4,027 research outputs found

    Adsorption of Alkanes on the Platinum Surface: Density Functional Theory compared to the Random Phase Approximation

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    Die Dichtefunktionaltheorie (DFT) einschließlich Dispersionkorrekturen (+D) wird mit der Random-Phase-Approximation (RPA) fĂŒr die Adsorption von Alkanen auf der Pt(111)-OberflĂ€che verglichen. RPA wird zuerst im Hinblick auf relevante technische Parameter evaluiert und fĂŒr die Methanadsorption an der Pt(111)-OberflĂ€che getestet. Im Vergleich zum Perdew-Burke-Ernzerhof-Funktional (PBE) mit Tkatchenkos Many-Body-Dispersionskorrektur (PBE+MBD) liefert RPA gute Ergebnisse. Auch reproduziert RPA experimentelle Adsorptionsenergien bei verschiedenen, physikalisch sinnvollen Beladungsstufen der Pt(111) OberflĂ€che mit AlkanmolekĂŒlen. FĂŒr Platin in der hexagonal dichtesten Kugelpackung sagt RPA richtigerweise die Methanadsorption an der hollow-tripod-Stelle voraus, wĂ€hrend mit PBE+MBD die Adsorption an einer anderen Stelle bevorzugt wĂ€re. Dies geht aus Schwingungsspektren hervor. Da periodisches RPA sehr rechenaufwĂ€ndig ist, wird ein QM:QM Hybridansatz (QM=Quantenmechanik) angewendet, wobei periodisches PBE(+D) mithilfe von RPA Rechnungen an Clustern korrigiert wird (RPA:PBE(+D)). In einem Test verschiedener Dispersionskorrekturen schneiden RPA:PBE und RPA:PBE+MBD am besten ab. Diese Arbeit ist wegbereitend fĂŒr die Anwendung des QM:QM Hybridansatzes zur Beschreibung der Adsorptionsprozesse an MetalloberflĂ€chen ‒ bei hoher Genauigkeit und deutlich verringertem Rechenaufwand. Auch Kresses low-scaling RPA Algorithmus wird getestet. Dieser Algorithmus ermöglicht, große Systeme, wie z.B. die Methan-, Ethan-, Propan- und n-Butanadsorption an Pt(111), zu untersuchen. Der Vergleich mit experimentellen Daten zeigt, dass mit RPA stets die beste Übereinstimmung erreicht wird. Dabei wird eine deutliche Verbesserung gegenĂŒber allen untersuchten Dichte-Funktionalen erzielt. Obwohl Bindungen mit RPA etwas zu schwach vorhergesagt werden, ist es die derzeit beste Methode zur Untersuchung der Adsorption an MetalloberflĂ€chen und damit der Benchmark fĂŒr diese Systeme.Density Functional Theory (DFT) including dispersion (+D) is compared against the Random Phase Approximation (RPA) for the adsorption of alkanes on the Pt(111) surface. RPA is first benchmarked with respect to technical parameters and tested for methane adsorption on Pt(111). It is found to perform well relative to the Perdew–Burke–Ernzerhof (PBE) functional augmented with the many-body dispersion scheme of Tkatchenko (PBE+MBD). It also compares well relative to experimentally derived adsorption energies at physically relevant coverages. RPA correctly assigns the adsorption of methane to the hcp (hexagonal close packed) hollow tripod site, matching vibrational spectra, whereas PBE+MBD found another site. Given the high cost of periodic RPA, a high-level: low-level QM:QM (QM = quantum mechanics) hybrid approach is applied using RPA (RPA:PBE(+D)), which has also been tested with several dispersion corrections, with RPA:PBE and RPA:PBE+MBD performing best. This extends the QM:QM hybrid approach to the study of adsorption on metal surfaces, resulting in high accuracy at significantly reduced cost. Finally we test the performance of the low-scaling RPA algorithm of Kresse and co-workers. This algorithm enables the study of larger systems and is applied to the first four n-alkanes (C1-C4) on the Pt(111) surface. Comparison against experiment indicates that RPA offers the best agreement, consistently better than any studied density functional. RPA underbinds slightly but is still found to be the best method for studying adsorption on metal surfaces and is the current benchmark for such systems

    The status of Abbott's Babbler in Borneo

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    We reviewed the occurrence of Abbott's Babbler Trichastoma abbotti on Borneo as a first step towards understanding why this species, which is common in most of its range, is so rare on the island. We were able to find only 21 documented Bornean records, most of which derived from areas of scrub habitat at low altitudes, especially near the coast

    A review of the status and distribution of the Bornean Bristlehead

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    We compiled all documented records of Bornean Bristlehead Pityriasis gymnocephata to determine what is known about the life-history and distribution of this enigmatic species. Pityriasis is a relict cracticid, related to the Australian magpies and butcherbirds. It is a highly social species and widespread throughout Borneo in forests below 1000m elevation, but rarely encountered

    Savings Behavior and Asset Choice of Households in Germany: Evidence from SAVE 2003 and 2005

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    The aim of this study is to answer the following questions: “What are the key qualitative and quantitative facts about household savings in Germany?”, “Why do Germans save?”, and “How do Germans save?” We want to discover what assets households choose when investing their savings. Finally we investigate the factors influencing the households’ decision of whether to invest in stocks. This study unfolds as follows. Section 2 gives a general overview of the SAVE survey by summarizing the existing waves of SAVE and reviewing the questionnaire with a particular focus on the SAVE 2005 survey. In addition, the section checks the data quality with respect to nonresponse problems, the quality of responses, and the representativeness of the survey. Sections 3 and 4 are devoted to the analysis of the SAVE 2003 and 2005 data. The savings behavior of the households interviewed is at the core of Section 3. Section 4 investigates the asset choice behavior with a particular focus on the stockholding decision of households. Section 5 summarizes and concludes

    Hybrid RPA:DFT Approach for Adsorption on Transition Metal Surfaces: Methane and Ethane on Platinum (111)

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    The hybrid QM:QM approach is extended to adsorption on transition metal surfaces. The random phase approximation (RPA) as the high-level method is applied to cluster models and, using the subtractive scheme, embedded in periodic models which are treated with density functional theory (DFT) that is the low-level method. The PBE functional, both without dispersion and augmented with the many-body dispersion (MBD), is employed. Adsorption of methane and ethane on the Pt(111) surface is studied. For methane in a 2 × 2 surface cell, the hybrid RPA:PBE and RPA:PBE+MBD results, −14.3 and −16.0 kJ mol–1, respectively, are in close agreement with the periodic RPA value of −13.8 kJ mol–1 at significantly reduced computational cost (factor of ∌50). For methane and ethane, the RPA:PBE results (−14.3 and −17.8 kJ mol–1, respectively) indicate underbinding relative to energies derived from experimental desorption barriers for relevant loadings (−15.6 ± 1.6 and −27.2 ± 2.9 kJ mol–1, respectively), whereas the hybrid RPA:PBE+MBD results (−16.0 and −24.9 kJ mol–1, respectively) agree with the experiment well within experimental uncertainty limits (deviation of −0.4 ± 1.5 and +2.3 ± 2.9 kJ mol–1, respectively). Finding a cluster that adequately and robustly represents the adsorbate at the bulk surface is important for the success of the RPA-based QM:QM scheme for metals.Norddeutscher Verbund f?r Hoch- und H?chstleistungsrechnen 10.13039/100030685Norddeutscher Verbund f?r Hoch- und H?chstleistungsrechnen 10.13039/100030685Deutsche Forschungsgemeinschaft 10.13039/501100001659Fonds der Chemischen Industrie 10.13039/100018992Peer Reviewe

    Developing emotion abilities and regulation strategies in a sport organization: an action research intervention

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    OBJECTIVES. This study aimed to improve the practice of individuals operating in a sport organization by providing an intervention to develop emotion abilities and strategies. DESIGN. A two-phase action research approach was adopted to facilitate the objective and to assess the intervention's effectiveness. Method: In the first phase of the intervention, 25 individuals fulfilling a range of roles (i.e., board of directors, chief executive officer, heads of performance and development, staff, administrators, national coaches and team managers, club coaches, national talent academy athletes) attended educational workshops over a 6 month period. In the second phase, three pivotal operators (i.e., national managers) received one-to-one coaching for a further 3 months. Data were collected using a range of self-report and performance measures, participant daily diaries, a researcher's log, and social validation interviews. RESULTS. Following social validation procedures the findings suggest that both phases were effective at improving the practice of participants, with significant improvements in regulation strategy use, perceptions of relationship quality, and closeness. However, only participants receiving the extended one-to-one coaching showed improvement in emotional intelligence ability scores. CONCLUSIONS. The findings indicate that short-term generic interventions to promote the use of adaptive emotion regulation strategies may be effective in sport organizations, but the purposive development of emotional intelligence may require more longitudinal and idiographic approaches

    A multi-label, dual-output deep neural network for automated bug triaging

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    Bug tracking enables the monitoring and resolution of issues and bugs within organizations. Bug triaging, or assigning bugs to the owner(s) who will resolve them, is a critical component of this process because there are many incorrect assignments that waste developer time and reduce bug resolution throughput. In this work, we explore the use of a novel two-output deep neural network architecture (Dual DNN) for triaging a bug to both an individual team and developer, simultaneously. Dual DNN leverages this simultaneous prediction by exploiting its own guess of the team classes to aid in developer assignment. A multi-label classification approach is used for each of the two outputs to learn from all interim owners, not just the last one who closed the bug. We make use of a heuristic combination of the interim owners (owner-importance-weighted labeling) which is converted into a probability mass function (pmf). We employ a two-stage learning scheme, whereby the team portion of the model is trained first and then held static to train the team--developer and bug--developer relationships. The scheme employed to encode the team--developer relationships is based on an organizational chart (org chart), which renders the model robust to organizational changes as it can adapt to role changes within an organization. There is an observed average lift (with respect to both team and developer assignment) of 13%-points in 11-fold incremental-learning cross-validation (IL-CV) accuracy for Dual DNN utilizing owner-weighted labels compared with the traditional multi-class classification approach. Furthermore, Dual DNN with owner-weighted labels achieves average 11-fold IL-CV accuracies of 76% (team assignment) and 55% (developer assignment), outperforming reference models by 14%- and 25%-points, respectively, on a proprietary dataset with 236,865 entries.Comment: 8 pages, 2 figures, 9 table

    A Population-Based Study of the Association of Medical Manpower with County Trauma Death Rates in the United States

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    OBJECTIVE: To determine the association between measures of medical manpower available to treat trauma patients and county trauma death rates in the United States. The primary hypothesis was that greater availability of medical manpower to treat trauma injury would be associated with lower trauma death rates. SUMMARY BACKGROUND DATA: When viewed from the standpoint of the number of productive years of life lost, trauma has a greater effect on health care and lost productivity in the United States than any disease. Allocation of health care manpower to treat injuries seems logical, but studies have not been done to determine its efficacy. The effect of medical manpower and hospital resource allocation on the outcome of injury in the United States has not been fully explored or adequately evaluated. METHODS: Data on trauma deaths in the United States were obtained from the National Center for Health Statistics. Data on the number of surgeons and emergency medicine physicians were obtained from the American Hospital Association and the American Medical Association. Data on physicians who have participated in the American College of Surgeons (ACS) Advanced Trauma Life Support Course (ATLS) were obtained from the ACS. Membership information for the American Association for Surgery of Trauma (AAST) was obtained from that organization. Demographic data were obtained from the United States Census Bureau. Multivariate stepwise linear regression and cluster analysis were used to model the county trauma death rates in the United States. The Statistical Analysis System (Cary, NC) for statistical analysis was used. RESULTS: Bivariate and multivariate analyses showed that a variety of medical manpower measures and demographic factors were associated with county trauma death rates in the United States. As in other studies, measures of low population density and high levels of poverty were found to be strongly associated with increased trauma death rates. After accounting for these variables, using multivariate analysis and cluster analysis, an increase in the following medical manpower measures were associated with decreased county trauma death rates: number of board-certified general surgeons, number of board-certified emergency medicine physicians, number of AAST members, and number of ATLS-trained physicians. CONCLUSIONS: This study confirms previous work that showed a strong relation among measures of poverty, rural setting, and increased county trauma death rates. It also found that counties with more board-certified surgeons per capita and with more surgeons with an increased interest (AAST membership) or increased training (ATLS) in trauma care have lower per-capita trauma death rates

    Multi‐century stasis in C3 and C4 grass distributions across the contiguous United States since the industrial revolution

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    AimsUnderstanding the functional response of ecosystems to past global change is crucial to predicting performance in future environments. One sensitive and functionally significant attribute of grassland ecosystems is the percentage of species that use the C4 versus C3 photosynthetic pathway. Grasses using C3 and C4 pathways are expected to have different responses to many aspects of anthropogenic environmental change that have followed the industrial revolution, including increases in temperature and atmospheric CO2, changes to land management and fire regimes, precipitation seasonality, and nitrogen deposition. In spite of dramatic environmental changes over the past 300 years, it is unknown if the C4 grass percentage in grasslands has shifted.LocationContiguous United States of America.MethodsHere, we used stable carbon isotope data (i.e. ή13C) from 30 years of soil samples, as well as herbivore tissues that date to 1739 CE, to reconstruct coarse‐grain C3 and C4 grass composition in North American grassland sites to compare with modern vegetation. We spatially resampled these three datasets to a shared 100‐km grid, allowing comparison of ή13C values at a resolution and extent common for climate model outputs and biogeographical studies.ResultsAt this spatial grain, the bison tissue proxy was superior to the soil proxy because the soils reflect integration of local carbon inputs, whereas bison sample vegetation across landscapes. Bison isotope values indicate that historical grassland photosynthetic‐type composition was similar to modern vegetation.Main conclusionsDespite major environmental change, comparing modern plot vegetation data to three centuries of bison ή13C data revealed that the biogeographical distribution of C3 and C4 grasses has not changed significantly since the 1700s. This is particularly surprising given the expected CO2 fertilization of C3 grasses. Our findings highlight the critical importance of capturing the full range of physiological, ecological and demographical processes in biosphere models predicting future climates and ecosystems.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139065/1/jbi13061.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139065/2/jbi13061_am.pd
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