11,210 research outputs found
The distance to M5 from its RR Lyrae variables
A variation of the Baade-Wesselink method has been applied to four RR Lyrae variables in the moderately metal-poor globular cluster M5. The method developed for the analysis utilizes an effective wavelength for each filter and relies on the accuracy of the calibration of absolute flux for bright standard stars by Oke and Gunn (1983), as well as on the accuracy of the absolute emitted fluxes predicted in the near-infrared by the Kurucz (1979) grid of model stellar atmospheres.
The results must be viewed as preliminary thus far due to apparent discrepancies between the photometrically and spectroscopically deduced angular diameter-phase relationships which are most apparent in the part of the cycle immediately following maximum light. This restricts the range of phase that can be used to derive the distance to the variables. The best value obtained for the mean of the 4 RR Lyrae stars in M5 is an absorption-corrected intensity mean absolute V magnitude of +1.05 mag (+0.15, -0.25 mag)
From workers education to societal competencies: approaches to a critical, emancipatory education for democracy
This article presents two conceptions concerning critical political education for workers, developed in Germany in the 1960s and the 1990s respectively. First, the conception of âSociological Imagination and Exemplary Learningâ published in 1968 by the German philosopher and sociologist Oskar Negt (1975). Further the elaboration of this conception, which since the 1980s is known as âSocietal Competenciesâ (Negt, 1986). These competencies concern fundamental knowledge, which enables people to make political judgments, and act politically in democratic societies in an enlightened and reflected way. This conception deliberately distinguishes itself from the economic, instrumentalist notions of key qualifications and key competencies, which at least since the 1970s have been discussed with the aim of maintaining individual employability and competitiveness. âSocietal competenciesâ aim for individual and collective emancipation, the development of the capability to make judgments, and autonomy in the sense of the enlightened political agency and participation in democratization processes. (DIPF/Orig.
Personality predictors of levels of forgiveness two and a half years after the transgression
The aim of the present study was to explore whether the domains and facets of the five-factor model of personality predicted motivational states for avoidance and revenge following a transgression at a second temporal point distant from the original transgression. A sample of 438 university students, who reported experiencing a serious transgression against them, completed measures of avoidance and revenge motivations around the transgression and five-factor personality domains and facets at time 1, and measures of avoidance and revenge motivations two and a half years later. The findings suggest that neuroticism, and specifically anger hostility, predicts revenge and avoidance motivation
Bidirectional Reactive Programming for Machine Learning
Reactive languages are dedicated to the programming of systems which interact
continuously and concurrently with their environment. Values take the form of
unbounded streams modeling the (discrete) passing of time or the sequence of
concurrent interactions. While conventional reactivity models recurrences
forward in time, we introduce a symmetric reactive construct enabling backward
recurrences. Constraints on the latter allow to make the implementation
practical. Machine Learning (ML) systems provide numerous motivations for all
of this: we demonstrate that reverse-mode automatic differentiation,
backpropagation, batch normalization, bidirectional recurrent neural networks,
training and reinforcement learning algorithms, are all naturally captured as
bidirectional reactive programs
Continuous-wave Doppler-cooling of hydrogen atoms with two-photon transitions
We propose and analyze the possibility of performing two-photon
continuous-wave Doppler-cooling of hydrogen atoms using the 1S-2S transition.
"Quenching" of the 2S level (by coupling with the 2P state) is used to increase
the cycling frequency, and to control the equilibrium temperature. Theoretical
and numerical studies of the heating effect due to Doppler-free two-photon
transitions evidence an increase of the temperature by a factor of two. The
equilibrium temperature decreases with the effective (quenching dependent)
width of the excited state and can thus be adjusted up to values close to the
recoil temperature.Comment: 11 pages, 4 figures in eps forma
Observation of dissipative chlorophyll-to-carotenoid energy transfer in light-harvesting complex II in membrane nanodiscs
Abstract Plants prevent photodamage under high light by dissipating excess energy as heat. Conformational changes of the photosynthetic antenna complexes activate dissipation by leveraging the sensitivity of the photophysics to the protein structure. The mechanisms of dissipation remain debated, largely due to two challenges. First, because of the ultrafast timescales and large energy gaps involved, measurements lacked the temporal or spectral requirements. Second, experiments have been performed in detergent, which can induce non-native conformations, or in vivo, where contributions from homologous antenna complexes cannot be disentangled. Here, we overcome both challenges by applying ultrabroadband two-dimensional electronic spectroscopy to the principal antenna complex, LHCII, in a near-native membrane. Our data provide evidence that the membrane enhances two dissipative pathways, one of which is a previously uncharacterized chlorophyll-to-carotenoid energy transfer. Our results highlight the sensitivity of the photophysics to local environment, which may control the balance between light harvesting and dissipation in vivo
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