Abstract The Sierra de Guadalupe is the last forest redoubt north of Mexico City. In order to restore its vegetation cover, or at least manage it, it is necessary to understand its development. It is a system with unity through which energy transits in different forms depending on the vegetation, which is the most evident result of lithological, edaphological, climatic, geographical and historical conditions with different types of human intervention. The behaviour of vegetation cover in the Sierra de Guadalupe in recent decades is described by comparing the area and perimeter of the mosaics. Four landscape indices were also applied: a matrix-patch-corridor approach (Puyravaud, 2003), which expresses the change in vegetation cover based on the equation of compound interest (Mikels, 2003), the detection of fragmentation by the proximity between the centres of the mosaics of each vegetation type; the relationship of the dissection of a landscape, based on the similarity of the mosaics, with circles of the same area (Bowen and Burgess, 1981), expressed by the possibility of an organism encountering another of its species at random sites in the landscape (Jaeger, 2000). The Markov transition matrix analysis shows the ecological succession of some mosaics and also the change from forest to urban land use in most of the Sierra. Moran’s autocorrelation index allows us to assess how clustered the patches are, or, in other words, how constant the energy flow across the landscape is. To determine the mosaics, 1994 and 2019 images of the Sierra de Guadalupe were compared and the perimeter of each mosaic was drawn freehand. Field visits were made to the study area to relate the texture and position of each mosaic. The Sierra de Guadalupe was defined as a set of microwatersheds with an extension of 16 813 ha. In 1994, 8698 ha were urbanised, by 2019 concrete had covered a further 1741 ha. 540 ha of forest and plantations have been established, in addition to the 1670 ha that already existed. The oak forest has spread along the ravines over 74 ha. The most important plant community in terms of extent in 1994 was xerophytic scrub, when it represented 16.8% of the Sierra. In 2019, xerophytic scrub with grassland had an extension of 12.7% of the total. Closed or open oak woodland, the most conserved and mature growing ecosystem, covered 334 ha in 1994 and by 2019 it reached 410 ha. As for artificial forest stands, eucalyptus plantations have been the most widespread, accounting for 3.7% in 1994, but 5.2% in 2019. The Puyvaraud index (2003) revealed an increase in forest mass of 1.05% per year. Of course, the forest stand canopy does not actually increase at that rate, rather forest stands became established until they were visible on satellite imagery as established canopy. Jaeger’s (2000) cohesion index indicates zero probability (both in 1994 and 2019) of encountering two organisms of the same species hypothetically randomly arranged in the landscape. The dissection index (Bowen and Burgess, 1981) yields a value of 5.84% in 1994 and 8.42% in 2019, indicating that the landscape has become more sparse by 3.42% with respect to the similarity of a circle of the same area as all patches, i.e. it has become finer grained. The Markov matrix reveals the most representative transitions (discarding transitions to urbanisation). Grasslands became xerophytic scrubland; scrubland became heterogeneous forest and oak woodland; xerophytic scrubland became eucalyptus plantations, scrubland and grassland became stands of pirul, and scrubland and grassland became artificial copses of pine, casuarina and white cedar. A correlation of 0.5 was found for 1994 and 0.06 for 2019. In general, vegetation cover has been almost entirely affected by human causes, either with negative environmental impact, such as the construction of colonies, or positive impact, such as reforestations. Landscape indices indicate that, with the exception of eucalyptus plantations, most forest communities have become small, scattered mosaics with little core area, forming a fine-grained landscape, and the retraction of the forest frontier has promoted further fragmentation.

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Resumen: La falta de un listado completo de las licofitas y los helechos del estado de Tlaxcala motivó el presente trabajo, el objetivo fue documentar la riqueza de la pteridoflora de dicha entidad. De 2013 a 2018 se recolectaron 34 números de licofitas y helechos en el municipio de Españita; las plantas se herborizaron, identificaron y depositaron en el Herbario Jorge Espinoza Salas (JES). Los ejemplares corresponden a 8 familias, 15 géneros y 23 taxones; de estas, 2 son del género Selaginella P. Beauv. A partir de la información de las fuentes consultadas, se elaboró una lista de 58 taxones de la entidad, lo que implica que en Españita se encuentra el 39.6% de los taxones conocidos en Tlaxcala. De estos, 2 son nuevos registros: Marsilea mollis B. L. Rob. & Fernald y Polypodium guttatum Maxon. 20 taxones son de hábito terrestre; 2, son epífitas, y 1, acuático. La vegetación con mayor riqueza son los bosques, dominados en el dosel por Quercus spp. y Juniperus deppeana Steud. Pese a que la mayor proporción de la vegetación de Españita es secundaria, es posible encontrar en ella una riqueza considerable de especies susceptibles de ser conservadas.

Abstract: The non-existence of a complete list of lycophytes and ferns for the state of Tlaxcala motivated this work, whose objective is to document the richness of pteridoflora existing in Tlaxcala state. From 2013 to 2018, the collection of 34 numbers of lycophytes and ferns was carried out in the municipality of Españita, the plants were herbalized, identified and deposited in the Jorge Espinoza Salas (JES) Herbarium, the specimens corresponds to eight families, 15 genera and 23 taxa. Of these, two taxa are of the genus Selaginella P. Beauv. From the sources consulted, a list of 58 taxa was prepared for the state, which implies that 39.6% of the taxa known in the entity are found in the municipality of Españita. Of these, two are new records for the state: Marsilea mollis B.L. Rob. & Fernald and Polypodium guttatum Maxon. 20 taxa are terrestrial; two, epiphytes, and one, aquatic. The types of vegetation with more taxa are the forests of Quercus spp. and Juniperus deppeana Steud. Although the vegetation of the municipality of Españita is secondary vegetation, it is possible to find in it a considerable richness of species capable of being conserved.

Abstract Urban trees are a fundamental part of the natural landscape within cities, as they reduce the negative effects caused by economic activities and contribute to improve the quality of life for the inhabitants of all social classes. The aim of this study was to make a diagnosis of the urban trees in streets of Puebla City in areas with different degrees of marginalization and type of existing roads. A stratified random sampling was carried out in public roads from May to October 2019. The species, total height, height to the first branch and height to canopy, basal diameter, diameter to the breast height, canopy cover diameter, also health condition, status of development and conflicts with infrastructure were determined. A total of 2 188 trees were recorded, 2 068 of which were found alive, which belong to 31 families, 56 genera and 75 species; 73.33 % are introduced species and only 26.67 % are native. The results from this study highlight the influence that socio-economic aspects have on the composition and structure of urban trees, mainly in street trees, being important to recognize that in the development of management plans and management of public urban trees it is necessary to integrate the different social and urban aspects that each urban center has.

Resumen El arbolado urbano forma parte fundamental del paisaje natural dentro de las ciudades, reduce los efectos negativos ocasionados por las actividades económicas y contribuye a mejorar la calidad de vida de los habitantes de todas las clases sociales. El objetivo del presente estudio fue realizar la caracterización de la estructura y la diversidad del arbolado en calles públicas de la ciudad de Puebla por áreas con diferente grado de marginación y orden vial. Se realizó un muestreo aleatorio estratificado en vialidades públicas de mayo a octubre de 2019; se determinó la especie, altura total, altura del fuste limpio, altura de copa viva y altura a copa viva, diámetro basal, diámetro normal, diámetro de la copa, así como condición y estado de desarrollo. Se registró un total de 2 188 árboles, de los cuales 2 068 estaban vivos; estos se agruparon en 31 familias, 56 géneros y 75 especies; 73.33 % son taxones introducidos y solo 26.67 % son nativos. Los resultados del estudio destacan la influencia de los aspectos socioeconómicos y urbanos en la composición y en la estructura del arbolado vial, por lo que deben de ser contemplados en la gestión y elaboración de planes de manejo.

Abstract Purpose: To analyze and compare the anatomy and composition of the seed coat from E. cyclocarpum seeds from two different origins and harvest years, and from 12 other legume species, through images obtained from a scanning electron microscope (SEM) as well as to perform a germination test and a proximal analysis of the first species. Methodological design: Samples of the E. cyclocarpum seed coat from two different provenances and years of harvest (1983 and 2019) were observed in an electronic microscope along with 12 other legume species. Scarification treatments for a germination test and a proximal analysis were conducted for E. cyclocarpum seeds collected in 2019. Results: The number of cell layers present in all of the species ranges from four to eight. The statistical analysis of germination was significant (p <0.0001) among the treatments; the one with the highest germination was sanding. The presence of a high percentage of lignin (L), neutral detergent fiber (NDF), acid detergent fiber (FDA), and nitrogen-free extract (ELN) in the seed coat was found. Research limitations: To obtain a seed coat sample, it is necessary to consider the location on the seed from which it is taken since the thickness of the seed coat can vary. Findings: The cell layers present in the seed coat are cuticle, macrosclereids, osteosclereids, and parenchyma (spongy, palisade, compact); It was observed that E. cyclocarpum has seven and eight layers while in the rest of the species four to eight. The presence of cell layers and lignin in the seed coat of E. cyclocarpum determines its physical dormancy.

Resumen Objetivo: analizar y comparar la anatomía y composición de la cubierta seminal en semillas de E. cyclocarpum de dos procedencias y años de recolección distintos, y de otras 12 especies de leguminosas, mediante el uso de imágenes obtenidas en un microscopio electrónico de barrido (MEB); así como realizar una prueba de germinación y un análisis proximal de la primera especie. Diseño metodológico: se observaron en un MEB muestras de cubierta seminal de E. cyclocarpum de dos procedencias y años de recolección distintos (1983 y 2019). También fueron observadas 12 especies de leguminosas. En semillas de E. cyclocarpum recolectada en 2019 se emplearon tratamientos de escarificación para realizar un estudio de germinación y también se hizo un análisis proximal. Resultados: el número de capas celulares presentes en todas las especies va de cuatro a ocho. El análisis estadístico de germinación fue significativo (p<0.0001), entre los tratamientos, el de mayor germinación fue el lijado. Se halló un alto porcentaje de lignina (L), fibra detergente neutra (FDN), fibra detergente ácida (FDA) y extracto libre de nitrógeno (ELN) en la cubierta seminal. Limitaciones de la investigación: para la obtención de la muestra de cubierta seminal es necesario considerar la parte de la semilla de donde se toma, ya que el grosor de esta puede variar. Hallazgos: las capas celulares presentes en la cubierta seminal son cutícula, macroesclereidas, osteoesclereidas, parénquima (esponjoso, en empalizada, compacto). E. cyclocarpum tiene siete y ocho capas, en el resto de las especies se observaron de cuatro a ocho capas. La presencia de capas celulares y lignina en la cubierta seminal (base seca) de E. cyclocarpum determina su latencia física.

Abstract The objective was to identify an optimal cutting height at harvest of sorghum forage (Sorghum bicolor L.) to improve the nutritional quality of silage, without reducing the dry matter (DM) yield of the forage. The effect of cutting height at 10, 20, 30, 40, 50 and 60 cm on DM yield and nutritional value of silage was evaluated. The forage was harvested when the grain reached a milky-dough state. The plants were crushed to a particle size of 2 cm and the forage was compacted to 261 kg of MS/m3 in mini silos. The DM yield reduced from harvesting at 40 cm above the ground. The neutral detergent fiber (NDF) and lignin of silage were superior when harvested at 10 cm, but lignin reduced by 1.4 % when the cut was greater than 20 cm. The NDF digestibility and total digestible nutrient (TDN) concentration increased when harvested at 40 cm. The highest content of non-fibrous carbohydrates (NFC) was obtained when harvested at 40 and 50 cm. The net lactation energy (NLE) of silage increased from harvesting at 20 cm. The optimal pH of silage was obtained when harvested at 30 cm. In conclusion, harvesting the sorghum fodder between 20 and 40 cm allows obtaining a silage with lower lignin content and, therefore, greater digestibility and energy concentration without negatively affecting the DM yield of the forage.

Resumen El objetivo fue identificar una altura de corte óptima a la cosecha del forraje de sorgo (Sorghum bicolor L.) para mejorar la calidad nutritiva del ensilaje, sin reducir el rendimiento de materia seca (MS) del forraje. Se evaluó el efecto de la altura de corte a 10, 20, 30, 40, 50 y 60 cm, sobre el rendimiento de MS y el valor nutritivo del ensilaje. El forraje se cosechó cuando el grano alcanzó un estado lechoso-masoso. Las plantas se trituraron a un tamaño de partícula de 2 cm y el forraje se compactó a 261 kg de MS/m3 en mini-silos. El rendimiento de MS se redujo a partir de cosechar a 40 cm sobre el suelo. La fibra detergente neutro (FDN) y lignina del ensilaje fueron superiores cuando se cosechó a 10 cm, pero la lignina se redujo 1.4 % cuando el corte fue mayor a 20 cm. La digestibilidad de la FDN y la concentración de nutrientes digestibles totales (NDT) aumentaron cuando se cosechó a 40 cm. El mayor contenido de carbohidratos no fibrosos (CNF) se obtuvo cuando se cosechó a 40 y 50 cm. La energía neta de lactancia (ENL) del ensilaje aumentó a partir de cosechar a 20 cm. El pH óptimo del ensilaje se obtuvo cuando se cosechó a 30 cm. En conclusión, cosechar el forraje de sorgo entre 20 y 40 cm permite obtener un ensilaje con menor contenido de lignina y, por consiguiente, mayor digestibilidad y concentración energética sin afectar negativamente el rendimiento de MS del forraje.

Abstract Introduction: Mental health damages represents one of the most relevan problems among general population and specifically among University students. Medical training involves particular exigencies that increases probabilities of having higher prevalence at experiencing mental health disorders among the medicine students. Objective: To compare the anxiety, depression and suicidal behavior among medicine and other bachelor degrees students at a University in Mexico. Method: It was designed a transversal study where it was applied a survey to a probabilistic fortuitous sample among first and last grade studentes of bachelor’s degree in medicine. This survey was also applied to a fortuitous sample of the same proportion to firste and last grade of different bachelor’s degree. Data obtained were processed in a bivariate analysis to calculate prevalence as well as association measures (OR) and statistical significance (X2). Results: The medicine students showed higher prevalence of anxiety, depression and suicidal behavior episodes, tan the students of different bachellor’s degree programs. It was also found that the last grade medicine students showed higher prevalences that the ones in first grade. Sex was a variable that presentes more influence among students of the other medicine bachelor’s degree programs. Conclusions: Medical training implies higher probabilities of depression, anxiety and suicidal behavior, mostly among last year students, than students of other academic program.

Resumen Introducción: Los daños a la salud mental representan uno de los problemas más relevantes en la población general y específicamente entre universitarios. La formación médica implica exigencias particulares que pueden hacer de sus estudiantes una población con mayor presencia de ciertos trastornos mentales. Objetivo: Comparar las prevalencias de ansiedad, depresión, conducta suicida entre alumnos de medicina y de otras carreras en una universidad en México. Método: Se diseñó un estudio transversal en el que se aplicó una encuesta a una muestra probabilística de estudiantes del primer y último grado de la licenciatura en medicina y a una muestra aleatoria de igual tamaño y mismas proporciones de estudiantes del primer y último grado de cualquier otra carrera. Los datos fueron procesados en un análisis bivariado para calcular prevalencias, medidas de asociación (OR) y significancia estadística (X2). Resultados: Los estudiantes de medicina mostraron prevalencias más altas de ansiedad, depresión y conducta suicida que los de otras carreras, los del último grado presentaron prevalencias más altas que los del primero. El sexo fue una variable que influyó más entre los estudiantes de otras carreras pero menos en la de medicina. Conclusiones: La formación médica implicaron mayores probabilidades de depresión, ansiedad y conducta suicida que otras profesiones, éstas son más altas en el último grado de los estudios.

Abstract Plant community management can use multivariate methods to find response patterns and generate hypotheses about possible relationships in species composition with respect to environmental gradients. The objective was to record patterns of distribution and uses of vegetation in the municipality of Catorce, San Luis Potosi. In 2019, six transects were shown, from the foot of the undergrowth to the west of the Sierra de Catorce, an endorheic drainage valley or plain and a low mountain range folded with a hill. Floristic composition, vertical and horizontal structure, and soil characteristics were analyzed at each site. Desert thickets of rosetophile, microphile and thorny forest were found. The indirect environmental factors that best explain the distribution are the porosity of the soil, pH, K, Ca, Fe and altitude, factors that influence the availability of water. The main use of plants is traditional medicinal.

Resumen La ordenación de comunidades vegetales puede usar métodos multivariados para hallar patrones de respuesta y generar hipótesis sobre las posibles relaciones existentes en la composición de especies con respecto a gradientes ambientales. El objetivo fue registrar patrones de distribución y usos de la vegetación en el municipio de Catorce, San Luis Potosí. En 2019, se muestrearon seis transectos, desde pie de monte bajo al oeste de la Sierra de Catorce, valle o planicie de drenaje endorreico y sierra baja plegada con lomerío. En cada sitio se analizó la composición florística, la estructura vertical y horizontal y las características del suelo. Se hallaron matorrales desérticos rosetófilo, micrófilo y bosque espinoso. Los factores ambientales indirectos que mejor explican la distribución son la porosidad del suelo, pH, K, Ca, Fe y altitud, factores que influyen en la disponibilidad de agua. El principal uso de las plantas es medicinal tradicional.

Abstract: Commonly, the improper signaling in road construction zones is the cause of different accidents to drivers, pedestrians, and road construction workers. The signaling used when a vehicle is approaching a repairing section could be classified into two classes: stationary or active. Nevertheless, active warning systems have demonstrated to reduce accidents in road work zones. Within the active signaling class we have: portable changeable message sign, flashing arrow signs, flagman, to mention some. This paper describes the implementation of two robotic flagmen controlled by the Controller Area Network (CAN) protocol. Each robotic flagman can perform four different actions: speed reduction (right and left) and lane change (right and left). The electronic circuitry and mechanical motors of the two robotic flagmen have the option to be powered by a solar charging system considering working zones where there is no access to the electric grid. The solar charging system guarantees a sufficient electrical power supply for night conditions operations. Also, the CAN protocol can be used to monitor the correct operability of the robotic flagmen thus eliminating the need to incorporate more expensive electronic devices such as cameras. The hardware combination in the control, monitoring, and solar charging system allow us to propose a low-cost practical implementation. The results of our implementation show that the longest response time of the robot is less than 850 ms once that the CAN message has been sent to the network. This demonstrates that our proposal can meet real-time implementation requirements.

Abstract: Hydrocephaly is one of the most common nosological subjects in neurosurgery, its treatment abides a shunt of cerebrospinal fluid, most of the time to a peritoneal cavity. One of the most frequent complications in this type of surgery occurs at the distal catheter level, with the obstruction of it and the bowel perforation and movement of it. We report three cases of a large intestine perforation and catheter migration to the rectum. The patients were successfully treated by an exterior deviation, preventive treatment of a possible infection and placing the distal catheter again to the atrium. From an abdominal point of view an explorative laparotomy were performed, a colostomy in two cases and a primary suture on the last one. All the patients unfold satisfactorily. Conclusions: This complication is rare. It must be treated urgently and with the right treatment it has a good prognosis.

Resumen: La hidrocefalia es una de las entidades nosológicas más comunes en neurocirugía, su tratamiento consiste en derivación del líquido cefalorraquídeo, generalmente hacia la cavidad peritoneal. Una de las complicaciones más frecuentes de este tipo de cirugías se presenta a nivel del catéter distal como la obstrucción de éste y la perforación de vísceras y migración del mismo. Reportamos tres casos de perforación del intestino grueso y migración del catéter hacia el recto. Los pacientes fueron tratados en forma exitosa mediante derivación al exterior, tratamiento de la posible infección y recolocación del catéter distal a la aurícula. Desde el punto de vista abdominal se realizó laparotomía exploradora, colostomía en dos casos y cierre primario en el otro, todos los pacientes evolucionaron en forma satisfactoria. Conclusiones: Esta complicación es poco frecuente. Debe tratarse en forma urgente y cuando se procede adecuadamente, el pronóstico es bueno.

Abstract Introduction chronicle difficulties in sleeping, as well as its privation are associated with disorders such as depression and anxiety; these pathologies have been observed by different researches on undergraduate medical internship students, whose bad sleepers percentage oscillates between 60 and 90%. Objective To evaluate changes in sleep quality, diurnal somnolence, anxiety and depression among students, both at the start and at the end of an undergraduate medical internship in a public university. Methods It was carried out an observational, prospective and longitudinal study, throughout variable measurement in a cohort both at the start and at the end of an undergraduate medical internship. From the total amount of undergraduate physicians of 2016 July generation (N=51), it was selected a fortuitous sample (n=45) where these instruments were applied: Pittsburgh sleep quality index, Epworth somnolence scale, Beck inventories for anxiety and depression, McNemar statistical tests for sleep quality, as well as Wilcoxon for diurnal somnolence, anxiety and depression. The information obtained was processed by SPSS software, version 22, with a significance level of 0.05. Results At the end of the medical internship the bad sleep quality, diurnal somnolence and anxiety level increased, presenting statistically significant differences. Depression degrees were negatively affected without apparent significance. Conclusions Both anxiety and depression showed an important increase of their prevalence by the end of the medical internship. Due to these situations, we recommend to implement periodically evaluations, prevention strategies and to assess the influence of several stressors.

Resumen Introducción Las dificultades crónicas de sueño, así como la privación de éste se asocian con trastornos como la depresión y la ansiedad, estas patologías han sido observadas por diferentes investigaciones en estudiantes del internado de medicina, en quienes el porcentaje de malos dormidores oscila entre 60% a 90%. Objetivo Evaluar los cambios en la calidad de sueño, somnolencia diurna, ansiedad y depresión al inicio y al final del internado médico en estudiantes de una Universidad pública. Método Se realizó un estudio observacional, prospectivo y longitudinal por medio de medición de variables en una cohorte al inicio y al final del internado. Del total de los médicos internos de pregrado de la generación julio 2016 (N= 51), se seleccionó una muestra aleatoria (n=45) en la que se aplicaron los instrumentos: índice de calidad de sueño Pittsburgh, escala de somnolencia Epworth, e Inventarios de Beck para Ansiedad y Depresión. Se realizó estadística descriptiva con medidas de tendencia central y de dispersión, así como las pruebas estadísticas McNemar para calidad de sueño y Wilcoxon para somnolencia diurna, ansiedad y depresión. La información se procesó con el programa SPSS versión 22 con Nivel de significancia de 0.05. Resultados Al final del internado médico se incrementó la mala calidad de sueño, la somnolencia diurna y los niveles de ansiedad presentando diferencias estadísticamente significativas. Se vieron afectados los grados de depresión en forma negativa sin mostrar significancia. Conclusiones Tanto la ansiedad como la depresión mostraron una elevación importante de sus prevalencias al final del internado médico, por lo que se recomienda realizar evaluaciones periódicas medidas de prevención y valorar la influencia de diversos estresores.

Abstract Background: Knowledge of growth is relevant because it provides information on the local dynamics of the population. Goals: This study evaluated the growth, size structure, morphometry, and sex ratio of C. bellicosus crab caught in the El Colorado lagoon, Ahome, Sinaloa, Mexico. Methods: Through size distributions and by the modal-progression method using the FISAT II program. Similarly, the growth parameters of the von Bertalanffy stationalized equation and the growth performance or Munro index (Ø) were determined from March 2012 to March 2013. Results: 3,242 organisms of C. bellicosus were captured of which 1,770 were males and 1,472 were females. The population of C. bellicosus in the lagoon ranged in size from 40 mm to 190 mm (CW), showing two similar modes for males and females (100 mm and 110 mm, respectively). The relationships between CL-CW for both sexes were adjusted to a linear type model (males, CL = 0.5265CW-0.0539, R2 = 0.8058, p <0.05, females, CL = 0.581CW-0.6335, R2 = 0.7643, p <0.05). The CW-TW relationship was of potential type (males, TW = 0.561AC3.0751, R2 = 0.7968, p <0.05; females, TW = 0.0834C2.9077, R2 = 0.7589, p <0.05). In females, K = 0.90 years-1 and L∞ = 169 mm, K = 1.20 years-1 and L∞ = 178.5 mm. Conclusions: The growth curves suggest that C. bellicosus reaches its maximum length at 2.5 to 3 years. The sex ratio of 0.81 F : 1 M was significant (X2 (0.05, 11) = 19.675, X2 observada = 58.481, p < 0.05).

Resumen Antecedentes: El conocimiento del crecimiento en cualquier especie es relevante debido a que proporciona información de la dinámica local de la población. Objetivos: Evaluar el crecimiento, la estructura de tallas, la morfometría y la proporción de sexos de las jaibas C. bellicosus capturadas en la laguna El Colorado, Ahome, Sinaloa, México. Métodos: Durante el periodo de marzo de 2012 a marzo de 2013 se evaluaron las distribuciones de frecuencias de tallas y se aplicó el método de progresión modal mediante el programa FiSAT II. Asimismo, se determinaron los parámetros de crecimiento de la ecuación de von Bertalanffy y el desempeño del crecimiento o índice de Munro (Ø). Resultados: Se capturaron 3,242 organismos de C. bellicosus, de los cuales 1,770 fueron machos y 1,472, hembras. La población de C. bellicosus en la laguna presentó un intervalo de tallas de 40 mm a 190 mm (AC), mostrando dos modas similares para machos y hembras (100 mm y 110 mm, respectivamente). Las relaciones entre el LC-AC para ambos sexos se ajustaron a un modelo de tipo lineal (machos, LC = 0.5265AC-0.0539, R2= 0.8058, p <0.05; hembras, LC = 0.581AC-0.6335, R2 = 0.7643, p <0.05). La relación AC-PT fue de tipo potencial (machos, PT = 0.561AC3.0751, R2 = 0.7968, p <0.05; hembras, PT = 0.0834AC2.9077, R2 = 0.7589, p <0.05). En hembras se estimó una K= 0.90 años-1 y L∞ = 169 mm, en los machos fue K = 1.20 años-1 y L∞ = 178.5 mm. Conclusiones: Las curvas de crecimiento sugirieron que C. bellicosus alcanzó su longitud máxima de 2.5 a 3 años. La proporción de sexos de 0.81 H : 1 M fue significativa (X2 (0.05, 11) = 19.675, X2 observada = 58.481, p < 0.05)

ABSTRACT: The size structure of Callinectes arcuatus was determined from 2,786 ind (1,956 males and 830 females) of C. arcuatus, which were collected from March 2012 to March 2013 in El Colorado Lagoon, Sinaloa, Mexico. Sampling was random in grid form considering five stations located within the study area. Measurements of length (CL), the width of the carapace (CW) and total weight (TW) were registered. The average carapace width of C. arcuatus was 9.4 ± 0.03 cm with a minimum of 5.3 cm and a maximum of 19.5 cm. For the length of the carapace (CL) the mean was 4.8 ± 0.02 cm with a minimum of 2.8 cm and a maximum of 9.2 cm, while the total weight varied between 16 and 416 g with an average of 54.0 ± 0.71 g, in both sexes (juveniles and adults).The morphometric relationships between CL-CW were adjusted a linear model. The equation is describing the relation TW-CW, which was adjusted to a potential model with a coefficient of determination of R2 = 0.71. The growth parameters estimated using the model of von Bertalanffy, for males was K = 0.84 yr-1 y CW∞ = 14.0 cm while for females K = 0.55 yr-1 and CW∞ = 15. 6 cm. According to the results obtained, it is observed that the organisms with sizes and maximum weights were presented in juvenile and adult males in C. arcuatus, being slightly larger and heavier than females in similar sizes and according to the growth curves the organisms, this species reaching is the maximum length between 3-4 years old.

ABSTRACT The World Health Organization and the American Psychological Association consider transsexuality a pathology and suggest sex-gender reassignment for the biopsychic adjustment of trans people. Through the discursive analysis of experience, this study describes the processes of medicalization and gender performativity in relation to the health of a group of trans women from Mexico City. For this purpose, a qualitative study was conducted in which 10 semi-structured interviews were carried out in 2015. As part of medicalization, the pathologization of transsexuality generated psychic suffering; on the other hand, sex-gender reassignment also entailed additional risks. It is possible to conclude that in trans women, violence and exclusion constitute the primary experiences explaining their foremost health problems. Therefore, it is suggested that it is necessary for discrimination be reduced and for advancements to be made in safer medical interventions.

RESUMEN La Organización Mundial para la Salud y la American Psychological Association consideran que la transexualidad es una patología y plantean la adecuación sexogenérica para el ajuste biopsíquico de las personas trans. Mediante el análisis discursivo de la experiencia, en este estudio se describen los procesos de medicalización y performatividad del género en su relación con la salud de un grupo de mujeres trans de la Ciudad de México, para lo cual se desarrolló un estudio cualitativo en el que se realizaron, en el año 2015, diez entrevistas semiestructuradas. Como parte de la medicalización, la patologización de la transexualidad generó sufrimiento psíquico; por su parte, la adecuación sexogenérica también implicó riesgos adicionales. Se puede concluir que, en las mujeres trans, la violencia y la exclusión resultan las principales experiencias que explican los problemas de salud más relevantes por lo que se sugiere disminuir la discriminación, así como avanzar en intervenciones médicas más seguras.

ABSTRACT The World Health Organization and the American Psychological Association consider transsexuality a pathology and suggest sex-gender reassignment for the biopsychic adjustment of trans people. Through the discursive analysis of experience, this study describes the processes of medicalization and gender performativity in relation to the health of a group of trans women from Mexico City. For this purpose, a qualitative study was conducted in which 10 semi-structured interviews were carried out in 2015. As part of medicalization, the pathologization of transsexuality generated psychic suffering; on the other hand, sex-gender reassignment also entailed additional risks. It is possible to conclude that in trans women, violence and exclusion constitute the primary experiences explaining their foremost health problems. Therefore, it is suggested that it is necessary for discrimination be reduced and for advancements to be made in safer medical interventions.

RESUMEN La Organización Mundial para la Salud y la American Psychological Association consideran que la transexualidad es una patología y plantean la adecuación sexogenérica para el ajuste biopsíquico de las personas trans. Mediante el análisis discursivo de la experiencia, en este estudio se describen los procesos de medicalización y performatividad del género en su relación con la salud de un grupo de mujeres trans de la Ciudad de México, para lo cual se desarrolló un estudio cualitativo en el que se realizaron, en el año 2015, diez entrevistas semiestructuradas. Como parte de la medicalización, la patologización de la transexualidad generó sufrimiento psíquico; por su parte, la adecuación sexogenérica también implicó riesgos adicionales. Se puede concluir que, en las mujeres trans, la violencia y la exclusión resultan las principales experiencias que explican los problemas de salud más relevantes por lo que se sugiere disminuir la discriminación, así como avanzar en intervenciones médicas más seguras.

ResumenLas escifomedusas se alimentan principalmente de crustáceos microscópicos, huevos y larvas de peces, moluscos y de otras medusas. La distribución y abundancia de la escifomedusa tiene una importancia económica y ecológica ya que son depredadores que influyen en la dinámica poblacional de otras pesquerías. El presente trabajo se realizó de septiembre 2013 hasta agosto 2014 en el sistema lagunar Arrastradero-Redonda, Tabasco, con el objetivo de aportar información sobre la distribución y abundancia espacial y temporal de la escifomedusa Stomolophus meleagris y su relación con los parámetros ambientales. Para su realización se efectuaron recorridos mensuales durante un ciclo anual y se recolectaron muestras biológicas; realizándose tres arrastres en cada una de las estaciones, en una área de 1 km2, con una duración de 5 a 10 min con un chinchorro playero de monofilamento de 20 m de longitud por 3 m de altura y luz de malla de 1.5 cm, con esos datos se realizó el análisis de eficiencia pesquera, (CPUE con Org./Unidad de superficie evaluada) y se determinó la relación con los parámetros ambientales. Se estableció que la mayor abundancia se presentó de la estación 1 a la 3 con 7 a 19 Org/km2 en los meses de abril hasta agosto 2014 y su menor abundancia se observó en las estaciones 6 a 10 con un promedio de 1 Org./km2 desde octubre 2013 a marzo 2014. El análisis de correlación múltiple por pasos indicó que existe una fuerte asociación entre la CPUE y algunas variables ambientales estudiadas, observándose el 70.9 % de la variabilidad de los datos. La salinidad fue la variable más influyente explicando el 64.3 % de la variabilidad, seguida por la temperatura con un 3.6 % mientras el oxígeno disuelto explica solo el 2.9 % de variabilidad, principalmente debido a que en la zona confluyen una serie de factores geológicos, oceanográficos y biológicos favorables para la proliferación de esta especie debido al aporte de agua marina de la barra de Tupilco. Sin embargo falta realizar mayores investigaciones que permita cuantificar este recurso y establecer zonas de explotación comercial y realizar estudios sobre el aspecto biológico, principalmente hábitos reproductivos y alimenticios; que aporten información necesaria para diseñar planes adecuados sobre su posible uso de manera adecuada. Así mismo con los datos obtenidos en el presente trabajo podamos determinar el potencial pesquero de este recurso en el estado de Tabasco.

Abstract:The scyphomedusae feed mainly on microscopic crustaceans, eggs and fish larvae, molluscs and some other jellyfishes. The distribution and abundance of the scyphomedusae has an economic and ecological impact as they are predators that have an influence on the population dynamics of other fisheries. This investigation took place in the lagoon system ‘ArrastraderoRedonda’, Tabasco, from September 2013 to August 2014, with the purpose to provide information on the distribution, and spatial and temporal abundance of Stomolophus meleagris; along with its relation to environmental parameters. A total of 10 stations were defined and biological samples were taken on a monthly basis during this annual cycle. For this purpose, three pulls with a beach seine monofilament (20 m long by 3 m height, mesh opening 1.5 cm, 5 to 10 minutes) per station were made within a 1 km2 area. Information obtained was used to calculate the fishing efficiency analysis (CPUE con org./Evaluated Area Unit) and to determine the relationship with the environmental parameters. Our results showed that the abundance in the stations 1 to 3 was from 7 to 19 org./km2 from April to August 2014; less organisms were observed in stations 6 to 10 (an average of 1 org./ km2) from October 2013 to March 2014. The multiple correlation steps analysis indicated that there is a strong association between the CPUE and some environmental investigated variables, and a 70.9 % variability of the data was observed. The salinity resulted the most important variable because it determined a 64.3 % of variation; it was followed by the temperature with a 3.6 %; meanwhile, dissolved oxygen explained only the 2.9 %, this was mainly because within the area there are several geological, oceanographic and biological factors that favor the distribution of this species due to seawater contribution through the Tupilco bar. With the provided data with this investigation we were able to determine the fishery potential of this resource for Tabasco state. However, additional research is required to allow an extended quantification of this resource, to determine the commercial exploitation areas, and drive studies about reproductive and feeding habits, that may provide the necessary information to establish plans for sustainable use. Rev. Biol. Trop. 65 (1): 167-179. Epub 2017 March 01.