60 research outputs found

    On metal-deficient barium stars and their link with yellow symbiotic stars

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    This paper addresses the question of why metal-deficient barium stars are not yellow symbiotic stars (YSyS). Samples of (suspected) metal-deficient barium (mdBa) stars and YSyS have been collected from the literature, and their properties reviewed. It appears in particular that the barium nature of the suspected mdBa stars needs to be ascertained by detailed abundance analyses. Abundances are therefore derived for two of them, HD 139409 and HD 148897, which reveal that HD 148897 should not be considered a barium star. HD 139409 is a mild barium star, with overabundances observed only for elements belonging to the first s-process peak (Y and Zr). The evidence for binarity among mdBa stars is then reviewed, using three different methods: (i) radial-velocity variations (from CORAVEL observations), (ii) Hipparcos astrometric data, and (iii) a method based on the comparison between the Hipparcos and Tycho-2 proper motions. A first-time orbit is obtained for HIP 55852, whereas evidence for the (so far unknown) binary nature of HIP 34795, HIP 76605, HIP 97874 and HIP 107478 is presented. Two stars with no evidence for binarity whatsoever (HIP 58596 and BD +3 2688) are candidates low-metallicity thermally-pulsing asymptotic giant branch stars, as inferred from their large luminosities. The reason why mdBa stars are not YSyS is suggested to lie in their different orbital period distributions: mdBa stars have on average longer orbital periods than YSyS, and hence their companion accretes matter at a lower rate, for a given mass loss rate of the giant star. The definite validation of this explanation should nevertheless await the determination of the orbital periods for the many mdBa stars still lacking periods, in order to make the comparison more significant.Comment: Astronomy & Astrophysics, in press; 16 pages, 14 figures; also available at http://www.astro.ulb.ac.be/Html/ps.html#PR

    Highly selective BSA imprinted polyacrylamide hydrogels facilitated by a metal-coding MIP approach

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    We report the fabrication of metal-coded molecularly imprinted polymers (MIPs) using hydrogel-based protein imprinting techniques. A Co(II) complex was prepared using (E)-2-((2 hydrazide-(4-vinylbenzyl) hydrazono)methyl)phenol; along with iron(III) chloroprotoporphyrin (Hemin), vinylferrocene (VFc), zinc (II) protoporphyrin (ZnPP) and protoporphyrin (PP), these complexes were introduced into the MIPs as co-monomers for metal-coding of non-metalloprotein imprints. Results indicate a 66% enhancement for bovine serum albumin (BSA) protein binding capacities (Q, mg/g) via metal-ion/ligand exchange properties within the metal-coded MIPs. Specifically, Co(II)-complex-based MIPs exhibited 92 ± 1% specific binding with Q values of 5.7 ± 0.45 mg BSA/g polymer and imprinting factors (IF) of 14.8 ± 1.9 (MIP/non-imprinted (NIP) control). The selectivity of our Co(II)-coded BSA MIPs were also tested using bovine haemoglobin (BHb), lysozyme (Lyz), and trypsin (Tryp). By evaluating imprinting factors (K), each of the latter proteins was found to have lower affinities in comparison to cognate BSA template. The hydrogels were further characterised by thermal analysis and differential scanning calorimetry (DSC) to assess optimum polymer composition

    Moment and Power of Lower Limb Joints in Running

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    Changes in strength and power performance and serum hormone concentrations during 12 weeks of task‐specific or strength training in conscripts

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    The purpose of this study was to investigate the effects of two different training programs on strength and power performance and serum hormone concentrations. A total of 104 male soldiers volunteered and took part in the 12‐week training period with baseline, mid‐, and post‐measurements of body composition, muscle strength, lower and upper body power, and blood samples to determine serum hormone concentrations. The mean (±SD) age of subjects was 20 ± 1 years, height 180 ± 6 cm and body mass 72.4 ± 8.8 kg. The subjects were divided into three different training groups: soldier task‐specific training (TS), strength training (ST), and control (CON). Each group had a total of 18 training sessions during the 12‐week study. In the muscle strength tests, most improvements could be observed in the TS and ST groups, especially, during the first weeks of the training period. Maximal isometric leg extension force increased significantly by 7.9 ± 12.2% (p < .05) in the TS and 7.1 ± 12.6% (p < .05) in the ST groups between the PRE and MID, as well as between the PRE and POST measurements by 8.1 ± 12.4% (p < .05) in TS and 12.3 ± 15.3% (p < .01) in ST. Serum TES concentration increased significantly in TS between the PRE and MID (16.8 ± 33.9%) and PRE and POST (11.2 ± 16.7%) measurements. Serum COR concentrations decreased in TS between the MID and POST (−7.8 ± 10.9%) and PRE and POST (−11.0 ± 14.3%) measurements. Although the differences observed were rather minor in magnitude, training in the TS and ST groups led to greater improvements in muscle strength and power performance compared to the training in the CON group. The development of strength and/or power of the lower and upper body was greater in the TS and ST groups, which is crucial for warfighter's performance. Therefore, it is important to have a structured resistance‐training program during military training to optimize the strength, power, and military‐specific performance.peerReviewe

    Changes in physical fitness and anthropometrics differ between female and male recruits during the Finnish military service

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    Introduction: Military training programmes are often similar for male and female recruits despite sex differences in physical performance that may influence training adaptations during military service. The present study aimed to compare changes in physical fitness and anthropometrics between Finnish female and male recruits during military service. Methods: A total of 234 690 male and 3549 female recruits participated in fitness tests at the beginning and end of military service between 2005 and 2015. Anthropometric measurements were body mass, height, body mass index (BMI) and waist circumference (WC). Fitness tests consisted 12 min running, standing long jump, and sit-ups and push-ups. Results: No changes were observed in anthropometrics, while both sexes improved most of the fitness test results. After adjustment for service time, branch, age, initial fitness test results, BMI and WC, improvement in running test performance was 158 m (95% CI 142 to 173, p≀0.001) greater in male than female recruits. Similarly, improvements were larger in male recruits for push-ups (5 reps/min, 95% CI 5 to 6, p≀0.001), sit-ups (2 reps/min, 95% CI 2 to 3, p≀0.001) and standing long jump (12 cm, 95% CI 11 to 13, p≀0.001) when compared with women. Conclusions: The study revealed sex differences in adaptations to the standardised military training. Both male and female recruits improved their physical fitness, but smaller gains were observed in women using the same training programme. The mechanisms explaining sex differences in adaptations to military training, and whether tailored training programmes are needed specifically for female recruits to reduce sex differences during military service, warrants further studies.peerReviewe

    Physical fitness and anthropometrics in Finnish soldiers during their early career : prospective changes during a 3-year follow-up

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    Introduction: Physical fitness is a fundamental capability required of military personnel, but studies focusing on longitudinal changes in physical fitness and anthropometrics in soldiers are lacking. The aim was to evaluate physical fitness and anthropometrics in soldiers during their early career. Methods: A 3-year prospective study included 180 male soldiers (baseline age 26±2 years) with measures of a 12 min running test, standing long jump, sit-up and push-up tests, and body mass, height and waist circumference (WC). Baseline data were stratified into tertiles, and the changes within each tertile were analysed using dependent t-tests and analysis of variance. Results: 12 min running test distance decreased on average by 2% (−54 m), sit-up performance 3% (−1.5 repetitions (reps)/min), push-up performance 4% (−1.9 reps/min) and standing long jump performance 1% (−2.1 cm) over the 3-year period (p<0.05). Both aerobic and muscular fitness decreased consistently among the highest baseline tertile (12 min running test: −70 m, sit-ups: −3.2 reps/min, push-ups: −7.5 reps/min, standing long jump: −5.5 cm; p<0.001), whereas both aerobic and muscular fitness levels were maintained and push-up performance was improved (p<0.05) in the lowest baseline tertiles. Body mass increased on average by 4% (+3.4 kg) and WC by 4% (+3.9 cm) (p<0.001), and these increases were observed for all baseline tertiles (p<0.05). Conclusions: Small decrements in physical fitness and anthropometrics exist during the early career of soldiers. The changes in physical fitness differed according to baseline fitness levels. The results indicate that support for exercise training may be needed even in a soldier’s early career.peerReviewe

    Greater levels of cardiorespiratory and muscular fitness are associated with low stress and high mental resources in normal but not overweight men

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    Background: The aim of the present study was to investigate how cardio respiratory (CRF) and muscular fitness (MF) together with leisure-time physical activity (LTPA) influence stress symptoms and mental resources among normal-weight and overweight men, because it is not known how body weight affects this association. Methods: In a cross-sectional study, 824 men (mean ± SD: age 25 ± 5 y, weight 81 ± 13 kg, BMI 25 ± 4 kg/m2 ) underwent CRF and MF tests and completed LTPA and stress questionnaires. For the analysis, the subjects were divided into BMI groups (normal vs. overweight) and CRF / MF / LTPA (low, moderate, high) tertiles. Results: Normal-weight men with low CRF reported 12 % (p = 0.001) more stress symptoms (SS) compared to normal-weight men with moderate CRF, and 13 % (p = 0.004) more SS compared to normal-weight men with high CRF. Normal-weight men with low MF reported 13 % (p = 0.001) higher SS compared to normal-weight men with moderate MF and 16 % (p = 0.002) more SS compared to men with high MF. Among overweight men, there were no significant differences in SS or mental resources (MR) between the low, moderate and high CRF and MF tertiles. Overweight men with high CRF experienced 8 % (p = 0.039) more SS compared to normal-weight participants with high CRF when age, tobacco and alcohol use, MF and LTPA were considered as covariates (p = 0.014). Conclusion: Higher CRF and MF are associated with lower stress and higher mental resources in normal-weight men, but in overweight men, these relationships may differ.peerReviewe
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