997 resultados para diffraction efficiency spectrum
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NlmCategory="UNASSIGNED">As opposed to the standard detective quantum efficiency (DQE), effective DQE (eDQE) is a figure of merit that allows comparing the performances of imaging systems in the presence of scatter rejection devices. The geometry of the EOS™ slot-scanning system is such that the detector is self-collimated and rejects scattered radiation. In this study, the EOS system was characterised using the eDQE in imaging conditions similar to those used in clinical practice: with phantoms of different widths placed in the X-ray beam, for various incident air kerma and tube voltages corresponding to the phantom thickness. Scatter fractions in EOS images were extremely low, around 2 % for all configurations. Maximum eDQE values spanned 9-14.8 % for a large range of air kerma at the detector plane from 0.01 to 1.34 µGy. These figures were obtained with non-optimised EOS setting but still over-performed most of the maximum eDQEs recently assessed for various computed radiology and digital radiology systems with antiscatter grids.
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Mammalian physiology and behavior follow daily rhythms that are orchestrated by endogenous timekeepers known as circadian clocks. Rhythms in transcription are considered the main mechanism to engender rhythmic gene expression, but important roles for posttranscriptional mechanisms have recently emerged as well (reviewed in Lim and Allada (2013) [1]). We have recently reported on the use of ribosome profiling (RPF-seq), a method based on the high-throughput sequencing of ribosome protected mRNA fragments, to explore the temporal regulation of translation efficiency (Janich et al., 2015 [2]). Through the comparison of around-the-clock RPF-seq and matching RNA-seq data we were able to identify 150 genes, involved in ribosome biogenesis, iron metabolism and other pathways, whose rhythmicity is generated entirely at the level of protein synthesis. The temporal transcriptome and translatome data sets from this study have been deposited in NCBI's Gene Expression Omnibus under the accession number GSE67305. Here we provide additional information on the experimental setup and on important optimization steps pertaining to the ribosome profiling technique in mouse liver and to data analysis.
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The bridged sulphate complex [Pd2 (C²,dmba) (µ-SO4) (SO2)2] has been obtained by reacting a saturated solution of SO2 in methanol and the cyclometallated compound [Pd(C²,N-dmba)(µ-N3)] 2; (dmba = N,N-dimethylbenzylamine), at room temperature for 24 h. Reaction product was characterized by elemental analysis, NMR comprising 13C{¹H} and ¹H nuclei and I.R. spectrum's measurements. Thermal behavior has been investigated and residual products identified by X-ray powder diffraction.
Role of the environmental spectrum in the decoherence and dissipation of a quantum Brownian particle
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Multicomponent ( Al2O3, CaO, SiO2, MgO) calcium aluminate-based glasses containing Nd3+ were prepared in order to evaluate their possibilities as laser host materials. The refractive index, UV-visible-near IR absorption spectrum, IR and visible luminescence spectra, and fluorescence decay time were measured. Judd-Ofelt model was used to obtain experimental intensity parameters ( omega2, omega4 and omega6), emission cross-section, radiative lifetimes, emission branching ratios and quantum efficiency.
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Hamstring muscle injuries and tendon disorders are common, especially in sports. They can be severe and difficult to treat, often resulting in impaired athletic performance and long rehabilitation times. Previous studies considering treatment of these problems are scarce. The current study was designed to investigate the effect of surgery on different types of hamstring muscle injuries and on proximal hamstring tendinopathy. In addition, we wanted to study the typical histopathological findings relating to proximal hamstring tendinopathy. In the study of complete (all three muscles torn) proximal hamstring avulsions (41 patients), our results showed that early operative treatment gives significantly better results than late surgery, and is therefore recommended. Despite this, considerable improvement of symptoms could also be achieved in chronic cases. In the study of partial (one or two muscles torn) proximal hamstring tears (47 patients), we observed that these injuries can cause significant functional deficit and impaired performance in athletes. The main finding was that after surgical repair most of the patients were able to return to their pre-injury level of sports. In the study of distal hamstring tears (18 patients), the results showed that surgical treatment had a good effect in the majority of these cases. In proximal hamstring tendinopathy, the main problem is pain which limits sports. In this study (90 patients), we found that after unsuccessful conservative treatment, surgery was a good treatment option resulting in full return to sports in most cases. In tendinopathic hamstring tendons, the morphological changes of tendinosis were largely identical to those previously described in other common (e.g. Achilles and patellar) tendinopathies. In chronic proximal hamstring avulsions, and also in reoperations, a large defect between distally retracted tendons and the ischial tuberosity may occasionally prevent anatomic reinsertion. We have described a reconstruction method using fascia lata autograft augmentation to be used in these most challenging repairs. This technique was utilized in the treatment of five patients, with encouraging results.
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Antimicrobial peptides offer a new class of therapeutic agents to which bacteria may not be able todevelop genetic resistance, since their main activity is in the lipid component of the bacterial cell mem-brane. We have developed a series of synthetic cationic cyclic lipopeptides based on natural polymyxin,and in this work we explore the interaction of sp-85, an analog that contains a C12 fatty acid at theN-terminus and two residues of arginine. This analog has been selected from its broad spectrum antibac-terial activity in the micromolar range, and it has a disruptive action on the cytoplasmic membrane ofbacteria, as demonstrated by TEM. In order to obtain information on the interaction of this analog withmembrane lipids, we have obtained thermodynamic parameters from mixed monolayers prepared withPOPG and POPE/POPG (molar ratio 6:4), as models of Gram positive and Gram negative bacteria, respec-tively. LangmuirBlodgett films have been extracted on glass plates and observed by confocal microscopy,and images are consistent with a strong destabilizing effect on the membrane organization induced bysp-85. The effect of sp-85 on the membrane is confirmed with unilamelar lipid vesicles of the same com-position, where biophysical experiments based on fluorescence are indicative of membrane fusion andpermeabilization starting at very low concentrations of peptide and only if anionic lipids are present.Overall, results described here provide strong evidence that the mode of action of sp-85 is the alterationof the bacterial membrane permeability barrier.
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The main purpose of this thesis is to measure and evaluate how accurately the current energy saving calculation in ABB’s new variable speed drive ACS850 works. The main topic of this thesis is energy-efficiency parameters. At the beginning of this thesis centrifugal pump, squirrel cage motor and variable speed drive, including some equations related to them, are being introduced. Also methods of throttling control and variable speed drive control of centrifugal pumps are being introduced. These subjects are introduced because the energy saving calculation in ACS850 is related to the centrifugal pumps usually driven by squirrel cage motors. The theory also includes short section about specific energy of pumping. Before measurements the current energy saving calculation of ACS850 is being introduced and analyzed. The measurements part includes introduction of measuring equipment, measurement results, summary and analysis of the measurements. At the end of this thesis a proposal for an improvement to the current energy saving calculation is being introduced and few proposals are made for new energy-efficiency parameters, which could be added to variable speed drives. At the end are also thoughts
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The role of transport in the economy is twofold. As a sector of economic activity it contributes to a share of national income. On the other hand, improvements in transport infrastructure create room for accelerated economic growth. As a means to support railways as a safe and environmentally friendly transportation mode, the EU legislation has required the opening of domestic railway freight for competition from beginning of year 2007. The importance of railways as a mode of transport has been great in Finland, as a larger share of freight has been carried on rails than in Europe on average. In this thesis it is claimed that the efficiency of goods transport can be enhanced by service specific investments. Furthermore, it is stressed that simulation can and should be used to evaluate the cost-efficiency of transport systems on operational level, as well as to assess transportation infrastructure investments. In all the studied cases notable efficiency improvements were found. For example in distribution, home delivery of groceries can be almost twice as cost efficient as the current practice of visiting the store. The majority of the cases concentrated on railway freight. In timber transportation, the item with the largest annual transport volume in domestic railway freight in Finland, the transportation cost could be reduced most substantially. Also in international timber procurement, the utilization of railway wagons could be improved by combining complementary flows. The efficiency improvements also have positive environmental effects; a large part of road transit could be moved to rails annually. If impacts of freight transport are included in cost-benefit analysis of railway investments, up to 50 % increase in the net benefits of the evaluated alternatives can be experienced, avoiding a possible inbuilt bias in the assessment framework, and thus increasing the efficiency of national investments in transportation infrastructure. Transportation systems are a typical example of complex real world systems that cannot be analysed realistically by analytical methods, whereas simulation allows inclusion of dynamics and the level of detail required. Regarding simulation as a viable tool for assessing the efficiency of transportation systems finds support also in the international survey conducted for railway freight operators; operators use operations research methods widely for planning purposes, while simulation is applied only by the larger operators.
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Coherent anti-Stokes Raman scattering (CARS) microscopy is rapidly developing into a unique microscopic tool in biophysics, biology and the material sciences. The nonlinear nature of CARS spectroscopy complicates the analysis of the received spectra. There were developed mathematical methods for signal processing and for calculations spectra. Fourier self-deconvolution is a special high pass FFT filter which synthetically narrows the effective trace bandwidth features. As Fourier self-deconvolution can effectively reduce the noise, which may be at a higher spatial frequency than the peaks, without losing peak resolution. The idea of the work is to experiment the possibility of using wavelet decomposition in spectroscopic for background and noise removal, and Fourier transformation for linenarrowing.
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Observational and theoretical studies point to microquasars (MQs) as possible counterparts of a significant fraction of the unidentified gamma-ray sources detected so far. At present, a proper scenario to explain the emission beyond soft X-rays from these objects is not known, nor what the precise connection is between the radio and the high-energy radiation. We develop a new model where the MQ jet is dynamically dominated by cold protons and radiatively dominated by relativistic leptons. The matter content and power of the jet are both related with the accretion process. The magnetic field is assumed to be close to equipartition, although it is attached to and dominated by the jet matter. For the relativistic particles in the jet, their maximum energy depends on both the acceleration efficiency and the energy losses. The model takes into account the interaction of the relativistic jet particles with the magnetic field and all the photon and matter fields. Such interaction produces significant amounts of radiation from radio to very high energies through synchrotron, relativistic Bremsstrahlung, and inverse Compton (IC) processes. Variability of the emission produced by changes in the accretion process (e.g. via orbital eccentricity) is also expected. The effects of the gamma-ray absorption by the external photon fields on the gamma-ray spectrum have been taken into account, revealing clear spectral features that might be observed. This model is consistent to the accretion scenario, energy conservation laws, and current observational knowledge, and can provide deeper physical information of the source when tested against multiwavelength data.
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Electron scattering on a thin layer where the potential depends self-consistently on the wave function has been studied. When the amplitude of the incident wave exceeds a certain threshold, a soliton-shaped brightening (darkening) appears on the layer causing diffraction of the wave. Thus the spontaneously formed transverse pattern can be viewed as a self-induced nonlinear quantum screen. Attractive or repulsive nonlinearities result in different phase shifts of the wave function on the screen, which give rise to quite different diffraction patterns. Among others, the nonlinearity can cause self-focusing of the incident wave into a beam, splitting in two "beams," single or double traces with suppressed reflection or transmission, etc.
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This paper examines the extent to which innovative Spanish firms pursue improvements in energy efficiency (EE) as an objective of innovation. The increase in energy consumption and its impact on greenhouse gas emissions justifies the greater attention being paid to energy efficiency and especially to industrial EE. The ability of manufacturing companies to innovate and improve their EE has a substantial influence on attaining objectives regarding climate change mitigation. Despite the effort to design more efficient energy policies, the EE determinants in manufacturing firms have been little studied in the empirical literature. From an exhaustive sample of Spanish manufacturing firms and using a logit model, we examine the energy efficiency determinants for those firms that have innovated. To carry out the econometric analysis, we use panel data from the Community Innovation Survey for the period 2008‐2011. Our empirical results underline the role of size among the characteristics of firms that facilitate energy efficiency innovation. Regarding company behaviour, firms that consider the reduction of environmental impacts to be an important objective of innovation and that have introduced organisational innovations are more likely to innovate with the objective of increasing energy efficiency. Keywords: energy efficiency, corporate targets, innovation, Community Innovation Survey. JEL Classification: Q40, Q55, O31
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Traditionally, school efficiency has been measured as a function of educational production. In the last two decades, however, studies in the economics of education have indicated that more is required to improve school efficiency: researchers must explore how significant changes in school organization affect the performance of at-risk students. In this paper we introduce Henry Levin’s adoption of the X-efficiency approach to education and we describe the efficient and cost-effective characteristics of one Learning Communities Project School that significantly improved its student outcomes and enrollment numbersand reduced its absenteeism rate to zero. The organizational change that facilitatedthese improvements defined specific issues to address. Students’ school success became the focus of the school project, which also offered specific incentives, selected teachers, involved parents and community members in decisions, and used the most efficient technologies and methods. This case analysis reveals new two elements—family training and community involvement—that were not explicit parts of Levin’s adaptation. The case of the Antonio Machado Public School should attract the attention of both social scientists and policy makers
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In the context of autonomous sensors powered by small-size photovoltaic (PV) panels, this work analyses how the efficiency of DC/DC-converter-based power processing circuits can be improved by an appropriate selection of the inductor current that transfers the energy from the PV panel to a storage unit. Each component of power losses (fixed, conduction and switching losses) involved in the DC/DC converter specifically depends on the average inductor current so that there is an optimal value of this current that causes minimal losses and, hence, maximum efficiency. Such an idea has been tested experimentally using two commercial DC/DC converters whose average inductor current is adjustable. Experimental results show that the efficiency can be improved up to 12% by selecting an optimal value of that current, which is around 300-350 mA for such DC/DC converters.