The 3.5 keV Line from Stringy Axions

An interesting result in particle astrophysics is the recent detection of an unexplained 3.5 keV line from galaxy clusters. A promising model, which can explain the morphology of the signal and its non-observation in dwarf spheroidal galaxies, involves a 7 keV dark matter particle decaying into a pair of ultra-light axions that convert into photons in the magnetic field of the clusters. Given that light axions emerge naturally in 4D string vacua, in this paper we present a microscopic realisation of this model within the framework of type IIB flux compactifications. Dark matter is a local closed string axion which develops a tiny mass due to subdominant poly-instanton corrections to the superpotential and couples via kinetic mixing to an almost massless open string axion living on a D3-brane at a singularity. The interaction of this ultra-light axion with photons is induced by U(1) kinetic mixing. After describing the Calabi-Yau geometry and the brane set-up, we discuss in depth moduli stabilisation, the resulting mass spectrum and the strength of all relevant couplings.Comment: 27 pages + appendices, 1 figure; typos corrected, references added, additional comments on the cosmological history and DM production in the conclusion

Primordial Black Holes from String Inflation

We present a single-field string inflationary model which allows for the generation of primordial black holes in the low mass region where they can account for a significant fraction of the dark matter abundance. The potential is typical of type IIB fibre inflation models and features a plateau at CMB scales and a near inflection point at large distance scales where the power spectrum is enhanced due to a period of ultra slow-roll. The tunability of the underlying parameters is guaranteed by scanning through the string landscape and their stability against quantum corrections is ensured by an effective shift symmetry.Comment: Updated references, typos fixed. Version submitted to JCA

Study of Residual Stresses from Two Machining Protocols Using an Indentation Method

Although high-speed machining offers a number of advantages over conventional machining, it is possible that the residual stress distributions generated by the former can affect the service life of the processed components. In this paper, a newly developed micro-indent method is used to evaluate different residual stress states, which were introduced in samples of AA 7075-T6 aluminum alloy milled at low and high-speed. Different surfaces were generated by varying the cutting speed in one order of magnitude, from 100 m/min to 1000 m/min. Two machining protocols, which consist of using different machine tools, were evaluated. The results show that it is possible to generate and to evaluate very small residual stresses. Finally, the values and levels obtained for normal components were analyzed in function of mechanical and thermal effects that generated the residual stresses.Fil: Diaz, Felipe Victor. Universidad Catolica de Santiago del Estero. Departamento Academico de Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; ArgentinaFil: Mammana, Claudio A.. Universidad Catolica de Santiago del Estero. Departamento Academico de Rafaela; ArgentinaFil: Guidobono, Armando P.. Instituto Nacional de Tecnologia Industrial; Argentin

Determination and Analysis of Residual Stresses Induced by High Speed Milling Using a Micro-indent Method

The purpose of this work is to determine and analyze residual stress normal components and anisotropy degrees introduced by high-speed milling in specimens of AA 6082-T6 and AA 7075-T6 aluminum alloys. At each machined sample, the climb and conventional cutting zones were evaluated and compared. This paper includes a comprehensive study of thermal and mechanical effects associated with the residual stress introduction. For normal components determination, an optimized micro-indent method was used. Each measurement sequence from this approach was performed using a high accuracy measuring machine and classified according to thermal deviations measured. The residual displacements were determined with an absolute error down to ±300 nm. The normal components analysis allowed to infer the strong influence of the rolling process previous to high-speed milling and besides, the stress levels associated with thermal effects (higher in AA 7075-T6). Finally, the lower residual stress anisotropy degrees in both materials observed in the conventional cutting zone would indicate more homogenous local plastic stretching in this region for all planar directions.Fil: Vottero, S.. Universidad Tecnológica Nacional. Facultad Regional Rafaela; ArgentinaFil: Diaz, Felipe Victor. Universidad Tecnológica Nacional. Facultad Regional Rafaela; ArgentinaFil: Mammana, Claudio Alejandro. Universidad Tecnológica Nacional. Facultad Regional Rafaela; ArgentinaFil: Guidobono, A.. Instituto Nacional de Tecnología Industrial; Argentin

On the correlation between residual stresses and displacements of the polycrystalline lattice: an experimental strategy

This work aims to propose a micro-indent method to evaluate the correlation between the relaxation of residual stresses and the shape changes of the polycrystalline lattice in specimens of a rolled plate of AA 6082-T6 aluminium alloy. Rolling strengthens the surface of the plate by introducing compressive residual stresses. Then, these stresses are relaxed by thermal distension. The method of micro-indents allowed measuring residual displacements with an error below ± 300 nm. The results obtained reveal that the rolling direction plays a vital role in terms of asymmetric expansion of the lattice. Furthermore, the lattice accumulates and restores elastic strain energy in the clockwise and anti-clockwise direction of rotation, alternatively. Finally, when the stress release process is finishing, the lattice adjusts the angle of rotation to approximate to the initial geometric shape.Fil: Diaz, Felipe Victor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Tecnológica Nacional. Facultad Regional Rafaela; ArgentinaFil: Rosso, F. N.. Universidad Tecnológica Nacional. Facultad Regional Rafaela; ArgentinaFil: Walker, A. C.. Universidad Tecnológica Nacional. Facultad Regional Rafaela; ArgentinaFil: Guidobono, A.P.M.. Instituto Nacional de Tecnología Industrial. Centro Regional Rosario; Argentin

Introducing the Journal of Melittology: An outlet for disseminating bee research and raising melittological awareness

A new journal is introduced, the focus of which is to disseminate the results of research on wild and managed bees, to raise public awareness of bees, and to promote and facilitate international communication and collaboration

Patient Medication Instruction and Provider Interactions: Effects on Knowledge and Attitudes

This prospective study examines whether a patient medication instruction sheet (PMI) given to clinic patients by their health care provider affects knowledge and/or attitudes with thiazide diuretic use as part of an antihypertensive regimen. Adult male patients ( N = 285) in a general medicine clinic were assigned to groups receiving the American Medical Association PMI describing their diuretic. Patients getting the PMI obtained it either directly from their provider or at the pharmacy dispensing window. All patients were surveyed by phone 1 week following the clinic visit with regard to the PMI, knowledge of medication use, and attitudes toward drug use. Results indicate that a provider-dispensed PMI results in higher levels of drug knowledge and greater patient satisfaction with their knowledge than a pharmacy-dispensed PMI. In addition, the PMIs educational value may be lessened by an incomplete verbal consult. This study demonstrates that the AMA PMI is an effective educational tool when distributed by a provider and can promote better understanding and use of prescribed medications.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66928/2/10.1177_109019818601300106.pd

Clasificación automática de tipos de semilla de quinua a través de descriptores de color

Los agricultores de quinua para obtener cosechas optimas deben seleccionar de manera adecuada sus semillas a cultivar sin que se mezclen con otras variedades. La investigación actual se centra en la clasificación automática de tres tipos de semillas de quinua (Sacaca, Pasankalla y Salcedo) utilizando descriptores de color. Después de la adquisición de imágenes de semilla de quinua, se les asigna el filtro Gaussianblur para corregir y cuantificar el color en las imágenes permitiendo resaltar las diferencias entre las características de cada tipo de semilla de quinua. Las imágenes suavizadas se asignan al proceso de segmentación utilizando el método de Otsu para extraer después las características y realizar el entrenamiento de los clasificadores. Para realizar la clasificación de las semillas de quinua se utilizó SVM mediante el análisis lineal pixel a pixel. Los resultados de ensayo demuestran que el procedimiento de desarrollo tiene una alta precisión

Mutant PIK3CA promotes cell growth and invasion of human cancer cells

SummaryPIK3CA is mutated in diverse human cancers, but the functional effects of these mutations have not been defined. To evaluate the consequences of PIK3CA alterations, the two most common mutations were inactivated by gene targeting in colorectal cancer (CRC) cells. Biochemical analyses of these cells showed that mutant PIK3CA selectively regulated the phosphorylation of AKT and the forkhead transcription factors FKHR and FKHRL1. PIK3CA mutations had little effect on growth under standard conditions, but reduced cellular dependence on growth factors. PIK3CA mutations resulted in attenuation of apoptosis and facilitated tumor invasion. Treatment with the PI3K inhibitor LY294002 abrogated PIK3CA signaling and preferentially inhibited growth of PIK3CA mutant cells. These data have important implications for therapy of cancers harboring PIK3CA alterations