Estudio asintótico de las vibraciones de un cuerpo con una masa concentrada en una superficie

El problema que aquí consideramos es un modelo matemático sobre las vibraciones de un cuerpo que contienen en su interior una región de pequeño espesor O(ε) limitada por dos planos paralelos y en donde la densidad es de orden O(ε −m) con m > 1. Fuera de dicha región, denominada masa concentrada sobre una superficie, la densidad es de orden O(1). En [4] D. Gómez, M. Lobo, and E. Pérez. Sobre vibraciones de baja frecuencia de un cuerpo con una masa concentrada sobre una superficie, Actas del XIX CEDYA, Universidad Carlos III, 2006 describimos el comportamiento asintótico, cuando ε tiende a cero, de los valores propios de orden O(ε m−1) del problema espectral asociado, bajas frecuencias. Aquí, caracterizamos comportamientos límites de frecuencias propias de otros órdenes de magnitud más grandes, las denominadas altas o medias frecuencias

On correctors for spectral problems in the homogenization of Robin boundary conditions with very large parameters

We obtain estimates for convergence rates of the eigenelements (λ", u") for the Laplace operator in a domain ⊂ R3 periodically perforated along a plane γ = ∩ {x1 = 0}. The boundary conditions are of the Dirichlet type on ∂ and of the Robin type, involving a large parameter O(ε− ), on the boundary of the cavities. The small parameter ε denotes the period while the size of each cavity is O(ε ). Here we consider the most significant case where α = κ = 2

Unilateral problems for the p-Laplace operator in perforated media involving large parameters

We address homogenization problems for variational inequalities issue from unilateral con-straints for the p-Laplacian posed in perforated domains of Rn, with n 3 and p 2 [2; n]. " is a small parameter which measures the periodicity of the structure while a" " measures the size of the perforations. We impose constraints for solutions and their uxes (associated with the p-Laplacian) on the boundary of the perforations. These constraints imply that the solution is positive and that the ux is bounded from above by a negative, nonlinear monotonic function of the solution multiplied by a parameter " which may be very large, namely, " ! 1 as " ! 0. We rst consider the case where p < n and the domains periodically perforated by tiny balls and we obtain homogenized problems depending on the relations between the di erent parameters of the problem: p, n, ", a" and ". Critical relations for parameters are obtained which mark important changes in the behavior of the solutions. Correctors which provide improved convergence are also computed. Then, we extend the results for p = n and the case of non periodically distributed isoperimetric perforations. We make it clear that the averaged constants of the problem, the perimeter of the perforations appears for any shape.This work has been partially supported by MINECO:MTM2013-44883-P

Effectiveness of Fosfomycin for the Treatment of Multidrug-Resistant Escherichia coli Bacteremic Urinary Tract Infections

IMPORTANCE The consumption of broad-spectrum drugs has increased as a consequence of the spread of multidrug-resistant (MDR) Escherichia coli. Finding alternatives for these infections is critical, for which some neglected drugs may be an option. OBJECTIVE To determine whether fosfomycin is noninferior to ceftriaxone or meropenem in the targeted treatment of bacteremic urinary tract infections (bUTIs) due to MDR E coli. DESIGN, SETTING, AND PARTICIPANTS This multicenter, randomized, pragmatic, open clinical trial was conducted at 22 Spanish hospitals from June 2014 to December 2018. Eligible participants were adult patients with bacteremic urinary tract infections due to MDR E coli; 161 of 1578 screened patients were randomized and followed up for 60 days. Data were analyzed in May 2021. INTERVENTIONS Patients were randomized 1 to 1 to receive intravenous fosfomycin disodium at 4 g every 6 hours (70 participants) or a comparator (ceftriaxone or meropenem if resistant; 73 participants) with the option to switch to oral fosfomycin trometamol for the fosfomycin group or an active oral drug or pa renteral ertapenem for the comparator group after 4 days. MAIN OUTCOMES AND MEASURES The primary outcome was clinical and microbiological cure (CMC) 5 to 7 days after finalization of treatment; a noninferiority margin of 7% was considered. RESULTS Among 143 patients in the modified intention-to-treat population (median [IQR] age, 72 [62-81] years; 73 [51.0%] women), 48 of 70 patients (68.6%) treated with fosfomycin and 57 of 73 patients (78.1%) treated with comparators reached CMC (risk difference, -9.4 percentage points; 1-sided 95% CI, -21.5 to infinity percentage points; P = .10). While clinical or microbiological failure occurred among 10 patients (14.3%) treated with fosfomycin and 14 patients (19.7%) treated with comparators (risk difference, -5.4 percentage points; 1-sided 95% CI. -infinity to 4.9; percentage points; P = .19), an increased rate of adverse event-related discontinuations occurred with fosfomycin vs comparators (6 discontinuations [8.5%] vs 0 discontinuations; P = .006). In an exploratory analysis among a subset of 38 patients who underwent rectal colonization studies, patients treated with fosfomycin acquired a new ceftriaxone-resistant or meropenem-resistant gram-negative bacteria at a decreased rate compared with patients treated with comparators (0 of 21 patients vs 4 of 17 patients [23.5%]; 1-sided P = .01). CONCLUSIONS AND RELEVANCE This study found that fosfomycin did not demonstrate noninferiority to comparators as targeted treatment of bUTI from MDR E coli; this was due to an increased rate of adverse event-related discontinuations. This finding suggests that fosfomycin may be considered for selected patients with these infections

Informe final del escaneo de horizonte sobre futuras especies exóticas invasoras en España

73 p.La introducción de especies exóticas invasoras (EEI) es una de las principales causas de la pérdida de biodiversidad a nivel global, que provoca grandes costes socioeconómicos. Sin embargo, el número de nuevas introducciones continúa creciendo año tras año. Por lo tanto, urge identificar posibles futuras EEI con el objetivo de diseñar e implementar medidas que prevengan y mitiguen los efectos negativos de su introducción. Así, el objetivo de este estudio es prospectar qué especies exóticas no establecidas en España podrían llegar fácilmente en los próximos 10 años, establecerse y causar importantes impactos ecológicos. Para ello, se ha realizado un escaneo de horizonte, siguiendo la metodología establecida en trabajos previos, siendo el primero para el conjunto de las especies exóticas invasoras en España. Se añadieron en el análisis especies que no son autóctonas de España, incluyendo los archipiélagos de Canarias y Baleares, y que no están establecidas en España. Un total de 39 científicos, expertos en distintos grupos taxonómicos y ecosistemas, ha evaluado 933 especies. Con el objetivo de analizar el acuerdo entre las evaluaciones individuales de los expertos y su consistencia, se llevaron a cabo dos análisis de fiabilidad complementarios, cuyos resultados se discuten en este informe. Como resultado del escaneo, se obtuvo una lista priorizada de 105 especies (46 con riesgo muy alto y 59 con riesgo alto). La mayoría de estas especies (84,8%), sin embargo, no están incluidas actualmente en el Catálogo Español de Especies Exóticas Invasoras. Por lo tanto, se recomienda la realización de un análisis de riesgo más detallado de estas especies y, si se confirma el riesgo alto, la solicitud de su incorporación en dicho catálogo o en el Listado de especies alóctonas susceptibles de competir con las especies silvestres autóctonas, alterar su pureza genética o los equilibrios ecológicos. Del mismo modo, se propone la realización de escaneos de horizonte específicos para los archipiélagos de Canarias y Baleares, ya que muchas de las especies autóctonas de la Península no lo son de las islas y podrían tener un gran impacto si allí se introdujeran. Este informe también analiza la afinidad taxonómica (i.e. filo) y funcional (i.e. productor primario, depredador, omnívoro, herbívoro o filtrador) de las especies de la lista priorizada, su origen geográfico y las principales vías de introducción. Por último, discute los mecanismos de impacto de dichas especies.Ministerio de Ciencia e Innovació

Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure &lt; 100 mmHg (n = 1127), estimated glomerular filtration rate &lt; 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation