4,105 research outputs found
Ultra-low Q values for neutrino mass measurements
We investigate weak nuclear decays with extremely small kinetic energy
release (Q value) and thus extremely good sensitivity to the absolute neutrino
mass scale. In particular, we consider decays into excited daughter states, and
we show that partial ionization of the parent atom can help to tune Q values to
<< 1 keV. We discuss several candidate isotopes undergoing beta+, beta-, bound
state beta, or electron capture decay, and come to the conclusion that a
neutrino mass measurement using low-Q decays might only be feasible if no
ionization is required, and if future improvements in isotope production
technology, nuclear mass spectroscopy, and atomic structure calculations are
possible. Experiments using ions, however, are extremely challenging due to the
large number of ions that must be stored. New precision data on nuclear
excitation levels could help to identify further isotopes with low-Q decay
modes and possibly less challenging requirements.Comment: 7 pages, 2 figures; v2: Typos corrected, references adde
The GSI anomaly
Recently, an experiment at GSI Darmstadt has observed oscillating decay rates
of heavy ions. Several controversial attempts have been made to explain this
effect in terms of neutrino mixing. We briefly describe the experimental
results, give an overview of the literature, and show that the effect cannot be
due to neutrino mixing. If the effect survives, it could, however, be explained
by hypothetical internal excitations of the mother ions (~ 10^(-15) eV).Comment: Contribution to the Proceedings of Neutrino 2008, based on a talk by
M. Lindner and on a poster by the author
Progress on Advanced Cryo-Tanks Structural Design Achieved in CHATT-Project
The EU-FP7-funded study called CHATT (Cryogenic Hypersonic Advanced Tank Technologies) was initiated early 2012 and successfully finished in June 2015. One of its core objectives has been the investigation of Carbon Fiber Reinforced Plastic (CFRP) cryogenic pressure tanks.
The focus of the paper is on the technology development tasks of the study and its major obtained results including manufacturing and testing of four subscale tanks
NOVEL HYPERSONIC LAUNCHER CONCEPT USING THIN-PLY CFRP COMPOSITES
Thin-ply carbon fibre reinforced plastic (CFRP) composites may allow for significant structural mass reductions of space launch vehicles, and could even become a break-through technology for space transportation. To evaluate the potential mass savings and their implications for the feasibility of novel launcher configurations, the Aurora hypersonic launcher studies were initiated in late-2015/early-2016. The task of these studies is to define a series of spaceplane type launchers using thin-ply CFRP composites, to quantify the weight saving potential on vehicle level when using thin-ply composites as well as the latest technologies in other areas, and eventually to evaluate whether new types of launch vehicles can be realized that are infeasible with conventional technology.
This paper will provide a brief overview of the thin-ply technology and will discuss a first evaluation of vehicle level mass savings for a rocket propelled Aurora configuration. The vehicle system design and structural analysis approaches are still simplified, but do nevertheless allow for a first order assessment of the relative mass saving potentials compared to conventional structures.
The preliminary results presented in this paper indicate that thin-ply composites could indeed lead to large scale mass savings on vehicle level, and encourage to further advance this promising technology. Finally, the paper provides an outlook on the future development line of Aurora and associated technologies
Irradiance Variations of the Sun and Sun-Like Stars -- Overview of Topical Collection
This topical collection summarizes recent advances in observing and modeling
irradiance variations of the Sun and Sun-like stars, emphasizing the links
between surface magnetic fields and the resulting solar and stellar
variability. In particular, the articles composing this collection summarize
recent progress in i) solar-irradiance measurements; ii) modeling of solar- and
stellar-irradiance variability; and iii) understanding of the effects of such
variability on Earth's climate and exoplanet environments. This
topical-collection overview article gives background and more details on these
aspects of variability.Comment: accepted for Solar Physic
Anaphylactic reaction at a pizzeria in a 13-year-old female patient
<jats:title>Abstract</jats:title><jats:sec>
<jats:title>Purpose of Review</jats:title>
<jats:p><jats:italic>Mycoplasma</jats:italic>, economically important pathogens in livestock, often establishes immunologically complex persistent infections that drive their pathogenesis and complicate prophylaxis and therapy of the caused diseases. In this review, we summarize some of the recent findings concerning cellular and molecular persistence mechanisms related to the pathogenesis of mycoplasma infections in livestock.</jats:p>
</jats:sec><jats:sec>
<jats:title>Recent Findings</jats:title>
<jats:p>Data from recent studies prove several mechanisms including intracellular lifestyle, immune dysregulation, and autoimmunity as well as microcolony and biofilm formation and apoptosis of different host cell types as important persistence mechanisms in several clinically significant <jats:italic>Mycoplasma</jats:italic> species, i.e., <jats:italic>M. bovis</jats:italic>, <jats:italic>M</jats:italic>. <jats:italic>gallisepticum</jats:italic>, <jats:italic>M. hyopneumoniae</jats:italic>, and <jats:italic>M</jats:italic>. <jats:italic>suis</jats:italic>.</jats:p>
</jats:sec><jats:sec>
<jats:title>Summary</jats:title>
<jats:p>Evasion of the immune system and the establishment of persistent infections are key features in the pathogenesis of livestock mycoplasmas. In-depth knowledge of the underlying mechanisms will provide the basis for the development of therapy and prophylaxis strategies against mycoplasma infections.</jats:p>
</jats:sec>
Self-Calibration of Neutrino Detectors using characteristic Backgrounds
We introduce the possibility to use characteristic natural neutrino
backgrounds, such as Geoneutrinos (\bar{\nu}_e) or solar neutrinos (\nu_e),
with known spectral shape for the energy calibration of future neutrino
detectors, e.g. Large Liquid Scintillator Detectors. This "CalEffect" could be
used without the need to apply any modifications to the experiment in all
situations where one has a suitable background with sufficient statistics.
After deriving the effect analytically using \chi^2 statistics, we show that it
is only tiny for reactor neutrino experiments, but can be applicable in other
situations. As an example, we present its impact on the identification of the
wiggles in the power spectrum of supernova neutrinos caused by Earth matter
effects. The Self-Calibration Effect could be used for cross checking other
calibration methods and to resolve systematical effects in the primary neutrino
interaction processes, in particular in the low energy cross sections.Comment: 6 pages, 4 figure
Gegenstand und Oberfläche. Morton Feldmans Gedanken über die Beziehung von Kunst und Musik
Feldman erläutert das "Thema seiner Musik" in dem im September 1969 entstandenen Aufsatz "Between categories" (Feldman 1985, S. 40) und kommt dabei direkt auf das Verhältnis Kunst/Musik zu sprechen. Hierbei trifft Feldman die Unterscheidung, daß ein Kunstwerk in bezug auf seinen Gegenstand oder in bezug zu seiner Oberfläche interpretiert werden kann. (DIPF/Orig.
Pyrenean pastoralists observations of environmental change: an exploratory study in Los Valles Occidentales of Aragón
21 páginas, 3 tablas[EN] Observations of environmental change by local resource users
may be an important source of information about past and current environmental
conditions to complement scientific studies and monitoring. In this exploratory,
qualitative study, we documented observations of environmental change made by 27
stockmen in the two westernmost valleys of the Central Western Pyrenees of Spain.
Pastoralists reported changes in weather, corresponding declines in the flow of
mountain springs, and an increase in shrub and tree cover in the mountains.
Explanations for the increase in woody plant cover differed in the two valleys; however,
the majority of stockmen from both villages believed that the lack of human
presence in the mountains contributes to shrub encroachment. Stockmen’s observations
of environmental change suggest additional research needs regarding climate
and vegetation change in the Pyrenees, and highlight the potential contributions of
Pyrenean pastoralists’ local knowledge to environmental monitoring, research and
management.[ES] Las observaciones sobre el cambio medioambiental realizadas por usuarios locales pueden ser una importante fuente de información sobre las caracterÃsticas medioambientales del pasado y del presente para complementar los estudios cientÃficos y el monitoreo. En este estudio cualitativo documentamos observaciones sobre el cambio medioambiental realizadas por 27 ganaderos en los dos valles más occidentales de los Pirineos centro occidentales españoles. Resumen cambios climáticos relativos a la disminución del caudal de las fuentes de montaña y al aumento de la cubierta vegetal de matorrales y arbolado en las montañas. Las explicaciones sobre el aumento de arbolado difieren en los dos valles; sin embargo la mayorÃa de los ganaderos de ambos pueblos pensaban que la falta de presencia humana en las montañas contribuye a la invasión del matorral. Las observaciones de los ganaderos sobre los cambios medioambientales sugieren la necesidad de investigaciones adicionales sobre los cambios climáticos y de vegetación en los Pirineos y evidencian las potenciales contribuciones del conocimiento local de los ganaderos para el monitoreo medioambiental, la investigación y la gestión.
Las observaciones sobre el cambio medioambiental realizadas por usuarios locales pueden ser una importante fuente de información sobre las caracterÃsticas medioambientales del pasado y del presente para complementar los estudios cientÃficos y el monitoreo. En este estudio cualitativo documentamos observaciones sobre el cambio medioambiental realizadas por 27 ganaderos en los dos valles más occidentales de los Pirineos centro occidentales españoles. Resumen cambios climáticos relativos a la disminución del caudal de las fuentes de montaña y al aumento de la cubierta vegetal de matorrales y arbolado en las montañas. Las explicaciones sobre el aumento de arbolado difieren en los dos valles; sin embargo la mayorÃa de los ganaderos de ambos pueblos pensaban que la falta de presencia humana en las montañas contribuye a la invasión del matorral. Las observaciones de los ganaderos sobre los cambios medioambientales sugieren la necesidad de investigaciones adicionales sobre los cambios climáticos y de vegetación en los Pirineos y evidencian las potenciales contribuciones del conocimiento local de los ganaderos para el monitoreo medioambiental, la investigación y la gestión.We thank the stockmen and residents of the Valleys of Ansó and Hecho for
their time and participation; the administrations of the municipalities of Ansó
and Hecho, and the Office of Economic Development of the Comarca of Jaca,
for their assistance and cooperation; Javier Agguirre for helpful suggestions
on our interview protocol, and Isabel Catalán Barrio and Guillermo Bueno for
their reviews of an earlier version of this manuscript. This research was supported
in part by Fellowships from the Spanish Fulbright Commission and
the Center for Collaborative Conservation at Colorado State University.Peer reviewe
High-Thrust in-Space Liquid Propulsion Stage: Storable Propellants
In the frame of a project funded by ESA, a consortium led by Avio in cooperation with Snecma, Cira, and DLR is performing the preliminary design of a High-Thrust in-Space Liquid Propulsion Stage for two different types of manned missions beyond Earth orbit. For these missions, one or two 100 ton stages are to be used to propel a manned vehicle. Three different propellant combinations; LOx/LH2, LOx/CH4 and MON-3/MMH are being compared.
The preliminary design of the storable variant (MON-3/MMH) has been performed by DLR. The Aestus II engine with a large nozzle expansion ratio has been chosen as baseline. A first iteration has demonstrated, that it indeed provides the best performance for the storable propellant combination, when considering all engines available today or which may be available in a short- to medium term. The RD-861 K engine has been proposed as alternative to reduce the development duration of the high-thrust stage. Structure analyses and optimisations have converged towards a common bulkhead architecture with a Whipple shield, similar to the one used on the ATV, to protect the main propellant tanks against perforations caused by meteoroids and space debris. The propulsion system has been built around six Aestus II engines equipped with TVC and placed on a circular engine thrust frame. The RCS, the thermal system, and the power system have also been included in the preliminary design, and they have been sized for the most demanding mission. The performance of the high-thrust stage, resulting from the preliminary design, has been assessed for both missions taken into consideration
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