The CDF Silicon Vertex Trigger Ashmanskas, Bill; Barchiesi, A.; Bardi, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Collider Detector at Fermilab (CDF) experiment's Silicon Vertex Trigger (SVT) is a system of 150 custom 9U VME boards that reconstructs axial tracks in the CDF silicon strip detector in a
15
μs
...pipeline. SVT's
35
μm
impact parameter resolution enables CDF's Level 2 trigger to distinguish primary and secondary particles, and hence to collect large samples of hadronic bottom and charm decays. We review some of SVT's key design features. Speed is achieved with custom VLSI pattern recognition, linearized track fitting, pipelining, and parallel processing. Testing and reliability are aided by built-in logic state analysis and test-data sourcing at each board's input and output, a common interboard data link, and a universal “Merger” board for data fan-in/fan-out. Speed and adaptability are enhanced by use of modern FPGAs.
Titanium alloy, Ti6Al4V, is widely used in dental and orthopedic implants. Despite its excellent biocompatibility, Ti6Al4V releases toxic Al and V ions into the surrounding tissue after implantation. ...In addition, the elastic modulus of Ti6Al4V (∼110
GPa) is significantly higher than that of bone (10–40
GPa), leading to a modulus mismatch and consequently implant loosening and deosteointegration. Zeolite coatings are proposed to prevent the release of the toxic ions into human tissue and enhance osteointegration by matching the mechanical properties of bone. Zeolite MFI coatings are successfully synthesized on commercially pure titanium and Ti6Al4V for the first time. The coating shows excellent adhesion by incorporating titanium from the substrate within the zeolite framework. Higher corrosion resistance than the bare titanium alloy is observed in 0.856
M NaCl solution at pHs of 7.0 and 1.0. Zeolite coatings eliminate the release of cytotoxic Al and V ions over a 7
day period. Pluripotent mouse embryonic stem cells show higher adhesion and cell proliferation on the three-dimensional zeolite microstructure surface compared with a two-dimensional glass surface, indicating that the zeolite coatings are highly biocompatible.
We explored the use of carbon nanotubes (CNTs) as suitable scaffold materials for osteoblast proliferation and bone formation. With the aim of controlling cell growth, osteosarcoma ROS 17/2.8 cells ...were cultured on chemically modified single-walled (SW) and multiwalled (MW) CNTs. CNTs carrying neutral electric charge sustained the highest cell growth and production of plate-shaped crystals. There was a dramatic change in cell morphology in osteoblasts cultured on MWNTs, which correlated with changes in plasma membrane functions.
A Time-of-Flight detector in CDF-II Acosta, D.; Ahn, M.; Anikeev, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
1
Journal Article
Recenzirano
A Time-of-Flight (TOF) detector, based on plastic scintillators and fine-mesh photomultipliers, has been added to the Collider Detector at Fermilab (CDF)-II experiment at the Tevatron
p
p
̄
collider. ...The primary physics motivation is to provide charged kaon identification to improve neutral B meson flavor determination. Besides that, the TOF detector found application in the CDF trigger system in implementation of highly ionizing particle, high multiplicity and cosmic rays triggers.
The properties of the nicotinic acetylcholine receptor (AChR) are modulated by its lipid microenvironment. Studies of such modulation are hampered by the cell's homeostatic mechanisms that impede ...sustained modification of membrane lipid composition. We have devised a novel strategy to circumvent this problem and study the effect of changes in plasma membrane lipid composition on the functional properties of AChR. This approach is based on the stable transfection of AChR subunit cDNAs into cells defective in a specific lipid metabolic pathway. In the present work we illustrate this new strategy with the successful transfection of a temperature‐sensitive Chinese hamster ovary (CHO) cell line, SPB‐1, with the genes corresponding to the four adult mouse AChR subunits. The new clone, SPB‐1/SPH, carries a mutation of the gene coding for serine palmitoyl transferase, the enzyme that catalyses the first step in sphingomyelin (Sph) biosynthesis. This defect causes a decrease of Sph de novo synthesis at non‐permissive temperatures. The IC50 for inhibition of α‐BTX binding with the agonist carbamoylcholine exhibited values of 3.6 and 2.7 μm in the wild‐type and Sph‐deficient cell lines, respectively. The corresponding IC50 values for the competitive antagonist d‐tubocurarine (d‐TC) were 2.8 and 3.4 μm, respectively. No differences in single‐channel properties were observed between wild‐type and mutant cell lines grown at the non‐permissive, lipid defect‐expressing temperature using the patch‐clamp technique. Both cells exhibited two open times with mean values of 0.35 ± 0.05 and 1.78 ± 0.2 ms at 12 °C. Taken together, these results suggest that the AChR is expressed as the complete heteroligomer. However, only 10–20% of the total AChR synthesized reached the surface membrane in the mutant cell line and exhibited a higher metabolic turnover, with a half‐life about 50% shorter than the wild‐type cells. When control CHO‐K1/A5 cells were treated with fumonisin B1, an inhibitor of sphingosine (sphinganine) N‐acetyltransferase (ceramide synthase), a 45.5% decrease in cell surface AChR expression was observed. The results suggest that sphingomyelin deficiency conditions AChR targeting to the plasma membrane.
In the absence of mechanical stimulation, brief exposure of osteoblasts to 1 alpha ,25(OH) sub(2) vitamin D sub(3) (1,25D) triggers plasma membrane electrical responses that couple to exocytosis. ...Here we describe for the first time 1,25D induction of exocytotic ATP release in static ROS 17/2.8 and SAOS-2 cells and primary calvarial osteoblasts expressing a vitamin D receptor (VDR). We found that 10 nM 1,25D optimally induced 45 plus or minus 1% and 40 plus or minus 1% of partial and complete exocytotic events, respectively, from a 1,25D-sensitive pool of ATP-containing secretory vesicles within 60 s. We measured a dose-dependent 1,25D induction of ATP secretion, with maximal response of similar to 6.2-fold (16.93 plus or minus 1.82 nM for SAOS-2) and 3.1-fold (18.89 plus or minus 1.39 nM for ROS 17/2.8) obtained with 10 nM 1,25D compared with basal ATP levels (2.75 plus or minus 0.39 nM, SAOS-2; 6.09 plus or minus 0.58 nM, ROS 17/2.8 cells). The natural metabolite 25(OH) vitamin D sub(3) (25D, 10 nM) induced a significant 3.6-fold increase of ATP release in ROS 17/2.8 cells, but there was no induction with the antagonist 1 beta ,25(OH) sub(2)vitamin D sub(3) (1 beta ,25D, 10 nM) or the steroid 17 beta -estradiol (10 nM). 1,25D-induced ATP secretion was abolished when cells were preincubated with inhibitors of vesicular exocytosis. siRNA VDR silencing prevented 1,25D stimulation of ATP exocytosis in ROS 17/2.8 and SAOS-2 cells. Similarly, 1,25D failed to stimulate ATP exocytosis in primary osteoblasts from a VDR knockout mouse. ATP secretion coupled to 1,25D induction of cytosolic calcium and chloride channel potentiation. Rapid 1,25D stimulation of ATP secretion involving nontranscriptional VDR functions in osteoblasts may help explain 1,25D bone anabolic properties.
We propose precise and fast-track reconstruction at hadron collider experiments, for use in online trigger decisions. We describe the features of fast-track (FTK), a highly parallel processor ...dedicated to the efficient execution of a fast-tracking algorithm. The hardware-dedicated structure optimizes speed and size; these parameters are evaluated for the ATLAS experiment. We discuss some applications of high-quality tracks available to the trigger logic at an early stage, by using the LHC environment as a benchmark. The most interesting application is online selection of b-quarks down to very low transverse momentum, providing interesting hadronic samples: examples are Z/sup 0/spl rarr//bb~, potentially useful for jet calibration, and multi-b final states for supersymmetric Higgs searches. The paper is generated from outside the ATLAS experiment and has not been discussed by the ATLAS collaboration.
Osteoblast apoptosis plays a crucial role in bone remodeling. Physiological doses of 1 alpha ,25(OH) sub(2)-vitamin D sub(3) (1,25D) protect osteoblasts against apoptosis by means of mechanisms only ...partially understood. We studied activation of an Akt survival cascade downstream of 1,25D nongenomic stimulation of phosphatidylinositide-3'-kinase (PI3K) in osteoblastic cells. We measured a dose- and time-dependent 1,25D induction of Akt phosphorylation (p-Akt) in cultured osteoblastic cells. Maximal response was achieved with 10 nM 1,25D after 5 min. We found that staurosporine (STSP)-induced apoptosis was significantly reduced in 1,25D-pretreated osteoblasts. 1,25D prosurvival effects were abolished when cells were preincubated with inhibitors of PI3K activation. By means of siRNA silencing, we proved that 1,25D induction of p-Akt requires a classic vitamin D receptor (VDR) in osteoblasts. Furthermore, non-osteoblastic CV-1 cells transfected with an enhanced green fluorescent protein (EGFP)-VDR construct responded to 1,25D treatment with a rapid p-Akt response associated with increased cell survival not detected in native, nontransfected cells. We measured increased levels of p-Akt substrates p-Bad and p-FKHR and significantly reduced activity of caspases 8 and 3/7 after 1,25D treatment. In addition, 1,25D-induced protection against apoptosis was abolished when osteoblasts were preincubated with pertussis toxin. We conclude that anti-apoptotic effects of 1,25D in osteoblasts occur through nongenomic activation of a VDR/PI3K/Akt survival pathway that includes phosphorylation of multiple p-Akt substrates and reduction of caspase activities.
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