658 research outputs found

    Investigating the impact of land-use land-cover change on Indian summer monsoon daily rainfall and temperature during 1951–2005 using a regional climate model

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    Daily moderate rainfall events, which constitute a major portion of seasonal summer monsoon rainfall over central India, have decreased significantly during the period 1951 through 2005. On the other hand, mean and extreme near-surface daily temperature during the monsoon season have increased by a maximum of 1–1.5 °C. Using simulations made with a high-resolution regional climate model (RegCM4) and prescribed land cover of years 1950 and 2005, it is demonstrated that part of the changes in moderate rainfall events and temperature have been caused by land-use/land-cover change (LULCC), which is mostly anthropogenic. Model simulations show that the increase in seasonal mean and extreme temperature over central India coincides with the region of decrease in forest and increase in crop cover. Our results also show that LULCC alone causes warming in the extremes of daily mean and maximum temperatures by a maximum of 1–1.2 °C, which is comparable with the observed increasing trend in the extremes. Decrease in forest cover and simultaneous increase in crops not only reduces the evapotranspiration over land and large-scale convective instability, but also contributes toward decrease in moisture convergence through reduced surface roughness. These factors act together in reducing significantly the moderate rainfall events and the amount of rainfall in that category over central India. Additionally, the model simulations are repeated by removing the warming trend in sea surface temperatures over the Indian Ocean. As a result, enhanced warming at the surface and greater decrease in moderate rainfall events over central India compared to the earlier set of simulations are noticed. Results from these additional experiments corroborate our initial findings and confirm the contribution of LULCC in the decrease in moderate rainfall events and increase in daily mean and extreme temperature over India. Therefore, this study demonstrates the important implications of LULCC over India during the monsoon season. Although, the regional climate model helps in better resolving land–atmosphere feedbacks over the Indian region, the inferences do depend on the fidelity of the model in capturing the features of Indian monsoon realistically. It is proposed that similar studies using a suite of climate models will further enrich our understanding about the role of LULCC in the Indian monsoon climate

    Threshold photoelectron photoion coincidence spectroscopy of trichloroethene and tetrachloroethene

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    The threshold photoelectron, the threshold photoelectron photoion coincidence and ion breakdown spectra of trichloroethene and tetrachloroethene have been recorded from 9 – 22 eV. Comparisons with the equivalent data for the three dichloroethene molecules and theoretical calculations highlight the nature of the orbitals involved during photoionisation in this energy range. The ground electronic state of C2_2HCl3+_3^+ (C2_2Cl4+_4^+) is bound, with excited valence states dissociating to C2_2HCl2+_2^+ (C2_2Cl3+_3^+) and C2_2HCl+^+ (C2_2Cl2+_2^+). Appearance energies suggest that C2_2HCl+^+ forms from C2_2HCl3+_3^+ by loss of two chlorine atoms, whereas C2_2Cl2+_2^+ forms from C2_2Cl4+_4^+ by loss of a Cl2_2 molecule. The translational kinetic energy release into C2_2HCl2+_2^+ (C2_2Cl3+_3^+) + Cl is determined as a function of energy. In both cases, the fraction of the available energy released into translational energy of the two products decreases as the photon energy increases

    Caracol, Belize, and Changing Perceptions of Ancient Maya Society

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    A Study on the Efficacy of a Naloxone Training Program

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    Introduction: The use of naloxone to reverse a potentially fatal opioid overdose is a harm reduction strategy that reduces mortality and increases the potential for referral to substance use treatment for affected individuals. In the setting of outreach performed by a street medicine team, we aimed to determine the effectiveness of an educational intervention involving distribution of naloxone accompanied by a brief instructive session about opioids, opioid overdose, and medication administration. Methods: Our street medicine outreach team distributed 200 naloxone kits to clinicians and volunteers involved in caring for patients on ‘street rounds,’ as well as in shelters, soup kitchens, and street medicine clinic settings. Those receiving a naloxone kit engaged in a peer-reviewed presentation on how to safely use the medication to reverse a potentially fatal opioid overdose. The study team developed and administered a pre- and post-survey of 10 multiple choice questions on material covered in the educational training. The pre- and post-survey scores were compared to assess the effectiveness of implementing this training. Results were stratified by participant gender and age group. Results: Out of the 200 participants, six were excluded from the analysis due to completely missing data from one or both surveys. The mean age of participants was 40.2±12.5 years; 120 (65.6%) were female, 62 (33.9%) were male, and 1 (0.6%) identified as nonbinary. Every survey question had an increase in correct responses from pre-survey to post-survey (identified by an increase in the percentage of correct responses). The mean survey total score increased from 5.5±1.6 to 7.5±1.3. Within the sample of 194, the mean difference in scores from pre-survey to post-survey was 2.02 points (95% CI [1.77, 2.26]), p\u3c0.0001. Males had a mean increase in the total score from 5.6±1.8 to 7.4±1.1. Females had a mean increase in the total score from 5.5±1.5 to 7.5±1.3. The difference in total scores in males was 1.89 points (95% CI [1.42, 2.35]), p\u3c0.0001, and in females was 2.02 points (95% CI [1.71, 2.32]), p\u3c0.0001. Post-test scores improved in all age groups. Conclusion: The educational training on opioids, opioid overdose, and the use of naloxone was an effective adjunct to naloxone kit distribution to volunteers and clinicians caring for people experiencing homelessness

    Subtidal macrozoobenthos communities from northern Chile during and post El Niño 1997–1998

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    Despite a large amount of climatic and oceanographic information dealing with the recurring climate phenomenon El Niño (EN) and its well known impact on diversity of marine benthic communities, most published data are rather descriptive and consequently our understanding of the underlying mechanisms and processes that drive community structure during EN are still very scarce. In this study, we address two questions on the effects of EN on macrozoobenthic communities: (1) how does EN affect species diversity of the communities in northern Chile? and (2) is EN a phenomenon that restarts community assembling processes by affecting species interactions in northern Chile? To answer these questions, we compared species diversity and co-occurrence patterns of soft-bottoms macrozoobenthos communities from the continental shelf off northern Chile during (March 1998) and after (September 1998) the strong EN event 1997–1998. The methods used varied from species diversity and species co-occurrence analyses to multivariate ordination methods. Our results indicate that EN positively affects diversity of macrozoobenthos communities in the study area, increasing the species richness and diversity and decreasing the species dominance. EN represents a strong disturbance that affects species interactions that rule the species assembling processes in shallow-water, sea-bottom environments

    How predation and landscape fragmentation affect vole population dynamics

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    Background: Microtine species in Fennoscandia display a distinct north-south gradient from regular cycles to stable populations. The gradient has often been attributed to changes in the interactions between microtines and their predators. Although the spatial structure of the environment is known to influence predator-prey dynamics of a wide range of species, it has scarcely been considered in relation to the Fennoscandian gradient. Furthermore, the length of microtine breeding season also displays a north-south gradient. However, little consideration has been given to its role in shaping or generating population cycles. Because these factors covary along the gradient it is difficult to distinguish their effects experimentally in the field. The distinction is here attempted using realistic agent-based modelling. Methodology/Principal Findings: By using a spatially explicit computer simulation model based on behavioural and ecological data from the field vole (Microtus agrestis), we generated a number of repeated time series of vole densities whose mean population size and amplitude were measured. Subsequently, these time series were subjected to statistical autoregressive modelling, to investigate the effects on vole population dynamics of making predators more specialised, of altering the breeding season, and increasing the level of habitat fragmentation. We found that fragmentation as well as the presence of specialist predators are necessary for the occurrence of population cycles. Habitat fragmentation and predator assembly jointly determined cycle length and amplitude. Length of vole breeding season had little impact on the oscillations. Significance: There is good agreement between our results and the experimental work from Fennoscandia, but our results allow distinction of causation that is hard to unravel in field experiments. We hope our results will help understand the reasons for cycle gradients observed in other areas. Our results clearly demonstrate the importance of landscape fragmentation for population cycling and we recommend that the degree of fragmentation be more fully considered in future analyses of vole dynamics

    Design and implementation of GRIP: a computerized glucose control system at a surgical intensive care unit

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    BACKGROUND: Tight glucose control by intensive insulin therapy has become a key part of critical care and is an important field of study in acute coronary care. A balance has to be found between frequency of measurements and the risk of hypoglycemia. Current nurse-driven protocols are paper-based and, therefore, rely on simple rules. For safety and efficiency a computer decision support system that employs complex logic may be superior to paper protocols. METHODS: We designed and implemented GRIP, a stand-alone Java computer program. Our implementation of GRIP will be released as free software. Blood glucose values measured by a point-of-care analyzer were automatically retrieved from the central laboratory database. Additional clinical information was asked from the nurse and the program subsequently advised a new insulin pump rate and glucose sampling interval. RESULTS: Implementation of the computer program was uneventful and successful. GRIP treated 179 patients for a total of 957 patient-days. Severe hypoglycemia (< 2.2 mmol/L) only occurred once due to human error. With a median (IQR) of 4.9 (4.2 – 6.2) glucose measurements per day the median percentage of time in which glucose fell in the target range was 78%. Nurses rated the program as easy to work with and as an improvement over the preceding paper protocol. They reported no increase in time spent on glucose control. CONCLUSION: A computer driven protocol is a safe and effective means of glucose control at a surgical ICU. Future improvements in the recommendation algorithm may further improve safety and efficiency
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