Information flow through a model of the C. elegans klinotaxis circuit

Understanding how information about external stimuli is transformed into behavior is one of the central goals of neuroscience. Here we characterize the information flow through a complete sensorimotor circuit: from stimulus, to sensory neurons, to interneurons, to motor neurons, to muscles, to motion. Specifically, we apply a recently developed framework for quantifying information flow to a previously published ensemble of models of salt klinotaxis in the nematode worm C. elegans. The models are grounded in the neuroanatomy and currently known neurophysiology of the worm. The unknown model parameters were optimized to reproduce the worm's behavior. Information flow analysis reveals several key principles underlying how the models operate: (1) Interneuron class AIY is responsible for integrating information about positive and negative changes in concentration, and exhibits a strong left/right information asymmetry. (2) Gap junctions play a crucial role in the transfer of information responsible for the information symmetry observed in interneuron class AIZ. (3) Neck motor neuron class SMB implements an information gating mechanism that underlies the circuit's state-dependent response. (4) The neck carries non-uniform distribution about changes in concentration. Thus, not all directions of movement are equally informative. Each of these findings corresponds to an experimental prediction that could be tested in the worm to greatly refine our understanding of the neural circuit underlying klinotaxis. Information flow analysis also allows us to explore how information flow relates to underlying electrophysiology. Despite large variations in the neural parameters of individual circuits, the overall information flow architecture circuit is remarkably consistent across the ensemble, suggesting that information flow analysis captures general principles of operation for the klinotaxis circuit

New models for two real scalar fields and their kinklike solutions

In this work we study the presence of kinks in models described by two real scalar fields in bi-dimensional space-time. We generate new two-field models, constructed from distinct but important one-field models, and we solve them with techniques that we introduce in the current work. We illustrate the results with several examples of current interest to high energy physics.Comment: 8 pages, 6 figures; To appear in Adv. High Energy Phy

On domain walls in a Ginzburg-Landau non-linear S^2-sigma model

The domain wall solutions of a Ginzburg-Landau non-linear $S^2$-sigma hybrid model are unveiled. There are three types of basic topological walls and two types of degenerate families of composite - one topological, the other non-topological- walls. The domain wall solutions are identified as the finite action trajectories (in infinite time) of a related mechanical system that is Hamilton-Jacobi separable in sphero-conical coordinates. The physical and mathematical features of these domain walls are thoroughly discussed.Comment: 26 pages, 18 figure

Femtosecond multichannel photodissociation dynamics of CH3I from the A band by velocity map imaging

4 pages, 3 figures, 1 table.The reaction times of several well-defined channels of the C–I bond rupture of methyl iodide from the A band, which involves nonadiabatic dynamics yielding ground state I(2P3/2) and spin-orbit excited I*(2P1/2) and ground and vibrationally excited CH3 fragments, have been measured by a combination of a femtosecond laser pump-probe scheme and velocity map imaging techniques using resonant detection of ground state CH3 fragments. The reaction times found for the different channels studied are directly related with the nonadiabatic nature of this multidimensional photodissociation reaction.Two of the authors (J. G. I. and J. D.) gratefully acknowledge financial support from the FPI program and the CSIC-Unidades Asociadas program, respectively, of the Spanish Ministry of Education and Science (MEC). This work has been financed by the Spanish MEC through Grant No. CTQ2005-08493- C02-01.Peer reviewe

Selection of lactic bacteria to induce malolactic fermentation in red wine of cv. Cencibel

This paper describes the procedure for the selection of three lactic acid bacteria strains from 40 indigenous strains isolated in two cellars of theSpanish region of Castilla-LaMancha.The isolates were identified by classical microbiological and molecular techniques: Pulsed-Field Gel Electrophoresis (pFGE) of bacterial chromosome fragments obtained from restriction enzymes.Selection was carried out considering the capacity to perform malolactic fermentation (MLF) in wine and the resistance to high alcoholic percentages and low pH levels. Three isolates (two Lactobacillus planta Tum and one Oenococcus oeni) which were able to pass the above mentioned tests were selected. These isolates produced low volatile acidity, showed a moderate resistance to SO2 and did not cause any degradation of residual sugars

How much to copy from others?The role of partial copying in social learning

One of the major ways that people engage in adaptive problemsolving is by copying the solutions of others. Most of the workon this field has focused on three questions: when to copy, whoto copy from, and what to copy. However, how much to copyhas been relatively less explored. In the current research, weare interested in the consequences for a group when its mem-bers engage in social learning strategies with different tenden-cies to copy entire or partial solutions and different complex-ities of search problems. We also consider different networktopologies that affect the solutions visible to each member.Using a computational model of collective problem solving,we demonstrate that strategies where social learning involvespartial copying outperform strategies where individuals copyentire solutions. We analyze the exploration/exploitation dy-namics of these social learning strategies under the differentconditions

Scattering between wobbling kinks

In this paper the scattering between a wobbling kink and a wobbling antikink in the standard $\phi^4$ model is numerically investigated. The dependence of the final velocities, wobbling amplitudes and frequencies of the scattered kinks on the collision velocity and on the initial wobbling amplitude is discussed. The fractal structure becomes more intricate due to the emergence of new resonance windows and the splitting of those arising in the non-excited kink scattering. Outside this phase the final wobbling amplitude exhibits a linear dependence of the collision velocity whereas the final frequency is a decreasing function. By contrast these magnitudes are almost independent of the initial wobbling amplitude.Comment: 20 pages, 13 figure

Comparison of aromatic composition of an endangered variety ('Albilla Dorada') with other recognized aromatic varieties

'Albilla Dorada' is a local and endangered grape variety. It was correctly identified beforehand by analysing six microsatellite regions recommended by the GENRES 081 project plus six other additional regions, resulting in one new genotype not described for any variety according to the literature consulted. The object of this paper is to characterize the aromatic composition of this grape vine genotype not previously described. The minority volatile compounds in the grapes were analysed by gas chromatography-mass spectroscopy (GC-MS) and compared with those of eight known aromatic cultivars: 'Albillo Real', 'Macabeo', 'Malvasía Aromática', 'Gewürztraminer', 'Viognier', 'Malvasía Riojana', 'Riesling' and 'Moscatel de Grano Menudo'. Statistically significant differences between varieties were found as regards the different fractions making up the aromatic composition. 'Albilla Dorada' differed from the rest in that it had higher proportions of alcohols, benzene alcohols and norisoprenoids. In the case of the terpene fraction, it was the variety with the highest proportions of citronellol and terpene hydroxides. Results of this work point out 'Albilla Dorada' is a variety with a singular aromatic identity and highlight the necessity of recovering it before its total disappearance.