52 research outputs found

    Decay of neutron-rich Mn nuclides and deformation of heavy Fe isotopes

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    The use of chemically selective laser ionization combined with beta-delayed neutron counting at CERN/ISOLDE has permitted identification and half-life measurements for 623-ms Mn-61 up through 14-ms Mn-69. The measured half-lives are found to be significantly longer near N=40 than the values calculated with a QRPA shell model using ground-state deformations from the FRDM and ETFSI models. Gamma-ray singles and coincidence spectroscopy has been performed for Mn-64 and Mn-66 decays to levels of Fe-64 and Fe-66, revealing a significant drop in the energy of the first 2+ state in these nuclides that suggests an unanticipated increase in collectivity near N=40

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    A chemically selective laser ion source has been used in a ÎČ\beta-decay study of heavy Ag isotopes into even-even Cd nuclides. Gamma-spectroscopic techniques in time-resolving event-by-event and multiscaling modes have permitted the identification of the first 2+^+ and 4+^+ levels in 126^{126}Cd78_{78}, 128^{128}Cd80_{80}, and tentatively the 2+^+ state in 130^{130}Cd82_{82}. From a comparison of these new states in 48_{48}Cd with the E(2+)E(2^+) and E(4+)/E(2+)E(4^+)/E(2^+) level systematics of 46_{46}Pd and 52_{52}Te isotopes and several recent model predictions, possible evidence for a weakening of the spherical N=82N=82 neutron-shell below double-magic 132^{132}Sn is obtained

    Variable liver fat concentration as a proxy for body fat mobilization postpartum has minor effects on insulin-induced changes in hepatic gene expression related to energy metabolism in dairy cows.

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    The liver plays a central role in adaptation for energy requirements around calving, and changes in the effects of insulin on hepatic energy metabolism contribute to metabolic adaptation in dairy cows. Hepatic insulin effects may depend on body fat mobilization. The objective of this study was to investigate the effects of insulin on the hepatic gene expression of enzymes involved in energy metabolism and factors related to nutrition partitioning in cows with high and low total liver fat concentration (LFC) after calving. Holstein cows were retrospectively grouped according to their LFC after calving as a proxy for body fat mobilization. Cows were classified as low (LLFC; LFC 24.4% fat/dry matter; n = 10) fat-mobilizing after calving. Euglycemic-hyperinsulinemic clamps [6 mU/(kg × min) of insulin for 6 h] were performed in wk 5 antepartum (ap) and wk 3 postpartum (pp). Before and at the end of the euglycemic-hyperinsulinemic clamps, liver biopsies were taken to measure the mRNA abundance of enzymes involved in carbohydrate and lipid metabolism, expression related to the somatotropic axis, and adrenergic and glucocorticoid receptors. The mRNA abundance of pyruvate carboxylase, cytosolic phosphoenolpyruvate carboxykinase (PEPCK; PCK1), acyl-CoA-dehydrogenase very long chain (ACADVL), and hydroxyl-methyl-glutaryl-CoA-synthase 1 increased, but the mRNA abundance of solute carrier family 2 (SLC2A2 and SLC2A4), growth hormone receptor 1A (GHR1A), insulin-like growth factor 1 (IGF1), sterol regulatory element binding factor 1, adrenoceptor α 1A, and glucocorticoid receptor decreased from ap to pp. Insulin treatment was associated with decreased PCK1, mitochondrial PEPCK, glucose-6-phosphatase, propionyl-CoA-carboxylase α, carnitine-palmitoyl-transferase 1A, ACADVL, and insulin receptor mRNA, but increased IGF1 and SLC2A4 mRNA ap and pp and GHR1A mRNA pp. The mRNA abundance of SLC2A4 was greater, and the mRNA abundance of GHR1A and IGF1 tended to be lower in LLFC than in HLFC. Administration of insulin, albeit at a supraphysiological dose, was associated with inhibition of gene expression related to glucose production and ÎČ-oxidation, but we observed variable effects in the degree of insulin depression of individual genes. Insulin status is important for regulation of nutrient partitioning, but different LFC pp had very little influence on changes in hepatic gene expression following administration of insulin

    Indices of heart rate variability as potential early markers of metabolic stress and compromised regulatory capacity in dried-off high-yielding dairy cows

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    High performing dairy cows experience distinct metabolic stress during periods of negative energy balance. Subclinical disorders of the cow’s energy metabolism facilitate failure of adaptational responses resulting in health problems and reduced performance. The autonomic nervous system (ANS) with its sympathetic and parasympathetic branches plays a predominant role in adaption to inadequate energy and/or fuel availability and mediation of the stress response. Therefore, we hypothesize that indices of heart rate variability (HRV) that reflect ANS activity and sympatho-vagal balance could be early markers of metabolic stress, and possibly useful to predict cows with compromised regulatory capacity. In this study we analysed the autonomic regulation and stress level of 10 pregnant dried-off German Holstein cows before, during and after a 10-h fasting period by using a wide range of HRV parameters. In addition heat production (HP), energy balance, feed intake, rumen fermentative activity, physical activity, non-esterified fatty acids, ÎČ-hydroxybutyric acid, cortisol and total ghrelin plasma concentrations, and body temperature (BT) were measured. In all cows fasting induced immediate regulatory adjustments including increased lipolysis (84%) and total ghrelin levels (179%), reduction of HP (−16%), standing time (−38%) and heart rate (−15%). However, by analysing frequency domain parameters of HRV (high-frequency (HF) and low-frequency (LF) components, ratio LF/HF) cows could be retrospectively assigned to groups reacting to food removal with increased or decreased activity of the parasympathetic branch of the ANS. Regression analysis reveals that under control conditions (feeding ad libitum) group differences were best predicted by the nonlinear domain HRV component Maxline (L MAX, R 2=0.76, threshold; TS=258). Compared with cows having L MAX values above TS (>L MAX: 348±17), those with L MAX values below TS (<L MAX: 109±26) had higher basal blood cortisol levels, lower concentrations of insulin, and respond to fasting with a shift of their sympatho-vagal balance towards a much stronger dominance of the sympathetic branch of the ANS and development of stress-induced hyperthermia. The data indicate a higher stress level, reduced well-being and restricted regulatory capacity in <L MAX cows. This assumption is in accord with the lower dry matter intake and energy corrected milk yield (16.0±0.7 and 42±2 kg/day) in lactating <L MAX compared with >L MAX cows (18.5±0.4 and 47.3 kg/day). From the present study, it seems conceivable that L MAX can be used as a predictive marker to discover alterations in central autonomic regulation that might precede metabolic disturbances
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