847 research outputs found

    Woman in Greece (Photograph)

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    Windows in Florence (Photograph)

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    Technical Skill Assessments as a Predictor or Agriculture Students\u27 Success after High School

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    This study was conducted using quantitative methods to determine if a relationship exists between former Agriculture Career and Technical Education (CTE) concentrators’ Technical Skills Assessment (TSA) performance and their attaining related placement after high school. The study included data from 13,581 agriculture students who graduated during the years 2015-2019. To investigate the relationship between TSA assessment performance and attaining related placement, multiple descriptive models were run and disaggregated by gender, race/ethnicity, Individuals Education Plan (IEP) status, and Socioeconomic Status (SES). The data revealed students who pass their TSA assessment are more likely to attain related placement compared to those not passing their assessment. Agriculture students’ rates of passing the TSA assessment and attaining related placement were high. Additional analysis to determine the relationship between TSA assessment performance and attaining related placement involved multiple binary logistic regression models. The logistic regression models helped determine how passing the TSA assessment and student demographics interacted and influenced students attaining related placement. Statistically significant findings were determined for TSA assessment, Black students, and those not disadvantaged in the SES category. The findings from this study may add merit to the numerous secondary CTE agriculture education programs in the United States. Keywords: Agriculture education, technical skill assessment, CTE accountability measures, industry-recognized credentia

    Adiabatic connection at negative coupling strengths

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    The adiabatic connection of density functional theory (DFT) for electronic systems is generalized here to negative values of the coupling strength α\alpha (with {\em attractive} electrons). In the extreme limit α\alpha\to-\infty a simple physical solution is presented and its implications for DFT (as well as its limitations) are discussed. For two-electron systems (a case in which the present solution can be calculated exactly), we find that an interpolation between the limit α\alpha\to-\infty and the opposite limit of infinitely strong repulsion (α+\alpha\to+\infty) yields a rather accurate estimate of the second-order correlation energy E\cor\glt[\rho] for several different densities ρ\rho, without using virtual orbitals. The same procedure is also applied to the Be isoelectronic series, analyzing the effects of near-degeneracy.Comment: 9 pages, submitted to PR

    The Fermionic Density-functional at Feshbach Resonance

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    We consider a dilute gas of neutral unpolarized fermionic atoms at zero temperature.The atoms interact via a short range (tunable) attractive interaction. We demonstrate analytically a curious property of the gas at unitarity. Namely, the correlation energy of the gas, evaluated by second order perturbation theory, has the same density dependence as the first order exchange energy, and the two almost exactly cancel each other at Feshbach resonance irrespective of the shape of the potential, provided (μrs)>>1(\mu r_s) >> 1. Here (μ)1(\mu)^{-1} is the range of the two-body potential, and rsr_s is defined through the number density n=3/(4πrs3)n=3/(4\pi r_s^3). The implications of this result for universality is discussed.Comment: Five pages, one table. accepted for publication in PR

    Retrofit Solutions for New Zealand Hollow-Core Floors and Investigation of Reliable Diaphragm Load-Paths in Earthquakes

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    Standard floor diaphragm design relies on compression struts and tension ties within the floor to transfer large forces between lateral load resisting structural elements and stiffen the building during earthquakes. Floors in reinforced concrete frame buildings have been observed with wide cracks around the floor perimeter following earthquakes, raising questions about how compression struts can form between the floor and frame elements. An experimental investigation into reliable floor diaphragm force transfer mechanisms, and by extension load-paths, was undertaken using a full-scale two-way super- assembly frame specimen. Two tests were conducted where the specimen was subjected to simultaneous bi-directional inter-storey drift demands to induce realistic earthquake cracking damage between the floor and the frame. At different floor damage states, in-plane shear deformations were applied to the frame specimen to capture the deterioration of diaphragm transfer load-paths. Wide perimeter cracking was anticipated to eliminate diaphragm compression strut load-paths until shear deformation of the support frame-initiated binding with the floor, as it changed to a rhomboidal shape. This behaviour was not observed due to two observed phenomena across the two tests. In the first test, loss of beam torsional stiffness governed as the diaphragm load-path failure mechanism. Beam-to-floor continuity reinforcement acting in tension exceeded the weak-axis shear and torsion capacity of the perimeter frame beam plastic hinges. Beam elongation deformation incompatibility demands were relieved by the tops of the beams rotating into the floor. Deformation concentrated in the beam plastic hinges rather than forming cracks at the beam-to-floor interface. In the second test, wide cracks developed at the support-beam-to-floor interfaces. However, despite this, the diaphragm in-plane shear stiffness deteriorated less than what was observed during the first test. It was found that diaphragm struts could form across wide beam-to-floor cracks due to aggregate rubble falling into the cracks and providing a residual contact stress load-path. Evidence of compression strut formation was recorded up to crack widths of 5.5 mm. An initial suggestion is that compression struts can cross wide cracks that are smaller than ¼ of the aggregate size used in the floor topping concrete mixture. This only applies where there is ductile continuity reinforcement crossing the critical crack interface. The rate of diaphragm shear stiffness degradation with increasing inter-storey drift demands was highly dependent on the ratio of simultaneous bi-directionality, due to the impact simultaneous bending actions had on beam torsional capacity. For low ratios of inter-storey drift simultaneous bi-directionality, beam torsional stiffness was maintained to a greater degree, providing higher diaphragm in-plane shear stiffness. An adjacent research stream was conducted related to hollow-core flooring systems. Hollow-core floors were widely installed in multi-storey buildings throughout New Zealand in the 1980s and 1990s. Hollow-core units were designed to act as simply supported members. Unfortunately, continuity reinforcement used to sustain floor diaphragm load-paths enforces deformation incompatibility demands on the floor during earthquakes, subjecting hollow-core units to substantial positive and negative bending moment demands they were not designed for. These demands can initiate a range of brittle failure mechanisms in the units. Concerns regarding the potential for commonly installed retrofits, used to increase seating widths for hollow-core units, to promote brittle failure of hollow-core units under negative moment demands prompted an experimental investigation. Six hollow-core unit sub-assembly experiments were used to identify unfavourable seating details which could cause negative moment failure of the floor during an earthquake and verify retrofit solutions to prevent this from occurring. Successful retrofits were installed in a full-scale two-way super-assembly frame specimen subjected to simultaneous bi-directional earthquake demands with full three-dimensional effects for further rigorous verification. Four viable retrofit strategies were identified and verified to prevent negative moment failure from occurring while providing adequate seating for the hollow-core units. Hollow-core units seated on beam plastic hinges extending out of interior frame columns, named beta units, were experimentally tested with seismic demands for the first time in the super-assembly experiment. Following inter-storey drift demands of 3%, the residual gravity carrying capacity of a beta unit with substantial web-splitting was tested. Shear failure of the unit near the support occurred at gravity load demands aligning to 91% of the NZS1170.5 (Standards New Zealand, 2016) design live load combination (1.2G + 1.5Q), demonstrating the vulnerability of beta units. Retrofit strategies to prevent brittle failure and collapse of vulnerable hollow-core units seated at the ends of support beams were also tested in the super-assembly specimen, providing verification and design improvements for catch-frame and hanger retrofits

    Radiomics-Based Outcome Prediction for Pancreatic Cancer Following Stereotactic Body Radiotherapy

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    (1) Background: Radiomics use high-throughput mining of medical imaging data to extract unique information and predict tumor behavior. Currently available clinical prediction models poorly predict treatment outcomes in pancreatic adenocarcinoma. Therefore, we used radiomic features of primary pancreatic tumors to develop outcome prediction models and compared them to traditional clinical models. (2) Methods: We extracted and analyzed radiomic data from pre-radiation contrast-enhanced CTs of 74 pancreatic cancer patients undergoing stereotactic body radiotherapy. A panel of over 800 radiomic features was screened to create overall survival and local-regional recurrence prediction models, which were compared to clinical prediction models and models combining radiomic and clinical information. (3) Results: A 6-feature radiomic signature was identified that achieved better overall survival prediction performance than the clinical model (mean concordance index: 0.66 vs. 0.54 on resampled cross-validation test sets), and the combined model improved the performance slightly further to 0.68. Similarly, a 7-feature radiomic signature better predicted recurrence than the clinical model (mean AUC of 0.78 vs. 0.66). (4) Conclusion: Overall survival and recurrence can be better predicted with models based on radiomic features than with those based on clinical features for pancreatic cancer

    Target temperature management following cardiac arrest : a systematic review and Bayesian meta-analysis

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    Background Temperature control with target temperature management (TTM) after cardiac arrest has been endorsed by expert societies and adopted in international clinical practice guidelines but recent evidence challenges the use of hypothermic TTM. Methods Systematic review and Bayesian meta-analysis of clinical trials on adult survivors from cardiac arrest undergoing TTM for at least 12 h comparing TTM versus no TTM or with a separation > 2 degrees C between intervention and control groups using the PubMed/MEDLINE, EMBASE, CENTRAL databases from inception to 1 September 2021 (PROSPERO CRD42021248140). All randomised and quasi-randomised controlled trials were considered. The risk ratio and 95% confidence interval for death (primary outcome) and unfavourable neurological recovery (secondary outcome) were captured using the original study definitions censored up to 180 days after cardiac arrest. Bias was assessed using the updated Cochrane risk-of-bias for randomised trials tool and certainty of evidence assessed using the Grading of Recommendation Assessment, Development and Evaluation methodology. A hierarchical robust Bayesian model-averaged meta-analysis was performed using both minimally informative and data-driven priors and reported by mean risk ratio (RR) and its 95% credible interval (95% CrI). Results In seven studies (three low bias, three intermediate bias, one high bias, very low to low certainty) recruiting 3792 patients the RR by TTM 32-34 degrees C was 0.95 [95% CrI 0.78-1.09] for death and RR 0.93 [95% CrI 0.84-1.02] for unfavourable neurological outcome. The posterior probability for no benefit (RR >= 1) by TTM 32-34 degrees C was 24% for death and 12% for unfavourable neurological outcome. The posterior probabilities for favourable treatment effects of TTM 32-34 degrees C were the highest for an absolute risk reduction of 2-4% for death (28-53% chance) and unfavourable neurological outcome (63-78% chance). Excluding four studies without active avoidance of fever in the control arm reduced the probability to achieve an absolute risk reduction > 2% for death or unfavourable neurological outcome toPeer reviewe
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