1,141 research outputs found

    A SUSY SU(5)xT' Unified Model of Flavour with large \theta_{13}

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    We present a SUSY SU(5)xT' unified flavour model with type I see-saw mechanism of neutrino mass generation, which predicts the reactor neutrino angle to be \theta_{13} = 0.14 close to the recent results from the Daya Bay and RENO experiments. The model predicts also values of the solar and atmospheric neutrino mixing angles, which are compatible with the existing data. The T' breaking leads to tri-bimaximal mixing in the neutrino sector, which is perturbed by sizeable corrections from the charged lepton sector. The model exhibits geometrical CP violation, where all complex phases have their origin from the complex Clebsch-Gordan coefficients of T'. The values of the Dirac and Majorana CP violating phases are predicted. For the Dirac phase in the standard parametrisation of the neutrino mixing matrix we get a value close to 90 degrees \delta = \pi/2 - 0.45 \theta^c = 84.3 degrees, \theta^c being the Cabibbo angle. The neutrino mass spectrum can be with normal ordering (2 cases) or inverted ordering. In each case the values of the three light neutrino masses are predicted with relatively small uncertainties, which allows to get also unambiguous predictions for the neutrino-less double beta decay effective Majorana mass.Comment: 31 pages, 7 figures; typos corrected, a few clarifying comments added; version to be published in Phys. Rev.

    Disk evolution in the Ori OB1 association

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    We analyze multi-band photometry of a subsample of low mass stars in the associations Ori OB1a and 1b discovered during the CIDA Orion Variability Survey, which have ages of 7 - 10 Myr and 3 - 5 Myr, respectively. We obtained UBVRcIc photometry at Mt. Hopkins for 6 Classical T Tauri stars (CTTS) and 26 Weak T Tauri stars (WTTS) in Ori OB1a, and for 21 CTTS and 2 WTTS in Ori OB1b. We also obtained L band photometry for 14 CTTS at Mt. Hopkins, and 10um and 18um photometry with OSCIR at Gemini for 6 CTTS; of these, all 6 were detected at 10um while only one was detected at 18um. We estimate mass accretion rates from the excess luminosity at U, and find that they are consistent with determinations for a number of other associations, with or without high mass star formation. The observed decrease of mass accretion rate with age is qualitatively consistent with predictions of viscous evolution of accretion disks. We find an overall decrease of disk emission from Taurus to Ori OB1b to Ori OB1a. This decrease implies that significant grain growth and settling towards the midplane has taken place in the inner disks of Ori OB1. We compare the SED of the star detected at both 10um and 18um with disk models for similar stellar and accretion parameters. We find that the low <= 18 um fluxes of this Ori OB1b star cannot be due to the smaller disk radius expected from viscous evolution in the presence of the FUV radiation fields from the OB stars in the association. Instead, we find that the disk of this star is essentially a flat disk, with little if any flaring, indicating a a significant degree of dust settling towards the midplane, as expected from dust evolution in protoplanetary disks.Comment: 35 pages, 11 figures, to appear in the Astronomical Journal. Full resolution figures in http://www.cida.ve/~briceno/publications

    An evolutionary model of industry dynamics and firms' institutional behavior with job search, bargaining and matching

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    This paper proposes an evolutionary model that captures the main dynamics of a world where heterogeneous firms and workers interact and co-evolve. Within a micro-meso perspective, the model focuses on the influence of firms' "institutional settings" on industry dynamics, formalizing these settings as firms' labor choices. Benefiting from insights offered by mainstream labor economics, we introduce the dynamic processes of job search, bargaining and matching in an evolutionary framework. The results of a computer simulation model show that in a stable environment there is an initial clear improvement in the average fitness of the population of incumbent firms, which then evolves around an evolutionary stationary threshold. The consideration of endogenous matching and bargaining processes in the labor market results in important frictions. Furthermore, the simulation results show an increasing wage inequality between the two types of workers considered in the model. We also consider the effect of both positive and negative demand shocks. The turbulence in the industry increases (decreases) after the negative (positive) demand shock. As expected, the negative demand shock causes a decrease in the number of vacancies and, consequently, the unemployment rates increase considerably. Following the positive demand shock, on the other hand, the firms slightly increase the number of vacancies, so the behavior in terms of unemployment rates is better than in the model without shocks.evolutionary, firm behavior, job search, bargaining and matching, microfoundations, industrial dynamics

    Effective Temperatures of Low-Mass Stars from High-Resolution H-band Spectroscopy

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    High-resolution, near-infrared spectra will be the primary tool for finding and characterizing Earth-like planets around low-mass stars. Yet, the properties of exoplanets can not be precisely determined without accurate and precise measurements of the host star. Spectra obtained with the Immersion GRating INfrared Spectrometer (IGRINS) simultaneously provide diagnostics for most stellar parameters, but the first step in any analysis is the determination of the effective temperature. Here we report the calibration of high-resolution H-band spectra to accurately determine effective temperature for stars between 4000-3000 K (\simK8--M5) using absorption line depths of Fe I, OH, and Al I. The field star sample used here contains 254 K and M stars with temperatures derived using BT-Settl synthetic spectra. We use 106 stars with precise temperatures in the literature to calibrate our method with typical errors of about 140 K, and systematic uncertainties less than \sim120 K. For the broadest applicability, we present Teff_{\rm eff}--line-depth-ratio relationships, which we test on 12 members of the TW Hydrae Association and at spectral resolving powers between \sim10,000--120,000. These ratios offer a simple but accurate measure of effective temperature in cool stars that is distance and reddening independent.Comment: 19 pages, 11 figures and 3 tables. Accepted in Ap

    Radii of 88 M subdwarfs and updated radius relations for low-metallicity M-dwarf stars

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    M subdwarfs are low-metallicity M dwarfs that typically inhabit the halo population of the Galaxy. Metallicity controls the opacity of stellar atmospheres; in metal-poor stars, hydrostatic equilibrium is reached at a smaller radius, leading to smaller radii for a given effective temperature. We compile a sample of 88 stars that span spectral classes K7 to M6 and include stars with metallicity classes from solar-metallicity dwarf stars to the lowest metallicity ultra subdwarfs to test how metallicity changes the stellar radius. We fit models to Palomar Double Spectrograph (DBSP) optical spectra to derive effective temperatures (T_ eff) and we measure bolometric luminosities (L_ bol) by combining broad wavelength-coverage photometry with Gaia parallaxes. Radii are then computed by combining the T_ eff and L_ bol using the Stefan–Boltzman law. We find that for a given temperature, ultra subdwarfs can be as much as five times smaller than their solar-metallicity counterparts. We present color-radius and color-surface brightness relations that extend down to [Fe/H] of −2.0 dex, in order to aid the radius determination of M subdwarfs, which will be especially important for the WFIRST exoplanetary microlensing survey.Published versio

    Modernisasi UMKM Berbasis Digital Marketing Pada Kelurahan Sukaramai, Pekanbaru

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    Perkembangan Teknologi mengubah cara hidup masyarakat. Termasuk cara berdagang yang harus mengikuti kebutuhan konsumen. Konsumen cenderung memanfaatkan teknologi informasi dalam berbelanja. Warga Kelurahan Sukaramai rata-rata merupakan pedagang kelas mikro sampai menengah terkhususnya di bidang pangan. Namun, usaha yang dijalani oleh para pedagang ini masih berbasis berdagang di tempat dan belum terbuka di dalam jaringan. Pengabdian ini bertujuan untuk membantu modernisasi usaha mikro kecil menengah pedagang di Kelurahan Sukaramai dari bentuk tradisional ke dalam bentuk Digital Marketing. Metode penelitian yang digunakan pada penelitian ini adalah metode pelatihan langsung dengan dua tahap yaitu tahapan persiapan dan tahap pelaksanaan. Pelaksanaan kegiatan ini memberikan dampak yang positif bagi masyarakat Kelurahan Sukaramai khususnya bagi para pedagang

    Analysing participatory video through the capability approach. A case study in Quart de Poblet (Valencia, Spain)

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    The aim of this paper is to analyse participatory video as a participatory action research method through the lenses of the capability approach. In order to do this, we used a participatory video experience that took place in the municipality of Quart de Poblet (Valencia, Spain) from February to March 2014. The participants were 11 young people between 16 and 24 years of age, severely affected by the economic crisis that has hit Spain in recent years. To develop our analysis, we introduced the participatory video as a technique and a process within the participatory action research methods. Then, we analysed the participatory process to verify the extent to which it had contributed to expanding the capabilities and agency of the participants. The evidence revealed a significant expansion of the awareness capability and, in some cases, of the capability for voice. In contrast, the capability to aspire and the agency of the participants were not expanded, due to contextual factors and the limitations of the process itself

    Energetic Components of Cooperative Protein Folding

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    A new lattice protein model with a four-helix bundle ground state is analyzed by a parameter-space Monte Carlo histogram technique to evaluate the effects of an extensive variety of model potentials on folding thermodynamics. Cooperative helical formation and contact energies based on a 5-letter alphabet are found to be insufficient to satisfy calorimetric and other experimental criteria for two-state folding. Such proteinlike behaviors are predicted, however, by models with polypeptide-like local conformational restrictions and environment-dependent hydrogen bonding-like interactions.Comment: 11 pages, 4 postscripts figures, Phys. Rev. Lett. (in press

    Childhood sleep disturbance and risk of psychotic experiences at 18 : UK birth cohort

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    BACKGROUND: Sleep disturbances are commonly reported in the psychosis prodrome, but rarely explored in relation to psychotic experiences. AIMS: To investigate the relationship between specific parasomnias (nightmares, night terrors and sleepwalking) in childhood and later adolescent psychotic experiences. METHOD: The sample comprised 4720 individuals from a UK birth cohort. Mothers reported on children's experience of regular nightmares at several time points between 2 and 9 years. Experience of nightmares, night terrors and sleepwalking was assessed using a semi-structured interview at age 12. Psychotic experiences were assessed at ages 12 and 18 using a semi-structured clinical interview. RESULTS: There was a significant association between the presence of nightmares at 12 and psychotic experiences at 18 when adjusted for possible confounders and psychotic experiences at 12 (OR = 1.62, 95% CI 1.19-2.20). The odds ratios were larger for those who reported persistent psychotic experiences. CONCLUSIONS: The presence of nightmares might be an early risk indicator for psychosis
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