7,888 research outputs found
Stability of Coalescence Hidden variable Fractal Interpolation Surfaces
In the present paper, the stability of Coalescence Hidden variable Fractal
Interpolation Surfaces(CHFIS) is established. The estimates on error in
approximation of the data generating function by CHFIS are found when there is
a perturbation in independent, dependent and hidden variables. It is proved
that any small perturbation in any of the variables of generalized
interpolation data results in only small perturbation of CHFIS. Our results are
likely to be useful in investigations of texture of surfaces arising from the
simulation of surfaces of rocks, sea surfaces, clouds and similar natural
objects wherein the generating function depends on more than one variable
Publishing in face of the COVID-19 pandemic
Doctors around the world are desperately looking for guidance to enable them to better manage their COVID-19 patients..
Pre-discovery observations of CoRoT-1b and CoRoT-2b with the BEST survey
The BEST wide-angle telescope installed at the Observatoire de Haute-Provence
and operated in remote control from Berlin by the Institut fuer
Planetenforschung, DLR, has observed the CoRoT target fields prior to the
mission. The resulting archive of stellar photometric lightcurves is used to
search for deep transit events announced during CoRoT's alarm-mode to aid in
fast photometric confirmation of these events. The "initial run" field of CoRoT
(IRa01) has been observed with BEST in November and December 2006 for 12
nights. The first "long run" field (LRc01) was observed from June to September
2005 for 35 nights. After standard CCD data reduction, aperture photometry has
been performed using the ISIS image subtraction method. About 30,000
lightcurves were obtained in each field. Transits of the first detected planets
by the CoRoT mission, CoRoT-1b and CoRoT-2b, were found in archived data of the
BEST survey and their lightcurves are presented here. Such detections provide
useful information at the early stage of the organization of follow-up
observations of satellite alarm-mode planet candidates. In addition, no period
change was found over ~4 years between the first BEST observation and last
available transit observations.Comment: AJ, accepte
Enhanced mobility of poly(3-hexylthiophene) transistors by spin-coating from high-boiling-point solvents
Efficient optical quantum information processing
Quantum information offers the promise of being able to perform certain
communication and computation tasks that cannot be done with conventional
information technology (IT). Optical Quantum Information Processing (QIP) holds
particular appeal, since it offers the prospect of communicating and computing
with the same type of qubit. Linear optical techniques have been shown to be
scalable, but the corresponding quantum computing circuits need many auxiliary
resources. Here we present an alternative approach to optical QIP, based on the
use of weak cross-Kerr nonlinearities and homodyne measurements. We show how
this approach provides the fundamental building blocks for highly efficient
non-absorbing single photon number resolving detectors, two qubit parity
detectors, Bell state measurements and finally near deterministic control-not
(CNOT) gates. These are essential QIP devicesComment: Accepted to the Journal of optics B special issue on optical quantum
computation; References update
Predicting total reaction cross sections for nucleon-nucleus scattering
Nucleon total reaction and neutron total cross sections to 300 MeV for 12C
and 208Pb, and for 65 MeV spanning the mass range, are predicted using
coordinate space optical potentials formed by full folding of effective
nucleon-nucleon interactions with realistic nuclear ground state densities.
Good to excellent agreement is found with existing data.Comment: 10 pages, 4 figure
Formation of the planet around the millisecond pulsar J1719-1438
Context. Recently the discovery of PSR J1719-1438, a 5.8 ms pulsar with a
companion in a 2.2 hr orbit, was reported. The combination of this orbital
period and the very low mass function is unique. The discoverers, Bailes et
al., proposed an ultracompact X-ray binary (UCXB) as the progenitor system.
However, the standard UCXB scenario would not produce this system as the time
required to reach this orbital period exceeds the current estimate of the age
of the Universe. The detached state of the system aggravates the problem. Aims.
We want to understand the evolutionary history of PSR J1719-1438, and determine
under which circumstances it could have evolved from an UCXB. Methods. We model
UCXB evolution varying the donor size and investigate the effect of a wind mass
loss from the donor, and compare the results with the observed characteristics
of PSR J1719-1438. Results. An UCXB can reach a 2.2 hr orbit within the age of
the Universe, provided that 1) the millisecond pulsar can significantly heat
and expand the donor by pulsar irradiation, or 2) the system loses extra
orbital angular momentum, e.g. via a fast wind from the donor. Conclusions. The
most likely scenario for the formation of PSR J1719-1438 is UCXB evolution
driven by angular momentum loss via the usual gravitational wave emission,
which is enhanced by angular momentum loss via a donor wind of ~3x10^-13
Msun/yr. Depending on the size of the donor during the evolution, the companion
presently probably has a mass of ~1-3 Jupiter masses, making it a very low mass
white dwarf as proposed by Bailes et al. Its composition can be either helium
or carbon-oxygen. A helium white dwarf companion makes the long (for an UCXB)
orbital period easier to explain, but the required inclination makes it a
priori less likely than a carbon-oxygen white dwarf.Comment: 5 pages, 4 figures. Accepted for publication in Astronomy and
Astrophysics. v2: Updated a referenc
Layer Features of the Lattice Gas Model for Self-Organized Criticality
A layer-by-layer description of the asymmetric lattice gas model for
1/f-noise suggested by Jensen [Phys. Rev. Lett. 64, 3103 (1990)] is presented.
The power spectra of the lattice layers in the direction perpendicular to the
particle flux is studied in order to understand how the white noise at the
input boundary evolves, on the average, into 1/f-noise for the system. The
effects of high boundary drive and uniform driving force on the power spectrum
of the total number of diffusing particles are considered. In the case of
nearest-neighbor particle interactions, high statistics simulation results show
that the power spectra of single lattice layers are characterized by different
exponents such that as one approaches the outer
boundary.Comment: LaTeX, figures upon reques
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