The Global Toll of Fine Particulate Matter

acquired January 1, 1850 - January 1, 2000

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Occasionally, short-term meteorological conditions merge with ongoing human emissions to produce extreme outbreaks of air pollution. In January 2013, a blanket of industrial pollution enveloped northeastern China. In June 2013, smoke from agricultural fires in Sumatra engulfed Singapore.

In most cases, the most toxic pollution lingers for a few days or even weeks, bringing increases in respiratory and cardiac health problems at hospitals. Eventually the weather breaks, the air clears, and memories of foul air begin to fade. But that’s not to say that the health risks disappear as well. Even slightly elevated levels of air pollution can have a significant effect on human health. Over long periods and on a global scale, such impacts can add up.

But exactly how much exposure to air pollution do people around the world get? And how much health damage is it causing? Since there are gaps in networks of ground sensors, University of North Carolina earth scientist Jason West is leading an effort to answer those questions using computer models that simulate the atmosphere.

In 2010, West published an estimate of the global health effects of air pollution based on a single atmospheric model. More recently, West and colleagues thought they could improve their calculations by using results from a range of atmospheric different models—six in all—rather than relying on just one. In 2013, they published their results in Environmental Research Letters, concluding that 2.1 million deaths occur worldwide each year as a direct result of a toxic type of outdoor air pollution known as fine particulate matter (PM2.5).

The map above shows the model estimate of the average number of deaths per square kilometer per year due to air pollution. The researchers used the difference in pollution levels between 1850 and 2000 as a measure of human-caused air pollution. Dark brown areas have more premature deaths than light brown areas. Blue areas have experienced an improvement in air quality relative to 1850 and a decline in premature deaths.

Fine particulate matter takes an especially large toll in eastern China, northern India, and Europe—all areas where urbanization has added considerable quantities of PM2.5 to the atmosphere since the start of the Industrial Revolution. In these heavily populated and polluted areas (shaded dark brown), air pollution created by humans causes more than 1,000 premature deaths per year per square kilometer.

A few areas—such as the southeastern United States—saw PM2.5 concentrations decline relative to pre-industrial levels (shown in blue), suggesting that premature mortality due to air pollution declined. In the southeastern United States, the decrease in PM2.5 was likely related to a decline in local biomass burning that has occurred over the last 160 years.

References

• Annberg et al, (2010, April 9) An Estimate of the Global Burden of Anthropogenic Ozone and 
Fine Particulate Matter on Premature Human Mortality Using 
Atmospheric Modeling. Environmental Health Perspectives, (118), 1189-1195.
• Discover (2013, July 17) Air Pollution Kills More Than 2 Million People Every Year. Accessed September 16, 2013.
• Institute of Physics (2013, July 12) Researchers estimate over two million deaths annually from air pollution.Accessed September 16, 2013.
• Silva, R. et al, (2013, March 23) Global premature mortality due to anthropogenic outdoor air pollution and the contribution of past climate change. Environmental Research Letters, 8 (3).

Earth Observatory image by Robert Simmon based on data provided by Jason West. Caption by Adam Voiland.Instrument: Model

13h

http://earthobservatory.nasa.gov/IOTD/view.php?id=82087&src=eorss-iotd

Finding Out What Dark Matter Is – And Isn’t

Astronomers using NASA’s Fermi Gamma-Ray Space Telescope have been looking for evidence of suspected types of dark matter particles within faint dwarf galaxies near the Milky Way — relatively “boring” galaxies that have little activity but are known to contain large amounts of dark matter. The results?

These aren’t the particles we’re looking for.

80% of the material in the physical Universe is thought to be made of dark matter — matter that has mass and gravity but does not emit electromagnetic energy (and is thus invisible). Its gravitational effects can be seen, particularly in clouds surrounding galaxies where it is suspected to reside in large amounts. Dark matter can affect the motions of stars, galaxies and even entire clusters of galaxies… but when it all comes down to it, scientists still don’t really know exactly what dark matter is.

Possible candidates for dark matter are subatomic particles called WIMPs (Weakly Interacting Massive Particles). WIMPs don’t absorb or emit light and don’t interact with other particles, but whenever they interact with each other they annihilate and emit gamma rays.

If dark matter is composed of WIMPs, and the dwarf galaxies orbiting the Milky Way do contain large amounts of dark matter, then any gamma rays the WIMPs might emit could be detected by NASA’s Fermi Gamma-Ray Space Telescope.

After all, that’s what Fermi does.

Ten such galaxies — called dwarf spheroids — were observed by Fermi’s Large-Area Telescope (LAT) over a two-year period. The international team saw no gamma rays within the range expected from annihilating WIMPs were discovered, thus narrowing down the possibilities of what dark matter is.

“In effect, the Fermi LAT analysis compresses the theoretical box where these particles can hide,” said Jennifer Siegal-Gaskins, a physicist at the California Institute of Technology in Pasadena and a member of the Fermi LAT Collaboration.

This dwarf spheroidal galaxy is a satellite of our Milky Way and is one of 10 used in Fermi's dark matter search. (Credit: ESO/Digital Sky Survey 2)

So rather than a “failed experiment”, such non-detection means that for the first time researchers can be scientifically sure that WIMP candidates within a specific range of masses and interaction rates cannot be dark matter.

(Sometimes science is about knowing what not to look for.)

A paper detailing the team’s results appeared in the Dec. 9, 2011, issue of Physical Review Letters. Read more on the Fermi mission page here.

by JASON MAJOR on APRIL 3, 2012

http://www.universetoday.com/94418/finding-out-what-dark-matter-is-and-isnt/

Un premier aperçu de l'empreinte d'antiatomes

Une équipe internationale dirigée par des physiciens canadiens de l'Université de Colombie Britannique, de l'Université Simon Fraser et du laboratoire TRIUMF de Vancouver, ont utilisé des micro-ondes pour manipuler des atomes d'anti-hydrogène. Les résultats, qui seront publiés mercredi dans la revue Nature, fournissent au monde entier un premier aperçu d'une "empreinte d'un antiatome". "Pendant des décennies, les scientifiques ont voulu étudier les propriétés intrinsèques des atomes d'antimatière dans l'espoir de trouver des indices qui pourraient aider à répondre à des questions fondamentales sur notre univers", explique l'auteur principal Mike Hayden, un physicien avec l'Université Simon Fraser et membre du projet ALPHA du CERN (Organisation Européenne de Recherche Nucléaire) ".

"Au milieu du siècle dernier, les physiciens ont développé et utilisé de techniques micro-ondes pour étudier les atomes ordinaires comme l'hydrogène. Aujourd'hui, 60 ou 70 ans plus tard, nous avons été témoins des toutes premières interactions micro-ondes avec un antiatome ".

Le travail de l'équipe ALPHA s'est focalisé sur le piégeage stable d'atomes d'anti hydrogène, la contrepartie d'antimatière de l'atome le plus simple, l'hydrogène. Leurs résultats ont été publiés dans trois articles de Nature en un peu plus d'un an. "Cette étude démontre la faisabilité de l'application de la spectroscopie micro-ondes à la manipulation extrêmement difficile d'antiatomes", dit le co-auteur Walter Hardy, un expert de renommée mondiale dans la spectroscopie micro-ondes à UBC. "ALPHA est sur le point d'entrer dans une phase de mise à niveau intensive qui promet de créer une image toujours plus claire de la structure interne des atomes d'antimatière".

L'antimatière est élément de base de la science-fiction, mais elle se distingue également comme l'un des plus grands mystères de la science. Les théories fondamentales prédisent une parfaite symétrie entre matière et antimatière, mais l'absence criante d'antimatière dans notre univers suggère qu'il pourrait exister une différence entre les deux. La spectroscopie micro-ondes est l'une des techniques les plus sensibles pour sonder la structure des atomes.

La mesure utilisée a impliqué le confinement d'antiatomes dans un piège magnétique et leur irradiation micro-ondes. Un réglage précis de la fréquence micro-ondes et du champ magnétique a permis aux chercheurs d'atteindre une résonance interne, sorte de coups de pied aux atomes pour les sortir du piège et pour obtenir des informations sur leurs propriétés.

Hardy et Hayden ont conçu l'appareillage pour cette dernière expérience, en travaillant en étroite collaboration avec les doctorants Ashkezari Mohammad de SFU et Tim Friesen de l'Université de Calgary. Les chercheurs du laboratoire TRIUMF de Vancouver et l'Université York ont alors détecté des signaux faibles à partir d'un système sophistiqué identifiant les événements d'annihilation matière-antimatière.


http://www.bulletins-electroniques.com/actualites/69518.htm

Des particules mesurées à une vitesse dépassant celle de la lumière

PARIS - Des neutrinos, particules élémentaires de la matière, ont été mesurés à une vitesse dépassant légèrement celle de la lumière, jusqu'alors considérée comme une limite infranchissable, ont annoncé jeudi des physiciens du CNRS.

Ce résultat totalement inattendu, vérifié pendant six mois par les spécialistes de l'expérience internationale Opera, doit toutefois encore être confirmé par d'autres expériences.


(©AFP / 22 septembre 2011 20h36)

http://www.romandie.com/news/n/_ALERTE___Des_particules_mesurees_a_une_vitesse_depassant_celle_de_la_lumiere220920112009.asp