Sentences with phrase «when ultraviolet»

Bell explained that p53 stimulates skin tanning when ultraviolet light activates it in the skin.

They showed a slightly weaker preference for the magnetic field when the light was filtered to allow in only some of the ultraviolet and blue light of the spectrum, and they had no preference at all when ultraviolet and blue light were absent.

That airglow arises when individual gas atoms — previously created when ultraviolet light blasted gas molecules apart — later recombine, the researchers explain.

But this study demonstrated that both molecular oxygen and ozone can be made without life when ultraviolet light breaks apart carbon dioxide (a carbon atom bound to two oxygen atoms).

For example, he says, the cosmic ray effect could explain why CFC and ozone levels decline during the Antarctic winter, when ultraviolet radiation is scarce.

The favoured idea is that water is responsible, but some argue that hydrogen peroxide and ozone, which might be created when ultraviolet light breaks down the carbon dioxide and oxygen in the Martian atmosphere, could be involved.

Few foods are natural sources of vitamin D, which is more abundantly produced when ultraviolet radiation from sunlight strikes the skin and triggers synthesis.

Such physical changes to the atmosphere might last only hours or days, he notes, but any subtle chemical changes — including those resulting from the extra hydrogen added to the air when ultraviolet light breaks down the water vapor — would persist much longer.

When ultraviolet rays from the sun fall on methane, they break the molecule into components that form ethane, a constituent of natural gas on Earth.

This only ended when ultraviolet light from the first stars and giant black holes had once again ionised the fog of neutral atoms filling the universe.

Such views suggest that tiny galaxies in the early universe played a crucial role in cosmic reionization — when ultraviolet radiation stripped electrons from hydrogen atoms in the cosmos.

Not exact matches

@Chad: I. Mutations in DNA sequences generally occur through one of two processes: A. Environmental factors: DNA damage from environmental agents such as ultraviolet light (sunshine), nuclear radiation or certain chemicals B. Mistakes that occur when a cell copies its DNA in preparation for cell division.

Finally, when certain ingredients interact with ultraviolet rays, they can morph into an ingredient that can cause a phototoxic, inflammatory reaction.

When illuminated by ultraviolet light they fluoresce and make products and fabrics appear brighter.»

Cool mist humidifiers with filters, cartridges or some ultraviolet lights are the best when it comes to fighting bacteria.

When you add in the germ - fighting power of the ultraviolet light included, it also gives you peace of mind that germs that plague other humidifiers won't be a problem here.

Most jaundice needs no treatment, but when it does, phototherapy (light therapy) is considered very safe and effective: Placing a baby naked in a bassinet, with his eyes covered, under blue «bililights» often does the trick, because ultraviolet light changes the bilirubin to a form that the baby can more easily dispose of in his urine.

Shedding light on the Dark Ages When the first stars formed, their intense ultraviolet light «reionized» the universe, stripping electrons from much of the hydrogen.

So when the solar system is traveling through that part of the galaxy, about every 62 million years, more cosmic rays hit Earth, causing direct radiation, increased ultraviolet rays and perhaps altered weather patterns.

The Methods: Photochemical modeling by a Caltech team indicates that ethane, a hydrocarbon detected on Titan by both of the Voyager spacecraft and the European Infrared Space Observatory, is created when solar ultraviolet light breaks down methane, a minor component of Titan's nitrogen - rich atmosphere, into a stew of organic molecules that form a dense orange - brown smog.

We know that they are under stress when they are fighting cancer or other diseases, so I wondered whether anything measureable could be seen if we put them under further stress with UVA light.We found that people with cancer have DNA which is more easily damaged by ultraviolet light than other people, so the test shows the sensitivity to damage of all the DNA — the genome — in a cell.»

Ground - based remote sensing through ultraviolet and infrared spectroscopy is used to measure the composition of a volcanic plume, the column of hot volcanic ash, gas, and rock emitted when the volcano erupts.

The Lymphocyte Genome Sensitivity (LGS) test looks at white blood cells and measures the damage caused to their DNA when subjected to different intensities of ultraviolet light (UVA), which is known to damage DNA.

Scientists think that when the first stars were born, these luminous objects and the galaxies they formed eventually pumped out X-rays and ultraviolet radiation that ripped electrons from their proton partners.

Ms Alice Koechlin, from the International Prevention Research Institute in Lyon, France, told the meeting that people who were at highest risk of dying from melanoma were those born between 1900 and 1960 when not only were the dangerous effects of exposure to ultraviolet (UV) radiation from sunlight largely unknown, but also health professionals believed that sunshine was positively beneficial.

Haigh's measurements showed that visible radiation increased between 2004 and 2007, when it was expected to decrease, and ultraviolet radiation dropped four times as much as predicted.

When high - energy ultraviolet light from the central star strikes a clump of dust and ice grains, it drives electrons off the particles.

But before the dawn of plants, scientists thought Earth's oxygen originated from a multistep process that starts when carbon dioxide reacts to ultraviolet light.

BARREN TREES Modern dwarf pines (shown) become unable to reproduce when irradiated by ultraviolet - B lamps.

By modeling the reaction, they concluded that the initial energy burst could come from ultraviolet (UV) light, which produces energetic oxygen called singlet oxygen when it breaks up water molecules.

They can also be used for biological labeling because of their low toxicity, chemical stability, and intense luminescence when excited by near - IR radiation, which can penetrate tissue much better than higher energy radiation such as ultraviolet, as is often required with quantum dot labels.

Roth and his colleagues instead went looking in Hubble's ultraviolet images, which can capture the light emitted when hydrogen and oxygen molecules collide with stray electrons.

And ozone, which forms a beneficial shield against ultraviolet radiation when high in the stratosphere, is an efficient greenhouse gas when it appears at airliner altitudes — as it increasingly does, since it too is a by - product of fossil fuel burning.

When the researchers irradiated the THC derivative with ultraviolet light, its structure altered just as the researchers expected, consequently activating the CB1 receptor.

Some substances in drugs, cosmetics and medicinal herbs can be toxic to the skin when exposed to ultraviolet light.

(A set of miscarried twins did show such signs; one of them had a finger that glowed when placed under ultraviolet light.)

But when the researchers spotlighted the frogs with an ultraviolet flashlight, the animals glowed blue - green.

Earth in the days when life was just beginning had no protective ozone layer, so light - dependent, iron - oxidizing bacteria formed iron minerals around themselves to protect them from damaging ultraviolet rays.

Our skin evolved to create vitamin D when it's exposed to the sun's ultraviolet (UV) rays.

The hybrid material melts when heated, and after being exposed to ultraviolet light, it stays melted even when cooled back down.

Their work has already shown that airborne microorganisms die when exposed to ultraviolet rays and titanium dioxide — a common ingredient in toothpaste and a pigment in paint.

When we generate this extreme ultraviolet light, next we have to get it all the way to the sample in a short pulse and then we must have the pump beam perfectly aligned on the sample.

The prostheses were made from a resin that hardens when exposed to ultraviolet laser light.

When the sun is at its most intense, ozone in the stratosphere absorbs more ultraviolet energy, making areas near the equator warmer than usual.

The researchers modified it by inserting azobenzene, a kind of chemical switch that takes on different shapes when illuminated with visible or ultraviolet light.

When an infrared pulse was then injected, they told New Scientist, the white hole converted it to ultraviolet, just as predicted.

In fluorescence microscopy, certain specimens, such as TB bacteria, can be dyed so that they emit light when exposed to ultraviolet radiation.

Niphakis began by making probe molecules that mimic the structure of arachidonoyl lipids and capture protein - binding partners when exposed to ultraviolet light.

For artificial lighting throughout the museum, conservators chose novel bulbs that use ultraviolet LEDs rather than the standard blue ones, and different blends of light - emitting phosphors that better approximate natural light when operated at the low intensity needed to avoid damaging fragile pigments.

When we lost our fur, the sun's ultraviolet rays damaged our newly exposed skin, which reacted by producing melanin, a pigment that absorbs the sun's solar radiation, explain anthropologists at Penn State.