560 research outputs found
Theory of Multidimensional Solitons
We review a number of topics germane to higher-dimensional solitons in
Bose-Einstein condensates. For dark solitons, we discuss dark band and planar
solitons; ring dark solitons and spherical shell solitons; solitary waves in
restricted geometries; vortex rings and rarefaction pulses; and multi-component
Bose-Einstein condensates. For bright solitons, we discuss instability,
stability, and metastability; bright soliton engineering, including pulsed atom
lasers; solitons in a thermal bath; soliton-soliton interactions; and bright
ring solitons and quantum vortices. A thorough reference list is included.Comment: review paper, to appear as Chapter 5a in "Emergent Nonlinear
Phenomena in Bose-Einstein Condensates: Theory and Experiment," edited by P.
G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez
(Springer-Verlag
New Creation instead of new Exodus : the innerbiblical exegesis and theological transformations of Isaiah 65:17–25
akzeptierte Manuskriptversio
Quantification of Residual Germinal Center Activity and HIV-1 DNA and RNA Levels Using Fine Needle Biopsies of Lymph Nodes during Antiretroviral Therapy
HIV-1 reservoirs are most often studied in peripheral blood (PB), but not all lymphocytes recirculate, particularly T follicular helper (Tfh) CD4+ T cells, as well as germinal center (GC) B cells, in lymph nodes (LNs). Ultrasound-guided fine needle biopsies (FNBs) from inguinal LNs and PB samples were obtained from 10 healthy controls (HCs) and 21 HIV-1-infected subjects [11 antiretroviral therapy (ART) naive and 10 on ART]. Tfh cells and GC B cells were enumerated by flow cytometry. HIV-1 DNA and cell-associated (CA) RNA levels in LNs and PB were quantified by real-time polymerase chain reaction. FNBs were obtained without adverse events. Tfh cells and GC B cells were highly elevated in ART-naive subjects, with a median GC B cell count >300-fold higher than HCs, but also remained higher in 4 out of the 10 subjects on ART. GC B cell counts and Tfh cell counts were highly correlated with each other, and also with activated T cells in LNs but not in blood. Levels of HIV-1 DNA and CA RNA viral burden in highly purified CD4+ T cells from FNBs were significantly elevated compared with those in CD4+ T cells from PB in the ART-naive group, but only trended toward an increase in the ART patients. FNBs enabled minimally invasive access to, and parallel measurement of residual activated T and B cells and viral burden within LNs in HIV-1-infected patients. These FNBs revealed significant GC activity that was not apparent from corresponding PB samples
Negative regulation of syntaxin4/SNAP-23/VAMP2-mediated membrane fusion by Munc18c <i>In Vitro</i>
Background: Translocation of the facilitative glucose transporter GLUT4 from an intracellular store to the plasma membrane is responsible for the increased rate of glucose transport into fat and muscle cells in response to insulin. This represents a specialised form of regulated membrane trafficking. Intracellular membrane traffic is subject to multiple levels of regulation by conserved families of proteins in all eukaryotic cells. Notably, all intracellular fusion events require SNARE proteins and Sec1p/Munc18 family members. Fusion of GLUT4-containing vesicles with the plasma membrane of insulin-sensitive cells involves the SM protein Munc18c, and is regulated by the formation of syntaxin 4/SNAP23/VAMP2 SNARE complexes. Methodology/Principal Findings Here we have used biochemical approaches to characterise the interaction(s) of Munc18c with its cognate SNARE proteins and to examine the role of Munc18c in regulating liposome fusion catalysed by syntaxin 4/SNAP23/VAMP2 SNARE complex formation. We demonstrate that Munc18c makes contacts with both t- and v-SNARE proteins of this complex, and directly inhibits bilayer fusion mediated by the syntaxin 4/SNAP23/VAMP2 SNARE complex. Conclusion/Significance Our reductionist approach has enabled us to ascertain a direct inhibitory role for Munc18c in regulating membrane fusion mediated by syntaxin 4/SNAP23/VAMP2 SNARE complex formation. It is important to note that two different SM proteins have recently been shown to stimulate liposome fusion mediated by their cognate SNARE complexes. Given the structural similarities between SM proteins, it seems unlikely that different members of this family perform opposing regulatory functions. Hence, our findings indicate that Munc18c requires a further level of regulation in order to stimulate SNARE-mediated membrane fusion
Laser Cooling of Optically Trapped Molecules
Calcium monofluoride (CaF) molecules are loaded into an optical dipole trap
(ODT) and subsequently laser cooled within the trap. Starting with
magneto-optical trapping, we sub-Doppler cool CaF and then load CaF
molecules into an ODT. Enhanced loading by a factor of five is obtained when
sub-Doppler cooling light and trapping light are on simultaneously. For trapped
molecules, we directly observe efficient sub-Doppler cooling to a temperature
of . The trapped molecular density of
cm is an order of magnitude greater than in the initial sub-Doppler
cooled sample. The trap lifetime of 750(40) ms is dominated by background gas
collisions.Comment: 5 pages, 5 figure
A review of patients who suddenly deteriorate in the presence of paramedics
<p>Abstract</p> <p>Background</p> <p>The report of the Ministerial Review of Trauma and Emergency Services in Victoria, Australia, recommended that paramedics be permitted to divert to the closest hospital in incidences of life threatening situations prior to and during transport. An audit of patients that suddenly deteriorated in paramedic care was recommended by the Ministerial Review. The objective of the study was to identify the number and outcome of patients who suddenly deteriorated in the presence of paramedics.</p> <p>Methods</p> <p>A retrospective cohort study of trauma patients who suddenly deteriorated in the presence of paramedics during 2002. As there was no standard definition, sudden deterioration was defined using a predetermined set of physiological criteria. Patient care record data of patients who suddenly deteriorated were compared with the State Trauma Registry to determine those who sustained hospital defined major trauma. Patient care records where hospital bypass was undertaken were identified and analysed. Ethics committee approval was obtained.</p> <p>Results</p> <p>There were 2,893 patients that suddenly deteriorated according to predefined criteria. 2,687 (5.1% of the total trauma patients for 2002) were suitable for further analysis. The majority of patients had a sudden decrease in BP (n = 2,463) with 4.3% having hospital defined major trauma. For patients with a sudden decrease in conscious state or a total GCS score of less than 13 (n = 77), 37.7% had hospital defined major trauma; and a sudden increase/decrease in pulse rate and sudden decrease in BP (n = 65), 26.2% had hospital defined major trauma. Only 28 documented incidents of hospital bypass were identified.</p> <p>Conclusion</p> <p>This study suggests that the incidents of patients suddenly deteriorating in the presence of paramedics are low and the incidence of hospital bypass is not well documented.</p
Antihyperlipidemic effects of Pleurotus ostreatus (oyster mushrooms) in HIV-infected individuals taking antiretroviral therapy
<p>Abstract</p> <p>Background</p> <p>Antiretroviral treatment (ART) regimens in HIV patients commonly cause significant lipid elevations, including increases in both triglycerides and cholesterol. Standard treatments for hypercholesterolemia include the HMG CoA reductase inhibitors, or "statins." Because many ART agents and statins share a common metabolic pathway that uses the cytochrome P450 enzyme system, coadministration of ART with statins could increase statin plasma levels significantly. The oyster mushroom, <it>Pleurotus ostreatus</it>, has been shown in animal models to decrease lipid levels - a finding that has been supported by preliminary data in a small human trial.</p> <p>Methods</p> <p>To assess the safety and efficacy of <it>P. ostreatus </it>in patients with HIV and ART-induced hyperlipidemia, a single-arm, open-label, proof-of-concept study of 8 weeks' duration with a target enrollment of 20 subjects was conducted. Study patients with ART-induced elevated non-HDL cholesterol levels (> 160 mg/dL) were enrolled. Participants received packets of freeze-dried <it>P. ostreatus </it>(15 gm/day) to be administered orally for the 8 week trial period. Lipid levels were drawn every two weeks to assess efficacy. Safety assessments included self-reported incidence of muscle aches and measurement of liver and muscle enzymes. Mean within-person change in lipid levels were estimated using generalized estimating equations to account for repeated observations on individuals. A 30 mg/dL decrease in non-HDL cholesterol was deemed clinically significant.</p> <p>Results</p> <p>126 patients were screened to enroll 25, of which 20 completed the 8-week study. The mean age was 46.4 years (36-60). Patients had a mean 13.7 yrs of HIV infection. Mean non-HDL cholesterol was 204.5 mg/dL at day 0 and 200.2 mg/dL at day 56 (mean within-person change = -1.70; 95% confidence interval (CI) = -17.4, 14.0). HDL cholesterol levels increased from 37.8 mg/dL at day 0 to 40.4 mg/dL on day 56 (mean within-person change = 2.6; 95% CI = -0.1, 5.2). Triglycerides dropped from 336.4 mg/dL on day 0 to 273.4 mg/dL on day 56 (mean within-person change = -63.0; 95% CI = -120.9, -5.1). Only 3 individuals achieved a sustained clinically significant (30 mg/dL) decline in non-HDL cholesterol after 8 weeks of therapy. There were no adverse experiences reported other than patients' distaste for the preparation. Liver function tests and muscle enzymes were not affected by the 8 weeks of treatment.</p> <p>Conclusions</p> <p><it>Pleurotus ostreatus </it>as administered in this experiment did not lower non-HDL cholesterol in HIV patients with ART-induced hypercholesterolemia. Small changes in HDL and triglycerides were not of a clinical magnitude to warrant further study.</p> <p>Trial Registration</p> <p>clinicaltrials.gov Identifier: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00069524">NCT00069524</a></p
Massive stars as thermonuclear reactors and their explosions following core collapse
Nuclear reactions transform atomic nuclei inside stars. This is the process
of stellar nucleosynthesis. The basic concepts of determining nuclear reaction
rates inside stars are reviewed. How stars manage to burn their fuel so slowly
most of the time are also considered. Stellar thermonuclear reactions involving
protons in hydrostatic burning are discussed first. Then I discuss triple alpha
reactions in the helium burning stage. Carbon and oxygen survive in red giant
stars because of the nuclear structure of oxygen and neon. Further nuclear
burning of carbon, neon, oxygen and silicon in quiescent conditions are
discussed next. In the subsequent core-collapse phase, neutronization due to
electron capture from the top of the Fermi sea in a degenerate core takes
place. The expected signal of neutrinos from a nearby supernova is calculated.
The supernova often explodes inside a dense circumstellar medium, which is
established due to the progenitor star losing its outermost envelope in a
stellar wind or mass transfer in a binary system. The nature of the
circumstellar medium and the ejecta of the supernova and their dynamics are
revealed by observations in the optical, IR, radio, and X-ray bands, and I
discuss some of these observations and their interpretations.Comment: To be published in " Principles and Perspectives in Cosmochemistry"
Lecture Notes on Kodai School on Synthesis of Elements in Stars; ed. by Aruna
Goswami & Eswar Reddy, Springer Verlag, 2009. Contains 21 figure
Formation of Supermassive Black Holes
Evidence shows that massive black holes reside in most local galaxies.
Studies have also established a number of relations between the MBH mass and
properties of the host galaxy such as bulge mass and velocity dispersion. These
results suggest that central MBHs, while much less massive than the host (~
0.1%), are linked to the evolution of galactic structure. In hierarchical
cosmologies, a single big galaxy today can be traced back to the stage when it
was split up in hundreds of smaller components. Did MBH seeds form with the
same efficiency in small proto-galaxies, or did their formation had to await
the buildup of substantial galaxies with deeper potential wells? I briefly
review here some of the physical processes that are conducive to the evolution
of the massive black hole population. I will discuss black hole formation
processes for `seed' black holes that are likely to place at early cosmic
epochs, and possible observational tests of these scenarios.Comment: To appear in The Astronomy and Astrophysics Review. The final
publication is available at http://www.springerlink.co
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