343 research outputs found
Quality of life and anorectal malformations: a single-center experience
Purpose: The treatment and long term clinical outcomes of anorectal malformations (ARM) in children have always been the focus of pediatric surgeons. This study aimed at reporting our experience as far as long-term follow-up of ARM in children is concern. Methods: We enrolled patients treated between 1999 and 2019, and established selection criteria to choose appropriate subjects. A validated questionnaire was used to determine long-term quality of life outcomes. Results: Out of a total of 48 patients treated within the study period, 28 were enrolled in this study. Among the latter, more than 35% had at least one long-time complication, and more than 90% had a good lifestyle. Urinary and fecal continence was achieved in more than 95% of the patients using medical devices. Conclusion: This study aimed to bring up new concepts; taking into consideration all aspects of life in patients with ARM, from school life to sexuality, while evaluating fecal and urinary continence. This is essential for the improvement of the skills of the different specialists involved in the management of these patients, and for the implementation of strategies that can improve postoperative function. Most especially, it will also help improve communication between doctors to ensure an adequate transition of these children into adult life
Gravity of higher-dimensional global defects
Solutions of Einstein's equations are found for global defects in a
higher-dimensional spacetime with a nonzero cosmological constant Lambda. The
defect has a (p-1)-dimensional core (brane) and a `hedgehog' scalar field
configuration in the n extra dimensions. For Lambda = 0 and n > 2, the
solutions are characterized by a flat brane worldsheet and a solid angle
deficit in the extra dimensions. For Lambda > 0, one class of solutions
describes spherical branes in an inflating higher-dimensional universe.
Instantons obtained by a Euclidean continuation of such solutions describe
quantum nucleation of the entire inflating brane-world, or of a spherical brane
in an inflating higher-dimensional universe. For Lambda < 0, one class of
solutions exhibits an exponential warp factor. It is similar to spacetimes
previously discussed by Randall and Sundrum for n = 1 and by Gregory for n = 2.Comment: 18 pages, no figures, uses revte
Nonsingular global string compactifications
We consider an exotic `compactification' of spacetime in which there are two
infinite extra dimensions, using a global string instead of a domain wall. By
having a negative cosmological constant we prove the existence of a nonsingular
static solution using a dynamical systems argument. A nonsingular solution also
exists in the absence of a cosmological constant with a time-dependent metric.
We compare and contrast this solution with the Randall-Sundrum universe and the
Cohen-Kaplan spacetime, and consider the options of using such a model as a
realistic resolution of the hierarchy problem.Comment: 8 pages revtex, 1 figure : References added and equation correcte
Semiclassical Quantisation Using Diffractive Orbits
Diffraction, in the context of semiclassical mechanics, describes the manner
in which quantum mechanics smooths over discontinuities in the classical
mechanics. An important example is a billiard with sharp corners; its
semiclassical quantisation requires the inclusion of diffractive periodic
orbits in addition to classical periodic orbits. In this paper we construct the
corresponding zeta function and apply it to a scattering problem which has only
diffractive periodic orbits. We find that the resonances are accurately given
by the zeros of the diffractive zeta function.Comment: Revtex document. Submitted to PRL. Figures available on reques
Isolation and characterization of tissue-specific isozymes of glucosephosphate isomerase from catfish and conger.
In teleosts glucosephosphate isomerase exists as two tissue-specific isozymes. Most tissues contain the more acidic liver-type isozyme, while white muscle contains the more basic isozyme; and a few tissues contain both the liver- and muscle-type isozymes as well as a hybird. The isozymes were isolated from catfish liver and muscle and from conger muscle and shown to be homogeneous by polyacrylamide gel electrophoresis, isoelectric focusing, analytical ultracentrifugation, and rechromatography. Both isozymes are of molecular weight 132,000 (S020,w = 7.0 S) and composed of two subunits of Mr approximately 65,000. The muscle and liver isozymes were shown to have distinct isoelectric points (catfish liver = 6.2; muscle = 7.0) and amino acid compositions. Tryptic peptide maps, after S-carboxymethylation and carbamylation, revealed several distinct differences in the primary structures of the isozymes. Although the isozymes could also be distinguished on the basis of their stabilities, most of their basic catalytic properties were found to be similar. A conger was obtained which was heterozygous for the variant allele at the muscle-glucosephosphate isomerase locus. A comparison of the variant conger muscle isozyme with the wild type revealed a single altered peptide, suggesting a point mutation. The structure-function studies, as well as the genetic studies, clearly establish that the two types of isozymes are of independent genetic origin
Synchronization modulation increases transepithelial potentials in MDCK monolayers through Na/K pumps
Peer reviewedPublisher PD
Drift or shift? Continuity, change, and international variation in knowledge production in OR/MS
With the aim of contributing to the debate around OR/MS as a discipline, this study provides a historical comparative investigation of publicly available knowledge production in the field. The empirical investigation is based on a content analysis of 300 randomly selected articles from six major journals in the field. We have found: (1) since the late 1950s to the present day there has been no significant change in the types of published research in OR/MS in North America; (2) from the late 1950s to the present day, there have been significant differences in types of published research in OR/MS internationally. The imputed imbalance between theory and applications in published work had already occurred in the early stages of the development of OR/MS in North America and has since remained very much the same. Furthermore, research in the United Kingdom has been distinctly different from that dominant in North America and elsewhere. There are also indications that outside North America and the United Kingdom there is an emerging turn towards applications-oriented research. Over the last two or three decades there has been a significant increase overall in the share of articles published by academic authors
The effect of parallel static and microwave electric fields on excited hydrogen atoms
Motivated by recent experiments we analyse the classical dynamics of a
hydrogen atom in parallel static and microwave electric fields. Using an
appropriate representation and averaging approximations we show that resonant
ionisation is controlled by a separatrix, and provide necessary conditions for
a dynamical resonance to affect the ionisation probability.
The position of the dynamical resonance is computed using a high-order
perturbation series, and estimate its radius of convergence. We show that the
position of the dynamical resonance does not coincide precisely with the
ionisation maxima, and that the field switch-on time can dramatically affect
the ionisation signal which, for long switch times, reflects the shape of an
incipient homoclinic. Similarly, the resonance ionisation time can reflect the
time-scale of the separatrix motion, which is therefore longer than
conventional static field Stark ionisation. We explain why these effects should
be observed in the quantum dynamics.
PACs: 32.80.Rm, 33.40.+f, 34.10.+x, 05.45.Ac, 05.45.MtComment: 47 pages, 20 figure
- …