bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracellular ATP activates nuclear translocation of ERK1/2 leading to the induction of matrix metalloproteinases expression in human endometrial stromal cells
Authors: Chang Shu-Ju , Wang Tao-Yeuan , Lee Yi-Hsuan , Tai Chen-Jei
Published: May 2007

ATP has been shown to activate the mitogen-activated protein kinase (MAPK) signaling pathway in various systems. However, little is known about the signaling events and the effects in human endometrial stromal cells (hESCs). The present study examined the effect of ATP on activating MAPKs and its subsequent events in hESCs. This study demonstrated the expression of the P2U/P2Y2 receptor in hESCs by reverse transcription-PCR (RT-PCR). A PCR product with a sequence identical to the reported 599 bp P2U/P2Y2 receptor cDNA was obtained. Western blot analysis, using a monoclonal antibody against the phosphorylated forms of ERK1/2, demonstrated that ATP activated MAPK in a dose- and time-dependent manner. Confocal microscopy showed an evident nuclear translocation of phosphorylated ERKs after 10 μM ATP treatment, but this effect was blocked by PD98059. To study the gene(s) induced by exogenous ATP, mRNA was extracted from hESCs in the presence or absence of 10 μM ATP. The gene array for 96 genes associated with members of human matrix metalloproteinases (MMPs) and adhesion molecules revealed that the expression of MMP-2, -3, -10, and -24 genes was increased and the effect was attenuated by PD98059. Furthermore the effects of ATP on the expression of MMP genes were confirmed by semiquantitative RT-PCR. To our knowledge, this is the first demonstration of the ATP-induced nuclear translocation of phospho-ERK1/2 that mediates MMPs gene expression in human endometrial cells. These results support the notion that the ERK1/2 signaling pathway is involved in mediating ATP actions in the human reproductive system.
Expression of extracellular matrix proteins and integrins in rat adrenal gland: importance for ACTH-associated functions
Authors: Otis Mélissa , Campbell Shirley , Payet Marcel D , Gallo-Payet Nicole
Published: May 2007

The expression of main extracellular matrix (ECM) and their integrins were studied in the adult rat adrenal gland. Collagen I, IV (CI, CIV), laminin (LN) and fibronectin (FN) expression was observed surrounding each glomerulosa cell and as long fibrils between the cords of fasciculata cells. In the medulla, FN was present around chromaffin cells or bordering blood vessels. Integrin α2, α3 and α5 were present mainly in the cortex, while α1 was present in the medulla. In culture, all ECM favoured proliferation of both glomerulosa and fasciculata cells, while protein synthesis was lower on FN and LN in glomerulosa cells. CIV promoted ACTH-induced proliferation whereas FN favoured ACTH-induced protein synthesis in glomerulosa cells. Except for LN, ECM increased expression of 3β-hydroxysteroid dehydrogenase and enhanced basal aldosterone, although corticosterone secretion was only enhanced by CI and CIV. In fasciculata cells, the potency of ACTH-induced cAMP production was lower on ECM, compared with plastic. Moreover, ACTH, but not ECM, activated mitogenic-activated protein kinase p38 and stress-activated protein kinases. Glomerulosa and fasciculata cells grown on CI and CIV had a polygonal morphology, while cells grown on LN appeared as clusters of small rounded cells. On FN, the glomerulosa cells exhibited polygonal morphology while fasciculata cells appeared as clusters of small rounded cells. Together, these results indicate that ECM modulates basal and ACTH-induced cell functions, with FN, CI and CIV specifically favouring steroid secretion, as opposed to LN which inhibits secretion while promoting proliferation.
Endothelin-2 induces oviductal contraction via endothelin receptor subtype A in rats
Authors: Al-Alem Linah , Bridges Phillip J , Su Wen , Gong Ming C , Iglarz Marc , Ko CheMyong
Published: May 2007

Proper function of the oviduct is critical to reproductive success with regulated contraction and relaxation facilitating transportation of the germ cells to the site of fertilization. Endothelin-2 (EDN2) is a potent vasoconstrictor produced by granulosa cells of the preovulatory follicle at the time of ovulation; however, whether this gonadotropin surge-induced peptide played a role in facilitating germ cell transportation by inducing oviductal contraction was unknown. The objectives of these experiments were (1) to determine whether the endothelin receptor system was present in the oviduct, (2) to test the hypothesis that EDN2 induces oviductal contraction via a specific endothelin receptor subtype, (3) to determine, as a possible alternate source of the ligand, whether mRNA for EDN2 was expressed in cumulus–oocyte complexes (COCs) within the oviduct, and (4) to determine whether EDN2 could overcome prostaglandin E2 (PGE2)-induced oviductal relaxation. Microarray and real-time PCR analysis indicated that mRNA for both the endothelin receptor subtypes (ETA and ETB) was present in the oviduct, whereas immunohistochemical examination revealed that ETA protein was the dominant isoform, present in the luminal epithelial cells of the oviduct. Real-time PCR analysis demonstrated that mRNA for EDN2 was expressed in COCs after ovulation. Isometric tension analysis indicated that EDN2 was a potent oviductal constrictor and that the contractile effect of EDN2 was mediated by the ETA and not the ETB receptor subtype. The oviductal contraction induced by EDN2 also reversed oviductal relaxation induced by PGE2. In summary, ETA receptor-specific EDN2-induced contraction as a facilitator of oviductal function suggests a novel pathway involved in germ cell transport and hence mammalian fertility.
Loss of soil structure for natural sedimentary clays
Authors: Hong Z. , Shen S. , Deng Y. , Negami T.
Published: May 2007

A number of oedometer and triaxial consolidated undrained triaxial shear tests were performed on both undisturbed and reconstituted specimens of natural soft clays. Based on a comparison of strength behaviour between undisturbed and reconstituted specimens of soft clays, a new interpretation of the loss of soil structure is proposed. This new definition indicates that the resistance of soil structure disappears completely when the consolidation stress is larger than the yield stress in oedometer compression (i.e. the post-yield stress state). The difference in behaviour of compression and strength between reconstituted and undisturbed specimens in the post-yield stress state is explained as being caused by the difference in water content, whereas the mechanical behaviour in the pre-yield stress state (i.e. consolidation stress smaller than yield stress in oedometer compression) is affected by both the water content and the resistance of the soil structure. Experimental data from mercury intrusion porosimetry for a strongly structured diatomite are also used to verify the dramatic change of microstructure in the vicinity of the consolidation yield stress.
General Beliefs about the World as Defensive Mechanisms against Death Anxiety
Authors: Hui Victoria Ka-Ying , Bond Michael Harris , Ng Timmy Sze Wing
Published: May 2007

Death ideation and death anxiety represent the cognitive and affective dimensions of death attitudes, respectively. General beliefs about the world are proposed to be useful defensive mechanisms protecting persons against the death anxiety provoked by death ideation. SEM is employed to test the proposed mediation model, using a sample of 133 Hong Kong Chinese university students. Results showed that death ideation was significantly and inversely linked to belief in social cynicism, reward for application, and fate control. Moreover, higher levels of belief in fate control and lower levels of religiosity predicted greater death anxiety. Only belief in fate control partially mediated the relationship between death ideation and death anxiety. Discussion focused on how social axioms serve as useful defensive mechanisms against death anxiety.
Parents in Death-Related Literature for Children
Authors: Corr Charles A.
Published: May 2007

This article explores ways in which parents are represented as being involved with children in death and loss experiences. These representations are taken from 46 selected examples of death-related literature designed to be read by or with children. The main goal for us is to ask how parents are portrayed in these books and how their interactions with children are depicted. Since parents usually bear primary responsibility for the care of their children, they are ordinarily expected to share their experience and insights with their children, and to help children cope with death and loss. What do they do and how do they help (or not help) children in this body of literature?
Readjusting Didactics to a Changing Epistemology
Authors: Chevallard Yves
Published: May 2007

This article provides an overview of the gradual development, in the span of two decades (1985–2005), of a theorisation which has come to be known as the Anthropological Theory of the Didactic (ATD). It stresses important stages in the dismissing — based on both fact and theory — of some widespread views of teaching and learning, and the establishing of new attitudes towards ‘the didactic’, seen as an anthropological dimension of social life. It emphasises the logic behind the evolution of a ‘science of the didactic’ that, in adapting to the changing nature of its object of study, currently brings to the fore new ideas, among which the concept of ‘study and research course’ (SRC) seems to be most promising.
Microscopic Chorionic Pseudocysts in Placental Membranes: A Histologic Lesion of in Utero Hypoxia
Authors: Stanek Jerzy , Weng Eric
Published: May 2007

Grossly apparent and microscopically intermediate trophoblast-lined subchorionic, septal, and cell island cysts are relatively common placental findings. To analyze the clinicopathologic correlations of histologically similar but grossly inapparent microscopic chorionic pseudocysts (lakes) arising in the chorion laeve of placental membranes (mccpm), selected placental and clinical parameters of all 172 consecutive placentas with mccpm (study group, sg) and all consecutive 3743 placentas without mccpm (comparative group, cg) from years 1994 through 2005 were statistically compared; mccpm were observed in 4.3% of all placentas and in 14.9% of placentas from preeclamptic mothers from 24- to 42-week pregnancies, their gestational weeks' distribution almost mirroring that of the distribution of preeclampsia, with a peak in the middle of the 3rd trimester. Microscopic chorionic pseudocysts (lakes) arising in the chorion laeve of placental membranes were statistically significantly more common in patients with preeclampsia and maternal diabetes mellitus. In placentas with mccpm, decidual arteriolopathy, homogeneous placental maturation, global hypoxic pattern of placental injury, chorangiosis, placental infarction, laminar necrosis of membranes, stem obliterative endarteritis, erythroblasts of fetal blood and decidual hemosiderosis were statistically significantly more common, while acute chorioamnionitis, villous fibrosis, and villous edema were less common ( P ≤ 0.05). There were no statistically significant differences between sg and cg in meconium staining, retroplacental hematoma, perivillous fibrin deposition, intervillous thrombi, chronic villitis, chorangiomas, placenta accreta, amnion nodosum, and marginate/vallate placenta. Highly statistically significant associations of mccpm with preeclampsia and a cluster of placental lesions known to be linked to placental hypoxia indicate that the mccpm form in response to hypoxia, particularly in patients with preeclampsia; mccpm should therefore be regarded and reported as a hypoxia-associated placental lesion.
The Problems and Promise of Central Pathology Review: Development of a Standardized Procedure for the Children's Oncology Group
Authors: Teot Lisa A. , Sposto Richard , Khayat Anita , Qualman Stephen , Reaman Gregory , Parham David
Published: May 2007

The practice of central histopathologic review by expert pathologists has accompanied entry of patients onto multi-institutional therapeutic research protocols for the past half-century, and it is still a key component in the majority of therapeutic protocols conducted by the Children's Oncology Group (COG). Policies regarding pathology review have historically varied but have recently been standardized by the COG. Pretreatment central pathology review has been used to improve the accuracy of pathology data that is critical to the conduct of the study and to ensure that ineligible patients are not enrolled on a study. Pretreatment central review is unnecessary when there are established criteria for diagnosis, when institutions can uniformly apply these criteria, and when diagnoses are reliably reported. Pretreatment central review is appropriate when there are established diagnostic criteria and expert reviewers can consistently apply them but when institutional diagnoses show significant variability. It is inappropriate when there are no standard criteria or when variability exists among experts. Retrospective reviews (for example, those performed after protocol entry and treatment have occurred) historically have been used to verify institutional diagnoses and to record other features of tumors, prior to analysis of research questions. However, delayed reporting of discrepant diagnoses from retrospective reviews introduced obvious concerns regarding the appropriateness of treatment and exposed institutional pathologists and clinicians to significant professional risks. This article examines the historical usage and current status of the central pathology review process and the rationale and indications for its performance.
Mesenchymal Hamartoma of the Liver Associated with Features of Beckwith-Wiedemann Syndrome and High Serum Alpha-Fetoprotein Levels
Authors: Cajaiba Mariana M. , Sarita-Reyes Carmen , Zambrano Eduardo , Reyes-Múgica Miguel
Published: May 2007

A 5-month-old girl with clinical features of Beckwith-Wiedemann syndrome (BWS), including a repaired omphalocele, an earlobe crease, enlarged adrenal glands, renal size discrepancy, and hyperinsulinemic hyperglycemia, presented with a 1.9-cm liver nodule. Markedly increased serum alpha-fetoprotein (AFP) levels (1 060 000 mg/L), highly suspicious for hepatoblastoma, were detected, and resection of the liver mass was performed. Histologic sections showed features characteristic of a mesenchymal hamartoma of the liver (MHL). No features of embryonal or fetal hepatocellular proliferation or heterologous stromal components were noted. By immunohistochemistry, the hepatocytes expressed AFP, but no nuclear accumulation of β-catenin was present. Electron microscopy revealed normal, mature hepatocytes. Here we address the diagnostic challenge of the uncommon association of MHL and BWS in the setting of markedly elevated serum AFP levels. In addition, we analyze the unusual pancreatic lesion (focal endocrine adenomatosis) leading to severe hyperinsulinemic hypoglycemia in a patient with possible BWS. We emphasize that MHLs may present with markedly increased serum AFP levels, mimicking hepatoblastomas, and may also be part of the expanding spectrum of findings of BWS.
Sudden Death in Toddlers Associated with Developmental Abnormalities of the Hippocampus: A Report of Five Cases
Authors: Kinney Hannah C. , Armstrong Dawna L. , Chadwick Amy E. , Crandall Laura A. , Hilbert Chelsea , Belliveau Richard A. , Kupsky William J. , Krous Henry F.
Published: May 2007

Sudden unexplained death in childhood (SUDC) is the sudden death of a child older than 1 year of age that remains unexplained after review of the clinical history, circumstances of death, and autopsy with appropriate ancillary testing. We report here 5 cases of SUDC in toddlers that we believe define a new entity associated with hippocampal anomalies at autopsy. All of the toddlers died unexpectedly during the night, apparently during sleep. Within 48 hours before death, 2 toddlers had fever, 3 had a minor upper respiratory tract infection, and 3 experienced minor head trauma. There was a history of febrile seizures in 2 (40%) and a family history of febrile seizures in 2 (40%). Hippocampal findings included external asymmetry and 2 or more microdysgenetic features. The incidence of certain microdysgenetic features was substantially increased in the temporal lobes of these 5 cases compared with the temporal lobes of 39 (control) toddlers with the causes of death established at autopsy ( P < 0.01). We propose that these 5 cases define a potential subset of SUDC whose sudden death is caused by an unwitnessed seizure arising during sleep in the anomalous hippocampus and producing cardiopulmonary arrest. Precipitating factors may be fever, infection, and/or minor head trauma. Suggested risk factors are a history of febrile seizures and/or a family history of febrile seizures. Future studies are needed to confirm these initial findings and to define the putative links between sudden death, hippocampal anomalies, and febrile seizures in toddlers.
Respiratory Virus Infection in Infants and Children
Authors: Hammond Sue , Chenever Emily , Durbin Joan E.
Published: May 2007

The recent availability of diagnostic polymerase chain reaction-based assays for the detection of viral pathogens has allowed us to identify the infectious agents present in a large percentage of culture-negative specimens. The information gained by these studies has led to a reassessment of the prevalence of individual viruses in lower respiratory tract infections in both normal and immunocompromised children. Pathologic examination of less severe cases identified by more sensitive methodologies in immunocompetent children is now possible and has prompted the realization that many of the classic features of particular viral infections in the lung are in fact hallmarks of fulminant disease. In this article we review the body of literature discussing these anatomic findings, the approaches taken by those investigators, and the types of reagents that are commercially available.
Einsatz von modifiziertem Holz für Parkett | Use of modified wood for wooden flooring
Authors: Scheicher Ulrich
Published: May 2007

Based on experience gained we can sum up the following points as given and proved. The hardness of the wood is increased many times; durability and thus the life span of a product considerably improved; only insignificant improvement has been achieved so far with regard to dimensional stabilisation;the natural character of the wood is preserved; the product(floor boards) is restorable, i.e. it can be smoothed and the new surface can be treated; its employment in heavily frequented rooms has furnished proof of its suitability.
Modifizierung der Holzeigenschaften durch Enzyme | Modification of wood properties through enzymes
Authors: Wagenführ André , Tech Sören , Unbehaun Holger
Published: May 2007

The addition of phenol oxidising enzyme preparations leads to a change in the fibre structure of lignocellulose products. This means that positive material properties can be selectively put in. In the production of materials the use of activated ownfibre binding forces only makes sense when the production process ensures that fibres are as close to one another as possible. This can be accomplished by fine tuning the density of the material to the method in question. Material densities of over 600 kg/m3 are necessary for dry method approaches. With wet methods, on the other hand, the properties of material can be improved starting from a density of 160 kg/m3. A good distribution and the use of additionally created hydro-bridge builders are responsible for this. The employment of charge carriers during the processing with a wet method also has a positive influence on the physical properties. The suspended particles that become detached from the fibre in the process bind together and are concentrated on the surface of the fibre.

To improve the steering of the process with the wet method further enzymatic treatment steps in lignocellulose can be carried out with micro- and nano-particle systems. This can be done via combinations of cationic starch or cationic polyacrylamide. With these systems the cationic polymer is added to the fibre suspension first, followed by the micro-particle components. Both the levels of additives used and the required incubation times can thereby be markedly reduced. Here for the first time we succeeded in using enzymes in processing technically relevant dimensions and were therefore able to renounce the addition of synthetic binding means without impairing the properties of the material.
Regeneration process in natural uneven-aged Caspian beech forests of Iran (reviewed paper)
Authors: Sagheb-Talebi Khosro , Abazari Bahram Delfan , Namiranian Manuchehr
Published: May 2007

Regeneration process was studied within twentytwo gaps produced from natural falling of trees in a semivirgin mixed forest of oriental beech in Iran. The area of the openings varied between 163 m2 and 1683 m2, caused by falling of 1 to 6 trees. Natural regeneration depended on the gap size, and was established within the openings with different compositions.
Beech sapling architecture following small and medium gap disturbances in silver fir-beech old-growth forests in Slovenia
Authors: Diaci Jurij , Kozjek Lahorka
Published: May 2007

The objective of our research was to examine the effect of canopy shading on beech sapling architecture in the oldgrowth silver fir-beech forests of Pecka and Rajhenavski Rog. In August 2003 we sampled one plot (352 m2) in a large gap in Pecka, which was a result of a strong windstorm in 1983, and eight small gaps (26–78 m2) with similar sapling heights (3.8–8 m). A ground view of each gap was drawn including the characteristics of gap border trees and the density of separate sapling layers was recorded. The height and diameter were measured for each sapling, as well as the following quality characteristics on selected dominant saplings: width of the crown,number of larger branches and knots (>1/3 DBH), intensity of stem bending, deviation from vertical growth, number of terminal shoots, and the type of damage. The results show a negative effect of high canopy shading (estimated relative light intensity was below 5%) on the architectural quality of saplings. A lower overall density of saplings, greater intensity of bending and deviation from vertical growth, a shorter stem length without branches, a larger number of saplings with two terminal shoots, and a larger number of damaged saplings were observed in small gaps.
Einfluss der Naturprozesse, waldbaulicher Massnahmen und Schutzmassnahmen auf die Erhaltung der Eibe im Naturreservat Pavelcovo, Slowakei | The effect of natural processes, silvicultural and protective measures on the conservation of common yew in the Nature Reserve Pavelcovo, Slovakia
Authors: Saniga Milan , Jaloviar Peter
Published: May 2007

The study analysed a 15-years experiment focusing on the effect of silvicultural treatment (increment thinning) and red deer browsing on the structure and regeneration processes of common yew (Taxus baccata L.) on a series of four permanent experimental plots in the Nature Reserve Pavelcovo. The reserve Pavelcovo is an age-differentiated natural forest with a typical two-layer structure. The fragmented upper layer is formed of common beech, silver fir, sycamore, Norway maple,Wych elm, common ash and European larch. The lower layer,which is relatively continuous, is formed primarily of common yew. Concerning forest typology, a major part of the reserve was classified to Fagetum tiliosum. The analysis of the effect of the thinning from above with negative selection confirmed a significant increment of yew crown diameters. Concerning the damage on yews with DBH over 2 cm by red deer browsing, a positive correlation was observed: with the increasing breastheight diameter, the share of yew trees damaged by barking increased. Red deer at the present counts becomes a serious factor disturbing natural regeneration processes of yew and causing its gradual decline in the forest ecosystems under investigation. The analysis of the efficiency of a thinning from above on the improvement of ecological conditions for seed germination, establishment, survival and growth of yew seedlings showed that in case of a continuous lower layer, the amount of the transmitted light is insufficient and is one of the principal causes of the auto-reduction of this tree species. A better survival of yew would require an intervention into the lower yew layer mainly through a sanitary selection.
Le WIS.2, un instrument informatique performant pour une gestion efficiente et ciblée des écosystèmes forestiers | WIS.2: a powerful software instrument for the efficient management of forest ecosystems
Authors: Rosset Christian
Published: May 2007

WIS.2 is a powerful software instrument for the management of forest ecosystems, which is targeted, efficient, sustainable,close to nature and multifunctional. This decision support system comprises numerous applications, each of which represents a particular domain of silvicultural management. It is possible to set up an analysis of the principal characteristics of a given domain, its particularities, the possibilities of silvicultural intervention and its limits, but also forest resources that are likely to be of specific interest. WIS.2 also makes it possible to put into place a managerial strategy by starting with a defined targeted state of the ecosystem in order to ensure the sustainable supply of forestry products in accordance with demand,then, concepts of intervention that are determined for the long and medium term according to the conditions of the stands. WIS.2 is conceived in such a way that it can quickly be adapted to accommodate changes in silvicultural management with relative ease.
Ertragskunde – Waldbau auf wissenschaftlicher Grundlage: Plädoyer für einen akademisch abgestützten Waldbau | Profitability – Scientifically based silviculture. Plea for academically supported silviculture
Authors: Zingg Andreas
Published: May 2007

Silviculture is under pressure, as are other areas of applied science. Central specialist forest sciences, such as silviculture,growth and yield or forestry establishments etc., are losing ground due to the division made between basic and applied research and quickly losing their importance in the university landscape. It is only in the German-speaking countries that silviculture and growth and yield are two separate specialist areas and thus not taught in combination with one another. Growth and yield is a scientific basis of silviculture. In its widest sense, siliviculture is a system and can be viewed as a standard circle of diverse activities, each of which has its own scientific problems. Silviculture is an important area of research that is struggling to maintain its hold in today's rapidly changing research landscape–above all because this discipline calls for long-term research. Only long-term silvicultural research will furnish a quantifiable and objective foundation for a modern,ecologically oriented management of the forest.
Das Theorem der übereinstimmenden Zustände und die Quantentheorie der Gase und Flüssigkeiten
Authors: Byk A.
Published: May 2007

Das Theorem der übereinstimmenden Zustände und die Sonderstellung der Substanzen mit niedriger kritischer Temperatur. — Quantentheoretische Verallgemeinerung des Theorems der übereinstimmenden Zustände („Quantentheorem der übereinstimmenden Zustände”︁). — Prüfung des Quantentheorems an den Zustandsgleichungen der Sättigung: 1. Berechnung von Dampfdruckgleichungen und von Siedepunkten; 2. Berechnung von Dampfvolumgleichungen und von Siedevolumina; 3. Berechnung des kritischen Koeffizienten. — Die Thermodynamik der Gase und Flüssigkeiten und die Quantentheorie. Absolute Größen und Relativitätsprinzip. — Zusammenfassung.
Time‐series analysis of traffic updates in loss systems
Authors: Filipiak Janusz , Chemouil Prosper
Published: May 2007

The paper deals with time‐series analysis of one‐line traffic measurements in loss systems. Discrete‐time stochastic models are derived for finite‐capacity trunk groups with non‐exponential distributions of interarrival and service times. The modelling accuracy is characterized by a prediction error. Simulation results are used to assert situations when the application of the proposed modelling technique is practical. Finally the adaptive Kalman filter is used to deal with cases when the statistics of observed processes are not known a priori.
Asymptotic behaviour of ornstein‐uhlenbeck first‐passage‐time density through periodic boundaries
Authors: Sacerdote L.
Published: May 2007

Use of the integral equation proposed by Buonocore et al.1 is made to obtain the asymptotic form of the first‐passage‐time p.d.f. for a normalized Ornstein‐Uhlenbeck process through a periodic boundary.
Compartmental models with phase‐type residence‐time distributions
Authors: Faddy M. J.
Published: May 2007

Phase‐type (PH) probability distributions provide a versatile class of distributions, and are shown to fit naturally into a Markovian compartmental system, where “individuals” or “particles” move between a series of compartments, so that phase‐type compartmental residence‐time distributions can be incorporated simply by increasing the size of the system. Examples of PH distributions covering a variety of behaviours are given, and an application involving data analysis is included.
Recursive partition and amalgamation with the exponential family: Theory and applications
Authors: Ciampi A. , Lou Z. , Lin Qian , Negassa A.
Published: May 2007

The theory of tree‐growing (RECPAM approach) is developed for outcome variables which are distributed as the canonical exponential family. The general RECPAM approach (consisting of three steps: recursive partition, pruning and amalgamation), is reviewed. This is seen as constructing a partition with maximal information content about a parameter to be predicted, followed by simplification by the elimination of ‘negligible’ information. The measure of information is defined for an exponential family outcome as a deviance difference, and appropriate modifications of pruning and amalgamation rules are discussed. It is further shown how the proposed approach makes it possible to develop tree‐growing for situations usually treated by generalized linear models (GLIM). In particular, Poisson and logistic regression can be tree‐structured. Moreover, censored survival data can be treated, as in GLIM, by observing a formal equivalence of the likelihood under random censoring and an appropriate Poisson model. Three examples are given of application to Poisson, binary and censored survival data.
Expert systems as a tool for statistics: A review
Authors: Hatabian Gérard , Augendre Hervé
Published: May 2007

The current state of using expert system (ES) techniques for statistics is expounded through the difficulties of defining the notion of statistical expert system (SES) and through several well‐known examples. The main characteristics of statistical expertise, and particularly the important concept of strategy are emphasized. The current state of SESs is seen in the context of the global trend of the evolution of ES, i.e. within the growth of second generation expert system (SGESs). The knowledge base of these ESs represent an attempt to represent not only experts' knowledge but also the way experts acquire their expertise, thanks to the existence of an underlying model. We show through many examples how far SESs are and/or will be able to be SGESs.
An imputation method for dealing with missing data in regression
Authors: Cooper Lee G. , De Leeuw Jan , Sogomonian Aram G.
Published: May 2007

We develop two methods for imputing missing values in regression situations. We examine the standard fixed‐effects linear‐regression modelY = Xβ + ϵ, where the regressorsXare fixed and ϵ is the error term. This research focuses on the problem of missingXvalues. A particular component of market‐share analysis has motivated this research where the price and other promotional instruments of each brand are allowed to have their own impact on the total sales volume in a consumer‐products category. When a brand is not distributed in a particular week, only a few of the many measures occurring in that observation are missing. ‘What values should be imputed for the missing measures?’ is the central question this paper addresses. This context creates a unique problem in the missing‐data literature, i.e. there is no true value for the missing measure. Using influence functions, from robust statistics we develop twoloss functions, each of which is a function of the missing and existingXvalues. These loss functions turn out to be sums of ratios of low‐order polynomials. The minimization of either loss function is an unconstrained non‐linear‐optimization problem. The solution to this non‐linear optimization leads to imputed values that have minimal influence on the estimates of the parameters of the regression model. Estimates using the method for replacing missing values are compared with estimates obtained via some conventional methods.
A non‐parametric competing risks model for manpower planning
Authors: McClean Sally , Gribbin Owen
Published: May 2007

One of the most important variables for manpower planners is duration until a specified event occurs. This is frequently the completed length of service until leaving a job, but may also include such variables as length of service in a grade until promotion, or length of a spell of withdrawal from the labour force.

In this paper we develop non‐parametric maximum likelihood estimators for the survivor functions of length of stay in a grade until leaving for a number of different possible destinations. Since the data are statistically incomplete, including right censored and left truncated durations, as well as complete durations, we must modify the competing risks theory in the biostatistical literature to take such incompleteness into account. Right censored durations arise when the individual is still in the grade when data collection ceases and left truncated durations when the individual is already in service when data collection commences.

The competing risks model is fitted to data for Northern Ireland nursing service and used to predict staff flows between grades. We may thus estimate future movements within the system and predict the future manpower stocks.
Hierarchical production control of a flexible manufacturing system
Authors: Xie Xiao‐Lan
Published: May 2007

A hierarchical production control framework for a flexible manufacturing system is proposed. The machines in the system are subject to failures in a wide spectrum band. At first, failures are clustered near some discrete points on the failure spectrum in order to define the hierarchical model. Each level in the hierarchy corresponds to a discrete point on the failure spectrum. At each level, faster varying failures are modelled by their mean behaviour, and more slowly varying failures are treated as static. Then, a hierarchical controller of multiple time scale type is proposed. System control at each level is based on the work of Kimemia and Gershwin. Simulation results conclude the paper.
Interaction between data analysis and telecommunications
Authors: Volle Michel
Published: May 2007

We consider interaction between data analysis and telecommunications from both sides, examining the contribution of each discipline to the other. The fast changes in telecommunications have some important consequences. First, the importance of statistics in the design of a network is growing, given the evolution of technology towards more digitalization and the resulting changes in dimensioning the network. Second, the technical tools of statistics are deeply modified, and there is concern about how to take this into account—particularly how to take advantage of the new economy of ‘value added services’ which uses the network as a ‘market place’.
On the numerical expansion of a second order stochastic process
Authors: Gutiérrez Ramón , Ruiz Juan Carlos , Valderrama Mariano J.
Published: May 2007

The utility of the classical Karhunen‐Loève expansion of a second order process is limited to its practical derivation, because it depends upon the solution of a Fredholm integral equation associated with it whose kernel is the covariance function of the process. So, in this paper we study two numerical procedures for solving such equations, the Rayleigh‐Ritz and the collocation methods, and also essay two different bases of L2‐orthogonal functions in order to perform the algorithms, Legendre polynomials and trigonometric functions, on two well‐known processes, the Wiener‐Lévy process and the Brownian‐bridge. The accuracy of the numerical results in relation to the real ones, as well as comparative studies among both procedures are also included.
Repairable failure‐delay systems with elementary structure
Authors: Limnios N.
Published: May 2007

This paper defines repairable failure‐delay systems, and gives explicit formulae for their availability. It presents models for single‐component, series and parallel systems with delay at system level, and a ‘rare event’ approximation for availability and reliability of series systems with delay at component level. Finally, it uses a renewal terminating process for deriving the limiting distribution of the lifetime of failure‐delay systems.
On the performance of peeling algorithms
Authors: Petitjean Michel , Saporta Gilbert
Published: May 2007

The peeling of a d‐dimensional set of points is usually performed with successive calls to a convex hull algorithm; the optimal worst‐case convex hull algorithm, known to have an O(n˙ Log (n)) execution time, may give an O(n˙n˙ Log (n)) to peel all the set; an O(n˙n) convex hull algorithm, m being the number of extremal points, is shown to peel every set with an O(n‐n) time, and proved to be optimal; an implementation of this algorithm is given for planar sets and spatial sets, but the latter give only an approximate O(n˙n) performance.
Clusterwise aggregation of relations: The case of paired comparisons of cognac ads
Authors: Owsinski Jan W. , Zadrożny Sławomir
Published: May 2007

This short paper takes up the problem stated by Gaul and Schader1 in 1988 of simultaneous clustering and aggregation of relations—in this case precedences (preferences)—so that aggregate preferences could represent relatively homogeneous groups of preference relations. The paper indicates the existence of two distinct questions, similar to those asked in the case of the global aggregation problem, regarding intra‐group agreement as to preferences represented in whatever form, and intra‐group agreement as to a common (‘regular’) preference. In both these cases, though, fundamental computational problems arise. This paper presents a heuristic for obtaining an approximate solution. Requirements as to the properly optimal method are outlined.
Note model‐checking in non‐stationary poisson processes
Authors: Solow Andrew R.
Published: May 2007

An approach to assessing the fit of a parametric non‐stationary Poisson process model to data is presented. The approach uses kernel estimation in conjunction with a parametric bootstrap. An example is given.
Embedded options in commercial banking and their impact on asset liability management
Authors: Boulier J. F. , Schoeffler P.
Published: May 2007

Commercial bankers sell—more often give away—options to their clients like the prepayment facility attached to a mortgage or the right to obtain a credit at a prespecified interest rate which is associated in France with specific term deposits. This paper aims to present the financial consequences of these options from a microeconomic point of view and on the scale of the French banking system. We first example our valuation techniques and then analyse the impact on the balance sheet of a typical commercial bank, both in terms of value and sensitivity. Securitization is presented in this context as a way to monitor risk exposure. Finally the global impact of these embedded options in the French banking system is estimated and briefly discussed.
Numerically intensive computing in Japanese financial institutions
Authors: Ohmori Keiji
Published: May 2007

Two major sophisticated services are needed by Japanese financial institutions. They are fund management and the development of new financial products. These are needed because of the increase of fund to be managed and deregulation. This paper will first, explain the current situation in Japanese financial institutions and, second, introduce the use of numerically intensive computing to provide these new services.
A dual strategy for the implementation of the aggregation principle in decision making under uncertainty
Authors: Rockafellar R. T. , Wets Roger J.‐B.
Published: May 2007

A solution method for stochastic programs is proposed based on the aggregation principle, which allows one to find the solution of a stochastic program by aggregating the solutions of individual deterministic scenario problems. The method concentrates on finding good estimates of the dual variables associated with the non‐anticipativity constraints.
A continuous time markov‐renewal replacement model for manpower systems
Authors: Gerontidis Ioannis I.
Published: May 2007

A continuous time Markov‐renewal model is presented that generalizes the classical Young and Almond model for manpower systems with given size. The construction is based on the associated Markov‐renewal replacement process and exploits the properties of the embedded replacement chain. The joint cumulant generating function of the grade sizes is derived and an asymptotic analysis provides conditions for these to converge in distribution to a multinominal random vector exponentially fast independently of the initial distribution, both for aperiodic and periodic embedded replacement chains. A regenerative approach to the wastage process is outlined and two numerical examples from the literature on manpower planning illustrate the theory.
Binary clustering with missing data
Authors: Nadif M. , Govaert G.
Published: May 2007

A clustering method is presented for analysing multivariate binary data with missing values. When not all values are observed, Govaert3 has studied the relations between clustering methods and statistical models. The author has shown how the identification of a mixture of Bernoulli distributions with the same parameter for all clusters and for all variables corresponds to a clustering criterion which uses L1 distance characterizing the MNDBIN method (Marchetti8). He first generalized this model by selecting parameters which can depend on variables and finally by selecting parameters which can depend both on variables and on clusters. We use the previous models to derive a clustering method adapted to missing data. This method optimizes a criterion by a standard iterative partitioning algorithm which removes the necessity either to ignore objects or to substitute the missing data. We study several versions of this algorithm and, finally, a brief account is given of the application of this method to some simulated data.
Design of cellular manufacturing systems with refixturing and material handling considerations
Authors: Damodaran V. , Singh N. , Lashkari R. S.
Published: May 2007

Refixturing and material handling aspects of cellular manufacturing systems are considered. For this purpose, two mathematical models are developed to determine machine groups and the assignment of part operations to machines. The first model is used simultaneously to assign operations of parts to machines and form machine groups. The second model is developed for the situation when new machines are procured for a cellular manufacturing environment. Examples are included to illustrate the applications of the models.
A scheduling algorithm for flexible flow lines with limited intermediate buffers
Authors: Sawik Tadeusz J.
Published: May 2007

A new heuristic algorithm is proposed for scheduling a flexible flow line with limited in‐process buffers. The line is made up of a certain number of processing stages. Each stage has one or more identical parallel machines with limited buffers. Each part is processed by at most one machine in each stage. The problem objective is to minimize the makespan of the schedule for a set of part types selected for processing. The computational results for a set of test problems used in the literature are reported. In addition, the efficiency of the algorithm is tested on several groups of random problems.
Unsupervised learning methodology: Application to nuclear power plants
Authors: Mourot G. , Kratz F. , Heraud N.
Published: May 2007

After a general presentation of the problem of unsupervised learning for diagnosis by pattern recognition, the methodology proposed is described as well as the necessary mathematical tools. This methodology is illustrated by the steam generator of a nuclear power plant.
A comprehensive approach of planning and scheduling based on petri nets
Authors: Harhalakis George , Proth Jean‐Marie , Xie Xiao‐Lan
Published: May 2007

The main results available on the use of black‐and‐white Petri nets for modelling, planning and scheduling manufacturing systems are presented. In the first part of the paper, the basics of Petri nets necessary to understand the subsequent presentation are introduced. Particular attention is paid to event graphs, a particular type of Petri nets used for modelling and evaluating ratio‐driven systems. The second part of the paper is devoted to ratio‐driven systems, their modelling and their scheduling. Job‐shops, assembly systems, and KANBAN systems are used to illustrate this section. Finally, the general case is investigated of manufacturing systems subject to changing demands. An approach based on conflict‐free Petri nets with input and output transitions is proposed for planning and scheduling this type of system.
Improving scoring techniques in banking applications
Authors: Perrodo Pascal
Published: May 2007

Scoring techniques are largely used today in banking applications, for marketing as well as risk assessment or control purposes. The most widely used method is Fisher's discriminatory analysis. We discuss here this method from a technical standpoint, showing its weaknesses and then propose a simpler and more general alternative. We first make an original presentation of the various scoring techniques and their basic principles. In particular, we provide a detailed description of Fisher's method, insisting on sensitive steps such as the discretization of continuous variables which is responsible for the nonlinearity of the model. We then go on to propose a new method that is completely linear and improves scoring performance. This technique is easy to explain, compute and use in real applications. Finally, we compare the performance of this new method with that of traditional techniques and of the more up‐to‐date neural nets method.
Minimax design of two‐state k‐out‐of‐n systems
Authors: Kouikoglou Vassilis S. , Phillis Yannis A.
Published: May 2007

The optimal size of k is specified for two‐state k‐out‐of‐n systems that may be functioning or fail in either state. It is assumed that the steady‐state, success and failure probabilities are not known exactly. The problem is reduced to finding the saddle‐point solution to a minimax optimization problem. An example shows that the minimax design is robust with regard to uncertainty.