Effects of limeted irrigation on the composition of must and wine of Cabernet Sauvignon under semi-arid conditions

Effects of irrigation were studied in a Cabernet Sauvignon vineyard in the Priorat region of Spain, in order to determine the effect of sprinkler irrigation on fruit ripening as well as on must and wine composition. The soil water potential was measured at different depths and irrigation was started when the soil water potential decreased to -1480 kPa. At this point, moderate doses of water (25 l/vine) were added every fortnight during July and August. The yield of the irrigated vines increased by 20%. The must obtained from irrigated vines showed higer levels of potassium than that of the non-irrigated vines. Total soluble solids increased earlier and more rapidly in irrigated vines. We also found higher levels of malic acid and the total acidity increased in both, must and wine. However, tannins and anthocyanins, were lower in wines of irrigated grapevines. The later result is possible due to a rainfall which occurred before harvest, since phenolics did not decresase when a similar irrigation was applied in subsequent years

The Index Distribution of Gaussian Random Matrices

We compute analytically, for large N, the probability distribution of the number of positive eigenvalues (the index N_{+}) of a random NxN matrix belonging to Gaussian orthogonal (\beta=1), unitary (\beta=2) or symplectic (\beta=4) ensembles. The distribution of the fraction of positive eigenvalues c=N_{+}/N scales, for large N, as Prob(c,N)\simeq\exp[-\beta N^2 \Phi(c)] where the rate function \Phi(c), symmetric around c=1/2 and universal (independent of $\beta$), is calculated exactly. The distribution has non-Gaussian tails, but even near its peak at c=1/2 it is not strictly Gaussian due to an unusual logarithmic singularity in the rate function.Comment: 4 pages Revtex, 4 .eps figures include

Estimation procedures affect the center of pressure frequency analysis

Even though frequency analysis of body sway is widely applied in clinical studies, the lack of standardized proceduresconcerning power spectrum estimation may provide unreliable descriptors. Stabilometric tests were applied to 35 subjects (20-51 years, 54-95 kg, 1.6-1.9 m) and the power spectral density function was estimated for the anterior-posterior center of press uretime series. The median frequency was compared between power spectra estimated according to signal partitioning, samplingrate, test duration, and detrending methods. The median frequency reliability for different test durations was assessed using t heintraclass correlation coefficient. When increasing number of segments, shortening test duration or applying linear detrending,the median frequency values increased significantly up to 137%. Even the shortest test duration provided reliable estimates asobserved with the intraclass coefficient (0.74-0.89 confidence interval for a single 20-s test). Clinical assessment of balance maybenefit from a standardized protocol for center of pressure spectral analysis that provides an adequate relationship betweenresolution and variance. An algorithm to estimate center of pressure power density spectrum is also proposed.Key words: Center of pressure; Spectral analysis; Quiet standing; Estimators; Median frequencyResearch partially supported by CNPq, Fundacao Universitaria Jose Bonifacio (FUJB), and FAPERJ. T.M.M. Vieira was therecipient of MSc scholarship from FAPERJ and CNPq.Received July 18, 2008. Accepted March 3, 200

Critical Behaviour of the Number of Minima of a Random Landscape at the Glass Transition Point and the Tracy-Widom distribution

We exploit a relation between the mean number $N_{m}$ of minima of random Gaussian surfaces and extreme eigenvalues of random matrices to understand the critical behaviour of $N_{m}$ in the simplest glass-like transition occuring in a toy model of a single particle in $N$-dimensional random environment, with $N\gg 1$. Varying the control parameter $\mu$ through the critical value $\mu_c$ we analyse in detail how $N_{m}(\mu)$ drops from being exponentially large in the glassy phase to $N_{m}(\mu)\sim 1$ on the other side of the transition. We also extract a subleading behaviour of $N_{m}(\mu)$ in both glassy and simple phases. The width $\delta{\mu}/\mu_c$ of the critical region is found to scale as $N^{-1/3}$ and inside that region $N_{m}(\mu)$ converges to a limiting shape expressed in terms of the Tracy-Widom distribution

Effective Free Energy for Individual Dynamics

Physics and economics are two disciplines that share the common challenge of linking microscopic and macroscopic behaviors. However, while physics is based on collective dynamics, economics is based on individual choices. This conceptual difference is one of the main obstacles one has to overcome in order to characterize analytically economic models. In this paper, we build both on statistical mechanics and the game theory notion of Potential Function to introduce a rigorous generalization of the physicist's free energy, which includes individual dynamics. Our approach paves the way to analytical treatments of a wide range of socio-economic models and might bring new insights into them. As first examples, we derive solutions for a congestion model and a residential segregation model.Comment: 8 pages, 2 figures, presented at the ECCS'10 conferenc

Stability of the replica symmetric solution for the information conveyed by by a neural network

The information that a pattern of firing in the output layer of a feedforward network of threshold-linear neurons conveys about the network's inputs is considered. A replica-symmetric solution is found to be stable for all but small amounts of noise. The region of instability depends on the contribution of the threshold and the sparseness: for distributed pattern distributions, the unstable region extends to higher noise variances than for very sparse distributions, for which it is almost nonexistant.Comment: 19 pages, LaTeX, 5 figures. Also available at http://www.mrc-bbc.ox.ac.uk/~schultz/papers.html . Submitted to Phys. Rev. E Minor change

Resistive damping implementation as a method to improve controllability in stiff ohmic RF-MEMS switches

This paper presents in detail the entire procedure of calculating the bias resistance of an ohmic RF-MEMS switch, controlled under resistive damping (charge drive technique). In case of a very stiff device, like the North Eastern University switch, the actuation control under resistive damping is the only way to achieve controllability. Due to the short switching time as well as the high actuation voltage, it is not practical to apply a tailored control pulse (voltage drive control technique). Implementing a bias resistor of 33 MΩ in series with the voltage source, the impact velocity of the cantilever has been reduced 80 % (13.2 from 65.9 cm/s), eliminating bouncing and high initial impact force during the pull-down phase. However, this results in an affordable cost of switching time increase from 2.38 to 4.34 μs. During the release phase the amplitude of bouncing has also been reduced 34 % (174 from 255 nm), providing significant improvement in both switching operation phases of the switch. © 2013 Springer-Verlag Berlin Heidelberg