572 research outputs found

    Protostellar Disk Evolution Over Million-Year Timescales with a Prescription for Magnetized Turbulence

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    Magnetorotational instability (MRI) is the most promising mechanism behind accretion in low-mass protostellar disks. Here we present the first analysis of the global structure and evolution of non-ideal MRI-driven T-Tauri disks on million-year timescales. We accomplish this in a 1+1D simulation by calculating magnetic diffusivities and utilizing turbulence activity criteria to determine thermal structure and accretion rate without resorting to a 3-D magnetohydrodynamical (MHD) simulation. Our major findings are as follows. First, even for modest surface densities of just a few times the minimum-mass solar nebula, the dead zone encompasses the giant planet-forming region, preserving any compositional gradients. Second, the surface density of the active layer is nearly constant in time at roughly 10 g/cm2, which we use to derive a simple prescription for viscous heating in MRI-active disks for those who wish to avoid detailed MHD computations. Furthermore, unlike a standard disk with constant-alpha viscosity, the disk midplane does not cool off over time, though the surface cools as the star evolves along the Hayashi track. The ice line is firmly in the terrestrial planet-forming region throughout disk evolution and can move either inward or outward with time, depending on whether pileups form near the star. Finally, steady-state mass transport is a poor description of flow through an MRI-active disk. We caution that MRI activity is sensitive to many parameters, including stellar X-ray flux, grain size, gas/small grain mass ratio and magnetic field strength, and we have not performed an exhaustive parameter study here.Comment: Accepted for publication in Astrophysical Journal. 19 pages, including 8 figure

    Mom-it helps when youre right here! Attenuation of neural stress markers in anxious youths whose caregivers are present during fMRI.

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    Close proximity to an attachment figure, such as a caregiver, has been shown to attenuate threat-related activity in limbic regions such as the hypothalamus in healthy individuals. We hypothesized that such features might be similarly attenuated by proximity during a potentially stressful situation in a clinically anxious population of youths. Confirmation of this hypothesis could support the role of attachment figures in the management of anxiety among children and adolescents. Three groups were analyzed: anxious children and adolescents who requested that their caregiver accompany them in the scanner room, anxious children and adolescents without their caregiver in the scanner room and healthy controls (each of N = 10). The groups were matched for age and, among the two anxious groups, for diagnosis (mean age 9.5). The children and adolescents were exposed to physical threat words during an fMRI assessment. Results indicate that activity in the hypothalamus, ventromedial, and ventrolateral prefrontal cortex were significantly reduced in anxious children and adolescents who requested that their caregiver accompany them in the scanner room compared to those without their caregiver in the scanner room. Mean activity in these regions in anxious children and adolescents with their caregiver in the scanner room was comparable to that of healthy controls. These data suggest links between social contact and neural mechanisms of emotional reactivity; specifically, presence of caregivers moderates the increase in anxiety seen with stressful stimuli. Capitalizing on the ability of anxious youths to manifest low levels of anxiety-like information processing in the presence of a caregiver could help in modeling adaptive function in behavioral treatments

    The perceived hazard of earcons in information technology exception messages: The effect of musical dissonance: Working paper series--10-03

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    Users of information technology (IT) commonly encounter exception messages during their interactions with application programs to signal a computing problem or error. Exception messages often are accompanied by earcons which are aural messages of a musical nature used in the human-computer interface to provide information and feedback about some computer object, operation, or interaction. Utilizing the notion of musical dissonance earcons were designed that vary as to their degree of aural disagreeableness along a rank order scale. It is hypothesized that in the context of IT exception messages earcons with a higher degree of musical dissonance (aural disagreeableness) would be perceived as communicating a higher degree of hazard associated with the underlying computing problem signaled by an exception message. Participants rated the degree of hazard of each earcon presented in a random order in an experiment. Results of the data analysis indicate partial support of the hypothesis. The implications are that it may be possible to increase the degree of hazard matching in IT environments by designing earcons that accompany exception messages to communicate different levels of perceived hazard of an underlying computer problem

    Response of Degarelix treatment in human prostate cancer monitored by HR-MAS 1H NMR spectroscopy.

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    INTRODUCTION: The androgen receptor (AR) is the master regulator of prostate cancer cell metabolism. Degarelix is a novel gonadotrophin-releasing hormone blocker, used to decrease serum androgen levels in order to treat advanced human prostate cancer. Little is known of the rapid metabolic response of the human prostate cancer tissue samples to the decreased androgen levels. OBJECTIVES: To investigate the metabolic responses in benign and cancerous tissue samples from patients after treatment with Degarelix by using HRMAS 1H NMR spectroscopy. METHODS: Using non-destructive HR-MAS 1H NMR spectroscopy we analysed the metabolic changes induced by decreased AR signalling in human prostate cancer tissue samples. Absolute concentrations of the metabolites alanine, lactate, glutamine, glutamate, citrate, choline compounds [t-choline = choline + phosphocholine (PC) + glycerophosphocholine (GPC)], creatine compounds [t-creatine = creatine (Cr) + phosphocreatine (PCr)], taurine, myo-inositol and polyamines were measured in benign prostate tissue samples (n = 10), in prostate cancer specimens from untreated patients (n = 7) and prostate cancer specimens from patients treated with Degarelix (n = 6). RESULTS: Lactate, alanine and t-choline concentrations were significantly elevated in high-grade prostate cancer samples when compared to benign samples in untreated patients. Decreased androgen levels resulted in significant decreases of lactate and t-choline concentrations in human prostate cancer biopsies. CONCLUSIONS: The reduced concentrations of lactate and t-choline metabolites due to Degarelix could in principle be monitored by in vivo 1H MRS, which suggests that it would be possible to monitor the effects of physical or chemical castration in patients by that non-invasive method.We acknowledge the support of The University of Cambridge, Cancer Research UK (C14303/A17197) and Hutchison Whampoa Limited. The Human Research Tissue Bank is supported by the NIHR Cambridge Biomedical Research Centre.This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s11306-016-1055-0

    Creative Education

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    Effective online collaboration is a valuable instructional approach appropriate for 21st century teaching and learning. This paper describes a case that involves two higher education student cohorts from the United States and Australia engaged in a global collaboration to promote an authentic teaching and learning experience. The collaboration aims to involve students in sharing, reflecting and synthesizing new knowledge to make a comparative analysis between education systems from the two countries. The global collaboration is matched against an Assessment and Teaching of 21st Century Skills framework to comprehend and justify this approach as part of a teacher education course. This case advocates the value of having future teachers using online resources in a global context as a way to effectively integrate new content with various technology resources to develop new learning and new relationships beyond their own culture

    Parents Still Matter! Parental Warmth Predicts Adolescent Brain Function and Anxiety and Depressive Symptoms Two Years Later

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    Anxiety is the most prevalent psychological disorder among youth, and even following treatment, confers risk for anxiety relapse and the development of depression. Anxiety disorders are associated with heightened response to negative affective stimuli in brain networks underlying emotion processing. One factor that can attenuate symptoms of anxiety and depression in high-risk youth is parental warmth. The current study investigates whether parental warmth helps to protect against future anxiety and depressive symptoms in adolescents with histories of anxiety, and whether neural functioning in brain regions implicated in emotion processing and regulation can account for this link. Following anxiety disorder treatment (Time 1), thirty adolescents (M age=11.58, SD=1.26) reported on maternal warmth and, two years later (Time 2), participated in functional neuroimaging task where they listened to pre-recorded criticism and neutral statements from a parent. Higher maternal warmth predicted lower neural activation during criticism, compared with neutral statements, in the left amygdala, bilateral insula, subgenual anterior cingulate, right ventrolateral prefrontal cortex, and anterior cingulate cortex. Maternal warmth was associated with adolescents’ anxiety and depressive symptoms due to the indirect effects of sgACC activation, suggesting that parenting may attenuate risk for internalizing through its effects on brain function

    Protocol for the Metformin Aneurysm Trial (MAT): A placebo-controlled randomised trial testing whether metformin reduces the risk of serious complications of abdominal aortic aneurysm

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    Background: Multiple observational studies have associated metformin prescription with reduced progression of abdominal aortic aneurysm (AAA). The Metformin Aneurysm Trial (MAT) will test whether metformin reduces the risk of AAA rupture-related mortality or requirement for AAA surgery (AAA events) in people with asymptomatic aneurysms. Methods: MAT is an international, multi-centre, prospective, parallel-group, randomised, placebo-controlled trial. Participants must have an asymptomatic AAA measuring at least 35 mm in maximum diameter, no diabetes, no contraindication to metformin and no current plans for surgical repair. The double-blind period is preceded by a 6-week, single-blind, active run-in phase in which all potential participants receive metformin. Only patients tolerating metformin by taking at least 80% of allocated medication will enter the trial and be randomised to 1500 mg of metformin XR or an identical placebo. The primary outcome is the proportion of AAA events defined as rupture-related mortality or need for surgical repair. Secondary outcomes include AAA growth, major adverse cardiovascular events and health-related quality of life. In order to test if metformin reduced the risk of AAA events by at least 25%, 616 primary outcome events will be required (power 90%, alpha 0.05). Discussion: Currently, there is no drug therapy for AAA. Past trials have found no convincing evidence of the benefit of multiple blood pressure lowering, antibiotics, a mast cell inhibitor, an anti-platelet drug and a lipid-lowering medication on AAA growth. MAT is one of a number of trials now ongoing testing metformin for AAA. MAT, unlike these other trials, is designed to test the effect of metformin on AAA events. The international collaboration needed for MAT will be challenging to achieve given the current COVID-19 pandemic. If this challenge can be overcome, MAT will represent a trial unique within the AAA field in its large size and design

    Reasons for hospitalizations in patients with type 2 diabetes mellitus in the CANVAS Program:a secondary analysis

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    AIMS: To determine the reasons for hospitalizations in the CANagliflozin cardioVascular Assessment Study (CANVAS) Program and the effects of the sodium glucose co-transporter 2 inhibitor canagliflozin on hospitalization. MATERIALS AND METHODS: A secondary analysis was performed on the CANVAS Program that included 10,142 participants with type 2 diabetes mellitus randomized to canagliflozin or placebo. The primary outcome was total (first plus all recurrent) all-cause hospitalization (ACH). Secondary outcomes were total hospitalizations categorized by the Medical Dictionary for Regulatory Activities hierarchy at the system organ class level, reported by investigators at each center. Outcomes were assessed using negative binomial models. RESULTS: Of the 7115 hospitalizations reported, the most common reasons were cardiac disorders (23.7%), infections and infestations (15.0%), and nervous system disorders (9.0%). The rate of total ACH was lower in the canagliflozin group (n=5795) compared to the placebo group (n=4347): 197.9 versus 215.8 participants per 1000 patient-years, respectively (rate ratio [RR] 0.92; 95% confidence interval [CI] 0.86, 0.98). Canagliflozin reduced the rate of total hospitalizations due to cardiac disorders (RR 0.81; 95% CI 0.75, 0.88). There was no significant difference between the canagliflozin and placebo groups in the rates of total hospitalizations due to infections and infestations (RR 0.96; 95% CI 0.86, 1.02) or nervous system disorders (RR 0.96; 95% CI 0.88, 1.05). CONCLUSIONS: In the CANVAS Program, the most common reasons for hospitalization were cardiac disorders, infections and infestations, and nervous system disorders. Canagliflozin, compared with placebo, reduced the rate of total ACH. This article is protected by copyright. All rights reserved

    Prospectus, January 16, 1973

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    CHAMPAIGN-URBANA PEACE MARCH SCHEDULED; Anti-war resolution proposed; IOC meeting; Parkland trail riders; Please send a picture; Health program enrollment; Financial Board opening; All club treasurers; Can you help?; U.S. Gov\u27t Speaker; Debaters compete at ISU; Cruisin\u27 \u2773; True happenings; Ken\u27s munchy cereal; Equal tyme; Getting ignored by the biggies; PC lady hits the big time; Writer\u27s view questioned; Wanna graduate?; Big Kid\u27s Day?; little fat kid; Population, resources, environment; Mass demonstrations in D.C., Inauguration Day; Chi Gamma Iota; New campus regs; Freed injured; Movie Review: The Getaway; Prof Spectushttps://spark.parkland.edu/prospectus_1973/1014/thumbnail.jp
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