bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Data Assimilation Using an Ensemble Kalman Filter Approach with Initial Condition and Model Physics Uncertainties
Authors: Fujita Tadashi , Stensrud David J. , Dowell David C. 
Published: May 2007

Abstract
The assimilation of surface observations using an ensemble Kalman filter (EnKF) approach is evaluated for the potential to improve short-range forecasting. Two severe weather cases are examined, in which the assimilation is performed over a 6-h period using hourly surface observations followed by an 18-h simulation period. Ensembles are created in three different ways—by using different initial and boundary conditions, by using different model physical process schemes, and by using both different initial and boundary conditions and different model physical process schemes. The ensembles are compared in order to investigate the role of uncertainties in the initial and boundary conditions and physical process schemes in EnKF data assimilation. In the initial condition ensemble, spread is associated largely with the displacement of atmospheric baroclinic systems. In the physics ensemble, spread comes from the differences in model physics, which results in larger spread in temperature and dewpoint temperature than the initial condition ensemble, and smaller spread in the wind fields. The combined initial condition and physics ensemble has properties from both of the previous two ensembles. It provides the largest spread and produces the best simulation for most of the variables, in terms of the rms difference between the ensemble mean and observations. Perhaps most importantly, this combined ensemble provides very good guidance on the mesoscale features important to the severe weather events of the day.
Ring-closing Metathesis Approach to a 16-Membered Macrocycle of Kendomycin
Authors: Sengoku Tetsuya , Uemura Daisuke , Arimoto Hirokazu 
Published: May 2007

Abstract
An approach to the macrocyclic core of kendomycin is described in which the Nozaki–Hiyama–Kishi coupling and a ring-closing olefin metathesis are the key reactions.
Novel Mesoporous CaO–B2O3–SiO2 Glasses with In Vitro Bioactivity
Authors: Xiu Tongping , Liu Qian , Wang Jacheng 
Published: May 2007

Abstract
Wormhole-like-ordered mesoporous CaO–B2O3–SiO2 (MCBS) glasses, prepared by a combination of surfactant-templating, sol–gel method and evaporation-induced self-assembly (EISA) processes, show good in vitro bioactivity, demonstrated by final formation of plate-like-carbonated calcium-deficient hydroxyapatite (d-HAp) on the surface after soaking in simulated body fluid (SBF) for a short period of time.
Genetic and Environmental Influences on Self-Concept in Female Preadolescent Twins: Comparison of Minnesota and Seoul Data
Authors: Hur Yoon-Mi 
Published: May 2007

AbstractIt has been argued that culture significantly influences the developmental basis of self-concept. The goal of the present study is to compare the relative importance of genetic and environmental factors to explain individual differences in various dimensions of self-concept in female preadoles- cents of Minnesota in the United States and Seoul in South Korea. Two hundred and eighteen monozygotic (MZ) and 137 dizygotic (DZ) twin pairs from the Minnesota Twin Family Study (MTFS) and 74 MZ and 42 DZ twin pairs from the Seoul Twin Family Study (STFS) completed the 6 cluster scales of the Piers–Harris Children's Self-Concept Scale (P–H). The 6 cluster scales of the P-H include Popularity, Physical Appearance and Attributes, Behavior, Intellectual Competence and School Status, Anxiety, and Happiness and Satisfaction. Univariate model- fitting analyses were performed. In both samples, a model incorporating shared and nonshared environmental influences fitted the data best for Popularity, Anxiety, and Intellectual Competence and School Status, whereas a model including additive genetic and nonshared environmental factors provided the best fit for Physical Appearance and Attributes, and Behavior. The univariate model did not yield an adequate fit for Happiness and Satisfaction. For Physical Appearance and Attributes, and Intellectual Competence and School Status, estimates of additive genetic and environmental factors were significantly different between the MTFS and the STFS samples. For Popularity, Anxiety, and Behavior, however, the genetic and environmental estimates were comparable between the two samples.
Genetic and Environmental Etiology of Effortful Control
Authors: Yamagata Shinji , Takahashi Yusuke , Kijima Nobuhiko , Maekawa Hiroko , Ono Yutaka , Ando Juko 
Published: May 2007

AbstractWe examined whether effortful control (EC), a temperament proposed by Rothbart and Bates (1998), has genetically coherent structure. A self- report measure of EC was administered to 450 Japanese twins (151 males and 299 females, ages 17 to 32 years) including 152 monozygotic and 73 dizygotic pairs. Univariate genetic analysis revealed that AE model fit best for the total EC as well as its subscales. The heritability estimate for total EC was 49%, and the estimates for subscales ranged between 32% and 45%. Multivariate genetic analysis revealed that the subscales of EC were genetically correlated to a high degree and environmentally correlated to a moderate degree. These results suggest that EC has substantial genetic basis and genetically coherent structure, supporting the validity of the construct. The implications to molecular genetic study and study of psychopathology were discussed.
Genetic and Environmental Influences on Finger-Sucking and Nail-Biting in Japanese Twin Children
Authors: Ooki Syuichi 
Published: May 2007

AbstractThe purpose of this study was to clarify the genetic contribution to finger-sucking and nail- biting in childhood using the largest databases available on Japanese twins. The subjects were 1131 pairs of 12-year-old twin children, consisting of 1057 males and 1205 females. All data were gathered by maternal questionnaire, and responses to the questionnaire were checked in the medical interview. The prevalence of finger-sucking between 0 to 2 years was 40% in males and 43% in females (p= .0053). The prevalence of nail-biting up until the age of 12 years was 28% in males and 26% in females (nonsignificant). Concordance rates and polychoric correlations were all higher in monozygotic pairs than in dizygotic pairs, irrespective of the sex combination. Univariate and bivariate genetic analyses using structural equation modeling was performed. The results showed that the proportion of total phenotypic variance attributable to genetic influences was 66% in males and 50% in females for finger-sucking, and 50% in both males and females for nail-biting. A co-occurrence of finger-sucking and nail-biting was observed in 17.7% of males (tetrachoric correlation:r= .40) and 15.7% of females (r= .32), which was attributed partly to common genetic or environmental factors. The proportion of total shared variance explained by genetic factors was 67%.
Verification of Self-Report of Zygosity Determined via DNA Testing in a Subset of the NAS-NRC Twin Registry 40 Years Later
Authors: Reed Terry , Plassman Brenda L. , Tanner Caroline M. , Dick Danielle M. , Rinehart Shannon A. , Nichols William C. 
Published: May 2007

AbstractThe National Academy of Sciences — National Research Council (NAS-NRC) twin panel, created nearly 50 years ago, had twin zygosity determined primarily via a similarity questionnaire that has been estimated to correctly classify at least 95% of twins. In the course of a study on the genetics of healthy ageing in the NAS-NRC twins, DNA was collected for genome-wide scanning and zygosity confirmation was examined in 343 participating pairs. The sample was supplemented from two other studies using NAS-NRC twins where one or both co-twins were suspected to have Alzheimer disease or another dementia, or Parkinson's disease. Overall 578 twin pairs with DNA were analyzed. Zygosity assignment for 96.8% (519/536) was confirmed via questionnaire. Among 42 pairs whose questionnaire responses were inconclusive for assigning zygosity, 50% were found to be monozygous (MZ) and 50% were dizygous (DZ). There was some evidence for greater misclassification of presumed DZ pairs in the healthy ageing study where participation favored pairs who were similar in having a favorable health history and willingness to volunteer without any element of perceived risk for a specific disease influencing participation.
The Cognitive Cost of Being a Twin: Two Whole-Population Surveys
Authors: Deary Ian J. , Pattie Alison , Wilson Valerie , Whalley Lawrence J. 
Published: May 2007

AbstractDo twins have a lower mean IQ score than singletons? Previous studies have not examined whole populations and are likely to be biased. Twin data from two whole-population surveys of IQ at age 11 years were examined: the Scottish Mental Surveys of 1932 and 1947. Additional variables from childhood were examined as possible mediating effects. There were 1080 twins from the 1932 survey, and 949 from the 1947 survey. In both surveys twins scored lower on the Moray House Test of verbal reasoning, equivalent to a deficit of about 5 IQ points. In the Scottish Mental Survey of 1947 the whole-population group of twins was compared in detail with a representative population sample. The same mental ability difference of about 5 IQ points was found, and was not accounted for by father's occupation, overcrowding in the childhood home, childhood height, school attendance or the number of people in the family.
Effects of Twin Separation in Primary School
Authors: van Leeuwen Marieke , van den Berg Stéphanie M. , van Beijsterveldt Toos C. E. M. , Boomsma Dorret I. 
Published: May 2007

AbstractWe studied the short- and long-term effects of classroom separation in twins on behavior problems and academic performance. Short-term effects were studied at age 7 in twins separated at age 5 and long-term effects at age 12 in twins who had been separated or together most of the time at school. Behavior problems were rated by mothers (Child Behavior Checklist at ages 3, 7 and 12) and teachers (Teacher Report Form at ages 7 and 12). Academic achievement was measured at age 12 using a national academic achievement test (CITO). At age 7, twins from separated pairs had more internalizing and externalizing problems than non- separated twins, as rated by both mothers and teachers. Only for the maternal ratings of internalizing problems, however, could these effects be attributed to the separation itself and not to preexisting problems (at age 3) between separated and nonseparated twins. Long-term effects of separation were significant for maternal and teacher ratings of internalizing and externalizing problems, but these effects could be explained by preexisting differences between separated and nonseparated groups. There were no differences in academic achievement between the separated and nonsepa- rated group. These results suggest that the decision to separate twins when they go to school is based in part on the existing behavioral problems of the twins and that, in the long run, separation does not affect problem behavior or academic achievement. The findings were the same for monozygotic and dizygotic twins.
Fetal Growth Restriction and Schizophrenia: A Swedish Twin Study
Authors: Nilsson Emma , Stålberg Gabriella , Lichtenstein Paul , Cnattingius Sven , Olausson Petra Otterblad , Hultman Christina M. 
Published: May 2007

AbstractObstetric complications increase the risk of schizophrenia. However, it is not known whether there is a causal relation or whether the association is mediated by genetic and/or shared environmental effects. The aim of this study was to investigate the associations between birthweight, other birth characteristics, and schizophrenia. Twin pairs discordant for schizophrenia will also control for unmeasured genetic and shared environmental effects. Prospectively filed obstetric records were used for a cohort analysis of 11,360 same-sexed twins, and within–twin pair analyses were conducted on 90 twin pairs discordant for schizophrenia. The results from the cohort study showed that low birthweight (less than or equal to 1999 grams; odds ratio [OR] 1.67, 95% confidence interval [CI] 0.88–3.14 and 2000–2299 grams; OR 1.79, 95% CI 1.07–3.01) and small head circumference (less than or equal to 31.5 cm; OR 1.61, 95% CI 1.03–2.51) were associated with later development of schizophrenia. The associations remained in the within-pair analyses. The association between low birthweight and schizophrenia is partly a function of reduced fetal growth. Fetal growth restriction seems to be associated with risk of schizophrenia independently of familial factors.
Education Issues; Twin Study Summaries; Famous Twin Babies and Famous Twins
Authors: Segal Nancy L. 
Published: May 2007

AbstractTwo educational issues of special relevance to twins and their families are reviewed. The first concerns newly passed legislation in the state of Minnesota allowing multiple birth parents to decide if their children should be placed in the same or separate classrooms. The second concerns a professor's accusations of identical twins' academic misconduct, based upon the twins' similar test performance. Next, reviews of timely research in the areas of religiosity, disease, conjoined twinning and autism are presented. Finally, some recent events featuring well-known twins are presented.
The Heritability of Telomere Length Among the Elderly and Oldest-Old
Authors: Bischoff Claus , Graakjaer Jesper , Petersen Hans Christian , Hjelmborg Jacob v. B. , Vaupel James W. , Bohr Vilhelm , Koelvraa Steen , Christensen Kaare 
Published: May 2007

AbstractA tight link exists between telomere length and both population doublings of a cell culture and age of a given organism. The more population doublings of the cell culture or the higher the age of the organism, the shorter the telomeres. The proposed model for telomere shortening, called the end replication problem, explains why the telomere erodes at each cellular turnover. Telomere length is regulated by a number of associated proteins through a number of different signaling pathways. The determinants of telomere length were studied using whole blood samples from 287 twin pairs aged 73 to 95 years. Structural equation models revealed that a model including additive genetic effects and non- shared environment was the best fitting model and that telomere length was moderately heritable, with an estimate that was sensitive to the telomere length standardization procedure. Sex-specific analyses showed lower heritability in males, although not statistically significant, which is in line with our earlier finding of a sex difference in telomere dynamics among the elderly and oldest-old.
Subjective Wellbeing and Sleep Problems: A Bivariate Twin Study
Authors: Nes Ragnhild B. , Røysamb Espen , Reichborn-Kjennerud Ted , Tambs Kristian , Harris Jennifer R. 
Published: May 2007

AbstractThe relationship between subjective wellbeing (SWB) and self-reported sleep problems was investigated in a cohort of Norwegian twins aged 18 to 31 years. Questionnaire data from 8045 same- and opposite-sex twins were analyzed using structural equation modeling to explore the relative effects of genetic and environmental influences on phenotypic variance and covariance. Special attention was paid to sex-specific effects. The correlation between the phenotypes was estimated to be −.43. Univariate analyses indicated considerable genetic influences for both SWB and sleep problems, for male and female twins alike. The best fitting bivariate model specified additive genetic and individual environmental factors for both phenotypes, and nonadditive genetic effects for sleep problems, with no sex-specific effects. Genetic and environmental effects accounted for 60% and 40% of the phenotypic correlation, respectively. Additive genetic factors affecting the two phenotypes were correlated (−.85), suggesting that part of the genetic effects that positively influence SWB also protect against sleep problems. In conclusion, the results indicate considerable overlap in genetic etiology for SWB and sleep problems, for males and females alike.
Eating Disorders: From Twin Studies to Candidate Genes and Beyond
Authors: Slof-Op ‘t Landt Margarita C. T. , van Furth Eric F. , Meulenbelt Ingrid , Slagboom P. Eline , Bartels Meike , Boomsma Dorret I. , Bulik Cynthia M. 
Published: May 2007

AbstractSubstantial effort has been put into the exploration of the biological background of eating disorders, through family, twin and molecular genetic studies. Family studies have shown that anorexia (AN) and bulimia nervosa (BN) are strongly familial, and that familial etiologic factors appear to be shared by both disorders. Twin studies often focus on broader phenotypes or subthreshold eating disorders. These studies consistently yielded moderate to substantial heritabilities. In addition, there has been a proliferation of molecular genetic studies that focused on Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) AN and BN. Seven linkage regions have been identified in genome-wide screens. Many genetic association studies have been performed, but no consistent association between a candidate gene and AN or BN has been reported. Larger genetic association studies and collaborations are needed to examine the involvement of several candidate genes and biological pathways in eating disorders. In addition, twin studies should be designed to assist the molecular work by further exploring genetic determinants of endophenotypes, evaluating the magnitude of contribution to liability of measured genotypes as well as environmental risk factors related to eating disorders. In this manner twin and molecular studies can move the field forward in a mutually informative way.
Heritabilities of Lipids in Young European American and African American Twins
Authors: Iliadou Anastasia , Snieder Harold , Wang Xiaoling , Treiber Frank A. , Davis Catherine L. 
Published: May 2007

AbstractTwin studies of lipids have almost exclusively involved Caucasians. People of African descent are known to show a healthier lipid profile, but relatively little is known about ethnic differences in genetic and environmental influences on lipids. One hundred and six African American (AA) and 106 European American (EA) twins (30 singletons and 91 complete pairs: 49 monozygotic, 21 dizygotic and 21 opposite-sex) from the south-eastern United States were studied (mean age 17.9 ± 3.2 years; 79% fasting). Lipids were assayed with the Cholestech LDX system. Analyses were adjusted for fasting status. Generalized estimating equations were used to test for the effects of sex and ethnicity on means, controlling for the dependence within twin pairs. Structural equation modeling was used to estimate genetic and environmental effects on each lipid variable. Females showed higher high-density lipoprotein (HDL) values than males (p< .001) and AAs showed higher HDL values than EAs (p< .001). EA males had higher triglyceride values than other groups (p= .02). All parameter estimates could be set equal across sex. Parameter estimates for total cholesterol, triglycerides and HDL could be set equal across ethnicity. The best fitting model for low- density lipoprotein (LDL) showed higher heritability in AAs (.92) than EAs (.69). Heritabilities ranged from 69% to 92%, with remaining variation explained by nonshared environmental effects. Adjustment for body mass index had virtually no effect on the heritability estimates. In this first twin study on lipids to include AAs, no ethnic differences in heritability were found except for LDL, where AAs exhibited higher estimates.
Heritability and Stability of Resting Blood Pressure
Authors: Hottenga Jouke-Jan , Boomsma Dorret I. , Kupper Nina , Posthuma Danielle , Snieder Harold , Willemsen Gonneke , de Geus Eco J. C. 
Published: May 2007

AbstractWe examined the contribution of genetic and environmental influences to variation in resting systolic (SBP) and diastolic (DBP) blood pressure in participants from 4 twin studies carried out between 1986 and 2003. A total of 1577 subjects (682 males, 895 females) participated. There were 580 monozygotic twins, 664 dizygotic twins and 333 of their siblings. The 4 studies sampled subjects in different age groups (average age 17, 32, 37, 44 years), allowing for comparison of the relative contribution of genetic and environmental factors across the first part of the life span. Blood pressure was assessed under laboratory conditions in 3 studies and by ambulatory monitoring in 1 study. Univariate analyses of SBP and DBP showed significant heritability of blood pressure in all studies (SBP h2 48% to 60%, DBP h2 34% to 67%). Overall, there was little evidence for sex differences in blood pressure heritability, and no evidence for differences in heritability due to measurement strategy (laboratory vs. ambulatory). For 431 subjects there were data from 2 or more occasions that allowed us to assess the tracking of blood pressure over time and to estimate the genetic and environmental contributions to blood pressure tracking. Correlations over time across an average period of 7.1 years (tracking) were between .41 and .70. Multivariate genetic analyses showed that blood pressure tracking was entirely explained by the same genetic factors being expressed across time. It was concluded that whole genome scans for resting blood pressure can safely pool data from males and females, laboratory and ambulatory recordings, and different age cohorts.
Are Twins at Risk of Cancer: Results From the Swedish Family-Cancer Database
Authors: Hemminki Kari , Chen Bowang 
Published: May 2007

AbstractA few twin studies on cancer have addressed questions on the possible carcinogenic or protective effects of twining by comparing the occurrence of cancer in twins and singletons. The nationwide Swedish Family-Cancer Database of 10.2 million individuals and 69,654 0- to 70-year-old twin pairs were used to calculate standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for all main cancers compared to singletons. The overall risk of cancer in same- or different-sex twins was at the same level as the risk for singletons. Testicular cancer, particularly seminoma, was increased among same-sex twins (1.54) and all twins to an SIR of 1.38. Among other tumors, neurinomas and nonthyroid endocrine gland tumors were increased. Colorectal cancers and leukemia were decreased among all twins. Melanoma and squamous cell skin cancer were decreased in male same-sex twins. The data on this unselected population of twins suggest that twinning per se is not a risk factor of cancer. In utero hormonal exposures or postnatal growth stimulation may be related to the risk of testicular cancer and pituitary tumors. Protective effects against colorectal cancer may be related to a beneficial diet, and in melanoma and skin cancer, to socioeconomic factors. The study involved multiple comparisons, and internal consistency between the results was one of the main factors considered for their plausibility. The results should encourage others working on twin and singleton populations to examine the specific associations and emerging hypotheses.