35 research outputs found
Energy balance methodology and modeling of supplementary forage production for cattle in Brazil
Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy
We review HB stars in a broad astrophysical context, including both variable
and non-variable stars. A reassessment of the Oosterhoff dichotomy is
presented, which provides unprecedented detail regarding its origin and
systematics. We show that the Oosterhoff dichotomy and the distribution of
globular clusters (GCs) in the HB morphology-metallicity plane both exclude,
with high statistical significance, the possibility that the Galactic halo may
have formed from the accretion of dwarf galaxies resembling present-day Milky
Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the
second-parameter problem is presented. A technique is proposed to estimate the
HB types of extragalactic GCs on the basis of integrated far-UV photometry. The
relationship between the absolute V magnitude of the HB at the RR Lyrae level
and metallicity, as obtained on the basis of trigonometric parallax
measurements for the star RR Lyrae, is also revisited, giving a distance
modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are
studied. Finally, the conductive opacities used in evolutionary calculations of
low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and
Space Scienc
Plantas medicinais de um remascente de Floresta OmbrĂłfila Mista Altomontana, Urupema, Santa Catarina, Brasil
Magnetohydrodynamic Oscillations in the Solar Corona and Earthâs Magnetosphere: Towards Consolidated Understanding
The reactions of dinitrogen tetroxide with lithium carbonate with a series of magnesium compounds, and with aluminium chloride
An isodicentric X chromosome with short arm fusion in a woman without somatic features of Turner's syndrome.
Negative effect of vitamin D on kidney function: a Mendelian randomization study.
The kidney plays a central role in the regulation of vitamin D metabolism. It is not clear, however, whether vitamin D influences kidney function. Previous studies have reported conflicting results, which may have been influenced by reverse causation and residual confounding. We conducted a Mendelian randomization (MR) study to obtain unconfounded estimates of the association between genetically instrumented vitamin D metabolites and estimated glomerular filtration rate (eGFR) as well as the urinary albumin:creatinine ratio (UACR).
We performed a two-sample MR study based on three single nucleotide variants associated with 25(OH)D levels: rs2282679, rs10741657 and rs12785878, related to the genes GC, CYP2R1 and DHCR7, respectively. Estimates of the allele-dependent effects on serum 25(OH)D and eGFR/UACR were obtained from summary statistics of published genome-wide association meta-analyses. Additionally, we performed a one-sample MR analysis for both 25(OH)D and 1,25(OH)2âD using individual-level data from six cohorts.
The combined MR estimate supported a negative causal effect of log transformed 25(OH)D on log transformed eGFR (ÎČâ= -0.013, Pâ=â0.003). The analysis of individual-level data confirmed the main findings and also revealed a significant association of 1,25(OH)2âD on eGFR (ÎČâ=â-0.094, Pâ=â0.008). These results show that a 10% increase in serum 25(OH)D levels causes a 0.3% decrease in eGFR. There was no effect of 25(OH)D on UACR (ÎČ = 0.032, Pâ=â0.265).
Our study suggests that circulating vitamin D metabolite levels are negatively associated with eGFR. Further studies are needed to elucidate the underlying mechanisms