bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Habitat Occupancy of Orange‐Crowned Warblers in Managed Forests of Oregon and Washington, USA
Authors: KROLL ANDREW J. , DUKE STEVEN D. , RUNDE DOUGLAS E. , ARNETT EDWARD B. , AUSTIN KELLY A.
Published: June 2007

Abstract:As part of a habitat management planning process for commercially managed forests, we developed and evaluated habitat occupancy models for the orange‐crowned warbler (Vermivora celata), a conservation priority species in Oregon and Washington, USA. We used repeated surveys to classify a random sample of managed conifer stands at the McKenzie, PeEll, and Tolt study sites in western Oregon and Washington as either occupied or unoccupied during 1994–1995. We modeled occupancy and detection probabilities as a function of stand‐level habitat characteristics subject to manipulation by management activities. The best‐fitting model indicated that orange‐crowned warblers were 2 times (95% CI: 0.99‐5.1) and 3.8 times (95% CI: 1.5–6.1) as likely to occupy a stand for every 5% increase in evergreen shrub cover and 5‐m decrease in canopy lift (ht to lowest live branch), respectively. Management actions that maintain evergreen shrub cover >10% and permit development of low canopy lifts (4–10 m) should promote habitat occupancy by the orange‐crowned warbler in commercial forests in western Oregon and Washington.
Condition, Survival, and Cause‐Specific Mortality of Adult Female Mule Deer in North‐Central New Mexico
Authors: BENDER LOUIS C. , LOMAS LAURIE A. , BROWNING JASON
Published: June 2007

Abstract: From December 2001 to December 2004 we monitored 30–44 adult female mule deer (Odocoileus hemionus) annually to assess the factors affecting survival and cause‐specific mortality. We found adult female survival of 0.63 (SE = 0.08), 0.90 (SE = 0.05), and 0.91 (SE = 0.04), 2002–2004, respectively. Starvation was the most common cause of mortality, accounting for 11/23 mortalities. Mean ingesta‐free body fat (IFBF) levels of adult females in December were low (6–9%), despite few (0–13%) lactating adult females, indicative of extremely nutritionally deficient summer—autumn ranges throughout the study site. A priori levels of IFBF and rump body condition scores (rBCS) were higher in deer that survived the following year regardless of cause of mortality. Logistical analysis indicated that models containing individual body fat, rBCS, mean population body fat, winter precipitation, precipitation during mid‐ to late gestation, and total annual precipitation were related (x2 ≥ 9.1; P ≤ 0.003) to deer survival, with individual IFBF (β =‐0.47 [SE = 0.21]; odds ratio = 0.63 [0.42‐0.94]) and population mean IFBF (β = ‐1.94 [SE = 0.68]; odds ratio = 0.14 [0.04‐0.54]) the best predictors; with either variable, probability of dying decreased as fat levels increased. Fawn production was low (2–29 fawns/100 ad F) and, combined with adult survival, resulted in estimated population rates of increase of ‐35%, ‐5%, and +6% for 2002–2004, respectively. Deer survival and population performance were limited in north‐central New Mexico, USA, due to poor condition of deer, likely a result of limited food resulting from both drought and long‐term changes in plant communities. Precipitation during mid‐ to late gestation was also important for adult female survival in north‐central New Mexico.
Looking Back and Moving Forward: Historicising the Social Construction of Early Childhood Education and Care as National Work
Authors: Wong Sandie
Published: June 2007

Whilst it is possible to construct early childhood education and care (ECEC) in multiple ways, this article focuses on constructions of ECEC that have emerged within nationalist discourses privileged in advanced Western countries today, that is, ECEC as ‘national work’. Although these constructs are problematic and thus subject to criticism, the author shows that, historically, positioning ECEC as being of national benefit proved a powerful strategy for the early advocates of ECEC in New South Wales, Australia. The author argues that, despite their problematic nature, contemporary advocates of universal ECEC should strategically use nationalist and economic discourses.
Mothers, Teachers, Maternalism and Early Childhood Education and Care: Some Historical Connections
Authors: Ailwood Jo
Published: June 2007

Many current debates in Australia regarding the policy, politics and practicalities of childcare provision are embedded in dominant discourses of maternalism. This article places these debates within some historical contexts, emphasising the long history of these debates and the enduring centrality of maternalism — where the most revered of roles and relationships a woman can have is that of mother and one-on-one carer for her young child. In this article, the author discusses some of the historical points at which maternalism came to dominate early childhood education and care. The author considers Froebel, and the women who spread his word, nation building and the rise of psychology, making links between these and current debates in Australia.
Comparing Different Traditions of Teaching and Learning: What Can We Learn about Teaching and Learning?
Authors: Hudson Brian
Published: May 2007

This article explores differences between traditions in relation to teaching and learning and aims to highlight the ways in which the study of the Central European and Northern European traditions of Didaktik has offered new dimensions to and fresh insights on the notion of reflective practice. In particular these traditions are seen to offer tools and ways of thinking that help to recognise and hold the complexity of teaching-studying-learning processes. A key tool for the analysis of the complex relations between teacher, student and content is the Didaktik triad. This provides a relational framework which places teaching and associated design issues at the heart of teaching-studying-learning processes. Furthermore, it provides a means for teachers' thinking about the most basic how, what and why questions around their work. Another key aspect of such traditions is the emphasis that is placed upon meaning and intentionality from the outset of the process of preparation for teaching. Connections are also made with current thinking in the field of scholarship in teaching and learning. Finally, the article aims to highlights ways in which such tools and ways of thinking can help to inform approaches to development in the didactical, pedagogical and technological uses of information and communications technology for student-centred learning.
Trends in Research on Teaching and Learning in Schools: Didactics Meets Classroom Studies
Authors: Klette Kirsti
Published: May 2007

The relation between teaching, instruction and children's learning arises whenever models of the teaching—learning process are discussed or whenever problems of learning occur. Despite massive research efforts we still know little about how differences in learning activities are related to students' learning. The primacy of teachers and teaching as the primary subjects of research has contributed to a rather limited understanding of what goes on in schools and classrooms. Few studies of teachers and teaching have examined the extent to which differences in teacher effectiveness are related to differences in teachers' subject matter knowledge, and there is still a tendency to discuss issues of teaching and learning in general terms separated from the content that has been taught. In this article the author argues for the need to bridge studies of teaching and learning with studies of the subject involved — to establish a conversation between didactics and classroom studies. An analytical design and framework able to bridge the teaching—learning gap needs to be developed. Emerging technologies in video/audio documentation provide one chain of investigations for bridging how different thematic patterns are linked to instructional activities and interaction formats in classrooms.
Effects of stimulation of adenosine A2A receptors on lipopolysaccharide-induced production of reactive oxygen species by equine neutrophils
Authors: Sun Wan-chun , Moore James N. , Hurley David J. , Vandenplas Michel L. , Murray Thomas F.
Published: June 2007

Objective—To assess the anti-inflammatory effects of an adenosine analogue on lipopolysaccharide (LPS)-stimulated equine neutrophils.

Sample Population—Neutrophils obtained from 10 healthy horses.

Procedures—An adenosine analogue (5′-N-ethylcarboxamidoadenosine [NECA]) was tested for its ability to inhibit production of reactive oxygen species (ROS) in LPS-stimulated equine neutrophils. Selective adenosine receptor antagonists were used to identify the receptor subtype responsible for effects. To assess the mechanism of action of NECA, cAMP concentrations were measured, and effects of dibutyryl cAMP (a stable analogue of cAMP) and rolipram (a type 4 phosphodiesterase inhibitor) were investigated.

Results—NECA elicited concentration-dependent inhibition of ROS production that was inhibited by ZM241385, a selective adenosine A2A receptor antagonist; this effect of NECA was not affected by the adenosine A2B receptor antagonist MRS1706. Also, ZM241385 blocked NECA-induced increases in cAMP concentrations, whereas MRS1706 did not alter this effect of NECA. Rolipram potentiated NECA-induced inhibition of ROS production, and dibutyryl cAMP also inhibited ROS production.

Conclusions and Clinical Relevance—Activation of adenosine A2A receptors inhibited ROS production by LPS-stimulated equine neutrophils in a cAMP-dependent manner. These results suggest that stable adenosine A2A receptor agonists may be developed as suitable anti-inflammatory drugs in horses.
Association of expiratory airway dysfunction with marked obesity in healthy adult dogs
Authors: Bach Jonathan F. , Rozanski Elizabeth A. , Bedenice Daniela , Chan Daniel L. , Freeman Lisa M. , Lofgren Jennifer L. S. , Oura Trisha J. , Hoffman Andrew M.
Published: June 2007

Objective—To evaluate the effects of obesity on pulmonary function in healthy adult dogs.

Animals—36 Retrievers without cardiopulmonary disease.

Procedures—Dogs were assigned to 1 of 3 groups on the basis of body condition score (1 through 9): nonobese (score, 4.5 to 5.5), moderately obese (score, 6.0 to 6.5), and markedly obese (score, 7.0 to 9.0). Pulmonary function tests performed in conscious dogs included spirometry and measurement of inspiratory and expiratory airway resistance (Raw) and specific Raw (sRaw) during normal breathing and during hyperpnea via head-out whole-body plethysmography. Functional residual capacity (FRC; measured by use of helium dilution), diffusion capacity of lungs for carbon monoxide (DLCO), and arterial blood gas variables (PaO2, PaCO2, and alveolar-arterial gradient) were assessed.

Results—During normal breathing, body condition score did not influence airway function, DLCO, or arterial blood gas variables. During hyperpnea, expiratory sRaw was significantly greater in markedly obese dogs than nonobese dogs and Raw was significantly greater in markedly obese dogs, compared with nonobese and moderately obese dogs. Although not significantly different, markedly obese dogs had a somewhat lower FRC, compared with other dogs.

Conclusions and Clinical Relevance—In dogs, obesity appeared to cause airflow limitation during the expiratory phase of breathing, but this was only evident during hyperpnea. This suggests that flow limitation is dynamic and likely occurs in the distal (rather than proximal) portions of the airways. Further studies are warranted to localize the flow-limited segment and understand whether obesity is linked to exercise intolerance via airway dys-function in dogs.
Progression of radiographic evidence of osteoarthritis following tibial plateau leveling osteotomy in dogs with cranial cruciate ligament rupture: 295 cases (2001–2005)
Authors: Hurley Connie R. , Hammer Douglas L. , Shott Susan
Published: June 2007

Objective—To determine whether radiographic signs of osteoarthritis became progressively worse and tibial slope angle (TSA) changed substantially following tibial plateau leveling osteotomy for treatment of cranial cruciate ligament rupture in dogs.

Design—Retrospective case series.

Animals—295 dogs (373 stifle joints).

Procedures—Medical records were reviewed. Radiographs obtained before and 8 weeks after surgery were used to determine the degenerative joint disease (DJD) score, calculated as the sum of individual scores (0 through 3) assigned to 30 radiographic factors. Radiographs obtained immediately and 8 weeks after surgery were used to measureTSA. For dogs that underwent bilateral surgery, data for the first joint treated were used in analyses. Data for the second joint treated in dogs that underwent bilateral surgery were analyzed separately.

Results—A small, but significant, increase was found in mean DJD score 8 weeks after surgery, compared with mean preoperative score. An inverse relationship was found between preoperative DJD score and the difference between postoperative and preoperative DJD scores. Mean TSA 8 weeks after surgery was significantly higher than mean TSA immediately after surgery. Analysis of data for the second stifle joints in the 78 dogs that underwent bilateral surgery yielded similar results.

Conclusions and Clinical Relevance—Results suggested that there was a small, but measurable, increase in the severity of radiographic changes attributed to osteoarthritis in the stifle joints of dogs that underwent tibial plateau leveling osteotomy because of cranial cruciate ligament rupture.
Sleep evaluation in the symptomatic episode of recurrent hypersomnia
Authors: Feketeová Eva , Tormašiová Mária
Published: June 2007

Recurrent hypersomnia (RH) is a rare disorder characterized by episodes of hypersomnia, variously accompanied by behavioural and cognitive disturbances, compulsive eating behaviour and hypersexuality. Electrophysiologic evaluation of the sleep during symptomatic and asymptomatic periods of RH distinguishes RH from other primary sleep or mental disorders. Unique polysomnographic findings during the hypersomniac attack lasting 96 hours in a 16-year-old boy affected with primary RH are presented in this paper.
Defining a Literature
Authors: Kennedy Mary M.
Published: June 2007

As scholars and their audiences pursue standards of evidence, standards for literature reviews have also become salient. Many authors advocate “systematic” reviews and articulate standards for these. This article compares the bodies of literature derived from systematic and other types of review, which the author labels conceptual, and examines problems associated with different approaches to defining a body of literature. These problems include (a) defining the boundaries of the literature, (b) distinguishing studies from citations, (c) distinguishing literature from lore, (d) deciding which reporting venues to include, and (e) weeding out anomalous studies. The article demonstrates that although systematic reviews may remove some biases through their inclusion rules, they may introduce other biases through their exclusion decisions and may thwart conceptual advances in a field.
Highly Dispersed Mixed Zirconia and Hafnia Nanoparticles in a Silica Matrix: First Example of a ZrO2–HfO2–SiO2 Ternary Oxide System
Authors: Armelao L. , Bertagnolli H. , Bleiner D. , Groenewolt M. , Gross S. , Krishnan V. , Sada C. , Schubert U. , Tondello E. , Zattin A.
Published: May 2007

ZrO2 and HfO2 nanoparticles are homogeneously dispersed in SiO2 matrices (supported film and bulk powders) by copolymerization of two oxozirconium and oxohafnium clusters (M4O2(OMc)12, M = Zr, Hf; OMc = OC(O)–C(CH3)CH2) with (methacryloxypropyl)trimethoxysilane (MAPTMS, (CH2C(CH3)C(O)O)–(CH2)3Si(OCH3)3). After calcination (at a temperature ≥800 °C), a silica matrix with homogeneously distributed MO2 nanocrystallites is obtained. This route yields a spatially homogeneous dispersion of the metal precursors inside the silica matrix, which is maintained during calcination. The composition of the films and the powders is studied before and after calcination by using Fourier transform infrared (FTIR) analysis, X‐ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and laser ablation inductively coupled plasma mass spectrometry (LA‐ICPMS). The local environment of the metal atoms in one of the calcined samples is investigated by using X‐ray Absorption Fine Structure (XAFS) spectroscopy. Through X‐ray diffraction (XRD) the crystallization of Hf and Zr oxides is seen at temperatures higher than those expected for the pure oxides, and transmission electron microscopy (TEM) shows the presence of well‐distributed and isolated crystalline oxide nanoparticles (5–10 nm).
Fatal Loeffler's endocarditis due to hypereosinophilic syndrome
Authors: Chao Bo H. , Cline‐Parhamovich Karen , Grizzard John D. , Smith Thomas J.
Published: May 2007

Hypereosinophilic syndrome (HES) is a rare disorder that can manifest in various organ systems. We report the case of a 54‐year‐old woman with a remote history of seizure disorder who presented with early signs of right‐sided heart failure. Laboratory studies showed significant eosinophilia (8 × 109 l−1). Computed tomography showed heterogeneity of the liver, mild ascites, moderate pleural effusion, multiple small pulmonary emboli, and a large right ventricular mass. Cardiac magnetic resonance imaging demonstrated that the right ventricular mass was due to thrombus and extensive endomyocardial fibrosis, consistent with Loeffler's endocarditis. Bone marrow biopsy showed marked eosinophilia but no abnormal myeloid maturation or a lymphoproliferative disorder; flow cytometry showed no clonality. Extensive infectious, immunologic, and toxicological studies were negative. Despite resolution of peripheral eosinophilia with medical management, including corticosteroids and cytotoxic agents, anticoagulation for pulmonary emboli and ventricular thrombus, and conventional treatment for heart failure, she developed worsening anasarca and died from ventricular fibrillation within 4 weeks of presentation. Autopsy confirmed the diagnosis. Loeffler's endocarditis, usually a late manifestation of HES, is characterized by fibrous thickening of the endocardium, leading to apical obliteration and restrictive cardiomyopathy, resulting in heart failure, thromboembolic events, or atrial fibrillation. HES is a potentially fatal disease with less than 50% reported 10‐year survival. This case presentation is unusual in its rapidly progressive course leading to sudden death. Am. J. Hematol. 82:920–923, 2007. © 2007 Wiley‐Liss, Inc.
Zur Frage des Vorhandenseins von festem Stickstoff in der Erdatmosphäre
Authors: Pelzer Heinz
Published: May 2007

Mit Hinblick auf die Vegardsche Nordlichthypothese wird untersucht, ob die höheren Atmosphärenschichten im Strahlungsgleichgewichte mit der Erd‐ und Sonnenstrahlung eine Temperatur erreichen können, die unterhalb des Schmelzpunktes von Stickstoff (36° K) liegt. Es ergibt sich, daß diese Temperatur auch auf der Nachtseite der Erde nur unter folgenden Voraussetzungen erreicht werden könnte: Bei Annahme einer gleichförmigen (grauen) Absorption müßten die tieferen Atmosphärenschichten die Erdstrahlung so gut wie vollkommen (bis auf einen Bruchteil 10−1430) absorbieren, oder aber selektiv bloß im Ultrarot mindestens 99,5 Proz. der Strahlung dieses selektiv absorbierten Spektralbereiches. Da diese Voraussetzungen schwerlich zutreffen können, scheint die Vegardsche Nordlichthypothese aus thermodynamischen Gründen allein schon abzulehnen zu sein.
Behavior of composite materials under microorganisms of soil
Authors: Legonkova O. A. , Selitzkaya O. V.
Published: May 2007

The article is devoted to the investigation of the dynamics of fungi and bacteria growth in different types of soil in dependence on the presence of composite materials based on polymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Studies on the preparation of branched polymers from styrene and divinylbenzene
Authors: Honglan Tang , Fanghong Gong , Chunlin Liu , Qiang Ren , Yang Yang , Bibiao Jiang , Chao Liu , Jianhai Chen
Published: May 2007

The self‐condensing vinyl polymerization of styrene and an inimer formed in situ by atom transfer radical addition from divinylbenzene and 2‐bromoisobutyl‐tert‐butyrate using atom transfer radical polymerization technique was studied. To study the polymerization mechanism and achieve high molecular weight polymer in a high polymer yield, the polymerization was carried out in bulk at 80°C. Proton nuclear magnetic resonance (1H‐NMR) spectroscopy and gel permeation chromatography (GPC) coupled with multiangle laser light scattering (MALLS) were used to monitor the polymerization process and characterize the solid polymers. It is proved that the polymerization shows a “living” polymerization behavior and the crosslinking reaction has been restrained effectively due to the introduction of styrene. Polymers with high molecular weight (Mw.MALLS > 105) can be prepared in high yield (near 80%). Comparison of the apparent molecular weights measured by GPC with the absolute values measured by MALLS indicates the existence of branched structures in the prepared polymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
The effect of photoperiod and prey density on long‐term survival of larvae—a data analytic approach where no parametric model is assumed and individual follow‐up is not available
Authors: Schechtman Edna , Wax Yochanan , Tandler Amos
Published: May 2007

A data analytic approach for analysing differences in long‐term survival and identifying treatment combinations which provide high survival in a factorial design set‐up is presented. The methods are particularly appropriate when individual follow‐up data are not available and no simple model fits the data. Upper quantiles of the survival distributions are used as the response variable and within and between‐treatment differences are analysed through both a structured ANOVA model and subset‐selection procedure. The methods are used to study the effects of several photoperiods and prey density treatments on the long‐term survival of the larvae of gilthead seabream,Sparus aurata.The two approaches used are shown to lead to similar conclusions.
A strategy for analysing mixed and pooled exponentials
Authors: Grego John , Hsi Hsiu‐Li , Lynch James
Published: May 2007

It is shown that a linear plot of the mean residual life on the failure rate characterizes the mixture of two exponentials. This plot is used to estimate the two components in the mixing distribution with the two largest mixing proportions. The EM algorithm is then used with these as initial values to obtain the MLE. Gradient plots are used to see if a higher‐order fit is needed. A heuristic is given on how to use the gradient plots to identify components in the higher‐order fit when this is the case. Graphs of an assignment function are then used to determine if the data are from a mixed model or simply the effect of pooling.
Mixed parallel processors with interdependent blocking
Authors: Van Dijk Nico M.
Published: May 2007

This paper studies a system of parallel service facilities or processors with mixed exponential and non‐exponential queues, a non‐exponential finite source input and interdependent arrival as well as departure blocking such as due to a common pool or shared resource. A concrete invariance condition upon the blocking protocol is provided. Under this condition the stationary busy source distribution is shown to be of an insensitive product form. The result unifies and extends known product form results as will be illustrated by several examples.
Searching for knowledge in a world flooded with facts
Authors: Michalski R. S.
Published: May 2007

The wide availability of computer technology and large electronic storage media has led to an enormous proliferation of databases in almost every area of human endeavour. This naturally creates an intense demand for powerful methods and tools for data analysis. Current methods and tools are primarily oriented toward extracting numerical and statistical data characteristics. While such characteristics are very important and useful, they are often insufficient. A decision maker typically needs an interpretation of these findings, and this has to be done by a data analyst. With the growth in the amount and complexity of the data, making such interpretations is an increasingly difficult problem. As a potential solution, this paper advocates the development of methods for conceptual data analysis. Such methods aim at semi‐automating the processes of determining high‐level data interpretations, and discovering qualitative patterns in data. It is argued that these methods could be built on the basis of algorithms developed in the area of machine learning. An exemplary system utilizing such algorithms, INLEN, is discussed. The system integrates machine learning and statistical analysis techniques with database and expert system technologies. Selected capabilities of the system are illustrated by examples from implemented modules.
Recent advances in automatic classification
Authors: Michaud P.
Published: May 2007

Traditional classification methods are divided into two broad types: hierarchical methods and non‐hierarchical methods in which the number of classes has to be fixed in advance. Both methods can handle both quantitative and qualitative data. A third type finds a partition optimizing a linear classification criterion (e.g. the Condorcet criterion) in which the number of classes does not have to be fixed in advance, but the data must be qualitative. A recent generalization, the ‘S theory’ can handle simultaneously both quantitative and qualitative data, and both linear and non‐linear classification criteria (in the space of paired comparisons of elements). With this ‘S theory’ the partition is obtained in order n (in terms of memory space and elementary operations), n being the number of elements to classify.
A fuzzy interpretation for an ecological site classification case
Authors: El‐Shishiny Hisham , Ghabbour Samir I.
Published: May 2007

A case study is presented in which four sites in the Jebel Marra highlands in western Sudan and four sites from the Erkowit plateau in eastern Sudan are classified according to a list of collected soil fauna taxa and their densities. The fuzzy isodata algorithm was used satisfactorily to classify the sites in accordance with a biologist's observations. Comparison of the fuzzy classification with the results of some ordination methods is also given.
Inference in lognormal multidimensional diffusion processes with exogenous factors: Application to modelling in economics
Authors: Gutiérrez R. , Angulo J. M. , González A. , Pérez R.
Published: May 2007

The multidimensional lognormal diffusion process with exogenous factors is treated using the Kolmogorov equations, and the mean vector and covariance matrix are estimated using discrete sampling by the maximum‐likelihood method. Also, this process is constructed as a solution of a multidimensional stochastic differential equation, and an estimation is made through the maximum‐likelihood method to infer the parameters of the exogenous factors, this time using continuous sampling. Finally, a test for a hypothesis based on these parameters is constructed.
Mixture decomposition via the simulated annealing algorithm
Authors: Ingrassia S.
Published: May 2007

This paper presents the problem of the evaluation of the maximum likelihood estimator, when the likelihood function has multiple maxima, using the stochastic algorithm called ‘simulated annealing’. Analysis of the particular case of the decomposition of a mixture of five univariate normal distributions shows the properties of this methodology with respect to the E—M algorithm. The results are compared considering some distance measures between the estimated distribution functions and the true one.
A simple proof for the matrix‐geometric theorem
Authors: Latouche Guy
Published: May 2007

For block‐partitioned matrices of the GI/M/1 type, it has been shown by M. F. Neuts that the stationary probability vector, when it exists, has a matrix‐geometric form. We present here a new proof, which we believe to be the simplest available today.
Considerations on modelling the market for softwood lumber in the United States
Authors: Uri Noel D. , Boyd Roy
Published: May 2007

The analysis in this paper looks at two important elements in modelling the market for timber in the United States. First, the issue of directional causality between price and quantity and its implications in a modelling effort is investigated. Second, the extent of the geographic market for timber is discussed and a method of detecting it is suggested. The method for detecting the extent of the geographical market is tractable and can be applied in a straightforward way. Both considerations are applied to the softwood lumber market in the United States.
Discriminant versus rough sets approach to vague data analysis
Authors: Krusińska Ewa , Slowinski Roman , Stefanowski Jerzy
Published: May 2007

This paper presents a comparative study of the use of two different methods of data analysis on a common set of data. The first is a method based on rough sets theory and the second is the location model method from the field of discriminant analysis. To investigate the comparative performance of these methods, a set of real medical data has been used. The data considered are of both discrete and continuous character. During the comparison, particular attention is paid to data reduction and to the derivation of decision rules and classification functions from the reduced set.
Complexity models in financial markets
Authors: Landes Thomas , Loistl Otto
Published: May 2007

In this approach, the complexity of the self‐organizing microstructure of the stock exchange is explicitly taken into consideration: the process of offers and trades as well as the adjustment of individual expectations are modelled with help of a (stochastic) jump process. Its abilities are illustrated by modelling the continuous quotations of asset prices at an auction type stock exchange. The functional form of the transition (hazard) rates is chosen to reflect the individual preferences and expectations as well as the economic environment. The model is described in detail and examples of Monte Carlo simulation results are presented.
On a stochastic model for particle sedimentation in fluids
Authors: Hesse C. H.
Published: May 2007

The engineering sciences have long been interested in models describing the settling (or sedimentation) of particle ensembles in viscous fluids. From a theoretical point of view, sedimentation constitutes a two phase many‐body phenomenon with complex interaction and as such has proved to be quite inaccessible to modelling attempts with relevance in applications. A stochastic model was introduced by Pickard and Tory in 1977 and was subsequently revised. In this paper we expand and refine the stochastic model and present a satisfactory model‐fitting procedure and parameter estimators based on transit times of sedimenting particles.
Manufacturing cell formation under capacity constraints
Authors: Xie Xiaolan
Published: May 2007

The cell formation problem is addressed for a manufacturing system containing groups of identical machines. Various part types are produced. The manufacture of a part requires a sequence of operations and each operation can be performed by any machine of a given type. The cell formation problem consists in grouping machines into cells and assigning operations to machines so as to minimize the intercell traffic while satisfying machine capacity constraints and other technical constraints. An important feature of this problem is that machines of the same type may be assigned to different cells. Since the problem is NP‐hard, heuristic solutions are proposed and numerical experiences show that the proposed algorithms lead to near‐optimal solutions.
Stochastic dispersive transport: An excursion from statistical physics to automated production line design
Authors: Hongler M.‐O.
Published: May 2007

Both the sediment transport dynamics and the population level of a buffer in automated production line systems can be described by the same class of stochastic differential equations. The ubiquitous noise is generated by continuous time Markov chains. The probability densities which describe the dynamics are governed by high‐order hyperbolic systems of partial differential equations. While this hyperbolic nature clearly exhibits a non‐diffusive character of the processes (diffusion would imply a parabolic evolution of the probability densities), we nevertheless can use a central limit theorem which holds for large‐time regimes. This enables analytical estimations of the time evolution of the moments of these processes. Particular emphasis is devoted to non‐Markovian, dichotomous alternating renewal processes, which enter directly into the description of the applications presented.
Non‐parametric vs parametric forecasting in time series: A computational point of view
Authors: Carbon M. , Delecroix M.
Published: May 2007

The finite sample behaviour of non‐parametric predictors is considered for time series. Among other results, it is shown by simulation arguments that such predictors compare favourably with predictors based on parametric models in the spirit of the usual Box‐Jenkins approach.
Estimating a linear functional relationship under linear constraints for errors
Authors: Lappi Juha , Sievänen Risto
Published: May 2007

Maximum likelihood estimates for parameters in a linear functional relationship are derived when the errors are also linearly related for each observation. This is approximately the case, for example, when both variables are smooth functions of time and their values are recorded as an experimental unit reaches a certain state. This kind of model specification was needed to describe how the timing of growth cessation of trees depends on night length and temperature sum. If the slope in the constraint equation for errors varies, then an iterative estimation procedure is needed. The estimation method is extended for a two‐phase linear model.
Estimating household purchase rates for consumer nondurable goods
Authors: Jain Dipak C. , Vilcassim Naufel J.
Published: May 2007

Understanding the purchase rates of households for frequently purchased packaged goods is an important element in developing effective marketing strategies. Previous researchers have attempted to estimate these rates by assuming that the time between purchases is a random variable that follows some common parametric probability distribution such as the exponential or Weibull distribution. Recent research has shown that for many frequently purchased packaged goods, the interpurchase times cannot be adequately described by these commonly used probability distributions. In this study we demonstrate how household purchase rates can be estimated in a robust manner using a generalized semiparametric approach that obviates the need for specifying a parametric form for the distribution of interpurchase times. The motivation being that often there is no theory of household purchase behaviour that specifiesa priorithe probability distribution underlying the interpurchase times. Our empirical results indicate that, for the data analysed, the household purchase rates exhibit a regular pattern that cannot be recovered by probability distributions often used in previous research. Further, marketing actions taken by sellers do indeed influence household purchase behaviour.
Parameter estimation in multi–component systems with failure interaction
Authors: Murthy D. N. P. , Wilson R. J.
Published: May 2007

In multi–component systems, failure of a component often affects one or more of the remaining components of the system. This type of interaction between components is called ‘failure interaction’. In this paper we consider two failure interaction models and study the problem of estimating the parameters of these models.
A reliability application of a mixture of inverse gaussian distributions
Authors: Smith Charles E. , Lánský Petr
Published: May 2007

A mixture of inverse Gaussian distributions (IGDs) is examined as a model for the lifetime of components. The components differ in one of three ways: in their initial quality, rate of wear, or variability of wear. These three cases are well represented by the parameters of the IGD model. The mechanistic interpretation of the IGD as the first passage time of Brownian motion with positive drift is adopted. The parameters considered are either dichotomous or continuous random variables. Parameter estimation is also examined for these two cases. The model seems to be most appropriate when the single IGD model fails due to heterogeneity of the initial component quality.
A systems approach to the calibration of deterministic dynamic nonlinear simultaneous equation models with incomplete data
Authors: Hartley Michael J.
Published: May 2007

This paper develops an interactive three–stage systems approach for the calibration of the structural parameters and missing data within a deterministic, dynamic non–linear simultaneous equations model under arbitrary configurations of incomplete data. In Stage One, we minimize a quadratic loss function in the differences between the actual endogenous variables and the predicted solution values, relative to any feasible choice of the structural parameters. Missing exogenous variables and initial endogenous variables are treated as additional parameters to be calibrated; whereas missing current endogenous variables are treated by the missing data updating condition, in which the current solution values iteratively and sequentially replace those absent. Stage One may or may not lead to unique calibrations of the structural parameters—a fact that can be monitoreda posterioriusing singular value decompositions of the relevant Jacobian matrix. If not, there is an equivalence class of parameter values, all of which result in the same loss function value. If Stage Two is necessary, we attempt to exploit the non–linearity and simultaneity of the structural system to extract further information about the parameters from the same database, by minimizing the distance between the restricted and unrestricted reduced forms, while constraining the parameters also to lie within the Stage One equivalence class. This requires the use of higher–order numerical derivatives, and probably restricts its use in all but the simplest of cases to the next generation of supercomputers with massive numbers of parallel processors and much larger word–sizes. In Stage Three, various methods by which the original structural model can be simplified, given a non–unique Stage One calibration, are entertained.
Joint availability of systems modelled by finite semi–markov processes
Authors: Csenki A.
Published: May 2007

Consider a repairable system at the time instants t and t + x, where t, x ≥0. The joint availability of the system at these time instants is defined as the probability of the system being functional in both t and t + x. A set of integral equations is derived for the joint availability of a system modelled by a finite semi–Markov process. The result is applied to the semi–Markov model of a two–unit system with sequential preventive maintenance. The method used for the numerical solution of the resulting system of integral equations is a two–point trapezoidal rule. The system of implementation is the matrix computation package MATLAB on the Apple Macintosh SE/30. The numerical results obtained by this method are shown to be in good agreement with those from simulation.
Estimation and filtering on a doubly stochastic poisson process
Authors: Valderrama Mariano J. , Jimenez Francisco , Gutierrez Ramon , Martinez‐Almecija Alfredo
Published: May 2007

An explicit formula for the characteristic function of a doubly stochastic Poisson process is derived in this paper by means of the harmonic decomposition of its intensity function that we suppose to be Gaussian. The statistical moments are then obtained, as well as the sample function density of the process. These results are applied to estimate the parameters of several well‐known processes. Finally, a linear filtering procedure for the intensity function is developed and the algorithm is implemented by computers.
Optimal control of dams
Authors: Abdel‐Hameed Mohamed , Nakhi Yasmin
Published: May 2007

Assume that a dam has a capacity V. Its water input I={It, t ϵ [0, ∞)}], is assumed to be a diffusion process. The water is released at one of two rates 0 and M units of water per unit of time. The release rate is 0 until the water reaches level λ(0 < λ < V), when the water is released at rate M until it reaches level λ, (0 ≤ τ < λ). Once the level λ is reached, the release rate remains at zero until level λ is reached again, and the cycle is repeated. Under general cost structure, we discuss and review some of the most recent work in the area of optimal control of dams with release policies of the above type; we also discuss some new results and corrections to some existing results.
A stopping rule for a compound poisson random variable
Authors: Randolph Paul , Sahinoǧlu Mehmet
Published: May 2007

An optimal empirical Bayesian stopping rule for the Poisson compounded with the geometric distribution is developed and applied to the problem of the sequential testing of computer software. For each checkpoint in time, either the software satisfies a desired economic criterion, or else the software testing is continued.
Optimal dynamic equilibrium in insurance policies
Authors: Page Dominique , Tremolieres Raymond
Published: May 2007

Insurance companies sell contracts of various types each of them having a specific probability of return. Insurers may also own, at the same time, several insurance contracts which evolve through time. In this context, expectation and variance of the free reserves appear as functions of the number of customers in different classes as well as their evolution. Assuming that the customer system can be formulated as an open Markov one characterized by free entry, it is interesting to seek the optimal new customer distribution over the different customer classes j, which permits the minimization of the variance of free reserves for a desired average level of free reserves at a given time horizon. It is shown that, under some conditions, the customer system converges to an optimal growth steady state.
The effects of quantized data
Authors: Jewell William S.
Published: May 2007

The effects of quantized data upon parameter estimation are investigated by re‐examining a variety of simple and complicated risk models previously studied by the author. In spite of this unifying theme, no general principles arise, except for demonstrating that estimation in models with two or more parameters can lead to unpredictable results, with or without the introduction to discrete data. In fact, certain common actuarial models are shown always to have poor estimation properties, even using substantial amounts of continuous data The paper concludes with a plea for the redevelopment of classical models that are continuous in nature, rather than perpetuating the current discrete multi‐parameter models, whose estimation properties are poor, since modern technology now permits inexpensive capture of all kinds of continuous data.
Balanced credibility estimation
Authors: Neuhaus Walther
Published: May 2007

This paper shows how a multivariate credibility estimator should be adjusted to satisfy a linear balancing constraint.
Applications of risk theory and multivariate analysis in insurance practice
Authors: Niggemeyer B. , Radtke M. , Reich A.
Published: May 2007

Segmentation strategies and differentiated preselection in underwriting call for new portfolio management techniques, the use of which is becoming increasingly widespread amongst insurance companies faced with growing competitive pressure. In recent years, mathematical procedures have been developed for this purpose and the applicability of existing procedures for use in insurance practice has been recognized. The present paper elucidates various methods for determining the aggregate claims distribution, which describes the performance and volatility of a portfolio. There then follows a presentation of multivariate methods, particularly generalized linear models and methods applying variance and discriminant analysis, which facilitate the analysis of more narrowly defined segments and subportfolios. Finally, the paper contains a description of applications used by numerous insurance companies, primarily for motor and property portfolios.
Operational time and a fundamental problem of insurance in a data‐rich environment
Authors: Reid D. H.
Published: May 2007

A problem of current concern in the assessment of claims experience in non‐life insurance is addressed. The problem relates to the interface of two well‐defined areas of actuarial activity, namely reserving and rating. A model is proposed that permits the analysis of claim settlement experience in such a way as to allow for variations in settlement rate, proportions of nil claims and variations from year to year in a risk‐factorial background. From this, the reserving approach may be developed coherently into the area of risk costing for rating purposes.
Stochastic modelling of household behaviour before, during and after a consumer price promotion
Authors: Takada Hirokazu , Chen Yu‐Min
Published: May 2007

A stochastic model is developed to study household behaviour with regard to purchase quantity, brand choice and purchase timing before, during and after a price change and a price promotion such as price‐offs and price‐cuts. The basic assumption of the model is that price promotion and levels of consumer inventory influence a household's purchase‐timing and brand‐switching decisions. The model incorporates market segments and brand switching on aggregated demand for the brands by the use of multivariate Markov processes. A transient stochastic model is employed to analyse the dynamic process of household behaviour before, during, and after a price promotion. The interpurchase time that is derived from the model does not require any assumptions and is not independently, identically distributed. An empirical analysis using the Information Resources Incorporated cracker data indicated that (1) price promotion does affect household purchase of the brand and (2) households with larger family size tend to purchase promoted items. We conjecture that households with larger family size take advantage of the lower price of the promoted brands while smaller households tend to remain loyal to one brand.
Biotin‐related abnormalities in human metabolism
Authors: Nyhan William L.
Published: May 2007

Recent work has led to the discovery that two severe hereditary human pathologies are caused by biotin deficiency. Significantly, administration of pharmacologic doses of biotin can provide clinically effective treatment. Both diseases are autosomal recessive in inheritance but differ in their associated enzymatic deficiencies. The clinical, enzymatic, and genetic characteristics of these pathologies are reviewed here.