Simulated and Actual Effects of the Brown Shrimp, Penaeus aztecus, Closure in Mexico

Simulations based on a yield-per-recruit model were performed to analyze the impact ofg rowth overfishing on brown shrimp, Penaeus aztecus, and to assess the effects of a closed season inshore and offshore of the Mexican States of Tamaulipas and Veracruz. Closure of both the inshore and offshore fisheries could enhance cohort yield by more than 300%. Cohon yield enhancement would be only about 60-80% if only the offshore season were closed. The closed season of 1993 gave better results as it covered a larger part of the brown shrimp peak recruitment period. Catch per unit of effort (CPUE) after closure in 1993, compared with 1994, was 2.4 times higher than the mean CPUE of the month. Total annual offshore yield increased 72% in 1993 (3,800 metric tons (t)) and 10% in 1994 (506 t) with respect to the mean annual offshore catch during the 10-year period prior to the 1993 closure. Simulation results could help identify alternatives that permit the coexistence of the inshore and offshore fisheries while maintaining high profitability of the brown shrimp fishery

Fecundity of Litopenaeus setiferus, Farfantepenaeus aztecus and F. duorarum, in the Southwestern Gulf of Mexico

Fecundity of white shrimp, Litopenaeus setiferus, brown shrimp, Farfantepenaeus aztecus, and pink shrimp F. duorarum and relationships to gonad weights and total and carapace length were estimated. Ovigerous females were collected in the southern Gulf of Mexico in February, May, August and November 1993. Fecundity was estimated by means of a gravimetric method. The equations relating fecundity to total weight and fecundity to gonad weight were linear in the 3 species. However, an exponential relationship was found between fecundity and carapace length in L. setiferus and F. aztecus. Of the relationships examined, gonad weight was considered a more precise indicator of fecundity. Fecundity estimates ranged from 70,647 to 558,270 eggs for 0.203 and 5.639 g gonad weight of L. setiferus, from 23,298 to 494,292 eggs for 0.061 to 2.561 g gonad weight in F. aztecus and from 138,618 to 225,543 eggs for 0.120 to 0.998 g gonad weight in F. duorarum

Parasitization of Callinectes rathbunae and Callinectes sapidus by the Rhizocephalan Barnacle Loxothylacus texanus in Alvarado Lagoon, Veracruz, Mexico

Callinectes rathbunae and CalIinectes sapidus in Alvarado Lagoon, Mexico, were sampled monthly for one year to determine the extent of parasitization by the rhizocephalan cirripede Loxothylacus texanus. Prevalence levels. host sex ratio, carapace width-weight variation, and distribution of the number of parasites among hosts were analyzed. Loxothylacus texanus was present almost exclusively in C. rathbunae with a mean prevalence of 7.58%, while less than 1% of all C. sapidus were parasitized. Callinectes rathbunae constitutes a new host record for this parasite. A study of infection revealed significant variation in prevalence and host size throughout the study period. The sex ratio of parasitized crabs differed from that of the total sample with mares being parasitized more often, and the comparison of carapace width-weight relationships revealed lower weights of parasitized crabs

Parasitization of Callinectes rathbunae and Callinectes sapidus by the Rhizocephalan Barnacle Loxothylacus texanus in Alvarado Lagoon, Veracruz, Mexico

Callinectes rathbunae and CalIinectes sapidus in Alvarado Lagoon, Mexico, were sampled monthly for one year to determine the extent of parasitization by the rhizocephalan cirripede Loxothylacus texanus. Prevalence levels. host sex ratio, carapace width-weight variation, and distribution of the number of parasites among hosts were analyzed. Loxothylacus texanus was present almost exclusively in C. rathbunae with a mean prevalence of 7.58%, while less than 1% of all C. sapidus were parasitized. Callinectes rathbunae constitutes a new host record for this parasite. A study of infection revealed significant variation in prevalence and host size throughout the study period. The sex ratio of parasitized crabs differed from that of the total sample with mares being parasitized more often, and the comparison of carapace width-weight relationships revealed lower weights of parasitized crabs

Integration through genetic programming on heterogeneous systems.

Nowadays, numerous applications in various scientific fields require the integration of mathematical functions that, due to some of their characteristics, do not have an analytical expression for their antiderivative. These definite integrals are usually solved by numerical integration methods, which provide an approximation of the numerical value of the integral in the integration range. With this type of solutions, a higher precision of the approximation entails a longer computation time, being necessary a trade-off between both aspects. In this work we present a genetic programming algorithm which provides mathematical expressions that approximate the antiderivative of analytically non-integrable functions. Heterogeneous devices, GPU and multicore CPU, have also been used in the development of the system to accelerate the parts suitable for it. The advantage of obtaining these approximate antiderivatives is the reduction of the computation time necessary to calculate the definite integral of the functions of interest, reducing it to simply evaluating the expression at the beginning and the end of the integration range.<br /

Virtual Reality-Based Interface for Advanced Assisted Mobile Robot Teleoperation

[EN] This work proposes a new interface for the teleoperation of mobile robots based on virtual reality that allows a natural and intuitive interaction and cooperation between the human and the robot, which is useful for many situations, such as inspection tasks, the mapping of complex environments, etc. Contrary to previous works, the proposed interface does not seek the realism of the virtual environment but provides all the minimum necessary elements that allow the user to carry out the teleoperation task in a more natural and intuitive way. The teleoperation is carried out in such a way that the human user and the mobile robot cooperate in a synergistic way to properly accomplish the task: the user guides the robot through the environment in order to benefit from the intelligence and adaptability of the human, whereas the robot is able to automatically avoid collisions with the objects in the environment in order to benefit from its fast response. The latter is carried out using the well-known potential field-based navigation method. The efficacy of the proposed method is demonstrated through experimentation with the Turtlebot3 Burger mobile robot in both simulation and real-world scenarios. In addition, usability and presence questionnaires were also conducted with users of different ages and backgrounds to demonstrate the benefits of the proposed approach. In particular, the results of these questionnaires show that the proposed virtual reality based interface is intuitive, ergonomic and easy to use.This research was funded by the Spanish Government (Grant PID2020-117421RB-C21 funded byMCIN/AEI/10.13039/501100011033) and by the Generalitat Valenciana (Grant GV/2021/181).Solanes, JE.; Muñoz García, A.; Gracia Calandin, LI.; Tornero Montserrat, J. (2022). Virtual Reality-Based Interface for Advanced Assisted Mobile Robot Teleoperation. Applied Sciences. 12(12):1-22. https://doi.org/10.3390/app12126071122121

Teleoperation of industrial robot manipulators based on augmented reality

This research develops a novel teleoperation for robot manipulators based on augmented reality. The proposed interface is equipped with full capabilities in order to replace the classical teach pendant of the robot for carrying out teleoperation tasks. The proposed interface is based on an augmented reality headset for projecting computer-generated graphics onto the real environment and a gamepad to interact with the computer-generated graphics and provide robot commands. In order to demonstrate the benefits of the proposed method, several usability tests were conducted using a 6R industrial robot manipulator in order to compare the proposed interface and the conventional teach pendant interface for teleoperation tasks. In particular, the results of these usability tests show that the proposed approach is more intuitive, ergonomic, and easy to use. Furthermore, the comparison results also show that the proposed method clearly improves the velocity of the teleoperation task, regardless of the user's previous experience in robotics and augmented reality technology

A Methodology to Produce Augmented-Reality Guided Tours in Museums for Mixed-Reality Headsets

[EN] In recent years, the use of technology in the museum context has changed radically. It has switched from the display of information to offering emotive, immersive, and rich experiences with heritage. Virtual interactive media have the potential to put museums back into a relevant place in our increasingly digital society. The emergence of augmented-reality glasses offers the possibility to test and implement new methodologies compatible with this aim. However, most of the first examples developed in recent years did not take advantage of the possibilities of this new medium. This paper presents a novel methodology for producing mixed-reality applications for museums and heritage sites, with an intuitive, immersive, and natural way of operating. An experimental prototype designed for the archaeological museum of the Almoina is shown in the paper to demonstrate the benefits of the proposed system and methodology of production. In addition, the paper shows the results of several tests.This research was founded by the Generalitat Valenciana (Grant GV/2021/181) and by the Spanish Government (Grant PID2020-117421RB-C21 funded by MCIN/AEI/10.13039/501100011033).Martí-Testón, A.; Muñoz García, A.; Solanes Galbis, JE.; Gracia Calandin, LI.; Tornero Montserrat, J. (2021). A Methodology to Produce Augmented-Reality Guided Tours in Museums for Mixed-Reality Headsets. Electronics. 10(23):1-21. https://doi.org/10.3390/electronics10232956121102

Evaluación del estado de la pesquería de camarón en el Golfo de Tehuantepec

Considering the integration of the total catches of white, brown, blue and crystal shrimp in a single population, the shrimp fishery in the Gulf of Tehuantepec was evaluated between 1960 and 2002 . Schaefers model estimated a value of optimal effort (fOPT) of 151 ships and an optimal catch (COPT) of 2,342 ton (r = 0.723, p &lt; 0.05). The models of Fox and Schaefer estimated 84 ships and 2,673 ton (r = 0.806 , p &lt; 0.05), and 110 ships and 1,504 ton (I=39.41%), respectively. Considering the Schaefers model, two exploitation periods were observed. The first period from 1960 to 1980, during which the fishing effort was mantained relatively constant in approximately 150 and 200 ships; whereas, the second one, from 1981 to 2002, showed a fluctuation between 220 and 350 ships. Comparisons with other units of fishing effort were not made, nevertheless, the interannual variability of the capture in the first period was similar to that reported for the Gulf of Tehuantepec from 1949 to 1981, which considered the number of ships in order to develop the Schaefers model. Independently of the unit of the fishing effort utilized, both evaluations suggest that the optimal level of catch was reached and surpassed at the end of the 70s and the beginning of the 80s. This provoked the reduction of the catches during the second period. In this last period, the rate of artisanal exploitation between 1983 and 2000 was not estimated, nevertheless, we considered that it must have been greater than what was obtained by the marine fishery (0,69 annual). The combination of both fisheries has increased the level of fishing effort on the populations of shrimp in the Gulf of Tehuantepec, resulting in a critical level of explotationConsiderando la integración de las capturas totales de camarón blanco, café, azul y cristal en una sola población, se evalúo la pesquería de camarón del Golfo de Tehuantepec entre los años 1960 y 2002. El modelo de Schaefer estimó un valor de esfuerzo óptimo (fOPT) de 151 barcos y una captura óptima (COPT) de 2,342 ton (r = 0.723, p &lt; 0.05). Los modelos de Fox y Schnute resultaron respectivamente en 84 barcos y 2,673 ton (r = 0.806 y p &lt; 0.05) y 110 barcos con 1,504 ton (I=39.41%). A partir del modelo de Schaefer se observaron dos períodos de explotación. El primer período ocurrió de 1960 a 1980, en donde el esfuerzo de pesca se mantuvo relativamente constante en aproximadamente 150 y 200 barcos; mientras que en el segundo, de 1981 a 2002, registró una fluctuación de 220 y 350 barcos. No se realizaron comparaciones con otras unidades de esfuerzo pesquero; sin embargo, la variabilidad interanual de la captura en el primer período, resultó similar al reportado en el Golfo de Tehuantepc de 1949 a 1981, en el que se consideró el número de viajes para desarrollar el modelo de Schaefer. Independientemente de la unidad del esfuerzo pesquero, ambas evaluaciones sugieren que el nivel óptimo de captura se alcanzó y superó a finales de los años setentas y principios de los ochentas. Lo anterior provocó la disminución de las capturas durante el segundo período. En este último, la tasa de explotación ribereña entre 1983 y 2000 no fue estimada, no obstante, se considera que debió haber sido mayor a la obtenida en alta mar (0.69 anual). La combinación de ambas pesquerías, ha incrementado el nivel del esfuerzo pesquero sobre las poblaciones de camarón en el Golfo de Tehuantepec, que la sitúan en un nivel crítico de explotación