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Search Results: 1 - 10 of 3562 matches for " Rivera "
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Influence of Rainfall Pattern in the Seasonal Variation of Fish Abundance in a Tropical Estuary with Restricted Marine Communication  [PDF]
Manuel Castillo-Rivera
Journal of Water Resource and Protection (JWARP) , 2013, DOI: 10.4236/jwarp.2013.53A032
Pueblo Viejo Lagoon is an estuary with restricted communication with the sea, so the freshwater influence tends to be more important. Therefore, the study focused on testing the hypothesis that the seasonal changes in species abundance would be mainly related to the local rainfall pattern. Monthly samplings were carried out over a one-year, using a seine net. A total of 9108 individuals were caught, corresponding to 66 species of fish, most of them with marine origin. Canonical correspondence analysis revealed that the rainfall-salinity gradient was revealed to be the most important driving force in the seasonal variation of fish composition. In this way, it was observed that seasonal fluctuations in total fish number were linked to preceding fluctuations (one month) in local rainfall. Similar pattern was exhibited by the abundance of Anchoa mitchilli (the most abundant species), Oreochromis mossambicus and Ariopsis felis, and this delayed effect was significant (cross-correlation analyses). In addition, the rainfall showed a direct influence (significant positive correlations) on abundance of D. auratus and M. martinica. The association between fish number and the rainfall regime seems to be related to lagoon productivity and the trophic responses of these species. By contrast, Brevoortia gunteri and Menidia beryllina showed an inverse correlation with rainfall. Other environmental variables (also influenced by rainfall regime) showed a significant relationship with A. hepsetus (salinity), B. chrysoura (depth) and M. curema (turbidity). Thus, at least 12 species showed some relationship with local rainfall, which accounted for 81.27% of the total number of fish collected. Although it is difficult to separate the relative importance of
A Case of Ectopic Growth Hormone Releasing Hormone (GHRH) from Pancreatic Neuroendocrine Tumor Resistant to Therapy  [PDF]
Ohoud Almohareb, Juan Rivera
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2013, DOI: 10.4236/ojemd.2013.37037

Introduction: Ectopic secretion of GHRH is a rare cause of acromegaly. However, its recognition is clinically important because different therapeutic approaches are required. Case Presentation: We present a challenging case of acromegaly secondary to ectopic GHRH secretion from pancreatic neuroendocrine tumor in a 52-year-old female. The patient is treated with different modalities which include pegvisomant in an attempt to control the stimulated GH-axis considering the limited data about its use in treatment of ectopic acromegaly. Conclusion: GHRH-secreting tumor is a rare cause of acromegaly. Surgical resection of the tumor is the therapy of choice whenever possible. However, further studies are warranted for unresectable tumor or resistant cases.

Facing the 2013 Gold Rush: A Population Viability Analysis for the Endangered White-Lipped Peccary (Tayassu pecari) in Corcovado National Park, Costa Rica  [PDF]
Christian J. Rivera
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.516085
Abstract: The white-lipped peccary (Tayassu pecari) is facing range-wide declines throughout the Neotropics. It has been eliminated from about 89% of its historical range in Costa Rica. Corcovado National Park, in the Osa Peninsula of Costa Rica, is the last remaining stronghold for the white-lipped peccary in the country. In 2013, the Park experienced a sudden gold rush that brought with it a wave of 250 miners and vigorous hunting pressures on the population. Given that the species is endangered and is susceptible to hunting due to its herding behavior and tendency to cohere and attack when threatened rather than flee, it is important to assess its probability of extinction under various hunting scenarios. Incorporating data from studies on the life history of the species throughout its range in the Neotropics and in Corcovado, I used the population viability analysis software VORTEX to simulate the population trajectories and probabilities of extinction of the species under current hunting pressures and under various management scenarios. The results of this study revealed that under the 2013 scenario where 250 miners were present in the Park, the population of white-lipped peccaries has a about a 40% chance of extinction within five years and about a 99% chance of extinction within 10 years. Moreover, there is an “extinction threshold” for the population between the presence of 100 and 150 miners hunting in the Park. At this threshold, the population growth rate, r, drops from a positive growth rate (r = 0.09, SD = 0.08) to a negative one (r = -0.07, SD = 0.29). I suggest that anti-mining and anti-poaching laws be enforced immediately, and that the number of miners be reduced to 100 at a minimum, if not completely, in order to ensure that the population of white-lipped peccaries becomes viable and evades a local extinction.
Applied Linguistic-Tú and Usted Spanish Personal Subject Pronouns  [PDF]
Joel Laffita Rivera
Open Journal of Modern Linguistics (OJML) , 2019, DOI: 10.4236/ojml.2019.91002
Abstract: While the simple phonetics of Spanish language makes it easier to learn and speak irrespective of its grammar complexity, acquiring a good command of this language requires a serious and disciplined study of its grammar. The use of null and overt pronouns and their different grammar related forms in Spanish elevates the level of complexity when it comes to second language acquisition (SLA). In this regard, the teaching and learning of Spanish grammar still remains a subject of interest among linguists. Thereby, the article aimed to provide a guideline through which English language native speakers would gain an insight about language traits, associated with two pronouns and how they should be used in the speaking and writing context of Spanish language communication.
A Study Conception about Language Similarities  [PDF]
Joel Laffita Rivera
Open Journal of Modern Linguistics (OJML) , 2019, DOI: 10.4236/ojml.2019.92005
Abstract: The present study contains a suitable literature material about linguistic similarities between English and Spanish languages. The linguistic components chosen from both languages to conduct the study research are as follows: 1) Pronunciation. 2) Vocabulary. 3) Grammar. The study contextualizes throughout its collected works data based on alphabetical-phonology, wordlist-cognates, adjectives-adverbs-verbs-patterns as well as an oriented-methodology. At present, there is a need to continue making available methodology-inputs and learning materials to support the acquisition of Spanish as Second Foreign Language (ELE). Therefore, the research article aimed to provide a manuscript through which Spanish/English bilingual Spanish language teachers and English speaking learners of Spanish know about language analogies and the advantages of doing so to enhance and empower cognitive domains and language competences regarding to the target language.
Blended Learning-Effectiveness and Application in Teaching and Learning Foreign Languages  [PDF]
Joel Laffita Rivera
Open Journal of Modern Linguistics (OJML) , 2019, DOI: 10.4236/ojml.2019.92013
Abstract: The present research paper is designed to investigate the importance of the application of Blended Learning (BL) in education as a method for teaching and learning Foreign Languages Subjects (FLs) at university level. The study has used the mixed-method approach for the collection of data and its analysis. The study discloses: The research-design; Foreign Language-framework; Teaching and learning-roleplay-reflection and Methodology-schemes. Although the employment of BL is very important in teaching and learning practices; the paper-results concluded that there is a need to provide methodologies and computer training sessions to the FL teachers for effective employment of BL in foreign languages classes. Consequently to this the study aimed to deliver an applicable script through which Spanish language teachers and foreign language teachers obtain pedagogical-and computer knowledge-inputs to setup foreign languages classes through Blended Learning.
Different Interaction Mechanisms of Evaporated Porphyrin Films Exposed to NO2  [PDF]
M. Rivera, M. Rivera, J. M. Rivera, O. Amelines-Sarria, Y. A. Wang
Advances in Materials Physics and Chemistry (AMPC) , 2018, DOI: 10.4236/ampc.2018.811030

In this work, metal free and zinc tetraphenylporphyrin films were employed as nitrogen dioxide (NO2) gas sensors. The films were vacuum evaporated and the sensor response was evaluated as changes in the optical absorption spectra, hydrophobic properties and conductivity at different gas concentrations. From UV-Vis results, important changes in the absorption peaks were observed after gas exposure. The morphology of the films before and after gas interaction was obtained by using scanning electron and atomic force microscopy. The films morphology showed a degradation after gas adsorption for the metal free system but gas entrapment for the zinc porphyrin film. In order to elucidate the gas adsorption phenomena, density functional theory calculations were also performed. Here, it was observed that the porphyrin chemical structure not only affects the gas coordination sites which affect the porphyrin electronic distribution and packing arrangement, but also, determines the gas detection mechanism for sensing applications.

La ca?a de azúcar y sus derivados en la huasteca san luís potosí méxico
Aguilar Rivera,Noé;
Diálogos Revista Electrónica de Historia , 2010,
Abstract: sugar cane is the first and most important harvest in mexico, the sugar the change was drastic because of the larger native population and the spaniards’ interest in other commodities such as minerals and other agricultural products. in this paper its present a summary of the evolution and strategies for the development of sugar industry in la huasteca potosina san luis potosi at the viceroyalty of new spain.
ARQ (Santiago) , 2002, DOI: 10.4067/S0717-69962002005000012
Abstract: the minimal art project involved an indoor installation placed inside an art gallery in santiago, another outdoor structure located in front of a finnish museum and lately a construction placed in xxv sao paulo bienal. these works that apparently merely pursue formal games, relate to architecture from the perspective of the social housing policies, that shape, standardise, and serialise forms of life by virtue of the minimum dwelling space
Ensaio sobre o espa?o e o sujeito: Lygia Clark e a psicanálise
Rivera, Tania;
ágora: Estudos em Teoria Psicanalítica , 2008, DOI: 10.1590/S1516-14982008000200004
Abstract: an essay about space and subject: lygia clark and psychoanalysis. the present essay defends the idea that the psychoanalytic reflection about the subject implies a consideration of space and its configuration as freud's topical concern and lacan's topological search already indicate. the displacement of the subject would thus be joined by a subversion of space, which has been culturally explored, throughout the 20th century, by works of modern and contemporary art. therefore a dialogue with this body of work is sought; a dialogue which is specifically focused on the works of brazilian artist lygia clark, so as to propose, as a counterpoint to such works, renewed considerations concerning the psychic work throughout fantasy.
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