Two, three, or four heads are better than one: Modification of college performance by peer monitoring.

Two studies with a total of 621 undergraduates assessed the effects of a peer-monitoring procedure on student performance in a college course. In the 1st study, Ss were assigned a learning partner and informed that their final grade would be determined by the average of their individual performances. A class with traditional grading served as the control group. In the 2nd study, grade averaging was again employed for experimental peer-monitoring groups of 2, 3, or 4 Ss. Here, experimental and control Ss were students in the same course. Both studies indicated the superiority of the peer-monitoring method over the typical individual performance contingency. Peer-monitoring procedures can be implemented in college courses with no added expense and minimal increases in bookkeeping. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The accelerator for the Los Alamos free-electron laser--IV

The design parameters and performance of the accelerator used with the Los Alamos free-electron laser are described. Special emphasis is placed on those features of the accelerator that affect emittance, energy spread, and micropulse temporal shape.     

Recombinant PSP94 (prostate secretory protein of 94 amino acids) demonstrates similar linear epitope structure as natural PSP94 protein

PSP94 has the potential to be a useful diagnostic marker and therapeutic agent in prostate cancer. Recently, different immunoassay systems for quantitative analysis of PSP94 in clinical samples have been developed, but the epitope structure of PSP94 protein has not been elucidated. In this study, we report an Escherichia coli expression system for recombinant GST-PSP94 fusion protein. GST-PSP94 contains antigenic determinants similar to natural PSP94 protein (determined both by Western blotting experiments and by ELISA) and can be used to study the structure of natural PSP94 antigen. Since GST-PSP94 was expressed in E. coli and purification involved a denaturing process, we propose that the epitope structure of PSP94 is linear and largely dependent on the primary amino acid sequence, rather than conformational structure. This hypothesis was supported by reciprocal competition in ELISA among natural, GST-PSP94 fusion protein, and purified recombinant PSP94 protein. The results demonstrate that the various forms of PSP94 can compete with each other in binding to rabbit PSP94 polyclonal antibody, although the natural PSP94 has a slightly higher affinity. When natural and recombinant PSP94 protein were denatured in vitro with urea and alkali, no effect on the binding to antibody was found. The epitope activity of natural PSP94 was also shown to be resistant to the treatment of detergent and reducing agent. The location of one of the linear epitopes recognized by the PSP94 antibody was determined to be in the N-terminus by using two synthetic peptides representing N- and C-terminal sequences. Competitive ELISA between the N-terminal peptide and PSP94 protein indicate that both natural and GST-PSP94 have similar immunoactive N-termini.     

Understanding the Interdependencies Between Composition,Microstructure, and Continuum Variables and Their Influence on the Fracture Toughness of α/β-Processed Ti-6Al-4V

The fracture toughness of a material depends upon the material’s composition and microstructure, as well as other material properties operating at the continuum level. The interrelationships between these variables are complex, and thus difficult to interpret, especially in multi-component, multi-phase ductile engineering alloys such as α/β-processed Ti-6Al-4V (nominal composition, wt pct). Neural networks have been used to elucidate how variables such as composition and microstructure influence the fracture toughness directly (i.e., via a crack initiation or propagation mechanism)—and independent of the influence of the same variables influence on the yield strength and plasticity of the material. The variables included in the models and analysis include (i) alloy composition, specifically, Al, V, O, and Fe; (ii) materials microstructure, including phase fractions and average sizes of key microstructural features; (iii) the yield strength and reduction in area obtained from uniaxial tensile tests; and (iv) an assessment of the degree to which plane strain conditions were satisfied by including a factor related to the plane strain thickness. Once trained, virtual experiments have been conducted which permit the determination of each variable’s functional dependency on the resulting fracture toughness. Given that the database includes both K _{1 C} and K _Q values, as well as the in-plane component of the stress state of the crack tip, it is possible to quantitatively assess the effect of sample thickness on K _Q and the degree to which the K _Q and K _{1 C} values may vary. These interpretations drawn by comparing multiple neural networks have a significant impact on the general understanding of how the microstructure influences the fracture toughness in ductile materials, as well as an ability to predict the fracture toughness of α/β-processed Ti-6Al-4V.     

The influence of latitude on the concentration of vitamin D3 and 25-hydroxy-vitamin D3 in Australian red meat

There is little information on the vitamin D content of Australian red meat or on the possible influence of latitude on this content. To determine the content of vitamin D₃ and 25-hydroxy-vitamin D₃ (25OHD₃), lamb and beef were analysed from 34° S with LC–IT-MS. To investigate the possible influence of latitude on vitamin D in meat, the lean meat and fat from five cuts of beef were analysed from 17° S and 41° S. Lamb contained 0.10 μg vitamin D₃/100 g and 0.20 μg 25OHD₃/100 g lean meat, while beef contained 0.12 μg vitamin D₃ and 0.27 μg 25OHD₃/100 g (lean meat). Latitude had no effect on the vitamin D₃ (P = 0.21) or 25OHD₃ (P = 0.29) content of lean beef, but fat from cattle in the 17° S latitude group contained significantly higher (P < 0.01) concentrations of vitamin D₃ than fat from the 41° S group of cattle.     

Tracking petroleum refinery emission events using lanthanum and lanthanides as elemental markers for PM2.5

Fine particulate matter levels at four air sampling stations in the Houston, TX area are apportioned to quantify the impact of emissions from a local refinery during a reported emission event. Through quantification of lanthanum and lanthanides using a recently developed analytical technique, the impacts of emissions from fluidized-bed catalytic cracking (FCC) units are quantitatively tracked across the Houston region. The results show a significant (33-106-fold) increase in contributions of FCC emissions to PM2.5 compared with background levels associated with routine operation. This impact from industrial emissions to ambient air quality occurs simultaneously with a larger, regional haze episode that lead to elevated PM2.5 concentrations throughout the entire region. By focusing on detailed chemical analysis of unique maker metals (lanthanum and lanthanides), the impact of emissions from the FCC unit was tracked from the local refinery that reported the emission event to a site approximately 50 km downwind, illustrating the strength of the analytical method to isolate an important source during a regional haze episode not related to the emission event. While this source apportionment technique could separate contributions from FCC emissions, improved time-resolved sampling is proposed to more precisely quantify the impacts of transient emission events on ambient PM2.5.     

Rheumatoid synovial cells from intact joints. Morphology, growth, and polykaryocytosis

Synovial cell lines were isolated by instillation of trypsin or chymotrypsin into intact knee joints of patients with persistent rheumatoid effusions resistant to conventional therapy. Morphology and growth in the primary phase were compared with rheumatoid cells isolated from excised synovium and nonrheumatoid synovial cells obtained from intact joints of cadavers or amputated limbs. Cell populations from all sources included varying proportions of macrophage-like and fibroblast-like cells, with only 1-3% multinucleated cells. In medium supplemented with calf serum alone, rheumatoid cells from intact joints showed negligible changes in morphology. However, in the presence of nonrheumatoid, autologous rheumatoid or homologous rheumatoid serum a rapid increase occurred in size of the macrophage-like cells and numbers of polykaryocytes, including some giant syncytial cells. These effects were directly proportional to serum concentration and were identical in fresh or heat-inactivated serum. In most of these rheumatoid cell lines no multiplication occurred, regardless of serum type or concentration. In rheumatoid synovial cells from excised synovium, human serum induced both polykaryocytosis and rapid growth of fibroblasts. Nonrheumatoid synovial cells grew rapidly but few polykaryocytes developed, mostly with less than 6 nuclei. Evidence of viral infection in rheumatoid synovial cells was sought by electron microscopy after stimulation of polykaryocytosis by human serum. In one of the cultures many cells were found with intranuclear particles possessing characteristics of the adenovirus group.