1,264 research outputs found

    Saturn Forms by Core Accretion in 3.4 Myr

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    We present two new in situ core accretion simulations of Saturn with planet formation timescales of 3.37 Myr (model S0) and 3.48 Myr (model S1), consistent with observed protostellar disk lifetimes. In model S0, we assume rapid grain settling reduces opacity due to grains from full interstellar values (Podolak 2003). In model S1, we do not invoke grain settling, instead assigning full interstellar opacities to grains in the envelope. Surprisingly, the two models produce nearly identical formation timescales and core/atmosphere mass ratios. We therefore observe a new manifestation of core accretion theory: at large heliocentric distances, the solid core growth rate (limited by Keplerian orbital velocity) controls the planet formation timescale. We argue that this paradigm should apply to Uranus and Neptune as well.Comment: 4 pages, including 1 figure, submitted to ApJ Letter

    Promoting Team-Based Exercise Among African American Breast Cancer Survivors

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    Physical activity benefits the health and well-being of breast cancer survivors (BCS). Yet, many African American survivors do not routinely exercise and have increased risk of poor outcomes. The purpose of this mixed-method study was to identify motivational factors compelling African American BCS to participate in a 14-week team walking program and to intend to continue exercise after the intervention concluded. Focus groups were held with participants (n = 12) before and after training. Content analysis discovered themes before the intervention: Not wanting to go at it alone, exercise not a life or treatment priority, cancer treatment affected activity, advocates to exercise, and can exercise really help? Four themes postintervention themes included: In the same boat, changed mind-set, improved weight and activity, and overcoming barriers. Physical data verified improvements. Results suggest that a team-based exercise training program may assist in overcoming a sedentary behavior tendency and subsequently improve health among survivors

    Survivors Speak: A Qualitative Analysis of Motivational Factors Influencing Breast Cancer Survivors’ Participation in a Sprint Distance Triathlon

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    Aims and Objectives To examine motivational factors influencing breast cancer survivors to participate in triathlon training, complete a triathlon and maintain an exercise thereafter. Background Routine exercise has been shown to improve quality of life and reduce recurrence for breast cancer survivors. Yet physical and psychological factors present barriers for initiating and maintaining an exercise routine. Research is limited in exploring factors of exercise motivation from the survivor\u27s perspective. Design Qualitative design using focus groups and individual follow-up phone interviews to explore motivation for exercise initiation and maintenance. Methods One to two weeks after completing a triathlon, 11 breast cancer survivors who trained together participated in one of three focus groups to discuss their experience. Five months post triathlon 6 of the 11 participants were successfully contacted and phone interviews were conducted to explore exercise maintenance. Focus groups and interviews were analysed using content and thematic analysis. Results Five themes emerged (1) Champion for Exercise, (2) Part of a Team, (3) Everyone Had a Story, (4) Not Really Exercise and (5) What Do We Do Now? Overall, survivors recognised their need for lifestyle change (e.g. moving from a sedentary lifestyle to a more active one). More importantly, they identified the team approach to exercise initiation was crucial in their success in sustaining a behavioural change. Conclusions Emphasis needed on developing team exercise training programmes for survivors. Nurses can play a critical role in discussing with survivors, the benefits of exercise initiation and maintenance. Relevance to clinical practice Breast cancer survivors are hesitant to initiate routine exercise. Training with women who share a common lived experience increases the likelihood of success. Nurses are in a position to encourage breast cancer survivors to participate in group exercise programmes as a way to improve quality of life

    Development of the Orion Crew Module Static Aerodynamic Database

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    This work describes the process of developing the nominal static aerodynamic coefficients and associated uncertainties for the Orion Crew Module for Mach 8 and below. The database was developed from wind tunnel test data and computational simulations of the smooth Crew Module geometry, with no asymmetries or protuberances. The database covers the full range of Reynolds numbers seen in both entry and ascent abort scenarios. The basic uncertainties were developed as functions of Mach number and total angle of attack from variations in the primary data as well as computations at lower Reynolds numbers, on the baseline geometry, and using different flow solvers. The resulting aerodynamic database represents the Crew Exploration Vehicle Aerosciences Project's best estimate of the nominal aerodynamics for the current Crew Module vehicle

    PinR mediates the generation of reversible population diversity in Streptococcus zooepidemicus

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    Opportunistic pathogens must adapt to and survive in a wide range of complex ecosystems. Streptococcus zooepidemicus is an opportunistic pathogen of horses and many other animals, including humans. The assembly of different surface architecture phenotypes from one genotype is likely to be crucial to the successful exploitation of such an opportunistic lifestyle. Construction of a series of mutants revealed that a serine recombinase, PinR, inverts 114 bp of the promoter of SZO_08560, which is bordered by GTAGACTTTA and TAAAGTCTAC inverted repeats. Inversion acts as a switch, controlling the transcription of this sortase-processed protein, which may enhance the attachment of S. zooepidemicus to equine trachea. The genome of a recently sequenced strain of S. zooepidemicus, 2329 (Sz2329), was found to contain a disruptive internal inversion of 7 kb of the FimIV pilus locus, which is bordered by TAGAAA and TTTCTA inverted repeats. This strain lacks pinR and this inversion may have become irreversible following the loss of this recombinase. Active inversion of FimIV was detected in three strains of S. zooepidemicus, 1770 (Sz1770), B260863 (SzB260863) and H050840501 (SzH050840501), all of which encoded pinR. A deletion mutant of Sz1770 that lacked pinR was no longer capable of inverting its internal region of FimIV. The data highlight redundancy in the PinR sequence recognition motif around a short TAGA consensus and suggest that PinR can reversibly influence the wider surface architecture of S. zooepidemicus, providing this organism with a bet-hedging solution to survival in fluctuating environments

    Acute effects of an Avena sativa herb extract on responses to the Stroop Color-Word test

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    Background and aims: Extracts from oat (Avena sativa) herb may benefit cognitive performance. This study investigated whether Neuravena®, an oat herb extract, could acutely improve responses to the Stroop Color–Word test, a measure of attention and concentration and the ability to maintain task focus.  Subjects and methods: Elderly volunteers with below-average cognitive performance consumed single doses (0, 1600, and 2400 mg) of oat herb extract at weekly intervals in a double-blind, randomized, crossover comparison. Resting blood pressure (BP) was assessed before and after supplementation, and a Stroop test was performed.  Results: Significantly fewer errors were made during the color-naming component of the Stroop test after consuming the 1600-mg dose than after the 0-mg or 2400-mg doses (F (1,36)=18.85, p<0.001). In 7 subjects with suspected cognitive impairment, Stroop interference score was also improved by the 1600-mg dose compared to 0- and 2400-mg doses (F (1, 34)=2.40, p<0.01). Resting BP was unaffected by supplementation.  Conclusions: Taking 1600 mg of oat herb extract may acutely improve attention and concentration and the ability to maintain task focus in older adults with differing levels of cognitive status
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