Riemannian metrics on an infinite dimensional symplectic group

The aim of this paper is the geometric study of the symplectic operators which are a perturbation of the identity by a Hilbert-Schmidt operator. This subgroup of the symplectic group was introduced in Pierre de la Harpe's classical book of Banach-Lie groups. Throughout this paper we will endow the tangent spaces with different Riemannian metrics. We will use the minimal curves of the unitary group and the positive invertible operators to compare the length of the geodesic curves in each case. Moreover we will study the completeness of the symplectic group with the geodesic distance.Comment: 18 pages. The final version of this preprint will appear in Journal of Mathematical Analysis and Application

Effect of ultrasonication on microbial quality, colour and ascorbic acid of passion-fruit juice during storage

Passion fruit juice (PFJ) has a delicate flavour very susceptible to thermal degradation. This study pursued to test the effect of sonication as non-thermal preservation method on some quality parameters of PFJ. The effect of ultrasound (20 kHz, 263 W, 89.25 µm) on the indigenous microflora, colour and ascorbic acid content of PFJ was studied. Firstly, the kinetic of microbial inactivation was determined for aerobic mesophilic counts and yeasts counts. Data was fitted to Weibull model, and a treatment time of 8 min was selected for stability studies. To this, untreated and sonicated juice was stored at 4 and 10 ºC up to 10 days and microbial quality, instrumental colour, pH and ascorbic acid content were evaluated. In general, ultrasound kept juice microbiologically stable for up to 10 days at 4 ºC without markedly affecting other parameters evaluated. Ultrasound seems suitable to stabilize microbiologically PFJ.Ciencias de la Alimentació

Embedding Theorems for the Dunkl Harmonic Oscillator on the Line

Embedding results of Sobolev type are proved for the Dunkl harmonic oscillator on the line

Suaeda foliosa Moq. (Caryophyllales: Amaranthaceae) first record of the genus and species for Valparaíso Region, Chile

Indexación: Web of Science; Scielo.BACKGROUND: The purpose of this paper is to present the finding of Suaeda foliosa in El Yali National Reserve, Chile. With this finding, the southern limit of the distribution is displaced from the current position at 31° S, 300 km southward. FINDINGS: In this work, we found this species on the banks of the Colejuda lagoon, 33° 45' S, which belongs to a body of hypersaline seasonal water found inside the protected area distinguished as a Ramsar site (No. 878). The determination of the genus and species was achieved by comparing with herbarium material deposited in the National Herbarium SGO Natural History Museum in Santiago de Chile. Once we identified the species, the collected material was deposited in the referred Herbarium (SGO 163975). pH, salinity, and conductivity of the water column and soil adjacent the three protected lagoons are compared, discussing the unique conditions of the lagoon Colejuda that may explain the presence of S. foliosa only in their environment and not in other water bodies. CONCLUSIONS: It can be concluded that El Yali wetland system harbors the S. foliosa southernmost population of the Americas.http://ref.scielo.org/xv9yc

Measuring Social carrying Capacity: An Exploratory Study

The tourist carrying capacity commands a growing interest given that it is closely linked with sustainable tourist development. The justification of the utility of this concept is given by means of a simple and efficient methodological proposal, by analysing the social carrying capacity. To this end, an empirical application is carried out in the Western Andalusia. In some of the cases analysed, the satisfaction of the tourist is found to decline when the levels of the tourist use are higher with respect to those attributes of the tourist destination supply. This mechanism can constitute a useful alarm signal for tourism planners.carrying capacity, tourist satisfaction, sustainable tourism, tourist destination.

MIMO PID Controller Tuning Method for Quadrotor Based on LQR/LQG Theory

In this work, a new pre-tuning multivariable PID (Proportional Integral Derivative) controllers method for quadrotors is put forward. A procedure based on LQR/LQG (Linear Quadratic Regulator/Gaussian) theory is proposed for attitude and altitude control, which suposes a considerable simplification of the design problem due to only one pretuning parameter being used. With the aim to analyze the performance and robustness of the proposed method, a non-linear mathematical model of the DJI-F450 quadrotor is employed, where rotors dynamics, together with sensors drift/bias properties and noise characteristics of low-cost commercial sensors typically used in this type of applications are considered. In order to estimate the state vector and compensate bias/drift effects in the measures, a combination of filtering and data fusion algorithms (Kalman filter and Madgwick algorithm for attitude estimation) are proposed and implemented. Performance and robustness analysis of the control system is carried out by employing numerical simulations, which take into account the presence of uncertainty in the plant model and external disturbances. The obtained results show the proposed controller design method for multivariable PID controller is robust with respect to: (a) parametric uncertainty in the plant model, (b) disturbances acting at the plant input, (c) sensors measurement and estimation errors