bluuebunny/crossref_metadata_2025_split huggingface dataset:
Guaranteed‐quality triangular mesh generation for domains with curved boundaries
Authors: Boivin Charles , Ollivier‐Gooch Carl 
Published: October 2002

AbstractGuaranteed‐quality unstructured meshing algorithms facilitate the development of automatic meshing tools. However, these algorithms require domains discretized using a set of linear segments, leading to numerical errors in domains with curved boundaries. We introduce an extension of Ruppert's Delaunay refinement algorithm to two‐dimensional domains with curved boundaries and prove that the same quality bounds apply with curved boundaries as with straight boundaries. We provide implementation details for two‐dimensional boundary patches such as lines, circular arcs, cubic parametric curves, and interpolated splines. We present guaranteed‐quality triangular meshes generated with curved boundaries, and propose solutions to some problems associated with the use of curved boundaries. Copyright © 2002 John Wiley & Sons, Ltd.
Transforming top‐down agricultural extension to a participatory system: a study of costs and prospective benefits in Egypt
Authors: Fleischer Gerd , Waibel Hermann , Walter‐Echols Gerd 
Published: October 2002

AbstractThis article challenges some previous assessments of agricultural extension relying on simple measures of costs per farmer trained. Taking the case of Egypt, five pilot projects that aim to transform the existing agricultural extension system to a participatory system are analysed as regards their cost‐effectiveness and prospective cost–benefits. It is shown that the intensity and likely impact of participatory approaches among the different projects vary. Hence, it is insufficient to judge extension programmes by their cost‐effectiveness alone. In the case of cotton, for example, the costs per farmer trained are considerably lower than in horticultural crops but there are large differences in prospective benefits which would make investment in participatory extension in the latter more promising. The article calls for a more careful analysis of the costs of extension programmes in agricultural development and identifies four major cost categories, namely base costs, start‐up costs, recurrent and farmers' costs. The article also submits that in the context of the debate on privatization of agricultural extension there is a role to be played for the public sector in agriculture. The success of participatory approaches to extension will depend on the quality of services provided in connection with farmer training programmes. Copyright © 2002 John Wiley & Sons, Ltd.
The random development of LOH on chromosome 9q in superficial bladder cancers
Authors: van Tilborg Angela AG , de Vries Annie , de Bont Maarten , Groenfeld Lilian E , Zwarthoff Ellen C 
Published: October 2002

AbstractAllelic loss on chromosome 9q is a very frequent event in bladder carcinogenesis. In recent years, efforts have been directed towards identifying the postulated tumour suppressor genes on this chromosome arm by deletion mapping and mutation analysis. However, no convincing candidate genes have been identified. This paper describes the development of chromosome 9q alterations in multiple recurrent superficial bladder cancers of ten patients and shows that loss of heterozygosity (LOH) on this chromosome is almost never the characteristic first step. The regions of loss are multiple and variable in different tumours from the same patient and expand in subsequent tumours. Moreover, the regions of loss vary from patient to patient. It is concluded that even if 9q harbours a bladder cancer gatekeeper gene, it is unlikely that the gene will be identified through LOH analysis alone. Copyright © 2002 John Wiley & Sons, Ltd.
A Markov model for sample size calculation and inference in vaccine cost‐effectiveness studies
Authors: Byrnes G. B. 
Published: October 2002

AbstractSample size and power formulae are derived for designing trials of vaccine cost‐effectiveness in healthy working adults. When existing trials of influenza vaccine have presented sample size calculations, these have been based on vaccine effectiveness. A Markov model is introduced to account for non‐independence of working days lost. Two effect sizes need to be specified, one for a reduction in the number of episodes of absence and the second for a reduction in the mean duration of episodes. The relative cost of vaccine provision is also incorporated. Applying the resulting formulae to published studies indicates that most were underpowered to detect any financial benefit. Moreover, biased estimates of variance have led to led to incorrect inference. Copyright © 2002 John Wiley & Sons, Ltd.
Multilevel modelling of medical data
Authors: Goldstein Harvey , Browne William , Rasbash Jon 
Published: October 2002

AbstractThis tutorial presents an overview of multilevel or hierarchical data modelling and its applications in medicine. A description of the basic model for nested data is given and it is shown how this can be extended to fit flexible models for repeated measures data and more complex structures involving cross‐classifications and multiple membership patterns within the software package MLwiN. A variety of response types are covered and both frequentist and Bayesian estimation methods are described. Copyright © 2002 John Wiley & Sons, Ltd.
Doses to the Embryo and Fetus from Intakes of Radionuclides by the Mother
Authors: Valentin J. 
Published: October 2002

In its Publications 56, 67, 69, 71, and 72, ICRP has provided age-specific biokinetic models and, using those models, compiled dose coefficients (doses per unit intake) for intakes of radionuclides by members of the public. Committed effective doses for the inhalation or ingestion of radionuclides by workers who are occupationally exposed were given in Publication 68 based on the most recent dosimetric and biokinetic models for adults. Additionally, a compilation of dose coefficients for both workers and members of the public has been issued on a CD-ROM. The present report complements that series by addressing doses to the embryo/fetus after intakes of radionuclides by a female member of the public or a female worker, before or during pregnancy. Ingestion and inhalation of selected radionuclides of the 31 elements for which age-dependent biokinetic models were provided in the previous reports are considered. These elements are H, C, S, Ca, Fe, Co, Ni, Zn, Se, Sr, Zr, Nb, Mo, Tc, Ru, Ag, Sb, Te, I, Cs, Ba, Ce, Pb, Po, Ra, Th, U, Np, Pu, Am, and Cm. New biokinetic and dosimetric models for calculating doses to the developing embryo and fetus are developed and used in conjunction with the models for infants, children, and adults presented in the previous reports. The models used take account of transfer of radionuclides across the placenta, distribution and retention of radionuclides in fetal tissues, growth of the fetus, and photon irradiation from radionuclides in the placenta and maternal tissues. Human and animal data are used as available in the development of these models. Intake scenarios comprising single or continuous maternal intakes are taken into account in the compilation of effective dose coefficients following ingestion or inhalation of the radionuclides considered. A CD-ROM with more comprehensive information on doses from inhalation of different particle sizes, tissue doses, and doses at various times after birth has been developed concurrently with the report and will be available shortly. The report does not consider doses to the offspring due to intakes of radionuclides in maternal milk and external irradiation from the mother's body after birth. The radiation sensitivity of the offspring is not discussed.
The current cost of heart failure to the National Health Service in the UK
Authors: Stewart Simon , Jenkins Andrew , Buchan Scot , McGuire Alistair , Capewell Simon , McMurray John J.J.V. 
Published: October 2002

AbstractWe have recently shown that heart failure admission rates continue to increase in the UK — particularly in older age groups. As hospital activity represents the major cost component of healthcare expenditure related to heart failure, this study evaluated the current cost of this syndrome to the National Health Service (NHS) in the UK. We applied contemporary estimates of healthcare activity associated with heart failure to the whole UK population on an age and sex‐specific basis to calculate its cost to the NHS for the year 1995. Direct components of healthcare included in these estimates were hospital admissions associated with a principal diagnosis of heart failure, associated outpatient consultations, general practice consultations and prescribed drug therapy. We also calculated the cost of nursing‐home care following a primary heart failure admission and the cost of hospitalisations associated with a secondary diagnosis of heart failure. Adjusting for probable increases in hospital activity and the progressive ageing of the UK population, we have also projected the cost of heart failure to the NHS for the year 2000. We estimated that there were 988000 individuals requiring treatment for heart failure in the UK during 1995. The ‘direct’ cost of healthcare for these patients was estimated to be £716 million, or 1.83% of total NHS expenditure. Hospitalisations and drug prescriptions accounted for 69 and 18% of this expenditure, respectively. The additional costs associated with long‐term nursing home care and secondary heart failure admissions accounted for a further £751 million (2.0% of total NHS expenditure). By the year 2000, we estimated that the combined total direct cost of heart failure would have risen to £905 million — equivalent to 1.91% of total NHS expenditure. Using well‐validated sets of data, these findings re‐confirm the importance of heart failure as a major public health problem in the UK. The annual direct cost of heart failure to the NHS in 2000 is likely to be of the order of 1.9% of total expenditure — the predominant cost component being hospitalisation.
The addition of pentoxifylline to conventional therapy improves outcome in patients with peripartum cardiomyopathy
Authors: Sliwa Karen , Skudicky Daniel , Candy Geoffrey , Bergemann Anette , Hopley Mark , Sareli Pinhas 
Published: October 2002

AbstractWe have reported previously that despite treatment with angiotensin‐converting enzyme inhibitors and β blockers, the outcome of patients with peripartum cardiomyopathy (PPC) remains unfavorable. Similar to other etiologies of left ventricular dysfunction, we found elevated levels of tumor necrosis factor‐α (TNF‐α) in this group of patients. In the present study we sought to evaluate the effects of pentoxifylline, a drug known to inhibit the production of TNF‐α, on clinical status, left ventricular function, and circulating plasma levels of TNF‐α, in patients with PPC. We followed prospectively 59 consecutive women with PPC. The first 29 patients (group 1) were treated with diuretics, digoxin, enalapril and carvedilol. The next 30 consecutive patients (group 2) received pentoxifylline 400 mg TID in addition to the previous therapy. Clinical evaluation, echocardiograms and TNF‐α determinations were performed at baseline and after 6 months of treatment. Patients in the pentoxifylline group were older and had a higher E/A ratio. Nine patients died (eight in group 1, P‐0.009 between groups). A combined end‐point of poor outcome defined as either death, failure to improve the left ventricular ejection fraction >10 absolute points or functional class III or IV at latest follow‐up, occurred in 52% of patients in group 1 and 27% of patients in group 2 (P‐0.03). Treatment with pentoxifylline (P‐0.04) was the only independent predictor of outcome. In conclusion, the results of this study suggest that the addition of pentoxifylline to conventional treatment, improves outcome in patients with peripartum cardiomyopathy.
SHARED RESPONSIBILITY IN HOME BIRTH PRACTICE: COLLABORATING WITH CLIENTS
Authors: Bailes Alice , Jackson Marsha E. 
Published: October 2002

ABSTRACTThe home setting not only provides a special environment for birth and the practice of midwifery, but also has an impact on the processes used in clinical decision making. This article focuses on collaboration between the midwife and the birthing woman and also discusses the collaborative relationship between midwives and obstetric consultants. A home birth case study illustrates the interactions among the midwife, the woman, and the medical system. These critical relationships provide structure for safe, effective clinical practice in planned home birth when practice boundaries are not defined by institutional walls.
Diabetes in Pregnancy: The Midwifery Role in Management
Authors: Avery Melissa D. 
Published: October 2002

ABSTRACTAlthough the primary focus of midwifery is on uncomplicated pregnancy, all midwives must screen for and, in some cases, comanage the care of women with diabetes mellitus and gestational diabetes. This article will review the types of diabetes, implications for preconceptional and pregnancy care, the changing recommendations relative to diabetes in pregnancy, and the role of the midwife in providing antepartal and intrapartal care for women with diabetes in collaboration with other health care professionals and in accordance with the philosophy and standards of the American College of Nurse‐Midwives. A specific case study will highlight the role of the midwife, with an overall focus on medical consultation, collaboration, and referral, as well as client involvement in the planning of care.
Gene perturbation and intervention in probabilistic Boolean networks
Authors: Shmulevich Ilya , Dougherty Edward R. , Zhang Wei 
Published: October 2002

Abstract
Motivation: A major objective of gene regulatory network modeling, in addition to gaining a deeper understanding of genetic regulation and control, is the development of computational tools for the identification and discovery of potential targets for therapeutic intervention in diseases such as cancer. We consider the general question of the potential effect of individual genes on the global dynamical network behavior, both from the view of random gene perturbation as well as intervention in order to elicit desired network behavior.
Results: Using a recently introduced class of models, called Probabilistic Boolean Networks (PBNs), this paper develops a model for random gene perturbations and derives an explicit formula for the transition probabilities in the new PBN model. This result provides a building block for performing simulations and deriving other results concerning network dynamics. An example is provided to show how the gene perturbation model can be used to compute long-term influences of genes on other genes. Following this, the problem of intervention is addressed via the development of several computational tools based on first-passage times in Markov chains. The consequence is a methodology for finding the best gene with which to intervene in order to most likely achieve desirable network behavior. The ideas are illustrated with several examples in which the goal is to induce the network to transition into a desired state, or set of states. The corresponding issue of avoiding undesirable states is also addressed. Finally, the paper turns to the important problem of assessing the effect of gene perturbations on long-run network behavior. A bound on the steady-state probabilities is derived in terms of the perturbation probability. The result demonstrates that states of the network that are more ‘easily reachable’ from other states are more stable in the presence of gene perturbations. Consequently, these are hypothesized to correspond to cellular functional states.
Availability: A library of functions written in MATLAB for simulating PBNs, constructing state-transition matrices, computing steady-state distributions, computing influences, modeling random gene perturbations, and finding optimal intervention targets, as described in this paper, is available on request from is@ieee.org.
Contact: is@ieee.org
* To whom correspondence should be addressed.
Quantification of protein surfaces, volumes and atom–atom
contacts using a constrained Voronoi procedure
Authors: McConkey B.J. , Sobolev V. , Edelman M. 
Published: October 2002

Abstract
Motivation: Geometric representations of proteins and ligands, including atom volumes, atom–atom contacts and solvent accessible surfaces, can be used to characterize interactions between and within proteins, ligands and solvent. Voronoi algorithms permit quantification of these properties by dividing structures into cells with a one-to-one correspondence with constituent atoms. As there is no generally accepted measure of atom–atom contacts, a continuous analytical representation of inter-atomic contacts will be useful. Improved geometric algorithms will also be helpful in increasing the speed and accuracy of iterative modeling algorithms.
Results: We present computational methods based on the Voronoi procedure that provide rapid and exact solutions to solvent accessible surfaces, volumes, and atom contacts within macromolecules. Furthermore, we define a measure of atom–atom contact that is consistent with the calculation of solvent accessible surfaces, allowing the integration of solvent accessibility and inter-atomic contacts into a continuous measure. The speed and accuracy of the algorithm is compared to existing methods for calculating solvent accessible surfaces and volumes. The presented algorithm has a reduced execution time and greater accuracy compared to numerical and approximate analytical surface calculation algorithms, and a reduced execution time and similar accuracy to existing Voronoi procedures for calculating atomic surfaces and volumes.
Availability: Source code and executable programs are available from the authors.
Contact: brendan.mcconkey@weizmann.ac.il
* To whom correspondence should be addressed.
Subtle motifs: defining the limits of motif finding algorithms
Authors: Keich U. , Pevzner P.A. 
Published: October 2002

Abstract
Motivation: What constitutes a subtle motif? Intuitively, it is a motif that is almost indistinguishable, in the statistical sense, from random motifs. This question has important practical consequences: consider, for example, a biologist that is generating a sample of upstream regulatory sequences with the goal of finding a regulatory pattern that is shared by these sequences. If the sequences are too short then one risks losing some of the regulatory patterns that are located further upstream. Conversely, if the sequences are too long, the motif becomes too subtle and one is then likely to encounter random motifs which are at least as significant statistically as the regulatory pattern itself. In practical terms one would like to recognize the sequence length threshold, or the twilight zone, beyond which the motifs are in some sense too subtle.
Results: The paper defines the motif twilight zone where every motif finding algorithm would be exposed to random motifs which are as significant as the one which is sought. We also propose an objective tool for evaluating the performance of subtle motif finding algorithms. Finally we apply these tools to evaluate the success of our MULTIPROFILER algorithm to detect subtle motifs.
Contact: keich@cs.ucsd.edu
* To whom correspondence should be addressed.
MAGNETISM AT THE SPATIAL LIMIT
Authors: MANOHARAN H. 
Published: October 2002

In this talk I will survey our recent experimental results in the detection and manipulation of magnetism at the spatial limit. Our experiments rely on atom manipulation techniques and scanning tunneling microscopy at low temperatures to enable atomic-scale imaging and control. We have observed "quantum mirages" in focusing devices of order 10 nanometers in size, built by assembling structures out of individual atoms. We have directly imaged the spin perturbations due to isolated magnetic moments on a metal surface. The detection of this localized magnetism can then be utilized in a type of teleportation experiment, in which the spectroscopic signature of an atom is sampled and projected to a remote location by means of a surrounding sea of electrons confined in an engineered nanostructure. The quantum mirage thus cast by a single magnetic atom can be coherently refocused at a distinct point where it is detected as a phantom atom around which the electronic structure mimics that at the real atom. Once materialized, this phantom can interact with real matter in intriguing ways. We have constructed other nanoscale magnetic structures which either elucidate the coupling between isolated moments or provide a mechanism for controlling and exploiting spin coupling over long distances. We have also been developing novel communication methods based on the fundamental effects we have discovered.
ELECTRON CORRELATION EFFECTS IN BIOLOGICAL MOLECULES
Authors: COX D. L. , ENDRES R. , KULKARNI R. V. , LABUTE M. , SINGH R. R. P. 
Published: October 2002

Allosteric (conformation changing) proteins with transition metal atoms are at the heart of much important biological function (e.g., myoglobin hemoglobin used for storing and transporting oxygen in the bloodstream). In the case of myoglobin and hemoglobin, oxygen ligation to the iron center induces a spin crossover (high to low) coupled to a structural change; apart from the role of Hunds' exchange in the spin crossover, electron interaction effects have been ignored. We argue that the spin crossover/structure change observed in the similarly structured but far simpler cobalt valence tautomer molecules1 necessitates an inclusion of underscreened Kondo like correlations for a complete description of the energetics of the transition and dynamics, e.g., for x-ray absorption data. We carry this study out with Varma-Yafet-Gunnarsson-Schonhammer wave functions, which, in chemistry language, are basis set restricted configuration interaction in character. We briefly review the applicability of such wave functions to the description of the putative Kondo molecules cerocene (Ce[(CH)5]2) and ytterbocene bipyridine (Yb[(CH)5]2(bipy)) and to the problem of electron transfer in biological molecules and organic conductors, where anomalous long range tunneling may occur. Research supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Division of Materials Research.