4781. Hair cortisol and testosterone concentrations and semen production of Bos taurus bullsGiuseppe Stradaioli, Tanja Peric, Marta Montillo, Antonella Comin, Mirco Corazzin, Maria Cristina Veronesi, Alberto Prandi, 2017, izvirni znanstveni članek Opis: The experiment was aimed to evaluate the usefulness of hair cortisol concentrations (HCC) in revealing the activation of the hypothalamic-pituitary-adrenal (HPA) axis due to the passage of
young bulls from genetic rearing stations to artificial insemination (AI) centre and the influence of this passage on hair testosterone concentrations (HTC). Hair samples on 33 yearling bulls were collected at the time of arrival (ST1) to the AI centre and 3 more hair samples (ST2, ST3, ST4) were collected at monthly intervals. After the end of quarantine each animal was submitted to the standard procedures for collection and production of semen. Overall HCC were significantly affected by period of collection (p<.01). In particular, HCC was higher in samples obtained after finishing the quarantine period (ST2) compared with those obtained on ST1. After ST2, the HCC decreased reaching at ST4 a value similar to that recorded at ST1. An effect of sampling time on HTC was not found (p>.05). The effect of breed was observed only for HTC that was higher in PRI than BS (p<.01). The HCC group have not influenced the semen variables
(p>.05). On the contrary, the effect of breed was evident. The results of this study replicated the effects of a major environmental stressor on mean cortisol concentrations assessed in hair, and add to the growing body of evidence that HCC is an effective and simply collected marker for long-term activity of the HPA system in response to persistent environmental challenge.
Ključne besede: Hair, bulls, cortisol, testosterone, semen
Objavljeno v RUNG: 20.03.2017; Ogledov: 5585; Prenosov: 0
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4782. Stability by linear approximation for time scale dynamical systemsSergey Kryzhevich, Alexander Nazarov, 2017, izvirni znanstveni članek Opis: We study systems on time scales that are generalizations of classical differential or difference equations and appear in numerical methods. In this paper we consider linear systems and their small nonlinear perturbations. In terms of time scales and of eigenvalues of matrices we formulate conditions, sufficient for stability by linear approximation. For non-periodic time scales we use techniques of central upper Lyapunov exponents (a common tool of the theory of linear ODEs) to study stability of solutions. Also, time scale versions of the famous Chetaev’s theorem on conditional instability are proved. In a nutshell, we have developed a completely new technique in order to demonstrate that methods of non-autonomous linear ODE theory may work for time-scale dynamics.
Ključne besede: Time scale system, Linearization, Lyapunov functions, Millionschikov rotations, Stability
Objavljeno v RUNG: 15.03.2017; Ogledov: 4024; Prenosov: 160
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4786. Transparent titania-zirconia thin films for self-cleaning and photocatalytic applicationNives Vodišek, Kandalam Ramanujachary, Vlasta Brezová, Urška Lavrenčič Štangar, 2016, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Thin films were prepared by sol-gel process, where different amount of zirconia were added to titania.
Photocatalytic activity of thin films was measured by two methods i) determination of degradation ration of methyl stearate with measuring the contact angle and ii) formation of hydroxyterephthalic acid was measured by spectrofluorometer.
Prepared samples were characterized by UV-Vis spectrophotometer, SEM, XRD, FT-IR ATR, and BET.
The result of measurements of photocatalytic activity shows that the highest activity has a sample without addition of zirconia, but mechanical stability of that sample is worse.
Ključne besede: photocatalysis, ZrO2/ TiO2, thin films, self-cleaning, low-temperature, sol-gel process
Objavljeno v RUNG: 14.03.2017; Ogledov: 5139; Prenosov: 203
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