Finite-Element Analysis of Shear-off Failure of Keyed Dry Joints in Precast Concrete Segmental Bridges

This article has been made available through the Brunel Open Access Publishing Fund.The structural behaviour of precast concrete segmental bridges is largely dependent on the behaviour of the joints between segments. The current practice is to use small keys that are usually unreinforced, distributed over the height of the web and the flange of concrete segments and these keys are normally dry. In this study, a numerical analysis model was established based on ABAQUS finite element code to investigate structural behaviour of keyed dry joints under direct shear. The concrete damage plasticity model along with the pseudo-damping scheme were incorporated to analyse the system for microcracks and to stabilize the solution, respectively. The numerical model is calibrated by full-scale experimental results published elsewhere. It was found that the predicted ultimate load, cracking evolution history, and final crack pattern agree reasonably well with experiment results. The validated numerical model was then employed for parametric study on factors affecting shear behaviour of keyed dry joints, in this case confining pressure. It has been found that shear capacity predicted by AASHTO diverges from that predicted by numerical analysis at high confining pressure because the contribution of friction in the total shear capacity reduces with the increase in confining pressure. Hence, it is recommended to reduce the friction coefficient used in AASHTO code when high confining pressure is applied. Moreover, the propagation of inclined crack is arrested at high confining pressure due to the fact that the fracture propagation direction is governed by the criterion of the maximum energy release rate

Predictors of Engagement in a Parenting Intervention Designed to Prevent Child Maltreatment

Objective: The objectives of this analysis were to: 1) assess the impact of sociodemographic factors, and perceived costs and benefits on engagement in a parenting program designed to prevent child maltreatment, 2) determine if perceived costs and benefits mediated the association between sociodemographic factors and engagement, and 3) assess whether or not race/ethnicity moderated the relationship between sociodemographic factors, perceived costs and benefits, and engagement.Methods: Perceived costs and benefits of the intervention were assessed from parents providing self-reports, including satisfaction/ usefulness of the program (benefits), and time/difficulty associated with the program (costs). Engagement was defined as attendance at both the mid-point and then the number of visits attended throughout the remainder of the intervention. To investigate the direct and indirect effects (through perceived costs and benefits) of parental sociodemographic factors (education, age, gender, number of children, household income) on program engagement, data were analyzed with structural equation modeling (SEM). To assess the potential moderating effect of race/ethnicity, separate models were tested for White and African-American parents.Results: Perceived benefits positively impacted attendance for both White (n=227) and African-American (n=141) parents, whereas perceived costs negatively influenced attendance only for White parents. Parent education and age directly impacted attendance for White parents, but no sociodemographic factor directly impacted attendance for African-American parents. The indirect impact of sociodemographic characteristics on attendance through perceived costs and perceived benefits differed by race/ethnicity.Conclusions: Results suggest that White parents participate in a parenting program designed to prevent child maltreatment differently based upon their perceived benefits and costs of the program, and based on benefits only for African-American parents. Parental perception of costs and/or benefits of a program may threaten the effectiveness of interventions to prevent child maltreatment for certain racial/ethnic groups, as it keeps them from fully engaging in empirically validated programs. Different methods may be required to retain participation in violence prevention programs depending upon race/ethnicity

Investigation of Visitors’ Participation and Willingness to Pay for the Baba Aman Recreational Park, Iran

The aim of this study is to estimate the recreational value of Baba Aman Natural Park near Bojnord in Northeast Iran. The recreational value of Baba Aman Park has been analyzed using a contingent valuation method. For this purpose, 201 on-site questionnaires were administered between June and September of 2006. Visitor’s willingness to pay (WTP) for Baba Aman recreational park has been estimated for future entrance fees associated with two scenarios including current conditions and proposed improvements of the recreational services in the park. Average WTP was estimated 1.5 and 2 times more than the current entrance fee, considering two scenarios. These amounts are insignificant when compared to the cost of improving the recreational services of the area. However, found that only 25% of visitors are willing to pay more money beyond the current entrance fee. Statistical analysis has revealed that the monthly income and level of education have significant effects on WTP amounts. Implications are discussed and conclusion drawn

Genome-wide SNP identification by high-throughput sequencing and selective mapping allows sequence assembly positioning using a framework genetic linkage map

Determining the position and order of contigs and scaffolds from a genome assembly within an organism’s genome remains a technical challenge in a majority of sequencing projects. In order to exploit contemporary technologies for DNA sequencing. We developed a strategy for whole genome single nucleotide polymorphism sequencing allowing the positioning of sequence contigs onto a linkage map using the bin mapping method. The strategy was tested on a draft genome of the fungal pathogen Venturia inaequalis, the causal agent of apple scab, and further validated using sequence contigs derived from the diploid plant genome Fragaria vesca. Using our novel method we were able to anchor 70% and 92% of sequences assemblies for V. inaequalis and F. vesca, respectively, to genetic linkage maps. We demonstrated the utility of this approach by accurately determining the bin map positions of the majority of the large sequence contigs from each genome sequence and validated our method by mapping single sequence repeat markers derived from sequence contigs on a full mapping population.Deciduous Fruit Producers Trust THRIP Program National Research Foundation Claude Harris Leon FoundationWeb of Scienc

Study on accelerated microbial corrosion of concrete by artificially intensified sewage

In this study, the artificially intensified sewage with different levels of chemical oxygen demand (COD) were prepared, and the changes in weight and strength, as well as the micro morphology, mineral compositions and pore structure of concrete specimens immersed in the artificially intensified sewage and water were investigated in comparison. In parallel, the COD, pH, H2S and O2 values, as well as the microbial species and contents of sewage were monitored in the corrosion process. Furthermore, the microbial structure and activities within biofilm developed on concrete surface were also analyzed. The results indicated that the increase of COD concentration of sewage from 300 to 9000 mg/L led to the decline of sewage pH from 6.4 to 2.3 and increase of biofilm thickness from 300 to 800 μm, as well as the substantial growth of dominant microorganisms (Bacteroidete, Proteobacteria, etc.). The drop of pH level and O2 concentration within biofilm also indicated the high activities of sulfate-reducing and sulfur-oxidizing reaction. Correspondingly, after 150 days of immersion both the mass loss and strength decline rate of concrete increased from 0.32% to 1.78% and from 10.6% to 31.7%, respectively. Furthermore, the microstructure of the specimens in sewage became loose and porous. The CH content of specimens in sewage was significant lower than that of specimens in water, and both the cumulative mercury quantity and harmful macropore proportion of specimens in intensified sewage were significantly larger than that of specimens in water, which indicated the chemical reaction between CH and some acid substance. Overall, the sewage concentration increased by 30 times can triple the corrosion rate of concrete. The results obtained are expected to explore a fast and realistic method to simulate the concrete corrosion in full flow sewer pipes

Molecular prediction of lytic vs lysogenic states for Microcystis phage: Metatranscriptomic evidence of lysogeny during large bloom events

Microcystis aeruginosa is a freshwater bloom-forming cyanobacterium capable of producing the potent hepatotoxin, microcystin. Despite increased interest in this organism, little is known about the viruses that infect it and drive nutrient mobilization and transfer of genetic material between organisms. The genomic complement of sequenced phage suggests these viruses are capable of integrating into the host genome, though this activity has not been observed in the laboratory. While analyzing RNA-sequence data obtained from Microcystis blooms in Lake Tai (Taihu, China), we observed that a series of lysogeny-associated genes were highly expressed when genes involved in lytic infection were down-regulated. This pattern was consistent, though not always statistically significant, across multiple spatial and temporally distinct samples. For example, samples from Lake Tai (2014) showed a predominance of lytic virus activity from late July through October, while genes associated with lysogeny were strongly expressed in the early months (June–July) and toward the end of bloom season (October). Analyses of whole phage genome expression shows that transcription patterns are shared across sampling locations and that genes consistently clustered by co-expression into lytic and lysogenic groups. Expression of lytic-cycle associated genes was positively correlated to total dissolved nitrogen, ammonium concentration, and salinity. Lysogeny-associated gene expression was positively correlated with pH and total dissolved phosphorous. Our results suggest that lysogeny may be prevalent in Microcystis blooms and support the hypothesis that environmental conditions drive switching between temperate and lytic life cycles during bloom proliferation

Mapping forests in monsoon Asia with ALOS PALSAR 50-m mosaic images and MODIS imagery in 2010.

Extensive forest changes have occurred in monsoon Asia, substantially affecting climate, carbon cycle and biodiversity. Accurate forest cover maps at fine spatial resolutions are required to qualify and quantify these effects. In this study, an algorithm was developed to map forests in 2010, with the use of structure and biomass information from the Advanced Land Observation System (ALOS) Phased Array L-band Synthetic Aperture Radar (PALSAR) mosaic dataset and the phenological information from MODerate Resolution Imaging Spectroradiometer (MOD13Q1 and MOD09A1) products. Our forest map (PALSARMOD50 m F/NF) was assessed through randomly selected ground truth samples from high spatial resolution images and had an overall accuracy of 95%. Total area of forests in monsoon Asia in 2010 was estimated to be ~6.3 × 10(6 )km(2). The distribution of evergreen and deciduous forests agreed reasonably well with the median Normalized Difference Vegetation Index (NDVI) in winter. PALSARMOD50 m F/NF map showed good spatial and areal agreements with selected forest maps generated by the Japan Aerospace Exploration Agency (JAXA F/NF), European Space Agency (ESA F/NF), Boston University (MCD12Q1 F/NF), Food and Agricultural Organization (FAO FRA), and University of Maryland (Landsat forests), but relatively large differences and uncertainties in tropical forests and evergreen and deciduous forests

B lymphocytes as effector cells in the immunotherapy of cancer

Over the years, the role of B cells in the host immune response to malignancy has been overshadowed by our focus on T cells. Nevertheless, B cells play important roles as antigen‐presenting cells and in the production of antibodies. Furthermore, B cells can function as effector cells that mediate tumor destruction on their own. This review will highlight the various functions of B cells that are involved in the host response to tumor. J. Surg. Oncol. 2012;105:431–435. © 2011 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90339/1/22093_ftp.pd

Quantification of the relationship between the environment and Fusarium head blight, Fusarium pathogen density, and mycotoxins in winter wheat in Europe

Measurements of local environmental conditions, intensity of Fusarium head blight (FHB) in wheat spikes, biomass of Fusarium graminearum, F. culmorum, and F. poae (pathogens causing FHB) and concentration of the mycotoxins deoxynivalenol (DON) and nivalenol (NIV) in harvested wheat grain were obtained in a total of 150 location-years, originating in three European countries (Hungary, Ireland, United Kingdom) from 2001 to 2004. Through window-pane methodology, the length and starting time of temporal windows where the environmental variables were significantly associated with the biological variables were identified. Window lengths of 5 to 30 days were evaluated, with starting times from 18 days before anthesis to harvest. Associations were quantified with nonparametric Spearman correlation coefficients. All biological variables were significantly associated with at least one evaluated environmental variable (P≤0.05). Moisture-related variables (e.g., average relative humidity, hours of relative humidity above 80%) had the highest positive correlations with the biological variables, but there also was a significant negative correlation between average temperature and several biological variables. When significant correlations were found, they were generally for all window lengths, but for a limited number of window start times (generally before anthesis for disease index and after anthesis for the toxins and late-season fungal biomasses). Semi-partial Spearman correlation coefficients were used to evaluate the relationship between the environmental variables and the concentration of DON and NIV after the effects of FHB intensity and fungal biomass on the mycotoxins were removed. Significant semi-partial correlations were found between relative humidity variables and DON, and between temperature and relative humidity variables and NIV for time windows that started after anthesis (and not for any earlier time windows). Results confirm that the environment influences disease, fungal biomass, and mycotoxin production, and help refine the time windows where the association is greatest. However, variability in the relationships was high, indicating that no single environmental variable is sufficient for prediction of disease or mycotoxin contamination

Modelling H5N1 in Bangladesh across spatial scales : model complexity and zoonotic transmission risk

Highly pathogenic avian influenza H5N1 remains a persistent public health threat, capable of causing infection in humans with a high mortality rate while simultaneously negatively impacting the livestock industry. A central question is to determine regions that are likely sources of newly emerging influenza strains with pandemic causing potential. A suitable candidate is Bangladesh, being one of the most densely populated countries in the world and having an intensifying farming system. It is therefore vital to establish the key factors, specific to Bangladesh, that enable both continued transmission within poultry and spillover across the human–animal interface. We apply a modelling framework to H5N1 epidemics in the Dhaka region of Bangladesh, occurring from 2007 onwards, that resulted in large outbreaks in the poultry sector and a limited number of confirmed human cases. This model consisted of separate poultry transmission and zoonotic transmission components. Utilising poultry farm spatial and population information a set of competing nested models of varying complexity were fitted to the observed case data, with parameter inference carried out using Bayesian methodology and goodness-of-fit verified by stochastic simulations. For the poultry transmission component, successfully identifying a model of minimal complexity, which enabled the accurate prediction of the size and spatial distribution of cases in H5N1 outbreaks, was found to be dependent on the administration level being analysed. A consistent outcome of non-optimal reporting of infected premises materialised in each poultry epidemic of interest, though across the outbreaks analysed there were substantial differences in the estimated transmission parameters. The zoonotic transmission component found the main contributor to spillover transmission of H5N1 in Bangladesh was found to differ from one poultry epidemic to another. We conclude by discussing possible explanations for these discrepancies in transmission behaviour between epidemics, such as changes in surveillance sensitivity and biosecurity practices