Today, it is theoretically assumed that frozen storage of semen doses in liquid nitrogen guarantees sperm functionality indefinitely. However, there are few studies that objectively evaluate the effects of long-term storage on sperm quality parameters. In this study, we show a freezability analysis of bull semen stored for 1, 10, 25, 40 and 45 years at −196°C. Sperm viability and full sperm motility were analyzed by CASA system, and acrosome integrity was assessed with Coomassie blue staining. Our results showed that sperm viability and total sperm motility were not affected by long-term cryopreservation at −196°C. Specifically, we did not find any significant differences (p > 0.05) associated between different long-time storing analyzed; both parameters showed optimal values of sperm viability and total sperm motility (both over 60%). Additionally, the acrosomal integrity parameter was not affected, showing an optimal range (87±1.6-95±0.5%). We conclude that the sperm quality of bovine semen is not affected by longterm storage at −196°C. However, future field trials will be necessary in order to validate that both fertility and embryo viability are maintained for the times analyzed.

No abstract

Las redes de conocimiento y la colaboración organizacional son reflejo de una cultura del éxito, liderazgo transformacional y clima de relaciones en torno a las que se gestan relaciones de confianza, apoyo, innovación y metas. Se trata de organizaciones bidireccionales y horizontales con equidad y solidaridad. El objetivo del presente trabajo es establecer las correlaciones entre los factores. Se llevó a cabo un estudio no experimental, transversal y exploratorio con una selección de 300 administrativos, estudiantes y docentes de una universidad pública del centro de México. A partir de un modelo estructural, los resultados muestran que existe una relación de dependencia entre el clima de metas y la colaboración. A partir de estos hallazgos se advierten líneas de investigación relativas a la confianza como determinante de las redes de conocimiento y la colaboración organizacional.

Objective. Social historical reconstruction of the Ayotzinapa case from the perspective of Social Work intervention models. Methodology. Mixed, a qualitative, retrospective and hermeneutical study with key informants and other quantitative, cross-sectional and correlational research with an intentional selection of mobilization activists in favor of Ayotzinapa. Results. Disclosure of meanings from discourses and narratives of causal attribution of responsibility to the State for the enforced disappearance and genocide of 43 students, as well as relationships that determine the expectations of justice based on the expectations of honesty. Conclusion. The intersection device corresponds to a qualitative and quantitative diagnosis of the social representations of the Ayotzinapa case spread as a central axis of a public agenda.

Anthropocentrism and ecoperiphery are two foundations that the present work used to specify a model for the study of sustainable local entrepreneurship. The differences between beliefs of scarcity and abundance of resources generate values, skills and knowledge that guide the undertaking of conservation or consumption of natural resources. A review of the Human Development problem, the theoretical and conceptual frameworks, as well as the most recent findings about social entrepreneurship allowed the specification of the relationships between the factors reviewed for discussion. Given that the documentary research allowed the discussion of two options for social entrepreneurship, one oriented to the conservation of nature and the other oriented to the exploitation of natural resources and the consumerism of public services, it was possible to anticipate study scenarios in those that the analysis of local and sustainable would start with perceptions, beliefs, values, knowledge and skills that make it possible to explain austere or consumerist lifestyles. The objective of this work was to specify a model for the study of sustainable entrepreneurship considering a review of the literature from 2019 to 2021. A cross-sectional and psychometric work was carried out with a sample of 450 coffee growers. A structure of three factors was found that explained 27% of the total variance, although the contrast of the model is recommended in other scenarios and samples.