2,801 research outputs found
The Pseudotransannular Ring Opening of 1-Aminocyclohept-4-ene-derived Epoxides in the Synthesis of Tropane Alkaloids: Total Synthesis of (±)-Ferrugine
We have optimized a synthetic approach to (±)-Ferrugine in 8 steps starting from 5-aminocyclohept-1-ene and using the Brønsted acid-catalyzed pseudotransannular ring-opening of the epoxide derived from this cycloheptene as the key step for the construction of the 8-azabicyclo[3.2.1]octane central core. While attempting the enantioselective synthesis of this natural product from enantiopure 2-hydroxy-8-azabicyclo[3.2.1]octane we have found that this compound shows a pronounced tendency to racemize via an achiral symmetric aziridinium intermediate. This racemization side process has been studied in detail using both experimental and computational methods
El impacto ambiental del desarrollo del turismo en las islas del archipiélago Jardines del Rey, Cuba
The quick process of tourist development undertaken in the Archipiélago Jardines del Rey, in the Republic of Cuba, represents a potential factor of environmental interference for the smalls islands that integrate this insular system; these geosystemes are characterized by their notables natural values, high degree of natural conservation, important geoecologys functions and particular natural fragility what makes them spcecially vulnerable before the human impacts. Presenly work, the islands of this archipielago are characterized and is carried out the analysis of the impact waited by the tourist development in the same ones, like a contribution to the clarification of the problem environmental perspective and to alert about the necessity of working in the prevention and evaluation of these aspects, it stops by means of the environmental planning to guarantee the protection of the islands.El acelerado proceso de desarrollo turístico empremdido en el archipiélago Jardines del Rey, en la RepUblica de Cuba, representa un potencial factor de perturbación ambiental para las pequeñas islas que integran este sistema insular. Estos geosistemas se caracterizan por sus notables valores naturales, alto grado de conservación natural, importantes funciones geoecológicas y particular fragilidad natural; lo que los hace especialmente vulnerables ante los impactos humanos. En el presente trabajo, se caracterizan las islas de este archipiélago y se realiza el análisis del impacto esperado por el desarrollo turístico en las mismas, como una contribución al esclarecimiento de la problemática ambiental futura y para alertar sobre la necesidad de trabajar en la prevención y evaluación de estos problemas, por medio de la planificación ambiental para garantizar así la protección de las islas
Estilo de vida y estado de nutrición en niños escolares
ResumenObjetivoRelacionar el estilo de vida y el estado de nutrición en escolares.MétodoEstudio correlacional, participaron 260 niños adscritos a la Clínica ISSSTE, elegidos aleatoriamente. Se utilizó el cuestionario sobre estilos de vida en la niñez y se valoró el peso y talla. Se obtuvo la aprobación de la Jefatura de Investigación del ISSSTE. En el análisis de datos se aplicó estadística descriptiva e inferencial.ResultadosParticiparon 137 niños y 123 niñas, con edades entre 6-12 años. Respecto al estado de nutrición, 5 de cada 10 de los participantes se encuentran en peso normal, 2 de cada 10 en sobrepeso y uno de cada 10 en obesidad y peso bajo. Sobre el estilo de vida 7 de cada 10 de los participantes se encontraron en riesgo bajo y 2 de cada 10 en riesgo mediano. Por otra parte, no se encontró relación entre el estilo de vida de los niños y su estado de nutrición (rs=0.038, p>0.05). Adicionalmente, se encontró que los niños con peso normal o bajo peso tienen mejores hábitos de sueño que los niños con sobrepeso u obesidad (U=3.79, p<0.001).ConclusionesEste estudio muestra indicios de que los aspectos vinculados con la dimensión psicocorporal y con uso del tiempo libre deberían indagarse a mayor profundidad, ya que fueron los que arrojaron cifras que ubican a los escolares en riesgo medio y alto.AbstractObjectiveTo explore the association between lifestyle and nutritional status among school children.MethodCorrelational study involving 260 children registered at an ISSSTE clinic, who were randomly selected. A questionnaire on childhood lifestyles was used; weight and height were also assessed. A project approval from the ISSSTE research committee was obtained. Descriptive and inferential statistics were used.Results137 boys and 123 girls with ages between 6 and 12 years old participated. In relation to the nutrition status, five out every ten have a normal weight; two out every ten are over weighted, and one out of every ten is obese or under weighted respectively. In relation to lifestyle, seven out of every ten participants have low risk; and two out of every ten have medium risk. On the other hand a relation between the lifestyle and nutritional status of the children was not found (rs=.038, p>0.05). Moreover, it was found that children with normal or low weights have better sleep habits in comparison to the children who are over weighted or obese U=3.79, p <.001).ConclusionsThis study suggests that issues related to the psychological and corporal dimensions, as well as the use of free time, should be further explored because they showed figures which place children within mid and high risks
3D numerical model of the Omega Nebula (M17): simulated thermal X-ray emission
We present 3D hydrodynamical simulations of the superbubble M17, also known
as the Omega nebula, carried out with the adaptive grid code yguazu'-a, which
includes radiative cooling. The superbubble is modelled considering the winds
of 11 individual stars from the open cluster inside the nebula (NGC 6618), for
which there are estimates of the mass loss rates and terminal velocities based
on their spectral types. These stars are located inside a dense interstellar
medium, and they are bounded by two dense molecular clouds.
We carried out three numerical models of this scenario, considering different
line of sight positions of the stars (the position in the plane of the sky is
known, thus fixed). Synthetic thermal X-ray emission maps are calculated from
the numerical models and compared with ROSAT observations of this astrophysical
object. Our models reproduce successfully both the observed X-ray morphology
and the total X-ray luminosity, without taking into account thermal conduction
effects.Comment: 8 pages, 6 figures, accepted for publication in MNRA
Specific Parameter-Free Global Optimization to Speed Up Setting and Avoid Factors Interactions
Meta-heuristics utilizing numerous parameters are more complicated than meta-heuristics with a couple of parameters for various reasons. In essence, the effort expected to tune the strategy-particular parameters is far more prominent as the quantity of parameters increases and furthermore, complex algorithms are liable for the presence of further parameter interactions. Jaya meta-heuristic does not involve any strategy-specific parameters and is a one-stage technique. It has demonstrated its effectiveness compared to major types of meta-heuristics and it introduces various points of interest, such as its easy deployment and set-up in industrial applications and its low complexity to be studied. In this work, a new meta-heuristic, Enhanced Jaya (EJaya) is proposed to overcome the inconsistency of Jaya in diverse situations, introducing coherent attraction and repulsion movements and restrained intensity for flight. Comparative results of EJaya in a set of benchmark problems including statistical tests show that it is feasible to increase the accuracy, scalability and exploitation capability of Jaya while keeping its specific parameter-free feature. EJaya is especially suitable for a priori undefined characteristics optimization functions or applications where the set-up time of the optimization process is critical and parameters tuning and interactions must be avoided
Phenotype-loci associations in networks of patients with rare disorders: application to assist in the diagnosis of novel clinical cases
Copy number variations (CNVs) are genomic structural variations (deletions, duplications, or translocations) that represent the 4.8–9.5% of human genome variation in healthy individuals. In some cases, CNVs can also lead to disease, being the etiology of many known rare genetic/genomic disorders. Despite the last advances in genomic sequencing and diagnosis, the pathological effects of many rare genetic variations remain unresolved, largely due to the low number of patients available for these cases, making it difficult to identify consistent patterns of genotype–phenotype relationships. We aimed to improve the identification of statistically consistent genotype–phenotype relationships by integrating all the genetic and clinical data of thousands of patients with rare genomic disorders (obtained from the DECIPHER database) into a phenotype–patient–genotype tripartite network. Then we assessed how our network approach could help in the characterization and diagnosis of novel cases in clinical genetics. The systematic approach implemented in this work is able to better define the relationships between phenotypes and specific loci, by exploiting large-scale association networks of phenotypes and genotypes in thousands of rare disease patients. The application of the described methodology facilitated the diagnosis of novel clinical cases, ranking phenotypes by locus specificity and reporting putative new clinical features that may suggest additional clinical follow-ups. In this work, the proof of concept developed over a set of novel clinical cases demonstrates that this network-based methodology might help improve the precision of patient clinical records and the characterization of rare syndromes
X-ray emission and dynamics from large diameter superbubbles: The case of N 70 superbubble
The morphology, dynamics and thermal X-ray emission of the superbubble N70 is
studied by means of 3D hydrodynamical simulations, carried out with the
{\sc{yguaz\'u-a}} code. We have considered different scenarios: the superbubble
being the product of a single supernova remnant, of the stellar winds from an
OB association, or the result of the joint action of stellar winds and a
supernova event. Our results show that, in spite that all scenarios produce
bubbles with the observed physical size, only those where the bubble is driven
by stellar winds and a SN event are successful to explain the general
morphology, dynamics and the X-ray luminosity of N70. Our models predict
temperatures in excess of at the interior of the superbubble,
however the density is too low and the emission in thermal X-ray above is too faint to be detected.Comment: 9 pages, 11 figures, ApJ accepte
A direct measurement of the baryonic mass function of galaxies & implications for the galactic baryon fraction
We use both an HI-selected and an optically-selected galaxy sample to
directly measure the abundance of galaxies as a function of their "baryonic"
mass (stars + atomic gas). Stellar masses are calculated based on optical data
from the Sloan Digital Sky Survey (SDSS) and atomic gas masses are calculated
using atomic hydrogen (HI) emission line data from the Arecibo Legacy Fast ALFA
(ALFALFA) survey. By using the technique of abundance matching, we combine the
measured baryonic function (BMF) of galaxies with the dark matter halo mass
function in a LCDM universe, in order to determine the galactic baryon fraction
as a function of host halo mass. We find that the baryon fraction of low-mass
halos is much smaller than the cosmic value, even when atomic gas is taken into
account. We find that the galactic baryon deficit increases monotonically with
decreasing halo mass, in contrast with previous studies which suggested an
approximately constant baryon fraction at the low-mass end. We argue that the
observed baryon fractions of low mass halos cannot be explained by reionization
heating alone, and that additional feedback mechanisms (e.g. supernova blowout)
must be invoked. However, the outflow rates needed to reproduce our result are
not easily accommodated in the standard picture of galaxy formation in a LCDM
universe.Comment: Accepted to ApJ. 45 pages (aastex), 19 figures; added references and
updated fig.18 for version
Plasmodium vivax Cell Traversal Protein for Ookinetes and Sporozoites (CelTOS) Functionally Restricted Regions Are Involved in Specific Host-Pathogen Interactions
Following the injection of Plasmodium sporozoites by a female Anopheles mosquito into the dermis, they become engaged on a long journey to hepatic tissue where they must migrate through different types of cell to become established in parasitophorous vacuoles in hepatocytes. Studies have shown that proteins such as cell traversal protein for Plasmodium ookinetes and sporozoites (CelTOS) play a crucial role in cell-traversal ability. Although CelTOS has been extensively studied in various species and included in pre-clinical assays it remains unknown which P. vivax CelTOS (PvCelTOS) regions are key in its interaction with traversed or target cells (Kupffer or hepatocytes) and what type of pressure, association and polymorphism these important regions could have to improve their candidacy as important vaccine antigens. This work has described producing a recombinant PvCelTOS which was recognized by ~30% P. vivax-infected individuals, thereby confirming its ability for inducing a natural immune response. PvCelTOS' genetic diversity in Colombia and its ability to interact with HeLa (traversal cell) and/or HepG2 cell (target cell) external membrane have been assessed. One region in the PvCelTOS amino-terminal region and another in its C-terminus were seen to be participating in host-pathogen interactions. These regions had important functional constraint signals (? less than 0.3 and several sites under negative selection) and were able to inhibit specific rPvCelTOS binding to HeLa cells. This led to suggesting that sequences between aa 41–60 (40833) and 141–160 (40838) represent promising candidates for an anti-P. vivax subunit-based vaccine. © Copyright © 2020 Arévalo-Pinzón, Garzón-Ospina, Pulido, Bermúdez, Forero-Rodríguez, Rodríguez-Mesa, Reyes-Guarín, Suárez and Patarroyo
Analysis of substrate specificity of cytochrome P450 monooxygenases involved in trichothecene toxin biosynthesis
[EN]Trichothecenes are a structurally diverse family of toxic secondary metabolites produced by certain species of multiple fungal genera. All trichothecene analogs share a core 12,13-epoxytrichothec-9-ene (EPT) structure but differ in presence, absence and types of substituents attached to various positions of EPT. Formation of some of the structural diversity begins early in the biosynthetic pathway such that some producing species have few trichothecene biosynthetic intermediates in common. Cytochrome P450 monooxygenases (P450s) play critical roles in formation of trichothecene structural diversity. Within some species, relaxed substrate specificities of P450s allow individual orthologs of the enzymes to modify multiple trichothecene biosynthetic intermediates. It is not clear, however, whether the relaxed specificity extends to biosynthetic intermediates that are not produced by the species in which the orthologs originate. To address this knowledge gap, we used a mutant complementation-heterologous expression analysis to assess whether orthologs of three trichothecene biosynthetic P450s (TRI11, TRI13 and TRI22) from Fusarium sporotrichioides, Trichoderma arundinaceum, and Paramyrothecium roridum can modify trichothecene biosynthetic intermediates that they do not encounter in the organism in which they originated. The results indicate that TRI13 and TRI22 could not modify the intermediates that they do not normally encounter, whereas TRI11 could modify an intermediate that it does not normally encounter. These findings indicate that substrate promiscuity varies among trichothecene biosynthetic P450s. One structural feature that likely impacts the ability of the P450s to use biosynthetic intermediates as substrates is the presence and absence of an oxygen atom attached to carbon atom 3 of EPT.SIOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL
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