936 resultados para Solomon Blatt


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Annually dated ice cores from West and East Antarctica provide proxies for past changes in atmospheric circulation over Antarctica and portions of the Southern Ocean, temperature in coastal West and East Antarctica, and the frequency of South Polar penetration of El Nino events. During the period (AD) 1700-1850, atmospheric circulation over the Antarctic and at least portions of the Southern Hemisphere underwent a mode switch departing from the out-of-phase alternation of multi-decadal long phases of EOF1 and EOF2 modes of the 850 hPa field over the Southern Hemisphere (as defined in the recent record by Thompson and Wallace, 2000; Thompson and Solomon, 2002) that characterizes the remainder of the 700 year long record. From (AD) 1700 to 1850, lower-tropospheric circulation was replaced by in-phase behavior of the Amundsen Sea Low component of EOF2 and the East Antarctic High component of EOF1. During the first phase of the mode switch, both West and East Antarctic temperatures declined, potentially in response to the increased extent of sea ice surrounding both regions. At the end of the mode switch, West Antarctic coastal temperatures rose and East Antarctic coastal temperatures fell, respectively, to their second highest and lowest of the record. Polar penetration of El Nino events increased during the mode switch. The onset of the AD 1700-1850 mode switch coincides with the extreme state of the Maunder Minimum in solar variability. Late 20th-century West Antarctic coastal temperatures are the highest in the record period, and East Antarctic coastal temperatures close to the lowest. Since AD 1700, extratropical regions of the Southern Hemisphere have experienced significant climate variability coincident with changes in both solar variability and greenhouse gases.

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by S. Levy

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Die Foliierung geht nur bis Bl. 311; zusätzlich gibt es das Blatt 182a.

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Climate refugia, locations where taxa survive periods of regionally adverse climate, are thought to be critical for maintaining biodiversity through the glacial–interglacial climate changes of the Quaternary. A critical research need is to better integrate and reconcile the three major lines of evidence used to infer the existence of past refugia – fossil records, species distribution models and phylogeographic surveys – in order to characterize the complex spatiotemporal trajectories of species and populations in and out of refugia. Here we review the complementary strengths, limitations and new advances for these three approaches. We provide case studies to illustrate their combined application, and point the way towards new opportunities for synthesizing these disparate lines of evidence. Case studies with European beech, Qinghai spruce and Douglas-fir illustrate how the combination of these three approaches successfully resolves complex species histories not attainable from any one approach. Promising new statistical techniques can capitalize on the strengths of each method and provide a robust quantitative reconstruction of species history. Studying past refugia can help identify contemporary refugia and clarify their conservation significance, in particular by elucidating the fine-scale processes and the particular geographic locations that buffer species against rapidly changing climate.

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von Anatole Leroy-Beaulieu. Ins Dt. übertr. von Carl von Vincenti

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Noble gas radionuclides, including 81Kr (t1/2 = 229,000 years), 85Kr (t1/2 = 10.8 years), and 39Ar (t1/2 = 269 years), possess nearly ideal chemical and physical properties for studies of earth and environmental processes. Recent advances in Atom Trap Trace Analysis (ATTA), a laser-based atom counting method, have enabled routine measurements of the radiokrypton isotopes, as well as the demonstration of the ability to measure 39Ar in environmental samples. Here we provide an overview of the ATTA technique, and a survey of recent progress made in several laboratories worldwide.We review the application of noble gas radionuclides in the geosciences and discuss how ATTA can help advance these fields, specifically: determination of groundwater residence times using 81Kr, 85Kr, and 39Ar; dating old glacial ice using 81Kr; and an 39Ar survey of the main water masses of the oceans, to study circulation pathways and estimate mean residence times. Other scientific questions involving a deeper circulation of fluids in the Earth's crust and mantle are also within the scope of future applications. We conclude that the geoscience community would greatly benefit from an ATTA facility dedicated to this field, with instrumentation for routine measurements, as well as for research on further development of ATTA methods.

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Vorbesitzer: Senckenbergische Bibliothek Frankfurt am Main;

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by Sol. M. Stroock

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Genetic improvement of native crops is a new and promising strategy to combat hunger in the developing world. Tef is the major staple food crop for approximately 50 million people in Ethiopia. As an indigenous cereal, it is well adapted to diverse climatic and soil conditions; however, its productivity is extremely low mainly due to susceptibility to lodging. Tef has a tall and weak stem, liable to lodge (or fall over), which is aggravated by wind, rain, or application of nitrogen fertilizer. To circumvent this problem, the first semi-dwarf lodging-tolerant tef line, called kegne, was developed from an ethyl methanesulphonate (EMS)-mutagenized population. The response of kegne to microtubule-depolymerizing and -stabilizing drugs, as well as subsequent gene sequencing and segregation analysis, suggests that a defect in the α-Tubulin gene is functionally and genetically tightly linked to the kegne phenotype. In diploid species such as rice, homozygous mutations in α-Tubulin genes result in extreme dwarfism and weak stems. In the allotetraploid tef, only one homeologue is mutated, and the presence of the second intact α-Tubulin gene copy confers the agriculturally beneficial semi-dwarf and lodging-tolerant phenotype. Introgression of kegne into locally adapted and popular tef cultivars in Ethiopia will increase the lodging tolerance in the tef germplasm and, as a result, will improve the productivity of this valuable crop.

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Tef Eragrostis tef (Zucc.) Trotter is a cereal crop resilient to adverse climatic and soil conditions, and possessing desirable storage properties. Although tef provides high quality food and grows under marginal conditions unsuitable for other cereals, it is considered to be an orphan crop because it has benefited little from genetic improvement. Hence, unlike other cereals such as maize and wheat, the productivity of tef is extremely low. In spite of the low productivity, tef is widely cultivated by over six million small-scale farmers in Ethiopia where it is annually grown on more than three million hectares of land, accounting for over 30% of the total cereal acreage. Tef, a tetraploid with 40 chromosomes (2n=4x=40), belongs to the Family Poaceae and, together with finger millet (Eleusine coracana Gaertn), to the Subfamily Chloridoideae. It was believed to have originated in Ethiopia. There are about 350 Eragrostis species of which E. tef is the only species cultivated for human consumption. At the present time, the gene bank in Ethiopia holds over five thousand tef accessions collected from geographical regions diverse in terms of climate and elevation. These germplasm accessions appear to have huge variability with regard to key agronomic and nutritional traits. In order to properly utilize the variability in developing new tef cultivars, various techniques have been implemented to catalog the extent and unravel the patterns of genetic diversity. In this review, we show some recent initiatives investigating the diversity of tef using genomics, transcriptomics and proteomics and discuss the prospect of these efforts in providing molecular resources that can aid modern tef breeding.

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A career workshop that applies models of the Cognitive Information Processing Approach (Sampson, Reardon, Peterson, & Lenz, 2004) and incorporates critical ingredients (Brown and Ryan Krane, 2000) to promote the career choice readiness of young adolescents was developed and evaluated with 334 Swiss students in seventh grade applying a Solomon four group design with a three-month follow-up. Participants significantly increased their performance in terms of career decidedness, career planning, career exploration, and vocational identity. Implications for evaluation research and counselling practice are presented.

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Fragestellung/Einleitung An der Universität Bern haben die Medizinstudierenden des 1. und 2. Jahres die Möglichkeit mit Pflegestudierenden zusammen ein Wahlpraktikum zu bestreiten. Hierbei stellen sich die Studierenden gegenseitig ihre Curricula vor und verbringen gemeinsam je einen Halbtag in beiden Bildungseinrichtungen. Mit dem RIPLS (readiness for Interprofessional learning scale) wollten wir die Bereitschaft der Studierenden vor und nach dem Wahlpraktikum erfassen und diese mit je einer Kontrollgruppe der beiden Studiengänge vergleichen. Methoden Als Messinstrument wählten wir die Readiness for Interprofessional Learning Scale (RIPLS). Da noch keine validierte deutsche Übersetzung der RIPLS existiert, haben wir die 19 items zu zweit übersetzt und mehrfach überarbeitet. Am Wahlpraktikum nahmen 15 Medizin- und 11 Pflegestudierende teil. Die Kontrollgruppen bestanden aus 34 Medizin- und 21 Pflegestudierenden. Die RIPLS wurden vor und unmittelbar nach dem Wahlpraktikum verteilt und eingesammelt. Ergebnisse Die Resultate der Befragung zeigen, dass sich die Antworten der Medizin- und Pflegestudierenden in der Tendenz sehr ähnlich sind. In der Regel sind alle inklusive die beiden Kontrollgruppen positiv zum interprofessionellen Lernen eingestellt. Nur bei einzelnen Items, die das Rollenverständnis der beiden Berufsgruppen betreffen, waren grössere Unterschiede erkennbar. Die Antworten vor und nach dem Wahlpraktikum unterscheiden sich nicht wesentlich. Diskussion/Schlussfolgerung Sowohl Medizin- als auch Pflegestudierende haben eine positive Haltung gegenüber interprofessionellen Lernen, unabhängig davon, ob sie sich für eine entsprechendes Wahlpraktikum gemeldet haben oder nicht. Die Teilnahme am Wahlpraktikum verändert diese Haltung jedoch nicht wesentlich. Dies kontrastiert mit den sehr positiven spontanen Rückmeldungen der Studierenden beider Studiengänge. Es stellt sich darum die Frage, ob die RIPLS das geeignete Messinstrument ist, um die Effekte eines interprofessionellen Wahlpraktikus zu erfassen. Literaturhinweise: [1] Parsell G, Bligh J. The development of a questionnaire to assess the readiness of health care students for interprofessional learning (RIPLS). Med Educ. 1999 Feb;33(2):95-100 [2] Solomon P, Salfi J. Evaluation of an interprofessional education communication skills initiative. Educ Health (Abingdon). 2011 Aug;24(2):616. Epub 2011 Jul 30.