Manuel Aldegunde

Bio: Manuel Aldegunde is an academic researcher from University of Warwick. The author has contributed to research in topics: Monte Carlo method & Glycogen. The author has an hindex of 23, co-authored 149 publications receiving 1840 citations. Previous affiliations of Manuel Aldegunde include University of Santiago de Compostela & University of Notre Dame.

Energy metabolism of fish brain.

Abstract: This review focuses on recent research on the metabolic function of fish brain. Fish brain is isolated from the systemic circulation by a blood-brain barrier that allows the transport of glucose, monocarboxylates and amino acids. The limited information available in fishes suggests that oxidation of exogenous glucose and oxidative phosphorylation provide most of the ATP required for brain function in teleosts, whereas oxidation of ketones and amino acids occurs preferentially in elasmobranchs. In several agnathans and benthic teleosts brain glycogen levels rather than exogenous glucose may be the proximate glucose source for oxidation. In situations when glucose is in limited supply, teleost brains utilize other fuels such as lactate or ketones. Information on use of lipids and amino acids as fuels in fish brain is scarce. The main pathways of brain energy metabolism are changed by several effectors. Thus, several parameters of brain energy metabolism have been demonstrated to change post-prandially in teleostean fishes. The absence of food in teleosts elicits profound changes in brain energy metabolism (increased glycogenolysis and use of ketones) in a way similar to that demonstrated in mammals though delayed in time. Environmental factors induce changes in brain energy parameters in teleosts such as the enhancement of glycogenolysis elicited by pollutants, increased capacity for anaerobic glycolysis under hypoxia/anoxia or changes in substrate utilization elicited by adaptation to cold. Furthermore, several studies demonstrate effects of melatonin, insulin, glucagon, GLP-1, cortisol or catecholamines on energy parameters of teleost brain, although in most cases the results are quite preliminary being difficult to relate the effects of those hormones to physiological situations. The few studies performed with the different cell types available in the nervous system of fish allow us to hypothesize few functional relationships among those cells. Future research perspectives are also outlined.

Selective changes in the contents of noradrenaline, dopamine and serotonin in rat brain areas during aging.

Abstract: This study examines the age-associated changes in noradrenaline (NA), dopamine (DA), 3,4-dihydroxyphenyl-acetic acid (DOPAC), serotonin (5-HT) and 5-hydroxy-3-indoleacetic acid (5-HIAA) in different brain areas of rats DA and DOPAC concentrations in striatum increased at third month of age, remaining without significant variations until 12th month of age, and decreasing in 24-month-old rats DA concentration dropped in hippocampus, amygdala and brainstem of 24-month-old-rats, whereas DOPAC levels decreased only in hippocampus These changes suggest an age-dependent deficit of the dopaminergic system, presumably related to a reduced number/activity of DA nigrostriatal and mesolimbic neurons An age-induced decline in NA content was found in the pons-medulla, the area containing NA neuronal bodies Concentrations of 5-HT were reduced with aging in frontal cortex, showing a tendency to decrease in all brain areas examined The increased 5-HIAA/5-HT ratio found in frontal cortex, amygdala and striatum suggests an age-related decreased synthesis and an accelerated 5-HT metabolism The 5-HIAA content decreased in brainstem of the oldest rats These findings point to a selective impairment of nigrostriatal and mesolimbic DA in aging rats, whereas reductions in NA were restricted to cell bodies region and 5-HT showed changes of different extent in areas of terminals and neuronal cell bodies

Effects of pinealectomy on regional brain serotonin metabolism.

Abstract: The influence of pinealectomy on serotonin cerebral metabolism was examined in male rats maintained in a long photoperiod (14 h L : 10 h D). Eight weeks after pinealectomy, serum, hepatic and CNS concentrations of tryptophan were not affected. The concentrations of 5-HT was significantly decreased in only three regions, hypothalamus, midbrain and hippocampus. The levels of 5-HIAA decreased significantly only in the hypothalamus and the midbrain. These results suggest that pinealectomy promotes a decreased hypothalamic and midbrain 5-HT utilization.

Quantum-Transport Study on the Impact of Channel Length and Cross Sections on Variability Induced by Random Discrete Dopants in Narrow Gate-All-Around Silicon Nanowire Transistors

Abstract: In this paper, we review and extend recent work on the effect of random discrete dopants on the statistical variability in gate-all-around silicon nanowire transistors. The electron transport is described using the nonequilibrium Green's function formalism. Full 3-D real-space and coupled-mode-space repre sentations are used. Two different cross sections (i.e., 2.2 × 2.2 and 4.2 × 4.2 nm2) and two different channel lengths (i.e., 6 and 12 nm) have been considered. The resistivity associated with discrete dopants can be estimated from the averaged current-voltage characteristics. The threshold-voltage variability and the sub threshold-slope variability are reduced greatly in the transistors with longer channel length. Both are smaller at equivalent channel lengths in the 2.2 × 2.2 nm2 device due to better electrostatic integrity. At the same time, the ON-state-current variability associated with the varying resistance of the access regions is virtually independent of the channel length. However, it is reduced greatly in the 4.2 × 4.2 nm2 transistor due to a fourfold increase in the number of dopants in the access regions and corresponding self-averaging effects. Finally, we present results for the smallest transistor combining two sources of variability (i.e., discrete random dopants and surface roughness) and phonon scattering.

Study of Discrete Doping-Induced Variability in Junctionless Nanowire MOSFETs Using Dissipative Quantum Transport Simulations

Abstract: The impact of discrete doping in junctionless gate all-around n-type silicon nanowire transistors is studied using 3-D nonequilibrium Green's functions simulations. The studied devices have a 20 nm long gate and cross sections of 4.2 × 4.2 and 6.2 × 6.2 nm2. The average doping concentration is 1020 cm-3. The dopant distributions are randomly generated and modeled in a fully atomistic way. Phonon scattering, elastic and inelastic, is also included in the simulations. We show that junctionless nanowire transistors have a much higher subthreshold variability than their inversion mode counterparts for the equivalent geometry and doping level.

Pattern Recognition and Machine Learning

Abstract: Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

The C programming language

Abstract: This ebook is the first authorized digital version of Kernighan and Ritchie's 1988 classic, The C Programming Language (2nd Ed.). One of the best-selling programming books published in the last fifty years, "K&R" has been called everything from the "bible" to "a landmark in computer science" and it has influenced generations of programmers. Available now for all leading ebook platforms, this concise and beautifully written text is a "must-have" reference for every serious programmers digital library. As modestly described by the authors in the Preface to the First Edition, this "is not an introductory programming manual; it assumes some familiarity with basic programming concepts like variables, assignment statements, loops, and functions. Nonetheless, a novice programmer should be able to read along and pick up the language, although access to a more knowledgeable colleague will help."

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg