As in glaciology, periglacial processes also occur in tropical regions, where altitude is the main controlling factor. Intertropical mountains that rise above the treeline ( 4000 m a.s.l.) are exposed to various surface freezing dynamics, whether permanent, seasonal, or diurnal. However, the high elevation where periglacial dynamics occur means that in situ studies are scarce and observations are temporally limited. Consequently, atmosphere-soil interactions in tropical high mountains remain poorly understood. While the formation of needle ice and frost heave are relatively common processes in temperate and cold climates at mid- and high latitudes, their origin is still mainly understood through theoretical approaches and laboratory experiments conducted under controlled conditions. As a result, studies of these phenomena in tropical mountain regions are almost nonexistent. Given the above, and considering its importance not only from a climatic perspective but also because it is associated with the prevalence of unconsolidated soils susceptible to removal by solifluction on mountain steep slopes, this research documents a specific occurrence in one of Mexico’s high mountains and provides an approach to understanding these processes from both theoretical and empirical perspectives. The study was conducted using air temperature, soil temperature at different depths, relative humidity, precipitation, and wind speed as the main variables. The results show the formation and growth of needle ice up to 7 cm in length, resulting from the availability of water in the soil and the thermal gradient within the first few centimeters of the surface, which causes the upward movement of unconsolidated soil particles.
Although studies related to periglacial dynamics in Mexico have advanced in recent years,there are still gaps in knowledge that need to be addressed to explain the various mechanisms associated with slope dynamics,which commonly occur recurrently in the high mountains of Mexico.Using both theoretical and empirical approaches,through the construction of indices of acicular ice formation potential,based on air and surface temperatures,atmospheric humidity levels,and wind speed,complemented by direct visual field observations,this study analyzes the formation of needle ice and the frost heave it causes in the upper part of the Cofre de Perote volcano.The aim is to understand how this repetitive process over time may prevent the consolidation of granular volcanic soils exposed to solifluction.The results indicate that the formation of needle ice takes place during the colder months of the year,because of the combined effects of air humidity,temperature,and wind speed,which together can give rise to ice needles ranging from a few millimeters to more than 7 cm in length.From a geomorphological perspective,the repetitive process of frost heave may be one of the factors explaining why granular soils in periglacial environments remain loose and exposed to various erosional dynamics,including fluvial,aeolian,and gravitational processes.From a climatological standpoint,the recurrent formation of acicular ice makes it possible to observe some of the effects of daily freeze-thaw cycles at the surface,which are closely associated with the gelifraction of bedrock and rock walls in the high mountains of Mexico.This study contributes to the understanding of high-mountain climatology,particularly by addressing a phenomenon that remains poorly understood within the scientific literature on tropical high-mountain environments.
Metal-organic frameworks (MOFs) are porous materials with high storage capacity and controlled release of agrochemicals, gases, nanomaterials, growth regulators, and other substances. MOFs are a new alternative for applications in plant tissue culture, such as plant health, germplasm conservation, production of metabolites, genetic improvement, and micropropagation. Furthermore, MOFs can interact with and are compatible with different liquid or semi-solid culture media, expanding their potential in the research and development of advanced plant biotechnology techniques to address future challenges and increase agricultural productivity. MOFs are a technological innovation with different applications in plant tissue culture.
Henry Oldenburg(1620-1677) fue la persona con la cual Baruch Spinoza sostuvo su más extensacorrespondencia. Teólogo proveniente de Bremen, Oldenburg fue a Londres como agente diplomático para obtener de Oliver Cromwell garantías de que, en caso de una guerra entre Inglaterra y los Países Bajos, la neutralidad de su país sería respetada. Al cabo de su misión, permaneció en Londres, donde posteriormente se integraría al círculo de Robert Boyle,del cual surgió la British Royal Society. Oldenburg fue secretario de la Royal Societydesde su oficialización en 1662 y responsable de PhilosophicalTransactionspor varios años.
El proposito del presente articulo es construir aproximaciones productivas entre la filosofia de Spinoza y algunos aspectos de la teoria de sistemas contemporanea, con especial atencion a la teoria de sistemas sociales. Para ello, exploramos inicialmente la distincion entre sustancia y modos, explicitando el caracter relativo de las configuraciones modales como parte o todo. Posteriormente, la nocion spinozista de individuo es interpretada como un sistema abierto en equilibrio dinamico y el concepto de autopoiesis es comparado al de conatus. Terminamos presentando la imaginacion como fundamento de la sociabilidad, y enfatizando el rol de los procesos epistemicos y comunicativos en la conformacion de los sistemas sociales
