823 research outputs found

    Bubbles as tracers of heat input to cooling flows

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    We examine the distribution of injected energy in three-dimensional, adaptive-grid simulations of the heating of cooling flows. We show that less than 10 percent of the injected energy goes into bubbles. Consequently, the energy input from the nucleus is underestimated by a factor of order 6 when it is taken to be given by PVgamma/(gamma-1), where P and V are the pressure and volume of the bubble, and gamma the ratio of principal specific heats.Comment: Accepted for publication in MNRAS; 5 page

    The Vector Direction of the Interstellar Magnetic Field Outside the Heliosphere

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    We propose that magnetic reconnection at the heliopause only occurs where the interstellar magnetic field points nearly anti-parallel to the heliospheric field. By using large-scale magnetohydrodynamic (MHD) simulations of the heliosphere to provide the initial conditions for kinetic simulations of heliopause (HP) reconnection we show that the energetic pickup ions downstream from the solar wind termination shock induce large diamagnetic drifts in the reconnecting plasma and stabilize non-anti-parallel reconnection. With this constraint the MHD simulations can show where HP reconnection most likely occurs. We also suggest that reconnection triggers the 2-3 kHz radio bursts that emanate from near the HP. Requiring the burst locations to coincide with the loci of anti-parallel reconnection allows us to determine, for the first time, the vector direction of the local interstellar magnetic field. We find it to be oriented towards the southern solar magnetic pole.Comment: Submitted to ApJ; incorporates minor referee-suggested revision

    Local perception of indoor air pollution with use of biofuel in rural communities of Uchalli Wetlands complex, salt range Pakistan

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    More than 2.4 billion people around the world in the rural community depend on biomass fuel (wood, charcoal animal dung, and crop residue). Incomplete combustion of this fuel has led to increased amounts of indoor pollution and raise in global warming; this has further led to the increase in the incidence of diseases. Therefore, interventions to reduce biomass fuel related emission by alternative fuels and improved combustion efficiency can improve health, add to socioeconomic development. The area selected for sampling was the Uchalli Wetlands Complex which in the Northwest of Khushab district in Pakistan which houses three saline lakes surrounded by forest and villages. A questionnaire was designed with questions regarding the household fuel use and techniques to improve livelihood and to create awareness and locals from the age of 19-95 were interviewed with a majority of males, houses in the area were mainly of stone blocks and majority males in the area worked in the city. Combined family system was prevalent in the area (80%) with about 42% of the population having no formal education. A wide variety of stoves were observed in the area with wives having a major decision (69%) in fuel choice which mainly depended on the cheapness and availability of the fuel. The cooking being mostly done (79.8%) outside in summers and indoors in winters. Majority of the respondents (94.7%) were aware that liquid petroleum gas and natural gas are better ways of reducing pollution and decreasing the incidence of diseases which included using dry wood, proper ventilation and many others

    Optimal control to limit the spread of COVID-19 in Italy

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    We apply optimal control theory to a generalized SEIR-type model. The proposed system has three controls, representing social distancing, preventive means, and treatment measures to combat the spread of the COVID-19 pandemic. We analyze such optimal control problem with respect to real data transmission in Italy. Our results show the appropriateness of the model, in particular with respect to the number of quarantined/hospitalized (confirmed and infected) and recovered individuals. Considering the Pontryagin controls, we show how in a perfect world one could have drastically diminish the number of susceptible, exposed, infected, quarantined/hospitalized, and death individuals, by increasing the population of insusceptible/protected.publishe

    Federalism and the Arab League: A theoretical synergy

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    Abstract. The paper is a theoretical analogy of the Arab league as a regional organization. The paper also discusses the objectives, strengths and weaknesses of the league. By adopting descriptive-historical research from library instrument, findings show that, there is no doubt that the league had recorded some appreciable level of achievements since its inception and there have equally been some challenges along the line. The paper concludes that, the Arab league must find a way to reduce the perpetual tension and violence in Palestine by working towards enthroning a peaceful relationship with Israel while retaining their cultural identity. The paper also recommends that, the Arab league should strengthen their relationship with the non-Arab Nations especially in the face of globalization to reap the benefits therein involved as a league. Arab league must ensure that Arab states stop waging needless wars between and among themselves. The Syria and Yemeni crises among others is a disgrace to the Arab world.Keywords: Arab league, Theoretical, Synergy, Federalism, Integration.JEL. A10, F15

    Resilience of local communities to climate change around a ramsar site in Pakistan

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    The Taunsa Barrage controls water flow in the River Indus for irrigation and flood control purposes. The river ecology is sensitive to climate change due to the high portion of its flow derived glacial melt. To assess the socio-economic status of the rural communities living within the Taunsa Barrage Wildlife sanctuary, a questionnaire was developed based on the perception of local communities about their resilience capacity and climate change. Temperature and rainfall data over the period 1951 – 2010 were analysed and used as an indicator of climate change. 85 of the respondents (n =100) reported that there had been an increase extreme climatic events over the past 60 years. These communities have proved to be resilient (94% n = 100) to it by changing occupations and lifestyles. However at the same time they have increased the pressure on natural resource use and this is causing a serious problem in the management of the protected area

    Probiotic Lactobacillus and Bifidobacterium Strains Counteract Adherent-Invasive Escherichia coli (AIEC) Virulence and Hamper IL-23/Th17 Axis in Ulcerative Colitis, but Not in Crohn's Disease

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    Hypersecretion of proinflammatory cytokines and dysregulated activation of the IL-23/Th17 axis in response to intestinal microbiota dysbiosis are key factors in the pathogenesis of inflammatory bowel diseases (IBD). In this work, we studied how Lactobacillus and Bifidobacterium strains affect AIEC-LF82 virulence mechanisms and the consequent inflammatory response linked to the CCR6-CCL20 and IL-23/Th17 axes in Crohn's disease (CD) and ulcerative colitis (UC) patients. All Lactobacillus and Bifidobacterium strains significantly reduced the LF82 adhesion and persistence within HT29 intestinal epithelial cells, inhibiting IL-8 secretion while not affecting the CCR6-CCL20 axis. Moreover, they significantly reduced LF82 survival within macrophages and dendritic cells, reducing the secretion of polarizing cytokines related to the IL-23/Th17 axis, both in healthy donors (HD) and UC patients. In CD patients, however, only B. breve Bbr8 strain was able to slightly reduce the LF82 persistence within dendritic cells, thus hampering the IL-23/Th17 axis. In addition, probiotic strains were able to modulate the AIEC-induced inflammation in HD, reducing TNF-\u3b1 and increasing IL-10 secretion by macrophages, but failed to do so in IBD patients. Interestingly, the probiotic strains studied in this work were all able to interfere with the IL-23/Th17 axis in UC patients, but not in CD patients. The different interaction mechanisms of probiotic strains with innate immune cells from UC and CD patients compared to HD suggest that testing on CD-derived immune cells may be pivotal for the identification of novel probiotic strains that could be effective also for CD patients

    Prospects for alleviating poverty and protecting the Taunsa barrage wildlife sanctuary, Indus river, Pakistan, through cultural and eco-tourism

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    The common assumption about protected areas is that they aggravate poverty amongst local residents by excluding them from livelihood activities such as fishing, agriculture, tourism and logging. It has been increasingly recognized that protected areas should instead contribute to sustaining the resident communities of surrounding areas. Eco-tourism could be an alternative form of income generation and has a substantial potential to boost and develop a relationship between people and nature. At the Taunsa Barrage Wildlife Sanctuary (TBWS), on the Indus River, Pakistan, local communities rely on local ecosystem services for up to 90% of their daily needs. To determine the potential for eco-tourism growth a SWOT analysis (Strengths, weaknesses, opportunities and threats) was designed based on discussion with stake holders (including community representative, non-governmental and governmental agencies)and personal observation during 2010. It is proposed as an approach for communities to utilize otherwise marginal cultural or ecological assets.Sustainability and involvement are both fundamental for the enduring future of this form of tourism. This study indicates that the prospects of eco-tourism as an instrument for empowerment and poverty alleviation at the TBWS are good.Eco-cultural tourism can offers ways to achieve sustainable resource and to engage with wider society. It could also act as a model for how cultural- and eco-tourism could empower local people in comparable settings in Pakistan
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