362 research outputs found
Frankenstein: The United States in Afghanistan during the 1980s and 1990s
For nearly the past quarter century, the United States has been involved in covert operations in a region of the world that most people could not locate on a map. Invisible wars being fought by the United States and other foreign intelligence agencies in Afghanistan sowed the seeds for the attacks on September 11, 2001. From the Soviet invasion in 1979 to the summer of 2001, intelligence agencies from around the globe have had a stake in supplying, training, and funding the very same people who carried out those terrible attacks. In the middle of this chaotic time period, Osama bin Laden used political manipulation to devise a plan that would leave a scar on the face of a nation for many years to come. This research will give a history of the U.S. government’s involvement in Afghanistan during the 1980s and 1990s. The Taliban and Al-Qaeda would rise from the ashes of the Soviet conflict to become the new enemy of America. To combat these new faceless adversaries, historians need to look at the mistakes made in the past to prevent similar tragedies in the future
A Post-AGB Star in the Small Magellanic Cloud Observed with the Spitzer Infrared Spectrograph
We have observed an evolved star with a rare combination of spectral
features, MSX SMC 029, in the Small Magellanic Cloud (SMC) using the
low-resolution modules of the Infrared Spectrograph on the Spitzer Space
Telescope. A cool dust continuum dominates the spectrum of MSX SMC 029. The
spectrum also shows both emission from polycyclic aromatic hydrocarbons (PAHs)
and absorption at 13.7 micron from C2H2, a juxtaposition seen in only two other
sources, AFGL 2688 and IRAS 13416-6243, both post-asymptotic giant branch (AGB)
objects. As in these sources, the PAH spectrum has the unusual trait that the
peak emission in the 7-9 micron complex lies beyond 8.0 micron. In addition,
the 8.6 micron feature has an intensity as strong as the C-C modes which
normally peak between 7.7 and 7.9 micron. The relative flux of the feature at
11.3 micron to that at 8 micron suggests that the PAHs in MSX SMC 029 either
have a low ionization fraction or are largely unprocessed. The 13-16 micron
wavelength region shows strong absorption features similar to those observed in
the post-AGB objects AFGL 618 and SMP LMC 11. This broad absorption may arise
from the same molecules which have been identified in those sources: C2H2,
C4H2, HC3N, and C6H6. The similarities between MSX SMC 029, AFGL 2688, and AFGL
618 lead us to conclude that MSX SMC 029 has evolved off the AGB in only the
past few hundred years, making it the third post-AGB object identified in the
SMC.Comment: 4 figures, Fig. 4 color; to appear in the 20 November 2006
Astrophysical Journal Letter
Abundances of Baade's Window Giants from Keck/HIRES Spectra: I. Stellar Parameters and [Fe/H] Values
We present the first results of a new abundance survey of the Milky Way bulge
based on Keck/HIRES spectra of 27 K-giants in the Baade's Window (, ) field. The spectral data used in this study are of much higher resolution
and signal-to-noise than previous optical studies of Galactic bulge stars. The
[Fe/H] values of our stars, which range between -1.29 and , were used to
recalibrate large low resolution surveys of bulge stars. Our best value for the
mean [Fe/H] of the bulge is . This mean value is similar to the
mean metallicity of the local disk and indicates that there cannot be a strong
metallicity gradient inside the solar circle. The metallicity distribution of
stars confirms that the bulge does not suffer from the so-called ``G-dwarf''
problem. This paper also details the new abundance techniques necessary to
analyze very metal-rich K-giants, including a new Fe line list and regions of
low blanketing for continuum identification.Comment: Accepted for publication in January 2006 Astrophysical Journal. Long
tables 3--6 withheld to save space (electronic tables in journal paper). 53
pages, 10 figures, 9 table
R CrB Candidates in the Small Magellanic Cloud: Observations of Cold, Featureless Dust with the Spitzer Infrared Spectrograph
We observed 36 evolved stars in the Small Magellanic Cloud (SMC) using the
low-resolution mode of the Infrared Spectrograph (IRS) on the Spitzer Space
Telescope. Two of these stars, MSX SMC 014 and 155, have nearly featureless
spectral energy distributions over the IRS wavelength range (5.2-35 um) and
F_nu peaking at ~8-9 um. The data can be fit by sets of amorphous carbon shells
or by single 600-700 K blackbodies. The most similar spectra found in extant
spectral databases are of R CrB, although the spectral structure seen in R CrB
and similar stars is much weaker or absent in the SMC sources. Both SMC stars
show variability in the near-infrared. Ground-based visual spectra confirm that
MSX SMC 155 is carbon-rich, as expected for R CrB (RCB) stars, and coincides
with an object previously identified as an RCB candidate. The temperature of
the underlying star is lower for MSX SMC 155 than for typical RCB stars. The
strength of the C_2 Swan bands and the low temperature suggest that it may be a
rare DY Per-type star, only the fifth such identified. MSX SMC 014 represents a
new RCB candidate in the SMC, bringing the number of RCB candidates in the SMC
to six. It is the first RCB candidate discovered with Spitzer and the first
identified by its infrared spectral characteristics rather than its visual
variability.Comment: Accepted by ApJ Letters 25 August, 2005, 4 pages (emulateapj), 5
figure
Strangeness production at SPS energies
We present a summary of measurements of strange particles performed by the
experiment NA49 in central and minimum bias Pb+Pb collisions in the beam energy
range 20A - 158A GeV. New results on Xi production in central Pb+Pb collisions
and on Lambda, Xi production in minimum bias collisions are shown. Transverse
mass spectra and rapidity distributions of strange particles at different
energies are compared. The energy dependence of the particle yields and ratios
is discussed. NA49 measurements of the Lambda and Xi enhancement factors are
shown for the first time.Comment: Submitted to J. Phys. G (Proceedings of the 9th International
Conference on Strangeness in Quark Matter, Los Angeles, USA, March 26-31,
2006). 9 pages, 9 figure
The European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC):experiences from a successful ERS Clinical Research Collaboration
In contrast to airway diseases like chronic obstructive pulmonary disease or asthma, and rare diseases such as cystic fibrosis, there has been little research and few clinical trials in bronchiectasis. Guidelines are primarily based on expert opinion and treatment is challenging because of the heterogeneous nature of the disease. In an effort to address decades of underinvestment in bronchiectasis research, education and clinical care, the European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC) was established in 2012 as a collaborative pan-European network to bring together bronchiectasis researchers. The European Respiratory Society officially funded EMBARC in 2013 as a Clinical Research Collaboration, providing support and infrastructure to allow the project to grow. EMBARC has now established an international bronchiectasis registry that is active in more than 30 countries both within and outside Europe. Beyond the registry, the network participates in designing and facilitating clinical trials, has set international research priorities, promotes education and has participated in producing the first international bronchiectasis guidelines. This manuscript article the development, structure and achievements of EMBARC from 2012 to 2017. EDUCATIONAL AIMS: To understand the role of Clinical Research Collaborations as the major way in which the European Respiratory Society can stimulate clinical research in different disease areasTo understand some of the key features of successful disease registriesTo review key epidemiological, clinical and translational studies of bronchiectasis contributed by the European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC) project in the past 5 yearsTo understand the key research priorities identified by EMBARC for the next 5 years
A Case Study for Large-Scale Human Microbiome Analysis Using JCVI’s Metagenomics Reports (METAREP)
As metagenomic studies continue to increase in their number, sequence volume and complexity, the scalability of biological analysis frameworks has become a rate-limiting factor to meaningful data interpretation. To address this issue, we have developed JCVI Metagenomics Reports (METAREP) as an open source tool to query, browse, and compare extremely large volumes of metagenomic annotations. Here we present improvements to this software including the implementation of a dynamic weighting of taxonomic and functional annotation, support for distributed searches, advanced clustering routines, and integration of additional annotation input formats. The utility of these improvements to data interpretation are demonstrated through the application of multiple comparative analysis strategies to shotgun metagenomic data produced by the National Institutes of Health Roadmap for Biomedical Research Human Microbiome Project (HMP) (http://nihroadmap.nih.gov). Specifically, the scalability of the dynamic weighting feature is evaluated and established by its application to the analysis of over 400 million weighted gene annotations derived from 14 billion short reads as predicted by the HMP Unified Metabolic Analysis Network (HUMAnN) pipeline. Further, the capacity of METAREP to facilitate the identification and simultaneous comparison of taxonomic and functional annotations including biological pathway and individual enzyme abundances from hundreds of community samples is demonstrated by providing scenarios that describe how these data can be mined to answer biological questions related to the human microbiome. These strategies provide users with a reference of how to conduct similar large-scale metagenomic analyses using METAREP with their own sequence data, while in this study they reveal insights into the nature and extent of variation in taxonomic and functional profiles across body habitats and individuals. Over one thousand HMP WGS datasets and the latest open source code are available at http://www.jcvi.org/hmp-metarep
Comparative Functional Genomics of Salt Stress in Related Model and Cultivated Plants Identifies and Overcomes Limitations to Translational Genomics
One of the objectives of plant translational genomics is to use knowledge and genes discovered in model species to improve crops. However, the value of translational genomics to plant breeding, especially for complex traits like abiotic stress tolerance, remains uncertain. Using comparative genomics (ionomics, transcriptomics and metabolomics) we analyzed the responses to salinity of three model and three cultivated species of the legume genus Lotus. At physiological and ionomic levels, models responded to salinity in a similar way to crop species, and changes in the concentration of shoot Cl− correlated well with tolerance. Metabolic changes were partially conserved, but divergence was observed amongst the genotypes. Transcriptome analysis showed that about 60% of expressed genes were responsive to salt treatment in one or more species, but less than 1% was responsive in all. Therefore, genotype-specific transcriptional and metabolic changes overshadowed conserved responses to salinity and represent an impediment to simple translational genomics. However, ‘triangulation’ from multiple genotypes enabled the identification of conserved and tolerant-specific responses that may provide durable tolerance across species
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Locative Media and Sociability:Using Location-Based Social Networks to Coordinate Everyday Life
Foursquare was a mobile social networking application that enabled people to share location with friends in the form of “check-ins.” The visualization of surrounding known social connections as well as unknown others has the potential to impact how people coordinate social encounters and forge new social ties. While many studies have explored mobile phones and sociability, there is a lack of empirical research examining location-based social network’s (LSBNs) from a sociability perspective. Drawing on a dataset of original qualitative research with a range of Foursquare users, the paper examines the application in the context of social coordination and sociability in three ways. First, the paper explores if Foursquare is used to organize certain social encounters, and if so, why. Second, the paper examines the visualization of surrounding social connections and whether this leads to “serendipitous encounters.” Lastly, the paper examines whether the use of Foursquare
can produce new social relationships
Hem-1 Complexes Are Essential for Rac Activation, Actin Polymerization, and Myosin Regulation during Neutrophil Chemotaxis
Migrating cells need to make different actin assemblies at the cell's leading and trailing edges and to maintain physical separation of signals for these assemblies. This asymmetric control of activities represents one important form of cell polarity. There are significant gaps in our understanding of the components involved in generating and maintaining polarity during chemotaxis. Here we characterize a family of complexes (which we term leading edge complexes), scaffolded by hematopoietic protein 1 (Hem-1), that organize the neutrophil's leading edge. The Wiskott-Aldrich syndrome protein family Verprolin-homologous protein (WAVE)2 complex, which mediates activation of actin polymerization by Rac, is only one member of this family. A subset of these leading edge complexes are biochemically separable from the WAVE2 complex and contain a diverse set of potential polarity-regulating proteins. RNA interference–mediated knockdown of Hem-1–containing complexes in neutrophil-like cells: (a) dramatically impairs attractant-induced actin polymerization, polarity, and chemotaxis; (b) substantially weakens Rac activation and phosphatidylinositol-(3,4,5)-tris-phosphate production, disrupting the (phosphatidylinositol-(3,4,5)-tris-phosphate)/Rac/F-actin–mediated feedback circuit that organizes the leading edge; and (c) prevents exclusion of activated myosin from the leading edge, perhaps by misregulating leading edge complexes that contain inhibitors of the Rho-actomyosin pathway. Taken together, these observations show that versatile Hem-1–containing complexes coordinate diverse regulatory signals at the leading edge of polarized neutrophils, including but not confined to those involving WAVE2-dependent actin polymerization
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