314 research outputs found

    Biopolymers impact on hygrothermal properties of rammed earth: from material to building scale

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    Three biopolymers were tested as rammed earth (RE) stabilizers, evaluating their impact on the hygrothermal behavior from material to building scale. Hygrothermal characterization included the determination of sorption isotherm, water vapor permeability, thermal conductivity at different moisture content, and specific heat capacity. The hygrothermal data were used as input for the simulation at whole-building scale considering combined heat and moisture transfer. The results were evaluated by comparing heating demand, thermal comfort during summer, and the contribution of walls for passively controlling indoor humidity. The results show that hygric properties were only slightly affected by the use of stabilizers, while the thermal conductivity was 33% higher for RE stabilized with lignin, consequently increasing the heating demand at whole-building scale. All RE walls were effective in reducing temperature oscillations in summer. In the particular case of a canicular event, the indoor temperature was reduced by up to 10° compared with the outdoor value. The indoor humidity also benefited from the passive regulation by RE walls, regardless of whether a stablizer was used

    Mechanical and Microstructural Characterization of Rammed Earth Stabilized with Five Biopolymers

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    This study aims to check the compatibility of a selection of waste and recycled biopolymers for rammed earth applications in order to replace the more common cement-based stabilization. Five formulations of stabilized rammed earth were prepared with different biopolymers: lignin sulfonate, tannin, sheep wool fibers, citrus pomace and grape-seed flour. The microstructure of the different formulations was characterized by investigating the interactions between earth and stabilizers through mercury intrusion porosimetry (MIP), nitrogen soprtion isotherm, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The unconfined compressive strength (UCS) was also evaluated for all stabilized specimens. Three out of five biopolymers were considered suitable as rammed earth stabilizers. The use of wool increased the UCS by 6%, probably thanks to the combined effect of the length of the fibers and the roughness of their surfaces, which gives a contribution in binding clay particles higher than citrus and grape-seed flour. Lignin sulfonate and tannin increased the UCS by 38% and 13%, respectively, suggesting the additives’ ability to fill pores, coat soil grains and form aggregates; this capability is confirmed by the reduction in the specific surface area and the pore volume in the nano-and micropore zones

    "Outside, it is snowing": Experience and finitude in the nonrepresentational landscapes of Alain Robbe-Grillet

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    Copyright © 2008 PionRomanillos J L, 2008. The definitive, peer-reviewed and edited version of this article is published in Environment and Planning D: Society and Space 26(5) 795 – 822 DOI: 10.1068/d6207This paper presents and explicates the anonymous and impersonal spatialities tentatively mapped in the novels of Alain Robbe-Grillet. Emerging from the kinds of landscapes and visualities articulated, these spatialities are at odds with the kind of anthropocentrism characteristic of phenomenological narratives of spatial experience that would start from an apparently stable human-subject position. It is argued that his body of literature dismantles the anthropocentric narratives and biographies that would produce in both the space of the world and the ‘phenomenological subject’ an unwarranted depth and naturalism. Importantly, and reflecting the theoretical turn towards the being of language, Robbe-Grillet questions the legitimacy of linguistic subjects to capture the spaces of the visible. As such, it is argued that his literature reflects an experience of the critiques of phenomenology. Importantly, this ‘critique’ goes hand in hand with the kinds of spatialities and landscapes that are rendered in the novels—the indefinite perspectives they open up, the paradoxical visualities they sustain or deny, and the disorientation they inject into the heart of spatial experience. These literary effects produce a nonanthropocentric and nonpersonal spatiality which, although contributing to an erasure of the ‘subject’, at the same time expose and open up a sociospatiality based on singularities, intensities, and finitude

    Chalcogenide Glasses for All-optical Processing

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    Copyright © 2006 IEEEChalcogenide glasses, which contain S, Se or Te atoms combined with network forming elements such as Ge, As, Sb have the largest third order optical nonlinearity of any inorganic glass. As a result they are attractive candidates for fibre and waveguide devices for all-optical signal processing in the telecommunications bands. In this talk I will review our recent progress in all-optical devices such as regenerators, wavelength converters and other devices in chalcogenide glasses.B. Luther-Davies, S. J. Madden, D-Y Choi, R-P Wang, A. V. Rode, A. Prasad, R. A. Jarvis, D. Moss, B. Eggleton, C. Grillet, M. R. E. Lamont, E. Magi, V. Ta’eed, M. Shookooh-Saremi, N. Baker, I. Littler, L. Fu, M. Rochette, Y. Rua

    Status of the CMS magnet (MT17)

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    The CMS experiment (Compact Muon Solenoid) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with a free bore of 6 m diameter and 12.5-m length, enclosed inside a 10 000-ton return yoke. The magnet will be assembled and tested in a surface hall at Point 5 of the LHC at the beginning of 2004 before being transferred by heavy lifting means to an experimental hall 90 m below ground level. The design and construction of the magnet is a common project of the CMS Collaboration. The task is organized by a CERN based group with strong technical and contractual participation from CEA Saclay, ETH Zurich, Fermilab, INFN Genova, ITEP Moscow, University of Wisconsin and CERN. The magnet project will be described, with emphasis on the present status of the fabrication. (15 refs)

    Is there a dark decay of neutrons in 6^6He ?

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    Motivated by the four standard deviations discrepancy between the mean values for the neutron lifetime obtained from beam and bottle experiments, we have searched for a hypothetical neutron dark decay in 6^6He nuclei through the channel 6He4He+n+χ^6{\rm He} \rightarrow ^4{\rm He}+n+\chi. The experiment used a 25~keV high intensity 6^6He+^+ beam with a high efficiency neutron detector. The search for a signal correlated with the 6^6He activity in the neutron detection rate resulted in a branching ratio Brχ4.0×1010{\rm Br}_\chi \leq 4.0\times10^{-10} with a 95\% C.L. over the mass window 937.993<mχ<mn0.975937.993 < m_\chi < m_n-0.975 MeV. This result is five orders of magnitude smaller than required to solve the neutron lifetime discrepancy

    Resurgence of vaccine-preventable diseases in Venezuela as a regional public health threat in the Americas

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    Venezuela’s tumbling economy and authoritarian rule have precipitated an unprecedented humanitarian crisis. Hyperinflation rates now exceed 45,000%, and Venezuela’s health system is in free fall. The country is experiencing a massive exodus of biomedical scientists and qualified healthcare professionals. Reemergence of arthropod-borne and vaccine-preventable diseases has sparked serious epidemics that also affect neighboring countries. In this article, we discuss the ongoing epidemics of measles and diphtheria in Venezuela and their disproportionate impact on indigenous populations. We also discuss the potential for reemergence of poliomyelitis and conclude that action to halt the spread of vaccine-preventable diseases within Venezuela is a matter of urgency for the country and the region. We further provide specific recommendations for addressing this crisis. © 2019 Centers for Disease Control and Prevention (CDC). All rights reserved

    First wave of COVID-19 in Venezuela:Epidemiological, clinical, and paraclinical characteristics of first cases

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    The coronavirus disease 2019 (COVID-19) pandemic has particularly affected countries with weakened health services in Latin America, where proper patient management could be a critical step to address the epidemic. In this study, we aimed to characterize and identify which epidemiological, clinical, and paraclinical risk factors defined COVID-19 infection from the first confirmed cases through the first epidemic wave in Venezuela. A retrospective analysis of consecutive suspected cases of COVID-19 admitted to a sentinel hospital was carried out, including 576 patient cases subsequently confirmed for severe acute respiratory syndrome coronavirus 2 infection. Of these, 162 (28.1%) patients met the definition criteria for severe/critical disease, and 414 (71.2%) were classified as mild/moderate disease. The mean age was 47 (SD 16) years, the majority of which were men (59.5%), and the most frequent comorbidity was arterial hypertension (23.3%). The most common symptoms included fever (88.7%), headache (65.6%), and dry cough (63.9%). Severe/critical disease affected mostly older males with low schooling (p < 0.001). Similarly, higher levels of glycemia, urea, aminotransferases, total bilirubin, lactate dehydrogenase, and erythrocyte sedimentation rate were observed in severe/critical disease patients compared to those with mild/moderate disease. Overall mortality was 7.6% (44/576), with 41.7% (28/68) dying in hospital. We identified risk factors related to COVID-19 infection, which could help healthcare providers take appropriate measures and prevent severe clinical outcomes. Our results suggest that the mortality registered by this disease in Venezuela during the first epidemic wave was underestimated. An increase in fatalities is expected to occur in the coming months unless measures that are more effective are implemented to mitigate the epidemic while the vaccination process is ongoing

    Modelling malaria treatment practices in Bangladesh using spatial statistics

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    <p>Abstract</p> <p>Background</p> <p>Malaria treatment-seeking practices vary worldwide and Bangladesh is no exception. Individuals from 88 villages in Rajasthali were asked about their treatment-seeking practices. A portion of these households preferred malaria treatment from the National Control Programme, but still a large number of households continued to use drug vendors and approximately one fourth of the individuals surveyed relied exclusively on non-control programme treatments. The risks of low-control programme usage include incomplete malaria treatment, possible misuse of anti-malarial drugs, and an increased potential for drug resistance.</p> <p>Methods</p> <p>The spatial patterns of treatment-seeking practices were first examined using hot-spot analysis (Local Getis-Ord Gi statistic) and then modelled using regression. Ordinary least squares (OLS) regression identified key factors explaining more than 80% of the variation in control programme and vendor treatment preferences. Geographically weighted regression (GWR) was then used to assess where each factor was a strong predictor of treatment-seeking preferences.</p> <p>Results</p> <p>Several factors including tribal affiliation, housing materials, household densities, education levels, and proximity to the regional urban centre, were found to be effective predictors of malaria treatment-seeking preferences. The predictive strength of each of these factors, however, varied across the study area. While education, for example, was a strong predictor in some villages, it was less important for predicting treatment-seeking outcomes in other villages.</p> <p>Conclusion</p> <p>Understanding where each factor is a strong predictor of treatment-seeking outcomes may help in planning targeted interventions aimed at increasing control programme usage. Suggested strategies include providing additional training for the Building Resources across Communities (BRAC) health workers, implementing educational programmes, and addressing economic factors.</p
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