bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of metallic impurities in oxide semiconductors: first‐principles calculations and PAC experiments
Authors: Errico L. A. , Fabricius G. , Rentería M. 
Published: July 2004

AbstractWe report an ab‐initio comparative study of the electric‐field‐gradient tensor (EFG) and structural relaxations introduced by acceptor (Cd) and donor (Ta) impurities when they replace cations in a series of binary oxides: TiO2, SnO2, and In2O3. Calculations were performed with the Full‐Potential Linearized‐Augmented Plane Waves method that allows us to treat the electronic structure and the atomic relaxations in a fully self‐consistent way. We considered different charge states for each impurity and studied the dependence on these charge states of the electronic properties and the structural relaxations. Our results are compared with available data coming from PAC experiments and previous calculations, allowing us to obtain a new insight on the role that metal impurities play in oxide semiconductors. It is clear from our results that simple models can not describe the measured EFGs at impurities in oxides even approximately. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical conductivity of MoS2 based organic–inorganic nanocomposites
Authors: Benavente E. , Santa Ana M. A. , González G. 
Published: July 2004

AbstractThe electrical conductivities of a series of MoS2‐organic layer nanocomposites prepared by the intercalation of donors like poly(ethylene oxide) and secondary amines are compared. Although for intercalated MoS2 species a metallic behavior is expected, the products behave as semiconductors probably because of their layered nature. Observed conductivities at room temperature depend on the host‐guest charge transfer reflected in both the amount of residual lithium and the donor intercalation degree, as well as on the nature of the donor. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The thermal conductivity of inhomogeneous thermoelectric materials
Authors: Goldsmid H. J. , Sharp J. W. 
Published: July 2004

AbstractPrevious measurements on polycrystalline Bi–Sb have suggested an anomalously low value for the electronic thermal conductivity. These measurements were made using the Harman technique in which the figure of merit is found from the difference between the adiabatic and isothermal electrical resistivities. We now demonstrate that the determination of the thermal conductivity using this approach is unreliable if the material is inhomogeneous. Such inhomogeneity can be chemical in its origin or it can arise from anisotropic thermoelectric parameters in a polycrystalline sample. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analytical tight‐binding calculations for optical absorption in single wall carbon nanotubes
Authors: Buonocore F. , Vinciguerra V. , Coffa S. 
Published: July 2004

AbstractWe present our calculations of the optical absorption for dipole direct transitions in the tight binding zone folding scheme for single wall carbon nanotubes. We have applied the Fermi's golden rule by calculating the electric dipole matrix element and we provide an analytical expression for it. We have calculated the optical absorption of semiconducting zig‐zag SWNTs equally distributed and with gaussian distribution of the diameters, where collisional broadening of the density of states was taken into account. The calculated behavior is in agreement with optical density measurements for SWNTs. Our analytical calculations will be useful for the analysis of the optical emission and absorption from single wall carbon nanotubes. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Melting volume change of different crystalline lattices
Authors: Lu H. M. , Jiang Q. 
Published: July 2004

AbstractThrough considering the packing density and the lattice contraction of Goldschmidt's premise, volume changes of elements crystals with different structures on melting are modeled. It is found that the predictions of the model are in agreement with the experimental and other theoretical results. In addition, the volume change of the solid–solid transition is also determined. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Estimation of infectious disease parameters from serological survey data: the impact of regular epidemics
Authors: Whitaker H. J. , Farrington C. P. 
Published: July 2004

AbstractSerological surveys are a useful source of information about epidemiological parameters for infectious diseases. In particular they may be used to estimate contact rates, forces of infection, the reproduction number and the critical vaccination threshold. However, these estimation methods require the assumption that the infection is in endemic equilibrium. Such equilibria seldom exist in practice: for example, many common infections of childhood exhibit regular epidemic cycles. In this paper, we investigate whether ignoring such cycles produces biased estimates. We apply the methods to data on mumps and rubella in the U.K. prior to the introduction of the combined measles, mumps, rubella (MMR) vaccine. We conclude that past epidemics have only a marginal effect on estimates, and that standard methods that do not adjust for regular epidemics are valid. Copyright © 2004 John Wiley & Sons, Ltd.
Local influence analysis when interfacing toxicokinetic and proportional hazard models
Authors: Sartori Nicola , Thomaseth Karl , Salvan Alberto 
Published: July 2004

AbstractWe present a local influence analysis to assigned model quantities in the context of a dose–response analysis of cancer mortality in relation to estimated absorbed dose of dioxin. The risk estimation is performed using dioxin dose as a time‐dependent explanatory variable in a proportional hazard model. The dioxin dose is computed using a toxicokinetic model, which depends on some factors, such as assigned constants and estimated parameters. We present a local influence analysis to assess the effects on final results of minor perturbations of toxicokinetic model factors. In the present context, there is no evidence of local influence in risk estimates. It is however possible to identify which factors are more influential. Copyright © 2004 John Wiley & Sons, Ltd.
Flexible modelling of discrete failure time including time‐varying smooth effects
Authors: Tutz G. , Binder H. 
Published: July 2004

AbstractDiscrete survival models have been extended in several ways. More flexible models are obtained by including time‐varying coefficients and covariates which determine the hazard rate in an additive but not further specified form. In this paper, a general model is considered which comprises both types of covariate effects. An additional extension is the incorporation of smooth interaction between time and covariates. Thus, in the linear predictor smooth effects of covariates which may vary across time are allowed. It is shown how simple duration models produce artefacts which may be avoided by flexible models. For the general model which includes parametric terms, time‐varying coefficients in parametric terms and time‐varying smooth effects estimation procedures are derived which are based on the regularized expansion of smooth effects in basis functions. The approach is used to model the sojourn time in a psychiatric hospital. It is demonstrated how initial conditions which have non‐linear influence are damped over time. Copyright © 2004 John Wiley & Sons, Ltd.
Sample size for testing and estimating the difference between two paired and unpaired proportions: a ‘two‐step’ procedure combining power and the probability of obtaining a precise estimate
Authors: Cesana Bruno Mario 
Published: July 2004

AbstractClinical trials and scientific research studies are currently planned calculating sample sizes to fulfill power requirements, but the simultaneous need to obtain a satisfactorily precise effect estimate is not widely recognized. I have devised a ‘two‐step’ iterative procedure for comparing two binomial parameters for two paired and unpaired proportions (the most frequent situations in scientific research), which takes into account power and the probability of obtaining a predetermined precision of the effect estimate. The first step provides the sample size for the power of the statistical test, the expected width of its corresponding confidence interval, and the probability of obtaining, under the alternative hypothesis, confidence intervals whose width is less than that expected. The second step iteratively increases this sample size until the probability of obtaining such confidence intervals exceeds a required threshold. Copyright 2004 © John Wiley & Sons, Ltd.
Imputing gene–treatment interactions when the genotype distribution is unknown using case‐only and putative placebo analyses—a new method for the Genetics of Hypertension Associated Treatment (GenHAT) study
Authors: Davis Barry R. , Ford Charles E. , Boerwinkle Eric , Arnett Donna , Eckfeldt John , Black Henry 
Published: July 2004

AbstractThere is a sizeable literature on methods for detecting gene–environment interaction in the framework of case‐control studies, particularly with reference to the assumption of independence of genotype and exposure. In the context of a clinical trial, wherein gene–drug interactions with regard to outcomes are examined, these methods may be readily applied, as gene and drug are independent by randomization.In an active‐controlled trial (experimental treatment vs standard) that has collected genotype information, gene–drug interactions can be estimated. In addition, the effect of the experimental treatment vs placebo can be imputed by using data from a historical placebo‐controlled trial (standard vs placebo) if either (a) genotype information is available from the historical trial or (b) assumptions are made about the prevalence of genotype and the odds ratios of genotype and disease in the historical trial using information from other studies. Motivation for these procedures is provided by the Genetics of Hypertension Associated Treatment, a large pharmacogenetics, ancillary study of a hypertension clinical trial, and examples from published hypertension trials will be used to illustrate the methods. Copyright © 2004 John Wiley & Sons, Ltd.
Modelling relative survival using transformation methods
Authors: Price Dionne L. , Manatunga Amita K. 
Published: July 2004

AbstractPatient survival is often assessed as a measure of effectiveness of treatment in cancer clinical trials. The relative survival rate is a measure of patient survival corrected for the effect of other causes of death. We incorporate an additive hazards model for the overall force of mortality focusing attention on the form of the underlying disease process. Transformation models for the cause‐specific hazard rate describing the disease process are considered. We demonstrate a method for estimating the transformation parameter providing insight into the appropriate choice of model structure. The models include the additive and multiplicative structures as special cases. We write the models in the generalized linear model framework and demonstrate ease of fitting via existing statistical software. The methodology is applied to a Hodgkin's disease data set to assess the effect of clinical trial results on population survival. Our analysis concludes that the multiplicative structure provides a more appropriate description of the data as compared to the additive structure. Copyright © 2004 John Wiley & Sons, Ltd.
Covariate adjustment in clinical trials with non‐ignorable missing data and non‐compliance
Authors: Levy Douglas E. , O'Malley A. James , Normand Sharon‐Lise T. 
Published: July 2004

AbstractEstimating causal effects in psychiatric clinical trials is often complicated by treatment non‐compliance and missing outcomes. While new estimators have recently been proposed to address these problems, they do not allow for inclusion of continuous covariates. We propose estimators that adjust for continuous covariates in addition to non‐compliance and missing data. Using simulations, we compare mean squared errors for the new estimators with those of previously established estimators. We then illustrate our findings in a study examining the efficacy of clozapine versus haloperidol in the treatment of refractory schizophrenia. For data with continuous or binary outcomes in the presence of non‐compliance, non‐ignorable missing data, and a covariate effect, the new estimators generally performed better than the previously established estimators. In the clozapine trial, the new estimators gave point and interval estimates similar to established estimators. We recommend the new estimators as they are unbiased even when outcomes are not missing at random and they are more efficient than established estimators in the presence of covariate effects under the widest variety of circumstances. Copyright © 2004 John Wiley & Sons, Ltd.
Creating the OOSPICE model architecture—A case of reuse
Authors: Henderson‐Sellers B. , Bohling J. , Rout T. 
Published: July 2004

AbstractThe OOSPICE project aims at creating a capability assessment package for component‐based development (CBD), which complements and extends the ISO 15504 technical report (SPICE) and its pending standard. In addition, it will offer support for process definition, creation and tailoring in the CBD domain. The major deliverables are a process reference model for CBD, a process assessment methodology, a new CBD methodology and supporting toolset, and an underpinning CBD process metamodel. Here, we evaluate the various terminologies in current usage in OO, CBD, capability assessment and the ISO standards, and then describe the important architectural framework of the project, which brings together the two previously disparate fields of process and methodology metamodeling with capability assessment and improvement. Additionally, we show how elements of preexisting standards, such as ISO 15504 and ISO 12207, as well as elements of existing OO process metamodels can be successfully reused to create a standard for this new focus on component‐based systems development. Copyright © 2004 John Wiley & Sons, Ltd.
Discrepancy between cell injury and benzodiazepine receptor binding after transient middle cerebral artery occlusion in rats
Authors: Abe Kohji , Kashiwagi Yuto , Tokumura Miwa , Hosoi Rie , Hatazawa Jun , Inoue Osamu 
Published: July 2004

AbstractWe investigated postischemic alterations in benzodiazepine receptor, D1 dopamine receptor, and muscarinic acetylcholine receptor binding after transient middle cerebral artery (MCA) occlusion in rats using [3H]‐flumazenil, [3H]‐SCH23390, and [3H]‐N‐methyl‐4‐piperidyl benzilate ([3H]‐NMPB), respectively, as radioligand. These ligand bindings were determined at 3 and 24 h and at 3 and 7 days after ischemia/reperfusion of MCA by using autoradiographic methods. Ischemic cell injury was clearly detected from 3 h after ischemia/reperfusion and progressively increased from 3–24 h after ischemia/reperfusion of MCA. The area of cell injury reached maximum at 24 h after ischemia/reperfusion of MCA. [3H]‐SCH23390 binding was reduced to 47% of the contralateral side at 3 days after ischemia/reperfusion of MCA. After 7 days, [3H]‐SCH23390 binding was further reduced by 20% in the striatum. [3H]‐NMPB binding was slightly decreased in both the striatum and cerebral cortex at 3 days after ischemia/reperfusion of MCA, and [3H]‐NMPB binding in the striatum and cerebral cortex were reduced to 42 and 62% of the contralateral side at 7 days after ischemia/reperfusion of MCA. [3H]‐NMPB was also decreased at 24 h. In contrast, [3H]‐flumazenil binding was not decreased in the striatum and cerebral cortex within 7 days after ischemia/reperfusion of MCA. These results suggest that [3H]‐SCH23390 and [3H]‐NMPB binding do not correlate with cell injury by ischemia/reperfusion, although vulnerability to ischemia/reperfusion was observed with these receptors. In addition, central benzodiazepine receptor imaging might be essentially stable to neuronal cell injury induced by transient focal cerebral ischemia in rats, in contrast to the results of PET studies. Synapse 53:234–239, 2004. © 2004 Wiley‐Liss, Inc.
Determination of bladder neck position by intraoperative introital ultrasound in colposuspension: outcome at 6‐month follow‐up
Authors: Viereck V. , Bader W. , Skala C. , Gauruder‐Burmester A. , Emons G. , Hilgers R. , Krauss T. 
Published: July 2004

AbstractObjectiveTo determine whether open colposuspension modified by intraoperative ultrasound to prevent overcorrection is a safe and effective procedure.MethodsNinety women operated on for urodynamically proven genuine stress urinary incontinence underwent intraoperative introital ultrasound in a prospective observational clinical study. The positions of the bladder neck and proximal urethra were assessed by determining the parameters height (H), distance (D) and the urethrovesical angle (β) perioperatively and for up to 6 months postoperatively. Colposuspension of the bladder neck was performed with a vertical height correction, ΔH (resting Hintraop − resting Hpreop) of 1 to 10 mm. Bladder neck positions were determined on an individual basis by introital ultrasound before, during and after surgery.ResultsSurgical elevation of the bladder neck (median height correction, ΔH 4 mm) resulted in a median intraoperative elevation of 9 mm (6 months: 8 mm). All postoperative measurements showed a significant reduction of the median linear movement of the bladder neck during straining (P < 0.0001). Anti‐incontinence surgery resulted in a significant reduction of funneling and hypermobility 6 months after surgery (P < 0.0001). At 6‐month follow‐up, 94% (85/90) of the women were continent. Evaluation immediately after surgery showed voiding difficulties and urge symptoms in 9% (8/90) of the patients each and de novo urge incontinence in 1% (1/90).ConclusionsIntraoperative introital ultrasound can help to optimize the colposuspension procedure. Ultrasonographic measurement of height H allows for objectively assessing the surgical procedure and can reduce postoperative complications by preventing excessive correction. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Can Early Diagnosis of Symptomatic Colorectal Cancer Improve the Prognosis?
Authors: Gonzalez‐Hermoso Fernando , Perez‐Palma Julian , Marchena‐Gomez Joaquin , Lorenzo‐Rocha Nieves , Medina‐Arana Vincente 
Published: July 2004

AbstractPatients with colorectal cancer continue to present with relatively advanced tumors. Delay in diagnosis is often believed to have been a contributing factor, and the validity of this hypothesis has seldom been questioned. The aim of this study was to establish whether a delay in diagnosis is related to long‐term survival and if the most frequent symptoms were related to the stage or time at which the carcinoma was diagnosed. Data from 660 patients surgically treated for uncomplicated colorectal carcinoma in our institution between 1985 and 2000 were analyzed retrospectively. Age, sex, initial symptoms, duration of symptoms, neoplasm location, curative surgery, TNM stage, and survival time were the variables recorded. Patients were classified into two groups according to symptom duration: < 3 months versus ≥ 3 months. Comparative statistical analysis was performed for the two groups as well as the initial symptom, TNM stage, and survival time. Also, the initial symptoms most frequently reported were compared with the TNM stage. The two groups were found to be equal with regard to distribution of age, gender, location of the neoplasm, type of surgery performed, and TNM stage. We found that symptom duration was shortened in the presence of abdominal pain (p = 0.002) [odds ratio (OR) 0.53; 95% confidence interval (CI) 0.35–0.80] and was delayed in the presence of an anemic syndrome (p = 0.006) (OR 2.4; 95% CI 1.27–4.56). Also, the stage of the neoplasm was related to rectal bleeding (p < 0.001) and abdominal pain (p = 0.008). The log‐rank test indicated that duration of symptoms was not related to long‐term survival (p = 0.90). We concluded that the duration of colorectal cancer symptoms is not related to the stage or prognosis of tumors.
Regression of Type II Gastric Carcinoids in Multiple Endocrine Neoplasia Type 1 Patients with Zollinger‐Ellison Syndrome after Surgical Excision of All Gastrinomas
Authors: Richards Melanie L. , Gauger Paul , Thompson Norman W. , Giordano Thomas J. 
Published: July 2004

AbstractEnterochromaffin‐like (ECL) tumors are documented in patients with hypergastrinemia secondary to chronic atrophic gastritis or with Zollinger‐Ellison syndrome and multiple endocrine neoplasia type 1 (ZES‐MEN‐1). In patients with ECL tumors and atrophic gastritis, normogastrinemia after antrectomy has resulted in resolution, regression, or stabilization of ECL tumors. The natural history of ECL tumors associated with ZES‐MEN‐1 following normalization of gastrin levels after gastrinoma resection has not been previously reported. The purpose of this study was to determine the course of ECL tumors in patients with ZES‐MEN‐1 following normalization of serum gastrin levels after gastrinoma resection. Two patients with ZES‐MEN‐1 had biopsy‐proven ECL tumors on endoscopic evaluation. They then underwent surgical exploration that included distal pancreatectomy, enucleation of pancreatic head tumors, duodenotomy with excision of submucosal tumors, and peripancreatic lymphadenectomy. Gastric ECL tumors larger than 1.0 cm were locally excised. Patients underwent long‐term follow‐up with biochemical and endoscopic surveillance. Normogastrinemia was achieved and sustained following gastrinoma resection in two patients with ZES‐MEN‐1. Periodic endoscopic surveillance over a 6‐year period showed complete resolution of the ECL tumors. The development of ECL tumors associated with ZES‐MEN‐1 is multifactorial. Studies identified a genetic influence on tumor growth with loss of heterozygosity at the MEN‐1 gene locus in ECL tumors. The resolution of ECL tumors in ZES‐MEN‐1 patients who are normogastrinemic indicates that an elevated gastrin level is a primary initiator for development of these tumors. Therefore both genetic defects and hypergastrinemia are causative agents. Normalization of serum gastrin levels is critical for the prevention of aggressive forms of ECL tumors.
The processes of iron deposition in the common hornet (vespa affinis)
Authors: Hsu Chin‐Yuan 
Published: July 2004

Summry— Among insects, only honeybees and bumblebees deposit iron biominerals intracellularly. Although hornet's behaviour is affected by the magnetic field and their abdomen has magnetic remanence, it is not known whether hornets (Vespa affinis) deposit iron biominerals and whether the process of iron deposition in hornets is the same as that of honeybees and bumblebees. Transmission electron microscopy and atomic emission spectroscopy were employed to study intracellular iron deposition in hornets. Iron deposition began on day 2 after eclosion. Primary iron‐granules (IGs) are first formed in primary iron deposition vesicles (IDVs) by the aggregation of tiny dense particles. Primary IDVs are double membrane vesicles that seem to derive from endoplasmic reticulum (ER). Primary IGs enlarged continuously into IGs by the aggregation of tiny dense particles till day 5 after eclosion. Next, IGs and IDVs fused to enlarge on day 7. Between days 10 and 17 IGs enlarged continuously in size by the aggregation of tiny dense particles. The cloudy area beneath the inner membrane of IDVs plays an important role in the formation of the tiny dense particles. IGs became mature on day 25 and left a small space, about 10nm in width, between IGs and the outer membrane of IDVs. IDVs including IGs are randomly distributed within the cytoplasm of trophocytes beneath the cuticle of hornets. Elemental composition analysis indicates that IGs are mainly comprised of iron, phosphorus and minor amounts of calcium.