6,717 research outputs found
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
Post reunification economic fluctuations in Germany: A real business cycle interpretation
We consider the cyclical properties of the German economy prior and after reunification in 1990 from the perspective of a real business cycle model. The model provides the framework for the selection and consistent measurement of the variables whose time series properties characterize the cycle. Simulations of the calibrated model reveal the model's potential to interpret the data. Major findings are that: i) the volatility of most aggregate time series has not changed significantly between the two time periods, ii) despite many conceptual differences between the European and the U.S. System of Accounts, the calibrated parameter values for the German economy are within the range of values usually employed in the real business cycle literature, iii) the model is closer to the data for the time period prior to reunification
Post reunification economic fluctuations in Germany: A real business cycle interpretation
We consider the cyclical properties of the German economy prior and after reunification in 1990 from the perspective of a real business cycle model. The model provides the framework for the selection and consistent measurement of the variables whose time series properties characterize the cycle. Simulations of the calibrated model reveal the model's potential to interpret the data. Major findings are that: i) the volatility of most aggregate time series has not changed significantly between the two time periods, ii) despite many conceptual differences between the European and the U.S. System of Accounts, the calibrated parameter values for the German economy are within the range of values usually employed in the real business cycle literature, iii) the model is closer to the data for the time period prior to reunification
Changes in neuronal CycD/Cdk4 activity affect aging, neurodegeneration, and oxidative stress.
Mitochondrial dysfunction has been implicated in human diseases, including cancer, and proposed to accelerate aging. The Drosophila Cyclin-dependent protein kinase complex cyclin D/cyclin-dependent kinase 4 (CycD/Cdk4) promotes cellular growth by stimulating mitochondrial biogenesis. Here, we examine the neurodegenerative and aging consequences of altering CycD/Cdk4 function in Drosophila. We show that pan-neuronal loss or gain of CycD/Cdk4 increases mitochondrial superoxide, oxidative stress markers, and neurodegeneration and decreases lifespan. We find that RNAi-mediated depletion of the mitochondrial transcription factor, Tfam, can abrogate CycD/Cdk4's detrimental effects on both lifespan and neurodegeneration. This indicates that CycD/Cdk4's pathological consequences are mediated through altered mitochondrial function and a concomitant increase in reactive oxygen species. In support of this, we demonstrate that CycD/Cdk4 activity levels in the brain affect the expression of a set of 'oxidative stress' genes. Our results indicate that the precise regulation of neuronal CycD/Cdk4 activity is important to limit mitochondrial reactive oxygen species production and prevent neurodegeneration
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
Industrias paleolíticas eolizadas en la región del Cabo de Peñas (Asturias)
[Resumen] En el borde costero de la región del Cabo Peñas ( Asturias ), se encuentran numerosos registros sedimentarios y prehist6ricos, particularmente del Paleolítico Inferior, que permiten una caracterización precisa entre la evolución litoral y los asentamientos humanos. En este trabajo, se estudian dos localizaciones prehistóricas de indudable interés: la punta de Cabo Peñas y El Otero ( Xagó ), donde vienen apareciendo útiles con signos evidentes de haber sido trabajados por el viento y que se encuentran asociados claramente al ambiente sedimentario. Se han sometido a análisis tipológicos y sedimentológicos, intentandose una aproximación cronológica.[Abstract] In the central and western coastal zone of the Cabo Peñas Asturias), there are several sedimentary and prehistoric records mainly from the Lower Palaeolithic allowing an accurate characterization between the littoral evolution and human establishment. In this work two interesting prehistoric sites are studied Cabo Peñas and El Otero ( Xagó ) where we met sorne eolized prehistoric industries associated to the sedimentary environment. Typologic and sedimentologic analysis were made and a chronology of the process was trie
On the Cyclicity of Regional House Prices: New Evidence for U.S. Metropolitan Statistical Areas
This paper is mainly concerned with the analysis of regional house price cycles. Based on a newly available data set consisting of the 40 largest U.S. Metropolitan Statistical Areas (MSAs), we introduce a wavelet transform based metric to study the housing cycle synchronization across MSAs. We derive several conclusions: (i) We show that regional housing cycle dissimilarities are significantly and strongly connected to geography. (ii) We show that U.S. regional housing cycles are considerably shorter compared to business cycles. (iii) By employing statistical methods, we also show that regional housing prices significantly converge after the bursting of the bubble only at higher business cycle frequencies, whereas for lower business cycle frequencies this is not the case. This is a notable result, because it directly implies that housing cycles behavior is different even at the business cycle
Relation between Brown Dwarfs and Exoplanets
One of the most debated subjects in Astronomy since the discovery of
exoplanets is how can we distinguish the most massive of such objects from
very-low mass stars like Brown Dwarfs (BDs)? We have been looking for evidences
of a difference in physical characteristics that could be related to different
formation processes. Using a new diagnostic diagram that compares the baryonic
gravitational potential (BGP) with the distances from their host stars, we have
classified a sample of 355 well-studied exoplanets according to their possible
structures. We have then compared the exoplanets to a sample of 87 confirmed
BDs, identifying a range in BGP that could be common to both objects. By
analyzing the mass-radius relations (MRR) of the exoplanets and BDs in those
different BGP ranges, we were able to distinguish different characteristic
behaviors. By comparing with models in the literature, our results suggest that
BDs and massive exoplanets might have similar structures dominated by liquid
metallic hydrogen (LMH).Comment: Poster #149 from proceeding of The 19th Cambridge Workshop on Cool
Stars, Stellar Systems, and the Sun; 06-10 June 2016, Uppsala, Swede
Nutritional disorders
Different nutritional deficiencies or toxicities may limit bean development and yield. N and P deficiencies are the most frequent, although deficiency of minor elements and Al/Mn toxicity can reduce yields considerably. Nutritional problems are usually diagnosed by soil and plant tissue analyses and the observation of symptoms produced by nutritional disorders. Optimum pH for bean production varies between 6.5 and 7.5; within these limits, the majority of the plant nutrients have their max. availability. Color illustrations are given of the symptoms of plant deficiencies and toxicities. (CIAT)Diversas deficiencias o toxicidades nutricionales pueden limitar el desarrollo del frijol y su rendimiento. Las deficiencias de N y P son las mas frecuentes, aunque las de elementos menores y la toxicidad de Al y Mn pueden reducir considerablemente los rendimientos. Los problemas nutricionales se diagnostican mediante el analisis del suelo y del tejido vegetal, y la observacion de los sintomas producidos por desordenes nutricionales. El pH optimo para producir frijol fluctua entre 6.5 y 7.5; dentro de estos limites, la mayoria de los elementos nutritivos de la planta presentan su max. disponibilidad. Se presentan ilustraciones a color de los sintomas de deficiencia o toxicidad en las plantas. (CIAT
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