137 research outputs found
Construction and Measurements of an Improved Vacuum-Swing-Adsorption Radon-Mitigation System
In order to reduce backgrounds from radon-daughter plate-out onto detector
surfaces, an ultra-low-radon cleanroom is being commissioned at the South
Dakota School of Mines and Technology. An improved vacuum-swing-adsorption
radon mitigation system and cleanroom build upon a previous design implemented
at Syracuse University that achieved radon levels of
0.2Bqm. This improved system will employ a better pump and
larger carbon beds feeding a redesigned cleanroom with an internal HVAC unit
and aged water for humidification. With the rebuilt (original) radon mitigation
system, the new low-radon cleanroom has already achieved a 300
reduction from an input activity of Bqm to a
cleanroom activity of Bqm.Comment: 5 pages, 4 figures, Proceedings of Low Radioactivity Techniques (LRT)
2015, Seattle, WA, March 18-20, 201
Near-infrared spectroscopy of the Blue Compact Dwarf galaxy Markarian 59
We present near-infrared (NIR) spectroscopic observations of the blue compact
dwarf (BCD) galaxy Mrk 59, obtained with the TripleSpec spectrograph mounted on
the 3.5m APO telescope. The NIR spectrum of Mrk 59, which covers the 0.90 -
2.40 micron wavelength range, shows atomic hydrogen, molecular hydrogen,
helium, sulfur and iron emission lines. The NIR data have been supplemented by
a SDSS optical spectrum. We found extinction in the BCD to be low [A(V)=0.24
mag] and to be the same in both the optical and NIR ranges. The NIR light does
not reveal hidden star formation. The H2 emission comes from dense clumps and
the H2 vibrational emission line intensities can be accounted for by photon
excitation. No shock excitation is needed. A CLOUDY photoinization model of Mrk
59 reproduces well the observed optical and NIR emission line fluxes. There is
no need to invoke sources of ionization other than stellar radiation.The [FeII]
1.257 and 1.643 micron emission lines, often used as supernova shock indicators
in low-excitation high-metallicity starburst galaxies, cannot play such a role
in high-excitation low-metallicity HII regions such as Mrk 59.Comment: 23 pages, 3 figures, accepted for publication in the Astrophysical
Journa
A bovine lymphosarcoma cell line infected with theileria annulata exhibits an irreversible reconfiguration of host cell gene expression
Theileria annulata, an intracellular parasite of bovine lymphoid cells, induces substantial phenotypic alterations to its host cell including continuous proliferation, cytoskeletal changes and resistance to apoptosis. While parasite induced modulation of host cell signal transduction pathways and NFκB activation are established, there remains considerable speculation on the complexities of the parasite directed control mechanisms that govern these radical changes to the host cell. Our objectives in this study were to provide a comprehensive analysis of the global changes to host cell gene expression with emphasis on those that result from direct intervention by the parasite. By using comparative microarray analysis of an uninfected bovine cell line and its Theileria infected counterpart, in conjunction with use of the specific parasitacidal agent, buparvaquone, we have identified a large number of host cell gene expression changes that result from parasite infection. Our results indicate that the viable parasite can irreversibly modify the transformed phenotype of a bovine cell line. Fifty percent of genes with altered expression failed to show a reversible response to parasite death, a possible contributing factor to initiation of host cell apoptosis. The genes that did show an early predicted response to loss of parasite viability highlighted a sub-group of genes that are likely to be under direct control by parasite infection. Network and pathway analysis demonstrated that this sub-group is significantly enriched for genes involved in regulation of chromatin modification and gene expression. The results provide evidence that the Theileria parasite has the regulatory capacity to generate widespread change to host cell gene expression in a complex and largely irreversible manner
The distribution of water in the high-mass star-forming region NGC 6334I
We present observations of twelve rotational transitions of H2O-16, H2O-18,
and H2O-17 toward the massive star-forming region NGC 6334 I, carried out with
Herschel/HIFI as part of the guaranteed time key program Chemical HErschel
Surveys of Star forming regions (CHESS). We analyze these observations to
obtain insights into physical processes in this region.
We identify three main gas components (hot core, cold foreground, and
outflow) in NGC 6334 I and derive the physical conditions in these components.
The hot core, identified by the emission in highly excited lines, shows a
high excitation temperature of 200 K, whereas water in the foreground component
is predominantly in the ortho- and para- ground states. The abundance of water
varies between 4 10^-5 (outflow) and 10^-8 (cold foreground gas). This
variation is most likely due to the freeze-out of water molecules onto dust
grains. The H2O-18/H2O-17 abundance ratio is 3.2, which is consistent with the
O-18/O-17 ratio determined from CO isotopologues. The ortho/para ratio in water
appears to be relatively low 1.6(1) in the cold, quiescent gas, but close to
the equilibrium value of three in the warmer outflow material (2.5(0.8)).Comment: 7 pages, 3 figures, accepted by A&
Star forming dwarf galaxies
Star forming dwarf galaxies (SFDGs) have a high gas content and low
metallicities, reminiscent of the basic entities in hierarchical galaxy
formation scenarios. In the young universe they probably also played a major
role in the cosmic reionization. Their abundant presence in the local volume
and their youthful character make them ideal objects for detailed studies of
the initial stellar mass function (IMF), fundamental star formation processes
and its feedback to the interstellar medium. Occasionally we witness SFDGs
involved in extreme starbursts, giving rise to strongly elevated production of
super star clusters and global superwinds, mechanisms yet to be explored in
more detail. SFDGs is the initial state of all dwarf galaxies and the relation
to the environment provides us with a key to how different types of dwarf
galaxies are emerging. In this review we will put the emphasis on the exotic
starburst phase, as it seems less important for present day galaxy evolution
but perhaps fundamental in the initial phase of galaxy formation.Comment: To appear in JENAM Symposium "Dwarf Galaxies: Keys to Galaxy
Formation and Evolution", P. Papaderos, G. Hensler, S. Recchi (eds.). Lisbon,
September 2010, Springer Verlag, in pres
Neural Correlates of the Difference between Working Memory Speed and Simple Sensorimotor Speed: An fMRI Study
The difference between the speed of simple cognitive processes and the speed of complex cognitive processes has various psychological correlates. However, the neural correlates of this difference have not yet been investigated. In this study, we focused on working memory (WM) for typical complex cognitive processes. Functional magnetic resonance imaging data were acquired during the performance of an N-back task, which is a measure of WM for typical complex cognitive processes. In our N-back task, task speed and memory load were varied to identify the neural correlates responsible for the difference between the speed of simple cognitive processes (estimated from the 0-back task) and the speed of WM. Our findings showed that this difference was characterized by the increased activation in the right dorsolateral prefrontal cortex (DLPFC) and the increased functional interaction between the right DLPFC and right superior parietal lobe. Furthermore, the local gray matter volume of the right DLPFC was correlated with participants' accuracy during fast WM tasks, which in turn correlated with a psychometric measure of participants' intelligence. Our findings indicate that the right DLPFC and its related network are responsible for the execution of the fast cognitive processes involved in WM. Identified neural bases may underlie the psychometric differences between the speed with which subjects perform simple cognitive tasks and the speed with which subjects perform more complex cognitive tasks, and explain the previous traditional psychological findings
Phosphatidylserine targeting for diagnosis and treatment of human diseases
Cells are able to execute apoptosis by activating series of specific biochemical reactions. One of the most prominent characteristics of cell death is the externalization of phosphatidylserine (PS), which in healthy cells resides predominantly in the inner leaflet of the plasma membrane. These features have made PS-externalization a well-explored phenomenon to image cell death for diagnostic purposes. In addition, it was demonstrated that under certain conditions viable cells express PS at their surface such as endothelial cells of tumor blood vessels, stressed tumor cells and hypoxic cardiomyocytes. Hence, PS has become a potential target for therapeutic strategies aiming at Targeted Drug Delivery. In this review we highlight the biomarker PS and various PS-binding compounds that have been employed to target PS for diagnostic purposes. We emphasize the 35 kD human protein annexin A5, that has been developed as a Molecular Imaging agent to measure cell death in vitro, and non-invasively in vivo in animal models and in patients with cardiovascular diseases and cancer. Recently focus has shifted from diagnostic towards therapeutic applications employing annexin A5 in strategies to deliver drugs to cells that express PS at their surface
Myosin IIA Modulates T Cell Receptor Transport and CasL Phosphorylation during Early Immunological Synapse Formation
Activation of T cell receptor (TCR) by antigens occurs in concert with an elaborate multi-scale spatial reorganization of proteins at the immunological synapse, the junction between a T cell and an antigen-presenting cell (APC). The directed movement of molecules, which intrinsically requires physical forces, is known to modulate biochemical signaling. It remains unclear, however, if mechanical forces exert any direct influence on the signaling cascades. We use T cells from AND transgenic mice expressing TCRs specific to the moth cytochrome c 88–103 peptide, and replace the APC with a synthetic supported lipid membrane. Through a series of high spatiotemporal molecular tracking studies in live T cells, we demonstrate that the molecular motor, non-muscle myosin IIA, transiently drives TCR transport during the first one to two minutes of immunological synapse formation. Myosin inhibition reduces calcium influx and colocalization of active ZAP-70 (zeta-chain associated protein kinase 70) with TCR, revealing an influence on signaling activity. More tellingly, its inhibition also significantly reduces phosphorylation of the mechanosensing protein CasL (Crk-associated substrate the lymphocyte type), raising the possibility of a direct mechanical mechanism of signal modulation involving CasL
The molecular basis of polysaccharide cleavage by lytic polysaccharide monooxygenases.
Lytic polysaccharide monooxygenases (LPMOs) are copper-containing enzymes that oxidatively break down recalcitrant polysaccharides such as cellulose and chitin. Since their discovery, LPMOs have become integral factors in the industrial utilization of biomass, especially in the sustainable generation of cellulosic bioethanol. We report here a structural determination of an LPMO-oligosaccharide complex, yielding detailed insights into the mechanism of action of these enzymes. Using a combination of structure and electron paramagnetic resonance spectroscopy, we reveal the means by which LPMOs interact with saccharide substrates. We further uncover electronic and structural features of the enzyme active site, showing how LPMOs orchestrate the reaction of oxygen with polysaccharide chains.We thank K. Rasmussen and R.M. Borup for experimental assistance, and MAXLAB, Sweden and the European Synchrotron Radiation Facility (ESRF), France, for synchrotron beam time and assistance. This work was supported by the UK Biotechnology and Biological Sciences Research Council (grant numbers BB/L000423 to P.D., G.J.D. and P.H.W., and BB/L021633/1 to G.J.D. and P.H.W.), Agence Française de l'Environnement et de la Maîtrise de l'Energie (grant number 1201C102 to B.H.), the Danish Council for Strategic Research (grant numbers 12-134923 to L.L.L. and 12-134922 to K.S.J.). Travel to synchrotrons was supported by the Danish Ministry of Higher Education and Science through the Instrument Center DANSCATT and the European Community's Seventh Framework Programme (FP7/2007-2013) under BioStruct-X (grant agreement 283570). L.M., S.F., S.C. and H.D. were supported by Institut de Chimie Moléculaire de Grenoble FR 2607, LabEx ARCANE (ANR-11-LABX-0003-01), the PolyNat Carnot Institute and the French Agence Nationale de la Recherche (PNRB2005-11).This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/nchembio.202
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