The pulsating DA white dwarf star EC 14012-1446: results from four epochs of time-resolved photometry

The pulsating DA white dwarfs are the coolest degenerate stars that undergo self-driven oscillations. Understanding their interior structure will help to understand the previous evolution of the star. To this end, we report the analysis of more than 200 h of time-resolved CCD photometry of the pulsating DA white dwarf star EC 14012-1446 acquired during four observing epochs in three different years, including a coordinated three-site campaign. A total of 19 independent frequencies in the star's light variations together with 148 combination signals up to fifth order could be detected. We are unable to obtain the period spacing of the normal modes and therefore a mass estimate of the star, but we infer a fairly short rotation period of 0.61 +/- 0.03 d, assuming the rotationally split modes are l=1. The pulsation modes of the star undergo amplitude and frequency variations, in the sense that modes with higher radial overtone show more pronounced variability and that amplitude changes are always accompanied by frequency variations. Most of the second-order combination frequencies detected have amplitudes that are a function of their parent mode amplitudes, but we found a few cases of possible resonantly excited modes. We point out the complications in the analysis and interpretation of data sets of pulsating white dwarfs that are affected by combination frequencies of the form f_A+f_B-f_C intruding into the frequency range of the independent modes.Comment: 14 pages, 6 figures, 6 tables. MNRAS, in pres

M-Dwarf Fast Rotators and the Detection of Relatively Young Multiple M-Star Systems

We have searched the Kepler light curves of ~3900 M-star targets for evidence of periodicities that indicate, by means of the effects of starspots, rapid stellar rotation. Several analysis techniques, including Fourier transforms, inspection of folded light curves, 'sonograms', and phase tracking of individual modulation cycles, were applied in order to distinguish the periodicities due to rapid rotation from those due to stellar pulsations, eclipsing binaries, or transiting planets. We find 178 Kepler M-star targets with rotation periods, P_rot, of < 2 days, and 110 with P_rot < 1 day. Some 30 of the 178 systems exhibit two or more independent short periods within the same Kepler photometric aperture, while several have three or more short periods. Adaptive optics imaging and modeling of the Kepler pixel response function for a subset of our sample support the conclusion that the targets with multiple periods are highly likely to be relatively young physical binary, triple, and even quadruple M star systems. We explore in detail the one object with four incommensurate periods all less than 1.2 days, and show that two of the periods arise from one of a close pair of stars, while the other two arise from the second star, which itself is probably a visual binary. If most of these M-star systems with multiple periods turn out to be bound M stars, this could prove a valuable way of discovering young hierarchical M-star systems; the same approach may also be applicable to G and K stars. The ~5% occurrence rate of rapid rotation among the ~3900 M star targets is consistent with spin evolution models that include an initial contraction phase followed by magnetic braking, wherein a typical M star can spend several hundred Myr before spinning down to periods longer than 2 days.Comment: 17 pages, 12 figures, 2 tables; accepted for publication in The Astrophysical Journa

Impacto sobre a aprendizagem dos alunos: Perspectivas sobre a Comissão Nacional de Certificação de Professores

The purpose of this study is to report National Board Certified Teachers’ (NBCTs) perceived impact on student learning. The guiding research question for this study, “How do teachers perceive the influence of the National Board Certification process on student learning in their own classrooms?” was explored. A total of 496 NBCTs currently teaching in North Carolina public schools completed the survey questionnaire in which they responded to demographic questions, Likert item questions, and open-ended questions. More than 80% of the study’s participants reported the certification process had positively influenced student learning in their classrooms. Thematic analysis revealed several reoccurring themes that NBCTs reported having impact on student learning in their classrooms. These included impact on academic achievement, improved teaching, and/or an increase of effective evaluation and assessment strategies.El propósito de este estudio es informar sobre la percepción del impacto de la Comisión Nacional de Certificación Docente (por su sigla en inglés NBCTs) en el aprendizaje de los estudiantes. La pregunta de investigación que guía este estudio es "¿Cómo perciben los profesores la influencia del proceso de Certificación de la NBCTs en el aprendizaje de los estudiantes en las aulas de su país”. Un total de 496 docentes que cuentan con su NBCTs en las escuelas públicas de Carolina del Norte completó la encuesta en la que respondieron a preguntas demográficas, preguntas usando escalas Likert y preguntas abiertas. Más del ochenta por ciento de los participantes del estudio informó que el proceso de certificación ha influido positivamente en el aprendizaje de los estudiantes en sus clases. Análisis temático reveló varios temas recurrentes que los docentes NBCTs reportaron influyen en el aprendizaje de los estudiantes, incluidos rendimiento académico, mejora de la enseñanza, y/o un aumento de estrategias de evaluación y evaluación eficaces.O objetivo deste estudo é relatar sobre as percepções de impacto da Comissão Nacional de Certificação de Professores (sigla em Inglês NBCTs) nos aprendizagens dos alunos. A questão de pesquisa que orientou este estudo foi "Como é que os professores percebem a influência do processo de certificação NBCTs na aprendizagem dos alunos nas salas de aula do seu país". Um total de 496 professores têm seus NBCTs nas escolas públicas da Carolina do Norte responderam as perguntas sobre dados demográficos, perguntas usando uma escala Likert e perguntas abertas. Mais de oitenta por cento dos participantes do estudo relataram que o processo de certificação tem efeitos positivos na aprendizagem dos alunos em suas aulas. A análise temática revelou vários temas recorrentes que os professores NBCTs indicaram que influenciam a aprendizagem dos alunos, incluindo desempenho acadêmico, melhoras na educação, e/ou um aumento de estratégias de avaliação e de avaliação eficazes

An asteroseismic test of diffusion theory in white dwarfs

The helium-atmosphere (DB) white dwarfs are commonly thought to be the descendants of the hotter PG1159 stars, which initially have uniform He/C/O atmospheres. In this evolutionary scenario, diffusion builds a pure He surface layer which gradually thickens as the star cools. In the temperature range of the pulsating DB white dwarfs (T_eff ~ 25,000 K) this transformation is still taking place, allowing asteroseismic tests of the theory. We have obtained dual-site observations of the pulsating DB star CBS114, to complement existing observations of the slightly cooler star GD358. We recover the 7 independent pulsation modes that were previously known, and we discover 4 new ones to provide additional constraints on the models. We perform objective global fitting of our updated double-layered envelope models to both sets of observations, leading to determinations of the envelope masses and pure He surface layers that qualitatively agree with the expectations of diffusion theory. These results provide new asteroseismic evidence supporting one of the central assumptions of spectral evolution theory, linking the DB white dwarfs to PG1159 stars.Comment: 7 pages, 3 figures, 3 tables, accepted for publication in A&

Social labs as good practice for transdisciplinary engagement processes in research and innovation

This article discusses a ‘Social Lab process’ applied in the field of research and innovation as good practice for transdisciplinary processes, and elaborates upon the structure and dynamics of these processes. It sheds light on how engagement processes could be set up for a more inclusive and participant-friendly atmosphere, allowing for meaningful and sustainable outcomes. Supported by data from a qualitative analysis of 19 Social Lab experiences according to the thematic programmes of the European Commission Horizon 2020 research framework programme, this article outlines requirements that need to be taken into account when implementing a transdisciplinary process in a Social Lab. Based on the concept of transdisciplinary research and the experience of this one-and-a-half-year process, the elements of participatory approaches required for successful implementation of a Social Lab, starting with inviting participants to develop small implementation projects (pilot activities) are described. The qualitative analysis of the process documentations highlights the importance of a clear definition of the framework and purpose of the process. Concrete assignments of the lab teams and roles, and the implementation of pilot activities, further proved crucial for successful and sustainable results. On this basis, recommendations for a fruitful participatory process are formulated

Considerations for the Next Revision of NASA's Space Telecommunications Radio System Architecture

Development of NASA's Software Defined Radio architecture, the Space Telecommunication Radio System (STRS), was initiated in 2004 with a goal of reducing the cost, risk and schedule when implementing Software Defined Radios (SDR) for National Aeronautics and Space Administration (NASA) space missions. Since STRS was first flown in 2012 on three Software Defined Radios on the Space Communication and Navigation (SCaN) Testbed, only minor changes have been made to the architecture. Multiple entities have since implemented the architecture and provided significant feedback for consideration for the next revision of the standard. The focus for the first set of updates to the architecture is items that enhance application portability. Items that require modifications to existing applications before migrating to the updated architecture will only be considered if there is compelling reasons to make the change. The significant suggestions that were further evaluated for consideration include expanding and clarifying the timing Application Programming Interfaces (APIs), improving handle name and identification (ID) definitions and use, and multiple items related to implementation of STRS Devices. In addition to ideas suggested while implementing STRS, SDR technology has evolved significantly and this impact to the architecture needs to be considered. These include incorporating cognitive concepts - learning from past decisions and making new decisions that the radio can act upon. SDRs are also being developed that do not contain a General Purpose Module - which is currently required for the platform to be STRS compliant. The purpose of this paper is to discuss the comments received, provide a summary of the evaluation considerations, and examine planned dispositions

Renal function and cortical blood flow during the recovery phase of acute renal failure

Renal function and cortical blood flow during the recovery phase of acute renal failure. The characteristics of the recovery process in dichromate-induced acute renal failure were determined. Rats were studied 1, 4, 7, and 14 days after the s.c. injection of either saline or potassium dichromate. In the sham-injected control animals, all values at each interval were similar. The typical pattern of acute renal failure was seen one day after dichromate injection: glomerular filtration rate (GFR) fell 80%, total renal blood flow (TRBF) was reduced 35%, the proportional flow to the outer cortex was diminished, and the urinary to plasma (U/P) inulin clearance was reduced. The early recovery phase, days 4 and 7, was characterized by: 1) a mild but significant diuresis, 2) progressive improvement in GFR and an increase in the proportional flow to the outer cortex, which actually exceeded control values, 3) a dissociation between improvement in renal function and changes in TRBF, since GFR increased progressively while TRBF remained relatively fixed, and 4) improvement in GFR that was associated with a progressive and parallel increase in absolute perfusion of the outer cortex. The present data suggest that the recovery process occurs in two stages. In the first stage, the restoration of outer cortical perfusion and renal function precedes the recovery of TRBF and tubular function, which occur during the second stage of the recovery process.Fonction rénale et débit sanguin rénal cortical au cours de la période de récupération de l'insuffisance rénale aiguë. Les caractéristiques du processus de récupération après une insuffisance rénale aiguë induite par le dichromate, ont été déterminées. Des rats ont été étudiés 1, 4, 7, et l4 jours après l'injection s.c. de dichromate de potassium ou de soluté salé. Chez les animaux contrôles, toutes les valeurs obtenues sont semblables. L'aspect typique de l'insuffisance rénale aiguë est observée un jour après l'injection de dichromate: GFR diminue de 80%, le débit sanquin rénal (TRBF) est réduit de 35%, la fraction de ce débit délivrée au cortex superficiel diminue et le U/P de l'inuline est abaissé. La phase de récupération précoce, aux jours 4 et 7, est caractérisée par: 1) une diurèse peu importante mais significativement plus grande, 2) une amélioration progressive de GFR et une augmentation de la fraction du débit délivrée au cortex superficiel, qui devient supérieure aux valeurs contrôles, 3) une dissociation entre l'amélioration de la fonction rénale indiquée par l'augmentation progressive de GFR, et TRBF qui reste relativement bas, 4) et une amélioration de GFR qui est associée à une augmentation progressive et parallèle du débit absolu de perfusion du cortex superficiel. Ces résultats suggèrent que le processus de récuparation survient en deux étapes. A la première étape, la récupération du débit cortical superficiel et de la fonction rénale précède la récupération de TRBF et de la fonction tubulaire qui constitue la deuxième étape

Model for the structure function constant for index of refraction fluctuations in Rayleigh-Benard turbulence

A model for the structure function constant associated with index of refraction fluctuations in Rayleigh-Benard turbulence is developed. The model is based upon the following assumptions: (1) the turbulence is homogeneous and isotropic at or near the mid-plane, (2) the rate of production is in balance with the rate of dissipation, (3) an inertial region exists, and (4) estimates for the rate of dissipation of temperature fluctuations and of turbulent kinetic energy can be made by assuming that the large-scale turbulence is dissipated in one eddy turnover time. From these assumptions, the dependence of the structure function on the geometry, heat flux, and the properties of the fluid is obtained. The model predicts that the normalized structure function constant is independent of the Rayleigh number. To verify the model, numerical simulations of Rayleigh-Benard turbulence were performed using two different approaches: an in-house code based on a pseudo-spectral method, and a finite volume code which employs a model for the smallest scales of the turbulence. The model was found to agree with the results of the simulations, thereby lending support for the assumptions underlying the theory.Comment: 25 pages, 10 figures, 1 tabl