406 research outputs found
Shear induced normal stress differences in aqueous foams
A finite simple shear deformation of an elastic solid induces unequal normal
stresses. This nonlinear phenomenon, known as the Poynting effect, is governed
by a universal relation between shear strain and first normal stresses
difference, valid for non-dissipative elastic materials. We provide the first
experimental evidence that an analog of the Poynting effect exists in aqueous
foams where besides the elastic stress, there are significant viscous or
plastic stresses. These results are interpreted in the framework of a
constitutive model, derived from a physical description of foam rheology
Performance improvement of an optical network providing services based on multicast
Operators of networks covering large areas are confronted with demands from
some of their customers who are virtual service providers. These providers may
call for the connectivity service which fulfils the specificity of their
services, for instance a multicast transition with allocated bandwidth. On the
other hand, network operators want to make profit by trading the connectivity
service of requested quality to their customers and to limit their
infrastructure investments (or do not invest anything at all).
We focus on circuit switching optical networks and work on repetitive
multicast demands whose source and destinations are {\em \`a priori} known by
an operator. He may therefore have corresponding trees "ready to be allocated"
and adapt his network infrastructure according to these recurrent
transmissions. This adjustment consists in setting available branching routers
in the selected nodes of a predefined tree. The branching nodes are
opto-electronic nodes which are able to duplicate data and retransmit it in
several directions. These nodes are, however, more expensive and more energy
consuming than transparent ones.
In this paper we are interested in the choice of nodes of a multicast tree
where the limited number of branching routers should be located in order to
minimize the amount of required bandwidth. After formally stating the problem
we solve it by proposing a polynomial algorithm whose optimality we prove. We
perform exhaustive computations to show an operator gain obtained by using our
algorithm. These computations are made for different methods of the multicast
tree construction. We conclude by giving dimensioning guidelines and outline
our further work.Comment: 16 pages, 13 figures, extended version from Conference ISCIS 201
Efficient Generation of Stable Planar Cages for Chemistry
In this paper we describe an algorithm which generates all colored planar
maps with a good minimum sparsity from simple motifs and rules to connect them.
An implementation of this algorithm is available and is used by chemists who
want to quickly generate all sound molecules they can obtain by mixing some
basic components.Comment: 17 pages, 7 figures. Accepted at the 14th International Symposium on
Experimental Algorithms (SEA 2015
Unitarity plus causality implies localizability
We consider a graph with a single quantum system at each node. The entire
compound system evolves in discrete time steps by iterating a global evolution
. We require that this global evolution be unitary, in accordance with
quantum theory, and that this global evolution be causal, in accordance
with special relativity. By causal we mean that information can only ever be
transmitted at a bounded speed, the speed bound being quite naturally that of
one edge of the underlying graph per iteration of . We show that under these
conditions the operator can be implemented locally; i.e. it can be put into
the form of a quantum circuit made up with more elementary operators -- each
acting solely upon neighbouring nodes. We take quantum cellular automata as an
example application of this representation theorem: this analysis bridges the
gap between the axiomatic and the constructive approaches to defining QCA.
KEYWORDS: Quantum cellular automata, Unitary causal operators, Quantum walks,
Quantum computation, Axiomatic quantum field theory, Algebraic quantum field
theory, Discrete space-time.Comment: V1: 5 pages, revtex. V2: Generalizes V1. V3: More precisions and
reference
Metabolite Identification from Biodegradation of Congo Red by Pichia sp.
Azo dyes are commonly used in textile and paper industries. However, its improper disposal often results in polluting water bodies. Azo dyes can cause adverse health effects because of its carcinogenic properties. Various methods to remove azo dyes from water have been proposed, including biological methods such as biosorption and biodegradation. Biosorption and biodegradation were done by using bacteria, yeast or mold. In general, yeasts have some advantages for azo dyes degradation due to its faster growth compared to mold and better resistance against unfavorable environment compared to bacteria. Previously, we observed that yeast Pichia sp. have the ability to degrade Congo red, an azo dye. However, information regarding biodegradation of azo dyes by Pichia sp. are still limited. Therefore, in this study, we showed degradation of Congo red by Pichia sp. crude enzyme extract obtained from separating Pichia cells from medium by centrifugation, followed by identification of its biodegradation products. Biodegradation product was separated from enzyme by ethyl acetate and then Gas Chromatography-Mass Spectroscopy (GC-MS) method was employed to identify biodegradation product. Chromatogram results of GC-MS showed that Congo red were degraded into various products such as biphenyl, naphthalene and smaller molecules with 94 m/z and 51 m/z. These results suggest involvement of azo reductase and laccase-like enzymes which cleaves azo bonds and oxidize the dye molecules to smaller molecules. This study implies the use of Pichia sp. as a bioremediation agent for the removal of azo dyes.
Keywords: Biodegradation, Congo red, Pichia sp., metabolite identification, GC-M
A microsensor array for biochemical sensing
A microsensor array to measure chemical properties of biological liquids is presented. A hybrid integration technique is used to mount four sensor chips on a micro flow channel: a pressure, temperature, pH, combined pO2 and pCO2 sensor chip. This results in a microsensor array which is developed to meet the technical requirements for space applications. The integration method allows to integrate other types of sensor chips. This multi-purpose and multi-user approach makes the microsensor array suitable for various biochemical applications
Data transformation for rank reduction in multi-trait MACE model for international bull comparison
Since many countries use multiple lactation random regression test day models in national evaluations for milk production traits, a random regression multiple across-country evaluation (MACE) model permitting a variable number of correlated traits per country should be used in international dairy evaluations. In order to reduce the number of within country traits for international comparison, three different MACE models were implemented based on German daughter yield deviation data and compared to the random regression MACE. The multiple lactation MACE model analysed daughter yield deviations on a lactation basis reducing the rank from nine random regression coefficients to three lactations. The lactation breeding values were very accurate for old bulls, but not for the youngest bulls with daughters with short lactations. The other two models applied principal component analysis as the dimension reduction technique: one based on eigenvalues of a genetic correlation matrix and the other on eigenvalues of a combined lactation matrix. The first one showed that German data can be transformed from nine traits to five eigenfunctions without losing much accuracy in any of the estimated random regression coefficients. The second one allowed performing rank reductions to three eigenfunctions without having the problem of young bulls with daughters with short lactations
- …