539 research outputs found
Response to combination therapy with interferon alfa-2a and ribavirin in chronic hepatitis C according to a TNF-alpha promoter polymorphism
Background. Tumor necrosis factor-alpha (TNF-alpha) is involved in the pathogenesis of chronic active hepatitis C. Polymorphisms in the promoter region of the TNF-alpha gene can alter the TNF-alpha expression and modify the host immune response. The present study aimed at the correlation of the G308A TNF-alpha polymorphism with the response to antiviral combination therapy in chronic hepatitis C. Patients and Methods: 62 patients with HCV and 119 healthy unrelated controls were genotyped for the G308A TNF-alpha promoter polymorphism. The patients received 3 x 3 million units of interferon alfa-2a and 1,0001,200 mg ribavirin daily according to their body weight. A response was defined as absence of HCV-RNA and normalization of S-ALT after 6 months of combination therapy. Results:With respect to the allele and genotype frequency, a significant difference was not observed between controls and patients with chronic hepatitis C. Furthermore, such a difference was also not observed if responders and non-responders to antiviral therapy were compared. Conclusions: The promoter polymorphism of the TNF-alpha gene investigated herein is equally distributed in healthy individuals and patients with hepatitis C and does not seem to predict the response to therapy with interferon alfa-2a and ribavirin. Copyright (C) 2003 S. Karger AG, Basel
Повторный гидравлический разрыв пласта в горизонтальных скважинах с нецементируемым хвостовиком
Myocardial perfusion imaging with 99mTc-tetrofosmin is based on the assumption of a linear correlation between myocardial blood flow (MBF) and tracer uptake. However, it is known that 99mTc-tetrofosmin uptake is directly related to energy-depen-dent transport processes, such as Na/H ion channel activity, as well as cellular and mitochondrial membrane potentials. Therefore, cellular alterations that affect these energy-depen-dent transport processes ought to influence 99mTc-tetrofosmin uptake independently of blood flow. Because metabolism (18F-FDG)–perfusion (99mTc-tetrofosmin) mismatch myocardium (MPMM) reflects impaired but viable myocardium showing cel-lular alterations, MPMM was chosen to quantify the blood flow– independent effect of cellular alterations on 99mTc-tetrofosmin uptake. Therefore, we compared microsphere-equivalent MBF (MBF_micr; 15O-water PET) and 99mTc-tetrofosmin uptake i
Detecting the Companions and Ellipsoidal Variations of RS CVn Primaries: I. sigma Geminorum
To measure the properties of both components of the RS CVn binary sigma
Geminorum (sigma Gem), we directly detect the faint companion, measure the
orbit, obtain model-independent masses and evolutionary histories, detect
ellipsoidal variations of the primary caused by the gravity of the companion,
and measure gravity darkening. We detect the companion with interferometric
observations obtained with the Michigan InfraRed Combiner (MIRC) at Georgia
State University's Center for High Angular Resolution Astronomy (CHARA) Array
with a primary-to-secondary H-band flux ratio of 270+/-70. A radial velocity
curve of the companion was obtained with spectra from the Tillinghast Reflector
Echelle Spectrograph (TRES) on the 1.5-m Tillinghast Reflector at Fred Lawrence
Whipple Observatory (FLWO). We additionally use new observations from the
Tennessee State University Automated Spectroscopic and Photometric Telescopes
(AST and APT, respectively). From our orbit, we determine model-independent
masses of the components (M_1 = 1.28 +/- 0.07 M_Sun, M_2 = 0.73 +/- 0.03
M_Sun), and estimate a system age of 5 -/+ 1 Gyr. An average of the 27-year APT
light curve of sigma Gem folded over the orbital period (P = 19.6027 +/- 0.0005
days) reveals a quasi-sinusoidal signature, which has previously been
attributed to active longitudes 180 deg apart on the surface of sigma Gem. With
the component masses, diameters, and orbit, we find that the predicted light
curve for ellipsoidal variations due to the primary star partially filling its
Roche lobe potential matches well with the observed average light curve,
offering a compelling alternative explanation to the active longitudes
hypothesis. Measuring gravity darkening from the light curve gives beta < 0.1,
a value slightly lower than that expected from recent theory.Comment: Accepted to ApJ, 11 pages, 6 figures, 8 table
Blunt cerebrovascular trauma causing vertebral arteryd issection in combination with a laryngeal fracture: a case report
<p>Abstract</p> <p>Introduction</p> <p>The diagnosis and therapy of blunt cerebrovascular injuries has become a focus since improved imaging technology allows adequate description of the injury. Although it represents a rare injury the long-term complications can be fatal but mostly prevented by adequate treatment.</p> <p>Case presentation</p> <p>A 33-year-old Caucasian man fell down a 7-meter scarp after losing control of his quad bike in a remote area. Since endotracheal intubation was unsuccessfully attempted due to the severe cervical swelling as well as oral bleeding an emergency tracheotomy was performed on scene. He was hemodynamically unstable despite fluid resuscitation and intravenous therapy with vasopressors and was transported by a helicopter to our trauma center. He had a stable fracture of the arch of the seventh cervical vertebra and fractures of the transverse processes of C5-C7 with involvement of the lateral wall of the transverse foramen. An abort of the left vertebral artery signal at the first thoracic vertebrae with massive hemorrhage as well as a laryngeal fracture was also detected. Further imaging showed retrograde filling of the left vertebral artery at C5 distal of the described abort. After stabilization and reconfirmation of intracranial perfusion during the clinical course weaning was started. At the time of discharge, he was aware and was able to move all extremities.</p> <p>Conclusion</p> <p>We report a rare case of a patient with vertebral artery dissection in combination with a laryngeal fracture after blunt trauma. Thorough diagnostic and frequent reassessments are recommended. Most patients can be managed with conservative treatment.</p
Carbon incorporation in MOCVD of MoS2 thin films grown from an organosulfide precursor
Altres ajuts: CERCA Programme/Generalitat de CatalunyaWith the rise of two-dimensional (2D) transition-metal dichalcogenide (TMD) semiconductors and their prospective use in commercial (opto)electronic applications, it has become key to develop scalable and reliable TMD synthesis methods with well-monitored and controlled levels of impurities. While metal-organic chemical vapor deposition (MOCVD) has emerged as the method of choice for large-scale TMD fabrication, carbon (C) incorporation arising during MOCVD growth of TMDs has been a persistent concern-especially in instances where organic chalcogen precursors are desired as a less hazardous alternative to more toxic chalcogen hydrides. However, the underlying mechanisms of such unintentional C incorporation and the effects on film growth and properties are still elusive. Here, we report on the role of C-containing side products of organosulfur precursor pyrolysis in MoS2 thin films grown from molybdenum hexacarbonyl Mo(CO)6 and diethyl sulfide (CH3CH2)2S (DES). By combining in situ gas-phase monitoring with ex situ microscopy and spectroscopy analyses, we systematically investigate the effect of temperature and Mo(CO)6/DES/H2 gas mixture ratios on film morphology, chemical composition, and stoichiometry. Aiming at high-quality TMD growth that typically requires elevated growth temperatures and high DES/Mo(CO)6 precursor ratios, we observed that temperatures above DES pyrolysis onset (â 600 °C) and excessive DES flow result in the formation of nanographitic carbon, competing with MoS2 growth. We found that by introducing H2 gas to the process, DES pyrolysis is significantly hindered, which reduces carbon incorporation. The C content in the MoS2 films is shown to quench the MoS2 photoluminescence and influence the trion-To-exciton ratio via charge transfer. This finding is fundamental for understanding process-induced C impurity doping in MOCVD-grown 2D semiconductors and might have important implications for the functionality and performance of (opto)electronic devices
Holocene glacier culminations in the Western Alps and their hemispheric relevance
The natural variability of Holocene climate defines the baseline to assess ongoing climate change. Greenland ice-core records indicate warming superimposed by abrupt climate oscillations in the early Holocene, followed by a general cooling trend throughout the middle and late Holocene that culminated during the Little Ice Age (LIA). Tropical precipitation changes correlate with these patterns throughout the Holocene. Here we use mountain glaciers in the European Alps to reconstruct the regional Holocene climate evolution and to test for a link between mid-latitude, North Atlantic, and tropical climate. Our precise 10Be chronology from Tsidjiore Nouve Glacier, western Swiss Alps, indicates a glacier culmination during the earliest Holocene ∼11.4 k.y. ago, likely related to the Preboreal Oscillation. Based on our data, no Holocene glacier advance of similar amplitude occurred until ∼3.8 k.y. ago, when the glacier reached LIA limits. The 10Be ages between 500 and 170 yr correspond to the LIA, while the youngest 10Be ages overlap with the historically recorded post-LIA glacier positions. Integrating our data with existing records, we propose a hemispheric climate link between the Alps, North Atlantic temperature, and tropical precipitation patterns for the Holocene, supporting the concept of a pervasive climate driver. These findings from northern mid-latitudes are consistent with the hypothesis formulated for the tropics that the Earth’s thermal equator, responding to North Atlantic temperature changes, might have migrated southward throughout the Holocene, reaching the southern turning point toward the end of the LIA
Native defect association in beta-Ga2O3 enables room-temperature p-type conductivity
The room temperature hole conductivity of the ultra wide bandgap
semiconductor beta Ga2O3 is a pre-requisite for developing the next-generation
electronic and optoelectronic devices based on this oxide. In this work,
high-quality p-type beta-Ga2O3 thin films grown on r-plane sapphire substrate
by metalorganic chemical vapor deposition (MOCVD) exhibit Rho = 50000Ohm.cm
resistivity at room temperature. A low activation energy of conductivity as
Ea2=170 meV was determined, associated to the oxygen - gallium native acceptor
defect complex. Further, taking advantage of cation (Zn) doping, the
conductivity of Ga2O3:Zn film was remarkably increased by three orders of
magnitude, showing a long-time stable room-temperature hole conductivity with
the conductivity activation energy of around 86 meV.Comment: 21pages; 9figure
Agonist-mediated switching of ion selectivity in TPC2 differentially promotes lysosomal function
Ion selectivity is a defining feature of a given ion channel and is considered immutable. Here we show that ion selectivity of the lysosomal ion channel TPC2, which is hotly debated (Calcraft et al., 2009;Guo et al., 2017;Jha et al., 2014;Ruas et al., 2015;Wang et al., 2012), depends on the activating ligand. A high-throughput screen identified two structurally distinct TPC2 agonists. One of these evoked robust Ca2+-signals and non-selective cation currents, the other weaker Ca2+-signals and Na+-selective currents. These properties were mirrored by the Ca2+ mobilizing messenger, NAADP and the phosphoinositide, PI(3,5)P-2, respectively. Agonist action was differentially inhibited by mutation of a single TPC2 residue and coupled to opposing changes in lysosomal pH and exocytosis. Our findings resolve conflicting reports on the permeability and gating properties of TPC2 and they establish a new paradigm whereby a single ion channel mediates distinct, functionally-relevant ionic signatures on demand
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