bluuebunny/crossref_metadata_2025_split huggingface dataset:
Removing the effect of SVD algorithmic artifacts present in quantitative MR perfusion studies
Authors: Smith M.R. , Lu H. , Trochet S. , Frayne R. 
Published: February 2004

AbstractQuantitative cerebral blood flow (CBF) values can be obtained from dynamic susceptibility contrast (DSC) MR perfusion studies using the standard singular value decomposition (sSVD) deconvolution algorithm. Reports in the literature from simulation and in vivo studies suggest that CBF estimates obtained using sSVD deconvolution depend on the arterial‐tissue delay (ATD). By contrast, Fourier transform (FT) deconvolution produces CBF estimates that are independent of ATD. The diagnostic reliability of quantitative CBF measurements to define areas of normal tissue flow and tissue at risk is brought into doubt by such gross sensitivity to the specifics of the deconvolution approach. This variation of CBF values with ATD is shown to be an artifact associated with the current implementation of the sSVD deconvolution algorithm. A reformulated version of the SVD deconvolution algorithm (rSVD) is presented and compared to the standard SVD algorithm through simulation and patient case studies. Magn Reson Med 51:631–634, 2004. © 2004 Wiley‐Liss, Inc.
Measurement of brain glutamate using TE‐averaged PRESS at 3T
Authors: Hurd Ralph , Sailasuta Napapon , Srinivasan Radhika , Vigneron Daniel B. , Pelletier Daniel , Nelson Sarah J. 
Published: February 2004

AbstractA method is introduced that provides improved in vivo spectroscopic measurements of glutamate (Glu), glutamine (Gln), choline (Cho), creatine (Cre), N‐acetyl compounds (NAtot, NAA + NAAG), and the inositols (mI and sI). It was found that at 3T, TE averaging, the f1 = 0 slice of a 2D J‐resolved spectrum, yielded unobstructed signals for Glu, Glu + Gln (Glx), mI, NAtot, Cre, and Cho. The C4 protons of Glu at 2.35 ppm, and the C2 protons of Glx at 3.75 ppm were well resolved and yielded reliable measures of Glu/Gln stasis. Apparent T1/T2 values were obtained from the raw data, and metabolite tissue levels were determined relative to a readily available standard. A repeatibility error of <5%, and a coefficient of variation (CV) of <10% were observed for brain Glu levels in a study of six normal volunteers. Magn Reson Med 51:435–440, 2004. © 2004 Wiley‐Liss, Inc.
Decreased cerebral perfusion correlates with increased BOLD hyperoxia response in transgenic mouse models of sickle cell disease
Authors: Kennan Richard P. , Suzuka Sandra M. , Nagel Ronald L. , Fabry Mary E. 
Published: February 2004

AbstractNeurological complications such as stroke are known consequences of sickle cell disease (SCD). In order to improve methods for the evaluation of stroke risk in SCD, MRI was used to evaluate cerebrovascular function in transgenic mouse models of human SCD. It is hypothesized that oxygen‐sensitive imaging in the brain will reveal areas of excess deoxygenation that are either at risk of or the result of vaso‐occlusion. Arterial spin labeling (ASL) perfusion was performed in order to correlate BOLD results with microvascular cerebral blood flow. Upon comparison with control animals, there was a relative increase in BOLD hyperoxia response of 42–67% (P < 0.001) in the transgenic mice while cerebral blood flow during normoxia was reduced by 30–40% (P < 0.02). Hyperoxia caused cerebral blood flow to decrease in control mice, whereas blood flow increased in the sickle transgenic mice. These results indicate impairment in brain autoregulation in the sickle cell transgenic mice leading to increased cerebral deoxyhemoglobin. Increased deoxyhemoglobin coupled with reduced perfusion may further increase the risk of vaso‐occlusion and stroke. This may reflect polymer reduction or reduced cell adhesion during hyperoxia. The MRI protocol is noninvasive and thus directly applicable to a clinical population. Magn Reson Med 51:525–532, 2004. © 2004 Wiley‐Liss, Inc.
In vivo assessment of tumoral angiogenesis
Authors: Troprès I. , Lamalle L. , Péoc'h M. , Farion R. , Usson Y. , Décorps M. , Rémy C. 
Published: February 2004

AbstractVessel size imaging (VSI) for brain tumor characterization was evaluated and the vessel size index measured by MRI (VSIMRI) was correlated with VSI obtained by histology (VSIhisto). Blood volume (BV) and VSI maps were obtained on 12 rats by simultaneous measurements of R2* and R2, before and after the injection of a macromolecular contrast agent, AMI‐227. Immunostaining of collagen IV in vessels was performed. An expression was derived for evaluating VSI from stereologic measurements on histology data (VSIhisto). On BV and VSI images obtained from large‐size tumors (n = 9), three regions could be distinguished and correlated well with histological sections: a high BV region surrounding the tumor, a necrotic area where BV is very low, and a viable tumor tissue region showing lower BV but higher VSI than the normal rat cortex, with the presence of larger vessels. The quantitative analysis showed a good correlation (Spearman rank's rho = 0.74) between VSIhisto and VSIMRI with a linear regression coefficient of 1.17. The good correlation coefficient supports VSI imaging as a quantitative method for tumor vasculature characterization. Magn Reson Med 51:533–541, 2004. © 2004 Wiley‐Liss, Inc.
Accentuation of high susceptibility of hypertrophied myocardium to ischemia: Complementary assessment of Gadophrin‐enhancement and left ventricular function with MRI
Authors: Schalla Simon , Wendland Michael F. , Higgins Charles B. , Ebert Wolfgang , Saeed Maythem 
Published: February 2004

AbstractThe aim of the study was to compare infarction size and left ventricular (LV) function in normal and hypertrophied hearts after brief ischemia using Gadophrin‐enhancement and functional assessment by MRI. Rats (n = 20) were assigned to aortic banding to induce LV hypertrophy or control. Eight weeks later, rats were subjected to 25 min of regional myocardial ischemia followed by 3 hr of reperfusion. The necrosis‐specific agent Gadophrin‐3 was injected to delineate infarcted myocardium on MRI. Effects of aortic banding and ischemia on LV mass and function were determined. At postmortem, areas at risk and infarction were measured. Close correlation was found between LV mass measured with MRI and at postmortem (r = 0.98). LV mass measured with MRI was significantly greater (0.81 ± 0.02 g) in animals with aortic banding compared to control (0.62 ± 0.02 g; P < 0.001). Infarction size was larger in hypertrophied hearts (19.0 ± 1.4% / 18.3 ± 1.5%) than in control (9.8 ± 1.7% / 9.2 ± 2.0%) on Gadophrin‐enhanced MRI and at postmortem, respectively. Similarly, greater impairment in ejection fraction was observed in hypertrophied hearts with MRI (39 ± 4% vs. 49 ± 2%; P = 0.02). Gadophrin‐3 provides accurate estimation of infarct size in hypertrophied hearts. Hypertrophied hearts are more sensitive to ischemia than nonhypertrophied hearts. The complementary assessment of Gadophrin‐enhancement and LV function with MRI provides unique information about myocardium sensitivity to ischemia. Magn Reson Med 51:552–558, 2004. © 2004 Wiley‐Liss, Inc.
Chemical shift and magnetic susceptibility contributions to the separation of intracellular and supernatant resonances in variable angle spinning NMR spectra of erythrocyte suspensions
Authors: Philp David J. , Bubb William A. , Kuchel Philip W. 
Published: February 2004

AbstractFactors contributing to the observation of two separate water resonance arising from erythrocyte suspensions under magic‐ and variable‐angle spinning conditions were examined. By observing the 1H NMR spectra of different chemical species in erythrocytes at different spinning angles, two major effects of comparable magnitude were shown to contribute to the separation: 1) an isotropic chemical shift difference, and 2) a susceptibility difference between the intracellular and supernatant compartments. When the sample was spun at the magic angle, the susceptibility difference did not contribute to the separation. Use of different angles between the spinning axis and the main magnetic field provided a method for quantifiying the isotropic chemical shift and susceptibility differences between the compartments. Magn Reson Med 51:441–444, 2004. © 2004 Wiley‐Liss, Inc.
Accelerated masonry construction review and future prospects
Authors: Ramamurthy K , Kunhanandan Nambiar E K 
Published: February 2004

AbstractThe limitations of conventional masonry cited quite often with respect to constructional, structural and functional performances are summarized, along with attempts to overcome these limitations through different methods of accelerating masonry construction (increasing size of masonry units, elimination of bedding mortar through adoption of: (i) conventional blocks using surface bonding or partial grouting; and (ii) interlocking blocks using dry‐stacking, or surface bonding) developed and proof‐tested or adopted in practice. The accelerated mortarless masonry constructions developed or being used in different countries and by various researchers vary in material, geometry and interlocking mechanism. A classification of interlocking block masonry systems is made, along with a review on the behaviour of some of these systems. The issues to be addressed by researchers in order to achieve a ‘High‐performance masonry’ are highlighted.
Vibration characteristics of steel–concrete composite floor systems
Authors: Hicks Stephen 
Published: February 2004

AbstractTrends towards long‐span, lightweight floors in steel–concrete composite construction are resulting in structures possessing low natural frequencies, and potentially susceptible to vibration problems. The most common source of vibrations is caused by human activities on the floor, however, in some instances, mechanically induced vibrations from air conditioning plant, etc. may also be problematic. In this paper the serviceability assessment of floor vibration occasioned by walking activities is considered.Over 30 years ago concerns were raised regarding vibrations induced by walking on steel–concrete composite floors that satisfied traditional deflection criteria. In response to these concerns, design criteria based on a simple impulsive loading function from a person rising onto the balls of the feet, and suddenly dropping onto the heels has been used as a measure of floor acceptability. More recently, design procedures have been developed that more realistically consider the excitation of the floor from walking activities.In the first part of this paper a historical review of acceptability criteria for floor vibrations will be made. Following this, the current design methodologies for steel–concrete composite floors will be reviewed prior to the presentation of results from a series of in situ vibration tests on a wide variety of floor types. After comparing the test results with current guidance, design recommendations and suggestions for future research will be given.
US–Japan cooperative earthquake research program on CFT structures: achievements on the Japanese side
Authors: Nishiyama Isao , Morino Shosuke 
Published: February 2004

AbstractThe US–Japan Cooperative Earthquake Research Program began in 1979, following the recommendations as outlined in the final report of the US–Japan Planning Group for the Program. The first four phases of the Program have been implemented on: (1) reinforced concrete; (2) structural steel; (3) masonry, and (4) precast/prestressed concrete. Phase 5, on composite and hybrid structures, was carried out from the fiscal year 1993 over 5‐years. In this phase, the following four research topics were executed: (1) new materials, elements and systems; (2) concrete‐filled structural steel tube column systems; (3) reinforced concrete column and structural steel beam systems; and (4) reinforced concrete and steel‐reinforced concrete wall systems.In this paper, the technical research conducted on the Japanese side related to the research topic of the concrete‐filled structural steel tube column system is overviewed and summarized. It includes experimental results (columns, beam–columns and beam–and‐column subassemblages), proposed design recommendations and a design implication study.
Structural damage in steel construction: regulatory aspects
Authors: Mirambell Enrique 
Published: February 2004

AbstractThis article reviews the damage found more or less systematically in the construction of carbon steel structures. The types of damage that occur and their causes are reviewed from a general standpoint, taking into account steel construction in buildings and public works. Classification of this damage and its analysis are made on the basis of the construction process, with particular emphasis on aspects linked to the design stage. We also look at certain regulatory considerations.
Function and technology of historic cross vaults
Authors: Theodossopoulos D , Sinha B P 
Published: February 2004

AbstractThis paper presents an outline of the technology of historic masonry cross vaults. The development of construction techniques for this roofing system has been highly dependent upon understanding the crucial role played by ribs in Gothic architecture in which a wide variety of forms was produced during the evolution of the structural scheme of buildings. Many of these technical issues were examined during the construction of a 1/4‐scale model cross vault, as part of an experimental project to assess the degree of safety of these structures. The model represents the remaining aisle vaults of the partially collapsed Holyrood Abbey church in Edinburgh, and was tested to failure by movement of abutments. Cross vaults are an integral part of the structure of many historic buildings, and knowledge of their technology and safety can significantly enhance the effectiveness of a conservation project.
Why educate “little scientists?” Examining the potential of practice‐based scientific literacy
Authors: Kevin O'Neill D. , Polman Joseph L. 
Published: February 2004

AbstractIn recent years, a number of curriculum reform projects have championed the notion of having students do science in ways that move beyond hands‐on work with authentic materials and methods, or developing a conceptual grasp of current theories. These reformers have argued that students should come to an understanding of science through doing the discipline and taking a high degree of agency over investigations from start to finish. This stance has occasionally been mocked by its critics as an attempt to create “little scientists”—a mission, it is implied, that is either romantic or without purpose. Here, we make the strong case for a practice‐based scientific literacy, arguing through three related empirical studies that taking the notion of “little scientists” seriously might be more productive in achieving current standards for scientific literacy than continuing to refine ideas and techniques based on the coverage of conceptual content. Study 1 is a classroom case study that illustrates how project‐based instruction can be carried out when teachers develop guidance and support strategies to bootstrap students' participation in forms of inquiry they are still in the process of mastering. Study 2 shows how sustained on‐line work with volunteer scientists appears to influence students' success in formulating credible scientific arguments in written project reports following an authentic genre. Study 3, using data from three suburban high school classes, suggests that involving students in the formulation of research questions and data analysis strategies results in better spontaneous use of empirical data collection and analysis strategies on a transfer task. The study also suggests that failing to involve students in the formulation of research can result in a loss of agency. The implications of these findings for future research and practice are discussed. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 234–266, 2004
Implementation variation and fidelity in an inquiry science program: Analysis of GLOBE data reporting patterns
Authors: Penuel William R. , Means Barbara 
Published: February 2004

AbstractThis article examines variations in patterns in the enactment of a large‐scale kindergarten through Grade 12 science inquiry program. Student data reports in the GLOBE program provide a useful measure of implementation because key design elements in the program are student collection and reporting of local environmental data. We examined associations among teachers' responses to survey items to patterns in GLOBE data reporting to develop hypotheses about important contextual factors related to program implementation. Implications for the study of science inquiry programs are discussed. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 294–315, 2004
Effects of the combined continuous administration of morphine and the high‐efficacy 5‐HT1A agonist, F 13640 in a rat model of trigeminal neuropathic pain
Authors: Deseure Kristof R. , Adriaensen Hugo F. , Colpaert Francis C. 
Published: February 2004

AbstractF 13640 is a recently discovered high‐efficacy 5‐HT1A receptor agonist that has demonstrated robust anti‐allodynic efficacy in a rat model of trigeminal neuropathic pain upon acute and continuous administration. In this model, continuous morphine infusion (5 mg/day) was shown to be effective during the first week of its administration but became almost completely ineffective by the end of the second week; F 13640's effectiveness (0.63 mg/day) remained unchanged during two weeks. Here, we examined the effects of combining F 13640 infusion with that of morphine. During the first week, the combination of the two agents produced a magnitude of effect that was similar to that of morphine when given alone and larger than that of F 13640 alone. During the second week, the combination produced an effect that was similar to that of F 13640 alone, and more effective than that of morphine alone. The latter data suggest that the 5‐HT1A agonist, F 13640, inhibits the development of tolerance to morphine in this model. However, it is also possible that little, if any, interaction occurred between the different mechanisms initiated by opioid and 5‐HT1A receptor activation, and that the anti‐allodynic effect that remained by the end of the two‐week treatment period is due solely to 5‐HT1A receptor activation. The stable effects of F 13640 during the second week of treatment surpassed those of morphine and were not improved by the addition of morphine to F 13640.
Modification of attentional biases in chronic pain patients: a preliminary study
Authors: Dehghani M. , Sharpe L. , Nicholas M.K. 
Published: February 2004

AbstractResearch suggests that chronic pain patients demonstrate cognitive biases towards pain‐related information and that such biases predict patient functioning. This study examined the degree to which a successful cognitive‐behavioural program was able to reduce the observed attentional bias towards sensory pain words. Forty‐two patients with chronic pain conditions for more than three months were recruited prior to commencing a cognitive‐behavioural pain management program. Participants were assessed before the program, after the program and at one‐month follow‐up. Results confirmed that chronic pain patients exhibited biased attention towards sensory pain‐related words at pre‐treatment. These biases were still evident at post‐treatment, but were no longer statistically significant at follow‐up. Multiple regression analyses indicated that the changes in attentional bias towards sensory words between post‐treatment and follow‐up were predicted by pre‐ to post‐treatment changes in fear of movement (Tampa Scale for Kinesiophobia) but not other relevant variables, such fear of pain or anxiety sensitivity. These results demonstrate that successful cognitive‐behavioural treatments can reduce selective attention, thought to be indicative of hypervigilance towards pain. Moreover, these biases appear to be changed by reducing the fear associated with movement. Theoretically, these results provide support for the fear of (re)injury model of pain. Clinically, this study supports the contention that fear of (re)injury and movement is an appropriate target of pain management and that reducing these fears causes patients to attend less to pain‐related stimuli.
Clinical predictors of admission status in first episode schizophrenia
Authors: Kelly B.D. , Clarke M. , Browne S. , McTigue O. , Kamali M. , Gervin M. , Kinsella A. , Lane A. , Larkin C. , O’Callaghan E. 
Published: February 2004

AbstractHaving a diagnosis of schizophrenia is a risk factor for involuntary admission to psychiatric inpatient care, but we have a limited understanding of why some patients and not others require involuntary admission. We aimed to identify the predictors of involuntary admission in first episode schizophrenia. We used validated instruments to assess clinical and socio-demographic variables in all patients (n = 78) with first episode schizophrenia from a defined geographical area admitted to a Dublin psychiatric hospital over a 4-year period. Involuntary patients (n = 17) could not be distinguished from voluntary patients (n = 61) on the basis of age, gender, living status, marital status, drug abuse or duration of untreated psychosis. Neither positive nor negative symptoms were useful predictors of admission status. Lack of insight was a strong predictor of involuntary status.
Transforming growth factor‐β1 induced alteration of skeletal morphogenesis in vivo
Authors: Ferguson Cristin M. , Schwarz Edward M. , Puzas J. Edward , Zuscik Michael J. , Drissi Hicham , O'Keefe Regis J. 
Published: February 2004

AbstractTransforming growth factor beta (TGF‐β) is expressed in the growth plate and is an important regulator of chondrocyte maturation. Loss of function results in premature chondrocyte maturation both in vitro and in vivo. While TGF‐β inhibits chondrocyte maturation in cell cultures, the effect of increased TGF‐β has not been well characterized in an in vivo development model. Addition of Affi‐gel agarose beads loaded with TGF‐β1 (10 ng/μl) to developing stage 24–25 chick limb buds resulted in limb shortening and altered morphology. In situ hybridization studies showed down regulation of Indian hedgehog (ihh), bone morphogenetic protein 6 (bmp6), and collagen type X (colX) expression, markers of chondrocyte maturation, in TGF‐β1 treated limbs. TGF‐β1 also decreased chondrocyte proliferation in the developing anlage. The findings confirm a critical role for TGF‐β during skeletal development. A more complete understanding of the role of TGF‐β and its down‐stream signals will lead to improved understanding and treatment of cartilage diseases. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
On the estimation of stock‐market reaction to corporate layoff announcements
Authors: Hahn TeWhan , Reyes Mario G. 
Published: February 2004

AbstractThis study investigates the stock‐market reaction to layoff announcements where more than 1000 workers are affected. We employ a dummy variable regression (DVR) version of the market model and compare the results obtained using ordinary least squares (OLS) versus exponential GARCH (EGARCH), and value‐weighted (VW) versus equally weighted (EW) market index. We find that the stock market responds negatively to layoffs attributed to low demand. We also find that contrary to prior research, the market reacts positively to restructuring‐related layoffs on the announcement date. This pattern of market reaction is observed regardless of the market index used or the parameter estimation methods employed, although the empirical results indicate that using EGARCH/VW market index tends to generate fewer statistically significant test results and smaller (in the absolute size of the cumulative) abnormal returns (ARs). Taken together, our study provides additional support for the claim that studies of stock‐market reaction to corporate events must account for the time variation in return volatility. Ignoring these could result in erroneous inferences.