Occurrence and diffusive air-seawater exchanges of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in Fildes Bay, King George Island, Antarctica

We report the levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in seawater and air, and the air-sea dynamics through diffusive exchange analysis in Fildes Bay, King George Island, Antarctica, between November 2019 and January 30, 2020. Hexachlorobenzene (HCB) was the most abundant compound in both air and seawater with concentrations around 39 ± 2.1 pg m−3 and 3.2 ± 2.4 pg L−1 respectively. The most abundant PCB congener was PCB 11, with a mean of 3.16 ± 3.7 pg m−3 in air and 2.0 ± 1.1 pg L−1 in seawater. The fugacity gradient estimated for the OCP compounds indicate a predominance of net atmospheric deposition for HCB, α-HCH, γ-HCH, 4,4′-DDT, 4,4′-DDE and close to equilibrium for the PeCB compound. The observed deposition of some OCs may be driven by high biodegradation rates and/or settling fluxes decreasing the concentration of these compounds in surface waters, which is supported by the capacity of microbial consortium to degrade some of these compounds. The estimated fugacity gradients for PCBs showed differences between congeners, with net volatilization predominating for PCB-9, a trend close to equilibrium for PCB congeners 11, 28, 52, 101, 118, 138, and 153, and deposition for PCB 180. Snow amplification may play an important role for less hydrophobic PCBs, with volatilization predominating after snow/glacier melting. As hydrophobicity increases, the biological pump decreases the concentration of PCBs in seawater, reversing the fugacity gradient to atmospheric deposition. This study highlights the potential impacts of climate change, through glacier retreat, on the biogeochemistry of POPs, remobilizing those compounds previously trapped within the cryosphere which in turn will transform the Antarctic cryosphere into a secondary source of the more volatile POPs in coastal areas, influenced by snow and ice melting

Information and Communication Technologies, as a strategy to promote academic interest in students

Teniendo en cuenta la incidencia de las nuevas tecnologías en la educación de hoy, el propósito de la presente investigación radica en implementar las tecnologías de la información y la comunicación TIC en el aula de clase para fomentar el interés académico en los estudiantes de la IED Fundación. Metodológicamente la investigación se orientó desde una mirada Cualitativa, bajo el paradigma sociocritico; la unidad de análisis estuvo constituida por cuarenta (40) estudiantes del grado octavo entre las edades de catorce (14) quince (15) y dieciséis (16) años; como técnica de recolección de información se utilizó la observación participante, como instrumento de recolección, el diario de campo; a partir de las actividades desarrolladas con la implementación de las TIC en el aula de clase se encontró que los estudiantes presentan mayores niveles de motivación e interés por aprender, mejorando significativamente su promedio de notas cuándo se trabajan los contenidos curriculares articulados con estasTaking into account the incidence of new information and communication technologies in education today, the purpose of research in the implementation of information technology and communication students of the IED Foundation. Methodologically, the research was oriented from a Qualitative perspective, under the socio-critical paradigm; the analysis unit consisted of forty (40) eighth grade students between the ages of fourteen (14) fifteen (15) and sixteen (16) years; as a tool for gathering information, the collection instrument, the field diary; From the activities developed with the implementation of ICT in the classroom, students were found to have higher levels of motivation and interest in learning, significantly improving their grade point average when working with articulated curricular content

Patrones de demanda de las prestaciones maternas del programa de maternidad saludable, cantones Alausí, Guano, Penipe. Chimborazo. Julio 2000-Junio 2001

Master en Economía de la SaludCuenc

Cell migration: From tissue culture to embryos

Cell migration is a fundamental process that occurs during embryo development. Classic studies using in vitro culture systems have been instrumental in dissecting the principles of cell motility and highlighting how cells make use of topographical features of the substrate, cell-cell contacts, and chemical and physical environmental signals to direct their locomotion. Here, we review the guidance principles of in vitro cell locomotion and examine how they control directed cell migration in vivo during development. We focus on developmental examples in which individual guidance mechanisms have been clearly dissected, and for which the interactions among guidance cues have been explored. We also discuss how the migratory behaviours elicited by guidance mechanisms generate the stereotypical patterns of migration that shape tissues in the developing embryo. © 2014. Published by The Company of Biologists Ltd

Apical contacts stemming from incomplete delamination guide progenitor cell allocation through a dragging mechanism

The developmental strategies used by progenitor cells to endure a safe journey from their induction place towards the site of terminal differentiation are still poorly understood. Here we uncovered a progenitor cell allocation mechanism that stems from an incomplete process of epithelial delamination that allows progenitors to coordinate their movement with adjacent extra-embryonic tissues. Progenitors of the zebrafish laterality organ originate from the surface epithelial enveloping layer by an apical constriction process of cell delamination. During this process, progenitors retain long-term apical contacts that enable the epithelial layer to pull a subset of progenitors along their way towards the vegetal pole. The remaining delaminated progenitors follow apically-attached progenitors’ movement by a co-attraction mechanism, avoiding sequestration by the adjacent endoderm, ensuring their fate and collective allocation at the differentiation site. Thus, we reveal that incomplete delamination serves as a cellular platform for coordinated tissue movements during development. Impact Statement: Incomplete delamination serves as a cellular platform for coordinated tissue movements during development, guiding newly formed progenitor cell groups to the differentiation site

Vascular reactivity in intrapulmonary arteries of chicken embryos during transition to ex ovo life

The present study aimed to characterize pulmonary vascular reactivity in the chicken embryo from the last stage of prenatal development and throughout the perinatal period. Isolated intrapulmonary arteries from noninternally pipped embryos at 19 days of incubation and from internally and externally pipped embryos at 21 days of incubation were studied. Arterial diameter and contractile responses to KCl, endothelin-1, and U-46619 increased with incubation but were unaffected by external pipping. In contrast, the contractions induced by norepinephrine, phenylephrine, and electric field stimulation decreased with development. No developmental changes were observed in endothelium-dependent [acetylcholine (ACh) and cyclopiazonic acid] or endothelium-independent [sodium nitroprusside (SNP)] relaxation. These relaxations were abolished by the soluble guanylate cyclase inhibitior 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. Endothelium-dependent relaxation was unaffected by blockade of cycloox

Vitamin C and oxidative stress in the seminiferous epithelium

In this article, we focus on the fundamental role of vitamin C transporters for the normal delivery of vitamin C to germ cells in the adluminal compartment of seminiferous tubules. We argue that the redox status within spermatozoa or in semen is partly responsible for the etiology of infertility. In this context, antioxidant defence plays a critical role in male fertility. Vitamin C, a micronutrient required for a wide variety of metabolic functions, has long been associated with male reproduction. Two systems for vitamin C transport have been described in mammals. Facilitative hexose transporters (GLUTs), with 14 known isoforms to date, GLUT1-GLUT14, transport the oxidized form of vitamin C (dehydroascorbic acid) into the cells. Sodium ascorbic acid co-transporters (SVCTs), SVCT1 and SVCT2 transport the reduced form of vitamin C (ascorbic acid). Sertoli cells control germ cell proliferation and differentiation through cell-cell communication and form the blood-testis barrier. Because the blood-testis barrier limits direct access of molecules from the plasma into the adluminal compartment of the seminiferous tubule, one important question is the method by which germ cells obtain vitamin C. Some interesting results have thrown light on this matter. Expression of SVCT2 and some isoforms of GLUT transporters in the testis have previously been described. Our group has demonstrated that Sertoli cells express functionally active vitamin C transporters. Kinetic characteristics were described for both transport systems (SVCT and GLUT systems). Sertoli cells are able to transport both forms of vitamin C. These findings are extremely relevant, because Sertoli cells may control the amount of vitamin C in the adluminal compartment, as well as regulating the availability of this metabolite throughout spermatogenesis

Aplicación de un manual de habilidades motrices básicas en niños de NB1 de la comuna de El Bosque

Tesis (Educación Física)El desarrollo de las habilidades motrices básicas cumple un rol fundamental en el desarrollo físico de los niños, estas habilidades permiten adquirir patrones motores básicos tales como saltar, correr, lanzar, coordinar, entre otros, que se emplean y se utilizan desde la infancia hasta la adultez, lo que forma una especie de "vocabulario básico" de la motricidad. Si bien es cierto, muchas de estas habilidades motrices se desarrollan a una edad temprana, existen diferentes factores que determinan el nivel de desempeño en que se pueden emplear estas habilidades y que en ocasiones marcan diferencias entre las distintas cualidades de los niños. Por lo anteriormente expuesto, se plantea determinar la efectividad de un manual de apoyo de habilidades motrices básicas para la clase de educación física de NB1, en los colegios municipales Elena Caffarena, Ciudad de Lyon y Paúl Harris de la comuna de El Bosque. El diseño utilizado en este estudio es pre-experimental con un tipo de estudio descriptivo. Las variables evaluadas son identificación del cuerpo, Tabla de equilibrio, Salto con un pie, Salto y calda, Recorrido con obstáculos y Recepción de un balón. Durante el tiempo de la ejecución del manual se registraron diferencias significativas en el desarrollo de las habilidades motoras básicas en los niños que fueron evaluados. Es importante destacar la constancia en la ejecución de dicho manual para asi notificar este progreso y la diferencia de los resultados Pre y Post test