¿Qué es el estuario de Bahía Blanca?

El estuario de Bahía Blanca es uno de los accidentes geográficos menos conocidos de la costa atlántica de la provincia de Buenos Aires (Argentina). Se pueden apreciar interesantes y hasta excepcionales características biológicas, geomorfológicas y oceanográficas. Es un área de algo más de 3000 km2 que, en su tipo, es sólo superada en extensión en la Argentina por el estuario del Plata. Este artículo de divulgación científica se pregunta por qué este notable desconocimiento de uno de los accidentes costeros más llamativos del país; incluye información sobre diversos tipos de estuarios, detalles sobre cangrejales y otros temas, así como lecturas sugeridas

Dinámica de aguas superficiales de tres períodos continuos de Landsat; diferencias subregionales en llanuras argentinas

[EN] The Pampean region in Argentina is an extensive plain characterized by abundant shallow lakes that fulfill many environmental, ecological, and social functions. This study aims to detect the multiannual lake area changes in this region during 2001-2009 using remote sensing, including lakes as small as ≥10,000 m2 or 1 ha. Landsat scenes of the wet (2008-2009), normal (2006), and dry (2008-2009) seasons were obtained, and using remote sensing techniques, the number and area of shallow lakes were calculated. The spatiotemporal variation of shallow lakes was studied in different climate periods in eight singular subregions. Spatial associations between annual precipitation and lake number and area were analyzed through the development of a Geographic Information System (GIS) at a subregional scale. During the study period the total lake area in the Pampean region decreased by 5257.39 km2 (62 %), but each subregion showed different responses to climatic events. In seven of them, the differences between climate periods prove to be statistically significant (P>0.01). The relationship between precipitation and lake number and area revealed the domain of positive association. We conclude that climate factors play a dominant role in lake changes across the Pampean plains. However, other factors such as origin, topographic and edaphic characteristics intensify or mitigate changes in surface hydrology.[ES] La Región Pampeana en Argentina es una extensa planicie caracterizada por abundantes lagunas que cumplen numerosas funciones ambientales, ecológicas y sociales. Este estudio tiene como objetivo detectar los cambios plurianuales del área lagunar en esta región durante el período 2001-2009 utilizando la teledetección, incluidos lagos tan pequeños como ≥ 10.000 m2 o 1 ha. Se obtuvieron escenas Landsat de las estaciones húmeda (2008-2009), normal (2006) y seca (2008-2009) y, mediante técnicas de teledetección, se calculó el número y el área de las lagunas. Se estudió su variación espacio-temporal en diferentes períodos climáticos en ocho subregiones singulares. Se analizaron las correlaciones espaciales entre la precipitación anual y el número y el área de los lagos mediante el desarrollo de un Sistema de Información Geográfica (SIG). Durante el período de estudio el área total de lagos en la región pampeana disminuyó en 5.257,39  km2 (62 %), pero cada subregión mostró diferentes respuestas a los eventos climáticos. En siete de ellos, las diferencias entre periodos climáticos resultan estadísticamente significativas (P>0,01). La relación entre la precipitación con el número y área de las lagunas reveló el dominio de asociaciones positivas. Si bien el clima juega un papel dominante en los cambios en las lagunas de planicie, otros factores, como el origen, las características topográficas y edáficas, intensifican o mitigan los cambios en la hidrología superficial.Authors would like to thank the Consejo Nacional de Investigaciones Científicas y Técnicas for supporting this study. Besides, to the United States Geological Survey for supplying the information analyzed in this study. This work was carried out with the aid of a grant from the Inter-American Institute for Global Change Research (IAI) CRN3038, which is supported by the US National Science Foundation (Grant GEO-1128040)Aliaga, VS.; Piccolo, M.; Perillo, G. (2021). Surface water extent dynamics from three periods of continuous Landsat time series; subregional differences across Argentine plains. Revista de Teledetección. 0(58):131-145. http://hdl.handle.net/10251/169769OJS13114505

Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters

Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV

The Lambda(b) differential production cross section and the cross section ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Lambda(b) decays reconstructed in the exclusive final state J/Psi Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and Lambda to proton pion, using a data sample corresponding to an integrated luminosity of 1.9 inverse femtobarns. The product of the cross section times the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls faster than that of b mesons. The measured value of the cross section times the branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06 +/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are statistical and systematic, respectively.Comment: Submitted to Physics Letters

Search for new physics in events with opposite-sign leptons, jets, and missing transverse energy in pp collisions at sqrt(s) = 7 TeV

A search is presented for physics beyond the standard model (BSM) in final states with a pair of opposite-sign isolated leptons accompanied by jets and missing transverse energy. The search uses LHC data recorded at a center-of-mass energy sqrt(s) = 7 TeV with the CMS detector, corresponding to an integrated luminosity of approximately 5 inverse femtobarns. Two complementary search strategies are employed. The first probes models with a specific dilepton production mechanism that leads to a characteristic kinematic edge in the dilepton mass distribution. The second strategy probes models of dilepton production with heavy, colored objects that decay to final states including invisible particles, leading to very large hadronic activity and missing transverse energy. No evidence for an event yield in excess of the standard model expectations is found. Upper limits on the BSM contributions to the signal regions are deduced from the results, which are used to exclude a region of the parameter space of the constrained minimal supersymmetric extension of the standard model. Additional information related to detector efficiencies and response is provided to allow testing specific models of BSM physics not considered in this paper.Comment: Replaced with published version. Added journal reference and DO

Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV

Isolated photon production is measured in proton-proton and lead-lead collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80 GeV with the CMS detector at the LHC. The measured ET spectra are found to be in good agreement with next-to-leading-order perturbative QCD predictions. The ratio of PbPb to pp isolated photon ET-differential yields, scaled by the number of incoherent nucleon-nucleon collisions, is consistent with unity for all PbPb reaction centralities.Comment: Submitted to Physics Letters

Rationale and design of a prospective substudy of clinical endpoint adjudication processes within an investigator-reported randomised controlled trial in patients with coronary artery disease: the GLOBAL LEADERS Adjudication Sub-StudY (GLASSY)

pragmatic and superiority randomised controlled trial designed to challenge the current treatment paradigm of dual antiplatelet therapy (DAPT) for 12 months followed by aspirin monotherapy among patients undergoing percutaneous coronary intervention. By design, all study endpoints are investigator reported (IR) and not subject to formal adjudication by an independent Clinical Event Committee (CEC), which may introduce detection, reporting or ascertainment bias. Methods and analysis We designed the GLOBAL LEADERS Adjudication Sub-StudY (GLASSY) to prospectively implement, in a large sample of patients enrolled within the GLOBAL LEADERS trial (7585 of 15 991, 47.5%), an independent adjudication process of reported and unreported potential endpoints, using standardised CEC procedures, in order to assess whether 23-month ticagrelor monotherapy (90mg twice daily) after 1-month DAPT is non-inferior to a standard regimen of DAPT for 12 months followed by aspirin monotherapy for the primary efficacy endpoint of death, nonfatal myocardial infarction, non-fatal stroke or urgent target vessel revascularisation and superior for the primary safety endpoint of type 3 or 5 bleeding according to the Bleeding Academic Research Consortium criteria. This study will comprehensively assess the comparative safety and efficacy of the two tested antithrombotic strategies on CEC-adjudicated ischaemic and bleeding endpoints and will provide insights into the role of a standardised CEC adjudication process on the interpretation of study findings by quantifying the level of concordance between IR-reported and CEC-adjudicated events. Ethics and dissemination GLASSY has been approved by local ethics committee of all study sites and/or by the central ethics committee for the country depending on country-specific regulations. In all cases, they deemed that it was not neces