1,720 research outputs found

    Scattering of shock waves in QCD

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    The cross section of heavy-ion collisions is represented as a double functional integral with the saddle point being the classical solution of the Yang-Mills equations with boundary conditions/sources in the form of two shock waves corresponding to the two colliding ions. I develop the expansion of this classical solution in powers of the commutator of the Wilson lines describing the colliding particles and calculate the first two terms of the expansion.Comment: 23 pages, 13 figure

    The Effects of Flooding on Four Common Louisiana Marsh Plants

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    The marshes of the Louisiana coastline have been deteriorating for decades as plants experience increasing levels of flooding. In this study, we determined the effects of flood duration on four of the most common marsh plants in Louisiana—Spartina alterniflora, Spartina patens, Panicum hemitomon, and Sagittaria lancifolia—by exposing them to different flooding regimes: 0%, 20%, 40%, 60%, 80%, and 100% of the time flooded. Cumulative plant height, soil redox, and soil pH were measured weekly. At the end of the experiment, above- and belowground biomass were measured. Redox measurements showed that the saturated soil (0% flooded) was slightly depleted of oxygen at a redox potential of 300 mV, whereas oxygen was depleted and nitrate and/or manganese used as electron acceptors in all the flooded treatments (20–100% flooded), which had an average soil redox potential near 200 mV. In the saturated treatment, the soil was slightly acidic (pH average 4.7), whereas the flooded treatments had neutral soil acidity (pH average 7.3). Spartina alterniflora biomass was significantly affected by flooding. Spartina alterniflora biomass in the saturated treatment was approximately twice the biomass achieved in any of the flooding treatments. Spartina patens showed a rapid decline in biomass with increased flood duration, reaching the lowest values in treatments that were flooded more than 50% of the time. Although aboveground biomass of Sagittaria lancifolia was not significantly related to flooding regime, belowground biomass decreased with increased flooding duration. The only species that showed no significant response to flooding duration was P. hemitomon. Our results suggest that wetland restoration techniques that reduce flooding frequency are most appropriate for organic marshes dominated by Spartina patens and Spartina alterniflora, whereas these techniques may be less appropriate for organic marshes dominated by Sagittaria lancifolia and P. hemitomon

    Independent trapping and manipulation of microparticles using dexterous acoustic tweezers

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    An electronically controlled acoustic tweezer was used to demonstrate two acoustic manipulation phenomena: superposition of Bessel functions to allow independent manipulation of multiple particles and the use of higher-order Bessel functions to trap particles in larger regions than is possible with first-order traps. The acoustic tweezers consist of a circular 64-element ultrasonic array operating at 2.35MHz which generates ultrasonic pressure fields in a millimeter-scale fluid-filled chamber. The manipulation capabilities were demonstrated experimentally with 45 and 90-lm-diameter polystyrene spheres. These capabilities bring the dexterity of acoustic tweezers substantially closer to that of optical tweezers

    Development of the CoMac Adherence Descriptor™: a linguistically-based survey for segmenting patients on their worldviews

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    Nonadherence to prescribed medication and healthy behaviors is a pressing health care issue. Much research has been conducted in this area under a variety of labels, such as compliance, disease management and, most recently, adherence. However, the complex factors related to predicting and, more importantly, understanding and explaining adherence, have nevertheless remained elusive. However, through an in-depth linguistic analysis of patient talk, the International Center for Intercultural Communication (ICIC) at Indiana University has produced a psycholinguistic coding system that uses patients' own language to cluster them into distinct groups based on their worldviews. ICIC's studies have shown, for example, that patients reveal their fundamental perceptions about themselves and their environment in their life narratives; clustering of individual patients based on these different perceptions is possible via the use of differential language in survey questions, and differential language can be used to tailor messages for individual patients in a manner that these individuals prefer over generically worded communication. In grant-funded research, an interdisciplinary team of researchers at the ICIC reviewed the literature and identified three basic psychosocial tenets related to adherence: control orientation, based on locus of control research; agency, based on self-efficacy; and affect or attitude and emotion. These three constructs were selected because, in the published literature, they have been consistently found to be connected to patient adherence. Based on this research, a survey, the CoMac Descriptor™ was developed. This report shows that The Descriptor™ questions and responses are valid and reliable in segmenting patients across psychosocial constructs, which will have positive implications for health care providers and patients

    Leptogenesis implications in models with Abelian family symmetry and one extra real Higgs singlet

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    We show that the neutrino models, as suggested by Low, which have an additional Abelian family symmetry and a real Higgs singlet to the default see-saw do not hinder the possibility of successful thermal leptogenesis. For these models (neglecting radiative effects), we have investigated the situation of strong washout in both the one-flavor approximation and when flavor effects are included. The result is that while such models predict that theta_{13}=0 and that one light neutrino to be massless, they do not modify or provide significant constraints on the typical leptogenesis scenario where the final asymmetry is dominated by the decays of the lightest right-handed neutrinos.Comment: 18 pages, RevTeX4, accepted by Phys. Rev. D. v2: minor corrections, note and 1 ref. added, same content as published versio

    Cleft Care UK study. Part 5: Child psychosocial outcomes and satisfaction with cleft services

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    © 2015 John Wiley & Sons A/S. Objectives: To describe the impact of cleft service centralization on parental perceptions of child outcomes and satisfaction with care from the Cleft Care UK (CCUK) study and compare them to the Clinical Standards Advisory Group (CSAG) study that took place 15 years earlier. Setting and Sample Population: A subgroup of respondents from a UK multicentre cross-sectional study (CCUK) of 5-year-olds born with non-syndromic unilateral cleft lip and palate. Materials and Methods: Data on parents' perceptions of child self-confidence and their satisfaction with treatment outcomes and service provision were collected via self-report questionnaires. Data were compared with findings from the 1998 CSAG study. Results: Fewer parents in the CCUK study perceived their children as having poor self-confidence than in the 1998 CSAG study (8 and 19%, respectively). At least 81% of parents report satisfaction with the child's facial features after surgery and 98% report being satisfied with the care received. These results are similar to those reported in 1998. There is no evidence of an adverse impact on families' ability to attend appointments at the cleft clinic following centralization. Levels of reported problems (around 30%) with attendance were similar to those reported by CSAG. Conclusion: Centralization of cleft services appears to have improved parental perceptions of some child outcomes but has made little difference to already high levels of parental satisfaction with cleft care services. Centralization is not associated with an increase in the proportion of families who find it difficult to attend appointments

    Observation of Amounts of Movement Practice Provided during Stroke Rehabilitation

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    Objective To investigate how much movement practice occurred during stroke rehabilitation, and what factors might influence doses of practice provided. Design Observational survey of stroke therapy sessions. Setting Seven inpatient and outpatient rehabilitation sites. Participants We observed a convenience sample of 312 physical and occupational therapy sessions for people with stroke. Interventions Not applicable. Main Outcome Measures We recorded numbers of repetitions in specific movement categories and data on potential modifying factors (patient age, side affected, time since stroke, FIM item scores, years of therapist experience). Descriptive statistics were used to characterize amounts of practice. Correlation and regression analyses were used to determine whether potential factors were related to the amount of practice in the 2 important categories of upper extremity functional movements and gait steps. Results Practice of task-specific, functional upper extremity movements occurred in 51% of the sessions that addressed upper limb rehabilitation, and the average number of repetitions/session was 32 (95% confidence interval [CI]=20–44). Practice of gait occurred in 84% of sessions that addressed lower limb rehabilitation and the average number of gait steps/session was 357 (95% CI=296–418). None of the potential factors listed accounted for significant variance in the amount of practice in either of these 2 categories. Conclusions The amount of practice provided during poststroke rehabilitation is small compared with animal models. It is possible that current doses of task-specific practice during rehabilitation are not adequate to drive the neural reorganization needed to promote function poststroke optimally
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