Preferences of young consumers for joints obtained from the technological division of the rabbit carcass evaluated by photographic images

Una muestra de 405 jóvenes de Andalucía, con edades comprendidas entre 18 y 32 años y con un 54,3% de mujeres, se sometió a dos pruebas de valoración de fotografías con la finalidad de conocer, por una parte, su preferencia entre las piezas pata trasera, pata delantera, pieza lomo y caja torácica procedentes del despiece tecnológico de la canal de conejo y, por otra parte, su preferencia entre la pieza lomo y las chuletas de lomo obtenidas de esta pieza por sección transversal al raquis. En la primera prueba el orden de preferencia, de mayor a menor atractivo, fue la pata trasera, la pieza lomo, la pata delantera y la caja torácica (P<0,001) tanto en hombres como en mujeres y si eran o no consumidores de carne de conejo. En la segunda prueba la pieza lomo fue mejor valorada que las chuletas de lomo (P<0,001) por el conjunto de los sujetos de la muestra, por ambos sexos y por los jóvenes que consumían carne de conejo, mientras que los no consumidores de carne de conejo no mostraron diferencias de valoración entre ambas presentaciones (P>0,05). Los resultados ilustran la mayor aceptación que pueden tener para los consumidores las piezas de la canal con mayor cantidad de carne, sugiriéndose que estas diferencias de preferencia entre piezas de la canal podrían influir en eventuales decisiones de compra de despieces de carne de conejo.A sample of 405 young people from Andalusia (Spain), aged between 18 and 32 years and 54.3% of women was subjected to two tests consisting in scoring of photographic images in order to study i) their preference among hind leg, fore leg, loin and thoracic cage joints obtained from the technological division of the rabbit carcass, and ii) their preference between the loin joint and loin chops obtained by transverse cutting of the raquis. In the first test the decreasing degree of preference was the hind leg, the loin joint, the fore leg and the thoracic cage (P <0.001) in both men and women and whether they were rabbit meat consumer or not. In the second test loin joint reached higher score than loin chops (P <0.001) for all the individuals in the sample, for both sexes and for young people who consume rabbit meat, while non rabbit meat consumers showed no difference in preference between the two presentations (P> 0.05). The results illustrate the higher acceptance that young consumers may show for joints of the carcass with higher meat content, this suggesting that differences in preference among carcass joints could influence any decisions to purchase cuts of rabbit meat

Nonlinear stochastic discrete drift-diffusion theory of charge fluctuations and domain relocation times in semiconductor superlattices

A stochastic discrete drift-diffusion model is proposed to account for the effects of shot noise in weakly coupled, highly doped semiconductor superlattices. Their current-voltage characteristics consist of a number stable multistable branches corresponding to electric field profiles displaying two domains separated by a domain wall. If the initial state corresponds to a voltage on the middle of a stable branch and a sudden voltage is switched so that the final voltage corresponds to the next branch, the domains relocate after a certain delay time. Shot noise causes the distribution of delay times to change from a Gaussian to a first passage time distribution as the final voltage approaches that of the end of the first current branch. These results agree qualitatively with experiments by Rogozia {\it et al} (Phys. Rev. B {\bf 64}, 041308(R) (2001)).Comment: 9 pages, 12 figures, 2 column forma

Temperature dependence of current self-oscillations and electric field domains in sequential tunneling doped superlattices

We examine how the current--voltage characteristics of a doped weakly coupled superlattice depends on temperature. The drift velocity of a discrete drift model of sequential tunneling in a doped GaAs/AlAs superlattice is calculated as a function of temperature. Numerical simulations and theoretical arguments show that increasing temperature favors the appearance of current self-oscillations at the expense of static electric field domain formation. Our findings agree with available experimental evidence.Comment: 7 pages, 5 figure

Bubble and Dew Point Calculations in Multicomponent and Multireactive Mixtures

Bubble and dew point calculations are useful in chemical engineering and play an important role in the study of separation equipments for non-reactive and reactive mixtures. To the best of the authors’s knowledge, few methods have been proposed for these calculations in systems with several chemical reactions. The objective of this paper is to introduce new conditions for performing bubble and dew point calculations in reactive mixtures. We have developed these conditions based on the application of transformed variables of Ung and Doherty (1995). Using these transformed variables, the solution space is restricted to compositions that are already at chemical equilibrium and by consequence the problem dimension is also reduced. The reliability and efficiency of three equation-solving methods are tested and compared using our equilibrium conditions: a) a simultaneous equation-solving approach using Newton method (SESN), b) an equation-decoupling approach using successive substitution method (EDSS) and c) an optimization approach using the stochastic optimization method Simulated Annealing(OSA). Our results indicated that even for simple reactive systems, bubble and dew point calculations are challenging for classical equation-solving methods and require robust strategies. We conclude that OSA and EDSS methods are reliable to locate bubble and dew points in reactive systems. EDSS is more efficient than OSA; however, OSA does not need initial guesses and is more suitable for difficult problems

Quasiperiodic time dependent current in driven superlattices: distorted Poincare maps and strange attractors

Intriguing routes to chaos have been experimentally observed in semiconductor superlattices driven by an ac field. In this work, a theoretical model of time dependent transport in ac driven superlattices is numerically solved. In agreement with experiments, distorted Poincare maps in the quasiperiodic regime are found. They indicate the appearance of very complex attractors and routes to chaos as the amplitude of the AC signal increases. Distorted maps are caused by the discrete well-to-well jump motion of a domain wall during spiky high-frequency self-sustained oscillations of the current.Comment: 10 pages, 4 figure

Evaluación del crecimiento de Pinabete (Abies guatemalensis Rehder) a través de plantas nodrizas

El pinabete (Abies guatemalensis Rehder) es una especie sumamente importante desde el punto de vista, ecológico, social y económico, lo que hace que sea una de las especies forestales mayormente amenazadas en Guatemala. Su aprovechamiento ha sido a una tasa superior a su regeneración natural, principalmente en época navideña, donde su corte y comercialización se considera ilegal y en época navideña su demanda se incrementa como árbol ornamental, debido a sus caracterí­sticas morfológicas, diseño de la planta y aroma caracterí­stico. Con el objeto de mejorar su reproducción se realizó un ensayo experimental para evaluar el efecto que tienen una serie de plantas sobre el crecimiento del pinabete. A este tipo de plantas que le brindan humedad, calor, nutrientes y protección a los árboles que están en crecimiento por regeneración natural o por trasplante se le denomina planta nodriza. La variable evaluada fue el crecimiento en mm de los arbolitos de pinabete luego de 82 dí­as de haber sido trasplantados en asocio con las plantas nodrizas. Los resultados arrojaron que el crecimiento en del pinabete se ve más favorecido cuando se encuentra en asocio con arrayán y musgo, pues en un perí­odo menor a tres meses los arbolitos de A. guatemalensis crecieron 2.4 y 2.1 cm respectivamente, mientras que con el resto de los tratamientos su crecimiento se vio limitado

Inverse ac Josephson Effect for a Fluxon in a Long Modulated Junction

We analyze motion of a fluxon in a weakly damped ac-driven long Josephson junction with a periodically modulated maximum Josephson current density. We demonstrate both analytically and numerically that a pure {\it ac} bias current can drive the fluxon at a {\it resonant} mean velocity determined by the driving frequency and the spatial period of the modulation, provided that the drive amplitude exceeds a certain threshold value. In the range of strongly ``relativistic'' mean velocities, the agreement between results of a numerical solution of the effective (ODE) fluxon equation of motion and analytical results obtained by means of the harmonic-balance analysis is fairly good; morever, a preliminary PDE result tends to confirm the validity of the collective-coordinate (PDE-ODE) reduction. At nonrelativistic mean velocities, the basin of attraction, in position-velocity space, for phase-locked solutions becomes progressively smaller as the mean velocity is decreased.Comment: 15 pages, 26 kbytes, of text in plain LaTeX. A uuencoded, Z-compressed tar archive, 21 kbytes, containing 3 PostScript, [email protected], [email protected], [email protected]

Gibbs Energy Minimization Using Simulated Annealing for Two-phase Equilibrium Calculations in Reactive Systems

Phase equilibrium calculations in systems subject to chemical reactions are involved in the design, synthesis and optimization of reactive separation processes. Until now, several methods have been developed to perform simultaneously physical and chemical equilibrium calculations. However, published methods may face numerical difficulties such as variable initialization dependence, divergence and convergence to trivial solutions or unstable equilibrium states. Besides, these methods generally use conventional composition variables and reactions extents as unknowns which directly affect the numerical implementation, reliability and efficiency of solving strategies. The objective of this work is to introduce and test an alternative approach to perform Gibbs energy minimization in phase equilibrium problems for reactive systems. Specifically, we have employed the transformed composition variables of Ung and Doherty and the stochastic optimization method Simulated Annealing for two-phase equilibrium calculations in reacting systems. Performance of this strategy has been tested using several benchmark problems and results show that proposed approach is generally suitable for the global minimization of transformed Gibbs energy in reactive systems with two-phase equilibrium

Gibbs Energy Minimization Using Simulated Annealing for Two-phase Equilibrium Calculations in Reactive Systems

Phase equilibrium calculations in systems subject to chemical reactions are involved in the design, synthesis and optimization of reactive separation processes. Until now, several methods have been developed to perform simultaneously physical and chemical equilibrium calculations. However, published methods may face numerical difficulties such as variable initialization dependence, divergence and convergence to trivial solutions or unstable equilibrium states. Besides, these methods generally use conventional composition variables and reactions extents as unknowns which directly affect the numerical implementation, reliability and efficiency of solving strategies. The objective of this work is to introduce and test an alternative approach to perform Gibbs energy minimization in phase equilibrium problems for reactive systems. Specifically, we have employed the transformed composition variables of Ung and Doherty and the stochastic optimization method Simulated Annealing for two-phase equilibrium calculations in reacting systems. Performance of this strategy has been tested using several benchmark problems and results show that proposed approach is generally suitable for the global minimization of transformed Gibbs energy in reactive systems with two-phase equilibrium