640 research outputs found
Coherent States Expectation Values as Semiclassical Trajectories
We study the time evolution of the expectation value of the anharmonic
oscillator coordinate in a coherent state as a toy model for understanding the
semiclassical solutions in quantum field theory. By using the deformation
quantization techniques, we show that the coherent state expectation value can
be expanded in powers of such that the zeroth-order term is a classical
solution while the first-order correction is given as a phase-space Laplacian
acting on the classical solution. This is then compared to the effective action
solution for the one-dimensional \f^4 perturbative quantum field theory. We
find an agreement up to the order \l\hbar, where \l is the coupling
constant, while at the order \l^2 \hbar there is a disagreement. Hence the
coherent state expectation values define an alternative semiclassical dynamics
to that of the effective action. The coherent state semiclassical trajectories
are exactly computable and they can coincide with the effective action
trajectories in the case of two-dimensional integrable field theories.Comment: 20 pages, no figure
On the Integrability of the Bukhvostov-Lipatov Model
The integrability of the Bukhvostov-Lipatov four-fermion model is
investigated. It is shown that the classical model possesses a current of
Lorentz spin 3, conserved both in the bulk and on the half-line for specific
types of boundary actions. It is then established that the conservation law is
spoiled at the quantum level -- a fact that might indicate that the quantum
Bukhvostov-Lipatov model is not integrable, contrary to what was previously
believed.Comment: 11 pages, 1 figure, LaTeX2e, AMS; new references adde
Entropic Gravity, Phase-Space Noncommutativity and the Equivalence Principle
We generalize E. Verlinde's entropic gravity reasoning to a phase-space
noncommutativity set-up. This allow us to impose a bound on the product of the
noncommutative parameters based on the Equivalence Principle. The key feature
of our analysis is an effective Planck's constant that naturally arises when
accounting for the noncommutative features of the phase-space.Comment: 12 pages. Version to appear at the Classical and Quantum Gravit
Radiation tests on commercial instrumentation amplifiers, analog switches & DAC's
A study of several commercial instrumentation amplifiers (INA110, INA111, INA114, INA116, INA118 & INA121) under neutron and vestigial gamma radiation was done. Some parameters (Gain, input offset voltage, input bias currents) were measured on-line and bandwidth, and slew rate were determined before and after radiation. The results of the testing of some voltage references REF102 and ADR290GR and the DG412 analog switch are shown. Finally, different digital-to-analog converters were tested under radiation. (6 refs)
Grupos climáticos para implantação de experimentos de melhoramento e plantio de Pinus taeda no Sul do Brasil.
Pinus taeda L. é uma das espécies mais cultivadas no mundo e no Brasil e, por isso, há diversos programas de melhoramento genético que são conduzidos para demandas específicas, tanto para as empresas de reflorestamento como para as indústrias. Estes programas de melhoramento são possíveis devido à alta variabilidade genética e ampla distribuição geográfica natural desta espécie. Devido à importância do clima na interação genótipo x ambiente; da ampla variabilidade genética das sementes e pelo fato das empresas reflorestadoras possuírem plantios de P. taeda em diversos locais da região Sul e Sudeste do Brasil a proposta deste trabalho foi delimitar e caracterizar grupos de áreas climáticas semelhantes e distintas, onde existem o plantio de P. taeda no Sul do Brasil, para subsidiar o melhoramento genético desta espécie. Como resultado, foram obtidos grupos climáticos que podem ser utilizados ao melhoramento da espécie, de forma mais assertiva em relação ao clima. A troca de informações sobre o desempenho em produção e crescimento dos plantios, divulgada entre as empresas, irá colaborar com os programas de melhoramento genético. Além disso, este aprofundamento na questão climática, associada ao melhoramento genético, torna este trabalho bastante importante, sobretudo como instrumento de auxílio no entendimento do comportamento desta espécie em relação às mudanças climáticas e na seleção de populações para atender à demanda do mercado decorrente de uma possível alteração do clima e impactos na produtividade, seja devido à seca, temperaturas mais elevadas e, ou pragas que possam ocorrer. Este trabalho apresenta aderência a diferentes metas dos Objetivos de Desenvolvimento Sustentável (ODS) estabelecidos pela Agenda 2030 da Organização das Nações Unidas (ONU), representando os ODS 8, 12, 13, 15 e 17, por ser direcionado ao aumento da produtividade, à gestão sustentável dos recursos florestais e ao incremento da capacidade de adaptação aos riscos climáticos. A valorização das parcerias multi-institucionais estão presentes em diferentes fases do trabalho, mostrando a importância de se estabelecer demandas e metas conjuntas, para resultados mais efetivos.ODS
Survey on the clinical trial results achieved in Brazil comparing praziquantel and oxamniquine in the treatment of mansoni schistosomiasis
A random, double-blind, parallel group clinical trial program was carried out to compare praziquantel, a recently developed anti-helmintic drug, and oxamniquine, an already established agent for treating mansoni schistosomiasis. Both drugs were administered orally as a single dose, on the average, praziquantel 55 mg/kg and oxamniquine 16 mg/kg BWT. The diagnosis and the parasitological follow-up lasting for a minimum of six months, were based on stool examinations according to Kato/Katz technique. A patient was considered cured if all results were negative and if he had performed at least three post-treatment controls, each one comprising three stool examinations. The finding of a single S. mansoni egg in any stool examination indicated, a therapeutical failure. A total of 267, cases were treated with praziquantel and 272 with oxamniquine. The two groups were homogeneous in regard to patients, age, clinical form of the disease, risk of reinfection and worm burden, relevant factors in the therapeutical response. The incidence and severity of untoward, effects were similar in both groups but abdominal distress and diarrhoea were more frequently reported under praziquantel and dizzines under oxamniquine (p 0.05). Amongst the noncured aptients a reduction of 88.6% and 74.6% in the mean number of eggs/g of feces Was seen following the treatment with praziquantel and oxamniquine, respectively (p < 0.05). In conclusion, in spite of their different chemical, pharmacological and toxicological profiles as well as mechanisms-of-action, inclusively praziquantel already had proved to be 100% active against S. mansoni strains resistant to oxamniquine, both drugs showed comparable tolerance and therapeutical efficacy
Global Phylogenomic Assessment of \u3ci\u3eLeptoseris\u3c/i\u3e and \u3ci\u3eAgaricia\u3c/i\u3e Reveals Substantial Undescibed Diversity at Mesophotic Depths
Background: Mesophotic coral communities are increasingly gaining attention for the unique biological diversity they host, exemplified by the numerous mesophotic fish species that continue to be discovered. In contrast, many of the photosynthetic scleractinian corals observed at mesophotic depths are assumed to be depth-generalists, with very few species characterised as mesophotic-specialists. This presumed lack of a specialised community remains largely untested, as phylogenetic studies on corals have rarely included mesophotic samples and have long suffered from resolution issues associated with traditional sequence markers.
Results: Here, we used reduced-representation genome sequencing to conduct a phylogenomic assessment of the two dominant mesophotic genera of plating corals in the Indo-Pacific and Western Atlantic, respectively, Leptoseris and Agaricia. While these genome-wide phylogenies broadly corroborated the morphological taxonomy, they also exposed deep divergences within the two genera and undescribed diversity across the current taxonomic species. Five of the eight focal species consisted of at least two sympatric and genetically distinct lineages, which were consistently detected across different methods.
Conclusions: The repeated observation of genetically divergent lineages associated with mesophotic depths highlights that there may be many more mesophotic-specialist coral species than currently acknowledged and that an urgent assessment of this largely unstudied biological diversity is warranted
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