1,310 research outputs found
Surface-hopping dynamics and decoherence with quantum equilibrium structure
In open quantum systems decoherence occurs through interaction of a quantum
subsystem with its environment. The computation of expectation values requires
a knowledge of the quantum dynamics of operators and sampling from initial
states of the density matrix describing the subsystem and bath. We consider
situations where the quantum evolution can be approximated by quantum-classical
Liouville dynamics and examine the circumstances under which the evolution can
be reduced to surface-hopping dynamics, where the evolution consists of
trajectory segments evolving exclusively on single adiabatic surfaces, with
probabilistic hops between these surfaces. The justification for the reduction
depends on the validity of a Markovian approximation on a bath averaged memory
kernel that accounts for quantum coherence in the system. We show that such a
reduction is often possible when initial sampling is from either the quantum or
classical bath initial distributions. If the average is taken only over the
quantum dispersion that broadens the classical distribution, then such a
reduction is not always possible.Comment: 11, pages, 8 figure
Implementasi Algoritma Fuzzy C - Means Clustering Dan Simple Additive Weighting Dalam Pemberian Bantuan Program Peningkatan Kualitas Kawasan Permukiman
Permasalahan kemiskinan di Indonesia sudah sangat mendesak untuk ditangani, khususnya pada wilayah perkotaan. Kementrian PUPR menyatakan salah satu kondisi fisik masyarakat miskin adalah tidak memiliki akses sarana dan prasarana dasar lingkungan yang memadai dengan kualitas permukiman yang jauh di bawah standar kelayakan. Untuk mengatasi permasalahan tersebut, pemerintah membentuk Program Peningkatan Kualitas Kawasan Permukiman (P2KKP) dengan harapan apabila kualitas kawasan permukiman dapat ditingkatkan maka masalah kemiskinan juga dapat terselesaikan. Di Kota Bengkulu, P2KKP mengelola data 14 indikator kondisi permukiman dari 1.183 RT yang tergabung dalam 67 Kelurahan dan 9 Kecamatan. 14 indikator tersebut dijadikan acuan untuk melakukan pengelompokkan RT berdasarkan kondisi permukimannya kemudian malakukan perangkingan untuk mengetahui RT-RT mana saja yang layak untuk diberikan bantuan. Dalam penelitian ini, dibangun sebuah sistem berbasis website yang dapat membantu proses penginputan data kondisi permukiman, melakukan pengelompokkan dan perangkingan serta publikasi informasi kepada masyarakat. Sistem ini akan mengimplementasikan algoritma fuzzy c-means clustering untuk proses pengelompokkan dan simple additive weighting untuk proses perangkinga
Using a terrestrial ecosystem survey to estimate the historical density of ponderosa pine trees
Maps of historical tree densities for project areas and landscapes may be useful for a variety of management purposes such as determining site capabilities and planning forest thinning treatments. We used the U.S. Forest Service Region 3 terrestrial ecosystem survey in a novel way to determine if the ecosystem classification is a useful a guide for estimating historical (1880) ponderosa pine (Pinus ponderosa) tree densities on a northern Arizona landscape. Based on sampling 53 sites spanning 9 ecosystem types, we grouped the types into low and high density categories. Tree density was less than 24/ acre on 91 percent (21 of 23) of sites in cinder, dry limestone, and clay basalt ecosystems. In contrast, 70 percent (21 of 30) of sites that contained densities exceeding 24 trees/acre were in basalt, mixed igneous, and moist limestone ecosystems
NorthStar, a support tool for the design and evaluation of quality improvement interventions in healthcare
Background: The Research-Based Education and Quality Improvement (ReBEQI) European partnership aims to establish a framework and provide practical tools for the selection, implementation, and evaluation of quality improvement (QI) interventions. We describe the development and preliminary evaluation of the software tool NorthStar, a major product of the ReBEQI project. Methods: We focused the content of NorthStar on the design and evaluation of QI interventions. A lead individual from the ReBEQI group drafted each section, and at least two other group members reviewed it. The content is based on published literature, as well as material developed by the ReBEQI group. We developed the software in both a Microsoft Windows HTML help system version and a web-based version. In a preliminary evaluation, we surveyed 33 potential users about the acceptability and perceived utility of NorthStar. Results: NorthStar consists of 18 sections covering the design and evaluation of QI interventions. The major focus of the intervention design sections is on how to identify determinants of practice (factors affecting practice patterns), while the major focus of the intervention evaluation sections is on how to design a cluster randomised trial. The two versions of the software can be transferred by email or CD, and are available for download from the internet. The software offers easy navigation and various functions to access the content. Potential users (55% response rate) reported above-moderate levels of confidence in carrying out QI research related tasks if using NorthStar, particularly when developing a protocol for a cluster randomised trial Conclusion: NorthStar is an integrated, accessible, practical, and acceptable tool to assist developers and evaluators of QI interventions
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The effects of diesel exhaust pollution on floral volatiles and the consequences for honey bee olfaction
There is growing evidence of a substantial decline in pollinators within Europe and North America, most likely caused by multiple factors such as diseases, poor nutrition, habitat loss, insecticides, and environmental pollution. Diesel exhaust could be a contributing factor to this decline, since we found that diesel exhaust rapidly degrades floral volatiles, which honey bees require for flower recognition. In this study, we exposed eight of the most common floral volatiles to diesel exhaust in order to investigate whether it can affect volatile mediated plant-pollinator interaction. Exposure to diesel exhaust altered the blend of common flower volatiles significantly: myrcene was considerably reduced, β-ocimene became undetectable, and β-caryophyllene was transformed into its cis-isomer isocaryophyllene. Proboscis extension response (PER) assays showed that the alterations of the blend reduced the ability of honey bees to recognize it. The chemically reactive nitrogen oxides fraction of diesel exhaust gas was identified as capable of causing degradation of floral volatiles
Thin-Film Metamaterials called Sculptured Thin Films
Morphology and performance are conjointed attributes of metamaterials, of
which sculptured thin films (STFs) are examples. STFs are assemblies of
nanowires that can be fabricated from many different materials, typically via
physical vapor deposition onto rotating substrates. The curvilinear--nanowire
morphology of STFs is determined by the substrate motions during fabrication.
The optical properties, especially, can be tailored by varying the morphology
of STFs. In many cases prototype devices have been fabricated for various
optical, thermal, chemical, and biological applications.Comment: to be published in Proc. ICTP School on Metamaterials (Augsut 2009,
Sibiu, Romania
The development of a theory-based intervention to promote appropriate disclosure of a diagnosis of dementia
Background: The development and description of interventions to change professional practice are often limited by the lack of an explicit theoretical and empirical basis. We set out to develop an intervention to promote appropriate disclosure of a diagnosis of dementia based on theoretical and empirical work. Methods: We identified three key disclosure behaviours: finding out what the patient already knows or suspects about their diagnosis; using the actual words 'dementia' or 'Alzheimer's disease' when talking to the patient; and exploring what the diagnosis means to the patient. We conducted a questionnaire survey of older peoples' mental health teams (MHTs) based upon theoretical constructs from the Theory of Planned Behaviour (TPB) and Social Cognitive Theory (SCT) and used the findings to identify factors that predicted mental health professionals' intentions to perform each behaviour. We selected behaviour change techniques likely to alter these factors. Results: The change techniques selected were: persuasive communication to target subjective norm; behavioural modelling and graded tasks to target self-efficacy; persuasive communication to target attitude towards the use of explicit terminology when talking to the patient; and behavioural modelling by MHTs to target perceived behavioural control for finding out what the patient already knows or suspects and exploring what the diagnosis means to the patient. We operationalised these behaviour change techniques using an interactive 'pen and paper' intervention designed to increase intentions to perform the three target behaviours. Conclusion : It is feasible to develop an intervention to change professional behaviour based upon theoretical models, empirical data and evidence based behaviour change techniques. The next step is to evaluate the effect of such an intervention on behavioural intention. We argue that this approach to development and reporting of interventions will contribute to the science of implementation by providing replicable interventions that illuminate the principles and processes underlying change.This project is funded by UK Medical Research Council, Grant reference number G0300999. Jeremy Grimshaw holds a Canada Research Chair in Health Knowledge Transfer and Uptake. Jill Francis is funded by the Chief Scientist Office of the Scottish Government Health Directorate. The views expressed in this study are those of the authors
Identification of crop cultivars with consistently high lignocellulosic sugar release requires the use of appropriate statistical design and modelling
Background In this study, a multi-parent population of barley cultivars was grown in the field for two consecutive years and then straw saccharification (sugar release by enzymes) was subsequently analysed in the laboratory to identify the cultivars with the highest consistent sugar yield. This experiment was used to assess the benefit of accounting for both the multi-phase and multi-environment aspects of large-scale phenotyping experiments with field-grown germplasm through sound statistical design and analysis. Results Complementary designs at both the field and laboratory phases of the experiment ensured that non-genetic sources of variation could be separated from the genetic variation of cultivars, which was the main target of the study. The field phase included biological replication and plot randomisation. The laboratory phase employed re-randomisation and technical replication of samples within a batch, with a subset of cultivars chosen as duplicates that were randomly allocated across batches. The resulting data was analysed using a linear mixed model that incorporated field and laboratory variation and a cultivar by trial interaction, and ensured that the cultivar means were more accurately represented than if the non-genetic variation was ignored. The heritability detected was more than doubled in each year of the trial by accounting for the non-genetic variation in the analysis, clearly showing the benefit of this design and approach. Conclusions The importance of accounting for both field and laboratory variation, as well as the cultivar by trial interaction, by fitting a single statistical model (multi-environment trial, MET, model), was evidenced by the changes in list of the top 40 cultivars showing the highest sugar yields. Failure to account for this interaction resulted in only eight cultivars that were consistently in the top 40 in different years. The correspondence between the rankings of cultivars was much higher at 25 in the MET model. This approach is suited to any multi-phase and multi-environment population-based genetic experiment
Exporting Cigarettes: Do Profits Trump Ethics and International Law?
In recent years, United States cigarette manufacturers have focused their efforts on foreign markets, especially Asia, Eastern Europe, and Third World states. This Note examines the impetus behind the manufacturers\u27 strategy, as well as the ethical and legal conflicts it creates.
The increase in United States cigarette exports results from a decline in the United States market, favorable market conditions abroad, and United States legislation that encourages foreign trade. While cigarette manufacturers point to the positive impact tobacco has on the United States economy, others argue that increased exportation inevitably will result in catastrophic health consequences worldwide. This Note explores the various areas of international law that potentially impose a duty on the United States to restrict its export of cigarettes. The author recommends several changes that would reconcile the domestic benefits of cigarette exportation with the individual harm incurred abroad and the potential repercussions for violating international law
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