307 research outputs found

    1+1+2 Electromagnetic perturbations on general LRS space-times: Regge-Wheeler and Bardeen-Press equations

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    We use the, covariant and gauge-invariant, 1+1+2 formalism developed by Clarkson and Barrett, and develop new techniques, to decouple electromagnetic (EM) perturbations on arbitrary locally rotationally symmetric (LRS) space-times. Ultimately, we derive 3 decoupled complex equations governing 3 complex scalars. One of these is a new Regge-Wheeler (RW) equation generalized for LRS space-times, whereas the remaining two are new generalizations of the Bardeen-Press (BP) equations. This is achieved by first using linear algebra techniques to rewrite the first-order Maxwell equations in a new complex 1+1+2 form which is conducive to decoupling. This new complex system immediately yields the generalized RW equation, and furthermore, we also derive a decoupled equation governing a newly defined complex EM 2-vector. Subsequently, a further decomposition of the 1+1+2 formalism into a 1+1+1+1 formalism is developed, allowing us to decompose the complex EM 2-vector, and its governing equations, into spin-weighted scalars, giving rise to the generalized BP equations

    Reverse engineering of a fixed wing unmanned aircraft 6-DoF model for navigation and guidance applications

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    A method for deriving the parameters of a six-degree-of-freedom (6-DoF) aircraft dynamics model by adopting reverse engineering techniques is presented. The novelty of the paper is the adaption of the 6-DoF Aircraft Dynamics Model (ADM) as a virtual sensor integrated in a low-cost navigation and guidance system designed for small Unmanned Aircraft (UA). The mass and aerodynamic properties of the JAVELIN UA are determined with the aid of an accurate 3D scanning and CAD processing. For qualitatively assessing the calculated ADM, a trajectory with high dynamics is simulated for the JAVELIN UA and compared with that of a published 6-DoF model of the AEROSONDE UA. Additionally, to confirm the validity of the approach, reverse engineering procedures are applied to a published CAD model of the AEROSONDE UA aiding to the calculation of the associated 6-DoF model parameters. A spiral descent trajectory is generated using both the published and calculated parameters of the AEROSONDE UA and a comparative analysis is performed that validates the methodology. The accurate knowledge of the ADM is then utilised in the development of a virtual sensor to augment the UA navigation and guidance system in case of primary navigation sensor outages

    Positive Counseling with College Students

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    College students face multiple challenges and can find college life to be overwhelming at times. In this paper, we examine how positive psychology, which embraces a strengths-based focus, has much to offer college students and their counselors. After providing an overview of positive psychology, we examine how positive psychology can be integrated into counseling generally and then more specifically into working with college students. We examine a number of different issues that college students face, and we offer different positive psychology techniques that have been found to be beneficial. Moreover, we provide a case study to demonstrate the benefits of taking a positive psychology approach to enhance counseling effectiveness. We also give attention to the potential benefits of taking a strengths-based approach to improving student retention and to how positive psychology can be applied to enhance the well-being of the counselor

    ‘A flying start’: Wildlife trypanosomes in tissues of Australian tabanids (Diptera: Tabanidae)

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    Tabanids (syn. horse flies) are biting-flies of medical and veterinary significance because of their ability to transmit a range of pathogens including trypanosomes – some species of which carry a combined health and biosecurity risk. Invertebrate vectors responsible for transmitting species of Trypanosoma between Australian wildlife remains unknown, thus establishing the role of potential vector candidates such as tabanids is of utmost importance. The current study aimed to investigate the presence of indigenous trypanosomes in tabanids from an endemic area of south-west Australia. A total of 148 tabanids were collected, with morphological analysis revealing two subgenera: Scaptia (Pseudoscione) and S. (Scaptia) among collected flies. A parasitological survey using an HRM-qPCR and sequencing approach revealed a high (105/148; 71%) prevalence of trypanosomatid DNA within collected tabanids. Individual tissues - proboscis (labrum, labium and mandibles, hypopharynx), salivary glands, proventriculus, midgut, and hindgut and rectum - were also tested from a subset of 20 tabanids (n = 140 tissues), confirming the presence of Trypanosoma noyesi in 31% of screened tissues, accompanied by T. copemani (3%) and T. vegrandis/T.gilletti (5%). An unconfirmed trypanosomatid sp. was also detected (9%) within tissues. The difference between tissues infected with T. noyesi compared with tissues infected with other trypanosome species was statistically significant (p < 0.05), revealing T. noyesi as the more frequent species detected in the tabanids examined. Fluorescence in situ hybridisation (FISH) and scanning electron microscopy (SEM) confirmed intact parasites within salivary glands and the proboscis respectively, suggesting that both biological and mechanical modes of transmission could occur. This study reveals the presence of Australian Trypanosoma across tabanid tissues and confirms intact parasites within tabanid salivary glands and the proboscis for the first time. Further investigations are required to determine whether tabanids have the vectorial competence to transmit Australian trypanosomes between wildlife

    Breaking voice identity perception: Expressive voices are more confusable for listeners.

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    The human voice is a highly flexible instrument for self-expression, yet voice identity perception is largely studied using controlled speech recordings. Using two voice-sorting tasks with naturally varying stimuli, we compared the performance of listeners who were familiar and unfamiliar with the TV show Breaking Bad. Listeners organised audio clips of speech with (1) low-expressiveness and (2) high-expressiveness into perceived identities. We predicted that increased expressiveness (e.g., shouting, strained voice) would significantly impair performance. Overall, while unfamiliar listeners were less able to generalise identity across exemplars, the two groups performed equivalently well when telling voices apart when dealing with low-expressiveness stimuli. However, high vocal expressiveness significantly impaired telling apart in both the groups: this led to increased misidentifications, where sounds from one character were assigned to the other. These misidentifications were highly consistent for familiar listeners but less consistent for unfamiliar listeners. Our data suggest that vocal flexibility has powerful effects on identity perception, where changes in the acoustic properties of vocal signals introduced by expressiveness lead to effects apparent in familiar and unfamiliar listeners alike. At the same time, expressiveness appears to have affected other aspects of voice identity processing selectively in one listener group but not the other, thus revealing complex interactions of stimulus properties and listener characteristics (i.e., familiarity) in identity processing

    Human osteoblast growth and maturation in response to metformin and the thienopyridone, A769662

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    Metformin (Met) is a biguanide drug widely used in the treatment and management of non insulin-dependent diabetes mellitus. In recent years it has emerged that Met, by stimulating adenosine monophosphate-activated protein kinase (AMPK), can promote the maturation of osteoblasts, albeit cells sourced from rodent and murine calvaria. Finding novel uses for existing drugs is especially appealing, primarily from the fiscal and time constraints posed in developing new products. Identifying agents capable of supporting human osteoblast growth and differentiation are attractive in a bone regenerative context. Since studies using Met are invariably restricted to rodent and murine osteoblasts we sought to investigate whether this biguanide might have a positive influence upon human osteoblast growth and maturation. To this end we examined the effect of Met on two osteoblast-like cell lines, MG63 and Saos-2, and compared the responses to primary human osteoblasts and their bone marrow-derived stem cell progeny. Furthermore we examined the effect of a cell permeable Met surrogate, A769662, which is a potent and far more selective activator of AMPK. Herein we report that Met is without influence on cell growth. Furthermore the application of Met, albeit in the millimolar range, actually inhibited osteoblast maturation. Conversely A769662 was toxic to the osteosarcoma-derived cell lines, MG63 and Saos-2, but without effect on the growth of primary cells or their stem cell progenitors. Since the cell lines are known to be p53 deficient we propose that activation of AMPK by A769662 could form part of the arsenal in the fight against osteosarcoma

    Children with lesbian parents: A community study

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    Existing research on children with lesbian parents is limited by reliance on volunteer or convenience samples. The present study examined the quality of parent-child relationships and the socio-emotional and gender development of a community sample of 7-year-old children with lesbian parents. Families were recruited through the Avon Longitudinal Study of Parents and Children, a geographic population study of 14,000 mothers and their children. Thirty-nine lesbian-mother families, 74 two-parent heterosexual families, and 60 families headed by single heterosexual mothers were compared on standardized interview and questionnaire measures administered to mothers, co-mothers/fathers, children, and teachers. Findings are in line with those of earlier investigations showing positive mother-child relationships and well-adjusted children

    A Role for Antimicrobial Stewardship in Clinical Sepsis Pathways: A Prospective Interventional Study

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    © 2017 by The Society for Healthcare Epidemiology of America. All rights reserved. OBJECTIVE To evaluate the impact of early infectious diseases (ID) antimicrobial stewardship (AMS) intervention on inpatient sepsis antibiotic management. DESIGN Interventional, nonrandomized, controlled study. SETTING Tertiary-care referral hospital, Sydney, Australia. PATIENTS Consecutive, adult, non-intensive care unit (non-ICU) inpatients triggering an institutional clinical sepsis pathway from May to August 2015. INTERVENTION All patients reviewed by an ID Fellow within 24 hours of sepsis pathway trigger underwent case review and clinic file documentation of recommendations. Those not reviewed by an ID Fellow were considered controls and received standard sepsis pathway care. The primary outcome was antibiotic appropriateness 48 hours after sepsis trigger. RESULTS In total, 164 patients triggered the sepsis pathway: 6 patients were excluded (previous sepsis trigger); 158 patients were eligible; 106 had ID intervention; and 52 were control cases. Of these 158 patients, 91 (58%) had sepsis, and 15 of these 158 (9.5%) had severe sepsis. Initial antibiotic appropriateness, assessable in 152 of 158 patients, was appropriate in 80 (53%) of these 152 patients and inappropriate in 72 (47%) of these patients. In the intervention arm, 93% of ID Fellow recommendations were followed or partially followed, including 53% of cases in which antibiotics were de-escalated. ID Fellow intervention improved antibiotic appropriateness at 48 hours by 24% (adjusted risk ratio, 1.24; 95% confidence interval, 1.04-1.47; P=.035). The appropriateness agreement among 3 blinded ID staff opinions was 95%. Differences in intervention and control group mortality (13% vs 17%) and median length of stay (13 vs 17.5 days) were not statistically significant. CONCLUSION Sepsis overdiagnosis and delayed antibiotic optimization may reduce sepsis pathway effectiveness. Early ID AMS improved antibiotic management of non-ICU inpatients with suspected sepsis, predominantly by de-escalation. Further studies are needed to evaluate clinical outcomes. Infect Control Hosp Epidemiol 2017;38:1032-1038
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