Solar-Sail Navigation: Estimation of Force, Moments, and Optical Parameters

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77367/1/AIAA-24340-772.pd

Radionuclide Determination In Surface Water Samples By Inductively Coupled Plasma With Sector Field Mass Spectrometry (ICP-SFMS)

The determination of naturally occurring radionuclides in the environment by inductively coupled plasma mass spectrometry of high resolution (ICP-SFMS) has gained recognition over the last fifteen years, relative to the radiometric techniques, as the result of improvement in instrumental performance, sample introduction equipment and sample preparation. With the increase in instrumental sensitivity, it is now possible to measure ultratrace levels of many radioisotopes.The aim of this work was to determined the natural radionuclides (232Th, 234U, 235U and 238U) in surface water using Inductively Coupled Plasma-Sector Field Mass Spectrometry (ICP-SFMS). The samples were sampling from Lerma river, State of Mexico at february to april 2015. The process of treatment of sample consisted in perform an acid digestion according to the 3015A USEPA method followed of the direct measurement in ICP-SFMS. Results obtained were: a) identify the presence of 232Th, 234U, 235U and 238U isotopes in water, b) isotopic ratios were for 234U/238U=1.133 ± 0.016. ICP-SFMS has gained popularity in the field of radiochemistry, particularly as a method of detection for long lived-actinides

Potential effects of optical solar sail degredation on trajectory design

The optical properties of the thin metalized polymer films that are projected for solar sails are assumed to be affected by the erosive effects of the space environment. Their degradation behavior in the real space environment, however, is to a considerable degree indefinite, because initial ground test results are controversial and relevant inspace tests have not been made so far. The standard optical solar sail models that are currently used for trajectory design do not take optical degradation into account, hence its potential effects on trajectory design have not been investigated so far. Nevertheless, optical degradation is important for high-fidelity solar sail mission design, because it decreases both the magnitude of the solar radiation pressure force acting on the sail and also the sail control authority. Therefore, we propose a simple parametric optical solar sail degradation model that describes the variation of the sail film's optical coefficients with time, depending on the sail film's environmental history, i.e., the radiation dose. The primary intention of our model is not to describe the exact behavior of specific film-coating combinations in the real space environment, but to provide a more general parametric framework for describing the general optical degradation behavior of solar sails. Using our model, the effects of different optical degradation behaviors on trajectory design are investigated for various exemplary missions

Organizaciones Agrarias y Cooperativas: Transformaciones en trabajo, producción, y acceso a la tierra en Misiones. 16H351

Las actividades agropecuarias en Misiones, vienen sufriendo profundas transformaciones que impactan de manera diferencial sobre los trabajadores y sobre los productores agrarios, pero también en el proceso manufacturero y de comercialización. Con el objetivo de identificar y analizar éstas transformaciones recientes, intentaremos generar conocimiento sobre cambios productivos y en la organización del trabajo en encadenamientos agroindustriales del té y la yerba mate, relevar las estrategias económicas de las cooperativas agroindustriales, identificando sus particularidades respecto a la organización del trabajo, a las modalidades de incorporación de tecnologías y normas de calidad, y en relación con las políticas públicas. También investigaremos la incidencia de organizaciones de productores agrarios sobre los cambios en la implementación de políticas agropecuarias, en especial respecto a la producción, comercialización de alimentos y acceso a la tierra. Considerando las interacciones complejas en las transformaciones en curso, al mismo tiempo las limitaciones contextuales y las estrategias de los actores, exploraremos canales de circulación de insumos y de productos, mecanismos de fijación de precios, para analizar relaciones económicas y de poder, así como transferencias entre los distintos sectores. Desde una perspectiva metodológica cualitativa, tomaremos algunas experiencias de producción y comercialización, por parte de pequeños productores en forma asociativa, como referencia empírica para reflexionar sobre las posibilidades y dificultades de las organizaciones agrarias

Contemporary Clinical and Molecular Epidemiology of Vancomycin-Resistant Enterococcal Bacteremia: A Prospective Multicenter Cohort Study (VENOUS I)

Background Vancomycin-resistant enterococci (VRE) are major therapeutic challenges. Prospective contemporary data characterizing the clinical and molecular epidemiology of VRE bloodstream infections (BSIs) are lacking. Methods The Vancomycin-Resistant Enterococcal BSI Outcomes Study (VENOUS I) is a prospective observational cohort of adult patients with enterococcal BSI in 11 US hospitals. We included patients with Enterococcus faecalis or Enterococcus faecium BSI with >= 1 follow-up blood culture(s) within 7 days and availability of isolate(s) for further characterization. The primary study outcome was in-hospital mortality. Secondary outcomes were mortality at days 4, 7, 10, 12, and 15 after index blood culture. A desirability of outcome ranking was constructed to assess the association of vancomycin resistance with outcomes. All index isolates were subjected to whole genome sequencing. Results Forty-two of 232 (18%) patients died in hospital and 39 (17%) exhibited microbiological failure (lack of clearance in the first 4 days). Neutropenia (hazard ratio [HR], 3.13), microbiological failure (HR, 2.4), VRE BSI (HR, 2.13), use of urinary catheter (HR, 1.85), and Pitt BSI score >= 2 (HR, 1.83) were significant predictors of in-hospital mortality. Microbiological failure was the strongest predictor of in-hospital mortality in patients with E faecium bacteremia (HR, 5.03). The impact of vancomycin resistance on mortality in our cohort changed throughout the course of hospitalization. Enterococcus faecalis sequence type 6 was a predominant multidrug-resistant lineage, whereas a heterogeneous genomic population of E faecium was identified. Conclusions Failure of early eradication of VRE from the bloodstream is a major factor associated with poor outcomes. Failure to eradicate enterococci from the bloodstream in the first 4 days after the index blood culture was the most consistent factor associated with increased risk of mortality. The association of vancomycin resistance with mortality changed throughout the course of the hospitalization

Enhancing quantum efficiency of thin-film silicon solar cells by Pareto optimality

We present a composite design methodology for the simulation and optimization of the solar cell performance. Our method is based on the synergy of different computational techniques and it is especially designed for the thin-film cell technology. In particular, we aim to efficiently simulate light trapping and plasmonic effects to enhance the light harvesting of the cell. The methodology is based on the sequential application of a hierarchy of approaches: (a) full Maxwell simulations are applied to derive the photon’s scattering probability in systems presenting textured interfaces; (b) calibrated Photonic Monte Carlo is used in junction with the scattering matrices method to evaluate coherent and scattered photon absorption in the full cell architectures; (c) the results of these advanced optical simulations are used as the pair generation terms in model implemented in an effective Technology Computer Aided Design tool for the derivation of the cell performance; (d) the models are investigated by qualitative and quantitative sensitivity analysis algorithms, to evaluate the importance of the design parameters considered on the models output and to get a first order descriptions of the objective space; (e) sensitivity analysis results are used to guide and simplify the optimization of the model achieved through both Single Objective Optimization (in order to fully maximize devices efficiency) and Multi Objective Optimization (in order to balance efficiency and cost); (f) Local, Global and “Glocal” robustness of optimal solutions found by the optimization algorithms are statistically evaluated; (g) data-based Identifiability Analysis is used to study the relationship between parameters. The results obtained show a noteworthy improvement with respect to the quantum efficiency of the reference cell demonstrating that the methodology presented is suitable for effective optimization of solar cell devices

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV

A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse momentum, using a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected particle and one or two jets

Search for anomalous t t-bar production in the highly-boosted all-hadronic final state

A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version includes a minor typo correction that will be submitted as an erratu