bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the time constant and path length of first-passage percolation
Authors: Kesten Harry 
Published: April 2006

Let U be the distribution function of the passage time of an individual bond of the square lattice, and let pT be the critical probability above which the expected size of the open component of the origin (in the usual bond percolation) is infinite. It is shown that if (∗)U(0–) = 0, U(0) < pT, then there exist constants 0 < a, C1 < ∞ such that a self-avoiding path of at least n steps starting at the origin and with passage time ≦ an} ≦ 2 exp (–C1n).From this it follows that under (∗) the time constant μ (U) of first-passage percolation is strictly positive and that for each c > 0 lim sup (1/n)Nn(c) <∞, where Nn(c) is the maximal number of steps in the paths starting at the origin with passage time at most cn.
Two-armed bandits with a goal, II. Dependent arms
Authors: Berry Donald A. , Fristedt Bert 
Published: April 2006

One of two random variables, X and Y, can be selected at each of a possibly infinite number of stages. Depending on the outcome, one's fortune is either increased or decreased by 1. The probability of increase may not be known for either X or Y. The objective is to increase one's fortune to G before it decreases to g, for some integral g and G; either may be infinite.In Part I (Berry and Fristedt (1980)), the distribution of X is unknown and that of Y is known. In the current part, it is known that either X or Y has probability α of increasing the current fortune by 1 and the other has probability β of increasing the fortune by 1, where α and β are known, but which goes with X is not known. We show that optimal strategies exist in general and find all optimal schemes when α = 0 and when α + β = 1. In both cases myopic strategies are shown to be optimal. A counterexample is used to show that myopic strategies, while intuitively very appealing, are not optimal for general (α, β).
Estimating and testing selection: the two-alleles, genic selection diffusion model
Authors: Watterson G. A. 
Published: April 2006

The estimation, and testing for the presence, of a selective advantage of one allele over another is considered. It is assumed that a population's allele frequencies are known from some initial time until fixation of one or other allele occurs. The statistics needed to perform the estimation and testing are the heterozygosity of the population summed over all generations, and the observation of which allele fixes. It is shown that certain asymptotic probability distributions arise which are similar to those proved by Brown and Hewitt for statistical inference from diffusion processes, but their results assumed that the diffusion had a stationary density which is not the case for alleles which fix.The genetic diffusion may be transformed to Brownian motion with constant drift, and the inference questions concerning selection can be transformed to questions about the first exit of a Brownian motion from an interval. It is thus possible to construct significance tests, and to calculate the power of those tests, for detecting selection.
A geometric interpretation of the relations between the exponential and generalized Erlang distributions
Authors: Dehon Michel , Latouche Guy 
Published: April 2006

Linear combinations of exponential distribution functions are considered, and the class of distribution functions so obtainable is investigated. Convex combinations correspond to hyperexponential distributions, while non-convex combinations yield, among other, generalized Erlang distributions obtainable as sums of independent exponential random variables with different parameters.For a given number n of different exponential distributions, the class investigated is an (n – 1)-dimensional convex subset of the n-dimensional real vector space generated by the n distribution functions. The geometric aspect of this subset is revealed, together with the location of hyperexponential and generalized Erlang distributions.
Dynamic priority rules for cyclic-type queues
Authors: Browne Sid , Yechiali Uri 
Published: April 2006

A cyclic service system is composed of K channels (queues) and a single cyclically roving server who typically takes a positive amount of time to switch between channels. Research has previously focused on evaluating and computing performance measures (notably, waiting times) of fixed template routing schemes under three main service disciplines, the exhaustive, gated and limited service regimes.In this paper, probabilistic results are derived that allow control strategies and optimal policies to be considered for the first time. By concentrating on a new objective function, we are able to derive rules of index form amenable for direct implementation to dynamically control the system at suitably defined decision epochs. These rules utilize current system information, are of an adaptive nature, and are shown to emanate from a general physical principle.
Two remarks on insensitive stochastic models
Authors: Schassberger R. 
Published: April 2006

This paper contains two contributions to the insensitivity theory for generalized semi-Markov schemes, namely
(1)a detailed account of a close relationship between insensitive schemes and partially balanced discrete-state Markov chains, and(2)an extension of the notion of an insensitive scheme in order to incorporate insensitivity phenomena not previously covered.
A branching-process solution of the polydisperse coagulation equation
Authors: Spouge John L. 
Published: April 2006

The polydisperse coagulation equation

models irreversible aggregation of particles with varying masses. This paper uses a one-parameter family of discrete-time continuous multitype branching processes to solve the polydisperse coagulation equation when The critical time tc when diverges corresponds to a critical branching process, while post-critical times t> tc correspond to supercritical branching processes.
Multivariate linear time series models
Authors: Hannan E. J. , Kavalieris L. 
Published: April 2006

This paper is in three parts. The first deals with the algebraic and topological structure of spaces of rational transfer function linear systems—ARMAX systems, as they have been called. This structure theory is dominated by the concept of a space of systems of order, or McMillan degree, n, because of the fact that this space, M(n), can be realised as a kind of high-dimensional algebraic surface of dimension n(2s + m) where s and m are the numbers of outputs and inputs. In principle, therefore, the fitting of a rational transfer model to data can be considered as the problem of determining n and then the appropriate element of M(n). However, the fact that M(n) appears to need a large number of coordinate neighbourhoods to cover it complicates the task. The problems associated with this program, as well as theory necessary for the analysis of algorithms to carry out aspects of the program, are also discussed in this first part of the paper, Sections 1 and 2.The second part, Sections 3 and 4, deals with algorithms to carry out the fitting of a model and exhibits these algorithms through simulations and the analysis of real data.The third part of the paper discusses the asymptotic properties of the algorithm. These properties depend on uniform rates of convergence being established for covariances up to some lag increasing indefinitely with the length of record, T. The necessary limit theorems and the analysis of the algorithms are given in Section 5. Many of these results are of interest independent of the algorithms being studied.
On two classes of interacting stochastic processes arising in cancer modeling
Authors: Bartoszyński Robert , Puri Prem S. 
Published: April 2006

The processes X and Y are said to interact if the laws governing the changes of either of them at time t depend on the values of the other process at times up to t. For bivariate interacting Markov processes, their limiting behavior is analysed by means of an approximation suggested by Fuhrmann, consisting of discretizing time, and assuming that in each time interval the processes develop independently, according to the laws obtained by fixing the value of the other process at its level attained at the beginning of the interval.In this way the conditions for almost sure extinction, escape to ∞ with positive probability, etc., are obtained (by using the martingale convergence theorem) for state-dependent branching processes studied by Roi, and for bivariate processes with one component piecewise determined.
Dispersive ordering results
Authors: Lynch James , Mimmack Gillian , Proschan Frank 
Published: April 2006

A distribution F is less dispersed than a distribution G if for all .We generalize a characterization of dispersive ordering of Shaked (1982) concerning sign changes of Fc – G, where Fc is a translate of F. We then use this generalization plus total positivity to develop a simple proof of a characterization of dispersive distributions due to Lewis and Thompson (1981); a distribution H is dispersive if
ESS modelling of diploid populations I: anatomy of one-locus allelic frequency simplices
Authors: Hines W. G. S. 
Published: April 2006

In order to determine the robustness of the mean-covariance approach to exploring behavioural models of sexual diploid biological populations which are based on the evolutionarily stable strategy (ESS) concept, relevant features of the probability simplex of allelic frequencies for a population with genetic variability at a single locus are explored. Singularities and related properties of mappings from the space of allele frequencies to the space of strategy frequencies are examined, and related to a certain covariance measure of variability present in the population.A companion paper builds on this characterization to establish that previous claims of stability in fact hold under slightly weaker conditions than initially indicated. The pair of papers also determines conditions under which unstable equilibria can occur, and establishes that these conditions are exceptional in practice.
The Horizon of the Random Cone Field Under a Trend
Authors: Nosko Vladimir P. 
Published: April 2006

The horizon ξ T(x) of a random field ζ (x, y) of right circular cones on a plane is investigated. It is supposed that bases of cones are centered at points sn = (xn, yn), n = 1, 2, ···, on the (X, Y)-plane, constituting a Poisson point process S with intensity λ0 > 0 in a strip ΠT = {(x, y): – ∞< x <∞, 0 ≦ y ≦ T}, while altitudes of the cones h1, h2, · ·· are of the form hn = hn* + f(yn), n = 1, 2, ···, where f(y) is an increasing continuous function on [0,∞), f(0) = 0, and h1*, h2*, · ·· is a sequence of i.i.d. positive random variables which are independent of the Poisson process S and have a distribution function F(h) with density p(h).Let denote the expected mean number of local maxima of the process ξ T(x) per unit length of the X-axis. We obtain an exact formula for under an arbitrary trend function f(y). Conditions sufficient for the limit being infinite are obtained in two cases: (a) h1* has the uniform distribution in [0, H], f(y) = kyγ; (b) h1* has the Rayleigh distribution, f(y) = k[log(y + 1)]γ. (In both cases γ 0 and 0 < k∞.) The corresponding sufficient conditions are: 0 < γ< 1 in case (a), 0 < γ< 1/2 in case (b).
On the Distributions of Scan Statistics of a Two-Dimensional Poisson Process
Authors: Alm Sven Erick 
Published: April 2006

Given a two-dimensional Poisson process, X, with intensity λ, we are interested in the largest number of points, L, contained in a translate of a fixed scanning set, C, restricted to lie inside a rectangular area.The distribution of L is accurately approximated for rectangular scanning sets, using a technique that can be extended to higher dimensions. Reasonable approximations for non-rectangular scanning sets are also obtained using a simple correction of the rectangular result.
Typification of Linnaean plant names in Brassicaceae (Cruciferae)
Authors: Cafferty Steve , Jarvis Charles E. 
Published: April 2006

AbstractLectotypes, neotypes and epitypes are designated by 23 specialists for 86 previously untypified Linnaean plant names belonging to the family Brassicaceae (Cruciferae), and one epitype is designated for a previously lectotypified name. These newly proposed types support the current usage of the names concerned. Earlier but ineffective or supersedable type statements are discussed.
The status of South American Grimmia herzogii Broth. (Musci)
Authors: Delgadillo M. Claudio , Villaseñor R. José Luis 
Published: April 2006

AbstractGrimmia herzogii Broth. recently became the centre of a controversy among specialists who consider it separate from or synonymous with G. longirostris Hook. Cluster and ordination analyses have shown that by detailed morphological study, specimens with small ovate to ovate­lanceolate leaves and sinuous setae belong in G. herzogii. Those with comparatively large leaves and straight setae correspond to the concept of G. longirostris and include G. nigella Herz., a species described from heterogeneous materials.
A reassessment of the nomenclature of Matricaria L. and Tripleurospermum Sch. Bip. (Asteraceae)
Authors: Applequist Wendy L. 
Published: April 2006

AbstractThe nomenclature of the taxa often called Matricaria recutita L. (common chamomile) and Tripleurospermum perforatum (Mérat) Laínz (scentless mayweed) is discussed with reference to nomenclatural history, recent typifications, and the provisions of the International Code of Botanical Nomenclature. Justification is presented for the use of the name Matricaria chamomilla L. for common chamomile and the epithet inodorum rather than perforatum for scentless mayweed, both of which have been avoided in much recent literature. Varietal nomenclature of M. chamomilla is addressed, and the combination Tripleurospermum maritimum subsp. inodorum is validated.
Some applications of the theory of infinite capacity service systems to a single server system with linearly state dependent service
Authors: Conolly B. W. 
Published: April 2006

SummaryA certain single server queueing system with negative exponential service with mean rate nμ, when the system contains n customers, and Poisson arrivals, is formally equivalent to the infinite capacity system M/M/∞. This equivalence is exploited to yield in a very simple manner results for the single server system which were previously obtained by difficult analysis (see Hadidi (1969)).
On the optimal control of stationary diffusion processes with inaccessible boundaries and no discounting
Authors: Morton R. 
Published: April 2006

SummaryBecause there are no boundary conditions, extra properties are required in order to identify the correct potential cost function. A solution of the Dynamic Programming equation for one-dimensional processes leads to an optimal solution within a wide class of alternatives (Theorem 1), and is completely optimal if certain conditions are satisfied (Theorem 2). Necessary conditions are also given. Several examples are solved, and some extension to the multidimensional case is shown.
Two-stage output procedure of a finite dam
Authors: Zuckerman Dror 
Published: April 2006

The input of water into a finite dam is a Wiener process with positive drift. Water may be released at either of two possible rates 0 or M. At any time the output rate can be increased from 0 to M with cost KM, (K ≧ 0), or decreased from M to 0 with zero cost. There is a reward of A monetary units for each unit of output, (A > 0). We will consider the problem of specifying an optimal control output policy under the following optimal criteria:
(a)Minimum total long-run average cost per unit time.(b)Minimum expected total discounted cost.
Average delay in queues with non-stationary Poisson arrivals
Authors: Ross Sheldon M. 
Published: April 2006

One of the major difficulties in attempting to apply known queueing theory results to real problems is that almost always these results assume a time-stationary Poisson arrival process, whereas in practice the actual process is almost invariably non-stationary. In this paper we consider single-server infinite-capacity queueing models in which the arrival process is a non-stationary process with an intensity function ∧(t), t ≧ 0, which is itself a random process. We suppose that the average value of the intensity function exists and is equal to some constant, call it λ, with probability 1.We make a conjecture to the effect that ‘the closer {∧(t), t ≧ 0} is to the stationary Poisson process with rate λ ' then the smaller is the average customer delay, and then we verify the conjecture in the special case where the arrival process is an interrupted Poisson process.
The maximum in critical Galton–Watson and birth and death processes
Authors: Kämmerle K. , Schuh H.-J. 
Published: April 2006

In this paper recent results by Weiner [10] on Mn:= max{Z0, · ··, Zn} are strengthened and generalized, where (Zn)n is a critical Galton–Watson branching process with finite and positive offspring variance and Z0 ≡ 1. It is shown that

Explicit asymptotic bounds are given for with . If (Zn)n has a linear fractional offspring distribution, it can be embedded in a critical birth and death process (Ẑ t)t. Using martingale methods one obtains thereof.These results generalize to the case Z0 ≡ k.
Research Review: Child protection referrals and minority ethnic children and families
Authors: Chand Ashok , Thoburn June 
Published: April 2006

ABSTRACTThis paper reviews the research on the referral of minority ethnic children to child and family social work teams because of child protection concerns. Specifically, it focuses on those studies that have researched the referral stage of the child ‘in need’ and child protection systems, and explored differences in patterns of referral between the main ethnic groups that make up the UK population.
Associations between plasma adiponectin concentrations and liver histology in patients with nonalcoholic fatty liver disease
Authors: Targher Giovanni , Bertolini Lorenzo , Rodella Stefano , Zoppini Giacomo , Scala Luca , Zenari Luciano , Falezza Giancarlo 
Published: April 2006

SummaryObjectives  To explore associations between plasma adiponectin concentrations and liver histology in patients with nonalcoholic fatty liver disease (NAFLD).Design and patients  In a cross‐sectional study, we enrolled 60 consecutive NAFLD patients and 60 age‐, sex‐ and body mass index (BMI)‐matched healthy controls.Measurements  NAFLD (by liver biopsy), plasma adiponectin concentrations, insulin resistance (by homeostasis model assessment, HOMA‐IR) and metabolic syndrome (MetS) features.Results  NAFLD patients had a marked decrease in plasma adiponectin concentration (6·1 ± 2·8 vs. 13·6 ± 3·8 µg/ml, P < 0·001) compared with matched controls. MetS, as defined by the Adult Treatment Panel III (ATP III) criteria, and its individual components were more frequent among NAFLD patients. The marked differences in adiponectin concentrations that were observed between the groups were little affected by adjustment for age, sex, BMI, HOMA‐IR score and MetS components. Notably, decreased adiponectin levels were closely associated with the degree of hepatic steatosis, necroinflammation and fibrosis (P < 0·001 for all) among NAFLD patients. By logistic regression analysis, low adiponectin levels independently predicted hepatic steatosis [odds ratio (OR) 2·3, 95% confidence interval (CI) 1·5–5·8, P < 0·001] and necroinflammation (OR 3·1, 95% CI 1·9–7, P < 0·001), but not fibrosis (P = 0·07), after adjustment for age, sex, BMI, HOMA‐IR and MetS components.Conclusions  NAFLD patients have markedly lower plasma adiponectin concentrations than control subjects. Low adiponectin levels are strongly associated with the severity of liver histology, thus further supporting the hypothesis that adiponectin might be involved in the development of NAFLD.
Woody biomass production during the second rotation of a bio‐energyPopulusplantation increases in a future high CO2world
Authors: LIBERLOO MARION , CALFAPIETRA CARLO , LUKAC MARTIN , GODBOLD DOUGLAS , LUO ZHI‐BIN , POLLE ANDREA , HOOSBEEK MARCEL R. , KULL OLEVI , MAREK MICHAL , RAINES CHRISTINE , RUBINO MAURO , TAYLOR GAIL , SCARASCIA‐MUGNOZZA GIUSEPPE , CEULEMANS REINHART 
Published: April 2006

AbstractThe quickly rising atmospheric carbon dioxide (CO2)‐levels, justify the need to explore all carbon (C) sequestration possibilities that might mitigate the current CO2increase. Here, we report the likely impact of future increases in atmospheric CO2on woody biomass production of three poplar species (Populus albaL. clone 2AS‐11,Populus nigraL. clone Jean Pourtet andPopulus×euramericanaclone I‐214). Trees were growing in a high‐density coppice plantation during the second rotation (i.e., regrowth after coppice; 2002–2004; POPFACE/EUROFACE). Six plots were studied, half of which were continuously fumigated with CO2(FACE; free air carbon dioxide enrichment of 550 ppm). Half of each plot was fertilized to study the interaction between CO2and nutrient fertilization. At the end of the second rotation, selective above‐ and belowground harvests were performed to estimate the productivity of this bio‐energy plantation. Fertilization did not affect growth of the poplar trees, which was likely because of the high rates of fertilization during the previous agricultural land use. In contrast, elevated CO2enhanced biomass production by up to 29%, and this stimulation did not differ between above‐ and belowground parts. The increased initial stump size resulting from elevated CO2during the first rotation (1999–2001) could not solely explain the observed final biomass increase. The larger leaf area index after canopy closure and the absence of any major photosynthetic acclimation after 6 years of fumigation caused the sustained CO2‐induced biomass increase after coppice. These results suggest that, under future CO2concentrations, managed poplar coppice systems may exhibit higher potential for C sequestration and, thus, help mitigate climate change when used as a source of C‐neutral energy.
Does exposure to di(2‐ethylhexyl) phthalate in pre‐pubertal boars affect semen quality post‐puberty?
Authors: Spjuth Linda , Ljungvall Karl , Saravia Fernando , Lundeheim Nils , Magnusson Ulf , Hultén Fredrik , Rodríguez‐Martínez Heriberto 
Published: April 2006

SummaryDi(2‐ethylhexyl) phthalate (DEHP), a plastic softener used in polyvinyl chloride (PVC) products, has been ascribed to have toxic effects on animal reproduction. The present study aimed at determining potential late effects of pre‐pubertal oral exposure to DEHP on semen quality in young pigs. Ten pairs of cross‐bred male siblings were used. One brother in each pair became, at random, the test animal while the other acted as control. Test males were exposed to 300 mg/kg body weight (bw) of DEHP administered orally three times a week from 3 to 7 weeks of age. The control group was given placebo (water). Semen analyses started when the boars reached 6 months of age, with semen collected twice weekly, until animals were 9 months of age. Semen was evaluated for ejaculate volume, sperm concentration, total sperm count, sperm motility, sperm morphology (including presence of cells other than spermatozoa) and sperm plasma membrane integrity. Total sperm motility tended to be lower while local motility was higher in the DEHP‐exposed group compared with controls (p = 0.07) when assessed by computer‐assisted sperm analysis. The DEHP‐exposed group had a significantly (p < 0.05) lower percentage of spermatozoa with tailless, defective heads (at 7–8 months of age) and double‐folded tails (at 6–7, 7–8 and 6–9 months of age), compared with controls (albeit always under 5%). In summary, there were no obvious adverse effects of early oral exposure to 300 mg/kg bw of DEHP on sperm output and sperm quality in post‐pubertal young boars.