bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fat suppressed MRI of articular cartilage with a spatial‐spectral excitation pulse
Authors: Hardy Peter A. , Recht Michael P. , Piraino David W. 
Published: March 2007

AbstractWe developed a three‐dimensional, gradient‐recalled‐echo imaging technique that incorporates a short‐duration spatial‐spectral excitation pulse from the family of binomial pulses. Binomial pulses of different orders were tested on phantoms and on normal volunteers to find the composite pulse that produced in the shortest duration the most reliable fat suppression. Composite pulses employing unipolar slice‐selective gradients with explicit rewinder gradients between each radiofrequency (RF) pulse were compared with composite RF pulses employing alternating‐polarity, slice‐select gradients. The advantage of the sequences using the unipolar gradients is improved fat suppression. Images of the knees of volunteers produced with the composite RF pulse have contrast between fat and articular cartilage equivalent to that on images created by the gradient‐recalled‐echo imaging technique employing a conventional chemsat pulse. The optimum RF pulse consisted of three amplitude‐ and phase‐modulated pulses combined with unipolar slice‐select gradients.
Locally focused MRI of interventions
Authors: Kuperman Vadim Y. , Nagle Scott K. , Levin David N. 
Published: March 2007

AbstractCertain interventional MR procedures would benefit from T2‐weighted imaging because of the sensitivity of T2‐weighted images to tissue damage and target lesion contrast. To acquire such images with reasonable temporal resolution, a single‐shot acquisition should be used because of the inherently long TR needed for T2 weighting. Unfortunately, most scanners require long readout times (eg, greater than 150 msec) and high bandwidths (eg, greater than 120 kHz) to perform conventional single‐shot imaging with high spatial resolution. The resulting images are thus degraded by unacceptable artifacts and noise levels. This study illustrates how to create locally focused MR images that have high spatial resolution in a region of interest and lower spatial resolution elsewhere in the image. Because these images can be created from sparse k‐space data, a scanner with modest gradients (eg, 10 mT/m maximal amplitude, 500 μsec minimal rise time) can acquire them after a single excitation with relatively short readout time and low bandwidth. This technique may make it practical to monitor interventions with T2‐weighted imaging. The method was illustrated by reconstructing dynamic changes, which were simulated experimentally by moving objects in the vicinity of a normal human head.
Single‐shot diffusion‐weighted RARE sequence: Application for temperature monitoring during hyperthermia session
Authors: II′yasov Kamil A. , Prof Jürgen Hennig 
Published: March 2007

AbstractA diffusion‐sensitive single‐shot RARE (rapid acquisition with relaxation enhancement) sequence was implemented on a 2T whole‐body MRI system. The sequence was optimized for diffusion‐based MR thermometry, both on a conventional whole‐body gradient system and on a high‐performance gradient insert. The use of spin‐echo versus stimulated‐echo diffusion weighting is discussed as a function of gradient performance. Diffusion‐based temperature mapping was used to observe the effect of the geometry of the antenna used for radiofrequency (RF) hyperthermia on the temperature distribution. Temperature changes of ±.5°C in gel and ±2°C in a muscle sample in vitro could be detected within 16 seconds (gel) or 1 minute (muscle) at a spatial resolution of 2 × 2 × 8 mm. Temperature changes in vivo were also observed on human muscle cooled with ice with comparable sensitivity for the measured apparent diffusion coefficient (ADC) values.
MRI monitoring of laser ablation using optical flow
Authors: Zientara Gary P. , Saiviroonporn Pairash , Morrison Paul R. , Fried Marvin P. , Hushek Stephen G. , Kikinis Ron , Jolesz Ferenc A. 
Published: March 2007

AbstractThe optical flow method is used for visualizing and quantifying the dynamics of tissue changes observed by MRI during thermal ablations. An approach was implemented for parallel two‐dimensional optical flow calculations including the replacement of spurious velocities. Velocity magnitude results were found to be accurate in low‐noise cases in tests using series of synthetic images. Optical flow results are presented from thermal ablation experiments utilizing a homogeneous polyacrylamide gel phantom and heterogeneous rabbit liver tissue in vivo, exhibiting heating and cooling with the accompanying quantitative characterization of the dilation and contraction of the thermally affected region. Results demonstrate that optical flow is capable of noninvasive real‐time monitoring and control of interstitial laser therapy (ILT).
Interactive MR‐guided percutaneous nephrostomy
Authors: Hagspiel Klaus D. , Kandarpa Krishna , Silverman Stuart G. 
Published: March 2007

AbstractOpen‐configuration MRI systems have been recently introduced and hold promise to allow the performance of a variety of minimally invasive procedures. Experience with MR‐guided catheter‐based luminal interventions is experimental to date. This is the first case of a successful percutaneous nephrostomy tube placement in a patient in an interventional MR system. The procedure was performed completely under MR guidance, and technical aspects are reviewed and compared with other, established techniques for percutaneous nephrostomy placement.
Subungual glomus tumor: Combined use of MRI and three‐dimensional contrast MR angiography
Authors: Boudghene Frank P. , Gouny Pierre , Tassart Marc , Callard Patrice , Breton Caroline Le , Vayssairat Michel 
Published: March 2007

AbstractWe describe a case of digital glomus tumor diagnosed by MRI and three‐dimensional contrast MR angiography (MRA). Images provided the formal definitive diagnosis and the precise localization of the tumor, guiding the necessary surgical resection. It is possible that noninvasive MRA could replace conventional arteriography for the evaluation of patients with clinical suspicion of glomus tumor.
Functional MRI of the lumbar spine in erect position in a superconducting open‐configuration MR system: Preliminary results
Authors: Zamani Amir A. , Moriarty Thomas , Hsu Liangge , Winalski Carl S. , Schaffer Jonathan L. , Isbister Holly , Schenck John F. , Rohling Kenneth W. , Jolesz Ferenc 
Published: March 2007

AbstractThe purpose of this study was to determine the feasibility of obtaining, and findings in, functional MRI of the lumbar spine in an erect position and with flexion and extension. Thirty subjects (including 5 volunteers) were imaged in a sitting position and while performing flexion and extension. The alternations in posterior disk margin, size of neural foramina, and central canal were evaluated. In addition, routine supine imaging was accomplished in 15 of these subjects. The foraminal size and posterior disk margins did not change appreciably from supine to upright position. With extension, there was an increased disk bulge in 27% of disks (40% of those with desiccation). Central canal size (50%) and foraminal size (27%) decreased with extension, especially at levels with disk desiccation. Images obtained with our open‐configuration MR unit were diagnostically adequate, although of inferior quality compared with those obtained with a conventional unit. Our preliminary results show the feasibility of obtaining diagnostic images of the erect lumbar spine with flexion and extension. The results are in agreement with those obtained with cadaveric studies. The utility of this method in diagnostic imaging of patients with low back pain remains to be determined.
Black‐blood MR angiography with grase: Measurement of flow‐induced signal attenuation
Authors: Yu Beverly C. , Jara Hernan , Melhem Elias R. , Caruthers Shelton D. , Yucel E. Kent 
Published: March 2007

AbstractWe investigated the feasibility of performing black‐blood MR angiography (MRA) with the gradient and spin‐echo (GRASE) pulse sequence. Phantom experiments and human testing were conducted, and the results were compared with those of turbo spin‐echo (TSE). We demonstrated that both techniques are able to produce signal suppression of flowing fluid to background level. With fewer radiofrequency (RF)‐refocusing pulses, GRASE pulse sequences could serve as an alternative black‐blood technique of reduced RF power exposure and shorter scan time. These relative advantages of GRASE may become useful when high‐resolution images are taken.
Simultaneous qualification and quantification of eight triterpenoids in Radix Achyranthis Bidentatae by high‐performance liquid chromatography with evaporative light scattering detection and mass spectrometric detection
Authors: Li Juan , Li Ping , Li Hui‐Jun , Song Yue , Bi Zhi‐Ming , Li Yan‐Jing 
Published: March 2007

AbstractAn HPLC with evaporative light scattering detection (ELSD) and ESI‐MS was established for the simultaneous determination of eight triterpenoids in Radix Achyranthis Bidentatae. The optimal chromatographic conditions were achieved on a Zorbax C18 column by linear gradient elution with 0.08% v/v aqueous formic acid and ACN as the mobile phase at the flow rate of 0.8 mL/min. Temperature for the detector drift tube was set at 101°C and the nitrogen flow rate was 2.8 L/min. The identities of the analytes were accomplished by comparing retention times and mass data with those of reference compounds. The validation of the method included tests of linearity, sensitivity, repeatability, recovery, and stability. All the calibration curves of the eight triterpenoids showed good linear regression (R2 >0.997) within the test ranges. The method provides desirable repeatability with overall intra‐ and interday variations of less than 4.9%. The obtained recoveries varied between 93.6 and 98.1% while the RSDs were below 3.9% (n = 3). The analysis results indicate that the content of investigated triterpenoids in Radix Achyranthis Bidentatae from different locations was greatly diverse, and the triterpenoids could be used as chemical markers for the discrimination of genuine and ungenuine crude drugs.
Efficient Improvement of Fluorescence Quantum Yield of Fluoreneethynylene‐Based Polymers by Introducing a Perfluoroalkylbenzene Unit to the Polymers
Authors: Zeng Danli , Chen Junwu , Chen Zhao , Zhu Weihong , He Jun , Yu Feng , Huang Hao , Wu Huanrong , Liu Chang , Ren Shijie , Du Junping , Sun Jing , Xu Erjian , Cao Amin , Fang Qiang 
Published: March 2007

AbstractIn comparison with poly(9,9‐dialkylfluorene)s widely used in organic optoelectronic devices, poly(9,9‐dialkylfluoreneethynylene)s (PFEs) have attracted less attention partly because of their poor fluorescence quantum yield (FQY) in the solid state. In order to improve the FQY, a 1,4‐bis(perfluorohexyl)benzene (BFB) unit was introduced to PFEs, and the results showed that the absolute FQY in the solid state was dependent on the mol‐% of the BFB unit in the copolymers. When mol‐% was 40 and 50%, respectively, the absolute FQY had greatly increased from 4.9% of PFE to 7.8 and 17.4% of the copolymers, respectively. For comparison, a 1,4‐dihexylbenzene (DHB) unit was also introduced to PFE, whereas the obtained copolymer showed the absolute FQY of 3.8%, suggesting that the DHB unit was not suitable for improvement of the FQY of PFEs. Electrochemically, the PFE containing BFB units showed lower reduction potential than that of PFE. All the fluorine‐containing polymers have good thermal stability.magnified image
Hydrogen Bonding‐Induced Transformation of Network Aggregates into Vesicles ‐ A Potential Method for the Preparation of Composite Vesicles
Authors: Zhang Jian Xiang , Li Xiao Dong , Yan Mei Qiu , Qiu Li Yan , Jin Yi , Zhu Kang Jie 
Published: March 2007

AbstractWhile network‐like assemblies are formed by amphiphilic polyphosphazenes with poly(N‐isopropylacrylamide) and ethyl tryptophan as side groups in aqueous solution, a significant morphology transformation is observed when small molecules that exhibit hydrogen‐bonding interactions with amphiphilic copolymers are introduced during the preparation of polymeric assemblies through a dialysis procedure. Depending on copolymer composition and the content of small molecules introduced, aggregates ranging from general vesicles, high‐genus vesicles, to well‐defined nanospheres can be prepared successfully as clearly evidenced by TEM observation, which suggests this procedure should be a novel approach to prepare composite vesicles.magnified image
Synthesis of Chain‐End Functionalized Polyolefins with a Bis(phenoxy imine) Titanium Catalyst
Authors: Makio Haruyuki , Fujita Terunori 
Published: March 2007

AbstractPolyethylenes and highly syndiotactic poly(propylene)s possessing chain end hydroxyl groups were synthesized by living polymerizations using L2TiCl2 [1, L: C6F5NCH(2OC6H33tBu)]/MAO and functionalized α‐olefins, H2CCH(CH2)nY [2; YOAlMe2, n = 4 (2a); YOSiMe3, n = 9 (2b)]. Because the primary insertion of 2 to a cationic species L2Ti+Me (3) derived from 1/MAO is much faster than the successive secondary insertion of 2, addition of an equimolar amount of 2 to 3 resulted in the quantitative formation of L2Ti+CH2CH(Me)(CH2)nY [4; YOAlMe2, n = 4 (4a); YOSiMe3, n = 9 (4b)]. These cationic species 4 served as functionalized initiators for the living polymerization of both ethylene and propylene and afforded polyolefins having extremely narrow molecular weight distributions and a hydroxyl group at the initiating chain end. The terminating chain end of the syndiotactic poly(propylene)s was also functionalized by adding an excess amount of 2b as a chain end capping agent to the living L2Ti–polymeryl species. Due to much slower insertion of the second molecule of 2b relative to the first one, the obtained polymers were end capped quantitatively by a single molecule of 2b. Telechelic syndiotactic poly(propylene)s were successfully synthesized through a living polymerization initiated by 4b and an end capping using 2b.magnified image
Orofacial automatisms induced by acute withdrawal from high‐dose midazolam mimicking nonconvulsive status epilepticus in a child
Authors: Epstein David , Difazio Marc 
Published: March 2007

AbstractNonconvulsive Status Epilepticus (NCSE) is not uncommon in children, and can be challenging to diagnose and treat. Etiologies vary widely and include infection, trauma and acute withdrawal from medications such as anticonvulsants. We report a child who experienced orofacial dyskinesias concerning for NCSE after withdrawal from high dose benzodiazepines andopiates. Automonic signs typically associated with sedative withdrawal were absent and treatment with benzodiazepines did not improve his symptoms. Diagnostic testing was negative, including electroencephalogram, and resolution was complete within five days. Our case demonstrates the orofacial dyskinesias that may occur during sedative medication withdrawal, and highlights potential confusion with non‐convulsive status epilepticus. © 2007 Movement Disorder Society
Cognitive‐behavioral therapy for depression in Parkinson's disease: A pilot study
Authors: Dobkin Roseanne DeFronzo , Allen Lesley A. , Menza Matthew 
Published: March 2007

AbstractThe present study was conducted to examine the feasibility and effect of an individual cognitive‐behavioral treatment (CBT) for depression that was modified to meet the unique needs of the PD patient and incorporated a separate social support intervention for caregivers. Fifteen PD patients with Major Depressive Disorder participated in the study with a caregiver. Patients received 10–14 sessions of modified individual CBT. Caregivers attended 3–4 psychoeducational sessions, occurring separately from the patients treatment sessions, which focused on strategies for offering appropriate support, and ways to respond to the patients' negative thoughts in a targeted manner. Patients experienced a significant reduction in depressive symptoms and negative cognitions, and an increased perception of social support over the course of treatment. Gains were maintained at 1‐month follow‐up. In conclusion, individual CBT, when modified appropriately, may be a feasible and effective option for PD depression. Larger, randomized controlled trials are needed to further evaluate the efficacy of this intervention and to identify specific mechanisms of change. © 2007 Movement Disorder Society
Global existence and blow‐up of the solutions for the multidimensional generalized Boussinesq equation
Authors: Wang Ying , Mu Chunlai 
Published: March 2007

AbstractIn this paper, the existence and the uniqueness of the global solution for the Cauchy problem of the multidimensional generalized Boussinesq equation are obtained. Furthermore, the blow‐up of the solution for the Cauchy problem of the generalized Boussinesq equation is proved. Copyright © 2007 John Wiley & Sons, Ltd.
Fredholm properties of multivariate refinement equations
Authors: Didenko Victor D. 
Published: March 2007

AbstractThe solvability of multivariate refinement equations in the Hilbert space L2(ℝs) is studied. It is shown that the set of all L2‐solutions of such equations either consists of the trivial solution only or it contains a subspace isomorphic to a space L∞(SM) where SM is a subset of ℝs with a positive Lebesgue measure. Therefore, the corresponding multivariate refinement operator is Fredholm if and only if it is invertible. Copyright © 2007 John Wiley & Sons, Ltd.
A detailed analysis of localized J‐difference GABA editing: theoretical and experimental study at 4 T
Authors: Kaiser L. G. , Young K. , Meyerhoff D. J. , Mueller S. G. , Matson G. B. 
Published: March 2007

AbstractThe problem of low signal‐to‐noise ratio for γ‐aminobutyric acid (GABA) in vivo is exacerbated by inefficient detection schemes and non‐optimal experimental parameters. To analyze the mechanisms for GABA signal loss of a MEGA‐PRESS J‐difference sequence at 4 T, numerical simulations were performed ranging from ideal to realistic experimental implementation, including volume selection and experimental radio frequency (RF) pulse shapes with a macromolecular minimization scheme. The simulations were found to be in good agreement with phantom and in vivo data from human brain. The overall GABA signal intensity for the simulations with realistic conditions for the MEGA‐PRESS difference spectrum was calculated to be almost half of the signal simulated under ideal conditions (∼43% signal loss). In contrast, creatine was reduced significantly less then GABA (∼19% signal loss). The ‘four‐compartment’ distribution due to J‐coupling in the PRESS‐based localization was one of the most significant sources of GABA signal loss, in addition to imperfect RF profiles for volume selection and editing. An alternative strategy that reduces signal loss due to the four‐compartment distribution is suggested. In summary, a detailed analysis of J‐difference editing is provided with estimates of the relative amounts of GABA signal losses due to various mechanisms. The numerical simulations presented in this study should facilitate both implementation of the more efficient acquisition and quantification process of J‐coupled systems. Copyright © 2007 John Wiley & Sons, Ltd.
Dimensioning and optimization of push‐to‐talk over cellular server
Authors: Alam M. T. , Wu Z. D. 
Published: March 2007

AbstractThe PoC (push‐to‐talk over cellular) application allows point‐to‐point or point‐to‐multipoint voice communication between mobile network users. The related work over PoC focuses on the performance analysis only and is ignorant about dimensioning a PoC controller to optimize revenue for service providers. In this paper, we dimension a PoC service with the assumption that the network grade of service is provided. The on‐demand sessions should have access priority over pre‐established sessions. A PoC controller should be able to terminate a PoC session based on an optimal timer. Moreover, the number of simultaneous session initiations by a PoC client is also a configurable parameter. We derived relations to provide access priority to special PoC sessions based on available transmit/receive units (TRU) and threshold level. Load sharing expressions are reported for a PoC controller using the Lagrange multiplier technique. A simple relation to control the PoC session timer is proposed. Finally, the derivation of maximum number of allowable simultaneous sessions is depicted using two‐state Markov models. Numerical results have been computed with the corresponding derivation to provide a useful insight into the system behaviour. A PoC service can benefit from these optimal values of our work during the busy hour. Copyright © 2007 John Wiley & Sons, Ltd.
Urine reagent stick protein determination: Utility in individuals with diabetes mellitus
Authors: Bloomgarden ZT 
Published: March 2007

AbstractThe study assessed the sensitivity and specificity of reagent stick urine analysis as a measure of albuminuria in individuals with diabetes mellitus. Using an automated method, reagent stick urine analysis for protein showed sensitivity and specificity both of 0.85 for detection of microalbuminuria (>25μg/ml). Visual reading of reagent strip protein showed similar sensitivity, but specificity was less than 0.6. In conclusion, the standard urine analysis test may offer specificity and sensitivity comparable to that of available microalbumin strips.
Comparison of the degradation of polycaprolactone and polycaprolactone–(β‐tricalcium phosphate) scaffolds in alkaline medium
Authors: Lam Christopher XF , Teoh Swee Hin , Hutmacher Dietmar W 
Published: March 2007

AbstractThe design and fabrication of scaffolds and biodegradable devices using slow‐degrading polymers and composites (degradation/resorption > 2 years) involve the necessity for long‐term in vitro and in vivo studies. If multiple designs and materials need to be tested, then this would use much time and financial resources. Accelerated degradation systems aim to achieve comparable degradation profiles within a shorter period of time. This investigation considers the hydrolytic degradation of polycaprolactone (PCL) and PCL–calcium phosphate (CaP) scaffolds in 5 mol L−1 NaOH at 37 °C. The scaffolds degrade via surface erosion, which proceeds in a consistent and predictable manner. The hydrolytic degradation of PCL‐based scaffolds alone is slow, governed by their high molecular weights, crystallinity, hydrophobicity, surface‐to‐volume ratio and porosity. The incorporation of CaP significantly increases the degradation rate. Copyright © 2007 Society of Chemical Industry
Modulus and damping of polymers in relation to their structure
Authors: Heijboer J. 
Published: March 2007

AbstractFor most applications of polymer products, the modulus or stiffness, i.e. resistance to deformation under load, is of prime importance. The mechanical losses or damping reveal molecular movements of small groups of atoms, which movements can be significant for the impact strength.This review illustrates the effect of crosslinking, polarity, and steric features of both side‐groups and main molecular chain on both shear modulus and damping as functions of temperature.The examples are mainly taken from commercial or recently developed polymers.It is concluded that the most promising way of increasing the softening temperature of thermoplastics is to introduce rings into the main molecular chain.