30 research outputs found
Low Mass Stars and Brown Dwarfs in Praesepe
Presented are the results of a large and deep optical-near-infrared
multi-epoch survey of the Praesepe open star cluster using data from the UKIDSS
Galactic Clusters Survey. Multiple colour magnitude diagrams were used to
select potential members and proper motions were used to assign levels of
membership probability. From our sample, 145 objects were designated as high
probability members (p >= 0.6) with most of these having been found by previous
surveys although 14 new cluster members are also identified. Our membership
assignment is restricted to the bright sample of objects (Z < 18). From the
fainter sample, 39 candidates were found from an examination of multiple colour
magnitude plots. Of these, 2 have small but significant membership
probabilities. Finally, using theoretical models, cluster luminosity and mass
functions were plotted with the later being fitted with a power law of alpha =
1.11 +/- 0.37 for the mass range 0.6 to 0.125 Msun and an assumed cluster age
of 500 Myrs in the UKIDSS Z photometric band. Likewise taking an assumed
cluster age of 1 Gyr we find alpha = 1.10 +/- 0.37. Similar values were also
found for the J and K bands. These results compare favourably with the result
of Kraus & Hillenbrand (2007) (alpha = 1.4 +/- 0.2) but are significantly lower
than that of the more recent study conducted by Boudreault et al. (2009) (alpha
= 1.8 +/- 0.1).Comment: 21 pages, 11 figures, 3 tables and 4 appendices. Accepted for
publication in MNRAS, corrected a missing referenc
The effect of vitamin D supplementation on plasma non-oxidised PTH in a randomised clinical trial
Objective: PTH can be oxidised in vivo, rendering it biologically inactive. Non-oxidised PTH (n-oxPTH) may therefore give a better image of the hormonal status of the patient. While vitamin D supplementation decreases total PTH (tPTH) concentration, the effect on n-oxPTH concentration is unexplored. We investigated the effect of vitamin D on n-oxPTH concentration in comparison to tPTH and compared the correlations between parameters of calcium, bone and lipid metabolism with n-oxPTH and tPTH.
Methods: N-oxPTH was measured in 108 vitamin D-insufficient (25(O H)D <75 nmol/L) hypertensive patients, treated with vitamin D (2800 IE daily) or placebo for 8 weeks in the Styrian Vitamin D Hypertension Trial (NCT02136771). We calculated the treatment effect and performed correlation analyses of n-oxPTH and tPTH with parameters of calcium, bone and lipid metabolism and oxidative stress.
Results: After treatment, compared to placebo, 25(OH)D concentrations increased, tPTH decreased by 9% (P < 0.001), n-oxPTH by 7% (P = 0.025) and the ratio of n-oxPTH/tPTH increased (P = 0.027). Changes in phosphate and HDL concentration correlated with changes in n-oxPTH, but not tPTH.
Conclusions: tPTH and n-oxPTH decrease upon vitamin D supplementation. Our study suggests that vitamin D supplementation reduces the oxidation of PTH, as we observed a small but significant increase in the non-oxidised proportion of PTH upon treatment. In addition, we found that changes in phosphate and HDL concentration showed a relationship with changes in n-oxPTH, but not tPTH. This may be explained by the biological activity of n-oxPTH. Further research should be carried out to establish the clinical relevance of n-oxPTH
A photometric long-term study of CP stars in open clusters
Photometric variability of chemically peculiar (CP) stars of the upper main
sequence is closely connected to their local stellar magnetic field and their
rotational period. Long term investigations, as presented here, help us to
identify possible stellar cycles (as in the Sun). Furthermore, these data
provide a basis for detailed surface mapping techniques. Photoelectric
Stroemgren uvby time series for 27 CP stars within the boundaries of open
clusters are presented. In addition, Hipparcos photometric data (from 1989 to
1993) are used for our analysis. Our observations cover a time period of about
six years (1986 to 1992) with typically fifteen measurements for each objects.
These observations help us to determine the rotational periods of these
objects. A standard reduction procedure was applied to the data. When possible,
we merged our data sets with already published ones to obtain a more
significant result. A detailed time series analysis was performed, involving
five different methods to minimize spurious detections. We established, for the
first time, variability for fourteen CP stars. For additional two stars, a
merging of already published data sets, resulted in more precise periods,
whereas for six objects, the published periods could be confirmed. Last, but
not least, no significant variations were found for five stars. Apart from six
stars, all targets seem to be members of their host open clusters.Comment: 10 pages, 3 figures, accepted by Astronomy and Astrophysic
Are soluble ST2 levels influenced by vitamin D and/or the seasons?
Objective: Cardiovascular disease manifestation and several associated surrogate markers, such as vitamin D, have shown substantial seasonal variation. A promising cardiovascular biomarker, soluble ST2 (sST2), has not been investigated in this regard – we therefore determined if systemic levels of sST2 are affected by seasonality and/or vitamin D in order to investigate their clinical interrelation and usability.
Design: sST2 levels were measured in two cohorts involving hypertensive patients at cardiovascular risk, the Styrian Vitamin D Hypertension Trial (study A; RCT design, 8 weeks 2800 IU cholecalciferol daily) and the Ludwigshafen Risk and Cardiovascular Health Study (LURIC; study B; cross-sectional design).
Methods: The effects of a vitamin D intervention on sST2 levels were determined in study A using ANCOVA, while seasonality of sST2 levels was determined in study B using ANOVA.
Results: The concentrations of sST2 remained unchanged by a vitamin D intervention in study A, with a mean treatment effect (95% confidence interval) of 0.1 (−0.6 to 0.8) ng/mL; P = 0.761), despite a rise in 25(OH)D (11.3 (9.2–13.5) ng/mL; P < 0.001) compared to placebo. In study B, seasonal variations were present in 25(OH)D levels in men and women with or without heart failure (P < 0.001 for all subgroups), while sST2 levels remained unaffected by the seasons in all subgroups.
Conclusions: Our study provides the first evidence that systemic sST2 levels are not interrelated with vitamin D levels or influenced by the seasons in subjects at cardiovascular risk
Genetic Fine-Mapping and Identification of Candidate Genes and Variants for Adiposity Traits in Outbred Rats
OBJECTIVE: Obesity is a major risk factor for multiple diseases and is in part heritable, yet the majority of causative genetic variants that drive excessive adiposity remain unknown. Here, outbred heterogeneous stock (HS) rats were used in controlled environmental conditions to fine‐map novel genetic modifiers of adiposity. METHODS:
Body weight and visceral fat pad weights were measured in male HS rats that were also genotyped genome‐wide. Quantitative trait loci (QTL) were identified by genome‐wide association of imputed single‐nucleotide polymorphism (SNP) genotypes using a linear mixed effect model that accounts for unequal relatedness between the HS rats. Candidate genes were assessed by protein modeling and mediation analysis of expression for coding and noncoding variants, respectively. RESULTS: HS rats exhibited large variation in adiposity traits, which were highly heritable and correlated with metabolic health. Fine‐mapping of fat pad weight and body weight revealed three QTL and prioritized five candidate genes. Fat pad weight was associated with missense SNPs in Adcy3 and Prlhr and altered expression of Krtcap3 and Slc30a3, whereas Grid2 was identified as a candidate within the body weight locus. CONCLUSIONS: These data demonstrate the power of HS rats for identification of known and novel heritable mediators of obesity traits
Chemical abundance analysis of the Open Clusters Berkeley 32, NGC 752, Hyades and Praesepe
Context. Open clusters are ideal test particles to study the chemical
evolution of the Galactic disc. However the existing high-resolution abundance
determinations, not only of [Fe/H], but also of other key elements, is largely
insufficient at the moment. Aims. To increase the number of Galactic open
clusters with high quality abundance determinations, and to gather all the
literature determinations published so far. Methods. Using high-resolution
(R~30000), high-quality (S/N$>60 per pixel), we obtained spectra for twelve
stars in four open clusters with the fiber spectrograph FOCES, at the 2.2 Calar
Alto Telescope in Spain. We use the classical equivalent widths analysis to
obtain accurate abundances of sixteen elements: Al, Ba, Ca, Co, Cr, Fe, La, Mg,
Na, Nd, Ni, Sc, Si, Ti, V, Y. Oxygen abundances have been derived through
spectral synthesis of the 6300 A forbidden line. Results. We provide the first
determination of abundance ratios other than Fe for NGC 752 giants, and ratios
in agreement with the literature for the Hyades, Praesepe and Be 32. We use a
compilation of literature data to study Galactic trends of [Fe/H] and
[alpha/Fe] with Galactocentric radius, age, and height above the Galactic
plane. We find no significant trends, but some indication for a flattening of
[Fe/H] at large Rgc, and for younger ages in the inner disc. We also found a
possible decrease of [Fe/H] with |z| in the outer disc, and a weak increase of
[alpha/Fe] with Rgc.Comment: 21 pages, Accepted for publication in A&A, Updated Table 1
Extracellular High Mobility Group Box 1 Plays a Role in the Effect of Bone Marrow Mononuclear Cell Transplantation for Heart Failure
Transplantation of unfractionated bone marrow mononuclear cells (BMCs) repairs and/or regenerates the damaged myocardium allegedly due to secretion from surviving BMCs (paracrine effect). However, donor cell survival after transplantation is known to be markedly poor. This discrepancy led us to hypothesize that dead donor BMCs might also contribute to the therapeutic benefits from BMC transplantation. High mobility group box 1 (HMGB1) is a nuclear protein that stabilizes nucleosomes, and also acts as a multi-functional cytokine when released from damaged cells. We thus studied the role of extracellular HMGB1 in the effect of BMC transplantation for heart failure. Four weeks after coronary artery ligation in female rats, syngeneic male BMCs (or PBS only as control) were intramyocardially injected with/without anti-HMGB1 antibody or control IgG. One hour after injection, ELISA showed that circulating extracellular HMGB1 levels were elevated after BMC transplantation compared to the PBS injection. Quantitative donor cell survival assessed by PCR for male-specific sry gene at days 3 and 28 was similarly poor. Echocardiography and catheterization showed enhanced cardiac function after BMC transplantation compared to PBS injection at day 28, while this effect was abolished by antibody-neutralization of HMGB1. BMC transplantation reduced post-infarction fibrosis, improved neovascularization, and increased proliferation, while all these effects in repairing the failing myocardium were eliminated by HMGB1-inhibition. Furthermore, BMC transplantation drove the macrophage polarization towards alternatively-activated, anti-inflammatory M2 macrophages in the heart at day 3, while this was abolished by HMGB1-inhibition. Quantitative RT-PCR showed that BMC transplantation upregulated expression of an anti-inflammatory cytokine IL-10 in the heart at day 3 compared to PBS injection. In contrast, neutralizing HMGB1 by antibody-treatment suppressed this anti-inflammatory expression. These data suggest that extracellular HMGB1 contributes to the effect of BMC transplantation to recover the damaged myocardium by favorably modulating innate immunity in heart failure
A Proposal of a Patient-Centred PtDA in Genetic Counselling for Hereditary Deafness
No abstract available
Professional Practice as an Element of Taxonomy - A Case of IT Students at the Polytechnic of Rijeka
There are two reasons for a formal review of the formal forms of education: the development speed of data-communication technologies and the increasing willingness of business entities to apply the same in a very strong competitive battle for dominance at the market. Although not only reason they are a sufficient challenge for educational institutions to adjust their curricula especially when they will help to better prepare their students for the labour market. Professional practice as a form of the highest levels of taxonomies, observed by Bloomâ??s scale, should be used for evaluating student performance, but also for evaluating the quality and marketing of all available programs. This paper presents the experience of professional studies of computer science at Polytechnic of Rijeka acquired through the organization of professional practice in those businesses, which represent a potential place of work after the completion of studies. Conducted research, together with the acquired experience can be a framework for any changes or modifications to curriculum and teaching methods. Respondents pattern for the two main groups: business owners, which basic business is providing IT services and those which use computer to support base of operations. What do respondents who supervise professional practice think about the readiness of graduates for inclusion in their business, which competencies are expected of potential candidates for employment and what are their proposals for changing the program