3,980 research outputs found

    Analytical Modeling of Interference Aware Power Control for the Uplink of Heterogeneous Cellular Networks

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    Inter-cell interference is one of the main limiting factors in current Heterogeneous Cellular Networks (HCNs). Uplink Fractional Power Control (FPC) is a well known method that aims to cope with such limiting factor as well as to save battery live. In order to do that, the path losses associated with Mobile Terminal (MT) transmissions are partially compensated so that a lower interference is leaked towards neighboring cells. Classical FPC techniques only consider a set of parameters that depends on the own MT transmission, like desired received power at the Base Station (BS) or the path loss between the MT and its serving BS, among others. Contrary to classical FPC, in this paper we use stochastic geometry to analyze a power control mechanism that keeps the interference generated by each MT under a given threshold. We also consider a maximum transmitted power and a partial compensation of the path loss. Interestingly, our analysis reveals that such Interference Aware (IA) method can reduce the average power consumption and increase the average spectral efficiency. Additionally, the variance of the interference is reduced, thus improving the performance of Adaptive Modulation and Coding (AMC) since the interference can be better estimated at the MT.Comment: 13 pages, 1 table and 7 figures. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

    ANÁLISIS DEL DESEMPLEO, LA MIGRACIÓN Y LA POBREZA EN MÉXICO

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    La mayoría de los movimientos poblacionales en todas las regiones geográficas del mundo, obedecen principalmente a motivaciones vinculadas con la búsqueda de mejores condiciones de vida. No obstante, en casi todos los casos el costo social de lograr que los hogares reciban lo necesario para sobrevivir es la ruptura familiar y la seguridad personal.Los graves problemas que están enfrentando las economías subdesarrolladas con bajo o nulo crecimiento económico, altas tasas de desempleo, elevado índice de migración y millones de habitantes en pobreza extrema. El objetivo del presente trabajo fue analizar el desempleo, la migración y la pobreza en México. El desempleo es uno de los problemas de la economía mexicana (según INEGI de 5.5%), le sigue la migración y la pobreza extrema. Debido al incremento del desempleo y los bajos salarios que tiene el país estimulan a las personas a emigrar. Aunado a lo anterior, en Estados Unidos de América la tasa de desempleo de los migrantes mexicanos se elevó de 8.0% a 12.0% (2009) aproximadamente, provocando una fuerte disminución en las remesas, lo que trae como consecuencia una baja en los ingresos de las familias que viven de dichas transferencias ocasionando que se agudice la pobreza en el país

    A Xenon Mass Gauging through Heat Transfer Modeling for Electric Propulsion Thrusters

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    The authors gratefully acknowledge the financial support given for this work by the Swedish National Space Board (NRFP-3 Call), COMSOL® advisors and OHB-Sweden for their interest on this topic.Peer reviewedPublisher PD

    ANÃLISIS DEL DESEMPLEO, LA MIGRACIÓN Y LA POBREZA EN MÉXICO

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    Undeveloped economies are dealing with very big issues such as low or null economic growth, higher rates of unemployment, high index of migration and millions of people living in extreme poverty. Therefore, the present investigation aims to analyze unemployment, migration and poverty in Mexico; since unemployment in Mexico has a rate of 5.5% according to INEGI, followed by migration and extreme poverty. One of the most important effects from the previous matters is that they have stimulated people to migrate. Because of the unemployment increase and the low wages in the country it has been stimulated the population to migrate. In addition, in the USA, the unemployment rate of Mexican migrants has raised from 8.0 to 12.0% (2009) approximately, inducing a strong decrease in remittances, which brings as a consequence a diminish in families revenue that depend on such remittances, causing an intensification in the country's poverty.Unemployment, migration, poverty, remittances and income., Agribusiness,

    The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Angular clustering tomography and its cosmological implications

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    We investigate the cosmological implications of studying galaxy clustering using a tomographic approach applied to the final BOSS DR12 galaxy sample, including both auto- and cross-correlation functions between redshift shells. We model the signal of the full shape of the angular correlation function, ω(θ)\omega(\theta), in redshift bins using state-of-the-art modelling of non-linearities, bias and redshift-space distortions. We present results on the redshift evolution of the linear bias of BOSS galaxies, which cannot be obtained with traditional methods for galaxy-clustering analysis. We also obtain constraints on cosmological parameters, combining this tomographic analysis with measurements of the cosmic microwave background (CMB) and type Ia supernova (SNIa). We explore a number of cosmological models, including the standard Λ\LambdaCDM model and its most interesting extensions, such as deviations from w_\rm{DE} = -1, non-minimal neutrino masses, spatial curvature and deviations from general relativity using the growth-index γ\gamma parametrisation. These results are, in general, comparable to the most precise present-day constraints on cosmological parameters, and show very good agreement with the standard model. In particular, combining CMB, ω(θ)\omega(\theta) and SNIa, we find a value of w_\rm{DE} consistent with 1-1 to a precision better than 5\% when it is assumed to be constant in time, and better than 6\% when we also allow for a spatially-curved Universe.Comment: 21 pages, 18 figures, accepted for publication MNRAS. The data used in this analysis is publicly available at https://sdss3.org/science/boss_publications.ph

    The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS anisotropic galaxy clustering

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    With the largest spectroscopic galaxy survey volume drawn from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), we can extract cosmological constraints from the measurements of redshift and geometric distortions at quasi-linear scales (e.g. above 50 h1h^{-1}Mpc). We analyze the broad-range shape of the monopole and quadrupole correlation functions of the BOSS Data Release 12 (DR12) CMASS galaxy sample, at the effective redshift z=0.59z=0.59, to obtain constraints on the Hubble expansion rate H(z)H(z), the angular-diameter distance DA(z)D_A(z), the normalized growth rate f(z)σ8(z)f(z)\sigma_8(z), and the physical matter density Ωmh2\Omega_mh^2. We obtain robust measurements by including a polynomial as the model for the systematic errors, and find it works very well against the systematic effects, e.g., ones induced by stars and seeing. We provide accurate measurements {DA(0.59)rs,fid/rs\{D_A(0.59)r_{s,fid}/r_s Mpc\rm Mpc, H(0.59)rs/rs,fidH(0.59)r_s/r_{s,fid} kms1Mpc1km s^{-1} Mpc^{-1}, f(0.59)σ8(0.59)f(0.59)\sigma_8(0.59), Ωmh2}\Omega_m h^2\} = {1427±26\{1427\pm26, 97.3±3.397.3\pm3.3, 0.488±0.0600.488 \pm 0.060, 0.135±0.016}0.135\pm0.016\}, where rsr_s is the comoving sound horizon at the drag epoch and rs,fid=147.66r_{s,fid}=147.66 Mpc is the sound scale of the fiducial cosmology used in this study. The parameters which are not well constrained by our galaxy clustering analysis are marginalized over with wide flat priors. Since no priors from other data sets, e.g., cosmic microwave background (CMB), are adopted and no dark energy models are assumed, our results from BOSS CMASS galaxy clustering alone may be combined with other data sets, i.e., CMB, SNe, lensing or other galaxy clustering data to constrain the parameters of a given cosmological model. The uncertainty on the dark energy equation of state parameter, ww, from CMB+CMASS is about 8 per cent. The uncertainty on the curvature fraction, Ωk\Omega_k, is 0.3 per cent. We do not find deviation from flat Λ\LambdaCDM.Comment: 15 pages, 11 figures. The latest version matches and the accepted version by MNRAS. A bug in the first version has been identified and fixed in the new version. We have redone the analysis with newest data (BOSS DR12

    Petrographic and geochemical evidence for multiphase formation of carbonates in the Martian orthopyroxenite Allan Hills 84001

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    This research has been funded by the Spanish Ministry of Science and Innovation (projects: AYA2011‐26,522, AYA 2015‐67175‐P, CTQ2015‐62,635‐ERC, and CTQ2014‐60,119‐P to which J.M. Trigo‐Rodríguez and C.E. Moyano‐Cambero acknowledge financial support). The UK Science and Technology Facilities Council is also thanked for funding through grants ST/H002960/1, ST/K000942/1, and ST/L002167/1. ICN2 and ICMAB acknowledge support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grants SEV‐2013‐0295 and SEV‐2015‐0496, respectively. We acknowledge B. Ballesteros and M. Rosado from the ICN2 Electron Microscopy Division, and A. Fernández from the ICTS (National Center of Electronic Microscopy) for the SEM, EDS, and microprobe measurements. We also thank the NASA Meteorite Working Group, and the Johnson Space Center for providing the ALH 84001,82 section. This study was done in the frame of a PhD on Physics at the Autonomous University of Barcelona (UAB) under the direction of J. M. Trigo‐Rodríguez.Peer reviewedPublisher PD

    Effects of Maternal Fish Oil and/or 5-MethylTetrahydrofolate Supplementation during Pregnancy on Offspring Brain Resting-State at 10 Years Old: A Follow-Up Study from the NUHEAL Randomized Controlled Trial

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    Recent studies have shown that maternal supplementation with folate and long-chain polyunsaturated fatty acids (LC-PUFAs) during pregnancy may affect children’s brain development. We aimed at examining the potential long-term effect of maternal supplementation with fish oil (FO) and/or 5-methyl-tetrahydrofolate (5-MTHF) on the brain functionality of offspring at the age of 9.5–10 years. The current study was conducted as a follow-up of the Spanish participants belonging to the Nutraceuticals for a Healthier Life (NUHEAL) project; 57 children were divided into groups according to mother’s supplementation and assessed through functional magnetic resonance imaging (fMRI) scanning and neurodevelopment testing. Independent component analysis and double regression methods were implemented to investigate plausible associations. Children born to mothers supplemented with FO (FO and FO + 5-MTHF groups, n = 33) showed weaker functional connectivity in the default mode (DM) (angular gyrus), the sensorimotor (SM) (motor and somatosensory cortices) and the fronto-parietal (FP) (angular gyrus) networks compared to the No-FO group (placebo and 5-MTHF groups, n = 24) (PFWE < 0.05). Furthermore, no differences were found regarding the neuropsychological tests, except for a trend of better results in an object recall (memory) test. Considering the No-FO group, the aforementioned networks were associated negatively with attention and speed-processing functions. Mother’s FO supplementation during pregnancy seems to be able to shape resting-state network functioning in their children at school age and appears to produce long-term effects on children´s cognitive processing.European Union (EU) 212652 007036Commission of the European Community within the 5th Framework Program QLK1-CT-1999-00888European Research Council (ERC) 322605 META-GROWTHSpanish Ministry of Science, Innovation and Universities FJCI-2017-3339

    SDSS-III Baryon Oscillation Spectroscopic Survey data release 12 : galaxy target selection and large-scale structure catalogues

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    The Baryon Oscillation Spectroscopic Survey (BOSS), part of the Sloan Digital Sky Survey (SDSS) III project, has provided the largest survey of galaxy redshifts available to date, in terms of both the number of galaxy redshifts measured by a single survey, and the effective cosmological volume covered. Key to analysing the clustering of these data to provide cosmological measurements is understanding the detailed properties of this sample. Potential issues include variations in the target catalogue caused by changes either in the targeting algorithm or properties of the data used, the pattern of spectroscopic observations, the spatial distribution of targets for which redshifts were not obtained, and variations in the target sky density due to observational systematics. We document here the target selection algorithms used to create the galaxy samples that comprise BOSS. We also present the algorithms used to create large-scale structure catalogues for the final Data Release (DR12) samples and the associated random catalogues that quantify the survey mask. The algorithms are an evolution of those used by the BOSS team to construct catalogues from earlier data, and have been designed to accurately quantify the galaxy sample. The code used, designated mksample, is released with this paper.Publisher PDFPeer reviewe

    Radio source calibration for the VSA and other CMB instruments at around 30 GHz

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    Accurate calibration of data is essential for the current generation of CMB experiments. Using data from the Very Small Array (VSA), we describe procedures which will lead to an accuracy of 1 percent or better for experiments such as the VSA and CBI. Particular attention is paid to the stability of the receiver systems, the quality of the site and frequent observations of reference sources. At 30 GHz the careful correction for atmospheric emission and absorption is shown to be essential for achieving 1 percent precision. The sources for which a 1 percent relative flux density calibration was achieved included Cas A, Cyg A, Tau A and NGC7027 and the planets Venus, Jupiter and Saturn. A flux density, or brightness temperature in the case of the planets, was derived at 33 GHz relative to Jupiter which was adopted as the fundamental calibrator. A spectral index at ~30 GHz is given for each. Cas A,Tau A, NGC7027 and Venus were examined for variability. Cas A was found to be decreasing at 0.394±0.0190.394 \pm 0.019 percent per year over the period March 2001 to August 2004. In the same period Tau A was decreasing at 0.22±0.070.22\pm 0.07 percent per year. A survey of the published data showed that the planetary nebula NGC7027 decreased at 0.16±0.040.16\pm 0.04 percent per year over the period 1967 to 2003. Venus showed an insignificant (1.5±1.31.5 \pm 1.3 percent) variation with Venusian illumination. The integrated polarization of Tau A at 33 GHz was found to be 7.8±0.67.8\pm 0.6 percent at pa =148±3 = 148^\circ \pm 3^\circ.}Comment: 13 pages, 15 figures, submitted to MNRA
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