bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response of non‐classically damped structures in the modal subspace
Authors: D'Aveni Antonino , Muscolino Giuseppe 
Published: April 2007

AbstractThe evaluation of the dynamic response of non‐classically damped linear structures requires the solution of an eigenproblem with complex eigenvalues and modal shapes. Since in practice only a small number of complex modes are needed, the complex eigenvalue problem is solved in the modal subspace in which the generalized damping matrix is not uncoupled by classical real modes. It follows that the evaluation of the structural response requires in both cases the determination of complex modes by numerical techniques, which are not as robust as techniques currently used for the solution of the real eigenvalue problem, and the use of complex algebra. In the present paper an unconditionally stable step‐by‐step procedure is presented for the response of non‐classically damped structures in the modal subspace without using complex quantities. The method is based on the evaluation of the fundamental operator in approximated form of the numerical procedure. In addition, the method can be easily modified to incorporate the modal superposition pseudo‐static correction terms.
Dynamic subscales in the finite element approximation of thermally coupled incompressible flows
Authors: Codina Ramon , Principe Javier 
Published: April 2007

AbstractIn this paper, we propose a variational multiscale finite‐element approximation for the incompressible Navier–Stokes equations using the Boussinesq approximation to model thermal coupling. The main feature of the formulation in contrast to other stabilized methods is that we consider the subscales as transient. They are solution of a differential equation in time that needs to be integrated. Likewise, we keep the effect of the subscales both in the nonlinear convective terms of the momentum and temperature equations and, if required, in the thermal coupling term of the momentum equation. Apart from presenting the main properties of the formulation, we also discuss some computational aspects such as the linearization strategy or the way to integrate in time the equation for the subscales. Copyright © 2007 John Wiley & Sons, Ltd.
Comparing density forecast models
Authors: Bao Yong , Lee Tae‐Hwy , Saltoğlu Burak 
Published: April 2007

AbstractIn this paper we discuss how to compare various (possibly misspecified) density forecast models using the Kullback–Leibler information criterion (KLIC) of a candidate density forecast model with respect to the true density. The KLIC differential between a pair of competing models is the (predictive) log‐likelihood ratio (LR) between the two models. Even though the true density is unknown, using the LR statistic amounts to comparing models with the KLIC as a loss function and thus enables us to assess which density forecast model can approximate the true density more closely. We also discuss how this KLIC is related to the KLIC based on the probability integral transform (PIT) in the framework of Diebold et al. (1998). While they are asymptotically equivalent, the PIT‐based KLIC is best suited for evaluating the adequacy of each density forecast model and the original KLIC is best suited for comparing competing models. In an empirical study with the S&P500 and NASDAQ daily return series, we find strong evidence for rejecting the normal‐GARCH benchmark model, in favor of the models that can capture skewness in the conditional distribution and asymmetry and long memory in the conditional variance.  Copyright © 2007 John Wiley & Sons, Ltd.
The hidden martingale restriction in Gram‐Charlier option prices
Authors: Corrado Charles 
Published: April 2007

AbstractA hidden martingale restriction is developed for option pricing models based on Gram–Charlier expansions of the normal density function. The restriction is hidden behind a reduction in parameter space for the Gram–Charlier expansion coefficients. The resulting restriction is invisible in the option price. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27: 517–534, 2007
A simplified approach to modeling the co‐movement of asset returns
Authors: Harris Richard D. F. , Stoja Evarist , Tucker Jon 
Published: April 2007

AbstractThe authors propose a simplified multivariate GARCH (generalized autoregressive conditional heteroscedasticity) model (the S‐GARCH model), which involves the estimation of only univariate GARCH models, both for the individual return series and for the sum and difference of each pair of series. The covariance between each pair of return series is then imputed from these variance estimates. The proposed model is considerably easier to estimate than existing multivariate GARCH models and does not suffer from the convergence problems that characterize many of these models. Moreover, the model can be easily extended to include more complex dynamics or alternative forms of the GARCH specification. The S‐GARCH model is used to estimate the minimum‐variance hedge ratio for the FTSE (Financial Times and the London Stock Exchange) 100 Index portfolio, hedged using index futures, and compared to four of the most widely used multivariate GARCH models. Using both statistical and economic evaluation criteria, it was found that the S‐GARCH model performs at least as well as the other models that were considered, and in some cases it was better. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:575–598, 2007
Testing association between disease and multiple SNPs in a candidate gene
Authors: Gauderman W. James , Murcray Cassandra , Gilliland Frank , Conti David V. 
Published: April 2007

AbstractCurrent technology allows investigators to obtain genotypes at multiple single nucleotide polymorphism (SNPs) within a candidate locus. Many approaches have been developed for using such data in a test of association with disease, ranging from genotype‐based to haplotype‐based tests. We develop a new approach that involves two basic steps. In the first step, we use principal components (PCs) analysis to compute combinations of SNPs that capture the underlying correlation structure within the locus. The second step uses the PCs directly in a test of disease association. The PC approach captures linkage‐disequilibrium information within a candidate region, but does not require the difficult computing implicit in a haplotype analysis. We demonstrate by simulation that the PC approach is typically as or more powerful than both genotype‐ and haplotype‐based approaches. We also analyze association between respiratory symptoms in children and four SNPs in the Glutathione‐S‐Transferase P1 locus, based on data from the Children's Health Study. We observe stronger evidence of an association using the PC approach (p = 0.044) than using either a genotype‐based (p = 0.13) or haplotype‐based (p = 0.052) approach. Genet. Epidemiol. 2007. © 2007 Wiley‐Liss, Inc.
The effect of chronic benzodiazepine use on cognitive functioning in older persons: good, bad or indifferent?
Authors: Bierman E. J. M. , Comijs H. C. , Gundy C. M. , Sonnenberg C. , Jonker C. , Beekman A. T. F. 
Published: April 2007

AbstractObjectiveThis study investigates the effects of benzodiazepine (BZ) use on cognitive performance in elderly persons in a longitudinal design.Study design and settingData were obtained from the Longitudinal Aging Study Amsterdam (LASA), in the Netherlands. 2,105 respondents (≥62 years of age) were included and had repeated measurements over a period of 9 years. For all BZs the type, dosage, frequency and duration of use was measured. The equivalent of a dose of diazepam was determined with regard to type and dosage and a cumulative dosage was calculated. General cognitive functioning was measured with the Mini‐Mental State Examination, information processing speed was measured with the coding task, fluid intelligence with Raven's Coloured Progressive Matrices and episodic memory with the Auditory Verbal Learning Test. Multilevel analyses were used to investigate the relationship between BZ use and cognitive decline.ResultsA negative effect of BZ use on cognitive performance was found. However, the effect sizes were very small.ConclusionThis study suggests that both duration and cumulative exposure to BZ has a small negative effect on the long‐term cognitive functioning of elderly people in the community. Copyright © 2007 John Wiley & Sons, Ltd.
Caffeine and 35% carbon dioxide challenge tests in panic disorder
Authors: Nardi Antonio E. , Valença Alexandre M. , Lopes Fabiana L. , de‐Melo‐Neto Valfrido L. , Freire Rafael C. , Veras Andre B. , Nascimento Isabella , King Anna Lucia , Soares‐Filho Gastão L. , Mezzasalma Marco A. , Zin Walter A. 
Published: April 2007

AbstractOur aim was to compare the demographic and clinical features of panic disorder (PD) patients with agoraphobia—DSM‐IV—who had a panic attack after both an oral caffeine and the 35% carbon dioxide (CO2) challenge tests (responsive group) and compare them with PD patients who did not have a panic attack after both tests (non‐responsive group). We examined 83 PD patients submitted to a 35% CO2test and to an oral caffeine (480 mg) intake within 1 week interval. A panic attack was induced in 51 (61.4%) patients during the CO2test (χ2 = 31.67, df = 1,p < 0.001) and in 38 (45.8%) patients during the caffeine test (χ2 = 18.28, df = 1,p = 0.023). All patients who had a panic attack during the caffeine test also had a panic attack during the CO2test (n = 38)—responsive group. The responsive had more (χ2 = 24.55, df = 1,p = 0.008) respiratory PD subtype, disorder started earlier (Mann‐Whitney,p < 0.001) had a higher familial prevalence of PD (χ2 = 20.34, df = 1,p = 0.019), less previous alcohol abuse (χ2 = 23.42, df = 1,p < 0.001), and had more previous depressive episodes (χ2 = 27.35, df = 1,p < 0.001). Our data suggest that there is an association between respiratory PD subtype and hyperreactivity to challenge tests: CO2and oral caffeine. Copyright © 2007 John Wiley & Sons, Ltd.
Comparison of gene expression data from human and mouse breast cancers: Identification of a conserved breast tumor gene set
Authors: Klein Andreas , Wessel Ralf , Graessmann Monika , Jürgens Martin , Petersen Iver , Schmutzler Rita , Niederacher Dieter , Arnold Norbert , Meindl Alfons , Scherneck Siegfried , Seitz Susanne , Graessmann Adolf 
Published: April 2007

AbstractThe aim of our work was to establish a database for breast cancer gene expression data in order to compare human and mouse breast cancer. We identified human and mouse homologues genes and compared the expression profile of 24 human breast tumors with 6 WAP‐SVT/t breast tumors (WAP‐SVT/t animals, line 8). Our studies confirmed the heterogeneity in gene expression of human as well as mouse breast cancer cells. However, 63 genes were found to be differentially expressed (upregulated: 40; downregulated: 23 genes) in at least 75% of the breast tumors of both species. To differentiate between early and late events in tumor formation, we compared the 63 differentially expressed genes with a mouse data set obtained from hyperplastic mammary glands. This revealed that the majority of the early deregulated genes are cell proliferation specific. These early changes seem to be necessary although not sufficient for breast cancer formation. Late alterations concern mainly genes belonging to the category of cell communication and metabolism. Interestingly, most of the 63 conserved genes are commonly associated with tumorigenesis. © 2007 Wiley‐Liss, Inc.
Preparation and properties of biodegradable polymeric blends from poly(propylene carbonate) and poly(ethylene‐co‐vinyl alcohol)
Authors: Wang X. L. , Du F. G. , Jiao J. , Meng Y. Z. , Li R. K. Y. 
Published: April 2007

AbstractBiodegradable blends of poly(propylene carbonate)/ethylene–vinyl alcohol copolymers (PPC/EVOH) were melt prepared. The mechanical strength, crystallization and melting behavior, morphologies, and thermal properties of these blends were fully investigated using tensile tester, modulated differential scanning calorimetry, scanning electron microscopy, and thermogravimetric analysis, respectively. The results indicated that the thermal stability of blends could be enhanced by increasing EVOH content. No change was observed for the tensile strength when EVOH content was lower than 30 wt %. The tensile strength, however, increased obviously with increasing EVOH content when EVOH content was higher than 30 wt %. The crystallization behavior of the PPC/EVOH blends was studied accordingly. The degradability test showed that the weight loss of PPC/EVOH blends increased with increasing EVOH content because of the strong moisture sorption of EVOH. Morphology observation indicated that the PPC/EVOH blends exhibited a two‐phase microstructure. The blends with EVOH contents ranging from 40 to 60 wt % showed the best comprehensive properties as biodegradable thermoplastic for many applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Comparison of amorphous TCP nanoparticles to micron‐sized α‐TCP as starting materials for calcium phosphate cements
Authors: Brunner Tobias J. , Bohner Marc , Dora Claudio , Gerber Christian , Stark Wendelin J. 
Published: April 2007

AbstractThe development of degradable bone cements with a mineral composition similar to natural bone was investigated using highly reactive calcium phosphate phases as starting materials. Mixtures of XRD‐amorphous, glassy tricalcium phosphate (amorphous‐TCP) nanoparticles of 25–60 nm size and micron sized, milled α‐TCP were set by hydration with sodium phosphate buffer and investigated for possible application as single component calcium phosphate cements (CPCs). Isothermal calorimetry allowed a precise tracking of the setting process. Amorphous‐TCP nanoparticles converted into calcium deficient hydroxyapatite with cement setting times below 12 min. The total energy release by the material during hardening corroborated the importance of high specific surface area and phase composition, that is, amorphous state of the nanometric starting material as repeatedly suggested earlier. The phase composition of the resulting CPCs was characterized by X‐ray diffraction before and after setting. The morphology was investigated by nitrogen adsorption, scanning, and transmission electron microscopy and revealed the formation of highly porous calcium deficient hydroxyapatite with specific surface areas of up to 160 m2 g−1 after setting. In contrast to the very fast reaction time and highest specific surface area, the mechanical stability of the resulting CPC is still insufficient and requires further improvement. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2007
Severe form of congenital cerebral and cerebellar atrophy: A neurodegenerative disorder of fetal onset
Authors: Phadke Shubha , Puri Ratna , Phadke Rajendra 
Published: April 2007

AbstractInfantile olivopontocerebellar atrophy (OPCA) is a rare congenital disorder likely due to an intrauterine neurodegenerative condition. Characteristic presentations are failure to thrive, cerebellar ataxia, respiratory insufficiency, and hypotonia or hypertonia. A few cases with severe manifestations (eg, the Pena‐Shokeir phenotype) presenting in the neonatal period have also been reported. We present a case of infantile OPCA with the Pena‐Shokeir II phenotype and severe atrophy of the cerebellum and cerebral hemispheres. Comparison of prenatal sonographic findings of the fetal brain at 30 weeks' menstrual age and CT findings during the neonatal period indicated prenatal onset of the neurodegenerative process, which progressed rapidly during the last trimester. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007
The dynamic fetal brain
Authors: Towner Dena , McGahan John , Rhee‐Morris Laila , Gerscovich Eugenio 
Published: April 2007

AbstractPurpose.To evaluate fetuses with normal intracranial anatomy in the second trimester that became abnormal in the third trimester.Methods.We sonographically examined 6 fetuses with a normal second‐trimester head sonogram that presented later in pregnancy with an abnormal head sonogram.Results.Four categories of intracranial pathology were depicted: obstructive hydrocephalus, intraventricular intracranial hemorrhage, non‐intraventricular intracranial hemorrhage, and porencephaly.Conclusions.Despite a normal midtrimester intracranial examination, evaluation of the fetal intracranial contents should be undertaken in subsequent sonographic examinations, because significant pathology can develop spontaneously. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007
Acromioclavicular joint injury: Enhanced technique of examination with dynamic maneuver
Authors: Peetrons Philippe , Bédard Justine P. 
Published: April 2007

AbstractAcromioclavicular (AC) sprains can be graded in 3 to 6 different types according to Tossy or Rockwell, respectively. In mild sprains (Tossy and Rockwell I), movements in the AC joint are minimal, because the coraco‐clavicular ligaments are intact. In these patients, stress radiography is usually normal, and sonographic examination at rest can be normal as well, showing minimal or no displacement between the 2 extremities of the bones. We present a simple dynamic maneuver to enhance the diagnosis of these mild sprains known as the cross‐arm maneuver, in which the hand is placed on the opposite shoulder. The dynamic sonographic examination during this maneuver clearly shows abnormal movements in the clavicle's extremity, which “falls down” to the acromion in the cross‐arm position and is raised and pulled from the acromion at rest. The maneuver is very easy to perform and may be useful when a mild AC joint sprain is suspected. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007
FAIR‐TrueFISP imaging of cerebral perfusion in areas of high magnetic susceptibility differences at 1.5 and 3 Tesla
Authors: Boss Andreas , Martirosian Petros , Klose Uwe , Nägele Thomas , Claussen Claus D. , Schick Fritz 
Published: April 2007

AbstractPurposeTo estimate cerebral blood perfusion in areas of strong magnetic susceptibility changes with high spatial and temporal resolution using a flow‐sensitive alternating inversion recovery (FAIR) arterial spin labeling (ASL) method.Materials and MethodsWe implemented an ASL method that is capable of imaging perfusion in areas of high magnetic susceptibility changes by combining a FAIR spin preparation with a true fast imaging in steady precession (TrueFISP) data acquisition strategy. A TrueFISP readout sequence was applied especially in regions with magnetic field inhomogeneities and compared with corresponding FAIR measurements obtained with a standard echo‐planar imaging (EPI) readout. Quantitative perfusion images were obtained at 1.5 Tesla (1.5T) from eight healthy volunteers (24–42 years old) and one patient (23 years old). FAIR‐TrueFISP perfusion images were compared with FAIR echo‐planar images. T1 maps, which are necessary for quantitative perfusion estimation, were obtained with inversion recovery (IR) TrueFISP and IR EPI. Additionally, high‐resolution perfusion measurements were performed on four volunteers at 3T.ResultsThe two ASL perfusion imaging modalities yielded comparable diagnostic image quality in brain areas with low susceptibility differences at 1.5T. Cerebral perfusion of gray matter (GM) areas was 105.7 ± 5.2 mL/100 g/minute for FAIR‐TrueFISP and 88.8 ± 14.6 mL/100 g/minute for FAIR‐EPI at 1.5T, and 70.4 ± 7.1 mL/100 g/minute for FAIR‐TrueFISP and 63.5 ± 6.9 mL/100 g/minute for FAIR‐EPI at 3.0T. Higher perfusion values at 1.5T were due to more pronounced partial‐volume effects from fast moving spins at lower spatial resolution. The FAIR‐TrueFISP sequence showed no significant distortions and markedly reduced signal void artifacts in areas of high susceptibility changes (e.g., near brain–bone transitions and close to metallic clips) compared to FAIR‐EPI. At 3T, highly resolved FAIR‐TrueFISP perfusion images were acquired with an in‐plane resolution of up to 1.3 mm.ConclusionFAIR‐TrueFISP allows for assessment of cerebral perfusion in areas of critically high susceptibility changes with conventional ASL methods. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Quadrature coil design for high‐resolution carotid artery imaging scores better than a dual phased‐array coil design with the same volume coverage
Authors: Ouhlous Mohamed , Moelker Adriaan , Flick Herman J. , Wielopolski Piotr A. , de Weert Thomas T. , Pattynama Peter M.T. , van der Lugt Aad 
Published: April 2007

AbstractPurposeTo evaluate the ability of a custom‐built coil design to provide improved signal‐to‐noise ratio (SNR) and less signal drop with increasing depth at the carotid artery.Materials and MethodsPhased‐array surface coils can provide a high SNR to image the carotid vessel wall. However, given the required field‐of‐view (FOV) and penetration depth, these coils show either a fast signal drop with increasing depth or a moderate SNR at increased coil size. A quadrature surface coil (a butterfly coil in conjunction with a linear single‐loop coil) was compared with a phased‐array coil in phantom and human studies.ResultsThe phantom studies showed that the quadrature coil has better SNR over the required FOV than a standard phased‐array coil (26% at 3 cm depth).ConclusionThe quadrature coil enables better image quality to be achieved. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Lactate, choline, and creatine levels measured by vitro 1H‐MRS as prognostic parameters in patients with non‐small‐cell lung cancer
Authors: Yokota Hajime , Guo Jianfei , Matoba Munetaka , Higashi Kotaro , Tonami Hisao , Nagao Yosinobu 
Published: April 2007

AbstractPurposeTo determine the biochemical characteristics of lung cancer tissue using in vitro 1H‐MRS, and investigate the correlation between survival probabilities and lactate (Lac), creatine (Cr), and choline (Cho) concentrations measured by in vitro 1H‐MRS.Materials and MethodsA total of 21 patients with lung cancer were included in this retrospective study. 1H‐MRS spectra measurements were performed at 6.35T using a JNM‐EX270, high‐resolution FT‐NMR spectrometer.ResultsWhen normal lung tissue was compared with lung cancer tissue, significant differences were noted most consistently in the levels of Lac and Cho, with lung cancer tissue showing higher values than normal lung tissue. Lac concentrations of lung cancer tissue were significantly higher in patients with recurrence compared to patients without recurrence (0.285 ± 0.096 μmol/g). The mean overall survival of patients in the low‐Lac group was 50.28 ± 6.47 months, which is significantly higher compared to the high‐Lac group, which had a mean survival time of only 30.49 ± 5.41 months.ConclusionKaplan‐Meier analysis of the data showed that the overall and disease‐free survival probabilities were significantly higher in patients with low tumor Lac values than in those with high tumor Lac concentrations. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.