7,168 research outputs found
A comparison study on criteria to select the most adequate weighting matrix
The practice of spatial econometrics revolves around a weighting matrix, which is often supplied by the user on previous knowledge. This is the so-called W issue. Probably, the aprioristic approach is not the best solution although, presently, there are few alternatives for the user. Our contribution focuses on the problem of selecting aWmatrix from among a finite set of matrices, all of them considered appropriate for the case. We develop a new and simple method based on the entropy corresponding to the distribution of probability estimated for the data. Other alternatives, which are common in current applied work, are also reviewed. The paper includes a large study of Monte Carlo to calibrate the effectiveness of our approach compared to others. A well-known case study is also included
Design and in Vitro Evaluation of a New Nano-Microparticulate System for Enhanced Aqueous-Phase Solubility of Curcumin
Curcumin, a yellow polyphenol derived from the turmeric Curcuma longa, has been associated with a diverse therapeutic potential including anti-inflammatory, antioxidant, antiviral, and anticancer properties. However, the poor aqueous solubility and low bioavailability of curcumin have limited its potential when administrated orally. In this study, curcumin was encapsulated in a series of novel nano-microparticulate systems developed to improve its aqueous solubility and stability. The nano-microparticulate systems are based entirely on biocompatible, biodegradable, and edible polymers including chitosan, alginate, and carrageenan. The particles were synthesized via ionotropic gelation. Encapsulating the curcumin into the hydrogel nanoparticles yielded a homogenous curcumin dispersion in aqueous solution compared to the free form of curcumin. Also, the in vitro release profile showed up to 95% release of curcumin from the developed nano-microparticulate systems after 9 hours in PBS at pH 7.4 when freeze-dried particles were used.CONACYTCUPIAPharmac
The importance of nonâdiffusional factors in determining photosynthesis of two contrasting quinoa ecotypes (Chenopodium quinoa willd.) subjected to salinity conditions
The broad distribution of quinoa in saline and nonâsaline environments is reflected in variations in the photosynthesisâassociated mechanisms of different ecotypes. The aim of this study was to characterize the photosynthetic response to high salinity (0.4 M NaCl) of two contrasting Chilean genotypes, Amarilla (saltâtolerant, salares ecotype) and Hueque (saltâsensitive, coastal ecotype). Our results show that saline stress induced a significant decrease in the K+/Na+ ratio in roots and an increase in glycine betaine in leaves, particularly in the sensitive genotype (Hueque). Measurement of the photosynthesisârelated parameters showed that maximum CO2 assimilation (Amax) in control plants was comparable between genotypes (ca. 9â10 ÎŒmol CO2 mâ2 sâ1). However, salt treatment produced different responses, with Amax values decreasing by 65.1% in the sensitive ecotype and 37.7% in the tolerant one. Although both genotypes maintained mesophyll conductance when stomatal restrictions were removed, the biochemical components of Amarilla were impaired to a lesser extent under salt stress conditions: for example, the maximum rate of ribuloseâ1,5â bisphosphate carboxylase/oxygenase (RubisCO; Vcmax) was not as affected in Amarilla, revealing that this enzyme has a higher affinity for its substrate in this genotype and, thus, a better carboxylation efficiency. The present results show that the higher salinity tolerance of Amarilla was also due to its ability to control nonâdiffusional components, indicating its superior photosynthetic capacity compared to Hueque, particularly under salt stress conditions
Functional role of PGAM5 multimeric assemblies and their polymerization into filaments.
PGAM5 is a mitochondrial protein phosphatase whose genetic ablation in mice results in mitochondria-related disorders, including neurodegeneration. Functions of PGAM5 include regulation of mitophagy, cell death, metabolism and aging. However, mechanisms regulating PGAM5 activation and signaling are poorly understood. Using electron cryo-microscopy, we show that PGAM5 forms dodecamers in solution. We also present a crystal structure of PGAM5 that reveals the determinants of dodecamer formation. Furthermore, we observe PGAM5 dodecamer assembly into filaments both in vitro and in cells. We find that PGAM5 oligomerization into a dodecamer is not only essential for catalytic activation, but this form also plays a structural role on mitochondrial membranes, which is independent of phosphatase activity. Together, these findings suggest that modulation of the oligomerization of PGAM5 may be a regulatory switch of potential therapeutic interest
Short communication: Performance, intestinal permeability, and metabolic profile of calves fed a milk replacer supplemented with glutamic acid
The objective of this study was to evaluate the potential benefits of supplementing glutamic acid in milk replacers (MR) with respect to calf performance, intestinal permeability, and metabolism. Sixty Holstein male calves (3 ± 1.3 d old and 45 ± 5.9 kg body weight) were individually housed and fed a control MR without AA supplementation (24.8% crude protein and 19.1% fat, dry matter basis), or MR supplemented with 0.3% glutamic acid (25.1% crude protein and 20.3% fat, dry matter basis). Animals followed the same MR feeding program and were weaned at 56 d of the study. The amount of starter concentrate offered was restricted to limit the effect of concentrate intake on calf metabolism. Individual daily consumption and weekly body weight were measured, and 4 h after the morning feeding, blood samples were obtained at 14 and 35 d to determine general biochemical parameters and plasma AA concentrations. On d 10 of the study, we conducted an intestinal permeability test by including 21 g of lactulose and 4.2 g of d-mannitol as markers in the MR. We found no differences in calf performance or in intestinal permeability (measured as lactulose:mannitol ratio). Serum glucose concentration was greater in unsupplemented calves than in Glu-supplemented calves. At 14 d, the proportion of plasma Leu was greater in Glu-supplemented calves; the proportion of Ile tended to be greater in Glu-supplemented calves; and the proportion of Met tended to be greater in unsupplemented calves. We observed no other differences. Small changes occurred in AA metabolism when supplementing calf MR with 0.3% glutamic acid, without leading to improvements in calf performance or changes in intestinal permeability.info:eu-repo/semantics/publishedVersio
Suitability of a three-dimensional model to measure empathy and its relationship with social and normative adjustment in Spanish adolescents: a cross-sectional study
Objectives:
(1) To examine the psychometric properties of the Basic Empathy Scale (BES) with Spanish adolescents, comparing a two and a three-dimensional structure;(2) To analyse the relationship between the three-dimensional empathy and social and normative adjustment in school.
Design:
Transversal and ex post facto retrospective study. Confirmatory factorial analysis, multifactorial invariance analysis and structural equations models were used.
Participants:
747 students (51.3% girls) from Cordoba, Spain, aged 12â17 years (M=13.8; SD=1.21).
Results:
The original two-dimensional structure was confirmed (cognitive empathy, affective empathy), but a three-dimensional structure showed better psychometric properties, highlighting the good fit found in confirmatory factorial analysis and adequate internal consistent valued, measured with Cronbachâs alpha and McDonaldâs omega. Composite reliability and average variance extracted showed better indices for a three-factor model. The research also showed evidence of measurement invariance across gender. All the factors of the final three-dimensional BES model were direct and significantly associated with social and normative adjustment, being most strongly related to cognitive empathy.
Conclusions:
This research supports the advances in neuroscience, developmental psychology and psychopathology through a three-dimensional version of the BES, which represents an improvement in the original two-factorial model. The organisation of empathy in three factors benefits the understanding of social and normative adjustment in adolescents, in which emotional disengagement favours adjusted peer relationships. Psychoeducational interventions aimed at improving the quality of social life in schools should target these components of empathy
Salmonella enterica serovars Typhimurium and Enteritidis causing mixed infections in febrile children in Mozambique
Background and purpose: Invasive nontyphoidal salmonellosis,
mostly caused by serovars Typhimurium and Enteritidis of
Salmonella enterica, has emerged as a major public health
problem in sub-Saharan Africa. The aim of this study was the
clinical and microbiological characterization of nontyphoidal
salmonellosis episodes affecting febrile children in Mozambique.
Patients and methods: The clinical records of the patients were
evaluated, and S. enterica isolates were characterized with
regard to serovar, phage type, antimicrobial resistance
(phenotype/responsible genes), plasmid content, pulsed-field gel
electrophoresis, and multilocus sequence typing. Results:
Fifteen S. Typhimurium and 21 S. Enteritidis isolates were
recovered from blood samples of 25 children, the majority with
underlying risk factors. With regard to phage typing, most
isolates were either untypeable or reacted but did not conform,
revealing that a number of previously unrecognized patterns are
circulating in Mozambique. Most isolates were
multidrug-resistant, with nearly all of the responsible genes
located on derivatives of serovar-specific virulence plasmids.
ST313 and ST11 were the predominant sequence types associated
with S. Typhimurium and S. Enteritidis, respectively, and the
uncommon ST1479 was also detected in S. Enteritidis. A distinct
XbaI fragment of ~350 kb was associated with pulsed-field gel
electrophoresis patterns of multidrug-resistant isolates of S.
Enteritidis. Nearly half of the children were coinfected with
both serovars, a fact expected to aggravate the disease and
hamper the treatment. However, particularly poor outcomes were
not observed for the coinfected patients. Conclusion: Mixed
Salmonella infections could frequently occur in febrile children
in Mozambique. Additional studies are required to determine
their actual impact and consequences, not only in this country,
but also in other African countries
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