42,394 research outputs found
Dynamical Screening of Atom Confined by Finite-Width Fullerene
This is an investigation on the dynamical screening of an atom confined
within a fullerene of finite width. The two surfaces of the fullerene lead to
the presence of two surface plasmon eigenmodes. It is shown that, in the
vicinity of these two eigenfrequencies, there is a large enhancement of the
confined atom's photoabsorption rate.Comment: 10 pages, 4 figures correction of figure 2 and equation 1
A low-power opportunistic communication protocol for wearable applications
© 2015 IEEE.Recent trends in wearable applications demand flexible architectures being able to monitor people while they move in free-living environments. Current solutions use either store-download-offline processing or simple communication schemes with real-time streaming of sensor data. This limits the applicability of wearable applications to controlled environments (e.g, clinics, homes, or laboratories), because they need to maintain connectivity with the base station throughout the monitoring process. In this paper, we present the design and implementation of an opportunistic communication framework that simplifies the general use of wearable devices in free-living environments. It relies on a low-power data collection protocol that allows the end user to opportunistically, yet seamlessly manage the transmission of sensor data. We validate the feasibility of the framework by demonstrating its use for swimming, where the normal wireless communication is constantly interfered by the environment
On the next-to-next-to-leading order QCD corrections to heavy-quark production in deep-inelastic scattering
The contribution of quarks with masses m >> Lambda_QCD is the only part of
the structure functions in deep-inelastic scattering (DIS) which is not yet
known at the next-to-next-to-leading order (NNLO) of perturbative QCD. We
present improved partial NNLO results for the most important structure function
F_2(x,Q^2) near the partonic threshold, in the high-energy (small-x) limit and
at high scales Q^2 >> m^2; and employ these results to construct approximations
for the gluon and quark coefficient functions which cover the full kinematic
plane. The approximation uncertainties are carefully investigated, and found to
be large only at very small values, x smaller about 10^-3, of the Bjorken
variable.Comment: 62 pages, LaTeX, 13 figures. Erratum for eq.(B.7
A copula model for dependent competing risks
"Many popular estimators for duration models require independent competing risks or independent censoring. In contrast, copula based estimators are also consistent in presence of dependent competing risks. In this paper we suggest a computationally convenient extension of the Copula Graphic Estimator (Zheng and Klein, 1995) to a model with more than two dependent competing risks. We analyse the applicability of this estimator by means of simulations and real world unemployment duration data from Germany. We obtain evidence that our estimator yields nice results if the dependence structure is known and that it is a powerful tool for the assessment of the relevance of (in-)dependence assumptions in applied duration research." (Author's abstract, IAB-Doku) ((en)) Additional Information Appendix for the FDZ-Methodenreport No. 02/2009Risikoabschätzung - Modell, Wirkungsforschung - Methode, Methodologie, Arbeitsmarktpolitik - Erfolgskontrolle, ältere Arbeitnehmer, Leistungsanspruch - Dauer, Arbeitslosigkeitsdauer, IAB-Beschäftigtenstichprobe
Decoherence in a fermion environment: Non-Markovianity and Orthogonality Catastrophe
We analyze the non-Markovian character of the dynamics of an open two-level
atom interacting with a gas of ultra-cold fermions. In particular, we discuss
the connection between the phenomena of orthogonality catastrophe and Fermi
edge singularity occurring in such a kind of environment and the memory-keeping
effects which are displayed in the time evolution of the open system
Bounds analysis of competing risks : a nonparametric evaluation of the effect of unemployment benefits on migration in Germany
"In this paper we derive nonparametric bounds for the cumulative incidence curve within a competing risks model with partly identified interval data. As an advantage over earlier attempts our approach also gives valid results in case of dependent competing risks. We apply our framework to empirically evaluate the effect of unemployment benefits on observed migration of unemployed workers in Germany. Our findings weakly indicate that reducing the entitlement length for unemployment benefits increases migration among high-skilled individuals." (Author's abstract, IAB-Doku) ((en))Arbeitslosenunterstützung, Leistungsanspruch - Dauer, Binnenwanderung, regionale Mobilität, Wanderungsmotivation, Mobilitätsbereitschaft, Arbeitslose, Hochqualifizierte, IAB-Beschäftigtenstichprobe
Bounds Analysis of Competing Risks: A Nonparametric Evaluation of the Effect of Unemployment Benefits on Imigration in Germany
In this paper we derive nonparametric bounds for the cumulative incidence curve within a competing risks model with partly identified interval data. As an advantage over earlier attempts our approach also gives valid results in case of dependent competing risks. We apply our framework to empirically evaluate the effect of unemployment benefits on observed migration of unemployed workers in Germany. Our findings weakly indicate that reducing the entitlement length for unemployment benefits increases migration among high-skilled individuals. --cumulative incidence curve,partially missing data,bounds analysis,difference-in-differences
Vacancy decay in endohedral atoms: the role of non-central position of the atom
We demonstrate that the Auger decay rate in an endohedral atom is very
sensitive to the atom's location in the fullerene cage. Two additional decay
channels appear in an endohedral system: (a) the channel due to the change in
the electric field at the atom caused by dynamic polarization of the fullerene
electron shell by the Coulomb field of the vacancy, (b) the channel within
which the released energy is transferred to the fullerene electron via the
Coulomb interaction. % The relative magnitudes of the correction terms are
dependent not only on the position of the doped atom but also on the transition
energy \om. Additional enhancement of the decay rate appears for transitions
whose energies are in the vicinity of the fullerene surface plasmons energies
of high multipolarity. % It is demonstrated that in many cases the additional
channels can dominate over the direct Auger decay resulting in pronounced
broadening of the atomic emission lines. % The case study, carried out for
Sc@C, shows that narrow autoionizing resonances in an
isolated Sc within the range \om = 30... 45 eV are dramatically
broadened if the ion is located strongly off-the-center. % Using the developed
model we carry out quantitative analysis of the photoionization spectrum for
the endohedral complex ScN@C and demonstrate that the additional
channels are partly responsible for the strong modification of the
photoionization spectrum profile detected experimentally by
M\"{u}ller et al. (J. Phys.: Conf. Ser. 88, 012038 (2008)).Comment: 32 pages, 11 figure
Bounds analysis of competing risks : a nonparametric evaluation of the effect of unemployment benefits on migration in Germany (Revised version of the FDZ Methodenbericht No. 04/2007)
"This paper suggests an approach for analyzing a dependent competing risks model in presence of partly identified interval data. We apply our nonparametric bounds framework to empirically evaluate the effect of unemployment benefits on the cumulative incidence of local job finding and inter-regional migration of unemployed workers in Germany. Our findings indicate that reducing the entitlement length for unemployment benefits has heterogenous effects depending on the household composition and the wage replacement ratio in absence of unemployment benefits." (Author's abstract, IAB-Doku) ((en))Arbeitslosenunterstützung, Leistungsanspruch - Dauer, Binnenwanderung, regionale Mobilität, Wanderungsmotivation, Mobilitätsbereitschaft, Arbeitslose, Hochqualifizierte, IAB-Beschäftigtenstichprobe
Morphological variation of the newly confirmed population of the javelin sand boa, Eryx jaculus (Linnaeus, 1758) (Serpentes, erycidae) in Sicily, Italy
The presence of the Javelin sand boa in Sicily has recently been confirmed. Here the morphological characters and sexual dimorphism of the Sicilian population of Eryx jaculus are presented. Seven meristic and six metric characters in 96 specimens from Sicily were examined. The results show that tail length, snout-vent length, the distance between nostrils and the number of ventral and subcaudal scales are different between sexes. The characters found in the Sicilian population of the Javelin sand boa resemble those of the African population (ssp. jaculus) rather than the Eurasian population (ssp. turcicus), but biomolecular studies are necessary to understand its taxonomic identity
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