400 research outputs found

    Can aggregate quarry silt lagoons provide resources for wading birds?

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    Wading birds have declined across Europe as the intensification of lowland agriculture has resulted in the loss and degradation of wetland areas. Lowland aggregate extraction sites that incorporate areas of fine, waste sediments deposited in silt lagoons have the potential to be restored for wader conservation. We set out to determine the potential value of silt lagoons to wading birds by comparing the water quality, sediment profiles, aquatic invertebrate abundance and diversity (prey availability) and wader site use at five sites representing various stages of active aggregate extraction and restoration for conservation purposes. Wader counts were conducted monthly over a twelve month period using replicated scan samples, and the invertebrate communities studied during the breeding and autumn migration season (June–September). Water quality variables were similar between sites, but sediments from active quarries were dominated by moderately sorted fine sands in comparison to the coarser sediment profiles of restored areas. June and September there was no significant difference in invertebrate diversity between sites, however richness was significantly lower on quarry sites and total abundance a factor of ten higher at restored sites than on silt lagoons, with the dominant taxa similar across all sites. Waders used all sites; albeit at lower abundance and richness on silt lagoons and two species were recorded breeding on active silting sites. We conclude that the fine, uniform sediments of modern silt lagoons limited invertebrate diversity and abundance, diminishing the value of silt lagoons to waders. Simple low-cost intervention measures increasing substrate heterogeneity and creating temporary ponds could increase invertebrate richness and abundance, and enhance the conservation potential of these sites

    Identification and functional characterization of the distinct plant pectin esterases PAE8 and PAE9 and their deletion mutants

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    MAIN CONCLUSION: PAE8 and PAE9 have pectin acetylesterase activity and together remove one-third of the cell wall acetate associated with pectin formation in Arabidopsis leaves. Inpae8andpae9mutants, substantial amounts of acetate accumulate in cell walls. In addition, the inflorescence stem height is decreased. Pectic polysaccharides constitute a significant part of the primary cell walls in dicotyledonous angiosperms. This diverse group of polysaccharides has been implicated in several physiological processes including cell-to-cell adhesion and pathogenesis. Several pectic polysaccharides contain acetyl-moieties directly affecting their physical properties such as gelling capacity, an important trait for the food industry. In order to gain further insight into the biological role of pectin acetylation, a reverse genetics approach was used to investigate the function of genes that are members of the Pectin AcetylEsterase gene family (PAE) in Arabidopsis. Mutations in two members of the PAE family (PAE8 and PAE9) lead to cell walls with an approximately 20 % increase in acetate content. High-molecular-weight fractions enriched in pectic rhamnogalacturonan I (RGI) extracted from the mutants had increased acetate content. In addition, the pae8 mutant displayed increased acetate content also in low-molecular-weight pectic fractions. The pae8/pae9-2 double mutant exhibited an additive effect by increasing wall acetate content by up to 37 %, suggesting that the two genes are not redundant and act on acetyl-substituents of different pectic domains. The pae8 and pae8/pae9-2 mutants exhibit reduced inflorescence growth underscoring the role of pectic acetylation in plant development. When heterologously expressed and purified, both gene products were shown to release acetate from the corresponding mutant pectic fractions in vitro. PAEs play a significant role in modulating the acetylation state of pectic polymers in the wall, highlighting the importance of apoplastic metabolism for the plant cell and plant growth. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00425-014-2139-6) contains supplementary material, which is available to authorized users

    07051 Working Group Outcomes -- Programming Paradigms for the Web: Web Programming and Web Services

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    Participants in the seminar broke into groups on ``Patterns and Paradigms\u27\u27 for web programming, ``Web Services,\u27\u27 ``Data on the Web,\u27\u27 ``Software Engineering\u27\u27 and ``Security.\u27\u27 Here we give the raw notes recorded during these sessions

    07051 Abstracts Collection -- Programming Paradigms for the Web: Web Programming and Web Services

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    From 28.01. to 02.02.2007, the Dagstuhl Seminar 07051 ``Programming Paradigms for the Web: Web Programming and Web Services\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

    07051 Executive Summary -- Programming Paradigms for the Web: Web Programming and Web Services

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    The world-wide web raises a variety of new programming challenges. To name a few: programming at the level of the web browser, data-centric approaches, and attempts to automatically discover and compose web services. This seminar brought together researchers from the web programming and web services communities and strove to engage them in communication with each other. The seminar was held in an unusual style, in a mixture of short presentations and in-depth discussion sessions in small groups. This style enabled the participants to identify and discuss burning questions in small birds-of-a-feather sessions as well as in large plenary sessions. It required active participation of all attendees

    Comments on A,B,C Chains of Heterotic and Type II Vacua

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    We construct, as hypersurfaces in toric varieties, Calabi-Yau manifolds corresponding to F-theory vacua dual to E8*E8 heterotic strings compactified to six dimensions on K3 surfaces with non-semisimple gauge backgrounds. These vacua were studied in the recent work of Aldazabal, Font, Ibanez and Uranga. We extend their results by constructing many more examples, corresponding to enhanced gauge symmetries, by noting that they can be obtained from previously known Calabi-Yau manifolds corresponding to K3 compactification of heterotic strings with simple gauge backgrounds by means of extremal transitions of the conifold type.Comment: 27p Plain TeX, 6 figures (4 in color) included via epsf.te

    Individual differences underlying susceptibility to addiction: Role for the endogenous oxytocin system

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    AbstractRecent research shows that the effects of oxytocin are more diverse than initially thought and that in some cases oxytocin can directly influence the response to drugs and alcohol. Large individual differences in basal oxytocin levels and reactivity of the oxytocin system exist. This paper will review the literature to explore how individual differences in the oxytocin system arise and examine the hypothesis that this may mediate some of the individual differences in susceptibility to addiction and relapse.Differences in the oxytocin system can be based on individual factors, e.g. genetic variation especially in the oxytocin receptor, age or gender, or be the result of early environmental influences such as social experiences, stress or trauma. The paper addresses the factors that cause individual differences in the oxytocin system and the environmental factors that have been identified to induce long-term changes in the developing oxytocin system during different life phases.Individual differences in the oxytocin system can influence effects of drugs and alcohol directly or indirectly. The oxytocin system has bidirectional interactions with the stress-axis, autonomic nervous system, neurotransmitter systems (e.g. dopamine, serotonin and GABA/glutamate) and the immune system. These systems are all important, even vital, in different phases of addiction.It is suggested that early life adversity can change the development of the oxytocin system and the way it modulates other systems. This in turn could minimise the negative feedback loops that would normally exist. Individuals may show only minor differences in behaviour and function unless subsequent stressors or drug use challenges the system. It is postulated that at that time individual differences in oxytocin levels, reactivity of the system or interactions with other systems can influence general resilience, drug effects and the susceptibility to develop problematic drug and alcohol use
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