The de Broglie Wave as a Localized Excitation of the Action Function

The Hamilton-Jacobi equation of relativistic quantum mechanics is revisited. The equation is shown to permit solutions in the form of breathers (nondispersive oscillating/spinning solitons), displaying simultaneous particle-like and wave-like behavior adaptable to the properties of the de Broglie clock. Within this formalism the de Broglie wave acquires the meaning of a localized excitation of the classical action function. The problem of quantization in terms of the breathing action function is discussed.Comment: 11 page

Local dynamics in high-order harmonic generation using Bohmian trajectories

We investigate high-order harmonic generation from a Bohmian-mechanical perspective, and find that the innermost part of the core, represented by a single Bohmian trajectory, leads to the main contributions to the high-harmonic spectra. Using time-frequency analysis, we associate this central Bohmian trajectory to an ensemble of unbound classical trajectories leaving and returning to the core, in agreement with the three step model. In the Bohmian scenario, this physical picture builds up non-locally near the core via the quantum mechanical phase of the wavefunction. This implies that the flow of the wavefunction far from the core alters the central Bohmian trajectory. We also show how this phase degrades in time for the peripheral Bohmian trajectories as they leave the core region.Comment: 7 pages, 3 figures; the manuscript has been considerably extended and modified with regard to the previous version

A Method for Shortening of the Rat Spine and its Neurologic Consequences

Large laboratory animals are the usual choice for complex surgical procedures on the spine and spinal cord, such as shortening of the spine. It would, however, be advantageous to be able to use a small inexpensive mammal like the rat. We describe a procedure which allows thoracic spondylectomy (T8-T9) to be performed in the rat with a satisfactory survival rate (69%). Functional consequences of the procedure on animals with uninjured spinal cord were monitored over a period of six months, at which time histologic examination was performed. There was a good correlation between operative trauma, consisting of mechanical injury to the cord assessed from the surgical notes, and the duration of postoperative spinal shock. Animals for which the cord appeared laminated or deformed at the time of sacrifice tended to show incomplete functional recovery. Cord cavitation developed, in most surviving animals (78%) but did not have a measurable adverse effect on functional outcome. In the present study, the cord was not intentionally injured; however, availability of this procedure may facilitate the future development of methods to implement recovery of function following spinal cord injury

The scattering of small bodies in planetary systems: constraints on the possible orbits of cometary material

The scattering of small bodies by planets is an important dynamical process in planetary systems. We present an analytical model to describe this process using the simplifying assumption that each particle's dynamics is dominated by a single planet at a time. As such the scattering process can be considered as a series of three body problems during each of which the Tisserand parameter with respect to the relevant planet is conserved. This constrains the orbital parameter space into which a particle can be scattered. Such arguments have previously been applied to the process by which comets are scattered to the inner Solar System from the Kuiper belt. Our analysis generalises this for an arbitrary planetary system. For particles scattered from an outer belt directly along a chain of planets, based on the initial value of the Tisserand parameter, we find that it is possible to (i) determine which planets can eject the particles from the system, (ii) define a minimum stellar distance to which particles can be scattered, and (iii) constrain range of particle inclinations (and hence the disc height) at different distances. Applying this to the Solar System, we determine that the planets are close to optimally separated for scattering particles between them. Concerning warm dust found around stars that also have Kuiper belt analogues, we show that, if there is to be a dynamical link between the outer and inner regions, then certain architectures for the intervening planetary system are incapable of producing the observations. Furthermore we show that for certain planetary systems, comets can be scattered from an outer belt, or with fewer constraints, from an Oort cloud analogue, onto star-grazing orbits, in support of a planetary origin to the metal pollution and dustiness of some nearby white dwarfs

High-spatial-resolution imaging of thermal emission from debris disks

We have obtained sub-arcsec mid-IR images of a sample of debris disks within 100 pc. For our sample of nineteen A-type debris disk candidates chosen for their IR excess, we have resolved, for the first time, five sources plus the previously resolved disk around HD 141569. Two other sources in our sample have been ruled out as debris disks since the time of sample selection. Three of the six resolved sources have inferred radii of 1-4 AU (HD 38678, HD 71155, and HD 181869), and one source has an inferred radius ~10-30 AU (HD 141569). Among the resolved sources with detections of excess IR emission, HD 71155 appears to be comparable in size (r~2 AU) to the solar system's asteroid belt, thus joining Zeta Lep (HD 38678, reported previously) to comprise the only two resolved sources of that class. Two additional sources (HD 95418 and HD 139006) show spatial extent that implies disk radii of ~1-3 AU, although the excess IR fluxes are not formally detected with better than 2-sigma significance. For the unresolved sources, the upper limits on the maximum radii of mid-IR disk emission are in the range ~1-20 AU, four of which are comparable in radius to the asteroid belt. We have compared the global color temperatures of the dust to that expected for the dust in radiative equilibrium at the distances corresponding to the observed sizes or limits on the sizes. In most cases, the temperatures estimated via these two methods are comparable, and therefore, we see a generally consistent picture of the inferred morphology and the global mid-IR emission. Finally, while our sample size is not statistically significant, we notice that the older sources (>200 Myr) host much warmer dust (T > 400 K) than younger sources (in the 10s of Myr).Comment: 46 pages, 12 figure

Quantum vortices and trajectories in particle diffraction

We investigate the phenomenon of the diffraction of charged particles by thin material targets using the method of the de Broglie-Bohm quantum trajectories. The particle wave function can be modeled as a sum of two terms $\psi=\psi_{ingoing}+\psi_{outgoing}$. A thin separator exists between the domains of prevalence of the ingoing and outgoing wavefunction terms. The structure of the quantum-mechanical currents in the neighborhood of the separator implies the formation of an array of \emph{quantum vortices}. The flow structure around each vortex displays a characteristic pattern called `nodal point - X point complex'. The X point gives rise to stable and unstable manifolds. We find the scaling laws characterizing a nodal point-X point complex by a local perturbation theory around the nodal point. We then analyze the dynamical role of vortices in the emergence of the diffraction pattern. In particular, we demonstrate the abrupt deflections, along the direction of the unstable manifold, of the quantum trajectories approaching an X-point along its stable manifold. Theoretical results are compared to numerical simulations of quantum trajectories. We finally calculate the {\it times of flight} of particles following quantum trajectories from the source to detectors placed at various scattering angles $\theta$, and thereby propose an experimental test of the de Broglie - Bohm formalism.Comment: 17 pages, 7 figures, accepted by IJB

Validation of the Saint George's Respiratory Questionnaire in patients with chronic obstructive pulmonary disease in Brazil

Introduction: The term quality of life has gained increasing importance in the scientific context. This study describes the adaptation of a disease-specific questionnaire developed by Paul Jones et al. in 1991, the St. George's Respiratory Questionnaire (SGRQ), to the Brazilian language and culture. This questionnaire evaluates the quality of life in patients with chronic obstructive pulmonary disease (COPD) and contains three domains (symptoms, activity, and impacts) divided in 76 items. The questionnaire is self-administrated, but it may be read to illiterate persons. Goal: To verify if the St. George's Respiratory Questionnaire is a valid tool to measure quality of life in patients with chronic obstructive pulmonary disease in Brazil. Methods: In order to validate the questionnaire in Brazil, it was initially translated into Portuguese and afterwards a back-translation into English, that was compared to the original version. A final Portuguese version was then written. This final version was, then, answered by 30 clinically stable COPD patients, according to the spirometry and oximetry values. Patients answered the questionnaire twice, within a 15 day interval. The length of time the patients took to answer the questionnaire and their doubts were noted. Wilcoxon test was used for the calculation of r probability between every single question between the two days; interclass correlation ratio was calculated to test the trustworthiness and reliability of the questionnaire. Results: Among the 30 participant patients, 10 were female and 20 were male. Mean age was 65.9 years. Most of the patients were found to be in stage 2 (56.7 %) of COPD, according to the American Thoracic Society classification. The interclass correlation ratio for the total score of the questionnaire was a = 0.79 and Wilcoxon p = 0.2110 (not statistically significant). The mean answering time for the two days of interview was, respectively, 11 minutes and 50 seconds and 10 minutes and 31 seconds. As concerns the doubts about the questions, the patients reported difficulties in answering Sections 4 and 5, each one of these questions written in a negative form. Conclusion: It can be concluded that the Brazilian version of the St. George's Respiratory Questionnaire is a valid and reliable tool to measure quality of life in patients with COPD in Brazil.Introdução: O termo qualidade de vida tem adquirido cada vez mais importância no contexto científico. O presente estudo descreve a adaptação para as língua e cultura brasileiras de um questionário doença-específico desenvolvido por Paul Jones et al. em 1991(1): o Questionário do Hospital Saint George na Doença Respiratória (SGRQ), para a avaliação de qualidade de vida em pacientes portadores de doença pulmonar obstrutiva crônica (DPOC). Esse questionário contém três componentes (sintomas, atividade e impactos) divididos em 76 itens. É auto-administrado e pode ser lido para pacientes analfabetos. Objetivo: Verificar se o SGRQ é um instrumento válido para medir qualidade de vida em pacientes portadores de DPOC no Brasil. Métodos: Para a validação deste questionário no Brasil, realizou-se, inicialmente, uma versão da língua inglesa para o português; em seguida, foi realizada a tradução retrógrada (back translation), do português para o inglês, e uma versão final foi aplicada em 30 pacientes com diagnóstico de DPOC, estáveis clinicamente e baseado em critérios de espirometria e oximetria. Os pacientes responderam ao questionário por duas vezes, num intervalo de 15 dias. O tempo de resposta foi cronometrado e as dúvidas apontadas pelos pacientes, anotadas. Foi utilizado o teste estatístico de Wilcoxon para cálculo de probabilidade de r e calculado o coeficiente de correlação intraclasse para testar a fidedignidade e a confiabilidade do questionário. Resultados: Dos 30 pacientes que participaram do estudo, 10 eram do sexo feminino e 20 do masculino. A média de idade foi de 65,9 anos. A maioria dos pacientes encontrava-se no estádio 2 (56,7%) da DPOC, segundo a classificação da American Thoracic Society. O coeficiente de correlação intraclasse para a pontuação total do questionário foi a = 0,79 e o resultado do teste de Wilcoxon p = 0,2110 (não significante estatisticamente). O tempo médio de resposta dos dois dias de entrevista foi, respectivamente, 11 minutos e 50 segundos e 10 minutos e 31 segundos. Em relação às dúvidas, as questões mais freqüentemente referidas foram as das seções 4 e 5, que contêm uma frase cada na forma negativa. Conclusão: Pode-se concluir que a versão brasileira do Questionário do Hospital Saint George na Doença Respiratória (SGRQ) é um instrumento válido e fidedigno para medir qualidade de vida em pacientes portadores de DPOC no Brasil.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaCentro Universitário de UberlândiaUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Centro de Reabilitação PulmonarUniversity of LondonUNIFESP, EPM, Centro de Reabilitação PulmonarSciEL

Antenatal depression in Sri Lanka: a qualitative study of public health midwives’ views and practices

Background Almost all pregnant people in Sri Lanka receive antenatal care by public health midwives. While there is strong infrastructure in Sri Lanka for postpartum mental health care, the current practices within antenatal mental health care have not been externally evaluated. The purpose of this study is to investigate the current clinical guidelines and experiences of how public health midwives diagnose and treat antenatal depression. Methods We conducted in-depth interviews with 12 public health midwives from four antenatal clinics in the Bope Poddala division in Galle, Sri Lanka and reviewed and extracted information on antenatal depression from clinical guidelines. Data was collected in Sinhala and translated into English. We used applied thematic analysis and worked closely with our local team to ensure data trustworthiness. Results Midwives (n = 12) reported varying degrees of knowledge on antenatal depression and did not have standardized diagnosis patterns. However, they were very consistent in their clinical practices, following guidelines for referral and follow-up of case management, building strong rapport. In their practice, midwives continue to face challenges of lack of human resources and high stigma around mental illness. They suggested that that care could be improved with use of a standardized diagnostic tool, and easier access to specialist care. We found the clinical guideline on the diagnosis and treatment of antenatal depression is lacking key details on symptoms for appropriate diagnosis, but it clearly guides on how to navigate treatment. Conclusions Public health midwives are following the clinical guideline to refer pregnant women who need intervention for antenatal depression and follow-up for case management. However, there is a need for more specific and context-relevant guidelines, especially for diagnosis of antenatal depression. Formative research is needed to explore intervention strategies to improve antenatal depression management in Sri Lanka.publishedVersio

Professional Development as a Process of Cultural Brokering: Positioning Coaches as Cultural Brokers

Teachers who serve diverse students must navigate two “worlds.” One world is that of standardized curricula and pedagogy and the other is culturally relevant education. To effectively navigate these worlds, teachers need assistance from “cultural brokers” who can help make sense of the tension that emerges when these two educational worlds interact. This study analyzes the work of two Center for Research on Education, Diversity, and Excellence coaches who worked as cultural brokers to help teachers integrate multiple pedagogical models. The results indicate the coaches shifted their strategies depending on teacher preferences, and helped teachers overcome constraints within their classrooms and curricula. Framing coaches as “cultural brokers” may be a useful metaphor for others assisting teachers with navigating the tension that emerges in implementing culturally relevant education