bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling evaporation using an artificial neural network algorithm
Authors: Sudheer K. P. , Gosain A. K. , Mohana Rangan D. , Saheb S. M.
Published: October 2002

This paper investigates the prediction of Class A pan evaporation using the artificial neural network (ANN) technique. The ANN back propagation algorithm has been evaluated for its applicability for predicting evaporation from minimum climatic data. Four combinations of input data were considered and the resulting values of evaporation were analysed and compared with those of existing models. The results from this study suggest that the neural computing technique could be employed successfully in modelling the evaporation process from the available climatic data set. However, an analysis of the residuals from the ANN models developed revealed that the models showed significant error in predictions during the validation, implying loss of generalization properties of ANN models unless trained carefully. The study indicated that evaporation values could be reasonably estimated using temperature data only through the ANN technique. This would be of much use in instances where data availability is limited. Copyright © 2002 John Wiley & Sons, Ltd.
Spectrophotometric discrimination of river dissolved organic matter
Authors: Baker Andy
Published: October 2002

There is a need to be able to differentiate the dissolved organic matter (DOM) fraction in river waters. Research in the 1970s and 1980s has attempted to utilize both absorbance and fluorescence to distinguish between DOM fractions in river waters, but both were limited by the available technology. Total organic carbon content has, therefore, been widely used as a standard method of measuring DOM concentration, although it has little power to differentiate DOM fractions. Recent advances in fluorescence spectrophotometry enable rapid and optically precise analysis of DOM. Here, we show how a combination of both fluorescence and absorbance can be used to discriminate statistically between spatial variations of DOM in tributaries in a small catchment of the Ouseburn, NE England. The results of the discriminant analysis suggest that about 70% of the samples can be correctly classified to its tributary. Discriminant function 1 explains 60·8% of the variance in the data and the fulvic‐like fluorescence intensity has the largest absolute correlation within this function; discriminant function 2 explains a further 21·5% of the variance and the fulvic‐like fluorescence emission wavelength has the largest absolute correlation within this function. The discriminant analysis does not correctly classify all tributaries every time, and successfully discriminates between the different tributaries 70% of the time. Occasions when the tributary waters are less well discriminated are due to either episodic pollution events (at two sites) or due to tributaries that have strong seasonal trends in spectrophotometric parameters, which allows the sites to be misclassified. Results suggest that spectrophotometric techniques have considerable potential in the discrimination of DOM in rivers. Copyright © 2002 John Wiley & Sons, Ltd.
Modelling interrill erosion in small cultivated catchments
Authors: Cerdan O. , Le Bissonnais Y. , Couturier A. , Saby N.
Published: October 2002

On the cultivated plateau of the loess belt area, the redistribution of precipitation is controlled by topography, cultural techniques and sealing processes. Recent multi‐scale studies carried out in northern France have provided quantitative references of interrill erosion rates. These experimental references have highlighted significant differences and evolution trends of mean sediment concentration in interrill flow between different defined categories of soil surface conditions, vegetation and rainfall characteristics. Thus, a classification of sediment concentration in interrill flow has been elaborated (Cerdan O, et al. 2002. Earth Surface Processes and Landforms 27(2): 193–205). The objective of this paper is to incorporate these results in the elaboration of the interrill erosion module of the STREAM model. At the field scale, this classification is used to assign a potential sediment concentration value to each agricultural field. For situations where there is no, or insufficient, experimental references, the classification is completed using a fuzzy logic approach. At the catchment scale, sediment is transported in proportion of the runoff volumes computed with the STREAM runoff module, and is deposited as a function of topography (vertical curvature, slope gradient), or vegetation cover. Sediment concentration thresholds were defined after field experiments; these thresholds define the limits above which sediment mass is deposited. The erosion component of the model has been tested with a data set from a small (ca 90 ha) intensively cultivated catchment. The quality of prediction given by the root‐mean‐square error (RMSE) is ca 8 t of precision on sediment delivery at the catchment outlet for observed sediment delivery that goes from 0·075 to 21 t (with an RMSE of ca 0·9 t for observed sediment delivery below 1 t and of ca 10·6 t for observed sediment delivery between 1 and ca 21 t). The evaluation also showed that the results at the outlet of the catchment are more sensitive to the concentration thresholds of the deposition rules than to the potential sediment concentration values assigned to each field. Copyright © 2002 John Wiley & Sons, Ltd.
Heavy metal transport in large river systems: heavy metal emissions and loads in the Rhine and Elbe river basins
Authors: Vink Rona , Behrendt Horst
Published: October 2002

Pollutant transport and management in the Rhine and Elbe basins is still of international concern, since certain target levels set by the international committees for protection of both rivers have not been reached. The analysis of the chain of emissions of point and diffuse sources to river loads will provide policy makers with a tool for effective management of river basins. The analysis of large river basins such as the Elbe and Rhine requires information on the spatial and temporal characteristics of both emissions and physical information of the entire river basin. In this paper, an analysis has been made of heavy metal emissions from various point and diffuse sources in the Rhine and Elbe drainage areas. Different point and diffuse pathways are considered in the model, such as inputs from industry, wastewater treatment plants, urban areas, erosion, groundwater, atmospheric deposition, tile drainage, and runoff. In most cases the measured heavy metal loads at monitoring stations are lower than the sum of the heavy metal emissions. This behaviour in large river systems can largely be explained by retention processes (e.g. sedimentation) and is dependent on the specific runoff of a catchment. Independent of the method used to estimate emissions, the source apportionment analysis of observed loads was used to determine the share of point and diffuse sources in the heavy metal load at a monitoring station by establishing a discharge dependency. The results from both the emission analysis and the source apportionment analysis of observed loads were compared and gave similar results. Between 51% (for Hg) and 74% (for Pb) of the total transport in the Elbe basin is supplied by inputs from diffuse sources. In the Rhine basin diffuse source inputs dominate the total transport and deliver more than 70% of the total transport. The diffuse hydrological pathways with the highest share are erosion and urban areas. Copyright © 2002 John Wiley & Sons, Ltd.
Scaling and regionalization of flood flows in British Columbia, Canada
Authors: Eaton Brett , Church Michael , Ham Darren
Published: October 2002

A regionalization of flood data in British Columbia reveals a common scaling with drainage area over the range 0·5×102<Ad<104 km2. This scaling is not a function of flood return period, which implies that simple scaling—consistent with a snowmelt‐dominated flow regime—applies to the province. The observed scale relation takes the form $Q \propto A_{d}^{0{\cdot}75}$, similar to values reported in previous studies. The scaling relation identified was used to define the regional pattern of hydroclimatic variability for flood flows in British Columbia after discounting the effect of drainage area. The pattern was determined by kriging a scale‐independent runoff factor k for the mean annual flood, 5 year flood and 20 year flood. The analysis permits quantification of uncertainty of the estimates, which can be used in conjunction with the mapped k‐fields to calculate a mean and range for floods with the identified return period for ungauged basins. Owing to the sparsity of data, the precision is relatively poor. The standard error is generally less than 75% of the estimate in the southern half of the province, whereas in the northern half it is often between 75 and 100%. Examination of the relative increase in flood magnitude with increasing return period reveals spatially consistent but statistically insignificant differences. Flood magnitude tends to increase more rapidly in the western regions, where rain events may contribute to flood generation. The relative increase in flood magnitude with return period is consistently lower in the eastern mountain ranges, where snowmelt dominates the flood flow regime. Copyright © 2002 John Wiley & Sons, Ltd.
Contaminant transport in fractured media: analytical solution and sensitivity study considering pulse, Dirac delta and sinusoid input sources
Authors: Shih David Ching‐Fang , Lin Gwo‐Fong , Wang I‐Sen
Published: October 2002

The analytical solution of one‐dimensional transport for a single species radioactive nuclide, considering the decay term in a single fracture for pulse, Dirac delta, and single sinusoid input sources, has been studied using the Laplace transform method. The dimensionless concentration of the radioactive nuclide in the fracture appears to be a function of space, elapsed time, dispersivity, retardation factor, half‐life of the nuclide, and release time. By comparing different values of groundwater velocity, retardation factor, dispersivity, and release time, the results show that the c/c0 ratio agrees with the nature of the physical and chemical characteristics of the nuclide in fracture transportation. The dimensionless concentration peak value from a small retardation factor is found to be more sensitive, within a time frame ranging from 10 years to a few hundreds years, than the case with a larger retardation factor for H‐3. Except for a small variation in the peak value, the result is almost the same for pulse and sinusoid inputs when considering the H‐3 nuclide. Analytical solutions during the preliminary screening phase are suitable for performance assessment on radioactive waste disposal sites under a one‐dimensional single fracture condition. Copyright © 2002 John Wiley & Sons, Ltd.
Laboratory flume studies of microflow environments of aquatic plants
Authors: Shi Z. , Hughes J. M. R.
Published: October 2002

The microflow environments of aquatic plants with reference toMyriophyllumandHydrillaare simulated in a laboratory flume. A Nix Streamflow microflow meter was used to measure the mean velocity profiles of flow at different densities of plants, flow ranges and measurement positions. Each mean velocity profile consists of three hydrodynamic regimes (i.e. within‐canopy zone, above‐canopy zone and a transitional zone between them), which indicate the presence of two benthic boundary layers (internal and external ones). Out of 38 measured mean velocity profiles, most do not fit a logarithmic relationship. The following hydrodynamic parameters are used in characterizing the flow regimes: local shear velocity (u*), roughness length (zo), canopy roughness Reynolds number (Re*), bed shear stress (τo) and laminar sublayer (σ). Copyright © 2002 John Wiley & Sons, Ltd.
New frontiers for arch models
Authors: Engle Robert
Published: October 2002

In the 20 years following the publication of the ARCH model, there has been a vast quantity of research uncovering the properties of competing volatility models. Wide‐ranging applications to financial data have discovered important stylized facts and illustrated both the strengths and weaknesses of the models. There are now many surveys of this literature. This paper looks forward to identify promising areas of new research. The paper lists five new frontiers. It briefly discusses three—high‐frequency volatility models, large‐scale multivariate ARCH models, and derivatives pricing models. Two further frontiers are examined in more detail—application of ARCH models to the broad class of non‐negative processes, and use of Least Squares Monte Carlo to examine non‐linear properties of any model that can be simulated. Using this methodology, the paper analyses more general types of ARCH models, stochastic volatility models, long‐memory models and breaking volatility models. The volatility of volatility is defined, estimated and compared with option‐implied volatilities. Copyright © 2002 John Wiley & Sons, Ltd.
Detecting multiple breaks in financial market volatility dynamics
Authors: Andreou Elena , Ghysels Eric
Published: October 2002

The paper evaluates the performance of several recently proposed tests for structural breaks in the conditional variance dynamics of asset returns. The tests apply to the class of ARCH and SV type processes as well as data‐driven volatility estimators using high‐frequency data. In addition to testing for the presence of breaks, the statistics identify the number and location of multiple breaks. We study the size and power of the new tests for detecting breaks in the conditional variance under various realistic univariate heteroscedastic models, change‐point hypotheses and sampling schemes. The paper concludes with an empirical analysis using data from the stock and FX markets for which we find multiple breaks associated with the Asian and Russian financial crises. These events resulted in changes in the dynamics of volatility of asset returns in the samples prior and post the breaks. Copyright © 2002 John Wiley & Sons, Ltd.
Bridging the gap between the distribution of realized (ECU) volatility and ARCH modelling (of the Euro): the GARCH‐NIG model
Authors: Forsberg Lars , Bollerslev Tim
Published: October 2002

This paper bridges the gap between traditional ARCH modelling and recent advances on realized volatilities. Based on a ten‐year sample of five‐minute returns for the ECU basket currencies versus the US dollar, we find that the realized volatilities constructed from the summation of the high‐frequency intraday squared returns conditional on the lagged squared daily returns are approximately Inverse Gaussian (IG) distributed, while the distribution of the daily returns standardized by their realized volatilities is approximately normal. Moreover, the implied daily GARCH model with Normal Inverse Gaussian (NIG) errors estimated for the ECU returns results in very accurate out‐of‐sample predictions for the three years of actual daily Euro/US dollar exchange rates. Copyright © 2002 John Wiley & Sons, Ltd.
Maximum likelihood estimation of STAR and STAR‐GARCH models: theory and Monte Carlo evidence
Authors: Chan Felix , McAleer Michael
Published: October 2002

Theoretical and practical interest in non‐linear time series models, particularly regime switching models, have increased substantially in recent years. Given the abundant research activity in analysing time‐varying volatility through Generalized Autoregressive Conditional Heteroscedasticity (GARCH) processes (see Engle,1982; Bollerslev,1986), it is important to analyse regime switching models with GARCH errors. A popular specification in this class is the (stationary) Smooth Transition Autoregressive–GARCH (STAR‐GARCH) model. Little is presently known about the structure of the model, or the consistency, asymptotic normality and finite sample properties of the estimators. The paper develops the structural and statistical properties of the STAR‐GARCH model, and investigates the finite sample properties of maximum likelihood estimation (MLE) of STAR and STAR‐GARCH models through numerical simulation. The effects of fixing the threshold value and/or the transition rate for the STAR model, misspecification of the conditional mean and the transition function of the STAR‐GARCH model, and the finite sample properties of the MLE for the STAR‐GARCH model, are also examined. These numerical results are used as a guide in empirical research, with an application to Standard and Poor's Composite 500 Index returns for alternative STAR‐GARCH models. Copyright © 2002 John Wiley & Sons, Ltd.
Some comments on risk
Authors: Granger Clive W. J.
Published: October 2002

Investor risk is a complicated concept in practice and is not well captured by measures of volatility as is well understood by uncertainty theory. Rather than asking statisticians to attempt to measure risk, it may be better to listen to decision theorists, but their suggestions are not very practical. Diversification is clearly helpful in reducing risk but the risk level of one portfolio cannot be measured without knowing the risks of other major portfolios. A meta‐analysis can be used to compare alternative volatility measures in terms of their forecasting utility. Copyright © 2002 John Wiley & Sons, Ltd.
GO‐GARCH: a multivariate generalized orthogonal GARCH model
Authors: van der Weide Roy
Published: October 2002

Multivariate GARCH specifications are typically determined by means of practical considerations such as the ease of estimation, which often results in a serious loss of generality. A new type of multivariate GARCH model is proposed, in which potentially large covariance matrices can be parameterized with a fairly large degree of freedom while estimation of the parameters remains feasible. The model can be seen as a natural generalization of the O‐GARCH model, while it is nested in the more general BEKK model. In order to avoid convergence difficulties of estimation algorithms, we propose to exploit unconditional information first, so that the number of parameters that need to be estimated by means of conditional information is more than halved. Both artificial and empirical examples are included to illustrate the model. Copyright © 2002 John Wiley & Sons, Ltd.
A theoretical comparison between integrated and realized volatility
Authors: Meddahi Nour
Published: October 2002

In this paper we provide both qualitative and quantitative measures of the precision of measuring integrated volatility by realized volatility for a fixed frequency of observation. We start by characterizing for a general diffusion the difference between realized and integrated volatility for a given frequency of observation. Then we compute the mean and variance of this noise and the correlation between the noise and the integrated volatility in the Eigenfunction Stochastic Volatility model of Meddahi (2001a). This model has as special cases log‐normal, affine and GARCH diffusion models. Using previous empirical results, we show that the noise is substantial compared with the unconditional mean and variance of integrated volatility, even if one employs five‐minute returns. We also propose a simple approach to capture the information about integrated volatility contained in the returns through the leverage effect. We show that in practice, the leverage effect does not matter. Copyright © 2002 John Wiley & Sons, Ltd.
Modelling and forecasting level shifts in absolute returns
Authors: Franses Philip Hans , Van Der Leij Marco , Paap Richard
Published: October 2002

Due to high and low volatility periods, time series of absolute returns experience temporary level shifts which differ in length and size. In this paper we modify the basic Censored Latent Effects Autoregressive [CLEAR] model, such that it can describe and forecast the location and size of such level shifts. For our particular application, we assume that technical trading variables may have explanatory value for future level shifts, where these effects may differ across upward‐ or downward‐tending markets. A natural competitor of the resultant switching regime CLEAR [SR‐CLEAR] model is a long‐memory model, which is known to pick up neglected level shifts. Hence, when we apply the SR‐CLEAR model to nine stock markets and document its good fit and forecasting ability, we compare it with a long‐memory model. Copyright © 2002 John Wiley & Sons, Ltd.
Estimating quadratic variation using realized variance
Authors: Barndorff‐Nielsen Ole E. , Shephard Neil
Published: October 2002

This paper looks at some recent work on estimating quadratic variation using realized variance (RV)—that is, sums ofMsquared returns. This econometrics has been motivated by the advent of the common availability of high‐frequency financial return data. When the underlying process is a semimartingale we recall the fundamental result that RV is a consistent (asM→ ∞) estimator of quadratic variation (QV). We express concern that without additional assumptions it seems difficult to give any measure of uncertainty of the RV in this context. The position dramatically changes when we work with a rather general SV model—which is a special case of the semimartingale model. Then QV is integrated variance and we can derive the asymptotic distribution of the RV and its rate of convergence. These results do not require us to specify a model for either the drift or volatility functions, although we have to impose some weak regularity assumptions. We illustrate the use of the limit theory on some exchange rate data and some stock data. We show that even with large values ofMthe RV is sometimes a quite noisy estimator of integrated variance. Copyright © 2002 John Wiley & Sons, Ltd.
Time irreversibility and EGARCH effects in US stock index returns
Authors: Chen Yi‐Ting , Kuan Chung‐Ming
Published: October 2002

In this paper we suggest using a modified version of the time reversibility (TR) test of Chen, Chou and Kuan (2000) as a complementary diagnostic test for time series models. The modified CCK test is easy to compute and requires weaker moment conditions than existing tests. Our simulations demonstrate that this test is powerful against asymmetry in volatility but the BDS test is not. In the empirical study of US stock index returns, we first find that these returns are all time irreversible. Applying the GARCH and EGARCH models to these returns, we also find that theQand BDS tests always accept the null hypothesis and cannot distinguish between these models. By contrast, the modified CCK test accepts only the EGARCH model with an order that can accommodate the underlying asymmetry in volatility. Our results suggest that the detected time irreversibility in these return series may be attributed to volatility asymmetry and that such asymmetry may be captured using a proper EGARCH model. Copyright © 2002 John Wiley & Sons, Ltd.
Financial volatility: an introduction
Authors: Franses Philip Hans , McAleer Michael
Published: October 2002

It is now 20 years since the publication of Engle's (1982) seminal paper, which introduced ARCH to the world. The ARCH paper had an enormous influence on both theoretical and applied econometrics, and was influential in the establishment of the discipline of Financial Econometrics. In this paper we provide an introduction to the special issue on modelling and forecasting financial volatility, which commemorates the Twentieth Anniversary of the publication of ARCH. Financial econometrics has become a mature discipline over the last two decades, and one of its major research objects is the modelling and forecasting of volatility. This special issue presents ten papers, all of which focus on volatility and risk. The papers examine issues such as the new frontiers of volatility, the selection of models for observed and unobserved volatility, the potential long‐memory property of volatility, and the measurement of volatility. The commonality of papers is that they do not examine the extant literature, which has been reviewed elsewhere, but rather outline a number of important issues that are not only of current interest, but are likely to remain so for many years to come. Copyright © 2002 John Wiley & Sons, Ltd.
Does gestational sac volume predict the outcome of missed miscarriage managed expectantly?
Authors: Acharya Ganesh , Morgan Heulwen
Published: October 2002

Purpose

The aim of this study was to investigate whether gestational sac volume (GSV) can predict the outcome of missed miscarriages that are managed expectantly.

Methods

This was a prospective observational study. Between February 1, 2000, and January 31, 2001, all patients with a confirmed first‐trimester missed miscarriage who chose to undergo expectant management were recruited to participate. A single investigator performed all sonographic examinations and measurements. The main outcome measure was a complete spontaneous abortion within 4 weeks of the initial diagnosis. A complete miscarriage was defined as a maximum anteroposterior diameter of the endometrium of less than 15 mm on transvaginal sonography and no persistent heavy vaginal bleeding. The patients could opt to undergo surgery at any time, but those who had not expelled the products of conception within 4 weeks of the diagnosis were advised to have surgical uterine evacuation.

Results

In total, 90 patients were enrolled, and 86 patients completed the study. The mean GSV, as measured by 3‐dimensional sonography, was 9.7 ± 8.9 ml, and the mean sac diameter was 24.5 ± 8.0 mm. A significant exponential correlation was found between the mean sac diameter and the GSV (r = 0.86; p < 0.0001). Forty‐six (53.5%) of the 86 patients experienced a complete miscarriage within 4 weeks of the diagnosis (ie, expectant management was successful), but expectant management was unsuccessful in the remaining 40 (46.5%) patients (5 had an incomplete miscarriage, and 35 did not expel the products of conception). The GSV did not differ significantly between the “successful” and “unsuccessful” groups (p = 0.82). A logistic regression analysis showed no significant correlation between GSV and the outcome of missed miscarriages managed expectantly (p = 0.59).

Conclusions

The GSV does not predict the outcome of expectant management of missed miscarriage within 4 weeks of the diagnosis. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30: 526–531, 2002; Published online in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/jcu.10107
Comparison of two‐dimensional and three‐dimensional sonography in evaluating fetal malformations
Authors: Xu Hui‐Xiong , Zhang Qing‐Ping , Lu Ming‐De , Xiao Xian‐Tao
Published: October 2002

Purpose

We assessed the differences between 2‐dimensional (2D) and 3‐dimensional (3D) sonography (US) in evaluating fetal malformations.

Methods

Both 2D US and 3D US were used to examine pregnant women whose fetuses had malformations. The diagnostic information provided by the modalities was evaluated and compared.

Results

A total of 62 malformations were confirmed by postnatal or postmortem follow‐up in 41 fetuses of 40 pregnant women. 2D US made a definite and correct diagnosis of 49 malformations (79%), whereas 3D US definitely diagnosed 58 malformations (94%) (p < 0.01). 3D US definitely diagnosed all the abnormalities in 38 fetuses (93%), whereas 2D US did so in only 32 fetuses (78%) (p < 0.05). In 35 (60%) of the 58 malformations revealed by both 3D US and 2D US, the former provided more diagnostic information than the latter. 3D US was particularly superior to 2D US in evaluating fetal malformations of the cranium and face, spine and extremities, and body surface.

Conclusions

In comparison with 2D US, 3D US improves the diagnostic capability by offering more diagnostic information in evaluating fetal malformations, particularly in displaying fetal malformations of the cranium and face, spine and extremities, and body surface. 3D US is a valuable adjunct to 2D US in prenatal diagnosis. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30:515–525, 2002; Published online in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/jcu.10109
Sonographic features with histologic correlation in two cases of palpable breast cancer after breast augmentation by liquid silicone injection
Authors: Cheung Yun‐Chung , Lee Kam‐Fai , Ng Shu‐Hang , Chan Siu‐Cheung , Wong Alex Mun‐Ching
Published: October 2002

Sonography is rarely used to evaluate the breasts in patients who have undergone liquid silicone injections for breast augmentation because strong acoustic shadowing from the resulting silicone granulomas hampers the examination. We report on 2 patients who underwent silicone injection 18 and 20 years earlier and in whom breast cancers (1 invasive ductal carcinoma and 1 carcinosarcoma) were diagnosed by sonographically guided core‐needle biopsy. On sonograms, both cancers had a peripheral hypoechoic rim surrounding an echogenic center. The echogenic center corresponded histologically to a silicone granuloma in 1 patient and to a large area of necrosis in the other; the hypoechoic rims corresponded to areas of cancer in both patients. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30: 548–551, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10110
Accuracy of sonography with a hydration test in differentiating between excretory renal obstruction and renal sinus cysts
Authors: Nicolau Carlos , Vilana Ramon , Del Amo Montse , Anguera Albert , Sala Xavier , Pages Mario , Arguis Pedro , Brú Concepcio
Published: October 2002

Purpose

The aim of this prospective study was to determine whether sonography with a hydration test to induce diuresis can be used to reliably differentiate between excretory renal obstruction and renal sinus cysts.

Methods

We performed sonographic examination of all patients diagnosed with minimal or moderate obstruction of the intrarenal collecting system or renal sinus cysts on the basis of excretory urography, CT, or both between September 1, 1998, and October 31, 1999. The largest fluid‐filled structures in the renal sinus were sonographically measured before and after each patient ingested 1.5 l of water. Cases in which the maximum diameters of the largest anechoic structures increased by at least 10% after hydration were diagnosed with excretory renal obstruction. The sonographic diagnoses were compared with the final diagnoses on excretory urography, CT, or both.

Results

Both kidneys were affected in 16 of the 36 patients examined, for a total of 52 kidneys. The sonographic diagnosis was consistent with the results of urography or CT in 48 (92%) of the 52 kidneys. The sonographic approach had a specificity of 92% and a sensitivity of 93% for the diagnosis of excretory renal obstruction, with only 1 false‐negative and 3 false‐positive results.

Conclusions

When used with the stimulated diuresis test, sonography can reliably distinguish between excretory renal obstruction and renal sinus cysts and can be used as an alternative to other imaging techniques such as urography. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30: 532–536, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10111
Unusual sonographic finding in a patient with late recurrence of a perianal fistula
Authors: Mayoral Jaime L. , Rubal Bernard J.
Published: October 2002

We describe a case of late recurrence of a perianal fistula in a 51‐year‐old man with a 4.5‐year history of recurrent perianal fistulas and abscesses. This was the fourth recurrence he had experienced; at each occurrence, he had undergone various examinations, including sigmoidoscopy, anoscopy, barium enema, fistulography, probe exploration, instillation of hydrogen peroxide, and/or sonography, and he had also undergone surgery. At our examination, transperineal sonography with a portable ultrasound scanner revealed an echogenic linear structure within the fistulous tract. Under endoanal sonographic guidance, surgery was performed, and a tan solid cylindrical structure longer than 2 cm was removed. Histopathologic examination revealed stratified squamous epithelium and soft tissue with substantial fibrosis and mild chronic inflammation, findings consistent with the characteristics of a remnant cast from a previous fistulous tract. Our findings suggest that some patients may benefit from relatively inexpensive sonographic examination with appropriate transducers. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30: 557–561, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10113
Quantitative Doppler evaluation of the splenoportal venous system in various stages of cirrhosis: Differences between right and left portal veins
Authors: Kutlu Ramazan , Karaman Ibrahim , Akbulut Ahmet , Baysal Tamer , Sigirci Ahmet , Alkan Alpay , Aladag Murat , Seckin Yuksel , Saraç Kaya
Published: October 2002

Purpose

The purpose of our study was to evaluate the relationship between the splenoportal hemodynamics in patients with cirrhosis and the stage of the disease.

Methods

Patients with cirrhosis were grouped according to modified Child‐Pugh scoring into stages A, B, and C of cirrhosis. A control group of healthy volunteers was included. After gastroenterologic clinical and laboratory examinations, all participants underwent a splenoportal Doppler sonographic evaluation in which the vessels' diameter, area, and blood flow velocity were measured and blood flow rate and the congestion index in the splenoportal venous system were calculated.

Results

Seventy‐five patients with cirrhosis (25 women and 50 men) were enrolled; the control group consisted of 30 healthy volunteers (15 women and 15 men) with no liver disease. The mean age (± standard deviation) of the patients was 54.4 ± 14.8 years (range, 13–80 years) and of the control subjects was 47.3 ± 14.5 years (range, 18–72 years). No significant differences in vessel diameter, blood flow velocity, and blood flow rate were found in the main and left portal veins between the study group and the control group. In the right portal vein, we found decreases in the vessel diameter, blood flow velocity, and blood flow rate, and in the splenic vein, we found increases in vessel diameter and blood flow rate. The congestion index was increased in the main portal and splenic veins but was unchanged in the left portal vein.

Conclusions

Although our data indicate that there is no difference in Doppler sonographic parameters of the main portal vein according to Child‐Pugh scores, the hemodynamic differences between the left and right branches of the portal vein may be clinically useful in patients with cirrhosis. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30: 537–543, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10114
Lower‐extremity deep venous thrombosis after upper‐extremity port catheter placement: An unusual complication
Authors: Mihmanli Ismail , Cantasdemir Murat , Kantarci Fatih , Mandel Nil Molinas , Cokyuksel Oktay
Published: October 2002

We describe the case of a woman with breast carcinoma who experienced deep venous thrombosis of the right lower extremity after placement of a double‐lumen central venous chemotherapy port catheter in the left upper extremity. Color Doppler sonography revealed a linear tubular structure within the right common femoral vein and sonographic features of thrombosis, suggesting deep venous thrombosis secondary to displacement of the port catheter. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30: 562–565, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10115
Sonographic findings in a duodenal duplication cyst
Authors: Narlawar Ranjeet S. , Rao Jhanvi R. , Karmarkar Santosh J. , Gupta Arunima , Hira Priya
Published: October 2002

We report the sonographic features of a duodenal duplication cyst containing ectopic pancreatic tissue in a 5‐month‐old boy who presented with symptoms of partial gastric outlet obstruction. Sonography revealed an anechoic, double‐walled, bilobed cystic lesion containing debris in the pyloroduodenal region. There was sound through‐transmission but no air or communication with the gastrointestinal tract. Surgical resection and histopathologic examination confirmed a duodenal duplication cyst containing pancreatic tissue. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30: 566–568, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10117
Acute lymphoblastic leukemia relapse in the breast diagnosed with gray‐scale and color Doppler sonography
Authors: Likaki‐Karatza Eleni , Mpadra Filitsa A. , Karamouzis Michalis V. , Ravazoula Panagiota , Koukouras Dimitrios , Margariti Sofia , Dimopoulos Ioannis
Published: October 2002

Extramedullary relapses of acute lymphoblastic leukemia (ALL) in children and young adults are rare and in most cases are localized in the central nervous system, testes, or both. We describe a rare case of extramedullary relapse of ALL in the breast of a 17‐year‐old girl. The patient, who had been diagnosed with ALL 1 year before and had been in complete remission for 5 months, was admitted to the hospital for investigation of a mass in her left breast. On clinical examination, she had a large, palpable, nontender mass in her left breast. Mammography revealed a very dense mass. On gray‐scale and power Doppler sonography, the appearance of the mass was consistent with malignancy. Histopathologic examination of a surgical biopsy specimen permitted accurate diagnosis of ALL. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30: 552–556, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10118
Thyrotoxic Periodic Paralysis: Sonographic appearances of the thyroid
Authors: King Ann D. , Chow Francis C. C. , Ahuja Anil T. , Richards Polly S.
Published: October 2002

Purpose

The aim of the study was to describe the sonographic appearances of the thyroid in patients with thyrotoxic periodic paralysis (TPP).

Methods

Of the 25 patients diagnosed with TPP between January 1, 1998, and December 31, 2001, as identified by a search of our patient database, 13 had undergone sonography of the thyroid. We retrospectively reviewed the clinical records and thyroid sonograms of these 13 patients. The sonograms were assessed subjectively for thyroid size, echogenicity, vascularity, and the presence of solid nodules and cysts.

Results

Sonography showed abnormality of the thyroid in all 13 patients. In 11 patients (85%), sonography showed widespread hypoechogenicity (compared with the muscle) whose distribution was diffuse (6 patients) or patchy (5 patients) and diffusely distributed areas of hypervascularity (type 1 pattern). All 11 of these patients had a clinical diagnosis of Graves' disease. One patient (8%) had multinodular goiter and enlargement of the thyroid with multiple heterogeneous solid nodules and cysts (type 2 pattern); the clinical diagnosis was toxic multinodal goiter. One patient (8%) had a combination of type 1 and type 2 patterns and a clinical diagnosis of Graves' disease.

Conclusions

The sonographic abnormalities of the thyroid in patients with TPP reflect the common underlying causes of thyrotoxicosis in the general population. The sonographic appearances associated with Graves' disease (type 1 pattern) were the most common abnormality detected. No sonographic features specific to TPP were identified. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30: 544–547, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10119
Origins of the cognitive (r)evolution
Authors: Mandler George
Published: October 2002

The well documented cognitive “revolution” was, to a large extent, an evolving return to attitudes and trends that were present prior to the advent of behaviorism and that were alive and well outside of the United States, where behaviorism had not developed any coherent support. The behaviorism of the 1920 to 1950 period was replaced because it was unable to address central issues in human psychology, a failure that was inherent in part in J. B. Watson's founding manifesto with its insistence on the seamless continuity of human and nonhuman animal behavior. The “revolution” was often slow and piecemeal, as illustrated by four conferences held between 1955 and 1966 in the field of memory. With the realization that different approaches and concepts were needed to address a psychology of the human, developments in German, British, and Francophone psychology provided some of the fuel of the “revolution.” © 2002 Wiley Periodicals, Inc.
When scientific knowledge becomes scientific discovery: The disappearance of classical conditioning before Pavlov
Authors: Logan Cheryl A.
Published: October 2002

In the nineteenth century, scientific materials in experimental physiology changed dramatically. In this context, phenomena that had been widely accepted were lost, sometimes to be reintroduced later as “discoveries.” I describe the loss of the phenomenon of classical conditioning, later rediscovered by Ivan Pavlov. In 1896, Austrian physiologist Alois Kreidl demonstrated experimentally that animals anticipate the occurrence of food that is cued by a variety of stimuli. Kreidl stated, moreover, that the fact that animals can be called to food had been widely known to science since the 1830s. I describe Kreidl's work and discuss several factors that may have led to the disappearance of conditioning prior to its rediscovery by Pavlov. © 2002 Wiley Periodicals, Inc.
Psychology's public image in “Topics of the Times”: Commentary from the editorial page of the New York Times between 1904 and 1947
Authors: Dennis Paul M.
Published: October 2002

Between 1904 and 1947, the New York Times published in a section of its editorial page, “Topics of the Times,” 196 commentaries on psychology. Prior to World War I, the majority of editorials centered on Hugo Münsterberg; psychological topics most frequently examined after the war were the mental test, child rearing advice, and psychoanalysis. Although the Times was enthusiastic in its support for psychology in the years immediately before and after World War I, editorial opinion soon turned negative. Critical of psychology for promising more than it could deliver, being inconsistent in its assertions over time, and not rising above the level of common sense, Times editorials weighed heavily on the side of undermining, rather than promoting, psychology's credibility from the late 1920s to 1940s. © 2002 Wiley Periodicals, Inc.
Moral education for the elite of democracy: The classe de philosophie between sociology and philosophy
Authors: Barberis Daniela S.
Published: October 2002

In this article, I address the issues at stake in the relationship between sociology and philosophy in the second half of the nineteenth century by focusing on a debate between two parties: Émile Durkheim, who was attempting to found an independent scientific sociology, and the editors and collaborators of the Revue de métaphysique et de morale (RMM), one of the central philosophical journals of the period. This debate focused on the role of philosophy in secondary school education, but at its heart, this was a struggle between two disciplines over which ought to direct the formation of good citizens for Third Republic France. © 2002 Wiley Periodicals, Inc.
Expression of the green fluorescent protein in the oligodendrocyte lineage: A transgenic mouse for developmental and physiological studies
Authors: Yuan Xiaoqing , Chittajallu Ramesh , Belachew Shibeshih , Anderson Stacie , McBain Chris J. , Gallo Vittorio
Published: October 2002

We generated a transgenic mouse expressing the enhanced green fluorescent protein (EGFP) under the control of the 2′‐3′‐cyclic nucleotide 3′‐phosphodiesterase (CNP) promoter. EGFP+ cells were visualized in live tissue throughout embryonic and postnatal development. Immunohistochemical analysis in brain tissue and in sciatic nerve demonstrated that EGFP expression was restricted to cells of the oligodendrocyte and Schwann cell lineages. EGFP was also strongly expressed in “adult” oligodendrocyte progenitors (OPs) and in gray matter oligodendrocytes. Fluorescence‐activated cell sorting allowed high‐yield purification of EGFP+ oligodendrocyte‐lineage cells from transgenic brains. Electrophysiological patch clamp recordings of EGFP+ cells in situ demonstrated that OP cells displayed large outward tetraethylammonium (TEA)‐sensitive K+ currents and very small inward currents, whereas mature oligodendrocytes were characterized by expression of large inward currents and small outward K+ currents. The proliferation rate of EGFP+ cells in developing white matter decreased with the age of the animals and was strongly inhibited by TEA. Oligodendrocyte development and physiology can be studied in live tissue of CNP‐EGFP transgenic mice, which represent a source of pure EGFP+ oligodendrocyte‐lineage cells throughout development. © 2002 Wiley‐Liss, Inc.
Primary motor neurons fail to up‐regulate voltage‐gated sodium channel Nav1.3/brain type III following axotomy resulting from spinal cord injury
Authors: Hains Bryan C. , Black Joel A. , Waxman Stephen G.
Published: October 2002

Epilepsy occurs in a small proportion of patients with spinal cord injury (SCI), but whether it is due to concomitant traumatic head injury or to changes in cortical motor neurons secondary to axotomy within the spinal cord is not known. Nav1.3/brain type III sodium channel expression is up‐regulated following peripheral axotomy of dorsal root ganglion (DRG) and facial motor neurons, but, to date, Nav1.3 expression has not been examined in upper (cortical) motor neurons following axotomy associated with SCI. In the present study, we examine Nav1.3 expression in upper motor neurons within rat primary motor cortex following midthoracic (T9) dorsal column transection, which severs the axons of those cells. Axotomized pyramidal cells were identified by retrograde transport of fluorogold. Immunolabeled cells were confined to layer V of the primary motor cortex and exhibited low levels of Nav1.3 staining. After axotomy, no significant changes were detected in Nav1.3 density or distribution in injured or uninjured cells, compared with control brains, in contrast to up‐regulation of Nav1.3 in ipsilateral DRG neurons after sciatic nerve transection. These results do not preclude a role for voltage‐gated sodium channels in post‐SCI epilepsy but suggest that up‐regulated expression of Nav1.3 channel is not involved. © 2002 Wiley‐Liss, Inc.
Single cell activity patterns of pedunculopontine tegmentum neurons across the sleep‐wake cycle in the freely moving rats
Authors: Datta Subimal , Siwek Donald F.
Published: October 2002

Microinjections of the excitatory amino acid, L‐glutamate into the cholinergic cell compartment of the pedunculopontine tegmentum (PPT) of the rat induces both wakefulness and/or rapid eye movement (REM) sleep depending on the glutamate dosage. However, no studies have systematically recorded the electrical activity of these cells in the freely moving rat across the sleep‐wake cycle. In this study, we have recorded the spontaneous activity patterns of single PPT cells (n = 70) in the freely moving rat across the sleep‐wake cycle. PPT neurons were classified into three groups based on patterns in their spontaneous activity. The first group of cells (12.86%) was more active during REM sleep than they were during wakefulness or slow‐wave sleep (SWS). The second group of cells (60.0%) was more active during REM and wakefulness than during SWS. The firing rate of the third group of cells (27.14%) did not change as a function of behavioral state. This study also demonstrated that the level of activity within the cholinergic cell compartment of the PPT during SWS drops to 7.4% of that observed during wakefulness and that during REM sleep it changes to 65.5% of wakefulness levels. These findings indicate that in the freely moving rat, the discharging of PPT neurons correlates with wakefulness and REM sleep. Additionally, these neurons may be an integral part of the brainstem wakefulness and REM sleep‐generating mechanisms in the rat. © 2002 Wiley‐Liss, Inc.