bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantifying and Addressing Parameter Indeterminacy in the Classical Twin Design
Authors: Keller Matthew C. , Coventry William L. 
Published: May 2007

AbstractTheclassical twin design(CTD) is the most common method used to infer genetic and environmental causes of phenotypic variation. As has long been acknowledged, different combinations of the common environment/assortative mating, and additive, dominant, and epistatic genetic effects can lead to the same observed covariation between twin pairs, meaning that there is an inherent indeterminacy in parameter estimates arising from the CTD. The CTD circumvents this indeterminacy by assuming that higher-order epistasis is negligible and that the effects of either dominant genetic variation or the common environment are nonexistent. These assumptions, however, lead to consistent biases in parameter estimation. The current paper quantifies these biases and discusses alternative strategies for dealing with parameter indeterminacy in twin designs. One strategy is to model the similarity among other relatives in addition to twins (extended twin-family designs), which reduces but does not eliminate indeterminacy in parameter estimates. A more general strategy, applicable to all twin designs, is to present the parameter indeterminacy explicitly, as in a graph. Presenting the space of mathematically equally likely parameter values is important, not only because it aids the proper interpretation of twin design findings, but also because it keeps behavioral geneticists themselves mindful of methodological assumptions that can easily go unexamined.
Twin and Genetic Effects on Life Events
Authors: Middeldorp Christel M. , Cath Danielle C. , Vink Jacqueline M. , Boomsma Dorret I. 
Published: May 2007

AbstractTwin studies that examine the effect of specific environmental risk factors on psychiatric disorders assume that there are no differences in prevalences of these risk factors between twins and singletons. Violation of this assumption signifies that the results from twin studies might not generalize to singletons. Another assumption, not only often underlying twin studies but also epidemiological research, is that life- events are not influenced by familial factors. We tested differences in prevalences of experienced life events in a Dutch sample of 2086 monozygotic (MZ) twins, 2090 dizygotic (DZ) twins and 1307 of their siblings. Self-reported data on life events (illness of self, illness of a significant other, spouse/romantic relationship, divorce/break-up of a relationship, death of a significant other, traffic accident, robbery, violent assault, sexual assault) were available from a survey- study. We further investigated whether familial resemblance was present for the exposure to these life events and, if so, whether this resemblance was due to genetic or common environmental factors. No differences were found in the prevalences of life events between MZ twins, DZ twins and their siblings. There was evidence for familial aggregation of all life events, except for traffic accidents in women. Results indicated genetic control on the presence of a spouse or involvement in a relationship. Familial resemblance of illness and death of a significant other was mainly due to common environment. For the other life events, it was not possible to distinguish between genetic and common environmental effects.
Co-Twin Dependence Modifies Heritability of Abstinence and Alcohol Use: A Population-Based Study of Finnish Twins
Authors: Penninkilampi-Kerola Varpu , Kaprio Jaakko , Moilanen Irma , Rose Richard J. 
Published: May 2007

AbstractThe role of co-twin dependence (twins' closeness or reliance on the co-twin) was examined as a moderator of genetic and environmental influences on alcohol use in adolescence and early adulthood in a large longitudinal population-based study of Finnish twins (FinnTwin16). The associations between co-twin dependence and alcohol use were studied first at an individual level in adolescence (n= 3362) and early adulthood (n= 2912). Then, maximum likelihood models were fit to the two waves of data from same-sex twin pairs to assess the differences and changes in genetic and environmental influences on alcohol use (abstinence, drinking frequency, intoxication frequency);N= 1342 pairs in adolescence, andN= 1078 pairs in early adulthood. Overall, no significant associations were found between co-twin dependence and individual alcohol use. However, co-twin dependence importantly modulated genetic effects on drinking habits, especially in adolescence, but also in early adulthood. Co-twin–dependent twins reported greater similarity in their alcohol-related behavior across all alcohol-use measures at both time points, and the role of genes and environments varied according to co-twin dependence. Shared environmental factors explained most of the variation in drinking among co- twin–dependent twins in adolescence and contributed to drinking to intoxication during early adulthood. In contrast, among co-twin–independent twin pairs, genetic variance contributed significantly to all alcohol-use measures at both time-points. An interdependent sibling relationship is an important modifier of drinking habits, and it appears to reduce the impact of inherited liabilities on alcohol-related behavior especially in adolescence.
Genetic Component of Noise Sensitivity
Authors: Heinonen-Guzejev Marja , Vuorinen Heikki S. , Mussalo-Rauhamaa Helena , Heikkilä Kauko , Koskenvuo Markku , Kaprio Jaakko 
Published: May 2007

AbstractWe investigated the genetic component of noise sensitivity using a twin-study design. The study sample consisted of 573 same-sexed twin pairs from the Finnish Twin Cohort. The 131 monozygotic (MZ) and 442 dizygotic (DZ) twin pairs with an age range of 31 to 88 years replied to a questionnaire on noise and health-related items in 1988. The noise sensitivity of respondents was defined as high, quite high, quite low or low. MZ pairs were more similar with regards noise sensitivity than DZ pairs, and quantitative genetic modeling indicated significant familiality. The best z-fitting genetic model provided an estimate of heritability of 36% (95% CI = .20–.50) and when hearing impaired subjects were excluded this rose to 40% (95% CI = .24–.54). In conclusion, noise sensitivity does aggregate in families and probably has a genetic component.
Short- and Long-Term Effects of Child Care on Problem Behaviors in a Dutch Sample of Twins
Authors: Van Beijsterveldt Toos C.E.M. , Hudziak James J. , Boomsma Dorret I. 
Published: May 2007

AbstractThis study examined the association between early child care on the development of behavior problems. At the age of 5 years, child care information was collected from parents on a large group of twins who were born between 1985 and 1997. Mothers and fathers rated the behavior of the child at ages 3, 7, and 10 years using the Child Behavior Checklist (CBCL) and teachers reported on the same children's behaviors using the Teacher's Report Form (TRF) at ages 7 and 10. At the age of 3 years, children with nonparental child care experiences had more externalizing problems than children with only parental child care. The long-term effects of quantity of child care were mixed and were only significant for mother ratings and for children from families with a low socioeconomic status. Overall, the effect sizes of child care were very small (effect sizes were between .12 and .23). Children with a larger amount of child care did not show more behavior problems, therefore it was questioned whether the increased levels of behavior problems could be attributed to quantity of child care.
A Retrospective Study of the Accuracy of Sonographic Chorionicity Determination in Twin Pregnancies
Authors: Menon Dev K. 
Published: May 2007

AbstractThe aim of this study was to determine the accuracy of sonographic chorionicity determination in the largest sample of twin pregnancies to date. We retrospectively analyzed 463 twin pregnancies delivered over a 6-year period to determine in each case what the antenatal sonographic prediction of chorionicity was, and then what the subsequent post partum pathological diagnosis of chorionicity was. Out of 436 twin pregnancies, 428 were correctly diagnosed for chorionicity as confirmed by pathology reports. Sonography as a screening tool for monochorionic twin pregnancies has a sensitivity of 100%, a specificity of 97.9% and a predictive value positive of 88.2%. Transvaginal scanning in the first trimester determined twin chorionicity with a sensitivity and a specificity of 100%. This study has confirmed in the largest sample to date that sono- graphic chorionicity determination is best done in the first trimester using vaginal scans, where it has 100% accuracy.
The Case of Monochorionic Twin Gestation Complicated by Intrauterine Demise of One Fetus in the First Trimester
Authors: Malinowski Witold , Koktysz Robert , Stawerski Pawel 
Published: May 2007

AbstractThe study investigated the clinical and pathomorpho- logical characteristics of monochorionic diamniotic twin gestations complicated by the spontaneous loss of one fetus during the first trimester. Nine monochorionic diamniotic twin gestations were analyzed in which the demise of one fetus occurred during the first trimester. During the course of the study, 178 twin gestations were sonographically identified during the first trimester. Forty-three (24.2%) were complicated by the intrauterine demise of one fetus before the end of the 12th week of pregnancy. Nine cases were monochorionic diamniotic. The gestational age of the demised fetuses ranged between 5 and 11 weeks (mean 7.4 weeks). The prognoses for the surviving fetuses were rather poor with the surviving co-twin dying 1 to 3 weeks after the first twin, with abortion of both fetuses. In only one case was gestation concluded on the 40th week with delivery of a live neonate. No blood coagulation changes were observed in the affected pregnant women, and the one live newborn did not reveal any haematological or neurological abnormalities. A postnatal study provided evidence for the history of monochorionic diamniotic placentation in all of the cases. In two cases, probable causes of fetal death were established (congenital malformation, the presence of anastomoses between blood vessels). The obtained results suggest an extremely high risk of mortality for the surviving twin fetus following the co-twin's death in cases of monochorial placentation. The morphological evaluation of placentas and fetal membranes enables the establishment of the type of placenta and, in certain cases, the probable cause of the intrauterine demise of one twin fetus during the first trimester of monochorionic diamniotic twin gestation.
The North American Industry Classification System and Its Implications for Accounting Research*
Authors: Krishnan Jayanthi , Press Eric 
Published: May 2007

AbstractIndustry classification is an important component of the methodological infrastructure of accounting research. Researchers have generally used the Standard Industrial Classification (SIC) system for assigning firms to industries. In 1999, the major statistical agencies of Canada, Mexico, and the United States began implementing the North American Industry Classification System (NAICS). The new scheme changes industry classification by introducing production as the basis for grouping firms, creating 358 new industries, extensively rearranging SIC categories, and establishing uniformity across all NAFTA nations.We examine the implications of the change for accounting research. We first assess NAICS's effectiveness in forming industry groups. Following Guenther and Rosman 1994, we use financial ratio variances to measure intra‐industry homogeneity and find that NAICS offers some improvement over the SIC system in defining manufacturing, transportation, and service industries.We also evaluate whether NAICS might have an impact on empirical research by reproducing part of Lang and Lundholm's 1996 study of information‐transfer and industry effects. Using SIC delineations, they focus on whether industry conditions or the level of competition is the main source of uncertainty resolved by earnings announcements. Across all levels of aggregation, we find inferences are similar using either SIC or NAICS. How‐ever, we also observe that the regression coefficients in Lang and Lundholm's model show smaller intra‐industry dispersion for NAICS, relative to SIC, definitions.Overall, the results suggest that NAICS definitions lead to more cohesive industries. Because of this, researchers may encounter some differences in using NAICS‐industry definitions, rather than SIC, but these will depend on research design and industry composition of the sample.
Synthesis, characterization and in vitro cytotoxicity of palladium(II) complexes with mixed ligands. X‐ray diffraction study of C31H36ClNPPdS2
Authors: Shaheen Farkhanda , Badshah Amin , Gielen Marcel , Gieck Christine , de Vos Dick 
Published: May 2007

AbstractPd(II) complexes with organophosphines and dithiocarbamates derivatives of α‐amino acids were synthesized by reacting N,N‐dicyclohexyldithiocarbamate (DCHDTC, compounds 1–3) and N‐methylcyclohexyldithiocarbamate (MCHDTC, compounds 4–6) with (R3P)2PdCl2 (R = Ph, o‐tolyl, Ph2Cl) in a 1:1 molar ratio. The complexes were characterized by elemental analyses, FT‐IR, multinuclear (1H, 13C and 31P) NMR and single X‐ray crystallography, showing that the dithiocarbamate acts as a bidentate ligand and binds to Pd(II) via two sulfur atoms, resulting in a square planar geometry around Pd(II). The cytotoxicity of compounds 2, 3 and 4 was determined in vitro against six human tumour cell lines, MCF7, EVSA‐T, WIDR, IGROV, M19 MEL, A498 and H226. Compounds 3 and 4 showed a moderate to low cytotoxicity, whereas compound 2 exhibited a very low cytotoxicity. The results of antifungal assays showed that compounds 1–6 possess antifungal activity against Fusarium moniliformes, Fusarium saolani, Mucor sp., Aspergillus niger and Aspergillus fumigatus. The anti‐inflammatory screening results of 1–6 are quite similar to those observed for the standard drug Declofenac at 10 mg kg−1, which inhibited the odema by 74% after 4 h. Copyright © 2007 John Wiley & Sons, Ltd.
A Markov Chain Model of Population Growth with an Application in Epidemiology
Authors: Lefevre C. 
Published: May 2007

AbstractThis paper is concerned with a class of population growth processes in discrete time; the simple epidemic process is considered as a specific example. A Markov chain model is constructed and standard Markov methods are used to study the main biological concepts. A simple and explicit formula is obtained for the transient distribution of the population size. Then, the cost of the process is defined and the joint probability generating function of its components is derived. Finally, the results are extended to the case where the inter‐transition periods are bounded i.i.d. random variables.
Robust Selection of the Most Discriminative Variables in the Dichotomous Problem with Application to Some Respiratory Disease Data
Authors: Krusińska Ewa , Liebhart Jerzy 
Published: May 2007

AbstractA robust method for selection of variables with the greatest discriminatory power is presented in the paper. The method deals with the two groups of data problem. An application of the method to some respiratory disease data and comparisons with classical procedures are given, also.
Adjusting for Multiplicity of Statistical Tests in the Analysis of Carcinogenicity Studies
Authors: Heyse J. F. , Rom D. 
Published: May 2007

AbstractBecause the evaluation of rodent carcinogenicity studies involves performing a statistical analysis at each tumor site encountered it is important to understand the extent to which this multiplicity affects the false positive rate. It is equally important to apply methods of accounting for this multiplicity in the analysis.In this paper we discuss one such method which involves calculating the overall significance level associated with P1, the most extreme isolated trend P‐value observed among the tumor sites encountered. The method constructs the distribution of trend scores simultaneously for each tumor site using a multiresponse randomization procedure. As such, it recognizes the discrete nature of the data and incorporates inherent dependencis that may exist between the tumor sites.For small studies it is possible to perform a complete rerandomization and compute an exact adjusted trend P‐value. However, for moderate or large studies the need exists for approximations based on efficient resampling plans. We report one such approximation proposed by Dr. John Tukey which involves correcting the exact Bonferroni upper bound. Also, we show that the independence assumption used in methods proposed by Mantel (1980) and Mantel et al. (1982) seems to be a reasonable approximation for the study discussed in the present report. This result needs to be supported further using additional studies.
Binary Data in Prerandomized Designs
Authors: Bernhard G. , Compagnone D. 
Published: May 2007

AbstractIn 1979 and 1981 Zelen introduced the so‐called prerandomized designs as an alternative to the completely randomized trial of therapies: The participants of the trial are first (pre‐) randomized to the treatment groups and asked afterwards for their consent. In the case of binary data, tests for selection and treatment effects in the simple and double prerandomized design are derived and then illustrated by a numerical example.
Application of the Biased Spring Balance Weighing Design Theory to Estimation of Differences of Line Effects for Legume Content
Authors: Ceranka B. , Katulska K. 
Published: May 2007

AbstractThe incidence matrix of a BIB design for v treatments has been used to construct a biased spring balance weighing design. Conditions under which an optimum biased spring balance weighing design exists are given. It is also shown how this theory may be utilized to obtain treatment and experiment designs to estimate differences in legume content between pair of lines in an experiment overseeded with grass species.
Complex Segregation Analysis on Multi‐Modal Distributions
Authors: Tai J. J. , Gross A. J. 
Published: May 2007

AbstractBy using sib‐pairs and parent‐pairs data, Tai and Gross (1988) proposed a method to test the existence of a 2‐allele major locus for a quantitative trait. This method is extended to include three alleles at a major locus in this paper. One may perform this extension in a feasible and practical manner. To show the advantage of this extension, a simulated data set of nuclear families from a 3‐allele ordered dominant (i.e., A > B, A > W and B > W in our notation) major locus model for a quantitative trait is analyzed by a 2‐allele codominant major locus mixed model and a 3‐allele ordered dominant major locus mixed model. The result shows that our method can distinguish between ambiguous trimodal distributions.
Analysis of Phenetic Relationships Among Populations of the Avian Genus Batis (Platysteirinae) by Means of Cluster Analysis and Multidimensional Scaling
Authors: Lawson Walter J. , Ogg Patti J. 
Published: May 2007

AbstractIn the course of a study of the evolution of a genus of African flycatchers, Batis, numerical techniques were employed to analyse the characters of the populations of the forest‐dwelling Batis and to throw some light on their relationships. The techniques reported upon in this paper are non‐metric multidimensional scaling (MDS) and the Unweighted Pair‐group Method using Arithmetic Averages (UPGMA). The results obtained from these numeric analyses closely parallel those using non‐quantitative methods.
A Nonparametric Test for Differences in the Dispersion of Dependent Samples
Authors: Boehnke K. 
Published: May 2007

AbstractA new statistic Δ to test the hypothesis of a difference in the dispersion of two dependent samples of ordinal data quality is proposed. It draws on the idea of rank assignment originally forwarded by Siegel and Tukey (1960). No exact probability levels can be given for this statistic for the time being, but it is shown that the statistic is linearly related to the so‐called Hotelling‐Pabst statistic D, and that one can use exact tables of the latter as a substitute in the statistical decision process with small samples. For larger samples, an approximation of Δ to the standard normal distribution is given. The problem of tied observations is not sufficiently solved yet. A conservative procedure of rank assignment is proposed as long as the exact distribution of Δ in the presence of ties is unknown.
Edge‐corrected Estimators for the Reduced Second Moment Measure of Point Processes
Authors: Doguwa Sani I. , Upton Graham J. G. 
Published: May 2007

AbstractA new edge‐corrected estimator is proposed for the second moment cumulative functionK(t)introduced by Ripley (1977,Journal of the Royal Statistical Society, Series B39, 172–212). This new estimator is compared by simulation methods with existing edge‐corrected estimators in the context of bothK(t)andL(t)functions which are used to study point patterns. The results of the simulation study suggests that the new estimator provides almost unbiased estimates ofK(t)andL(t)and has a smaller mean squared error than its predecessors.
Binary Responses and the Three‐period Cross‐over
Authors: Morrey G. H. 
Published: May 2007

AbstractProblems with carry‐over effects in the simple two‐period cross‐over have lead to interest in more complex cross‐over designs. A method for analysing the optimum two‐treatment three‐period design with binary response variables is given by making a simple extension to Gart's logistic model. The method gives independent tests for, and estimates of the difference in treatment and first‐order carry‐over effects. An example of the analysis is given, using the loglinear models facility in GLIM.
Asymptotic Efficiency of the Chi‐Square Test for Heterogeneity of Proportions in Some Sparse‐Data Cases
Authors: Anderson S. , Hauck W. W. 
Published: May 2007

AbstractWe consider the problem of testing for heterogeneity of K proportions when K is not small and the binomial sample sizes may not be large. We assume that the binomial proportions are normally distributed with variance σ2. The asymptotic relative efficiency (ARE) of the usual chi‐square test is found relative to the likelihood‐based tests for σ2=0. The chi‐square test is found to have ARE = 1 when the binomial sample sizes are all equal and high relative efficiency for other cases. The efficiency is low only in cases where there is insufficient data to use the chi‐square test.
Two Models for Interaction in a 3‐way Analysis of Variance With One Observation Per Cell
Authors: Onukogu Ike B. , Ama N. O. 
Published: May 2007

AbstractThe paper shows that three factor interaction can be represented by two different models in a 3‐way classification without replications. Each model is developed as a product of the three main effects plus the sum of the products of a main effect and a two‐factor interaction. A conditional F‐test for non‐additivity is derived from each model.A pseudo‐correlation exists between the models and as this correlation coefficient tends to unity the models are shown to converge. Extension of the procedure to four‐factor interaction and higher is indicated.
Improvement of Ratio‐Type Estimators
Authors: Tankou Victoire , Dharmadhikari Sudhakar 
Published: May 2007

AbstractThis paper proposes a method for using multi‐auxiliary information at both the design and the estimation stages of a sample survey. The proposed method is an extension of the classical multivariate method of Olkin (1958). The results of Agarwal and Kumar (1978) come out as a special case.