6,193 research outputs found
Some finite solvable groups with non-trivial lattice endomorphisms
The main purpose of this paper is to exhibit a doubly-infinite family of examples which are extensions of a p-group by a p′-group, with the action satisfying some conditions of Zappa (1951), arising from his study of dual-standard (meet-distributive) subgroups. The examples show that Zappa's conditions do not bound the nilpotency class (or even the derived length) of the p-group. The key to this work is found in closely related conditions of Hartley (published here for the first time). The examples use some exceptional relationships between primes
Compact CMOS active quenching/recharge circuit for SPAD arrays
Avalanche diodes operating in Geiger mode are able to detect single photon events. They can be employed to photon counting and time-of-flight estimation. In order to ensure proper operation of these devices, the avalanche current must be rapidly quenched, and, later on, the initial equilibrium must be restored. In this paper, we present an active quenching/recharge circuit specially designed to be integrated in the form of an array of single-photon avalanche diode (SPAD) detectors. Active quenching and recharge provide benefits like an accurately controllable pulse width and afterpulsing reduction. In addition, this circuit yields one of the lowest reported area occupations and power consumptions. The quenching mechanism employed is based on a positive feedback loop that accelerates quenching right after sensing the avalanche current. We have employed a current starved inverter for the regulation of the hold-off time, which is more compact than other reported controllable delay implementations. This circuit has been fabricated in a standard 0.18 μm complementary metal-oxide-semiconductor (CMOS) technology. The SPAD has a quasi-circular shape of 12 μm diameter active area. The fill factor is about 11%. The measured time resolution of the detector is 187 ps. The photon-detection efficiency (PDE) at 540 nm wavelength is about 5% at an excess voltage of 900 mV. The break-down voltage is 10.3 V. A dark count rate of 19 kHz is measured at room temperature. Worst case post-layout simulations show a 117 ps quenching and 280 ps restoring times. The dead time can be accurately tuned from 5 to 500 ns. The pulse-width jitter is below 1.8 ns when dead time is set to 40 ns.Ministerio de Economía y Competitividad TEC2012-38921-C02, IPT-2011-1625-430000, IPC-20111009 CDTIJunta de Andalucía TIC 2338-2013Office of Naval Research (USA) N00014141035
Minimum energy paths for conformational changes of viral capsids
In this work we study how a viral capsid can change conformation using
techniques of Large Deviations Theory for stochastic differential equations.
The viral capsid is a model of a complex system in which many units - the
proteins forming the capsomers - interact by weak forces to form a structure
with exceptional mechanical resistance. The destabilization of such a structure
is interesting both per se, since it is related either to infection or
maturation processes, and because it yields insights into the stability of
complex structures in which the constitutive elements interact by weak
attractive forces. We focus here on a simplified model of a dodecahederal viral
capsid, and assume that the capsomers are rigid plaquettes with one degree of
freedom each. We compute the most probable transition path from the closed
capsid to the final configuration using minimum energy paths, and discuss the
stability of intermediate states.Comment: 27 pages, 4 figures. New version, to appear in Physical Review
Gravitational-wave luminosity of binary neutron stars mergers
We study the gravitational-wave peak luminosity and radiated energy of
quasicircular neutron star mergers using a large sample of numerical relativity
simulations with different binary parameters and input physics. The peak
luminosity for all the binaries can be described in terms of the mass ratio and
of the leading-order post-Newtonian tidal parameter solely. The mergers
resulting in a prompt collapse to black hole have largest peak luminosities.
However, the largest amount of energy per unit mass is radiated by mergers that
produce a hypermassive neutron star or a massive neutron star remnant. We
quantify the gravitational-wave luminosity of binary neutron star merger
events, and set upper limits on the radiated energy and the remnant angular
momentum from these events. We find that there is an empirical universal
relation connecting the total gravitational radiation and the angular momentum
of the remnant. Our results constrain the final spin of the remnant black-hole
and also indicate that stable neutron star remnant forms with super-Keplerian
angular momentum.Comment: 5 pages, 4 figure
A versatile and light-weight slow control system for small-scale applications
We present an open source slow control system for small and medium scale
projects. Thanks to its modular and flexible design, where the various
instruments are read and controlled by independent plugins, Doberman (Detector
OBsERving and Monitoring ApplicatioN) can be quickly adapted for many
applications, also making use of existing code or proprietary components. The
system uses a SQL database to store the data from the instruments and provides
an online application to display and browse through the data. It allows the
modification of device settings while the program is running and features a
protocol to handle exceptions, including the automated distribution of alarm
messages. We present two case studies from astroparticle physics, on which
Doberman is successfully deployed: a low-background screening facility
installed in a remote underground laboratory and a detector R&D platform using
cryogenic liquid xenon
Wie geht es dir wirklich? : Kompetenzkurs für Multiplikatorinnen und Multiplikatoren zur Stärkung der psychischen Gesundheit Jugendlicher
Darstellung des Themas: Jede zweite Person erlebt im Verlauf des Lebens eine psychische Störung. Da die meisten psychischen Störungen in der Jugend entstehen und sich im späteren Leben chronifizieren können, ist es wichtig, die psychische Gesundheit von Jugendlichen zu fördern und ihnen Unterstützungsangebote zu bieten.
Ziel: Diese Arbeit befasst sich mit der Entwicklung eines Kompetenzkurses für Multiplikator_innen zur Stärkung der psychischen Gesundheit Jugendlicher. Durch den Kurs wird die psychische Gesundheit von Jugendlichen gezielt gefördert und befähigt Multiplikator_innen, psychische Krisen bei Jugendlichen zu erkennen und bedarfsgerecht zu handeln.
Methodik: Mithilfe einer Literaturrecherche sind Quellen zur Datengrundlage ausgesucht worden. Aufbauend ist ein theoriebasiertes Pilotprojekt mit dem Projektmanagementtool Quint-Essenz konzipiert worden.
Zentrale Ergebnisse:
Die Literaturrecherche zeigt auf, dass der Kompetenzkurs einen Beitrag zur Schliessung der Lücke im psychiatrischen Versorgungssystem leistet. Das theoriebasierte Pilotprojekt trägt den Namen ensa teens, lehnt sich an das bisherige Programm ensa an und die Konzipierung ist in die Teilschritte Projektbegründung, Gesundheitsförderung, Projektplanung, Projektorganisation und Projektsteuerung unterteilt worden.
Schlussfolgerung: ensa teens ist eine Massnahme, welche Multiplikator_innen befähigt, Jugendliche in Krisensituationen zu unterstützen und psychische Auffälligkeiten zu erkennen. Die Implementierung des Pilotprojektes ist realisierbar, da es mehr Chancen als Risiken aufweist
How can expert knowledge increase the realism of conceptual hydrological models? : a case study based on the concept of dominant runoff process in the Swiss Pre-Alps
Both modellers and experimentalists agree that using expert knowledge can improve the realism of conceptual hydrological models. However, their use of expert knowledge differs for each step in the modelling procedure, which involves hydrologically mapping the dominant runoff processes (DRPs) occurring on a given catchment, parameterising these processes within a model, and allocating its parameters. Modellers generally use very simplified mapping approaches, applying their knowledge in constraining the model by defining parameter and process relational rules. In contrast, experimentalists usually prefer to invest all their detailed and qualitative knowledge about processes in obtaining as realistic spatial distribution of DRPs as possible, and in defining narrow value ranges for each model parameter.
Runoff simulations are affected by equifinality and numerous other uncertainty sources, which challenge the assumption that the more expert knowledge is used, the better will be the results obtained. To test for the extent to which expert knowledge can improve simulation results under uncertainty, we therefore applied a total of 60 modelling chain combinations forced by five rainfall datasets of increasing accuracy to four nested catchments in the Swiss Pre-Alps. These datasets include hourly precipitation data from automatic stations interpolated with Thiessen polygons and with the inverse distance weighting (IDW) method, as well as different spatial aggregations of Combiprecip, a combination between ground measurements and radar quantitative estimations of precipitation. To map the spatial distribution of the DRPs, three mapping approaches with different levels of involvement of expert knowledge were used to derive so-called process maps. Finally, both a typical modellers' top-down set-up relying on parameter and process constraints and an experimentalists' set-up based on bottom-up thinking and on field expertise were implemented using a newly developed process-based runoff generation module (RGM-PRO). To quantify the uncertainty originating from forcing data, process maps, model parameterisation, and parameter allocation strategy, an analysis of variance (ANOVA) was performed.
The simulation results showed that (i) the modelling chains based on the most complex process maps performed slightly better than those based on less expert knowledge; (ii) the bottom-up set-up performed better than the top-down one when simulating short-duration events, but similarly to the top-down set-up when simulating long-duration events; (iii) the differences in performance arising from the different forcing data were due to compensation effects; and (iv) the bottom-up set-up can help identify uncertainty sources, but is prone to overconfidence problems, whereas the top-down set-up seems to accommodate uncertainties in the input data best. Overall, modellers' and experimentalists' concept of model realism differ. This means that the level of detail a model should have to accurately reproduce the DRPs expected must be agreed in advance
Experimentation with Animals: A Key Aspect of the 3Rs. The Genetic Quality
The genetic quality of laboratory animals is essential for reproducibility of scientific research. Working with animals of certifiedgenetic quality is still a pending issue in Argentina due to the lack of routine genetic controls, of information on the genetic background of animals and of proper training. Apart from being concerned with having their results published and getting funding for research, scientists should know the genetic origin of laboratory animals. Consequently, they should perform genetic controls to verifywhether animal integrity has been compromised by accidental genetic contamination or genetic drift. The aim of this work was toevaluate the genetic purity of the inbred C57BL/6J mouse strain from three animal facilities belonging to the Buenos Aires UniversitySchool of Medicine network by analyzing a panel of microsatellite markers. Female mice tail samples (3-5 mm) were taken and genomic DNA was obtained by organic extraction. The genetic profile of each animal was determined by PCR-fragment analysis, usingmicrosatellites D1Mit155, D2Mit493, D3Mit49, D13Mit13, D6Mit8 and D12Mit12, located on six different autosomal chromosomesand selected from the Mouse Genome Informatics database (www.informatics.jax.org/searches). The results obtained provided keydata on the genetic quality of the three inbred animal colonies studied. They also served as an example for other laboratory animalfacilities in Argentina and as a starting point to modify the conditions and management of laboratory animal colonies. We determinedthe genetic purity of the inbred C57BL/6J mouse strain in all animal facilities evaluated. All six loci analyzed were homozygous,certifying their isogenicity and phenotypic uniformity. These results are promising for animal facilities mainly performing biomedical research. They also show a positive evolution in handling animal colonies and use of the 3Rs, and researcher commitment withanimal science, since they promote the supply of genetically quality-controlled animals. The positive impact of these results shouldencourage other researchers using this inbred strain to perform periodic genetic monitoring, thereby consolidating the supply ofquality-controlled mice. This pioneering study carried out in IGEVET (CONICET- UNLP) should consolidate the genetic monitoring ofinbred strains throughout the country.Fil: Lizarraga, Maria Alfonsina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Posik, Diego Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Zappa, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Castillo, Nadia Sabiela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Giovambattista, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentin
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