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Sexually hyperactive bucks are more efficient than sexually hypoactive bucks in stimulating testosterone secretion and sexual behaviour in other bucks in seasonal sexual rest by the phenomenon that we called the “buck-to-buck effect”. Here, we determined whether physical separation and reduction of the duration of contact with the sexually hyperactive bucks would modify those parameters in sexually hypoactive bucks exposed to the “buck-to-buck effect”. Bucks were subjected to natural day length throughout the study; this was the sexually hypoactive group. Other bucks were subjected to artificial long days (16 h of light per day) from 15 November to 15 January followed by exposure to natural day length to stimulate their sexual activity during the rest season; this was the sexually hyperactive group. In Experiment 1, we determined testosterone concentrations and sexual behaviour of six sexually hypoactive bucks separated 1.5 m from six sexually hyperactive bucks for 60 days by a metal open work fence, while a control group of six sexually hypoactive bucks was in permanent contact with six sexually hyperactive bucks. In Experiment 2, the duration of contact with sexually hyperactive males was reduced from 31 days (contact group, six bucks) to 10 days (withdraw group, seven bucks). In experiments 1 and 2, there was an effect of time (P

Seasonality of reproductive activity in rams and bucks is the major constraint in temperate and subtropical zones. Rapid alternation between 1 month of short days and 1 month of long days (LD) over three years in lightproof buildings eliminates this seasonality. We examined if this would also work in open barns, using only supplementary light. Over two years, one group of bucks (n = 7) was subjected to alternate 1 month of LD and 1 month of permanent light (LD–LL) and another group (n = 7) to alternate 1 month of LD and 1 month of natural light (LD–NL). A simultaneous control group, used for both experiments (CG1, n = 6; CG2, n = 6), remained under natural photoperiod. BW, testis weight (TW), plasma testosterone (T) and cortisol (C) were evaluated in all bucks. CG1 and CG2 bucks showed identical dramatic seasonal variations in BW (stable or decreasing in summer), TW (from 85 ± 12 g in February to 127 ± 7 g in July) and T (from 2.7 ± 1.2 ng/mL in January–April to 24.3 ± 3.2 ng/mL in June–October). By contrast, BW of LD–LL and LD–NL bucks increased regularly during the experiment. From 5 and 9 months after the experiment onset, LD–LL and LD–NL bucks, respectively, maintained constant TW of 115 ± 5 g until the experiment end. After the first 3 months

Strawberries are highly consumed around the world; however, the post-harvest shelf life is a market challenge to mitigate. It is necessary to guarantee the taste, color, and nutritional value of the fruit for a prolonged period of time. In this work, a nanocoating based on chitosan and ZnO nanoparticles for the preservation of strawberries was developed and examined. The chitosan was obtained from residual shrimp skeletons using the chemical method, and the ZnO nanoparticles were synthesized by the close-spaced sublimation method. X-ray diffraction, scanning electron microscopy, electron dispersion analysis, transmission electron microscopy, and infrared spectroscopy were used to characterize the hybrid coating. The spaghetti-like ZnO nanoparticles presented the typical wurtzite structure, which was uniformly distributed into the chitosan matrix, as observed by the elemental mapping. Measurements of color, texture, pH, titratable acidity, humidity content, and microbiological tests were performed for the strawberries coated with the Chitosan/ZnO hybrid coating, which was uniformly impregnated on the strawberries’ surface. After eight days of storage, the fruit maintained a fresh appearance. The microbial load was reduced because of the synergistic effect between chitosan and ZnO nanoparticles. Global results confirm that coated strawberries are suitable for human consumption.

Resumen: Introducción y objetivos: La tasa de detección de adenomas (TDA) es el más importante indicador de calidad para la prevención del cáncer colorrectal. Sin embargo, los pólipos serratos también son lesiones precursoras de cáncer colorrectal. El objetivo del estudio fue comparar la tasa de detección de pólipos serratos proximales (PSP) y la tasa de detección de pólipos serratos clínicamente significativos (PSCS), entre endoscopistas, y analizar la relación entre estos parámetros y la TDA. Métodos: Estudio observacional, transversal y prospectivo. Se incluyeron a todos los pacientes que acudieron para colonoscopia al Policlínico Peruano Japonés entre julio del 2015 y agosto del 2016. Se utilizó regresión logística multivariada para comparar la TDA, la tasa detección de PSP y la tasa de detección de PSCS entre los endoscopistas. Se calculó la asociación entre estos parámetros mediante el coeficiente de correlación de Pearson. Resultados: Fueron incluidos 15 endoscopistas y 1,378 colonoscopias. La tasa de detección de PSP estuvo en el rango de 1.8-17% entre los endoscopistas. La tasa de detección de PSP tuvo una correlación casi perfecta con la tasa de detección de PSCS (ρ = 0.922). La tasa de detección de PSP tuvo una fuerte correlación con la TDA (ρ = 0.769). Conclusiones: La tasa de detección de PSP tiene gran variabilidad entre endoscopistas, y tiene una correlación casi perfecta con la tasa de detección de PSCS, así como una fuerte correlación con la TDA. Estos resultados sugieren una alta tasa de PSCS perdidos por los endoscopistas con una baja tasa de detección de PSP. Abstract: Introduction and aims: The adenoma detection rate (ADR) is the most important quality indicator for the prevention of colorectal cancer but serrated polyps are also precursor lesions of the disease. The aim of our study was to compare the detection rate of proximal serrated polyps (PSPs) and that of clinically significant serrated polyps (CSSPs) between endoscopists and analyze the relation of those parameters to the ADR. Methods: An observational, prospective, cross-sectional study was conducted on all patients that underwent colonoscopy at the Policlínico Peruano Japonés within the time frame of July 2015 and August 2016. The ADR and PSP and CSSP detection rates between endoscopists were compared through multivariate logistic regression and the association between those parameters was calculated through the Pearson correlation coefficient. Results: The study included 15 endoscopists and 1,378 colonoscopies. The PSP detection rate ranged from 1.8-17% between endoscopists and had an almost perfect correlation with the CSSP detection rate (p = 0.922), as well as strongly correlating with the ADR (p = 0.769). Conclusions: There was great variability in the PSP detection rate between endoscopists. It also had an almost perfect correlation with the CSSP detection rate and strongly correlated with the ADR. Those results suggest a high CSSP miss rate at endoscopy and a low PSP detection rate.

Introduction and aims: The adenoma detection rate (ADR) is the most important quality indicator for the prevention of colorectal cancer but serrated polyps are also precursor lesions of the disease. The aim of our study was to compare the detection rate of proximal serrated polyps (PSPs) and that of clinically significant serrated polyps (CSSPs) between endoscopists and analyze the relation of those parameters to the ADR. Methods: An observational, prospective, cross-sectional study was conducted on all patients that underwent colonoscopy at the Policlínico Peruano Japonés within the time frame of July 2015 and August 2016. The ADR and PSP and CSSP detection rates between endoscopists were compared through multivariate logistic regression and the association between those parameters was calculated through the Pearson correlation coefficient. Results: The study included 15 endoscopists and 1,378 colonoscopies. The PSP detection rate ranged from 1.8-17% between endoscopists and had an almost perfect correlation with the CSSP detection rate (p = 0.922), as well as strongly correlating with the ADR (p = 0.769). Conclusions: There was great variability in the PSP detection rate between endoscopists. It also had an almost perfect correlation with the CSSP detection rate and strongly correlated with the ADR. Those results suggest a high CSSP miss rate at endoscopy and a low PSP detection rate. Resumen: Introducción y objetivos: La tasa de detección de adenomas (TDA) es el más importante indicador de calidad para la prevención del cáncer colorrectal. Sin embargo, los pólipos serratos también son lesiones precursoras de cáncer colorrectal. El objetivo del estudio fue comparar la tasa de detección de pólipos serratos proximales (PSP) y la tasa de detección de pólipos serratos clínicamente significativos (PSCS) entre endoscopistas, y analizar la relación entre estos parámetros y la TDA. Métodos: Estudio observacional, transversal y prospectivo. Se incluyeron a todos los pacientes que acudieron para colonoscopia al Policlínico Peruano Japonés entre julio del 2015 y agosto del 2016. Se utilizó regresión logística multivariada para comparar la TDA, la tasa detección de PSP y la tasa de detección de PSCS entre los endoscopistas. Se calculó la asociación entre estos parámetros mediante el coeficiente de correlación de Pearson. Resultados: Fueron incluidos 15 endoscopistas y 1378 colonoscopias. La tasa de detección de PSP estuvo en el rango de 1,8-17% entre los endoscopistas. La tasa de detección de PSP tuvo una correlación casi perfecta con la tasa de detección de PSCS (ρ = 0,922). La tasa de detección de PSP tuvo una fuerte correlación con la TDA (ρ = 0,769). Conclusiones: La tasa de detección de PSP tiene gran variabilidad entre endoscopistas, y tiene una correlación casi perfecta con la tasa de detección de PSCS, y una fuerte correlación con la TDA. Estos resultados sugieren una alta tasa de PSCS perdidos por los endoscopistas con una baja tasa de detección de PSP.

Longstanding disparities in four-year transfer rates for Black/African American and Latinx/Hispanic community college students, relative to their Asian and white peers, raise important equity questions about the vertical transfer function in the U.S. higher education system. Using data from one of the nation's largest and most racially and ethnically diverse community college systems, we examined whether differences in early academic momentum (e.g., first-year cumulative GPA, summer enrollment, number of first-year credits attempted and earned) were a root cause of gaps in transfer outcomes between different racial and ethnic groups. Multi-group structural equation modeling (SEM) results revealed a strong relationship between early academic momentum and vertical transfer success for community college students. However, the results showed academic momentum did not operate in the same manner for all racial and ethnic groups and some indicators were particularly important for improving transfer outcomes for Black/African American and Latinx/Hispanic students. These results have important implications for community college research and practice pertinent to vertical transfer outcomes.

El objetivo del trabajo era conocer el perfil de salud y la prevención cardiovascular mediante la historia personal, familiar y electrocardiograma de los adolescentes para mejorar las indicaciones sobre la realización de ejercicio físico en los centros escolares. Se realizó un estudio observacional descriptivo de una cohorte de alumnado de escuelas públicas y privadas. Muestra. 1391 adolescentes (667 chicos y 724 chicas). Metodología. Estudio observacional descriptivo. Cuestionario estructurado sobre la historia familiar y personal de ejercicio físico y factores de riesgo, y realización de un electrocardiograma. Resultados. El ejercicio físico entre 2 y 5 horas a la semana era realizado por el 45 % de los chicos y 47 % de las chicas y más de 5 horas, por el 39.7 % y 23 %, respectivamente. Síntomas: palpitaciones aisladas (23.7 % chicos y 39.1 % chicas), mareo y/o pérdida de conocimiento transitorio sin consecuencias (7.3 % y 13.8 % respectivamente), algún tipo de patología cardíaca controlada (4.2 % chicos y 2.1 % chicas). En los electrocardiogramas 59 presentaron alteraciones inespecíficas de la repolarización y 9 bloqueo incompleto de rama derecha, en todos se descartaron cardiopatías. Factores de riesgo detectados: hipertensión arterial (2.3 %), hipercolesterolemia (7.3 %), diabetes (2.3 %), preobesos (7.6 % chicos y 6.5 % chicas), obesidad (2.2 % y 1.5 % respectivamente) y fumadores de más de 6 cigarrillos al día (1.2 % chicos y 2.2 % chicas). Conclusión. La información del alumnado sobre sus antecedentes personales, familiares cardiovasculares, electrocardiograma y nivel de actividad física que realizan, permite llevar a cabo un programa de educación sanitaria que facilite mejorar los hábitos dietéticos, implementar la actividad física y eliminar los hábitos tóxicos o no saludables

Abstract In this work we study the possibility that the gamma ray excess (GRE) at the Milky Way galactic center come from the annihilation of dark matter with a (1, 0) ⊕ (0, 1) space-time structure (spin-one dark matter, SODM). We calculate the production of prompt photons from initial state radiation, internal bremsstrahlung, final state radiation including the emission from the decay products of the μ, τ or hadronization of quarks. Next we study the delayed photon emission from the inverse Compton scattering (ICS) of electrons (produced directly or in the prompt decay of μ, τ leptons or in the hadronization of quarks produced in the annihilation of SODM) with the cosmic microwave background or starlight. All these mechanisms yield significant contributions only for Higgs resonant exchange, i.e. for M ≈ M H /2, and the results depend on the Higgs scalar coupling to SODM, g s . The dominant mechanism at the GRE bump is the prompt photon production in the hadronization of b quarks produced in D ¯ D → b ¯ b $$ \overline{D}D\to \overline{b}b $$ , whereas the delayed photon emission from the ICS of electrons coming from the hadronization of b quarks produced in the same reaction dominates at low energies (ω < 0.3 GeV ) and prompt photons from c and τ , as well as from internal bremsstrahlung, yield competitive contributions at the end point of the spectrum (ω ≥ 30 GeV ). Taking into account all these contributions, our results for photons produced in the annihilation of SODM are in good agreement with the GRE data for g s ∈ [0.98, 1.01] × 10 −3 and M ∈ [62.470, 62.505] GeV . We study the consistency of the corresponding results for the dark matter relic density, the spin-independent dark matter-nucleon cross-section σ p and the cross section for the annihilation of dark matter into b ¯ b $$ \overline{b}b $$ , τ + τ − , μ + μ − and γγ, taking into account the Higgs resonance effects, finding consistent results in all cases.

Presentado en sesión de 6 de agosto de 1958

In semiarid conditions, feed is often scarce and variable with underfeeding being common; these factors can potentially induce fertility reductions in both sexes. Sexually active bucks are able to very efficiently fertilize out-of-season goats, but we do not know whether underfeeding would reduce the ability of bucks to fertilize goats during these periods. Two experiments were conducted to determine (i) testicular size and change of odor intensity of undernourished bucks exposed to long days and (ii) the ability of these bucks to stimulate reproductive activity in seasonally anestrous goats. In experiment 1, bucks (n = 7) were fed 1.5 times the normal maintenance requirements from September to May and formed the well-fed group. Another group of bucks (n = 7) were fed 0.5 times the maintenance requirements and formed the undernourished group. All bucks were subjected to artificially long days from 1 November to 15 January; this period was followed by a natural photoperiod until 30 May. Body weight, scrotal circumference and male odor intensity changes were determined every 2 weeks. In experiment 2, two groups of female goats (n = 26 each) were exposed to well-fed (n = 2) or undernourished bucks (n = 2) on 31 March. Ovulations and pregnancy rates were determined by transrectal ultrasonography. In experiment 1, a treatment by time interaction was detected for BW, scrotal circumference and odor intensity changes (P < 0.001). The BWs of well-fed bucks were greater than those of the undernourished bucks from October to May (P < 0.01), as were the scrotal circumferences from December to March (P < 0.05) and odor intensities from February to May (P < 0.05). In experiment 2, the proportions of females that ovulated at least once (100% v. 96%) or those that were diagnosed as pregnant (85% v. 77%; P > 0.05) did not differ significantly between the goats exposed to well-fed or undernourished bucks. The interval between the introduction of bucks and the onset of estrous behavior was shorter in goats exposed to well-fed bucks compared to the interval for those goats exposed to undernourished bucks (2.5 ± 0.2 v. 9.5 ± 0.6 days; P < 0.05). We conclude that undernourishment reduces the testicular size and odor intensity responses in bucks exposed to long days, but that undernourished bucks are still able to stimulate reproductive activity in seasonally anestrous goats, as is also the case for well-fed bucks.

The utilization of fossil fuel has increased atmospheric carbon dioxide (CO2) concentrations drastically over the last few decades. This leads to global warming and climate change, increasing the occurrence of more severe weather around the world. One promising solution to reduce anthropogenic CO2 emissions is methanation. Many researchers and industries are interested in CO2 methanation as a power-to-gas technology and carbon capture and storage (CCS) system. Producing an energy carrier, methane (CH4), via CO2 methanation and water electrolysis is an exceptionally effective method of capturing energy generated by renewables. To enhance methanation efficiency, numerous researches have been conducted to develop catalysts with high activity, CH4 selectivity, and stability against the reaction heat. Therefore, in this mini-review, the characteristics and recent advances of metal-based catalysts in methanation of CO2 is discussed.

The exposure of adult, female, Mediterranean goats during anoestrus to males with induced sexual activity via photostimulation, induces a very high percentage of ovulations. The present work examines the ability of photostimulated bucks to improve the male effect-induced reproductive response of young does over that induced by non-stimulated bucks. A 2×2 factorial experiment was designed, consisting of doe age and buck photoperiod treatments. During seasonal anoestrus, 41 does aged 7 (n=19) or 10 (n=22) months were subjected to the male effect on 10 April; half of each group was exposed to males rendered sexually active by prior exposure to 3 months of long days (16 h of light/day) from 31 October (PHOTO bucks), and half to males maintained under the natural photoperiod (CONTROL bucks). Oestrous activity was recorded daily by direct visual observation of the marks left by male-worn marking harnesses over the 32 days following the bringing of the sexes together (introduction). Doe body weight and body condition were determined weekly. Ovulation was detected by measuring plasma progesterone concentrations twice per week over the 3 weeks after introduction. The ovulation rate was assessed by transrectal ultrasonography. Fecundity, fertility, prolificacy and productivity were also determined. The interaction doe age × buck photoperiod treatment had no effect on any outcome. The percentage of females showing ovulation or oestrus was higher in the does exposed to PHOTO bucks (85% v. 43% for those exposed to CONTROL bucks) they also showed higher fertility (75% v. 43%) and productivity (1.05±0.17 v. 0.57±0.16 kids born per doe serviced) (all P values at least P

Recently, chitin and chitosan are widely investigated for food preservation and active packaging applications. Chemical, as well as biological methods, are usually adopted for the production of these biopolymers. In this study, modification to a chemical method of chitin synthesis from shrimp shells has been proposed through the application of high-frequency ultrasound. The impact of sonication time on the deproteinization step of chitin and chitosan preparation was examined. The chemical identities of chitin and chitosan were verified using infrared spectroscopy. The influence of ultrasound on the deacetylation degree, molecular weight and particle size of the biopolymer products was analysed. The microscopic characteristics, crystallinity and the colour characteristics of the as-obtained biopolymers were investigated. Application of ultrasound for the production of biopolymers reduced the protein content as well as the particle size of chitin. Chitosan of high deacetylation degree and medium molecular weight was produced through ultrasound assistance. Finally, the as-derived chitosan was applied for beef preservation. High values of luminosity, chromatid and chrome were noted for the beef samples preserved using chitosan films, which were obtained by employing biopolymer subjected to sonication for 15, 25 and 40 min. Notably; these characteristics were maintained even after ten days of packaging. The molecular weight of these samples are 73.61 KDa, 86.82 KDa and 55.66 KDa, while the deacetylation degree are 80.60%, 92.86% and 94.03%, respectively; in the same order, the particle size of chitosan are 35.70 μm, 25.51 μm and 20.10 μm.

Stylized facts appear in electoral processes worldwide, from Brazil to India. Here, we update a statistics carried on in Mexican elections but considering the inhomogeneities in electoral districts through the Nominal List (NL) (the list of valid electors in a given decision process) for the last three presidential elections. We find that the NL distribution at polling station detail is composed of, at least, three windows with a step function structure. Next, we study the consequences of the windows structure for the statistical properties of the processes. We obtain that the asymmetric vote distribution by polling station recovers a Gaussian shape for two of the windows; meanwhile, the standardized distribution of votes follows a distorted Gaussian, near to a skew normal. The distribution of the turnout at each polling station or voters’ participation ratio is close to a skew normal one in the bulk and failing at the wings. The average of voters increases in a linear way with the Nominal List and depends on the window considered. The results do not depend on the municipality, political district or urban versus nonurban distinction, and the electoral process considered.

In confined management systems, well-nourished bucks rendered sexually active by exposure to long days are efficient in fertilizing out-of-season goats. However, underfeeding is common in semi-extensive management systems and may reduce the reproductive efficiency of bucks. The objective of the present study was to determine whether nutritional supplementation improved the sexual activity of bucks submitted to long days in semi-extensive management systems and their ability to stimulate the reproduction of goats in semi-extensive or confined conditions. In experiment 1, three groups of bucks were placed in different flocks and grazed daily with females for 7 h. Each day after grazing, males were separated from females and moved into open pens. One group did not receive any treatment (control group; n = 6). Two other groups were submitted to artificially long days from 15 November to 15 January. From 16 January, one group did not receive nutritional supplementation (long-day group; n = 5), whereas bucks from the other group each received 600 g of a commercial concentrate (long-day+supplementation group; n = 5). The fourth group was kept in confined conditions, exposed to long days and fed alfalfa hay (long-day confined group; n = 6). On 26 March, anovulatory goats from other flocks were assigned to four groups (n = 27 each) and confined separately in open pens. Three bucks of each group were housed with the females. Pregnancy rates were greater in the goats housed with the long-day group than those housed with the control group (P

Background or Context: Although many scholars have evaluated how Hispanic-serving institutions (HSIs) "serve" and can better "serve" Latinx students and their communities, scant research has integrated artificial intelligence (AI) technology within this evaluation of diversity and "servingness." With institutions of higher education continuing to explore ways to integrate AI into their everyday operations, it is critical to understand whether HSIs are leveraging AI chatbot technology, given this specific technology's ubiquity in modern society. Purpose, Objective, Research Question, or Focus of Study: This study aimed to evaluate whether HSIs employ AI chatbot technology on their websites and the usability of this technology in accessing admissions information in English and Spanish. As a result, this study analyzes all 558 Hispanic-serving institution (.edu) websites and interacts with embedded AI chatbots to evaluate whether HSIs utilize chatbots and if these chatbots are engineered or staffed to communicate with Spanish-speaking audiences. Research Design: This study employed a mixed methods approach, utilizing qualitative and quantitative data collection and analysis methods. Given the study's emphasis on human-computer interaction, the researchers also engaged with interactive research methods to perform artificial intelligence testing. Conclusions or Recommendations: Findings suggest roughly 20% of HSIs employ AI chatbots, but far fewer use bilingual English/Spanish chatbots (12%). However, HSIs are equally as likely to staff English (20%) live agents as Spanish (21%) live agents when users are elevated from AI. Our findings demonstrate the importance of having Spanish and bilingual information embedded into HSIs to truly "serve" Latinx students and their families (Garcia, 2019). More specifically, Spanish should be incorporated within technological spaces where Latinx students and their communities may seek HSI information to pursue higher education such as how to apply for admission and financial aid. Ultimately, HSIs must consider how technology services like AI chatbots provide resources and answer questions in Spanish to ensure equitable access to information for Latinx students, their families, and their communities. Moreover, HSI leadership must continue to explore how HSIs may be transformed through technological innovation, such as artificial intelligence integration within digital spaces, including the HSI's website.

In this study, a novel hybrid material based on Polyvinyl Alcohol-Chitosan (PVA-Chi) was made, reinforced with conductive fillers such as the polypyrrole (PPy), Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS), carbon black (CB), and multi-wall carbon nanotube (MWCNT). In order to observe the mechanical and electrical responses of this composite material, for obtaining composite materials, and to characterize them for the development of applications in engineering, FTIR analysis made clear the different functional groups present in the matrix and the fillers used. Using quaternary mixtures (4 fillers) increased the contact angle, which increased hydrophobicity of the biocomposite. The Nyquist diagram of the analyzed samples showed a decrease in resistance and energy diffusion; the latter because of transferring electrons caused by the conductive polymers CB and the MWCNT. In the mechanical tension tests, Young’s modulus values of 18.386 MPa were obtained, in contrast with the material matrix of PVA-Chi, which showed values of 11.628 MPa. Morphological analysis by SEM showed the materials got were homogeneous. The materials got showed higher electrical conductivity in the OH’s presence and NH2 groups, which could have possible applications in biopolymer electrodes.

This multi-sited case study explored Men of Color (MoC) programs at Hispanic-serving community colleges. By employing frameworks designed to make meaning of Hispanic-serving institution (HSI) organizational identity, we examined how MoC program practitioners define the organizational identity of their Hispanic-serving community college, and how these understandings shape the services provided to Latino men. Findings underscored factors and identity markers that practitioners used to define HSI identity and "servingness" toward Latino men. In addition, our findings highlighted the problems and inconsistencies that exist when it comes to prioritizing the educational needs of community college Latino men. We provided implications for practice tailored for community college practitioners.

INTRODUCCIÓN El establecimiento de programas de Producción in vitro de Embriones (PIVE) se presenta como una herramienta para de los sistemas de producción bovina y como una forma de obtener entre un 30 a 40% de crías post Transferencia de Embriones (TE). El estrés oxidativo resultante de la exposición a concentraciones elevadas de oxígeno, luz, concentraciones inusuales de metabolitos y sustratos que inducen reacciones químicas perjudiciales, que provocan la producción de especies reactivas de oxígeno y nitrógeno (RON/RNS), ponen en peligro la PIVE. Aunque los gametos poseen mecanismos especializados que le permiten contrarrestar los efectos nocivos de estos radicales, bajo las condiciones in vitro, esto genera daños tanto estructurales como funcionales a nivel de mitocondrias, membrana lipídica, ácidos nucleicos, hasta provocar la apoptosis celular (Otoi, Do, Shibata, Taniguchi, Nii et al., 2015). Una estrategia para bloquear los efectos dañinos de ROS/ RNS durante la PIVE, es la suplementación de antioxidantes al medio de cultivo (Papis, Poleszczuk, Wenta‐Muchalska, & Modlinski, 2007; El-Raey, Geshi, Somfai, Kaneda, Hirako et al., 2011; Rodrigues-Cunha, Mesquita, Bressan, Collado, Balieiro et al., 2016). La Melatonina (MLT) es una indolamina secretada por la glándula pineal que posee un poder antioxidante muy versátil en comparación con otros antioxidantes. Estudios previos demuestran que las suplementaciones en los medios de cultivos con melatonina mejoran la tasa de desarrollo de embriones de ratón fecundados. En ovejas, los suplementos de melatonina incrementaron las tasas de eclosión de blastocistos. La adición de melatonina durante la maduración in vitro promueve la competencia meiótica en ovocitos bovinos (El-Raey et al., 2011). Un Estudio reciente demostró que ovocitos bovinos madurados en medios suplementados con MLT son capaces de mejorar el desarrollo embrionario in vitro (Tian, Wang, Zhang, He, Ji et al., 2017), así como también proteger las células del cúmulo de la fragmentación nuclear y aumentar la expresión génica de las enzimas antioxidantes (Rodrigues-Cunha et al., 2016). El objetivo de este estudio fue evaluar el efecto de la suplementación con Melatonina sobre la competencia ovocitaria y la fecundación de ovocitos bovinos.

INTRODUCCIÓN El objetivo de cualquier método para obtener ovocitos es lograr el mayor número de ellos viables para maximizar la producción de embriones in vitro. Existen deferentes factores que afectan la calidad de los ovocitos al momento de su recuperación mediante la técnica de ovum pick up (OPU), tales como el tipo y calibre de aguja, frecuencia de aspiración, raza y condición corporal de la vaca, etc. Entre ellos, la presión de vacío que se utiliza para su recuperación ha sido reiteradamente documentada (Hasler, 1998; Ward, Lonergan, Enright, & Boland, 2000; Boni, 2012). Las evidencias indican que la presión de vacío, durante la aspiración de ovocitos mediante OPU, afecta el número y características de los ovocitos recuperados, así como también su competencia para madurar y desarrollarse a blastocistos luego de la fecundación in vitro (FIV) (Hasler, 1998; Vos, Henriksen, & Dielman, 1999; Ward et al., 2000). Ward et al. (2000) evaluaron el efecto de cuatro presiones de vacío (30, 50, 70, 90 mmHg) sobre la competencia de los ovocitos de progresar a blastocistos luego de la FIV. Aunque la presión aplicada durante la OPU no afectó el número de ovocitos recuperados, como si lo indicaron otros estudios (Vos et al., 1999), los ovocitos aspirados con una presión de 90 mmHg comprometieron su viabilidad y redujeron en más de 20% lograr iniciar la segmentación luego de la FIV. Aun mas, las presiones de vacío superiores a 50 mmHg redujeron en promedio 2.8 y 4.5 veces la capacidad de los embriones para progresar a los estadios de blastocistos y blastocistos protruidos respectivamente (Ward et al., 2000). Se estableció como objetivo de este estudio determinar el efecto de la presión de vacío sobre ovocitos colectados de ovarios de matadero en la región sur de la sierra ecuatoriana a más de 2,500 msnm.

Los materiales compuestos son de vital importancia para el ser humano desde sus primeros tiempos, en la actualidad el empleo de estos materiales ha proliferado en la industria debido a la presencia de propiedades físicas que no están presentes en ninguno de sus componentes. El hecho de conocer previamente las propiedades de los materiales compuestos es unos de los problemas a los que se enfrenta la ciencia. Los métodos de homogeneización se emplean para calcular las propiedades efectivas de materiales compuestos. En el presente trabajo se plantea la formulación del método de homogeneización asintótica para compuestos tridimensionales y la transformación de los problemas locales a partir de las simetrías presentes en un compuesto de inclusiones elipsoidales periódicas. Se formula la resolución de los problemas locales por el método de elementos finitos utilizando elementos tetraédricos de cuatro nodos en la discretización del problema. Se realizan los cálculos numéricos para la obtención de los coeficientes efectivos en un material de inclusiones elipsoidales periódicas de aluminio embebidas en una matriz. La matriz es a su vez un compuesto del mismo aluminio con inclusiones esféricas de carburo de silicio con distribución cuadrada. Se muestran algunos de los resultados obtenidos para este compuesto variando la fracción volumétrica de aluminio para distintas razones de aspecto de las inclusiones elipsoidales. Se observa que en el caso de constituyentes isotrópicos, con una geometría del compuesto que presente una dirección predominante, el material resultante pierde esta propiedad.

El objetivo de este estudio fue comprobar la eficiencia de un entrenamiento de fuerza para el tren inferior y superior, basado en el mantenimiento de la potencia mecánica en jugadores cadetes de tenis. 18 tenistas (10 en el grupo experimental y 8 en el grupo control) participaron en el estudio. Se realizó un periodo de adaptación anatómica (cinco semanas de duración) previo al periodo de intervención en el grupo experimental. El periodo de intervención tuvo una duración de seis semanas donde se trabajó con los ejercicios de bench-press con peso libre y semi-squat en maquina Smith, con una carga estable del 60% de la fuerza dinámica máxima. Se evaluaron previa y posteriormente al periodo de intervención la potencia desarrollada en el tren superior como inferior con diferentes tests, tanto directos como indirectos. Los resultados parecen indicar que la metodología de entrenamiento basada en el mantenimiento de la potencia mecánica es eficiente para la mejora de la potencia máxima, permitiendo una optimización de las sesiones y minimizando el trabajo residual.Palabras clave: Fuerza, sobrecarga, fallo mecánico

The instrumental contains a system of indicators obtained from a study based on relevant concepts and criteria as well as the characterization of rural settlements. The system of indicators includes parameters which evaluate the environmental factors that constitute the rural settlement. The instrumental design has an implicit systemic and integral focus in order to achieve local sustainability. The instrument has been validated in five rural settlements within the municipality of Masaya, Nicaragua. The system of indicators was obtained from a compilation of the most significant forty variables or components. Taking into account the Theory of Systems and using a process of association, significance and graphical interrelationships fifteen specific indicators were obtained as well as six general indicators with their corresponding system category. The results of the validation are shown using histograms and matrices. In conclusion, the instrumental allows measurement and assessment of the environmental quality of settlements. It also demonstrates limitations as well as potential for improvement in living conditions for residents. The instrument can also act as a guide for integral development within rural settlements as well as the wider regions.

We investigated whether undernutrition during the second half of pregnancy impaired the behaviour of does and their kids at parturition and early mutual recognition. Twenty-two control and 22 underfed mixed-breed, multiparous dairy goats were used, together with their respective kids (control, n = 31: nine singles, 16 twins and six triplets; underfed, n = 32: 11 singles, 18 twins and three triplets). Undernutrition involved limiting protein and energy intake at 70% of the nutritional requirements for maintenance and foetal growth from day 70 of pregnancy until birth. The behaviour of mothers and their two first-born kids was observed for 90 min from the birth of each kid. Maternal olfactory recognition of the kid was assessed at 4 h post partum by testing selective nursing behaviour. Non-olfactory recognition was assessed at 8 h in a two-choice test excluding olfactory cues. In kids, preference for the mother was assessed in a two-choice test at either 12 or 24 h post partum. Bodyweight of does and kids were lower in the underfed group up to 2 weeks post partum. At parturition, licking, maternal bleating frequency and latency to nursing did not differ between nutritional groups. Control kids were faster than underfed kids to stand, search for and reach the udder, but underfed kids bleated more and tended to spend more time at the udder. Both control and underfed does accepted their own kid and rejected the alien in the selectivity test at 4 h. In contrast, at 8 h post partum, only control goats showed a significant preference for their own kid in the non-olfactory recognition test. Both control and underfed kids showed a preference for their own mother at 12 and 24 h and undernutrition during pregnancy had little influence on the performance of kids. However, 12 h-old underfed kids tended to be less active than control kids and visited their own mothers less than control kids. There were no significant correlations between the behaviour of the mother or of the kid at parturition and their performance in the discrimination tests. Overall, undernutrition in the second half of pregnancy appears to be more detrimental for the behaviour of the mother than for the kid. Furthermore, it has more impact on the establishment of maternal non-olfactory recognition than on maternal care at parturition or the establishment of maternal selectivity.

We investigated whether kids were able to discriminate their own mother from an alien one in a two-choice test on the day of birth when they had access to acoustic, visual and olfactory cues from their mother, and whether this discrimination depended on the selective maternal behaviour of the mother (i.e. exclusive nursing of own kids). When given the choice between their own mother and an alien equivalent dam, 8-h-old kids did not show a significant preference for their dam, whereas 12- and 24-h-old kids did. When given the choice between their own and an alien mother that were both non-selective because they had been rendered peripherally anosmic by irrigation of the nostrils with zinc sulphate, 12-h-old kids did not show a significant preference for their mother. These results are similar to those reported in sheep and may suggest that the contrast of behaviour between their own and an alien mother existing in normosmic does is important for discrimination of dams by kids at this age. Finally, testing 8-h-old kids in a smaller enclosure resulted in some improvement of their performance, although they still failed to display a significant preference for their mother. On the whole, kids are able to discriminate between their own and an alien mother goat as early as previously reported in lambs. The impairment of this ability when mothers are anosmic and not selective suggests that acceptance behaviours displayed by the mother may serve as one of the cues orientating the choice of the kid when given the choice between intact mothers. Finally, the present results do not suggest the existence of fundamental differences in the establishment of a preference for the mother between lambs, which are followers, and kids, which are hiders.

The milk production of dairy goats under various regimes of mother-young contact from day 4 post partum were studied during the first 2 months of lactation, together with the prolactin (PRL) and growth hormone (GH) responses to udder stimulation. In the control group, 13 goats and their kids were left in permanent contact and did not undergo milking. In two additional groups, goats were machine milked once a day in the morning (at 0800 h) and kids were allowed 10 hours (from 1000 to 2000 h; 10H group, n = 11) or 5 h (from 1000 to 2000 h; 5H group, n = 11) of mother-young interaction per day. In the last group (MO, n = 10), mothers were permanently separated from their kids on day 4 post partum and milked once a day. Milk production during a 24-h period at 37 days post partum performed by controlled nursing and weighing of the kids (groups with kids) or by two machine milking 12 h apart (milking only group) revealed a higher production in the three groups with some mother-young contact than in the MO group. Total milk collected by milking over the 2 months of the study did not differ between the three groups that underwent milking. Kid weights at 2 months were 3.4 to 4.8 kg. lighter in the groups that underwent milking than in the control group. Hormonal profiles were significantly affected by restricted mother-young contact, with highest pre-stimulation concentrations of PRL and GH in the 5H group. Restricting mother-young contact from the first week postpartum can permit an early collection of milk without major effects on kid growth, when compared with one daily milking in goats totally separated from their young.

La generación de residuos sólidos de concreto hidráulico, considerados como desecho, está convirtiéndose en un problema medioambiental. El material de construcción mayormente fabricado es el cemento Portland (CP), pero un problema es su alta temperatura de fabricación, que genera contaminantes. El uso de agregados triturados provenientes de demolición de concreto hidráulico se aprovecha para generar Concreto Hidráulico Reciclado, un material que puede abatir costos, disminuir la contaminación y abaratar la edificación. Sin embargo, la elaboración de concreto reciclado se enfrenta a la búsqueda de diseños óptimos para lograr el mayor desempeño mecánico bajo solicitaciones estáticas y dinámicas. En este trabajo se hace una revisión de los avances internacionales en esta temática.

En el trabajo se utiliza un nuevo esquema de análisis para el cálculo de las tensiones en la sección de la garganta de loscordones de soldadura de las uniones a solape con costuras de filete longitudinal y transversa; se obtienen expresiones decálculo que se corresponden mejor que las expresiones clásicas con relación a los valores obtenidos por el Método de losElementos Finitos.Palabras Claves: Uniones soldadas a solape, soldadura de filete, costuras de filete longitudinal y transversal._________________________________________________________________________________Abstract.In this paper a new scheme of analysis is used for the stress calculation in the throat welded area in laps joints with filletwelds transversely and longitudinally loaded. New calculation expressions are obtained that express better than the classicexpressions in relation to the values obtained by the Finite Elements Method.Key words: Lap welds, welded joints, fillet weld transversely loaded, fillet weld longitudinally loaded.

En el presente trabajo se aplica la Teoría de la Torsión de Perfiles de Paredes Delgadas para el cálculo de las tensiones enlas uniones soldadas con costuras de filete en perfiles de configuración geométrica compleja sometidas a torsión. Seobtienen nuevas expresiones para el cálculo de las tensiones cuyos resultados se aproximan mejor que las expresionesclásicas con relación a los resultados obtenidos por el Método de los Elementos Finitos.Palabras claves: Torsión, uniones soldadas, soldadura de filete.______________________________________________________________________________Abstract.In this paper, the Thin Walled profiles Torsion Theory is applied to calculation of torsional shear stresses of complex geometryprofiles welded joints fillets. New calculation expressions are obtained that allowed to obtain a better aproach than the classicexpressions in relation to the values obtained by the Finite Elements Method.Key words: Torsion, welded joints, welding fillets.

En el Trabajo se presentan los resultados de una investigación realizada por el colectivo de Mecánica Aplicada de laFacultad de Ingeniería Mecánica de La Universidad de Cienfuegos, con vistas a esclarecer la causa de la fractura delcigüeñal de uno de los motores de la Moto Nave “Mar del Sur” de le Empresa EQUITALL.La investigación del material del cigüeñal arrojó que se trata de acero 30. Los cálculos realizados demostraron, que lacapacidad resistente de este acero es insuficiente para soportar las tensiones que se desarrollan en el codo de salida delcigüeñal y los factores de seguridad a la fatiga en algunos de los puntos mas críticos del cachete, por donde se produjo lafractura, dan inferiores a la unidad y la aplicación de la Mecánica de la Fractura Subcrítica, confirmó que la Vida Útil delárbol con dicho material, es muy limitada.Palabras claves: Cigüeñal diesel, fractura por fatiga, mecánica de la fractura subcrítica.__________________________________________________________________________Abstract.This research paper shows the results of an investigation carried out by the Applied Mechanics staff of the MechanicalEngineering faculty of the Cienfuegos University. It was developed in order to determine the crankshaft failure causes ofengines of a boat diesel engine.The crankshaft material investigation showed that it was steel grade 30. The calculations showed that the steel resistancecapacity is not enough to support the stresses produced in the crankshaft output elbow. The fatigue security factors in someof the most critical areas of the cheek, where the failure took place, are lower than unity. The subcritical fracture mechanicsapplication confirmed that the shaft working life is quite limited with this steel.Key words: Diesel crankshaft, fatigue fracture, subcritical fracture mechanics.

En el trabajo se utiliza un nuevo esquema de análisis para el cálculo de las tensiones en la sección de la garganta de loscordones de soldadura de las uniones a solape con costuras de filete longitudinal y transversa; se obtienen expresiones decálculo que se corresponden mejor que las expresiones clásicas con relación a los valores obtenidos por el Método de losElementos Finitos.Palabras Claves: Uniones soldadas a solape, soldadura de filete, costuras de filete longitudinal y transversal._______________________________________________________________________________Abstract.In this paper a new scheme of analysis is used for the stress calculation in the throat welded area in laps joints with filletwelds transversely and longitudinally loaded. New calculation expressions are obtained that express better than the classicexpressions in relation to the values obtained by the Finite Elements Method.Key words: Lap welds, welded joints, fillet weld transversely loaded, fillet weld longitudinally loaded.

En el presente trabajo se aplica la Teoría de la Torsión de Perfiles de Paredes Delgadas para el cálculo de las tensiones enlas uniones soldadas con costuras de filete en perfiles de configuración geométrica compleja sometidas a torsión. Seobtienen nuevas expresiones para el cálculo de las tensiones cuyos resultados se aproximan mejor que las expresionesclásicas con relación a los resultados obtenidos por el Método de los Elementos Finitos.Palabras claves: Torsión, uniones soldadas, soldadura de filete._______________________________________________________________________________Abstract.In this paper, the Thin Walled profiles Torsion Theory is applied to calculation of torsional shear stresses of complex geometryprofiles welded joints fillets. New calculation expressions are obtained that allowed to obtain a better aproach than the classicexpressions in relation to the values obtained by the Finite Elements Method.Key words: Torsion, welded joints, welding fillets.

En el trabajo se presenta el cálculo de las tensiones de cortante en la sección de la garganta para las uniones soldadassometidas a flexión con costuras de filete de sección transversal asimétrica cuando el plano de carga no pasa por el centrode flexión o no coincide con los ejes centroidales principales de inercia. Los resultados obtenidos por las expresiones decálculo propuestas se comparan con los obtenidos por el Método de los Elementos Finitos demostrando de esta manera lavalidez de las mismas.Palabras claves: Flexión, uniones soldadas, soldadura de filete.___________________________________________________________________________Abstract.In this paper is presented the bending shear stresses calculation in the throat area for asymmetric welded joints with filletweldings, when the load plane does not go by the flexion center or it do not coincide with the mains inertia centroidal axes.The results obtained by the proposed expressions are compared with those obtained by the Finite Elements Methoddemonstrating by this way the validity of the same ones.Key words: Bending, welded joints, fillet weldings.

The aim of this study was to test the efficiency of upper and lower limb strength training, based on the maintenance of mechanical power in young tennis players. Eighteen male players voluntarily agreed to participate in the study (10 in the experimental group and 8 in the control group). We performed an anatomical adaptation period (five weeks) before the intervention period in the experimental group. The intervention period lasted six weeks where they worked a bench-press exercise with free weights and semi-squat in the Smith machine (steady load of 60% of the maximum dynamic force). Before and after the intervention period, the players’ upper and lower limb power was evaluated with different tests, both direct and indirect. The results suggest that the training methodology based on the maintenance of the mechanical power improved the maximum power, therefore allowing optimization of the length of the training session and minimizing residual training. Key Words: strength, overloading, mechanical failure

Density functional theory studies are reported to analyze the interaction between hydrogen sulfide (H2S) and graphene. The electron-ion interactions have been modeled using ultrasoft pseudopotentials and the exchange-correlation energies have been approximated by the method of the generalized gradient approximation in the parameterization of Perdew-Burke-Ernzerhof. Three graphene structures, one intrinsic and two with defects (vacancy and sustitution), and four H2S concentrations have been studied. The optimal geometries, binding energies, density of states (DOS) and charge density were obtained. In order to study the adsorption process three high symmetry sites were considered, namely, top, bridge, and center. The preferential adsorption structure corresponds to the center site in a physical way. The DOS of graphene-H2S systems shows a metallic behavior which coincides with the behavior of the isolated graphene. The geometrical structure of the graphene and the hydrogen sulfide remains unchanged.

Los sueros empleados para este estudio procedí­an de 40 vaquillas criollas encastadas de cebíº de dos años de edad, seronegativas a rabia al empezar el experimento. Se vacunaron cada una con una dosis (10 6-7 UFP) de la vacuna antirrábica cepa Y"¢319. Se sangró a los animales a 2, 3, 4 y 8 semanas y a 3 y 6 meses de la vacunación. Se efectuaron pruebas de seroneutralización en ratones y de reducción de placas con los sueros mencionados, a fin de comparar la sensibilidad relativa de las dos pruebas en la detección de anticuerpos tempranos (menos de 30 dí­as) y tardí­os (más de 30 dí­as). Se observó que la prueba de reducción de placa es 10 veces más sensible que la seroneutralización en ratones para detectar anticuerpos tempranos y cinco veces más sensible en la detección de anticuerpos tardí­os. La prueba de reducción de placas resultó más confiable y reproducible que la prueba de seroneutralización en ratones

Se utilizaron cuatro series de tres botellas de Roux cada una, con cada uno de los siguientes tratamientos: 1. Un lote testigo sin virus. 2. Un lote infectado con virus de estomatitis vesicular inactivado con radiaciones ultravioleta (VSV-UV). 3. Un lote infectado solamente con virus de rabia. 4. Un lote infectado con VSV-UV y posteriormente infectado con virus de rabia. Se tomaron muestras cada hora durante 48 horas de cada una de las botellas y se titularon en la prueba de placas en suspensión en agarosa. El virus obtenido en el tratamiento cuatro, fue tratado con suero antirrábico monoespecífico y fue neutralizado completamente por el suero. La constante de producción de virus rábico en los tratamientos tres y cuatro fue de K = 7.2 X 10-10 y de K = 8.4 X 10-10, respectivamente. Como promedio de los experimentos, el período de latencia fue reducido en 2.5 hs ± 30 minutos con respecto a los valores observados en el tratamiento tres. En virtud de los resultados obtenidos, es probable que la actividad de replicasa del virus de la estomatitis vesicular haya sido utilizada por el virus de la rabia. Estos resultados son preliminares y dado que el título final de virus fue el mismo, no se justifica la adición del VSV-UV a cultivos celulares para producción de vacuna, no sólo por el escaso efecto observado sino también por los riesgos de incluir ARN defectuoso de un virus diferente al que se desea producir.