2,428 research outputs found
A Methodology to Engineer and Validate Dynamic Multi-level Multi-agent Based Simulations
This article proposes a methodology to model and simulate complex systems,
based on IRM4MLS, a generic agent-based meta-model able to deal with
multi-level systems. This methodology permits the engineering of dynamic
multi-level agent-based models, to represent complex systems over several
scales and domains of interest. Its goal is to simulate a phenomenon using
dynamically the lightest representation to save computer resources without loss
of information. This methodology is based on two mechanisms: (1) the activation
or deactivation of agents representing different domain parts of the same
phenomenon and (2) the aggregation or disaggregation of agents representing the
same phenomenon at different scales.Comment: Presented at 3th International Workshop on Multi-Agent Based
Simulation, Valencia, Spain, 5th June 201
Static and vibration analysis of isotropic and functionally graded sandwich plates using an edge-based MITC3 finite elements
Static and vibration analysis of isotropic and functionally graded sandwich plates using a higher-order shear deformation theory is presented in this paper. Lagrangian functional is used to derive the equations of motion. The mixed interpolation of tensorial components (MITC) approach and edge-based-strain technique is used to solve problems. A MITC3 three-node triangle element with 7 degree-of-freedoms per nodes that only requires the C0-type continuity is developed. Numerical results for isotropic and functionally graded sandwich plates with different boundary conditions are proposed to validate the developed theory and to investigate effects of material distribution, side-to-thickness ratio, thickness ratio of layers and boundary conditions on the deflection, stresses and natural frequencies of the plates
The genetic diversity and evolutionary history of hepatitis C virus in Vietnam
AbstractVietnam has a unique history in association with foreign countries, which may have resulted in multiple introductions of the alien HCV strains to mix with those indigenous ones. In this study, we characterized the HCV sequences in Core-E1 and NS5B regions from 236 Vietnamese individuals. We identified multiple HCV lineages; 6a, 6e, 6h, 6k, 6l, 6o, 6p, and two novel variants may represent the indigenous strains; 1a was probably introduced from the US; 1b and 2a possibly originated in East Asia; while 2i, 2j, and 2m were likely brought by French explorers. We inferred the evolutionary history for four major subtypes: 1a, 1b, 6a, and 6e. The obtained Bayesian Skyline Plots (BSPs) consistently showed the rapid HCV population growth from 1955 to 1963 until 1984 or after, corresponding to the era of the Vietnam War. We also estimated HCV growth rates and reconstructed phylogeographic trees for comparing subtypes 1a, 1b, and HCV-2
Vitrification of a monatomic 2D simple liquid
A monatomic simple liquid in two dimensions, where atoms interact
isotropically through the Lennard-Jones-Gauss potential [M. Engel and H.-R.
Trebin, Phys. Rev. Lett. 98, 225505 (2007)], is vitrified by the use of a rapid
cooling technique in a molecular dynamics simulation. Transformation to a
crystalline state is investigated at various temperatures and the
time-temperature-transformation (TTT) curve is determined. It is found that the
transformation time to a crystalline state is the shortest at a temerature 14%
below the melting temperature Tm and that at temperatures below Tv = 0.6 Tm the
transformation time is much longer than the available CPU time. This indicates
that a long-lived glassy state is realized for T < Tv.Comment: 5pages,5figures,accepted for publication in CEJ
A new photon recoil experiment: towards a determination of the fine structure constant
We report on progress towards a measurement of the fine structure constant to
an accuracy of or better by measuring the ratio of the
Planck constant to the mass of the cesium atom. Compared to similar
experiments, ours is improved in three significant ways: (i) simultaneous
conjugate interferometers, (ii) multi-photon Bragg diffraction between same
internal states, and (iii) an about 1000 fold reduction of laser phase noise to
-138 dBc/Hz. Combining that with a new method to simultaneously stabilize the
phases of four frequencies, we achieve 0.2 mrad effective phase noise at the
location of the atoms. In addition, we use active stabilization to suppress
systematic effects due to beam misalignment.Comment: 12 pages, 9 figure
Financial Inclusion and Macroeconomic Stability in Emerging and Frontier Markets
Financial inclusion, being considered as a key enabler to reducing poverty and boosting prosperity
in emerging and frontier markets such as Vietnam, is the process in which individuals and small
businesses are provided with an access to useful and affordable financial products and services.
The extant literature on the empirical evidence regarding the contribution of financial inclusion to
macroeconomic stability is mixed. This paper investigates the linkages between financial inclusion
and macroeconomic stability, which has not yet been thoroughly examined in the literature, for 22
emerging and frontier economies from 2008 to 2015, with particular focus on a potential optimal
level. Using the panel threshold estimation technique, the empirical findings show that financial
inclusion, as approximated by the growth rate in the number of bank branches over 100,000
account holders, is found to enhance financial stability under a certain threshold. Financial
inclusion is also found to be of benefit to maintaining stable inflation and output growth. Policy
implications are also discussed on the basis of the important empirical findings
Profiling anticancer and antioxidant activities of phenolic compounds present in black walnuts (Juglans nigra) using a high-throughput screening approach
Our recent studies have demonstrated multiple health-promoting benefits from black
walnut kernels. These biological functions of black walnuts are likely associated with their bioactive
constituents. Characterization of phenolic compounds found in black walnut could point out
underexplored bioactive activities of black walnut extracts and promote the development of novel
applications of black walnut and its by-products. In the present study, we assessed bioactivity profiles
of phenolic compounds identified in the kernels of black walnuts using a high-throughput screening
(HTS) approach. Black walnut phenolic compounds were evaluated in terms of their total antioxidant
capacity, antioxidant response element (ARE) induction, and anticancer activities. The anticancer
activities were identified by evaluating the effects of the phenolic compounds on the growth of
the tumorigenic alveolar epithelial cells (A549) and non-tumorigenic lung fibroblast cells (MRC-5).
Out of 16 phenolic compounds tested, several compounds (penta-O-galloyl-β-d-glucose, epicatechin
gallate, quercetin, (–)-epicatechin, rutin, quercetin 3-β-d-glucoside, gallic acid, (+)-catechin, ferulic
acid, syringic acid) exerted antioxidant activities that were significantly higher compared to Trolox,
which was used as a control. Two phenolic compounds, penta-O-galloyl-β-d-glucose and quercetin
3-β-d-glucoside, exhibited antiproliferative activities against both the tumorigenic alveolar epithelial
cells (A549) and non-tumorigenic lung fibroblast cells (MRC-5). The antioxidant activity of black
walnut is likely driven not only by penta-O-galloyl-β-d-glucose but also by a combination of multiple
phenolic compounds. Our findings suggested that black walnut extracts possibly possess anticancer
activities and supported that penta-O-galloyl-β-d-glucose could be a potential bioactive agent for the
cosmetic and pharmaceutical industries.Supplementary Materials: Figure S1: Data distribution of controls (Trolox,
DL-sulforaphane, tert- butylhydroquinone) in total antioxidant capacity and antioxidant response element (ARE)
activation assays. Figure S2: Data distribution of controls (Trolox, DL-sulforaphane) in cytotoxicity assays.USDA/ARS Dale Bumpers Small Farm Research Center,
Center for Agroforestry at University of Missouri and
Missouri Department of Agriculture Specialty Crop Block Grant Program (SCBGP).http://www.mdpi.com/journal/moleculespm2020Plant Production and Soil Scienc
An Efficient Representation of Euclidean Gravity I
We explore how the topology of spacetime fabric is encoded into the local
structure of Riemannian metrics using the gauge theory formulation of Euclidean
gravity. In part I, we provide a rigorous mathematical foundation to prove that
a general Einstein manifold arises as the sum of SU(2)_L Yang-Mills instantons
and SU(2)_R anti-instantons where SU(2)_L and SU(2)_R are normal subgroups of
the four-dimensional Lorentz group Spin(4) = SU(2)_L x SU(2)_R. Our proof
relies only on the general properties in four dimensions: The Lorentz group
Spin(4) is isomorphic to SU(2)_L x SU(2)_R and the six-dimensional vector space
of two-forms splits canonically into the sum of three-dimensional vector spaces
of self-dual and anti-self-dual two-forms. Consolidating these two, it turns
out that the splitting of Spin(4) is deeply correlated with the decomposition
of two-forms on four-manifold which occupies a central position in the theory
of four-manifolds.Comment: 31 pages, 1 figur
Physicians, Primary Caregivers and Topical Repellent: All Under-Utilised Resources in Stopping Dengue Virus Transmission in Affected Households
BACKGROUND: Primary health care facilities frequently manage dengue cases on an ambulatory basis for the duration of the patient’s illness. There is a great opportunity for specific messaging, aimed to reduce dengue virus (DENV) transmission in and around the home, to be directly targeted toward this high-risk ambulatory patient group, as part of an integrated approach to dengue management. The extent however, to which physicians understand, and can themselves effectively communicate strategies to stop focal DENV transmission around an ambulatory dengue case is unknown; the matter of patient comprehension and recollection then ensues. In addition, the effectiveness of N,N-diethyl-3-methylbenzamide (DEET)-based insect repellent in protecting dengue patients from Aedes aegypti mosquitoes’ bites has not been investigated.
METHODOLOGY: A knowledge, attitude and practice (KAP) survey, focusing on the mechanisms of DENV transmission and prevention, was performed using semi-structured questionnaires. This survey was targeted towards the patients and family members providing supportive care, and physicians routinely involved in dengue patient management in Southern Vietnam. An additional clinical observational study was conducted to measure the efficacy of a widely-used 13% DEET-based insect repellent to repel Ae. aegypti mosquitoes from the forearms of dengue cases and matched healthy controls.
PRINCIPAL FINDINGS: Among both the physician (n = 50) and patient (n = 49) groups there were several respondents lacking a coherent understanding of DENV transmission, leading to some inappropriate attitudes and inadequate acute preventive practices in the household. The application of insect repellent to protect patients and their relatives from mosquito bites was frequently recommended by majority of physicians (78%) participating in the survey. Nevertheless, our tested topical application of 13% DEET conferred only ~1hr median protection time from Ae. aegypti landing. This is notably shorter than that advertised on the manufacturer’s label. No differences in landing time between febrile dengue cases or matched healthy controls (n = 19 experiments) were observed.
CONCLUSIONS/SIGNIFICANCE: Our study identifies missed opportunities for primary care physicians to improve public health through communication of strategies that could prevent focal dengue transmission in and around a case household. We advocate better access to more efficient communication methods for physicians and auxilliary health workers, supporting to educate those at high risk of DENV transmission. Our empirical testing of a widely-available 13% DEET-based repellent was limited in its protective efficacy against Ae. aegypti mosquito bites, and therefore DENV transmission, suggesting more frequent application is necessary to be beneficial
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