1,026 research outputs found
dotCall64: An Efficient Interface to Compiled C/C++ and Fortran Code Supporting Long Vectors
The R functions .C() and .Fortran() can be used to call compiled C/C++ and
Fortran code from R. This so-called foreign function interface is convenient,
since it does not require any interactions with the C API of R. However, it
does not support long vectors (i.e., vectors of more than 2^31 elements). To
overcome this limitation, the R package dotCall64 provides .C64(), which can be
used to call compiled C/C++ and Fortran functions. It transparently supports
long vectors and does the necessary castings to pass numeric R vectors to
64-bit integer arguments of the compiled code. Moreover, .C64() features a
mechanism to avoid unnecessary copies of function arguments, making it
efficient in terms of speed and memory usage.Comment: 17 page
Force-dependent unbinding rate of molecular motors from stationary optical trap data
Molecular motors walk along filaments until they detach stochastically with a
force-dependent unbinding rate. Here, we show that this unbinding rate can be
obtained from the analysis of experimental data of molecular motors moving in
stationary optical traps. Two complementary methods are presented, based on the
analysis of the distribution for the unbinding forces and of the motor's force
traces. In the first method, analytically derived force distributions for slip
bonds, slip-ideal bonds, and catch bonds are used to fit the cumulative
distributions of the unbinding forces. The second method is based on the
statistical analysis of the observed force traces. We validate both methods
with stochastic simulations and apply them to experimental data for kinesin-1
Fourth-Order Perturbation Theory for the Half-Filled Hubbard Model in Infinite Dimensions
We calculate the zero-temperature self-energy to fourth-order perturbation
theory in the Hubbard interaction for the half-filled Hubbard model in
infinite dimensions. For the Bethe lattice with bare bandwidth , we compare
our perturbative results for the self-energy, the single-particle density of
states, and the momentum distribution to those from approximate analytical and
numerical studies of the model. Results for the density of states from
perturbation theory at agree very well with those from the Dynamical
Mean-Field Theory treated with the Fixed-Energy Exact Diagonalization and with
the Dynamical Density-Matrix Renormalization Group. In contrast, our results
reveal the limited resolution of the Numerical Renormalization Group approach
in treating the Hubbard bands. The momentum distributions from all approximate
studies of the model are very similar in the regime where perturbation theory
is applicable, . Iterated Perturbation Theory overestimates the
quasiparticle weight above such moderate interaction strengths.Comment: 19 pages, 17 figures, submitted to EPJ
Analytical and Numerical Treatment of the Mott--Hubbard Insulator in Infinite Dimensions
We calculate the density of states in the half-filled Hubbard model on a
Bethe lattice with infinite connectivity. Based on our analytical results to
second order in , we propose a new `Fixed-Energy Exact Diagonalization'
scheme for the numerical study of the Dynamical Mean-Field Theory. Corroborated
by results from the Random Dispersion Approximation, we find that the gap opens
at . Moreover, the density of states near the gap
increases algebraically as a function of frequency with an exponent
in the insulating phase. We critically examine other analytical
and numerical approaches and specify their merits and limitations when applied
to the Mott--Hubbard insulator.Comment: 22 pages, 16 figures; minor changes (one reference added, included
comparison with Falicov-Kimball model
Wirkung bewegungsinduzierender Sitzmöbel im Unterricht auf die Lösungsfähigkeit bei Algebra und die Befindlichkeit
Die kognitive Leistungsfähigkeit ist eine grundlegende Voraussetzung für
die Bewältigung von Lerninhalten, die im Schulunterricht vermittelt werden.
Wissenschaftliche Studien belegen eine enge Verbindung von Motorik
und Kognition (z. B. Laufer, Ashkenazi & Josman, 2008), wobei unterschiedliche
Fragestellungen, wie etwa der Einfluss des Alters oder die Art
der motorisch-kognitiven Aufgaben ein weites Forschungsfeld eröffnen
und unterschiedliche Schlussfolgerungen über den Zusammenhang zulassen
(vgl. Szturm et al., 2013; Makizako, Furuna, Ihira & Shimada, 2013;
Van Impe et al., 2012). In der vorliegenden Studie wurde, basierend auf der
Grundannahme einer positiven Wirkung auf die kognitive Leistungsfähigkeit
durch Bewegungsinduktion während des Sitzens (vgl. Maus, Henz &
Schöllhorn, 2013), die Leistung bei Algebra sowie die subjektive Einschätzung
der Befindlichkeit unter bewegtem und statischem Sitzen getestet
Automated evaluation and comparison of grapevine genotypes by means of grape cluster architecture
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