2,176 research outputs found

    Landscape ecological Decision & Evaluation Support System LEDESS : users guide

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    To understand the basic strategies in nature development, it is necessary to examine existing plans and schemes in order to reveal and clarify underlying concepts. Two questions are crucial here: what is the ecological objective, and what is the spatial strategy? The first question is related to the level of the ecosystem. With different types of nature management, different ecosystems can develop at the same site. Nature policy decides which system is to be developed. The second question is related to the landscape as a whole, the spatial pattern of ecosystems. It is taken into account that other activities, such as farming, recreation, water supply and quarrying, also require space. Nature development cannot be considered independently from those activities. Therefore, a spatial strategy is required to combine all land use functions. To find an optimal balance between the two questions, different nature development scenarios are developed

    Uniform electron gases: III. Low-density gases on three-dimensional spheres

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    By combining variational Monte Carlo (VMC) and complete-basis-set limit Hartree-Fock (HF) calculations, we have obtained near-exact correlation energies for low-density same-spin electrons on a three-dimensional sphere (3-sphere), i.e.~the surface of a four-dimensional ball. In the VMC calculations, we compare the efficacies of two types of one-electron basis functions for these strongly correlated systems, and analyze the energy convergence with respect to the quality of the Jastrow factor. The HF calculations employ spherical Gaussian functions (SGFs) which are the curved-space analogs of cartesian Gaussian functions. At low densities, the electrons become relatively localized into Wigner crystals, and the natural SGF centers are found by solving the Thomson problem (i.e. the minimum-energy arrangement of nn point charges) on the 3-sphere for various values of nn. We have found 11 special values of nn whose Thomson sites are equivalent. Three of these are the vertices of four-dimensional Platonic solids --- the hyper-tetrahedron (n=5n=5), the hyper-octahedron (n=8n=8) and the 24-cell (n=24n=24) --- and a fourth is a highly symmetric structure (n=13n=13) which has not previously been reported. By calculating the harmonic frequencies of the electrons around their equilibrium positions, we also find the first-order vibrational corrections to the Thomson energy.Comment: 6 pages, 2 figures, accepted for publication in the Journal of Chemical Physic

    Invasive oysters as new hosts for native shell-boring polychaetes: Using historical shell collections and recent field data to investigate parasite spillback in native mussels in the Dutch Wadden Sea

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    Biological invasions can have manifold effects on native biota, including impacts on species interactions in invaded ecosystems. Among those are effects on parasite-host interactions, for example in cases where invaders serve as a new host for native parasites, leading to an amplification of the parasite population which may ultimately result in increased infection levels in the original native hosts (parasite spillback). In this study, we investigated the potential spillback of the native shell-boring polychaete Polydora ciliata from invasive Pacific oysters (Crassostrea (Magallana) gigas) to native mussels (Mytilus edulis) in the Dutch Wadden Sea. A field survey in the intertidal revealed that the majority of P. ciliata can nowadays be found in the shells of live but also dead Pacific oysters and much less in shells of other potential host species: mussels and periwinkles (Littorina littorea). Using a unique historical shell collection based on long-term sampling programmes in the intertidal and subtidal of the western Dutch Wadden Sea, we compared P. ciliata infections in mussels before and after the invasion of the Pacific oyster by means of x-ray scans. Both for the intertidal and subtidal, we did not detect differences in prevalence of P. ciliata in mussels between pre- and post-invasion periods. This suggests that the invasion of the Pacific oyster may not have caused a strong spillback to mussels regarding P. ciliata and thus the invasion probably had little indirect infection-mediated effects on the condition and fitness of native mussels. Instead, the acquisition of native P. ciliata by the invasive oysters suggests that they may themselves be affected by the new infections and this may warrant further research

    A Continuous Battle for Host-Derived Glycans Between a Mucus Specialist and a Glycan Generalist in vitro and in vivo

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    The human gastrointestinal tract is colonized by a diverse microbial community, which plays a crucial role in human health. In the gut, a protective mucus layer that consists of glycan structures separates the bacteria from the host epithelial cells. These host-derived glycans are utilized by bacteria that have adapted to this specific compound in the gastrointestinal tract. Our study investigated the close interaction between two distinct gut microbiota members known to use mucus glycans, the generalist Bacteroides thetaiotaomicron and the specialist Akkermansia muciniphila in vitro and in vivo. The in vitro study, in which mucin was the only nutrient source, indicated that B. thetaiotaomicron significantly upregulated genes coding for Glycoside Hydrolases (GHs) and mucin degradation activity when cultured in the presence of A. muciniphila. Furthermore, B. thetaiotaomicron significantly upregulated the expression of a gene encoding for membrane attack complex/perforin (MACPF) domain in co-culture. The transcriptome analysis also indicated that A. muciniphila was less affected by the environmental changes and was able to sustain its abundance in the presence of B. thetaiotaomicron while increasing the expression of LPS core biosynthesis activity encoding genes (O-antigen ligase, Lipid A and Glycosyl transferases) as well as ABC transporters. Using germ-free mice colonized with B. thetaiotaomicron and/or A. muciniphila, we observed a more general glycan degrading profile in B. thetaiotaomicron while the expression profile of A. muciniphila was not significantly affected when colonizing together, indicating that two different nutritional niches were established in mice gut. Thus, our results indicate that a mucin degrading generalist adapts to its changing environment, depending on available carbohydrates while a mucin degrading specialist adapts by coping with competing microorganism through upregulation of defense related genes.Peer reviewe

    A novel mutation in PTHLH in a family with a variable phenotype with brachydactyly, short stature, oligodontia and developmental delay

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    Mutations in PTHLH (PTH-like hormone), cause brachydactyly type E (BDE) characterized by shortening of metacarpals, metatarsals and/or phalanges with short stature. In this report we describe three siblings and their mother with a novel heterozygous mutation c.25 T &gt; C, p.Trp9Arg in exon 2 of the PTHLH gene. Beside the known clinical features of PTHLH mutations all had a delay in speech and language development, unknown if this is related to the mutation. Patients with PTHLH mutation may have a variable phenotypic presentation.</p

    Influenza vaccination of hospital healthcare staff from the perspective of the employer:a positive balance

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    OBJECTIVE: To assess the annual productivity loss among hospital healthcare workers attributable to influenza and to estimate the costs and economic benefits of a vaccination programme from the perspective of the the employer.DESIGN: Cost-benefit analysis.METHODS: The percentage of work loss due to influenza was determined using monthly age and gender specific figures for productivity loss among healthcare workers of the University Medical Center Groningen (UMCG), the Netherlands over the period January 2006-June 2008. Influenza periods were determined on the basis of national surveillance data. The average increase in productivity loss in these periods was estimated by comparison with the periods outside influenza seasons. The direct costs of productivity loss from the perspective of the employer were estimated using the friction cost method. In the sensitivity analyses various modelling parameters were varied, such as the vaccination coverage.RESULTS: In the UMCG, with approximately 9,400 employees, the estimated annual costs associated with productivity loss due to influenza before the introduction of the yearly influenza vaccination program were € 675,242 or on average, € 72 per employee. The economic benefits of the current vaccination program with a vaccination coverage of 24% with a vaccine effectiveness of 71% were estimated at € 89,858 or € 10 per employee. The nett economic benefits of a vaccination program with a target vaccination coverage of 70% with a vaccine effectiveness of 71% were estimated at € 244,325 or € 26 per employee.CONCLUSION: This modelling study performed from the perspective of the employer showed that an annual influenza vaccination programme for hospital personnel can save costs.</p

    Конференции

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    Background Polypharmacy poses threats to patients’ health. The Systematic Tool to Reduce Inappropriate Prescribing (STRIP) is a drug optimization process for conducting medication reviews in primary care. To effectively and efficiently incorporate this method into daily practice, the STRIP Assistant—a decision support system that aims to assist physicians with the pharmacotherapeutic analysis of patients’ medical records—has been developed. It generates context-specific advice based on clinical guidelines. Objective The aim of this study was to validate the STRIP Assistant’s usability as a tool for physicians to optimize medical records for polypharmacy patients. Methods In an online experiment, 42 physicians were asked to optimize medical records for two comparable polypharmacy patients, one in their usual manner and one using the STRIP Assistant. Changes in effectiveness were measured by comparing respondents’ optimized medicine prescriptions with medication prepared by an expert panel of two geriatrician-pharmacologists. Efficiency was operationalized by recording the time the respondents took to optimize the two cases. User satisfaction was measured with the System Usability Scale (SUS). Independent and paired t tests were used for analysis. Results Medication optimization significantly improved with the STRIP Assistant. Appropriate decisions increased from 58 % without the STRIP Assistant to 76 % with it (p < 0.0001). Inappropriate decisions decreased from 42 % without the STRIP Assistant to 24 % with it (p < 0.0001). Participants spent significantly more time optimizing medication with the STRIP Assistant (24 min) than without it (13 min; p < 0.0001). They assigned it a below-average SUS score of 63.25. Conclusion The STRIP Assistant improves the effectiveness of medication reviews for polypharmacy patients
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