4,459 research outputs found

    Matching small β\beta functions using centroid jitter and two beam position monitors

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    Matching to small beta functions is required to preserve emittance in plasma accelerators. The plasma wake provides strong focusing fields, which typically require beta functions on the mm-scale, comparable to those found in the final focusing of a linear collider. Such beams can be time consuming to experimentally produce and diagnose. We present a simple, fast, and noninvasive method to measure Twiss parameters in a linac using two beam position monitors only, relying on the similarity of the beam phase space and the jitter phase space. By benchmarking against conventional quadrupole scans, the viability of this technique was experimentally demonstrated at the FLASHForward plasma-accelerator facility.Comment: 8 pages, 7 figure

    Is antenatal group B streptococcal carriage a predictor of adverse obstetric outcome?

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    OBJECTIVES: While early-onset neonatal GBS sepsis is positively associated with premature birth and prolonged rupture of membranes, there is debate in the literature as to whether maternal GBS colonization is a predictor of adverse obstetric outcome. This is a critical issue to resolve for appropriate management (expectant vs. interventional management) of the patient presenting with premature rupture of membranes, who has no overt signs of sepsis, but who is colonized with GBS. METHODS: Since 1981 it has been hospital policy to screen all public patients antenatally for genital carriage of GBS by collection of a low vaginal swab at 28-32 weeks. All patients colonized with GBS antenatally are given penicillin as intrapartum chemoprophylaxis. Review of all GBS-colonized antenatal patients for a 12-month period (580 of 4,495 patients) and a randomized (every fourth consecutive antenatal patient) number of noncolonized patients (958) was made. Lower vaginal GBS colonization and other risk factors for preterm delivery were assessed using univariate and multivariate generalized linear modeling. RESULTS: In the study group, the maternal GBS colonization rate was 12.9%. When cofounding variables were controlled in a multivariate analysis, the association between antepartum GBS colonization and preterm labor and preterm rupture of membranes was not significant. CONCLUSION: Maternal antenatal carriage of GBS does not predict preterm labor. Therefore it is appropriate that expectant management occur for a GBS-colonized woman who ruptures her membranes, is not in labor, and has no evidence of sepsis

    Ultrasonic studies of the magnetic phase transition in MnSi

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    Measurements of the sound velocities in a single crystal of MnSi were performed in the temperature range 4-150 K. Elastic constants, controlling propagation of longitudinal waves reveal significant softening at a temperature of about 29.6 K and small discontinuities at ∼\sim28.8 K, which corresponds to the magnetic phase transition in MnSi. In contrast the shear elastic moduli do not show any softening at all, reacting only to the small volume deformation caused by the magneto-volume effect. The current ultrasonic study exposes an important fact that the magnetic phase transition in MnSi, occurring at 28.8 K, is just a minor feature of the global transformation marked by the rounded maxima or minima of heat capacity, thermal expansion coefficient, sound velocities and absorption, and the temperature derivative of resistivity.Comment: 4 pages, 4 figure

    General massive one-loop off-shell three-point functions

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    In this work we compute the most general massive one-loop off-shell three-point vertex in D-dimensions, where the masses, external momenta, and exponents of propagators are arbitrary. This follows our previous paper in which we have calculated several new hypergeometric series representations for massless and massive (with equal masses) scalar one-loop three-point functions, in the negative dimensional approach.Comment: 16 pages, 2 figures, 4 table

    HPV vaccination of immunocompromised hosts.

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    It is well-established that immunocompromised people are at increased risk of HPV-related disease compared with those who are immunocompetent. Prophylactic HPV sub-unit vaccines are safe and immunogenic in immunocompromised people and it is strongly recommended that vaccination occur according to national guidelines. When delivered to immunocompromised populations, HPV vaccines should be given as a 3-dose regimen

    Point of care blood tests during home visits by out-of-hours primary care clinicians; a mixed methods evaluation of a service improvement

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    Objectives We aimed to evaluate test usage and patient and clinician experience following the introduction of point-of-care (POC) blood tests into a primary care out-of-hours service. Design A mixed methods service evaluation comprising quantitative records of the clinical contexts of tests taken and qualitative interviews with clinicians. Research permissions and governance were obtained for patient interviews. Setting Out-of-hours primary care. Participants All patients requiring home visits from the service during the implementation period. Interventions The i-STAT POC blood test platform was introduced to two bases providing home visits for a period of 8 months. Venous blood samples were used and two cartridges were available. The CHEM8 cartridge measures sodium, potassium, chloride, total carbon dioxide (TCO2), anion gap, ionised calcium, glucose, urea, creatinine, haematocrit and haemoglobin. The CG4 cartridge measures lactate, pH, PaO2 and PCO2, TCO2, bicarbonate, base excess and oxygen saturation. Primary and secondary outcome measures The proportion of home visits where tests were taken, the clinical contexts of those tests, the extent to which clinicians felt the tests had influenced their decisions, time taken to perform the test and problems encountered. Clinician and patient experiences of using POC tests. Results i-STAT POC tests were infrequently used, with successful tests taken at just 47 contacts over 8 months of implementation. The patients interviewed felt that testing had been beneficial for their care. Clinician interviews suggested barriers to POC tests, including practical challenges, concerns about time, doubt over whether they would improve clinical decision making and concern about increased medicolegal risk. Suggestions for improving adoption included sharing learning, adopting a whole team approach and developing protocols for usage. Conclusions POC tests were not successfully adopted by an out-of-hours home visiting service in Oxfordshire. While some clinicians felt they could not add value, in other cases they resulted in improved patient experience. Adoption could be promoted by improving technical, team and education factors
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