3,336 research outputs found
Dietary fibre and cell-wall polysaccharides in chaenomeles fruits
In this paper, research on dietary fibre and cell-wall polysaccharides in chaenomeles fruits is reported and summarised. The dietary fibre in fruits of 12 genotypes of Japanese quince (Chaenomeles japonica) and 1 genotype of flowering quince (C. speciosa) was prepared using two different methods: the Alcohol Insoluble Solid (AIS) method; and the AOAC method for total as well as for soluble and insoluble fibre. The two methods resulted in significantly different estimates, however, no interaction was found between the methods and the genotypes studied. For content of total dietary fibre, three main groups were distinguished, one containing a low amount of fibre (3 genotypes, 28–30 g/100 g dry matter); one containing a moderate amount of fibre (9 genotypes, 30–36 g/100 g dry matter) and an isolated genotype (C. speciosa) that contained a high amount of fibre (38 g/100 g dry matter). The amount and the nature of monomeric sugars in the constituent polysaccharides of the fibre were determined after total hydrolysis of the AIS and the TDF (Total Dietary Fibre). The fibre contained mostly pectic and cellulosic polysaccharides. A sequential extraction scheme allowed the separation of the cell-wall material into its major components (cellulose, pectins and hemicelluloses). The AIS was composed of 30 g pectins, 8 g hemicelluloses and 60 g cellulosic residue/100 g AIS. In 100 g entire dry fruit (800 g entire fresh fruit) there were 11 g pectins, 3 g hemicelluloses and 18 g cellulosic residue. Pectins were mostly located in the flesh of the fruit. Pectins were more efficiently extracted with hot dilute acid than with other extraction media. Pectins had a high degree of methylation (DM) and a low degree of acetylation (DAc). No difference was found in the quantity of polysaccharides extracted from two Japanese quince genotypes, or in the composition of these constituent polysaccharides. The physico-chemical properties of pectins extracted from two genotypes of Japanese quince were studied. On average, the fruits contained 11 g pectins/100 g dry fruit corresponding to 1.4 g pectins/100 g fresh fruit. Pectins were sequentially extracted, and the cells from the flesh of the fruits were observed with a confocal laser scan microscope. Although the dilute acid conditions were the most efficient for extraction of pectins, pectins extracted by water or potassium oxalate had higher (> 600 ml/g) intrinsic viscosities than pectins extracted by dilute acid (< 400 ml/g). Anionic exchange chromatography was performed on the acid-extracted pectins. The pectins were composed of four populations, the first being mainly composed of arabinans, the second of homogalacturonans and the third of rhamnogalacturonans. The composition of the fourth population differed depending on the genotype studied
A morphological study of cluster dynamics between critical points
We study the geometric properties of a system initially in equilibrium at a
critical point that is suddenly quenched to another critical point and
subsequently evolves towards the new equilibrium state. We focus on the
bidimensional Ising model and we use numerical methods to characterize the
morphological and statistical properties of spin and Fortuin-Kasteleyn clusters
during the critical evolution. The analysis of the dynamics of an out of
equilibrium interface is also performed. We show that the small scale
properties, smaller than the target critical growing length with the dynamic exponent, are characterized by equilibrium at the
working critical point, while the large scale properties, larger than the
critical growing length, are those of the initial critical point. These
features are similar to what was found for sub-critical quenches. We argue that
quenches between critical points could be amenable to a more detailed
analytical description.Comment: 26 pages, 13 figure
Persistence in the two dimensional ferromagnetic Ising model
We present very accurate numerical estimates of the time and size dependence
of the zero-temperature local persistence in the ferromagnetic Ising
model. We show that the effective exponent decays algebraically to an
asymptotic value that depends upon the initial condition. More
precisely, we find that takes one universal value for
initial conditions with short-range spatial correlations as in a paramagnetic
state, and the value for initial conditions with the long-range
spatial correlations of the critical Ising state. We checked universality by
working with a square and a triangular lattice, and by imposing free and
periodic boundary conditions. We found that the effective exponent suffers from
stronger finite size effects in the former case.Comment: v2: minor corrections and typos correcte
A Unifying Framework for Finite Wordlength Realizations.
A general framework for the analysis of the finite
wordlength (FWL) effects of linear time-invariant digital filter
implementations is proposed. By means of a special implicit system
description, all realization forms can be described. An algebraic
characterization of the equivalent classes is provided, which
enables a search for realizations that minimize the FWL effects
to be made. Two suitable FWL coefficient sensitivity measures
are proposed for use within the framework, these being a transfer
function sensitivity measure and a pole sensitivity measure. An
illustrative example is presented
Critical percolation in the dynamics of the 2d ferromagnetic Ising model
We study the early time dynamics of the 2d ferromagnetic Ising model
instantaneously quenched from the disordered to the ordered, low temperature,
phase. We evolve the system with kinetic Monte Carlo rules that do not conserve
the order parameter. We confirm the rapid approach to random critical
percolation in a time-scale that diverges with the system size but is much
shorter than the equilibration time. We study the scaling properties of the
evolution towards critical percolation and we identify an associated growing
length, different from the curvature driven one. By working with the model
defined on square, triangular and honeycomb microscopic geometries we establish
the dependence of this growing length on the lattice coordination. We discuss
the interplay with the usual coarsening mechanism and the eventual fall into
and escape from metastability.Comment: 67 pages, 33 figure
How soon after a zero-temperature quench is the fate of the Ising model sealed?
We study the transient between a fully disordered initial condition and a
percolating structure in the low-temperature non-conserved order parameter
dynamics of the bi-dimensional Ising model. We show that a stable structure of
spanning clusters establishes at a time . Our
numerical results yield for the square and kagome,
for the triangular and for the bowtie-a
lattices.We generalise the dynamic scaling hypothesis to take into account this
new time-scale. We discuss the implications of these results for other
non-equilibrium processes.Comment: 5 pages, 6 figures + supplemental material (2 pages, 1 figure),
version 2: new co-author, extended manuscrip
Alien Registration- Thibault, Alice F. (Lewiston, Androscoggin County)
https://digitalmaine.com/alien_docs/28125/thumbnail.jp
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