Showing papers by "The Chinese University of Hong Kong published in 1999"

Culture specific and cross-culturally generalizable implicit leadership theories: Are attributes of charismatic/transformational leadership universally endorsed?

Abstract: This study focuses on culturally endorsed implicit theories of leadership (CLTs). Although cross-cultural research emphasizes that different cultural groups likely have different conceptions of what leadership should entail, a controversial position is argued here: namely that attributes associated with charismatic/transformational leadership will be universally endorsed as contributing to outstanding leadership. This hypothesis was tested in 62 cultures as part of the Global Leadership and Organizational Behavior Effectiveness (GLOBE) Research Program. Universally endorsed leader attributes, as well as attributes that are universally seen as impediments to outstanding leadership and culturally contingent attributes are presented here. The results support the hypothesis that specific aspects of charismatic/transformational leadership are strongly and universally endorsed across cultures.

A meta-analysis of studies using bias and precision statistics to compare cardiac output measurement techniques.

Abstract: Introduction. Bias and precision statistics have succeeded regression analysis when measurement techniques are compared. However, when applied to cardiac output measurements, inconsistencies occur in reporting the results of this form of analysis. Methods. A MEDLINE search was performed, dating from 1986. Studies comparing techniques of cardiac output measurement using bias and precision statistics were surveyed. An error-gram was constructed from the percentage errors in the test and reference methods and was used to determine acceptable limits of agreement between methods. Results. Twenty-five articles were found. Presentation of statistical data varied greatly. Four different statistical parameters were used to describe the agreement between measurements. The overall limits of agreement in studies evaluating bioimpedance (n = 23) was ±37% (15–82%) and in those evaluating Doppler ultrasound (n = 11) ±65% (25–225%). Objective criteria used to assess outcome were given in only 44% of the articles. These were (i) limits of agreement approaching ±15–20%, (ii) limits of agreement of less than 1 L/min, and (iii) more than 75% of bias measurements within ±20% of the mean. Graphically, we showed that limits of agreement of up to ±30% were acceptable. Conclusions. When using bias and precision statistics, cardiac output, bias, limits of agreement, and percentage error should be presented. Using current reference methods, acceptance of a new technique should rely on limits of agreement of up to ±30%.

Efficient time series matching by wavelets

Abstract: Time series stored as feature vectors can be indexed by multidimensional index trees like R-Trees for fast retrieval. Due to the dimensionality curse problem, transformations are applied to time series to reduce the number of dimensions of the feature vectors. Different transformations like Discrete Fourier Transform (DFT) Discrete Wavelet Transform (DWT), Karhunen-Loeve (KL) transform or Singular Value Decomposition (SVD) can be applied. While the use of DFT and K-L transform or SVD have been studied on the literature, to our knowledge, there is no in-depth study on the application of DWT. In this paper we propose to use Haar Wavelet Transform for time series indexing. The major contributions are: (1) we show that Euclidean distance is preserved in the Haar transformed domain and no false dismissal will occur, (2) we show that Haar transform can outperform DFT through experiments, (3) a new similarity model is suggested to accommodate vertical shift of time series, and (4) a two-phase method is proposed for efficient n-nearest neighbor query in time series databases.

Rapid Clearance of Fetal DNA from Maternal Plasma

Abstract: Summary Fetal DNA has been detected in maternal plasma during pregnancy. We investigated the clearance of circulating fetal DNA after delivery, using quantitative PCR analysis of the sex-determining region Y gene as a marker for male fetuses. We analyzed plasma samples from 12 women 1–42 d after delivery of male babies and found that circulating fetal DNA was undetectable by day 1 after delivery. To obtain a higher time-resolution picture of fetal DNA clearance, we performed serial sampling of eight women, which indicated that most women (seven) had undetectable levels of circulating fetal DNA by 2 h postpartum. The mean half-life for circulating fetal DNA was 16.3 min (range 4–30 min). Plasma nucleases were found to account for only part of the clearance of plasma fetal DNA. The rapid turnover of circulating DNA suggests that plasma DNA analysis may be less susceptible to false-positive results, which result from carryover from previous pregnancies, than is the detection of fetal cells in maternal blood; also, rapid turnover may be useful for the monitoring of feto-maternal events with rapid dynamics. These results also may have implications for the study of other types of nonhost DNA in plasma, such as circulating tumor-derived and graft-derived DNA in oncology and transplant patients, respectively.

Worldwide variations in the prevalence of symptoms of atopic eczema in the International Study of Asthma and Allergies in Childhood.

Abstract: BACKGROUND: Little is known about the prevalence of atopic eczema outside Northern Europe. OBJECTIVES: We sought to describe the magnitude and variation in the prevalence of atopic eczema symptoms throughout the world. METHODS: A cross-sectional questionnaire survey was conducted on random samples of schoolchildren aged 6 to 7 years and 13 to 14 years from centers in 56 countries throughout the world. Those children with a positive response to being questioned about the presence of an itchy relapsing skin rash in the last 12 months that had affected their skin creases were considered to have atopic eczema. Children whose atopic eczema symptoms resulted in sleep disturbance for 1 or more nights per week were considered to have severe atopic eczema. RESULTS: Complete data was available for 256,410 children aged 6 to 7 years in 90 centers and 458,623 children aged 13 to 14 years in 153 centers. The prevalence range for symptoms of atopic eczema was from less than 2% in Iran to over 16% in Japan and Sweden in the 6 to 7 year age range and less than 1% in Albania to over 17% in Nigeria for the 13 to 14 year age range. Higher prevalences of atopic eczema symptoms were reported in Australasia and Northern Europe, and lower prevalences were reported in Eastern and Central Europe and Asia. Similar patterns were seen for symptoms of severe atopic eczema. CONCLUSIONS: Atopic eczema is a common health problem for children and adolescents throughout the world. Symptoms of atopic eczema exhibit wide variations in prevalence both within and between countries inhabited by similar ethnic groups, suggesting that environmental factors may be critical in determining disease expression. Studies that include objective skin examinations are required to confirm these findings.

Systems with finite communication bandwidth constraints. II. Stabilization with limited information feedback

Abstract: For part I, see ibid., vol.42, p.1294-8, 1997. In this paper a new class of feedback control problems is introduced. Unlike classical models, the systems considered here have communication channel constraints. As a result, the issue of coding and communication protocol becomes an integral part of the analysis. Since these systems cannot be asymptotically stabilized if the underlying dynamics are unstable, a weaker stability concept called containability is introduced. A key result connects containability with an inequality equation involving the communication data rate and the rate of change of the state.

Quantitative Analysis of Cell-free Epstein-Barr Virus DNA in Plasma of Patients with Nasopharyngeal Carcinoma

Abstract: Using real-time quantitative PCR, cell-free EBV DNA was detectable in the plasma of 96% (55 of 57) of nasopharyngeal carcinoma (NPC) patients (median concentration, 21058 copies/ml) and 7% (3 of 43) of controls (median concentration, 0 copies/ml) Advanced-stage NPC patients had higher plasma EBV DNA levels than those with early-stage disease At 1 month after completion of radiotherapy, plasma EBV DNA was undetectable in 7 of 15 subjects (47%) but remained high in the remaining 8 subjects (53%) Clinical examination revealed that all of the former seven subjects had complete tumor regression, whereas six of the eight latter subjects exhibited evidence of disease persistence or had developed distant metastases These results suggest that quantitative analysis of plasma EBV DNA may be a useful clinical and research tool in the screening and monitoring of NPC patients

Interim Report and Recommendations of the World Health Organization Task-Force for Osteoporosis

Abstract: Harry K. Genant (Chairman) , Cyrus Cooper (Rapporteur) , Gyula Poor (Rapporteur) , Ian Reid (Rapporteur) , George Ehrlich (Editor), J. Kanis (Editor), B. E. Christopher Nordin (Editor), Elizabet h Barrett-Connor , Dennis Black, J.-P. Bonjour, Bess Dawson-Hughes , Pierre D. Delmas, J. Dequeker , Sergio Ragi Eis, Carlo Gennari , Olaf Johnell , C. Conrad Johnston, Jr, Edith M. C. Lau, Uri A. Liberman, Robert Lindsay, Thomas John Martin, Basel Masri, Carlos A. Mautalen, Pierre J. Meunier, Paul D. Miller , Ambrish Mithal, Hirotoshi Morii , Socrates Papapoul os, Anthony Woolf, Wei Yu and Nikolai Khaltaev (WHO Secretariat) 30

Views from Inside and Outside: Integrating Emic and Etic Insights about Culture and Justice Judgment

Abstract: We analyze forms of synergy between emic and etic approaches to research on culture and cognition. Drawing on the justice judgment literature, we describe dynamics through which the two approaches stimulate each other's progress. Moreover, we delineate ways in which integrative emic/etic frameworks overcome limitations of narrower frameworks in modeling culture and cognition. Finally, we identify advantages of integrative frameworks in guiding responses to the diverse justice sensitivities in international organizations.

Statistical estimation in varying coefficient models

Abstract: Varying coefficient models are a useful extension of classical linear models. They arise naturally when one wishes to examine how regression coefficients change over different groups characterized by certain covariates such as age. The appeal of these models is that the coef .cient functions can easily be estimated via a simple local regression.This yields a simple one-step estimation procedure. We show that such a one-step method cannot be optimal when different coefficient functions admit different degrees of smoothness. This drawback can be repaired by using our proposed two-step estimation procedure.The asymptotic mean-squared error for the two-step procedure is obtained and is shown to achieve the optimal rate of convergence. A few simulation studies show that the gain by the two-step procedure can be quite substantial.The methodology is illustrated by an application to an environmental data set.

Entropy-based subspace clustering for mining numerical data

Abstract: Mining numerical data is a relatively difficult problem in data mining. Clustering is one of the techniques. We consider a database with numerical attributes, in which each transaction is viewed as a multi-dimensional vector. By studying the clusters formed by these vectors, we can discover certain behaviors hidden in the data. Traditional clustering algorithms find clusters in the full space of the data sets. This results in high dimensional clusters, which are poorly comprehensible to human. One important task in this setting is the ability to discover clusters embedded in the subspaces of a high-dimensional data set. This problem is known as subspace clustering. We follow the basic assumptions of previous work CLIQUE. It is found that the number of subspaces with clustering is very large, and a criterion called the coverage is proposed in CLIQUE for the pruning. In addition to coverage, we identify new useful criteria for this problem and propose an entropybased algorithm called ENCLUS to handle the criteria. Our major contributions are: (1) identify new meaningful criteria of high density and correlation of dimensions for goodness of clustering in subspaces, (2) introduce the use of entropy and provide evidence to support its use, (3) make use of two closure properties based on entropy to prune away uninteresting subspaces efficiently, (4) propose a mechanism to mine non-minimally correlated subspaces which are of interest because of strong clustering, (5) experiments are carried out to show the effectiveness of the proposed method.

Detection of Aberrant p16 Methylation in the Plasma and Serum of Liver Cancer Patients

Abstract: We have studied the feasibility of detecting tumor-associated aberrant p16 methylation in the circulation of patients with hepatocellular carcinoma (HCC). We extracted DNA from the tumor tissues and peripheral blood plasma or serum of 22 HCC patients. p16 methylation was found in 73% (16 of 22) of HCC tissues using methylation-specific PCR. Among the 16 cases with aberrant methylation in the tumor tissues, similar changes were also detected in the plasma/serum samples of 81% (13 of 16) of the cases. No methylated p16 sequences were detected in the peripheral plasma/serum of the six HCC cases without these changes in the tumor, in 38 patients with chronic hepatitis/cirrhosis, or in 10 healthy control subjects. These results suggest that circulating liver tumor DNA may be detected using tumor-associated DNA methylation changes. Because methylation abnormalities have been found in many other genes and tumor types, this approach may have implications for the noninvasive detection of a wide variety of cancers.

Quantitative Abnormalities of Fetal DNA in Maternal Serum in Preeclampsia

Abstract: Background: There is much recent interest in the biologic and diagnostic implication of cell-free non-host DNA in the plasma and serum of human subjects. To determine if quantitative abnormalities of circulating non-host DNA may be associated with certain pathologic processes, we used circulating fetal DNA in preeclampsia as a model system. Methods: We studied 20 preeclamptic women and 20 control subjects of comparable gestational age (means, 32 and 33 weeks, respectively). Male fetal DNA in maternal serum was measured using real-time quantitative PCR for the SRY gene on the Y chromosome. Results: The imprecision (CV) of the assay was 2.7%. The median circulating fetal DNA was increased fivefold in 20 preeclamptic women compared with 20 control pregnant women (381 vs 76 genome-equivalents/mL, P <0.001). Conclusions: These observations suggest that preeclampsia is associated with disturbances in the liberation and/or clearance mechanisms of circulating DNA. These results also raise the possibility that measurement of circulating DNA may prove useful as a marker for the diagnosis and/or monitoring of preeclampsia.

Reexamining the Theory of Planned Behavior in Understanding Wastepaper Recycling

Abstract: Using Ajzen’s theory of planned behavior (TOPB), this study examined wastepaper-recycling behavior among college students in Hong Kong. Two hundred and eighty-two college students completed a quest...

What You Don'T Know About Customer-Perceived Quality: the Role of Customer Expectation Distributions

Abstract: We show that some of the most common beliefs about customer-perceived quality are wrong For example, 1) it isnot necessary to exceed customer expectations to increase preference, 2) receiving an expected level of bad service does not reduce preference, 3) rational customers may rationally choose an option with lower expected quality, even if all nonquality attributes are equal, and 4) paying more attention to loyal, experienced customers can sometimes be counter-productive These surprising findings make sense in retrospect, once customer expectations are viewed as distributions, rather than simple point expectations That is, each customer has a probability density function that describes the relative likelihood that a particular quality outcome will be experienced Customers form these expectation distributions based on their cumulative experience with the good or service A customer's cumulative expectation distribution maybe conceptualized as being a predictive density for the next transaction When combined with a diminishing returns (ie, concave) utility function, this Bayesian theoretical framework results in predictions of: (a) how consumers will behave over time, and (b) how their perceptions and evaluations will change In managerial terms, we conclude that customers consider not only expected quality, but also risk This may help explain why current measures of customer satisfaction (which is highly related to expected quality) only partially predict future behavior We find that most of the predictions of our theoretical model are borne out by empirical evidence from two experiments Thus, we conclude that our approach provides a useful simplification of reality that successfully predicts many aspects of the dynamics of consumer response to quality These findings are relevant to both academics and managers Academics in the area of customer satisfaction and service quality need to be aware that it may be insufficient to measure only the point expectation, as has always been the standard practice Instead it may be necessary to measure the uncertainty that the customer has with respect to the level of service that will be received Due to questionnaire length constraints, it may not be practical for managers to include uncertainty questions on customer satisfaction surveys Nevertheless it is possible to build a proxy for uncertainty by measuring the extent of experience with the service/good, and this proxy can be used to partially control for uncertainty effects The findings of the study were obtained using 1) an analytical model of customer expectation updating, based on aset of assumptions that are well-supported in the academic literature, and 2) two behavioral experiments using human subjects: a cross-sectional experiment, and a longitudinal experiment Both the analytical model and the behavioral experiments were designed to investigate the effects that distributions of expectations might have, and especially the effects that might deviate from the predictions that would arise from a traditional point expectation model The behavioral experiments largely confirmed the predictions of the analytical model As it turned out, the analytical model correctly (in most cases) predicted behavioral effects that contradict some of the best-accepted "truisms" of customer satisfaction It is now clear that a more sophisticated view of customer expectations is required-one that considers not only the point expectation but also the likelihood across the entire distribution of possible outcomes This distinction is not "just academic," because it results in predictable behavior that deviates significantly from that which was traditionally expected based on simpler models

Endoscopic retreatment compared with surgery in patients with recurrent bleeding after initial endoscopic control of bleeding ulcers.

Abstract: Background and Methods After endoscopic treatment to control bleeding of peptic ulcers, bleeding recurs in 15 to 20 percent of patients. In a prospective, randomized study, we compared endoscopic retreatment with surgery after initial endoscopy. Over a 40-month period, 1169 of 3473 adults who were admitted to our hospital with bleeding peptic ulcers underwent endoscopy to reestablish hemostasis. Of 100 patients with recurrent bleeding, 7 patients with cancer and 1 patient with cardiac arrest were excluded from the study; 48 patients were randomly assigned to undergo immediate endoscopic retreatment and 44 were assigned to undergo surgery. The type of operation used was left to the surgeon. Bleeding was considered to have recurred in the event of any one of the following: vomiting of fresh blood, hypotension and melena, or a requirement for more than four units of blood in the 72-hour period after endoscopic treatment. Results Of the 48 patients who were assigned to endoscopic retreatment, 35 had long-term...

The Separation of Ownership and Control in East Asian Corporations

Abstract: We examine the separation of ownership and control for 2,980 corporations in nine East Asian countries. In all countries, voting rights frequently exceed cash-flow rights via pyramid structures and cross-holdings. The separation of ownership and control is most pronounced among family-controlled firms and small firms. More than two-thirds of firms are controlled by a single shareholder. Managers of closely held firms tend to be relatives of the controlling shareholder's family. Older firms are generally family-controlled, dispelling the notion that ownership becomes dispersed over time. Finally, significant corporate wealth in East Asia is concentrated among a few families.

Classification of solutions of higher order conformally invariant equations

Abstract: Recently, there have been much analytic work on the conformally invariant operators as well as its associated differential equations. A well known second order conformally invariant operator comes from the Yamabe problem or, more generally, the problem of prescribed scalar curvature. Given a smooth positive function K defined on a compact Riemannian manifold (M, g0) of dimension n ≥ 2, we ask whether there exists a metric g conformal to g0 such that K is the scalar curvature of the new metric g. Let g = eg0 for n = 2 or g = u 4 n−2 g0 for n ≥ 3, then the problem is reduced to find solutions of the following nonlinear elliptic equations:

Quantitative and Temporal Correlation between Circulating Cell-Free Epstein-Barr Virus DNA and Tumor Recurrence in Nasopharyngeal Carcinoma

Abstract: Recently, cell-free EBV DNA has been detected in the plasma and serum of patients with nasopharyngeal carcinoma (NPC) We studied the relationship between plasma/serum EBV DNA and tumor recurrence Using real-time quantitative PCR, the median plasma EBV DNA concentration in 10 patients with tumor recurrence was determined to be 32,350 copies/ml, whereas that in 15 patients in continuous remission for a mean period of 2 years was 0 copy/ml Longitudinal follow-up of 17 NPC patients revealed 6 individuals with tumor recurrence and 11 patients who remained in remission Significant elevations in serum EBV DNA, sometimes up to 6 months before detectable clinical deterioration, were observed in the patients who subsequently developed tumor recurrence Continuously low or undetectable levels of serum EBV DNA were observed in the patients who remained in remission These results suggest that plasma/serum cell-free EBV DNA may be a valuable tool for the monitoring of NPC patients for the early detection of tumor recurrence

Air pollution and hospital admissions for respiratory and cardiovascular diseases in Hong Kong.

Abstract: OBJECTIVE: To investigate short term effects of concentrations of pollutants in ambient air on hospital admissions for cardiovascular and respiratory diseases in Hong Kong. METHODS: Retrospective ecological study. A Poisson regression was performed of concentrations of daily air pollutant on daily counts of emergency hospital admissions in 12 major hospitals. The effects of time trend, season, and other cyclical factors, temperature, and humidity were accounted for. Autocorrelation and overdispersion were corrected. Daily concentrations of nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3), and particulate matter or = 65 years were at higher risk. Significant positive interactions were detected between NO2, O3, and PM10, and between O3 and winter months. CONCLUSIONS: Adverse health effects are evident at current ambient concentrations of air pollutants. Further reduction in air pollution is necessary to protect the health of the community, especially that of the high risk group.

Prediction of hypertension, diabetes, dyslipidaemia or albuminuria using simple anthropometric indexes in Hong Kong Chinese

Abstract: Prediction of hypertension, diabetes, dyslipidaemia or albuminuria using simple anthropometric indexes in Hong Kong Chinese

Nasopharyngeal carcinoma cell line (C666‐1) consistently harbouring Epstein‐Barr virus

Abstract: We have established a cell line (C666-1) from undifferentiated nasopharyngeal carcinoma (NPC). This cell line consistently carries the Epstein-Barr virus (EBV) in long-term cultures. C666-1 is a subclone of its parental cell line, C666, derived from an NPC xenograft of southern Chinese origin. It grows as an adherent culture and lacks contact inhibition. In addition, it is tumorigenic in athymic nude mice. The cells consistently express EBV-encoded RNAs and are positively stained for cytokeratin, an epithelial marker. In addition, they express EBNA1 protein, LMP1 and LMP2 transcripts and thus resemble the EBV latency II pattern. The virus genotype is EBV-1 with the latent membrane protein 1 gene showing a 30-bp deletion at the carboxyl terminus, both consistent with findings in southern Chinese NPC tumours. Cytogenetic analysis revealed a sub-diploid status with a chromosomal modal number of 45. C666-1 is unique among NPC cell lines in that it carries EBV. These cells may serve as a good investigative tool as the viral latency pattern and genotype are observed in the majority of primary NPC biopsies from Chinese patients.

Validation of the Chinese-Cantonese version of the hospital anxiety and depression scale and comparison with the Hamilton Rating Scale of Depression.

Abstract: Objective The aim of this study was to validate the Chinese-Cantonese version of the Hospital Anxiety and Depression Scale (HADS) and to compare it with the Hamilton Rating Scale of Depression (HRSD) as a screening tool for depressive disorders in general hospital in-patients. Method The Chinese-Cantonese version of the HADS was administered to general hospital in-patients seen on a consultation basis, and psychiatric diagnoses were made according to DSM-111-R. The subjects were further rated independently with the HRSD. Results The Chinese-Cantonese version of the HADS was found to have good internal consistency and external validity, with favourable sensitivity and specificity for screening for psychiatric disorders. However, its performance was marginally inferior to that of the HRSD. The scale also performed poorly in identifying major depression. Conclusion The HADS has limitations with regard to identification of depressive disorders. However, despite its shortcomings, it remains one of the best paper-and-pencil tests for screening psychiatric disorders in the medically ill.

Increased Fetal DNA Concentrations in the Plasma of Pregnant Women Carrying Fetuses with Trisomy 21

Abstract: Background: The recent discovery of the presence of circulating cell-free fetal DNA in maternal plasma opens up new prenatal diagnostic applications and provides new avenues for clinical investigation. It is of research and potential diagnostic interest to determine whether fetal trisomy 21 may be associated with quantitative abnormalities of circulating fetal DNA in maternal plasma. Methods: Maternal plasma samples were prospectively collected from two centers situated in Hong Kong and Boston. Samples collected from Boston consisted of 7 women carrying male trisomy 21 fetuses, 19 carrying euploid male fetuses, and 13 carrying female fetuses. Samples collected from Hong Kong consisted of 6 women carrying male trisomy 21 fetuses, 18 carrying euploid male fetuses, and 10 carrying female fetuses. Male fetal DNA in maternal plasma was measured using real-time quantitative Y-chromosomal PCR. Results: For patients recruited from Boston, the median circulating fetal DNA concentrations in women carrying trisomy 21 and euploid male fetuses were 46.0 genome-equivalents/mL and 23.3 genome-equivalents/mL, respectively ( P = 0.028). For patients recruited from Hong Kong, the median circulating fetal DNA concentrations in women carrying trisomy 21 and euploid male fetuses were 48.2 genome-equivalents/mL and 16.3 genome-equivalents/mL, respectively ( P = 0.026). None of the samples from women carrying female fetuses had detectable Y-chromosomal signals. Conclusions: Abnormally high concentrations of circulating fetal DNA are found in a proportion of women carrying fetuses with trisomy 21. The robustness and reproducibility of real-time PCR analysis of maternal plasma makes it a valuable tool for cross-institutional collaboration involving centers located in different parts of the world.

Building a culture of collaboration through hybrid language practices

Abstract: (1999). Building a culture of collaboration through hybrid language practices. Theory Into Practice: Vol. 38, Building Community Through Cooperative Learning, pp. 87-93.

Putting the "Noun Bias" in Context: A Comparison of English and Mandarin.

Abstract: Recently, researchers have been debating whether children exhibit a universal “noun bias” when learning a first language. The present study compares the proportions of nouns and verbs in the early vocabularies of 24 English- and 24 Mandarin-speaking toddlers ( M age 5 20 months) and their mothers. Three different methods were used to measure the proportion of noun types, relative to verb types: controlled observations in three contexts (book reading, mechanical toy play, regular toy play), identical across languages; a vocabulary checklist (MacArthur Communicative Development Inventory); and mothers’ reporting of their children’s “first words.” Across all measures, Mandarin-speaking children were found to have relatively fewer nouns and more verbs than English-speaking children. However, context itself played an important role in the proportions of nouns found in children’s vocabularies, such that, regardless of the language spoken, children’s vocabularies appeared dominated by nouns when they were engaged in book reading, but not when they were playing with toys. Mothers’ speech to children showed the same language differences (relatively more verbs in Mandarin), although both Mandarin- and English-speaking mothers produced relatively more verbs than their children. In sum, whether or not language-learning toddlers demonstrate a “noun bias” depends on a variety of factors, including the methods by which their vocabularies are sampled and the contexts in which observations occur.

Price discovery in the German equity index derivatives markets

Abstract: This article examines the intraday price discovery process among stock index, index futures, and index options in Germany using DAX index securities and intraday transactions data. The three index securities contribute to a common factor, but the spot index and index futures have substantially larger information shares than index options. Moreover, the returns of the three index securities exhibit feedback effects, with futures being dominant. Because the trading costs of the futures appear to be the lowest of the three and those of the options to be the highest, the results are consistent with the transaction cost hypothesis. © 1999 John Wiley & Sons, Inc. Jrl Fut Mark 19: 619–643, 1999