2,602 research outputs found
Combustion of the butanol isomers: reaction pathways at elevated pressures from low-to-high temperatures
Identification of a neuropeptide precursor protein that gives rise to a "cocktail" of peptides that bind Cu(II) and generate metal-linked dimers
The Transparency document associated with this article can be
found,in online version.This work was supported by a Leverhulme Trust grant (RPG-2013-351) awarded to MRE and National Science Foundation (USA) grant awards DEB 1036416, 1036358, 1036366, and 1036368
A Critical Appraisal of Guidelines for Antenatal Care: Components of Care and Priorities in Prenatal Education
There are a variety of published prenatal care (PNC) guidelines that claim a scientific basis for the information included. Four sets of PNC guidelines published between 2005 and 2009 were examined and critiqued. The recommendations for assessment procedures, laboratory testing, and education/counseling topics were analyzed within and between these guidelines. The PNC components were synthesized to provide an organized, comprehensive appendix that can guide providers of antepartum care. The appendix may be used to locate which guidelines addressed which topics to assist practitioners to identify evidence sources. The suggested timing for introducing and reinforcing specific topics is also presented in the appendix. Although education is often assumed to be a vital component of PNC, it was inconsistently included in the guidelines that were reviewed. Even when education was included, important detail was lacking. Addressing each woman\u27s needs as the first priority was suggested historically and remains relevant in current practice to systematically provide care while maintaining the woman as the central player. More attention to gaps in current research is important for the development of comprehensive prenatal guidelines that contribute effectively to the long‐term health and well‐being of women, families, and their communities
Chandra observations of Cygnus OB2
Cygnus OB2 is the nearest example of a massive star forming region,
containing over 50 O-type stars and hundreds of B-type stars. We have analyzed
two Chandra pointings in Cyg OB2, detecting ~1700 X-ray sources, of which ~1450
are thought to be members of the association. Optical and near-IR photometry
has been obtained for ~90% of these sources from recent deep Galactic plane
surveys. We have performed isochrone fits to the near-IR color-magnitude
diagram, deriving ages of 3.5(+0.75,-1.0) and 5.25(+1.5,-1.0) Myrs for sources
in the two fields, both with considerable spreads around the pre-MS isochrones.
The presence of a second population in the region, somewhat older than the
present-day O-type stars, has been suggested by other authors and fits with the
ages derived here. The fraction of sources with inner circumstellar disks (as
traced by the K-band excess) is found to be very low, but appropriate for a
population of age ~5 Myrs. We measure the stellar mass functions and find a
power-law slope of Gamma = -1.09 +/- 0.13, in good agreement with the global
mean value estimated by Kroupa. A steepening of the mass function at high
masses is observed and we suggest this is due to the presence of the previous
generation of stars that have lost their most massive members. Finally,
combining our mass function and an estimate of the radial density profile of
the association suggests a total mass of Cyg OB2 of ~30,000 Msun, similar to
that of many of our Galaxy's most massive star forming regions.Comment: 6 pages, 4 figures, conference proceedings for JENAM 2010: Star
Clusters in the Era of Large Surveys, Editors: A.Moitinho and J. Alve
Abscisic Acid Insensitive 4 transcription factor is an important player in the response of Arabidopsis thaliana to two-spotted spider mite (Tetranychus urticae) feeding.
Plants growing in constantly changeable environmental conditions are compelled to evolve regulatory mechanisms to cope with biotic and abiotic stresses. Effective defence to invaders is largely connected with phytohormone regulation, resulting in the production of numerous defensive proteins and specialized metabolites. In our work, we elucidated the role of the Abscisic Acid Insensitive 4 (ABI4) transcription factor in the plant response to the two-spotted spider mite (TSSM). This polyphagous mite is one of the most destructive herbivores, which sucks mesophyll cells of numerous crop and wild plants. Compared to the wild-type (Col-0) Arabidopsis thaliana plants, the abi4 mutant demonstrated increased susceptibility to TSSM, reflected as enhanced female fecundity and greater frequency of mite leaf damage after trypan blue staining. Because ABI4 is regarded as an important player in the plastid-to-nucleus retrograde signalling process, we investigated the plastid envelope membrane dynamics using stroma-associated fluorescent marker. Our results indicated a clear increase in the number of stroma-filled tubular structures deriving from the plastid membrane (stromules) in the close proximity of the site of mite leaf damage, highlighting the importance of chloroplast-derived signals in the response to TSSM feeding activity
Identifying metabolites by integrating metabolome databases with mass spectrometry cheminformatics.
Novel metabolites distinct from canonical pathways can be identified through the integration of three cheminformatics tools: BinVestigate, which queries the BinBase gas chromatography-mass spectrometry (GC-MS) metabolome database to match unknowns with biological metadata across over 110,000 samples; MS-DIAL 2.0, a software tool for chromatographic deconvolution of high-resolution GC-MS or liquid chromatography-mass spectrometry (LC-MS); and MS-FINDER 2.0, a structure-elucidation program that uses a combination of 14 metabolome databases in addition to an enzyme promiscuity library. We showcase our workflow by annotating N-methyl-uridine monophosphate (UMP), lysomonogalactosyl-monopalmitin, N-methylalanine, and two propofol derivatives
To respond or not to respond - a personal perspective of intestinal tolerance
For many years, the intestine was one of the poor relations of the immunology world, being a realm inhabited mostly by specialists and those interested in unusual phenomena. However, this has changed dramatically in recent years with the realization of how important the microbiota is in shaping immune function throughout the body, and almost every major immunology institution now includes the intestine as an area of interest. One of the most important aspects of the intestinal immune system is how it discriminates carefully between harmless and harmful antigens, in particular, its ability to generate active tolerance to materials such as commensal bacteria and food proteins. This phenomenon has been recognized for more than 100 years, and it is essential for preventing inflammatory disease in the intestine, but its basis remains enigmatic. Here, I discuss the progress that has been made in understanding oral tolerance during my 40 years in the field and highlight the topics that will be the focus of future research
Strength development characteristics of concrete produced with blended cement using Ground Granulated Blast furnace Slag (GGBS) under various curing conditions
Astronomical Spectroscopy
Spectroscopy is one of the most important tools that an astronomer has for
studying the universe. This chapter begins by discussing the basics, including
the different types of optical spectrographs, with extension to the ultraviolet
and the near-infrared. Emphasis is given to the fundamentals of how
spectrographs are used, and the trade-offs involved in designing an
observational experiment. It then covers observing and reduction techniques,
noting that some of the standard practices of flat-fielding often actually
degrade the quality of the data rather than improve it. Although the focus is
on point sources, spatially resolved spectroscopy of extended sources is also
briefly discussed. Discussion of differential extinction, the impact of
crowding, multi-object techniques, optimal extractions, flat-fielding
considerations, and determining radial velocities and velocity dispersions
provide the spectroscopist with the fundamentals needed to obtain the best
data. Finally the chapter combines the previous material by providing some
examples of real-life observing experiences with several typical instruments.Comment: An abridged version of a chapter to appear in Planets, Stars and
Stellar Systems, to be published in 2011 by Springer. Slightly revise
The extraordinary evolutionary history of the reticuloendotheliosis viruses
The reticuloendotheliosis viruses (REVs) comprise several closely related amphotropic retroviruses isolated from birds. These viruses exhibit several highly unusual characteristics that have not so far been adequately explained, including their extremely close relationship to mammalian retroviruses, and their presence as endogenous sequences within the genomes of certain large DNA viruses. We present evidence for an iatrogenic origin of REVs that accounts for these phenomena. Firstly, we identify endogenous retroviral fossils in mammalian genomes that share a unique recombinant structure with REVs—unequivocally demonstrating that REVs derive directly from mammalian retroviruses. Secondly, through sequencing of archived REV isolates, we confirm that contaminated Plasmodium lophurae stocks have been the source of multiple REV outbreaks in experimentally infected birds. Finally, we show that both phylogenetic and historical evidence support a scenario wherein REVs originated as mammalian retroviruses that were accidentally introduced into avian hosts in the late 1930s, during experimental studies of P. lophurae, and subsequently integrated into the fowlpox virus (FWPV) and gallid herpesvirus type 2 (GHV-2) genomes, generating recombinant DNA viruses that now circulate in wild birds and poultry. Our findings provide a novel perspective on the origin and evolution of REV, and indicate that horizontal gene transfer between virus families can expand the impact of iatrogenic transmission events
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