5,107 research outputs found

    Black hole solutions in f(R) gravity coupled with non-linear Yang-Mills field

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    It is shown that in the static, spherically symmetric spacetime the problem of metric f(R) gravity coupled with non-linear Yang-Mills (YM) field constructed from the Wu-Yang ansatz as source, can be solved in all dimensions. By non-linearity it is meant that the YM Lagrangian depends arbitrarily on its invariant. A particular form is considered to be in the power-law form with limit of the standard YM theory. The formalism admits black hole solutions with single or double horizons in which f(R) can be obtained, in general numerically. In 6-dimensional case we obtain an exact solution given by f(R)=\surdR gravity that couples with the YM field in a consistent manner.Comment: 12 pages, 8 figures, revised version with major changes including expanded references. Dedicated to the memory of Yavuz Nutku (1943-2010

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    Robust Cardiac Motion Estimation using Ultrafast Ultrasound Data: A Low-Rank-Topology-Preserving Approach

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    Cardiac motion estimation is an important diagnostic tool to detect heart diseases and it has been explored with modalities such as MRI and conventional ultrasound (US) sequences. US cardiac motion estimation still presents challenges because of the complex motion patterns and the presence of noise. In this work, we propose a novel approach to estimate the cardiac motion using ultrafast ultrasound data. -- Our solution is based on a variational formulation characterized by the L2-regularized class. The displacement is represented by a lattice of b-splines and we ensure robustness by applying a maximum likelihood type estimator. While this is an important part of our solution, the main highlight of this paper is to combine a low-rank data representation with topology preservation. Low-rank data representation (achieved by finding the k-dominant singular values of a Casorati Matrix arranged from the data sequence) speeds up the global solution and achieves noise reduction. On the other hand, topology preservation (achieved by monitoring the Jacobian determinant) allows to radically rule out distortions while carefully controlling the size of allowed expansions and contractions. Our variational approach is carried out on a realistic dataset as well as on a simulated one. We demonstrate how our proposed variational solution deals with complex deformations through careful numerical experiments. While maintaining the accuracy of the solution, the low-rank preprocessing is shown to speed up the convergence of the variational problem. Beyond cardiac motion estimation, our approach is promising for the analysis of other organs that experience motion.Comment: 15 pages, 10 figures, Physics in Medicine and Biology, 201

    Zoonotic disease management and infection control practices among veterinarians in the United Arab Emirates

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    This study was conducted to assess zoonotic disease management and infection control practices (ICPs) among veterinarians in the United Arab Emirates (UAE). A questionnaire was developed in SurveyMonkey, an online tool, and was distributed by email during February–May 2020 to 470 veterinarians practicing across the UAE. A total of 110 individuals completed the survey, giving a response rate of 23.4% (110/470). Results indicate that reported hand hygiene, sharps management, barrier or isolation practices, and personal choices for personal protective equipment (PPE) in common practice scenarios varied among practitioners. The majority (>75%) of veterinarians in all practice types reported always washing their hands before eating, drinking, or smoking at work. The survey revealed that 19% and 10% of large and small animal veterinarians indicated they sterilized and reused disposable needles. Veterinarians among all practices indicated high rates (75% to 80%) of recapping needles before disposal. When handling an animal suspected of having a zoonotic disease, most (90%) of small animal veterinarians reported always using practices such as isolating the animal and removing outwear before contact with other animals. However, only half (55%) of the large animal respondents reported always isolating the animal or sterilizing all equipment used on the animal of concern. Fewer than half of the large animal (35%) and mixed practice (44%) veterinarians indicated they would always be limiting human contact with the animal of concern. All of the small animal respondents reported full compliance with PPE while performing surgery and necropsy. Among large animal veterinarians, 44% reported not using respiratory or eye protection when aiding with parturition or handling conception products. Failure to use appropriate PPE when handling blood samples was the second most common noncompliant practice among large animal (39%) veterinarians and mixed practice (41%) respondents. Our study indicates a need for continuous education regarding ICPs in the veterinary community in the UAE. Better awareness of the risk of zoonotic disease exposure and options for managing this risk and liability issues could drive the adoption of infection control practices

    Risk factors associated with brucella seropositivity in sheep and goats in Duhok Province, Iraq

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    Sera from 432 small ruminants (335 sheep and 97 goats) from 72 farms in Duhok Province, northern Iraq, were collected to investigate risk factors associated with brucellosis seropositivity. Serum samples were tested using the Rose Bengal test (RBT) and an indirect enzyme-linked immunosorbent assay (iELISA). Using parallel interpretation, RBT and iELISA results showed that 31.7% (95% confidence interval (CI): 26.1, 36.3) of sheep and 34.0% (95% CI: 24.7, 44.3) of goats had antibodies against Brucella in the study area. A random-effects multivariable logistic regression model indicated that a higher chance of being seropositive (odds ratio (OR) = 1.7; 95% 1.4; 2.2) was associated with an increase in the age of animals. The odds of Brucella seropositivity in flocks where sheep and goats grazed together was 2.0 times higher (95% CI: 1.08; 3.9) compared to flocks where sheep and goats grazed separately. The odds of Brucella seropositivity in small ruminants was 2.2 higher (95% CI: 1.2; 4.3) for animals originating from farms with a history of goat abortion in the preceding 12 months. In contrast, for every 1000 Iraqi Dinars (~0.85 US Dollar) spent by the farmers on control of Brucella in their flocks, the odds of Brucella seropositivity decreased significantly (OR = 0.9, p-value = 0.021). The final model also indicated significant differences in Brucella seropositivity between the different districts of Duhok Province. This study provides a contribution to the epidemiology of brucellosis in small ruminants in northern Iraq

    Knowledge, attitudes, and practices (KAPs) of farmers on foot and mouth disease in cattle in Baghlan Province, Afghanistan: A descriptive study

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    This study was performed to investigate the knowledge, attitudes, and practices (KAPs) of farmers, animal traders, and veterinary professionals on FMD in Baghlan province, Afghanistan. Four structured questionnaires were administered to the respondents. Almost half (48.5%) of the farmers had heard of the occurrence of FMD in their neighbourhood or knew the name of the disease. The majority of farmers could recognise the clinical signs of FMD in their animals (salivation, 85.9%; tongue ulcers, 78.8%; gum lesions, 78.2%; hoof lesions, 76.8%). Most farmers stated that the “introduction of new animals” was the primary cause of FMD appearing on their farms and to control the spread of the disease, over half of the farmers (56%) preferred not to buy cattle from unknown or potentially infected sources. Animal traders’ knowledge was limited to recognising some clinical signs of the disease such as: salivation, and lesions in the mouth and on the feet. No animals were directly imported by the traders from outside Afghanistan. Over half of the local veterinary professionals (65%) kept record books of the animal diseases seen and/or treatment plans undertaken, and 80% of them reported the occurrence of FMD to the provincial, regional, and central veterinary authorities. No regular vaccination programme against FMD was implemented in the province. Poor import controls and quarantine were considered to be the main barriers to the control of FMD in the study area and the surrounding provinces. It can be concluded that, despite relatively good knowledge about FMD in the study area, there are gaps in farmers’ and traders’ knowledge that need to be addressed to overcome the burden of the disease in the province. These should focus on strengthening interprovincial quarantine measures and implementation of regular vaccination campaigns against the circulating FMDV within the area
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