709 research outputs found
Differences in trajectories and predictive factors of cognition over time in a sample of cognitively healthy adults, in zaragoza, spain
Great inter-individual variability has been reported in the maintenance of cognitive function in aging. We examined this heterogeneity by modeling cognitive trajectories in a population-based longitudinal study of adults aged 55+ years. We hypothesized that (1) distinct classes of cognitive trajectories would be found, and (2) between-class differences in associated factors would be ob-served. The sample comprised 2403 cognitively healthy individuals from the Zaragoza Dementia and Depression (ZARADEMP) project, who had at least three measurements of the Mini-Mental State Examination (MMSE) in a 12-year follow-up. Longitudinal changes in cognitive functioning were modeled using growth mixture models (GMM) in the data. The best-fitting age-adjusted model showed 3 distinct trajectories, with 1-high-to-moderate (21.2% of participants), 2-moderate-stable (67.5%) and, 3-low-and-declining (9.9%) cognitive function over time, respectively. Compared with the reference 2-trajectory, the association of education and depression was significantly different in trajectories 1 and 3. Instrumental activities of daily living (iADLs) were only associated with the declining trajectory. This suggests that intervention strategies should be tailored specifically to individuals with different trajectories of cognitive aging, and intervention strategies designed to maintain cognitive function might be different from those to prevent decline. A stable cognitive performance (‘successful cognitive aging’) rather than a mild decline, might be more ‘normal’ than generally expected
Arsenic speciation in beverages by direct injection-ion chromatography hydride generation atomic fluorescence spectrometry
The procedure developed allows the direct speciation of arsenic in these samples with good sensitivity, selectivity, precision and accuracy. Detection limits determined using the optimized conditions were found to be between 0.16 and 2.9ng ml−1 for arsenite, dimethylarsinic acid, monomethylarsonic acid and arsenate, while standard addition studies showed that the procedure is free from matrix interferences. As no certified reference materials are available for these analytes or matrices, validation was carried out by studying spike recoveries and by comparison of results with an alternative technique
Anisotropic intrinsic spin relaxation in graphene due to flexural distortions
We propose an intrinsic spin scattering mechanism in graphene originated by
the interplay of atomic spin-orbit interaction and the local curvature induced
by flexural distortions of the atomic lattice. Starting from a multiorbital
tight-binding Hamiltonian with spin-orbit coupling considered
non-perturbatively, we derive an effective Hamiltonian for the spin scattering
of the Dirac electrons due to flexural distortions. We compute the spin
lifetime due to both flexural phonons and ripples and we find values in the
microsecond range at room temperature. Interestingly, this mechanism is
anisotropic on two counts. First, the relaxation rate is different for
off-plane and in-plane spin quantization axis. Second, the spin relaxation rate
depends on the angle formed by the crystal momentum with the carbon-carbon
bond. In addition, the spin lifetime is also valley dependent. The proposed
mechanism sets an upper limit for spin lifetimes in graphene and will be
relevant when samples of high quality can be fabricated free of extrinsic
sources of spin relaxation.Comment: extended version with 7 pages, 4 figures and several new results; a
numerical error has been corrected leading to longer spin lifetimes than in
the previous versio
A model of Mira's cometary head/tail entering the Local Bubble
We model the cometary structure around Mira as the interaction of an AGB wind
from Mira A, and a streaming environment. Our simulations introduce the
following new element: we assume that after 200 kyr of evolution in a dense
environment Mira entered the Local Bubble (low density coronal gas). As Mira
enters the bubble, the head of the comet expands quite rapidly, while the tail
remains well collimated for a 100 kyr timescale. The result is a
broad-head/narrow-tail structure that resembles the observed morphology of
Mira's comet. The simulations were carried out with our new adaptive grid code
WALICXE, which is described in detail.Comment: 12 pages, 8 figures (4 in color). Accepted for publication in The
Astrophysical Journa
A second look at N=1 supersymmetric AdS_4 vacua of type IIA supergravity
We show that a class of type IIA vacua recently found within the N=4
effective approach corresponds to compactification on Ads_4 \times S^3 \times
S^3/Z_2^3. The results obtained using the effective method completely match the
general ten-dimensional analysis for the existence of N=1 warped
compactifications on Ads_4 \times M_6. In particular, we verify that the
internal metric is nearly-Kahler and that for specific values of the parameters
the Bianchi identity of the RR 2-form is fulfilled without sources. For another
range of parameters, including the massless case, the Bianchi identity is
satisfied when D6-branes are introduced. Solving the tadpole cancellation
conditions in D=4 we are able to find examples of appropriate sets of branes.
In the second part of this paper we describe how an example with internal space
CP^3 but with non nearly-Kahler metric fits into the general analysis of flux
vacua.Comment: Latex file, 35 pages, no figures. Reference added, minor corrections
adde
Effects of fiber inclusion on growth performance and nutrient digestibility of piglets reared under optimal or poor hygienic conditions
Two experiments were conducted to estimate the standardized ileal digestible (SID) Trp:Lys ratio requirement for growth performance of nursery pigs. Experimental diets were formulated to ensure that lysine was the second limiting AA throughout the experiments. In Exp. 1 (6 to 10 kg BW), 255 nursery pigs (PIC 327 × 1050, initially 6.3 ± 0.15 kg, mean ± SD) arranged in pens of 6 or 7 pigs were blocked by pen weight and assigned to experimental diets (7 pens/diet) consisting of SID Trp:Lys ratios of 14.7%, 16.5%, 18.4%, 20.3%, 22.1%, and 24.0% for 14 d with 1.30% SID Lys. In Exp. 2 (11 to 20 kg BW), 1,088 pigs (PIC 337 × 1050, initially 11.2 kg ± 1.35 BW, mean ± SD) arranged in pens of 24 to 27 pigs were blocked by average pig weight and assigned to experimental diets (6 pens/diet) consisting of SID Trp:Lys ratios of 14.5%, 16.5%, 18.0%, 19.5%, 21.0%, 22.5%, and 24.5% for 21 d with 30% dried distillers grains with solubles and 0.97% SID Lys. Each experiment was analyzed using general linear mixed models with heterogeneous residual variances. Competing heteroskedastic models included broken-line linear (BLL), broken-line quadratic (BLQ), and quadratic polynomial (QP). For each response, the best-fitting model was selected using Bayesian information criterion. In Exp. 1 (6 to 10 kg BW), increasing SID Trp:Lys ratio linearly increased (P 24.0%]) SID Trp:Lys ratio. For G:F, the best-fitting model was a BLL in which the maximum G:F was estimated at 20.4% (95% CI: [14.3%, 26.5%]) SID Trp:Lys. In Exp. 2 (11 to 20 kg BW), increasing SID Trp:Lys ratio increased (P < 0.05) ADG and G:F in a quadratic manner. For ADG, the best-fitting model was a QP in which the maximum ADG was estimated at 21.2% (95% CI: [20.5%, 21.9%]) SID Trp:Lys. For G:F, BLL and BLQ models had comparable fit and estimated SID Trp:Lys requirements at 16.6% (95% CI: [16.0%, 17.3%]) and 17.1% (95% CI: [16.6%, 17.7%]), respectively. In conclusion, the estimated SID Trp:Lys requirement in Exp. 1 ranged from 20.4% for maximum G:F to 23.9% for maximum ADG, whereas in Exp. 2 it ranged from 16.6% for maximum G:F to 21.2% for maximum ADG. These results suggest that standard NRC (2012) recommendations may underestimate the SID Trp:Lys requirement for nursery pigs from 11 to 20 kg BW
Chemical characteristics of soybean meals available in the European Union market: A 2015 survey
The aim of this research was to determine the chemical composition and nutritive value of soybean meals (SBM) from beans of different origins collected in the European Union in 2015 . Based on a previous survey conducted from 2008 to 2014, we hypothesized that the SBM from the different countries could show differences in chemical composition,
protein quality, and nutritional value. In total, 40 SBM samples from USA (n = 14), Brazil (BRA; n = 15), and Argentina (ARG; n = 11) were collected at random from 5 key feed compounders and analyzed for proximal components, minerals, sugars, fibers, amino acids (AA),
and protein quality
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