56 research outputs found

    The ovary learns to ovulate

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    Sensory stimuli from the external environment (e.g. visual and olfactory stimuli, stress) or internal stimuli cause brain nerve fibres to release neurotransmitters (catecholamines, indolamines and cholinergic agents). These neurotransmitters regulate the secretion of gonadotrophin-releasing hormone (GnRH) from neurosecretory cells of the hypothalamus (Kamberi, 1975). It would seem that under the proper steroid environment, catecholamines (dopamine, norepinephrine or epinephrine) and the cholinergic agent acetylcholine exert a stimulatory influence, whereas indolamines (serotonin or its metabolic product, melatonin) have an opposite effect. In turn, GnRH reaches the anterior pituitary via the hypophyseal portal system, and, through the mediation of cAMP [though may be not as an obligatory intermediate (Naor et al., 1975)], controls gonadotrophin secretion (Labrie et al., 1974

    In-plane anisotropy of electrical transport in Y0.85_{0.85}Tb0.15_{0.15}Ba2_2Cu3_3O7−x_{7-x} films

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    We fabricate high-quality c-axis oriented epitaxial YBa2_2Cu3_3O7−x_{7-x} films with 15% of yttrium atoms replaced by terbium (YTBCO) and study their electrical properties. The Tb substitution reduces the charge carrier density resulting in increased resistivity and decreased critical current density compared to the pure YBa2_2Cu3_3O7−x_{7-x} films. The electrical properties of the YTBCO films show an in-plane anisotropy in both the superconducting and normal state providing evidence for the twin-free film. Unexpectedly, the resistive transition of the bridges also demonstrates the in-plane anisotropy that can be explained within the framework of Tinkham's model of the resistive transition and the Berezinskii-Kosterlitz-Thouless (BKT) model depending on the sample parameters. We consider YTBCO films to be a promising platform for both the fundamental research on the BKT transition in the cuprate superconductors and for the fabrication of devices with high kinetic inductance

    A giant right atrial myxoma with pulmonary arterial hypertension

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    Here we report a case of a right atrial mass that morphology mimicking myxoma, in a young patient with no past medical history. The mass was pathologically confirmed to be symptomatic and surgical removal was successfully done

    Cardiac disease in patients with mucopolysaccharidosis: presentation, diagnosis and management

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    The mucopolysaccharidoses (MPSs) are inherited lysosomal storage disorders caused by the absence of functional enzymes that contribute to the degradation of glycosaminoglycans (GAGs). The progressive systemic deposition of GAGs results in multi-organ system dysfunction that varies with the particular GAG deposited and the specific enzyme mutation(s) present. Cardiac involvement has been reported in all MPS syndromes and is a common and early feature, particularly for those with MPS I, II, and VI. Cardiac valve thickening, dysfunction (more severe for left-sided than for right-sided valves), and hypertrophy are commonly present; conduction abnormalities, coronary artery and other vascular involvement may also occur. Cardiac disease emerges silently and contributes significantly to early mortality

    Integrating anaerobic digestion and pyrolysis for treating digestates derived from sewage sludge and fat wastes

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    P. 32603-32614The coupling of biological and thermal technologies allows for the complete conversion of wastes into energy and biochar eliminating the problem of sludge disposal. The valorisation of fatty residues as co-substrate in a mesophilic digester of a wastewater treatment plant was studied considering an integrated approach of co-digestion and pyrolysis. Four digested samples obtained from co-digestion of sewage sludge and butcher’s fat waste were studied by thermogravimetric analysis. The activation energy corresponding to the sludge pyrolysis was calculated by a non-isothermal kinetic. Arrhenius activation energy was lower for the pyrolysis of a digested grease sample (92 kJ mol−1 obtained by OFW and 86 kJ mol−1 obtained by Vyazovkin) than for the pyrolysis of sewage sludge and its blends (164–190 kJ mol−1 obtained by OFW and 162–190 kJ mol−1 obtained by Vyazovkin). The analysis of the integrated approach of anaerobic co-digestion and pyrolysis of digestates demonstrated that the addition of 3% (w/v) of fat to the feeding sludge results in a 25% increase in the electricity obtained from biogas (if a combined heat and power unit is considered for biogas valorisation) and increasing the fat content to 15% allows for covering all thermal needs for drying of digestate and more than doubles (2.4 times) the electricity production when the scenario of digestion and pyrolysis is contemplated.S

    MPPT of PEM Fuel Cell Using PI-PD Controller Based on Golden Jackal Optimization Algorithm

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    Subversive environmental impacts and limited amounts of conventional forms of energy necessitate the utilization of renewable energies (REs). Unfortunately, REs such as solar and wind energies are intermittent, so they should be stored in other forms to be used during their absence. One of the finest storage techniques for REs is based on hydrogen generation via an electrolyzer during abundance, then electricity generation by fuel cell (FC) during their absence. With reference to the advantages of the proton exchange membrane fuel cell (PEM-FC), this is preferred over other kinds of FCs. The output power of the PEM-FC is not constant, since it depends on hydrogen pressure, cell temperature, and electric load. Therefore, a maximum power point tracking (MPPT) system should be utilized with PEM-FC. The techniques previously utilized have some disadvantages, such as slowness of response and largeness of each oscillation, overshoot and undershoot, so this article addresses an innovative MPPT for PEM-FC using a consecutive controller made up of proportional-integral (PI) and proportional-derivative (PD) controllers whose gains are tuned via the golden jackal optimization algorithm (GJOA). Simulation results when applying the GJOA-PI-PD controller for MPPT of PEM-FC reveal its advantages over other approaches according to quickness of response, smallness of oscillations, and tininess of overshoot and undershoot. The overshoot resulting using the GJOA-PI-PD controller for MPPT of PEM-FC is smaller than that of perturb and observe, GJOA-PID, and GJOA-FOPID controllers by 98.26%, 86.30%, and 89.07%, respectively. Additionally, the fitness function resulting when using the GJOA-PI-PD controller for MPPT of PEM-FC is smaller than that of the aforementioned approaches by 93.95%, 87.17%, and 87.97%, respectively
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