bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redundancy and the choice of hydrologic indices for characterizing streamflow regimes
Authors: Olden Julian D. , Poff N. L. 
Published: March 2003

AbstractThe utility of hydrologic indices for describing various aspects of streamflow regimes has resulted in their increased application in riverine research. Consequently, researchers are now confronted with the task of having to choose among a large number of competing hydrologic indices to reduce computational effort and variable redundancy prior to statistical analyses, while still adequately representing the major facets of the flow regime. The present study addresses this concern by providing a comprehensive review of 171 currently available hydrologic indices (including the commonly used Indicators of Hydrologic Alteration) using long‐term flow records from 420 sites from across the continental USA. We highlight patterns of redundancy among these hydrologic indices and provide a number of statistically and ecologically based recommendations for the selection of a reduced set of indices that can simultaneously (1) explain a dominant proportion of statistical variation in the complete set of hydrologic indices and (2) minimize multicollinearity while still adequately representing recognized, critical attributes of the flow regime. In addition, we examine the transferability of hydrologic indices across ‘stream types’ by identifying indices that consistently explain dominant patterns of variance across streams in varying climatic and geologic environments. Together, our results provide a framework from which researchers can identify hydrologic indices that adequately characterize flow regimes in a non‐redundant manner. In combination with ecological knowledge, this framework can guide researchers in the parsimonious selection of hydrologic indices for future hydroecological studies. Copyright © 2003 John Wiley & Sons, Ltd.
A comparison of methods for evaluating instream flow needs for recreation along rivers in southern Alberta, Canada
Authors: Rood Stewart B. , Tymensen Wilco , Middleton Ron 
Published: March 2003

AbstractFour methods were compared for determining recreational instream flow needs (R‐IFN) for paddling canoes, kayaks and rafts on ten river reaches in the Oldman River Basin of southern Alberta. Two flow criteria were evaluated: ‘minimal flow’—the low flow that still provides a reasonable quality river trip; and ‘sufficient flow’—the lower end of the favoured flow range. A voluntary, mail‐in user survey from 1983 to 1997 produced 394 responses (4251 paddler days) relative to flow suitability. An expert judgment approach considered flow recommendations from three regional paddling guides that were considered comprehensive and credible. A flow comparison involved about 20 paddle trips per reach by the authors with differing groups, boats and flows. These subjective approaches produced quite consistent results (r2 = 0.63) and these were compared to results from an objective, hydraulic modelling method, the ‘depth, discharge method’ (DDM), that applied stage–discharge functions to determine flows that would satisfy depth criteria of 60 and 75 cm. The DDM minimal flows were closely correlated with the means of the subjective methods (r2 = 0.73). Thus, all four approaches produced generally consistent results, indicating that all methods were valid. Typical minimal and sufficient flows were about 15 and 30 m3 s−1, respectively, for the medium‐sized river reaches that had average annual discharges (mean Q) of about 20 m3 s−1. A close correlation (r2 = 0.90) between the minimal flow and mean Q suggests that mean Q can provide an initial estimate for R‐IFN for rivers of this type and size. We recommend that R‐IFN studies commence with the DDM since it is quick, inexpensive and objectively defensible. This would provide guidelines for subsequent subjective assessments that should involve more than one approach to increase the breadth of subjective consideration. Copyright © 2003 John Wiley & Sons, Ltd.
Microelectronic Bonding Processes Monitored by Integrated Sensors
Authors: Mayer M. , Schwizer J. 
Published: March 2003

AbstractReal‐time monitoring methods are beneficial for the control, optimization, and failure analysis of microelectronic packaging processes. The focus of this chapter is on the real‐time monitoring of two widely used processes, soft solder die bonding and thermosonic ball bonding. The methods presented here use uniquely developed microsensors integrated on custom‐made test chips using commercial double‐metal CMOS processes.For the soft solder die bonding process, nine aluminum‐based resistive temperature detectors were integrated on various locations on a test chip. The temperature was monitored during the placement of the test chip on the leadframe. The experimental results describe the wetting and spreading effects of the molten solder under the drip. Together with numerical results obtained with a transient thermal finite element model, the beginning of wetting can be quantified. For the soft solder PbSn10, wetting occurred around 30 ms after touch down. This method hence can be used to determine wetting times under different process conditions. The wetting time determines an upper limit of the through put of the process.For the thermosonic ball bonding process, temperature and force sensors were integrated on test chips. The sensors are aluminum resistors and piezoresistivep+‐ andn+‐diffused resistors placed around bond pads. A bond quality parameter can be derived from the temperature signal variation during bonding. The piezoresistive sensors permit the measurement of forces in the x‐, y‐, and z‐directions simultaneously. The ultrasonic tangential force signal reached a typical value of 0.12 N on a 50μm diameter contact zone and revealed significant process characteristics. Four process phases are identified which are necessary for a successful ball bond formation. These phases are assigned to initial stiction, sliding, bond growth, and deformation effects.
XPS analysis of petroleum well tubing adherence
Authors: Cosultchi A. , Rossbach P. , Hernandez‐Calderon I. 
Published: March 2003

AbstractUndesired material adhered to the internal surface of the tubing wall of some petroleum wells is critical for crude oil production. Field samples of steel with petroleum solid adherence were characterized by means of x‐ray photoelectron spectroscopy, x‐ray diffraction and atomic absorption spectroscopy. The deposit naturally adhered on the steel surface is structurally formed by a thin, black and hard corrosion product layer (inner layer) ∼15 µm thick under a thick, black and brittle organic deposit layer (outer layer) ∼0.01 m thick composed mainly of hydrocarbons. This outer layer contains small amounts of barium sulphate (BaSO4) co‐precipitated with organic compounds, which may contribute to the deposit's lack of cohesion. On the contrary, the inner layer of the deposit is firmly adhered to the steel substrate and contains clay minerals and iron compounds embedded in the hydrocarbon layer. Copyright © 2003 John Wiley & Sons, Ltd.
Transition models for change‐point estimation in logistic regression
Authors: Pastor‐Barriuso Roberto , Guallar Eliseo , Coresh Josef 
Published: March 2003

AbstractAlthough a wide variety of change‐point models are available for continuous outcomes, few models are available for dichotomous outcomes. This paper introduces transition methods for logistic regression models in which the dose–response relationship follows two different straight lines, which may intersect or may present a jump at an unknown change‐point. In these models, the logit includes a differentiable transition function that provides parametric control of the sharpness of the transition at the change‐point, allowing for abrupt changes or more gradual transitions between the two different linear trends, as well as for estimation of the location of the change‐point. Linear‐linear logistic models are particular cases of the proposed transition models. We present a modified iteratively reweighted least squares algorithm to estimate model parameters, and we provide inference procedures including a test for the existence of the change‐point. These transition models are explored in a simulation study, and they are used to evaluate the existence of a change‐point in the association between plasma glucose after an oral glucose tolerance test and mortality using data from the Mortality Follow‐up of the Second National Health and Nutrition Examination Survey. Copyright 2002 John Wiley & Sons, Ltd.
The use of putative placebo in active control trials: two applications in a regulatory setting
Authors: Durrleman Sylvain , Chaikin Philip 
Published: March 2003

AbstractFor life‐threatening diseases, ethical considerations preclude the inclusion of an untreated control group in the investigation of a new therapeutic agent when a standard therapy exists. In these cases, active controlled studies are conducted, and may be planned to demonstrate either superiority or equivalence/non‐inferiority of the new drug over the standard therapy (active control). In the non‐inferiority study, an important aspect is the ability to detect an inferior drug (assay sensitivity). It has been suggested that assay sensitivity for a non‐inferiority study should be deduced from historical data, specifically placebo controlled studies with the standard therapy. The assessment of assay sensitivity may also be important in a superiority trial that fails to demonstrate a statistically significant difference between treatments, and the sponsor attempts to determine whether there is lack of inferiority as an alternative hypothesis for regulatory approval. This paper describes two methods of putative placebo analysis for assessing assay sensitivity in active controlled trials. One approach imputes a point estimate for the odds ratio (95 per cent confidence interval) for a new drug (T) compared to a placebo control (P). A Bayesian approach calculates the posterior probability that T is superior to P, or, that T is at least k per cent as good as the active control (A) and A is more effective than P. These methods are applied in two clinical/regulatory settings: a phase III trial comparing docetaxel (Taxotere) to doxorubicin in metastatic breast cancer patients, and a phase III programme with two trials comparing enoxaparin (Lovenox) plus aspirin to unfractionated heparin plus aspirin in patients with unstable angina or non‐Q‐wave myocardial infarction. The methodologies presented in this paper were used in securing regulatory approval for docetaxel in the treatment of locally advanced or metastatic breast cancer after failure of prior chemotherapy, and for enoxaparin in the treatment of acute coronary syndrome. Copyright © 2003 John Wiley & Sons, Ltd.
Mid‐course sample size modification in clinical trials based on the observed treatment effect
Authors: Jennison Christopher , Turnbull Bruce W. 
Published: March 2003

AbstractIt is not uncommon to set the sample size in a clinical trial to attain specified power at a value for the treatment effect deemed likely by the experimenters, even though a smaller treatment effect would still be clinically important. Recent papers have addressed the situation where such a study produces only weak evidence of a positive treatment effect at an interim stage and the organizers wish to modify the design in order to increase the power to detect a smaller treatment effect than originally expected. Raising the power at a small treatment effect usually leads to considerably higher power than was first specified at the original alternative. Several authors have proposed methods which are not based on sufficient statistics of the data after the adaptive redesign of the trial. We discuss these proposals and show in an example how the same objectives can be met while maintaining the sufficiency principle, as long as the eventuality that the treatment effect may be small is considered at the design stage. The group sequential designs we suggest are quite standard in many ways but unusual in that they place emphasis on reducing the expected sample size at a parameter value under which extremely high power is to be achieved. Comparisons of power and expected sample size show that our proposed methods can out‐perform L. Fisher's ‘variance spending’ procedure. Although the flexibility to redesign an experiment in mid‐course may be appealing, the cost in terms of the number of observations needed to correct an initial design may be substantial. Copyright © 2003 John Wiley & Sons, Ltd.
Non‐parametric estimators of a monotonic dose–response curve and bootstrap confidence intervals
Authors: Dilleen Maria , Heimann Günter , Hirsch Ian 
Published: March 2003

AbstractIn this paper we consider study designs which include a placebo and an active control group as well as several dose groups of a new drug. A monotonically increasing dose–response function is assumed, and the objective is to estimate a dose with equivalent response to the active control group, including a confidence interval for this dose. We present different non‐parametric methods to estimate the monotonic dose–response curve. These are derived from the isotonic regression estimator, a non‐negative least squares estimator, and a bias adjusted non‐negative least squares estimator using linear interpolation. The different confidence intervals are based upon an approach described by Korn, and upon two different bootstrap approaches. One of these bootstrap approaches is standard, and the second ensures that resampling is done from empiric distributions which comply with the order restrictions imposed. In our simulations we did not find any differences between the two bootstrap methods, and both clearly outperform Korn's confidence intervals. The non‐negative least squares estimator yields biased results for moderate sample sizes. The bias adjustment for this estimator works well, even for small and moderate sample sizes, and surprisingly outperforms the isotonic regression method in certain situations. Copyright © 2003 John Wiley & Sons, Ltd.
Resettable smart dampers for multi‐level seismic hazard mitigation of steel moment frames
Authors: Barroso Luciana R. , Chase J. Geoffrey , Hunt Stephen 
Published: March 2003

AbstractA main goal of supplemental control devices is to manage the energy dissipation in the system. Resettable devices have emerged as a promising control device for application to civil structures as they are effective energy dissipators. This paper presents an investigation of the ability of semi‐active control methods utilizing resettable devices to mitigate structural response in the presence of hysteretic, geometric and yielding nonlinearities under various intensity level seismic hazard suites to define control efficacy and seismic hazard statistics. A major component of this research is to assess the effect of device placement on control benefit. Results show that resettable devices limited to realistic peak force/dissipation levels of ∼13% building weight are effective at limiting permanent deflections and indicate the importance of zero tracking for nonlinear systems. However, floor accelerations rise significantly as displacement is limited, and the performance improvement is not the same for all ground motions. Owing to predominantly first‐mode response of the case study structure, peak and permanent drifts saw larger reductions as more device authority was placed at the base of the structure, although the best overall results distributed device authority roughly proportional to the structural storey shears. Copyright © 2003 John Wiley & Sons, Ltd.
The cerebroplacental Doppler ratio revisited
Authors: Baschat A. A. , Gembruch U. 
Published: March 2003

AbstractObjectiveTo evaluate the distribution of Doppler pulsatility index (PI) measurements of the umbilical and middle cerebral arteries in singleton fetuses of women with normal uterine artery blood flow and to construct reference ranges for the cerebroplacental PI Doppler ratio.MethodsThe PI was determined in the mid‐portion of the umbilical artery and the mid‐ or distal segment of the middle cerebral artery in 306 normal singleton fetuses. The cerebroplacental Doppler ratio (CPR) was determined from paired measurements. After determination of the best fit, reference ranges were constructed for each parameter against gestational age (GA).ResultsThe PI for the umbilical artery had a linear relationship with GA (umbilical artery PI = − 0.0246 × GA + 1.7791, r2 = 0.4025, P < 0.001). The middle cerebral artery PI and the CPR both showed a quadratic relationship with GA (middle cerebral artery PI = − 0.0058 × GA2 + 0.3335 × GA − 2.7317, r2 = 0.2365, P < 0.01), (CPR = − 0.0059 × GA2 + 0.383 × GA − 4.0636, r2 = 0.2788, P < 0.001).ConclusionThe CPR is not constant throughout gestation. Reference ranges constructed by a standardized Doppler technique may be of benefit in the monitoring of high‐risk pregnancies. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Does transvaginal sonographic measurement of cervical length before 14 weeks predict preterm delivery in high‐risk pregnancies?
Authors: Berghella V. , Talucci M. , Desai A. 
Published: March 2003

AbstractObjectiveTo determine whether high‐risk patients manifest cervical length < 25 mm on transvaginal ultrasound before 14 weeks of gestation, and if this finding is predictive of preterm delivery.MethodsAsymptomatic pregnancies at high risk for preterm birth were followed prospectively from 10 + 0 weeks to 13 + 6 weeks with transvaginal sonographic measurement of the cervix. A cervical length < 25 mm was considered a short cervix at this gestational age and at the follow‐up ultrasound examinations, performed between 14 and 24 weeks. The primary outcome was preterm birth at < 35 weeks of gestation.ResultsOne hundred and eighty‐three pregnancies met the study criteria and were included in the analysis. Only 10 (5%) patients had a cervix < 25 mm before 14 weeks. The sensitivity, specificity and positive and negative predictive values of a short cervix were 14%, 97%, 50%, and 82%, respectively (relative risk, 2.8; 95% confidence interval, 1.4–5.6). The mean transvaginal sonographic cervical length before 14 weeks of gestation was 33.7 ± 6.9 mm in pregnancies which delivered preterm (n = 36), and 35.0 ± 6.8 mm in those delivering at term (n = 147) (P = 0.3). Follow‐up transvaginal ultrasound examination of the cervix to 24 weeks revealed that the average gestational age at which a short cervix was detected was 18.7 ± 2.9 weeks.ConclusionA cervical length < 25 mm on transvaginal sonographic assessment rarely occurs before 14 weeks even in high‐risk patients destined to deliver preterm; in these patients cervical changes predictive of preterm birth develop mostly after this gestational age. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal nasal bone length: reference range and clinical application in ultrasound screening for trisomy 21
Authors: Bunduki V. , Ruano R. , Miguelez J. , Yoshizaki C. T. , Kahhale S. , Zugaib M. 
Published: March 2003

AbstractObjectivesFetuses with trisomy 21 typically present with subtle facial abnormalities, including a hypoplastic nasal bone. The aim of this study was to provide a reference range for the length of the fetal nasal bone and to test its value in second‐trimester ultrasound screening for trisomy 21.DesignA reference range of fetal nasal bone length was established from cross‐sectional data on 1923 consecutive singleton pregnancies scanned at 16–24 weeks' gestation in women older than 35 years. Screening for trisomy 21 was prospectively studied using the measurement of fetal nasal bone lengths smaller than the 5th percentile as a cut‐off value.ResultsFollow‐up was possible in 1631 cases (84.8%). Trisomy 21 was found in 22 cases (1.35%). Nasal bone length measurement increased as a function of gestational age (P < 0.05) showing a linear relationship. Screening for trisomy 21 using the 5th percentile as a cut‐off value resulted in a sensitivity of 59.1% for a 5.1% false‐positive rate. The likelihood ratio was 11.6.ConclusionScreening for trisomy 21 using fetal nasal bone length measurements showed a sensitivity comparable to that of maternal biochemistry for a given false‐positive rate of 5%. Association of nasal bone lengths with other sonographic markers, taking into account the background risk for maternal and gestational age, may further improve sensitivity and reduce false positives, allowing avoidance of unnecessary invasive diagnostic procedures. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Invasive intrauterine treatment of pulmonary atresia/intact ventricular septum with heart failure
Authors: Arzt W. , Tulzer G. , Aigner M. , Mair R. , Hafner E. 
Published: March 2003

AbstractThe mortality and morbidity of children with pulmonary atresia/intact ventricular septum (PA/IVS) are linked to the degree of right ventricular (RV) hypoplasia. Opening up the pulmonary valve (PV) in fetal life could result in improved growth of the RV making it amenable to biventricular repair postnatally. Successful valvulotomy of the PV was performed in a fetus with heart failure at 28 weeks. Following the procedure there was significant growth of the tricuspid valve and RV. The neonate was delivered at 38 weeks with a RV suitable for biventricular repair. In utero pulmonary valvulotomy is feasible and may change the natural history of the condition in affected fetuses with PA/IVS. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Ba3P3I2 und Ba5P5I3: Stufenweise Oxidation von Bariumphosphid mit Iod
Authors: Nuss Jürgen , Jansen Martin 
Published: March 2003

AbstractDurch Reaktion von Bariumphosphid mit Iod wurden die neuen Verbindungen Ba3P3I2 und Ba5P5I3 erhalten. Die luft‐ und hydrolyseempfindlichen Verbindungen kristallisieren jeweils in einem neuen Strukturtyp: Ba3P3I2 (oP32, Pnma, a = 1719.5(5) pm, b = 462.4(2) pm, c = 1427.2(4) pm, Z = 4, R(F)N′ = 0.067 (N′(hkl) = 2667); Ba5P5I3 (mC52, C2/m, a = 4266.4(13) pm, b = 456.3(2) pm, c = 943.1(3) pm, β = 92.20(3)°, Z = 4, R(F)N′ = 0.040 (N′(hkl) = 3909). Beide können als ein Doppelsalz zwischen einer hypothetischen Zintl‐Phase ('Ba2P3' bzw. 'Ba7P10') und einem Halogenid (BaI2) beschrieben werden. Charakteristische Strukturmerkmale sind gewinkelte P3‐ und P4‐Ketten gemäß Ba3[P3]I2 bzw. Ba10[P3]2[P4]I6. Die Bindungsverhältnisse werden auf der Basis der Strukturmerkmale und physikalischen Eigenschaften interpretiert.
Die Kristallstruktur von KPr3Te8
Authors: Stöwe Klaus 
Published: March 2003

AbstractVon den Verbindungen der Zusammensetzung ALn3Q8 ( A = Na, K, Rb, Cs; Ln = Selten‐Erd‐Metall; Q = S, Se und Te) konnte die Struktur des Tellurids KPr3Te8 durch Einkristallstrukturanalyse gelöst und verfeinert werden. Kristalle der Verbindung konnten durch eine Synthese nach der Flux‐Technik mit K2Te3 als Flussmittel nach der Abtrennung des K2Te3‐Überschusses durch Extraktion mit absolutem Dimethylformamid (DMF) erhalten werden. Die Verbindung kristallisiert monoklin in der Raumgruppe P121/c1 mit den Gitterparametern a = 1390, 58(7) pm, b = 1291, 06(6) pm, c = 900, 18(5) pm und β = 99, 264(6)° isotyp zu KNd3Te8. Strukturmerkmale in der Kristallstruktur von KPr3Te8 sind gewinkelte Einheiten aus drei Telluratomen [Te3]2— sowie zick‐zack‐förmige unendliche Ketten aus Telluratomen [Te4]4—. Die kürzesten interatomaren Abstände in den Ketten alternieren mit 298 und 300 pm nur geringfügig und liegen im Bereich partieller Bindungen. Beide Strukturelemente sind in nahezu planaren Schichten angeordnet und untereinander durch ein System von sekundären Wechselwirkungen mit interatomaren Abständen im Bereich von 327 bis 349 pm verknüpft. Die Struktur von KPr3Te8 kann als Auffüllungs‐Defektvariante des binären NdTe3‐Typs verstanden werden. Dies wird anhand entsprechender Gruppe‐Untergruppe‐Beziehungen in Form eines Bärnighausen‐Stammbaums dargelegt.