1,662 research outputs found
Radiation-hard ASICs for optical data transmission in the ATLAS pixel detector
We have developed two radiation-hard ASICs for optical data transmission in
the ATLAS pixel detector at the LHC at CERN: a driver chip for a Vertical
Cavity Surface Emitting Laser (VCSEL) diode for 80 Mbit/s data transmission
from the detector, and a Bi-Phase Mark decoder chip to recover the control data
and 40 MHz clock received optically by a PIN diode. We have successfully
implemented both ASICs in 0.25 um CMOS technology using enclosed layout
transistors and guard rings for increased radiation hardness. We present
results from prototype circuits and from irradiation studies with 24 GeV
protons up to 57 Mrad (1.9 x 10e15 p/cm2).Comment: 8th Tropical Seminar on Innovative Particle and Radiation Detectors,
Siena, Italy (2002
Effects of manipulating hypothalamic triiodothyronine concentrations on seasonal body weight and torpor cycles in siberian hamsters
Peer reviewedPublisher PD
ILC Beam Energy Measurement by means of Laser Compton Backscattering
A novel, non-invasive method of measuring the beam energy at the
International Linear Collider is proposed. Laser light collides head-on with
beam particles and either the energy of the Compton scattered electrons near
the kinematic end-point is measured or the positions of the Compton
backscattered -rays, the edge electrons and the unscattered beam
particles are recorded. A compact layout for the Compton spectrometer is
suggested. It consists of a bending magnet and position sensitive detectors
operating in a large radiation environment. Several options for high spatial
resolution detectors are discussed. Simulation studies support the use of an
infrared or green laser and quartz fiber detectors to monitor the backscattered
photons and edge electrons. Employing a cavity monitor, the beam particle
position downstream of the magnet can be recorded with submicrometer precision.
Such a scheme provides a feasible and promising method to access the incident
beam energy with precisions of or better on a bunch-to-bunch basis
while the electron and positron beams are in collision.Comment: 47 pages, 26 figures, version as accepted by Nucl. Instr. Meth. A
after improvement
IL10-Deficiency in CD4+ T Cells Exacerbates the IFNγ and IL17 Response During Bacteria Induced Colitis
Background/Aims: IL10 is a key inhibitor of effector T cell activation and a
mediator of intestinal homeostasis. In addition, IL10 has emerged as a key
immunoregulator during infection with various pathogens, ameliorating the
excessive T-cell responses that are responsible for much of the
immunopathology associated with the infection. Because IL10 plays an important
role in both intestinal homeostasis and infection, we studied the function of
IL10 in infection-associated intestinal inflammation. Methods: Wildtype mice
and mice deficient in CD4+ T cell-derived or regulatory T cells-derived IL10
were infected with the enteric pathogen Citrobacter (C.) rodentium and
analyzed for the specific immune response and pathogloy in the colon. Results:
We found that IL10 expression is upregulated in colonic tissue after infection
with C. rodentium, especially in CD4+ T cells, macrophages and dendritic
cells. Whereas the deletion of IL10 in regulatory T cells had no effect on C.
rodentium induced colitis, infection of mice deficient in CD4+ T cell-derived
IL10 exhibited faster clearance of the bacterial burden but worse colitis,
crypt hyperplasia, and pathology than did WT mice. In addition, the depletion
of CD4+ T cell-derived IL10 in infected animals was accompanied by an
accelerated IFNγ and IL17 response in the colon. Conclusion: Thus, we conclude
that CD4+ T cell-derived IL10 is strongly involved in the control of C.
rodentium-induced colitis. Interference with this network could have
implications for the treatment of infection-associated intestinal
inflammation
Recommended from our members
Acid-base properties, deactivation, and in situ regeneration of condensation catalysts for synthesis of methyl methacrylate
Condensation reaction of a propionate with formaldehyde is a novel route for synthesis of methyl methacrylate (MMA). The reaction mechanism involves a proton abstraction from the propionate on the basic sites and activation of the aliphatic aldehyde on the acidic sites of the catalyst. The acid-base properties of ternary V-Si-P oxide catalysts and their relation to the NWA yield in the vapor phase condensation of formaldehyde with propionic anhydride has been studied for the first time. Five different V-Si-P catalysts with different atomic ratios of vanadium, silicon, and phosphorous were synthesized, characterized, and tested in a fixed-bed microreactor system. A V-Si-P 1:10:2.8 catalyst gave the maximum condensation yield of 56% based on HCHO fed at 300{degrees}C and 2 atm and at a space velocity of 290 cc/g cat{center_dot}h. A parameter called the ``q-ratio`` has been defined to correlate the condensation yields to the acid-base properties. The correlation of q-ratio with the condensation yield shows that higher q-ratios are more desirable. The long-term deactivation studies on the V-Si-P 1: 10:2.8 catalyst at 300{degrees}C and 2 atm and at a space velocity of 290 cc/g cat{center_dot}h show that the catalyst activity drops by a factor of nearly 20 over a 180 h period. The activity can be restored to about 78% of the initial activity by a mild oxidative regeneration at 300{degrees}C and 2 atm. The performance of V-Si-P catalyst has been compared to a Ta/SiO{sub 2} catalyst. The Ta- catalyst is more stable and has a higher on-stream catalyst life
Insights from twenty years of comparative research in Pacific Large Ocean States
Under global environmental change, understanding the interactions between people and nature has become critical for human survival. Comparative research can identify trends within social-ecological systems providing key insights for both environmental and developmental research. Island systems, with clear land boundaries, have been proposed as ideal case studies for comparative research, but it is unclear to what extent their potential has been fulfilled. To summarize existing research and identify potential gaps and new directions, we reviewed comparative environmental and developmental research on Pacific Large Ocean States. A diversity of case study locations and research themes were addressed within the sample of reviewed studies. Within the reviewed literature climate change, energy infrastructure, trade and fisheries were key themes of environmental and developmental research compared between island systems. Research was biased towards wealthier Pacific Large Ocean States and those with a relatively higher degree of socio-economic development. Our review highlights the potential value of a stronger a priori inclusion of spatial scale and conceptual frameworks, such as spatial resilience, to facilitate generalization from case studies
ATLAS Pixel Opto-Electronics
We have developed two radiation-hard ASICs for optical data transmission in
the ATLAS pixel detector at the LHC at CERN: a driver chip for a Vertical
Cavity Surface Emitting Laser (VCSEL) diode for 80 Mbit/s data transmission
from the detector, and a Bi-Phase Mark decoder chip to recover the control data
and 40 MHz clock received optically by a PIN diode. We have successfully
implemented both ASICs in 0.25 micron CMOS technology using enclosed layout
transistors and guard rings for increased radiation hardness. We present
results of the performance of these chips, including irradiation with 24 GeV
protons up to 61 Mrad (2.3 x 10e15 p/cm^2).Comment: 17 pages, 23 figures, submitted to NIM Added references. Added figure
15. Moved sec. IV to sec. I
Semileptonic Branching Fraction of Charged and Neutral B Mesons
An examination of leptons in events tagged by reconstructed
decays yields semileptonic branching fractions of for charged and for neutral mesons.
This is the first measurement for charged . Assuming equality of the charged
and neutral semileptonic widths, the ratio is
equivalent to the ratio of lifetimes. A postscript version is available through
World-Wide-Web in http://w4.lns.cornell.edu/public/CLNS/1994Comment: 9 pages (in REVTEX format) Preprint CLNS94-1286, CLEO 94-1
Detection of Molecular Paths Associated with Insulitis and Type 1 Diabetes in Non-Obese Diabetic Mouse
Recent clinical evidence suggests important role of lipid and amino acid metabolism in early pre-autoimmune stages of type 1 diabetes pathogenesis. We study the molecular paths associated with the incidence of insulitis and type 1 diabetes in the Non-Obese Diabetic (NOD) mouse model using available gene expression data from the pancreatic tissue from young pre-diabetic mice. We apply a graph-theoretic approach by using a modified color coding algorithm to detect optimal molecular paths associated with specific phenotypes in an integrated biological network encompassing heterogeneous interaction data types. In agreement with our recent clinical findings, we identified a path downregulated in early insulitis involving dihydroxyacetone phosphate acyltransferase (DHAPAT), a key regulator of ether phospholipid synthesis. The pathway involving serine/threonine-protein phosphatase (PP2A), an upstream regulator of lipid metabolism and insulin secretion, was found upregulated in early insulitis. Our findings provide further evidence for an important role of lipid metabolism in early stages of type 1 diabetes pathogenesis, as well as suggest that such dysregulation of lipids and related increased oxidative stress can be tracked to beta cells
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