Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

We report a magnetic study of two preceramic hearths located at the southern region of Mexico City. Thermal demagnetization was applied between 200 to 540 °C to define the remanent magnetization components. The maximum unblocking temperature of the secondary magnetic component reached due to the last heating was identified in most samples. They were used to develop thermomagnetic anomaly source maps. The direction of this component was used to place the blocks to their last cooling spot and configurate a real and primal magnetic anomaly map produced by the thermoremanent magnetization acquired. A protocol to relocate blocks frame is proposed using geomagnetic secular variation curves. The thermomagnetic mapping revealed the position and temperature (220 to 460 °C) of the last heat sources. The distribution of these sources allowed to model an extensional zone of benefit and probable uses of the hearths.

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Es necesario explorar fuentes de proteína alterna para adicionar a la alimentación de aves en regiones rurales. Son contados los estudios realizados en moringa para este propósito. Se determinó el análisis proximal, el contenido de Fe, Ca y taninos a la harina de hoja de moringa. Se evaluó el efecto del consumo de una dieta con 10 % de harina sobre cuatro parámetros productivos y seis serológicos (dos proteínas y cuatro enzimas) en pollos de engorda Ross-308. También se realizaron estudios histopatológicos del hígado y riñón de los pollos. La hoja de moringa presentó 33.4 % de proteína y un alto contenido de hierro (19.7 mg/100 g) y calcio (2593.3 mg/100 g) así como bajo contenido de taninos (24.4 mg EC/100 g). Se observó una reducción del 12 y 20 % en la ganancia en peso y en el índice de productividad, respectivamente, en los pollos a los que se les adicionó moringa. No se observaron diferencias entre el grupo control y el adicionado con moringa en el contenido de proteínas y la actividad de la alanino aminotransferasa y la aspartato aminotransferasa, pero si en la albúmina, la fosfatasa alcalina y la gama galutamil transpeptidasa, que sugiere cierto daño hepático y renal. Estos resultados no se observaron en los estudios histológicos. Se sugiere seguir realizando estudios con niveles de complementación menor con la harina de moringa para comparar los efectos encontrados en el presente estudio y así poder definir su uso potencial.

This study is an evaluation of resistance to natural infection by Cooperia spp. in Zebu x Holstein crossbreed calves in the tropics. Fourteen four-month-old calves were dewormed and moved to pastures naturally infested with gastrointestinal nematodes under sub-humid tropical conditions. Fecal samples were collected from each animal every seven days for three months to quantify the number of eggs per gram of feces (EPG), and nematode species identified with end-point PCR. Hair samples were collected for genotyping using the GeneSeek Genomic Profiler HD-V3 panel, which contains 139,376 SNP markers. Variation in EPG per individual ranged from a minimum of 7+7 to a maximum of 4,657+1,886 EPG. The PCR identified breed differences between the Zebu x Holstein crossbreeds. Genome-wide association studies detected five statistically significant haplotypes (P<0.001). The haplotype in chromosome 2 includes four markers, that in chromosome 10 includes three, that in chromosome 15 includes two, that in chromosome 23 includes four and chromosome X includes three. Of these regions only chromosome 23 was found to be associated with parasite resistance, measured as EPG phenotypes. The remaining chromosomes exhibited no association in the studied animals. These regions could be sequenced and tested for gene expression against Cooperia and other gastrointestinal nematodes.

Microbial protein synthesized in the rumen is a major contributor of metabolizable protein. Thus, accurate estimation of microbial protein is essential in ruminant nutrition. The objective of this review is to describe the microbial composition, major factors affecting its yield and methods to estimate microbial protein flow to the intestine. The use of novel molecular techniques to elucidate the ruminal microbiome and improve methods for estimating microbial protein are discussed. Bacteria, protozoa, fungi and archaea compose the ruminal microbiome. Main factors affecting microbial protein synthesis are availability of carbohydrates, ruminally degradable protein, dietary fat, and ruminal pH. Major microbial markers used to estimate microbial protein synthesis are total purines, diaminopimelic acid and labeled nitrogen; in addition, DNA through real-time PCR is being tested for the estimation of bacterial, protozoal and yeast protein separately. The main difficulty in the estimation of microbial protein flow is obtaining representative microbial pellets from the rumen, which are used as reference to establish the ratio of marker/nitrogen. Detailed phylogenetic analysis using High-throughput DNA sequencing has recently revealed drastic taxonomic differences between fluid-associated bacteria and bacteria from whole intestinal digesta contents. For example, ruminal fluid contains less Fibrobacteres and Proteobacteria, but more Firmicutes compared to whole intestinal digesta. This demonstrates the need of developing effective bacterial collection procedures for obtaining representative ruminal microbial reference pellets to prevent bias on the estimation of the contribution of microbial protein to the intestinal supply of metabolizable protein.

The objective of this study was to evaluate the economic viability, through different supplementation strategies, of the post-weaning and finishing stages of cattle supplemented on Brachiaria brizantha cv. Marandu pastures during the rainy and dry seasons. The experimental period was 447 d. The study comprised the post-weaning and finishing stages of 22 intact male crossbred (½ Holstein-Zebu) cattle with an average initial weight of 164.09 ± 12.13 kg and an average age of 7 mo. The animals were distributed in a randomized design with 11 replications per treatment. The following supplementation strategies were tested: strategy 1 (S1): Mineral mix in the 1st and 3rd periods and protein-energy supplementation at 0.2 % of the body weight (BW) in the 2nd period; and strategy 2 (S2): protein-energy supplementation at 0.4 % BW in the 1st and 3rd periods, and protein-energy supplementation at 0.6 % BW in the 2nd period. Strategy 1 resulted in a lower cost per arroba produced and lower cost per hectare, generating a greater net profit per hectare and consequently a higher internal rate of return. When herbage is available, mineral supplementation supplied during the rainy season, associated with low levels of protein-energy supplementation in the dry season (S1), is of greater economic attractiveness for the development of the project, as it leads to higher internal rates of return and net present values in the entire period.

On April 27th 2018, the first summit in eleven years was held between North Korean and South Korean chief executives. This paper addresses Argentinian newspapers Clarín and Página 12&nbsp; editorial approaches pertaining to that summit. The purpose is to analyze whether there is a difference in the frequency of the media coverage and the editorial approach of both newspapers. This paper tries to explain these phenomena through Framing, Agenda-setting and Intermedia Agenda-setting theories, based upon authors such as Kiousis (2004), Zunino (2016), Martini, Luchessi (2004), Amadeo (2008), Amadeo and Aruguete (2013) and Aruguete (2015). Given that the summit is not considered to be controversial in Argentina, the hypothesis assumes that these newspapers, although divergent within the national arena, will have a similar coverage in this case. Following this aim, a mixed gathering “of successive stages” was done (first, a quantitative one, and then, a qualitative one) of media coverage on both newspapers. This was then processed and codified in order to build a measurement model utilizing different data matrices. The analysis of the index results show that the relevance given by both newspapers was medium level, with the presence of cover and back cover articles. When it comes to the editorial approach, both papers focused on concepts such as de-nuclearization and analysis of geopolitical consequences therein. However, Clarín adopts a bias position favoring the South Korean stand, together with rhetorical resources criticizing North Korean leadership and government. Thus, for this reason, the hypothesis has only a partial corroboration.

The tourism sector is considered in Ecuador as an economic and social activity, generating entrepreneurial opportunities that promote integral and inclusive development and improve the quality of life of the population. The objective of this research is to analyze the contribution of the Theories of Resources and Capacities (Grant, 1991, Barney, 1991, Stam, 2009), social entrepreneurship (Dees, 1998, Pollock, 2015, Buzinde et al., 2017) and that of community tourism (Murphy, 1985; Manyara and Jones, 2007, Kokkranikal and Morrison, 2011) for the creation of community tourism enterprises in the Province of Manabí of Ecuador. The methodology used is documentary and descriptive. Community tourism in Ecuador is part of a strategy of local development, promoted by the State for the claim and self-management of its territories and natural resources. The Theory of Resources and Capacities provides cognitive tools to social enterprises, based on key relationships among resources, capabilities and competitive advantages, this is not limited only to the business sector but on the contrary can be extrapolated to different types of organizations with In order to improve the planning, control, optimization of its processes and consecution of goals and objectives. It is concluded that the identification of the internal resources of community tourism ventures will allow us to know and size their structure and thus enhance their capabilities, suggesting an additional element to their self-management. It is of interest to emphasize that social entrepreneurship in the Manabi community tourism requires a profitable economic dimension because they are social enterprises that have an organizational structure with their natural, cultural and human resources and capacities that require an economic investment for their maintenance.

Nowadays the disclosure of information in organizations is mainly made through its web pages. However, sometimes it may not be of high quality or enough to reveal their responsibilities to its stakeholders. Under this premise, this investigation carries out the measurement of social responsibility of Ecuadorian credit unions in October 2018 by the disclosure of information in its web pages. Using the same structure of the work carried out by Navarro, Alcaraz and Ortiz (2010), indicators are established based on the Global Reporting Initiative (GRI). These are evaluated by determining both, their reliability and validity with the support of statistical tests. Through the technique of content analysis and based on the established indicators, an index that allows categorizing credit unions according to the level of social responsibility is established. It is concluded that the credit unions disclose practices related more to the economic issue than the social, therefore they would be relegating their cooperative essence, while the disclosure on environmental issues is minimal. Finally, it is determined that the credit unions of Segment 1 are those that disclose the best practices of social responsibility through their web pages.

The development of the future professional graphic design requires the constant use of didactic and financial resources for learning, the product of a growing market and with greater demands due to global growth. This directs the way to the use of teaching strategies in correspondence with the style of student learning that strengthen their potentialities. The objective is to evaluate the learning styles present in the students assigned to the Graphic Design program of FADLUZ, to generate teaching and motivational strategies that stimulate their learning. A descriptive and field research was considered, the sample consisted of 59 Students active and enrolled in the curricular units of the Instrumental Axis of the Graphic Design Program of the FADLUZ who were administered the Kolb Learning Styles Inventory of 1985 through a form in Google Form. Most students learn using Reflective Observation (OR) and are inclined primarily to two learning styles. The Assimilator with 51% followed by Divergent with 32% identified that the trend is towards a more balanced learning. To conclude that the identification of the type of learning style in Graphic Design students does not lead to a particular type of active teaching strategy, even though efforts can be focused on the design of activities, selection of educational material, presenting information, creating or not working groups and modifying the aspects to be evaluated. It is important for the student to identify their learning style to strengthen their training process. Likewise, motivation should be fostered that fosters the interest to learn, without neglecting the fact of knowing what strategies can be implemented according to the style of learning.