A New Characterization of Fine Scale Diffusion on the Cell Membrane

We use a large single particle tracking data set to analyze the short time and small spatial scale motion of quantum dots labeling proteins in cell membranes. Our analysis focuses on the jumps which are the changes in the position of the quantum dots between frames in a movie of their motion. Previously we have shown that the directions of the jumps are uniformly distributed and the jump lengths can be characterized by a double power law distribution. Here we show that the jumps over a small number of time steps can be described by scalings of a {\em single} double power law distribution. This provides additional strong evidence that the double power law provides an accurate description of the fine scale motion. This more extensive analysis provides strong evidence that the double power law is a novel stable distribution for the motion. This analysis provides strong evidence that an earlier result that the motion can be modeled as diffusion in a space of fractional dimension roughly 3/2 is correct. The form of the power law distribution quantifies the excess of short jumps in the data and provides an accurate characterization of the fine scale diffusion and, in fact, this distribution gives an accurate description of the jump lengths up to a few hundred nanometers. Our results complement of the usual mean squared displacement analysis used to study diffusion at larger scales where the proteins are more likely to strongly interact with larger membrane structures.Comment: 18 pages, 7 figure

Morphodynamics, sedimentary and anthropogenic influences in the San Vicente de la Barquera estuary (North coast of Spain)

The estuary of San Vicente de la Barquera (Cantabria, Spain) occupies two fluvial valleys that have incised into soft sedimentary rocks (Lower Mesozoic) and are controlled by inactive faults. These two estuary subsystems, the Escudo (main valley) and Gandarilla, share outer estuarine zones, i.e., a sandy bay and an estuary-mouth complex. The complexity of the system lies in the presence of a confining barrier formed by an aeolian dune/ beach system that is currently enclosed by a jetty, which has allowed the dune progradation over the past 50 years. Furthermore, connected to the inner inlet in the sand bay there is a flood-tidal delta, the most important morphosedimentary and dynamic unit. This unit exhibits a heart shape caused by the wide range of flows in this estuarine zone and channelizes the flows and sediments into the estuary, primarily during rising and high tides. In particular, the counter-clockwise surficial rotation due to the Coriolis effect is essential to the development of sand shoals, spill-over lobes, sand waves and megaripples. The presence of estuarine beaches into the bay is common in many Cantabrian estuaries, even culminating in small dune fields, in this case due to anthropogenic influences. This paper explains the impact on the estuary of human occupation and port management, focussing on the dynamic and sedimentary distribution of a bar-barrier estuary and the changes produced in its distal part by the construction of the two jetties in the mouth

Hydrodynamic controls of morpho-sedimentary evolution in a rock-bounded mesotidal estuary. Tina Menor (N Spain)

The Tina Menor estuary is a highly confined incised valley with advanced sedimentary infilling. The outstanding feature of this estuary is its longitudinal zonation, which forms four segments from the outer to the inner limit: Mouth complex, Bay, Tidal flats and Upper channel. The innermost part of the Bay and the Tidal Flats (semi-reclaimed areas) are broader estuarine zones, whereas the Mouth Complex and outermost Bay are confined by narrow rocky outcrops. This paper explains the dynamics and sedimentary distribution of a highly confined and singular estuary, detailing the fluvial-tidal controls on the variations in water mixing (QF/QT). This estuary is largely of salt wedge type and the dynamics are characterised by recording currents (speed and direction) in the water column during a tidal cycle in a spring tide; this process consists of the tidal waves propagation and their dissipation upstream hypo-synchronously and the mixing of fresh and saline waters. The morphology, dynamics and sedimentary distributions have been integrated to develop a conceptual model that demonstrates the circulation within the estuary. The sinuous geometry of the estuarine valley and the Coriolis Effect detected, play a fundamental role in determining the morphology and sedimentary distribution. Consequently, this study provides an adequate overview of this type of confined mesotidal estuary, quite common in the eastern Atlantic coast.The mrophology, dynamics and sedimentary distributions have been integrated to develop a conceptual model that demonstrates the circulation within the estuary. The sinous geometry of the estuarine valley and the Coriolis effect detected, play  a fundamental role in determining the morphology and sedimentary distribution. Consequently, this study provides an adequate overview of this type of confined mesotidal estuary, quite common in the eastern Atlantic coast.El estuario de Tina Menor es un valle encajado altamente confinado y sedimentariamente en un avanzado estado de colmatación. Se caracteriza por su zonación longitudinal en cuatro segmentos bien diferenciados desde su sector más externo hasta el límite interior: Complejo de Desembocadura, Bahía, Llanuras Mareales y Canal Superior. El interior de la Bahía y las Llanuras Mareales de carácter fangoso (zonas semi-reclamadas) son las más extensas, mientras que el Complejo de Desembocadura y la parte externa de la Bahía, están estrechamente confinadas por afloramientos rocosos. Este trabajo explica la distribución dinámica y sedimentaria de un estuario singular y altamente confinado, detallando los controles fluviales-mareales en la variación de las mezclas de agua (QF/QT). Este estuario es en gran parte del tipo de cuña salina y la dinámica fue caracterizada por las medidas de corrientes (velocidad y dirección) realizadas en la columna de agua durante un ciclo mareal en marea viva; este proceso consiste en la propagación de las ondas de marea y su disipación de aguas arriba hiposincrónicamente y la mezcla de aguas dulces y salinas. La morfología, dinámica y las distribuciones sedimentarias, se han integrado para desarrollar un modelo conceptual que demuestre la circulación dentro del estuario. La geometría sinuosa del valle estuarino y la detección del efecto de Coriolis, juegan un rol fundamental para determinar la distribución morfologica y sedimentaria. Consecuentemente, este estudio proporciona un visión adecuada de este tipo de estuarios mesomareales confinados, tan comunes en las costas atlánticas orientales

Oxygen content variation and cation doping dependence of (La)1.4(Sr1-yCay)1.6Mn2O7 (y = 0, 0.25, 0.5) bilayered manganites properties

The results of the synthesis and characterization of the optimally doped (La)1.4(Sr1-yCay)1.6Mn2O7 solid solution with y=0, 0.25 and 0.5 are reported. By progressively replacing the Sr with the smaller Ca, while keeping fixed the hole-concentration due to the divalent dopant, the 'size effect' of the cation itself on the structural, transport and magnetic properties of the bilayered manganite has been analysed. Two different annealing treatments of the solid solution, in pure oxygen and in pure argon, allowed also to study the effect of the oxygen content variation. Structure and electronic properties of the samples have been investigated by means of X-ray powder diffraction and X-ray absorption spectroscopy measurements. Magnetoresistivity and static magnetization measurements have been carried out to complete the samples characterization. Oxygen annealing of the solid solution, that showed a limit for about y=0.5, induces an increase of the Mn average valence state and a transition of the crystal structure from tetragonal to orthorhombic while the argon annealing induces an oxygen under-stoichiometry and, in turn, a reduction of the Mn average valence state. Along with the Ca substitution, the Jahn-Teller distortion of the MnO6 octahedra is reduced. This has been directly connected to a general enhancement of the transport properties induced by the Ca-doping. For the same cation composition, oxygen over-stoichiometry leads to higher metal-insulator transition temperatures and lower resistivity values. Curie temperatures (TC) reduce by increasing the Ca-doping. The lower TC for all the annealed samples with respect to the 'as prepared' ones are connected to the strong influence on the magnetic interaction of the point defects due to the oxygen content variation.Comment: 49 pages, 13 figure

El complejo de dunas eólicas de la Playa de Frouxeira (Meirás-Valdoviño, La Coruña)

[Resumen] Dentro del complejo dunar, situado en la parte posterior de la playa de Frouxeira, se han distinguido varios tipos de dunas : montículos aislados, remontantes, parabólicas y blow-outs y cartografiados en cuatro subzonas: dunas activas, subrecientes, remontantes y fósiles. Se establecen las características texturales de las arenas dunares y de playa, tanto granulométricas como a partir de los índices de correlación lineal entre los diferentes parámetros, además del contenido carbonatado. Finalmente, se determina la evolución sedimentaria y su relación con el resto de la cornisa cantábrica, mediante los datos prehistóricos asociados al medio de depósito[Abstract] Several coastal sand dunes are classified ( isolated mounds, climbing, parabolic and blow-outs ) and they are distributed in four areas: active, subrecent, climbing and fossil ones. Textural patterns as well granulometric parameters as lineal correlation index among them are stablished. Finally, the sedimentary evolution is determlnated by the help of the prehistoric information from the Asturian and Cantabrian region

Geomorphological evolution of the calcareous coastal cliffs in North Iberia (Asturias and Cantabria regions)

This paper presents an analysis of the main morphologies observed in the coastal cliffs of northern Spain (Asturias and Cantabria regions). The objective of this contribution is to establish a hypothesis on the origin and evolution of this rocky coast, as well as to present a detailed inventory, to characterise quantitatively and qualitatively singular morphologies and to highlight the geological heritage of this protected coast. The evolution process starts with the formation of an ancient coastal planation surface characterised by a flat morphology caused by regional mainly uplift and to relative sea level falls. Afterwards, wave erosion processes would have started eroding the cliff foot and simultaneously, karst activity produced some exokarst morphologies (sinkholes, karren, etc.) through stratification and fracturing network, while the underground drainage systems produced some caves and chasms. In the following step, corresponding to the last glaciation from the paleoclimatic point of view, sea level fall together with a deepening of the fluvial network caused the preservation of the existing caves and chasms and the generation of new ones at a lower level. On the other hand, dissolution processes on limestones created sinkholes in those areas characterised by alternating layers of limestones and marls, generating collapses. When the sea level reached the maximum height during the Holocene a new erosion cycle of the coastal cliffs began. As a consequence, new landforms and processes were produced, like bays, caves fillings, and intrusion of new sediments in small confined estuaries. In these areas, other types of morphologies associated with the last sea level rise can be observed, such as closed beaches, uncommon closed estuaries developed inside a sinkhole, blowholes produced by mixed wave action and widening of prevailing vertical pipes inside the limestones (including the second largest in the world), total or partial sedimentary filling of small confined estuaries, as well as a tombolo deposit. It is important to point out, that some sites described are included in the Spanish Inventory of Sites of Geological Interest (IELIG). Due to the evolution model here proposed, a portion of the coastal sector described are included in the Global Geosites Project

Organização e aplicação de um caso simulado cts em aulas de química no ensino médio

Atualmente muito se discute sobre como a Química é geralmente trabalhada no Ensino Médio: descontextualizada, sem relações com a sociedade e o cotidiano dos estudantes. Muitas vezes, o ensino se dá como se estivesse resumido à memorização de nomes complexos e aplicação de fórmulas na resolução de problemas sem relação com aspectos sociais da ciência. Para promover mudanças nesse cenário, é necessário um posicionamento crítico por parte de professores e estudantes e compreendemos que a utilização de abordagens CTS (Ciência, Tecnologia e Sociedade) no ensino de Química pode contribuir nesse sentido. A fim de colaborar com as reflexões sobre mudanças no foco da Educação Química, buscando formas de romper a barreira do ensino tradicional, apresentamos esse estudo no qual são mostrados a organização e aplicação de um Caso Simulado CTS em aulas de Química no Ensino Médio

Analyse demographique de l'Ile de Sainte Lucie; 1946-1970.

Memoire (M.Sc.), Universite de Montreal, 1976.IDRC pers CRDI. Etude sur le profil demographique et la dynamique de la population de Sainte Lucie de 1946 a 1970 - discute la croissance demographique dans une perspective historique; analyse la structure de la population par age et par sexe, et tout particulierement l'evolution de la mortalite, de la fecondite et de l'emigration; inclut des projections, donnees statistiques, bibliographie

Elaboración de nueve guías complementarias de laboratorio para la ejecución de prácticas de aplicación analítica en la asignatura laboratorio de Análisis Instrumental I

La química cumple un papel importante en la vida del hombre a nivel personal e industrial, actualmente en cada industria utilizan métodos instrumentales para el control de calidad de productos y servicios de análisis, la labor del profesional de la química principalmente el tecnólogo químico con formación analítica es aplicar las técnicas instrumentales para optimizar y verificar ensayos, y que estos cumplan con los estándares establecidos y fomenten en el proceso de aprendizaje la motivación, aprehensión, retención, recuperación, generalización, desempeño y retroalimentación relacionándolas con las capacidades como son las destrezas motoras, la información verbal, destrezas intelectuales, actitudes y estrategias. Las prácticas de laboratorio a desarrollar permitirán comprobar los conocimientos teóricos desarrollados en la asignatura de análisis instrumental I, sirviendo de apoyo para complementar el trabajo practico descrito en el manual de laboratorio de análisis instrumental ya existente y el cual se seguirá utilizando, puesto que todas las técnicas que se estudian son aplicadas en el campo laboral del sector industrial, la labor de los químicos analistas es planificar, ejecutar, evaluar y reportar resultados de determinaciones analíticas