Dynamic Phenotypic Clustering in Noisy Ecosystems

In natural ecosystems, hundreds of species typically share the same environment and are connected by a dense network of interactions such as predation or competition for resources. Much is known about how fixed ecological niches can determine species abundances in such systems, but far less attention has been paid to patterns of abundances in randomly varying environments. Here, we study this question in a simple model of competition between many species in a patchy ecosystem with randomly fluctuating environmental conditions. Paradoxically, we find that introducing noise can actually induce ordered patterns of abundance-fluctuations, leading to a distinct periodic variation in the correlations between species as a function of the phenotypic distance between them; here, difference in growth rate. This is further accompanied by the formation of discrete, dynamic clusters of abundant species along this otherwise continuous phenotypic axis. These ordered patterns depend on the collective behavior of many species; they disappear when only individual or pairs of species are considered in isolation. We show that they arise from a balance between the tendency of shared environmental noise to synchronize species abundances and the tendency for competition among species to make them fluctuate out of step. Our results demonstrate that in highly interconnected ecosystems, noise can act as an ordering force, dynamically generating ecological patterns even in environments lacking explicit niches

Potential cellular and biochemical mechanisms of exercise and physical activity on the ageing process

Exercise in young adults has been consistently shown to improve various aspects of physiological and psychological health but we are now realising the potential benefits of exercise with advancing age. Specifically, exercise improves cardiovascular, musculoskeletal, and metabolic health through reductions in oxidative stress, chronic low-grade inflammation and modulating cellular processes within a variety of tissues. In this this chapter we will discuss the effects of acute and chronic exercise on these processes and conditions in an ageing population, and how physical activity affects our vasculature, skeletal muscle function, our immune system, and cardiometabolic risk in older adults

Three Proterozoic orogenic episodes and an intervening exhumation event in the Black Canyon of the Gunnison region, Colorado

U/Pb zircon/titanite geochronology, in situ monazite geochronology, and 40Ar/39Ar thermochronology provide an unusually complete data set for reconstructing the tectonic history of Proterozoic rocks exposed in the Black Canyon, Gunnison, Colorado. These new geochronologic data record three protracted orogenic episodes and an exhumation event between orogenic pulses: (1) Yavapai orogeny (1741-1689 Ma), (2) exhumation marked by an angular unconformity beneath post-Yavapai, pre-Mazatzal quartzites, (3) Mazatzal orogeny (postquartzite deposition), and (4) 1434-1403 Ma intracratonic tectonism. Supracrustal rocks of the Black Canyon succession were deposited or crystallized at or prior to 1741 ± 4 Ma and were intruded by the 1713 ± 2 Ma Pitts Meadow granodiorite. Paleoproterozoic high-temperature metamorphism (\u3e650°C) associated with the Yavapai orogeny occurred between 1741 and 1690 Ma. Deposition of interorogenic quartzites took place after ∼1700 Ma. The Vernal Mesa monzogranite was emplaced at 1434 ± 2 Ma followed by metamorphism (∼600° ± 50°C and ∼3 ± 1 kbar) at ≤ 1403 ± 23 Ma. 40Ar/39Ar thermochronology records Mesoproterozoic middle crustal temperatures of 350°-500°C, with the highest temperatures occurring near the Vernal Mesa monzogranite and the NE-striking Black Canyon shear zone. The area cooled through 350°C by ∼1385 Ma but variably cooled through 300°C from 1370 to 1100 Ma, suggesting long-term residence of rocks above the 250°C isotherm at ∼10 km crustal depths. When these results are combined with geologic data to construct generalized pressure/temperature/time/deformation paths (PTtD), a new template for the evolution of Proterozoic rocks of southwestern Colorado and the southwestern United states emerges

Efeitos da atividade física na densidade mineral óssea e na remodelação do tecido ósseo Efectos de la actividad física en la densidad mineral ósea y en la remodelacion del tejido óseo Effects of the physical activity on the bone mineral density and bone remodelation

Este artigo revisa os efeitos de diferentes modalidades esportivas e do treinamento de força na remodelação óssea e discutir as possíveis relações da densidade mineral óssea (DMO) com a força muscular e a composição corporal. Numerosos estudos indicam que a atividade física de alto impacto, ou que exija alta produção de força, pode ter um efeito benéfico na DMO, devido à deformação desse tecido, ocorrida durante a atividade. Alguns autores têm avaliado os efeitos do treinamento físico em alguns marcadores bioquímicos da remodelação óssea, já que a variação das concentrações desses marcadores pode indicar um estado de formação ou reabsorção óssea. Entretanto, a inconsistência dos resultados encontrados sugere que a análise dos efeitos da atividade física na remodelação óssea, através desses marcadores, deve ser mais investigada. Existem muitas discrepâncias a respeito da relação entre a DMO com a força muscular e a composição corporal, principalmente na determinação de qual desses fatores está mais associado com a DMO. A determinação de qual o tipo de atividade física seja ideal para aumentar o pico de massa óssea na adolescência, ou mesmo mantê-la após a idade adulta, é muito importante para a prevenção e o possível tratamento da osteoporose.<br>Este artículo busca revisar los efectos de modalidades deportivas diferentes y del entrenamiento de fuerza en la remodelación del hueso y discutir las posibles relaciones entre la densidad mineral del hueso (DMO) con la fuerza muscular y la composición corporal. Los numerosos estudios indican que la actividad física de alto impacto o que exige producción alta de fuerza, pueden tener un efecto beneficioso en la DMO, debido a la deformación que ese tejido, pasa durante la actividad física. Algunos autores han estado evaluando los efectos de la educación física en algunos marcadores bioquímicos de la remodelación del hueso, desde la variación de las concentraciones de esos marcadores que puedan indicar un estado de la formación o reabsorción del hueso. Sin embargo, la inconsistencia de los resultados encontrados, sugiere que el análisis de los efectos de la actividad física en el remodelación del hueso, a través de esos marcadores, debe investigarse más. Muchas diferencias existen con respecto a la relación entre la DMO con la fuerza muscular y la composición corporal, principalmente en la determinación de cual de esos factores está más asociada con la DMO. La determinación de que tipo de actividad física es ideal para aumentar el pico de masa del hueso en la adolescencia, o incluso mantenerla después de la edad adulta, es muy importante para la prevención y el posible tratamiento de la osteoporosis.<br>The purpose of this article is to make a review on different sportive modalities and the power training on the bone remodeling, and to discuss the possible relationship of the bone mineral density (BMD) to the muscular power and body composition. Several studies indicate that the high impact physical activity or physical activities demanding a high power production may have a benefic effect on the BMD due to the deformation that occurs in such tissue during the activity. Some authors have been assessing the effects of the physical training on some biochemical markers of the bone remodeling, since the variation on the concentrations of these markers might indicate a bone turnover or reabsorption state. Nevertheless, the inconsistency of the results found suggests that the analysis of the effects of the physical activity on the bone remodeling through these markers must be further investigated. There are many discrepancies as to the relationship of the BMD to the muscular power and body composition, mainly to determine what factors are most associated to the BMD. The determination of what type of physical activity is the ideal to increase the bone mass peak during the adolescence or even aiming to keep it later in the adult years is quite important in order to prevent and possibly treat the osteoporosis