362 research outputs found
Effect of Image Forces on Polyelectrolyte Adsorption at a Charged Surface
The adsorption of flexible and highly charged polyelectrolytes onto
oppositely charged planar surfaces is investigated by means of Monte Carlo
simulations. The effect of image forces stemming from the dielectric
discontinuity at the substrate interface is considered. The influence, at fixed
polyelectrolyte volume fraction, of chain length and surface-charge density is
also considered. A detailed structural study, including monomer and fluid
charge distributions, is provided. It is demonstrated that image forces can
considerably reduce the degree of polyelectrolyte adsorption and concomitantly
inhibit the charge inversion of the substrate by polyelectrolytes.Comment: 19 pages - 7 eps figs - RevTex 4 - submitted for publicatio
Exploring nonlocal observables in shock wave collisions
We study the time evolution of 2-point functions and entanglement entropy in
strongly anisotropic, inhomogeneous and time-dependent N=4 super Yang-Mills
theory in the large N and large 't Hooft coupling limit using AdS/CFT. On the
gravity side this amounts to calculating the length of geodesics and area of
extremal surfaces in the dynamical background of two colliding gravitational
shockwaves, which we do numerically. We discriminate between three classes of
initial conditions corresponding to wide, intermediate and narrow shocks, and
show that they exhibit different phenomenology with respect to the nonlocal
observables that we determine. Our results permit to use (holographic)
entanglement entropy as an order parameter to distinguish between the two
phases of the cross-over from the transparency to the full-stopping scenario in
dynamical Yang-Mills plasma formation, which is frequently used as a toy model
for heavy ion collisions. The time evolution of entanglement entropy allows to
discern four regimes: highly efficient initial growth of entanglement, linear
growth, (post) collisional drama and late time (polynomial) fall off.
Surprisingly, we found that 2-point functions can be sensitive to the geometry
inside the black hole apparent horizon, while we did not find such cases for
the entanglement entropy.Comment: 28 pp, 9 figs; v2: updated references, changed color bars in Figure 2
and Figure
Raccolta dati su alcuni nuovi materiali di impiego nel settore elettrico e elettronico
Questa tesi ha come scopo quello di fare una rassegna dei materiali di recente sviluppo nel settore elettrico ed elettronico, descrivendone le proprietĂ , lo sviluppo storico, le applicazioni attuali e anche quelle possibili in futuro che attualmente sono solo in fase di sperimentazione.
Limitandosi all’illustrazione delle caratteristiche e dei campi di applicazione dei vari materiali, senza entrare nel dettaglio dei metodi costruttivi né sulle tecniche di ricerca attuali, questa tesi vuole descrivere la situazione dello stato attuale dei materiali elettromagnetici e dei loro differenti utilizzi
Adsorption of Oligo- and Polypeptides as Model Polyelectrolytes
The adsorption of oligo- and polylysines on silver iodide and
polystyrene latex has been measured as a function of concentration,
pH and ionic strength w. At low pH, polylysine adsorbs in
a flat conformation. Loops start to develop if the pH is increased
or if w is raised. The electrolyte effect persists up to very high \u27
concentrations. The principles and some results of a new polyelectrolyte
adsorption theory are outlined. It explains the experimentally
observed features at least semiquantitatively. The segment
density profile of a polyelectrolyt adsorbate does not resemble that
of an uncharged macromolecule. It depends on the charge on the
chain and on w and under certain conditions it contains a region
of negative adsorption
Polyelectrolyte multilayer formation: electrostatics and short-range interactions
We investigate the phenomenon of multilayer formation via layer-by-layer
deposition of alternating charge polyelectrolytes. Using mean-field theory, we
find that a strong short-range attraction between the two types of polymer
chains is essential for the formation of multilayers. The dependence of the
required short-range attraction on the polymer charge fraction and salt
concentration is calculated. For weak short-range attraction between any two
adjacent layers, the adsorbed amount (per added layer) decays as the distance
from the surface increases, until the chains stop adsorbing altogether. For
strong short-range attraction, the adsorbed amount per layer increases after an
initial decrease, and finally it stabilizes in the form of a polyelectrolyte
multilayer that can be repeated many times.Comment: 8 pages, 7 figure
Quasiperiodic oscillations in a strong gravitational field around neutron stars testing braneworld models
The strong gravitational field of neutron stars in the brany universe could
be described by spherically symmetric solutions with a metric in the exterior
to the brany stars being of the Reissner-Nordstrom type containing a brany
tidal charge representing the tidal effect of the bulk spacetime onto the star
structure. We investigate the role of the tidal charge in orbital models of
high-frequency quasiperiodic oscillations (QPOs) observed in neutron star
binary systems. We focus on the relativistic precession model. We give the
radial profiles of frequencies of the Keplerian (vertical) and radial epicyclic
oscillations. We show how the standard relativistic precession model modified
by the tidal charge fits the observational data, giving estimates of the
allowed values of the tidal charge and the brane tension based on the processes
going in the vicinity of neutron stars. We compare the strong field regime
restrictions with those given in the weak-field limit of solar system
experiments.Comment: 26 pages, 6 figure
Profiles of emission lines generated by rings orbiting braneworld Kerr black holes
In the framework of the braneworld models, rotating black holes can be
described by the Kerr metric with a tidal charge representing the influence of
the non-local gravitational (tidal) effects of the bulk space Weyl tensor onto
the black hole spacetime. We study the influence of the tidal charge onto
profiled spectral lines generated by radiating tori orbiting in vicinity of a
rotating black hole. We show that with lowering the negative tidal charge of
the black hole, the profiled line becomes to be flatter and wider keeping their
standard character with flux stronger at the blue edge of the profiled line.
The extension of the line grows with radius falling and inclination angle
growing. With growing inclination angle a small hump appears in the profiled
lines due to the strong lensing effect of photons coming from regions behind
the black hole. For positive tidal charge () and high inclination angles
two small humps appear in the profiled lines close to the red and blue edge of
the lines due to the strong lensing effect. We can conclude that for all values
of , the strongest effect on the profiled lines shape (extension) is caused
by the changes of the inclination angle.Comment: Accepted by General Relativity and Gravitatio
Improved diagnosis of trichomonas vaginalis infection by PCR using vaginal swabs and urine specimens compared to diagnosis by wet mount microscopy, culture, and fluorescent staining
Does trust in health care influence the use of complementary and alternative medicine by chronically ill people?
BACKGROUND: People's trust in health care and health care professionals is essential for the effectiveness of health care, especially for chronically ill people, since chronic diseases are by definition (partly) incurable. Therefore, it may be understandable that chronically ill people turn to complementary and alternative medicine (CAM), often in addition to regular care. Chronically ill people use CAM two to five times more often than non-chronically ill people. The trust of chronically ill people in health care and health care professionals and the relationship of this with CAM use have not been reported until now. In this study, we examine the influence of chronically ill people's trust in health care and health care professionals on CAM use. METHODS: The present sample comprises respondents of the 'Panel of Patients with Chronic Diseases' (PPCD). Patients (≥25 years) were selected by GPs. A total of 1,625 chronically ill people were included. Trust and CAM use was measured by a written questionnaire. Statistical analyses were t tests for independent samples, Chi-square and one-way analysis of variance, and logistic regression analysis. RESULTS: Chronically ill people have a relatively low level of trust in future health care. They trust certified alternative practitioners less than regular health care professionals, and non-certified alternative practitioners less still. The less trust patients have in future health care, the more they will be inclined to use CAM, when controlling for socio-demographic and disease characteristics. CONCLUSION: Trust in future health care is a significant predictor of CAM use. Chronically ill people's use of CAM may increase in the near future. Health policy makers should, therefore, be alert to the quality of practising alternative practitioners, for example by insisting on professional certification. Equally, good quality may increase people's trust in public health care
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