905 research outputs found
Does a preference for fatty foods prior to commencing treatment with the ketogenic diet predict the efficacy of this diet?
AbstractThe ketogenic diet can be effective in children who suffer from drug-resistant epilepsy. However, it is still hard to predict how large an effect this diet will have for an individual child. Previous data suggests a high-fat food preference is more likely in those with epilepsy, as assessed by in-person forced-choice design. The aim of this study is to examine whether a partiality to fatty foods prior to commencing the ketogenic diet can be used as a predictive factor for the efficacy of this diet in children with drug-resistant epilepsy.Data from 43 children aged between 2 and 19 years was used in this retrospective, non-controlled, non-randomised, open study. All children had followed the ketogenic diet for a period of 3 months or more. Before commencing the diet, a food record was collected for each child to determine the percentage of daily energy-intake accounted for by fats. Parents of the participants completed a questionnaire to measure fat-preference in the pre-diet period and received a score to objectify the efficacy of the treatment.The raw scores on the food record and on the questionnaire were divided into subgroups. Subsequently Kendall's tau-b was calculated for the correlation between each combination of variables. A non-significant correlation was found for the relationship between the food record and the questionnaire (p=.939), the relationship between the food record and the efficacy of the treatment (p=.827) and the relationship between the questionnaire and the efficacy of the treatment (p=.539). This means treatment efficacy cannot be predicted by the child's food preference
On a Three-Dimensional Gravity Model with Higher Derivatives
The purpose of this work is to present a model for 3D massive gravity with
topological and higher-derivative terms. Causality and unitarity are discussed
at tree-level. Power-counting renormalizability is also contemplated.Comment: 9 pages, Latex, no figures; to be published in Gen. Rel. Gra
Role of Visual Dysfunction in Postural Control in Children With Cerebral Palsy
Introduction: Deficient postural control is one of the key problems in cerebral palsy (CP). Little, however, is known about the specific nature of postural problems of children with CP, nor of the relation between abnormal posture and dysfunction of the visual system. Aim of the study: To provide additional information on the association of abnormalities in postural control and visual dysfunction of the anterior or posterior part of the visual system. Methods: Data resulting from ophthalmologic, orthoptic, neurological, neuro-radiological, and ethological investigations of more than 313 neurologically impaired children were retrospectively analyzed. Results: Abnormal postural control related to ocular and ocular motor disorders consisted of anomalous head control and subsequent abnormal head posture and torticollis. The abnormal postural control related to retrochiasmatical damage of the visual system consisted of a torticollis combined with adjustment of the upper part of the body, as if at the same time adapting to a combination of defects and optimizing residual visual functions. Conclusion: Visual dysfunctions play a distinct role in the postural control of children with CP
Epilepsy surgery in tuberous sclerosis: The Dutch experience
SummaryIntroductionEpilepsy associated with tuberous sclerosis complex (TSC) is drug resistant in more than half of the patients. Epilepsy surgery may be an alternative treatment option, if the epileptogenic tuber can be identified reliably and if seizure reduction is not at the expense of cognitive or other functions. We report the pre-surgical identification of the epileptogenic tuber and post-surgical outcome of patients with TSC in The Netherlands.MethodsTwenty-five patients underwent the pre-surgical evaluation of the Dutch Comprehensive Epilepsy Surgery Programme, including a detailed seizure history, interictal and ictal video EEG registrations, 3D FLAIR MRI scans and neuropsychological testing. Suitability of the candidates was decided in consensus. Seizure outcome, scored with the Engel classification, and cognition were reassessed at fixed post-surgery intervals.ResultsEpilepsy surgery was performed in six patients. At follow-up, four patients had Engel classification 1, two had classification 4. Improved development and behaviour was perceived by the parents of two patients. Epilepsy surgery was not performed in 19 patients because seizures were not captured, ictal onset zones could not be localised or were multiple, interictal EEG, video EEG and MEG results were not concordant, or seizure burden had diminished during decision making. A higher cognition index was found in the surgical patients compared to the non-surgical candidates.ConclusionsEpilepsy surgery can be performed safely and successfully in patients in whom semiology, interictal EEG, ictal EEG, MEG and the location of tubers are concordant. In other cases the risk of surgery should be weighed against the chance of seizure relief and in case of children subsequent impact on neurodevelopment
On the Dirac Eigenvalues as Observables of the on-shell N=2 D=4 Euclidean Supergravity
We generalize previous works on the Dirac eigenvalues as dynamical variables
of the Euclidean gravity and N=1 D=4 supergravity to on-shell N=2 D=4 Euclidean
supergravity. The covariant phase space of the theory is defined as as the
space of the solutions of the equations of motion modulo the on-shell gauge
transformations. In this space we define the Poisson brackets and compute their
value for the Dirac eigenvalues.Comment: 10 pages, LATeX fil
Dimensional regularization of the path integral in curved space on an infinite time interval
We use dimensional regularization to evaluate quantum mechanical path
integrals in arbitrary curved spaces on an infinite time interval. We perform
3-loop calculations in Riemann normal coordinates, and 2-loop calculations in
general coordinates. It is shown that one only needs a covariant two-loop
counterterm (V_{DR} = R/8) to obtain the same results as obtained earlier in
other regularization schemes. It is also shown that the mass term needed in
order to avoid infrared divergences explicitly breaks general covariance in the
final result.Comment: 13 pages, 10 figures, LaTe
Intensity Distribution of Waves Transmitted Through a Multiple Scattering Medium
The distributions of the angular transmission coefficient and of the total
transmission are calculated for multiple scattered waves. The calculation is
based on a mapping to the distribution of eigenvalues of the transmission
matrix. The distributions depend on the profile of the incoming beam. The
distribution function of the angular transmission has a stretched exponential
decay. The total-transmission distribution grows log-normally whereas it decays
exponentially.Comment: 8 pages, revtex3.0, 3 postscript figures, NvR0
Dimensional regularization of nonlinear sigma models on a finite time interval
We extend dimensional regularization to the case of compact spaces. Contrary
to previous regularization schemes employed for nonlinear sigma models on a
finite time interval (``quantum mechanical path integrals in curved space'')
dimensional regularization requires only a covariant finite two-loop
counterterm. This counterterm is nonvanishing and given by R/8.Comment: 9 pages, 7 figures, LaTeX, minor changes in text and reference
Local Unit Invariance, Back-Reacting Tractors and the Cosmological Constant Problem
When physics is expressed in a way that is independent of local choices of
unit systems, Riemannian geometry is replaced by conformal geometry. Moreover
masses become geometric, appearing as Weyl weights of tractors (conformal
multiplets of fields necessary to keep local unit invariance manifest). The
relationship between these weights and masses is through the scalar curvature.
As a consequence mass terms are spacetime dependent for off-shell gravitational
backgrounds, but happily constant for physical, Einstein manifolds.
Unfortunately this introduces a naturalness problem because the scalar
curvature is proportional to the cosmological constant. By writing down tractor
stress tensors (multiplets built from the standard stress tensor and its first
and second derivatives), we show how back-reaction solves this naturalness
problem. We also show that classical back-reaction generates an interesting
potential for scalar fields. We speculate that a proper description of how
physical systems couple to scale, could improve our understanding of
naturalness problems caused by the disparity between the particle physics and
observed, cosmological constants. We further give some ideas how an ambient
description of tractor calculus could lead to a Ricci-flat/CFT correspondence
which generalizes the AdS side of Maldacena's duality to a Ricci-flat space of
one higher dimension.Comment: 20 pages, 2 figure
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