5,960 research outputs found

    Certain minimal varieties are set-theoretic complete intersections

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    We present a class of homogeneous ideals which are generated by monomials and binomials of degree two and are set-theoretic complete intersections. This class includes certain reducible varieties of minimal degree and, in particular, the presentation ideals of the fiber cone algebras of monomial varieties of codimension two

    Pediatric Resident Knowledge, Confidence, and Experience in Transitioning Youth with Special Healthcare Needs

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    Background. The transition from pediatric to adult healthcare is vital to the 17% of adolescents with special healthcare needs (SHCN). Barriers to successful transition exist. The purpose of this study was to assess the baseline knowledge, confidence, and experience of pediatric residents in our state on transitioning adolescents with SHCN from pediatric to adult-oriented health care. Methods. An anonymous, voluntary, self-report survey was distributed electronically via Survey Monkey® to 2011-2012 pediatric residents in the state of Kansas (n = 39). Results. Of 39 pediatric residents, 21 (54%) completed the survey. Most (71%) had two or fewer adolescents with SHCN on their patient panel. Overall, the majority categorized their knowledge (71%) and experience (81%) transitioning adolescents with SHCN as minimal or very minimal. Conclusions. Pediatric residents report a general lack of knowledge, confidence, and experience in transitioning youth with SHCN. Additional training opportunities are needed to overcome the barriers in successful transition planning

    Coupled cavities for enhancing the cross-phase modulation in electromagnetically induced transparency

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    We propose an optical double-cavity resonator whose response to a signal is similar to that of an Electromagnetically Induced Transparency (EIT) medium. A combination of such a device with a four-level EIT medium can serve for achieving large cross-Kerr modulation of a probe field by a signal field. This would offer the possibility of building a quantum logic gate based on photonic qubits. We discuss the technical requirements that are necessary for realizing a probe-photon phase shift of Pi caused by a single-photon signal. The main difficulty is the requirement of an ultra-low reflectivity beamsplitter and to operate a sufficiently dense cool EIT medium in a cavity.Comment: 10 pages, 5 figures, REVTeX, to appear in Phys. Rev. A (v2 - minor changes in discussion of experimental conditions

    SPI observations of positron annihilation radiation from the 4th galactic quadrant: sky distribution

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    During its first year in orbit the INTEGRAL observatory performed deep exposures of the Galactic Center region and scanning observations of the Galactic plane. We report on the status of our analysis of the positron annihilation radiation from the 4th Galactic quadrant with the spectrometer SPI, focusing on the sky distribution of the 511 keV line emission. The analysis methods are described; current constraints and limits on the Galactic bulge emission and the bulge-to-disk ratio are presented.Comment: 4 pages, 2 figures, accepted for publication in the proceedings of the 5th INTEGRAL worksho

    Stress and visual function in infantile nystagmus syndrome.

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    PURPOSE: Infantile nystagmus syndrome (INS) is an involuntary oscillation of the eyes that has been reported to impair vision and worsen under stress. This investigation aimed to measure visual function in terms of visual acuity (VA) and response time (RT), when INS subjects are placed under stress. METHODS: A total of 23 subjects with INS and 20 control subjects performed a 2-alternative forced choice (2AFC) staircase procedure identifying the gap in a Landolt C, under 4 experimental conditions: initial acclimatization (A); task demand (TD), during which subjects received a small electrical shock for every incorrect answer; anticipatory anxiety (AA), during which subjects received a small shock at random intervals; and relaxed (R). Arousal was monitored with galvanic skin conductance (SkC). In addition to VA and eye movements, RTs were recorded. RESULTS: The SkC was higher in the TD and AA periods and lower during A and R. Shock significantly increased nystagmus amplitude (P < 0.01) and intensity (P < 0.007), and reduced foveation periods (FPs, P < 0.022). In both groups, VA was not reduced, but showed a slight improvement. However, shock increased RT (P < 0.009), and INS subjects were slower than controls (P < 0.0005). CONCLUSIONS: Increased arousal ("stress") provoked more intense nystagmus eye movements. As seen in other studies, stress did not reduce VA despite the shorter FPs. Although VA and FP can correlate across subjects, there would appear to be little correlation, if any, within a subject. However, RTs did increase with stress and shorter FPs, which may have an adverse impact on the visual performance of those with INS

    A Primary Care Nurse-Delivered Walking Intervention in Older Adults: PACE (Pedometer Accelerometer Consultation Evaluation)-Lift Cluster Randomised Controlled Trial.

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    Background: Brisk walking in older people can increase step-counts and moderate to vigorous intensity physical activity (MVPA) in ≥10-minute bouts, as advised in World Health Organization guidelines. Previous interventions have reported step-count increases, but not change in objectively measured MVPA in older people. We assessed whether a primary care nurse-delivered complex intervention increased objectively measured step-counts and MVPA. Methods and Findings: A total of 988 60–75 year olds, able to increase walking and randomly selected from three UK family practices, were invited to participate in a parallel two-arm cluster randomised trial; randomisation was by household. Two-hundred-ninety-eight people from 250 households were randomised between 2011 and 2012; 150 individuals to the intervention group, 148 to the usual care control group. Intervention participants received four primary care nurse physical activity (PA) consultations over 3 months, incorporating behaviour change techniques, pedometer step-count and accelerometer PA intensity feedback, and an individual PA diary and plan. Assessors were not blinded to group status, but statistical analyses were conducted blind. The primary outcome was change in accelerometry assessed average daily step-counts between baseline and 3 months, with change at 12 months a secondary outcome. Other secondary outcomes were change from baseline in time in MVPA weekly in ≥10-minute bouts, accelerometer counts, and counts/minute at 3 months and 12 months. Other outcomes were adverse events, anthropometric measures, mood, and pain. Qualitative evaluations of intervention participants and practice nurses assessed the intervention’s acceptability. At 3 months, eight participants had withdrawn or were lost to follow-up, 280 (94%) individuals provided primary outcome data. At 3 months changes in both average daily step-counts and weekly MVPA in ≥10-minute bouts were significantly higher in the intervention than control group: by 1,037 (95% CI 513–1,560) steps/day and 63 (95% CI 40–87) minutes/week, respectively. At 12 months corresponding differences were 609 (95% CI 104–1,115) steps/day and 40 (95% CI 17–63) minutes/week. Counts and counts/minute showed similar effects to steps and MVPA. Adverse events, anthropometry, mood, and pain were similar in the two groups. Participants and practice nurses found the intervention acceptable and enjoyable. Conclusions : The PACE-Lift trial increased both step-counts and objectively measured MVPA in ≥10-minute bouts in 60–75 year olds at 3 and 12 months, with no effect on adverse events. To our knowledge, this is the first trial in this age group to demonstrate objective MVPA increases and highlights the value of individualised support incorporating objective PA assessment in a primary care setting. Trial Registration: Controlled-Trials.com ISRCTN4212256

    Transverse Fresnel-Fizeau drag effects in strongly dispersive media

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    A light beam normally incident upon an uniformly moving dielectric medium is in general subject to bendings due to a transverse Fresnel-Fizeau light drag effect. In conventional dielectrics, the magnitude of this bending effect is very small and hard to detect. Yet, it can be dramatically enhanced in strongly dispersive media where slow group velocities in the m/s range have been recently observed taking advantage of the electromagnetically induced transparency (EIT) effect. In addition to the usual downstream drag that takes place for positive group velocities, we predict a significant anomalous upstream drag to occur for small and negative group velocities. Furthermore, for sufficiently fast speeds of the medium, higher order dispersion terms are found to play an important role and to be responsible for peculiar effects such as light propagation along curved paths and the restoration of the spatial coherence of an incident noisy beam. The physics underlying this new class of slow-light effects is thoroughly discussed

    Towards deterministic optical quantum computation with coherently driven atomic ensembles

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    Scalable and efficient quantum computation with photonic qubits requires (i) deterministic sources of single-photons, (ii) giant nonlinearities capable of entangling pairs of photons, and (iii) reliable single-photon detectors. In addition, an optical quantum computer would need a robust reversible photon storage devise. Here we discuss several related techniques, based on the coherent manipulation of atomic ensembles in the regime of electromagnetically induced transparency, that are capable of implementing all of the above prerequisites for deterministic optical quantum computation with single photons.Comment: 11 pages, 7 figure

    Bright squeezing from self-induced transparencies in dressed three-level atoms

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    We investigate two schemes for the efficient conversion of coherent input light into bright-squeezed output light. Both schemes utilize strong signal and weak probe fields, interacting with three-level ladder-configuration atoms inside optical cavities. The schemes differ in the resonance requirements of the cavities and produce noise suppression for quite different tuning regimes. Quantum-noise reduction is a consequence of the dressing of the atoms with two coherent fields. By tuning the probe light in the right fashion, spontaneous emission from the excited state can be made to counteract signal-light intensity fluctuations
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