bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theoretical study of hydrogen and deuterium bond in glutaric acid crystal dimer
Authors: Noureddine Issaoui , Houcine Ghalla , Brahim Oujia 
Published: April 2011

AbstractIn the spirit of the work of Blaise et al. [J Chem Phys, 2005, 122, 64306], we have extended their quantum theoretical approach by accounting for the intrinsic anharmonicity of the slow frequency mode, which is described by a Morse potential to reproduce the polarized infrared line shapes of glutaric acid dimer and its deuterium derivative at different temperatures. In this approach, the adiabatic approximation is performed for each separate H‐bond bridge of the dimer, and a strong nonadiabatic correction is introduced into the model via the resonant exchange between the fast mode excited states of the two moieties. Working within the strong anharmonic coupling theory, according to which the high‐frequency mode is anharmonically coupled to the H‐bond bridge, this approach incorporated the Davydov coupling between the excited states of the two moieties, the quantum direct and indirect dampings and the intrinsic anharmonicity of the H‐bond bridge. The spectral density was obtained within the linear response theory by Fourier transform of the damped autocorrelation functions. The numerical results show that the theoretical line shapes of the glutaric acid dimer are in fairly good agreement with the experimental ones. Using a minimum number of independent parameters, this theoretical approach fits correctly the experimental line shapes of the glutaric acid dimer. The effects of deuteration and temperature have been successfully reproduced by our calculations. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
Evaluation of DFT methods to study reactions of benzene with OH radical
Authors: Scheiner Steve 
Published: April 2011

AbstractSeveral density functional theory” (DFT) methods are applied to two different reaction channels involving OH• + C6H6, and the results compared with high‐level ab initio calculations. The OH• adds directly to one C atom in the first channel, first forming an encounter complex with the OH• poised above the aromatic plane. B3LYP, BH&HLYP, and MPW1K compute an accurate estimate of the overall exothermicity, whereas M05‐2X, PBE0, and PBEPBE overestimate this quantity to some degree. With the exceptions of PBEPBE and PBE0, the other methods produce an acceptable barrier to addition. All approaches except BH&HLYP correctly predict an exothermic H• abstraction, although PBEPBE is too exothermic. The BH&HLYP barrier to H• abstraction is too high while the MPW1K, PBE0, and B3LYP values are better, and M05‐2X the best. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Fault tolerant control using virtual actuators and set‐separation detection principles
Authors: Seron María M. , De Doná José A. , Richter Jan 
Published: April 2011

SUMMARYIn this paper we combine a set‐separation approach to fault detection and identification (FDI), recently proposed by the authors, with the virtual actuator approach to controller reconfiguration of Steffen and Lunze. The FDI approach is based on the separation of sets that characterize the system operation under different actuator fault situations that can occur in the plant. The derivation of these sets takes into account the closed‐loop system reconfigured by means of the virtual actuator under all considered actuator faults. Analytic conditions in terms of closed‐loop system parameters and bounds on external signals can be deduced from the required set separation which, in turn, guarantees closed‐loop stability, setpoint tracking, and optimal performance properties of the scheme under all considered fault situations. Thus, the main contribution of this paper is twofold. First, it provides an integrated strategy for fault tolerant control by adapting two existing techniques for FDI and for controller reconfiguration to work in combined form. Second, and more importantly, it endows the resulting combined scheme with guaranteed closed‐loop stability, setpoint tracking and optimal performance properties under actuator faults and in the presence of disturbances. Copyright © 2011 John Wiley & Sons, Ltd.
COMT Val158met genotype and striatal D2/3 receptor binding in adults with 22q11 deletion syndrome
Authors: Boot Erik , Booij Jan , Zinkstok Janneke R. , Baas Frank , Swillen Ann , Owen Michael J. , Murphy Declan G. , Murphy Kieran C. , Linszen Don H. , Van Amelsvoort Thérèse A. 
Published: April 2011

AbstractAlthough catechol‐O‐methyltransferase (COMT) activity evidently affects dopamine function in prefrontal cortex, the contribution is assumed less significant in striatum. We studied whether a functional polymorphism in the COMT gene (Val158Met) influences striatal D2/3R binding ratios (D2/3R BPND) in 15 adults with 22q11 deletion syndrome and hemizygous for this gene, using single photon emission computed tomography and the selective D2/3 radioligand [123I]IBZM. Met hemizygotes had significantly lower mean D2/3R BPND than Val hemizygotes. These preliminary data suggest that low COMT activity may affect dopamine levels in striatum in humans and this may have implications for understanding the contribution of COMT activity to psychiatric disorders. Synapse, 2011. © 2011 Wiley‐Liss, Inc.
Prediction of preterm birth using the cervical consistency index
Authors: Parra‐Saavedra M. , Gómez L. , Barrero A. , Parra G. , Vergara F. , Navarro E. 
Published: April 2011

AbstractObjectivesTo assess the diagnostic power of a new cervical consistency index (CCI) obtained using transvaginal sonography for the prediction of spontaneous preterm birth (PTB) and to establish reference ranges for this new variable.MethodsIncluded in this prospective cross‐sectional study were 1115 singleton pregnancies at 5–36 weeks of gestation. Anteroposterior cervical diameter was measured before (AP) and after (AP′) application of pressure on the cervix using the transvaginal probe. The index was calculated using the formula: CCI = ((AP′/AP) × 100). Cervical length was also measured. The outcomes evaluated were spontaneous PTB before 32, 34 and 37 weeks. Logistic regression and analysis of receiver–operating characteristics (ROC) curves were performed to evaluate the diagnostic power of CCI and cervical length (adjusted for gestational age). Intraclass correlation coefficients (ICCs) and Bland–Altman analysis were used to evaluate intra‐ and interobserver variability.ResultsIn the 1031 women with follow‐up, the rate of spontaneous PTB before 32 weeks was 0.87%, before 34 weeks was 2.13% and before 37 weeks was 7.76% (n = 80). There were 31 (3.01%) iatrogenic PTBs before 37 weeks. An inverse linear correlation between gestational age and CCI was observed, with regression equation: CCI (in %) = 89.8 − 1.35× (GA in weeks); r2 = 0.66, P < 0.001. Cervical length showed an inverse quadratic, though non‐significant, relationship with gestational age: CL (in mm) = 31.084 − 0.0278× (GA in weeks)2 + 1.0772× (GA in weeks); r2 = 0.076, P < 0.14. The intra‐ and interobserver ICCs for CCI were 0.99 (95% CI, 0.988–0.994) and 0.98 (95% CI, 0.973–0.987), respectively. The area under the ROC curve for CCI in the prediction of spontaneous PTB before 32 weeks was 0.947, for spontaneous PTB before 34 weeks it was 0.943 and for spontaneous PTB before 37 weeks it was 0.907. For a 5% screen‐positive rate, CCI had a sensitivity of 67%, 64% and 45% for prediction of spontaneous PTB before 32, 34 and 37 weeks, respectively, with equivalent values of 11%, 9% and 11% for cervical length.ConclusionsCCI shows a clear inverse linear relationship with GA. Assessment of CCI is reproducible and is effective in the prediction of spontaneous PTB. This new variable appears to provide better prediction of spontaneous PTB than does cervical length. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
GI‐RADS reporting system for ultrasound evaluation of adnexal masses in clinical practice: a prospective multicenter study
Authors: Amor F. , Alcázar J. L. , Vaccaro H. , León M. , Iturra A. 
Published: April 2011

AbstractObjectiveTo assess the clinical usefulness of a structured reporting system based on ultrasound findings for management of adnexal masses.MethodsThis was a prospective multicenter study comprising 432 adnexal masses in 372 women (mean age, 44.0 (range, 13–78) years) over a 36‐month period. Ninety‐three (25%) women were postmenopausal and 279 (75%) women were premenopausal. Patients were evaluated with transvaginal ultrasound by one of three examiners expert in gynecological ultrasound. Reporting was provided to referring clinicians according to the Gynecologic Imaging Report and Data System (GI‐RADS) classification. A predetermined management protocol was offered to referral clinicians. It was suggested that patients classified as GI‐RADS 2 be managed with follow‐up scan, patients classified as GI‐RADS 3 undergo laparoscopic surgery and patients classified as GI‐RADS 4 or 5 be referred to a gynecologic oncologist. Definitive histologic diagnosis was available in 370 cases and 62 additional cases were considered as benign because of spontaneous resolution during follow‐up. These outcomes were used as the gold standard for calculating the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+) and negative likelihood ratio (LR−) of GI‐RADS classification for identifying adnexal masses at high risk of malignancy, considering GI‐RADS 4 and 5 as being malignant.ResultsOf the 432 tumors, 112 were malignant and 320 benign. The GI‐RADS classification rate was as follows: GI‐RADS 2, 92 (21%) cases; GI‐RADS 3, 184 (43%) cases; GI‐RADS 4, 40 (9%) cases; GI‐RADS 5, (27%) 116 cases. Sensitivity for this system was 99.1% (95% CI, 95.1–99.8%), specificity was 85.9% (95% CI, 81.7–89.3%), LR+ was 7.05 (95% CI, 5.37–9.45) and LR− was 0.01 (95% CI, 0.001–0.07). PPV and NPV were 71.1% and 99.6%, respectively.ConclusionsThe GI‐RADS reporting system performed well in identifying adnexal masses at high risk of malignancy and seems to be useful for clinical decision‐making. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Cervical length measurement for the prediction of preterm birth in multiple pregnancies: a systematic review and bivariate meta‐analysis
Authors: Lim A. C. , Hegeman M. A. , Huis In ‘T Veld M. A. , Opmeer B. C. , Bruinse H. W. , Mol B. W. J. 
Published: April 2011

AbstractObjectivesTo review the literature on cervical length as a predictor of preterm birth in asymptomatic women with a multiple pregnancy.MethodsWe searched MEDLINE, Embase and reference lists of included articles to identify all studies that reported on the accuracy of cervical length for predicting preterm birth in asymptomatic women with a multiple pregnancy. We scored study characteristics and study quality, and extracted data in order to construct two‐by‐two tables cross‐classifying cervical length and preterm delivery. Meta‐analysis using a bivariate model was performed. Summary receiver–operating characteristics (ROC) curves were generated for various test characteristics and outcome definitions.ResultsWe found 21 studies reporting on 2757 women. There was a large variation in gestational age at measurement, cut‐off point for cervical length and definition of preterm birth. The summary ROC curve indicated a good predictive capacity of short cervical length for preterm birth. Summary estimates of sensitivity and specificity for preterm birth before 34 weeks’ gestation were 78% and 66%, respectively, for 35 mm, 41% and 87% for 30 mm, 36% and 94% for 25 mm and 30% and 94% for 20 mm.ConclusionsIn women with a multiple pregnancy, second‐trimester cervical length is a strong predictor of preterm birth. In the absence of effective preventive strategies, there is currently no place in clinical practice for cervical length measurement in this population. However, future studies should evaluate preventive interventions in women with multiple pregnancies and a short cervix, and cervical length should be measured in any trial studying preventive strategies in multiple pregnancies. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome
Authors: Blaas H. G. K. , Salvesen K. Å. , Khnykin D. , Jahnsen F. L. , Eik‐Nes S. H. 
Published: April 2011

AbstractAll cases of ichthyosis prematurity syndrome (IPS), registered at the National Center for Fetal Medicine in Trondheim, Norway between 1987 and 2010 were identified and the findings analyzed. Five fetuses with IPS were identified between 1988 and 2000. All five developed polyhydramnios between 28 and 31 weeks. The fetal stomach appeared to be empty in four cases, and was not described in one case. The fetal skin was described as ‘uneven’ at ultrasound examination in two cases. Separation of chorionic and amniotic membranes with a peculiar appearance of echo‐free fluid in the chorionic cavity and echogenic sediment in the amniotic cavity were observed between 28 + 5 and 32 + 3 weeks in all cases. All fetuses were delivered prematurely between 30 and 34 weeks. All neonates had difficulties in breathing, two developed aspiration pneumonia, and one had bilateral pneumothorax after intubation and died at 6 months because of pulmonary and cardiac sequelae. Prenatal sonographic signs of IPS are separation of the membranes, echogenic amniotic fluid and echo‐free chorionic fluid occurring between 28 and 32 weeks' gestation. Delivery occurs at 30–34 weeks and, as there is a high risk of asphyxia, an experienced neonatal intensive care unit team should be present at delivery. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Use of a high‐frequency linear transducer and MTI filtered color flow mapping in the assessment of fetal heart anatomy at the routine 11 to 13 + 6‐week scan: a randomized trial
Authors: Votino C. , Kacem Y. , Dobrescu O. , Dessy H. , Cos T. , Foulon W. , Jani J. 
Published: April 2011

AbstractObjectiveTo prospectively assess the contribution of a high‐frequency linear transducer and of moving target indicator (MTI) filtered color flow mapping in the visualization of cardiac fetal anatomy at the routine 11 to 13 + 6‐week scan.MethodsThis was a cross‐sectional prospective study, including 300 singleton fetuses at 11 to 13 + 6 weeks' gestation. Patients were randomized into four groups and a detailed fetal cardiac examination was conducted transabdominally using either a conventional curvilinear transducer, a conventional curvilinear transducer and MTI filtered color flow mapping, a high‐frequency linear transducer or a high‐frequency linear transducer and MTI filtered color flow mapping. Regression analysis was used to investigate the effect on the ability to visualize different cardiac structures of the following parameters: gestational age at ultrasound examination; fetal crown–rump length (CRL); maternal body mass index (BMI); transducer–heart distance; the technique used at ultrasound; and the position of the placenta.ResultsThe four‐chamber view was visualized in 89.0% of fetuses and regression analysis showed this rate was correlated with CRL and the use of MTI filtered color flow mapping during ultrasonography, and inversely correlated with BMI and transducer–heart distance. Use of a conventional curvilinear transducer and MTI filtered color flow mapping allowed visualization of the four‐chamber view in 97.3% of fetuses, while this was only possible in 84.0% of fetuses using a high‐frequency linear transducer. The left and right outflow tracts were visualized in 62.3 and 57.7% of fetuses, respectively. Regression analysis showed that the ability to visualize the left or the right outflow tract was correlated with the use of MTI filtered color flow mapping during scanning and was inversely correlated with transducer–heart distance. The use of a conventional curvilinear transducer and MTI filtered color flow mapping allowed visualization of the left and right outflow tracts in 96.0 and 97.3% of fetuses, respectively, while this was only possible in 37.3 and 26.7% of fetuses using a high‐frequency linear transducer.ConclusionsDuring the routine 11 to 13 + 6‐week scan, the use of MTI filtered color flow mapping but not of a high‐frequency linear transducer, improves visualization of cardiac anatomy. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
A standardized measurement technique may improve the reliability of measurements of endometrial thickness and volume
Authors: Martins W. P. , Raine‐Fenning N. J. , Leite S. P. , Ferriani R. A. , Nastri C. O. 
Published: April 2011

AbstractObjectiveTo investigate whether standardization of the multiplanar view (SMV) when evaluating the uterus using three‐dimensional ultrasonography (3D‐US) improves intra‐ and interobserver reliability and agreement with regard to endometrial measurement.MethodsTwo‐dimensional (2D) and 3D‐US was used to measure endometrial thickness by two observers in 30 women undergoing assisted reproduction treatment. Endometrial volume was measured with Virtual Organ Computer‐aided AnaLysis (VOCAL™) in the longitudinal (A) and coronal (C) planes using an unmodified multiplanar view (UMV) and a standardized multiplanar view (SMV). Measurement reliability was evaluated by intraclass correlation coefficient (ICC) and agreement was examined using Bland–Altman plots with limits of agreement (LoA). The ease of outlining the endometrial–myometrial interface was compared between the A‐ and C‐planes using subjective assessment.ResultsEndometrial volume measurements using the SMV and A‐plane were more reliable (intra‐ and interobserver ICCs, 0.979 and 0.975, respectively) than were measurements of endometrial thickness using 2D‐US (intra‐ and interobserver ICCs, 0.742 and 0.702, respectively) or 3D‐US (intra‐ and interobserver ICCs, 0.890 and 0.784, respectively). The LoAs were narrower for SMV than for UMV. Reliability and agreement were not much different between the A‐ and C‐planes. However the observers agreed that delineating the endometrial–myometrial interface using the A‐plane was easier (first and second observer, 50.0 and 46.7%, respectively) or ‘comparable’ (50 and 53.3%, respectively), but never more difficult than using the C‐plane.ConclusionsEndometrial volume measurements are more reliable than endometrial thickness measurements and are best performed using SMV and the A‐plane. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Gaussian elimination
Authors: Higham Nicholas J. 
Published: April 2011

AbstractAs the standard method for solving systems of linear equations, Gaussian elimination (GE) is one of the most important and ubiquitous numerical algorithms. However, its successful use relies on understanding its numerical stability properties and how to organize its computations for efficient execution on modern computers. We give an overview of GE, ranging from theory to computation. We explain why GE computes an LU factorization and the various benefits of this matrix factorization viewpoint. Pivoting strategies for ensuring numerical stability are described. Special properties of GE for certain classes of structured matrices are summarized. How to implement GE in a way that efficiently exploits the hierarchical memories of modern computers is discussed. We also describe block LU factorization, corresponding to the use of pivot blocks instead of pivot elements, and explain how iterative refinement can be used to improve a solution computed by GE. Other topics are GE for sparse matrices and the role GE plays in the TOP500 ranking of the world's fastest computers. WIREs Comp Stat 2011 3 230–238 DOI: 10.1002/wics.164This article is categorized under:

Applications of Computational Statistics > Computational Mathematics
Algorithms and Computational Methods > Numerical Finite Arithmetic
Algorithms and Computational Methods > Numerical Methods
Synthesis, Crystal Structure, and Ru/Ir Site Preference in the Complex Boride Series Ti2FeRu5–xIrxB2 and Zr2Fe1–δRu5–x+δIrxB2 (x = 1–4, δ < 0.15)
Authors: Hermus Martin , Fokwa Boniface P. T. 
Published: April 2011

AbstractPolycrystalline samples and single crystals of the complex boride series Ti2FeRu5–xIrxB2 and Zr2Fe1–δRu5–x+δIrxB2 (x = 1–4, δ < 0.15) were synthesized by arc melting the elements and characterized by powder and single‐crystal X‐ray diffraction as well as energy dispersive spectroscopy. All quinary phases could be synthesized in the titanium series, whereas only the first two ruthenium‐rich phases are stable and both are always present in nearly all synthetic targets of the zirconium series. These compounds crystallize in the tetragonal space group P4/mbm (Z = 2) and they represent the first quinary substitutional variants of the Ti3Co5B2‐type structure containing a mixture of 4d/5d transition metals. Their structures consist of layers of ruthenium and iridium atoms, building trigonal, tetragonal, and pentagonal prisms, in which the other elements are located. The trigonal prisms are filled with boron and the pentagonal prisms accommodate either titanium or zirconium. The tetragonal prisms are filled either with iron (in the Ti series) or with an iron‐rich Fe/Ru mixture (in the Zr series). Ruthenium and iridium share two sites in these structures leading to a strong size‐dependent site preference in both series.
The Non‐Centrosymmetric Crystal Structure of Molybdenum(VI) Oxide Bromide MoO2Br2
Authors: Schustereit Tanja , Schleid Thomas , Hartenbach Ingo 
Published: April 2011

AbstractRed, transparent single crystals of molybdenum(VI) dioxide dibromide MoO2Br2 emerged as by‐product after thermal analyses of reaction mixtures comprising REBr3 (RE = La or Gd) and MoO3. The structure of this highly water sensitive compound can be described in the non‐centrosymmetric monoclinic space group Cc with the lattice constants a = 1522.33(15) pm, b = 390.61(4) pm, c = 771.09(8) pm, β = 104.394(7)° and four formula units per unit cell. Crystallographically unique Mo6+ cations are surrounded by four oxide and twobromide anions in the shape of distorted octahedra withthe two Br– ligands situated in trans position to each other. These octahedra are interconnected by the four O2– anions via vertices to form ${2}\atop{{\infty}}${MoO${v}\atop{4/2}$Br${t}\atop{2/1}$} layers parallel to the bc plane, whereas the bromide anions remain terminal. These sheets are piled along [100] with the Br– anions pointing towards the center of square voids of adjacent layers.
The Complex Amide K2[Zr(NH2)6]
Authors: Kraus Florian , Baer Sebastian A. , Karttunen Antti J. 
Published: April 2011

AbstractWe present the low‐temperature synthesis of potassium hexaamido zirconate(IV) from the transition metal tetrafluoride and thealkali metal dissolved in liquid ammonia at –40 °C. Potassium hexaamido zirconate(IV) K2[Zr(NH2)6] is the first ternary amide reported for elements of group 4 of the periodic table It crystallizes with a novel structure type in the trigonal space group R$\bar{3}$c with a = 6.5422(2) Å, c = 32.824(2) Å, V = 1216.66(9) Å3, Z = 6 and c/a = 5.017. The structure can be derived from the K2PtCl6 type. The compound contains discrete D3‐symmetric [Zr(NH2)6]2– anions which differ significantly from octahedral shape. Quantum chemical calculations show the distortion to arise from a splitting of degenerate d‐orbitals on the zirconium atom leading to a significant gain in energy.