1,111 research outputs found

    Construction Cost Sensitivity of a Lignocellulosic Ethanol Biorefinery

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    The technology has been developed to convert feedstock with cellulose content into ethanol. However, ethanol produced from cellulosic feedstock is the same as ethanol distilled from grain. The objective of research is to determine the price per gallon of ethanol needed so that producing lignocellulosic based ethanol become economically feasible.Environmental Economics and Policy, Production Economics,

    Relativistic ponderomotive force, uphill acceleration, and transition to chaos

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    Starting from a covariant cycle-averaged Lagrangian the relativistic oscillation center equation of motion of a point charge is deduced and analytical formulae for the ponderomotive force in a travelling wave of arbitrary strength are presented. It is further shown that the ponderomotive forces for transverse and longitudinal waves are different; in the latter, uphill acceleration can occur. In a standing wave there exists a threshold intensity above which, owing to transition to chaos, the secular motion can no longer be described by a regular ponderomotive force. PACS number(s): 52.20.Dq,05.45.+b,52.35.Mw,52.60.+hComment: 8 pages, RevTeX, 3 figures in PostScript, see also http://www.physik.th-darmstadt.de/tqe

    On the Behavior of Hexane on Graphite at Near-Monolayer Densities

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    We present the results of molecular dynamics (MD) studies of hexane physisorbed onto graphite for eight coverages in the range 0.875ρ1.050.875 \le \rho \le 1.05 (in units of monolayers). At low temperatures the adsorbate molecules form a uniaxially incommensurate herringbone (UI-HB) solid. At high coverages the solid consists of adsorbate molecules that are primarily rolled on their side perpen-dicular to the surface of the substrate. As the coverage is decreased, the amount of molecular rolling diminishes until ρ\rho = 0.933 where it disappears (molecules become primarily parallel to the surface). If the density is decreased enough, vacancies appear. As the temperature is increased we observe a three-phase regime for ρ>0.933\rho > 0.933 (with an orientationally ordered nematic mesophase), for lower coverages the system melts directly to the disordered (and isotropic) liquid phase. The solid-nematic transition temperature is very sensitive to coverage whereas the melting temperature is quite insensitive to it, except for at low coverages where increased in-plane space and ultimately vacancies soften the solid phase and lower the melting temperature. Our results signal the importance of molecular rolling and tilting (which result from an the competition between molecule-molecule and molecule-substrate interactions) for the formation of the intermediate phase, while the insensitivity of the system's melting temperature to changing density is understood in terms of in-plane space occupation through rolling. Comparisons and contrasts with experimental results are discussed

    Thoroughness of Mediastinal Staging in Stage IIIA Non-small Cell Lung Cancer

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    IntroductionGuidelines recommend that patients with clinical stage IIIA non-small cell lung cancer (NSCLC) undergo histologic confirmation of pathologic lymph nodes. Studies have suggested that invasive mediastinal staging is underutilized, although practice patterns have not been rigorously evaluated.MethodsWe used the Surveillance, Epidemiology, and End Results-Medicare database to identify patients with stage IIIA NSCLC diagnosed from 1998 through 2005. Invasive staging and use of positron emission tomography (PET) scanning were assessed using Medicare claims. Multivariable logistic regression was used to identify patient characteristics associated with use of invasive staging.ResultsOf 7583 stage IIIA NSCLC patients, 1678 (22%) underwent invasive staging. Patients who received curative intent cancer treatment were more likely to undergo invasive staging than patients who did not receive cancer-specific therapy (30% versus 9.8%, adjusted odds ratio, 3.31; 95% confidence interval, 2.78–3.95). The oldest patients (age, 85–94 years) were less likely to receive invasive staging than the youngest (age, 67–69 years; 27.6% versus 11.9%; odds ratio, 0.46; 95% confidence interval, 0.34–0.61). Sex, marital status, income, and race were not associated with the use of the invasive staging. The use of invasive staging was stable throughout the study period, despite an increase in the use of PET scanning from less than 10% of patients before 2000 to almost 70% in 2005.ConclusionNearly 80% of Medicare beneficiaries with stage IIIA NSCLC do not receive guideline adherent mediastinal staging; this failure cannot be entirely explained by patient factors or a reliance on PET imaging. Incentives to encourage use of invasive staging may improve care

    Small denominators, frequency operators, and Lie transforms for nearly integrable quantum spin systems

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    Based on the previously proposed notions of action operators and of quantum integrability, frequency operators are introduced in a fully quantum-mechanical setting. They are conceptually useful because another formulation can be given to unitary perturbation theory. When worked out for quantum spin systems, this variant is found to be formally equivalent to canonical perturbation theory applied to nearly integrable systems consisting of classical spins. In particular, it becomes possible to locate the quantum-mechanical operator-valued equivalent of the frequency denominators that may cause divergence of the classical perturbation series. The results that are established here link the concept of quantum-mechanical integrability to a technical question, namely, the behavior of specific perturbation series

    Making Drug Approval Decisions in the Face of Uncertainty:Cumulative Evidence versus Value of Information

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    Background: The COVID-19 pandemic underscored the criticality and complexity of decision making for novel treatment approval and further research. Our study aims to assess potential decision-making methodologies, an evaluation vital for refining future public health crisis responses. Methods: We compared 4 decision-making approaches to drug approval and research: the Food and Drug Administration’s policy decisions, cumulative meta-analysis, a prospective value-of-information (VOI) approach (using information available at the time of decision), and a reference standard (retrospective VOI analysis using information available in hindsight). Possible decisions were to reject, accept, provide emergency use authorization, or allow access to new therapies only in research settings. We used monoclonal antibodies provided to hospitalized COVID-19 patients as a case study, examining the evidence from September 2020 to December 2021 and focusing on each method’s capacity to optimize health outcomes and resource allocation. Results: Our findings indicate a notable discrepancy between policy decisions and the reference standard retrospective VOI approach with expected losses up to 269billionUSD,suggestingsuboptimalresourceuseduringthewaitforemergencyuseauthorization.Relyingsolelyoncumulativemetaanalysisfordecisionmakingresultsinthelargestexpectedloss,whilethepolicyapproachshowedalossupto269 billion USD, suggesting suboptimal resource use during the wait for emergency use authorization. Relying solely on cumulative meta-analysis for decision making results in the largest expected loss, while the policy approach showed a loss up to 16 billion and the prospective VOI approach presented the least loss (up to $2 billion). Conclusion: Our research suggests that incorporating VOI analysis may be particularly useful for research prioritization and treatment implementation decisions during pandemics. While the prospective VOI approach was favored in this case study, further studies should validate the ideal decision-making method across various contexts. This study’s findings not only enhance our understanding of decision-making strategies during a health crisis but also provide a potential framework for future pandemic responses. This study reviews discrepancies between a reference standard (retrospective VOI, using hindsight information) and 3 conceivable real-time approaches to research-treatment decisions during a pandemic, suggesting suboptimal use of resources. Of all prospective decision-making approaches considered, VOI closely mirrored the reference standard, yielding the least expected value loss across our study timeline. This study illustrates the possible benefit of VOI results and the need for evidence accumulation accompanied by modeling in health technology assessment for emerging therapies.</p
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