bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimating mean hospital cost as a function of length of stay and patient characteristics
Authors: Polverejan Elena , Gardiner Joseph C. , Bradley Cathy J. , Holmes‐Rovner Margaret , Rovner David 
Published: October 2003

AbstractStatistical models have been used to assess the influence of clinical and demographic factors on hospital charge and length of stay (LOS). Hospital costs constitute a significant proportion of overall expenditure in health care. With escalating costs, knowing the correlates of LOS and in‐hospital cost is important for decisions on allocating resources.However, hospital charge and LOS are correlated. We describe two regression models that permit estimation of mean charges as a function of patient hospital stay and adjust for the influence of patient characteristics and treatment procedures on LOS and charge. In the first model, the mean charge over a specified duration is a weighted average of the expected cumulative charge, with weighting determined by the distribution of LOS. The second model for LOS and charge explicitly accounts for their correlation and yields estimates of the average charge per average LOS.The methods are applied to assess mean charges and mean charge per day by cardiac procedure in a cohort of patients hospitalized for acute myocardial infarction, while adjusting for the impact of patient demographic and clinical factors on LOS and charge.For relatively short hospital stays, and when only total hospital charges are available, these models provide a flexible approach to estimating summary measures on resource use while controlling for the effects of covariates on LOS and charge. Copyright © 2002 John Wiley & Sons, Ltd.
Salvage of recurrent head and neck squamous cell carcinoma after primary curative surgery
Authors: Wong Ling Yuen , Wei William Ignace , Lam Lai Kun , Yuen Anthony Po Wing 
Published: October 2003

AbstractPurpose.The efficacy of salvage treatment of recurrent head and neck squamous cell carcinomas (HNSCC) after primary curative surgery was evaluated.Methods.The management outcome of 377 patients who had recurrent squamous cell carcinoma of oral cavity, oropharynx, hypopharynx, and larynx after primary curative surgery was reviewed.Results.The surgical salvage rates of recurrence were 29% local, 30% tracheostomal, 56% unilateral nodal recurrence of previously undissected neck, 32% of unilateral neck recurrence after prior neck dissection, and 11% lung metastasis. The 5‐year tumor‐free actuarial survival rates of those patients who received surgical salvage was 35% for local recurrence, 32% for unilateral nodal recurrence of the previously undissected neck, and 18% for nodal recurrence of the previously dissected neck. One patient of six with tracheostomal recurrence salvaged with surgery and one patient of six with lung metastasis salvaged with lobectomy survived without tumor at 5 years. There was no 5‐year survivor of all patients salvaged with other nonsurgical methods. The mean survival of patients without surgical salvage was 6 months.Conclusions.There was a moderate chance of cure after surgical salvage of locoregional recurrent HNSCC. Surgical salvage was, however, only feasible for early recurrent tumor. Close follow‐up surveillance of early recurrence is essential after primary treatment of patients. © 2003 Wiley Periodicals, Inc. Head and Neck 25: 000–000, 2003
Current management of benign parotid tumors—The role of limited superficial parotidectomy
Authors: O'Brien Christopher J. 
Published: October 2003

AbstractBackground.Parotid tumors are mostly benign, but their evaluation and treatment require a thorough knowledge of the relevant anatomy and pathology. Surgical treatment of benign tumors is aimed at complete removal of the mass with facial nerve preservation. The aim of this study was to evaluate the results of treatment of benign parotid neoplasms when surgery entailed limited superficial parotidectomy.Methods.All patients with benign parotid tumors treated by the author from 1988 to 2002 were reviewed. Data had been prospectively accessioned onto the computerized database of the Department of Head and Neck Surgery, RPAH. Limited superficial parotidectomy was carried out in all previously untreated patients with tumors superficial to the plane of the facial nerve. Median follow‐up time was 6 years (range, 1–14 years).Results.A total of 363 parotidectomies was carried out on 355 patients, 29 of whom (8%) were previously treated. Tumors arose deep to the plane of the facial nerve in 40 patients (11%), and, of these, 16 occupied the parapharyngeal space. Pleomorphic adenoma (70%) and Warthin's tumors (15%) were the most common pathologic types. Temporary postoperative facial weakness occurred after 98 operations (27%). Facial weakness was permanent in 2.5% of patients (9 cases) who had normal preoperative function; however, in this group the facial nerve was intentionally resected in 2 patients, 3 others had had previous surgery, and 1 had a deep lobe tumor. Tumor recurrence developed in three patients (0.8%), two of whom had been previously treated.Conclusion.Complete superficial parotidectomy is unnecessary in the treatment of benign localized parotid tumors. Limited parotidectomy is associated with very low rates of morbidity and recurrence. Preoperative investigations should be used selectively; however, the author recommends routine (or at least liberal) use of fine‐needle aspiration biopsy. © 2003 Wiley Periodicals, Inc. Head and Neck 25: 000–000, 2003
Tumor thickness influences prognosis of T1 and T2 oral cavity cancer—but what thickness?
Authors: O'Brien Christopher J. , Lauer Christopher S. , Fredricks Susanne , Clifford Anthony R. , McNeil Edward B. , Bagia Jai S. , Koulmandas Christina 
Published: October 2003

AbstractBackground.Previous studies have demonstrated that tumor thickness might influence prognosis in oral cancer, but the significant point at which outcome changes has varied from 1.5 mm to 6 mm. The clinical relevance of thickness remains unclear, and a reproducible prognostic “breakpoint” needs to be defined.Methods.Tumor thickness was measured in 145 oral cavity squamous cancers, clinically staged T1 (n = 62) or T2 (n = 83). Clinical and pathologic data were collected prospectively between 1988 and 2000, but thickness was measured on paraffin sections for this study. Minimum follow‐up was 2 years, and thickness was correlated with local control, cervical node involvement, and survival. Patients with clinically positive nodes (n = 21) were not excluded. Overall, 55 patients had pathologic node involvement at some time in their disease.Results.Median tumor thickness was 6.2 mm, and there was little variation between sites: tongue, 6.4 mm; floor of mouth, 6.6 mm; and other sites, 5.7 mm. Median thickness for T1 tumors was 4.3 mm, significantly less than the T2 group, 8 mm (p < .01). Median thickness also varied significantly for tumors with associated nodal disease (8.5 mm) and without nodal disease (5.8 mm) (p < .01). Prognosis changed significantly at a cutoff of 4 mm with local control, nodal disease, and survival rates of 91%, 8%, and 100%, respectively, for tumors <4 mm compared with 84%, 48%, and 74% for those 4 mm or more thick (p < .01). Subgrouping greater than and less than 3 mm and 5 mm also showed a difference but with poorer discrimination. Thickness and pathologic nodal involvement were highly significant independent prognostic factors.Conclusions.Tumor thickness is a highly significant, objectively measurable prognostic factor in early stage oral cancers. There is a need to standardize techniques of measurement to allow a multiinstitutional study to be carried out. This will facilitate the development of strategies aimed at improving the outcome of higher risk patients. © 2003 Wiley Periodicals, Inc. Head Neck 25: 000–000, 2003
Localisation of WE‐14 immunoreactivity in the developing mouse limbo‐corneal nerve net
Authors: Curry William James , Brockbank Simon , Mccollum Anna Patricia , Boyle Cliona , Gibson David 
Published: October 2003

AbstractWE‐14 is generated in subpopulations of chromogranin A immunopositive endocrine cells and neurons including those innervating the anterior uvea. This study investigated WE‐14 in intact sclero‐limbo‐corneal tissue from embryonic (E17), neonatal (N0‐N16), and adult mice using immunocytochemistry and confocal scanning laser microscopy. Weak WE‐14 immunostaining was observed at birth in nerve fibre tracts entering the corneal mid‐stroma from the limbo‐scleral junction. Immunopositive fibre tracts were evident throughout the cornea at N3; by N5 the mid‐stromal plexus had begun to generate fibre populations extending toward the developing corneal epithelium, and some varicose fibres terminated amongst the developing epithelium. Immunostaining was evident at N7 in the developing limbo‐scleral nerve net and some fibres exhibited a close association with unidentified vascular elements. By N11 and in subsequent neonates, the cornea had developed a distinct stratified nerve net composed of thick mid‐stromal and thinner upper stromal nerve fibre bundles; both possessed populations of varicose WE‐14 immunopositive fibres. In the adult, a sub‐epithelial network of varicose WE‐14 immunopositive fibres were evident at the limbo‐scleral junction. Some fibres exhibited a close association with unidentified vascular elements, while others extended into the upper peripheral corneal stroma. WE‐14 was evident in leashes throughout the basal corneal epithelium and generated fibres ramifying between the stratified epithelium with some fibres terminating amongst the outermost corneal epithelia. This study has demonstrated that WE‐14 was evident in the limbo‐corneal nerve net at birth and that its detection parallels corneal development to adulthood, where WE‐14 is evident in a subpopulation of nerve fibres. Microsc. Res. Tech. 62:408–414, 2003. © 2003 Wiley‐Liss, Inc.
Temporal and topographic ultrastructural alterations of rat heart myofibrils caused by thyroid hormone
Authors: Ferreira Paula Juliana , L'Abbate Carolina , Abrahamsohn Paulo Alexandre , Gouveia Cecilia Azevedo , Moriscot Anselmo Sigari 
Published: October 2003

AbstractIn order to further our understanding regarding the temporal and topographic ultrastructural aspects of the myocardium under thyrotoxicosis, thyroxine (T4; 25 and 100 μg/100 g bw) was administered to young rats 24 hours after birth until 15 days. The animals were then sacrificed, the hearts excised and weighed, and the ventricle tissue samples were then processed for confocal and transmission electron microscopy. At 48/72 hours and 1 week after initiation of T4 treatment with 100 μg/100 g bw, numerous lamellar bodies (probably formed by phospholipids) progressively accumulated in the heart. These bodies were observed in the cytosol, inside mitochondria and in the extracellular matrix. At 2 weeks of T4 treatment with 100 μg/100 g bw, lamellar bodies were virtually absent. Changes in cell shape, disorganization of intercellular junctions, and substantial myofibrillar disarray were observed in many cardiomyocytes. A gradient of myofibrillar disarray, which increased in abundance and intensity from the endocardium to the epicardium, was also observed. Immunocytochemical staining for desmin showed that the arrangement of this protein was disorganized in many cells of T4‐treated rats as compared with normal ones, confirming ultrastructural data. The predominant appearance of myofibrillar disarray, associated with disorganization of cytoskeletal proteins in the deep myocardium, may be due to higher mechanical wall stress and consequent higher metabolic demand. Alternatively, differential sensitivity of cardiomyocytes to thyroid hormone in different areas is also a possibility. Microsc. Res. Tech. 62:451–459, 2003. © 2003 Wiley‐Liss, Inc.
Historical origins of schizophrenia: Two early madmen and their illness
Authors: Heinrichs R. Walter 
Published: October 2003

AbstractSchizophrenia is a serious mental illness with a remarkably short recorded history. Unlike depression and
mania, which are recognizable in ancient texts, schizophrenia‐like disorder appeared rather suddenly in
the psychiatric literature of the early nineteenth century. This could mean that the illness is a recent disease
that was largely unknown in earlier times. But perhaps schizophrenia existed, embedded and disguised within more
general concepts of madness and within the arcane languages and cultures of remote times. Both possibilities
present major challenges to historical and psychiatric scholarship. These challenges are explored in this paper
by presenting two “new” cases of schizophrenia, one from the eighteenth and one from the fourteenth
century. The cases suggest that the illness may have existed as early as the medieval period. However,
establishing the population prevalence of schizophrenia in earlier times—and therefore resolving the
permanence‐recency debate—may not be a feasible enterprise. © 2003 Wiley Periodicals, Inc.
Thermodynamic characteristics and numerical modeling of internal nitridation of nickel base alloys
Authors: Christ H.‐J. , Chang S.‐Y. , Krupp U. 
Published: October 2003

AbstractKinetics and thermodynamics of the process of internal nitridation of various nickel‐base alloys have been investigated in oxygen‐free nitrogen atmospheres. Furthermore, the influence of formation and spalling of a protective oxide scale on the internal nitridation behavior of the alloys was studied by isothermal and cyclic oxidation tests in air. In general, nitridation kinetics of model nickel‐base alloys of the system Ni‐Cr‐Ti was found to obey a parabolic rate law indicating that the nitridation process is diffusion‐controlled. The temperature dependence of the nitridation rate constants is well described by an equation of the Arrhenius type. A thermodynamic calculation of the Ni‐Cr‐Ti‐Al‐N system was used to determine the nitrogen solubility in respective alloys as a function of temperature and alloy composition. The results show that a higher chromium content gives rise to an increase in the nitrogen solubility of Ni‐Cr‐Ti alloys leading to an increased nitridation rate in accordance with the experimental observations. From the calculated values for the nitrogen solubility, the diffusion coefficients of nitrogen were assessed using Wagner's classical theory of internal oxidation. A computer model of internal nitridation was developed that combines a commercial thermodynamic software (ChemApp) with a finite‐difference diffusion calculation. It was found that this model describes the internal nitridation process in reasonable agreement with the experimental results and allows to treat the case of simultaneous formation of different nitrides. The dependence of internal nitridation behavior on spalling and cracking of the oxide was incorporated into the simulation on the basis of simple assumptions showing that this calculation method successfully applies also to complex internal corrosion processes.
Nitridation in NH3‐H2O‐mixtures
Authors: Grabke H. J. , Strauss S. , Vogel D. 
Published: October 2003

AbstractExposures were conducted of iron, nickel, ferritic 1‐18%Cr steels, austenitic 18%Cr‐9%Ni‐ and 20%Cr‐31%Ni‐steels and a 16%Cr‐Ni‐base alloy at 500°C in He‐30%H2O and 70%H2O‐30%NH3, to compare the corrosion behaviour of these materials in water vapor as in conventional power plants with their behaviour in a NH3‐H2O mixture, i.e. under conditions of the “Kalina‐cycle”. After 50 h in He‐H2O generally a dense oxide scale had grown on iron and on the steels, whereas the scale grown in NH3‐H2O was porous, due to initial formation of the γ′‐ and ε‐nitrides, which are converted to Fe3O4 later. The porous scale allows internal nitridation of the Cr‐steels, nitrogen is transferred into the metal phase and reacts to finely dispersed CrN‐precipitates. This process causes stresses in the material and formation of cracks. The higher the Cr‐content of the material, the worse is the damage of the materials surface.Least corrosion damage occurs for iron and the 1%CrMo‐steel, however, the inward penetration of nitridation is greatest, and after 5 years on the low Cr‐steel a layer of about 15 mm would be embrittled by internal nitridation, formation of γ′ and ε‐nitride layers and external oxidation.Nickel is strongly damaged by intermediate formation of instable Ni3N, which causes internal stresses and cracking, but also pore formation by its decomposition. The surface region of the 15%Cr‐Ni‐base alloy is also destroyed by internal nitridation and extrusion of Ni‐particles, while for this material the inward penetration of nitridation is relatively slow due to the low solubility and diffusivity of N in Ni and Ni‐alloys.
Typical failures in pyrolysis coils for ethylene cracking
Authors: Jakobi D. , Gommans R. 
Published: October 2003

AbstractThis paper points out the main failure mechanisms for tubes and outlet parts of pyrolysis furnace coils. In most cases there is a combination of factors which ultimately lead to the failure, e. g. carburization and creep ductility exhaustion. This results in bulging, bending and ovalisation of the tubes. Also, brittle fracture during furnace trips can result in large, longitudinal cracks on many tubes in the furnace.The metallurgical background of the combined action of carburization and creep ductility exhaustion will be explained. Dense and stable oxide scales on the bore surface lower the amount of catalytic coke and also the carbon ingress into the alloy matrix (carburization). Carburization is also determined by the nickel content of the matrix. Creep ductility exhaustion is determined by the number of cycles (start/stop‐ and decoke cycles) and the nature (or severity) of these cycles.Pyrolysis tube failures can be prevented by a combination of proper furnace operation, materials choice, regular inspections and good design.
Filamentous carbon formation caused by catalytic metal particles from iron oxide
Authors: Bonnet F. , Ropital F. , Berthier Y. , Marcus P. 
Published: October 2003

AbstractThe thermodynamic equilibrium between metallic iron, iron oxides, iron carbides and an hydrocarbon/hydrogen mixture was calculated at 600°C. On the basis of the metastable Fe‐C‐O phase diagram, both metallic iron and iron oxides can be directly converted into carbides in reducing and carburizing atmosphere. Thermogravimetric (ATG) measurements have been performed in iC4H10‐H2‐Ar atmosphere at 600°C on reduced and pre‐oxidised iron samples. The kinetic of coke formation was studied on both surface states by sequential exposure experiments. The initial stages of the transformation were characterised by scanning electron microscopy (SEM) observations and X‐ray diffraction (XRD) analysis. On a reduced surface, the results are consistent with the mechanism currently proposed to explain catalytic coke formation. Cementite (Fe3C) is formed on the iron surface after carbon supersaturation (ac > 1). The graphite deposition on its surface (ac = 1) induces its decomposition. Iron atoms from cementite diffuse through the graphite and agglomerate to small particles that act as catalysts for further carbon deposition. A new mechanism of catalytic particle formation is proposed when an oxide scale initially covers the iron surface. In the carburizing and reducing atmosphere, magnetite (Fe3O4) can be directly converted into cementite (Fe3C). XPS analysis confirm that, in this process, metallic iron is not an intermediary specie of the oxide/carbide reaction. At the same time, graphite deposition occurs at the metal/oxide interface through the cracks present in the oxide scale. Iron carbide in contact with graphite is partially decomposed and acts as catalyst for graphitic filaments growth.
Copolyester/layered silicate nanocomposites: The effect of the molecular size and molecular structure of the intercalant on the structure and viscoelastic properties of the nanocomposites
Authors: Kalgaonkar Rajendra A. , Jog Jyoti P. 
Published: October 2003

AbstractThe preparation of poly(ethylene glycol‐co‐cyclohexane‐1,4‐dimethanol terephthalate)/layered silicate nanocomposites via a melt‐intercalation technique is reported. Layered silicates modified with different alkyl ammonium intercalants have been used for this purpose. A comparison is made between carefully chosen pairs of the nanocomposites, the choice depending on the cation‐exchange capacity or the intercalant concentration of the organically modified montmorillonite, to study the effects of the molecular size and molecular structure of the intercalant. The structure of the nanocomposites is characterized with wide‐angle X‐ray diffraction. The presence of well‐defined diffraction peaks and an observed increase in the interlayer spacing in the nanocomposites imply the formation of an intercalated hybrid. To investigate the viscoelastic behavior, these nanocomposites are also subjected to dynamic mechanical analysis. The dynamic mechanical properties show an increase in the storage modulus of the nanocomposites over the entire temperature range studied (except in the transition region from 68 to 78 °C) in comparison with that of the pristine polymer. The size of the intercalant molecule and the presence of functional groups capable of forming favorable interactions with the polymer govern the amount of polymer infiltrating the clay gallery space and control the increase in the modulus of the nanocomposite. The tan δ peak signifying the glass‐transition temperature shifts to lower temperatures in the nanocomposites. Interestingly, the nanocomposites show less damping than the pristine polymer. This behavior is understood in terms of the confinement of the polymer chains in the clay interlayer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3102–3113, 2003
The size and number of local free volumes in polypropylenes: A positron lifetime and PVT study
Authors: Kilburn D. , Bamford D. , Dlubek G. , Pionteck J. , Alam M. A. 
Published: October 2003

AbstractThe temperature dependence of the mean size of local free volumes in an amorphous atactic (aPP) and a semicrystalline syndiotactic polypropylene (sPP), and an amorphous ethylene‐propylene copolymer (E‐co‐P48) has been studied. Pressure‐volume‐temperature (PVT) experiments were performed for aPP, from which the hole fraction h of the Simha‐Somcynsky theory and the number density of holes were estimated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3089–3093, 2003