sa favorizeze scaderea în greutate, spun cercetatorii.
Dezvaluirea a ceea cercetatorii au numit "riscul ascuns al produselor fara zahar" ar putea afecta vânzarile acestora, mai ales datorita faptului ca oamenii le considera sanatoase si au încredere în ele.
Studiul, intitulat "Sunt produsele fara zahar cu adevarat benefice sanatatii dentare?" a analizat rolul substantelor folosite în unele produse pentru a reduce riscul aparitiei cariilor. Rezultatele sale au indicat ca în timp ce substantele numite alcooli de zahar sau polioli reduc riscul aparitiei cariilor, ele pot provoca o aciditate în gura care duce la eroziunea smaltului dintilor.
Substantele în cauza includ xilitolul, care este utilizat pe scara larga în multe produse din Uniunea Europeana, el fiind proclamat drept "benefic pentru dantura".
Ca urmare a rezultatelor, cercetatorii de la Universitatile din Boston, Helsinki si Nevada sustin ca publicul ar trebui sa fie informat cu privire la continutul de sorbitol si xilitol al unor produse, având în vedere ca acestea indica un risc ascuns de eroziune. Mai mult, acesti aditivi acizi sunt responsabili si de aparitia unor cazuri de tulburari gastrice si chiar diaree osmotica.
Un tuffo nel vuoto, il paracadute sulle spalle, davanti a sé un paesaggio da mozzare il fiato. Se i voli estremi dei base jumpers si consumano in pochi secondi, a catturarne gli attimi più suggestivi ci pensa questo video diffuso da una piattaforma video australiana dedicata ai filmati di argomento sportivo.
Sullo sfondo di spettacolari salti nel vuoto vi sono le cime di Norvegia, Svizzera e Francia, dove i temerari del volo hanno affrontato cadute libere di 1800 metri e oltre. Basta vederli lanciarsi in slow motion, per avere l'impressone che, in volo, l'adrenalina lasci spazio ad attimi di grande pace e silenzio.
Ma non tutti i lanci vanno a lieto fine. Guarda anche il video della disavventura di Christopher Brewer, un base jumper americano a cui non si è aperto il paracadute. Un sabato Brewer si è lanciato da un'altezza di 270 metri, da un ponte sospeso su un fiume della West Virginia. Il suo paracadute non si è aperto e il 27enne è precipitato in acqua a una velocità di 120 km all'ora. Fortunatamente la tuta alare che indossava ha frenato la caduta e il ragazzo è sopravvissuto. (Immagini sconsigliate a un pubblico sensibile).
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