2,814 research outputs found
The effect of electric field on important food-processing enzymes : comparison of inactivation kinetics under conventional and ohmic heating
This work deals with the determination of the inactivation kinetics of several enzymes, most of them
used as time-temperature integrators in the food industry. The tested enzymes were polyphenoloxidase,
lipoxygenase, pectinase, alkaline phosphatase, and ÎČ-galactosidase, and the inactivation assays were performed
under conventional and ohmic heating conditions. The thermal history of the samples (conventional and
ohmically processed) was made equal to determine if there was an additional inactivation caused by the presence
of an electric field, thus eliminating temperature as a variable. All the enzymes followed 1st-order inactivation
kinetics for both conventional and ohmic heating treatments. The presence of an electric field does not cause
an enhanced inactivation to alkaline phosphatase, pectinase, and ÎČ-galactosidase. However, lipoxygenase and
polyphenoloxidase kinetics were significantly affected by the electric field, reducing the time needed for inactivation.
The results of the present work can be used industrially to determine processing effectiveness when ohmic
heating technology is applied
Equivalence of Fokker-Planck approach and non-linear -model for disordered wires in the unitary symmetry class
The exact solution of the Dorokhov-Mello-Pereyra-Kumar-equation for quasi
one-dimensional disordered conductors in the unitary symmetry class is employed
to calculate all -point correlation functions by a generalization of the
method of orthogonal polynomials. We obtain closed expressions for the first
two conductance moments which are valid for the whole range of length scales
from the metallic regime () to the insulating regime () and
for arbitrary channel number. In the limit (with )
our expressions agree exactly with those of the non-linear -model
derived from microscopic Hamiltonians.Comment: 9 pages, Revtex, one postscript figur
Universal Parametric Correlations of Eigenvalues of Random Matrix Ensemble
Eigenvalue correlations of random matrix ensembles as a function of an
external perturbation are investigated vis the Dyson Brownian Motion Model in
the situation where the level density has a hard edge singularity. By solving a
linearized hydrodynamical equation, a universal dependence of the
density-density correlator on the external field is found. As an application we
obtain a formula for the variance of linear statistics with the parametric
dependence exhibited as a Laplace transform.Comment: 23 pages, late
ÂżCĂłmo promover el interĂ©s por la cultura cientĂfica? una propuesta didĂĄctica fundamentada
Path Integral Approach to the Scattering Theory of Quantum Transport
The scattering theory of quantum transport relates transport properties of
disordered mesoscopic conductors to their transfer matrix \bbox{T}. We
introduce a novel approach to the statistics of transport quantities which
expresses the probability distribution of \bbox{T} as a path integral. The
path integal is derived for a model of conductors with broken time reversal
invariance in arbitrary dimensions. It is applied to the
Dorokhov-Mello-Pereyra-Kumar (DMPK) equation which describes
quasi-one-dimensional wires. We use the equivalent channel model whose
probability distribution for the eigenvalues of \bbox{TT}^{\dagger} is
equivalent to the DMPK equation independent of the values of the forward
scattering mean free paths. We find that infinitely strong forward scattering
corresponds to diffusion on the coset space of the transfer matrix group. It is
shown that the saddle point of the path integral corresponds to ballistic
conductors with large conductances. We solve the saddle point equation and
recover random matrix theory from the saddle point approximation to the path
integral.Comment: REVTEX, 9 pages, no figure
The interfruta project and its contribution to the knowledge of chestnut moth (Cydia splendana Hubner)(Lepidoptera: Tortricidae) dispersal and infestation on Terceira Island, Azores
The chestnut moth is one of the principal pests on Terceira Island affecting
the quality of all chestnut production. Investigation work developed by the
Interfruta II Project (a project of interregional cooperation among the three
Atlantic regions: Azores, Madeira and Canaries) aims at increasing interest in fruit
and the vineyard production in the three partner regions. The chestnut moth (Cydia
splendana Hubner) (Lepidoptera: Tortricidae) is the only specie responsible for
chestnut fruit damage.
The monitoring of this pest using Delta traps with sex pheromone revealed
the adult abundance during the season. The higher activity period was between July
and October, the months when the chestnut harvest begins.
A map of Terceira Island using a GPS and ArcGis 8.0 software was made
showing the locality of all the chestnut production areas studied.
In the evaluated orchards, fruit damage reached its maximum of 38% at
Terra ChĂŁ, 218 m of altitude and a southern exposure, and a minimum of 0%
damage at Biscoitos, at about the same altitude but with a northern exposure. In
both cases, the percentages of infestation were achieved by analyzing a sample of
2.500 chestnuts for each parcel of land.info:eu-repo/semantics/publishedVersio
Finite element analysis of stress extent at peri-implant bone surrounding external hexagon or Morse taper implants
The purpose of the present study was to evaluate the distribution of stresses and consequent bone volume affected surrounding external hexagon or Morse taper dental implant systems by finite element analysis.The authors acknowledge the support provided by the Dept. of Mechanical Engineering at the University of Minho (Portugal) and by Drawing 3D implicit Finite Element Code (DD3imp, Portugal). This study was supported by FCT-Portugal (EXCL/EMS-TEC/0460/2012; UID/EEA/04436/2013, NORTE-01-0145-FEDER-000018 - HAMaBICo), CNPq-Brazil (PVE/CAPES/CNPq/407035/2013-3).info:eu-repo/semantics/publishedVersio
Kinetic description of particle interaction with a gravitational wave
The interaction of charged particles, moving in a uniform magnetic field,
with a plane-polarized gravitational wave is considered using the
Fokker-Planck- Kolmogorov (FPK) approach. By using a stochasticity criterion,
we determine the exact locations in phase space, where resonance overlapping
occurs. We investigate the diffusion of orbits around each primary resonance of
order (m) by deriving general analytical expressions for an effective diffusion
coeficient. A solution to the corresponding diffusion equation (Fokker-Planck
equation) for the static case is found. Numerical integration of the full
equations of motion and subsequent calculation of the diffusion coefficient
verifies the analytical results.Comment: LaTeX file, 15 page
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