333 research outputs found
Jonckheere-Terpstra test for nonclassical error versus log-sensitivity relationship of quantum spin network controllers
Selective information transfer in spin ring networks by energy landscape shaping control has the property that the error 1âprob, where prob is the transfer success probability, and the sensitivity of the error to spin coupling uncertainties are statistically increasing across a family of controllers of increasing error. The need for a statistical Hypothesis Testing of a concordant trend is made necessary by the noisy behavior of the sensitivity versus the error as a consequence of the optimization of the controllers in a challenging error landscape. Here, we examine the concordant trend between the error and another measure of performanceâthe logarithmic sensitivityâused in robust control to formulate a well known fundamental limitation. Contrary to error versus sensitivity, the error versus logarithmic sensitivity trend is less obvious, because of the amplification of the noise due to the logarithmic normalization. This results in the Kendall Ï test for rank correlation between the error and the log sensitivity to be somewhat pessimistic with marginal significance level. Here it is shown that the Jonckheere-Terpstra test, because it tests the Alternative Hypothesis of an ordering of the medians of some groups of log sensitivity data, alleviates this statistical problem. This identifies cases of concordant trend between the error and the logarithmic sensitivity, a highly anti-classical features that goes against the well know sensitivity versus complementary sensitivity limitation
Spherical Relativistic Hartree theory in a Woods-Saxon basis
The Woods-Saxon basis has been suggested to replace the widely used harmonic
oscillator basis for solving the relativistic mean field (RMF) theory in order
to generalize it to study exotic nuclei. As examples, relativistic Hartree
theory is solved for spherical nuclei in a Woods-Saxon basis obtained by
solving either the Schr\"odinger equation or the Dirac equation (labelled as
SRHSWS and SRHDWS, respectively and SRHWS for both). In SRHDWS, the negative
levels in the Dirac Sea must be properly included. The basis in SRHDWS could be
smaller than that in SRHSWS which will simplify the deformed problem. The
results from SRHWS are compared in detail with those from solving the spherical
relativistic Hartree theory in the harmonic oscillator basis (SRHHO) and those
in the coordinate space (SRHR). All of these approaches give identical nuclear
properties such as total binding energies and root mean square radii for stable
nuclei. For exotic nuclei, e.g., Ca, SRHWS satisfactorily reproduces the
neutron density distribution from SRHR, while SRHHO fails. It is shown that the
Woods-Saxon basis can be extended to more complicated situations for exotic
nuclei where both deformation and pairing have to be taken into account.Comment: 12 pages, 9 figure
Model Channel Ion Currents in NaCl - SPC/E Solution with Applied-Field Molecular Dynamics
Using periodic boundary conditions and a constant applied field, we have
simulated current flow through an 8.125 Angstrom internal diameter, rigid,
atomistic channel with polar walls in a rigid membrane using explicit ions and
SPC/E water. Channel and bath currents were computed from ten 10-ns
trajectories for each of 10 different conditions of concentration and applied
voltage. An electric field was applied uniformly throughout the system to all
mobile atoms. On average, the resultant net electric field falls primarily
across the membrane channel, as expected for two conductive baths separated by
a membrane capacitance. The channel is rarely occupied by more than one ion.
Current-voltage relations are concentration-dependent and superlinear at high
concentrations.Comment: Accepted for publication in Biophysical Journa
Early-Time Energy Loss in a Strongly-Coupled SYM Plasma
We carry out an analytic study of the early-time motion of a quark in a
strongly-coupled maximally-supersymmetric Yang-Mills plasma, using the AdS/CFT
correspondence. Our approach extracts the first thermal effects as a small
perturbation of the known quark dynamics in vacuum, using a double expansion
that is valid for early times and for (moderately) ultrarelativistic quark
velocities. The quark is found to lose energy at a rate that differs
significantly from the previously derived stationary/late-time result: it
scales like T^4 instead of T^2, and is associated with a friction coefficient
that is not independent of the quark momentum. Under conditions representative
of the quark-gluon plasma as obtained at RHIC, the early energy loss rate is a
few times smaller than its late-time counterpart. Our analysis additionally
leads to thermally-corrected expressions for the intrinsic energy and momentum
of the quark, in which the previously discovered limiting velocity of the quark
is found to appear naturally.Comment: 39 pages, no figures. v2: Minor corrections and clarifications.
References added. Version to be published in JHE
Relativistic Continuum Hartree Bogoliubov Theory for Ground State Properties of Exotic Nuclei
The Relativistic Continuum Hartree-Bogoliubov (RCHB) theory, which properly
takes into account the pairing correlation and the coupling to (discretized)
continuum via Bogoliubov transformation in a microscopic and self-consistent
way, has been reviewed together with its new interpretation of the halo
phenomena observed in light nuclei as the scattering of particle pairs into the
continuum, the prediction of the exotic phenomena -- giant halos in nuclei near
neutron drip line, the reproduction of interaction cross sections and
charge-changing cross sections in light exotic nuclei in combination with the
Glauber theory, better restoration of pseudospin symmetry in exotic nuclei,
predictions of exotic phenomena in hyper nuclei, and new magic numbers in
superheavy nuclei, etc. Recent investigations on new effective interactions,
the density dependence of the interaction strengthes, the RMF theory on the
Woods-Saxon basis, the single particle resonant states, and the resonant BCS
(rBCS) method for the pairing correlation, etc. are also presented in some
details.Comment: 79 pages. Prog. Part. Nucl. Phys. (2005) in pres
Dissipative superfluid dynamics from gravity
Charged asymptotically AdS black branes in five dimensions are sometimes
unstable to the condensation of charged scalar fields. For fields of infinite
charge and squared mass -4 Herzog was able to analytically determine the phase
transition temperature and compute the endpoint of this instability in the
neighborhood of the phase transition. We generalize Herzog's construction by
perturbing away from infinite charge in an expansion in inverse charge and use
the solutions so obtained as input for the fluid gravity map. Our tube wise
construction of patched up locally hairy black brane solutions yields a one to
one map from the space of solutions of superfluid dynamics to the long
wavelength solutions of the Einstein Maxwell system. We obtain explicit
expressions for the metric, gauge field and scalar field dual to an arbitrary
superfluid flow at first order in the derivative expansion. Our construction
allows us to read off the the leading dissipative corrections to the perfect
superfluid stress tensor, current and Josephson equations. A general framework
for dissipative superfluid dynamics was worked out by Landau and Lifshitz for
zero superfluid velocity and generalized to nonzero fluid velocity by Clark and
Putterman. Our gravitational results do not fit into the 13 parameter
Clark-Putterman framework. Purely within fluid dynamics we present a consistent
new generalization of Clark and Putterman's equations to a set of superfluid
equations parameterized by 14 dissipative parameters. The results of our
gravitational calculation fit perfectly into this enlarged framework. In
particular we compute all the dissipative constants for the gravitational
superfluid.Comment: v1: 58 + 1 pages; v2: 83 + 1 page
Loop Quantum Gravity a la Aharonov-Bohm
The state space of Loop Quantum Gravity admits a decomposition into
orthogonal subspaces associated to diffeomorphism equivalence classes of
spin-network graphs. In this paper I investigate the possibility of obtaining
this state space from the quantization of a topological field theory with many
degrees of freedom. The starting point is a 3-manifold with a network of
defect-lines. A locally-flat connection on this manifold can have non-trivial
holonomy around non-contractible loops. This is in fact the mathematical origin
of the Aharonov-Bohm effect. I quantize this theory using standard field
theoretical methods. The functional integral defining the scalar product is
shown to reduce to a finite dimensional integral over moduli space. A
non-trivial measure given by the Faddeev-Popov determinant is derived. I argue
that the scalar product obtained coincides with the one used in Loop Quantum
Gravity. I provide an explicit derivation in the case of a single defect-line,
corresponding to a single loop in Loop Quantum Gravity. Moreover, I discuss the
relation with spin-networks as used in the context of spin foam models.Comment: 19 pages, 1 figure; v2: corrected typos, section 4 expanded
Critical Trapped Surfaces Formation in the Collision of Ultrarelativistic Charges in (A)dS
We study the formation of marginally trapped surfaces in the head-on
collision of two ultrarelativistic charges in space-time. The metric of
ultrarelativistic charged particles in is obtained by boosting
Reissner-Nordstr\"om space-time to the speed of light. We show that
formation of trapped surfaces on the past light cone is only possible when
charge is below certain critical - situation similar to the collision of two
ultrarelativistic charges in Minkowski space-time. This critical value depends
on the energy of colliding particles and the value of a cosmological constant.
There is richer structure of critical domains in case. In this case
already for chargeless particles there is a critical value of the cosmological
constant only below which trapped surfaces formation is possible. Appearance of
arbitrary small nonzero charge significantly changes the physical picture.
Critical effect which has been observed in the neutral case does not take place
more. If the value of the charge is not very large solution to the equation on
trapped surface exists for any values of cosmological radius and energy density
of shock waves. Increasing of the charge leads to decrease of the trapped
surface area, and at some critical point the formation of trapped surfaces of
the type mentioned above becomes impossible.Comment: 30 pages, Latex, 7 figures, Refs. added and typos correcte
The Bosnian version of the international self-report measure of posttraumatic stress disorder, the Posttraumatic Stress Diagnostic Scale, is reliable and valid in a variety of different adult samples affected by war
BACKGROUND: The aim of the present study was to assess the internal consistency and discriminant and convergent validity of the Bosnian version of a self-report measure of posttraumatic stress disorder (PTSD), the Posttraumatic Stress Diagnostic Scale (PTDS). The PTDS yields both a PTSD diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders 4(th )edition (DSM-IV) and a measure of symptom severity. METHODS: 812 people living in Sarajevo or in Banja Luka in Bosnia-Herzegovina, of whom the majority had experienced a high number of traumatic war events, were administered the PTDS and other measures of trauma-related psychopathology. The psychometric properties of the instrument were assessed using Cronbach's alpha and principal components analysis, and its construct validity was assessed via Spearman correlation coefficients with the other instruments. RESULTS: The PTDS and its subscales demonstrated high internal consistency. The principal components revealed by an exploratory analysis are broadly consistent with the DSM-IV subscales except that they reproduce some previously reported difficulties with the "numbing" items from the avoidance subscale. The construct validity of the PTDS was supported by appropriate correlations with other relevant measures of trauma related psychopathology. CONCLUSION: The Bosnian version of the PTDS thus appears to be a time-economic and psychometrically sound measure for screening and assessing current PTSD. This self-report measure awaits further validation by interview methods
A functional magnetic resonance imaging investigation of visual hallucinations in the human striate cortex
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