Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Cambio de nicho climático y modelos de distribución potencial de especies invasoras

"Las especies invasoras representan una de las principales amenazas para la diversidad biológica, ya que modifican los ecosistemas, hibridan con especies nativas y compiten por los recursos disponibles. Durante el proceso de invasión, estas especies enfrentan diferentes retos, como adaptarse a condiciones abióticas diferentes a las del área nativa o enfrentarse a nuevos competidores, como como plagas y depredadores. Las condiciones físicas son determinantes en la distribución de las plantas, ya que son limitantes ecológicos y fisiológicos para la distribución de las especies. Para estimar el cambio de nicho climático se seleccionaron 19 especies de plantas introducidas en tierras bajas de Sur América y originarias de África, a las cuales, por medio de un análisis de ordenación, se les cuantificó la dinámica del nicho climático presentado entre el área de origen - África y el área invasora- América." -- Tomado del Formato de Documento de Grado.By September 2017 there were 50.278 demobilized who initiated the reintegration process: 6.799 women and 45.479 men. Even though one of the main elements to assure that they will not reoffend is the finding of a licit income source, the unemployment rate is 19.6%, more than the national average. Additionally, the unemployment rate for demobilized women doing the reintegration process is 39.1% while for men it is of 15.6%. The Item Count Technique (also known as list experiment) identifies the social desirability bias for calculating the labor discrimination and the gender gap on it. The results show that there is a social desirability bias regarding the willingness of hiring a demobilized person. Potential employees are also more willing to hire a demobilized man (62.38%) than a woman (46.11%). Finally, there exists a social desirability bias of 17.45 percentage points for hiring a demobilized woman, while for men this bias is of 4.29 percentage pointsMagíster en Ciencias BiológicasMaestrí

Plantas exóticas con alto potencial de invasión en Colombia

Como parte de la misión del Instituto Humboldt y en el marco del Plan Operativo y el Plan trienal de Investigación PICIA, el Programa de Ciencias de la Biodiversidad y su línea de Evaluación de riesgo de vida Silvestre, presenta la publicación Plantas exóticas con alto potencial de invasión en Colombia, como resultado del trabajo colaborativo entre el Instituto Humboldt y el Instituto Amazónico de Investigaciones Sinchi

Influencias del cambio climático y la variabilidad climática sobre el recurso hídrico, biodiversidad y servicios ecosistémicos en el departamento del Magdalena

El Cambio Climático global es una de las mayores preocupaciones de la humanidad dado por el gran impacto que puede tener en la sostenibilidad futura del desarrollo socioeconómico y ambiental. La variabilidad climática a largo plazo no se manifiesta de forma uniforme en todos los lugares, depende de las características particulares de cada región. Por lo que el desarrollo de análisis regionales de variables como la precipitación, temperatura, velocidad del viento, clorofila, NDVI, precipitación, anomalías del nivel del mar, entre otros son altamente relevantes para permitir un acercamiento a los efectos locales que pueden ser ocasionados por los procesos climáticos globales. Este libro recopila investigaciones realizadas en el departamento del Magdalena, sobre como el cambio climático y sus consecuencias negativas puede influir en este departamento, como afecta a la comunidad y su desarrollo.Primera Edició

Multinational prospective cohort study of incidence and risk factors for central line-associated bloodstream infections in ICUs of 8 Latin American countries

Background: Our objective was to identify central line (CL)-associated bloodstream infections (CLABSI) rates and risk factors in Latin-America. Methods: From January 1, 2014 to February 10, 2022, we conducted a multinational multicenter prospective cohort study in 58 ICUs of 34 hospitals in 21 cities in 8 Latin American countries (Argentina, Brazil, Colombia, Costa Rica, Dominican Republic, Ecuador, Mexico, Panama). We applied multiple-logistic regression. Outcomes are shown as adjusted-odds ratios (aOR). Results: About 29,385 patients were hospitalized during 92,956 days, acquired 400 CLABSIs, and pooled CLABSI rate was 4.30 CLABSIs per 1,000 CL-days. We analyzed following 10 variables: Gender, age, length of stay (LOS) before CLABSI acquisition, CL-days before CLABSI acquisition, CL-device utilization (DU) ratio, CL-type, tracheostomy use, hospitalization type, intensive care unit (ICU) type, and facility ownership, Following variables were independently associated with CLABSI: LOS before CLABSI acquisition, rising risk 3% daily (aOR=1.03;95%CI=1.02-1.04; P < .0001); number of CL-days before CLABSI acquisition, rising risk 4% per CL-day (aOR=1.04;95%CI=1.03-1.05; P < .0001); publicly-owned facility (aOR=2.33;95%CI=1.79-3.02; P < .0001). ICU with highest risk was medical-surgical (aOR=2.61;95%CI=1.41-4.81; P < .0001). CL with the highest risk were femoral (aOR=2.71;95%CI=1.61-4.55; P < .0001), and internal-jugular (aOR=2.62;95%CI=1.82-3.79; P < .0001). PICC (aOR=1.25;95%CI=0.63-2.51; P = .52) was not associated with CLABSI risk. Conclusions: Based on these findings it is suggested to focus on reducing LOS, CL-days, using PICC instead of femoral or internal-jugular; and implementing evidence-based CLABSI prevention recommendations.Revisión por pare

Voces de la gestión territorial. Estrategias complementarias para la conservación de la biodiversidad en Colombia

Colombia es un país con una alta riqueza biológica y cultural, tan diverso en su territorio como en las estrategias de conservación que en él se implementan. Sin embargo, muchas de estas estrategias no se han dado a conocer lo suficiente, lo que hace difícil su articulación a los procesos de gestión y ordenamiento del territorio. Existen algunos avances en su identificación como los ejercicios que se han realizado en los sistemas regionales de áreas protegidas para recopilar la información sobre estrategias complementarias de conservación en sus jurisdicciones, la articulación que realizan organizaciones privadas para identificar las iniciativas de conservación voluntaria por parte de la sociedad civil y el trabajo realizado por comunidades campesinas, indígenas y afrodescendientes para visibilizar sus áreas de conservación. Este libro, por lo tanto, tiene como objetivo visibilizar experiencias de conservación y gestión de la biodiversidad, diferentes a las áreas protegidas, teniendo en cuenta que el Convenio de Diversidad Biológica a través de la Meta Aichi 11 introduce el concepto de otras medidas efectivas de conservación basadas en áreas (OMEC) o áreas conservadas como instrumentos para lograr sistemas de conservación más completos, representativos y efectivamente gestionados (UNEP CDB, 2010). Esperamos sea un aporte para llenar un vacío de conocimiento acerca de dichas estrategias, mostrando sus principales características, los diferentes tipos de gobernanza con los que cuentan, sus mecanismos de implementación, fortalezas y debilidades, aprendizajes y cómo estos pueden ser aplicados a la gestión de la biodiversidad en el territorio.Servicios ecosistémicosGobernanzaManejo de territoriosDeforestación de bosquesPérdida y degradaciónEcosistemasComunidades localesConservación de la biodiversida

Searches for the ZγZ\gamma decay mode of the Higgs boson and for new high-mass resonances in pppp collisions at s=13\sqrt{s} = 13 TeV with the ATLAS detector

International audienceThis article presents searches for the Zγ decay of the Higgs boson and for narrow high-mass resonances decaying to Zγ, exploiting Z boson decays to pairs of electrons or muons. The data analysis uses 36.1 fb$^{−1}$ of pp collisions at $\sqrt{s}=13$ recorded by the ATLAS detector at the CERN Large Hadron Collider. The data are found to be consistent with the expected Standard Model background. The observed (expected — assuming Standard Model pp → H → Zγ production and decay) upper limit on the production cross section times the branching ratio for pp → H → Zγ is 6.6. (5.2) times the Standard Model prediction at the 95% confidence level for a Higgs boson mass of 125.09 GeV. In addition, upper limits are set on the production cross section times the branching ratio as a function of the mass of a narrow resonance between 250 GeV and 2.4 TeV, assuming spin-0 resonances produced via gluon-gluon fusion, and spin-2 resonances produced via gluon-gluon or quark-antiquark initial states. For high-mass spin-0 resonances, the observed (expected) limits vary between 88 fb (61 fb) and 2.8 fb (2.7 fb) for the mass range from 250 GeV to 2.4 TeV at the 95% confidence level

Search for direct top squark pair production in final states with two leptons in s=13\sqrt{s} = 13 TeV pppp collisions with the ATLAS detector

International audienceThe results of a search for direct pair production of top squarks in events with two opposite-charge leptons (electrons or muons) are reported, using $36.1~\hbox {fb}^{-1}$ of integrated luminosity from proton–proton collisions at $\sqrt{s}=13$ TeV collected by the ATLAS detector at the Large Hadron Collider. To cover a range of mass differences between the top squark $\tilde{t}$ and lighter supersymmetric particles, four possible decay modes of the top squark are targeted with dedicated selections: the decay $\tilde{t} \rightarrow b \tilde{\chi }_{1}^{\pm }$ into a b-quark and the lightest chargino with $\tilde{\chi }_{1}^{\pm } \rightarrow W \tilde{\chi }_{1}^{0}$ , the decay $\tilde{t} \rightarrow t \tilde{\chi }_{1}^{0}$ into an on-shell top quark and the lightest neutralino, the three-body decay $\tilde{t} \rightarrow b W \tilde{\chi }_{1}^{0}$ and the four-body decay $\tilde{t} \rightarrow b \ell \nu \tilde{\chi }_{1}^{0}$ . No significant excess of events is observed above the Standard Model background for any selection, and limits on top squarks are set as a function of the $\tilde{t}$ and $\tilde{\chi }_{1}^{0}$ masses. The results exclude at 95% confidence level $\tilde{t}$ masses up to about 720 GeV, extending the exclusion region of supersymmetric parameter space covered by previous searches

Measurements of ttˉt\bar{t} differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pppp collisions at s=13 \sqrt{s}=13\, TeV using the ATLAS detector

Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and $t\bar{t}$ system kinematic observables using proton--proton collisions at a center-of-mass energy of $\sqrt{s} = 13$ TeV. The data set corresponds to an integrated luminosity of $36.1$ fb$^{-1}$, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum $p_{\rm T} > 500$ GeV and a second with $p_{\rm T}>350$ GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a $b$-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated $\chi^2$ values. The cross-section for $t\bar{t}$ production in the fiducial phase-space region is $292 \pm 7 \ \rm{(stat)} \pm 76 \rm{(syst)}$ fb, to be compared to the theoretical prediction of $384 \pm 36$ fb