Albedo reduction by absorbing aerosols over China

Long-term observations with satellites show that absorbing aerosols have reduced the local planetary albedo (LPA) over China during the recent decade. While the reduction of air pollution was leading to an LPA decrease in Europe, an increase of pollution in China also lowered the LPA. The strong absorption in clouds is accompanied by a cloud lifetime effect over the Red Basin and surrounding areas in southern Chin

Impact of ship emissions on cloud properties over coastal areas

Although land based emissions in Europe are decreasing, ship emissions continue to grow. The main emissions from ships can modulate cloud properties of coastal areas and are of direct relevance to the earth radiation budget. In this context, satellite data from AVHRR onboard NOAA-14 are evaluated for six years (1997–02) in order to assess impact of ship emissions on cloud properties over coastal areas. Study area was chosen in such a way that it includes the English Channel and top three polluting harbours in Europe. Results present first evidence of possible impact of ship emissions on both cloud albedo and cloud top temperature over coastal areas using long-term satellite measurements. Increase in cloud albedo (with corresponding decrease in cloud top temperature) and higher variability are observed over coastal areas. This effect is more pronounced for areas over and around harbours and the English Channel. It also confirms indirect aerosol effects

Mesopredator Release by an Emergent Superpredator: A Natural Experiment of Predation in a Three Level Guild

Chakarov N, Krüger O. Mesopredator Release by an Emergent Superpredator: A Natural Experiment of Predation in a Three Level Guild. PLoS ONE. 2010;5(12): e15229.Background: Intraguild predation (IGP) is widespread but it is often neglected that guilds commonly include many layers of dominance within. This could obscure the effects of IGP making unclear whether the intermediate or the bottom mesopredator will bear higher costs from the emergence of a new top predator. Methodology/Principal Findings: In one of the most extensive datasets of avian IGP, we analyse the impact of recolonization of a superpredator, the eagle owl Bubo bubo on breeding success, territorial dynamics and population densities of two mesopredators, the northern goshawk Accipiter gentilis and its IG prey, the common buzzard Buteo buteo. The data covers more than two decades and encompass three adjacent plots. Eagle owls only recolonized the central plot during the second decade, thereby providing a natural experiment. Both species showed a decrease in standardized reproductive success and an increase in brood failure within 1.5 km of the superpredator. During the second decade, territory dynamics of goshawks was significantly higher in the central plot compared to both other plots. No such pattern existed in buzzards. Goshawk density in the second decade decreased in the central plot, while it increased in both other plots. Buzzard density in the second decade rapidly increased in the north, remained unchanged in the south and increased moderately in the center in a probable case of mesopredator release. Conclusions/Significance: Our study finds support for top-down control on the intermediate mesopredator and both top-down and bottom-up control of the bottom mesopredator. In the face of considerable costs of IGP, both species probably compete to breed in predator-free refugia, which get mostly occupied by the dominant raptor. Therefore for mesopredators the outcome of IGP might depend directly on the number of dominance levels which supersede them

Inelastic H and D atom scattering from Au(111) as benchmark for theory.

Efficient transfer of translational energy to electron-hole pair excitation involving multiple collisions dominates H atom collisions with metal surfaces. For this reason, H atom interaction with metal surfaces cannot be modeled within the commonly used Born-Oppenheimer approximation (BOA). This fact makes H atom scattering from metal surfaces an ideal model system for dynamics that go beyond the BOA. We chose the H/Au(111) system as a model system to obtain a detailed dataset that can serve as a benchmark for theoretical models developed for describing electronically nonadiabatic processes at metal surfaces. Therefore, we investigate the influence of various experimental parameters on the energy loss in detail including isotopic variant, incidence translational energy, incidence polar and azimuthal angles, and outgoing scattering angles

Compressed vessels bias red blood cell partitioning at bifurcations in a hematocrit-dependent manner:implications in tumor blood flow

The tumor microenvironment is abnormal and associated with tumor tissue hypoxia, immunosuppression, and poor response to treatment. One important abnormality present in tumors is vessel compression. Vessel decompression has been shown to increase survival rates in animal models via enhanced and more homogeneous oxygenation. However, our knowledge of the biophysical mechanisms linking tumor decompression to improved tumor oxygenation is limited. In this study, we propose a computational model to investigate the impact of vessel compression on red blood cell (RBC) dynamics in tumor vascular networks. Our results demonstrate that vessel compression can alter RBC partitioning at bifurcations in a hematocrit-dependent and flow rate–independent manner. We identify RBC focusing due to cross-streamline migration as the mechanism responsible and characterize the spatiotemporal recovery dynamics controlling downstream partitioning. Based on this knowledge, we formulate a reduced-order model that will help future research to elucidate how these effects propagate at a whole vascular network level. These findings contribute to the mechanistic understanding of hemodilution in tumor vascular networks and oxygen homogenization following pharmacological solid tumor decompression

Soil pore distribution as affected by cattle trampling under no-till and reduced-till systems

Soil pore size affects soil air and water dynamics, and thus influence crop productivity. The aim of this study was to evaluate the impact of reduced-tillage (RT) and no-tillage (NT) systems on soil pore distribution under animal grazing. The soil was sampled at 0-5, 5-10, 10-15 and 15-20 cm depths before and after animal grazing. Bulk density, total porosity and the volume of three pore sizes (macropores, mesopores and micropores) were determined. Differences in total porosity between both tillage systems were statistically significant (P<0.01) in the top 10 cm layer before grazing. Lower total porosity in NT could be related to the effect of previous years’grazing. In RT, disk operations before planting the oat (Avena sativa) crop increased porosity values in the tilled zone at 0-10 cm and decreased them at depths below 10 cm. Macroporosity accounted for 32 (RT) and 20% (NT) of the total porosity in the soil surface, and decreased to 17 (RT) and 17% (NT) in deeper layers. Cattle trampling had a more pronounced effect under RT as compared with NT. Tillage operations increased macroporosity, which had been reduced by cattle trampling. Bulk density and total porosity were adversely affected below 15 cm depth.Los diferentes tamaños de poros modifican la dinámica del aire y agua edáfica, influyendo sobre la productividad de los cultivos. El objetivo de este estudio fue evaluar el efecto de la labranza reducida (RT) y la siembra directa (NT) sobre los cambios en la distribución de los diferentes tamaños de poros en suelos con pastoreo directo. Se tomaron muestras a 0-5, 5-10, 10-15 y 15- 20 cm antes y después del pastoreo con bovinos. Se determinó la densidad aparente, la porosidad total y el volumen ocupado por tres tamaños de poros (macroporos, mesoporos y microporos). Las diferencias en la porosidad total entre sistemas de labranza fueron estadísticas (P<0,01) en los 10 cm superficiales. La menor porosidad total en NT podría reflejar el efecto de los años previos de pastoreo. En RT, el laboreo con disco previo a la siembra de la avena (Avena sativa) incrementó la porosidad total en los 10 cm superficiales y la disminuyó en los 10-20 cm. La macroporosidad representó el 32 (RT) y 20% (NT) de la porosidad total, disminuyendo al 17 (RT) y 17% (NT) en profundidad. El pastoreo animal produjo una reducción más importante del espacio poroso en RT que en NT. El laboreo incrementó la macroporosidad, la que fue reducida durante el pastoreo animal. La densidad aparente y la porosidad total fueron adversamente afectadas por debajo de los 15 cm