612 research outputs found
Cornering pseudoscalar-mediated dark matter with the LHC and cosmology
Models in which dark matter particles communicate with the visible sector through a pseudoscalar mediator are well-motivated both from a theoretical and from a phenomenological standpoint. With direct detection bounds being typically subleading in such scenarios, the main constraints stem either from collider searches for dark matter, or from indirect detection experiments. However., LHC searches for the mediator particles themselves can not only compete with — or even supersede — the reach of direct collider dark matter probes, but they can also test scenarios in which traditional monojet searches become irrelevant, especially when the mediator cannot decay on-shell into dark matter particles or its decay is suppressed. In this work we perform a detailed analysis of a pseudoscalar-mediated dark matter simplified model, taking into account a large set of collider constraints and concentrating on the parameter space regions favoured by cos-mological and astrophysical data. We find that mediator masses above 100-200 GeV are essentially excluded by LHC searches in the case of large couplings to the top quark, while forthcoming collider and astrophysical measurements will further constrain the available parameter space
Computation of the Euler Number of a Binary Image Composed of Hexagonal Cells
ABSTRACTMost of the proposals to compute the Euler number of a binary image have been designed to work with imagescomposed of squared cells. Only a few of these methods (in the case of images composed of hexagonal cells) havebeen reported in literature, although it is known that images composed of hexagonal cells do not suffer from theproblems of connectivity frequently found in the case of images composed of squared cells. In this paper, a new wayto compute the Euler number (E) of a binary image composed of hexagonal cells is presented. For this, the perimeterP of the isolated regions in the image, their contact perimeter c P and the type T of a cell are used to obtain thisimportant invariant. The proposal can be used alone or in combination with other features to describe any binaryplanar shape composed of hexagonal pixels for its further recognition
Search for solar electron anti-neutrinos due to spin-flavor precession in the Sun with Super-Kamiokande-IV
Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMDue to a very low production rate of electron anti-neutrinos ( -v e) via nuclear fusion in the Sun, a flux of solar -v e is unexpected. An appearance of -v e in solar neutrino flux opens a new window for the new physics beyond the standard model. In particular, a spin-flavor precession process is expected to convert an electron neutrino into an electron anti-neutrino (ve → ̄ve) when neutrino has a finite magnetic moment. In this work, we have searched for solar v e in the Super-Kamiokande experiment, using neutron tagging to identify their inverse beta decay signature. We identified 78 v e candidates for neutrino energies of 9.3 to 17.3 MeV in 2970.1 live days with a fiducial volume of 22.5 kiloton water (183.0 kton⋅year exposure). The energy spectrum has been consistent with background predictions and we thus derived a 90% confidence level upper limit of 4.7×10−4 on the ve -> -v e conversion probability in the Sun. We used this result to evaluate the sensitivity of future experiments, notably the Super-Kamiokande Gadolinium (SK-Gd) upgrad
Tectónica reciente y activa en la parte occidental de la Cordillera Bética
Based on new seismological and recent faulting data, we analyze five main sectors in the western part of the Betic Cordillera from an active tectonic perspective: i. The northwestern frontal sector of the cordillera, including the Morón de la Frontera area, with shallow (< 15 km depth) seismogenic active NE-SW reverse and strike-slip faults that do not reach the surface. ii. The Teba area, in the External Zones, which is deformed by sparse N-S to NW-SE normal faults with associated wedges of Quaternary sediments and active strike-slip faults at intermediate crustal levels. iii. The Ronda Basin, representing the major Late Miocene intramontane basin of the western Betic Cordillera, is mainly deformed by NNE-SSW and WNW-ESE folds and locally by NW-SE normal faults. iv. The internal part of the orogen, which is characterized by shallow (<40 km) and intermediate (40 to 120 km depth) seismicity beneath Málaga and the Alborán Sea, ENE-WSW folding, relief uplift, river incision and scarce active faults with surface expression. v. The Spanish Atlantic coast, which coincides with the western end of the Betic orogen, where Pliocene to Quaternary shallowmarine sedimentary rocks are deformed by meso-scale NW-SE oriented normal faults and few ENE-WSW reverse faults. These data support the recent tectonic activity of the western Betic Cordillera determined by the NW-SE Eurasian-African convergence with variable features from the mountain front, characterized by shallow deformations, up to the Internal Zones that mainly undergo uplift and intermediate seismicity.Se han analizado, basándonos en nuevos datos sismológicos y de deformación reciente, cinco sectores de la Cordillera Bética occidental desde la perspectiva de la tectónica reciente: i. El sector frontal noroccidental de la cordillera, que incluye el área de Morón de la Frontera, con fallas sismogénicas superficiales (< 15 km de profundidad) de dirección NE-SO inversas y de salto en dirección, que no continúan hasta superficie. ii. El área de Teba, en las Zonas Externas, está deformada por escasas fallas de salto en dirección a niveles intermedios de la corteza y fallas normales de orientación N-S a NO-SE que cortan cuñas sedimentarias cuaternarias. iii. La Cuenca de Ronda, que representa la mayor cuenca intramontañosa de la Cordillera Bética occidental, está principalmente deformada por pliegues NNE-SSO y ONO-ESE y localmente por fallas normales de dirección NO-SE. iv. La parte interna del orógeno está caracterizada por sismicidad superficial (<40 km) e intermedia (40 a 120 km de profundidad) bajo Málaga y el Mar de Alborán, pliegues ENE-WSW, elevación del relieve, incisión fluvial y escasas fallas activas con expresión superficial. v. La costa Atlántica española, que coincide con la terminación occidental del orógeno Bético, donde las rocas sedimentarias marinas poco profundas del Plio-Cuaternario están deformadas por fallas normales NO-SE y algunas fallas inversas de orientación ENE-OSO. Todos estos datos revelan la actividad tectónica reciente de la Cordillera Bética occidental determinada por la convergencia NO-SE entre Eurasia y África, con variables características desde el frente montañoso, caracterizado por deformación superficial, hasta las Zonas Internas que muestran sismicidad intermedia y levantamiento
Surgical Options for the Refractive Correction of Keratoconus: Myth or Reality
Keratoconus provides a decrease of quality of life to the patients who suffer from it. The treatment used as well as the method to correct the refractive error of these patients may influence on the impact of the disease on their quality of life. The purpose of this review is to describe the evidence about the conservative surgical treatment for keratoconus aiming to therapeutic and refractive effect. The visual rehabilitation for keratoconic corneas requires addressing three concerns: halting the ectatic process, improving corneal shape, and minimizing the residual refractive error. Cross-linking can halt the disease progression, intrastromal corneal ring segments can improve the corneal shape and hence the visual quality and reduce the refractive error, PRK can correct mild-moderate refractive error, and intraocular lenses can correct from low to high refractive error associated with keratoconus. Any of these surgical options can be performed alone or combined with the other techniques depending on what the case requires. Although it could be considered that the surgical option for the refracto-therapeutic treatment of the keratoconus is a reality, controlled, randomized studies with larger cohorts and longer follow-up periods are needed to determine which refractive procedure and/or sequence are most suitable for each case
Theoretical Model to Estimate the Distribution of Radon in Alveolar Membrane Neighborhood
Radon is a naturally occurring radioactive gas which tends to concentrate indoors, easily emanates from the ground into the air, where it disintegrates and emits radioactive particles. It can enter the human body through breathing or ingesting mostly water. When radon inhaled, travels through the respiratory tract to alveoli where the majority is expelled into the environment. Moreover, when ingested in water, it passes into the intestine where it is absorbed and driven from the bloodstream to the lungs; in these organs, due to differences in partial pressures, it is transported to alveoli by simple diffusion process. When radon is not removed, it decays in short-lived solid disintegration products (218Po and 214Po) with high probability of being deposited in biological tissues, causing DNA damage because of the densely ionizing alpha radiation emitted. We propose a semi-empirical, smooth, and continuous pair potential function in order to model the molecular interactions between radon and lung alveolar walls; we use Molecular Dynamics (MD) to determine the gas distribution in an alveolar neighborhood wall, and estimate the quantity thereof it diffuses through the alveolar membrane as a concentration function
Monocyte chemotactic protein-1 (MCP-1) as a predictor of prolonged urinary incontinence after radical prostatectomy
Objectives: To investigate monocyte chemotactic protein-1 (MCP-1) as a novel urinary biomarker to predict prolonged post prostatectomy incontinence. Methods: Men submitted urine samples prior to robotic radical prostatectomy. MCP-1 values were derived using an ELISA test. Pad usage at 7, 30, and 60 days were documented by patient post cards mailed when zero pads was reached. The primary outcome was defined as no incontinence pad usage at 30 days at prostatectomy. Results: After exclusions, 76 patients were included in analyses. Continence was reached by 29% (22/76), 56% (42/76), and (75/76) 98% at 7, 30, and 60 days, respectively. The average MCP-1 (p=0.258) was not different between the continent and incontinent groups. Highest quartile of MCP-1 (MCP > 166 pg/mL) and normalized MCP-1 (MCP-1/TV >0.53) noted a significant delay in continence at 30 days (p=0.050 and p=0.003). Only 26% (5/19) in the highest MCP1/TV quartile were continent, whereas 65% (37/57) of men in the 3 lower quartiles reached zero pad continence (p=0.003). In a logistic regression model the highest quartile of MCP1/TV had a significant chance of being incontinent at 30 days (OR 0.22; 95% CI 0.058-0.80; p=0.022). Conclusion: MCP-1/TV is a urinary biomarker that may predict prolonged urinary incontinence after radical prostatectomy
Electro-extractive fermentation for efficient biohydrogen production
Electrodialysis, an electrochemical membrane technique, was found to prolong and enhance the production of biohydrogen and purified organic acids via the anaerobic fermentation of glucose by Escherichia coli. Through the design of a model electrodialysis medium using cationic buffer, pH was precisely controlled electrokinetically, i.e. by the regulated extraction of acidic products with coulombic efficiencies of organic acid recovery in the range 50–70% maintained over continuous 30-day experiments. Contrary to\ud
previous reports, E. coli produced H2 after aerobic growth in minimal medium without inducers and with a mixture of organic acids dominated by butyrate. The selective separation of organic acids from fermentation provides a potential nitrogen-free carbon source for further biohydrogen production in a parallel photofermentation. A parallel study incorporated this fermentation system into an integrated biohydrogen refinery (IBR) for the conversion of organic waste to hydrogen and energy
In vitro Study of the Survival, Reproduction and Morphology of Daphnia pulicaria irradiated with a Low Energy Laser
Daphnia is a genus of crustaceans that is representative of freshwater communities. The species exhibit a high sensitivity to a wide range of toxic compounds so that they have been used internationally as biomonitors in toxicity tests to evaluate ecosystem conditions such as water quality. It is also a model genus in genetics, epigenetics and reproductive ecology. In this work, we used Daphnia pulicaria as a model to measure the effects of low-energy laser irradiation on survival, reproduction, and morphology variables of parental organisms and their offspring. We used (1) a single clone line of organisms to eliminate interindividual genetic variability; (2) individuals from more than 50 generations after the clone line was established, and offspring from the third brood onwards to dissipate maternal and epigenetic effects, and (3) neonates, those individuals of the species that have less than 48 hours of life, because they are the most sensitive stage to optical stimuli. We analyzed number of deaths, longevity, age at first reproduction, number of offspring per week, number of total offspring during all their life cycle, body size, size of the antennules, and length of the apical spine of the 4th and 5th brood of the irradiated individuals, who were exposed to a blue laser stimulus of 405 nm for 25 minutes with a power of 40 mW at a distance of 50 cm, compared to those of the control (non-irradiated) group
Challenges in context-aware mobile language learning: the MASELTOV approach
Smartphones, as highly portable networked computing devices with embedded sensors including GPS receivers, are ideal platforms to support context-aware language learning. They can enable learning when the user is en-gaged in everyday activities while out and about, complementing formal language classes. A significant challenge, however, has been the practical implementation of services that can accurately identify and make use of context, particularly location, to offer meaningful language learning recommendations to users. In this paper we review a range of approaches to identifying context to support mobile language learning. We consider how dynamically changing aspects of context may influence the quality of recommendations presented to a user. We introduce the MASELTOV project’s use of context awareness combined with a rules-based recommendation engine to present suitable learning content to recent immigrants in urban areas; a group that may benefit from contextual support and can use the city as a learning environment
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