Upper bounds on the superfluid stiffness and superconducting TcT_c: Applications to twisted-bilayer graphene and ultra-cold Fermi gases

Understanding the material parameters that control the superconducting transition temperature $T_c$ is a problem of fundamental importance. In many novel superconductors, phase fluctuations determine $T_c$, rather than the collapse of the pairing amplitude. We derive rigorous upper bounds on the superfluid phase stiffness for multi-band systems, valid in any dimension. This in turn leads to an upper bound on $T_c$ in two dimensions (2D), which holds irrespective of pairing mechanism, interaction strength, or order-parameter symmetry. Our bound is particularly useful for the strongly correlated regime of low-density and narrow-band systems, where mean field theory fails. For a simple parabolic band in 2D with Fermi energy $E_F$, we find that $k_BT_c \leq E_F/8$, an exact result that has direct implications for the 2D BCS-BEC crossover in ultra-cold Fermi gases. Applying our multi-band bound to magic-angle twisted bilayer graphene (MA-TBG), we find that band structure results constrain the maximum $T_c$ to be close to the experimentally observed value. Finally, we discuss the question of deriving rigorous upper bounds on $T_c$ in 3D.Comment: Revised figures, includes estimates from another model of MA-TBG, published version of manuscrip

Natural Variation in Diauxic Shift between Patagonian Saccharomyces eubayanus Strains

The study of natural variation can untap novel alleles with immense value for biotechnological applications. Saccharomyces eubayanus Patagonian isolates exhibit differences in the diauxic shift between glucose and maltose, representing a suitable model to study their natural genetic variation for novel strains for brewing. However, little is known about the genetic variants and chromatin regulators responsible for these differences. Here, we show how genome-wide chromatin accessibility and gene expression differences underlie distinct diauxic shift profiles in S. eubayanus. We identified two strains with a rapid diauxic shift between glucose and maltose (CL467.1 and CBS12357) and one strain with a remarkably low fermentation efficiency and longer lag phase during diauxic shift (QC18). This is associated in the QC18 strain with lower transcriptional activity and chromatin accessibility of specific genes of maltose metabolism and higher expression levels of glucose transporters. These differences are governed by the HAP complex, which differentially regulates gene expression depending on the genetic background. We found in the QC18 strain a contrasting phenotype to those phenotypes described in S. cerevisiae, where hap4D, hap5D, and cin5D knockouts significantly improved the QC18 growth rate in the glucose-maltose shift. The most profound effects were found between CIN5 allelic variants, suggesting that Cin5p could strongly activate a repressor of the diauxic shift in the QC18 strain but not necessarily in the other strains. The differences between strains could originate from the tree host from which the strains were obtained, which might determine the sugar source preference and the brewing potential of the strain.Fil: Molinet, Jennifer. Universidad de Santiago de Chile; ChileFil: Eizaguirre, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales; ArgentinaFil: Quintrel, Pablo. Universidad de Santiago de Chile; ChileFil: Bellora, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Instituto de Tecnologías Nucleares para la Salud; ArgentinaFil: Villarroel, Carlos A.. Universidad de Talca; ChileFil: Villarreal, Pablo. Universidad de Santiago de Chile; ChileFil: Benavides Parra, José. Universidad de Santiago de Chile; ChileFil: Nespolo, Roberto F.. Universidad Austral de Chile; ChileFil: Libkind Frati, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales; ArgentinaFil: Cubillos, Francisco A.. Universidad de Santiago de Chile; Chil

Software y aplicaciones en computación de altas prestaciones para el contexto de la UNdeC

En la actualidad, para abordar problemas de mayor tamaño y complejidad estudios de ciencia básica y aplicada utilizan Computación de Altas Prestaciones (HPC - High Performance Computing). El HPC permite mejorar la capacidad, velocidad y precisión en el procesamiento de datos. Con el proyecto que da origen a este trabajo se propone abordar seis estudios desde la perspectiva del HPC, para explorar los aspectos centrales del paralelismo aplicado desde las Ciencias de la Computación en otras disciplinas. Algunas de los estudios que se abordan ya vienen desarrollándose en la Universidad Nacional de Chilecito, otros se inician a partir de cooperaciones con otras instituciones o para formalizar trabajos finales de postgrado. En todos los casos, el HPC será abordado a través de un proceso metodológico organizado para: Consolidar una infraestructura de experimentación, desarrollo y producción de soluciones a problemas de HPC. Desarrollar las capacidades científico-tecnológicas del equipo. Fomentar la vinculación y transferencia con los sectores académico, social y productivo. Cada problema abordado reúne entre sus integrantes, investigadores especialistas en la disciplina del estudio, investigadores de Ciencias de la Computación y estudiantes en sus últimos años de formación de grado. Se espera consolidar a corto plazo un grupo de investigación, desarrollo y transferencia que generará oportunidades de formación de recursos humanos, proveerá de servicios a la comunidad en el área de estudio y potenciará los vínculos de cooperación con otras instituciones.Eje: Procesamiento Distribuido y Paralelo.Red de Universidades con Carreras en Informátic

Tecnología HPC como motor de ciencia de la UNdeC

En la actualidad, para abordar problemas de mayor tamaño y complejidad, los estudios de ciencia básica y aplicada utilizan Computación de Altas Prestaciones (HPC - High Performance Computing). El HPC permite mejorar la capacidad, velocidad y precisión en el procesamiento de datos. Con el proyecto que da origen a este trabajo se abordan seis estudios desde la perspectiva del HPC, para explorar los aspectos centrales del paralelismo aplicado desde las Ciencias de la Computación en otras disciplinas. Algunos de estos estudios se realizan exclusivamente en la Universidad Nacional de Chilecito, mientras que otros son en cooperación con otras instituciones nacionales y extranjeras. Entre estos, tres formalizan trabajos finales de postgrado. En todos los casos, el HPC será abordado a través de un proceso metodológico organizado para: ● Consolidar una infraestructura de experimentación, desarrollo y producción de soluciones a problemas de HPC ● Desarrollar las capacidades científico-tecnológicas del equipo ● Fomentar la vinculación y transferencia con los sectores académico, social y productivo Cada problema abordado reúne entre sus integrantes investigadores especialistas en la disciplina del estudio, investigadores de Ciencias de la Computación y estudiantes en sus últimos años de formación de grado. Con esto, se está consolidando un grupo de investigación, desarrollo y transferencia que generará oportunidades de formación de recursos humanos, proveerá de servicios a la comunidad en el área de estudio y potenciará los vínculos de cooperación con otras instituciones.Eje: Procesamiento distribuido y paralelo.Red de Universidades con Carreras en Informátic

Tecnología HPC en la UNdeC como motor de ciencia

En la actualidad, para abordar problemas de mayor tamaño y complejidad, los estudios de ciencia básica y aplicada utilizan Computación de Altas Prestaciones (HPC - High Performance Computing). El HPC permite mejorar la capacidad, velocidad y precisión en el procesamiento de datos. Con el proyecto que da origen a este trabajo se abordan seis estudios desde la perspectiva del HPC, para explorar los aspectos centrales del paralelismo aplicado desde las Ciencias de la Computación en otras disciplinas. Algunos de estos estudios se realizan exclusivamente en la Universidad Nacional de Chilecito, mientras que otros son en cooperación con otras instituciones nacionales y extranjeras. Entre estos, tres formalizan trabajos finales de postgrado. En todos los casos, el HPC es abordado a través de un proceso metodológico organizado para: - Consolidar una infraestructura de experimentación, desarrollo y producción de soluciones a problemas de HPC - Desarrollar las capacidades científico-tecnológicas del equipo - Fomentar la vinculación y transferencia con los sectores académico, social y productivo Cada problema abordado reúne entre sus integrantes investigadores especialistas en la disciplina del estudio, investigadores de Ciencias de la Computación y estudiantes en sus últimos años de formación de grado. Con esto, se está consolidando un grupo de investigación, desarrollo y transferencia que generará oportunidades de formación de recursos humanos, proveerá de servicios a la comunidad en el área de estudio y potenciará los vínculos de cooperación con otras instituciones.Red de Universidades con Carreras en Informátic

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Immunocompromised patients with acute respiratory distress syndrome: Secondary analysis of the LUNG SAFE database

Background: The aim of this study was to describe data on epidemiology, ventilatory management, and outcome of acute respiratory distress syndrome (ARDS) in immunocompromised patients. Methods: We performed a post hoc analysis on the cohort of immunocompromised patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE) study. The LUNG SAFE study was an international, prospective study including hypoxemic patients in 459 ICUs from 50 countries across 5 continents. Results: Of 2813 patients with ARDS, 584 (20.8%) were immunocompromised, 38.9% of whom had an unspecified cause. Pneumonia, nonpulmonary sepsis, and noncardiogenic shock were their most common risk factors for ARDS. Hospital mortality was higher in immunocompromised than in immunocompetent patients (52.4% vs 36.2%; p &lt; 0.0001), despite similar severity of ARDS. Decisions regarding limiting life-sustaining measures were significantly more frequent in immunocompromised patients (27.1% vs 18.6%; p &lt; 0.0001). Use of noninvasive ventilation (NIV) as first-line treatment was higher in immunocompromised patients (20.9% vs 15.9%; p = 0.0048), and immunodeficiency remained independently associated with the use of NIV after adjustment for confounders. Forty-eight percent of the patients treated with NIV were intubated, and their mortality was not different from that of the patients invasively ventilated ab initio. Conclusions: Immunosuppression is frequent in patients with ARDS, and infections are the main risk factors for ARDS in these immunocompromised patients. Their management differs from that of immunocompetent patients, particularly the greater use of NIV as first-line ventilation strategy. Compared with immunocompetent subjects, they have higher mortality regardless of ARDS severity as well as a higher frequency of limitation of life-sustaining measures. Nonetheless, nearly half of these patients survive to hospital discharge. Trial registration: ClinicalTrials.gov, NCT02010073. Registered on 12 December 2013

MACVIA Clinical Decision Algorithm in Allergic Rhinitis in adolescents and adults

International audienceThe selection of pharmacotherapy for patients with allergic rhinitis depends on several factors, including age, prominent symptoms, symptom severity, control of allergic rhinitis, patient preferences and cost. Allergen exposure and resulting symptoms vary and treatment adjustment is required. Clinical decision support systems (CDSS) may be beneficial for the assessment of disease control. Clinical decision support systems should be based on the best evidence and algorithms to aid patients and health care professionals to jointly determine the treatment and its step-up or step-down strategy depending on AR control. MACVIA-LR (Fighting chronic diseases for active and healthy ageing) one of the reference sites of the European Innovation Partnership on Active and Healthy Ageing, has initiated an allergy sentinel network (MASK: MACVIA-ARIA Sentinel networK). A clinical decision support system is currently being developed to optimize allergic rhinitis control. An algorithm developed by consensus is presented in this paper. This algorithm should be confirmed by appropriate trials