1,862 research outputs found

    Enabling Future Sustainability Transitions: An Urban Metabolism Approach to Los Angeles Pincetl et al. Enabling Future Sustainability Transitions

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    Summary: This synthesis article presents an overview of an urban metabolism (UM) approach using mixed methods and multiple sources of data for Los Angeles, California. We examine electric energy use in buildings and greenhouse gas emissions from electricity, and calculate embedded infrastructure life cycle effects, water use and solid waste streams in an attempt to better understand the urban flows and sinks in the Los Angeles region (city and county). This quantification is being conducted to help policy-makers better target energy conservation and efficiency programs, pinpoint best locations for distributed solar generation, and support the development of policies for greater environmental sustainability. It provides a framework to which many more UM flows can be added to create greater understanding of the study area's resource dependencies. Going forward, together with policy analysis, UM can help untangle the complex intertwined resource dependencies that cities must address as they attempt to increase their environmental sustainability

    Pathogenicity locus, core genome, and accessory gene contributions to Clostridium difficile virulence

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    Clostridium difficile is a spore-forming anaerobic bacterium that causes colitis in patients with disrupted colonic microbiota. While some individuals are asymptomatic C. difficile carriers, symptomatic disease ranges from mild diarrhea to potentially lethal toxic megacolon. The wide disease spectrum has been attributed to the infected host’s age, underlying diseases, immune status, and microbiome composition. However, strain-specific differences in C. difficile virulence have also been implicated in determining colitis severity. Because patients infected with C. difficile are unique in terms of medical history, microbiome composition, and immune competence, determining the relative contribution of C. difficile virulence to disease severity has been challenging, and conclusions regarding the virulence of specific strains have been inconsistent. To address this, we used a mouse model to test 33 clinical C. difficile strains isolated from patients with disease severities ranging from asymptomatic carriage to severe colitis, and we determined their relative in vivo virulence in genetically identical, antibiotic-pretreated mice. We found that murine infections with C. difficile clade 2 strains (including multilocus sequence type 1/ribotype 027) were associated with higher lethality and that C. difficile strains associated with greater human disease severity caused more severe disease in mice. While toxin production was not strongly correlated with in vivo colonic pathology, the ability of C. difficile strains to grow in the presence of secondary bile acids was associated with greater disease severity. Whole-genome sequencing and identification of core and accessory genes identified a subset of accessory genes that distinguish high-virulence from lower-virulence C. difficile strains

    ProFlex: A Probabilistic and Flexible Data Storage Protocol for Heterogeneous Wireless Sensor Networks

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    This paper presents ProFlex, a proactive data distribution protocol for heterogeneous wireless sensor networks (HWSNs). ProFlex guarantees robustness in data retrieval by intelligently managing data replication among selected storage nodes in the network. Contrarily to related protocols in the literature, ProFlex considers the resource constraints of sensor nodes and constructs multiple data replication structures, which are managed by more powerful nodes. Additionally, ProFlex takes profit of the higher communication range of such powerful nodes in the network and use the long link to improve data distribution. When compared with Supple -- a related protocol, we show by simulation that Proflex increases the network resilience under failures circumstances, decreases the overhead of transmitted messages, and decreases the number of hops to find a specific data in the network.Cet article porte sur la proposition d'un protocole de données proactif de distribution pour les réseaux de capteurs sans fil hétérogènes (HWSNs). Notre protocole, ProFlex, garantit la robustesse de la récupération des données grâce à sa gestion intelligente de la réplication des données entre les nœuds de stockage sélectionnés dans le réseau. Contrairement à d'autres protocoles dans la littérature, ProFlex considère les contraintes de ressources de capteurs et construit plusieurs structures de réplication des données, qui sont gérés par des nœuds plus puissants. En outre, ProFlex profite de la meilleure communication radio de ces nœuds plus puissants et utilise ces longues portée pour améliorer la distribution des données. Nous avons comparé ProFlex avec le protocole Supple et nous avons montré par simulation que Proflex augmente la résilience du réseau, même dans des circonstances des pertes de messages, diminue la surcharge de messages transmis, et diminue le nombre de sauts nécessaire pour trouver un ensemble de données spécifiques dans le réseau

    Integration of external and internal dosimetry in Switzerland

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    Individual monitoring regulations in Switzerland are based on the ICRP60 recommendations. The annual limit of 20 mSv for the effective dose applies to the sum of external and internal radiation. External radiation is monitored monthly or quarterly with TLD, DIS or CR-39 dosemeters by 10 approved external dosimetry services and reported as Hp(10) and Hp(0.07). Internal monitoring is done in two steps. At the workplace, simple screening measurements are done frequently in order to recognise a possible incorporation. If a nuclide dependent activity threshold is exceeded then one of the seven approved dosimetry services for internal radiation does an incorporation measurement to assess the committed effective dose E50. The dosimetry services report all the measured or assessed dose values to the employer and to the National Dose Registry. The employer records the annually accumulated dose values into the individual dose certificate of the occupationally exposed person, both the external dose Hp(10) and the internal dose E50 as well as the total effective dose E = Hp(10)+E50. Based on the national dose registry an annual report on the dosimetry in Switzerland is published which contains the statistics for the total effective dose, as well as separate statistics for external and internal exposur

    Few smooth d-polytopes with n lattice points

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    We prove that, for fixed n there exist only finitely many embeddings of Q-factorial toric varieties X into P^n that are induced by a complete linear system. The proof is based on a combinatorial result that for fixed nonnegative integers d and n, there are only finitely many smooth d-polytopes with n lattice points. We also enumerate all smooth 3-polytopes with at most 12 lattice points. In fact, it is sufficient to bound the singularities and the number of lattice points on edges to prove finiteness.Comment: 20+2 pages; major revision: new author, new structure, new result

    Systematics, fishery and biology of the white sardine Escualosa thoracata (Valenciennes, 1847) exploited off Kerala, south-west coast of India

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    Landings of the white sardine Escualosa thoracata (Valenciennes, 1847) indicated a shift in their abundance from north-east to south-west coast of India and a sharp decline in the resource landings during the last decade along the entire range of its distribution. High local demand coupled with competitive price for the species might have led to overexploitation of this otherwise seasonal resources along the major areas of its abundance along the Indian coast. Detailed study on the systematics, fishery and biology of the species landed along Kerala coast was undertaken during 2015 and 2016. Stock assessment studies indicated near optimum fishing pressure on the resource along the Kerala coast

    Structure and regeneration status of mangrove patches along the estuarine and coastal stretches of Kerala, India

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    This study presents the structural characteristics and regeneration potential of mangrove patches in the estuarine and coastal areas of Kerala, a tropical maritime state in India. Field surveys were carried out at 46 selected sites during August 2015 to May 2016. In each site, the vegetative structure and regeneration status were assessed using the quadrat method. Altogether 219 quadrates were laid out and a total of 13 true mangrove species, belonging to 5 families and 8 genera, were recorded. The total tree density and stand basal area of the study region was 1678.08/ha and 20.33 m2/ha respectively. The low basal areas indicate the reduced structural development in mangroves. Of the 13 tree species, Avicennia constitutes 56% of the total Important Value Index (IVI) and Avicennia officinalis represents 41% of the IVI in Kerala, followed by Avicennia marina (15%), Rhizophora mucronata (15%), Sonneratia alba (8%) Rhizophora apiculata (7%) and Excoecaria agallocha (7%). The diameter at breast height (DBH) in the study area revealed that 47% of the tree species came under the 1–10 cm DBH class. Total sapling and seedling density in Kerala was 2238.35 and 3232.42 individuals/ha respectively. Density of young plants (seedlings ? saplings) was only 31% greater of tree density and varied from 3–63%, which indicates poor regeneration potential. The Maturity index value (MIV) and complexity index (Ic) value of mangroves were 18.30 and 109.81 respectively. However, the low Ic value (\10) observed in seven out of ten coastal districts indicated poor structural development of mangroves in Kerala. Therefore, locationspecific conservation and management measures, guided by the knowledge on spatial distribution and habitat requirements of mangrove varieties should be taken to preserve the mangrove diversity of Kerala
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