304 research outputs found

    Law School Libraries 2007

    Get PDF
    The primary mission of the law school library is to meet the information needs of the faculty and students of the institution it supports. In addition to their role in educating future lawyers, law schools are the major producers of scholarly literature in law and rely on academic law libraries to provide the resources and support needed for research and publication. Beyond support for the core functions of legal education and research, the specific missions of law school libraries vary depending on the size and missions of law schools of different types. Differences among law schools result in differences among their libraries in collection size and composition, staffing and services offered, and additional clienteles served

    Student-oriented vesus teacher-centred: the effect of learning at workstations about birds and bird flight on cognitive achievement and motivation

    Full text link
    The study investigated cognitive and motivational effects of two educational interventions, a conventional versus a student-oriented approach. We monitored the impact on the cognitive achievement outcome and the motivation of students. Both approaches dealt with the subject of birds and bird flight; the student-oriented approach consisted of a unit based on workstations, the conventional one was taught in a more teacher-centred manner. 326 secondary school pupils of the highest stratification level participated in this study. By using a pre-, post- and retention-test design, both approaches were evaluated with the same empirical batteries (by applying a cognitive item set and the 'Intrinsic Motivation Inventory'). The conventional approach provided higher achievement scores whereas the student-oriented approach showed a higher motivational rating. Comparing the student-oriented approach with and without introduction, the group with introduction attained higher achievement scores. The results are discussed in terms of general expectations about the cognitive outcome in open learning environments and self-determination theory. Educational implications are drawn concerning the implementation of learning at workstations in school curricula

    Modularisierung als Schlüsselinstrument der Studienreform

    Get PDF

    Evolution and Spectral Response of a Steam Atmosphere for Early Earth with a coupled climate-interior model

    Get PDF
    The evolution of Earth's early atmosphere and the emergence of habitable conditions on our planet are intricately coupled with the development and duration of the magma ocean phase during the early Hadean period (4 to 4.5 Ga). In this paper, we deal with the evolution of the steam atmosphere during the magma ocean period. We obtain the outgoing longwave radiation using a line-by-line radiative transfer code GARLIC. Our study suggests that an atmosphere consisting of pure H2_{2}O, built as a result of outgassing extends the magma ocean lifetime to several million years. The thermal emission as a function of solidification timescale of magma ocean is shown. We study the effect of thermal dissociation of H2_{2}O at higher temperatures by applying atmospheric chemical equilibrium which results in the formation of H2_{2} and O2_{2} during the early phase of the magma ocean. A 1-6\% reduction in the OLR is seen. We also obtain the effective height of the atmosphere by calculating the transmission spectra for the whole duration of the magma ocean. An atmosphere of depth ~100 km is seen for pure water atmospheres. The effect of thermal dissociation on the effective height of the atmosphere is also shown. Due to the difference in the absorption behavior at different altitudes, the spectral features of H2_{2} and O2_{2} are seen at different altitudes of the atmosphere. Therefore, these species along with H2_{2}O have a significant contribution to the transmission spectra and could be useful for placing observational constraints upon magma ocean exoplanets.Comment: 22 pages, 17 Figures, accepted for publication in ApJ on March

    Bioprozessautomatisierung einer Algenanlage mithilfe eines Single-Board-Computers

    Get PDF
    Für die effektive Haltung von Mikroorganismen, kleinen Pflanzen oder Algen in Bioreaktoren ist die Aufrechterhaltung optimaler Kultivierungsbedingungen, wie beispielsweise pH-Wert, Temperatur oder Nährstoffgehalt, notwendig. Diese Parameter können sich während der Kultivierung ändern, weshalb sie regelmäßig kontrolliert und gegebenenfalls angepasst werden müssen. Wir präsentieren hier den technischen Aufbau und die Softwarerealisierung eines Automatisierungssystems zur autonomen Regulierung des pH-Wertes in Bioreaktoren, in denen die grüne Mikroalge Scenedesmus rubescens kultiviert wird. Dazu wurde ein System mit pH-Sensoren, Signalwandlern und Magnetventilen zur kontrollierten CO2-Begasung aufgebaut. Für die Steuerung und die Datenaufzeichnung diente ein Single-Board-Computer (Raspberry Pi) mit Webeserver. Die Anlage war voll funktionsfähig und konnte über mehrere Tage fehlerlos den pH-Wert auf einen vorgegebenen Wert regeln. Das System ist leicht auch auf Großanlagen und für andere Parameter erweiterbar. Durch die Nutzung eines Single-Board-Computers erfordert die Anlage nur minimalen Platz- und Energiebedarf und ist mit geringen Anschaffungskosten verbunden.The maintenance of stable internal conditions such as pH, temperature, or nutrients is essential for the cultivation of microorganisms, small plants and algae in bioreactors. These parameters can significantly vary during cultivation and have to be controlled and regulated. Here we present the technical construction and software implementation of an automation system for measurement and controlling pH in bioreactors for cultivating the green micro algae Scenedesmus rubescens. The system was built up with pH sensors, a signal transducing unit and magnetic valves that regulate the CO2 volume flow. A single-board-computer (Raspberry Pi) with web server was used as control unit and for data recording. The established system was stable for several days and approved for fulfilling all requirements. It is easily expandable for other parameters and can be used for larger systems. By using the Raspberry Pi as a low cost, very energy efficient credit-card sized computer with minimum space requirements the system can serve as an alternative for commercial automation systems

    A long-term analysis of the declining population of the Egyptian vulture in the Italian peninsula: Distribution, habitat preference, productivity and conservation implications

    Get PDF
    Between the beginning of the 1970s and the early 1990s the breeding population of the Egyptian vulture (Neophron percnopterus) in the Italian peninsula declined from 29 to nine breeding pairs. We analysed the main aspects of the decline of this population during the last 30 years, namely: (1) landscape structure and composition of active and extinct nesting sites; (2) changes in the land use and number of cattle within the breeding range; (3) productivity (1986-1999) of the last nine pairs breeding in the Italian peninsula. Further decline in the breeding population was probably stopped by creating artificial feeding sites and protecting the last nesting sites from direct persecution. Nearly two-thirds of the pairs laid at least one egg per year, and half of the pairs fledged at least one young per year. The mean number of fledged young was 0.99±0.66 per breeding pair, and 1.27±0.45 per successful pair. About 75% of the breeding failures occurred during incubation, and 71% were related to human activities and direct persecution. The nesting cliff occupation rate, percentage of breeding attempts that fledged at least one chick and mean number of fledged young were negatively correlated with the distance to an artificial feeding site. © 2001 Elsevier Science Ltd. All rights reserved.Peer Reviewe

    Spectral features of Earth-like planets and their detectability at different orbital distances around F, G, and K-type stars

    Full text link
    We investigate the spectral appearance of Earth-like exoplanets in the HZ of different main sequence stars at different orbital distances. We furthermore discuss for which of these scenarios biomarker absorption bands may be detected during primary or secondary transit with near-future telescopes and instruments.We analyze the spectra taking into account different filter bandpasses of two photometric instruments planned to be mounted to the JWST. We analyze in which filters and for which scenarios molecular absorption bands are detectable when using the space-borne JWST or the ground-based telescope E-ELT. Absorption bands of CO2, H2O, CH4 and O3 are clearly visible in high-resolution spectra as well as in the filters of photometric instruments. However, only during primary eclipse bands of CO2, H2O and O3 are detectable for all scenarios when using photometric instruments and an E-ELT telescope setup. CH4 is only detectable at the outer HZ of the K star since here the atmospheric modeling results in very high abundances. Since the detectable CO2 and H2O bands overlap, separate bands need to be observed to prove their existence in the atmosphere. In order to detect H2O in a separate band, a S/N>7 needs to be achieved for E-ELT observations, e.g. by co-adding at least 10 transit observations. Using a spaceborne telescope like the JWST enables the detection of CO2 at 4.3mu, which is not possible for ground-based observations due to the Earth's atmospheric absorption. Hence combining observations of spaceborne and groundbased telescopes might allow to detect the presence of the biomarker molecule O3 and the related compounds H2O and CO2 in a planetary atmosphere. Other absorption bands using the JWST can only be detected for much higher S/Ns, which is not achievable by just co-adding transit observations since this would be far beyond the planned mission time of JWST.(abridged)Comment: 15 pages, 8 figure

    Divergent Evolution of Eukaryotic CC- and A-Adding Enzymes

    Get PDF
    Synthesis of the CCA end of essential tRNAs is performed either by CCA-adding enzymes or as a collaboration between enzymes restricted to CC- and A-incorporation. While the occurrence of such tRNA nucleotidyltransferases with partial activities seemed to be restricted to Bacteria, the first example of such split CCA-adding activities was reported in Schizosaccharomyces pombe. Here, we demonstrate that the choanoflagellate Salpingoeca rosetta also carries CC- and A-adding enzymes. However, these enzymes have distinct evolutionary origins. Furthermore, the restricted activity of the eukaryotic CC-adding enzymes has evolved in a different way compared to their bacterial counterparts. Yet, the molecular basis is very similar, as highly conserved positions within a catalytically important flexible loop region are missing in the CC-adding enzymes. For both the CC-adding enzymes from S. rosetta as well as S. pombe, introduction of the loop elements from closely related enzymes with full activity was able to restore CCA-addition, corroborating the significance of this loop in the evolution of bacterial as well as eukaryotic tRNA nucleotidyltransferases. Our data demonstrate that partial CC- and A-adding activities in Bacteria and Eukaryotes are based on the same mechanistic principles but, surprisingly, originate from different evolutionary events

    Das Eheschließungs- und Ehescheidungsverhalten in der Stadt Essen im Zeitvergleich

    Full text link
    Der Wandel des Eheschließungs- und Ehescheidungsverhaltens und die damit einhergehende Veränderung der Haushalts- und Familienstrukturen hat Auswirkungen auf vielerlei Bereiche der Kommunalpolitik, z.B. im Hinblick auf den Bedarf an Kinderganztagsbetreuung, Erziehungshilfe, Altenpflege, soziale Dienste und letztendlich auch die Infrastruktur und Wohnraumversorgung. Vor diesem Hintergrund wird das Eheschließungs- und Ehescheidungsverhalten der Bevölkerung in Essen im Zeitvergleich untersucht. Betrachtet werden die Zahlen der Eheschließungen und Ehescheidungen sowie das Heiratsalter von 1930 bis 1994. Anhand der Zahlen wird verdeutlicht, daß die eheliche Lebensgemeinschaft einem Bedeutungswandel unterliegt und immer mehr nur für einen bestimmten, zeitlich begrenzten Lebensabschnitt gewählt wird. (ICA
    corecore