48 research outputs found

    Co dimers on hexagonal carbon rings proposed as subnanometer magnetic storage bits

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    It is demonstrated by means of density functional and ab-initio quantum chemical calculations, that transition metal - carbon systems have the potential to enhance the presently achievable area density of magnetic recording by three orders of magnitude. As a model system, Co_2-benzene with a diameter of 0.5 nm is investigated. It shows a magnetic anisotropy in the order of 0.1 eV per molecule, large enough to store permanently one bit of information at temperatures considerably larger than 4 K. A similar performance can be expected, if cobalt dimers are deposited on graphene or on graphite. It is suggested that the subnanometer bits can be written by simultaneous application of a moderate magnetic and a strong electric field.Comment: 13 pages, 4 figure

    Urbane Grünflächenausstattung und deren Erreichbarkeit – Indikatordesign und empirischer Städtevergleich

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    Das Bestreben, multifunktionale Grünflächen zu erhalten und zu fördern, bedarf entsprechender Kennwerte und Indikatoren zur quantitativen und qualitativen Beschreibung der Zielerreichung. Im Rahmen eines Forschungsprojekts wurden Indikatoren zur Bewertung der Ökosystemleistung „Erholung in der Stadt“ erarbeitet und für 182 deutsche Städte umgesetzt. Die bundesweite Auswertung der Untersuchungsergebnisse ergibt für deutsche Städte mit mehr als 50 000 Einwohnern ein heterogenes Bild in der Grünflächenausstattung und -erreichbarkeit. Eine detailliertere Ergebnisinterpretation wird hierbei durch einen empirischen Städtevergleich auf Basis eines Rankings und einer Typisierung ermöglicht. Auf Grundlage der Typisierung können Städte mit einer im bundesweiten Vergleich überdurchschnittlich guten Grünflächenausstattung und Grünflächenerreichbarkeit identifiziert werden

    Germany’s Ecosystem Services – State of the Indicator Development for a Nationwide Assessment and Monitoring

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    The obligations of the EU Biodiversity Strategy 2020 are generating a need to create national maps and monitoring systems for the state of biodiversity and ecosystem services (ES) on the basis of indicators. The paper gives an overview of the ecosystem services indicators being developed for Germany in the context of ongoing research projects. Additionally, it provides the indicator specifications, which are aligned with the EU MAES framework concepts (initiative on Mapping and Assessment of Ecosystems and their Services). We illustrate aspects of data selection, calculation and negotiation procedures, results and target values in general and by way of examples. The German indicator-based approach presents measures and sums up ES in their spatial expression and temporal change and compares them with objectives. As far as possible, this is carried out according to the demand-supply concept. A prioritization of ES classes to be processed was carried out in the framework of an expert-based assessment. The results indicated that 21 of the 48 CICES classes (Common International Classification of Ecosystem Services) were most relevant for Germany in recent years. We proposed a total of 51 indicators, of which 14 indicators for 4 ES classes were accepted, implemented and published by the end of 2016. The development of ES maps and the indicator-based assessment on a national scale is a process. Consequently, the necessary further steps are shown

    Rapid Growth Reduces Cold Resistance: Evidence from Latitudinal Variation in Growth Rate, Cold Resistance and Stress Proteins

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    Background: Physiological costs of rapid growth may contribute to the observation that organisms typically grow at submaximal rates. Although, it has been hypothesized that faster growing individuals would do worse in dealing with suboptimal temperatures, this type of cost has never been explored empirically. Furthermore, the mechanistic basis of the physiological costs of rapid growth is largely unexplored. Methodology/Principal Finding: Larvae of the damselfly Ischnura elegans from two univoltine northern and two multivoltine southern populations were reared at three temperatures and after emergence given a cold shock. Cold resistance, measured by chill coma recovery times in the adult stage, was lower in the southern populations. The faster larval growth rates in the southern populations contributed to this latitudinal pattern in cold resistance. In accordance with their assumed role in cold resistance, Hsp70 levels were lower in the southern populations, and faster growing larvae had lower Hsp70 levels. Yet, individual variation in Hsp70 levels did not explain variation in cold resistance. Conclusions/Significance: We provide evidence for a novel cost of rapid growth: reduced cold resistance. Our results indicate that the reduced cold resistance in southern populations of animals that change voltinism along the latitudinal gradient may not entirely be explained by thermal selection per se but also by the costs of time constraint-induced higher growth rates. This also illustrates that stressors imposed in the larval stage may carry over and shape fitness in the adul

    Evolution and plasticity of anuran larval development in response to desiccation. A comparative analysis

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    Anurans breed in a variety of aquatic habitats with contrasting levels of desiccation risk, which may result in selection for faster development during larval stages. Previous studies suggest that species in ephemeral ponds reduce their developmental times to minimize desiccation risks, although it is not clear how variation in desiccation risk affects developmental strategies in different species. Employing a comparative phylogenetic approach including data from published and unpublished studies encompassing 62 observations across 30 species, we tested if species breeding in ephemeral ponds (High risk) develop faster than those from permanent ponds (Low risk) and/or show increased developmental plasticity in response to drying conditions. Our analyses support shorter developmental times in High risk, primarily by decreasing body mass at metamorphosis. Plasticity in developmental times was small and did not differ between groups. However, accelerated development in High risk species generally resulted in reduced sizes at metamorphosis, while some Low risk species were able compensate this effect by increasing mean growth rates. Taken together, our results suggest that plastic responses in species breeding in ephemeral ponds are constrained by a general trade-off between development and growth rates

    Abundance of thecosomatous pteropods in the Arabian Sea and Persian Gulf (Table 2)

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    This paper deals with the presence and distribution of Thecosomatous Pteropods in the Indian Ocean. 122 plankton-samples, taken by R.V. "Meteor" during the International Indian Ocean Expedition (IIOE) in 1964-65 were investigated. They contain a total number of about 45000 Thecosomata, belonging to 22 species and 5 families. Some species (e.g. Creseis acicula and Limacina inflata) are common in the entire area, others (e.g. Creseis chierchiae and Desmopterus gardinieri) show a quite distinct distribution. From several species only one single specimen was captured, others are completely lacking in the collection though they have been reported frequently from the same area by other expeditions. This may be due to seasonal variations and to the fact that no bathial tows were taken. In spite of these restrictions the extensive material from a relatively small area offers the possibility to compare specific and nonspecific features in related species and to question their taxonomic value

    Die thecosomen Pteropoden der "Meteor"-Expedition in den Indischen Ozean 1964/65

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    This paper deals with the presence and distribution of Thecosomatous Pteropods in the Indian Ocean. 122 plankton-samples, taken by R.V. "Meteor" during the International Indian Ocean Expedition (IIOE) in 1964-65 were investigated. They contain a total number of about 45000 Thecosomata, belonging to 22 species and 5 families. Some species (e.g. Creseis acicula and Limacina inflata) are common in the entire area, others (e.g. Creseis chierchiae and Desmopterus gardinieri) show a quite distinct distribution. From several species only one single specimen was captured, others are completely lacking in the collection though they have been reported frequently from the same area by other expeditions. This may be due to seasonal variations and to the fact that to bathial tows were taken. In spite of these restrictions the extensive material from a relatively small area offers the possibility to compare specific and nonspecific features in related species and to question their taxonomic value
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