Critical Binder cumulant in two-dimensional anisotropic Ising models

The Binder cumulant at the phase transition of Ising models on square lattices with various ferromagnetic nearest and next-nearest neighbour couplings is determined using mainly Monte Carlo techniques. We discuss the possibility to relate the value of the critical cumulant in the isotropic, nearest neighbour and in the anisotropic cases to each other by means of a scale transformation in rectangular geometry, to pinpoint universal and nonuniversal features.Comment: 7 pages, 4 figures, submitted to J. Phys.

Critical Binder cumulant for isotropic Ising models on square and triangular lattices

Using Monte Carlo techniques, the critical Binder cumulant U* of isotropic nearest-neighbour Ising models on square and triangular lattices is studied. For rectangular shapes, employing periodic boundary conditions, U* is found to show the same dependence on the aspect ratio for both lattice types. Similarly, applying free boundary conditions for systems with square as well as circular shapes for both lattices, the simulational findings are also consistent with the suggestion that, for isotropic Ising models with short-range interactions, U* depends on the shape and the boundary condition, but not on the lattice structure.Comment: 7 pages, 4 figures, submitted to J. Stat. Mec

Performance of screening for aneuploidies by cell-free DNA analysis of maternal blood in twin pregnancies

Objectives To report clinical implementation of cell‐free DNA (cfDNA) analysis of maternal blood in screening for trisomies 21, 18 and 13 in twin pregnancies and examine variables that could influence the failure rate of the test. Methods cfDNA testing was performed in 515 twin pregnancies at 10–28 weeks' gestation. The failure rate of the test to provide results was compared with that in 1847 singleton pregnancies, and logistic regression analysis was used to determine which factors among maternal and pregnancy characteristics were significant predictors of test failure. Results Failure rate of the cfDNA test at first sampling was 1.7% in singletons and 5.6% in twins. Of those with a test result, the median fetal fraction in twins was 8.7% (range, 4.1–30.0%), which was lower than that in singletons (11.7% (range, 4.0–38.9%)). Multivariable regression analysis demonstrated that twin pregnancy, higher maternal weight and conception by in‐vitro fertilization provided significant independent prediction of test failure. Follow‐up was available in 351 (68.2%) of the twin pregnancies and comprised 334 with euploid fetuses, 12 discordant for trisomy 21 and five discordant for trisomy 18. In all 323 euploid cases with a result, the risk score for each trisomy was < 1:10 000. In 11 of the 12 cases with trisomy 21 and in the five with trisomy 18, the cfDNA test gave a high‐risk result, but in one case of trisomy 21, the score was < 1:10 000. Conclusion In twin pregnancies screening by cfDNA testing is feasible, but the failure rate is higher and detection rate may be lower than in singletons

Prediction of adverse perinatal outcome by cerebroplacental ratio in women undergoing induction of labor

Objective: To investigate the performance of screening for adverse perinatal outcome by the cerebroplacental ratio (CPR) measured within 24 hours of induction of labor. Methods: This was a prospective observational study in 1,902 singleton pregnancies undergoing induction of labor at ≥ 37 weeks’ gestation. Doppler ultrasound was used to measure the pulsatility index (PI) in the umbilical artery (UA) and fetal middle cerebral artery (MCA) before induction of labor. The measured UA PI and MCA PI and their ratio were converted to multiples of the median (MoM) after adjustment for gestational age. Univariate and multivariate logistic regression analysis was used to determine whether CPR improved the prediction of adverse perinatal outcome that was provided by maternal characteristics, medical history and obstetric factors. The detection rate (DR) and false-positive rate (FPR) of screening by CPR were estimated for cesarean section for presumed fetal distress and neonatal adverse outcome, which included umbilical arterial or venous cord blood pH ≤7 and ≤7.1, respectively, 5-minute Apgar score 24 hours, or hypoxic ischemic encephalopathy. Results: A combination of maternal and pregnancy characteristics, including age, weight, racial origin, previous obstetric history, preeclampsia, gestational age at delivery and amniotic fluid volume, identified 39% of pregnancies requiring cesarean section for fetal distress at FPR of 10%; addition of CPR did not improve the performance of screening. In screening for adverse neonatal outcome by a combination of parity and CPR the DR was 17% at FPR of 10%. Conclusion: Low CPR, measured within 24 hours of induction of labor, is associated with increased risk of cesarean section for fetal distress and adverse neonatal outcome, but the performance of CPR for such surrogates of adverse perinatal outcome is poor

Comparison of different methods of measuring angle of progression in prediction of labor outcome

Objective: First, to compare the manual sagittal and para-sagittal and automated para-sagittal methods of measuring the angle of progression (AOP) by transperineal ultrasound during labor, and second, to develop models for the prediction of time-to-delivery and need for cesarean section (CS) for failure to progress (FTP) in a population of patients undergoing induction of labor. Methods: This was a prospective observational study of transperineal ultrasound on a cohort of 512 women with singleton pregnancies undergiong induction of labor. A random selection of 50 stored images was assessed for inter- and intra-observer reliability between methods. In the cases of vaginal delivery univariate linear, multivariate linear and quantile regression were performed to predict time-to-delivery. Univariate and multivariate binomial logistic regression were performed to predict CS for FTP in the first stage of labor. Results: The intra correlation coefficients (ICC) for the manual para-sagittal method for a single observer was 0.97 (CI 0.95-0.98) and for two observers was 0.96 (CI 0.93-0.98) indicating good reliability. The ICC for the sagittal method for a single observer was 0.93 (0.88-0.96) and for two observers was 0.74 (0.58-0.84) indicating moderate reliabilty for a single observer and poor reliability between two observers. Bland-Altman analysis demonstrated narrower limits of agreement for the manual para-saggittal approach than for the sagittal approach for both single and two observers. The automated para-sagittal method failed to capture an image in 19% of cases. The mean difference between sagittal and para-sagittal methods was 110. In pregnancies resulting in vaginal delivery, 54% of the variation in time-to-delivery was explained in a model combining parity, epidural and syntocinon use during labour and the sonographic findings of fetal head position and AOP. In the prediction of CS for FTP in the first stage of labour a model which combined maternal factors with the sonographic measurements of AOP and estimated fetal weight was superior to one utilising maternal factors alone (area under the curve 0.80 vs 0.76). Conclusions: First, the method of measuring AOP with greatest reliability is the manual parasagittal technique and future research should focus on this technique, second, over half of the variation in time to vaginal delivery can be explained by a model that combines maternal factors, pregnancy characteristics and ultrasound findings, and third, the ability of AOP to provide clinically useful prediction CS for FTP in the first stage of labour is limited

Diagnosis of major heart defects by routine first-trimester ultrasound examination: association with high nuchal translucency, tricuspid regurgitation and abnormal flow in the ductus venosus

Objective: To examine the association between fetal major heart defects and high nuchal translucency thickness (NT), tricuspid regurgitation and abnormal flow in the ductus venosus in a large population of singleton pregnancies undergoing a routine ultrasound examination at 11-13 weeks’ gestation. Methods: This was a retrospective study of prospectively collected data from singleton pregnancies attending for a routine ultrasound scan at 11-13 weeks’ gestation which included examination of fetal anatomy, measurement of NT, and assessment of blood flow across the tricuspid valve and in the ductus venosus according to a standardized protocol. The incidence of fetal NT ≥95th and NT ≥99th percentile, tricuspid regurgitation and reversed a-wave in the ductus venosus in fetuses with and without major heart defects was determined and the performance of each marker and their combination in the detection of major heart defects was calculated. Results: The study population of 93,209 pregnancies with no apparent chromosomal abnormality included 211 (0.23%) with major heart defects and 92,998 morphologically normal neonates. In 113 (53.6%) of the major heart defects the diagnosis was made at the 11-13 weeks scan, in 82 (38.9%) at the 18-24 weeks scan, in 10 (4.7%) at the third-trimester scan and in 6 (2.8%) postnatally. At the 11-13 weeks scan we diagnosed all cases of tricuspid or pulmonary atresia and polyvalvular dysplasia, >90% of cases of hypoplastic left heart syndrome or atrioventricular septal defect, about 60% of complex heart defects and left atrial isomerism (interrupted inferior vena cava with normal intracardiac anatomy), 30-40% of tetralogy of Fallot and arch abnormalities, 25% of tricuspid valve abnormalities, about 15% of transposition of great arteries, but none of aortic or pulmonary stenosis and common arterial trunk. Fetal NT ≥95th percentile, NT ≥99th percentile, tricuspid regurgitation, or abnormal ductus venosus flow was observed in 77 (36.5%), 45 (21.3%), 61 (28.9%), and 58 (27.5%) of the fetuses with major heart defects, respectively, and in 5,678 (6.1%), 857 (0.9%), 1,136 (1.2%), and 1,644 (1.8%) of those without heart defects. Any one of NT ≥95th, tricuspid regurgitation or abnormal flow in the ductus venosus was found in 117 (55.5%, 95% CI 48.5–62.3%) of the fetuses with heart defects and in 8,166 (8.8%, 95% CI 8.6-9.0%) of those without heart defects. Any one of NT ≥99th percentile and the other two markers was found in 99 of the fetuses with heart defects (46.9%, 95% CI 40.0-53.9%) and in 3,517 of those without heart defects (3.8%, 95% CI 3.7-3.9%). Conclusion: At 11-13 weeks’ gestation measurement of fetal NT and assessment of flow across the tricuspid valve and in the ductus venosus can lead to the early diagnosis of major heart defects

Reference ranges for the size of the fetal cardiac outflow tracts from 13 to 36 weeks gestation: a single-center study of over 7000 cases

BACKGROUND: Assessment of the outflow tract views is an integral part of routine fetal cardiac scanning. For some congenital heart defects, notably coarctation of the aorta, pulmonary valve stenosis, and aortic valve stenosis, the size of vessels is important both for diagnosis and prognosis. Existing reference ranges of fetal outflow tracts are derived from a small number of cases. METHODS AND RESULTS: The study population comprised 7945 fetuses at 13 to 36 weeks’ gestation with no detectable abnormalities from pregnancies resulting in normal live births. Prospective measurements were taken of (1) the aortic and pulmonary valves in diastole at the largest diameter with the valve closed, (2) the distal transverse aortic arch on the 3 vessel and trachea view beyond the trachea at the distal point at its widest systolic diameter, and (3) the arterial duct on the 3 vessel and trachea view at its widest systolic diameter. Regression analysis, with polynomial terms to assess for linear and nonlinear contributors, was used to establish the relationship between each measurement and gestational age. The measurement for each cardiac diameter was expressed as a z score (difference between observed and expected value divided by the fitted SD corrected for gestational age) and percentile. Analysis included calculation of gestation-specific SDs. Regression equations are provided for the cardiac outflow tracts and for the distal transverse aortic arch:arterial duct ratio. CONCLUSIONS: The study established reference ranges for fetal outflow tract measurements at 13 to 36 weeks’ gestation that are useful in clinical practice

Tricyclo­[3.3.1.03,7]nonane-3,7-diyl bis­(methane­sulfonate)

The crystal structure of the title compound, C11H18O6S2, was determined to investigate the effect of the eclipsed mesyl groups on the bond length of the vicinal quaternary C atoms. The two quaternary C atoms of the noradamantane skeleton and the two O atoms to which they are connected all located essentially in the same plane [maximum deviation 0.01 Å], resulting in an eclipsing conformation of the C—O bonds. The C—C bond of the quaternary C atoms is 1.597 (3) Å is considerably longer than the other C—C bonds of the mol­ecule

Vacuum-Ultraviolet and Ultraviolet Fluorescence and Absorption Studies of Er(3+)-Doped Liluf4 Single-Crystals

Journal URL: http://apl.aip.org/apl/top.js

Cuentos y poemas griegos modernos para niños y gente joven

El Centro de Estudios Bizantinos y Neohelénicos, perteneciente a nuestra Facultad de Filosofía y Humanidades, ha venido realizando una plausible labor de traducción directa y edición de la literatura neogriega. Destacan en esta línea editorial los libros de grandes figuras de la poesía, y diversas antologías, como las de cuentistas contemporáneos y de mujeres. Cada obra es presentada con estudios preliminares y un interesante aparato crítico.