5 research outputs found
Perturbed nonlinear models from Noncommutativity
By means of the Ehrenfest's Theorem inside the context of a noncommutative
Quantum Mechanics it is obtained the Newton's Second Law in noncommutative
space. Considering discrete systems with infinite degrees of freedom whose
dynamical evolutions are governed by the noncommutative Newton's Second Law we
have constructed some alternative noncommutative generalizations of
two-dimensional field theories.Comment: 6 pages. v2 minor changes added and references adde
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
Entropy and holography in theories of gravitation.
Estudamos a entropia em várias situações na gravidade, verificando se seu comportamento Ă© holográfico, obedecendo Ă lei de área de Bekenstein. Inicialmente, usando o mĂ©todo da \"parede de tijolos\", calculamos, em diversos casos, a entropia estatĂstica de um campo escalar num fundo nĂŁo trivial. Tal fundo Ă© gerado por buracos negros de 4 ou 5 dimensões com cargas. A fĂłrmula da entropia de Bekenstein Ă© geralmente satisfeita, mas algumas correções sĂŁo discutidas no caso pentadimensional. Este mĂ©todo Ă© tambĂ©m aplicado para soluções tipo buracos negros na gravidade de Lovelock. Resulta que o mĂ©todo de \"parede de tijolos\", apesar de correto para a teoria de Einstein-Hilbert, pode nĂŁo ser válido em geral, o que tambĂ©m acontece com a lei área. Algumas propriedades concernentes Ă teoria de cordas, especialmente a tecnologia das D-branas, sĂŁo revistas naqueles aspectos necessários para este trabalho. TambĂ©m estudamos e calculamos o limite superior da entropia para a gravidade de Lovelock. Finalmente, verificamos a validade do princĂpio holográfico num universo de (4 + n) dimensões numa fase inflacionária assimĂ©trica.We study the entropy for various situations in gravity, checking whether its behavior is holographic, obeying Bekensteins area law. First, using the brick wall method, we compute the statistical entropy of a scalar field in a nontrivial background in different cases. Such a background is generated by four and five dimensional black holes with charges. The Bekenstein entropy formula is generally obeyed, but corrections are discussed in the latter case. This method is applied also to the black hole solutions of the Lovelock gravity. It turns out that the brickwall method, through correct for the Einstein-Hilbert theory, may fail in general. The same happens to the area law. Some properties concerning string theory, especially the D-branes technology, are reviewed while necessary to this work. Furthermore, we study and compute the upper limit of the entropy for the Lovelock gravity. Finally, we check the validity of the holographic principle in a (4+n) dimensional universe in an asymmetric inflationary phase
Entropy and holography in theories of gravitation.
Estudamos a entropia em várias situações na gravidade, verificando se seu comportamento Ă© holográfico, obedecendo Ă lei de área de Bekenstein. Inicialmente, usando o mĂ©todo da \"parede de tijolos\", calculamos, em diversos casos, a entropia estatĂstica de um campo escalar num fundo nĂŁo trivial. Tal fundo Ă© gerado por buracos negros de 4 ou 5 dimensões com cargas. A fĂłrmula da entropia de Bekenstein Ă© geralmente satisfeita, mas algumas correções sĂŁo discutidas no caso pentadimensional. Este mĂ©todo Ă© tambĂ©m aplicado para soluções tipo buracos negros na gravidade de Lovelock. Resulta que o mĂ©todo de \"parede de tijolos\", apesar de correto para a teoria de Einstein-Hilbert, pode nĂŁo ser válido em geral, o que tambĂ©m acontece com a lei área. Algumas propriedades concernentes Ă teoria de cordas, especialmente a tecnologia das D-branas, sĂŁo revistas naqueles aspectos necessários para este trabalho. TambĂ©m estudamos e calculamos o limite superior da entropia para a gravidade de Lovelock. Finalmente, verificamos a validade do princĂpio holográfico num universo de (4 + n) dimensões numa fase inflacionária assimĂ©trica.We study the entropy for various situations in gravity, checking whether its behavior is holographic, obeying Bekensteins area law. First, using the brick wall method, we compute the statistical entropy of a scalar field in a nontrivial background in different cases. Such a background is generated by four and five dimensional black holes with charges. The Bekenstein entropy formula is generally obeyed, but corrections are discussed in the latter case. This method is applied also to the black hole solutions of the Lovelock gravity. It turns out that the brickwall method, through correct for the Einstein-Hilbert theory, may fail in general. The same happens to the area law. Some properties concerning string theory, especially the D-branes technology, are reviewed while necessary to this work. Furthermore, we study and compute the upper limit of the entropy for the Lovelock gravity. Finally, we check the validity of the holographic principle in a (4+n) dimensional universe in an asymmetric inflationary phase