System for energy harvesting and/or generation, storage, and delivery

A device and method for harvesting, generating, storing, and delivering energy to a load, particularly for remote or inaccessible applications. The device preferably comprises one or more energy sources, at least one supercapacitor, at least one rechargeable battery, and a controller. The charging of the energy storage devices and the delivery of power to the load is preferably dynamically varied to maximize efficiency. A low power consumption charge pump circuit is preferably employed to collect power from low power energy sources while also enabling the delivery of higher voltage power to the load. The charging voltage is preferably programmable, enabling one device to be used for a wide range of specific applications

On fundamental domains and volumes of hyperbolic Coxeter-Weyl groups

We present a simple method for determining the shape of fundamental domains of generalized modular groups related to Weyl groups of hyperbolic Kac-Moody algebras. These domains are given as subsets of certain generalized upper half planes, on which the Weyl groups act via generalized modular transformations. Our construction only requires the Cartan matrix of the underlying finite-dimensional Lie algebra and the associated Coxeter labels as input information. We present a simple formula for determining the volume of these fundamental domains. This allows us to re-produce in a simple manner the known values for these volumes previously obtained by other methods.Comment: v2: to be published in Lett Math Phys (reference added, typo corrected

FUSE spectroscopy of sdOB primary of the post common-envelope binary LB 3459 (AA Dor)

LB 3459 (AA Dor) is an eclipsing, close, post common-envelope binary consisting of an sdOB primary star and an unseen secondary with an extraordinarly low mass - formally a brown dwarf. A recent NLTE spectral analysis shows a discrepancy with the surface gravity, which is derived from analyses of radial-velocity and lightcurves. We aim at precisely determing of the photospheric parameters of the primary, especially of the surface gravity, and searching for weak metal lines in the far UV. We performed a detailed spectral analysis of the far-UV spectrum of LB 3459 obtained with FUSE by means of state-of-the-art NLTE model-atmosphere techniques. A strong contamination of the far-UV spectrum of LB 3459 by interstellar line absorption hampers a precise determination of the photospheric properties of its primary star. Its effective temperature (42 kK) was confirmed by the evaluation of new ionization equilibria. For the first time, phosphorus and sulfur have been identified in the spectrum of LB 3459. Their photospheric abundances are solar and 0.01 times solar, respectively. From the C III 1174-1177A multiplet, we can measure the rotational velocity of 35 +/- 5 km/sec of the primary of LB 3459 and confirm that the rotation is bound. From a re-analysis of optical and UV spectra, we determine a higher log g = 5.3 (cgs) that reduces the discrepancy in mass determination in comparison to analyses of radial-velocity and lightcurves. However, the problem is not completely solved.Comment: 10 pages, 15 figure

Einsam(er) seit der Coronapandemie: Wer ist besonders betroffen? – psychologische Befunde aus Deutschland

Hintergrund: Soziale Isolation ist ein Risikofaktor für Einsamkeit und damit für gesundheitliche Beeinträchtigungen. Veränderungen im Zusammenhang mit der Coronapandemie in Deutschland gilt es besser zu verstehen. Fragestellung: Ziel der Studie war es, Einsamkeit und assoziierte Faktoren vor und während der Coronapandemie in Deutschland systematisch zu untersuchen. Die Fragestellungen waren: 1. Wie einsam fühlen sich Menschen vor und während der Coronapandemie? 2. Wie viele Menschen fühlen sich seit Beginn der Coronapandemie einsamer? 3. Wie viele Menschen berichten über gesundheitliche Belastungen während der Coronapandemie? Material und Methoden: Im Jahr 2019 (vor der Coronapandemie) wurden 1003 und im Jahr 2020 (während der Coronapandemie) 1050 Erwachsene online befragt (51 % Frauen; 18-90 Jahre). Ergebnisse: Es fühlten sich 10,8 % vs. 26,6 % der Befragten vor bzw. seit der Coronapandemie mehrfach pro Woche oder täglich einsam. Alleinlebende, Frauen und Jüngere fühlten sich häufiger einsam. Seit der Coronapandemie fühlten sich 30,8 % einsamer, v. a. Jüngere. Von starken gesundheitlichen Belastungen berichteten 18,9 %, dies hing mit jüngerem Alter, verschiedenen Sorgen/Ängsten und Einsamkeit zusammen. Diskussion: Die höhere Ausprägung der Einsamkeit und Sorgen während der Coronapandemie sollte bei verhaltensbezogenen Maßnahmen zur Prävention der psychischen und körperlichen Beeinträchtigungen sowie behördlichen Maßnahmen berücksichtigt werden. Jüngere Menschen und Alleinlebende könnten profitieren, indem sie zu gezielten Bewältigungsstrategien (z. B. angemessener Nutzung digitaler Medien) ermutigt werden

On the sdOB primary of the post common-envelope binary AA Doradus (LB 3459)

AA Dor is an eclipsing, post common-envelope binary with an sdOB-type primary and a low-mass secondary. Eleven years ago, an NLTE spectral analysis showed a discrepancy in the surface gravity that was derived by radial-velocity and light-curve analysis, log g = 5.21 +/- 0.1 (cm/sec^2) and log g = 5.53 +/- 0.03, respectively. We aim to determine both the effective temperature and surface gravity of AA Dor precisely from high-resolution, high-S/N observations taken during the occultation of the secondary. We calculated an extended grid of metal-line blanketed, state-of-the-art, non-LTE model atmospheres in the parameter range of the primary of AA Dor. Synthetic spectra calculated from this grid were compared to optical observations. We verify Teff = 42000 +/- 1000 K from our former analyses and determine a higher log g = 5.46 +/- 0.05. The main reason are new Stark-broadening tables that were used for calculating of the theoretical Balmer-line profiles. Our result for the surface gravity agrees with the value from light-curve analysis within the error limits, thereby solving the so-called gravity problem in AA Dor.Comment: 6 pages, 7 figure

Eisenstein series for infinite-dimensional U-duality groups

We consider Eisenstein series appearing as coefficients of curvature corrections in the low-energy expansion of type II string theory four-graviton scattering amplitudes. We define these Eisenstein series over all groups in the E_n series of string duality groups, and in particular for the infinite-dimensional Kac-Moody groups E9, E10 and E11. We show that, remarkably, the so-called constant term of Kac-Moody-Eisenstein series contains only a finite number of terms for particular choices of a parameter appearing in the definition of the series. This resonates with the idea that the constant term of the Eisenstein series encodes perturbative string corrections in BPS-protected sectors allowing only a finite number of corrections. We underpin our findings with an extensive discussion of physical degeneration limits in D<3 space-time dimensions.Comment: 69 pages. v2: Added references and small additions, to be published in JHE