638 research outputs found
High resolution mass spectrometry in molecular structure and stereochemical studies - Effect of stereochemistry on the fragmentation of epimeric derivatives of azabicycloalkanes
High resolution mass spectrometry in studies of stereochemistry effect on fragmentation of epimeric derivatives of azabicycloalkane
Wolf Trap continuation study Final report
Critical evaluation of light and X ray scatter, conductivity, and fluorescence as part of Wolf Trap extraterrestrial life detector developmen
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Transformation Toughening in Ceramics
The origin of transformation toughening in ceramics is examined using two separate approaches: one based on the stress field ahead of the crack and the other on the changes in thermodynamic potential during a crack increment. Both approaches yield essentially similar predictions of trends in toughness with particle size, temperature, composition, etc. The stress intensity analysis provides fully quantitative predictions of the toughness. These indicate that the shielding of the crack by the transformation zone only develops in the presence of a transformed wake, leading to R-curve behavior
The organic geochemistry of ancient sediments, part II
Chemical analysis of sediment and oil hydrocarbon content by gas chromatography and mass spectrometry to establish inception period of bio-organic evolutio
SIRT6 stabilizes DNA-dependent Protein Kinase at chromatin for DNA double-strand break repair
The Sir2 chromatin regulatory factor links maintenance
of genomic stability to life span extension in yeast. The mammalian Sir2
family member SIRT6 has been proposed to have analogous functions, because
SIRT6-deficiency leads to shortened life span and an aging-like
degenerative phenotype in mice, and SIRT6 knockout cells exhibit genomic
instability and DNA damage hypersensitivity. However, the molecular mechanisms
underlying these defects are not fully understood. Here, we show that
SIRT6 forms a macromolecular complex with the DNA double-strand break (DSB)
repair factor DNA-PK (DNA-dependent protein kinase) and promotes DNA DSB
repair. In response to DSBs, SIRT6 associates dynamically with chromatin
and is necessary for an acute decrease in global cellular acetylation
levels on histone H3 Lysine 9. Moreover, SIRT6 is required for
mobilization of the DNA-PK catalytic subunit (DNA-PKcs) to chromatin in response
to DNA damage and stabilizes DNA-PKcs at chromatin adjacent to an induced
site-specific DSB. Abrogation of these SIRT6 activities leads to impaired
resolution of DSBs. Together, these findings elucidate a mechanism whereby
regulation of dynamic interaction of a DNA repair factor with chromatin
impacts on the efficiency of repair, and establish a link between chromatin
regulation, DNA repair, and a mammalian Sir2 factor
Lunar Outgassing, Transient Phenomena and The Return to The Moon, I: Existing Data
Herein the transient lunar phenomena (TLP) report database is subjected to a
discriminating statistical filter robust against sites of spurious reports, and
produces a restricted sample that may be largely reliable. This subset is
highly correlated geographically with the catalog of outgassing events seen by
the Apollo 15, 16 and Lunar Prospector alpha-particle spectrometers for
episodic Rn-222 gas release. Both this robust TLP sample and even the larger,
unfiltered sample are highly correlated with the boundary between mare and
highlands, as are both deep and shallow moonquakes, as well as Po-210, a
long-lived product of Rn-222 decay and a further tracer of outgassing. This
offers another significant correlation relating TLPs and outgassing, and may
tie some of this activity to sagging mare basalt plains (perhaps mascons).
Additionally, low-level but likely significant TLP activity is connected to
recent, major impact craters (while moonquakes are not), which may indicate the
effects of cracks caused by the impacts, or perhaps avalanches, allowing
release of gas. The majority of TLP (and Rn-222) activity, however, is confined
to one site that produced much of the basalt in the Procellarum Terrane, and it
seems plausible that this TLP activity may be tied to residual outgassing from
the formerly largest volcanic ffusion sites from the deep lunar interior. With
the coming in the next few years of robotic spacecraft followed by human
exploration, the study of TLPs and outgassing is both promising and imperiled.
We will have an unprecedented pportunity to study lunar outgassing, but will
also deal with a greater burden of anthropogenic lunar gas than ever produced.
There is a pressing need to study lunar atmosphere and its sources while still
pristine. [Abstract abridged.]Comment: 35 pages, 3 figures, submitted to Icarus. Other papers in series
found at http://www.astro.columbia.edu/~arlin/TLP
What is a sustainable healthy diet? A discussion paper
The food system today is destroying the environment upon which future food production depends.
While the food system generates enough food energy for our population of over 7 billion it does not deliver adequate and affordable nutrition for all. About half the global population is inadequately or inappropriately nourished.
Without action, these problems are set to become acute. As our global population grows, urbanises and becomes wealthier, it is demanding more resource intensive, energy rich foods.
What, and how much we eat directly affects what, and how much is produced. We therefore need to consume more „sustainable diets‟ – diets that have lower environmental impacts, and are healthier.
But what does such a diet look like? Can health, environmental sustainability, and all the other goals we have for our food system really be reconciled, or will there be trade offs
General scientific guidance for stakeholders on health claim applications
The European Food Safety Authority (EFSA) asked the Panel on Dietetic Products Nutrition and Allergies (NDA) to update the General guidance for stakeholders on the evaluation of Article 13.1, 13.5 and 14 health claims published in March 2011. Since then, the NDA Panel has completed the evaluation of Article 13.1 claims except for claims put on hold by the European Commission, and has evaluated additional health claim applications submitted pursuant to Articles 13.5, 14 and also 19. In addition, comments received from stakeholders indicate that general issues that are common to all health claims need to be further clarified and addressed. This guidance document aims to explain the general scientific principles applied by the NDA Panel for the evaluation of all health claims and outlines a series of steps for the compilation of applications. The general guidance document represents the views of the NDA Panel based on the experience gained to date with the evaluation of health claims, and it may be further updated, as appropriate, when additional issues are addressed
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