A Study on the Growth Rate of Brown Shrimp (Penaeus aztecus aztecus Ives, 1891) from the Coasts of Veracruz and Tamaulipas, Mexico

The present study was undertaken with the purpose of getting the proper basis for exploiting brown shrimp resources in a rational manner, by introducing control regulations of fishing activities. The growth rate models are necessary for the other parameters of population dynamics of the stocks of this species, whose annual catch, Osborn, Maghan and Drummond (1969), averages 54 million pounds of tail weight, representing 52% of the total shrimp caught in the Gulf of Mexico. This shows that Penaeus aztecus aztecus is the most important of shrimp species exploited in this region. Nevertheless, the brown shrimp is the least well known of the three most common species. The growth rate was determined by fitting the von Bertalanffy growth curve to offshore populations, on which according to Cook and Lindner (1970), there are no published data, although an unsuccessful attempt was made by Klima (1964). Published data are only from inshore waters (Williams 1955, Loesch 1965, Joyce and St. Amant et al., from Cook and Lindner 1970). Statistical calculations of length-weight and total length-tail length ratios were required before available raw data could be used in growth analyses. Tesch (1968), points out that age data, along with length and weight measurements represent the basis for information on growth, composition of stocks, maturity age, life span, mortality and production

Fish and Fisheries of the Eastern Coast of Mexico, with Emphasis on Coral Reef Species

The state on knowledge of fish communities associated with coral reefs of the southern Gulf of Mexico (Veracruz, Campeche bank), and eastern Yucatan on the Caribbean is reviewed, in addition to a description of the main fisheries of the area. The review includes coral reef fish of Veracruz, the Campeche Bank, and reefs running along the Caribbean coast up to the border with Belize. Data recorded suggest that the heterogeneity of different levels (region, reef and reef zone) may be responsible for a larger number of niches available, promoting higher specific diversity that is more evident in the Caribbean reefs. The environmental conditions create patterns of differential abundance among the three zones. The main regional fisheries include more than 60 species and the current yield suggests a 30% reduction compared to catch volumes recorded a few years ago. The changes in coral coverage and the fishing pressure over coral reefs have exerted effects on species of fishing importance

Spontaneous Symmetry Breakdown in non-relativistic Quantum Mechanics

The advantages and disadvantages of some pedagogical non-relativistic quantum-mechanical models, used to illustrate spontaneous symmetry breakdown, are discussed. A simple quantum-mechanical toy model (a spinor on the line, subject to a magnetostatic interaction) is presented, that exhibits the spontaneous breakdown of an internal symmetry.Comment: 19 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1111.1213. Equations (30) and (31) have been corrected. Other minor correction

Relationship between the isometric force of the dominant hand and the Body Mass Index of university students

INTRODUCTION: Strength is the neuromuscular capacity to overcome or counter resistances through muscular activity and is closely linked to all the motor actions that the human being develops, and to his body mass index. OBJECTIVE: To determine the level of correlation between body mass index (BMI) and the isometric strength of the dominant hand of university students. METHOD: The strength was evaluated with a TAKEI SCIENTIFIC INSTRUMENT 5401 dynamometer to 70 university students using a random sampling method using a descriptive transactional design. We obtained data that were processed with a bivariate correlation obtaining the Pearson coefficient. We used SPSS ver. 15. RESULTS: The studied age was 23 ± 1.9 years, with a length of 165.6 cm. ± 7.72 for women and 173.7 cm. ± 7.95 men, as well as a weight in women of 64.1 ± 14.82 kg and men 82.3 ± 14.72 kg, which results in a BMI for women of 25.01 ± 4.405 m2/kg and 25.06 with ± 4.398 m2/kg for men. On the other hand, the female isometry strength was 3.08. ± 0.613 Kg and for men was 3.68 ± 0.839 Kg. In females, there was not correlation between the BMI and isometric strength (Sig = .192). Contrary, in males, there was a significant and negative correlation grade between the BMI and isometric strength (r = -0,452; Sig. = 0.035). CONCLUSIONS: In this study, it was observed that as BMI increases, strength does not grow. Therefore, other variables should be evaluated to understand what is related to the overweight or obesity of students

Patogenicidad de especies de Fusarium asociadas a la pudrición basal del ajo en el centro norte de México

ResumenEl ajo en México es uno de los cultivos de hortalizas más rentables, más del 83% de esta superficie es aportada por los estados de Zacatecas, Guanajuato, Sonora, Puebla, Baja California y Aguascalientes.La pudrición basal ocasionada por Fusarium spp. se encuentra ampliamente distribuida a nivel mundial; esta enfermedad se ha convertido en una limitante en zonas productoras de cebolla y ajo, no solo en México, sino también en otros países, En México, se ha informado la presencia de Fusarium oxysporum en plantas en Guanajuato y en semillas de ajo en Aguascalientes. En el estado de Morelos se ha reportado la presencia de Fusarium culmorum en cultivares de cebolla. Asimismo, en Aguascalientes se tienen antecedentes de otras especies como Fusarium proliferatum, Fusarium verticillioides, Fusarium solani y Fusarium acuminatum. Para este trabajo se planteó como objetivo identificar las especies de Fusarium encontradas en los estados de Zacatecas, Guanajuato y Aguascalientes, y evaluar su patogenicidad. Se realizaron recolectas de plantas con síntomas de la enfermedad en los estados antes mencionados. De los muestreos realizados se identificaron las especies F. oxysporum, F. proliferatum, F. verticillioides, F. solani y F. acuminatum; las cepas de Aguascalientes identificadas como AGS1A (F. oxysporum), AGS1B (F. oxysporum) y AGSY-10 (F. acuminatum) fueron las que presentaron bajo condiciones de invernadero un mayor índice de severidad.AbstractGarlic in Mexico is one of the most profitable vegetable crops, grown in almost 5,451ha; out of which more than 83% are located in Zacatecas, Guanajuato, Sonora, Puebla, Baja California and Aguascalientes.Blossom-end rot caused by Fusarium spp is widely distributed worldwide and has been a limiting factor in onion and garlic production regions, not only in Mexico but also in other countries. The presence of Fusarium oxysporum has been reported in Guanajuato and Aguascalientes. Fusarium culmorum has been reported in onion cultivars of Morelos; and Fusarium proliferatum, Fusarium verticillioides, Fusarium solani and Fusarium acuminatum have been previously reported in Aguascalientes. The goal of this work was identifying the Fusarium species found in Zacatecas, Guanajuato and Aguascalientes, to assess their pathogenicity. Plants with disease symptoms were collected from hereinabove mentioned States. The samples resulted in the identification of: F. oxysporum, F. proliferatum, F. verticillioides, F. solani and F. acuminatum species; out of which Aguascalientes AGS1A (F. oxysporum), AGS1B (F. oxysporum) and AGSY-10 (F. acuminatum) strains showed higher severity under greenhouse conditions

Utjecaj trajanja in vitro sazrijevanja i inkubacije s aktivirajućim čimbenikom na kapacitet izlijeganja goveđih partenota - kratko priopćenje

The period of both in vitro maturation (IVM) and incubation with oocyte activators affects the blastocyst yield following parthenogenetic activation (PA). Nevertheless, it is still unknown how these conditions impact the expansion and hatching rates of bovine parthenogenetic blastocysts. The objective of this study was to assess the influence of the duration of IVM and exposure to the activating agent, 6-dimethylaminopurine (6-DMAP), on a number of developmental parameters in bovine parthenotes, including: Cleavage, blastocyst formation, expansion, and hatching. Slaughterhouse oocytes were subjected to different periods of IVM. Subsequently, eggs were first parthenogenetically activated for five minutes with ionomycin and then incubated for distinct lengths of time with a second activator, 6-DMAP. The treatments were: a) Control: 22 h IVM/4 h 6-DMAP; b) 22 h IVM/5 h 6-DMAP; c) 24 h IVM/4 h 6-DMAP; and d) 24 h IVM/5 h 6-DMAP. Developmental stages were evaluated at day 4 and day 8 of in vitro culture (IVC). No differences were detected in most developmental parameters. However, the duration of IVM and incubation with 6-DMAP significantly affected (P<0.05) hatching capacity considering the number of blastocysts (Hatch./Blast.). Also, this same variable was higher (P<0.05) in group b) 22 h IVM/5 h 6-DMAP (45.89 ± 12.59%), as compared to c) 24 h IVM/4 h 6-DMAP (6.67 ± 6.67%). In conclusion, the length of IVM and incubation with 6-DMAP influenced parthenogenetic development, where 22 h IVM/5 h 6-DMAP was the condition producing the highest Hatch./Blast. rate in bovine parthenotes.Vrijeme in vitro sazrijevanja (IVM) i vrijeme inkubacije s aktivatorima oocista utječu na stvaranje blastocista nakon partenogenetske aktivacije (PA). Ipak, još uvijek se ne zna kako navedeno utječe na ekspanziju i stopu izlijeganja goveđih partenogenetskih blastocista. Cilj rada bio je istražiti utjecaj trajanja IVM i izloženosti aktivirajućem čimbeniku 6-dimethylaminopurinu (6-DMAP) na više razvojnih parametara u goveđih partenota, uključujući diobu, formiranje blastociste, ekspanziju i izlijeganje. Oocite prikupljene u klaonicama bile su podvrgnute različitom trajanju IVM. Nakon toga jajašca su prvo partenogenetski aktivirana s ionomicinom kroz 5 minuta i nakon toga inkubirana tijekom određenih vremenskih razdoblja sa drugim aktivatorom, 6-DMAP. Protokoli po istraženim skupinama bili su sljedeći: a) kontrolna skupina 22 h IVM/4 h 6-DMAP, b) skupina 22 h IVM/5 h 6-DMAP, c) skupina 24 h IVM/4 h 6-DMAP i d) skupina 24 h IVM/5 h 6-DMAP. Razvojni stadiji in vitro kulture (IVC) procijenjivani su 4. i 8. dan. Za većinu razvojnih parametara nisu utvrđene razlike između istraženih skupina. Ipak, trajanja IVM i inkubacije sa 6-DMAP znakovito su utjecali (P<0,05) na kapacitet izlijeganja kad se u obzir uzme broj blastocista (izlijeganja/ blasociste). Također, isti pokazatelji bili su viši (P<0,05) u skupini b) 22 h IVM/5 h 6-DMAP (45,89 ± 12,59 %) u odnosu na skupinu c) 24 h IVM/4 h 6-DMAP (6,67 ± 6,67 %). Zaključno, trajanje IVM i inkubacije sa 6-DMAP utjecali su na partenogenetski razvoj, pri čemu je 22 h IVM/5 h 6-DMAP kombinacija koja u goveđih partenota proizvodi najvišu stopu za pokazetelj izlijeganje/blasociste

Feasibility of the adoption of soil erosion mitigation technology on farmland and pastures in northern Mexico

Objective: Identify the socioeconomic factors that determine the adoption of mitigation technologies of soil erosion in the Nazas-Aguanaval watershade at Durango State, Mexico. Design/methodology/approach: During 2018, 61 semi-structured surveys were applied to farmers in the region. The variables associated with the adoption disposition a binomial Logit regression of maximum likelihood was used. Results: Perception of the soil erosion problem, location of the watershade or agriculture productive unit, and economic activity were the most influential variables in the model. The main variable that conditions the disposition to improve the soil is the perception of soil erosion in the farm, with a marginal effect of 45.03 %. Limitations on study/implications: The results of this survey could be applicable to the study area only. Findings/conclusions: It is necessary to promote and increase the perception, understanding and acceptance of soil erosion mitigation technologies through training.Objective: To identify the socioeconomic factors which determine the adoption of soil erosion mitigation technologies in the Nazas-Aguanaval watershed region in the state of Durango, Mexico. Design/methodology/approach: During 2018, 61 semi-structured surveys were applied to farmers in the region. The variables associated with the willingness to adopt or not were analyzed with a maximum likelihood binomial Logit regression model. Results: Perception of the soil erosion problem, location of the watershed or agricultural unit, and economic activity were the most influential variables in the model. The main variable that conditions the willingness to adopt technologies to improve the soil is the perception of soil erosion in production areas, with a marginal effect of 45.03%. Limitations on study/implications: The results of this survey may only be applicable to the study area. Findings/conclusions: Training is necessary to promote and increase the perception, understanding and acceptance of soil erosion mitigation technologie

Structural analysis of an agroforestry area in a portion of the xeric shrubland of northeast of Mexico

Antecedentes y Objetivos: Los estudios de comunidades vegetales permiten conocer los impactos causados por las actividades agrícolas y pecuarias, especialmente en las zonas áridas. El objetivo de este trabajo fue contrastar la diversidad, composición y estructura de los estratos arbóreo y arbustivo de tres áreas (Agroforestal, Regenerada y Referencia) del matorral xerófilo. Métodos: Se establecieron tres áreas con cuatro sitios de muestreo de 1600 m2 cada una, elegidos al azar, en donde se censaron y registraron los individuos arbóreos y arbustivos. En cada área se calcularon parámetros ecológicos, así como los índices de Shannon y Margalef. Resultados clave: Considerando las tres áreas, se registró un total de 25 especies de plantas vasculares pertenecientes a 22 géneros y 15 familias. Fabaceae fue la familia mejor representada con nueve especies, siendo el género Acacia el que tuvo un mayor número (tres). Los valores de riqueza de especies, el índice de Shannon, índice de Margalef y abundancia, entre el área Referencia y Agroforestal, fueron similares, y en ambos los resultados fueron significativamente mayores que los valores del área Regenerada. El área Agroforestal presentó menor abundancia pero mayor dominancia comparada con las otras dos áreas estudiadas y fue el área que alcanzó el mayor porcentaje de similitud con el área de Referencia. Conclusiones: La actividad Agroforestal contribuye en cierta manera con el mantenimiento de la diversidad y la composición de plantas vasculares del matorral espinoso tamaulipeco estudiado; y dicha actividad no permite cambiar en gran medida la composición y estructura de este tipo de vegetación.Background and Aims: The studies of plant communities allow to know the impacts caused by the agricultural and livestock activities, especially in arid zones. The objective of this work was to contrast the diversity, composition and structure of the arboreal and shrub strata of three areas (Agroforestry, Regenerated and Reference) of the xerophilous scrub. Methods: In each area four sampling sites of 1600 m2 each one were established randomly, where all arboreal and shrubby individuals were registered and censused. In each area, ecological parameters were calculated, as well as the Shannon and Margalef indices. Key results: In the three areas, a total of 25 species of vascular plants belonging to 22 genera and 15 families were registered. The best represented family was Fabaceae with nine species, being the genus Acacia the one that presented the largest species number (three). The observed values of species richness, the Shannon index, Margalef index and abundance between the Reference and Agroforestry area were similar, and both were significantly higher than the values of the Regenerated area. The Agroforestry area presented lower abundance but greater dominance compared with the other two areas studied, and it was the area that reached the highest percentage of similarity with the Reference area. Conclusions: The Agroforestry activity contributes in a certain way in the maintenance of the diversity and composition of vascular plants of the Tamaulipan thorn scrub studied; and this activity does not allow to change to a large extent the composition and structure of this type of vegetation.Este estudio fue apoyado parcialmente por el proyecto PROMEP/103.5/12/3585