Nancy Garcia

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Clement Wong

Robert G Burton

The University of Georgia

marco antonio ZAVALETA SANCHEZ

Tao Sun

Yuval Peres

University of California, Berkeley

University of Oxford

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Papers by Nancy Garcia

On Mixing Times for Stratified Walks on the D-Cube

Using the electric and coupling approaches, we derive a series of results concerning the mixing t... more

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Spatial birth and death processes as solutions of stochastic equations

Latin American journal of probability and mathematical statistics

Spatial birth and death processes are obtained as solutions of a system of stochastic equations. ... more Spatial birth and death processes are obtained as solutions of a system of stochastic equations. The processes are required to be locally finite, but may involve an infinite population over the full (noncompact) type space. Conditions are given for existence and uniqueness of such solutions, and for temporal and spatial ergodicity. For birth and death processes with constant death rate, a sub-criticality condition on the birth rate implies that the process is ergodic and converges exponentially fast to the stationary distribution.

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retrieval from written texts

Context tree selection and linguistic rhythm

proxy of the Kullback-Leibler distance

ABSTRACT estimator for basis selection based on a

Continuity properties of a factor of Markov chains

Starting from a Markov chain with a finite alphabet, we consider the chain obtained when all but ... more

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A general context-tree-based approach to perfect simulation for chains of infinite order

We establish new sufficient conditions for perfect simulation of chains of infinite order on a co... more We establish new sufficient conditions for perfect simulation of chains of infinite order on a countable alphabet. This is done through the introduction of the \emph{localized continuity} assumption. This new assumption, which is formalized with the help of the notion of \emph{context trees}, includes the traditional continuous case, probabilistic context trees and discontinuous kernels. Since our assumptions are more refined than uniform continuity, our algorithms perfectly simulate continuous chains faster than the existing algorithms of the literature. We also give a simple extension of the method allowing to perfectly simulate chains which are neither necessarily continuous nor necessarily weakly non-null.

Correlates of rhythm in written texts of Brazilian and European Portuguese

We address the question of detecting fingerprints of rhythm in writ-ten texts. We study texts fro... more We address the question of detecting fingerprints of rhythm in writ-ten texts. We study texts from 20th century Brazilian and Portuguese authors. In these texts we codify the syllables according to whether they carry main stress or not, and whether they are at the beginning of a phono-logical word or not. Additionally, periods are also marked. Modeling the sequences of symbols obtained with this codification as Variable Length Markov Chains, we estimate the patterns for each text. This probabilis-tic model discriminates European Portuguese from Brazilian Portuguese. Moreover, the model obtained for each language has a clear linguistic interpretation, as it captures structural features which have long been conjectured in the literature.

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Dynamic analysis of electric arcs using a time domain Newton technique

6th IEEE Power Electronics Congress. Technical Proceedings. CIEP 98 (Cat. No.98TH8375), 1998

Abstract - The dynamic behavior of an arc furnace directly connected to an electric network is an... more

Newton methods for the fast computation of the periodic steady-state solution of systems with nonlinear and time-varying components

199 IEEE Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.99CH36364), 1999

NEWTON METHODS FOR THE FAST COMPUTATION OF THE PERIODIC ... VARYING COMPONENTS STEADY-STATE SOLUT... more

Prevalence and intensity of infection, metacyclogenesis and nuclear phenotypes in Panstrongylus megistus (Burmeister, 1835) after ingestion of Trypanosoma cruzi (Chagas, 1909) II and subjection to heat shock

Brazilian journal of biology = Revista brasleira de biologia, 2011

This study aimed to contribute to our knowledge of the parasite-vector interaction associated wit... more This study aimed to contribute to our knowledge of the parasite-vector interaction associated with Trypanosoma cruzi (Chagas, 1909) infection in Panstrongylus megistus (Burmeister, 1835), an important vector of Chagas' disease in Brazil. The prevalence and intensity of T. cruzi infection, the incidence of metacyclogenesis and the frequency of nuclear phenotypes in Malpighian tubules were investigated in nymphs of P. megistus, reared at 28 °C and subjected to heat shock (40 °C, 1 hour) two days after infection with T. cruzi II (Y strain). Following the 45-day post-infection period, the frequency of epimastigotes was much higher than that of trypomastigotes in both heat-shocked and non-shocked insects, and the prevalence of infection was not altered by heat shock. Fewer epimastigotes and trypomastigotes were found in the infected insects subjected to the heat shock, indicating that the multiplication and metacyclogenesis of the parasites were affected by the stress. In infected sp...

Experimentally induced heat- and cold-shock tolerance in adult Panstrongylus megistus (Burmeister) (Hemiptera, Reduviidae)

Brazilian journal of biology = Revista brasleira de biologia, 2003

The survival rate of domestic male and female adult Panstrongylus megistus was studied after sequ... more The survival rate of domestic male and female adult Panstrongylus megistus was studied after sequential heat and cold shocks in order to investigate shock tolerance compared to that previously reported for nymphs. Sequential shocks were such that a milder shock (0 degree C, 5 degrees C, 35 degrees C, or 40 degrees C for 1 h) preceded a severe one (0 degree C or 40 degrees C for 12 h), separated by intervals of 8, 18, 24, and 72 h at 28 degrees C (control temperature). The preliminary thermal shock induced tolerance to the more severe one, although tolerance intensity depended on the initial shock temperature and the interval between treatments. Despite the observed tolerance, the survival rate for insects subjected to both shocks decreased when compared to that of individuals subjected to a single mild shock. When tolerance differed with sex, females showed greater values than males. In contrast to the response detected in nymphs, for which higher heat tolerance values were sustaine...

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Stochastically Perturbed Chains of Variable Memory

Journal of Statistical Physics, 2015

In this paper, we study inference for chains of variable order under two distinct contamination r... more In this paper, we study inference for chains of variable order under two distinct contamination regimes. Consider we have a chain of variable memory on a finite alphabet containing zero. At each instant of time an independent coin is flipped and if it turns head a contamination occurs. In the first regime a zero is read independent of the value of the chain. In the second regime, the value of another chain of variable memory is observed instead of the original one. Our results state that the difference between the transition probabilities of the original process and the corresponding ones of the contaminated process may be bounded above uniformly. Moreover, if the contamination probability is small enough, using a version of the Context algorithm we are able to recover the context tree of the original process through a contaminated sample.

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Size Effects in the Magnetoresistance of Graphite: Absence of Magnetoresistance in Micrometer size Samples

by Nancy Garcia and Jesús González

We present a study of the magnetoresistance of highly oriented pyrolytic graphite (HOPG) as a fun... more We present a study of the magnetoresistance of highly oriented pyrolytic graphite (HOPG) as a function of the sample size. Our results show unequivocally that the magnetoresistance reduces with the sample size even for samples of hundreds of micrometers size. This sample size effect is due the large mean free path and Fermi wavelength of carriers in graphite and may explain the observed practically absence of magnetoresistance in micrometer confined small graphene samples where quantum effects should be at hand. These were not taken into account in the literature yet and ask for a revision of experimental and theoretical work on graphite.

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From Ohmic to Ballistic Transport in Oriented Graphite

In this work we show that the spreading ohmic resistance of a quasi-2D system of size Ω, thicknes... more In this work we show that the spreading ohmic resistance of a quasi-2D system of size Ω, thickness t with a constriction of size W connecting two half-parts of resistivity ρ goes as (2ρ/πt)ln(Ω/W), diverging logarithmically with the size. Measurements in highly oriented pyrolytic graphite (HOPG) as well as numerical simulations confirm this relation.

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Analysis of Aggregated Functional Data from Mixed Populations with Application to Energy Consumption

Understanding the energy consumption patterns of different types of consumers is essential in any... more Understanding the energy consumption patterns of different types of consumers is essential in any planning of energy distribution. However, obtaining consumption information for single individuals is often either not possible or too expensive. Therefore, we consider data from aggregations of energy use, that is, from sums of individuals' energy use, where each individual falls into one of C consumer classes. Unfortunately, the exact number of individuals of each class may be unknown: consumers do not always report the appropriate class, due to various factors including differential energy rates for different consumer classes. We develop a methodology to estimate the expected energy use of each class as a function of time and the true number of consumers in each class. We also provide some measure of uncertainty of the resulting estimates. To accomplish this, we assume that the expected consumption is a function of time that can be well approximated by a linear combination of B-splines. Individual consumer perturbations from this baseline are modeled as B-splines with random coefficients. We treat the reported numbers of consumers in each category as random variables with distribution depending on the true number of consumers in each class and on the probabilities of a consumer in one class reporting as another class. We obtain maximum likelihood estimates of all parameters via a maximization algorithm. We introduce a special numerical trick for calculating the maximum likelihood estimates of the true number of consumers in each class. We apply our method to a data set and study our method via simulation.

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Perfect simulation and finitary coding for multicolor systems with interactions of infinite range

We consider a particle system on Z d with finite state space and interactions of infinite range. ... more We consider a particle system on Z d with finite state space and interactions of infinite range. Assuming that the rate of change is continuous and decays sufficiently fast, we introduce a perfect simulation algorithm for the stationary process. The basic tool we use is a representation of the infinite range change rates as a mixture of finite range change rates. The perfect simulation scheme provides the basis for the construction of a finitary coding from an i.i.d. finite-value process to the invariant measure of the multicolor system.

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A constructive approach to the Monge-Kantorovich problem for chains of infinite order

ABSTRACT We propose a constructive approach to solve the Monge-Kantorovich problem for chains of ... more ABSTRACT We propose a constructive approach to solve the Monge-Kantorovich problem for chains of infinite order on a finite alphabet with an additive cost function. From this constructive descrip- tion of the Kantorovich coupling we obtain, for any &gt; 0, a perfect simulation algorithm for sampling from an -approximating coupling which assigns to the cost function an expectation which is -close to the minimum cost. Our approach is based on a regenerative scheme which enable us to construct the Kantorovich coupling as a mixture of product measures.

Fluidic components based on ferrofluids

1st Annual International IEEE-EMBS Special Topic Conference on Microtechnologies in Medicine and Biology. Proceedings (Cat. No.00EX451), 2000

Abstract The miniaturisation of steps like synthesis or analysis of liquids or gases requires mic... more Abstract The miniaturisation of steps like synthesis or analysis of liquids or gases requires microchannels,-pumps and-valves. Here a microvalve is presented which uses a ferrofluid as sealing medium. Compared to mechanical valves this has the advantage of total adaptability to any geometry even allowing the hermetic sealing of channels or grooves with changing cross-section. For the movement of the ferrofluid a coil driven external magnet is used. An actuator using a magnet, driven by microcoils makes the main microfluidic ...

Aggregated functional data model for near-infrared spectroscopy calibration and prediction

Journal of Applied Statistics, 2014

Calibration and prediction for NIR spectroscopy data are performed based on a functional interpre... more Calibration and prediction for NIR spectroscopy data are performed based on a functional interpretation of the Beer-Lambert formula. Considering that, for each chemical sample, the resulting spectrum is a continuous curve obtained as the summation of overlapped absorption spectra from each analyte plus a Gaussian error, we assume that each individual spectrum can be expanded as a linear combination of B-splines basis. Calibration is then performed using two procedures for estimating the individual analytes curves: basis smoothing and smoothing splines.

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Spatial Point Processes and the Projection Method

In and Out of Equilibrium 2, 2008

The projection method obtains non-trivial point processes from higher dimensional Poisson point p... more The projection method obtains non-trivial point processes from higher dimensional Poisson point processes by constructing a random subset of the higher dimensional space and projecting the points of the Poisson process lying in that set onto the lower dimensional region. This paper presents a review of this method related to spatial point processes as well as some examples of its applications. The results presented here are known for sometime but were not published before. Also, we present a backward construction of general spatial pure-birth processes and spatial birth and death processes based on the projection method that leads to a perfect simulation scheme for some Gibbs distributions in compact regions.

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On Mixing Times for Stratified Walks on the D-Cube

Using the electric and coupling approaches, we derive a series of results concerning the mixing t... more

Download

Spatial birth and death processes as solutions of stochastic equations

Latin American journal of probability and mathematical statistics

Download

retrieval from written texts

Context tree selection and linguistic rhythm

proxy of the Kullback-Leibler distance

ABSTRACT estimator for basis selection based on a

Continuity properties of a factor of Markov chains

Starting from a Markov chain with a finite alphabet, we consider the chain obtained when all but ... more

Download

A general context-tree-based approach to perfect simulation for chains of infinite order

Correlates of rhythm in written texts of Brazilian and European Portuguese

Download

Dynamic analysis of electric arcs using a time domain Newton technique

6th IEEE Power Electronics Congress. Technical Proceedings. CIEP 98 (Cat. No.98TH8375), 1998

Abstract - The dynamic behavior of an arc furnace directly connected to an electric network is an... more

Newton methods for the fast computation of the periodic steady-state solution of systems with nonlinear and time-varying components

199 IEEE Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.99CH36364), 1999

NEWTON METHODS FOR THE FAST COMPUTATION OF THE PERIODIC ... VARYING COMPONENTS STEADY-STATE SOLUT... more

Brazilian journal of biology = Revista brasleira de biologia, 2011

Experimentally induced heat- and cold-shock tolerance in adult Panstrongylus megistus (Burmeister) (Hemiptera, Reduviidae)

Brazilian journal of biology = Revista brasleira de biologia, 2003

Download

Stochastically Perturbed Chains of Variable Memory

Journal of Statistical Physics, 2015

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Size Effects in the Magnetoresistance of Graphite: Absence of Magnetoresistance in Micrometer size Samples

by Nancy Garcia and Jesús González

Download

From Ohmic to Ballistic Transport in Oriented Graphite

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Analysis of Aggregated Functional Data from Mixed Populations with Application to Energy Consumption

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Perfect simulation and finitary coding for multicolor systems with interactions of infinite range

Download

A constructive approach to the Monge-Kantorovich problem for chains of infinite order

Fluidic components based on ferrofluids

1st Annual International IEEE-EMBS Special Topic Conference on Microtechnologies in Medicine and Biology. Proceedings (Cat. No.00EX451), 2000

Aggregated functional data model for near-infrared spectroscopy calibration and prediction

Journal of Applied Statistics, 2014

Download

Spatial Point Processes and the Projection Method

In and Out of Equilibrium 2, 2008

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