Pulsations in M dwarf stars

We present the results of the first theoretical non-radial non-adiabatic pulsational study of M dwarf stellar models with masses in the range 0.1 to 0.5M_solar. We find the fundamental radial mode to be unstable due to an \epsilon mechanism caused by deuterium (D-) burning for the young 0.1 and 0.2M_solar models, by non-equilibrium He^3 burning for the 0.2 and 0.25M_solar models of 10^4Myr, and by a flux blocking mechanism for the partially convective 0.4 and 0.5M_solar models once they reach the age of 500Myr. The periods of the overstable modes excited by the D-burning are in the range 4.2 to 5.2h for the 0.1M_solar models and is of order 8.4h for the 0.2M_solar models. The periods of the modes excited by He^3 burning and flux blocking are in the range 23 to 40min. The more massive and oldest models are more promising for the observational detection of pulsations, as their ratio of instability e-folding time to age is more favourable.Comment: 5 pages, 4 figures, 2 tables. Accepted for publication in MNRAS Letters on 2011 October 11 Version 2 is the accepted manuscript with changes in boldfac

Empirical analysis of corporate credit lines

Since bank credit lines are a major source of corporate funding, we examine the determinants of credit line usage with a comprehensive database of Spanish corporate credit lines. A line’s default status is a key factor driving its usage, which increases as a firm’s financial condition worsens. Line usage decreases by roughly 10% for each year of its life. Lender characteristics, such as the number and length of a firm’s banking relationships, are found to affect a firm’s usage decisions, and credit line usage is found to be inversely related to macroeconomic condition

How does competition impact bank risk-taking?

A common assumption in the academic literature is that franchise value plays a key role in limiting bank risk-taking. As market power is the primary source of franchise value, reduced competition in banking markets has been seen as promoting banking stability. We test this hypothesis using data for the Spanish banking system. We find that standard measures of market concentration do not affect bank risk-taking. However, we find a negative relationship between market power measured using Lerner indexes based on bank-specific interest rates and bank risk. Our results support the franchise value paradig

On the classification and properties of noncommutative duplicates

We give an explicit description of the set of all factorization structures, or twisting maps, existing between the algebras k^2 and k^2, and classify the resulting algebras up to isomorphism. In the process we relate several different approaches formerly taken to deal with this problem, filling a gap that appeared in a recent paper by Cibils. We also provide a counterexample to a result concerning the Hochschild (co)homology appeared in a paper by J.A. Guccione and J.J. Guccione.Comment: 11 pages, no figure

Desarrollo de Web Services en NodeJS para la red de sensores inalámbrica

Dentro del presente reporte PAP se describe el proceso que se llevó a cabo a lo largo del semestre primavera 2020 referente al desarrollo de los webservices enfocados en el lado del servidor (backend). Así mismo, se describen sus finalidades, funcionalidades, implementaciones y tecnologías utilizadas. Estos webservices reciben información de monitoreo ambiental e información interna de los nodos que se encuentran tanto en el bosque de la primavera, como dentro de las instalaciones del ITESO. Almacena dicha información en una base que puede ser consultada con finalidades de análisis de datos vía web por medio de request HTTP al servidor alocado en cPanel.ITESO, A.C

Acoplamiento entre las comunidades planctónicas de un lago amazónico de aguas claras (lago Boa, Colombia)

Las comunidades planctónicas de un lago están relacionadas entre sí de diversas maneras. Para los lagos amazónicos colombianos poco es lo que se conoce sobre este acoplamiento. Se realizaron siete visitas al lago Boa (Caquetá Medio) desde mayo de 1999 a mayo de 2000, durante las cuales se tomaron muestras de bacterioplancton, fitoplancton, nanozooplancton (protozoos) y rotíferos y crustáceos (mesozooplancton) para conocer sus variaciones y sus relaciones numéricas a lo largo del ciclo hidrológico. Los promedios de abundancias de individuos por litro fluctuaron entre 4.1 · 109 a 1.4 · 1010 bacterias, 5.5 · 103 a 6.4 · 106 microalgas, 2.2 · 104 a 1.1 · 105 protozoos nanoplanctónicos y 8.1 a 240 organismos mesozooplanctónicos (rotíferos y crustáceos). Todas las comunidades tuvieron mayores abundancias en el periodo de aguas bajas, cuando el lago se desconectó del río Metá. El fitoplancton fue muy diverso y poco abundante; los grupos dominantes fueron las clorofitas, dinofitas y cianobacterias. El mesozooplancton fue escaso y estuvo compuesto principalmente por rotíferos. Dentro de los protozoos nanoplanctónicos predominaron los ciliados. Se halló una asociación estadística significativa entre las abundancias totales del fitoplancton y del bacterioplancton (p = 0.0001), lo cual sugiere algún grado de interdependencia de las dos comunidades. Durante los meses de inundación la fuerza física del pulso hidrológico parece causar que las comunidades funcionen con mayor autonomía, ya que en esta época el lago Boa se comporta como un verdadero sistema lótico.Planktonic communities of a lake are related in several forms. For Colombian Amazon lakes little is known about this coupling. Seven surveys in the Boa Lake (Middle Caquetá) were made between May of 1999 and May of 2000 to take samples of bacterioplankton, phytoplankton, nanozooplankton (protozoa) and rotifers and crustaceans (mesozooplankton), to study their variations and numerical relationships throughout the hydrological cycle. Average densities per liter were 4.1 · 109 a 1.4 · 1010 bacteria,5.5 · 103 a 6.4 · 106 phytoplankontes, 2.2 · 104 a 1.1 · 105 nanoplanktonic protozoa and 8.1 to 240 mesozooplanktontes (rotifers and crustaceans). All the communities had higher abundances in the low water period, when the lake was disconnected from the Met'a River. Phytoplankton was very diverse and scarce, but dominant groups were Chlorophyta, Dinophyta, and Cyanobacteria. Mesozooplankton was scarce and with low diversity, with rotifers as the most important group. Ciliates were predominant within nanoplanktonic protozoa. There was a significant statistical relationship between phytoplankton and bacterioplankton total densities (p = 0.0001), which suggesst some level of interdependence among these planktonic communities. During the flood months, the physical force of the hydrologic pulse seems to cause communities to become more autonomous, because at this time the Boa Lake acts more like a lotic system

Thermodynamic modelling of metamorphic processes: state of the art in pseudosection approach

Understanding global-scale orogenic processes related to supercontinents, and their relationship to the secular evolution of the Earth's lithosphere, represent important challenges for Earth scientists today. The record of these processes is preserved in the microstructures, mineral assemblages and mineral compositions of lithospheric rocks exhumed to the Earth's surface. Given a well-characterized microstructural evolution, thermodynamic modelling is the key to quantifying changes in pressure and temperature, with the rate of these changes being provided by rock-forming and accessory mineral-based geochronology. Thus, metamorphic rocks provide Pressure–Temperature–time–deformation (P–T–t–d) data that help to parameterize orogenic processes