Einstein-Cartan gravitational collapse of a homogeneous Weyssenhoff fluid

We consider the gravitational collapse of a spherically symmetric homogeneous matter distribution consisting of a Weyssenhoff fluid in the presence of a negative cosmological constant. Our aim is to investigate the effects of torsion and spin averaged terms on the final outcome of the collapse. For a specific interior spacetime setup, namely the homogeneous and isotropic FLRW metric, we obtain two classes of solutions to the field equations where depending on the relation between spin source parameters, $(i)$ the collapse procedure culminates in a spacetime singularity or $(ii)$ it is replaced by a non-singular bounce. We show that, under certain conditions, for a specific subset of the former solutions, the formation of trapped surfaces is prevented and thus the resulted singularity could be naked. The curvature singularity that forms could be gravitationally strong in the sense of Tipler. Our numerical analysis for the latter solutions shows that the collapsing dynamical process experiences four phases, so that two of which occur at the pre-bounce and the other two at post-bounce regimes. We further observe that there can be found a minimum radius for the apparent horizon curve, such that the main outcome of which is that there exists an upper bound for the size of the collapsing body, below which no horizon forms throughout the whole scenario.Comment: 23 pages, 11 figure

The Effect of IELTS Listening Strategy Use on the Reduction of IELTS Listening Test Anxiety and on IELTS Listening Performance

The study investigates the impact of IELTS listening strategy use on the reduction of listening test anxiety and on the listening performance of the IELTS test takers in light of the data of 80 participants on the pretest and post-test IELTS listening along with the participants' score on pre-anxiety and post anxiety scale. So, drawing on the instruments including a proficiency test, pre/post-test, anxiety questionnaire, materials for strategy instruction, the participants were randomly divided into two groups: Control Group and Experimental Group, each including 40 participants. As per the procedure, after tackling their pre-listening performance and pre-anxiety score, one group was treated with IELTS-Listening related strategies and the other group was not treated, but both were administered listening test. The results of the study indicated that those treated with IELTS strategy outperformed ( t (78) = 4.57, p = .000, r = .460 ) those receiving no listening-related strategy. Furthermore, the results of a t-test run on the post-test of the groups anxiety arrived at a statistically significant difference (t (78) = 5.77, p = .000, r = .547), representing that the control group outperformed the experimental group. Also, Pearson Correlation done for finding out a potential relationship between anxiety and listening performance indicated a negative and weak to moderate relationship ((r (78) = -.26, p = .020). The pedagogical implications of the study are in detailed argued

Improving Profitability of a Color Production Line by Breaking Down Bottlenecks: A Computer Simulation Approach

Bottlenecks are one of the controversial issues in manufacturing companies. Managers and designers attempt to manage this trouble to improve efficiency in different ways. For example, expanding capacity is a prevalent solution to get rid of bottlenecks. In this paper, a color production line is chosen, which faces several challenges in its production line. This company attempts to distinguish and diminish the bottlenecks in the production line. The objective of this paper is to build a developed model of a production line to improve its profitability by breaking down its bottlenecks. Besides, the optimum number of operators with different utilizations is investigated in this paper. Furthermore, we considered the construction of new quality control in the station, which is the most time-wasting operation in the production line. The current study aims to apply computer simulation to examine the production line bottlenecks. In doing so, arena 14.00 software is used. Then the results are analyzed, and several managerial implications are presented.Comment: 10 page

The role of ethics in water, food and environmental security from the perspective of farmers: case study at Lordegan in Chaharmahal and Bakhtiari province, Iran

The overexploitation of natural resources leads to environmental degradation and negative impacts to present and future generations. Therefore, the efficient and rational use of the natural resources is vital because their regeneration involves very costs and time. The water issue is so important that it is not just technical data that need to be addressed to solve its crisis, but also social, moral and cultural data must be used. So far, agricultural water use ethics have been discussed as a topic related to field of environmental ethics. Water ethics should be considered as an applied ethics that is based on the recognition of water as a requirement for life. Water is the major limiting factor in agricultural production. Therefore, it is important to utilize it correctly, especially in agricultural activities. In the present study, the general objective was to analyze the principles (human dignity, mutual good, solidarity, supervision, and justice) of the water ethics in the viewpoint of farmers, in the Lordegan township in Chaharmahal and Bakhtiari province, Iran. The present research was performed using a descriptive-analytical method, with field information through questionnaires. The research sample consisted of 219 people selected using Cochran’s formula. The results of the research indicate that the farmers have a high average age (54 years). 32.9% of the respondents are illiterate and only 14.2% had a university degree. Farmers are well acquainted with and adhered to the principles of water ethics. But even though they know that harvesting water from underground aquifers is immoral, in practice more than half of them do so, indicating that long-term water scarcity will lead to ethical disrespect. The results of the research show that in times of water crisis, including climate change, support to farmers should be strengthened, especially in economic and income terms, so that their cultural and environmental gifts are not threatened.The overexploitation of natural resources leads to environmental degradation and negative impacts to present and future generations. Therefore, the efficient and rational use of the natural resources is vital because their regeneration involves very costs and time. The water issue is so important that it is not just technical data that need to be addressed to solve its crisis, but also social, moral and cultural data must be used. So far, agricultural water use ethics have been discussed as a topic related to field of environmental ethics. Water ethics should be considered as an applied ethics that is based on the recognition of water as a requirement for life. Water is the major limiting factor in agricultural production. Therefore, it is important to utilize it correctly, especially in agricultural activities. In the present study, the general objective was to analyze the principles (human dignity, mutual good, solidarity, supervision, and justice) of the water ethics in the viewpoint of farmers, in the Lordegan township in Chaharmahal and Bakhtiari province, Iran. The present research was performed using a descriptive-analytical method, with field information through questionnaires. The research sample consisted of 219 people selected using Cochran’s formula. The results of the research indicate that the farmers have a high average age (54 years). 32.9% of the respondents are illiterate and only 14.2% had a university degree. Farmers are well acquainted with and adhered to the principles of water ethics. But even though they know that harvesting water from underground aquifers is immoral, in practice more than half of them do so, indicating that long-term water scarcity will lead to ethical disrespect. The results of the research show that in times of water crisis, including climate change, support to farmers should be strengthened, especially in economic and income terms, so that their cultural and environmental gifts are not threatened

Evaluación de esquemas de microfísica WRF en la simulación de una línea de turbonada sobre IRAN utilizando datos de radar y de reanálisis

Se registró una línea de turbonada en el puerto de Dayyer, al suroeste de Irán, el 19 de marzo de 2017. En el presente documento, hemos simulado los rasgos característicos asociados con la línea de turbonada mediante el modelo de investigación y pronóstico meteorológico (WRF) utilizando cinco microfísicas diferentes (MP) esquemas. Para validar las características simuladas de la línea de turbonada, la reflectividad de la sección transversal de latitud-altura y longitud-altura y el valor de precipitación derivado de la reflectividad observada recopilada por el radar meteorológico Doppler en Bushehr, datos de la estación meteorológica sinóptica en el puerto de Dayyer junto con NCEP-NCAR y ERA -Se utilizaron datos de reanálisisINTERIM. Para verificar la precipitación simulada, se calculó la curva Fractions Skill Score (FSS). El examen de los resultados de la simulación de la presión geopotencial y al nivel del mar muestra que las simulaciones del modelo que utilizan diferentes esquemas de MP concuerdan bien con los reanálisis de verificación. Además, la distribución espacial de las precipitaciones de las simulaciones y las observaciones de verificación no mostraron grandes diferencias. Sin embargo, existen diferencias significativas en los detalles de las simulaciones, como la reflectividad máxima de las celdas convectivas, la extensión vertical de las celdas de tormenta, la velocidad y dirección del viento, los valores de precipitación y las curvas FSS. Sin embargo, todas las simulaciones han mostrado celdas convectivas sobre el puerto de Dayyer en el momento de la aparición de la línea de turbonada, pero solo la simulación del modelo que usa el esquema Lin MP es consistente con la reflectividad del radar y la extensión vertical correspondientes. El gráfico FSS mostró que la habilidad cambia con la escala espacial. Los resultados utilizando el esquema de microfísica Lin cruzaron la línea FSSuniform a escalas más bajas en comparación con otros esquemas de M

Individual-based modelling of cyanobacteria blooms: Physical and physiological processes

Lakes and reservoirs throughout the world are increasingly adversely affected by cyanobacterial harmful algal blooms (CyanoHABs). The development and spatiotemporal distributions of blooms are governed by complex physical mixing and transport processes that interact with physiological processes affecting the growth and loss of bloom-forming species. Individual-based models (IBMs) can provide a valuable tool for exploring and integrating some of these processes. Here we contend that the advantages of IBMs have not been fully exploited. The main reasons for the lack of progress in mainstreaming IBMs in numerical modelling are their complexity and high computational demand. In this review, we identify gaps and challenges in the use of IBMs for modelling CyanoHABs and provide an overview of the processes that should be considered for simulating the spatial and temporal distributions of cyanobacteria. Notably, important processes affecting cyanobacteria distributions, in particular their vertical passive movement, have not been considered in many existing lake ecosystem models. We identify the following research gaps that should be addressed in future studies that use IBMs: 1) effects of vertical movement and physiological processes relevant to cyanobacteria growth and accumulations, 2) effects and feedbacks of CyanoHABs on their environment; 3) inter and intra-specific competition of cyanobacteria species for nutrients and light; 4) use of high resolved temporal-spatial data for calibration and verification targets for IBMs; and 5) climate change impacts on the frequency, intensity and duration of CyanoHABs. IBMs are well adapted to incorporate these processes and should be considered as the next generation of models for simulating CyanoHABs

Risk factors of HBs Ag positive in blood donors of Hamedan, Iran

Background: Viral hepatitis B is a common community acquired infection. It damages the liver tissue and can be a risk factor for cirrhosis and liver cancer. In the present study, we investigated the major risk factors for being HBs Ag positive among blood donors of Hamedan, Iran.Methods: A cross-sectional study was carried out in Hamedan city. All of the blood donors in Blood Transfusion Organization Center of the city were asked to fill out a questionnaire between September 2011 and February 2012. Logistic regression was used to calculate Odds Ratios (OR) for risk factors of being HBs Ag positive using IBM SPSS Statistics for Windows, Version 22.0.Results: Among 571 participants 119 (20.8%) were HBs Ag positive. Of all patients, 158 (27.6%) were female, 506 (88.6%) were living in urban areas. Also, 375 (65.7%) were married. Among the potential risk factors of HBs Ag positivity studied, “History of Surgery” ranked first (OR=3.11 P=0.003) and “Familial History of Liver Disease” was the second significant risk factor (OR=2.90 P=0.013). Human bite, dental filling, and needle stick had odds ratios less than one. However, they were not found to be statistically significant (P>0.05).Conclusion: Of all risk factors investigated in the present study, “History of Surgery” suggests a risk of infection transmission through surgical team. More studies on different populations are needed due to regional characteristics of hepatitis transmission

Impacts of atmospheric stilling and climate warming on cyanobacterial blooms: An individual-based modelling approach

Harmful algal blooms of the freshwater cyanobacteria genus Microcystis are a global problem and are expected to intensify with climate change. In studies of climate change impacts on Microcystis blooms, atmospheric stilling has not been considered. Stilling is expected to occur in some regions of the world with climate warming, and it will affect lake stratification regimes. We tested if stilling could affect water column Microcystis distributions using a novel individual-based model (IBM). Using the IBM coupled to a three-dimensional hydrodynamic model, we assessed responses of colonial Microcystis biomass to wind speed decrease and air temperature increase projected under a future climate. The IBM altered Microcystis colony size using relationships with turbulence from the literature, and included light, temperature, and nutrient effects on Microcystis growth using input data from a shallow urban lake. The model results show that dynamic variations in colony size are critical for accurate prediction of cyanobacterial bloom development and decay. Colony size (mean and variability) increased more than six-fold for a 20% decrease in wind speed compared with a 2 °C increase in air temperature. Our results suggest that atmospheric stilling needs to be included in projections of changes in the frequency, distribution and magnitude of blooms of buoyant, colony-forming cyanobacteria under climate change

The potential therapeutic use of renin-angiotensin system inhibitors in the treatment of inflammatory diseases

Inflammation is a normal part of the immune response to injury or infection but its dysregulation promotes the development of inflammatory diseases, which cause considerable human suffering. Non-steroidal anti-inflammatory agents (NSAIDs) are the most commonly prescribed agents for the treatment of inflammatory diseases but they are accompanied by a broad range of side effects, including gastrointestinal and cardiovascular events. The renin-angiotensin system (RAS) is traditionally known for its role in blood pressure regulation. However, there is increasing evidence that RAS signalling is also involved in the inflammatory response associated with several disease states. Angiotensin II increases blood pressure by binding to angiotensin type 1 (AT1) receptor, and direct renin inhibitors (DRIs), angiotensin-converting enzyme (ACE) inhibitors and AT1 receptor blockers (ARBs) are clinically used as anti-hypertensive agents. Recent data suggest that these drugs also have anti-inflammatory effects. Therefore, this review summarizes these recent findings for the efficacy of two of the most widely used antihypertensive drug classes, ACE inhibitors and ARBs, to reduce or treat inflammatory diseases such as atherosclerosis, arthritis, steatohepatitis, colitis, pancreatitis and nephritis