713 research outputs found

    On the Supergravity Evaluation of Wilson Loop Correlators in Confining Theories

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    We explicitly show the area law behavior of a circular Wilson loop in confining theories from supergravity. We calculate the correlator of two Wilson loops from supergravity in confining backgrounds. We find that it is dominated by an exchange of a ``scalarball'' that is lighter than the glueballs. We interpret these results in terms of the meson-meson potential in such theories.Comment: Latex, 13 pages, 2 figure

    Host Use and Geographic Variation in Fall Webworms (Hyphantria cunea)

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    Host use in herbivores is determined by a variety of ecological drivers, including bottom-up and top-down selective pressures such as host abundance, host plant quality, and parasitism pressure. If the relative importance and strength of interactions among these selective conditions change over an herbivore’s geographic range, local patterns of host use should change in response, evident in differing diet breadths. The fall webworm (Hyphantria cunea) is a widespread, polyphagous moth with two color morphs, red and black-headed. In the eastern United States, fall webworms feed on dozens of plant species and previous research demonstrated that host plant abundance was the only significant predictor of host plant use. Populations of fall webworm in Colorado are found on considerably fewer host plant species than populations farther east. We investigated the impacts of host abundance, larval performance, and parasitism on patterns of host use for fall webworm in Colorado to determine whether differences in selective pressures may explain why these populations are relatively more specialized compared to previously-studied populations. Additionally, we used DNA sequences from fall webworms collected across their geographic range to investigate genetic variation via phylogenetic tree building and AMOVAs. Using those genetic techniques, we found that red-headed and black-headed fall webworms are not reproductively isolated, but there are two genetic groups: one that is exclusively black-headed and one that is both red and black-headed. Similar to studies on eastern populations, we found that host abundance was a significant predictor of host use. We also found a trade-off between host quality, as measured by larval performance, and percent parasitism. Host plants that supported larvae with higher fitness, as measured by survival, pupal weight, feeding efficiency, and development time, also had a greater proportion of larval mortality due to parasitism. Local patterns of host plant abundance may lead fall webworms to a relatively restricted diet in Colorado compared to the east coast, while the trade-off between quality and parasitism may explain the maintenance of a generalized feeding strategy

    Constructive factorization of LPDO in two variables

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    We study conditions under which a partial differential operator of arbitrary order nn in two variables or ordinary linear differential operator admits a factorization with a first-order factor on the left. The factorization process consists of solving, recursively, systems of linear equations, subject to certain differential compatibility conditions. In the generic case of partial differential operators one does not have to solve a differential equation. In special degenerate cases, such as ordinary differential, the problem is finally reduced to the solution of some Riccati equation(s). The conditions of factorization are given explicitly for second- and, and an outline is given for the higher-order case.Comment: 16 pages, to be published in Journal "Theor. Math. Phys." (2005

    Model selection and prediction of outcomes in recent onset schizophrenia patients who undergo cognitive training.

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    Predicting treatment outcomes in psychiatric populations remains a challenge, but is increasingly important in the pursuit of personalized medicine. Patients with schizophrenia have deficits in cognition, and targeted cognitive training (TCT) of auditory processing and working memory has been shown to improve some of these impairments; but little is known about the baseline patient characteristics predictive of cognitive improvement. Here we use a model selection and regression approach called least absolute shrinkage and selection operator (LASSO) to examine predictors of cognitive improvement in response to TCT for patients with recent onset schizophrenia. Forty-three individuals with recent onset schizophrenia randomized to undergo TCT were assessed at baseline on measures of cognition, symptoms, functioning, illness duration, and demographic variables. We carried out 10-fold cross-validation of LASSO for model selection and regression. We followed up on these results using linear models for statistical inference. No individual variable was found to correlate with improvement in global cognition using a Pearson correlation approach, and a linear model including all variables was also found not to be significant. However, the LASSO model identified baseline global cognition, education, and gender in a model predictive of improvement on global cognition following TCT. These findings offer guidelines for personalized approaches to cognitive training for patients with schizophrenia

    Deforming baryons into confining strings

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    We find explicit probe D3-brane solutions in the infrared of the Maldacena-Nunez background. The solutions describe deformed baryon vertices: q external quarks are separated in spacetime from the remaining N-q. As the separation is taken to infinity we recover known solutions describing infinite confining strings in N=1{\mathcal{N}}=1 gauge theory. We present results for the mass of finite confining strings as a function of length. We also find probe D2-brane solutions in a confining type IIA geometry, the reduction of a G_2 holonomy M theory background. The relation between these deformed baryons and confining strings is not as straightforward.Comment: 1+13 pages. LaTeX. 3 Figures. Factor of 2N fixed to N for the IIA background. Minor changes to tex

    Assessing HeartSong as a Neonatal Music Therapy Intervention:A Qualitative Study on Personal and Professional Caregivers' Perspectives

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    Background: The music therapy HeartSong intervention pairs newborn infant heartbeats with parents' Song of Kin. Formal evidence on professional and personal caregiver perspectives of this intervention is lacking. Purpose: This survey study evaluates the HeartSong music therapy intervention from parent and staff perspectives. Methods: A qualitative study assessing inclusion of HeartSong for family neonatal intensive care unit (NICU) care surveyed 10 professional caregivers comprising medical and psychosocial NICU teams anonymously reflecting their impressions of the intervention. Digital survey of parents/guardians contacted through semistructured phone interviews relayed impressions of recordings: subsequent setup, Song of Kin selection, and use of HeartSong, including thoughts/feelings about it as an intervention. Results: Professional and personal caregivers valued the HeartSong intervention for bereavement support, family support, including parental, extended family/infant support, and to enhance bonding. Emergent themes: memory-making, connectedness/closeness, support of parent role, processing mental health needs of stressful NICU days, and subsequent plans for lifelong HeartSong use. Therapeutic experience was named as a crucial intervention aspect and participants recommended the HeartSong as a viable, accessible NICU intervention. Implications for Practice and Research: HeartSong's use showed efficacy as a clinical NICU music therapy intervention for families of critically ill and extremely preterm infants, when provided by trained, specialized, board-certified music therapists. Future research focusing on HeartSong in other NICU populations might benefit infants with cardiac disease, parental stress, and anxiety attending to parent-infant bonding. Costs and time benefits related to investment are needed before implementation is considered.</p
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