971 resultados para theoretische Teilchenphysik, Extra-Dimensionen, Flavor, Higgs, Präzisionstests
Resumo:
For Northern Hemisphere extra-tropical cyclone activity, the dependency of a potential anthropogenic climate change signal on the identification method applied is analysed. This study investigates the impact of the used algorithm on the changing signal, not the robustness of the climate change signal itself. Using one single transient AOGCM simulation as standard input for eleven state-of-the-art identification methods, the patterns of model simulated present day climatologies are found to be close to those computed from re-analysis, independent of the method applied. Although differences in the total number of cyclones identified exist, the climate change signals (IPCC SRES A1B) in the model run considered are largely similar between methods for all cyclones. Taking into account all tracks, decreasing numbers are found in the Mediterranean, the Arctic in the Barents and Greenland Seas, the mid-latitude Pacific and North America. Changing patterns are even more similar, if only the most severe systems are considered: the methods reveal a coherent statistically significant increase in frequency over the eastern North Atlantic and North Pacific. We found that the differences between the methods considered are largely due to the different role of weaker systems in the specific methods.
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The Nigerian video film industry known as Nollywood forms one of the world’s biggest entertainment industries today. In its stories, Nollywood reflects the values, desires and fears of African viewers and shows them new postcolonial forms of performative self-expression. In that way, it has become a point of reference for a wide range of people. As such, it not only excites a large number of viewers inside and outside Nigeria but also inspires some of them to make their own films. This nascent phenomenon of Nollywood inspired filmmaking is the starting point of my doctoral thesis and this article. By applying the methods of shared anthropology and performance ethnography I study a group of African migrants making their own film in Switzerland.
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Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H --> gamma-gamma, H --> ZZ* --> 4 leptons and H --> WW --> 2 leptons + 2 neutrinos. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of 7 TeV and 8 TeV, corresponding to an integrated luminosity of about 25/fb. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson.
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The meter-per-second precision achieved by today’s velocimeters enables us to search for 1−10 M⊕ planets in the habitable zone of cool stars. This paper reports on the detection of three planets orbiting GJ 163 (HIP 19394), a M3 dwarf monitored by our ESO/HARPS search for planets. We made use of the HARPS spectrograph to collect 150 radial velocities of GJ 163 over a period of eight years. We searched the radial-velocity time series for coherent signals and found five distinct periodic variabilities. We investigated the stellar activity and called into question the planetary interpretation for two signals. Before more data can be acquired we concluded that at least three planets are orbiting GJ 163. They have orbital periods of Pb = 8.632 ± 0.002, Pc = 25.63 ± 0.03, and Pd = 604 ± 8 days and minimum masses msini = 10.6 ± 0.6, 6.8 ± 0.9, and 29 ± 3 M⊕, respectively. We hold our interpretations for the two additional signals with periods P(e) = 19.4 and P(f) = 108 days. The inner pair presents an orbital period ratio of 2.97, but a dynamical analysis of the system shows that it lays outside the 3:1 mean motion resonance. The planet GJ 163c, in particular, is a super-Earth with an equilibrium temperature of Teq = (302 ± 10)(1 − A)1/4 K and may lie in the so-called habitable zone for albedo values (A = 0.34 − 0.89) moderately higher than that of Earth (A⊕ = 0.2−0.3).
Resumo:
The vast diversity of planetary systems detected to date is defying our capability of understanding their formation and evolution. Well-defined volume-limited surveys are the best tool at our disposal to tackle the problem, via the acquisition of robust statistics of the orbital elements. We are using the HARPS spectrograph to conduct our survey of ≈850 nearby solar-type stars, and in the course of the past nine years we have monitored the radial velocity of HD 103774, HD 109271, and BD-061339. In this work we present the detection of five planets orbiting these stars, with msin (i) between 0.6 and 7 Neptune masses, four of which are in two multiple systems, comprising one super-Earth and one planet within the habitable zone of a late-type dwarf. Although for strategic reasons we chose efficiency over precision in this survey, we have the capability to detect planets down to the Neptune and super-Earth mass range as well as multiple systems, provided that enough data points are made available.
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Objective. To investigate the association of the three major genetic groups of Mycobacterium tuberculosis with pulmonary and extra-pulmonary tuberculosis in clustered and non-clustered TB cases in the Houston area. ^ Study design. Secondary analysis of an ambi-directional study. ^ Study population. Three hundred fifty-eight confirmed cases of tuberculosis in the Houston that occurred between October 1995 and May 1997, who had been interviewed by the Houston T13 Initiative staff at Baylor College of Medicine, and whose isolates have had their DNA fingerprint and genetic group determined. ^ Exclusions. Individuals whose mycobacterial genotype was unknown, or whose data variables were unavailable. ^ Source of data. Laboratory results, patient interviews, and medical records at clinics and hospitals of the study population. ^ Results. In clustered cases, the majority of both, pulmonary and extra-pulmonary TB cases were caused by genetic group 1. Independent factors were assessed to determine the interactions that may influence the site of infection or increase the risk for one site or another. HIV negative males were protected against extra-pulmonary TB compared to HIV negative females. Individuals ages 1–14 years were at higher risk of having extra-pulmonary TB. Group 3 organisms were found less frequently in the total population in general, especially in extra-pulmonary disease. This supports the evidence in previous studies that this group is the least virulent and genetically distinct from the other two groups. Group 1 was found more frequently among African Americans than other ethnic groups, a trend for future investigations. ^ Among the non-clustered cases, group 2 organisms were the majority of the organisms found in both sites. They were also the majority of organisms found in African Americans, Caucasians, and Hispanics causing the majority of the infections at both sites. However, group 1 organisms were the overwhelming majority found in Asian/Pacific Islander individuals, which may indicate these organisms are either endemic to that area, or that there is an ethnic biological factor involved. This may also be due to a systematic bias, since isolates from individuals from that geographic region lack adequate copies of the insertion sequence IS6110, which leads to their placement in the non-clustered population. ^ The three genetic groups of Mycobacterium tuberculosis were not found equally distributed between sites of infection in both clustered and non-clustered cases. Furthermore, these groups were not distributed in the same patterns among the clustered and non-clustered cases, but rather in distinct patterns. ^
Resumo:
Gaining economic benefits from substantially lower labor costs has been reported as a major reason for offshoring labor-intensive information systems services to low-wage countries. However, if wage differences are so high, why is there such a high level of variation in the economic success between offshored IS projects? This study argues that offshore outsourcing involves a number of extra costs for the ^his paper was recommended for acceptance by Associate Guest Editor Erran Carmel. client organization that account for the economic failure of offshore projects. The objective is to disaggregate these extra costs into their constituent parts and to explain why they differ between offshored software projects. The focus is on software development and maintenance projects that are offshored to Indian vendors. A theoretical framework is developed a priori based on transaction cost economics (TCE) and the knowledge-based view of the firm, comple mented by factors that acknowledge the specific offshore context The framework is empirically explored using a multiple case study design including six offshored software projects in a large German financial service institution. The results of our analysis indicate that the client incurs post contractual extra costs for four types of activities: (1) re quirements specification and design, (2) knowledge transfer, (3) control, and (4) coordination. In projects that require a high level of client-specific knowledge about idiosyncratic business processes and software systems, these extra costs were found to be substantially higher than in projects where more general knowledge was needed. Notably, these costs most often arose independently from the threat of oppor tunistic behavior, challenging the predominant TCE logic of market failure. Rather, the client extra costs were parti cularly high in client-specific projects because the effort for managing the consequences of the knowledge asymmetries between client and vendor was particularly high in these projects. Prior experiences of the vendor with related client projects were found to reduce the level of extra costs but could not fully offset the increase in extra costs in highly client-specific projects. Moreover, cultural and geographic distance between client and vendor as well as personnel turnover were found to increase client extra costs. Slight evidence was found, however, that the cost-increasing impact of these factors was also leveraged in projects with a high level of required client-specific knowledge (moderator effect).
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Seit mehr als zwanzig Jahren werden in der tertiären Lehramtsausbildung Schulpraktika reformiert und neuerdings in ihrem zeitlichen Umfang relativ zur Studienzeit vergrößert. Zum Gegenstand reger Forschungsaktivitäten avancierten Schulpraktika jedoch erst im letzten Jahrzehnt. Hiermit werden ein Überblick über das Forschungsfeld (Grundlagen der schulpraktischen Komponenten der Lehrerbildung; Forschungsmethodik) vorgelegt und aktuelle Forschungsergebnisse zu zentralen Aspekten der Wirksamkeit von Praktika und Effekten von Mentoring präsentiert. In englischsprachigen bzw. deutschsprachigen Beiträgen wird der Forschungsstand in Deutschland, den Niederlanden, Österreich und der Schweiz sowie den USA aufgezeigt. Der Band richtet sich an Personen, die in der Lehrerbildung tätig sind, also an Dozent/inn/en in Hochschulen und Seminaren, an Lehrerbildungsforscher/innen sowie an Fachpersonen in der Bildungsadministration und interessierte Studierende.
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Pädagogische Interventionen sind ein wichtiges Thema für Theorie, Empirie und Praxis. Voraussetzung für ihren Erfolg ist allerdings, dass sie empirisch begleitet werden. Zwar liegen einige Werke zur Durchführung psychologischer Interventionen vor, allerdings finden sich solche kaum für den pädagogischen Bereich. Der vorliegende Band zeigt erstmals die Grundlagen pädagogischer Interventionsforschung auf und gibt einen umfassenden Überblick über Interventionsforschung in zentralen pädagogischen Themen. Anhand von Beispielen für Interventionsformen zeigt er auf, wie pädagogische Interventionen erfolgen können. Er vermittelt sowohl theoretisches Grund- als auch empirisches Handlungswissen und zielt darauf ab, pädagogische Kompetenzen aufzubauen und Anregungen für die Weiterentwicklung des pädagogischen Arbeitsfelds in sich verändernden Lebenswelten zu geben. Der Band richtet sich an Studierende und Forschende der Pädagogik und der Pädagogischen Psychologie sowie an Personen, die pädagogische Interventionen systematisch und fundiert durchführen wollen.
Resumo:
Im vorliegenden Beitrag wird versucht, den [Lehr-Lern-Prozess] in Hinblick auf individualisierten Unterricht genauer zu klären und auf die aktuelle Diskussion zur wirksamen Implementierung von Bildungsstandards zu beziehen. Dabei wird ein lehr-lerntheoretisches Modell dargestellt, das Orientierungshilfen für die lern-wirksame Gestaltung von unterrichtlichen Prozessen bieten soll. Es wird im Weiteren auf die folgenden Qualitätsmerkmale guten Unterrichts bezogen: das Fördern einer positiven Lernatmosphäre, das Herstellen einer (bildungsstandardbezogenen) Zielorientierung und die Berücksichtigung von Lernvoraussetzungen durch pädagogische Diagnostik, die mit aufgabenbasierten und protokollierten Lernförderungskreisläufen gekoppelt ist. Abschließend werden Anwendungsmöglichkeiten dieses Modells insbesondere in der Unterrichtsgestaltung und -evaluation kurz aufgezeigt und kritisch diskutiert.
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BACKGROUNDS In vitro fertilization involves high dosage gonadotropin stimulation, which apparently has some negative impact on follicular endocrine function. As chorionic gonadotropin stimulation has been shown to increase the blood-follicular permeability in animal models, this raises the question if such an effect also applies to gonadotropins in humans, possibly affecting the endocrine follicular milieu. FINDINGS Follicular fluid and serum were collected at the time of follicular aspiration in in vitro fertilisation without (Natural cycle IVF, n = 24) and with (conventional gonadotropin stimulated IVF, n = 31) gonadotropin stimulation. The concentration of the extra-ovarian hormones prolactin and cortisol were analysed by immunoassays. RESULTS Median serum prolactin and cortisol concentrations were 12.3 ng/mL and 399 nmol/L without versus 32.2 ng/mL and 623 nmol/L with gonadotropin stimulation. The corresponding concentrations in follicular fluid were 20.6 ng/mL and 445 nmol/L versus 28.8 ng/ml and 456 nmol/L for prolactin and cortisol. As a consequence, mean follicular fluid:serum ratios were significantly reduced under gonadotropin stimulation (prolactin p = 0.0138, cortisol p = 0.0001). As an enhanced blood-follicular permeability and transportation, induced by gonadotropin stimulation, would result in increased instead of decreased follicular fluid:serum ratios as found in this study, it can be assumed that this does not affect extra-ovarian protein and steroid hormones as illustrated by prolactin and cortisol. CONCLUSIONS The model of serum follicular fluid:serum ratio of hormones, produced outside the ovaries, did not reveal a gonadotropin induced increased blood-follicular transportation capacity. Therefore it can be assumed that the effect of gonadotropins on follicular endocrine function is not due to an increased ovarian permeability of extra-ovarian hormones.