bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical group comparison of diffusion tensors via multivariate hypothesis testing
Authors: Whitcher Brandon , Wisco Jonathan J. , Hadjikhani Nouchine , Tuch David S. 
Published: May 2007

AbstractDiffusion tensor imaging (DTI) provides a powerful tool for identifying white matter (WM) alterations in clinical populations. The prevalent method for group‐level analysis of DTI is statistical comparison of the diffusion tensor fractional anisotropy (FA) metric. The FA metric, however, does not capture the full orientational information contained in the diffusion tensor. For example, the FA test is incapable of detecting group‐level differences in diffusion orientation when the level of anisotropy is unaffected. Here, we apply multivariate hypothesis testing procedures to the elements of the diffusion tensor as an alternative to univariate testing using FA. Both parametric and nonparametric tests are proposed with each choice carrying specific assumptions about the diffusion tensor model. Of particular interest is the Cramér test, which works on Euclidean interpoint distances and can be readily adapted to a specific non‐Euclidean framework by applying matrix logarithms to the diffusion tensors. Using Monte Carlo simulations, we show that multivariate tests can detect diffusion tensor principal eigenvector differences of 15 degrees with up to 80–90% power under typical design conditions. We also show that some multivariate tests are more sensitive to FA differences, when compared to a univariate test on FA, even if there is no principal eigenvector difference. The Cramér test, using the Euclidean interpoint distances, performed best under both simulation scenarios. When applying the Cramér test of the diffusion tensor in a clinical population with a history of migraine, a 169% increase was observed in the volume of a significant cluster compared to the univariate FA test. Magn Reson Med 57:1065–1074, 2007. © 2007 Wiley‐Liss, Inc.
2H double quantum filtered (DQF) NMR spectroscopy of the nucleus pulposus tissues of the intervertebral disc
Authors: Perea William , Cannella Marco , Yang Jun , Vega Alexander J. , Polenova Tatyana , Marcolongo Michele 
Published: May 2007

AbstractDeuterium (2H) double‐quantum filtered (DQF) NMR spectroscopy of nucleus pulposus (NP) tissues from human intervertebral discs is reported. The DQF spectral intensities, DQ build‐up rates, and DQF‐detected rotating‐frame spin‐lattice relaxation times are sensitive to the degree of hydration of the NP tissue, and display a monotonous correlation with age between 15 and 80 years. The implications of this work are that the changes in water dynamics as detected via DQF NMR spectroscopy may be used as a probe of tissue degeneration in NP, particularly in the early stages of degeneration to which most standard NMR methods are not sensitive. Magn Reson Med 57:990–999, 2007. © 2007 Wiley‐Liss, Inc.
Self‐calibration method for radial GRAPPA/k‐t GRAPPA
Authors: Huang Feng , Vijayakumar Sathya , Li Yu , Hertel Sarah , Reza Shahed , Duensing George R. 
Published: May 2007

AbstractGeneralized autocalibrating partially parallel acquisitions (GRAPPA), an important parallel imaging technique, can be easily applied to radial k‐space data by segmenting the k‐space. The previously reported radial GRAPPA method requires extra calibration data to determine the relative shift operators. In this work it is shown that pseudo‐full k‐space data can be generated from the partially acquired radial data by filtering in image space followed by inverse gridding. The relative shift operators can then be approximated from the pseudo‐full k‐space data. The self‐calibration method using pseudo‐full k‐space data can be applied in both k and k‐t space. This technique avoids the prescans and hence improves the applicability of radial GRAPPA to image static tissue, and makes k‐t GRAPPA applicable to radial trajectory. Experiments show that radial GRAPPA calibrated with pseudo‐full calibration data generates results similar to radial GRAPPA calibrated with the true full k‐space data for that image. If motion occurs during acquisition, self‐calibrated radial GRAPPA protects structural information better than externally calibrated GRAPPA. However, radial GRAPPA calibrated with pseudo‐full calibration data suffers from residual streaking artifacts when the reduction factor is high. Radial k‐t GRAPPA calibrated with pseudo‐full calibration data generates reduced errors compared to the sliding‐window method and temporal GRAPPA (TGRAPPA). Magn Reson Med 57:1075–1085, 2007. © 2007 Wiley‐Liss, Inc.
Numerical calculation of grounding system in low‐frequency domain based on the boundary element method
Authors: Li Zhong‐Xin , Fan Jian‐Bin 
Published: May 2007

AbstractA new mathematical model for accurately computing currents flowing along the high‐voltage ac substation's grounding system and nearby floating metallic conductors buried in the multilayer earth model has been developed in this paper, which is a hybrid of the Galerkin‐type boundary element method (BEM) and the conventional nodal analysis method. Only the propagation effect of electromagnetic waves within the substation's limited area has been neglected in this model. The quasi‐static complex image method and the closed form of Green's function are introduced into this model to accelerate the mutual impedance and induction coefficients calculation. The model is then implemented in a computer program, which can be used to calculate current distribution of any configuration of the grounding system, with or without floating metallic conductors'. Copyright © 2007 John Wiley & Sons, Ltd.
A higher‐order potential flow method for thick bodies, thin surfaces and wakes
Authors: Bernasconi D. J. , Richelsen P. M. 
Published: May 2007

AbstractA higher‐order panel method for analysing the three‐dimensional potential flow fields around bodies and wakes is presented. The geometric surfaces are represented by continuous curved patches, with no discretization into panels. These geometric patches hold singularity distributions that have C2 continuity, and which are solved by applying Dirichlet or Neumann boundary conditions at discrete collocation points. While higher‐order methods have previously been developed for thick bodies and Dirichlet boundary conditions, this potential flow method is capable of modelling continuous geometry and singularity surfaces over thin bodies and wakes.The continuous surface method has a number of advantages over conventional constant panel methods. Firstly, as curved geometries are represented exactly, changing the order of the solution does not modify the physical shape of the configuration under investigation. Furthermore, the continuous singularity distributions allow velocities to be evaluated accurately across the entire surface rather than just at collocation points. This means that pressure distributions can be calculated exactly without interpolation, and streamlines can be constructed very close to surfaces without problems of divergence. Finally, body and wake surfaces do not exhibit the strong modelling singularities that can present difficulties with wake relaxation. Copyright © 2007 John Wiley & Sons, Ltd.
Interferon‐gamma‐dependent mechanisms of mycobacteria‐induced pulmonary immunopathology: the role of angiostasis and CXCR3‐targeted chemokines for granuloma necrosis
Authors: Aly S , Laskay T , Mages J , Malzan A , Lang R , Ehlers S 
Published: May 2007

AbstractThe mechanisms leading to granuloma caseation, a hallmark of tuberculosis (TB) in humans, are poorly understood. Lung histopathology of C57BL/6 (WT) mice 16 weeks after aerosol infection with Mycobacterium avium strain TMC724 is uniquely characterized by centrally necrotizing granulomas, strongly resembling human TB lesions. However, IFN‐γ‐deficient (GKO) and IFN‐γ‐receptor‐deficient (GRKO) mice did not develop granuloma necrosis following M. avium infection. Comparison of differentially expressed genes in infected WT and GKO lungs by DNA microarray and RNase protection assays revealed that the angiostatic chemokines CXCL9–11 were significantly reduced in GKO mice. In contrast, angiogenic mediators such as angiopoietin and vascular endothelial growth factor, and angiogenic chemokines such as CXCL2, CCL3, and CCL4, remained unchanged or were expressed at higher levels than in infected WT mice, suggesting impaired neovascularization of the granuloma as a possible mechanism for caseation in WT mice. Granuloma vascularization was significantly decreased in central, but not peripheral, areas of granulomas of infected WT compared to GKO mice. In contrast to GRKO mice, WT mice showed signs of severe hypoxia in cells immediately surrounding the necrotic core of granulomas as measured immunohistochemically with a reagent detecting pimonidazole adducts. To test the hypothesis that CXCR3, the common receptor for the angiostatic chemokines CXCL9–11, is involved in granuloma caseation, histomorphology was assessed in M. avium‐infected mice deficient for CXCR3 (CXCR3‐KO). 16 weeks after infection, these mice developed caseating granulomas similar to WT mice. We conclude that IFN‐γ causes a dysbalance between angiostatic and angiogenic mediators and a concomitant reduction in granuloma vascularization, but that CXCR3‐targeted chemokines are not sufficient to induce granuloma necrosis in a mouse model of mycobacteria‐induced immunopathology. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
The phosphatidylserine receptor mediates phagocytosis by vascular smooth muscle cells
Authors: Kolb S , Vranckx R , Huisse M‐G , Michel J‐B , Meilhac O 
Published: May 2007

AbstractApoptosis participates in every step of atherogenesis, but the process of clearance of apoptotic cells by phagocytosis has been underestimated. Rapid removal of apoptotic cells is critical for tissue homeostasis, in order to avoid accumulation of necrotic material and subsequent inflammation in the pathological vascular wall. We have demonstrated by RT–PCR, western blot and immunocytofluorescence that vascular smooth muscle cells (VSMCs) express the phosphatidylserine receptor (PSR). We then tested the involvement of PSR in the ability of VSMCs to bind and engulf apoptotic cells. We used a model of senescent erythrocytes, which expose PS after 4 days of culture (85% of cells relative to 8% in freshly isolated erythrocytes). The pseudo‐peroxidase activity of haemoglobin contained within erythrocytes allowed us to quantify per se both binding and phagocytosis by VSMCs. We have also shown by light and confocal microscopy that VSMCs were able to ingest aged erythrocytes. Addition of a blocking antibody or transfection of VSMCs by a siRNA directed against PSR reduced the binding and engulfment of aged erythrocytes by more than 90%. These results suggest that PSR is involved in phagocytosis of PS‐presenting cells. Incubation of aged erythrocytes with VSMCs also significantly increased the expression of PSR, suggesting that the tethering/ingestion of apoptotic cells triggers this process. Immunostaining for PSR in complicated atherosclerotic plaques shows positivity in the media and macrophage‐rich areas. The mechanisms underlying phagocytosis and involving PSR in vivo, within the pathological arterial wall, deserve further investigation. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Pemetrexed, a multitargeted antifolate drug, demonstrates lower efficacy in comparison to methotrexate against osteosarcoma cell lines
Authors: Bodmer N. , Walters D.K. , Fuchs B. 
Published: May 2007

AbstractThe folate inhibitor methotrexate (MTX) is an important component of osteosarcoma (OS) treatment regimens. New generation multitargeted antifolates, such as pemetrexed (PMX), have shown promise in the treatment of various solid tumors. In this study, the in vitro efficacy of MTX and PMX was compared in OS cell lines. MTX demonstrated a superior cytotoxic effect in comparison to PMX in all tested cell lines. Apoptosis assays revealed that both MTX and PMX induce apoptosis but MTX demonstrated superior efficacy. These in vitro results suggest that PMX as a single agent may not demonstrate improved efficacy compared to MTX in OS patients. Pediatr Blood Cancer 2008;50:905–908. © 2007 Wiley‐Liss, Inc.
NMR assignment of iso‐α‐acids from isomerised extracts of Humulus lupulus L. cones
Authors: Khatib Alfi , Wilson Erica G. , Kim Hye Kyong , Supardi Moses , Choi Young Hae , Verpoorte Robert 
Published: May 2007

AbstractIso‐α‐acids are known to contribute to the characteristic bitter taste of beer. Six iso‐α‐acids were isolated from a carbon dioxide extract of the cones of Humulus lupulus L. by centrifugal partition chromatography followed by separation through β‐cyclodextrin binding. This method overcame the low yield issue of most isolation procedures that results from the low stability of these compounds to light and oxygen. Their full identification was performed using one‐ and two‐dimensional NMR spectrometry, including 1H‐ and 13C‐NMR, 1H‐1H COSY, HMQC and HMBC and electrospray ionisation mass spectrometry. The results confirmed the structures of the isolated compounds as trans‐isocohumulone, cis‐isocohumulone, trans‐isohumulone, cis‐isohumulone, trans‐isoadhumulone and cis‐isoadhumulone. Epimers can be easily distinguished by observing the chemical shift differences of the H‐5, H‐1′″, H‐2′″ and C‐5 signals and the different splitting pattern of H‐5 and H‐2″. Copyright © 2007 John Wiley & Sons, Ltd.
Could ovarian choriocarcinoma be detected by maternal serum screening for Down syndrome?
Authors: Gauchez Anne‐Sophie , Dreux Sophie , Stéfani Laetitia , Mousseau Mireille , Jouk Pierre‐Simon , Muller Françoise 
Published: May 2007

AbstractThe incidence of ovarian malignancies during gestation ranges from 1 in 8000 to 1 in 20 000 deliveries. Ovarian malignancies that produce human chorionic gonadotropin (hCG) are limited to germ cell tumors, of which dysgerminoma is the most frequent (45%) malignant type encountered in pregnant patients, the others being ovarian choriocarcinoma and mixed germ cell tumors (Boulay and Podczaski, 1998). In women of childbearing age, it is hard to distinguish between metastatic choriocarcinoma on a complete mole and primary ovarian choriocarcinoma. Treatment is based on adnexectomy followed by chemotherapy. Given the extreme rarity of these tumors, the long‐term prognosis is difficult to establish. Had the diagnosis for our patient been made during pregnancy, the therapeutic approach would have been discussed in terms of gestational age. In the last trimester, we could have suggested cesarean section followed by adnexectomy, and then chemotherapy. In the second‐trimester, chemotherapy could have been discussed, although the fetal toxicity of cisplatin chemotherapy is not firmly defined (Ferrandina et al., 2005). This treatment is an alternative to termination of pregnancy. We retrospectively studied maternal serum biochemistry so as to assess the possibility of a diagnosis of ovarian choriocarcinoma at the time of maternal serum screening for Down syndrome. Copyright © 2007 John Wiley & Sons, Ltd.
Mechanism of a one‐step method for preparing silane grafting and cross‐linking polypropylene
Authors: Yang Shujing , Song Guojun , Zhao Yunguo , Yang Chao , She Xilin 
Published: May 2007

AbstractA high‐melt‐strength polypropylene (HMSPP) with partially cross‐linking, modified from a normal isotactic polypropylene (IPP), is prepared by a one‐step silane grafting and cross‐linking method in a twin‐screw reactive extruder. The melt grafting and cross‐linking of IPP is achieved by using vinyl unsaturated silane with long chain as a grafting monomer, benzoyl peroxide (BPO) as an initiator, styrene as a coagent, and a little water as a catalyst for cross‐linking. By analyzing the difference of the Fourier transformed infrared spectra between raw and modified PP, comparing the variety of the melt flow rate (MFR) and gel percentage between cured and uncured PP samples, and investigating the effect of catalyst on the MFR and gel percentage of modified PP, the partially cross‐linked polypropylene in the way of one‐step reactive extrusion has been verified. We put forward the reactive mechanism of one‐step method based on our experimental results. In this mechanism, the hydrolysis and condensation of silane occur first through the catalysis of water and a compound with two or more double‐bond is formed, which then the compound reacts with PP macroradicals to form the partially cross‐linked PP. POLYM. ENG. SCI., 47:1004–1008, 2007. © 2007 Society of Plastics Engineers
The rheological and physical properties of linear and branched polypropylene blends
Authors: McCallum Tara J. , Kontopoulou Marianna , Park Chul B. , Muliawan Edward B. , Hatzikiriakos Savvas G. 
Published: May 2007

AbstractThe rheological, thermal, and mechanical properties of blends consisting of a linear high melt flow rate polypropylene (PP) and two branched PPs are characterized in detail. Blends containing branched PPs display evidence of miscibility in the melt state and exhibit high melt elasticity together with significant strain hardening in extensional deformation while retaining good flow properties. Out of the two blend systems examined the blends containing linear and branched PPs with similar melt flow rates have better mechanical properties, higher crystallization temperatures, and higher crystallinities. POLYM. ENG. SCI., 47:1133–1140, 2007. © 2007 Society of Plastics Engineers
Synthesis, characterization, mechanical properties and biocompatibility of interpenetrating polymer network–super‐porous hydrogel containing sodium alginate
Authors: Yin Lichen , Fei Likun , Tang Cui , Yin Chunhua 
Published: May 2007

AbstractIn this investigation an interpenetrating polymer network–superporous hydrogel containing sodium alginate (IPN‐SPHAlg) was synthesized. The morphology of the polymer was characterized using scanning electron microscopy, light images and porosity, and the polymer was further examined by swelling ratio, mechanical strength and biocompatibility. The results indicated that the IPN‐SPHAlg possessed both large numbers of interconnected pores and an interpenetrating network. The swelling ratio of IPN‐SPHAlg was lower than that of the superporous hydrogel (SPH) and it decreased as the sodium alginate/monomer ratio increased. The IPN‐SPHAlg exhibited pH responsiveness and salt‐sensitive properties. Compared to SPH and SPH composites, the mechanical strength of IPN‐SPHAlg was significantly enhanced. Thiazolyl blue assay on AD293 cells, in situ lactate dehydrogenase assay and morphological study of rat intestine showed that the polymer induced no significant cell or mucosal damage. The fast swelling, good mechanical properties, pH sensitivity and biocompatibility of the IPN‐SPHAlg suggested it as a potential candidate in the field of drug‐delivery systems. Copyright © 2007 Society of Chemical Industry
Synthesis and characterization of novel π‐conjugated polymers with phosphole ring derivatives
Authors: Na Hai‐Sub , Morisaki Yasuhiro , Aiki Yasuhiro , Chujo Yoshiki 
Published: June 2007

AbstractNovel π‐conjugated polymers (8–10) were prepared by the palladium‐catalyzed Sonogashira coupling reaction of three kinds of phosphole‐ring‐containing monomers with 2,5‐dihexyloxyl‐1,4‐diethynylbenzene. The obtained polymers (8–10) were regioregulated with the 2,5‐substituted phosphole ring in the polymer main chain and characterized with 1H, 13C, and 31P NMR and FTIR. Polymers 8–10 were found to have an extended π‐conjugated system according to the results of UV–vis absorption spectra. In the fluorescence emission spectra of 8–10, moderate emission peaks were observed in the visible blue‐to‐green region. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2867–2875, 2007
Synthesis and photophysical properties of Rhodamine B dye‐bearing poly(isobutyl methacrylate‐co‐2,2,2‐trifluoroethyl methacrylate) as a temperature‐sensing polymer film
Authors: Obata Makoto , Morita Mako , Nakase Kayoko , Mitsuo Kazunori , Asai Keisuke , Hirohara Shiho , Yano Shigenobu 
Published: June 2007

AbstractTo develop a novel temperature‐sensitive paint, methacrylamide monomers bearing Rhodamine B dye (two regioisomers, 3a and 3b) were synthesized and polymerized with isobutyl methacrylate and 2,2,2‐trifluoroethyl methacrylate to afford Rhodamine B‐pendant polymers 4a and 4b. The methacrylamide monomers 3a and 3b showed photophysical properties almost identical with those of Rhodamine B. The temperature sensitivity of the luminescence intensity of 3a and 3b was also similar to that of Rhodamine B. The polymers 4a and 4b have excellent solubility in nonpolar organic solvents and are suitable for application as paint. Films of polymers 4a and 4b showed temperature‐dependent luminescence, which is applicable for temperature‐sensing. The temperature sensitivity of the film of 4a was estimated to be −0.37% °C−1, and was independent of pressure. The film of 4b showed higher temperature sensitivity, but its temperature sensitivity was slightly pressure‐dependent. Hence, polymer 4a is expected to be superior for practical use in paints having temperature‐sensing functionality. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2876–2885, 2007
Modular synthesis of ABC type block copolymers by “click” chemistry
Authors: Opsteen Joost A. , van Hest Jan C. M. 
Published: June 2007

AbstractHeterotelechelic polystyrene (PS), poly(tert‐butyl acrylate) (PtBA), and poly (methyl acrylate) (PMA), containing both azide and triisopropylsilyl (TIPS) protected acetylene end groups, were prepared in good control (Mw/Mn ≤ 1.24) by atom transfer radical polymerization (ATRP). The end groups were independently applied in two successive “click” reactions, that is: first the azide termini were functionalized and, after deprotection, the acetylene moieties were utilized for a second conjugation step. As a proof of concept, PS was consecutively functionalized with propargyl alcohol and azidoacetic acid, as confirmed by MALDI‐ToF MS. In addition, the same methodology was employed to modularly build up an ABC type triblock terpolymer. Size exclusion chromatography measurements demonstrated first coupling of PtBA to PS and, after the deprotection of the acetylene functionality on PS, connection of PMA, yielding a PMA‐b‐PS‐b‐PtBA triblock terpolymer. The reactions were driven to completion using a slight excess of azide functionalized polymers. Reduction of the residual azide groups into amines allowed easy removal of this excess of polymer by column chromatography. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2913–2924, 2007