30 research outputs found
Spin-Rotation Symmetry Breaking in the Superconducting State of CuxBi2Se3
Spontaneous symmetry breaking is an important concept for understanding
physics ranging from the elementary particles to states of matter. For example,
the superconducting state breaks global gauge symmetry, and unconventional
superconductors can break additional symmetries. In particular, spin rotational
symmetry is expected to be broken in spin-triplet superconductors. However,
experimental evidence for such symmetry breaking has not been conclusively
obtained so far in any candidate compounds. Here, by 77Se nuclear magnetic
resonance measurements, we show that spin rotation symmetry is spontaneously
broken in the hexagonal plane of the electron-doped topological insulator
Cu0.3Bi2Se3 below the superconducting transition temperature Tc=3.4 K. Our
results not only establish spin-triplet superconductivity in this compound, but
may also serve to lay a foundation for the research of topological
superconductivity
Strange Attractors in Dissipative Nambu Mechanics : Classical and Quantum Aspects
We extend the framework of Nambu-Hamiltonian Mechanics to include dissipation
in phase space. We demonstrate that it accommodates the phase space
dynamics of low dimensional dissipative systems such as the much studied Lorenz
and R\"{o}ssler Strange attractors, as well as the more recent constructions of
Chen and Leipnik-Newton. The rotational, volume preserving part of the flow
preserves in time a family of two intersecting surfaces, the so called {\em
Nambu Hamiltonians}. They foliate the entire phase space and are, in turn,
deformed in time by Dissipation which represents their irrotational part of the
flow. It is given by the gradient of a scalar function and is responsible for
the emergence of the Strange Attractors.
Based on our recent work on Quantum Nambu Mechanics, we provide an explicit
quantization of the Lorenz attractor through the introduction of
Non-commutative phase space coordinates as Hermitian matrices in
. They satisfy the commutation relations induced by one of the two
Nambu Hamiltonians, the second one generating a unique time evolution.
Dissipation is incorporated quantum mechanically in a self-consistent way
having the correct classical limit without the introduction of external degrees
of freedom. Due to its volume phase space contraction it violates the quantum
commutation relations. We demonstrate that the Heisenberg-Nambu evolution
equations for the Quantum Lorenz system give rise to an attracting ellipsoid in
the dimensional phase space.Comment: 35 pages, 4 figures, LaTe
Evaluation of the activity of CYP2C19 in Gujrati and Marwadi subjects living in Mumbai (Bombay)
BACKGROUND: Inherited differences in the metabolism and disposition of drugs, and genetic polymorphisms in the targets of drug therapy (e.g., receptors), can greatly influence efficacy and toxicity of medications. Marked interethnic differences in CYP2C19 (a member of the cytochrome P-450 enzyme superfamily catalyzing phase I drug metabolism) which affects the metabolism of a number of clinically important drugs have been documented. The present study evaluated the activity of CYP2C19 in normal, healthy Gujrati and Marwadi subjects by phenotyping (a western Indian population). METHODS: All subjects received 20 mg of omeprazole, which was followed by blood collection at 3 hrs to estimate the metabolic ratio of omeprazole to 5-hydroxyomeprazole. The analysis was done by HPLC. RESULTS: It was seen that 10.36% of this population were poor metabolizers(PM) whereas 89.63% were extensive metabolizers(EM). CONCLUSION: A genotyping evaluation would better help in identifying population specific genotypes and thus help individualize drug therapy
Non-perturbative corrections to the one-loop free energy induced by a massive scalar field on a stationary slowly varying in space gravitational background
Conservation Genetics of a Critically Endangered Limpet Genus and Rediscovery of an Extinct Species
A third of all known freshwater mollusk extinctions worldwide have occurred within a single medium-sized American drainage. The Mobile River Basin (MRB) of Alabama, a global hotspot of temperate freshwater biodiversity, was intensively industrialized during the 20(th) century, driving 47 of its 139 endemic mollusk species to extinction. These include the ancylinid limpet Rhodacmea filosa, currently classified as extinct (IUCN Red List), a member of a critically endangered southeastern North American genus reduced to a single known extant population (of R. elatior) in the MRB.We document here the tripling of known extant populations of this North American limpet genus with the rediscovery of enduring Rhodacmea filosa in a MRB tributary and of R. elatior in its type locality: the Green River, Kentucky, an Ohio River Basin (ORB) tributary. Rhodacmea species are diagnosed using untested conchological traits and we reassessed their systematic and conservation status across both basins using morphometric and genetic characters. Our data corroborated the taxonomic validity of Rhodacmea filosa and we inferred a within-MRB cladogenic origin from a common ancestor bearing the R. elatior shell phenotype. The geographically-isolated MRB and ORB R. elatior populations formed a cryptic species complex: although overlapping morphometrically, they exhibited a pronounced phylogenetic disjunction that greatly exceeded that of within-MRB R. elatior and R. filosa sister species.Rhodacmea filosa, the type species of the genus, is not extinct. It persists in a Coosa River tributary and morphometric and phylogenetic analyses confirm its taxonomic validity. All three surviving populations of the genus Rhodacmea merit specific status. They collectively contain all known survivors of a phylogenetically highly distinctive North American endemic genus and therefore represent a concentrated fraction of continental freshwater gastropod biodiversity. We recommend the establishment of a proactive targeted conservation program that may include their captive propagation and reintroduction
Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.
Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability
A introdução das Ciências Naturais no Pará por meio das instituições de ensino
The objective of this research is to analyze the process of introduction of science in Pará, through the schools, and the conditions that allowed this process. We resumed the Pombal reforms of the second half of the eighteenth century, which marked the introduction of the Modern Scientific Rationality in Portuguese Kingdom, where the Para was Cologne. They expelled the Jesuits by inserting a gap in education, which began to be filled with the creation of the College of Nobles, Reform at the University of Coimbra and implementation of Régias classes. At that stage the natural sciences were introduced only in the metropolis, while in Pará created classes that kept the dominance of Letters and Humanities. The Marquis of Pombal's reforms have made the most favorable educational environment paraense receptivity of Natural Sciences, mainly because of the nationalization of education. This became incisive from the second half of the 1830s Rulers of Pará suggested the introduction of scientific disciplines and educational models in effect in countries like France, which was a diffuser center of modernity. This began to be realized with the creation of Liceu Paraense in 1841, which was intended to provide secondary education. Ten years later, in 1851, he implanted the first time physics and chemistry, which was repeated twice more, in 1868 and 1873. In the first insertion Botany was also present, while in the latter, the Natural History. In 1871, the initial phase of the Belle Époque, a time when the entry of Modernity in Para was accelerating, Physics and Chemistry were continued in Escola Normal do Pará, created this year in order to train teachers to work in primary education, but only until 1872, when they were taken out of this institution. In 1890 they returned with more expressiveness, being represented by six Sciences. In primary education, the natural sciences also consisted, from 1870, motivating teachers in that sector the coursing Physics and Chemistry in the Escola Normal and Liceu Paraense. Thus, educational institutions were instrumental in the introduction of science in Pará, conditioned by the social context, first of Pombal reforms, culminating in the nationalization of education, and Belle-Époque, with the acceleration of Modernity entry in Pará. scientific presence in the curricula was marked by discontinuities in the initial phase, since the reception of the modernizing process, the local culture, had not yet made the learning of science is an imperative need. This began to happen from 1890 when the Science began to widen in school curricula.O objetivo desta pesquisa é analisar o processo de introdução das Ciências no Pará, por meio das escolas, e as condições que possibilitaram esse processo. Retomamos as Reformas Pombalinas da segunda metade do século XVIII, que marcaram a introdução da Racionalidade Científica Moderna no Reino Português, onde o Pará era Colônia. Expulsaram os Jesuítas, inserindo uma lacuna na educação, que começou a ser preenchida com a criação do Colégio dos Nobres, da Reforma na Universidade de Coimbra e implantação de Aulas Régias. Nessa fase as Ciências Naturais foram introduzidas somente na Metrópole, enquanto que no Pará criaram Aulas que mantiveram o predomínio das Letras e Humanidades. As Reformas do Marquês de Pombal tornaram o ambiente educacional paraense mais favorável a receptividade das Ciências da Natureza, principalmente por causa da estatização da educação. Esta se tornou incisiva a partir da segunda metade da década de 1830. Governantes do Pará sugeriram a introdução de disciplinas científicas e modelos educacionais que vigoravam em países como a França, que era um centro difusor da modernidade. Isso começou a se concretizar com a criação do Liceu Paraense em 1841, que tinha o propósito de proporcionar o ensino secundário. Dez anos depois, em 1851, ele implantou pela primeira vez a Física e a Química, o que se repetiu por mais duas vezes, em 1868 e 1873. Na primeira inserção a Botânica também esteve presente, enquanto que na última, a História Natural. Em 1871, fase inicial da Belle-Époque, momento em que a entrada da Modernidade no Pará estava acelerando, Física e Química tiveram continuidade na Escola Normal do Pará, criada nesse ano, com o fim de formar professores para atuarem na instrução primária, mas somente até 1872, quando foram retiradas desta instituição. Em 1890 retornaram com mais expressividade, sendo representada por seis Ciências. Na instrução primária, as Ciências da Natureza também constaram, a partir de 1870, motivando professores desse ramo a cursarem Física e Química na Escola Normal e no Liceu Paraense. Com isso, as instituições de ensino foram fundamentais na introdução das ciências no Pará, condicionadas pelo contexto social, inicialmente das Reformas Pombalinas, que culminou na estatização da educação, e da Belle-Époque, com a aceleração da entrada da Modernidade no Pará. A presença científica nos currículos foi marcada por descontinuidades, na fase inicial, visto que a recepção do processo modernizador, pela cultura local, ainda não tinha tornado a aprendizagem das ciências uma necessidade imperativa. Isso começou a acontecer a partir de 1890, quando as Ciências passaram a se ampliar nos currículos escolares