313 research outputs found

    Does relative deprivation induce migration?: evidence from Sub-Saharan Africa

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    This analysis revisits the decades-old relative deprivation theory of migration. In contrast to the traditional view that migration is driven by absolute income maximization, we test whether relative deprivation induces migration in the context of sub-Saharan Africa. Taking advantage of the internationally comparable longitudinal data from integrated household and agriculture surveys from Tanzania, Ethiopia, Malawi, Nigeria, and Uganda, we use panel fixed effects to estimate the effects of relative deprivation on migration decisions. Using per capita consumption expenditure and multidimensional wealth index as well-being measures, we find that a household’s migration decision is based not only on its absolute well-being level but also on the relative position of the household in the well-being distribution of the community in which it resides. We also discover that the effect of relative deprivation on migration is amplified in rural, agricultural, and male-headed households. Results are robust to alternative specifications including the use of Hausman Taylor Instrumental Variable (HTIV) estimator and pooled data across the five countries. Results confirm that the “migration-relative deprivation” relationship also holds in the context of sub-Saharan Africa. We argue that policies designed to check rural–urban migration through rural transformation and poverty reduction programs should use caution because such programs can increase economic inequality, which further increases migration flow

    Variation in brachial plexus formation, branching pattern and relation with major vessels

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    Background: Anatomical variations in the formation, branching pattern and relations of the brachial plexus have been described in humans by many authors; however these have not been extensively catalogued. The aim of the study was to describe variations in brachial plexus formation, branching pattern and relation with major vessels.Methods: This study included thorough dissection of 60 brachial plexuses which belonged to 30 cadavers (male: female ratio = 28:02 ) with age range of 20-60 years, obtained from the Department of Anatomy, College of Medical Sciences (CMS-TH), following standard guidelines. Results: Out of 60 limbs dissected in present study, the variation in formation was found in 20 limbs (33.3%), out of which 12 limbs (20%) had variations in the trunk and 8 limbs (13.3%) had variations in the cord, remaining 40 limbs (66.6%) were normal in the formation of brachial plexus. Normal branching pattern of the posterior cord was encountered in 52 (86.67%) limbs, the remaining 8 (13.33%) being variants in one form or the other. The upper subscapular nerve, the thoracodorsal nerve, the lower subscapular nerve and the axillary nerve were found to arise normally in 91.66%, 96.66%, 96.66% and 98.33% of the limbs respectively.Conclusion: The present study carried out on adult human cadavers revealed some rare variations in the formation, branching pattern and relations of the brachial plexus. These variations are of clinical significance for the surgeons, radiologists and the anesthesiologists.

    G10/COSMOS : 38 band (far-UV to far-IR) panchromatic photometry using LAMBDAR

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    We present a consistent total flux catalogue for a ∌1 deg2 subset of the Cosmic Evolution Survey (COSMOS) region (RA ∈ [149∘.55, 150∘.65], Dec. ∈ [1∘.80, 2∘.73]) with near-complete coverage in 38 bands from the far-ultraviolet to the far-infrared. We produce aperture matched photometry for 128 304 objects with i < 24.5 in a manner that is equivalent to the Wright et al. catalogue from the low-redshift (z < 0.4) Galaxy and Mass Assembly (GAMA) survey. This catalogue is based on publicly available imaging from GALEX, Canada–France–Hawaii Telescope, Subaru, Visible and Infrared Survey Telescope for Astronomy, Spitzer and Herschel, contains a robust total flux measurement or upper limit for every object in every waveband and complements our re-reduction of publicly available spectra in the same region. We perform a number of consistency checks, demonstrating that our catalogue is comparable to existing data sets, including the recent COSMOS2015 catalogue. We also release an updated Davies et al. spectroscopic catalogue that folds in new spectroscopic and photometric redshift data sets. The catalogues are available for download at http://cutout.icrar.org/G10/dataRelease.php. Our analysis is optimised for both panchromatic analysis over the full wavelength range and for direct comparison to GAMA, thus permitting measurements of galaxy evolution for 0 < z < 1 while minimizing the systematic error resulting from disparate data reduction methods.Publisher PDFPeer reviewe

    Galactic googly : the rotation-metallicity bias in the inner stellar halo of the Milky Way

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    The first and second moments of stellar velocities encode important information about the formation history of the Galactic halo. However, due to the lack of tangential motion and inaccurate distances of the halo stars, the velocity moments in the Galactic halo have largely remained ‘known unknowns’. Fortunately, our off-centric position within the Galaxy allows us to estimate these moments in the galactocentric frame using the observed radial velocities of the stars alone. We use these velocities coupled with the hierarchical Bayesian scheme, which allows easy marginalization over the missing data (the proper motion, and uncertainty-free distance and line-of-sight velocity), to measure the velocity dispersions, orbital anisotropy (ÎČ) and streaming motion (vrot) of the halo main-sequence turn-off (MSTO) and K-giant (KG) stars in the inner stellar halo (r â‰Č 15 kpc). We study the metallicity bias in kinematics of the halo stars and observe that the comparatively metal-rich ([Fe/H] > −1.4) and the metal-poor ([Fe/H] ≀ −1.4) MSTO samples show a clear systematic difference in vrot ∌ 20-40 km s−1, depending on how restrictive the spatial cuts to cull the disc contamination are. The bias is also detected in KG samples but with less certainty. Both MSTO and KG populations suggest that the inner stellar halo of the Galaxy is radially biased i.e. σr > σΞ or σϕ and ÎČ â‰ƒ 0.5. The apparent metallicity contrariety in the rotation velocity among the halo sub-populations supports the co-existence of multiple populations in the galactic halo that may have formed through distinct formation scenarios, i.e. in situ versus accretion.Publisher PDFPeer reviewe

    Galaxy and Mass Assembly (GAMA): Panchromatic data release (far-UV–far-IR) and the low-z energy budget

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    We present the Galaxy And Mass Assembly (GAMA) Panchromatic Data Release (PDR) constituting over 230 deg2 of imaging with photometry in 21 bands extending from the farUV to the far-IR. These data complement our spectroscopic campaign of over 300k galaxies, and are compiled from observations with a variety of facilities including: GALaxy Evolution eXplorer, Sloan Digital Sky Survey, Visible and Infrared Telescope for Astronomy (VISTA), Wide-field Infrared Survey Explorer, and Herschel, with the GAMA regions currently being surveyedbyVLTSurveyTelescope(VST)andscheduledforobservationsbyAustralianSquare Kilometer Array Pathfinder (ASKAP). These data are processed to a common astrometric solution, from which photometry is derived for ∌221373 galaxies with r < 19.8 mag. Online tools are provided to access and download data cutouts, or the full mosaics of the GAMA regions in each band. We focus, in particular, on the reduction and analysis of the VISTA VIsta Kilo-degree INfrared Galaxy data, and compare to earlier data sets (i.e. 2MASS and UKIDSS) before combining the data and examining its integrity. Having derived the 21-band photometric catalogue, we proceed to fit the data using the energy balance code MAGPHYS. These measurements are then used to obtain the first fully empirical measurement of the 0.1–500 ÎŒm energy output of the Universe. Exploring the cosmic spectral energy distribution across three time-intervals (0.3–1.1, 1.1–1.8, and 1.8–2.4 Gyr), we find that the Universe is currently generating (1.5 ± 0.3) × 1035 h70 W Mpc−3, down from (2.5 ± 0.2) × 1035 h70 W Mpc−3 2.3 Gyr ago. More importantly, we identify significant and smooth evolution in the integrated photon escape fraction at all wavelengths, with the UV escape fraction increasing from 27(18) per cent at z= 0.18 in NUV(FUV) to 34(23) per cent at z= 0.06. The GAMA PDR can be found at: http://gama-psi.icrar.org/

    Visual Reasoning with Multi-hop Feature Modulation

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    Recent breakthroughs in computer vision and natural language processing have spurred interest in challenging multi-modal tasks such as visual question-answering and visual dialogue. For such tasks, one successful approach is to condition image-based convolutional network computation on language via Feature-wise Linear Modulation (FiLM) layers, i.e., per-channel scaling and shifting. We propose to generate the parameters of FiLM layers going up the hierarchy of a convolutional network in a multi-hop fashion rather than all at once, as in prior work. By alternating between attending to the language input and generating FiLM layer parameters, this approach is better able to scale to settings with longer input sequences such as dialogue. We demonstrate that multi-hop FiLM generation achieves state-of-the-art for the short input sequence task ReferIt --- on-par with single-hop FiLM generation --- while also significantly outperforming prior state-of-the-art and single-hop FiLM generation on the GuessWhat?! visual dialogue task.Comment: In Proc of ECCV 201
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