bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiscale detection of localized anomalous structure in aggregate disease incidence data
Authors: Louie Mary M. , Kolaczyk Eric D. 
Published: February 2006

AbstractWe present a modelling framework for detection of potentially anomalous structure in aggregate spatial disease incidence data in a manner sensitive to localization at multiple scales and/or positions. The key technical contribution is the re‐casting of the components of a multiscale disease mapping methodology, recently introduced by the authors in an earlier paper, into a form appropriate for hypothesis testing. In particular, we describe how hypotheses of spatially clustered variations in disease incidence may be linked in one‐to‐one correspondence with collections of hypotheses on the values of certain multiscale parameters associated with a user‐defined hierarchy of nested partitions of an overall spatial region. A Bayesian hypothesis testing methodology is developed in the context of a standard Poisson measurement model, over the collection of possible multiscale hypotheses. We discuss the specification of hyper parameters and prior distributions on the space of models. The methodology is illustrated on both simulated and real data. Copyright © 2006 John Wiley & Sons, Ltd.
Impact of prior choice on local Bayes factors for cluster detection
Authors: Gangnon Ronald E. 
Published: February 2006

AbstractIn this paper, we evaluate the usefulness of local Bayes factors as a tool for spatial cluster detection. In particular, we consider whether local Bayes factors from models with a fixed, but overly large number of clusters can consistently identify the evidence for clustering for a variety of prior specifications for the cluster locations. We also investigate the robustness of the local Bayes factor to the number of clusters included in the model. We explore the impacts of prior choice for cluster location and the number of clusters on posterior inference for disease rates. We conduct the comparison by analysing data on 1990 breast cancer incidence in Wisconsin. Copyright © 2006 John Wiley & Sons, Ltd.
Fast detection of arbitrarily shaped disease clusters
Authors: Assunção R. , Costa M. , Tavares A. , Ferreira S. 
Published: February 2006

AbstractDisease cluster detection and evaluation have commonly used spatial statistics methods that scan the map with a fixed circular window to locate candidate clusters. Recently, there has been interest in searching for clusters with arbitrary shape. The circular scan test retains high power of detecting a cluster, but does not necessarily identify the exact regions contained in a non‐circular cluster particularly well. We propose, implement and evaluate a new procedure that is fast and produces clusters estimates of arbitrary shape in a rich class of possible cluster candidates. We showed that our methods contain the so‐called upper level set method as a particular case. We present a power study of our method and, among other results, the main conclusion is that the likelihood‐based arbitrarily shaped scan method is not appropriate to find a cluster estimate. When the parameter space includes the set of all possible spatial clusters in a map, a large and discrete parameter space, maximum likely cluster estimates tend to overestimate the true cluster by a large extent. This calls for a new approach different from the maximum likelihood method for this important public health problem. Copyright © 2006 John Wiley & Sons, Ltd.
The geography of power: statistical performance of tests of clusters and clustering in heterogeneous populations
Authors: Waller Lance A. , Hill Elizabeth G. , Rudd Rose Anne 
Published: February 2006

AbstractHeterogeneous population densities complicate comparisons of statistical power between hypothesis tests evaluating spatial clusters or clustering of disease. Specifically, the location of a cluster within a heterogeneously distributed population at risk impacts power properties, complicating comparisons of tests, and allowing one to map spatial variations in statistical power for different tests. Such maps provide insight into the overall power of a particular test, and also indicate areas within the study area where tests are more or less likely to detect the same local increase in relative risk. While such maps are largely driven by local sample size, we also find differences due to features of the statistics themselves. We illustrate these concepts using two tests: Tango's index of clustering and the spatial scan statistic. Furthermore, assessments of the accuracy of the ‘most likely cluster’ involve not only statistical power, but also spatial accuracy in identifying the location of a true underlying cluster. We illustrate these concepts via induction of artificial clusters within the observed incidence of severe cardiac birth defects in Santa Clara County, CA in 1981. Copyright © 2006 John Wiley & Sons, Ltd.
An extended power of cluster detection tests
Authors: Takahashi Kunihiko , Tango Toshiro 
Published: February 2006

AbstractSeveral tests have been proposed to detect spatial disease clustering without prior information on their locations. In order to compare the performance of these tests, most authors employ the usual power, i.e. the rejection probability of the null hypothesis of no clustering due to various reasons. However, the usual power is not always appropriate for evaluating the cluster detection tests since their purpose is to both reject the null hypothesis and identify the cluster areas accurately. In this paper, we propose an extended power of the cluster detection tests, which includes the usual power as a special case. Further, we define the profile of the extended power, which can be expected to play an important role in the evaluation and comparison of several cluster detection tests. The proposed extended power and its profile are demonstrated by two tests—Kulldorff's circular spatial scan statistic and a flexible spatial scan statistic proposed by Tango and Takahashi. Copyright © 2006 John Wiley & Sons, Ltd.
A cluster model for space–time disease counts
Authors: Yan Ping , Clayton Murray K. 
Published: February 2006

AbstractModelling disease clustering over space and time can be helpful in providing indications of possible exposures and planning corresponding public health practices. Though a considerable number of studies focus on modelling spatio‐temporal patterns of disease, most of them do not directly model a spatio‐temporal clustering structure and could be ineffective for detecting clusters. In this paper, we extend a purely spatial cluster model to accommodate space–time clustering. Inference is performed in a Bayesian framework using reversible jump Markov chain Monte Carlo. This idea is illustrated using data on female breast cancer mortality from Japan. A hierarchical parametric space–time model for mapping disease is used for comparison. Copyright © 2006 John Wiley & Sons, Ltd.
Statistical methods for the detection of spatial clustering in case–control data
Authors: Rogerson Peter A. 
Published: February 2006

AbstractIn this paper, I develop new approaches for the detection of spatial clustering in case–control data. One method is based upon drawing Thiessen polygons around each control. It is unnecessary to actually draw or compute the boundaries of the polygons; it is sufficient to count, for each control, the number of cases that are closer to that control than to any other control. A second method is similar to the Cuzick–Edwards method, which is based on counts of cases that are among thek‐nearest neighbours of cases, but is instead based upon the number of cases within a specified distance of cases. These first two methods are global methods in the sense that they provide a single statistic that measures the degree of spatial clustering. The third method suggests a local statistic, for tests of the null hypothesis of no spatial clustering around a prespecified focus. The method is based upon the cumulative χ2test, which is typically used to test whether cases are more prevalent than expected around a prespecified location. This is also extended to the case where all observational locations are considered as potential cluster locations and multiple testing is carried out. Each of the new methods is illustrated using data on childhood leukaemia and lymphoma cases in North Humberside. Copyright © 2006 John Wiley & Sons, Ltd.
Likelihood based tests for spatial randomness
Authors: Song Changhong , Kulldorff Martin 
Published: February 2006

AbstractMany different methods have been proposed to test the spatial randomness of a point pattern adjusting for an inhomogeneous background population. These tests can be classified into cluster detection tests, concerned with the detection and inference of local clusters, and global clustering tests, which collect evidence for clustering throughout the study region. This paper is mainly concerned about global clustering tests.Some tests for spatial randomness are based on likelihoods, which include the spatial and space–time scan statistics with variable window size and Gangnon and Clayton's weighted average likelihood ratio tests. Both of these tests perform well compared to other tests for cluster detection and global clustering, respectively. In this study, we develop other likelihood based tests for global clustering and we explore the use of different weight functions with these tests. The power of these tests is evaluated using simulated data set and compared with existing methods. Copyright © 2006 John Wiley & Sons, Ltd.
The practical application of a mathematical model to predict the outcome of pregnancies of unknown location
Authors: Kirk E. , Condous G. , Haider Z. , Lu C. , Van Huffel S. , Timmerman D. , Bourne T. 
Published: February 2006

AbstractObjectiveA logistic regression model has been developed previously to predict which pregnancies of unknown location (PULs) become ectopics. This model was based on the human chorionic gonadotropin (hCG) ratio (hCG 48 h/hCG 0 h). The aim of this study was to evaluate the model in an early pregnancy clinical setting.MethodsThis was a prospective non‐interventional observational study. Women classified as having a PUL had serum hCG and progesterone levels taken at presentation and 48 h later. At 48 h, nurse practitioners in the early pregnancy unit gave their subjective assessment of the likely pregnancy outcome based upon existing strategies to predict the outcome of PULs and their own previous experience. This was used as the basis for the clinical management of the women. The hormonal data were then entered into the model, which was available on the clinic computer in the form of a Microsoft Excel package, and the predicted outcome according to this model was recorded for each case. The model was weighted in favor of detecting an ectopic pregnancy at the expense of failing PULs and intrauterine pregnancies. All women were followed up until the final true diagnosis was established: a failing PUL, an intrauterine pregnancy or an ectopic pregnancy. The predicted outcome according to the model was compared with that of the subjective assessment of the expert operator and the true outcome after follow‐up.ResultsData were obtained from 357 women classified as having PULs. The final clinical outcomes were: 162 (45.4%) failing PULs, 166 (46.5%) intrauterine pregnancies and 29 (8.1%) ectopic pregnancies. Subjective assessment utilizing current strategies gave sensitivities of 79.3%, 92.8% and 87.0% for the detection of ectopic pregnancy, intrauterine pregnancy and failing PUL, respectively. The model detected ectopic pregnancy, intrauterine pregnancy and failing PUL with sensitivities of 82.8%, 86.8% and 73.5%, respectively. There were no adverse outcomes.ConclusionThis logistic regression model, based on the hCG ratio, can be used to predict the outcome of PULs, especially the ectopic pregnancies, with a high degree of certainty. It compares favorably with subjective assessment by experienced operators using current strategies to predict the outcome of PULs. The model can be used by those with limited knowledge or understanding of the behavior of serum biochemistry in the first trimester and in turn aid in the classification of PULs into those at low and those at high risk of ectopic pregnancy at 48 h. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal diagnosis of persistent left superior vena cava and its associated congenital anomalies
Authors: Berg C. , Knüppel M. , Geipel A. , Kohl T. , Krapp M. , Knöpfle G. , Germer U. , Hansmann M. , Gembruch U. 
Published: February 2006

AbstractObjectiveTo evaluate the associated conditions and the outcome of persistent left superior vena cava (PLSVC) detected in fetal life.MethodsThis was a retrospective review of all cases of PLSVC detected prenatally between 1998 and 2004 in two tertiary referral centers in Germany. Patient charts, ultrasound video recordings and still frames of all cases were reviewed for associated conditions and outcome.ResultsEighty‐two cases of PLSVC were detected in the study period. Thirty‐seven cases (45%) were associated with heterotaxy syndromes, 19 (23%) with isolated cardiac malformations, seven (9%) with aneuploidy, six (7%) with complex malformation syndromes and six (7%) with isolated extracardiac malformations. Seven cases (9%) had no associated condition. Eighty‐three percent of the fetuses in this series had associated cardiac malformations; the most frequent cardiac malformations in those with heterotaxy syndromes were complete atrioventricular septal defect (75%) and right outflow tract obstruction (58%). After exclusion of cases with heterotaxy, most congenital heart defects were ventricular septal defects (41%) and coarctation (34%). The outcome of PLSVC was determined solely by the associated conditions. After exclusion of terminated cases, heterotaxy syndromes as well as complete atrioventricular septal defects were associated significantly with perinatal and infant death. In contrast, all cases with isolated PLSVC or associated correctable extracardiac malformations survived and were doing well at the time of writing.ConclusionsPLSVC detected in fetal life has to be followed by a meticulous inspection of the fetal anatomy as it is frequently associated with heterotaxy syndromes, other cardiac/non‐cardiac malformations and aneuploidy that determine the outcome. Isolated PLSVC is a benign vascular anomaly and may not affect the outcome. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal detection of heart defects in a non‐selected population of 30 149 fetuses—detection rates and outcome
Authors: Tegnander E. , Williams W. , Johansen O. J. , Blaas H.‐G. K. , Eik‐Nes S. H. 
Published: February 2006

AbstractObjectivesTo evaluate the detection rate of congenital heart defects (CHD) in a non‐selected population and to follow outcome after diagnosis.MethodsAll 30 149 fetuses/newborns that were scheduled to deliver at our hospital between February 1991 and December 2001 were registered prospectively. Of these, 29 460 (98%) fetuses had a prenatal ultrasound scan at our center. The routine fetal examination at approximately 18 weeks' gestation included the four‐chamber view and the great arteries of the fetal heart. The follow‐up period was 2–13 years.ResultsOf 97 major CHDs, 55 (57%) were detected prenatally, 16% (9/55) prior to, 66% (36/55) at and 18% (10/55) after the routine scan. Forty‐four percent (19/43) of the isolated CHDs, 67% (36/54) of those with associated malformations and 48% (11/23) of the isolated ductal‐dependent CHDs were detected. Thirty‐eight percent (37/97) had an abnormal karyotype. Of the 55 major CHDs detected, 44% (24) of the pregnancies with lethal/serious fetal malformations were terminated, 15% (8) died in utero, 42% (23) were born alive and 27% (15) were still alive after 2 years. Of the 42 CHDs detected postnatally, 2% (1) were terminated for other reasons, 98% (41) were born alive and 81% (34) were still alive after 2 years.ConclusionsPrenatal detection of CHD is still a challenge, with a 57% detection rate only. Isolated defects are detected less frequently. The overall outcome suggests that the most severe defects are detected with the present screening setting; only 27% of the babies with major CHDs detected were still alive after 2 years. Data from long‐term follow‐up will be of importance for the counseling process. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Seasonality in neotropical populations of Plutella xylostella (Lepidoptera): resource availability and migration
Authors: Campos Wellington Garcia , Schoereder José H. , DeSouza Og F. 
Published: February 2006

AbstractThe present study aimed to verify (1) whether seasonal increases in neotropical populations of Plutella xylostella are directly provoked by regular influxes of migrants, and (2) whether temporal variation in food availability is the ecological process behind such predictable events. Over 3 years, plants that P. xylostella prefers were cultivated and irrigated in order to provide a continuous and abundant supply of food. Nevertheless, seasonal oscillations in the population of the herbivore still occurred. The hypothesis of seasonal availability of host plants could not explain the population pattern. In April, when the insect was practically extinct from the area, an artificial infestation (immigration) with 10,000 pupae established a precocious population. Therefore, the start of the natural cycles of population growth, during July–August, seems to be due to external factors, rather than an improvement in local conditions for resident individuals. In the beginning of the natural cycles, the increase in the density of adults significantly preceded the increase in immatures. Plutella xylostella does not diapause, and therefore immigration is the proximate cause of the seasonal population increases. Hypotheses about local factors are suggested to explain the decreasing phase of the predictable population cycles.
THE POLYNOMIAL NUMERICAL INDEX OF A BANACH SPACE
Authors: Choi Yun Sung , Garcia Domingo , Kim Sung Guen , Maestre Manuel 
Published: February 2006

AbstractIn this paper, we introduce the polynomial numerical index of order $k$ of a Banach space, generalizing to $k$-homogeneous polynomials the ‘classical’ numerical index defined by Lumer in the 1970s for linear operators. We also prove some results. Let $k$ be a positive integer. We then have the following:(i) $n^{(k)}(C(K))=1$ for every scattered compact space $K$.(ii) The inequality $n^{(k)}(E)\geq k^{k/(1-k)}$ for every complex Banach space $E$ and the constant $k^{k/(1-k)}$ is sharp.(iii) The inequalities$$ n^{(k)}(E)\leq n^{(k-1)}(E)\leq\frac{k^{(k+(1/(k-1)))}}{(k-1)^{k-1}}n^{(k)}(E) $$for every Banach space $E$.(iv) The relation between the polynomial numerical index of $c_0$, $l_1$, $l_{\infty}$ sums of Banach spaces and the infimum of the polynomial numerical indices of them.(v) The relation between the polynomial numerical index of the space $C(K,E)$ and the polynomial numerical index of $E$.(vi) The inequality $n^{(k)}(E^{**})\leq n^{(k)}(E)$ for every Banach space $E$.Finally, some results about the numerical radius of multilinear maps and homogeneous polynomials on $C(K)$ and the disc algebra are given.
NORM ESTIMATES OF THE PRE-SCHWARZIAN DERIVATIVES FOR CERTAIN CLASSES OF UNIVALENT FUNCTIONS
Authors: Kim Yong Chan , Sugawa Toshiyuki 
Published: February 2006

AbstractA sharp norm estimate will be given to the pre-Schwarzian derivatives of close-to-convex functions of specified type. In order to show the sharpness, we introduce a kind of maximal operator which may be of independent interest. We also discuss a relation between the subclasses of close-to-convex functions and the Hardy spaces.
SPECTRUM OF THE LAPLACIAN OF AN ASYMMETRIC FRACTAL GRAPH
Authors: Jordan Jonathan 
Published: February 2006

AbstractWe consider a simple self-similar sequence of graphs that does not satisfy the symmetry conditions that imply the existence of a spectral decimation property for the eigenvalues of the graph Laplacians. We show that, for this particular sequence, a very similar property to spectral decimation exists, and we obtain a complete description of the spectra of the graphs in the sequence.
THE NORM OF THE PRODUCT OF POLYNOMIALS IN INFINITE DIMENSIONS
Authors: Boyd C. , Ryan R. A. 
Published: February 2006

AbstractGiven a Banach space $E$ and positive integers $k$ and $l$ we investigate the smallest constant $C$ that satisfies $\|P\|\hskip1pt\|Q\|\le C\|PQ\|$ for all $k$-homogeneous polynomials $P$ and $l$-homogeneous polynomials $Q$ on $E$. Our estimates are obtained using multilinear maps, the principle of local reflexivity and ideas from the geometry of Banach spaces (type and uniform convexity). We also examine the analogous problem for general polynomials on Banach spaces.
LOW-REGULARITY SOLUTIONS FOR THE OSTROVSKY EQUATION
Authors: Huo Zhaohui , Jia Yueling 
Published: February 2006

AbstractThe well-posedness of the Ostrovsky equation is considered. Local well-posedness for data in $\tilde{H}^s(\mathbb{R})$ $(s\geq-\frac{1}{8})$ and global well-posedness for data in $\tilde{L}^{2}(\mathbb{R})$ are obtained.
LEGENDRIAN GRAPHS GENERATED BY TANGENTIAL FAMILY GERMS
Authors: Capitanio Gianmarco 
Published: February 2006

AbstractWe construct a Legendrian version of envelope theory. A tangential family is a one-parameter family of rays emanating tangentially from a regular plane curve. The Legendrian graph of the family is the union of the Legendrian lifts of the family curves in the projectivized cotangent bundle $PT^*\mathbb{R}^2$. We study the singularities of Legendrian graphs and their stability under small tangential deformations. We also find normal forms of their projections into the plane. This allows us to interpret the beak-to-beak perestroika as the apparent contour of a deformation of the double Whitney umbrella singularity $A_1^\pm$.
RIGIDITY OF HYPERSURFACES IN A EUCLIDEAN SPHERE
Authors: Wang Qiaoling , Xia Changyu 
Published: February 2006

AbstractThis paper studies topological and metric rigidity theorems for hypersurfaces in a Euclidean sphere. We first show that an $n({\geq}\,2)$-dimensional complete connected oriented closed hypersurface with non-vanishing Gauss–Kronecker curvature immersed in a Euclidean open hemisphere is diffeomorphic to a Euclidean $n$-sphere. We also show that an $n({\geq}\,2)$-dimensional complete connected orientable hypersurface immersed in a unit sphere $S^{n+1}$ whose Gauss image is contained in a closed geodesic ball of radius less than $\pi/2$ in $S^{n+1}$ is diffeomorphic to a sphere. Finally, we prove that an $n({\geq}\,2)$-dimensional connected closed orientable hypersurface in $S^{n+1}$ with constant scalar curvature greater than $n(n-1)$ and Gauss image contained in an open hemisphere is totally umbilic.
DIFFRACTIVE GEODESICS OF A POLYGONAL BILLIARD
Authors: Hillairet Luc 
Published: February 2006

AbstractWe define the notion of diffractive geodesic for a polygonal billiard or, more generally, for a Euclidean surface with conical singularities. We study the local geometry of the set of such geodesics of given length and we relate it to a number that we call classical complexity. This classical complexity is then computed for any diffractive geodesic. As an application we describe the set of periodic diffractive geodesics as well as the symplectic aspects of the ‘diffracted flow’.