847 resultados para ponderomotive broadening


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The Interstellar Boundary Explorer (IBEX) observes the IBEX ribbon, which stretches across much of the sky observed in energetic neutral atoms (ENAs). The ribbon covers a narrow (~20°-50°) region that is believed to be roughly perpendicular to the interstellar magnetic field. Superimposed on the IBEX ribbon is the globally distributed flux that is controlled by the processes and properties of the heliosheath. This is a second study that utilizes a previously developed technique to separate ENA emissions in the ribbon from the globally distributed flux. A transparency mask is applied over the ribbon and regions of high emissions. We then solve for the globally distributed flux using an interpolation scheme. Previously, ribbon separation techniques were applied to the first year of IBEX-Hi data at and above 0.71 keV. Here we extend the separation analysis down to 0.2 keV and to five years of IBEX data enabling first maps of the ribbon and the globally distributed flux across the full sky of ENA emissions. Our analysis shows the broadening of the ribbon peak at energies below 0.71 keV and demonstrates the apparent deformation of the ribbon in the nose and heliotail. We show global asymmetries of the heliosheath, including both deflection of the heliotail and differing widths of the lobes, in context of the direction, draping, and compression of the heliospheric magnetic field. We discuss implications of the ribbon maps for the wide array of concepts that attempt to explain the ribbon's origin. Thus, we present the five-year separation of the IBEX ribbon from the globally distributed flux in preparation for a formal IBEX data release of ribbon and globally distributed flux maps to the heliophysics community.

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Understanding nuclear and electronic dynamics of molecular systems has advanced considerably by probing their nonlinear responses with a suitable sequence of pulses. Moreover, the ability to control crucial parameters of the excitation pulses, such as duration, sequence, frequency, polarization, slowly varying envelope, or carrier phase, has led to a variety of advanced time-resolved spectroscopic methodologies. Recently, two-dimensional electronic spectroscopy with ultrashort pulses has become a more and more popular tool since it allows to obtain information on energy and coherence transfer phenomena, line broadening mechanisms, or the presence of quantum coherences in molecular complexes. Here, we present a high fidelity two-dimensional electronic spectroscopy setup designed for molecular systems in solution. It incorporates the versatility of pulse-shaping methods to achieve full control on the amplitude and phase of the individual exciting and probing pulses. Selective and precise amplitude- and phase-modulation is shown and applied to investigate electronic dynamics in several reference molecular systems.

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In any physicochemical process in liquids, the dynamical response of the solvent to the solutes out of equilibrium plays a crucial role in the rates and products: the solvent molecules react to the changes in volume and electron density of the solutes to minimize the free energy of the solution, thus modulating the activation barriers and stabilizing (or destabilizing) intermediate states. In charge transfer (CT) processes in polar solvents, the response of the solvent always assists the formation of charge separation states by stabilizing the energy of the localized charges. A deep understanding of the solvation mechanisms and time scales is therefore essential for a correct description of any photochemical process in dense phase and for designing molecular devices based on photosensitizers with CT excited states. In the last two decades, with the advent of ultrafast time-resolved spectroscopies, microscopic models describing the relevant case of polar solvation (where both the solvent and the solute molecules have a permanent electric dipole and the mutual interaction is mainly dipole−dipole) have dramatically progressed. Regardless of the details of each model, they all assume that the effect of the electrostatic fields of the solvent molecules on the internal electronic dynamics of the solute are perturbative and that the solvent−solute coupling is mainly an electrostatic interaction between the constant permanent dipoles of the solute and the solvent molecules. This well-established picture has proven to quantitatively rationalize spectroscopic effects of environmental and electric dynamics (time-resolved Stokes shifts, inhomogeneous broadening, etc.). However, recent computational and experimental studies, including ours, have shown that further improvement is required. Indeed, in the last years we investigated several molecular complexes exhibiting photoexcited CT states, and we found that the current description of the formation and stabilization of CT states in an important group of molecules such as transition metal complexes is inaccurate. In particular, we proved that the solvent molecules are not just spectators of intramolecular electron density redistribution but significantly modulate it. Our results solicit further development of quantum mechanics computational methods to treat the solute and (at least) the closest solvent molecules including the nonperturbative treatment of the effects of local electrostatics and direct solvent−solute interactions to describe the dynamical changes of the solute excited states during the solvent response.

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BACKGROUND: While significant strides have been made in health research, the incorporation of research evidence into healthcare decision-making has been marginal. The purpose of this paper is to provide an overview of how the utility of health services research can be improved through the use of theory. Integrating theory into health services research can improve research methodology and encourage stronger collaboration with decision-makers. DISCUSSION: Recognizing the importance of theory calls for new expectations in the practice of health services research. These include: the formation of interdisciplinary research teams; broadening the training for those who will practice health services research; and supportive organizational conditions that promote collaboration between researchers and decision makers. Further, funding bodies can provide a significant role in guiding and supporting the use of theory in the practice of health services research. SUMMARY: Institutions and researchers should incorporate the use of theory if health services research is to fulfill its potential for improving the delivery of health care.

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Contraction of cardiac muscle is regulated through the Ca2+ dependent protein-protein interactions of the troponin complex (Tn). The critical role cardiac troponin C (cTnC) plays as the Ca2+ receptor in this complex makes it an attractive target for positive inotropic compounds. In this study, the ten Met methyl groups in cTnC, [98% 13C ϵ]-Met cTnC, are used as structural markers to monitor conformational changes in cTnC and identify sites of interaction between cTnC and cardiac troponin I (cTnI) responsible for the Ca2+ dependent interactions. In addition the structural consequences that a number of Ca2+-sensitizing compounds have on free cTnC and the cTnC·cTnI complex were characterized. Using heteronuclear NMR experiments and monitoring chemical shift changes in the ten Met methyl 1H-13C correlations in 3Ca2+ cTnC when bound to cTnI revealed an anti-parallel arrangement for the two proteins such that the N-domain of cTnI interacts with the C-domain of cTnC. The large chemical shifts in Mets-81, -120, and -157 identified points of contact between the proteins that include the C-domain hydrophobic surface in cTnC and the A, B, and D helical interface located in the regulatory N-domain of cTnC. TnI association [cTnI(33–80), cTnI(86–211), or cTnI(33–211)] was found also to dramatically reduce flexibility in the D/E central linker of cTnC as monitored by line broadening in the Met 1H- 13C correlations of cTnC induced by a nitroxide spin label, MTSSL, covalently attached to cTnC at Cys 84. TnI association resulted in an extended cTnC that is unlike the compact structure observed for free cTnC. The Met 1H-13C correlations also allowed the binding characteristics of bepridil, TFP, levosimendan, and EMD 57033 to the apo, 2Ca2+, and Ca2+ saturated forms of cTnC to be determined. In addition, the location of drug binding on the 3Ca2+cTnC·cTnI complex was identified for bepridil and TFP. Use of a novel spin-labeled phenothiazine, and detection of isotope filtered NOEs, allowed identification of drug binding sites in the shallow hydrophobic cup in the C-terminal domain, and on two hydrophobic surfaces on N-regulatory domain in free 3Ca2+ cTnC. In contrast, only one N-domain drug binding site exists in 3Ca2+ cTnC·cTnI complex. The methyl groups of Met 45, 60 and 80, which are grouped in a hydrophobic patch near site II in cTnC, showed the greatest change upon titration with bepridil or TFP, suggesting that this is a critical site of drug binding in both free cTnC and when associated with cTnI. The strongest NOEs were seen for Met-60 and -80, which are located on helices C and D, respectively, of Ca2+ binding site II. These results support the conclusion that the small hydrophobic patch which includes Met-45, -60, and -80 constitutes a drug binding site, and that binding drugs to this site will lead to an increase in Ca2+ binding affinity of site II while preserving maximal cTnC activity. Thus, the subregion in cTnC makes a likely target against which to design new and selective Ca2+-sensitizing compounds. ^

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From seemingly outdated passages of Aristotle on oikonomikè, this paper tries to select and separate what is old-fashioned from what is valid for today. From these latter elements –which may be abridged in the intrinsic ethical and political character of economics– we can extract useful lessons. These lessons refer to the impact of Ethics and Politics on Economics. They stress the relevance of personal virtues and institutions for a suitable functioning of the economy. From an epistemological point of view, these lessons highlight the inexact character of Economics and the necessity of firm reliance on data. Current economics does not deal with ends, but only with means. The Aristotelian perspective would specially deal with ends. This concern with ends leads to prudential, not technical analysis and decisions. This calls for broadening the scope of Economics and consequently should provoke changes in its instruction. The paper concludes that a closer attention to Aristotle’s thought would have a high impact on current economy and Economics.

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La elucidación, parcial y provisoria, de los compromisos ideológicos inconscientemente sostenidos redunda en aportes a la reflexión sobre la intervención de los trabajadores sociales. Articulamos cierta teoría crítica de las ideologías con Trabajo Social y realizamos un análisis crítico del enunciado «El Trabajo Social ante los cambios que implican las nuevas legislaciones… ». Presentamos la clínica transdisciplinaria de la intervención social (Karsz, 2007), propuesta con alta potencialidad, pues analiza las intervenciones concretas en sus múltiples vinculaciones y aporta una voz disruptiva en el campo discursivo del Trabajo Social argentino actual, colaborando en abrir el abanico de las teorías críticas en la profesión.

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El objetivo es presentar categorías construidas por Vigotsky desde un enfoque psicológico y educativo, para enriquecer perspectivas sobre relaciones entre adolescentes y escuelas, integrando el contexto social e histórico en el que se inscriben. Se problematiza la concepción de fracaso escolar y de educabilidad de los sujetos, que los reduce a problemas individuales. Los textos de Vigotsky en Paidología del adolescente , escritos hace casi ochenta años, anticipan y proveen insumos significativos para la agenda de problemas contemporáneos sobre el desarrollo de los sujetos y las prácticas educativas. Se enfocan las unidades de análisis en el estudio de fenómenos psicoeducativos, para explicar y comprender conductas, funciones y procesos, desde planos personales, interpersonales y socioculturales. El recorrido del autor, pionero del enfoque socio-histórico-cultural, abarca dimensiones complejas, como intereses, pensamiento conceptual, imaginación y personalidad, analizando los procesos psíquicos superiores como desarrollos de la historia cultural de los adolescentes. Se articula el análisis de la obra con la revisión que autores contemporáneos post-vigotskianos realizan de la categoría de Zona de Desarrollo Próximo. La lectura puede ampliar la perspectiva de agentes psicoeducativos sobre problemas y estrategias de intervención, tomando distancia de una lógica aplicacionista y enriqueciendo las lógicas de implicación y transformación situacional

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El objetivo es presentar categorías construidas por Vigotsky desde un enfoque psicológico y educativo, para enriquecer perspectivas sobre relaciones entre adolescentes y escuelas, integrando el contexto social e histórico en el que se inscriben. Se problematiza la concepción de fracaso escolar y de educabilidad de los sujetos, que los reduce a problemas individuales. Los textos de Vigotsky en Paidología del adolescente , escritos hace casi ochenta años, anticipan y proveen insumos significativos para la agenda de problemas contemporáneos sobre el desarrollo de los sujetos y las prácticas educativas. Se enfocan las unidades de análisis en el estudio de fenómenos psicoeducativos, para explicar y comprender conductas, funciones y procesos, desde planos personales, interpersonales y socioculturales. El recorrido del autor, pionero del enfoque socio-histórico-cultural, abarca dimensiones complejas, como intereses, pensamiento conceptual, imaginación y personalidad, analizando los procesos psíquicos superiores como desarrollos de la historia cultural de los adolescentes. Se articula el análisis de la obra con la revisión que autores contemporáneos post-vigotskianos realizan de la categoría de Zona de Desarrollo Próximo. La lectura puede ampliar la perspectiva de agentes psicoeducativos sobre problemas y estrategias de intervención, tomando distancia de una lógica aplicacionista y enriqueciendo las lógicas de implicación y transformación situacional

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El objetivo es presentar categorías construidas por Vigotsky desde un enfoque psicológico y educativo, para enriquecer perspectivas sobre relaciones entre adolescentes y escuelas, integrando el contexto social e histórico en el que se inscriben. Se problematiza la concepción de fracaso escolar y de educabilidad de los sujetos, que los reduce a problemas individuales. Los textos de Vigotsky en Paidología del adolescente , escritos hace casi ochenta años, anticipan y proveen insumos significativos para la agenda de problemas contemporáneos sobre el desarrollo de los sujetos y las prácticas educativas. Se enfocan las unidades de análisis en el estudio de fenómenos psicoeducativos, para explicar y comprender conductas, funciones y procesos, desde planos personales, interpersonales y socioculturales. El recorrido del autor, pionero del enfoque socio-histórico-cultural, abarca dimensiones complejas, como intereses, pensamiento conceptual, imaginación y personalidad, analizando los procesos psíquicos superiores como desarrollos de la historia cultural de los adolescentes. Se articula el análisis de la obra con la revisión que autores contemporáneos post-vigotskianos realizan de la categoría de Zona de Desarrollo Próximo. La lectura puede ampliar la perspectiva de agentes psicoeducativos sobre problemas y estrategias de intervención, tomando distancia de una lógica aplicacionista y enriqueciendo las lógicas de implicación y transformación situacional

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Miocene paleoceanographic evolution exhibits major changes resulting from the opening and closing of passages, the subsequent changes in oceanic circulation, and development of major Antarctic glaciation. The consequences and timing of these events can be observed in variations in the distribution of deep-sea hiatuses, sedimentation patterns, and biogeographic distribution of planktic organisms. The opening of the Drake Passage in the latest Oligocene to early Miocene (25-20 Ma) resulted in the establishment of the deep circumpolar current, which led to thermal isolation of Antarctica and increased global cooling. This development was associated with a major turnover in planktic organisms, resulting in the evolution of Neogene assemblages and the eventual extinction of Paleogene assemblages. The erosive patterns of two widespread hiatuses (PH, 23.0-22.5 Ma; and NH 1, 20-18 Ma) indicate that a deep circumequatorial circulation existed at this time, characterized by a broad band of carbonate-ooze deposition. Siliceous sedimentation was restricted to the North Atlantic and a narrow band around Antarctica. A major reorganization in deep-sea sedimentation and hiatus distribution patterns occurred near the early/middle Miocene boundary, apparently resulting from changes in oceanic circulation. Beginning at this time, deep-sea erosion occurred throughout the Caribbean (hiatus NH 2, 16-15 Ma), suggesting disruption of the deep circumequatorial circulation and northward deflection of deep currents, and/or intensification of the Gulf Stream. Sediment distribution patterns changed dramatically with the sudden appearance of siliceous-ooze deposition in the marginal and east equatorial North Pacific by 16.0 to 15.5 Ma, coincident with the decline of siliceous sedimentation in the North Atlantic. This silica switch may have been caused by the introduction of Norwegian Overflow Water into the North Atlantic acting as a barrier to outcropping of silica-rich Antarctic Bottom Water. The main aspects of the present oceanic circulation system and sediment distribution pattern were established by 13.5 to 12.5 Ma (hiatus NH 3), coincident with the establishment of a major East Antarctic ice cap. Antarctic glaciation resulted in a broadening belt of siliceous-ooze deposition around Antarctica, increased siliceous sedimentation in the marginal and east equatorial North Pacific and Indian Oceans, and further northward restriction of siliceous sediments in the North Atlantic. Periodic cool climatic events were accompanied by lower eustatic sea levels and widespread deep-sea erosion at 12 to 11 Ma (NH 4), 10 to 9 Ma (NH 5), 7.5 to 6.2 Ma (NH 6), and 5.2 to 4.7 Ma (NH 7).

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Using a new Admittance-based model for electrical noise able to handle Fluctuations and Dissipations of electrical energy, we explain the phase noise of oscillators that use feedback around L-C resonators. We show that Fluctuations produce the Line Broadening of their output spectrum around its mean frequency f0 and that the Pedestal of phase noise far from f0 comes from Dissipations modified by the feedback electronics. The charge noise power 4FkT/R C2/s that disturbs the otherwise periodic fluctuation of charge these oscillators aim to sustain in their L-C-R resonator, is what creates their phase noise proportional to Leeson’s noise figure F and to the charge noise power 4kT/R C2/s of their capacitance C that today’s modelling would consider as the current noise density in A2/Hz of their resistance R. Linked with this (A2/Hz?C2/s) equivalence, R becomes a random series in time of discrete chances to Dissipate energy in Thermal Equilibrium (TE) giving a similar series of discrete Conversions of electrical energy into heat when the resonator is out of TE due to the Signal power it handles. Therefore, phase noise reflects the way oscillators sense thermal exchanges of energy with their environment.

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Using a new Admittance-based model for electrical noise able to handle Fluctuations and Dissipations of electrical energy, we explain the phase noise of oscillators that use feedback around L-C resonators. We show that Fluctuations produce the Line Broadening of their output spectrum around its mean frequency f0 and that the Pedestal of phase noise far from f0 comes from Dissipations modified by the feedback electronics. The charge noise power 4FkT/R C2/s that disturbs the otherwise periodic fluctuation of charge these oscillators aim to sustain in their L-C-R resonator, is what creates their phase noise proportional to Leeson’s noise figure F and to the charge noise power 4kT/R C2/s of their capacitance C that today’s modelling would consider as the current noise density in A2/Hz of their resistance R. Linked with this (A2/Hz?C2/s) equivalence, R becomes a random series in time of discrete chances to Dissipate energy in Thermal Equilibrium (TE) giving a similar series of discrete Conversions of electrical energy into heat when the resonator is out of TE due to the Signal power it handles. Therefore, phase noise reflects the way oscillators sense thermal exchanges of energy with their environment

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The Stark full widths at half of the maximal line intensity (FWHM, ω) have been measured for 25 spectrallines of PbIII (15 measured for the first time) arising from the 5d106s8s, 5d106s7p, 5d106s5f and 5d106s5g electronic configurations, in a lead plasma produced by ablation with a Nd:YAG laser. The optical emission spectroscopy from a laser-induced plasma generated by a 10 640 Å radiation, with an irradiance of 2 × 1010 W cm− 2 on a lead target (99.99% purity) in an atmosphere of argon was analysed in the wavelength interval between 2000 and 7000 Å. The broadening parameters were obtained with the target placed in argon atmosphere at 6 Torr and 400 ns after each laser light pulse, which provides appropriate measurement conditions. A Boltzmann plot was used to obtain the plasma temperature (21,400 K) and published values of the Starkwidths in Pb I, Pb II and PbIII to obtain the electron number density (7 × 1016 cm− 3); with these values, the plasma composition was determined by means of the Saha equation. Local Thermodynamic Equilibrium (LTE) conditions and plasma homogeneity has been checked. Special attention was dedicated to the possible self-absorption of the different transitions. Comparison of the new results with recent available data is also presented.

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The magazine of the Spanish Nuclear Society (SNE), “Nuclear España” is a scientific-technical publication with almost thirty years of uninterrupted edition and more than 300 numbers published. Their pages approach technical subjects related to the nuclear energy, as well as the activities developed by the SNE, especially in national and international meetings. The main part of the magazine is composed by articles written by known specialist of the energy industry. One of the top goals of the magazine is to help on transferring the knowledge from the generation that built the nuclear power plants in Spain and the new generation of professionals that have started its nuclear career in the last years. Each number is monographic, trying to cover as many aspects on an issue as it is possible, with collaborations from the companies, the research centers and universities that helps to have complementary points of view. On the other hand the articles help to deep in the issue´s topic, broadening the view of the readers about the nuclear field and helping to share knowledge across the industry. The news section of the Magazine picks up the actuality of the sector as a whole. The editorial section reflects the opinion of the SNE Governing Board and the Magazine Committee on the subjects of interest in this field. On the other hand, the monthly interview sets out the professional outstanding opinions. With a total of eleven numbers per year, three of them have a noticeable international character: the one dedicated to the operative experiences on the Spanish and European nuclear power plants, the monographic issue devoted tothe Annual Meeting of the SNE and the international issue, which covers the last activities of the Spanish industry in international projects. Both first are bilingual issues (Spanish-English), whereas the international edition is published completely in English. Besides its diffusion through all the members of the SNE, the Magazine is distributed, in the national scope, to companies and organisms related to the nuclear power, universities, research centers, representatives of the Central, Autonomic and Local Administrations, mass media and communication professionals. It is also sent to the utilities and research centers in Europe, United States, South America and Asia.