Spatiotemporal chaotic dynamics of solitons with internal structure in the presence of finite-width inhomogeneities

We present an analytical and numerical study of the Klein-Gordon kink-soliton dynamics in inhomogeneous media. In particular, we study an external field that is almost constant for the whole system but that changes its sign at the center of coordinates and a localized impurity with finite-width. The soliton solution of the Klein-Gordon-like equations is usually treated as a structureless point-like particle. A richer dynamics is unveiled when the extended character of the soliton is taken into account. We show that interesting spatiotemporal phenomena appear when the structure of the soliton interacts with finite-width inhomogeneities. We solve an inverse problem in order to have external perturbations which are generic and topologically equivalent to well-known bifurcation models and such that the stability problem can be solved exactly. We also show the different quasiperiodic and chaotic motions the soliton undergoes as a time-dependent force pumps energy into the traslational mode of the kink and relate these dynamics with the excitation of the shape modes of the soliton.Comment: 10 pages Revtex style article, 22 gziped postscript figures and 5 jpg figure

Time discrimination of impulsive overlapping echos

This paper presents the processing of on acoustic echo built up by a sum of identical replicas of a given emitted signal; the sum terms have différent amplitude and phase . The method here presented consists in comparing, in a recurrent way, the envelope and the phase function of the echo with those of the emitted signal, and then getting the delays and amplitudes of the pulses that made up the echo.Traitement d'un écho acoustique lorsque celui-ci est la somme d'impulsions identiques au signal émis, mais avec une amplitude et un retard différent

Cytochrome c Deficiency Differentially Affects the In Vivo Mitochondrial Electron Partitioning and Primary Metabolism Depending on the Photoperiod

Plant respiration provides metabolic flexibility under changing environmental conditions by modulating the activity of the nonphosphorylating alternative pathways from the mitochondrial electron transport chain, which bypass the main energy-producing components of the cytochrome oxidase pathway (COP). While adjustments in leaf primary metabolism induced by changes in day length are well studied, possible differences in the in vivo contribution of the COP and the alternative oxidase pathway (AOP) between different photoperiods remain unknown. In our study, in vivo electron partitioning between AOP and COP and expression analysis of respiratory components, photosynthesis, and the levels of primary metabolites were studied in leaves of wild-type (WT) plants and cytochrome c (CYTc) mutants, with reduced levels of COP components, under shortand long-day photoperiods. Our results clearly show that differences in AOP and COP in vivo activities between WT and cytc mutants depend on the photoperiod likely due to energy and stress signaling constraints. Parallel responses observed between in vivo respiratory activities, TCA cycle intermediates, amino acids, and stress signaling metabolites indicate the coordination of different pathways of primary metabolism to support growth adaptation under different photoperiods.info:eu-repo/semantics/publishedVersio

Configuration Complexities of Hydrogenic Atoms

The Fisher-Shannon and Cramer-Rao information measures, and the LMC-like or shape complexity (i.e., the disequilibrium times the Shannon entropic power) of hydrogenic stationary states are investigated in both position and momentum spaces. First, it is shown that not only the Fisher information and the variance (then, the Cramer-Rao measure) but also the disequilibrium associated to the quantum-mechanical probability density can be explicitly expressed in terms of the three quantum numbers (n, l, m) of the corresponding state. Second, the three composite measures mentioned above are analytically, numerically and physically discussed for both ground and excited states. It is observed, in particular, that these configuration complexities do not depend on the nuclear charge Z. Moreover, the Fisher-Shannon measure is shown to quadratically depend on the principal quantum number n. Finally, sharp upper bounds to the Fisher-Shannon measure and the shape complexity of a general hydrogenic orbital are given in terms of the quantum numbers.Comment: 22 pages, 7 figures, accepted i

Effects of dietary eicosapentaenoic acid on growth, survival, pigmentation and fatty acid composition in Senegal sole (Solea senegalensis) larvae during the Artemia feeding period

We examined the effect of dietary eicosapentaenoic acid (20:5n-3, EPA) on growth, survival, pigmentation and fatty acid composition of Senegal sole larvae using a dose-response design. From 3 to 40 days post hatch (dph), larvae were fed live food that had been enriched using one of four experimental emulsions containing graduated concentrations of EPA and constant docosahexaenoic acid (22:6n-3, DHA) and arachidonic acid (20:4n-6, ARA). Proportions of EPA in the enriched Artemia nauplii were described as “nil” (EPA-N, 0.5% total fatty acids, TFA), “low” (EPA-L, 10.7% TFA), “medium” (EPA-M, 20.3% TFA) or “high” (EPA-H, 29.5% TFA). Significant differences among dietary treatments in larval length were observed at 25, 30 and 40 dph, and in dry weight at 30 and 40 dph, although no significant correlation could be found between dietary EPA content and growth. The stage of eye migration at 17 and 25 dph was significantly affected by dietary levels of EPA. Significantly lower survival was observed in fish fed EPA-H enriched nauplii. A significantly lower percentage of fish fed EPA-N (82.7%) and EPA-L (82.9%) diets were normally pigmented compared to the fish fed EPA-M (98.1%) and EPA-H (99.4%) enriched nauplii. Tissue fatty acid concentrations reflected the corresponding dietary composition. Arachidonic and docosahexaenoic acid levels in all the tissues examined were inversely related to dietary EPA. There was an increase in the proportion of docosapentaenoic acid (22:5n-3, DPA) in the tissues relative to the diet, which is indicative of chain elongation of EPA. This work concluded that Senegal sole larvae have a very low EPA requirement during the live feeding period

SUMOylation of synaptic and synapse-associated proteins:An update

SUMOylation is a post‐translational modification that regulates protein signalling and complex formation by adjusting the conformation or protein–protein interactions of the substrate protein. There is a compelling and rapidly expanding body of evidence that, in addition to SUMOylation of nuclear proteins, SUMOylation of extranuclear proteins contributes to the control of neuronal development, neuronal stress responses and synaptic transmission and plasticity. In this brief review we provide an update of recent developments in the identification of synaptic and synapse‐associated SUMO target proteins and discuss the cell biological and functional implications of these discoveries. [Image: see text

The Mesencephalic Locomotor Region Recruits V2a Reticulospinal Neurons to Drive Forward Locomotion in Larval Zebrafish

The mesencephalic locomotor region (MLR) is a brain stem area whose stimulation triggers graded forward locomotion. How MLR neurons recruit downstream vsx2+ (V2a) reticulospinal neurons (RSNs) is poorly understood. Here, to overcome this challenge, we uncovered the locus of MLR in transparent larval zebrafish and show that the MLR locus is distinct from the nucleus of the medial longitudinal fasciculus. MLR stimulations reliably elicit forward locomotion of controlled duration and frequency. MLR neurons recruit V2a RSNs via projections onto somata in pontine and retropontine areas, and onto dendrites in the medulla. High-speed volumetric imaging of neuronal activity reveals that strongly MLR-coupled RSNs are active for steering or forward swimming, whereas weakly MLR-coupled medullary RSNs encode the duration and frequency of the forward component. Our study demonstrates how MLR neurons recruit specific V2a RSNs to control the kinematics of forward locomotion and suggests conservation of the motor functions of V2a RSNs across vertebrates

The mesencephalic locomotor region recruits V2a reticulospinal neurons to drive forward locomotion in larval zebrafish

The mesencephalic locomotor region (MLR) is a brain stem area whose stimulation triggers graded forward locomotion. How MLR neurons recruit downstream vsx2+ (V2a) reticulospinal neurons (RSNs) is poorly understood. Here, to overcome this challenge, we uncovered the locus of MLR in transparent larval zebrafish and show that the MLR locus is distinct from the nucleus of the medial longitudinal fasciculus. MLR stimulations reliably elicit forward locomotion of controlled duration and frequency. MLR neurons recruit V2a RSNs via projections onto somata in pontine and retropontine areas, and onto dendrites in the medulla. High-speed volumetric imaging of neuronal activity reveals that strongly MLR-coupled RSNs are active for steering or forward swimming, whereas weakly MLR-coupled medullary RSNs encode the duration and frequency of the forward component. Our study demonstrates how MLR neurons recruit specific V2a RSNs to control the kinematics of forward locomotion and suggests conservation of the motor functions of V2a RSNs across vertebrates. Carbo-Tano and colleagues investigate the mesencephalic locomotor region in larval zebrafish and its role in triggering forward locomotion by activating specific sets of hindbrain V2a reticulospinal neurons

Rollover cyclometalation vs nitrogen coordination in Tetrapyridyl Anticancer Gold(III) complexes: effect on protein interaction and toxicity

In this work, a pair of gold(III) complexes derived from the analogous tetrapyridyl ligands H(2)biqbpy1 and H(2)biqbpy2 was prepared: the rollover, bis-cyclometalated [Au(biqbpy1)Cl ([1]Cl) and its isomer [Au(biqbpy2)Cl ([2]Cl). In [1](+), two pyridyl rings coordinate to the metal via a Au-C bond ((CNNC)-N-boolean AND-N-boolean AND-C-boolean AND coordination) and the two noncoordinated amine bridges of the ligand remain protonated, while in [2](+) all four pyridyl rings of the ligand coordinate to the metal via a Au-N bond ((NNNN)-N-boolean AND-N-boolean AND-N-boolean AND coordination), but both amine bridges are deprotonated. As a result, both complexes are monocationic, which allowed comparison of the sole effect of cyclometalation on the chemistry, protein interaction, and anticancer properties of the gold(III) compounds. Due to their identical monocationic charge and similar molecular shape, both complexes [1]Cl and [2]Cl displaced reference radioligand [H-3]dofetilide equally well from cell membranes expressing the K(v)11.1 (hERG) potassium channel, and more so than the tetrapyridyl ligands H(2)biqbpy1 and H(2)biqbpy2. By contrast, cyclometalation rendered [1]Cl coordinatively stable in the presence of biological thiols, while [2]Cl was reduced by a millimolar concentration of glutathione into metastable Au(I) species releasing the free ligand H(2)biqbpy2 and TrxR-inhibiting Au+ ions. The redox stability of [1]Cl dramatically decreased its thioredoxin reductase (TrxR) inhibition properties, compared to [2]Cl. On the other hand, unlike [2]Cl, [1]Cl aggregated into nanoparticles in FCS-containing medium, which resulted in much more efficient gold cellular uptake. [1]Cl had much more selective anticancer properties than [2]Cl and cisplatin, as it was almost 10 times more cytotoxic to human cancer cells (A549, A431, A375, and MCF7) than to noncancerous cells (MRC5). Mechanistic studies highlight the strikingly different mode of action of the two compounds: while for [1]Cl high gold cellular uptake, nuclear DNA damage, and interaction with hERG may contribute to cell killing, for [2]Cl extracellular reduction released TrxR-inhibiting Au+ ions that were taken up in minute amounts in the cytosol, and a toxic tetrapyridyl ligand also capable of binding to hERG. These results demonstrate that bis-cyclometalation is an appealing method to improve the redox stability of Au(III) compounds and to develop gold-based cytotoxic compounds that do not rely on TrxR inhibition to kill cancer cells.Medicinal ChemistryMetals in Catalysis, Biomimetics & Inorganic Material