The Chandra Dust Scattering Halo of Galactic Center transient Swift J174540.7-290015

We report the detection of a dust scattering halo around a recently discovered X-ray transient, Swift J174540.7-290015, which in early February of 2016 underwent one of the brightest outbursts (F_X ~ 5e-10 erg/cm^2/s) observed from a compact object in the Galactic Center field. We analyze four Chandra images that were taken as follow-up observations to Swift discoveries of new Galactic Center transients. After adjusting our spectral extraction for the effects of detector pileup, we construct a point spread function for each observation and compare it to the GC field before the outburst. We find residual surface brightness around Swift J174540.7-290015, which has a shape and temporal evolution consistent with the behavior expected from X-rays scattered by foreground dust. We examine the spectral properties of the source, which shows evidence that the object transitioned from a soft to hard spectral state as it faded below L_X ~ 1e36 erg/s. This behavior is consistent with the hypothesis that the object is a low mass X-ray binary in the Galactic Center.Comment: Accepted for publication in Ap

Motivos y hábitos de práctica de actividad física en escolares de 12 a 16 años en una población rural de Sevilla

La creciente preocupación en nuestro país por los problemas que conllevan la obesidad y el sedentarismo plantea de forma imperiosa detectar las carencias en la actividad física de la población escolar. En este sentido nuestro estudio ahonda un poco más en los motivos y hábitos de práctica de niños y niñas entre 12 y 16 años de una zona rural de Sevilla. Los resultados muestran como tan solo un 28% de las chicas practica actividad física (AF) con asiduidad. Estos porcentajes no son tan preocupantes en el caso de los chicos (58%). Otro aspecto determinante en este trabajo ha sido el establecer los motivos que llevan a los alumnos a practicar AF, siendo la diversión el motivo fundamental en chicos y chicas (38% y 31% respectivamente). Similares motivos encuentran diversos autores (García Ferrando, 1997; Palou et al., 2005; Chillón, 2005). Por otra parte ¿la falta de tiempo¿ es el principal motivo que argumentan los alumnos para no practicar AF (24% de los chicos y 28% de las chicas), siendo éste el más determinante igualmente en otros trabajos (García Ferrando, 1997; Hernán et al., 2002; Palou et al., 2005). Teniendo en cuenta los motivos y prácticas aquí reflejados, padres y educadores debemos promover estrategias atractivas que reviertan positivamente en el ocio de nuestros niños, facilitando así los tan codiciados "hábitos saludables"

Correct regionalization of a tissue primordium is essential for coordinated morphogenesis.

During organ development, tubular organs often form from flat epithelial primordia. In the placodes of the forming tubes of the salivary glands in the Drosophila embryo, we previously identified spatially defined cell behaviors of cell wedging, tilting, and cell intercalation that are key to the initial stages of tube formation. Here, we address what the requirements are that ensure the continuous formation of a narrow symmetrical tube from an initially asymmetrical primordium whilst overall tissue geometry is constantly changing. We are using live-imaging and quantitative methods to compare wild-type placodes and mutants that either show disrupted cell behaviors or an initial symmetrical placode organization, with both resulting in severe impairment of the invagination. We find that early transcriptional patterning of key morphogenetic transcription factors drives the selective activation of downstream morphogenetic modules, such as GPCR signaling that activates apical-medial actomyosin activity to drive cell wedging at the future asymmetrically placed invagination point. Over time, transcription of key factors expands across the rest of the placode and cells switch their behavior from predominantly intercalating to predominantly apically constricting as their position approaches the invagination pit. Misplacement or enlargement of the initial invagination pit leads to early problems in cell behaviors that eventually result in a defective organ shape. Our work illustrates that the dynamic patterning of the expression of transcription factors and downstream morphogenetic effectors ensures positionally fixed areas of cell behavior with regards to the invagination point. This patterning in combination with the asymmetric geometrical setup ensures functional organ formation

Counting Arithmetical Structures on Paths and Cycles

Let G be a finite, connected graph. An arithmetical structure on G is a pair of positive integer vectors d, r such that (diag (d) - A) r=0 , where A is the adjacency matrix of G. We investigate the combinatorics of arithmetical structures on path and cycle graphs, as well as the associated critical groups (the torsion part of the cokernels of the matrices (diag (d) - A)). For paths, we prove that arithmetical structures are enumerated by the Catalan numbers, and we obtain refined enumeration results related to ballot sequences. For cycles, we prove that arithmetical structures are enumerated by the binomial coefficients ((2n-1)/(n-1)) , and we obtain refined enumeration results related to multisets. In addition, we determine the critical groups for all arithmetical structures on paths and cycles

Web blight

Web blight, caused by the fungus Thanatephorus cucumeris, is prevalent in tropical regions with high to moderate temp. and RH; more than 200 plant species serve as hosts to this pathogen. Hyphae can grow rapidly over healthy tissue of leaves, flowers, petioles, and pods. For efficient control, the use of disease-free seeds, elimination of harvest debris, crop rotation, mulching, using spaced furrows and intercropping; the use of adequate chemical products, the use of resistant var., and integrated control are also recommended. The symptoms and damage caused by the disease are illustrated in color. (CIAT)La mustia hilachosa, causada por el hongo Thanatephorus cucumeris, prevalece en las regiones tropicales con una temp. y HR entre moderada y alta; mas de 200 especies vegetales le sirven de hospedante al patogeno. Las hifas del hongo pueden crecer rapidamente en el tejido sano de las hojas, flores, peciolos y vainas. Para un buen control se recomienda el uso de semilla libre de patogenos, la eliminacion de residuos de cosecha, rotacion de cultivos, la utilizacion de cobertura vegetal, espaciamiento entre surcos y asociaciones; tambien se recomienda el control quimico, el uso de var. resistentes y el control integrado. Se ilustran a color los sintomas y danos causados por la enfermedad. (CIAT

Counting Arithmetical Structures on Paths and Cycles

Let G be a finite, connected graph. An arithmetical structure on G is a pair of positive integer vectors d, r such that (diag (d) - A) r=0 , where A is the adjacency matrix of G. We investigate the combinatorics of arithmetical structures on path and cycle graphs, as well as the associated critical groups (the torsion part of the cokernels of the matrices (diag (d) - A)). For paths, we prove that arithmetical structures are enumerated by the Catalan numbers, and we obtain refined enumeration results related to ballot sequences. For cycles, we prove that arithmetical structures are enumerated by the binomial coefficients ((2n-1)/(n-1)) , and we obtain refined enumeration results related to multisets. In addition, we determine the critical groups for all arithmetical structures on paths and cycles

Validation Study of Waray Text Readability Instrument

In 2012 the Leyte Normal University developed a computer software—modelled after the Spache Readability Formula (1953) made for English—made to help rank texts that can is used by teachers or research groups on selecting appropriate reading materials to support the DepEd’s MTB-MLE program in Region VIII, in the Philippines. However, “several experiments have already established that existing readability measures in English cannot directly be used to compute readability of other languages.” To validate the Waray Text Readability Instrument (WTRI) formula, 15 stories were rated by 24 randomly selected teachers from two elementary schools in Tacloban City. The WTRI software uses two factors in determining readability, namely: (a) sentence length and (b) frequency of commonly occurring words. The teachers’ task is to read the given text and rate the grade level of each text by considering these three factors: (1) frequency of commonly used words; (2) sentence length; and, (3) total number of words. The data gathered was compared with the WTRI’s ratings of the same texts. Statistical testing was done to determine if there is a significant difference between the teachers’ rating of the texts and the WTRI’s ratings. As a result, there was no significant difference between the software’s grade level ratings and that of the teachers’. It implied that the WTRI’s calculation is valid

Ahorro energético en riego por aspersión. Pruebas de nuevos aspersores en banco automático con viento

El consumo energético en regadío es directamente proporcional a los valores objetivos de presión de una red colectiva de riego presurizada. El sistema de riego en parcela que más condiciona esta presión objetivo es el riego por aspersión. En este trabajo se ha analizado el comportamiento de los aspersores más utilizados en España en condiciones normales de funcionamiento frente a condiciones de presiones más bajas. Para ello se utilizó un banco de ensayo automático con viento y otro en condiciones confinadas sin viento. Se analizaron los aspersores en múltiples condiciones de trabajo, priorizando en el estudio la variable presión. Para ello se contempló un rango de presiones de 1,5 bar a 3.5 bar y con dos regímenes de viento: sin viento y con viento moderado. Como resultados del estudio se ofrece un análisis global de los datos obtenidos, que justifican la posibilidad de reducir la presión en riego por aspersión Además, se profundiza en resultados concretos para la reducción de la presión en el marco de riego de doce por quince metros

Microscopic theory of network glasses

A molecular theory of the glass transition of network forming liquids is developed using a combination of self-consistent phonon and liquid state approaches. Both the dynamical transition and the entropy crisis characteristic of random first order transitions are mapped out as a function of the degree of bonding and the density. Using a scaling relation for a soft-core model to crudely translate the densities into temperatures, the theory predicts that the ratio of the dynamical transition temperature to the laboratory transition temperature rises as the degree of bonding increases, while the Kauzmann temperature falls relative to the laboratory transition. These results indicate why highly coordinated liquids should be "strong" while van der Waals liquids without coordination are "fragile".Comment: slightly revised version that has been accepted for publication in Phys. Rev. Let

Characterization of interactions of eggPC lipid structures with different biomolecules

In this paper we study the interactions of two biomolecules (ascorbic acid and Annonacin) with a bilayer lipid membrane. Egg yolk phosphatidylcholine (eggPC) liposomes (in crystalline liquid state) were prepared in solutions of ascorbic acid (AA) at different concentration levels. On the other hand, liposomes were doped with Annonacin (Ann), a mono-tetrahydrofuran acetogenin (ACG), which is an effective citotoxic substance. While AA pharmacologic effect and action mechanisms are widely known, those of Ann’s are only very recently being studied. Both Fourier Transformed Infrared (FTIR) and Raman spectroscopic techniques were used to study the participation of the main functional groups of the lipid bilayer involved in the membrane-solution interaction. The obtained spectra were comparatively analyzed, studying the spectral bands corresponding to both the hydrophobic and the hydrophilic regions in the lipid bilayer. Electrochemical experiments namely; impedance spectroscopy (EIS) and cyclic voltamperometry (CV) were used as the main characterization techniques to analyse stability and structural changes of a model system of supported EggPC bilayer in connection with its interactions with AA and Ann. At high molar ratios of AA, there is dehydration in both populations of the carbonyl group of the polar head of the lipid. On the other hand, Ann promotes the formation of hydrogen bonds with the carbonyl groups. No interaction between AA and phosphate groups is observed at low and intermediate molar ratios. Ann is expected to be able to induce the dehydration of the phosphate groups without the subsequent formation of H bonds with them. According to the electrochemical analysis, the interaction of AA with the supported lipid membrane does not alter its dielectric properties. This fact can be related to the conservation of structured water of the phosphate groups in the polar heads of the lipid. On the other hand, the incorporation of Ann into the lipid membrane generates an increase in the number of defects while changes the dielectric constant. This, in turn, can be associated with the induced dehydration of the phosphate groups.Facultad de Ciencias ExactasFacultad de Ingeniería (FI)Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA