564 research outputs found
Comparing the performance of two structural indicators for different water models while seeking for connections between structure and dynamics in the glassy regime
In this work, we compare the performance of two structural indicators based on the degree of translational order up to the second coordination shell in three water models: SPC/E, TIP4P/2005, and TIP5P. Beyond directly contrasting their distributions for different temperatures to evidence their usefulness in estimating the fraction of structured and unstructured molecules and, when possible, their classification capability, we also correlate them with an indirect measure of structural constraint: the dynamic propensity. Furthermore, this procedure enables us to show the existence of evident correlations between structural and dynamical information. More specifically, we find that locally structured molecules display a preference for low dynamic propensity values and, more conspicuously, that locally unstructured molecules are extremely subject to high dynamic propensity. This result is particularly relevant for the supercooled regime where the establishment of firm links between the structure and dynamics has remained rather elusive since the occurrence of dynamics that vary in orders of magnitude upon supercooling usually contrast with barely noticeable overall structural changes.Fil: Verde, Alejandro Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Montes de Oca, Joan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Accordino, Sebastián R.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Alarcón, Laureano M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Appignanesi, Gustavo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin
Dark matter in Inert Doublet Model with one scalar singlet and gauge symmetry
We study Dark Matter (DM) abundance in the framework of the extension of the
Standard Model (SM) with an additional gauge symmetry. One complex
singlet is included to break the gauge symmetry, meanwhile one of the
doublets is considered inert to introduce a DM candidate. The stability of the
DM candidate is analyzed with a continuous gauge symmetry as well as
discrete symmetry. We find allowed regions for the free model parameters
which are in agreement with the most up-to-date experimental results reported
by CMS and ATLAS collaborations, the upper limit on WIMP-nucleon cross section
imposed by XENON1T collaboration and the upper limit on the production
cross-section of a gauge boson times the branching ratio of the
boson decaying into . We also obtain allowed regions
for the DM candidate mass from the relic density reported by the PLANCK
collaboration including light, intermediate and heavy masses; depending mainly
on two parameters of the scalar potential, and
. We find that trough
production, it may only be possible for a
future hadron-hadron Circular Collider (FCC-hh) to be able to detect a DM
candidate within the range of masses 10-60 GeV.Comment: Accepted version to be published in EPJC, typos corrected, cites
adde
Renormalized Wick expansion for a modified PQCD
The renormalization scheme for the Wick expansion of a modified version of
the perturbative QCD introduced in previous works is discussed. Massless QCD is
considered, by implementing the usual multiplicative scaling of the gluon and
quark wave functions and vertices. However, also massive quark and gluon
counter-terms are allowed in this mass less theory since the condensates are
expected to generate masses. A natural set of expansion parameters of the
physical quantities is introduced: the coupling itself and to masses and
associated to quarks and gluons respectively. This procedure allows to
implement a dimensional transmutation effect through these new mass scales. A
general expression for the new generating functional in terms of the mass
parameters and is obtained in terms of integrals over arbitrary but
constant gluon or quark fields in each case. Further, the one loop potential,
is evaluated in more detail in the case when only the quark condensate is
retained. This lowest order result again indicates the dynamical generation of
quark condensates in the vacuum.Comment: 13 pages, one figur
Tuberculosis and airflow obstruction: evidence from the PLATINO study in Latin America
The aim of the present study was to evaluate the association between history of tuberculosis and airflow obstruction.A population-based, multicentre study was carried out and included 5,571 subjects aged >= 40 yrs living in one of five Latin American metropolitan areas: São Paulo (Brazil); Montevideo (Uruguay); Mexico City (Mexico); Santiago (Chile); and Caracas (Venezuela). Subjects performed pre- and post-bronchodilator spirometry and were asked whether they had ever been diagnosed with tuberculosis by a physician.The overall prevalence of airflow obstruction (forced expiratory volume in one second/forced vital capacity post-bronchodilator < 0.7) was 30.7% among those with a history of tuberculosis, compared with 13.9% among those without a history. Males with a medical history of tuberculosis were 4.1 times more likely to present airflow obstruction than those without such a diagnosis. This remained unchanged after adjustment for confounding by age, sex, schooling, ethnicity, smoking, exposure to dust and smoke, respiratory morbidity in childhood and current morbidity. Among females, the unadjusted and adjusted odds ratios were 2.3 and 1.7, respectively.In conclusion, history of tuberculosis is associated with airflow obstruction in Latin American middle-aged and older adults.Univ Fed Pelotas, BR-96020220 Pelotas, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilNatl Inst Resp Dis, Mexico City, DF, MexicoUniv Republica, Montevideo, UruguayCatholic Univ Chile, Santiago, ChileCent Univ Venezuela, Caracas, VenezuelaUniversidade Federal de São Paulo, São Paulo, BrazilWeb of Scienc
Efectos del cambio climático sobre estados tempranos de Quercus ariifolia (Fagaceae), un encino endémico de bosques estacionalmente secos de México
Background and Aims: Tree recruitment in seasonally dry forests occurs during the rainy season. However, higher temperatures and reduced rainfalls are expected in these ecosystems because of climate change. These changes could induce drought conditions during the rainy season and affect tree recruitment. Plants subjected to thermal or water stress often display morphological and physiological shifts addressed to prioritize their survival. If recently emerged tree seedlings display these responses, this could improve their development during the rainy season and increase their survival chances. Our aim was to test whether recently emerged oak seedlings display these responses.Methods: We performed a field experiment with Quercus ariifolia, an oak species endemic to seasonally dry forests of central Mexico. At the beginning of the rainy season (September 2016), we sowed acorns of this species in control plots under the current climate and plots in which climate change was simulated by increasing temperature and reducing rainfall (CCS plots). Seedling emergence and survival were monitored every seven days during the rainy season (until January 2017). At the end of the experiment, we measured several functional traits on surviving seedlings and compared them between controls and CCS plots.Key results: Higher temperature and lower rainfall generated water shortage conditions in CCS plots. This did not affect emergence of seedlings but reduced their survival. Seedlings that survived in CCS plots displayed shifts in their functional traits, which matched with those of plants subjected to thermal and water stress.Conclusions: Our results suggest that climate change can increase the extinction risk of Q. ariifolia in seasonally dry forest of Mexico by reducing the survival of its offspring. Nevertheless, the results also suggest that seedlings developed under climate change conditions can display functional shifts that could confer them tolerance to increased drought.Antecedentes y Objetivos: El reclutamiento de árboles en bosques estacionalmente secos ocurre en la temporada de lluvias. Sin embargo, en estos ecosistemas se esperan mayores temperaturas y menores precipitaciones debido al cambio climático. Estos cambios pueden inducir condiciones de sequía durante la temporada de lluvias y afectar el reclutamiento. Las plantas sometidas a estrés térmico e hídrico usualmente muestran cambios morfológicos y fisiológicos dirigidos a priorizar su supervivencia. Si plántulas recientemente emergidas muestran estas respuestas, esto pudiera mejorar su desarrollo durante la temporada de lluvias y aumentar sus posibilidades de supervivencia. Nuestro objetivo fue establecer si plántulas de encino recién emergidas muestran estas respuestas.Métodos: Realizamos un experimento de campo con Quercus ariifolia, un encino endémico de bosques estacionalmente secos del centro de México. Al comienzo de la temporada de lluvias (septiembre 2016) sembramos bellotas de esta especie en parcelas control bajo el clima actual, y parcelas donde aumentamos la temperatura y redujimos la precipitación (parcelas CCS). La emergencia y la supervivencia de plántulas se registró cada siete días durante la temporada de lluvias (hasta enero 2017). Al final del experimento, medimos varios rasgos funcionales en las plántulas sobrevivientes y los comparamos entre controles y parcelas CCS.Resultados clave: La mayor temperatura y la menor precipitación generaron condiciones de sequía en las parcelas CCS. Esto no afectó la emergencia de plántulas, pero redujo su supervivencia. Las plántulas sobrevivientes en las parcelas CCS mostraron cambios en sus rasgos funcionales, que coincidían con los observados en plantas sometidas a estrés térmico y/o hídrico.Conclusiones: Nuestros resultados sugieren que el cambio climático puede aumentar el riesgo de extinción de Q. ariifolia en bosques estacionalmente secos de México al reducir la supervivencia de plántulas. Sin embargo, los resultados también sugieren que las plántulas desarrolladas en condiciones de cambio climático pueden mostrar alteraciones funcionales que pudieran conferirles tolerancia al aumento de la sequía
- …