bluuebunny/crossref_metadata_2025 huggingface dataset:
Valence bond descriptions of benzene and cyclobutadiene and their counterparts with localized bonds
Authors: Dijkstra Fokke , Van Lenthe Joop H. , Havenith Remco W. A. , Jenneskens Leonardus W.
Published: January 2003

Geometry optimizations have been performed for benzene and cyclobutadiene and for the corresponding moieties with nonresonating double bonds, viz. 1,3,5‐cyclohexatriene and 1,3‐cyclobutadiene. The calculations were done using the valence bond self‐consistent field method including orbital optimization. Both strictly local and delocalized p‐like orbitals were used for the π system, which influences the strengths of the π bonds. The calculations result in geometries and resonance and stabilization energies for benzene and cyclobutadiene, which are compared with theoretical models of aromaticity. The importance of resonance is discussed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
User‐parameterised generic models: a solution to the conundrum of modelling access for SMEs?
Authors: Winch Graham W. , Arthur Daniel J. W.
Published: January 2003

System dynamics (SD) has been shown to be a powerful strategic analysis approach, but it can also be a costly one. If there is an insistence that to have any validity and value, all models have to be constructed largely from scratch, then the time, expertise and costs involved appear, effectively, to preclude their widespread use in small–medium enterprise (SME) applications. This article describes “proof‐of‐concept” trials with a simulator based on a user‐parameterised generic model that could offer affordable and manageable access to SD modelling for SMEs. While not pretending to provide quantitative predictions, the simulator does provide managers with a vehicle to challenge the validity of their mental models as their firm undergoes major change, to gain insights into the future challenges, and maybe enhance their confidence through “pre‐experiencing” future scenarios. The trials concluded that user‐parameterised generic models do have potential value in this kind of usage, and may therefore be the only viable option for many smaller firms to benefit from system dynamics modelling and scenario planning. Copyright © 2002 John Wiley & Sons, Ltd.
Transforming an agricultural trade organization: a system‐dynamics‐based intervention
Authors: Weber Michael , Schwaninger Markus
Published: January 2003

The management of agricultural trade organizations in Switzerland is characterized by completely new entrepreneurial challenges due to a progressive opening of agricultural markets and a corresponding reform in the state's agricultural policy. The need for well‐suited strategic management tools has suddenly become manifest. Given this background, the intervention described in this article took place in a division of a union of cooperatives in the Swiss agribusiness, which is a typical example of a small to medium‐sized enterprise (SME). The aim of the project was to search for possible ways to sustain the viability of the division in the future. The intervention started with the development of an overall descriptive network‐type model of the strategically relevant issues faced by the division. A system dynamics (SD) model was built as a decision support tool for one of two crucial strategic issues: the organization of the distribution system. Based on the insights derived from model‐building and simulation, the management team changed its shared mental model of the issue at hand, achieving a deeper understanding of the situation faced, the options available and their implications. Thereupon, they have started to reorganize the whole distribution system. In sum, the modeling and simulation activities undertaken had a powerful trigger function in the process by inducing organizational learning at a very fast pace. Copyright © 2002 John Wiley & Sons, Ltd.
Opportunities and pitfalls related to e‐commerce strategies in small–medium firms: a system dynamics approach
Authors: Bianchi Carmine , Bivona Enzo
Published: January 2003

E‐commerce is often perceived as a powerful lever to foster growth of SMEs. However, both the literature and empirical evidence have shown the perils hidden in superficial decision making by SME entrepreneurs. A system dynamics (SD) approach is used in this article to demonstrate how managing processes of accumulation and depletion of strategic assets, detecting inertial effects of decisions made in the past, and selectively acting on policy levers are likely to help entrepreneurs in understanding opportunities and pitfalls related to e‐commerce strategies.

A feedback analysis of three case studies selected from the literature and the main findings from a survey conducted by the authors on SMEs pursuing e‐commerce strategies are discussed. Based on the insights developed through this analysis, the last section of the article shows a generic SD model aimed to help entrepreneurs to better understand processes of accumulation and depletion of strategic assets, in SMEs' e‐ventures. Copyright © 2002 John Wiley & Sons, Ltd.
Combining system dynamics and conjoint analysis for strategic decision making with an automotive high‐tech SME
Authors: Schmidt Markus J. , Gary Michael Shayne
Published: January 2003

An erratum has been published for this article in System Dynamics Review 18:4 2002, p. 533.

This article describes the use of system dynamics in combination with conjoint analysis to assist a high‐tech SME explore robust strategic policies in a context where customer preferences were critical to strategic decision making. Conjoint analysis served an important role in eliciting customers' underlying choice preferences and had a significant impact on the structure and parameterization of the final simulation model. The combination of methods was quite powerful in this case, and the authors feel it could be successfully applied to a broad class of problems where behavioral policies of decision makers include tradeoffs among multiple attributes. Methods developed to address the multi‐attribute choice problem (e.g., conjoint analysis) add needed precision to model formulation and validation. The alternative is to employ formulations that are not empirically derived or grounded in the extensive choice theory literature, and it is suggested that this alternative is not viable when model behavior is sensitive to choice preferences. Copyright © 2002 John Wiley & Sons, Ltd.
Introducing SD modelling into planning and control systems to manage SMEs' growth: a learning‐oriented perspective
Authors: Bianchi Carmine
Published: January 2003

This article emphasises the need for a learning‐oriented approach to planning and control as a prerequisite for SMEs' survival and growth. Such a perspective can be effectively pursued through the development of interactive learning environments linking system dynamics (SD) and accounting models, which provide two complementary views of business phenomena. In order to properly support the drawing up of business plans and the evaluation of results associated with their implementation, the use of financial SD models embodying the accounting perspective is recommended. This is likely to enhance a shift in SME key actors' minds, as they will be able to analyse under the feedback view financial variables they are used to frame only through the accounting ‘lens’. The article remarks how the specific features that sharply differentiate SMEs from larger firms discourage any systematic replication of the approaches commonly adopted in bigger companies practice, where SD has been more widely utilised. Copyright © 2002 John Wiley & Sons, Ltd.
Direct observation of growth motion of elements by ultrahigh vacuum scanning electron microscopy combined with total reflection angle x‐ray spectroscopy
Authors: Yamanaka Toshiro , Shimomura Naoharu , Ino Shozo
Published: January 2003

By using ultrahigh vacuum scanning electron microscopy (UHV‐SEM) combined with characteristic x‐ray spectroscopy under a grazing detection‐angle condition, the behaviours of elements on surfaces and at interfaces during the growth of Ga on an Si(111)‐√3 × √3‐Ag surface and of Au on Si(111)‐√3 × √3‐Ag were studied. Site exchange and other surrounding elements were observed directly. When a 2/3 monolayer of Ga was deposited, Ag was substituted by Ga and dissociated from the √3 × √3‐Ag structure, resulting in the formation of Ag particles 10–20 nm in size. During further Ga deposition, Ga surrounded the Ag particles. Substitution of Ag by Au also was observed during the growth of Au. Compared with the resolution of conventional SEM energy‐dispersive x‐ray spectrometry (EDX), which is several micrometres, resolution in elementary analysis has been improved significantly due to a small beam size and cut‐off of x‐rays from deep regions. Using the present method, local elementary analysis of surface structures of only ∼5 nm in size is possible. Copyright © 2003 John Wiley & Sons, Ltd.
Novel compositional accommodation mechanism in SrNbO3 epitaxial thin films revealed by analytical electron microscopy
Authors: Takeno S. , Ohara R. , Sano K. , Kawakubo T.
Published: January 2003

A novel compositional accommodation mechanism in perovskite (ABO3) SrNbO3 thin films was revealed by field‐emission analytical electron microscopy (AEM). A new analytical methodology for estimating localized structures such as planar faults is also presented. The method was applied for investigating the compositional accommodation mechanism of B‐ion‐rich SrNbO3 epitaxial thin films. Two types of accommodation mechanism—formation of B‐ion‐rich amorphous phase and (110)‐located high‐density planar defects—were revealed. The latter mechanism is a new finding for B‐ion‐rich perovskites. Copyright © 2003 John Wiley & Sons, Ltd.
Fe(O,OH)6 network structure of rust formed on weathering steel
Authors: Kimura M. , Suzuki T. , Shigesato G. , Kihira H. , Suzuki S.
Published: January 2003

X‐ray absorption fine structure (XAFS) analysis and transmission electron microscopy (TEM) have been used for investigating the atomic structure and microstructure of rust formed on a weathering steel and a relevant iron–chromium alloy. The XAFS results have shown that the atomic structure of the rust is an Fe(O,OH)6 network, which is formed during corrosion. From comparison of XAFS spectra for rust formed under different conditions, it has been shown that the Fe(O,OH)6 network structure evolves in the process of corrosion and a small amount of an alloying element such as chromium modifies the evolution process and morphology of the rust. Observation by TEM has revealed that rust formed on the weathering steel consists of heterogeneous but mainly very fine α‐FeOOH, which is caused by chromium. Copyright © 2003 John Wiley & Sons, Ltd.
Applications of continuous time hidden Markov models to the study of misclassified disease outcomes
Authors: Bureau Alexandre , Shiboski Stephen , Hughes James P.
Published: January 2003

Disease progression in prospective clinical and epidemiological studies is often conceptualized in terms of transitions between disease states. Analysis of data from such studies can be complicated by a number of factors, including the presence of individuals in various prevalent disease states and with unknown prior disease history, interval censored observations of state transitions and misclassified measurements of disease states. We present an approach where the disease states are modelled as the hidden states of a continuous time hidden Markov model using the imperfect measurements of the disease state as observations. Covariate effects on transitions between disease states are incorporated using a generalized regression framework. Parameter estimation and inference are based on maximum likelihood methods and rely on an EM algorithm. In addition, techniques for model assessment are proposed. Applications to two binary disease outcomes are presented: the oral lesion hairy leukoplakia in a cohort of HIV infected men and cervical human papillomavirus (HPV) infection in a cohort of young women. Estimated transition rates and misclassification probabilities for the hairy leukoplakia data agree well with clinical observations on the persistence and diagnosis of this lesion, lending credibility to the interpretation of hidden states as representing the actual disease states. By contrast, interpretation of the results for the HPV data are more problematic, illustrating that successful application of the hidden Markov model may be highly dependent on the degree to which the assumptions of the model are satisfied. Copyright © 2003 John Wiley & Sons, Ltd.
Transitions in an imperfectly observed binary variable: depressive symptomatology in adolescents
Authors: Wolfe Rory , Carlin John B. , Patton George C.
Published: January 2003

We describe a methodology for analysing transitions over time in a binary outcome variable that is subject to misclassification (that is, measurement error). Logistic regression models for transition events in the true underlying state are combined with estimates of probabilities of misclassification of the underlying state. The model is based on the Markovian assumption that the probabilities of transition in the underlying state at a given time depend only on the underlying state at the previous time. Hence we estimate odds‐ratio effects for transitions that are adjusted for the effect of misclassification. Comparing these adjusted estimates with estimates that are obtained without taking misclassification into account indicates that the latter can be biased either toward or away from the null. For the estimates to exist, certain restrictions on the observed data and misclassification probabilities need to be met. If these restrictions are not satisfied then the conclusion from the analysis is that all observed transition events can be explained solely by the error in outcome assessment, in which case it is likely that an aspect of the model is incorrect. The motivation for this work comes from an analysis of transitions in depression status for a cohort of Australian teenagers participating in a longitudinal study of adolescent health. Copyright © 2003 John Wiley & Sons, Ltd.
Latvia
Authors: Lhabitant François‐Serge , Novikova Svetlana
Published: January 2003

Situated on a trading crossroads between Western Europe and Russia, Latvia has emerged as one of the most
successful countries in Central Europe. This article provides a comprehensive review of Latvia's historical
development, political structure, economy, investment, and foreign‐trade environment. It aims to be a
useful source of information for foreign businessmen and investors interested in doing business in Latvia. In the
fall of 1991, when the Baltic States separated from the Soviet system, no one predicted that these countries
would make the transition to a market‐based economy as quickly and as effectively as they have. However,
11 years later, with notable growth and rising standards of living, such thinking is no longer considered overly
optimistic. “It is the biggest, most complicated, and most promising piece of the new Europe,” wrote
The Economist (1998) in reference to the Baltic region. Wherever there is new growth,
there are many business opportunities to be found. Latvia's position in the center of this region is one
indication of the business potential for those with the capacity to do business there. © 2003 Wiley
Periodicals, Inc.
The Eurozone formation: MNC and international bank reactions
Authors: Lees Francis , Mauer Laurence
Published: January 2003

Introduction of the Euro has brought dramatic changes to the perceptions and realities of MNC finance. These
changes vary considerably based on whether the multinational company has integrated its U.S. and European treasury
operations or is U.S. dollar‐centric in finance orientation. We conducted a survey to determine changes in
U.S.‐based MNC treasury practice resulting from the Eurozone formation. This article reports the results of
this survey with regard to hedging activities, European banking arrangements, and Euro financial market sourcing.
The effects on the two types of MNCs are compared. Implications for international banks are examined. Recent
Eurozone bank merger developments are also reviewed, with special focus on M&A developments in both France and
Germany. © 2003 Wiley Periodicals, Inc.
Prediction of early pregnancy viability in the absence of an ultrasonically detectable embryo
Authors: Elson J. , Salim R. , Tailor A. , Banerjee S. , Zosmer N. , Jurkovic D.
Published: January 2003

Objective

To identify clinical, ultrasound and biochemical parameters that may allow prediction of pregnancy viability in women without a detectable embryo on ultrasound examination.

Methods

This was a prospective observational study of pregnant women with an ultrasound finding of a gestational sac measuring < 20 mm mean diameter without a visible embryo. Women's age, menstrual dates, clinical symptoms (pain and bleeding), mean gestational sac diameter and measurements of serum beta‐human chorionic gonadotropin and progesterone were recorded in all cases. All women were managed expectantly until the pregnancy viability was established conclusively based on clinical and ultrasound findings. All parameters were tested by univariate analysis and then analyzed in a stepwise procedure to form a logistic regression model for predicting pregnancy viability.

Results

One hundred and eighteen (59%) women had a normal intrauterine pregnancy and 82 (41%) had a miscarriage. Stepwise analysis showed that three diagnostic parameters (maternal age, gestational sac diameter and serum progesterone) contributed significantly to the predictive power of the logistic model. With this model, at a cut‐off value of 10% probability, the diagnosis of viable pregnancy was made with a sensitivity of 99.2% (95% CI, 95.8–99.97) and specificity of 70.7% (95% CI, 61.3–78.9).

Conclusion

The use of a logistic regression model allows prediction of pregnancy viability when an embryo cannot be visualized on ultrasound scan. Copyright © 2002 ISUOG. Published by John Wiley & Sons, Ltd.
Isolated non‐compaction of the ventricular myocardium: prenatal diagnosis and natural history
Authors: Karatza A. A. , Holder S. E. , Gardiner H. M.
Published: January 2003

Isolated non‐compaction of the ventricular myocardium (NCVM) is a rare cardiomyopathy characterized by the persistence of numerous marked ventricular trabeculations and deep intertrabecular recesses with direct vascular supply by the ventricular cavities. We report two cases diagnosed by fetal echocardiography at 27 and 30 weeks' gestation, respectively. Postnatal echocardiography verified the presence of the NCVM seen prenatally. Diagnosis was confirmed at postmortem following neonatal demise in the first case. Surgical intervention for exomphalos and extrahepatic biliary atresia was required in the second case, but there is no clinical abnormality of the cardiovascular system a year after delivery. The uncertainty of prognosis and the familial recurrence described elsewhere indicate the difficulty of counseling and the value of prenatal diagnosis, which is feasible using currently available ultrasonographic equipment. Copyright © 2002 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal cardiac function assessed by Doppler myocardial performance index (Tei Index)
Authors: Friedman D. , Buyon J. , Kim M. , Glickstein J. S.
Published: January 2003

Objectives

The Tei Index (TI) is a useful, non‐invasive, Doppler‐derived myocardial performance tool which can be used to assess aspects of systolic and diastolic function. The aim of this study was to determine normal values of fetal left ventricular (LV) TI in second‐ and third‐ trimester fetuses and to compare these to other values reported in the literature.

Methods

Doppler waveforms of the LV outflow tracts were obtained in 74 second‐ and early third‐trimester fetuses. The LV isovolumic contraction time (ICT), isovolumic relaxation time (IRT) and ejection time (ET) were measured and the TI calculated using the formula (ICT + IRT)/ET. The literature on LV myocardial function in the fetus was also reviewed.

Results

The normal TI in second‐ and early third‐trimester fetuses (18–31 weeks' gestation) was 0.53 ± 0.13. The ICT was 43 ± 14 ms, the ET was 173 ± 16 ms and the IRT was 48 ± 13 ms.

Conclusion

The TI can be easily obtained in the fetus without the need for precise anatomic imaging. The TI may be a useful tool to explore fetal myocardial function in different clinical situations. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Changes in flow velocity patterns of the superior and inferior venae cavae during placental circulatory insufficiency
Authors: Fouron J.‐C. , Absi F. , Skoll A. , Proulx F. , Gosselin J.
Published: January 2003

Objectives

Placental circulatory insufficiency, expressed by the disappearance of the diastolic component of the umbilical artery Doppler velocity waveforms, causes blood flow redistribution that could disturb, to different extents, the systemic venous returns to the heart. The purpose of this study was to investigate the effect of an absence of diastolic blood flow in the umbilical artery on the relationship between the Doppler flow velocities of the venae cavae.

Methods

Fifteen normal fetuses (normal group) were matched for gestational age with 11 fetuses with absent diastolic flow in the umbilical artery (abnormal group). In the venae cavae, the following Doppler variables were measured and compared between groups: (a) during ventricular systole: maximum (Smax) and minimum velocities (Smin) and velocity integrals (SI); (b) during ventricular diastole: peak velocity of the E‐wave and its integral (EI), the A‐wave and its integral (AI). A venous velocity index (VVI) was defined as (Smax + Smin)/Smax.

Results

In the normal group, Smin and VVI were significantly higher in the inferior vena cava (IVC) than in the superior vena cava (SVC). The ratio SVC‐VVI/IVC‐VVI was therefore always less than one. In the abnormal group, Smin, SI, E, EI and VVI were higher in the SVC compared to those of the IVC. The ratio SVC‐VVI/IVC‐VVI was always greater than one.

Conclusion

In the absence of umbilical artery diastolic flow, a reciprocal shift is observed between the IVC and SVC velocity waveforms characterized by a flow profile in the IVC which resembles that of a normal SVC profile and vice versa. These changes are another manifestation of blood flow redistribution towards the brain in the presence of placental circulatory insufficiency. They should be taken into account on Doppler assessment of ventricular diastolic function based on venous flow patterns during placental circulatory impairment. Copyright © 2002 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal ultrasonographic diagnosis of atypical Nonne–Milroy lymphedema
Authors: Lev‐Sagie A. , Hamani Y. , Raas‐Rothschild A. , Yagel S. , Anteby E. Y.
Published: January 2003

Nonne–Milroy lymphedema is a relatively rare disorder characterized by firm edema of the lower extremities either on the whole leg or limited to the feet or toes. We report a case of atypical Nonne–Milroy syndrome that presented prenatally with bilateral leg edema, bilateral hydrothorax and lung hypoplasia at 22 weeks' gestation. The differential diagnoses are discussed. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Congenital chylothorax: a case report
Authors: Brito T. , Oliveira C. , Sousa L. , Barbosa A. , Pinho O. , Mesquita M. , Pinto R. , Inocêncio A. , Valente F.
Published: January 2003

A case of unilateral congenital hydrothorax diagnosed at 21 weeks and treated with a pleuro‐amniotic shunt at 23 weeks' gestation is presented. The rapid production of pleural fluid led to the development of polyhydramnios which was treated with a selective Cox inhibitor. Due to worsening of the hydrothorax, a third thoracocentesis was performed at 30 weeks' gestation prior to a Cesarean section. The neonate responded well to mechanical ventilation, a thoracic drainer that was inserted between days 5 and 14, fluid and protein replacement and gradual transition from parenteral to intestinal nutrition. Early diagnosis of chylothorax should be treated by thoraco‐amniotic drainage to prevent fetal pulmonary hypoplasia and congestive cardiac failure. Polyhydramnios is a complication of this therapy and may require treatment with a Cox inhibitor. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Nasal bone hypoplasia in trisomy 21 at 15–22 weeks' gestation
Authors: Cicero S. , Sonek J. D. , Mckenna D. S. , Croom C. S. , Johnson L. , Nicolaides K. H.
Published: January 2003

Objective

To investigate the potential value of ultrasound examination of the fetal profile for present/hypoplastic fetal nasal bone at 15–22 weeks' gestation as a marker for trisomy 21.

Methods

This was an observational ultrasound study in 1046 singleton pregnancies undergoing amniocentesis for fetal karyotyping at 15–22 (median, 17) weeks' gestation. Immediately before amniocentesis the fetal profile was examined to determine if the nasal bone was present or hypoplastic (absent or shorter than 2.5 mm). The incidence of nasal hypoplasia in the trisomy 21 and the chromosomally normal fetuses was determined and the likelihood ratio for trisomy 21 for nasal hypoplasia was calculated.

Results

All fetuses were successfully examined for the presence of the nasal bone. The nasal bone was hypoplastic in 21/34 (61.8%) fetuses with trisomy 21, in 12/982 (1.2%) chromosomally normal fetuses and in 1/30 (3.3%) fetuses with other chromosomal defects. In 3/21 (14.3%) trisomy 21 fetuses with nasal hypoplasia there were no other abnormal ultrasound findings. In the chromosomally normal group hypoplastic nasal bone was found in 0.5% of Caucasians and in 8.8% of Afro‐Caribbeans. The likelihood ratio for trisomy 21 for hypoplastic nasal bone was 50.5 (95% CI 27.1–92.7) and for present nasal bone it was 0.38 (95% CI 0.24–0.56).

Conclusion

Nasal bone hypoplasia at the 15–22‐week scan is associated with a high risk for trisomy 21 and it is a highly sensitive and specific marker for this chromosomal abnormality. Copyright © 2002 ISUOG. Published by John Wiley & Sons, Ltd.
Sonography of pregnancies with first‐trimester bleeding and a small intrauterine gestational sac without a demonstrable embryo
Authors: Falco P. , Zagonari S. , Gabrielli S. , Bevini M. , Pilu G. , Bovicelli L.
Published: January 2003

Objective

This was a prospective observational cohort study to evaluate the outcome and prognostic criteria of pregnancies with first‐trimester bleeding and a gestational sac ≤16 mm without a demonstrable embryo.

Methods

Criteria for admission into the study included: (1) first‐trimester bleeding; (2) a transvaginal scan performed upon admission demonstrating a single intrauterine gestational sac with a mean diameter ≤16 mm and without a demonstrable embryo. The outcome variable was miscarriage, defined as pregnancy loss prior to 22 weeks. The following explanatory variables were considered: maternal age, menstrual age, size of the gestational sac, presence or absence of the yolk sac and subchorionic hematoma, and β‐human chorionic gonadotropin levels. The relationship of these variables with pregnancy failure was analyzed by stepwise logistic regression.

Results

Of 50 patients, 32 (64%) underwent miscarriage. The receiver–operating characteristics (ROC) curve of the size of the gestational sac demonstrated a high level of statistical significance (area under the ROC curve 0.9080, P < 0.000001) and stepwise logistic regression revealed that this was the only variable independently correlated with the subsequent occurrence of miscarriage.

Discussion

It is commonly accepted that in pregnant patients with first‐trimester bleeding, demonstration by transvaginal ultrasound of an intrauterine gestational sac ≤16 mm without an embryo may be compatible with a viable pregnancy. Our results suggest that in general this finding is associated with a poor outcome, with miscarriage occurring in two‐thirds of patients. When the sac is small for gestational age, the risk of miscarriage is greatly increased. In the present series, a gestational sac diameter less than −1.34 standard deviations of the mean was associated with pregnancy failure in over 90% of cases. Copyright © 2002 ISUOG. Published by John Wiley & Sons, Ltd.
Treatment of severe fetal chylothorax associated with pronounced hydrops with intrapleural injection of OK‐432
Authors: Jorgensen C. , Brocks V. , Bang J. , Jorgensen F. S. , Rønsbro L.
Published: January 2003

We describe a case of a 25‐week fetus with severe bilateral pleural effusion, marked ascites, skin edema, an anterior thick (hydropic) placenta and polyhydramnios in which the most probable diagnosis was congenital chylothorax. Treatment with a pleuroamniotic shunt was planned, however the location of the fetus just below the anterior placenta made the placement of the shunt too dangerous. We therefore decided to use intrapleural injection of OK‐432. From week 29, the lungs looked normal, the pleural effusion had resolved and the thoracic circumference was within normal limits. The severe ascites persisted throughout the pregnancy and a total volume of 3680 mL was removed on several occasions. A Cesarean section was performed at 38 weeks and a normal male was delivered. Continuous positive airway pressure was needed on the first 4 days but after a week the situation was stable. On day 8, an X‐ray showed normally developed lungs. OK‐432 appears to have prevented pulmonary hypoplasia in our patient. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Audit of prenatal and postnatal diagnosis of isolated open spina bifida in three university hospitals in The Netherlands
Authors: Olde Scholtenhuis M. A. G. , Cohen‐Overbeek T. E. , Offringa M. , Barth P. G. , Stoutenbeek Ph. , Gooskens R. H. , Wladimiroff J. W. , Bilardo C. M.
Published: January 2003

Objective

To audit the current Dutch policy of prenatal detection of isolated open spina bifida based on offering detailed ultrasound examination only on indication.

Methods

A retrospective analysis of prenatally diagnosed isolated spina bifida cases and of newborns diagnosed with this condition was carried out in three university hospitals. The data were collected from databases and clinical records of the departments of prenatal diagnosis, obstetrics, neonatology, child neurology and neurosurgery of the three centers.

Results

Between January 1996 and December 1999, 88 cases of isolated open spina bifida were diagnosed prenatally by ultrasound investigation. Thirty‐eight cases (43%) were diagnosed before the 24th week of gestation. Of these, 35 (92%) ended in termination of the pregnancy at the parents' request. Of the remaining 50 cases (57%) diagnosed after the 24th week of gestation, eight (16%) pregnancies were terminated beyond the legal limit for termination due to the severity of the condition. Of the 88 cases of isolated spina bifida, 25 infants (28%) were still alive at the age of 4 years. In the same audit period 112 newborn infants with isolated open spina bifida were admitted to the neonatology, child neurology, or neurosurgery ward of the three centers. Of these cases, 47 (42%) had been diagnosed prenatally and 65 (58%) were an unexpected finding at birth. In 24 infants (21%) surgical treatment was withheld because of the severity of the condition and predicted poor outcome, whereas the remaining 88 infants (79%) underwent surgical repair.

Conclusion

The current practice in The Netherlands of offering ultrasound screening to high‐risk patients only leads to the early detection of a minority of cases of spina bifida. Most cases are diagnosed either after the 24th week of gestation or they remain undiagnosed until after birth. When spina bifida is diagnosed before the 24th week of gestation the vast majority of parents opt for termination. In order to reduce the birth prevalence of spina bifida in The Netherlands the introduction of a policy of routine ultrasound screening should be considered. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Echocardiographic evaluation of fetal hydrothorax: the effusion ratio as a diagnostic tool
Authors: Bigras J.‐L. , Ryan G. , Suda K. , Silva A. E. , Seaward P. G. R. , Windrim R. , McCrindle B. W.
Published: January 2003

Objective

Fetal hydrothorax may lead to hydrops and is associated with mortality as high as 50%. The objective of this study was to define the pathophysiology of fetal hydrothorax and its relation to hydrops.

Methods

Measurements from echocardiograms of 33 fetuses diagnosed with hydrothorax were made, and included diameters of the thorax, heart, inferior vena cava, right ventricle (RV), left ventricle (LV) and aortic and pulmonary valves. Doppler‐derived velocities were measured in the aorta and pulmonary artery just above the aortic and pulmonary valves. The ratio of the area of the effusion to the area of the thorax (effusion ratio) was calculated. Variables were converted into Z‐scores from regression equations based on normal data. Features of fetuses with and without hydrops were compared.

Results

Higher effusion ratios were noted in hydropic versus non‐hydropic fetuses. Compared to a normal population, study subjects had smaller dimensions of LV, RV and aortic and pulmonary valves. They also had higher pulmonary artery peak velocities. The comparison between non‐hydropic and hydropic fetuses revealed lower values for LV and pulmonary valve dimensions, and peak aortic velocity in hydropic fetuses. The severity of LV compression correlated significantly with effusion ratio.

Conclusion

Fetal hydrothorax is accompanied by compression of the cardiac structures, resulting in altered cardiac hemodynamics. Echocardiographic assessment, including the measurement of effusion ratio, may be a useful tool in guiding fetal therapy. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Three cross‐sectional planes for fetal color Doppler echocardiography
Authors: Chaoui R. , McEwing R.
Published: January 2003

Routine use of color Doppler during every fetal cardiac examination remains controversial. Many examiners still believe that color should be reserved for cases of suspected congenital heart defect (CHD). In our opinion, color Doppler should be applied in every cardiac scan due to the increase in speed and accuracy that it allows. The purpose of this review is to first explain how color Doppler presets can be optimized and, second, to propose the use of three cross‐sectional planes to simplify color Doppler fetal echocardiography: the four‐chamber (4CV), five‐chamber (5CV) and three‐vessel (3VV) views. A practical approach to the detection of CHD with these planes is presented, with typical findings and possible abnormalities evident during systole and diastole. The diastolic pattern on the 4CV is characterized by two equal color stripes. Connection (‘H’‐sign) or size inequality of the two stripes, or a unilateral color stripe, are important abnormal findings. In systole valve regurgitation should be excluded. In the 5CV, turbulent flow, ventricular septal defect or an overriding aorta (‘Y’‐sign) can be detected. In the 3VV the aorta and pulmonary trunk should be of nearly equal size and demonstrate antegrade flow. Abnormal findings encountered include absence of one vessel, discrepant size of the vessels, retrograde flow in one of the vessels, or the ‘U’‐sign, where the trachea is enclosed between both vessels, suggesting right‐sided aortic arch. In summary, we propose that color Doppler examination utilizing these three planes alone is sufficient to obtain adequate information for the detection of most common CHD. Copyright © 2002 ISUOG. Published by John Wiley & Sons, Ltd.
Outcome of children with prenatally diagnosed central nervous system malformations
Authors: Adama Van Scheltema P. N. , Nagel H. T. C. , Brouwer O. F. , Vandenbussche F. P. H. A.
Published: January 2003

Objective

To study the outcome of pregnancies with a prenatally diagnosed central nervous system (CNS) malformation.

Methods

Leiden University Medical Centre is a tertiary referral center for fetal ultrasound and invasive prenatal diagnosis. Maternal and neonatal records of prenatally diagnosed CNS malformations were retrospectively reviewed over a 6‐year period (1993–1998). Information on current development of surviving children was obtained by contacting the care‐giving pediatric neurologist.

Results

During the study period 124 fetuses were diagnosed with a CNS malformation. Data on pregnancy and delivery were available for 118 pregnancies. Additional malformations were present in 47% of fetuses (55/118). A total of 46% of pregnancies (54/118) were terminated, and 15% (18/118) ended in spontaneous intrauterine death. A total of 39% of pregnancies (46/118) resulted in live birth, and 29 of the infants were still alive at the age of 3 months. One child was lost to follow‐up, one infant died at the age of 4 months, and two children died at the age of 3 years. Psychomotor development of the remaining 25 children was normal for five, slightly disabled for seven, moderately disabled for five and severely disabled for eight.

Conclusion

Due to the high rate of termination of pregnancy and to the frequent association with other anomalies, the survival rate of pregnancies in which a CNS defect had been diagnosed prenatally was only 25%. More than 50% of surviving children were moderately or severely disabled. Copyright © 2002 ISUOG. Published by John Wiley & Sons, Ltd.
Factors influencing the prenatal detection of structural congenital heart diseases
Authors: Wong S. F. , Chan F. Y. , Cincotta R. B. , Lee‐Tannock A. , Ward C.
Published: January 2003

Objective

To assess the factors influencing the prenatal detection rate of structural congenital heart diseases (CHDs).

Methods

A retrospective study was conducted at a major obstetric hospital in Australia between 1 January 1996 and 30 June 1999. The medical records of all fetuses and infants born with CHD, except those with isolated patent ductus arteriosus or secundum atrial septal defect, were reviewed. Only pregnancies that had prenatal ultrasound scan assessments for morphological surveys were included. The following factors that may influence the detection rate were assessed: complexity of the lesions; experience of the sonographers (performance in tertiary versus non‐tertiary institutions); presence of other structural or chromosomal anomalies; and maternal body mass index (BMI).

Results

The incidence of structural CHD in this series, excluding cases referred from other hospitals, was 7.0 per 1000 (179/25 529). Of the 179 pregnancies with CHD, 151 had prenatal ultrasound scans and were included in the study. The overall detection rate for CHDs in this series was 40.4%. The detection rate for isolated septal defects was poor (13.7%). The detection rates were significantly higher for complex lesions (54%), for lesions with concomitant septal defects (66.7%), and for lesions with abnormal four‐chamber views (62.9%). The detection rate was also higher if the scan was performed in the tertiary institution, and if there were other chromosomal or structural anomalies. Maternal BMI did not affect the detection rate in the current series. Stepwise logistic regression analysis showed that three independent variables affecting the detection rate were complexity of the cardiac lesion, experience of the operator, and the detection of chromosomal anomalies.

Conclusion

A high detection rate for major CHDs can be achieved in a screening setting but there is still room for improvement in scanning skills in the four‐chamber view and great‐artery analysis in both tertiary and local centers. Copyright © 2002 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal tissue Doppler echocardiography: detection rates of cardiac structures and quantitative assessment of the fetal heart
Authors: Tutschek B. , Zimmermann T. , Buck T. , Bender H. G.
Published: January 2003

Objectives

Tissue Doppler echocardiography (TDE) has been developed in adult cardiology, but only recently has it been applied to fetal heart studies. We implemented TDE on a high‐resolution ultrasound system used for prenatal scanning by changing the Doppler settings, but without specific TDE equipment, to study cardiac tissue motion of normal fetuses in the second and third trimesters.

Methods

Using color Doppler settings optimized for low velocity motion assessment, detection rates of cardiac structures were measured in 47 fetuses. With pulsed Doppler, axial diastolic and systolic cardiac wall velocities were recorded in another 30 fetuses.

Results

In all fetuses TDE could detect cardiac wall motion. The right ventricular wall and the level of the atrioventricular valves were most easily seen. Axial contraction velocities of the fetal heart increased with gestational age.

Conclusions

TDE can be used to study normal fetal cardiac function throughout gestation. A regular ultrasound system without additional hardware or software is suitable for screening studies using TDE. Copyright © 2002 ISUOG. Published by John Wiley & Sons, Ltd.
Introduction: Moving youth participation forward
Authors: O'Donoghue Jennifer L. , Kirshner Benjamin , McLaughlin Milbrey
Published: January 2003

Given the emerging interest among researchers, practitioners, and policymakers in youth participation, it is important to examine and assess carefully the promise and challenges of youth engagement.
From assets to agents of change: Social justice, organizing, and youth development
Authors: Ginwright Shawn , James Taj
Published: January 2003

Young people are joining together to demand a voice in the decisions that affect their lives. In the process, they are transforming policies and making institutions more accountable.
Youth conferences as a context for engagement
Authors: Pancer S. Mark , Rose‐Krasnor Linda , Loiselle Lisa D.
Published: January 2003

Youth conferences can be effective means for engaging youth in the life of their schools, communities, and nation, bringing benefits not only to youth themselves but also to the community, which gains through the energy, ideas, and values that youth contribute.
Building young people's public lives: One foundation's strategy
Authors: Sherman Robert F.
Published: January 2003

Foundations are awakening to the untapped potential of serious, policy‐focused community change efforts led by teenagers and young adults. This chapter lays out background questions, a point of view, and programmatic strategies that one foundation developed for supporting young people who are taking direct action to improve their lives and communities.
Moving youth participation into the classroom: Students as allies
Authors: Cervone Barbara , Cushman Kathleen
Published: January 2003

The experiences of urban public high school students, told in their own words, offer new and veteran teachers guidance on how to reach adolescent learners and illustrate what youth‐adult partnerships in the classroom might look like.
Characterization of the X̃ 2A1 (0,0,0) ground vibronic state of CH2+ by pulsed-field-ionization zero-kinetic-energy photoelectron spectroscopy
Authors: Willitsch S. , Merkt F.
Published: January 2003

The rotational structure of the X̃ 2A1 (0,0,0) ground vibronic state of CH2+ has been observed by pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectroscopy. Rotational levels with asymmetric top rotational quantum numbers N+⩽5 and Ka+⩽2 have been used to derive a purely experimental r0 structure [rCH=(1.1049±0.0041) Å, αHCH=(139.77±0.27) degrees]. Whereas the positions of the Ka+=0 and 1 levels are in good agreement with previous results, the positions of the Ka+=2 levels, which are observed for the first time, suggest that the theoretical description of the bending potential and of the Renner–Teller effect in CH2+ could still be refined. The single photon photoionization dynamics of the CH2 X̃ 3B1 ground state is also consistent with a bent geometry for the ground state of CH2+. First PFI-ZEKE photoelectron spectra of CD2 are also presented.
Quantification of order in the Lennard-Jones system
Authors: Errington Jeffrey R. , Debenedetti Pablo G. , Torquato Salvatore
Published: January 2003

We conduct a numerical investigation of structural order in the shifted-force Lennard-Jones system by calculating metrics of translational and bond-orientational order along various paths in the phase diagram covering equilibrium solid, liquid, and vapor states. A series of nonequilibrium configurations generated through isochoric quenches, isothermal compressions, and energy minimizations are also considered. Simulation results are analyzed using an ordering map representation [Torquato et al., Phys. Rev. Lett. 84, 2064 (2000); Truskett et al., Phys. Rev. E 62, 993 (2000)] that assigns both equilibrium and nonequilibrium states coordinates in an order metric plane. Our results show that bond-orientational order and translational order are not independent for simple spherically symmetric systems at equilibrium. We also demonstrate quantitatively that the Lennard-Jones and hard sphere systems sample the same configuration space at supercritical densities. Finally, we relate the structural order found in fast-quenched and minimum-energy configurations (inherent structures).
Solute-structure dependence of solvation dynamics studied by reference interaction-site model theory
Authors: Nishiyama Katsura , Hirata Fumio , Okada Tadashi
Published: January 2003

A combination of the reference interaction-site model theory and site–site Smoluchowski–Vlasov equation is applied to estimate the dynamic response function of the average-energy relaxation of the solute–solvent system, SS(t). We calculate SS(t) for 13 model solutes with different structure, from a simple ion to an octopole, in a polar solvent. The partial charges of the ions and multipoles are changed to investigate nonlinear character of SS(t). The “nonlinear character” we study here corresponds to the response of the solvent fluctuation after the sudden change of the solute charge-distribution. Our present results reveal that SS(t) depends on the molecular structure and charge distribution of the solute. SS(t) is decomposed into two parts: one corresponding to the optical mode of solvent, the other to the acoustic mode. We show that for multipoles the optical mode is responsible for the fast part of SS(t), while the acoustic mode plays an important role in the slower dynamics. The dual nature of SS(t) is essential for the nonlinearity of solvation dynamics.