Search results for "Delta"
showing 10 items of 471 documents
Influence of spontaneous hypertension on n-3 delta-6-desaturase activity and fatty acid composition of rat hepatocytes.
1995
The first and rate limiting step in the conversion of alpha-linolenic acid is catalyzed by the delta-6-desaturase enzyme. The activity of such an enzyme was studied in order to investigate the n-3 Polyunsaturated Fatty Acid biogenesis during hypertension. Rat isolated hepatocyte n-3 delta-6-desaturase activity was higher in 1 month old Spontaneously Hypertensive Rats — prehypertensive period- as compared to normotensive Wistar Kyoto rats, whereas there was no significant difference at 12 months — hypertensive period-. Our data indicate no correlation between the directly measured enzyme activity and the changes in hepatocyte n-3 fatty acid compositions. The loss of hepatocyte n-3 delta-6-de…
Altered desaturase activities and fatty acid composition in liver microsomes of spontaneously diabetic Wistar BB rat.
1992
We examined the activities of delta 9, delta 6 and delta 5 desaturases and fatty acid composition of liver microsomes in the insulin-dependent spontaneously diabetic adult female Wistar Bio-Breeding (BB) rat. The diabetic BB rats were subcutaneously injected with different doses of protamine zinc insulin in order to be killed in hyper-, normo- or hypo-glycemic states. Desaturase activities, which are partially inhibited by spontaneous diabetes during the normo- and hyper-glycemic periods, were similarly affected by the various insulin treatment; delta 9 desaturase activity being more depressed than the desaturase activities of either delta 6 of delta 5. Insulin treatment with 10 I.U./kg bod…
Digital power conversion system based on a sigma-delta modulator linear model
2005
This paper presents a new linear model for the sigma-delta (/spl Sigma//spl Delta/) modulator, based on modeling the nonlinear quantizer with a linear factor, and its input-to-output transfer function is given. The use of a 1-bit sigma-delta modulator in DC/DC power converter systems permits to implement a complete digital control. Results of an investigation from a prototype for a DC-DC converter are here reported. Using of a field programmable gate array allows implementing a simple variable control function. The modulator output produces a variable-frequency variable duty-ratio signal to control the switching power transistors.
Functional Principal Components Analysis with Survey Data
2008
This work aims at performing Functional Principal Components Analysis (FPCA) with Horvitz-Thompson estimators when the observations are curves collected with survey sampling techniques. FPCA relies on estimations of the eigenelements of the covariance operator which can be seen as nonlinear functionals. Adapting to our functional context the linearization technique based on the influence function developed by Deville (1999), we prove that these estimators are asymptotically design unbiased and convergent. Under mild assumptions, asymptotic variances are derived for the FPCA’ estimators and convergent estimators of them are proposed. Our approach is illustrated with a simulation study and we…
Ephaptic coupling of myelinated nerve fibers
2001
Numerical predictions of a simple myelinated nerve fiber model are compared with theoretical results in the continuum and discrete limits, clarifying the nature of the conduction process on an isolated nerve axon. Since myelinated nerve fibers are often arranged in bundles, this model is used to study ephaptic (nonsynaptic) interactions between impulses on parallel fibers, which may play a functional role in neural processing.
THE ROLE OF GAMMA-DELTA (γδ) T LYMPHOCYTES IN MELANOMA: BASIC SCIENCE FINDINGS AND CLINICAL CORRELATIONS
2012
INTRODUCTION: Advanced melanoma is associated with a poor prognosis. Numerous clinical trials have focused on the potential of tumor-infiltrating lymphocytes (TILs) for immunotherapy in stage III and IV melanoma, but its treatment remains challenging. Gamma-delta (γδ) T cells are the most represented subpopulation of TILs and have shown therapeutic potentials in many solid tumors, although their role against melanoma has not been fully investigated. MATERIALS AND METHODS: Seventy-four patients with cutaneous melanoma underwent peritumoral skin biopsies and blood sample collection. TILs and circulating lymphocytes phenotype and effector functions were analzyed using immunohistochemistry and …
Convergence of Boobnov-Galerkin Method Exemplified
2004
In this Note, Boobnov–Galerkin’s method is proved to converge to an exact solution for an applied mechanics problem. We address in detail the interrelation of Boobnov–Galerkin method and the exact solution in the beam deflection problems. Namely, we show the coincidence of these two methods for clamped–clamped boundary conditions, using an alternative set of functions proposed by Filonenko-Borodich.12 Received 25 February 2003; accepted for publication 13 March 2004. Copyright c 2004 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Copies of this paper may be made for personal or internal use, on condition that the copier pay the $10.00 per-copy fee to th…
Coupled Discrete Fractional-Order Logistic Maps
2021
This paper studies a system of coupled discrete fractional-order logistic maps, modeled by Caputo’s delta fractional difference, regarding its numerical integration and chaotic dynamics. Some interesting new dynamical properties and unusual phenomena from this coupled chaotic-map system are revealed. Moreover, the coexistence of attractors, a necessary ingredient of the existence of hidden attractors, is proved and analyzed.
Collective-Mode Enhanced Matter-Wave Optics
2021
International audience; In contrast to light, matter-wave optics of quantum gases deals with interactions even in free space and for ensembles comprising millions of atoms. We exploit these interactions in a quantum degenerate gas as an adjustable lens for coherent atom optics. By combining an interaction-driven quadrupole-mode excitation of a Bose-Einstein condensate (BEC) with a magnetic lens, we form a time-domain matter-wave lens system. The focus is tuned by the strength of the lensing potential and the oscillatory phase of the quadrupole mode. By placing the focus at infinity, we lower the total internal kinetic energy of a BEC comprising 101(37) thousand atoms in three dimensions to …
Phylogeny of viroids, viroidlike satellite RNAs, and the viroidlike domain of hepatitis delta virus RNA.
1991
We report a phylogenetic study of viroids, some plant satellite RNAs, and the viroidlike domain of human hepatitis delta virus RNA. Our results support a monophyletic origin of these RNAs and are consistent with the hypothesis that they may be "living fossils" of a precellular RNA world. Moreover, the viroidlike domain of human hepatitis delta virus RNA appears closely related to the viroidlike satellite RNAs of plants, with which it shares some structural and functional properties. On the basis of our phylogenetic analysis, we propose a taxonomic classification of these RNAs.