2,572 research outputs found
Manufacturing process and the integration process needed to create a streamline work cell for instruction at the university level course
Internet kao najrašireniji medij današnjice mijenja način komunikacije i poslovanja između proizvođača i potrošača. Marketing u suradnji s internetom dovodi do internetskog marketinga koji koristi informacijsku tehnologiju za ostvarivanje marketinških ciljeva. Nova tehnologija povećava uspješnost širenja informacija i mijenja suštinu marketinga
Whose streets? Roadway protests and weaponised automobility
The article examines the role of automobility in US-based anti-racism demonstrations and counter-demonstrations. We contrast the spatial strategies of highway occupations by racial justice activists, with so-called “weaponised car” attacks by the American far right. Analysing online memes and anti-protest legislation, the article explores under-acknowledged links between “automobile supremacy”—the structure of motorists' privilege as embedded in law, the built environment and the popular imaginary—and the patterns of racial stratification often termed “white supremacy”. We document three ways in which automobility has been enlisted as means of violence against protestors and against wider Black communities in the US: through the use of vehicles, right-of-way conventions, and roadways as weapons. The article demonstrates how the imperative to make way for the motorist has long provided cover for racial injustice.Publisher PDFPeer reviewe
Patterned probes for high precision 4D-STEM bragg measurements.
Nanoscale strain mapping by four-dimensional scanning transmission electron microscopy (4D-STEM) relies on determining the precise locations of Bragg-scattered electrons in a sequence of diffraction patterns, a task which is complicated by dynamical scattering, inelastic scattering, and shot noise. These features hinder accurate automated computational detection and position measurement of the diffracted disks, limiting the precision of measurements of local deformation. Here, we investigate the use of patterned probes to improve the precision of strain mapping. We imprint a "bullseye" pattern onto the probe, by using a binary mask in the probe-forming aperture, to improve the robustness of the peak finding algorithm to intensity modulations inside the diffracted disks. We show that this imprinting leads to substantially improved strain-mapping precision at the expense of a slight decrease in spatial resolution. In experiments on an unstrained silicon reference sample, we observe an improvement in strain measurement precision from 2.7% of the reciprocal lattice vectors with standard probes to 0.3% using bullseye probes for a thin sample, and an improvement from 4.7% to 0.8% for a thick sample. We also use multislice simulations to explore how sample thickness and electron dose limit the attainable accuracy and precision for 4D-STEM strain measurements
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An Analysis of the Efficacy and Comparative Costs of Using Flow Devices to Resolve Conflicts with North American Beavers Along Roadways in the Coastal Plain of Virginia
Road damage caused by beavers is a costly problem for transportation departments in the U.S. Population control and dam destruction are the most widely used methods to reduce road damage caused by beavers, but the benefits of such measures in some situations are often very short-term. At chronic damage sites, it may be more effective and cost-beneficial to use flow devices to protect road structures and critical areas adjacent to roads. To determine the potential benefits of using flow devices at chronic beaver damage sites, from June 2004 to March 2006 we installed 40 flow devices at 21 sites identified by transportation department personnel as chronic damage sites in Virginia’s Coastal Plain. Following installations, study sites were monitored to determine flow device performance and any required maintenance and repairs. Between March 2006 and August 2007, transportation department personnel were surveyed to collect data on flow device efficacy and comparative costs. As of August 2007, transportation department personnel indicated that 39 of the 40 flow devices installed were functioning properly and meeting management objectives. The costs to install and maintain flow devices were significantly lower than preventative road maintenance, damage repairs, and/or population control costs at these sites prior to flow device installations. Prior to flow device installations, the transportation department saved 1.00 spent per year on preventative maintenance, road repairs, and beaver population control. Following flow device installations, the transportation department saved 1.00 spent to install, monitor, and maintain flow devices. Given the demonstrated low costs to build and maintain flow devices, transportation agencies may substantially reduce road maintenance costs by installing and maintaining flow devices at chronic beaver damage sites
Anomalous relaxation kinetics of biological lattice-ligand binding models
We discuss theoretical models for the cooperative binding dynamics of ligands
to substrates, such as dimeric motor proteins to microtubules or more extended
macromolecules like tropomyosin to actin filaments. We study the effects of
steric constraints, size of ligands, binding rates and interaction between
neighboring proteins on the binding dynamics and binding stoichiometry.
Starting from an empty lattice the binding dynamics goes, quite generally,
through several stages. The first stage represents fast initial binding closely
resembling the physics of random sequential adsorption processes. Typically
this initial process leaves the system in a metastable locked state with many
small gaps between blocks of bound molecules. In a second stage the gaps
annihilate slowly as the ligands detach and reattach. This results in an
algebraic decay of the gap concentration and interesting scaling behavior. Upon
identifying the gaps with particles we show that the dynamics in this regime
can be explained by mapping it onto various reaction-diffusion models. The
final approach to equilibrium shows some interesting dynamic scaling
properties. We also discuss the effect of cooperativity on the equilibrium
stoichiometry, and their consequences for the interpretation of biochemical and
image reconstruction results.Comment: REVTeX, 20 pages, 17 figures; review, to appear in Chemical Physics;
v2: minor correction
Commensurate Stripes and Phase Coherence in Manganites Revealed with Cryogenic Scanning Transmission Electron Microscopy
Incommensurate charge order in hole-doped oxides is intertwined with exotic
phenomena such as colossal magnetoresistance, high-temperature
superconductivity, and electronic nematicity. Here, we map at atomic resolution
the nature of incommensurate order in a manganite using scanning transmission
electron microscopy at room temperature and cryogenic temperature ( 93K).
In diffraction, the ordering wavevector changes upon cooling, a behavior
typically associated with incommensurate order. However, using real space
measurements, we discover that the underlying ordered state is
lattice-commensurate at both temperatures. The cations undergo picometer-scale
(6-11 pm) transverse displacements, which suggests that charge-lattice
coupling is strong and hence favors lattice-locked modulations. We further
unearth phase inhomogeneity in the periodic lattice displacements at room
temperature, and emergent phase coherence at 93K. Such local phase variations
not only govern the long range correlations of the charge-ordered state, but
also results in apparent shifts in the ordering wavevector. These
atomically-resolved observations underscore the importance of lattice coupling
and provide a microscopic explanation for putative "incommensurate" order in
hole-doped oxides
Bending and Breaking of Stripes in a Charge-Ordered Manganite
In complex electronic materials, coupling between electrons and the atomic
lattice gives rise to remarkable phenomena, including colossal
magnetoresistance and metal-insulator transitions. Charge-ordered phases are a
prototypical manifestation of charge-lattice coupling, in which the atomic
lattice undergoes periodic lattice displacements (PLDs). Here we directly map
the picometer scale PLDs at individual atomic columns in the room temperature
charge-ordered manganite BiSrCaMnO using
aberration corrected scanning transmission electron microscopy (STEM). We
measure transverse, displacive lattice modulations of the cations, distinct
from existing manganite charge-order models. We reveal locally unidirectional
striped PLD domains as small as 5 nm, despite apparent bidirectionality
over larger length scales. Further, we observe a direct link between disorder
in one lattice modulation, in the form of dislocations and shear deformations,
and nascent order in the perpendicular modulation. By examining the defects and
symmetries of PLDs near the charge-ordering phase transition, we directly
visualize the local competition underpinning spatial heterogeneity in a complex
oxide.Comment: Main text: 20 pages, 4 figures. Supplemental Information: 27 pages,
14 figure
Icy futures:carving the northern sea route
The research examines intersections between globalisation and climate change in the (re)emergence of a 'Northern Sea Route' through the Russian Arctic, which some speculate could soon rival or replace the Suez Canal as major global trade artery. The research explores shifts in the contemporary shipping system, a relatively underexplored area of mobilities research, examining the affordances and risks posed to shipping and resource extraction activities by melting Arctic sea-ice, as sections of the maritime Arctic become increasingly integrated into global circuits. The research examines actual and potential developments surrounding the Northern Sea Route (NSR) in the Russian Arctic, examining the ways geopolitics, geoeconomics and geophysical processes collide in the ‘Anthropocene Arctic’
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