García Márquez's Pentimenti

Latin American Studie

English-Spanish Cognates in the Charlotte Zolotow Award Picture Books: Vocabulary, Morphology, and Orthography Lessons for Latino ELLs

English-Spanish cognates are words that are orthographically and semantically identical or nearly identical in English and Spanish as a result of a common etymology. Because of the similarities in the two languages, Spanish-dominant Latino English Language Learners (ELLs) can be taught to recognize English cognates thereby increasing their bilingualism and bi-literacy for these two languages. There are over 20,000 English-Spanish cognates, many of the academic vocabulary words. Despite their vast educational potential, however, cognates are typically excluded as a word category in the language arts curriculum, thus denying Latino ELLs of a resource for acquiring English-Spanish bilingualism and bi-literacy. English-Spanish cognates may be distinguished from non-cognate words by their rule-governed morphological and orthographic structures. To capitalize on the inherent differences between cognates and non-cognates, the present manuscript presents morphological and orthographic strategies that can be used to teach Latino ELLs to recognize the rich cognate vocabulary found in picture books, specifically, those books which have been cited as Charlotte Zolotow Award winners and honor books. Through these strategically-designed language activities revolving around the read-alouds of the Zolotow Award books, teachers can introduce Latino ELLs to cognates in the early primary school years to encourage their development of bilingualism and bi-literacy

Low pO2 selectively inhibits K channel activity in chemoreceptor cells of the mammalian carotid body

The hypothesis that changes in environmental O2 tension (pO2) could affect the ionic conductances of dissociated type I cells of the carotid body was tested. Cells were subjected to whole-cell patch clamp and ionic currents were recorded in a control solution with normal pO2 (pO2 = 150 mmHg) and 3-5 min after exposure to the same solution with a lower pO2. Na and Ca currents were unaffected by lowering pO2 to 10 mmHg, however, in all cells studied (n = 42) exposure to hypoxia produced a reversible reduction of the K current. In 14 cells exposed to a pO2 of 10 mmHg peak K current amplitude decreased to 35 +/- 8% of the control value. The effect of low pO2 was independent of the internal Ca2+ concentration and was observed in the absence of internal exogenous nucleotides. Inhibition of K channel activity by hypoxia is a graded phenomenon and in the range between 70 and 120 mmHg, which includes normal pO2 values in arterial blood, it is directly correlated with pO2 levels. Low pO2 appeared to slow down the activation time course of the K current but deactivation kinetics seemed to be unaltered. Type I cells subjected to current clamp generate large Na- and Ca-dependent action potentials repetitively. Exposure to low pO2 produces a 4-10 mV increase in the action potential amplitude and a faster depolarization rate of pacemaker potentials, which leads to an increase in the firing frequency. Repolarization rate of individual action potentials is, however, unaffected, or slightly increased. The selective inhibition of K channel activity by low pO2 is a phenomenon without precedents in the literature that explains the chemoreceptive properties of type I cells. The nature of the interaction of molecular O2 with the K channel protein is unknown, however, it is argued that a hemoglobin-like O2 sensor, perhaps coupled to a G protein, could be involved

Ionic currents in dispersed chemoreceptor cells of the mammalian carotid body

Ionic currents of enzymatically dispersed type I and type II cells of the carotid body have been studied using the whole cell variant of the patch-clamp technique. Type II cells only have a tiny, slowly activating outward potassium current. By contrast, in every type I chemoreceptor cell studied we found (a) sodium, (b) calcium, and (c) potassium currents. (a) The sodium current has a fast activation time course and an activation threshold at approximately -40 mV. At all voltages inactivation follows a single exponential time course. The time constant of inactivation is 0.67 ms at 0 mV. Half steady state inactivation occurs at a membrane potential of approximately -50 mV. (b) The calcium current is almost totally abolished when most of the external calcium is replaced by magnesium. The activation threshold of this current is at approximately -40 mV and at 0 mV it reaches a peak amplitude in 6-8 ms. The calcium current inactivates very slowly and only decreases to 27% of the maximal value at the end of 300-ms pulses to 40 mV. The calcium current was about two times larger when barium ions were used as charge carriers instead of calcium ions. Barium ions also shifted 15-20 mV toward negative voltages the conductance vs. voltage curve. Deactivation kinetics of the calcium current follows a biphasic time course well fitted by the sum of two exponentials. At -80 mV the slow component has a time constant of 1.3 +/- 0.4 ms whereas the fast component, with an amplitude about 20 times larger than the slow component, has a time constant of 0.16 +/- 0.03 ms. These results suggest that type I cells have predominantly fast deactivating calcium channels. The slow component of the tails may represent the activity of a small population of slowly deactivating calcium channels, although other possibilities are considered. (c) Potassium current seems to be mainly due to the activity of voltage-dependent potassium channels, but a small percentage of calcium-activated channels may also exist. This current activates slowly, reaches a peak amplitude in 5-10 ms, and thereafter slowly inactivates. Inactivation is almost complete in 250-300 ms. The potassium current is reversibly blocked by tetraethylammonium. Under current-clamp conditions type I cells can spontaneously fire large action potentials. These results indicate that type I cells are excitable and have a variety of ionic conductances. We suggest a possible participation of these conductances in chemoreception

Aprendizaje del concepto de matriz a través de problemas aplicados a la ingeniería

En este trabajo, se presentan los avances del proyecto de investigación que tiene como objetivo describir las construcciones y mecanismos mentales de los estudiantes de la carrera de ingeniería en mecatrónica de la UPZ (Universidad Politécnica de Zacatecas), respecto al concepto de matriz cuando se enfrenta a situaciones problemáticas aplicadas a la ingeniería en mecatrónica. El marco teórico que sustenta la investigación es la teoría APOE, la cual cuenta con un ciclo de investigación como metodología. Este ciclo consta de tres fases: análisis teórico del concepto, diseño e implementación de enseñanza y el análisis y verificación de los datos. Se presenta como avance de la investigación, la primera componente del ciclo de la teoría APOE, que da como resultado una descomposición genética preliminar del concepto de matriz

Energy conditions in modified Gauss-Bonnet gravity

In considering alternative higher-order gravity theories, one is liable to be motivated in pursuing models consistent and inspired by several candidates of a fundamental theory of quantum gravity. Indeed, motivations from string/M-theory predict that scalar field couplings with the Gauss-Bonnet invariant, G, are important in the appearance of non-singular early time cosmologies. In this work, we discuss the viability of an interesting alternative gravitational theory, namely, modified Gauss-Bonnet gravity or f(G) gravity. We consider specific realistic forms of f(G) analyzed in the literature that account for the late-time cosmic acceleration and that have been found to cure the finite-time future singularities present in the dark energy models. We present the general inequalities imposed by the energy conditions and use the recent estimated values of the Hubble, deceleration, jerk and snap parameters to examine the viability of the above-mentioned forms of f(G) imposed by the weak energy condition.Comment: 9 pages, 8 figures. V2: minor additions and corrections; to appear in PR

High-throughput biodiversity analysis: Rapid assessment of species richness and ecological interactions of Chrysomelidae (Coleoptera) in the tropics

Biodiversity assessment has been the focus of intense debate and conceptual and methodological advances in recent years. The cultural, academic and aesthetic impulses to recognise and catalogue the diversity in our surroundings, in this case of living objects, is furthermore propelled by the urgency of understanding that we may be responsible for a dramatic reduction of biodiversity, comparable in magnitude to geological mass extinctions. One of the most important advances in this attempt to characterise biodiversity has been incorporating DNA-based characters and molecular taxonomy tools to achieve faster and more efficient species delimitation and identification, even in hyperdiverse tropical biomes. In this assay we advocate for a broad understanding of Biodiversity as the inventory of species in a given environment, but also the diversity of their interactions, with both aspects being attainable using molecular markers and phylogenetic approaches. We exemplify the suitability and utility of this framework for large-scale biodiversity assessment with the results of our ongoing projects trying to characterise the communities of leaf beetles and their host plants in several tropical setups. Moreover, we propose that approaches similar to ours, establishing the inventories of two ecologically inter-related and species-rich groups of organisms, such as insect herbivores and their angiosperm host-plants, can serve as the foundational stone to anchor a comprehensive assessment of diversity, also in tropical environments, by subsequent addition of trophic levels.The ‘Fundación BBVA’ (Spain) has funded the bulk of this work thanks to their support for our large-scale biodiversity assessment initiative in Nicaraguan tropical dry forests (project BIOCON08-045, IP: JGZ). Our work in Nicaragua has benefited from a postdoctoral ‘Juan de la Cierva’ contract (Spanish Ministry of Science and Innovation, MICINN) to AP, and an AECID predoctoral studentship (Spanish Ministry of Foreign Affairs and Cooperation) and a SENESCYT scholarship (Secretariat of High Education, Science, Technology and Innovation, Ecuador) to GDC. The National Geographic Society supported most of our research in New Caledonia (project 8380-07, IP: JGZ) with help from a travel grant awarded by the Percy Sladen Memorial Fund of the Linnean Society of London to JGZ. The Spanish High Research Council (CSIC), in the framework of a cooperation agreement with the Vietnamese Academy of Sciences, supports our work in dry tropical forests of southern Vietnam (IP: JGZ) as well as a predoctoral studentship to DTN. Several EU Synthesys research stays (GB-TAF-1840, SE-TAF-1893, DE-TAF-4348) and a Mayr Travel Grant (Harvard University) as well as project CGL2008-00007/BOS (MICINN, IP: JGZ) have contributed to the discovery of a new tropical species of Calligrapha, and the latter also framed the predoctoral studentship to TM.Peer Reviewe