865 research outputs found
A semiclassical analysis of the Efimov energy spectrum in the unitary limit
We demonstrate that the (s-wave) geometric spectrum of the Efimov energy
levels in the unitary limit is generated by the radial motion of a primitive
periodic orbit (and its harmonics) of the corresponding classical system. The
action of the primitive orbit depends logarithmically on the energy. It is
shown to be consistent with an inverse-squared radial potential with a lower
cut-off radius. The lowest-order WKB quantization, including the Langer
correction, is shown to reproduce the geometric scaling of the energy spectrum.
The (WKB) mean-squared radii of the Efimov states scale geometrically like the
inverse of their energies. The WKB wavefunctions, regularized near the
classical turning point by Langer's generalized connection formula, are
practically indistinguishable from the exact wave functions even for the lowest
() state, apart from a tiny shift of its zeros that remains constant for
large .Comment: LaTeX (revtex 4), 18pp., 4 Figs., already published in Phys. Rev. A
but here a note with a new referece is added on p. 1
The interaction of core-collapse supernova ejecta with a companion star
The progenitors of many CCSNe are expected to be in binary systems. After the
SN explosion, the companion may suffer from mass stripping and be shock heated
as a result of the impact of the SN ejecta. If the binary system is disrupted,
the companion is ejected as a runaway and hypervelocity star. By performing a
series of 3D hydrodynamical simulations of the collision of SN ejecta with the
companion star, we investigate how CCSN explosions affect their companions. We
use the BEC code to construct the detailed companion structure at the time of
SN explosion. The impact of the SN blast wave on the companion is followed by
means of 3D SPH simulations using the Stellar GADGET code. For main-sequence
(MS) companions, we find that the amount of removed mass, impact velocity, and
chemical contamination of the companion that results from the impact of the SN
ejecta, strongly increases with decreasing binary separation and increasing
explosion energy. Their relationship can be approximately fitted by power laws,
which is consistent with the results obtained from impact simulations of
SNe~Ia. However, we find that the impact velocity is sensitive to the momentum
profile of the outer SN ejecta and, in fact, may decrease with increasing
ejecta mass, depending on the modeling of the ejecta. Because most companions
to Ib/c CCSNe are in their MS phase at the moment of the explosion, combined
with the strongly decaying impact effects with increasing binary separation, we
argue that the majority of these SNe lead to inefficient mass stripping and
shock heating of the companion star following the impact of the ejecta. Our
simulations show that the impact effects of Ib/c SN ejecta on the structure of
MS companions, and thus their long-term post-explosion evolution, is in general
not dramatic. We find that at most 10% of their mass is lost, and their
resulting impact velocities are less than 100 km/s.Comment: Accepted for publication in Astronomy and Astrophysics, some minor
typographical errors are fixed, the affiliation of second author is correcte
Towards Picogram Detection of Superparamagnetic Iron-Oxide Particles Using a Gradiometric Receive Coil
Superparamagnetic iron-oxide nanoparticles can be used in a variety of
medical applications like vascular or targeted imaging. Magnetic particle
imaging (MPI) is a promising tomographic imaging technique that allows
visualizing the 3D nanoparticle distribution concentration in a non-invasive
manner. The two main strengths of MPI are high temporal resolution and high
sensitivity. While the first has been proven in the assessment of dynamic
processes like cardiac imaging, it is unknown how far the detection limit of
MPI can be lowered. Within this work, we will present a highly sensitive
gradiometric receive-coil unit combined with a noise-matching network tailored
for the measurement of mice. The setup is capable of detecting 5 ng of iron in
vitro at 2.14 sec acquisition time. In terms of iron concentration we are able
to detect 156 {\mu}g/L marking the lowest value that has been reported for an
MPI scanner so far. In vivo MPI mouse images of a 512 ng bolus at 21.5 ms
acquisition time allow for capturing the flow of an intravenously injected
tracer through the heart of a mouse. Since it has been rather difficult to
compare detection limits across MPI publications we propose guidelines
improving the comparability of future MPI studies.Comment: 15 Pages, 7 Figures, V2: Changed the initials of Author Kannan M
Krishnan, added two citations, corrected typo
Empirical competence-testing: A psychometric examination of the German version of the Emotional Competence Inventory
The “Emotional Competence Inventory“ (ECI 2.0) by Goleman and Boyatzis assesses emotional intelligence (EI) in organizational context by means of 72 items in 4 clusters (self-awareness, self- management, social awareness, social skills) which at large consist of 18 competencies. Our study examines the psychometric properties of the first German translation of this instrument in two different surveys (N = 236). If all items are included in reliability analysis the ECI is reliable (Cronbach’s Alpha = .90), whereas the reliability of the four sub dimensions is much smaller (Alpha = .62 - .81). For 43 items the corrected item-total correlation with its own scale is higher than correlations with the other three clusters. Convergent validity was examined by using another EI instrument (Wong & Law, 2002). We found a significant correlation between the two instruments (r = .41). The German version of the ECI seems to be quite useful, although the high reliability is achieved by a large number of items. Possibilities of improvement are discussed
Emotional Intelligence and its consequences for occupational and life satisfaction - Emotional Intelligence in the context of irrational beliefs
According to Albert Ellis' theory of Rational Emotive Behavior Therapy irrational beliefs (IB) lead to maladaptive emotions. A central component of irrationality is the denial of one's own possibilities to control important aspects of life. A specific IB is that one cannot control and thus cannot avoid certain emotion states. Emotion research considers regulative emotion control a pivotal component of the concept of emotional intelligence (EI). A negative association between IB and EI can thus be theoretically derived from both concepts. Furthermore both should be related to life satisfaction. We examined the relationship between IB and EI using standardized questionnaire instruments and the predictive value of both concepts regarding life satisfaction. We found a significant negative correlation between both conceptions (r = -.21). Life satisfaction and occupational satisfaction are better predicted by IB. R² increases from .04 to .12 when both concepts are incorporated in regression analysis
Numerical evolution of axisymmetric, isolated systems in General Relativity
We describe in this article a new code for evolving axisymmetric isolated
systems in general relativity. Such systems are described by asymptotically
flat space-times which have the property that they admit a conformal extension.
We are working directly in the extended `conformal' manifold and solve
numerically Friedrich's conformal field equations, which state that Einstein's
equations hold in the physical space-time. Because of the compactness of the
conformal space-time the entire space-time can be calculated on a finite
numerical grid. We describe in detail the numerical scheme, especially the
treatment of the axisymmetry and the boundary.Comment: 10 pages, 8 figures, uses revtex4, replaced with revised versio
Geriatrische Assessments und Diagnostik beim älteren Patienten
As is the case with younger patients, the treatment decisions for elderly patients with thoracic tumours are primarily based on the results of the usual routine diagnostics. Standardised assessments of existing comorbidities and geriatric assessments may provide information which are of particular relevance for intensive and/or complex therapy modalities and which may require early corresponding intervention or measures for support
1142 A new approach towards improved visualization of myocardial edema using T2-weighted imaging
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