187 research outputs found
EMC aspects of a lightning surge generator and its measuring system
Adequate EMC techniques can make digital measurements in high voltage engineering as straightforward as they are in low-voltage electronics. The authors demonstrate that for the case of a 2.4 MV lightning surge generator. Interference currents in grounding structures and coaxial cables have been measured. With an EMC cabinet and a differentiating/integrating measuring system, the effects of these interference currents can be suppressed far enough to obtain clean results of the high voltage waveform on a digital oscilloscop
Tunable Depletion Potentials Driven By Shape Variation Of Surfactant Micelles
Depletion interaction potentials between micron-sized colloidal particles are induced by nanometer-scale surfactant micelles composed of hexaethylene glycol monododecyl ether (C12E6), and they are measured by video microscopy. The strength and range of the depletion interaction is revealed to arise from variations in shape anisotropy of the surfactant micelles. This shape anisotropy increases with increasing sample temperature. By fitting the colloidal interaction potentials to theoretical models, we extract micelle length and shape anisotropy as a function of temperature. This work introduces shape anisotropy tuning as a means to control interparticle interactions in colloidal suspensions, and it shows how the interparticle depletion potentials of micron-scale objects can be employed to probe the shape and size of surrounding macromolecules at the nanoscale
The emergence of international food safety standards and guidelines: understanding the current landscape through a historical approach
Following the Second World War, the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) teamed up to construct an International Codex Alimentarius (or 'food code') which emerged in 1963. The Codex Committee on Food Hygiene (CCFH) was charged with the task of developing microbial hygiene standards, although it found itself embroiled in debate with the WHO over the nature these standards should take. The WHO was increasingly relying upon the input of biometricians and especially the International Commission on Microbial Specifications for Foods (ICMSF) which had developed statistical sampling plans for determining the microbial counts in the final end products. The CCFH, however, was initially more focused on a qualitative approach which looked at the entire food production system and developed codes of practice as well as more descriptive end-product specifications which the WHO argued were 'not scientifically correct'. Drawing upon historical archival material (correspondence and reports) from the WHO and FAO, this article examines this debate over microbial hygiene standards and suggests that there are many lessons from history which could shed light upon current debates and efforts in international food safety management systems and approaches
State Transition Algorithm
In terms of the concepts of state and state transition, a new heuristic
random search algorithm named state transition algorithm is proposed. For
continuous function optimization problems, four special transformation
operators called rotation, translation, expansion and axesion are designed.
Adjusting measures of the transformations are mainly studied to keep the
balance of exploration and exploitation. Convergence analysis is also discussed
about the algorithm based on random search theory. In the meanwhile, to
strengthen the search ability in high dimensional space, communication strategy
is introduced into the basic algorithm and intermittent exchange is presented
to prevent premature convergence. Finally, experiments are carried out for the
algorithms. With 10 common benchmark unconstrained continuous functions used to
test the performance, the results show that state transition algorithms are
promising algorithms due to their good global search capability and convergence
property when compared with some popular algorithms.Comment: 18 pages, 28 figure
Melting Pot 2.0
Multi-agent artificial intelligence research promises a path to develop
intelligent technologies that are more human-like and more human-compatible
than those produced by "solipsistic" approaches, which do not consider
interactions between agents. Melting Pot is a research tool developed to
facilitate work on multi-agent artificial intelligence, and provides an
evaluation protocol that measures generalization to novel social partners in a
set of canonical test scenarios. Each scenario pairs a physical environment (a
"substrate") with a reference set of co-players (a "background population"), to
create a social situation with substantial interdependence between the
individuals involved. For instance, some scenarios were inspired by
institutional-economics-based accounts of natural resource management and
public-good-provision dilemmas. Others were inspired by considerations from
evolutionary biology, game theory, and artificial life. Melting Pot aims to
cover a maximally diverse set of interdependencies and incentives. It includes
the commonly-studied extreme cases of perfectly-competitive (zero-sum)
motivations and perfectly-cooperative (shared-reward) motivations, but does not
stop with them. As in real-life, a clear majority of scenarios in Melting Pot
have mixed incentives. They are neither purely competitive nor purely
cooperative and thus demand successful agents be able to navigate the resulting
ambiguity. Here we describe Melting Pot 2.0, which revises and expands on
Melting Pot. We also introduce support for scenarios with asymmetric roles, and
explain how to integrate them into the evaluation protocol. This report also
contains: (1) details of all substrates and scenarios; (2) a complete
description of all baseline algorithms and results. Our intention is for it to
serve as a reference for researchers using Melting Pot 2.0.Comment: 59 pages, 54 figures. arXiv admin note: text overlap with
arXiv:2107.0685
Induction of Antibodies in Rhesus Macaques That Recognize a Fusion-Intermediate Conformation of HIV-1 gp41
A component to the problem of inducing broad neutralizing HIV-1 gp41 membrane proximal external region (MPER) antibodies is the need to focus the antibody response to the transiently exposed MPER pre-hairpin intermediate neutralization epitope. Here we describe a HIV-1 envelope (Env) gp140 oligomer prime followed by MPER peptide-liposomes boost strategy for eliciting serum antibody responses in rhesus macaques that bind to a gp41 fusion intermediate protein. This Env-liposome immunization strategy induced antibodies to the 2F5 neutralizing epitope 664DKW residues, and these antibodies preferentially bound to a gp41 fusion intermediate construct as well as to MPER scaffolds stabilized in the 2F5-bound conformation. However, no serum lipid binding activity was observed nor was serum neutralizing activity for HIV-1 pseudoviruses present. Nonetheless, the Env-liposome prime-boost immunization strategy induced antibodies that recognized a gp41 fusion intermediate protein and was successful in focusing the antibody response to the desired epitope
Articular cartilage and changes in Arthritis: Cell biology of osteoarthritis
The reaction patterns of chondrocytes in osteoarthritis can be summarized in five categories: (1) proliferation and cell death (apoptosis); changes in (2) synthetic activity and (3) degradation; (4) phenotypic modulation of the articular chondrocytes; and (5) formation of osteophytes. In osteoarthritis, the primary responses are reinitiation of synthesis of cartilage macromolecules, the initiation of synthesis of types IIA and III procollagens as markers of a more primitive phenotype, and synthesis of active proteolytic enzymes. Reversion to a fibroblast-like phenotype, known as 'dedifferentiation', does not appear to be an important component. Proliferation plays a role in forming characteristic chondrocyte clusters near the surface, while apoptosis probably occurs primarily in the calcified cartilage
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