Superconducting Surface Impedance under Radiofrequency Field

Based on BCS theory with moving Cooper pairs, the electron states distribution at 0K and the probability of electron occupation with finite temperature have been derived and applied to anomalous skin effect theory to obtain the surface impedance of a superconductor under radiofrequency (RF) field. We present the numerical results for Nb and compare these with representative RF field-dependent effective surface resistance measurements from a 1.5 GHz resonant structure

Operating Experience with Superconducting Cavities at Jefferson Lab

The CEBAF recirculating superconducting electron linac at Jefferson Lab is now in full operation supporting nuclear physics experiments in three target halls at up to 4.4 GeV. The 330 SRF cavities, operating at 2.0 K, continue to perform well above design specifications, and have accumulated over 8,000,000 operating cavity hours. The authors have to date no evidence of degradation of cavity performance. The SRF cavities have demonstrated excellent reliability. The one klystron per cavity design provides CEBAF with flexibility and redundancy for normal operations. Several techniques have been developed for establishing optimum operating conditions for the 330 independent systems. Operation of the cavities and control systems at the full design current of 1 mA has recently been achieved. The principal constraints on usable gradient for low current operations are (1) discharge at the cold ceramic rf window induced by electron field emission in cavities, (2) tuner controls, and (3) stability of the waveguide vacuum in the region between the warm and cold windows. Several cryomodules have been improved by application of rf helium processing while installed on the beamline

Prostate Cancer and PSA Testing: Implications of Provider-Patient Communication and Shared- Decision Making on National Screening Recommendations

The national recommendations for use of the prostate specific antigen (PSA) test for prostate cancer screening have been modified over the years as scientific evidence emerged. Current screening recommendations discourage widespread PSA screening for men at low to average risk, but provide specific guidelines for shared-decision making between men and their health providers about the benefits and risks of PSA testing. This study was an examination of relationships between men’s assessment of the quality of their care and communication with their health providers, the extent to which providers engage men in recommended discussions about PSA testing, and factors associated with shared-decision making and PSA testing. Secondary data from the U.S. Health Information National Trends Survey 4, Cycle 2 that included men with no history of prostate cancer and in the recommended age ranges for prostate cancer screening were analyzed (N=777). Non-Hispanic white men rated their quality of care higher than men of other races (c2 (49, n=635) = 7.23, p = 0.0098), whereas Hispanic men gave the lowest ratings compared to other men (c2 (49, n=635) = 5.42, p = 0.024). Previous PSA testing was reported by 64% of the men, 56% of whom stated that they discussed screening with their provider and 80% reported that they were asked if they wanted to have the test done. However, only 21% - 39% reported having ever discussed the pros and cons of PSA testing. Discussing PSA testing with a provider was the strongest predictor of obtaining the test (OR=69.5, CI = 23.6 – 204.6) but the effect was significantly modified when providers and patients engaged in the shared-decision making process (OR = 47.42, CI = 14.91 – 150.74). Age, education level and perceived quality of care were consistent, positive predictors of PSA testing. These results indicate there is a gap in provider-patient discussions about PSA screening and suggest that health providers may not be following the recommended guidelines for the content of the discussions needed to facilitate shared-decision making. Effective provider-based interventions to increase shared-decision-making about PSA testing are needed if the national objectives for prostate cancer screening are to be met

Investigating the evolution of apoptosis in malaria parasites: the importance of ecology

Apoptosis is a precisely regulated process of cell death which occurs widely in multicellular organisms and is essential for normal development and immune defences. In recent years, interest has grown in the occurrence of apoptosis in unicellular organisms. In particular, as apoptosis has been reported in a wide range of species, including protozoan malaria parasites and trypanosomes, it may provide a novel target for intervention. However, it is important to understand when and why parasites employ an apoptosis strategy before the likely long-and short-term success of such an intervention can be evaluated. The occurrence of apoptosis in unicellular parasites provides a challenge for evolutionary theory to explain as organisms are expected to have evolved to maximise their own proliferation, not death. One possible explanation is that protozoan parasites undergo apoptosis in order to gain a group benefit from controlling their density as this prevents premature vector mortality. However, experimental manipulations to examine the ultimate causes behind apoptosis in parasites are lacking. In this review, we focus on malaria parasites to outline how an evolutionary framework can help make predictions about the ecological circumstances under which apoptosis could evolve. We then highlight the ecological considerations that should be taken into account when designing evolutionary experiments involving markers of cell death, and we call for collaboration between researchers in different fields to identify and develop appropriate markers in reference to parasite ecology and to resolve debates on terminology.Host-parasite interactio

A bioinformatics approach to the development of immunoassays for specified risk material in canned meat products

A bioinformatics approach to developing antibodies to specific proteins has been evaluated for the production of antibodies to heat-processed specified risk tissues from ruminants (brain and eye tissue). The approach involved the identification of proteins specific to ruminant tissues by interrogation of the annotation fields within the Swissprot database. These protein sequences were then interrogated for peptide sequences that were unique to the protein. Peptides were selected that met these criteria as close as possible and that were also theoretically resistant to either pepsin or trypsin. The selected peptides were synthesised and used as immunogens to raise monoclonal antibodies. Antibodies specific for the synthetic peptides were raised to half of the selected peptides. These antibodies have each been incorporated into a competitive enzyme-linked immunosorbent assay (ELISA) and shown to be able to detect the heat-processed parent protein after digestion with either pepsin or trypsin. One antibody, specific for alpha crystallin peptide (from bovine eye tissue), was able to detect the peptide in canned meat products spiked with 10% eye tissue. These results, although preliminary in nature, show that bioinformatics in conjunction with enzyme digestion can be used to develop ELISA for proteins in high-temperature processed foods and demonstrate that the approach is worth further stud

TEACHING MARKETING AND MANAGEMENT TO AN EXTENSION AUDIENCE IN AN INTER-DISCIPLINARY SETTING

This paper discusses how economists utilize an inter-disciplinary workshop to teach marketing and management concepts to beef cattle producers and beef industry advisors. Range and animal scientists along with economists teach concepts in the classroom and then demonstrate these concepts with hands-on field activities in an 8-day Ranch Practicum, spread over an 8-month period.Teaching/Communication/Extension/Profession,

Dynamical instabilities of Bose-Einstein condensates at the band-edge in one-dimensional optical lattices

We report on experiments that demonstrate dynamical instability in a Bose-Einstein condensate at the band-edge of a one-dimensional optical lattice. The instability manifests as rapid depletion of the condensate and conversion to a thermal cloud. We consider the collisional processes that can occur in such a system, and perform numerical modeling of the experiments using both a mean-field and beyond mean-field approach. We compare our numerical results to the experimental data, and find that the Gross-Pitaevskii equation is not able to describe this experiment. Our beyond mean-field approach, known as the truncated Wigner method, allows us to make quantitative predictions for the processes of parametric growth and thermalization that are observed in the laboratory, and we find good agreement with the experimental results.Comment: v2: Added several reference

A rapid bioluminescence assay for measuring ​myeloperoxidase activity in human plasma

Myeloperoxidase (MPO) is a circulating cardiovascular disease (CVD) biomarker used to estimate clinical risk and patient prognosis. Current enzyme-linked immunosorbent assays (ELISA) for MPO concentration are costly and time-intensive. Here we report a novel bioluminescence assay, designated MPO activity on a polymer surface (MAPS), for measuring MPO activity in human plasma samples using the bioluminescent substrate L-012. The method delivers a result in under an hour and is resistant to confounding effects from endogenous MPO inhibitors. In a pilot clinical study, we compared MAPS and two clinical ELISAs using 72 plasma samples from cardiac catheterization patients. Results from parallel MAPS and ELISAs were concordant within 2±11 μg l(−1) MPO with similar uncertainty and reproducibility. Results between parallel MAPS and ELISA were in better agreement than those between independent ELISAs. MAPS may provide an inexpensive and rapid assay for determining MPO activity in plasma samples from patients with CVD or potentially other immune and inflammatory disorders

Simulated holographic three-dimensional intensity shaping of evanescent-wave fields

The size of bright structures in traveling-wave light fields is limited by diffraction. This in turn limits a number of technologies, for example, optical trapping. One way to beat the diffraction limit is to use evanescent waves instead of traveling waves. Here we apply a holographic algorithm, direct search, to the shaping of complex evanescent-wave fields. We simulate three-dimensional intensity shaping of evanescent-wave fields using this approach, and we investigate some of its limitations. (c) 2008 Optical Society of America.</p