309 research outputs found
Data Fusion Techniques for Processing Aerospace Remote Sensing Electro-Optical Data
This paper deals with data fusion between different resolution multispectral (MS) and panchromatic (Pan) images in order to obtain high spatial resolution MS images. A survey is provided about the state-of-the-art data fusion techniques and synthesized product's quality assessment criteria. Several fusion algorithms and quality indexes were implemented in a Toolbox with a graphical user interface developed in MATLAB environment, namely Fusion Tool Box (FTB), developed to obtain experimental results. The analysis performed through FTB on two different data sets was oriented to validate the theoretical analysis and to perform a quantitative comparison among fusion algorithms for several applications. Results allow a first level evaluation of advantages and drawbacks of the various techniques for specific applications
Lexical evolution rates by automated stability measure
Phylogenetic trees can be reconstructed from the matrix which contains the
distances between all pairs of languages in a family. Recently, we proposed a
new method which uses normalized Levenshtein distances among words with same
meaning and averages on all the items of a given list. Decisions about the
number of items in the input lists for language comparison have been debated
since the beginning of glottochronology. The point is that words associated to
some of the meanings have a rapid lexical evolution. Therefore, a large
vocabulary comparison is only apparently more accurate then a smaller one since
many of the words do not carry any useful information. In principle, one should
find the optimal length of the input lists studying the stability of the
different items. In this paper we tackle the problem with an automated
methodology only based on our normalized Levenshtein distance. With this
approach, the program of an automated reconstruction of languages relationships
is completed
2d frustrated Ising model with four phases
In this paper we consider a 2d random Ising system on a square lattice with
nearest neighbour interactions. The disorder is short range correlated and
asymmetry between the vertical and the horizontal direction is admitted. More
precisely, the vertical bonds are supposed to be non random while the
horizontal bonds alternate: one row of all non random horizontal bonds is
followed by one row where they are independent dichotomic random variables. We
solve the model using an approximate approach that replace the quenched average
with an annealed average under the constraint that the number of frustrated
plaquettes is keep fixed and equals that of the true system. The surprising
fact is that for some choices of the parameters of the model there are three
second order phase transitions separating four different phases:
antiferromagnetic, glassy-like, ferromagnetic and paramagnetic.Comment: 17 pages, Plain TeX, uses Harvmac.tex, 4 ps figures, submitted to
Physical Review
Influence of Ageing Time and Method on Beef Quality and Safety
The effectiveness of dry ageing with regard to retaining meat quality is still subject to debate. At 4 d post mortem, samples of boneless strip loins were excised from young Charolais carcasses and then stored for a further 26 d in a cooler, either vacuum-packaged (VP) or dried-aged (DA). Loin samples were also dissected 7 d post mortem as a control treatment (CT). Chemical, instrumental and microbiological data (n = 18) were determined in longissimus dorsi and underwent ANOVA to estimate the differences in the ageing fixed factor split into two orthogonal contrasts: control vs. aged and VP vs. DA. Ageing loss (both surface dehydration and water purge) was greater in DA compared to VP samples, resulting in the lowest moisture content and highest crude protein and fat percentage in DA loins. The ageing method did not affect meat surface colour, except for redness, which had the lowest value in DA samples. Meat tenderness improved a similar amount following both VP and DA ageing treatments. Compared to the control, prolonged ageing raised both the peroxide value and the total microbial count, especially in DA samples, though both remained within the recommended limits. In summation, both ageing methods improved beef meat tenderisation, preserving its shelf life
Evolution of the most recent common ancestor of a population with no selection
We consider the evolution of a population of fixed size with no selection.
The number of generations to reach the first common ancestor evolves in
time. This evolution can be described by a simple Markov process which allows
one to calculate several characteristics of the time dependence of . We also
study how is correlated to the genetic diversity.Comment: 21 pages, 10 figures, uses RevTex4 and feynmf.sty Corrections :
introduction and conclusion rewritten, references adde
Statistical properties of genealogical trees
We analyse the statistical properties of genealogical trees in a neutral
model of a closed population with sexual reproduction and non-overlapping
generations. By reconstructing the genealogy of an individual from the
population evolution, we measure the distribution of ancestors appearing more
than once in a given tree. After a transient time, the probability of
repetition follows, up to a rescaling, a stationary distribution which we
calculate both numerically and analytically. This distribution exhibits a
universal shape with a non-trivial power law which can be understood by an
exact, though simple, renormalization calculation. Some real data on human
genealogy illustrate the problem, which is relevant to the study of the real
degree of diversity in closed interbreeding communities.Comment: Accepted for publication in Phys. Rev. Let
Discriminant analysis of pyrrolizidine alkaloid contamination in bee pollen based on near-infrared data from lab-stationary and portable spectrometers
Bee pollen may be contaminated with pyrrolizidine alkaloids (PAs) and their N-oxides (PANOs), which are mainly detected by liquid chromatography coupled to tandem mass spectrometry (LC\u2013MS/MS), even though the use of fast near-infrared (NIR) spectroscopy is an ongoing alternative. Therefore, the main challenge of this study was to assess the feasibility of both a lab-stationary (Foss) and a portable (Polispec) NIR spectrometer in 60 dehydrated bee pollen samples. After an ANOVA-feature selection of the most informative NIR spectral data, canonical discriminant analysis (CDA) was performed to distinguish three quantitative PA/PANO classes (\ub5g/kg): 400, high. According to the LC\u2013MS/MS analysis, 77% of the samples were contaminated with PAs/PANOs and the sum content of the 17 target analytes was higher than 400\ua0\ub5g/kg in 28% of the samples. CDA was carried out on a pool of 18 (Foss) and 22 (Polispec) selected spectral variables and allowed accurate classification of samples from the low class as confirmed by the high values of Matthews correlation coefficient ( 65 0.91) for both NIR spectrometers. Leave-one-out cross-validation highlighted precise recognition of samples characterised by a high PA/PANO content with a low misclassification rate (0.02) as false negatives. The most informative wavelengths were within the 2400\ua0nm regions for Foss and > 1500\ua0nm for Polispec that could be associated with cyclic amines, and epoxide chemical structures of PAs/PANOs. In sum, both lab-stationary and portable NIR systems are reliable and fast techniques for detecting PA/PANO contamination in bee pollen
Quaternary capable folds and seismic hazard in Lombardia (Northern Italy): the Castenedolo structure near Brescia.
We identify evidence of late Quaternary compressive tectonics
in the Northern sector of the Central Po Plain through a systematic
revision of the literature, new field mapping, and a new study of
seismic reflection data obtained by ENI E&P. In particular, the reinterpretation
of ca. 18.000 km of seismic profiles clearly shows a belt
of segmented, 10 to 20 km long, fault propagation folds, controlled
by the Plio-Quaternary growth of several out-of-sequence thrusts. As
an example of this active structural style, in this paper we focus on a
buried fold located just south of the Castenedolo Hill, a few km SE
of Brescia. Although the Castenedolo anticline has long ago been
described as a young compressional structure (e.g., DESIO, 1965), no
detailed structural analysis of this feature has been performed until
now. We calculated the uplift rates of this fold through the analysis
of its syntectonic sedimentary record as imaged by the extremely
high quality ENI E&P subsurface data available in the area. The evolution
of this anticline was a discontinuous process characterized by
several tectonic uplift pulses (with rates of ca. 0.1 mm/yr) of different
duration, separated by periods of variable extent in which no
fold growth occurred. The Quaternary growth history of this anticline
and the presence of faulted and folded late Pleistocene to
Holocene deposits at nearby sites (Ciliverghe and Monte Netto)
demonstrate that the significant seismicity of this area (e.g., the
December 25, 1222, Io = IX MCS Brescia earthquake, MAGRI &
MOLIN, 1986; GUIDOBONI, 1986) must be related to active compressional
structures within the Brescia piedmont belt. Our
regional investigations show that the structural and paleoseismic
setting illustrated near Castenedolo is typical of the whole Lombardia
domain of the Southern Alps. This implies that the currently
accepted seismotectonic model for this region, and related
seismic hazard assessment, should be thoroughly and carefully
re-evaluated
Field-enlarging transformations and chiral theories
A field-enlarging transformation in the chiral electrodynamics is performed.
This introduces an additional gauge symmetry to the model that is unitary and
anomaly-free and allows for comparison of different models discussed in the
literature. The problem of superfluous degrees of freedom and their influence
on quantization is discussed. Several "mysteries" are explained from this point
of view.Comment: 14 pages, LaTeX-file, BI-TP 93/0
On the accuracy of language trees
Historical linguistics aims at inferring the most likely language
phylogenetic tree starting from information concerning the evolutionary
relatedness of languages. The available information are typically lists of
homologous (lexical, phonological, syntactic) features or characters for many
different languages.
From this perspective the reconstruction of language trees is an example of
inverse problems: starting from present, incomplete and often noisy,
information, one aims at inferring the most likely past evolutionary history. A
fundamental issue in inverse problems is the evaluation of the inference made.
A standard way of dealing with this question is to generate data with
artificial models in order to have full access to the evolutionary process one
is going to infer. This procedure presents an intrinsic limitation: when
dealing with real data sets, one typically does not know which model of
evolution is the most suitable for them. A possible way out is to compare
algorithmic inference with expert classifications. This is the point of view we
take here by conducting a thorough survey of the accuracy of reconstruction
methods as compared with the Ethnologue expert classifications. We focus in
particular on state-of-the-art distance-based methods for phylogeny
reconstruction using worldwide linguistic databases.
In order to assess the accuracy of the inferred trees we introduce and
characterize two generalizations of standard definitions of distances between
trees. Based on these scores we quantify the relative performances of the
distance-based algorithms considered. Further we quantify how the completeness
and the coverage of the available databases affect the accuracy of the
reconstruction. Finally we draw some conclusions about where the accuracy of
the reconstructions in historical linguistics stands and about the leading
directions to improve it.Comment: 36 pages, 14 figure
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