694 research outputs found

    Coalition capacity assessment of Columbia coalitions for a healthier Columbia (a qualitative assessment) [abstract]

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    Obesity is one of the leading public health concerns in the United States in adults and children. This qualitative study focused on five coalitions involved in addressing this issue in Columbia, MO. The coalitions are Playgrounds Without Borders Community Steering Committee, Columbia Action Network, Healthy Environment Policy Initiative, Grow Healthy Columbia/Boone County Partnership, and Move More Eat Smart

    Deep Reinforcement Learning Based Energy Storage Arbitrage With Accurate Lithium-ion Battery Degradation Model

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    Accurate estimation of battery degradation cost is one of the main barriers for battery participating on the energy arbitrage market. This paper addresses this problem by using a model-free deep reinforcement learning (DRL) method to optimize the battery energy arbitrage considering an accurate battery degradation model. Firstly, the control problem is formulated as a Markov Decision Process (MDP). Then a noisy network based deep reinforcement learning approach is proposed to learn an optimized control policy for storage charging/discharging strategy. To address the uncertainty of electricity price, a hybrid Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM) model is adopted to predict the price for the next day. Finally, the proposed approach is tested on the the historical UK wholesale electricity market prices. The results compared with model based Mixed Integer Linear Programming (MILP) have demonstrated the effectiveness and performance of the proposed framework

    Measurements of tidal flow variability in Ramsey Sound, Pembrokeshire

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    The nature of the flow at in-stream tidal energy sites is particularly important for predicting array and device performance, and also for operations and maintenance planning. Previous developers have reported issues such as the choice of vessel, cost of operations, and the limits of operation of deployment vessels. The dynamics of the flow around slack water has been of particular interest at Ramsey Sound in Pembrokeshire (UK) for planning the recovery of an existing turbine, the Tidal Energy Limited ‘Deltastream’. This research presents flow characteristics of Ramsey Sound, based on analysis of Acoustic Doppler Current Profiler (ADCP) measurements and tide gauge data from the nearby Standard Port of Milford Haven. The ADCP was located approximately 300 m across the channel, at the northern end of the channel, where the channel width was 1200 m and the mean depth was approximately 33 m. The flow dynamics were examined specifically to look at times potentially suitable for offshore operations Two weeks of data were used in the analysis, spanning a complete spring-neap cycle. Results demonstrate that flow velocities exhibited clear asymmetry, with stronger flows on the northerly directed flood tide than on the ebb. There was considerable variation in the measured current speed around the time of the maximum, suggesting large scale bed feature generated turbulence. The flood (northerly) current maximum was approximately in phase with high water at Milford Haven. Cross correlation indicated that the flow generally led the elevation by 20 minutes. In contrast to the expected theory, the current strength at mid-depth was stronger than at the surface on the maximum flood tide. The maximum flow speed in the tide was reasonably predictable from the tide range at Milford. A threshold-based analysis of the ADCP measurements allowed the duration of slow-moving water to be identified for operation planning. Operations and planning in light of sound understanding of hydrodynamics at tidal energy sites is critical for future economic success of the tidal energy sector. The results shown here from an ADCP deployment in Ramsey Sound have shown the capability to give useful tools for planning recovery operations

    Discovery of an ultramassive pulsating white dwarf

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    We announce the discovery of the most massive pulsating hydrogen-atmosphere (DA) white dwarf (WD) ever discovered, GD 518. Model atmosphere fits to the optical spectrum of this star show it is a 12,030 +/- 210 K WD with a log(g) = 9.08 +/- 0.06, which corresponds to a mass of 1.20 +/- 0.03 Msun. Stellar evolution models indicate that the progenitor of such a high-mass WD endured a stable carbon-burning phase, producing an oxygen-neon-core WD. The discovery of pulsations in GD 518 thus offers the first opportunity to probe the interior of a WD with a possible oxygen-neon core. Such a massive WD should also be significantly crystallized at this temperature. The star exhibits multi-periodic luminosity variations at timescales ranging from roughly 425-595 s and amplitudes up to 0.7%, consistent in period and amplitude with the observed variability of typical ZZ Ceti stars, which exhibit non-radial g-mode pulsations driven by a hydrogen partial ionization zone. Successfully unraveling both the total mass and core composition of GD 518 provides a unique opportunity to investigate intermediate-mass stellar evolution, and can possibly place an upper limit to the mass of a carbon-oxygen-core WD, which in turn constrains SNe Ia progenitor systems.Comment: 5 pages, 3 figures, Astrophysical Journal Letters, 771, L2 (2013

    Clinical Profile and Disability Levels of Younger vs. Older TKR and THR Patients in a National Research Consortium

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    Introduction: A growing number of patients under 65 years old undergo total knee replacement (TKR) and total hip replacement (THR).1 This trend has raised concerns that younger patients may receive surgery prematurely. We examined demographic and clinical factors in younger versus older patients in a national sample of THR and THR patients. Methods: Patients undergoing primary TKR and THR from 7/1/11 through 12/03/12 were identified from a national research consortium that gathers demographics, comorbid conditions (Charlson Comorbidity Index), Short Form 36 Physical Component Score (PCS) and Mental Component Score (MCS), burden of musculoskeletal disease using the Knee injury and Osteoarthritis Outcome Score (KOOS) or the Hip injury and Osteoarthritis Outcome Score (HOOS) and the Oswestry Low Back Pain Disability Questionnaire. Descriptive statistics were performed. Results: TKR patients included 1326 younger ( Conclusion: Younger patients have fewer medical illnesses at the time of TKR or THR, but have greater functional impairment and higher rates of obesity and smoking as well as lower mental health scores

    Discovery of pulsations, including possible pressure modes, in two new extremely low mass, He-core white dwarfs

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    We report the discovery of the second and third pulsating extremely low mass white dwarfs (WDs), SDSS J111215.82+111745.0 (hereafter J1112) and SDSS J151826.68+065813.2 (hereafter J1518). Both have masses < 0.25 Msun and effective temperatures below 10,000 K, establishing these putatively He-core WDs as a cooler class of pulsating hydrogen-atmosphere WDs (DAVs, or ZZ Ceti stars). The short-period pulsations evidenced in the light curve of J1112 may also represent the first observation of acoustic (p-mode) pulsations in any WD, which provide an exciting opportunity to probe this WD in a complimentary way compared to the long-period g-modes also present. J1112 is a Teff = 9590 +/- 140 K and log(g) = 6.36 +/- 0.06 WD. The star displays sinusoidal variability at five distinct periodicities between 1792-2855 s. In this star we also see short-period variability, strongest at 134.3 s, well short of expected g-modes for such a low-mass WD. The other new pulsating WD, J1518, is a Teff = 9900 +/- 140 K and log(g) = 6.80 +/- 0.05 WD. The light curve of J1518 is highly non-sinusoidal, with at least seven significant periods between 1335-3848 s. Consistent with the expectation that ELM WDs must be formed in binaries, these two new pulsating He-core WDs, in addition to the prototype SDSS J184037.78+642312.3, have close companions. However, the observed variability is inconsistent with tidally induced pulsations and is so far best explained by the same hydrogen partial-ionization driving mechanism at work in classic C/O-core ZZ Ceti stars.Comment: 9 pages, 5 figures, accepted to The Astrophysical Journa

    Social Support and Total Joint Replacement: Differences Preoperatively between Patients Living Alone and Those Living with Others

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    Introduction: Social relationships affect mental health, physical health, and mortality risk. Little is known about social support and patients electing to have total joint replacement (TJR) surgery. We explored the differences between participants living alone and those living with at least one other adult prior to TJR surgery. Materials & methods: Preoperative and 6 month postoperative FORCE-TJR Registry survey data were collected from 6269 primary unilateral TJR patients between May 2011 and December 2013. Data included demographics, comorbid conditions, operative joint pain severity (HOOS/KOOS), musculoskeletal disease burden, physical function (SF-36 PCS), and mental health (SF36 MCS). Results: Participants living alone were more likely to be older, female, on Medicare, with a high school education or less, and a racial/ethnic minority. Prior to surgery, they reported a greater number of comorbid conditions and non-surgical joints causing pain. Those living alone also had lower mean MCS summary measure, lower Social Functioning Scale score and a lower HOOS/KOOS Activities of Daily Living score before TJR. There were no differences preoperatively in mean BMI, mean PCS, or HOOS/KOOS surgical joint pain, symptoms, or quality of life scores between the two groups. Six months postoperatively, those living alone had lower mean PCS and MCS, but were more likely to report less pain and symptoms in the surgical joint. Unadjusted analyses of mean change over time found less improvement in PCS for those living alone compared to those not living alone. Conclusion: Recognizing differences in social support prior to TJR surgery could inform interventions and potentially influence patient reported outcomes postoperatively

    What have human experimental overfeeding studies taught us about adipose tissue expansion and susceptibility to obesity and metabolic complications?

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    Overfeeding experiments, in which we impose short-term positive energy balance, help unravel the cellular, physiological and behavioural adaptations to nutrient excess. These studies mimic longer-term mismatched energy expenditure and intake. There is considerable inter-individual heterogeneity in the magnitude of weight gain when exposed to similar relative caloric excess reflecting variable activation of compensatory adaptive mechanisms. Significantly, given similar relative weight gain, individuals may be protected from/predisposed to metabolic complications (insulin resistance, dyslipidaemia, hypertension), non-alcoholic fatty liver disease and cardiovascular disease. Similar mechanistic considerations underpinning the heterogeneity of overfeeding responses are pertinent in understanding emerging metabolic phenotypes, for example, metabolically unhealthy normal weight and metabolically healthy obesity. Intrinsic and extrinsic factors modulate individuals’ overfeeding response: intrinsic factors include gender/hormonal status, genetic/ethnic background, baseline metabolic health and cardiorespiratory fitness; extrinsic factors include macronutrient (fat vs carbohydrate) content, fat/carbohydrate composition and overfeeding pattern. Subcutaneous adipose tissue (SAT) analysis, coupled with metabolic assessment, with overfeeding have revealed how SAT remodels to accommodate excess nutrients. SAT remodelling occurs either by hyperplasia (increased adipocyte number) or by hypertrophy (increased adipocyte size). Biological responses of SAT also govern the extent of ectopic (visceral/liver) triglyceride deposition. Body composition analysis by DEXA/MRI (dual energy X-ray absorptiometry/magnetic resonance imaging) have determined the relative expansion of SAT (including abdominal/gluteofemoral SAT) vs ectopic fat with overfeeding. Such studies have contributed to the adipose expandability hypothesis whereby SAT has a finite capacity to expand (governed by intrinsic biological characteristics), and once capacity is exceeded ectopic triglyceride deposition occurs. The potential for SAT expandability confers protection from/predisposes to the adverse metabolic responses to overfeeding. The concept of a personal fat threshold suggests a large inter-individual variation in SAT capacity with ectopic depot expansion/metabolic decompensation once one’s own threshold is exceeded. This review summarises insight gained from overfeeding studies regarding susceptibility to obesity and related complications with nutrient excess
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