521 resultados para 1369
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We report on a novel experimental setup for distributed measurement of temperature, based on spontaneous Brillouin scattering in optical fiber. We have developed a mode-locked Brillouin fiber ring laser in order to generate the dual frequency source required for a heterodyne detection of the backscattered signal. This relatively simple system enables temperature measurements over 20 km with a spatial resolution of 7 m.
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The linear stability of flow past two circular cylinders in a side-by-side arrangement is investigated theoretically, numerically and experimentally under the assumption of a two-dimensional flow field, in order to explore the origin of in-phase and antiphase oscillatory flows. Steady symmetric flow is realized at a small Reynolds number, but becomes unstable above a critical Reynolds number though the solution corresponding to the flow still satisfies the basic equations irrespective of the magnitude of the Reynolds number. We obtained the solution numerically and investigated its linear stability. We found that there are two kinds of unstable modes, i.e., antisymmetric and symmetric modes, which lead to in-phase and antiphase oscillatory flows, respectively. We determined the critical Reynolds numbers for the two modes and evaluated the critical distance at which the most unstable disturbance changes from the antisymmetric to the symmetric mode, or vice versa. ©2005 The Physical Society of Japan.
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Доклад, поместен в сборника на Националната конференция "Образованието в информационното общество", Пловдив, май, 2009 г.
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Az alábbi írás Kornai János életműsorozata közeljövőben megjelenő harmadik kötetének bevezetője alapján készült. (A sorozat első kötete, A hiány és második kötete, A szocialista rendszer 2012-ben jelent meg.) Ritkán fordul elő, hogy életművét rendszerezve, egy szerző maga veszi tételesen sorra írásait, tárja fel az írások megszületésének körülményeit, és elemzi őket több évtized távlatából. Kornai János életműsorozatának összeállításakor erre a rendkívüli feladatra vállalkozott. A kötetben megjelenő 22 íráshoz fűzött gondolatainak közlésekor mai szemmel veszi górcső alá az egy kivételével a rendszerváltás előtt írt cikkeit, valamint 1956-ban írott első könyvét, A túlzott központosítást. Az írásokat rendszerező bevezető a központosításra és a piaci reformra összpontosítja a figyelmet - e témakörről bebizonyosodott, hogy korai még csupán a közgazdaságtani elmélettörténet fejezeteként számon tartani. A kötetben megjelenő írások egy része közvetlenül kapcsolódik a magyar gazdaság tapasztalataihoz, másik része pedig elméleti jellegű. Ennek megfelelően az itt közölt bevezetés is foglalkozik mind a magyar gazdaságtörténet máig is figyelemre méltó és tanulságos gyakorlati problémáival, mind pedig a szocializmust és a kapitalizmust, a centralizált és decentralizált formákat összehasonlító általános elméletekkel. ______ This piece forms the introduction to the forthcoming third volume of János Kor-nai s life s work series reissued in Hungarian. (The first and second volumes, Economics of Shortage and The Political Economy of the Socialist System, ap-peared in 2012.) It is rare for an author to arrange his own life s work, taking his writings item by item, presenting the circumstances in which they arose, and ana-lysing them decades later. His thoughts on the twenty-two writings in the volume, at the time of republication, involve scrutinizing with present-day eyes articles written, with one exception, before the change of system, along with his first book, Overcentralization, written in 1956. The introduction that systematizes these fo-cuses on centralization and on market reform - events show it is still too soon to see these subjects simply as a chapter in the theoretical history of economics. Some of the articles draw directly on experiences with the Hungarian economy, while others have a theoretical nature. So the introduction also deals both with practical problems of Hungarian economic history that remain notable and instructive, and with comparative general theories of socialism and capitalism and centralized and decentralized forms.
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Based on the observation of more than 10 000 leaves of plane trees, four populations of Corythucha ciliata (Say, 1832) (Heteroptera: Tingidae) are investigated. After having introduced some parameters derived from the data, we draw spatial-temporal patterns and describe the seasonal population dynamics of Corythucha ciliata. Amongst others, the temporal change of the density of population, the state plane of larvae–adults, the inclination to accumulate, and the intraspecific competition are examined. Population and biomass dynamics is characterized for populations with and without limited nutrient source in case of different weather circumstances and effects.
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A szerző a 2008-ban kezdődött gazdasági világválság hatását vizsgálja az egy részvényre jutó nyereség előrejelzésének hibájára. Számos publikáció bizonyította, hogy az elemzők a tényértékeknél szisztematikusan kedvezőbb tervértéket adnak meg az egy részvényre jutó előrejelzéseikben. Más vizsgálatok azt igazolták, hogy az egy részvényre jutó előrejelzési hiba bizonytalan környezetben növekszik, míg arra is számos bizonyítékot lehet találni, hogy a negatív hírek hatását az elemzők alulsúlyozzák. A gazdasági világválság miatt az elemzőknek számtalan negatív hírt kellett figyelembe venniük az előrejelzések készítésekor, továbbá a válság az egész gazdaságban jelentősen növelte a bizonytalanságot. A szerző azt vizsgálja, hogy miként hatott a gazdasági világválság az egy részvényre jutó nyereség- előrejelzés hibájára, megkülönböztetve azt az időszakot, amíg a válság negatív hír volt, attól, amikor már hatásaként jelentősen megnőtt a bizonytalanság. _____ The author investigated the impact of the financial crisis that started in 2008 on the forecasting error for earnings per share. There is plentiful evidence from the 1980s that analysts give systematically more favourable values in their earnings per share (EPS) forecasts than reality, i.e. they are generally optimistic. Other investigations have supported the idea that the EPS forecasting error is greater under uncertain environmental circumstances, while other researchers prove that the analysts under-react to the negative information in their forecasts. The financial crisis brought a myriad of negative information for analysts to consider in such forecasts, while also increasing the level of uncertainty for the entire economy. The article investigates the impact of the financial crisis on the EPS forecasting error, distinguishing the period when the crisis gave merely negative information, from the one when its effect of uncertainty was significantly increased over the entire economy.
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The cruise industry is a highly complex, but under-researched component of the hospitality industry. This article seeks to explore the paradoxical relationship between shipboard and shore side operations using the McKinsey 7S Framework, thereby providing a foundation for further inquiry. Recommendations are made for practitioners, and ideas are provided for future research.
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Vol. 22, Issue ?, 8 pages
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The purpose of this study was to identify the factors that motivate nursing faculty to use service learning. The study was based on the theory of planned behavior (TPB), which implies that the target behavior of intention to use service learning in higher education is influenced by the predictor variables of behavior beliefs (attitude), normative beliefs (peer influence), and control beliefs (confidence and resources). External variables were also considered (years of teaching experience, tenure status, and the type of curriculum). Group interviews and a pilot test were conducted to create the instrument for the study, and Cronbach alpha were calculated for survey item reliability. The participants were full time undergraduate nursing faculty members (n=-160) in the Southeastern United States who taught in universities with accredited nurse education programs. Demographic data as well as scores on scaled survey responses were used to evaluate the intention of nursing faculty to use service learning in their classes. Pearson product moment correlation coefficient and path analysis were applied to the data. The correlation findings indicated that there were statistically significant relationships between behavior beliefs, normative beliefs, and control beliefs and nursing faculty intention to use service learning. The path analysis also indicated that behavior beliefs and normative beliefs were significant, while control beliefs were not a strong influence on intention to use service learning. Normative beliefs showed the strongest direct influence. The use of a community based curriculum also had a positive influence on intention, and faculty with tenure status were more likely to have positive behavior beliefs (attitude) towards service learning. Finally, as teaching experience increased, positive attitudes towards the intention to use service learning decreased. Seventy-nine percent of the variation in the intention to use service learning was explained by the theory of planned behavior, the type of curriculum, teaching experience, and tenure status. These results will assist nursing administration and faculty to design strategies to facilitate the implementation of service learning pedagogy, as well as a community based curriculum which will help meet the 21st century goals set forth from the American Association of Colleges of Nursing.
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Approaches to quantify the organic carbon accumulation on a global scale generally do not consider the small-scale variability of sedimentary and oceanographic boundary conditions along continental margins. In this study, we present a new approach to regionalize the total organic carbon (TOC) content in surface sediments (<5 cm sediment depth). It is based on a compilation of more than 5500 single measurements from various sources. Global TOC distribution was determined by the application of a combined qualitative and quantitative-geostatistical method. Overall, 33 benthic TOC-based provinces were defined and used to process the global distribution pattern of the TOC content in surface sediments in a 1°x1° grid resolution. Regional dependencies of data points within each single province are expressed by modeled semi-variograms. Measured and estimated TOC values show good correlation, emphasizing the reasonable applicability of the method. The accumulation of organic carbon in marine surface sediments is a key parameter in the control of mineralization processes and the material exchange between the sediment and the ocean water. Our approach will help to improve global budgets of nutrient and carbon cycles.
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Peer reviewed
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El objetivo del artículo es realizar un diagnóstico sobre la percepción de los factores que intervienen en el rendimiento académico de los estudiantes de cinco carreras universitarias en una escuela de educación superior en México, para así reconocer las áreas de oportunidad que permitan sugerir políticas y estrategias para elevar su rendimiento. Se utilizó una muestra de 1651 estudiantes, se obtuvieron los datos a partir de un cuestionario con treinta preguntas que estudian la percepción del rendimiento académico en escala tipo Likert. Se realizó un análisis factorial exploratorio que permitiera reducir los datos, facilitar la interpretación y validar el instrumento. Se identificaron tres factores: a) el rol de los profesores, b) la evaluación y c) la motivación de los estudiantes. Se llevó a cabo un análisis comparativo por carrera. Se encontró que los estudiantes perciben que la mayoría de los maestros no se preocupan por la condición de los jóvenes en situación de reprobación. Además, casi no motivan y carecen de expresiones de sentimientos de orgullo por los logros académicos de los estudiantes. La mitad de los participantes piensa que los docentes no cubren el temario en su totalidad. Se detectó que los estudiantes poseen una alta motivación siendo esto positivo porque son alumnos dedicados y responsables. Se concluye realizando una serie de sugerencias y explicando las implicaciones que tiene este trabajo para las instituciones de educación superior.