9,349 research outputs found
Symbolic Sequences and Tsallis Entropy
We address this work to investigate symbolic sequences with long-range
correlations by using computational simulation. We analyze sequences with two,
three and four symbols that could be repeated times, with the probability
distribution . For these sequences, we verified that
the usual entropy increases more slowly when the symbols are correlated and the
Tsallis entropy exhibits, for a suitable choice of , a linear behavior. We
also study the chain as a random walk-like process and observe a nonusual
diffusive behavior depending on the values of the parameter .Comment: Published in the Brazilian Journal of Physic
Testosterone insulin-like effects: an in vitro study on the short-term metabolic effects of testosterone in human skeletal muscle cells
Testosterone by promoting different metabolic pathways contributes to short-term homeostasis of skeletal muscle, the largest insulin-sensitive tissue and the primary site for insulin-stimulated glucose utilization. Despite evidences indicate a close relationship between testosterone and glucose metabolism, the molecular mechanisms responsible for a possible testosterone-mediated insulin-like effects on skeletal muscle are still unknown
Parametric Analysis of a Heavy Metal Sorption Isotherm Based on Fractional Calculus
Heavy metals are widely recognized as being hazardous to human health and environmentally aggressive. The literature reports different approaches for lead removal, for example, water hyacinths. Heavy metal sorption isotherm modeling represents an important tool towards the study of equilibrium conditions. Fractional calculus represents a novel approach and a growing research field for process modeling, based on derivatives of arbitrary order. Recently, a novel isotherm based on fractional calculus was proposed for lead sorption using water hyacinth (Eichhornia crassipes). This paper reports a general procedure on error analysis and its influence on parameter estimation. It was applied to mathematical models based on fractional differential equations, focusing on a heavy metal novel isotherm sorption model. Parameter variance was calculated by using two different approaches (with the complete Hessian matrix and with a simplified Hessian matrix), and joint parameter confidence regions were generated, being successfully able to show that the fractional nature of the model is statistically valid
Noise Generation in Household Refrigerators: An Experimental Study on fluid Borne Noise
The oscillatory pressure disturbance created by the refrigerant flow through pipes and components is one of the main sources of noise in household refrigerators. This type of excitation is transmitted to the pipes and travels through the structure reaching the cabinet and other parts exposed to the air, where audible airborne sound waves are created. In order to get a better understanding of this type of noise a household refrigerator was especially instrumented with thermocouples, absolute and dynamic pressure transducers and accelerometers. Tests were carried out at different operating conditions, when it was found that the compressor was the main source of excitation, practically affecting the entire refrigeration loop. It was also found that the flow velocity at the outlet of the capillary tube was high enough to induce significant vibrations in the evaporator. Finally, it was found that the entrance of vapor bubbles in the capillary tube produces sporadic and strong excitations. However those excitations do not travel very far along the flow, being attenuated by the condenser and the evaporator, but can nevertheless be transmitted to the pipes. In view of the collected database, comments and suggestions concerning the design of household refrigerators are presented and discussed
Microscopic cluster model for the description of (18O,16O) two-neutron transfer reactions
Excitation energy spectra and absolute cross-section angular distributions were measured for the 13C(18O,16O)15C two-neutron transfer reaction at 84 MeV incident energy. Exact finite-range coupled reaction channel calculations are used to analyse the data considering both the direct two-neutron transfer and the two-step sequential mechanism. For the direct calculations, two approaches are discussed: The extreme cluster and the newly introduced microscopic cluster. The latter makes use of spectroscopic amplitudes in the centre-of-mass reference frame, derived from shell-model calculations. The results describe well the experimental cross sections
Microscopic cluster model for the description of new experimental results on the C 13 (O 18, O 16) C 15 two-neutron transfer at 84 MeV incident energy
The C13(O18,O16)C15 reaction is studied at 84 MeV incident energy. Excitation energy spectra and absolute cross-section angular distributions for the strongest transitions are measured with good energy and angular resolutions. Strong selectivity for two-neutron configurations in the states of the residual nucleus is found. The measured cross-section angular distributions are analyzed by exact finite-range coupled reaction channel calculations. The two-particle wave functions are extracted using the extreme cluster and the independent coordinate scheme with shell-model derived coupling strengths. A new approach also is introduced, the microscopic cluster, in which the spectroscopic amplitudes in the center-of-mass reference frame are derived from shell-model calculations using the Moshinsky transformation brackets. This new model is able to describe well the experimental cross section and to highlight cluster configurations in the involved wave functions
Amino acids and hypertension in adults
Accumulating evidence suggests a potential role of dietary protein among nutritional factors interfering with the regulation of blood pressure. Dietary protein source (plant versus animal protein), and especially, protein composition in terms of amino acids has been postulated to interfere with mechanisms underlying the development of hypertension. Recently, mounting interest has been directed at amino acids in hypertension focusing on habitual dietary intake and their circulating levels regardless of single amino acid dietary supplementation. The aim of the present review was to summarize epidemiological evidence concerning the connection between amino acids and hypertension. Due to the large variability in methodologies used for assessing amino acid levels and heterogeneity in the results obtained, it was not possible to draw robust conclusions. Indeed, some classes of amino acids or individual amino acids showed non-causative association with blood pressure as well as the incidence of hypertension, but the evidence was far from being conclusive. Further research should be prompted for a thorough understanding of amino acid effects and synergistic actions of different amino acid classes on blood pressure regulation
Which physical activity in patients affected by hypoparathyroidism? A review of the literature and practical recommendations
Background Hypoparathyroidism (HypoP) is a rare endocrine condition characterized by hypocalcaemia and hyperphos- phatemia, as a consequence of absent or improperly low parathyroid hormone (PTH) levels. Patients affected by HypoP have a clinical condition often characterized by paresthesias and muscle spasms, as well as long-term consequences as nephro- lithiasis, extraskeletal calcification, and fractures. In the literature, likely due to these symptoms, few data exist regarding the appropriate physical activity (PA) in subjects suffering from HypoP.
Purpose This review evaluates the literature on exercise-based approaches to the management of individuals affected by HypoP and evaluates: (1) the effects of physical exercise on muscle cramps and other clinical symptoms; (2) the effects of exercise on PTH and calcium level; (3) the most suitable clinical exercise testing; and (4) the most suitable exercise combination.
Methods and results A systematic search was conducted using the databases MEDLINE, Google Scholar using âhypopar- athyroidism AND Physical Activityâ, âTraining AND hypoparathyroidismâ, âExercise AND muscle crampsâ, âExercise AND Fatigueâ as keywords. In addition, references list from the included articles were searched and cross-checked to identify any further potentially eligible studies. A total of 50 manuscripts were found among which 39 manuscripts were selected. A few clinical studies have been performed in HypoP patients to evaluate PA training protocols.
Conclusion Although further research is needed to draw solid conclusions regarding best PA protocols in subjects affected by HypoP, a PA protocol has been proposed within the manuscript to encourage patients to attempt exercise to improve their clinical conditions and their quality of life
Weighing Super-Massive Black Holes with Narrow Fe K Line
It has been suggested that the narrow cores of the Fe K emission
lines in Active Galactic Nuclei (AGNs) are likely produced in the torus, the
inner radius of which can be measured by observing the lag time between the
and band flux variations. In this paper we compare the virial products of
the infrared time lags and the narrow Fe K widths for 10 type 1 AGNs
with the black hole masses from other techniques. We find the narrow Fe
K line width is in average 2.6 times broader than
expected assuming an isotropic velocity distribution of the torus at the
distance measured by the infrared lags. We propose the thick disk model of the
torus could explain the observed larger line width. Another possibility is the
contamination by emission from the broad line region or the outer accretion
disk. Alternatively, the narrow iron line might originate from the inner most
part of the obscuring torus within the sublimation radius, while the infrared
emission from outer cooler part. We note the correlation between the black hole
masses based on this new technique and those based on other known techniques is
statistically insignificant. We argue that this could be attributed to the
small sample size and the very large uncertainties in the measurements of iron
K line widths. The next generation of X-ray observatories could help verify the
origin of the narrow iron K line and the reliability of this new
technique.Comment: 12 pages, 2 figures, 2 tables, Science China G, in pres
Histochemical characterisation and gene expression analysis of skeletal muscles from maremmana and aubrac steers reared on grazing and feedlot systems
This study aimed to characterise the fibre composition of Triceps brachii (TB) and Semimem-branosus (SM) muscles from 20 Maremmana (MA) and 20 Aubrac (AU) steers, and the effect of grazing activity in comparison with feedlot system. The histochemical method was performed with the m-ATPase method with an acid pre-incubation, thus allowing to distinguish type I, IIA, and IIB fibres. Additionally, on total RNA extracted from SM muscle, the expressions of atp1a1, mt-atp6, and capn1 genes were evaluated, in order to find potential associations with muscle fibre histochemical characteristics. In SM muscle, the MA steers had the greater frequency of oxidative fibres (type I and IIA) and the higher atp1a1 expression, in comparison to AU steers. Conversely, AU steers had a greater frequency of type IIB fibres, and the higher capn1 expression. A similar histochemical pattern was observed in TB muscle. The grazing activity was probably insufficient to determine differences both for fibre proportion and size, and gene expressions, except for mt-atp6 expression that was surprisingly highest in feedlot MA in comparison to other steers. These findings further the knowledge of muscle properties belonging to these breeds, and the effect of voluntary physical activity since few studies were available in this regard
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