704 research outputs found

    Recursive Multi-Time-Step Coupling of Multiple Subdomains

    Get PDF
    The need for efficient computation methods for modeling of large-scale structures has become critically important over the past few years. Efficient means of analysis often involve coupling in space through domain decomposition and multi scale methods in time. The multi-time-step coupling method is a coupling method in time which allows for efficient analysis of large-scale problems for structural dynamics where a large structural model is decomposed into smaller subdomains that are solved independently and then coupled back together to obtain the global solution. For coupling of more than two subdomains that are solved at different timesteps, we employ recursive methods. Currently a constraint on this recursive coupling is that subdomains with the same time step must be coupled first before coupling with other subdomains of different time steps. In this research, we develop a computational algorithm to overcome this constraint and allow the user to specify general coupling orders for the different subdomains. Our efforts till now have been directed towards coding the recursive coupling of multi-subdomain models and we have verified that the equations that will allow us to overcome coupling constraint are correct. We are in the process of implementing these equations into our codes. Once in place, these sets of codes will allow users to conduct simulation of structural dynamics in a very efficient manner

    Gene Expression Study of Monocytes/Macrophages during Early Foreign Body Reaction and Identification of Potential Precursors of Myofibroblasts

    Get PDF
    Foreign body reaction (FBR), initiated by adherence of macrophages to biomaterials, is associated with several complications. Searching for mechanisms potentially useful to overcome these complications, we have established the signaling role of monocytes/macrophages in the development of FBR and the presence of CD34+ cells that potentially differentiate into myofibroblasts. Therefore, CD68+ cells were in vitro activated with fibrinogen and also purified from the FBR after 3 days of implantation in rats. Gene expression profiles showed a switch from monocytes and macrophages attracted by fibrinogen to activated macrophages and eventually wound-healing macrophages. The immature FBR also contained a subpopulation of CD34+ cells, which could be differentiated into myofibroblasts. This study showed that macrophages are the clear driving force of FBR, dependent on milieu, and myofibroblast deposition and differentiation

    Associations between reliable changes in depression and changes in BMI, total body fatness and visceral adiposity during a 12-month weight loss trial.

    Get PDF
    We investigated associations between changes in depression and body composition over a 12-month weight loss trial. Of the 298 adults (BMI > 27 m/kg2), 219 with complete depression and body composition data were included. A 10-item Center for Epidemiologic Studies Depression Scale measured depression; dual-energy X-ray absorptiometry measured body composition. Multinomial logistic regression predicted reliable changes in depression by BMI, body fat (BF) and visceral adiposity (VAT). Multiplicative interaction terms tested modification by sex and ethnicity. Participants with increases in body composition were less likely to experience improvements in depression (BMI: RRR = 0.79 (0.68-0.91), p < 0.01; BF: RRR = 0.97 (0.94 - 0.99), p = 0.01; VAT: RRR = 0.99 (0.98-1.00), p = 0.02), but not worsening of depression (BMI: RRR = 1.29 (0.96-1.73), p = 0.10; BF: RRR = 1.04 (0.99-1.09), p = 0.15; VAT: RRR = 1.01 (1.00-1.03), p = 0.18). Sex and ethnicity interaction terms were not significant. However, the relationship was only significant among females, among non-Latinos for BMI and BF, and among Latinos for VAT. Our study supports the association between depression and obesity and highlights the need for longitudinal studies investigating VAT and depression in diverse ethnic groups

    The Interpersonal Style and Complementarity Between Crisis Negotiators and Forensic Inpatients

    Get PDF
    Previous negotiation research has explored the interaction and communication between crisis negotiators and perpetrators. A crisis negotiator attempts to resolve a critical incident through negotiation with an individual, or group of persons in crisis. The purpose of this study was to establish the interpersonal style of crisis negotiators and complementarity of the interpersonal interaction between them and forensic inpatients. Crisis negotiators, clinical workers and students (n = 90) used the Check List of Interpersonal Transactions-Revised (CLOIT-R) to identify interpersonal style, along with eight vignettes detailing interpersonal styles. Crisis negotiators were most likely to have a friendly interpersonal style compared to the other non-trained groups. Complementarity theory was not exclusively supported as submissive individuals did not show optimistic judgments in working with dominant forensic inpatients and vice versa. Exploratory analysis revealed that dominant crisis negotiators were optimistic in working with forensic inpatients with a dominant interpersonal style. This study provides insight into the area of interpersonal complementarity of crisis negotiators and forensic inpatients. Whilst further research is required, a potential new finding was established, with significant ‘similarity’ found when dominant crisis negotiators are asked to work with dominant forensic inpatients

    Global trends in ultraprocessed food and drink product sales and their association with adult body mass index trajectories

    Get PDF
    This study evaluated global trends in ultraprocessed food and drink (UPFD) volume sales/capita and associations with adult body mass index (BMI) trajectories. Total food/drink volume sales/capita from Euromonitor for 80 countries (2002‐2016) were matched to mean adult BMI from the NCD Risk Factor Collaboration (2002‐2014). Products were classified as UPFD/non‐UPFD according to the NOVA classification system. Mixed models for repeated measures were used to analyse associations between UPFD volume sales/capita and adult BMI trajectories, controlling for confounding factors. The increase in UPF volume sales was highest for South and Southeast Asia (67.3%) and North Africa and the Middle East (57.6%), while for UPD, the increase was highest for South and Southeast Asia (120.0%) and Africa (70.7%). In 2016, baked goods were the biggest contributor to UPF volume sales (13.1%‐44.5%), while carbonated drinks were the biggest contributor to UPD volume sales (40.2%‐86.0%). For every standard deviation increase (51 kg/capita, 2002) in UPD volume sales, mean BMI increased by 0.195 kg/m2 for men (P < .001) and 0.072 kg/m2 for women (P = .003). For every standard deviation (40 kg/capita, 2002) increase in UPF volume sales, mean BMI increased by 0.316 kg/m2 for men (P < .001), while the association was not significant for women. Increases in UPFD volume sales/capita were positively associated with population‐level BMI trajectories

    Impairing autophagy in retinal pigment epithelium leads to inflammasome activation and enhanced macrophage-mediated angiogenesis

    Get PDF
    Age-related decreases in autophagy contribute to the progression of age-related macular degeneration (AMD). We have now studied the interaction between autophagy impaired in retinal pigment epithelium (RPE) and the responses of macrophages. We find that dying RPE cells can activate the macrophage inflammasome and promote angiogenesis. In vitro, inhibiting rotenone-induced autophagy in RPE cells elicits caspase-3 mediated cell death. Co-culture of damaged RPE with macrophages leads to the secretion of IL-1β, IL-6 and nitrite oxide. Exogenous IL-6 protects the dysfunctional RPE but IL-1β causes enhanced cell death. Furthermore, IL-1β toxicity is more pronounced in dysfunctional RPE cells showing reduced IRAK3 gene expression. Co-culture of macrophages with damaged RPE also elicits elevated levels of pro-angiogenic proteins that promote ex vivo choroidal vessel sprouting. In vivo, impaired autophagy in the eye promotes photoreceptor and RPE degeneration and recruitment of inflammasome-activated macrophages. The degenerative tissue environment drives an enhanced pro-angiogenic response, demonstrated by increased size of laser-induced choroidal neovascularization (CNV) lesions. The contribution of macrophages was confirmed by depletion of CCR2 + monocytes, which attenuates CNV in the presence of RPE degeneration. Our results suggest that the interplay between perturbed RPE homeostasis and activated macrophages influences key features of AMD development

    Does Economic Agglomeration Lead to Efficient Rural to Urban Land Conversion? An Examination of China’s Metropolitan Area Development Strategy

    Get PDF
    Urbanization involves expansion of the amount of land covered by urban uses. Rural to urban land conversion (RULC) can satisfy demand for the additional space that growing cities require. However, there can be negative consequences, such as the loss of productive agricultural land and/or the destruction of natural habitats. Considerable interest therefore exists among policy makers and researchers regarding how the efficiency of RULC can be maximized. We used the Gini index and a data envelopment analysis to quantify the relationship between RULC and economic development for 17 metropolitan areas in China. We did this from two perspectives: (i) coordination; and (ii) efficiency. We found that economic agglomeration fosters the coordination of the amount of rural land that is allocated to be converted to urban uses. Similarly, economic agglomeration increases the efficiency of RULC in terms of the processes of socio-economic production. Through production technology innovation and readjustment in the scale of input factors, the productive efficiency of RULC can be promoted. Our findings suggest a need to strictly limit the amount of RULC, design differential land management policies according to location and development level, and adjust RULC allocation between different cities. Further, in harnessing the potential of intensive urban land use and restructuring, production factors, including land, can be enhanced through technological innovation. Research presented in this paper provides insights for areas of the world which are yet to undergo the rapid urbanization that China has experienced, but where it is projected to occur over the coming decades

    Evaluation of Arctic Sea Ice Thickness Simulated by AOMIP Models

    Get PDF
    We compare results from six AOMIP model simulations with estimates of sea ice thickness obtained from ICESat, moored and submarine-based upward looking sensors, airborne electromagnetic measurements and drill holes. Our goal is to find patterns of model performance to guide model improvement. The satellite data is pan-arctic from 2004-2008, ice-draft data is from moored instruments in Fram Strait, the Greenland Sea and the Beaufort Sea from 1992-2008 and from submarines from 1975-2000. The drill hole data are from the Laptev and East Siberian marginal seas from 1982-1986 and from coastal stations from 1998-2009. While there are important caveats when comparing modeled results with measurements from different platforms and time periods such as these, the models agree well with moored ULS data. In general, the AOMIP models underestimate the thickness of measured ice thicker than about 2 m and overestimate thickness of ice thinner than 2 m. The simulated results are poor over the fast ice and marginal seas of the Siberian shelves. Averaging over all observational data sets, the better correlations and smaller differences from observed thickness are from the ECCO2 and UW models

    Delimitation of lymphatic filariasis transmission risk areas: a geo-environmental approach

    Get PDF
    BACKGROUND: The Global Programme to Eliminate Lymphatic Filariasis (GPELF) depends upon Mass Drug Administration (MDA) to interrupt transmission. Therefore, delimitation of transmission risk areas is an important step, and hence we attempted to define a geo-environmental risk model (GERM) for determining the areas of potential transmission of lymphatic filariasis. METHODS: A range of geo-environmental variables has been selected, and customized on GIS platform to develop GERM for identifying the areas of filariasis transmission in terms of "risk" and "non-risk". The model was validated through a 'ground truth study' following standard procedure using GIS tools for sampling and Immuno-chromotographic Test (ICT) for screening the individuals. RESULTS: A map for filariasis transmission was created and stratified into different spatial entities, "risk' and "non-risk", depending on Filariasis Transmission Risk Index (FTRI). The model estimation corroborated well with the ground (observed) data. CONCLUSION: The geo-environmental risk model developed on GIS platform is useful for spatial delimitation purpose on a macro scale
    corecore