1,787 research outputs found

    Responsiveness of bovine cumulus-oocyte-complexes (COC) to porcine and recombinant human FSH, and the effect of COC quality on gonadotropin receptor and Cx43 marker gene mRNAs during maturation in vitro

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    Substantially less development to the blastocyst stage occurs in vitro than in vivo and this may be due to deficiencies in oocyte competence. Although a large proportion of bovine oocytes undergo spontaneous nuclear maturation, less is known about requirements for proper cytoplasmic maturation. Commonly, supraphysiological concentrations of FSH and LH are added to maturation media to improve cumulus expansion, fertilization and embryonic development. Therefore, various concentrations of porcine FSH (pFSH) and recombinant human FSH (rhFSH) were investigated for their effect on bovine cumulus expansion in vitro. Expression of FSHr, LHr and Cx43 mRNAs was determined in cumulus-oocyte complexes to determine whether they would be useful markers of oocyte competence. In serum-free media, only 1000 ng/ml pFSH induced marked cumulus expansion, but the effect of 100 ng/ml pFSH was amplified in the presence of 10% serum. In contrast, cumulus expansion occurred with 1 ng/ml rhFSH in the absence of serum. FSHr mRNA was highest at 0–6 h of maturation, then abundance decreased. Similarly, Cx43 mRNA expression was highest from 0–6 h but decreased by 24 h of maturation. However, the relative abundance of LHr mRNA did not change from 6–24 h of maturation. Decreased levels of FSHr, LHr and Cx43 mRNAs were detected in COCs of poorer quality. In conclusion, expansion of bovine cumulus occurred at low doses of rhFSH in serum-free media. In summary, FSHr, LHr and Cx43 mRNA abundance reflects COC quality and FSHr and Cx43 mRNA expression changes during in vitro maturation; these genes may be useful markers of oocyte developmental competence

    Propiedades f?sicas y mec?nicas de la madera de la especie Sangre gallina Vismia baccifera (L) Triana y planch procedente del Bajo Calima, municipio de Buenaventura.

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    72 p. Recurso Electr?nicoLa explotaci?n maderera es una de las principales actividades econ?micas de las comunidades del pacifico colombiano, ?sta implica procesos como la tala indiscriminada y la comercializaci?n de madera en estado juvenil con tendencia al aprovechamiento selectivo, desconociendo el potencial de muchas especies, lo que ocasiona un grave deterioro del bosque. En la presente investigaci?n se estudiaron las propiedades f?sicas y mec?nicas de la especie Vismia baccifera (L.) Triana y Planch, proveniente de la regi?n del Bajo Calima, Buenaventura, con el fin de ampliar el conocimiento acerca de las especies maderables de la zona, lo cual permite plantear soluciones a problem?ticas relacionadas con el manejo forestal. Las propiedades f?sicas determinadas fueron las contracciones (longitudinales, transversales y volum?tricas), la densidad b?sica y en sus diferentes estados (verde, seca al aire y anhidra). Las propiedades mec?nicas evaluadas fueron: compresi?n paralela y perpendicular al grano, flexi?n est?tica, cizallamiento paralelo al grano, dureza, arrancamiento de clavos y tenacidad. La metodolog?a empleada corresponde a una adaptaci?n de las Normas T?cnicas Colombianas ICONTEC para la realizaci?n de ensayos en madera. Con los resultados obtenidos se clasific? la madera de la especie de acuerdo a las normas DIN y ASTM. Se encontr? que la densidad b?sica de la especie es 0,47 g/cm3, es decir que la madera de este ?rbol es blanda. Las propiedades mec?nicas en general se clasificaron como medias y bajas, por lo tanto se recomienda emplear esta especie en construcciones de estructuras livianas. Palabras clave: Propiedades f?sicas, Propiedades mec?nicas, Bajo Calima, Vismia bacciferaLogging is one of the main economic activities of the Colombian Pacific communities. It involves processes such as: indiscriminate logging, and young wood commercialization prone to selective logging. Moreover, logging does not recognize the potential of many species, and it causes serious forest degradation. In this study, the physical and mechanical properties of the species Vismia baccifera (L.) Triana and Planch were assessed. The species mentioned before were from the region of Bajo Calima, Buenaventura. The objective of this study was to increase knowledge about timber species in the Bajo Calima area. It allows to propose solutions for forest management problems. The identified physical properties were contractions such as: (longitudinal, transverse and volumetric). Furthermore, wood basic density in its different phases were (green, open air dried and anhydrous). The mechanical properties evaluated were: parallel and perpendicular grain compression, static flexion, parallel shearing grain, hardness, pulling nails and tenacity. The methodology corresponds to an adaptation of the Colombian Technical Standards ICONTEC for testing wood. The results guided the wood species classification according to DIN and ASTM standards qualified. It was found that the basic density of this species is 0,47 g / cm3. That is to say the wood of this tree is soft. In general, the mechanical properties were classified as medium and low. Therefore, it is recommended to use this wood species in light structures buildings. Keywords: Physical properties, Mechanical properties, Bajo Calima, Vismia baccifer

    Process algebra modelling styles for biomolecular processes

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    We investigate how biomolecular processes are modelled in process algebras, focussing on chemical reactions. We consider various modelling styles and how design decisions made in the definition of the process algebra have an impact on how a modelling style can be applied. Our goal is to highlight the often implicit choices that modellers make in choosing a formalism, and illustrate, through the use of examples, how this can affect expressability as well as the type and complexity of the analysis that can be performed

    Spin and orbital dynamics through the metal-to-insulator transition in Cd2_2Os2_2O7_7 probed with high-resolution RIXS

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    High-resolution resonant inelastic x-ray scattering (RIXS) measurements (Δ\DeltaE = 46 meV) have been performed on Cd2_2Os2_2O7_7 through the metal-to-insulator transition (MIT). A magnetic excitation at 125 meV evolves continuously through the MIT, in agreement with recent Raman scattering results, and provides further confirmation for an all-in, all-out magnetic ground state. Asymmetry of this feature is likely a result of coupling between the electronic and magnetic degrees of freedom. We also observe a broad continuum of interband excitations centered at 0.3 eV energy loss. This is indicative of significant hybridization between Os 5dd and O 2pp states, and concurrent itinerant nature of the system. In turn, this suggests a possible break down of the free-ion model for Cd2_2Os2_2O7_7.Comment: Accepted in Physical Review B (10 pages

    Perspective: Role of Micronutrients and Omega-3 Long-Chain Polyunsaturated Fatty Acids for Immune Outcomes of Relevance to Infections in Older Adults:A Narrative Review and Call for Action

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    The immune system is weakened by advancing age, often referred to as immunosenescence, increasing the vulnerability to, and frequently the severity of, infectious diseases in older people. This has become very apparent in the current coronavirus disease 2019 (COVID-19) pandemic for which older people are at higher risk of severe outcomes, even those who are fully vaccinated. Aging affects both the innate and adaptive immune systems and is characterized by an imbalanced inflammatory response. Increasing evidence shows that optimal status of nutrients such as vitamins C, D, and E and selenium and zinc as well as the omega-3 (n-3) fatty acids DHA and EPA can help compensate for these age-related changes. While inadequate intakes of these nutrients are widespread in the general population, this is often more pronounced in older people. Maintaining adequate intakes is a challenge for them due to a range of factors such as physical, physiological, and cognitive changes; altered absorption; and the presence of noncommunicable diseases. While nutritional requirements are ideally covered by a balanced diet, this can be difficult to achieve, particularly for older people. Fortified foods and nutritional complements are effective in achieving adequate micronutrient intakes and should be considered as a safe and cost-effective means for older people to improve their nutritional status and hence support their defense against infections. Complementing the diet with a combination of micronutrients, particularly those playing a key role in the immune system such as vitamins C, D, and E and selenium and zinc as well as DHA and EPA, is recommended for older people. Optimal nutrition to support the immune system in older people will remain essential, particularly in the face of the current COVID-19 pandemic and, thus, developing strategies to ensure adequate nutrition for the growing number of older adults will be an important and cost-effective investment in the future

    Strongly Gapped Spin-Wave Excitation in the Insulating Phase of NaOsO3

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    NaOsO3 hosts a rare manifestation of a metal-insulator transition driven by magnetic correlations, placing the magnetic exchange interactions in a central role. We use resonant inelastic x-ray scattering to directly probe these magnetic exchange interactions. A dispersive and strongly gapped (58 meV) excitation is observed indicating appreciable spin-orbit coupling in this 5d3 system. The excitation is well described within a minimal model Hamiltonian with strong anisotropy and Heisenberg exchange (J1=J2=13.9 meV). The observed behavior places NaOsO3 on the boundary between localized and itinerant magnetism
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