882 research outputs found
Load rating of the stone arch bridge at Poniklá using 2D and 3D models.
Zděné klenbové mosty jsou jedinečnou a důležitou částí světové silniční sítě. Mnohé byly postaveny před více než 100 lety a od té doby měnící se dopravní zátěž vyžaduje obnovení informací o jejich bezpečnosti. Zatížitelnost mostu určuje jeho přípustné zatížení k ověření bezpečnosti a v normách a směrnicích existují metody k jejímu stanovení. Platí to pro ocelové, železobetonové a dřevěné mosty ale pro zděné klenbové mosty není přijata žádná konsistentní metoda. Práce nejprve identifikuje existující metody a sofware použitelné k určení zatížitelnosti zděných klenbových mostů. Lze je shrnout do těchto kategorií: normy, semiempirické metody, metody založené na mezní únosnosti a numerické metody. Mnohé z nich používají jednodušší 2D modely místo 3D modelů protože nelineární 3D výpočet je mnohem obtížnější a dražší. Třídimensionální podstata mostů se často nerespektuje a příčné efekty se zanedbávají . V tomto kontextu je cílem práce je poskytnout opravné koeficienty pro 2D nelineární výpočty které pokryjí odchylky v příčném směru v případové studii mostu v Poniklé v severních Čechách v České republice.M odely jsou vytvořeny v software RFEM. Kompletní je analýza v lineárně pružném režimu při nesymetrickém zatížení. Opravné faktory jsou vypočteny pro několik příčných řezů podél rozpětí jednoho pole, kde mohou vzniknout mechanismy. Byla provedena analýza senzitivity na změny materiálovýchparametrů k ověření konsistence výsledků. Konečným cílem disertace je použít tento přístup na 2D nelineární model vytvořený v nekomerčním software stavební fakulty ČVUT a poskytnout aktualizovanou zatížitelnost zděného klenbového mostu v Poniklé. Rozšíření znalostí o očekávaných rozdílech mezi 2D a3D modely může pomoci vytvořit přesnější modely zatížitelnosti a snížit nároky na vstupní data. Je tedy naším zájmem porozumět rozdílům mezi 2D a 3D modely. Hlavním cílem diplomové práce je srovnat tyto rozdíly na případu mostu v Poniklé v severních Čechách v České republice.Masonry arch bridges are a unique and important part of the world’s bridge stock. Many were built over 100 years ago, and in that time changing traffic patterns and loading conditions require updated information of their current usage. Bridge load rating is the method of determining the load carrying capacity of all bridges, to verify safety, and methods exist in codes that can be applied. However, the applicability of these load rating techniques is limited to steel, reinforced concrete, and timber bridges. For masonry arch bridges, no one method is adopted consistently to examine these bridges. The work herein presented, first identifies all of the methods and software that exist in order to determine the load rating of masonry arch bridges. Load rating methods typically fall under the following categories: codes, semi-empirical methods, limit analysis-based methods, and numerical methods. Many of these methods utilize 2D models instead of 3D models, as it is much more difficult and expensive to perform a nonlinear 3D analysis. The intrinsic nature of bridges in three-dimensions is often not considered, disregarding any transverse effect due to their components. In this context, the primary objective of this thesis is to provide correction factors for nonlinear 2D solutions which cover the transverse fluctuations the case study of the Poniklá Bridge located in Bohemia in the Czech Republic. Models are created in the software RFEM. The analysis completed is linear elastic under unsymmetrical live loading. Correction factors are calculated at locations along the span of the arch where possible failure mechanisms can be created. A sensitivity analysis of material properties was carried out to validate the model. The final objective of this thesis is to apply this approach to a 2D nonlinear model, created using a non-commercial software designed in the CTU Faculty of Civil Engineering, and to provide an updated load rating for the masonry arch bridge at Poniklá. The growth of knowledge regarding the expected difference between 2D and 3D models can help to make load rating models more accurate and easier to carry out with less input data
Social Distance and Reciprocity
Contrary to the predictions of non-cooperative game theory, trust and reciprocity are commonly reported in simple games. We conduct a one-shot investment game to examine how social distance affects behavior in two-person exchanges. Two aspects of social distance are examined: ex post revelation of complete information on the second playerâ??s choice set and ex post revelation of information regarding the second playerâ??s identity. The results indicate that reciprocity is not affected by knowledge of the choice set, but depends critically on the possible revelation of the decision makerâ??s identity. That is, the possibility that the second playerâ??s identity (picture) is revealed to his/her counterpart has a profound effect on the degree of reciprocity extended.
Rescue of a stone bridge with respect to current condition and standards
A three span stone masonry bridge dating back to the middle of the 19th century, still in the roadway network, is assessed to prevent its demolition. Its industrial heritage value and ecological concerns were the principal reasons for the assessment. The carbon footprint of the stone arch replacement would be approximately 200 t CO2 emission owing to 430 m3 reinforced concrete in the new structure. Besides the cultural monument, considerable energy, CO2 emissions and natural resources can be saved in accordance with the sustainable development goals. Standards, guides and commercial software do not provide an adequate support for the assessment of masonry arch bridges, therefore an innovative two phase application of a commercial linear sttructural analysis code and an original in-house code was developed for the purpose. Thousands of stone ach bridges still in service worlwide give the case study more general importance
Social Distance and Reciprocity
Contrary to the predictions of non-cooperative game theory, trust and reciprocity are commonly reported in simple games. We conduct a one-shot investment game to examine how social distance affects behavior in two-person exchanges. Two aspects of social distance are examined: ex post revelation of complete information on the second player’s choice set and ex post revelation of information regarding the second player’s identity. The results indicate that reciprocity is not affected by knowledge of the choice set, but depends critically on the possible revelation of the decision maker’s identity. That is, the possibility that the second player’s identity (picture) is revealed to his/her counterpart has a profound effect on the degree of reciprocity extended
An evaluation of post-production facial composite enhancement techniques
Purpose: This article describes four experiments evaluating post-production enhancement techniques with facial composites mainly created using the EFIT-V holistic system.
Design/methodology/approach: Each experiment was conducted in two stages. In Stage 1, constructors created between one and four individual composites of unfamiliar targets. These were merged to create morphs, and in Experiment 3, composites were also vertically stretched. In Stage 2, participants familiar with the targets named or provided target-similarity ratings to the images.
Findings: In Experiments 1-3, correct naming rates were significantly higher to between-witness 4-morphs, within-witness 4-morphs and vertically stretched composites than to individual composites. In Experiment 4, there was a positive relationship between composite-target similarity ratings and between-witness morph-size (2-, 4-, 8-, 16-morphs).
Practical implications: The likelihood of a facial composite being recognised can be improved by morphing and vertical stretch.
Originality/value: A greater understanding of the theoretical underpinnings and applied advantage of post-production facial composite techniques should ensure greater acceptance by the criminal justice system, leading to better detection outcomes
The Effect of Low Temperature Laundering and Detergents on the Survival of Escherichia coli and Staphylococcus aureus on Textiles Used in Healthcare Uniforms
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Aims: To determine the survival of Escherichia coli and Staphylococcus aureus on cotton and polyester and the effectiveness of low temperature laundering and detergents on the removal of microorganism from healthcare laundry.
Methods and Results: Survival of E. coli and S. aureus on polyester or cotton was assessed over 3 weeks and the efficacy of a domestic wash (40°C and 60°C) and a range of detergents was also determined. Both bacteria were able to survive on cotton (5 log(10)) and polyester (0.28 log(10)) for up to 3 weeks. Laundering at 40°C resulted in a 3.5 log(10) removal of the initial 7.7 log(10) inoculum and some cross contamination to sterile fabrics (3 log(10). Increasing the temperature to 60°C resulted in the complete removal of the initial inoculum.
Conclusions: This study shows that most of the microorganisms are removed at 40°C however, those cells still remaining may have the potential for further contamination to the clinical environment and patients
Significance and Impact of Study: National Health Service (NHS) nurses are required to domestically launder their uniforms at 60°C to ensure safe removal of microorganisms, 33% of NHS staff questioned said they launder their uniforms at 40°C, which could potentially result in transmission of Hospital Acquired Infections (HAIs)
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Point-of-care C-reactive protein-based tuberculosis screening for people living with HIV: a diagnostic accuracy study.
BackgroundSymptom-based screening for tuberculosis is recommended for all people living with HIV. This recommendation results in unnecessary Xpert MTB/RIF testing in many individuals living in tuberculosis-endemic areas and thus poor implementation of intensified case finding and tuberculosis preventive therapy. Novel approaches to tuberculosis screening are needed to help achieve global targets for tuberculosis elimination. We assessed the performance of C-reactive protein (CRP) measured with a point-of-care assay as a screening tool for active pulmonary tuberculosis.MethodsFor this prospective study, we enrolled adults (aged ≥18 years) living with HIV with CD4 cell count less than or equal to 350 cells per μL who were initiating antiretroviral therapy (ART) from two HIV/AIDS clinics in Uganda. CRP concentrations were measured at study entry with a point-of-care assay using whole blood obtained by fingerprick (concentration ≥10 mg/L defined as screen positive for tuberculosis). Sputum samples were collected for Xpert MTB/RIF testing and culture. We calculated the sensitivity and specificity of point-of-care CRP and WHO symptom-based screening in reference to culture results. We repeated the sensitivity analysis with Xpert MTB/RIF as the reference standard.FindingsBetween July 8, 2013, and Dec 15, 2015, 1237 HIV-infected adults were enrolled and underwent point-of-care CRP testing. 60 (5%) patients with incomplete or contaminated cultures were excluded from the analysis. Of the remaining 1177 patients (median CD4 count 165 cells per μL [IQR 75-271]), 163 (14%) had culture-confirmed tuberculosis. Point-of-care CRP testing had 89% sensitivity (145 of 163, 95% CI 83-93) and 72% specificity (731 of 1014, 95% CI 69-75) for culture-confirmed tuberculosis. Compared with WHO symptom-based screening, point-of-care CRP testing had lower sensitivity (difference -7%, 95% CI -12 to -2; p=0·002) but substantially higher specificity (difference 58%, 95% CI 55 to 61; p<0·0001). When Xpert MTB/RIF results were used as the reference standard, sensitivity of point-of-care CRP and WHO symptom-based screening were similar (94% [79 of 84] vs 99% [83 of 84], respectively; difference -5%, 95% CI -12 to 2; p=0·10).InterpretationThe performance characteristics of CRP support its use as a tuberculosis screening test for people living with HIV with CD4 count less than or equal to 350 cells per μL who are initiating ART. HIV/AIDS programmes should consider point-of-care CRP-based tuberculosis screening to improve the efficiency of intensified case finding and increase uptake of tuberculosis preventive therapy.FundingNational Institutes of Health; President's Emergency Plan for AIDS Relief; University of California, San Francisco, Nina Ireland Program for Lung Health
Linguistic Structures and Economic Outcomes
Linguistic structures have recently started to attract attention from economists as determinants of economic phenomena. This paper provides the first comprehensive review of this nascent literature and its achievements so far. First, we explore the complex connections between language, culture, thought and behaviour. Then, we summarize the empirical evidence on the relationship between linguistic structures and economic and social outcomes. We follow up with a discussion of data, empirical design and identification. The paper concludes by discussing implications for future research and policy
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