La universitas, un crisol de la opinión

La lección recupera la categoría de natalidad en Hannah Arendt para poner de relieve el carácter único e iniciante de la palabra humana, que implicada en un intercambio dialógico de opiniones, donde el diseño del lugar y convivencia para un ejercicio gozoso de conversación que se abre reverentemente a la otredad de la persona con quien se dialoga, constituye la base fundamental de una comunidad política, asamblea, que se convierta en fermento de una sociedad más democrática. Ese es el rol, propone el autor, que puede jugar la universidad en las circunstancias que actualmente amenazan con condenarnos al silencio o a la unanimidad impuesta

Vertical Jumping as a Monitoring Tool in Endurance Runners: A Brief Review

Jumping performance (e.g., countermovement jump [CMJ]), as a measure of neuromuscular performance, has been suggested as an easy-to-use tool which simultaneously provides neuromuscular and metabolic information and, thereby, allows coaches to confidently monitor the status of their athletes during a workout. This hypothesis has been satisfactorily tested with sprint athletes. However, the rationale for the use of CMJ height loss as an index to monitor the workload during an endurance running session is not sufficiently evidence-based. First, it is assumed that a CMJ height loss occurs during typical interval training for endurance runners. Second, it is also assumed that a significant relationship between metabolic stress and the neuromuscular strain induced during these endurance workouts exists. These two assumptions will be questioned in this review by critically analyzing the kinetics of CMJ performance during and after running workouts, and the relationship between neuromuscular and physiological stress induced during different protocols in endurance runners. The current evidence shows that fatigue induced by common running workouts for endurance runners does not counterbalance the potentiation effect in the CMJ height. Additionally, the findings reported among different studies are consistent regarding the lack of association between CMJ height loss and physiological stress during interval sessions in endurance runners. In practical terms, the authors suggest that this marker of neuromuscular fatigue may not be used to regulate the external training load during running workouts in endurance runners. Nevertheless, the analysis of CMJ height during running workouts may serve to monitor chronic adaptations to training in endurance runners

The variability of strength production capacities during a judo contest

Background. The muscular response of athletes in a judo contest is one of the most important aspect to measure with precision. Objective. Our purpose was to obtain and analyse the variability of strength associated to muscular performance parameters during a judo contest. Methods. Thirty-five men performed five 5-minute bouts with 15 minutes of passive rest. Immediately after each bout, muscular performance parameters were tested: countermovement jump (CMJ), maximal dynamic strength capacities (mean power velocity (MPV), mean strength (MS), maximum strength (MXS), mean power (MP) and maximum power (MXP)) in upper body, dominant (DHS) and non-dominant handgrip isometric strength (NDHS). ANOVA to compare baseline test data and successive bouts was used. Results. ANOVA revealed significant differences in NDHS (p<0.001), DHS (p<0.001), CMJ (p<0.001), MPV (p<0.001), MXS (p<0.001), MP (p<0.001) and MXP (p<0.001). No significant differences in MS (p = 0.008) were found. Some significant correlations between NDHS and ΔPMX (r=0.368, p=0.050), MPV and ΔMXS (r=0.528, p=0.001) and ΔMXP (r=0.683, p<0.001), MPX and ΔMXS (r=0.528, p=0.001) and ΔMP (r=0.877, p<0.001) were found. Conclusion. Due to judo contest can be considered a high intensity exercise, it produces an amount of muscular fatigue and therefore significant loss strength that it cannot be recovery during rest-times between successive bouts. For this reason, it was a high variability in strength production capacities, which are modified during a judo contest

Neuromuscular performance of explosive power athletes versus untrained individuals

Electromechanical delay (EMD) and rate of force development (RFD) are determinants of explosive neuromuscular performance. We may expect a contrast in EMD and RFD between explosive power athletes, who have a demonstrable ability for explosive contractions, and untrained individuals. However, this comparison, and the neuromuscular mechanisms for any differences, has not been studied. The neuromuscular performance of explosive power athletes (n = 9) and untrained controls (n = 10) was assessed during a series of twitch, tetanic, explosive and maximum voluntary, isometric knee extensions. Knee extension force and EMG of the superficial quadriceps was measured in three 50 ms time windows from their onset, and normalised to strength and maximal M-wave (Mmax), respectively. Involuntary and voluntary EMD were determined from twitch and explosive voluntary contractions, respectively, and were similar for both groups. The athletes were 28% stronger and their absolute RFD in the first 50 ms was 2-fold that of controls. Athletes had greater normalised RFD (4.86 ± 1.46 vs. 2.81 ± 1.20 MVC.s-1) and neural activation (mean quadriceps, 0.26 ± 0.07 vs. 0.15 ± 0.06 Mmax) during the first 50 ms of explosive voluntary contractions. Surprisingly the controls had a greater normalised RFD in the second 50 ms (6.68 ± 0.92 vs. 7.93 ± 1.11 MVC.s-1) and a greater change in EMG preceding this period. However, there were no differences in the twitch response or normalised tetanic RFD between groups. The differences in voluntary normalised RFD between athletes and controls were explained by agonist muscle neural activation, and not the similar intrinsic contractile properties of the groups

Anaerobic Speed Reserve, Sprint Force–Velocity Profile, Kinematic Characteristics, and Jump Ability among Elite Male Speed-and Endurance-Adapted Milers

This study aimed to compare sprint, jump performance, and sprint mechanical variables between endurance-adapted milers (EAM, specialized in 1500–3000-m) and speed-adapted milers (SAM, specialized in 800–1500 m) and to examine the relationships between maximal sprint speed (MSS), anaerobic speed reserve (ASR), sprint, jump performance, and sprint mechanical characteristics of elite middle-distance runners. Fifteen participants (8 EAM; 7 SAM) were evaluated to obtain their maximal aerobic speed, sprint mechanical characteristics (force–velocity profile and kinematic variables), jump, and sprint performance. SAM displayed greater MSS, ASR, horizontal jump, sprint performance, and mechanical ability than EAM (p < 0.05). SAM also showed higher stiffness in the 40-m sprint (p = 0.026) and a higher ratio of horizontal-to-resultant force (RF) at 10 m (p = 0.003) and RFpeak (p = 0.024). MSS and ASR correlated with horizontal (r = 0.76) and vertical (r = 0.64) jumps, all sprint split times (r ≤ −0.85), stiffness (r = 0.86), and mechanical characteristics (r ≥ 0.56) during the 100-m sprint, and physical qualities during acceleration (r ≥ 0.66) and sprint mechanical effectiveness from the force–velocity profile (r ≥ 0.69). Season-best times in the 800 m were significantly correlated with MSS (r = −0.86). Sprint ability has a crucial relevance in middle-distance runners’ performance, especially for SA

Force–velocity profiles in CrossFit athletes: A cross-sectional study considering sex, age, and training frequency

Introduction: The force–velocity profile has been analysed previously in different sports modalities; nevertheless, it has not been analysed in CrossFit. Objective: The aim of this study was to report neuromuscular characteristics of CrossFit athletes using their individual force-velocity profile, investigating differences according to sex, age, and training frequency. Materials and Meth-ods: 72 males (33.17 ± 6.86 years; BMI: 25.93 ± 3.64 kg/m2) and 18 females (30.11 ± 6.92 years; BMI: 23.53 ± 3.98 kg/m2) participated in this study. The force-velocity profile was calculated using Samo-zino’s method. Furthermore, neuromuscular characterization was completed with a squat jump and three drop jumps (20, 30, and 40 cm). Results: Regarding sex, significant differences in all analysed mechanical variables (p < 0.001) were found except for the theoretical maximal force (p = 0.944). No significant differences were found between age groups. Considering training frequency, athletes who train more than 5 days per week showed higher performance in all analysed mechanical variables (p < 0.05). Conclusion: CrossFit athletes have a force-velocity profile more oriented towards velocity than force. Males and females have different neuromuscular characteristics, also neuromus-cular improvements can be achieved at any age. Moreover, higher neuromuscular performance is developed with a training frequency of 5 days or more per week

Pollen collection and honey bee forager distribution in cantaloupe

Honey bee (Apis mellifera, L.) pollen collection and forager distribution were examined during the 2002 summer in a cantaloupe (Cucumis melo, L., Cruiser cv ) field with plastic mulch and drip irrigated. The experimental site was located near the INIFAP Campo Experimental La Laguna, Matamoros, Coahuila within La Laguna region, Mexico. Two trials were conducted in the same location, but were separated by a 800 m wide pecan orchard. Both cantaloupe trials were planted the same date. Trial 1. Nine honey-bee hives were placed in a three hectare field at the start of bloom. Each hive was fitted with a modified-Ontario pollen trap. The pollen was collected one day a week from each colony every hour beginning from 8:30 hr to 14:30 hr during the first four blooming weeks of the crop. Trial 2. Three weeks after the start of bloom, in a ten-ha field 30 honey bee colonies were located. In four randomlyselected rows of 105 m long, 10 m transects at 25, 50, 75 and 100 m distances from the apiary were marked. The foraging bees were counted simultaneously at the transects every half hour from 7:30 hr until 20:30 hr at the same pollen collection-day during the third week of cantaloupe bloom. Pollen collection was higher early in the morning (22.6 g per colony), dropping to medium amount from 9:30 hr (13.7 g), 10:30 hr (12.5 g) to 11:30 hr (9.5 g) and remaining low from 12:30 through the afternoon (less than 2.6 g per colony; p&lt; 0.05). The distribution pattern showed that bees were in the cantaloupe after 8:00 hr, reaching a maximum between 10:30 hr and 14:30 hr when the bees began to decrease, until foraging flights ceased completely at about 20:30 hr. No statistical differences were found in the number of foraging bees among the evaluated distances from the apiary.Durante el verano del 2002 la colecta de polen y la distribución de las abejas (Apis mellifera L.) pecoreadoras fueron estudiadas en el cultivo de melón (Cucumis melo L., cv Cruiser ) bajo condiciones de riego por goteo y acolchado plástico. El lote experimental estuvo localizado cerca del Campo Experimental La Laguna del INIFAP, en el municipio de Matamoros, Coahuila, México. Dos experimentos se realizaron en el mismo predio, en lotes separados 800 m por una huerta de nogal. Ambas superficies de melón fueron sembradas en la misma fecha. Experimento N° 1. Al inicio de la floración se colocaron nueve colmenas en tres hectáreas de cultivo. Cada colmena contó con una trampa de polen tipo Ontario modificada. El polen se colectó cada hora de cada colmena un día por semana de las 8:30 hr a las 14:30 hr durante las cuatro primeras semanas de floración del cultivo. Experimento N° 2. Tres semanas después del inicio de la floración se colocaron 30 colmenas en un campo de melón de diez hectáreas. En cuatro surcos de 105 m de longitud se marcaron transectos de diez metros a 25, 50, 75 y 100 metros de distancia del apiario. Las abejas pecoreadoras fueron contadas simultáneamente en cada transecto cada media hora de las 7:30 hr hasta las 20:30 horas, el mismo día en que fue colectado el polen de la tercera semana de floración. La colecta de polen fue mayor temprano por la mañana (22.6 g por colmena), disminuyendo a una cantidad media de las 9:30 hr (13.7 g), 10:30 hr (12.5 g) a las 11:30 hr (9.5 g) y permaneciendo baja desde las 12:30 hasta el mediodía (menos de 2.6 g por colmena; p&lt;0.05). El patrón de distribución mostró que las abejas se presentaron en el cultivo de melón después de las 8:00 hr y alcanzaron su máximo entre las 10:30 hr y las 14:30 hr cuando las abejas iniciaron su disminución hasta el cese de los vuelos a las 20:30 hr. No se encontraron diferencias significativas en el número de abejas pecoreadoras a las diferentes distancias del apiario que fueron evaluadas

Especies de plantas visitadas por abejas pecoreadoras durante la inducción de polinización en melón.

The purpose of the research was to determine, by identifying pollen in corbicular pellets, the different plant species visited by honeybees (Apis mellifera L.) during cantaloupe (Cucumis melo L.) induced pollination. This work was carried out in La Laguna region, located in the states of Coahuila and Durango, Mexico in the spring of 2003. During the first 31 days of cantaloupe bloom, 18 honey bee colonies were placed in a six ha field, nine of which had a bottom pollen trap. Trapped pollen was collected twice per a week weighed and frozen. Through the year, anthers of wild and cultivated flowering plant species around the cantaloupe field and in La Laguna were collected, acetolyzed and preserved for pollen identified. Corbicular pollen from the 5th, 9th, 12th, 20th, 24th and 31st sample dates after start of staminate bloom was processed, identified and counted by microscopy. Pollen size was calculated with the formula: volume V=?a2b where a is the major axe and b the minor axis and multiplied by the number of pollen grains to get the total volume. Cantaloupe pollen made up 8.7 %, 9.8%, 17.6 %, 9.3 %, 28.1% and 83.5% of that collected (number of pollen grains) on respectively for the sample dates. The percentage of volume basis pollen for cantaloupe was: 51.6%, 85.0%, 66.6 %, 84.4 %, 68.9% and 95.0% respectively. It is concluded that the cantaloupe was the main species visited as a plant pollen source for pollinating honeybees and that the plants present in the sample like mesquite (Prosopis juliflora (Swartz) DC.), alfalfa (Medicago sativa L.), creosote bush (Larrea tridentata (DC) Cov.), cucumber (Cucumis sativus L.), London rocket (Sysimbrium irio L.) and sorghum (Sorghum vulgare L.) were species visited as supplementary pollen sources.El objetivo de la investigación fue determinar, a través de la identificación del polen corbicular, las diferentes especies de plantas que son visitadas por las abejas (Apis mellifera L.) durante la polinización inducida del melón (Cucumis melo L.). El trabajo se llevó a cabo en La Laguna ocalizada en los estados de Coahuila y Durango, México en la primavera del 2003. Durante los primeros 31 días de la floración del melón, un campo de seis hectáreas fue polinizada por 18 colmenas, nueve de las cuales tenía una trampa para captura de polen. El polen fue colectado dos veces por semana, pesado y congelado. Durante el año se colectaron anteras de plantas silvestres y cultivadas en floración alrededor del cultivo y en la región para preservarlas e identificar su polen usando la técnica de acetolisis. El polen corbicular, muestreado los días 5°, 9°, 12°, 20°, 24° y 31° contados a partir del inicio de la aparición de las flores estaminadas, fue procesado y contado en el microscopio óptico. El tamaño del polen fue calculado mediante la fórmula: volumen V=?a2b donde a es el eje mayor y b el eje menor y multiplicado por el número de granos de polen se obtuvo el volumen total. El polen de melón fue el 8.7 %, 9.8%, 17.6 %, 9.3 %, 28.1% y 83.5% del colectado (en base al número de granos) respectivamente en las fechas de muestreo. El porcentaje del polen de melón en base al volumen fue: 51.6%, 85.0%, 66.6 %, 84.4 %, 68.9% y 95.0% respectivamente. Se concluye que el melón fue la principal planta visitada por las abejas como fuente de polen y que las especies de plantas con mayor número de granos de polen presentes en las muestras como mezquite (Prosopis juliflora (Swartz) DC.), alfalfa (Medicago sativa L.), gobernadora (Larrea tridentata (DC) Cov.), pepino (Cucumis sativus L.), mostacilla (Sysimbrium irio L.) y sorgo (Sorghum vulgare L.) fueron especies visitadas como fuentes suplementarias de polen

Vineyard yeld estimation by VINBOT robot - preliminary results with the white variety Viosinho

Nowadays it is recognized that vineyard yield estimation can bring several benefits to all the vine and wine industry and, consequently, there is a strong demand for fast and reliable yield estimation methods. Recently a strong effort has been made on developing machine vision tools to automatically estimate vineyard yields evolving several research teams worldwide. In this paper we aim to present preliminary results obtained in the frame of an European research project (VINBOT: “Autonomous cloud-computing vineyard robot to optimise yield management and wine quality”) focus on yield estimation. A ground truth evaluation trial was set up in an experimental vineyard with the white variety Viosinho, trained on a vertical shoot positioning system and spur pruned. A sample of contiguous vines was labeled and submitted to a detailed assessment of vegetative and reproductive data to feed a viticulture data library. The vines were scanned during the ripening period of the 2015 season by the VINBOT sensor head composed with a set of sensors capable of capturing vineyard images and 3D data. Ground truth data was used to relate with images taken by the sensors and to test algorithms of image analysis. In this paper we present and discuss the relationships between actual and estimated yield computed using the surface occupied by the grape clusters in the images. Our preliminary results showed that, despite of a slight underestimation of the ground truth, caused mainly by cluster occlusion, when the canopy density allows visualization of most part of the clusters, the yield can be estimated by machine vision with a high fidelity. Further research is ongoing to test those devices and methodologies in other varieties and to improve the estimation accuracyinfo:eu-repo/semantics/publishedVersio