Efficient single-step time-dependent analysis of PC structures

This paper describes an efficient single-step method to predict the time-dependent behaviour of prestressed concrete (PC) structures due to concrete creep, concrete shrinkage and cable relaxation. A versatile tendon sub-element is first developed to model prestressing cables of arbitrary profiles. To enable accurate estimation of losses of cable forces, a new relaxation model is formulated based on the equivalent creep coefficient, which is verified to work not only in the case of intrinsic relaxation but also under various boundary conditions. An efficient single-step finite-element method is then devised for time-dependent analysis of PC structures considering creep, shrinkage and relaxation based on the age-adjusted elasticity modulus, shrinkage-adjusted elasticity modulus and relaxation-adjusted elasticity modulus respectively. The effects of creep, shrinkage and relaxation on the long-term performance of PC structures are investigated. The numerical results obtained indicate not only the accuracy of the method but also the significance of considering the interaction among various time-varying factors.published_or_final_versio

Will CARICOM countries be vulnerable to financial crises as a result of the Economic Partnership Agreement (EPA): the Cotonou Agreement?

Whether the EPA contains the seeds of potential financial crises in relation to the CARICOM countries, using the concepts of globalisation, volatility risk and hubris (of leadership, economic thought and a weak regulatory environment). This study seeks to establish whether financial crises may occur when the variables of globalisation, volatility risk and hubris within a weak regulatory environment coincide within the framework of the Economic Partnership Agreement between the ACP countries, (in particular the CARICOM countries) and the EU (the Cotonou Agreement). Ultimately it is the intention to assess whether there is any association between these factors to determine if when combined we can anticipate the likely occurrence of financial crises. A number of research hypotheses were derived from the review of the literature in Documents 2 and 3. The evidence presented in Document 4 did not support the null hypotheses and allowed us to conclude that there is a statistical association among globalisation, volatility risk and hubris. In conclusion, we explore the attitudes of key sectors with respect to the EPA economic framework and proffer that a likely combination of these three variables may contribute to the occurrence of financial crises. Furthermore it is the author’s contention that the Cotonou Agreement may contain the ingredients to usher in another financial crisis

Experimental and numerical investigation of post-tensioned concrete flat slabs in fire

Session 1A: Concrete Structures (I)Tests of four post-tensioned high-strength self-compacting concrete flat slab specimens have been conducted under fire condition. Tendon distributions including distributed-distributed and banded-distributed patterns as well as various loading ratios were considered. Two of the specimens with lower moisture contents demonstrated excellent fire resistance performance, while the others with relatively high moisture contents experienced severe concrete spalling. The test results obtained from the tests are presented and discussed with respect to temperature distributions, deflections, crack patterns and concrete spalling. Moreover, numerical modelling employing the package ABAQUS has been conducted to help interpret the test results in order to get better understanding of slabs in fire.postprin

First trimester maternal tryptophan metabolism and embryonic and fetal growth:the Rotterdam Periconceptional Cohort (Predict Study)

STUDY QUESTION: What is the association between first trimester maternal tryptophan (TRP) metabolites and embryonic and fetal growth? SUMMARY ANSWER: Higher 5-hydroxytryptophan (5-HTP) concentrations are associated with reduced embryonic growth and fetal growth and with an increased risk of small-for-gestational age (SGA), while higher kynurenine (KYN) concentrations are associated with a reduced risk of SGA. WHAT IS KNOWN ALREADY: The maternal TRP metabolism is involved in many critical processes for embryonic and fetal growth, including immune modulation and regulation of vascular tone. Disturbances in TRP metabolism are associated with adverse maternal and fetal outcomes. STUDY DESIGN, SIZE, DURATION: This study was embedded within the Rotterdam Periconceptional Cohort (Predict Study), an ongoing prospective observational cohort conducted at a tertiary hospital from November 2010 onwards. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 1115 women were included before 11 weeks of gestation between November 2010 and December 2020. Maternal serum samples were collected between 7 and 11 weeks of gestation, and TRP metabolites (TRP, KYN, 5-HTP, 5-hydroxytryptamine, and 5-hydroxyindoleacetic acid) were determined using a validated liquid chromatography (tandem) mass spectrometry method. Serial 3D ultrasound scans were performed at 7, 9, and 11 weeks of gestation to accurately assess features of embryonic growth, including crown-rump length (CRL) and embryonic volume (EV) offline using virtual reality systems. Fetal growth parameters were retrieved from medical records and standardized according to Dutch reference curves. Mixed models were used to assess associations between maternal TRP metabolites and CRL and EV trajectories. Linear and logistic regression models were utilized to investigate associations with estimated fetal weight (EFW) and birthweight, and with SGA, respectively. All analyses were adjusted for potential confounders. MAIN RESULTS AND THE ROLE OF CHANCE: Maternal 5-HTP concentrations and the maternal 5-HTP/TRP ratio were inversely associated with embryonic growth (5-HTP, √CRL: β = -0.015, 95% CI = -0.028 to -0.001; 5-HTP 3√EV: β = -0.009, 95% CI = -0.016 to -0.003). An increased maternal 5-HTP/TRP ratio was also associated with lower EFW and birthweight, and with an increased risk of SGA (odds ratio (OR) = 1.006, 95% CI = 1.00-1.013). In contrast, higher maternal KYN concentrations were associated with a reduced risk of SGA in the unadjusted models (OR = 0.548, 95% CI = 0.320-0.921). LIMITATIONS, REASONS FOR CAUTION: Residual confounding cannot be ruled out because of the observational design of this study. Moreover, this study was conducted in a single tertiary hospital, which assures high internal validity but may limit external validity. WIDER IMPLICATIONS OF THE FINDINGS: The novel finding that maternal 5-HTP concentrations are associated with a smaller embryo and fetus implies that disturbances of the maternal serotonin pathway in the first trimester of pregnancy are potentially involved in the pathophysiology of fetal growth restriction. The association between higher maternal KYN concentrations and a reduced risk of SGA substantiate the evidence that the KYN pathway has an important role in fetal growth. More research is needed to delve deeper into the potential role of the maternal TRP metabolism during the periconception period and pregnancy outcome for mother and offspring. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by the Department of Obstetrics and Gynecology and the Department of Clinical Chemistry of the Erasmus MC, University Medical Center, Rotterdam, the Netherlands. The authors have no competing interests to disclose. TRIAL REGISTRATION NUMBER: N/A.</p

How is rape a weapon of war?: feminist international relations, modes of critical explanation and the study of wartime sexual violence

Rape is a weapon of war. Establishing this now common claim has been an achievement of feminist scholarship and activism and reveals wartime sexual violence as a social act marked by gendered power. But the consensus that rape is a weapon of war obscures important, and frequently unacknowledged, differences in ways of understanding and explaining it. This article opens these differences to analysis. Drawing on recent debates regarding the philosophy of social science in IR and social theory, it interprets feminist accounts of wartime sexual violence in terms of modes of critical explanation – expansive styles of reasoning that foreground particular actors, mechanisms, reasons and stories in the formulation of research. The idea of a mode of critical explanation is expanded upon through a discussion of the role of three elements (analytical wagers, narrative scripts and normative orientations) which accomplish the theoretical work of modes. Substantive feminist accounts of wartime sexual violence are then differentiated in terms of three modes – of instrumentality, unreason and mythology – which implicitly structure different understandings of how rape might be a weapon of war. These modes shape political and ethical projects and so impact not only on questions of scholarly content but also on the ways in which we attempt to mitigate and abolish war rape. Thinking in terms of feminist modes of critical explanation consequently encourages further work in an unfolding research agenda. It clarifes the ways in which an apparently commonality of position can conceal meaningful disagreements about human action. Exposing these disagreements opens up new possibilities for the analysis of war rape

Assessment of variation in bacterial composition among microhabitats in a mangrove environment using DGGE fingerprints and barcoded pyrosequencing

Here, we use DGGE fingerprinting and barcoded pyrosequencing data, at six cut-off levels (85-100%), of all bacteria, Alphaproteobacteria and Betaproteobacteria to assess composition in the rhizosphere of nursery plants and nursery-raised transplants, native plants and bulk sediment in a mangrove habitat. When comparing compositional data based on DGGE fingerprinting and barcoded pyrosequencing at different cut-off levels, all revealed highly significant differences in composition among microhabitats. Procrustes superimposition revealed that ordination results using cut-off levels from 85-100% and DGGE fingerprint data were highly congruent with the standard 97% cut-off level. The various approaches revealed a primary gradient in composition from nursery to mangrove samples. The affinity between the nursery and transplants was greatest when using Betaproteobacteria followed by Alphaproteobacteria data. There was a distinct secondary gradient in composition from transplants to bulk sediment with native plants intermediate, which was most prevalent using all bacteria at intermediate cut-off levels (92-97%). Our results show that PCR-DGGE provides a robust and cost effective exploratory approach and is effective in distinguishing among a priori defined groups.This study was funded by the Deutsche Forschungsgemeinschaft SM59/4-1 and 4-2 (www.dfg.de/en/index.jsp), FAPERJ-Brazil (www.faperj.br), Centre for Environmental and Marine Studies (CESAM, Portugal) (www.cesam.ua.pt), Foundation for Science and Technology (FCT, Portugal) PTDC/AAC-CLI/107916/2008 (http://alfa.fct.mctes.pt) and the European Regional Development Fund (ERDF) through COMPETE- (FCOMP-01-0124-FEDER-008657). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.publishe

Mood instability, mental illness and suicidal ideas : results from a household survey

Purpose: There is weak and inconsistent evidence that mood instability (MI) is associated with depression, post traumatic stress disorder (PTSD) and suicidality although the basis of this is unclear. Our objectives were first to test whether there is an association between depression and PTSD, and MI and secondly whether MI exerts an independent effect on suicidal thinking over and above that explained by common mental disorders. Methods: We used data from the Adult Psychiatric Morbidity Survey 2007 (N = 7,131). Chi-square tests were used to examine associations between depression and PTSD, and MI, followed by regression modelling to examine associations between MI and depression, and with PTSD. Multiple logistic regression analyses were used to assess the independent effect of MI on suicidal thinking, after adjustment for demographic factors and the effects of common mental disorder diagnoses. Results: There are high rates of MI in depression and PTSD and the presence of MI increases the odds of depression by 10.66 [95 % confidence interval (CI) 7.51–15.13] and PTSD by 8.69 (95 % CI 5.90–12.79), respectively, after adjusting for other factors. Mood instability independently explained suicidal thinking, multiplying the odds by nearly five (odds ratio 4.82; 95 % CI 3.39–6.85), and was individually by some way the most important single factor in explaining suicidal thoughts. Conclusions: MI is strongly associated with depression and PTSD. In people with common mental disorders MI is clinically significant as it acts as an additional factor exacerbating the risk of suicidal thinking. It is important to enquire about MI as part of clinical assessment and treatment studies are required

The design and evaluation of an open loop ground source heat pump operating in an ochre-rich coal mine water environment

Mine water from the abandoned coal mines is considered a good source of low enthalpy energy resource as the temperature of the mine water remains stable throughout the year and is suitable to be used for heating and cooling applications when implemented in conjunction with Ground Source Heat Pump (GSHP). The GSHP is considered to be a low carbon technology and its application for space heating and cooling is being actively investigated and developed by companies and local councils around the world. The open loop GSHP installations, in comparison to closed loop systems, are suitable and economical for large scale heating and cooling demands. This is because there is no time delay for heat transfer when compared with closed loop systems and because they use large volumes of coal mine water at a relatively constant temperatures. A few installations both large and small scale open loop mine water heating and cooling systems have been recently constructed throughout the world. However, coal mine water is associated with relatively poor water quality in some cases, often characterised by high salinity and pyrite oxidation. Despite the fact that mine water temperatures are favourably inclined for an efficient GSHP operations, concerns have been raised over the possibility of damage to the equipment due to poor water quality caused by clogging of the heat exchangers due to pyrite oxidation (ochre) in particular. Not much information is available on the impact of ochre has on the performance of an open loop GSHP when it is operated using the coal mine water rich in pyrite. This paper presents a novel design and implementation of an open loop system of GSHP operating in an ochre rich mine water environment. The results show that open loop systems, when combined with suitable heat pump and the associated design configurations of heat exchangers and maintenance procedures, could provide an efficient and reliable heating system at a lower cost

Are Apathy and Depressive Symptoms Related to Vascular White Matter Hyperintensities in Severe Late Life Depression?

OBJECTIVE: Apathy symptoms are defined as a lack of interest and motivation. Patients with late-life depression (LLD) also suffer from lack of interest and motivation and previous studies have linked apathy to vascular white matter hyperintensities (WMH) of the brain in depressed and nondepressed patients. The aim of this study was to investigate the relationship between apathy symptoms, depressive symptoms, and WMH in LLD. We hypothesize that late-onset depression (LOD; first episode of depression after 55 years of age) is associated with WMH and apathy symptoms. METHODS: Apathy scores were collected for 87 inpatients diagnosed with LLD. Eighty patients underwent brain magnetic resonance imaging. Associations between depressive and apathy symptoms and WMH were analyzed using linear regression. RESULTS: All 3 subdomains of the 10-item Montgomery–Åsberg Depression Rating Scale correlated significantly with the apathy scale score (all P < .05). In the total sample, apathy nor depressive symptoms were related to specific WMH. In LOD only, periventricular WMH were associated with depression severity (β = 5.21, P = .04), while WMH in the left infratentorial region were associated with apathy symptoms (β coefficient = 5.89, P = .03). CONCLUSION: Apathy and depressive symptoms are highly overlapping in the current cohort of older patients with severe LLD, leading to the hypothesis that apathy symptoms are part of depressive symptoms in the symptom profile of older patients with severe LLD. Neither apathy nor depressive symptoms were related to WMH, suggesting that radiological markers of cerebrovascular disease, such as WMH, may not be useful in predicting these symptoms in severe LLD