14,492 research outputs found
Empiricism and stochastics in cellular automaton modeling of urban land use dynamics
An increasing number of models for predicting land use change in regions of rapidurbanization are being proposed and built using ideas from cellular automata (CA)theory. Calibrating such models to real situations is highly problematic and to date,serious attention has not been focused on the estimation problem. In this paper, wepropose a structure for simulating urban change based on estimating land usetransitions using elementary probabilistic methods which draw their inspiration fromBayes' theory and the related ?weights of evidence? approach. These land use changeprobabilities drive a CA model ? DINAMICA ? conceived at the Center for RemoteSensing of the Federal University of Minas Gerais (CSR-UFMG). This is based on aneight cell Moore neighborhood approach implemented through empirical land useallocation algorithms. The model framework has been applied to a medium-size townin the west of São Paulo State, Bauru. We show how various socio-economic andinfrastructural factors can be combined using the weights of evidence approach whichenables us to predict the probability of changes between land use types in differentcells of the system. Different predictions for the town during the period 1979-1988were generated, and statistical validation was then conducted using a multipleresolution fitting procedure. These modeling experiments support the essential logicof adopting Bayesian empirical methods which synthesize various information aboutspatial infrastructure as the driver of urban land use change. This indicates therelevance of the approach for generating forecasts of growth for Brazilian citiesparticularly and for world-wide cities in general
Combining exclusive semi-leptonic and hadronic B decays to measure |V_ub|
The Cabibbo-Kobayashi-Maskawa matrix element |V_ub| can be extracted from the
rate for the semi-leptonic decay B -> pi + l + antineutrino_l, with little
theoretical uncertainty, provided the hadronic form factor for the B -> pi
transition can be measured from some other B decay. In here, we suggest using
the decay B -> pi J\psi. This is a color suppressed decay, and it cannot be
properly described within the usual factorization approximation; we use instead
a simple and very general phenomenological model for the b d J\psi vertex. In
order to relate the hadronic form factors in the B -> pi J\psi and B -> pi + l
+ antineutrino_l decays, we use form factor relations that hold for
heavy-to-light transitions at large recoil.Comment: Latex, 7 pages, no figure
New species and new record of anthomedusae from southern Brazil
A new species of Hydromedusa belonging to the genus Octocanna Haeckel 1879, here revived, is described from the coastal waters off Santos. The new species belongs to the family Phialuciidae, it is named Octocanna haeckeli sp. n. and differs from the other two species of the genus in being smaller, in having a high dome shaped umbrella, four tentacles, eight bulbs and eight marginal vesicles at sexual maturity. The genus Octocanna is here revived for Phialuciidae with eight radial canals, eight gonads, four or more tentacles and never more than four lips. The genus Octophialucium Kramp 1955 is considered valid for Phialuciidae with eight radial canals, eight gonads and eight lips. In the same series of samples, some specimens of Octophialucium bigelowi Kramp 1955 were taken which are very similar to Octocanna haeckeli but have eight lips, eight tentacles, rudimentary bulbs and a larger number of marginal vesicles at sexual maturity, which is reached at approximately the same umbrella size. The two similar species were taken in the same water mass at approximately the same time of the same year.Descreve-se uma nova espécie de hidromedusa, coletada em águas costeiras próximas a Santos, pertencente ao gênero Octocanna Haeckel 1879. Este gênero foi considerado obsoleto por KRAMP, mas o achado presente mostra que deve ser reestabelecido. A nova espécie chamada Otocanna haeckeli pertence à família Phialuciidae. Difere das outras duas espécies do mesmo gênero por ser menor, ter umbrela alta em forma de domo, 4 tentáculos, 8 bulbos e 8 vesículas marginais quando atinge a maturidade sexual. A validade do gênero Octocanna fica restabelecida para as Phialuciidae com 8 canais radiais, 8 gônadas, 4 ou mais tentáculos e nunca mais do que 4 lábios. O gênero Octophialucium Kramp 1955 é mantido como válido para Phialuciidae com 8 canais radiais, 8 gônadas e 8 lábios. Na mesma série de amostras foram coletados alguns espécimes de Octophialucium bigelowi Kramp 1955 que se assemelham à primeira vista a Octocanna haeckeli, mas têm 8 lábios, 8 tentáculos, bulbos rudimentares e um número maior de vesículas marginais quando sexualmente maduros. Ambas as espécies atingem a maturidade com aproximadamente o mesmo tamanho e foram coletadas na mesma massa d'água, em datas próximas do mesmo ano
Erlang Code Evolution Control
During the software lifecycle, a program can evolve several times for
different reasons such as the optimisation of a bottle-neck, the refactoring of
an obscure function, etc. These code changes often involve several functions or
modules, so it can be difficult to know whether the correct behaviour of the
previous releases has been preserved in the new release. Most developers rely
on a previously defined test suite to check this behaviour preservation. We
propose here an alternative approach to automatically obtain a test suite that
specifically focusses on comparing the old and new versions of the code. Our
test case generation is directed by a sophisticated combination of several
already existing tools such as TypEr, CutEr, and PropEr; and other ideas such
as allowing the programmer to chose an expression of interest that must
preserve the behaviour, or the recording of the sequences of values to which
this expression is evaluated. All the presented work has been implemented in an
open-source tool that is publicly available on GitHub.Comment: Pre-proceedings paper presented at the 27th International Symposium
on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur,
Belgium, 10-12 October 2017 (arXiv:1708.07854
Retinal Vessel Segmentation Using the 2-D Morlet Wavelet and Supervised Classification
We present a method for automated segmentation of the vasculature in retinal
images. The method produces segmentations by classifying each image pixel as
vessel or non-vessel, based on the pixel's feature vector. Feature vectors are
composed of the pixel's intensity and continuous two-dimensional Morlet wavelet
transform responses taken at multiple scales. The Morlet wavelet is capable of
tuning to specific frequencies, thus allowing noise filtering and vessel
enhancement in a single step. We use a Bayesian classifier with
class-conditional probability density functions (likelihoods) described as
Gaussian mixtures, yielding a fast classification, while being able to model
complex decision surfaces and compare its performance with the linear minimum
squared error classifier. The probability distributions are estimated based on
a training set of labeled pixels obtained from manual segmentations. The
method's performance is evaluated on publicly available DRIVE and STARE
databases of manually labeled non-mydriatic images. On the DRIVE database, it
achieves an area under the receiver operating characteristic (ROC) curve of
0.9598, being slightly superior than that presented by the method of Staal et
al.Comment: 9 pages, 7 figures and 1 table. Accepted for publication in IEEE
Trans Med Imag; added copyright notic
Group Theory analysis of phonons in two-dimensional Transition Metal Dichalcogenides
Transition metal dichalcogenides (TMDCs) have emerged as a new two
dimensional materials field since the monolayer and few-layer limits show
different properties when compared to each other and to their respective bulk
materials. For example, in some cases when the bulk material is exfoliated down
to a monolayer, an indirect-to-direct band gap in the visible range is
observed. The number of layers ( even or odd) drives changes in space
group symmetry that are reflected in the optical properties. The understanding
of the space group symmetry as a function of the number of layers is therefore
important for the correct interpretation of the experimental data. Here we
present a thorough group theory study of the symmetry aspects relevant to
optical and spectroscopic analysis, for the most common polytypes of TMDCs,
i.e. , and , as a function of the number of layers. Real space
symmetries, the group of the wave vectors, the relevance of inversion symmetry,
irreducible representations of the vibrational modes, optical selection rules
and Raman tensors are discussed.Comment: 32 pages, 4 figure
Avaliação da utilização de nim (Azadirachta indica) no controle parasitário em bovinos de produção leiteira em sistema orgânico.
O objetivo do presente foi avaliar a eficácia do extrato oleoso de Nim em bovinos, naturalmente parasitados por Haemabotia irritans, Dermatobia honinis e Rhipicephallus (Boophilus) microplus, sob um sistema orgânico de produção leiteira. Observou-se que tanto a determinação da concentração do produto a ser utilizado quanto o acompanhamento das variáveis climáticas, associadas ao manejo, são essenciais para que se alcancem resultados satisfatórios.bitstream/item/40435/1/BOP-47.pd
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