1,361 research outputs found
Temporal Lossy In-Situ Compression for Computational Fluid Dynamics Simulations
Während CFD Simulationen für Metallschmelze im Rahmen des SFB920 fallen auf dem Taurus HPC Cluster in Dresden sehr große Datenmengen an, deren Handhabung den wissenschaftlichen Arbeitsablauf stark verlangsamen. Zum einen ist der Transfer in Visualisierungssysteme nur unter hohem Zeitaufwand möglich. Zum anderen ist interaktive Analyse von zeitlich abhängigen Prozessen auf Grund des Speicherflaschenhalses nahezu unmöglich. Aus diesen Gründen beschäftigt sich die vorliegende Dissertation mit der Entwicklung sog. Temporaler In-Situ Kompression für wissenschaftliche Daten direkt innerhalb von CFD Simulationen. Dabei werden mittels neuer Quantisierungsverfahren die Daten auf ~10% komprimiert, wobei dekomprimierte Daten einen Fehler von maximal 1% aufweisen. Im Gegensatz zu nicht-temporaler Kompression, wird bei temporaler Kompression der Unterschied zwischen Zeitschritten komprimiert, um den Kompressionsgrad zu erhöhen. Da die Datenmenge um ein Vielfaches kleiner ist, werden Kosten für die Speicherung und die Übertragung gesenkt. Da Kompression, Transfer und Dekompression bis zu 4 mal schneller ablaufen als der Transfer von unkomprimierten Daten, wird der wissenschaftliche Arbeitsablauf beschleunigt
A Comprehensive Survey of the Problems of Old Age, Past and Present Solutions Offered for Them, and the Obligation of the Church with Regard to Them
Many secular agencies are delving into this problem. Instead of pointing the way as prophet, the church has been content to follow in the wake. The purpose of this thesis is to stimulate the church and its charitable agencies to find better more adequate means to care for the aged Christians. Insurance companies are aware of the increasing number of aged. Political parties are aware of the potential voting strength they have. The church must also be aware of their needs and requirements, and be prepared to fill them on a much grander scale than ever before
Spectrum Analysis of Bright Kepler Gamma Doradus Candidate Stars
Ground-based spectroscopic follow-up observations of the pulsating stars
observed by the Kepler satellite mission are needed for their asteroseismic
modelling. We aim to derive the fundamental parameters for a sample of 26 Gamma
Doradus candidate stars observed by the Kepler satellite mission to accomplish
one of the required preconditions for their asteroseismic modelling and to
compare our results with the types of pulsators expected from the existing
light curve analysis. We use the spectrum synthesis method to derive the
fundamental parameters like Teff, logg, [M/H], and vsini from newly obtained
spectra and compute the spectral energy distribution from literature photometry
to get an independent measure of Teff. We find that most of the derived Teff
values agree with the values given in the Kepler Input Catalogue. According to
their positions in the HR-diagram three stars are expected Gamma Dor stars, ten
stars are expected Delta Sct stars, and seven stars are possibly Delta Sct
stars at the hot border of the instability strip. Four stars in our sample are
found to be spectroscopic binary candidates and four stars have very low
metallicity where two show about solar C abundance. Six of the 10 stars located
in the Delta Sct instability region of the HR-diagram show both Delta Sct and
Gamma Dor-type oscillations in their light curves implying that Gamma Dor-like
oscillations are much more common among the Delta Sct stars than predicted by
theory. Moreover, seven stars showing periods in the Delta Sct and the Delta
Sct-Gamma Dor range in their light curves are located in the HR-diagram left of
the blue edge of the theoretical Delta Sct instability strip. The consistency
of these findings with recent investigations based on high-quality Kepler data
implies the need for a revision of the theoretical Gamma Dor and Delta Sct
instability strips.Comment: 10 pages, 3 figures, 7 tables; accepted for publication in MNRA
KIC 7177553: a quadruple system of two close binaries
KIC 7177553 was observed by the Kepler satellite to be an eclipsing eccentric binary star system with an 18-day orbital period. Recently, an eclipse timing study of the Kepler binaries has revealed eclipse timing variations (ETVs) in this object with an amplitude of ~100 s and an outer period of 529 days. The implied mass of the third body is that of a super-Jupiter, but below the mass of a brown dwarf. We therefore embarked on a radial velocity (RV) study of this binary to determine its system configuration and to check the hypothesis that it hosts a giant planet. From the RV measurements, it became immediately obvious that the same Kepler target contains another eccentric binary, this one with a 16.5-day orbital period. Direct imaging using adaptive optics reveals that the two binaries are separated by 0”.4 (~167 AU) and have nearly the same magnitude (to within 2%). The close angular proximity of the two binaries and very similar γ velocities strongly suggest that KIC 7177553 is one of the rare SB4 systems consisting of two eccentric binaries where at least one system is eclipsing. Both systems consist of slowly rotating, nonevolved, solar-like stars of comparable masses. From the orbital separation and the small difference in γ velocity, we infer that the period of the outer orbit most likely lies in the range of 1000–3000 yr. New images taken over the next few years, as well as the high-precision astrometry of the Gaia satellite mission, will allow us to set much narrower constraints on the system geometry. Finally, we note that the observed ETVs in the Kepler data cannot be produced by the second binary. Further spectroscopic observations on a longer timescale will be required to prove the existence of the massive planet
HD 51106 and HD 50747: an ellipsoidal binary and a triple system observed with CoRoT
We present an analysis of the observations of HD 51106 and HD 50747 by the
satellite CoRoT, obtained during its initial run, and of the spectroscopic
preparatory observations.
AIMS: We complete an analysis of the light curve, extract the main
frequencies observed, and discuss some preliminary interpretations about the
stars.
Methods: We used standard Fourier transform and pre-whitening methods to
extract information about the periodicities of the stars.
Results: HD 51106 is an ellipsoidal binary, the light curve of which can be
completely explained by the tidal deformation of the star and smaller secondary
effects. HD 50747 is a triple system containing a variable star, which exhibits
many modes of oscillation with periods in the range of a few hours. On the
basis of this period range and the analysis of the physical parameters of the
star, we conclude that HD 50747 is a Gamma-Doradus star.Comment: 7 pages, 8 figures, use (Astronomy-Astrophysics format/macro LAtex
Devitalization of Glioblastoma Cancer Cells by Non-invasive Physical Plasma: Modulation of Proliferative Signalling Cascades
Background/Aim: Glioblastoma (GBM) is the most common and most lethal type of cancer of the central nervous system in adults. Despite aggressive treatment, which is based on surgical resection, if possible, followed by radiation and chemotherapy, a high recurrence rate and therapy resistance is observed. Thus, additional innovative therapies are urgently needed to improve the poor median survival of only 15 months. Treatment of solid tumours with non-invasive physical plasma (NIPP) represents such a novel and innovative anticancer procedure. Materials and Methods: In this study, we investigated the effect of NIPP, an ionized argon gas, on the in vitro growth of human GBM cell lines, LN-18 and U-87 MG. Proliferation was measured by live cell count. Subsequently, proliferative factors were analysed at the level of nucleic acids (polymerase chain reaction) and proteins (western blotting). Results: For both GBM lines, a treatment time-dependent decrease in growth was observed compared to controls. Additionally, NIPP treatment resulted in reduced rates of AKT serine/threonine kinase 1 (AKT1) and extracellular-regulated kinase 1/2 ERK1/2 expression, whereas expression of p21, proliferating cell nuclear antigen, and heat-shock proteins 90α and 90β was not affected. In both cell lines, a strong increase in expression of tumour-suppressive microRNA-1 (miR-1) was detected after exposure to NIPP. Conclusion: Our results demonstrated that NIPP is able to efficiently attenuate growth of GBM cells and suggest AKT1, ERK1/2 and miR-1 to be pivotal factors of NIPP-modulated cellular signalling. Translated into the clinical setting, NIPP may represent a promising option for the treatment of GBM
A 1-D modelling of streaming potential dependence on water content during drainage experiment in sand
The understanding of electrokinetics for unsaturated conditions is crucial
for numerous of geophysical data interpretation. Nevertheless, the behaviour of
the streaming potential coefficient C as a function of the water saturation Sw
is still discussed. We propose here to model both the Richards' equation for
hydrodynamics and the Poisson's equation for electrical potential for
unsaturated conditions using 1-D finite element method. The equations are first
presented and the numerical scheme is then detailed for the Poisson's equation.
Then, computed streaming potentials (SPs) are compared to recently published SP
measurements carried out during drainage experiment in a sand column. We show
that the apparent measurement of DV / DP for the dipoles can provide the SP
coefficient in these conditions. Two tests have been performed using existing
models for the SP coefficient and a third one using a new relation. The results
show that existing models of unsaturated SP coefficients C(Sw) provide poor
results in terms of SP magnitude and behaviour. We demonstrate that the
unsaturated SP coefficient can be until one order of magnitude larger than
Csat, its value at saturation. We finally prove that the SP coefficient follows
a non-monotonous behaviour with respect to water saturation. Key words:
Electrical properties; Electromagnetic theory; Hydrogeophysics; Hydrology;
Permeability and porosity; electrokinetic; streaming potential; self-potential;
water content; water saturation; unsaturated condition; finite element modelin
The development of memory maintenance strategies:Training cumulative rehearsal and interactive imagery in children aged between 5 and 9
The current study explored the extent to which children above and below the age of 7 years are able to benefit from either training in cumulative rehearsal or in the use of interactive imagery when carrying out working memory tasks. Twenty-four 5- to 6-year-olds and 24 8- to 9-year olds were each assigned to one of three training groups who either received cumulative rehearsal, interactive imagery, or passive labelling training. Participants’ ability to maintain material during a filled delay was then assessed, and the nature of the distraction that was imposed during this delay was varied to shed further light on the mechanisms that individuals used to maintain the memoranda in working memory in the face of this distraction. The results suggest that the rehearsal training employed here did improve recall by virtue of encouraging rehearsal strategies, in a way that was not observed among participants receiving interactive imagery training. The fact that these effects were not mediated by age group counts against the view that younger individuals are either unable to rehearse, or show impoverished verbal serial recall because they do not spontaneously engage in rehearsal
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