104 research outputs found

    Relevance of using the equipment for control of fishing gear to reduce inaccuracy in evaluation of marine organisms abundance

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    Geometric parameters of the bottom trawl DT 27.1/24.4 were tested aboard RV TINRO in the Bering Sea using the acoustic equipment «Scanmar» (Norway). Possible errors in the estimates of marine organisms abundance by bottom trawl survey are calculated for different species by comparing the actual data on the trawl geometry with the fixed constant value of its horizontal opening. The obtained data can be used for evaluation of the hauled area in bottom trawl surveys

    Foam Metals High-Temperature Electrical Characteristics’ Investigation

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    In the work presented we have carried out experimental investigations of high- temperature electrophysical properties of foam metals. We have obtained data of foam nickel and foam copper resistivity and temperature coefficients of resistance (TCR) versus their plane deformation degree within the temperature range from 100 to 950 ºС

    Hydrodynamics Model of Temperature Variation due to Gas Flaring activities in some parts of Niger Delta Area of Nigeria

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    This research is investigating the Hydrodynamics Model of Temperature Variation due to Gas Flaring activities in some parts of Niger Delta Area of Nigeria. The unsteady flow of radiative heat flux is represented using mathematical techniques to model the basic equations of fluid in motion by radiative transfer process using general differential forms. Laplace transform is used to obtain expressions for Temperature, Velocity, etc to solve problems of heat flow. The use the continuity, momentum, Navier-Stokes, Dasey and Energy equations is exploited. The results show that radiation parameter influences the variation of temperature distribution in the environment

    Review of Mathematical Modelling of the Time Dependent Schrodinger Wave Equation using Different methods

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    This paper focuses on the principle of time dependent Schrödinger equation (TDSE) which simplified so many reviewed ideas, class room teaching, research ideologies and personal study meant for advanced knowledge. In this research work,  the enlightenment of the basic concept of Schrödinger wave equation to improve knowledge about simple ways for mathematical understanding in deriving TDSE using different technique in more comprehensive approach. The research shows clearly that TDSE can be derived using time independent equation, wave mechanics, classical & Hamilton-Jacobi’s equations. Different methods and ways by different researchers/scholars have been used in the past. In this paper, we review the quantum field theoretic route to the Schrodinger wave equation which treats time and space as parameters, not operators. Furthermore, we recall that a classical (nonlinear) wave equation can be derived from the classical action via Hamiltonian-Jacobi theory. By requiring the wave equation to be linear we again arrive at the Schrodinger equation, without postulating operator relations. The underlying philosophy is operational. Surely, a particle is what a particle detector detects. This leads us to a useful physical picture combining the wave (field) and particle paradigms which points the way to the time-dependent Schrodinger equation. However, the result provides a comprehensive well derived derivation, derived using various approaches, which would make this research a unique one from different areas of specializations

    Higher Responsiveness of Pattern Generation Circuitry to Sensory Stimulation in Healthy Humans Is Associated with a Larger Hoffmann Reflex

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    Simple Summary Individual differences in the sensorimotor circuitry play an important role for understanding the nature of behavioral variability and developing personalized therapies. While the spinal network likely requires relatively rigid organization, it becomes increasingly evident that adaptability and inter-individual variability in the functioning of the neuronal circuitry is present not only in the brain but also in the spinal cord. In this study we investigated the relationship between the excitability of pattern generation circuitry and segmental reflexes in healthy humans. We found that the high individual responsiveness of pattern generation circuitries to tonic sensory input in both the upper and lower limbs was related to larger H-reflexes. The results provide further evidence for the importance of physiologically relevant assessments of spinal cord neuromodulation and the individual physiological state of reflex pathways. The state and excitability of pattern generators are attracting the increasing interest of neurophysiologists and clinicians for understanding the mechanisms of the rhythmogenesis and neuromodulation of the human spinal cord. It has been previously shown that tonic sensory stimulation can elicit non-voluntary stepping-like movements in non-injured subjects when their limbs were placed in a gravity-neutral unloading apparatus. However, large individual differences in responsiveness to such stimuli were observed, so that the effects of sensory neuromodulation manifest only in some of the subjects. Given that spinal reflexes are an integral part of the neuronal circuitry, here we investigated the extent to which spinal pattern generation excitability in response to the vibrostimulation of muscle proprioceptors can be related to the H-reflex magnitude, in both the lower and upper limbs. For the H-reflex measurements, three conditions were used: stationary limbs, voluntary limb movement and passive limb movement. The results showed that the H-reflex was considerably higher in the group of participants who demonstrated non-voluntary rhythmic responses than it was in the participants who did not demonstrate them. Our findings are consistent with the idea that spinal reflex measurements play important roles in assessing the rhythmogenesis of the spinal cord

    Polynomial unconstrained binary optimisation inspired by optical simulation

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    We propose an algorithm inspired by optical coherent Ising machines to solve the problem of polynomial unconstrained binary optimisation (PUBO). We benchmark the proposed algorithm against existing PUBO algorithms on the extended Sherrington-Kirkpatrick model and random third-degree polynomial pseudo-Boolean functions, and observe its superior performance. We also address instances of practically relevant computational problems such as protein folding and electronic structure calculations with problem sizes not accessible to existing quantum annealing devices. In particular, we successfully find the lowest-energy conformation of lattice protein molecules containing up to eleven amino-acids. The application of our algorithm to quantum chemistry sheds light on the shortcomings of approximating the electronic structure problem by a PUBO problem, which, in turn, puts into question the applicability of quantum annealers in this context.Comment: 10 pages, 6 figure

    Dynamic magnetic response of a ferrofluid in a static uniform magnetic field

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    A theory for the frequency-dependent magnetic susceptibility of a ferrofluid in a static uniform magnetic field is developed, including the dipolar interactions between the constituent particles. Interactions are included within the framework of modified mean-field theory. Predictions are given for the linear responses of the magnetization to a probing ac field both parallel and perpendicular to the static field and are tested against results from Brownian dynamics simulations. The effects of the particle concentration and dipolar coupling constant on the field-dependent static susceptibilities and the frequency dispersions are shown to be substantial, which justifies taking proper account of the interactions between particles. The theory is reliable provided that the volume concentration and dipolar coupling constant are not too large and within the range of values for real ferrofluids. © 2018 American Physical Society

    Predictors of visceral obesity in normal weight obstructive sleep apnea patients

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    BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is epidemiologically related to adverse cardiovascular outcomes. The pathophysiology clues are metabolic changes and obesity. The most studied anthropometric predictors of obesity, such as body mass index (BMI), waist circumference (WC), are influenced by various factors such as sex, type of constitution, hydration balance. The normal range of BMI and WC limits the diagnostic search for metabolic disturbances and visceral obesity in patients with respiratory sleep distress and can lead to increased cardiovascular risks. AIMS: to investigate the visceral obesity predictors in normal weight patients with obstructive sleep apnea syndrome. MATERIALS AND METHODS: We had performed а cross-sectional study, 68 patients were examined with mean age of 38.24 ± 7.4 years. The main group (38 individuals) was represented by patients with OSAS. The control group consisted of healthy individuals without OSAS. Alternative markers of visceral obesity, such as lipid accumulation products, visceral obesity index, conicity index have been studied. RESULTS: In the main group we found different disorders of lipid metabolism such as the increase in triglyceride levels by 94%, low-density lipids by 32%, total cholesterol by 10% compared with the control group. Anthropometric evidence was obtained for excessive fat accumulation in patients with normal body weight and OSAS: WC was 89.6 ± 5.7 cm in the main group and was higher than in the control group 83.7 ± 6.3 cm (p = 0.024) due to an increase in the visceral fat compartment, as evidenced by the conicity index (67.2 ± 7.0 and 59.3 ± 6.2 respectively, p = 0.032) and waist to height ratio (0.58 ± 0.05 and 0.53 ± 0.04 in the main and control groups, respectively, p = 0.041). Correlation relationships between the severity of sleep apnea syndrome and visceral obesity indicators were revealed. CONCLUSIONS: Normal weight patients with breathing disorders are at risk of visceral fat obesity and, thereby, increased cardiovascular risk. Assessment of additional markers of visceral obesity in patients with normal body weight and sleep apnea is recommended to include in the dynamic observation programms

    Clinical features of the course of tuberculous meningitis in HIV-infected patients

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    Background. Central nervous system tuberculosis is one of the most severe forms of extrapulmonary tuberculosis, which is due to an unfavorable clinical course, a high incidence of neurological complications and deaths. Despite this, the problem of early diagnosis is still not solved. Aim. To study the clinical and laboratory-instrumental features of the early diagnosis of tuberculous meningitis in HIV-infected patients. Materials and methods. A retrospective analysis of 31 case histories of patients with tuberculous lesions of the meninges and central nervous system in the late stages of HIV infection who were treated at the Clinical Tuberculosis Dispensary of Krasnodar Territory in 20202022 was carried out. The data of clinical manifestations of the disease, the results of laboratory and instrumental methods of examination were analyzed. Statistical data processing was performed by Microsoft Office Excel 2021 with the calculation of averages, standard deviation. Results. Tuberculous lesions of the meninges and the central nervous system among HIV-infected people were more common in men of working age who were not previously registered in a tuberculosis dispensary. All HIV-infected patients had late stages of HIV infection with severe immunodeficiency: the content of CD4+ lymphocytes less than 100 cells was detected in 45.46%; from 100 to 200 cells/l of CD4+ lymphocytes were recorded in 36.36%, more than 200 cells/l in 18.18%. Also, in all the studied patients, the primary focus was established in the form of tuberculosis of the respiratory organs, represented in 56.52% of cases by disseminated pulmonary tuberculosis. More than 70% had generalized tuberculosis with damage to the kidneys, spleen, and peripheral lymph nodes. A feature of the manifestation of tuberculous meningitis in HIV-infected people can be considered a high frequency of acute increase in neurological symptoms. Of the cerebral manifestations, the most common were: headache, dizziness, photophobia. 13.04% of HIV-infected patients complained of nausea and vomiting. 91.30% showed signs of damage to the substance of the brain, represented by mono-, hemiparesis and damage to the cranial nerves, mainly IIIIV, VI, VII pairs. The composition of CSF in HIV-positive patients revealed the presence of mild pleocytosis (up to 100 cells/l) in 56.52% of cases. The nature of the change in the concentration of proteins, chlorides and glucose is nonspecific. Conclusions. The study revealed the features of medical and social characteristics, clinical and laboratory and instrumental picture of tuberculous meningitis in HIV-infected patients and without HIV infection
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