750 research outputs found
The evolution of Lithium: Implications of a universal Spite plateau
The cosmological 7Li problem consists in explaining why the primordial Li abundance, as predicted by the standard Big Bang nucleosynthesis theory with constraints from WMAP and Planck, is a factor of 3 larger than the Li abundance measured in the stars of the Spite plateau defined by old, warm dwarf stars of the Milky Way halo. Several explanations have been proposed to explain this difference, including various Li depletion processes as well as non-standard Big Bang nucleosynthesis, but the main question remains unanswered. In this paper, we present detailed chemical evolution models for dwarf spheroidal and ultra faint galaxies, compute the galactic evolution of 7Li abundance in these objects, and compare it with observations of similar objects. In our models, Li is mainly produced by novae and cosmic rays, and to a minor extent, by low and intermediate mass stars. We adopt the yield combination that best fits the Li abundances in the Milky Way stars. It is evident that the observations of dwarf objects define a Spite plateau, identical to that observed in the Milky Way, thus suggesting that the Spite plateau could be a universal feature and its meaning should be discussed. The predictions of our models for dwarf galaxies are obtained by assuming as Li primordial abundance either the one detected in the atmospheres of the oldest halo stars (Spite plateau; A(Li) ~ 2.2 dex), or the one from cosmological observations (WMAP; A(Li) ~ 2.66 dex). Finally, we discuss the implications of the universality of the Spite plateau results
Coeducational ideas In physical education teachers: Pshycometric properties of a scale
Ante la falta de cuestionarios o escalas que evaluaran los diferentes aspectos coeducativos que caracterizan al profesorado de Educación FÃsica y la necesidad de conocer cuál es la concepción que tienen sobre este modelo, se desprende el objetivo de este trabajo, como el de evaluar las propiedades psicométricas mediante un instrumento que hemos denominado Escala sobre el pensamiento coeducativo del profesorado de EF para valorar las opiniones respecto a la coeducación y la metodologÃa que se utiliza en sus clases. La muestra estuvo compuesta por 213 profesores, 133 hombres y 43 mujeres. La escala fue aplicada mediante papel, envÃo de correo electrónico y plataforma moddle. El análisis de los datos muestra unos resultados adecuados en cuanto
a estructura factorial, consistencia interna y tipos de validez. Se concluye que esta Escala representa un instrumento válido y fiable para analizar las caracterÃsticas coeducativas del profesoradoBecause of the absence of questionnaires or scales which will assess different coeducative aspects that are characteristics of PE teacher and need to know which is the conception that they have about this model, it is deduced the aim of this work as that which evaluate the psychometric properties through a tool called the Scale of coeducational ideas in physical education teachers to value the opinions about coeducation and the methodology used in their classes. The sample was composed by 213 teachers, 133 men and 43 women. The questionnaire was applied by means of paper, electronic mail shipment and platform moddle. The data analysis shows appropriate results in terms of factor structure, internal consistency and validity types. We conclude that the escale represents a valid and reliable instrument to analyze the coeducative characteristics of the teacher
Validation positive behaviors questionnaire in educative dance
El objetivo de la presente investigación era adaptar y validar al contexto de la danza educativa, el Cuestionario de Comportamientos Positivos en Educación FÃsica. La muestra estuvo formada por 921 alumnos, de sexo femenino (n = 421) y masculino (n = 500), con edades comprendidas entre los 11 y los 17 años, pertenecientes a cuatro escuelas en México. Esta investigación estaba organizada por ConArte (Consorcio Internacional de Arte y Escuela). Los resultados obtenidos mostraron que el instrumento presentaba una adecuada validez factorial y consistencia interna. Asimismo, el instrumento se mostró invariante en cuanto al género y la edad de los participantes. De esta manera, este trabajo aporta evidencias cientÃficas de que el cuestionario de comportamientos positivos en la danza educativa se muestra válido y fiable para analizar dichos comportamientos durante este tipo de clasesThe aim of the current research was to validate into the educative dance in Mexican secondary school, the questionnaire of positive behaviors in physical education. The sample was formed by 921 students, both female (n = 421) and male (n = 500) participants, ranging in age from 11 to 17 years old, belonged to four schools from Mexico. This research was organized by ConArte (International Consortium of Art and School). The results showed that the instrument had an adequate factorial validity and internal consistency. Furthermore, the instrument was invariant regarding individuals´ gender and age. Thus, this work gives empiric evidences that the questionnaire of positive behaviors in educative dance is valid and reliable to assess these behavior
The aggregation of cytochrome C may be linked to its flexibility during refolding
Large-scale expression of biopharmaceutical proteins in cellular hosts results in production of large insoluble mass aggregates. In order to generate functional product, these aggregates require further processing through refolding with denaturant, a process in itself that can result in aggregation. Using a model folding protein, cytochrome C, we show how an increase in final denaturant concentration decreases the propensity of the protein to aggregate during refolding. Using polarised fluorescence anisotropy, we show how reduced levels of aggregation can be achieved by increasing the period of time the protein remains flexible during refolding, mediated through dilution ratios. This highlights the relationship between the flexibility of a protein and its propensity to aggregate. We attribute this behaviour to the preferential urea-residue interaction, over self-association between molecules
Long-term monitoring of the radio-galaxy M87 in gamma-rays: joint analysis of MAGIC, VERITAS and Fermi-LAT data
M87 was discovered in the very-high-energy band (VHE, E > 100 GeV) with HEGRA
in 2003, long before its emission was detected in the high-energy band (HE, E >
100 MeV) with Fermi-LAT in 2009, opening the window to a new family of
extragalactic sources with tilted jets. After a series of major VHE flares in
2005, 2008, and 2010, which were detected in multiple bands, the source has
been found in a low activity state, interrupted only by comparatively
smaller-scale flares. MAGIC and VERITAS, two stereoscopic Cherenkov telescope
arrays located at Roque de los Muchachos Observatory (Canary Islands, Spain)
and the Fred Lawrence Whipple Observatory (Arizona, US), have monitored M87
continuously and in coordination for more than 10 years. In this work, we
present the data for 4 years of MAGIC and VERITAS observations corresponding to
2019, 2020, 2021 and 2022. The resulting light curves are shown in daily and
monthly scales where no significant variability is observed. In addition, we
show the first joint analysis using combined event data from the two VHE
instruments and Fermi-LAT to compute the spectral energy distribution
Expanding the Applicability of Poly(Ionic Liquids) in Solid Phase Microextraction: Pyrrolidinium Coatings
Crosslinked pyrrolidinium-based poly(ionic liquids) (Pyrr-PILs) were synthesized through a fast, simple, and solventless photopolymerization scheme, and tested as solid phase microextraction (SPME) sorbents. A series of Pyrr-PILs bearing three different alkyl side chain lengths with two, eight, and fourteen carbons was prepared, characterized, and homogeneously coated on a steel wire by using a very simple procedure. The resulting coatings showed a high thermal stability, with decomposition temperatures above 350 degrees C, excellent film stability, and lifetime of over 100 injections. The performance of these PIL-based SPME fibers was evaluated using a mixture of eleven organic compounds with different molar volumes and chemical functionalities (alcohols, ketones, and monoterpenes). The Pyrr-PIL fibers were obtained as dense film coatings, with 67 mu m thickness, with an overall sorption increase of 90% and 55% as compared to commercial fibers of Polyacrylate (85 mu m) (PA85) and Polydimethylsiloxane (7 mu m) (PDMS7) coatings, respectively. A urine sample doped with the sample mixture was used to study the matrix effect and establish relative recoveries, which ranged from 60.2% to 104.1%.David J. S. Patinha, and Liliana C. Tome are grateful to FCT (Fundacao para a Ciencia e a Tecnologia) for the PhD research grant SFRH/BD/97042/2013 and the Post-Doctoral research grant (SFRH/BPD/101793/2014), respectively. David J. S. Patinha also thanks the financial support from COST-Exil Project 1206. The NMR data was acquired at CERMAX (Centro de Ressonncia Magnetica Antnio Xavier) which is a member of the National NMR network. This work was partially supported by FCT through Research Unit GREEN-it " Bioresources for Sustainability" (UID/Multi/04551/2013) and the Associate Laboratory CICECO Aveiro Institute of materials (UID/CTM/50011/2013)
Prioritization of mycotoxins for risk management action based on both public health risk and mitigation efficacy
There is a large and progressively growing number of mycotoxins with new potential concerns and implications on consumer protection. The classical approach to risk management is to deal with each emerging hazard individually, leading to both overload and lack of coherence in terms of an overall riskbased approach. The development of mitigation strategies should prioritize mycotoxins that regularly
occur at undesirable levels in commonly consumed commodities, wherein both the toxicological profiles and effectiveness of mitigation are understood with a reasonable degree of certainty. The ultimate goal of mycotoxin mitigation is to prevent adverse health effects caused by foodborne exposure to mycotoxins, while preserving nutritional and organoleptic quality of food. The International Life Sciences Institute Europe (ILSI Europe) Food Contaminants Task Force is firmly committed to contributing to the understanding of the issues of mycotoxins affecting the different points of the food chain.
This presentation will illustrate a recent new activity that is devoted to establishing a framework for the prioritization of mycotoxins found in food following a risk-based approach (decision tree). Based on the evidence and scale of risk to consumers, and the potential for risk mitigation, the framework will enable the differentiation between mycotoxins where risk management action is both warranted and likely to be effective based on available evidence. Through case-studies, this framework will also highlight potential knowledge gaps. The proposed activity is therefore devoted to delineating the right path for scaling and
prioritizing mycotoxins in terms of risk-ranking and consequent mitigation opportunities.info:eu-repo/semantics/publishedVersio
Truncated and Helix-Constrained Peptides with High Affinity and Specificity for the cFos Coiled-Coil of AP-1
Protein-based therapeutics feature large interacting surfaces. Protein folding endows structural stability to localised surface epitopes, imparting high affinity and target specificity upon interactions with binding partners. However, short synthetic peptides with sequences corresponding to such protein epitopes are unstructured in water and promiscuously bind to proteins with low affinity and specificity. Here we combine structural stability and target specificity of proteins, with low cost and rapid synthesis of small molecules, towards meeting the significant challenge of binding coiled coil proteins in transcriptional regulation. By iteratively truncating a Jun-based peptide from 37 to 22 residues, strategically incorporating i-->i+4 helix-inducing constraints, and positioning unnatural amino acids, we have produced short, water-stable, alpha-helical peptides that bind cFos. A three-dimensional NMR-derived structure for one peptide (24) confirmed a highly stable alpha-helix which was resistant to proteolytic degradation in serum. These short structured peptides are entropically pre-organized for binding with high affinity and specificity to cFos, a key component of the oncogenic transcriptional regulator Activator Protein-1 (AP-1). They competitively antagonized the cJun–cFos coiled-coil interaction. Truncating a Jun-based peptide from 37 to 22 residues decreased the binding enthalpy for cJun by ~9 kcal/mol, but this was compensated by increased conformational entropy (TDS ≤ 7.5 kcal/mol). This study demonstrates that rational design of short peptides constrained by alpha-helical cyclic pentapeptide modules is able to retain parental high helicity, as well as high affinity and specificity for cFos. These are important steps towards small antagonists of the cJun-cFos interaction that mediates gene transcription in cancer and inflammatory diseases
Gene-based mapping of trehalose biosynthetic pathway genes reveals association with source- and sink-related yield traits in a spring wheat panel
Trehalose 6-phosphate (T6P) signalling regulates carbon use and allocation and is a target to improve crop yields. However, the specific contributions of trehalose phosphate synthase (TPS) and trehalose phosphate phosphatase (TPP) genes to source- and sink-related traits remain largely unknown. We used enrichment-capture sequencing on TPS and TPP genes to estimate and partition the genetic variation of yield-related traits in a spring wheat (Triticum aestivum) breeding panel specifically built to capture the diversity across the 75,000 CIMMYT wheat cultivar collection. Twelve phenotypes were correlated to variation in TPS and TPP genes including plant height and biomass (source), spikelets per spike, spike growth, and grain filling traits (sink) which showed indications of both positive and negative gene selection. Individual genes explained proportions of heritability for biomass and grain-related traits. Three TPS1 homeologues were particularly significant for trait variation. Epistatic interactions were found within and between the TPS and TPP gene families for both plant height and grain-related traits. Gene-based prediction improved predictive ability for grain weight when gene effects were combined with the whole-genome markers. Our study has generated a wealth of information on natural variation of TPS and TPP genes related to yield potential which confirms the role for T6P in resource allocation and in affecting traits such as grain number and size confirming other studies which now opens up the possibility of harnessing natural genetic variation more widely to better understand the contribution of native genes to yield traits for incorporation into breeding programmes
Oleanolic acid reduces hyperglycemia beyond treatment period with Akt/FoxO1-induced suppression of hepatic gluconeogenesis in type 2 diabetic mice
The present study investigated the chronic efficacy of oleanolic acid (OA), a triterpenoid selected from our recent screening, on hyperglycemia in type-2 diabetic mice. C57BL/6J mice were fed a high-fat diet followed by low doses of streptozotocin to generate a type-2 diabetic model. OA (100 mg/kg/day) was administered orally for 2 weeks with its effects monitored for 6 weeks. High-fat feeding and streptozotocin generated a steady hyperglycemia (21.261.1 mM) but OA administration reversed the hyperglycemia by ,60%
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