46 research outputs found

    Dynamics of a Charged Particle Around a Slowly Rotating Kerr Black Hole Immersed in Magnetic Field

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    The dynamics of a charged particle moving around a slowly rotating Kerr black hole in the presence of an external magnetic field is investigated. We are interested to explore the conditions under which the charged particle can escape from the gravitational field of the black hole after colliding with another particle. The escape velocity of the charged particle in the innermost stable circular orbit is calculated. The effective potential and escape velocity of the charged particle with angular momentum in the presence of magnetic field is analyzed. This work serves as an extension of a preceding paper dealing with the Schwarzschild black hole [Zahrani {\it et al}, Phys. Rev. D 87, 084043 (2013)].Comment: 20 pages, 12 figure

    Dynamics of Particles Around a Schwarzschild-like Black Hole in the Presence of Quintessence and Magnetic Field

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    We investigate the dynamics of a neutral and a charged particle around a static and spherically symmetric black hole in the presence of quintessence matter and external magnetic field. We explore the conditions under which the particle moving around the black hole could escape to infinity after colliding with another particle. The innermost stable circular orbit (ISCO) for the particles are studied in detail. Mainly the dependence of ISCO on dark energy and on the presence of external magnetic field in the vicinity of black hole is discussed. By using the Lyapunov exponent, we compare the stabilities of the orbits of the particles in the presence and absence of dark energy and magnetic field. The expressions for the center of mass energies of the colliding particles near the horizon of the black hole are derived. The effective force on the particles due to dark energy and magnetic field in the vicinity of black hole is also discussed.Comment: 25 pages, 17 figures, accepted for publication in the European Physical Journal

    Particle Dynamics Around Weakly Magnetized Reissner-Nordstr\"{o}m Black Hole

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    Considering the geometry of Reissner-Nordstr\"{o}m (RN) black hole immersed in magnetic field we have studied the dynamics of neutral and charged particles. A collision of particles in the inner stable circular orbit is considered and the conditions for the escape of colliding particles from the vicinity of black hole are given. The trajectories of the escaping particle are discussed. Also the velocity required for this escape is calculated. It is observed that there are more than one stable regions if magnetic field is present in the accretion disk of black hole so the stability of ISCO increases in the presence of magnetic field. Effect of magnetic field on the angular motion of neutral and charged particles is observed graphically.Comment: 16 pages, 16 figures, version accepted for publication in 'Advances in High Energy Physics

    A Study of Casual Relationship of Job Design and Employee’s Behavior

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    Some factors other than higher salaries, compensation benefits and conducive workplace seem to have strong impact on employee’s performance i.e. organization citizenship behavior and counterproductive work behavior.  Purpose of this study is to examine the impact of job design elements i.e. job enlargement, job enrichment and job rotation on employee’s organizational citizenship behavior and counterproductive work behavior in the banking sector of Faisalabad and extent to which this relationship is mediated by motivation. Data was collected from 170 frontline managers of banks. After analysis of data, it was found that that there is a positive and significant relationship between job enlargements, job enrichment on OCB while negative and significant relationship between job rotation and OCB. Negative and significant relationship between job enlargement and CWB, negative but insignificant relationship between job enrichment and CWB while positive and significant relationship was found between the job rotation and CWB. Motivation was partially mediating the relationship between job enlargement, enrichment, rotation and organizational citizenship behavior, while motivation was partially mediating the relationship between job rotation and counterproductive work behavior. This study enhances the existing literature of job design and contributes to research by finding how job design influences the OCB & CWB.&nbsp

    Serological and Molecular Investigation of Brucella Species in Dogs in Pakistan

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    Brucellosis is an important bacterial zoonosis caused by B. abortus and B. melitensis in Pakistan. The status of canine brucellosis caused by B. canis remains obscure. In total, 181 serum samples were collected from stray and working dogs in two different prefectures viz. Faisalabad (n = 87) and Bahawalpur (n = 94). Presence of antibodies against B. canis and B. abortus/B. melitensis was determined using the slow agglutination test (SAT) and ELISA, respectively. Real-time PCR was performed to detect and differentiate Brucella DNA at the species level. In Faisalabad, the serological prevalence was found to be 9.2% (8/87) and 10.3% (9/87) by SAT and ELISA, respectively. Only one of the ELISA positive samples (1.15%) yielded amplification for B. abortus DNA. In Bahawalpur, 63.8% (60/94) samples were found positive by SAT; however, none of the samples was positive by ELISA or by real-time PCR. Location, age (≥1 year) and body condition (weak) were found to be associated with B. canis infection, whereas presence of wounds was found to be associated with B. abortus infection only. These findings point towards a risk of transmission from dog to livestock and humans and vice versa. The study expects to draw the attention of concerned authorities towards infection prevention and animal welfare. This study warrants further epidemiological investigation on brucellosis in pet dogs and their owners. To the best of our knowledge, this is first ever report on B. canis and B. abortus in dogs in Pakistan

    Serological and molecular detection of bovine brucellosis at institutional livestock farms in Punjab, Pakistan

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    Bovine brucellosis remains a persistent infection in ruminants in Pakistan. A total of 828 (409 buffaloes and 419 cattle) sera were collected from 11 institutional-owned livestock farms in Punjab, Pakistan. The samples were tested by rose bengal plate agglutination test (RBPT) and indirect enzyme-linked immunosorbent assay (iELISA). The seroprevalence along with 95% confidence interval (CI) was determined. Univariable and multivariable analysis of the epidemiological background data was conducted and odds ratio (OR) was calculated to understand any association between the risk factors and the seroprevalence. An overall seroprevalence of 3.9% (Positive/Tested = 32/828) and 3.3% (27/828) was detected by RBPT and iELISA, respectively. The seroprevalence of 5.6% (CI 3.6–8.3) and 4.7%, (CI 2.8–7.2) and the odds ratio of 2.63 (CI 1.20–5.77) and 2.50 (CI 1.08–5.78) for testing positive by RBPT and iELISA, respectively were significantly higher (p < 0.05) in buffaloes than in cattle. Breed, sex, history of abortion and retention of fetal membranes (RFM) in the animals were not found statistically significantly associated with the infection. RBPT and iELISA based results agreed almost perfect (k = 0.877). In total, Brucella abortus-DNA (9/27) was amplified from seropositive samples by real-time polymerase chain reaction. This study identified for the first time the etiological agents of brucellosis at a molecular level at institutional-owned livestock farms in Pakistan. View Full-Tex

    Biology, Ecology, Infestation, and Management of Warble Flies (Diptera: Oestridae)

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    The range grazing livestock (cattles and goats) are afflicted by a significant skin/hide issue known as warble fly larval infestation, which is caused by the larvae of Hypoderma lineatum and Hypoderma bovis species which resulted in substantial economic losses to the leather industries. The life cycle of hypodermosis is complex, involving both ecto- and endoparasitic stages. Female warble flies deposit their eggs in rows of 5-8 on individual hairs of the host, often targeting the legs but also other areas. These eggs are securely attached to the hairs and a single female fly may lay as many as 800 eggs on a host within a week, which is typically their lifespan. Egg hatching occurs 3-7 days after the eggs are laid. The larvae then move down under to the skin and actively penetrate it, causing great irritation for cattle and goats. Some tactics used to control warble flies on animals are chemical insecticides which are available in the form of sprays, pour-ons, and injections. These chemicals can kill or repel adult flies and prevent larvae from developing into mature flies. Predatory insects e.g., wasps can be used to control warble fly populations. Physical methods i.e., fly traps, fly swatters, and sticky tapes can be used to capture or kill adult flies. Practices such as maintaining clean living conditions, grazing management, and reducing animal stress can help prevent warble fly infestations. It is important to consult with a veterinarian to determine the best control method for incidences of warble fly infestation

    AI-driven optimization of ethanol-powered internal combustion engines in alignment with multiple SDGs: A sustainable energy transition

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    With the escalating requirement for global sustainable energy solutions and the complexities linked with the complete transition to new technologies, internal combustion engines (ICEs) powered with biofuels like ethanol are gaining significance over time. However, problems linked to the performance and emissions of such ICEs necessitate accurate prediction and optimization. The study employed the integration of artificial neural networks (ANN) and multi-level historical design of response surface methodology (RSM) to address these challenges in alignment with the Sustainable Development Goals (SDGs). A single-cylinder spark ignition (SI) engine powered with ethanol-gasoline blends at different loads and speeds was used to gather data. Among six initially trained ANN models, the most efficient model with a regression coefficient (R2) of 0.9952 (training), 0.98579 (validation), 0.98847 (testing), and 0.99307 (overall) was employed to predict outputs such as brake power, brake specific fuel consumption (BSFC), brake thermal energy (BTE), concentration of carbon dioxide (CO2), carbon monoxide (CO), hydrocarbons (HC), and oxides of nitrogen NOx. Predicted outputs were optimized by incorporating RSM. On implementing optimized conditions, it was observed that BP and BTE increased by 19.9%, and 29.8%, respectively. Additionally, CO, and HC emissions experienced substantial reductions of 28.1%, and 40.6%, respectively. This research can help engine producers and researchers make refined decisions and achieve improved performance and emissions. The study directly supports SDG 7, SDG 9, SDG 12, SDG 13, and SGD 17, which call for achieving affordable, clean energy, sustainable industrialization, responsible consumption, and production, taking action on climate change, and partnership to advance the SDGs as a whole respectively
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