1,192 research outputs found
Potential energy threshold for nano-hillock formation by impact of slow highly charged ions on a CaF(111) surface
We investigate the formation of nano-sized hillocks on the (111) surface of
CaF single crystals by impact of slow highly charged ions. Atomic force
microscopy reveals a surprisingly sharp and well-defined threshold of potential
energy carried into the collision of about 14 keV for hillock formation.
Estimates of the energy density deposited suggest that the threshold is linked
to a solid-liquid phase transition (``melting'') on the nanoscale. With
increasing potential energy, both the basal diameter and the height of the
hillocks increase. The present results reveal a remarkable similarity between
the present predominantly potential-energy driven process and track formation
by the thermal spike of swift ( GeV) heavy ions.Comment: 10 pages, 2 figure
Comparison of turbulence models for the computational fluid dynamics simulation of wind turbine wakes in the atmospheric boundary layer
An elliptic computational fluid dynamics wake model based on the actuator disk concept is used to simulate a wind turbine, approximated by a disk upon which a distribution of forces, defined as axial momentum sources, is applied on an incoming non-uniform shear flow. The rotor is supposed to be uniformly loaded with the exerted forces estimated as a function of the incident wind speed, thrust coefficient and rotor diameter. The model is assessed in terms of wind speed deficit and added turbulence intensity for different turbulence models and is validated from experimental measurements of the Sexbierum wind turbine experiment
Second-generation antipsychotics clinical pharmacy plan developed from hospital pharmacy to primary health care
The growing role of hospital pharmacists in the ambulatory care setting challenges new changes. Drug distribution to Primary/Ambulatory Healthcare needs to reformulate
a clinical pharmacy practice plan when presented with a patient having schizophrenia, according to criteria of rational drug use, equity and accessibility of the patient for sustained concentrations for several weeks indicated only for chronic therapy in patients who have trouble adhering to oral therapy that might achieve a markedly decline of positive, negative and cognitive symptoms. Therefore, these important features of long-acting injectable antipsychotics (LAIs, previously known as depot antipsychotics) need to be addressed on real-world practice. The purpose of the study is to develop drug distribution logistics for second-generation antipsychotics from Spanish Hospital Pharmacy to all Primary Health Care Sector (target population: Urban, Rural, and Homecare Support) from 2015 to 2016
From molecular to multi-asperity contacts: how roughness bridges the friction scale gap
While friction stems from the fundamental interactions between atoms at a
contact interface, its best descriptions at the macroscopic scale remain
phenomenological. The so called "rate-and-state" models, which specify the
friction response in terms of the relative sliding velocity and the "age" of
the contact interface, fail to uncover the nano-scale mechanisms governing the
macro-scale response, while models of friction at the atomic scale often
overlook how roughness can alter the friction behavior. Here we bridge this gap
between nano and macro descriptions of friction by correlating the physical
origin of macroscopic friction to the existence, due to nanometric roughness,
of contact junctions between adsorbed monolayers. Their dynamics, as we show,
emerges from molecular motion. Through coupled experimental and atomic
simulations, we highlight that transient friction overshoots its steady-state
value after the system is allowed to rest, with the friction force decaying to
a steady-state value over a distance of a few nanometers, much smaller than the
junction size, even with a root-mean-square roughness of 0.6 nm. We demonstrate
how this transient decay is intrinsically related to the evolution of the
number of cross-surface attractive physical links between adsorbed molecules on
rough surfaces. We also show that roughness is a sufficient condition for the
appearance of frictional aging. In systems that show structural aging, this
paints contact junctions as a key component in the observation of the transient
friction overshoot, and shows how infrajunction molecular motion can control
the macroscopic response
Introduction to the Special Section on Social Computing and Social Internet of Things
The papers in this special section focus on social computing and the social Internet of Things (SIoT). SIoT is a new and latest paradigm that extends Internet of Things. This provides an ideal platform for interconnected devices and objects to effectively interact across social platforms for the betterment of the community on a whole. Any Social Internet of things based system means that the data is distributed in nature and focuses on the interest of a larger group of people than a particular individual. Thus social Internet of things have a wide scope and can be used to develop a wide range of applications that involves a group of people or community working towards accomplishing a common objective such as joint ventures, office setup, co-ownerships and so on. Social Computing may be defined as the study of the collaborative behavior of a group of computer users working on some common objectives
Stability of solitons in PT-symmetric couplers
Families of analytical solutions are found for symmetric and antisymmetric
solitons in the dual-core system with the Kerr nonlinearity and PT-balanced
gain and loss. The crucial issue is stability of the solitons. A stability
region is obtained in an analytical form, and verified by simulations, for the
PT-symmetric solitons. For the antisymmetric ones, the stability border is
found in a numerical form. Moving solitons of both types collide elastically.
The two soliton species merge into one in the "supersymmetric" case, with equal
coefficients of the gain, loss and inter-core coupling. These solitons feature
a subexponential instability, which may be suppressed by periodic switching
("management").Comment: Optics Letters 2011 (in press
Diagenetic Evolution and Porosity Destruction of Turbiditic Hybrid Arenites and Siliciclastic Sandstones of Foreland Basins: Evidence from the Eocene Hecho Group, Pyrenees, Spain
International audienceThis study aims to unravel the impact of diagenetic alterations on porosity loss of foreland-basin turbiditic hybrid arenites and associated siliciclastic sandstones of the Eocene Hecho Group (south-central Pyrenees, Spain). In this succession, hybrid arenites and calclithites are extensively cemented by mesogenetic calcite cement (delta18O VPDB = â10.0 per thousand to â5.8per thousand ; Th, mode = 80° C; salinity mode = 18.8 wt% eq. NaCl), Fe-dolomite (delta18O VPDB = â8.5 per thousand to â6.3 per thousand ) and trace amounts of siderite. The extent of carbonate cementation is interpreted to be related to the amounts of extrabasinal and intrabasinal carbonate grains, which provided nuclei and sources for the precipitation and growth of carbonate cements. Other diagenetic alterations, such as pyrite and albitization, had no impact on reservoir quality. Scarce early diagenetic cements, coupled with abundant ductile carbonate and siliciclastic framework grains, have led to rapid porosity loss owing to compaction. Conversely, abundant quartz in the sandstones prevented rapid loss of porosity by mechanical compaction. Reservoir quality was affected by mesogenetic cementation by quartz overgrowths, calcite and dolomite intergranular pressure dissolution of quartz grains, and formation of fracture-filling calcite cement (delta 18O V-PDB values from â10.4 per thousand to â7.8 per thousand ; Th temperatures of circa 150° C), which are attributed to deep circulation of hot meteoric waters during extensional stages of tectonism. The results of this study illustrate that diagenetic evolution pathways of the arenites and sandstones are closely linked to the variation in detrital composition, particularly the proportion and types of extrabasinal noncarbonates, extrabasinal carbonates, and intrabasinal carbonate grains. These insights suggest that marine turbiditic hybrid arenites and calclithites of foreland basins are subjected to more rapid and extensive porosity loss owing to compaction and cementation than associated siliciclastic sandstones. Degradation of reservoir quality makes these hybrid arenites, calclithites, and sandstones suitable as tight gas reservoirs, but only if fracture porosity and permeability develop during tectonic deformation
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