528 research outputs found

    The effect of New Zealand blackcurrant supplementation on recovery from muscle damage induced by drop jumps

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    New Zealand blackcurrant (NZBC) is a rich source of anthocyanins, which improve blood flow and display anti-inflammatory and antioxidant properties that may improve recovery from exercise-induced muscle damage (EIMD). Limited evidence is available as to whether anthocyanin supplements can aid recovery in the days following muscle damaging exercise. The aim of this study was to examine if NZBC extract improves recovery following muscle damaging exercise. Following a double-blind, repeated crossover design, 12 recreationally active males (mean±SD: age 29±6 years, stature 1.80±0.07 m, body mass 78.0±10.7 kg, ÎŁ of 4 skinfolds 35.65± 12.30 mm, maximal voluntary isometric contraction (MVIC) baseline 497± 120 N) ingested either 2 x 300 mg·day−1 capsules with a NZBC extract (CurraNZℱ; each containing 105 mg anthocyanin) or a visually matched placebo (PLA) 7-days prior and 3-days after completing a 100-drop jump protocol (100-DJP). Measures of MVIC, electrically stimulated (ES) contractions, countermovement jumps (CMJ), perceived muscle soreness (visual analogue scale), serum interleukin-6 (IL-6) and prostaglandin-E2 (PGE2) were made pre- (baseline), immediately-, 24-, 48- and 72 h-post the 100-DJP. MVIC, ES, CMJ and muscle soreness variables were analysed using a mixed model ANOVA with significance set at p < 0.05. MVIC peak force was reduced immediately-post 100-DJP, compared to baseline (NZBC: 90±10; PLA: 93±11 %; P = 0.001, ηp2 = 0.320), but returned to baseline at 24 h with no difference between groups (P = 0.940). ES doublet peak force was reduced compared to baseline immediately- 24-, 48- and 72 h-post (P 0.05). In conclusion, the NZBC extract did not accelerate recovery of MVIC or ES doublet peak force, perceptions of muscle soreness or inflammation following muscle damaging exercise in recreationally active males and large inter-individual variation in responses were present

    On-sky tests of the CuReD and HWR fast wavefront reconstruction algorithms with CANARY

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    CuReD (Cumulative Reconstructor with domain Decomposition) and HWR (Hierarchical Wavefront Reconstructor) are novel wavefront reconstruction algorithms for the Shack–Hartmann wavefront sensor, used in the single-conjugate adaptive optics. For a high-order system they are much faster than the traditional matrix–vector-multiplication method. We have developed three methods for mapping the reconstructed phase into the deformable mirror actuator commands and have tested both reconstructors with the CANARY instrument. We find out that the CuReD reconstructor runs stably only if the feedback loop is operated as a leaky integrator, whereas HWR runs stably with the conventional integrator control. Using the CANARY telescope simulator we find that the Strehl ratio (SR) obtained with CuReD is slightly higher than that of the traditional least-squares estimator (LSE). We demonstrate that this is because the CuReD algorithm has a smoothing effect on the output wavefront. The SR of HWR is slightly lower than that of LSE. We have tested both reconstructors extensively on-sky. They perform well and CuReD achieves a similar SR as LSE. We compare the CANARY results with those from a computer simulation and find good agreement between the two

    Four methods for determining the composition of trace radioactive surface contamination of low-radioactivity metal

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    Four methods for determining the composition of low-level uranium- and thorium-chain surface contamination are presented. One method is the observation of Cherenkov light production in water. In two additional methods a position-sensitive proportional counter surrounding the surface is used to make both a measurement of the energy spectrum of alpha particle emissions and also coincidence measurements to derive the thorium-chain content based on the presence of short-lived isotopes in that decay chain. The fourth method is a radiochemical technique in which the surface is eluted with a weak acid, the eluate is concentrated, added to liquid scintillator and assayed by recording beta-alpha coincidences. These methods were used to characterize two `hotspots' on the outer surface of one of the He-3 proportional counters in the Neutral Current Detection array of the Sudbury Neutrino Observatory experiment. The methods have similar sensitivities, of order tens of ng, to both thorium- and uranium-chain contamination.Comment: 22 pages, 19 figure

    Covariant Field Equations, Gauge Fields and Conservation Laws from Yang-Mills Matrix Models

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    The effective geometry and the gravitational coupling of nonabelian gauge and scalar fields on generic NC branes in Yang-Mills matrix models is determined. Covariant field equations are derived from the basic matrix equations of motions, known as Yang-Mills algebra. Remarkably, the equations of motion for the Poisson structure and for the nonabelian gauge fields follow from a matrix Noether theorem, and are therefore protected from quantum corrections. This provides a transparent derivation and generalization of the effective action governing the SU(n) gauge fields obtained in [1], including the would-be topological term. In particular, the IKKT matrix model is capable of describing 4-dimensional NC space-times with a general effective metric. Metric deformations of flat Moyal-Weyl space are briefly discussed.Comment: 31 pages. V2: minor corrections, references adde

    Deformation of Super Yang-Mills Theories in R-R 3-form Background

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    We study deformation of N=2 and N=4 super Yang-Mills theories, which are obtained as the low-energy effective theories on the (fractional) D3-branes in the presence of constant Ramond-Ramond 3-form background. We calculate the Lagrangian at the second order in the deformation parameter from open string disk amplitudes. In N=4 case we find that all supersymmetries are broken for generic deformation parameter but part of supersymmetries are unbroken for special case. We also find that classical vacua admit fuzzy sphere configuration. In N=2 case we determine the deformed supersymmetries. We rewrite the deformed Lagrangians in terms of N=1 superspace, where the deformation is interpreted as that of coupling constants.Comment: v2: reference added, v3: published version in JHE

    Students with global experiences during medical school are more likely to work in settings that focus on the underserved: an observational study from a public U.S. institution

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    Background: Global health interest has grown among medical students over the past 20 years, and most medical schools offer global health opportunities. Studies suggest that completing global health electives during medical school may increase the likelihood of working with underserved populations in a clinical or research capacity. This study aimed to assess the association of global electives in medical school on subsequently working in global health and with underserved populations in the United States (U.S.), additionally considering students’ interests and experiences prior to medical school. We also examined whether respondents perceived benefits gained from global electives. Methods: We surveyed medical school graduates (classes of 2011-2015) from a large public medical school in the U.S. to describe current practice settings and previous global health experience. We evaluated work, volunteer, and educational experiences preceding medical school, socioeconomic status, race and ethnicity using American Medical College Application Service (AMCAS) data. We assessed the association between students’ backgrounds, completing global health electives in medical school and current work in global health or with underserved populations in the U.S. Results: In the 5 to 8 years post-graduation, 78% of 161 respondents reported work, research, or teaching with a focus on global or underserved U.S. populations. Completing a global health elective during medical school (p = 0.0002) or during residency (p = 0.06) were positively associated with currently working with underserved populations in the U.S. and pre-medical school experiences were marginally associated (p = 0.1). Adjusting for pre-medical school experiences, completing a global health elective during medical school was associated with a 22% greater prevalence of working with an underserved population. Perceived benefits from global electives included improved cultural awareness, language skills, public health and research skills, and ability to practice in technology-limited settings. Conclusion: Medical school graduates who participated in global electives as students were more likely than their peers to pursue careers with underserved populations, independent of experiences prior to medical school. We hypothesize that by offering global health experiences, medical schools can enhance the interests and skills of graduates that will make them more likely and better prepared to work with underserved populations in the U.S. and abroad

    Overcoming barriers to adolescent vaccination: perspectives from vaccine providers in North Carolina

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    To capture strategies for achieving high adolescent coverage of tetanus-diphtheria-acellular pertussis (Tdap), meningococcal conjugate (MenACWY), and human papillomavirus (HPV) vaccination, we surveyed employees of 20 North Carolina (N.C.) clinics that achieved adolescent vaccination coverage higher than the state average. One employee per clinic completed a surveysummarizing clinic practices regarding adolescent vaccination; perceived barriers and facilitators to Tdap/MenACWY/HPV vaccination; and the role of “champions” who made special efforts to promote adolescent vaccination. Common perceived barriers for all vaccinations were parental opposition and logistical barriers to receiving vaccination. For HPV vaccination, employees cited parental concerns about sexual behavior and injection site pain; no school vaccination requirement; and low-perceived benefit in boys. Most clinics (80%) implemented successful changes to increase adolescent vaccination: consistently offering vaccination, tracking vaccination status using existing data, providing appointment reminders, updating providers on vaccination recommendations, and expanding vaccination hours. Strategies to improve HPV vaccination included co-administration with Tdap and MenACWY, and providing reminders to complete the vaccination series. Vaccine champions strongly recommended vaccination to parents (55%) and educated parents on vaccination recommendations (36%). Clinics in N.C.and similar settings can implement these and other low-resource strategies to overcome adolescent vaccination barriers. Abbreviations: CDC=Centers for Disease Control and Prevention; EHR=Electronic health record; HPV=Human papillomavirus; Tdap=Tetanus-diphtheria-acellular pertussis vaccine; MenACWY=Meningococcal Conjugate Vaccine; NCIB=North Carolina Immunization Branch; NCIR=North Carolina Immunization Registry; ACIP=Advisory Committee on Immunization Practices

    Tall tales from de Sitter space II: Field theory dualities

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    We consider the evolution of massive scalar fields in (asymptotically) de Sitter spacetimes of arbitrary dimension. Through the proposed dS/CFT correspondence, our analysis points to the existence of new nonlocal dualities for the Euclidean conformal field theory. A massless conformally coupled scalar field provides an example where the analysis is easily explicitly extended to 'tall' background spacetimes.Comment: 31 pages, 2 figure

    World-sheet duality for D-branes with travelling waves

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    We study D-branes with plane waves of arbitrary profiles as examples of time-dependent backgrounds in string theory. We show how to reproduce the quantum mechanical (one-to-one) open-string S-matrix starting from the closed-string boundary state for the D-branes, thereby establishing the channel duality of this calculation. The required Wick rotation to a Lorentzian worldsheet singles out as 'prefered' time coordinate the open-string light-cone time.Comment: 17 pages, Latex file, uses JHEP3.cls, two figures. Added references and corrected two typo

    Clean Time-Dependent String Backgrounds from Bubble Baths

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    We consider the set of controlled time-dependent backgrounds of general relativity and string theory describing ``bubbles of nothing'', obtained via double analytic continuation of black hole solutions. We analyze their quantum stability, uncover some novel features of their dynamics, identify their causal structure and observables, and compute their particle production spectrum. We present a general relation between squeezed states, such as those arising in cosmological particle creation, and nonlocal theories on the string worldsheet. The bubble backgrounds have various aspects in common with de Sitter space, Rindler space, and moving mirror systems, but constitute controlled solutions of general relativity and string theory with no external forces. They provide a useful theoretical laboratory for studying issues of observables in systems with cosmological horizons, particle creation, and time-dependent string perturbation theory.Comment: 38 pages, harvmac big, 6 figure
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