Adjusting the Labor Supply to Mitigate Violent Shocks: Evidence from Rural Colombia

This paper studies the use of labor markets to mitigate the impact of violent shocks on households in rural areas in Colombia. It examines changes in the labor supply from on-farm to off-farm labor as a means of coping with the violent shock and the ensuing redistribution of time within households. It identifies the heterogeneous response by gender. Because the incidence of violent shocks is not exogenous, the analysis uses instrumental variables that capture several dimensions of the cost of exercising terror. As a response to the violent shocks, households decrease the time spent on on-farm work and increase their supply of labor to off-farm activities (non-agricultural ones). Men carry the bulk of the adjustment in the use of time inasmuch as they supply the most hours to off-farm non-agricultural work and formal labor markets. Labor markets do not fully absorb the additional labor supply. Women in particular are unable to find jobs in formal labor markets and men have increased time dedicated to leisure and household chores. Additional off-farm supply does not fully cover the decrease in consumption. The results suggest that in rural Colombia, labor markets are a limited alternative for coping with violent shocks. Thus, policies in conflict-affected countries should go beyond short-term relief and aim at preventing labor markets from collapsing and at supporting the recovery of agricultural production.Conflict, labor markets, developing economies, instrumental variables

Highest Redshift Image of Neutral Hydrogen in Emission: A CHILES Detection of a Starbursting Galaxy at z = 0.376

Our current understanding of galaxy evolution still has many uncertainties associated with the details of the accretion, processing, and removal of gas across cosmic time. The next generation of radio telescopes will image the neutral hydrogen (H i) in galaxies over large volumes at high redshifts, which will provide key insights into these processes. We are conducting the COSMOS H i Large Extragalactic Survey (CHILES) with the Karl G. Jansky Very Large Array, which is the first survey to simultaneously observe H i from z = 0 to z ~ 0.5. Here, we report the highest redshift H i 21 cm detection in emission to date of the luminous infrared galaxy COSMOS J100054.83+023126.2 at z = 0.376 with the first 178 hr of CHILES data. The total H i mass is (2.9 ± 1.0) × 10^(10) M_⊙ and the spatial distribution is asymmetric and extends beyond the galaxy. While optically the galaxy looks undisturbed, the H i distribution suggests an interaction with a candidate companion. In addition, we present follow-up Large Millimeter Telescope CO observations that show it is rich in molecular hydrogen, with a range of possible masses of (1.8–9.9) × 10^(10) M_⊙. This is the first study of the H i and CO in emission for a single galaxy beyond z ~ 0.2

Topological biomarkers for real-time detection of epileptic seizures

Automated seizure detection is a fundamental problem in computational neuroscience towards diagnosis and treatment's improvement of epileptic disease. We propose a real-time computational method for automated tracking and detection of epileptic seizures from raw neurophysiological recordings. Our mechanism is based on the topological analysis of the sliding-window embedding of the time series derived from simultaneously recorded channels. We extract topological biomarkers from the signals via the computation of the persistent homology of time-evolving topological spaces. Remarkably, the proposed biomarkers robustly captures the change in the brain dynamics during the ictal state. We apply our methods in different types of signals including scalp and intracranial EEG and MEG, in patients during interictal and ictal states, showing high accuracy in a range of clinical situations.Comment: 21 pages, 12 figure

Discovery of a Small Central Disk of CO and HI in the Merger Remnant NGC 34

We present CO(1-0) and HI(21-cm) observations of the central region of the wet merger remnant NGC 34. The Combined Array for Research in Millimeter-wave Astronomy (CARMA) observations detect a regularly rotating disk in CO with a diameter of 2.1 kpc and a total molecular hydrogen mass of ($2.1 \pm 0.2) \times10^9~M_\odot$. The rotation curve of this gas disk rises steeply, reaching maximum velocities at 1" (410 pc) from the center. Interestingly, HI observations done with the Karl G. Jansky Very Large Array show that the absorption against the central continuum has the exact same velocity range as the CO in emission. This strongly suggests that the absorbing HI also lies within 1" from the center, is mixed in and corotates with the molecular gas. A comparison of HI absorption profiles taken at different resolutions (5"-45") shows that the spectra at lower resolutions are less deep at the systemic velocity. This provides evidence for HI emission in the larger beams, covering the region from 1 kpc to 9 kpc from the center. The central rapidly rotating disk was likely formed either during the merger or from fall-back material. Lastly, the radio continuum flux of the central source at mm wavelengths ($5.4\pm1.8$ mJy) is significantly higher than expected from an extrapolation of the synchrotron spectrum, indicating the contribution of thermal free-free emission from the central starburst.Comment: Accepted for publication in A

Gas in Galaxies in Different Environments across Cosmic Time

Cold gas is fundamental in understanding galaxy formation and evolution since it provides the fuel for star formation. In addition, the atomic gas can be used to probe the internal properties of galaxies, their halos, and their environment. Several of the remaining questions in galaxy evolution can be addressed by studying the gas properties in galaxies, in particular, the following three: (1) How do galaxies get their gas? (2) How do galaxies change over time? (3) How are galaxies affected by the environment? The work presented in this thesis addresses these questions. The thesis is divided into three parts that cover a range of topics related to gas in galaxies, including the fate of gas in a merger remnant, the evolution and distribution of halo gas, and how the gas properties of galaxies change as a function of redshift and environment. Part I consists of two chapters that present the atomic and molecular gas properties of a wet merger remnant (NGC 34). Chapter 2 is an analysis of the HI distribution and kinematics in NGC 34. We find that the progenitors of NGC 34 were gas-rich. The kinematics of the tidal tails suggest that some of the gas is returning to the central regions and forming an outer disk. In addition, we find puzzling absorption near the systemic velocity against the radio continuum. Chapter 3 is a follow-up study consisting of CO observations done with CARMA and new VLA data with a large velocity coverage to search for outflows. We detect CO concentrated in the inner regions that matches the velocity range of the HI in absorption, indicating that there is a circumnuclear disk in the central regions of molecular and atomic gas. We do not detect the outflow seen in the optical spectrum in CO or HI, but are able to place upper limits on both. Part II is an analysis of halo gas in a Milky Way mass galaxy. We use a cosmological high resolution hydrodynamic simulation to study the distribution, origin, and evolution of halo gas. At z=0, we find that the amount (~ 10⁸ M_sun), covering fraction and distribution are consistent with existing observations. The origin of halo gas is a combination of filamentary and satellite material. In addition, we find that the amount of halo gas is roughly constant between z=0.3 to z=0, but increases at earlier times. Part III presents results from the COSMOS HI Large Extragalactic Survey (CHILES), an HI deep field done with the VLA. These observations show how galaxies grow in different environments across cosmic time. We are using the expanded capabilities of the VLA to probe HI in part of the COSMOS field with a 5" resolution. Chapter 5 presents results from the pilot that was observed during commissioning. We observed for 60 hr and covered the redshift range 0<z<0.19 in one setting. We report 33 direct detections in different environments across the redshift range, and a stacked HI mass of (1.8 ± 0.3) x 10⁹ M_sun for galaxies in a wall at z=0.12. The pilot demonstrated that the VLA was ready to carry a full HI deep field. The full survey will be 1002 hr spread over several B array configurations. Chapter 6 presents preliminary results for the first 178 hr of the survey (Phase I). We describe the data reduction from Phase I, lessons for upcoming configurations, and present preliminary results. We detect very extended HI disks in nearby dwarf galaxies, and present the highest redshift detection to date (z=0.376)

Propuesta metodológica para la asignación del código único de entidad para los elementos incluidos en la base de datos cartográfica integrada a escala 1:100.000 del Instituto Geográfico Agustín Codazzi (IGAC)

El presente trabajo propone una metodología que permite asignar el Código Único de Entidad (CUE) para cada elemento geográfico con topónimo conocido e incluido en la Base de Datos Cartográfica Integrada escala 1:100.000 del Instituto Geográfico Agustín Codazzi (IGAC). Para ello se realizó el diagnóstico de la información entre la base de Nombres Geográficos a la escala de estudio encontrando inconsistencias como diferencias en los topónimos y/o posición, luego se resolvieron las inconsistencias encontradas de una plancha seleccionada, se editaron sobre la Base Integrada según observaciones realizadas a la plancha y se asignó el CUE a los elementos de ésta de acuerdo a la metodología plantead