55 research outputs found
Extended phase space quantization of a black hole interior model in Loop Quantum Cosmology
Considerable attention has been paid to the study of the quantum geometry of
nonrotating black holes within the framework of Loop Quantum Cosmology. This
interest has been reinvigorated since the introduction of a novel effective
model by Ashtekar, Olmedo and Singh. Despite recent advances in its foundation,
there are certain questions about its quantization that still remain open. Here
we complete this quantization taking as starting point an extended phase space
formalism suggested by several authors, including the proposers of the model.
Adopting a prescription that has proven succesful in Loop Quantum Cosmology, we
construct an operator representation of the Hamiltonian constraint. By
searching for solutions to this constraint operator in a sufficiently large set
of dual states, we show that it can be solved for a continuous range of the
black hole mass. This fact seems in favour of a conventional classical limit
(at least for large masses) and contrasts with recent works that advocate a
discrete spectrum. We present an algorithm that determines the solutions in
closed form. To build the corresponding physical Hilbert space and conclude the
quantization, we carry out an asymptotic analysis of those solutions, which
allows us to introduce a suitable inner product on them.Comment: 15 page
Transferencia de los resultados de Trabajos Fin de Grado y Máster a la docencia -TF-Transfer
Depto. de GeografíaFac. de Geografía e HistoriaFALSEsubmitte
Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study
Summary
Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally.
Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies
have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of
the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income
countries globally, and identified factors associated with mortality.
Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to
hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis,
exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a
minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical
status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary
intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause,
in-hospital mortality for all conditions combined and each condition individually, stratified by country income status.
We did a complete case analysis.
Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital
diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal
malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome
countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male.
Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3).
Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income
countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups).
Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome
countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries;
p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients
combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11],
p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20
[1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention
(ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety
checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed
(ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of
parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65
[0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality.
Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome,
middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will
be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger
than 5 years by 2030
The time-dependent mass of cosmological perturbations in loop quantum cosmology: Dapor-Liegener regularization
35 pags., 5 figs.In this work, we compute the time-dependent masses that govern the dynamics of scalar and tensor perturbations propagating on an effective flat, homogeneous, and isotropic background within the framework of loop quantum cosmology (LQC), regularized according to the procedure put forward by Dapor and Liegener. To do so, we follow the two main approaches that, in the field of LQC, lead to hyperbolic equations for the perturbations in the ultraviolet sector: the hybrid and dressed metric formalisms. This allows us to compare the masses resulting from both proposals and analyze their positivity in regimes of physical interest: the big bounce and the contracting de Sitter phase in the asymptotic past that is a defining feature of the model under consideration.This work has been supported by Project No. FIS2017-86497-C2-2-P of MICINN from Spain. A GarciaQuismondo acknowledges that the project that gave rise to these results received the support of a fellowship from ‘la Caixa’ Foundation (ID 100010434). The fellowship code is LCF/BQ/DR19/11740028. G Sanchez Perez acknowledges support of the Grant No. CSIC JAEINT19_EX_0632
Confirmed clinical case of chronic kidney disease of nontraditional causes in agricultural communities in Central America: a case definition for surveillance
ABSTRACT Over the last 20 years, many reports have described an excess of cases of chronic kidney disease (CKD) in the Pacific coastal area of Central America, mainly affecting male farmworkers and signaling a serious public health problem. Most of these cases are not associated with traditional risk factors for CKD, such as aging, diabetes mellitus, and hypertension. This CKD of nontraditional causes (CKDnT) might be linked to environmental and/or occupational exposure or working conditions, limited access to health services, and poverty. In response to a resolution approved by the Directing Council of the Pan American Health Organization (PAHO) in 2013, PAHO, the U.S. Centers for Disease Control and Prevention, and the Latin American Society of Nephrology and Hypertension (SLANH) organized a consultation process in order to expand knowledge on the epidemic of CKDnT and to develop appropriate surveillance instruments. The Clinical Working Group from SLANH was put in charge of finding a consensus definition of a confirmed clinical case of CKDnT. The resulting definition establishes mandatory criteria and exclusion criteria necessary for classifying a case of CKDnT. The definition includes a combination of universally accepted definitions of CKD and the main clinical manifestations of CKDnT. Based on the best available evidence, the Clinical Working Group also formulated general recommendations about clinical management that apply to any patient with CKDnT. Adhering to the definition of a confirmed clinical case of CKDnT and implementing it appropriately is expected to be a powerful instrument for understanding the prevalence of the epidemic, evaluating the results of interventions, and promoting appropriate advocacy and planning efforts
Evaluación de impacto del programa de formación docente en Bogotá
The article examines the impact of the Teacher Training Program carried out by the Secretariat of Education of Bogotá. The quantitative analysis shows that there is no direct relationship between teacher training and the most usual dependent variables (achievement, dropout, repetition). From a qualitative perspective, the trained teacher (called the actor), and his peer (called the censor), were asked about their perception of the instrument (the training) and the results obtained. In general, the evaluation of the program is very good, but there is a lack of institutional capacity to take advantage of the benefits of teacher training.El artículo examina el impacto del programa de formación de docentes llevado a cabo por la Secretaría de Educación de Bogotá. El análisis cuantitativo muestra que no hay una relación directa entre la formación de los docentes y las variables dependientes más usuales (logro, deserción, repitencia…). Y desde la perspectiva cualitativa, se le preguntó al docente formado (llamado el actor) y a su par (llamado el censor), por su percepción sobre el instrumento (la formación) y los resultados obtenidos. En general, la evaluación que se hace del programa es muy buena, pero se observa falta de capacidad institucional para aprovechar los beneficios de la formación docente
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