The STAR Time Projection Chamber (TPC) is used to record the collisions at the Relativistic Heavy Ion Collider. The TPC is the central element in a suite of detectors that surrounds the interaction ...vertex. The TPC provides complete coverage around the beam-line, and provides complete tracking for charged particles within ±1.8 units of pseudo-rapidity of the center-of-mass frame. Charged particles with momenta greater than
100
MeV/c
are recorded. Multiplicities in excess of 3000 tracks per event are routinely reconstructed in the software. The TPC measures
4
m
in diameter by
4.2
m
long, making it the largest TPC in the world.
LIGHT is a member of the TNF cytokine superfamily that signals through the lymphotoxin (LT)beta receptor and the herpesvirus entry mediator. LIGHT may function as a costimulatory factor for the ...activation of lymphoid cells and as a deterrent to infection by herpesvirus, which may provide significant selective pressure shaping the evolution of LIGHT. Here, we define the molecular genetics of the human LIGHT locus, revealing its close linkage to the TNF superfamily members CD27 ligand and 4-1BB ligand, and the third complement protein (C3), which positions LIGHT within the MHC paralog on chromosome 19p13.3. An alternately spliced isoform of LIGHT mRNA that encodes a transmembrane-deleted form is detected in activated T cells and gives rise to a nonglycosylated protein that resides in the cytosol. Furthermore, membrane LIGHT is shed from the cell surface of human 293 T cells. These studies reveal new mechanisms involved in regulating the physical forms and cellular compartmentalization of LIGHT that may contribute to the regulation and biological function of this cytokine.
On Selecting Psychology Graduate Students Edwards, Wayne R; Schleicher, Deidra J
Journal of educational psychology,
09/2004, Letnik:
96, Številka:
3
Journal Article
Recenzirano
This study provides initial evidence for the criterion-related validity of tacit knowledge (TK) as an alternative measure for selecting psychology graduate students and adds insight to the construct ...of TK by evaluating its factor structure, assessing convergent relationships with other variables, and exploring alternative reasons for why TK predicts performance. TK provided incremental validity beyond GRE scores, undergraduate GPA, and 7 personality dimensions in predicting graduate school performance. Moreover, TK scores computed from experts at different universities yielded nearly identical criterion-related validity coefficients, thus strengthening the generalizability of the predictor. Although the results of the present study demonstrate convergent relationships between TK and conceptually related variables, factor analyses conducted on the TK measure did not support the subdimensions proposed by the authors of the scale. Limitations of the present study, issues involving revision of the TK measure, and recommendations for future research are discussed.
The neutron economy and online refueling capability of heavy water moderated reactors enable them to use many different fuel types, such as low enriched uranium, plutonium mixed with uranium, or ...plutonium and/or U mixed with thorium, in addition to their traditional natural uranium fuel. However, the toxicity and radiological protection methods for fuels other than natural uranium are not well established. A previous paper by the current authors compared the composition and toxicity of irradiated natural uranium to that of three potential advanced heavy water fuels not containing plutonium, and this work uses the same method to compare irradiated natural uranium to three other fuels that do contain plutonium in their initial composition. All three of the new fuels are assumed to incorporate plutonium isotopes characteristic of those that would be recovered from light water reactor fuel via reprocessing. The first fuel investigated is a homogeneous thorium-plutonium fuel designed for a once-through fuel cycle without reprocessing. The second fuel is a heterogeneous thorium-plutonium-U bundle, with graded enrichments of U in different parts of a single fuel assembly. This fuel is assumed to be part of a recycling scenario in which U from previously irradiated fuel is recovered. The third fuel is one in which plutonium and Am are mixed with natural uranium. Each of these fuels, because of the presence of plutonium in the initial composition, is determined to be considerably more radiotoxic than is standard natural uranium. Canadian nuclear safety regulations require that techniques be available for the measurement of 1 mSv of committed effective dose after exposure to irradiated fuel. For natural uranium fuel, the isotope Pu is a significant contributor to the committed effective dose after exposure, and thermal ionization mass spectrometry is sensitive enough that the amount of Pu excreted in urine is sufficient to estimate internal doses, from all isotopes, as low as 1 mSv. In addition, if this method is extended so that Pu is also measured, then the combined amount of Pu and Pu is sufficiently high in the thorium-plutonium fuel that a committed effective dose of 1 mSv would be measurable. However, the fraction of Pu and Pu in the other two fuels is sufficiently low that a 1 mSv dose would remain below the detection limit using this technique. Thus new methods, such as fecal measurements of Pu (or other alpha emitters), will be required to measure exposure to these new fuels.
An economic analysis is presented of a proposed synergy between two nuclear utilities, Utility L that owns light water reactors (LWR) and Utility H that owns heavy water moderated reactors (HWR). ...Americium is partitioned from LWR spent fuel produced by Utility L and then transmuted in HWRs operated by Utility H. Additionally, reprocessed uranium (RU) from spent LWR fuel is used as fuel for the HWRs to transmute the americium. The analysis is based on the estimated value of RU to Utility L if it is re-enriched using centrifuges and used as LWR fuel, and the estimated cost to Utility L of partitioning americium from spent LWR fuel. In order for this scenario to be economically acceptable to Utility L, the averted disposal cost due to partitioning americium from LWR spent fuel most likely must exceed $230/kg heavy metals in spent nuclear fuel. A sensitivity analysis shows that the cost of partitioning americium from spent LWR fuel has the greatest effect on this value, followed by the cost of natural uranium. During steady state operations, a single HWR should be able to transmute all of the Am-241 from approximately five LWRs using RU from just those reactors as fuel.
•Americium from spent LWR fuel can be burned in HWRs fueled with RU.•We analyze the economics for a utility with LWRs to burn Am and RU in HWRs.•The averted disposal cost must exceed $200/kg spent fuel for this to be beneficial.•This result is most sensitive to the cost of separating Am from spent LWR fuel.•A rise in the cost of NU would worsen the economic acceptability of this scheme.
Superficially similar cleavable targeting signals specify whether lumenal proteins are transported across the thylakoid membrane by a Sec- or ΔpH-dependent pathway. A twin-arginine motif is essential ...but not sufficient to direct ΔpH-dependent targeting; here we show that a second determinant is located in the hydrophobic region. A highly hydrophobic amino acid is found either two or three residues C-terminal to the twin-arginine in all known transfer peptides for the ΔpH-dependent system, and substitution of this residue in the 23-kDa (23K) peptide markedly inhibits translocation. Further, whereas the insertion of twin-arginine in a Sec-dependent precursor does not permit efficient ΔpH-dependent targeting, the simultaneous presence of a leucine at the +3 position (relative to the RR) enables the peptide to function as efficiently as an authentic transfer peptide. RRNVL, RRAAL and RRALA within a Sec targeting signal all support efficient ΔpH-dependent targeting, RRNVA is less effective and RRNAA/RRNAG are totally ineffective. We conclude that the core signal for this pathway is a twin-arginine together with an adjacent hydrophobic determinant.
Integration and conventional systems at STAR Matis, H.S.; Brown, R.L.; Christie, W. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2003, Letnik:
499, Številka:
2
Journal Article
Recenzirano
Odprti dostop
At the beginning of the design and construction of the STAR detector, the collaboration assigned a team of physicists and engineers the responsibility of coordinating the construction of the ...detector. This group managed the general space assignments for each sub-system and coordinated the assembly and planning for the detector. Furthermore, as this group was the only STAR group with the responsibility of looking at the system as a whole, the collaboration assigned it several tasks that spanned the different sub-detectors. These items included grounding, rack layout, cable distribution, electrical, power and water, and safety systems. This paper describes these systems and their performance.
We studied nest parasitism of greater prairie-chickens (Tympanuchus cupido pinnatus) by ring-necked pheasants (Phasianus colchicus) as a possible contributing factor in the decline of an isolated ...population of prairie-chickens in Jasper County, Illinois. Both species nested in small, scattered grasslands maintained on prairie-chicken sanctuaries. Incidence of parasitic laying by pheasant hens in prairie-chicken nests increased from 2 to 43% between 1970 and 1983 and remained high through 1987. Nest success (≥1 host-egg hatching) did not differ (P = 0.33) between 60 unmanaged parasitized nests (43%) and 602 unparasitized nests (51%). However, success of 14 parasitized prairie-chicken nests managed by removal of pheasant eggs (86%) was greater (P = 0.02) than for 24 unmanaged parasitized nests (46%) during 1983 and 1985-87. Hatchability of fertile prairie-chicken eggs was less (P < 0.01) in parasitized nests (77%, conservatively) than in unparasitized nests (94%), because of earlier hatching of pheasant eggs, increased embryo mortality of prairie-chickens, or increased nest abandonment. Large clutches of prairie-chicken eggs typical of early nests were more likely (P < 0.001) parasitized than small clutches laid later. Factors correlated with rate of nest parasitism included numbers of pheasant cocks (P = 0.01) and numbers of pheasant nests (P < 0.001) found each year. Although pheasant control apparently eliminated nest parasitism during 1988-94, prairie-chicken numbers continued to decline. Without management intervention to control pheasants on sanctuaries, the survival of this isolated, remnant flock of prairie-chickens may be in greater jeopardy.
The patient required bilateral salpingoophorectomy for pain caused by the late effects of pelvic infection. Division of adhesions was followed by torrential bleeding from the gluteal tributaries of ...the right internal iliac vein aggravated by the partial retraction of those veins into the subgluteal region. Measures to control the bleeding and the late complications are described.
Complexity measures for rule-based programs O'Neal, M.B.; Edwards, W.R.
IEEE transactions on knowledge and data engineering,
10/1994, Letnik:
6, Številka:
5
Journal Article
Recenzirano
Software complexity measures are quantitative estimates of the amount of effort required by a programmer to comprehend a piece of code. Many measures have been designed for standard procedural ...languages, but little work has been done to apply software complexity concepts to nontraditional programming paradigms. This paper presents a collection of software complexity measures that were specifically designed to quantify the conceptual complexity of rule-based programs. These measures are divided into two classes: bulk measures, which estimate complexity by examining aspects of program size, and rule measures, which gauge complexity based on the ways in which program rules interact with data and other rules. A pilot study was conducted to assess the effectiveness of these measures. Several measures were found to correlate well with the study participants' ratings of program difficulty and the time required by them to answer questions that required comprehension of program elements. The physical order of program rules was also shown to affect comprehension. The authors conclude that the development of software complexity measures for particular programming paradigms may lead to better tools for managing program development and predicting maintenance effort in nontraditional programming environments.< >
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