308 research outputs found
Anomalous double peak structure in Nb/Ni superconductor/ferromagnet tunneling DOS
We have experimentally investigated the density of states (DOS) in Nb/Ni
(S/F) bilayers as a function of Ni thickness, . Our thinnest samples show
the usual DOS peak at , whereas intermediate-thickness samples
have an anomalous ``double-peak'' structure. For thicker samples ( nm), we see an ``inverted'' DOS which has previously only been reported in
superconductor/weak-ferromagnet structures. We analyze the data using the
self-consistent non-linear Usadel equation and find that we are able to
quantitatively fit the features at if we include a large amount
of spin-orbit scattering in the model. Interestingly, we are unable to
reproduce the sub-gap structure through the addition of any parameter(s).
Therefore, the observed anomalous sub-gap structure represents new physics
beyond that contained in the present Usadel theory.Comment: 4 pages, 3 figure
Gegenbauer-solvable quantum chain model
In an innovative inverse-problem construction the measured, experimental
energies , , ... of a quantum bound-state system are assumed
fitted by an N-plet of zeros of a classical orthogonal polynomial . We
reconstruct the underlying Hamiltonian (in the most elementary
nearest-neighbor-interaction form) and the underlying Hilbert space
of states (the rich menu of non-equivalent inner products is offered). The
Gegenbauer's ultraspherical polynomials are chosen for
the detailed illustration of technicalities.Comment: 29 pp., 1 fi
Effects of technology-based interventions on dietary intake or anthropometrics among adolescents and adults in South Asia-A systematic review of intervention studies
Introduction: Mobile technology has been increasingly used as part of dietary interventions, but the effects of such interventions have not been systematically evaluated in the South Asian context. The systematic review aimed to determine the effects of technology-based interventions on dietary intake or anthropometrics among adolescents and adults in South Asia. Methods: Five electronic databases were searched (PubMed, Scopus, Web of Science, Global Health Library and Health Technology Assessment). Studies published in English between 1st January 2011 and 31st December 2021were included. Interventions that evaluated the effects of dietary interventions using technology on dietary outcomes and anthropometrics in adolescents or adults in the age group of 13-44 years (or a broader age group) from South Asia were eligible for inclusion. The risk of bias was assessed using the Cochrane Risk-of-bias 2 tool and ROBINS-I tool. A narrative synthesis was conducted. Results: Twenty-one studies met the inclusion criteria (20,667 participants). Eleven of the 17 randomised controlled trials (RCTs) had a high overall risk of bias. The four non-randomised intervention studies had a serious or critical overall risk of bias. When including studies with low risk or some concern for bias, the interventions had a beneficial effect on at least one dietary outcome in four of the six RCTs that measured changes in diet, and no effect on the anthropometric outcomes in the six RCTs that measured changes in anthropometric outcomes.Discussion: Technology-based dietary interventions have had some positive effects on dietary intake, but no effects on anthropometry in South Asia. More evidence is needed as the overall risk of bias was high in a majority of the studies.Peer reviewe
Proximity Effect in Nb/Au/CoFe Trilayers
We have investigated the superconducting critical temperatures of Nb/Au/CoFe
trilayers as a function of Au and CoFe thicknesses. Without the CoFe layer the
superconducting critical temperatures of Nb/Au bilayers as a function of Au
thickness follow the well-known proximity effect between a superconductor and a
normal metal. The superconducting critical temperatures of Nb/Au/CoFe trilayers
as a function of Au thickness exhibit a rapid initial increase in the small Au
thickness region and increase slowly to a limiting value above this region,
accompanied by a small oscillation of Tc. On the other hand, the
superconducting critical temperatures of Nb/Au/CoFe trilayers as a function of
CoFe thickness show non-monotonic behavior with a shallow dip feature. We
analyzed the Tc behavior in terms of Usadel formalism and found that most
features are consistent with the theory, although the small oscillation of Tc
as a function of the Au thickness cannot be accounted for. We have also found
quantitative values for the two interfaces: Nb/Au and Au/CoFe.Comment: 25 pages, 6 figure
Mining the ESO WFI and INT WFC archives for known Near Earth Asteroids. Mega-Precovery software
The ESO/MPG WFI and the INT WFC wide field archives comprising 330,000 images
were mined to search for serendipitous encounters of known Near Earth Asteroids
(NEAs) and Potentially Hazardous Asteroids (PHAs). A total of 152 asteroids (44
PHAs and 108 other NEAs) were identified using the PRECOVERY software, their
astrometry being measured on 761 images and sent to the Minor Planet Centre.
Both recoveries and precoveries were reported, including prolonged orbital arcs
for 18 precovered objects and 10 recoveries. We analyze all new opposition data
by comparing the orbits fitted before and after including our contributions. We
conclude the paper presenting Mega-Precovery, a new online service focused on
data mining of many instrument archives simultaneously for one or a few given
asteroids. A total of 28 instrument archives have been made available for
mining using this tool, adding together about 2.5 million images forming the
Mega-Archive.Comment: Accepted for publication in Astronomische Nachrichten (Sep 2012
Calculating all elements of minimal index in the infinite parametric family of simplest quartic fields
summary:It is a classical problem in algebraic number theory to decide if a number field is monogeneous, that is if it admits power integral bases. It is especially interesting to consider this question in an infinite parametric family of number fields. In this paper we consider the infinite parametric family of simplest quartic fields generated by a root of the polynomial , assuming that , and has no odd square factors. In addition to generators of power integral bases we also calculate the minimal index and all elements of minimal index in all fields in this family
Quantitative analysis of proximity effect in , Nb/Ni, and bilayers
We have studied the behavior of the superconducting critical temperature Tc
in , Nb/Ni, and bilayers as a function
of the thickness of each ferromagnetic metal layer. The Tc s of three sets of
bilayers exhibit non-monotonic behavior as a function of each ferromagnetic
metal thickness. Employing the quantitative analysis based on Usadel formalism
of the effect of the exchange energy, we observed that the Tc behavior of
bilayers is in good agreement with the theoretical values
over the entire range of the data. On the other hand, the Tc s of Nb/Ni and
bilayers show a higher value in the small thickness regime
than the theoretical prediction obtained from the calculation, which matches
the dip position and the saturation value of Tc in the large thickness limit.
This discrepancy is probably due to the weakened magnetic properties of Ni and
when they are thin. We discuss the values of our fitting
parameters and its implication on the validity of the current Usadel formalism
of the effect of the exchange energy.Comment: 10 pages, 5 figures and 1 tabl
Localization transition of random copolymers at interfaces
We consider adsorption of random copolymer chains onto an interface within
the model of Garel et al. Europhysics Letters 8, 9 (1989). By using the replica
method the adsorption of the copolymer at the interface is mapped onto the
problem of finding the ground state of a quantum mechanical Hamiltonian. To
study this ground state we introduce a novel variational principle for the
Green's function, which generalizes the well-known Rayleigh-Ritz method of
Quantum Mechanics to nonstationary states. Minimization with an appropriate
trial Green's function enables us to find the phase diagram for the
localization-delocalization transition for an ideal random copolymer at the
interface.Comment: 5 page
Photospheric activity, rotation, and star-planet interaction of the planet-hosting star CoRoT-6
The CoRoT satellite has recently discovered a hot Jupiter that transits
across the disc of a F9V star called CoRoT-6 with a period of 8.886 days. We
model the photospheric activity of the star and use the maps of the active
regions to study stellar differential rotation and the star-planet interaction.
We apply a maximum entropy spot model to fit the optical modulation as observed
by CoRoT during a uninterrupted interval of about 140 days. Photospheric active
regions are assumed to consist of spots and faculae in a fixed proportion with
solar-like contrasts. Individual active regions have lifetimes up to 30-40
days. Most of them form and decay within five active longitudes whose different
migration rates are attributed to the stellar differential rotation for which a
lower limit of \Delta \Omega / \Omega = 0.12 \pm 0.02 is obtained. Several
active regions show a maximum of activity at a longitude lagging the
subplanetary point by about 200 degrees with the probability of a chance
occurrence being smaller than 1 percent. Our spot modelling indicates that the
photospheric activity of CoRoT-6 could be partially modulated by some kind of
star-planet magnetic interaction, while an interaction related to tides is
highly unlikely because of the weakness of the tidal force.Comment: 9 pages, 7 figures, accepted to Astronomy & Astrophysic
An exactly solvable quantum-lattice model with a tunable degree of nonlocality
An array of N subsequent Laguerre polynomials is interpreted as an
eigenvector of a non-Hermitian tridiagonal Hamiltonian with real spectrum
or, better said, of an exactly solvable N-site-lattice cryptohermitian
Hamiltonian whose spectrum is known as equal to the set of zeros of the N-th
Laguerre polynomial. The two key problems (viz., the one of the ambiguity and
the one of the closed-form construction of all of the eligible inner products
which make Hermitian in the respective {\em ad hoc} Hilbert spaces) are
discussed. Then, for illustration, the first four simplest, parametric
definitions of inner products with and are explicitly
displayed. In mathematical terms these alternative inner products may be
perceived as alternative Hermitian conjugations of the initial N-plet of
Laguerre polynomials. In physical terms the parameter may be interpreted as
a measure of the "smearing of the lattice coordinates" in the model.Comment: 35 p
- …