bluuebunny/crossref_metadata_2025_split huggingface dataset:
MRI using radiofrequency magnetic field phase gradients
Authors: Sharp Jonathan C. , King Scott B. 
Published: November 2009

AbstractConventionally, MR images are formed by applying gradients to the main static magnetic field (B0). However, the B0 gradient equipment is expensive, power‐hungry, complex, and noisy and can induce eddy currents in nearby conducting structures, including the patient. Here, we describe a new silent, B0 gradient‐free MRI principle, Transmit Array Spatial Encoding (TRASE), based on phase gradients of the radio‐frequency (RF) field. RF phase gradients offer a new method of k‐space traversal. Echo trains using at least two different RF phase gradients allow spin phase to accumulate, causing k‐space traversal. Two such RF fields provide one‐dimensional imaging and three are sufficient for two‐dimensional imaging. Since TRASE is a k‐space method, analogues of many conventional pulse sequences are possible. Experimental results demonstrate one‐dimensional and two‐dimensional RF MRI and slice selection using a single‐channel, transmit/receive, 0.2 T, permanent magnet, human MR system. The experimentally demonstrated spatial resolution is much higher than that provided by RF receive coil array sensitivity encoding alone but lower than generally achievable with B0 gradients. Potential applications are those in which one or more of the features of simplified equipment, lower costs, silent MRI, or the different physics of the image formation process are particularly advantageous. Magn Reson Med, 2010. © 2009 Wiley‐Liss, Inc.
A multislice gradient echo pulse sequence for CEST imaging
Authors: Dixon W. Thomas , Hancu Ileana , Ratnakar S. James , Sherry A. Dean , Lenkinski Robert E. , Alsop David C. 
Published: November 2009

AbstractChemical exchange–dependent saturation transfer and paramagnetic chemical exchange–dependent saturation transfer are agent‐mediated contrast mechanisms that depend on saturating spins at the resonant frequency of the exchangeable protons on the agent, thereby indirectly saturating the bulk water. In general, longer saturating pulses produce stronger chemical and paramagnetic exchange–dependent saturation transfer effects, with returns diminishing for pulses longer than T1. This could make imaging slow, so one approach to chemical exchange–dependent saturation transfer imaging has been to follow a long, frequency‐selective saturation period by a fast imaging method. A new approach is to insert a short frequency‐selective saturation pulse before each spatially selective observation pulse in a standard, two‐dimensional, gradient‐echo pulse sequence. Being much less than T1 apart, the saturation pulses have a cumulative effect. Interleaved, multislice imaging is straightforward. Observation pulses directed at one slice did not produce observable, unintended chemical exchange–dependent saturation transfer effects in another slice. Pulse repetition time and signal‐to noise ratio increase in the normal way as more slices are imaged simultaneously. Magn Reson Med, 2010. © 2009 Wiley‐Liss, Inc.
Motion correction using an enhanced floating navigator and GRAPPA operations
Authors: Lin Wei , Huang Feng , Börnert Peter , Li Yu , Reykowski Arne 
Published: November 2009

AbstractA method for motion correction in multicoil imaging applications, involving both data collection and reconstruction, is presented. The floating navigator method, which acquires a readout line off center in the phase‐encoding direction, is expanded to detect translation/rotation and inconsistent motion. This is done by comparing floating navigator data with a reference k‐space region surrounding the floating navigator line, using a correlation measure. The technique of generalized autocalibrating partially parallel acquisition is further developed to correct for a fully sampled, motion‐corrupted dataset. The flexibility of generalized autocalibrating partially parallel acquisition kernels is exploited by extrapolating readout lines to fill in missing “pie slices” of k‐space caused by rotational motion and regenerating full k‐space data from multiple interleaved datasets, facilitating subsequent rigid‐body motion correction or proper weighting of inconsistent data (e.g., with through‐plane and nonrigid motion). Phantom and in vivo imaging experiments with turbo spin‐echo sequence demonstrate the correction of severe motion artifacts. Magn Reson Med, 2010. © 2009 Wiley‐Liss, Inc.
Quantification of T2 in the abdomen at 3.0 T using a T2‐prepared balanced turbo field echo sequence
Authors: Hoad Caroline L. , Cox Eleanor F. , Gowland Penny A. 
Published: November 2009

AbstractThe T2‐prepared balanced turbo field echo sequence has been used to measure T2 in phantoms and in vivo in the abdomen with low sensitivity to radiofrequency pulse errors. The effects of noise, errors in the pulse flip angles, and off resonance effects on the results have been simulated. It was found from simulations that for normal conditions, including the flip angle in the fit improved the systematic errors due to radiofrequency pulse errors and noise in the results to less than 1% without significantly increasing the random errors. For a 0.3% noise level, the standard deviation in the measured T2 was approximately 0.003 ms. Off‐resonance effects had a minimal effect on the measured T2 value. The T2 at 3.0 T of various abdominal organs was measured, in particular the liver (31 ± 6 ms), spleen (54 ± 15 ms), kidney cortex (76 ± 6 ms), kidney medulla (61 ± 8 ms), and pancreas (42 ± 20 ms). Magn Reson Med, 2010. © 2009 Wiley‐Liss, Inc.
Change in the proton T1 of fat and water in mixture
Authors: Hu Houchun H. , Nayak Krishna S. 
Published: November 2009

AbstractThis work describes observed changes in the proton T1 relaxation time of both water and lipid when they are in relatively homogeneous mixtures. Results obtained from vegetable oil–water emulsions, pork kidney and lard mixtures, and excised samples of white and brown adipose tissues are presented to demonstrate this change in T1 as a function of mixture fat fraction. As an initial proof of concept, a simpler acetone‐water experiment was performed to take advantage of complete miscibility between acetone and water and both components' single chemical shift peaks. Single‐voxel MR spectroscopy was used to measure the T1 of predominant methylene spins in fat and the T1 of water spins in each setup. In the vegetable oil–water emulsions, the T1 of fat varied by as much as 3‐fold when water was the dominant mixture component. The T1 of pure lard increased by 170 msec (+37%) when it was blended with lean kidney tissue in a 16% fatty mixture. The fat T1 of lipid‐rich white adipose tissue was 312 msec. In contrast, the fat T1 of leaner brown adipose tissue (fat fraction 53%) was 460 msec. A change in the water T1 from that of pure water was also observed in the experiments. Magn Reson Med, 2010. © 2009 Wiley‐Liss, Inc.
Evidence of gender‐specific motor templates to resist valgus loading at the knee
Authors: Cammarata Martha L. , Dhaher Yasin Y. 
Published: November 2009

AbstractGender differences in neuromuscular control of the lower extremity may contribute to increased injury risk in females, but the neurophysiological mechanisms underlying these differences remain unclear. In this study, we sought to explore the effect of gender on volitional and reflex neuromuscular responses to a rapid valgus perturbation at the knee applied under “intervene” and “do not intervene” conditions. Multiple 7° ramp‐and‐hold valgus perturbations were applied at the neutrally extended knee of 12 male and 12 female healthy subjects, while surface electromyography over the quadriceps and hamstrings recorded the neuromuscular response. Volitional responses did not vary between groups, perhaps reflecting the relative novelty of the loading direction. However, reflex responses observed under the “do not intervene” paradigm did vary by gender. Males demonstrated much more frequent and consistent reflex muscle activation than females. Moreover, muscle activation patterns were gender‐specific. Diminished responses in female subjects may indicate that the position‐based valgus perturbation did not produce the necessary mechanical stimulus to elicit reflexes. These gender differences in reflex control of the knee provide new insight into the control of frontal‐plane knee joint movement and loading and may elucidate the neuromechanical underpinnings associated with neuromuscular control. Muscle Nerve, 2010
Redetermination of the optimal stimulation intensity modifies resting H‐reflex recovery after a sustained moderate‐intensity muscle contraction
Authors: Rupp Thomas , Girard Olivier , Perrey Stéphane 
Published: November 2009

AbstractThis study aimed to determine whether the time‐course of maximal resting H‐reflex amplitude (Hmax) recovery after a prolonged moderate‐intensity muscle contraction differs according to the optimal stimulation intensity used (predetermined vs. readjusted). Thirteen males performed a sustained isometric plantar flexion at 40% of their maximal voluntary contraction torque output until exhaustion. Hmax of the soleus muscle was recorded before and 2, 6, 10, and 14 min after the end of the contraction, then normalized by the respective maximal M‐wave to form the Hmax/Mmax ratio. During recovery, pre‐ and redetermined optimal stimulation intensities (mini‐recruitment curve drawn before each recovery measurement) were applied randomly to measure Hmax. When using redetermined stimulation intensities, normalized H‐reflex values were systematically greater (+11, +16, +15, and +15% after 2‐, 6‐, 10‐, and 14‐min recovery periods, respectively) than those obtained with the predetermined intensity. Keeping the stimulation intensity constant to evoke Hmax after a sustained muscle contraction can underestimate the H‐reflex facilitation occurring after exhaustive exercise. It is therefore more appropriate to redefine the optimal stimulation intensity to evoke Hmax (using mini‐recruitment curves) when the purpose is to analyze spinal modulation during the recovery phase. Muscle Nerve, 2010
Schwann cells as a source of insulin‐like growth factor‐1 for extraocular muscles
Authors: Feng Chengyuan , Von Bartheld Christopher S. 
Published: November 2009

AbstractPrecise force regulation is fundamentally important for extraocular muscle (EOM) function. Insulin‐like growth factor‐1 (IGF‐1) plays a major role in EOM force regulation, but the source of endogenous IGF‐1 is unclear. Multiple IGF‐1 sources may supply EOMs, including: the EOM itself; the systemic circulation; innervating motoneurons; and Schwann cells within nerves. IGF‐1 expression was measured in chicken during oculomotor system maturation by using real‐time polymerase chain reaction (PCR). Accumulation of radiolabeled IGF‐1 in EOMs was compared after either injection into the vascular circulation or into the trochlear nerve. Schwann cells were the most prominent IGF‐1 source. A microtubule‐dependent mechanism exists to anterogradely transport IGF‐1 to EOMs. EOMs were significantly more efficient in extracting IGF‐1 from the nerve than from the systemic circulation. Therefore, Schwann cells are the most prominent and potentially the most important source of IGF‐1 for EOMs. These findings may contribute to a better understanding of EOM force regulation and its failure in strabismus. Muscle Nerve, 2010
Diffuse large B‐cell lymphoma presenting as piriformis syndrome
Authors: Ye Byoung Seok , Sunwoo Il Nam , Suh Bum Chun , Park Jong‐Pil , Shim Dong‐Suk , Kim Seung Min 
Published: November 2009

AbstractPiriformis syndrome (PS) is a rare condition characterized by pain and paresthesia of the buttock, often radiating to the posterior thigh. A patient with sciatica that was clinically suspicious for PS, underwent diagnostic work‐up. A diagnosis of diffuse large B‐cell lymphoma with neurolymphomatosis (NL) was made. To our knowledge, this is the first report of NL presenting as PS. NL is a possible cause of secondary PS. Muscle Nerve, 2010
Acute‐onset chronic inflammatory demyelinating polyneuropathy with cranial nerve involvement, dysautonomia, respiratory failure, and autoantibodies
Authors: Hantson Philippe , Kevers Luc , Fabien Nicole , Van Den Bergh Peter 
Published: November 2009

AbstractWe examined a 27‐year‐old woman who developed rapidly progressive quadriplegia and acute respiratory failure that required mechanical ventilation in the intensive care unit. It was unclear whether this was a presentation of Guillain–Barré syndrome (GBS) or acute‐onset chronic inflammatory demyelinating polyradiculoneuropathy (A‐CIDP). Remarkable features included multiple cranial nerve involvement, respiratory failure, dysautonomia, and skin manifestations. Several autoantibodies were elevated, including antinuclear (ANA), anticardiolipin (aCL), thyroid, and calcium‐sensing receptor (CaSR) autoantibodies. The patient was initially diagnosed with GBS and treated with intravenous immunoglobulin (IVIg). After almost complete recovery, relapse with quadriplegia and respiratory failure was observed 12 weeks after motor symptom onset. She then received IVIg and steroid pulse therapy followed by maintenance oral methylprednisolone and plasma exchange. She recovered completely 4 months after the relapse. The further clinical and serological course was consistent with systemic lupus erythematosus (SLE)‐associated CIDP. Herein we evaluate the association between A‐CIDP and some biological markers of autoimmunity. Muscle Nerve, 2010
A Patient with neurofibromatosis type 1 and Charcot–Marie–Tooth disease type 1B
Authors: Lancaster Eric , Elman Lauren B. , Scherer Steven S. 
Published: November 2009

AbstractWe describe a patient with both neurofibromatosis type 1 and Charcot–Marie–Tooth disease type 1B. Although one might expect an overwhelming tumor burden due to the combination of these two disorders, the two mutations did not appear to interact. Muscle Nerve 41: 555–558, 2010
Ocular myasthenia gravis in a senior population: Diagnosis, therapy, and prognosis
Authors: Allen Jeffrey A. , Scala Stephanie , Jones H. Royden 
Published: November 2009

AbstractThe objectives of this study were (I) to explore the prognosis of ocular myasthenia gravis (OMG) in patients with onset at age 70 years and above (i.e. senior persons); (2) to identify predictors of secondary generalization in this age group; and 3) to address the effects of immunotherapy on this population of patients. We performed a retrospective analysis of 39 patients with myasthenia gravis who presented with only ocular signs and symptoms after age 70 years. Generalized myasthenia gravis (GMG) developed in 12 OMG patients (31%). None of the GMG patients required ventilator assistance or a feeding tube. Of the 12 ocular patients progressing to GMG, only one (8%) received immunotherapy prior to generalization. Of those OMG patients who did not progress to GMG, 52% received immunomodulatory therapy. Our senior OMG patients had a prognosis comparable with those of the published data for younger individuals. Although the presence of increased acetylceholine receptor antibody titers and occasionally abnormal repetitive nerve stimulation were useful tools to diagnose OMG, no test was predictive of later generalization. Senior onset OMG patients who received immunotherapy less frequently developed GMG than those not so treated. Muscle Nerve, 2010
Monotonic and cyclic modeling of interface between geotextile and gravelly soil
Authors: Zhang Ga , Wang Liping , Zhang Jian‐Min 
Published: November 2009

AbstractThis paper describes a modified elasto‐plasticity damage model to capture monotonic and cyclic behavior of the interface between a geotextile and gravelly soil. New damage variable and shear strength criterion are introduced on the basis of test observations. The formulations of the modified model are obtained by extending those of the original interface model. The model parameters with physical meaning are easily determined from a group of cyclic shear tests and a confining compression test. The model predictions are compared with the results of a series of direct shear tests and large‐scale pullout tests. The comparison results demonstrate that the model accurately describes the monotonic and cyclic stress–strain relationship of the interface between a geotextile and gravelly soil while capturing new characteristics: (1) the strength that is nonlinearly dependent on the normal stress; (2) significant shear strain‐softening; (3) the comprehensive volumetric strain response with dependency on the shear direction; and (4) the evolution of behavior associated with the changes in the physical state that includes the geotextile damage. This model is used in a finite element analysis of pullout tests, indicating that the tensile modulus of a geotextile has a significant effect on the response of the geotextile–gravel system. Copyright © 2009 John Wiley & Sons, Ltd.
Characterizing user‐level network virtualization: performance, overheads and limits
Authors: Tsugawa Mauricio , Fortes José A. B. 
Published: November 2009

AbstractConnectivity limitations in the current Internet have motivated the development of many overlay networking technologies that enable applications to transparently overcome such limitations. For easy development and deployment, overlay networks are typically implemented via a user‐level network virtualization software layer, often using high‐level languages. Existing solutions report performance that can keep up with slow wide‐area links—however, the question remains as to how overlay networks perform on new high‐speed Internet connections. This paper characterizes the performance of user‐level packet processing, which is at the core of most overlay networks implementations. To this end, building blocks of packet‐processing software are identified and characterized, and performance of IP forwarders developed in C and Java are compared through extensive measurements. Factors that affect the performance of overlay networks and limitations of existing solutions are characterized, providing insights on possible improvements. Experimental results show the following: to achieve maximum throughput, only a few microseconds (2–5) can be spent in virtual network processing; processing of small packets can limit TCP throughput; and overlays need to be carefully architected as encapsulation overheads can be substantial. Copyright © 2009 John Wiley & Sons, Ltd.
Using virtual topologies to manage inter‐domain QoS in next‐generation networks
Authors: Freitas Ricardo B. , de Paula Luciano B. , Madeira Edmundo , Verdi Fabio L. 
Published: November 2009

AbstractRecently, several computer fields have turned to virtualization as a way to simplify complex problems. In this context, the Virtual Topology Service (VTS) was created to manage the advertisement and acquisition of virtual topologies (abstractions of the network status of a domain) and their use in inter‐domain resource reservation to provide end‐to‐end quality of service (QoS). As an effort to create new network architectures which could attend current requirements like mobility and context‐aware applications and support autonomous, heterogeneous and mobile domains next‐generation networks (NGNs) emerged, with Ambient Networks (AN) as one of its instances. With an ever increasing multitude of online applications, end‐to‐end QoS has become increasingly important, especially for media and real‐time uses. In this context, in order to better manage inter‐domain QoS in these new networks, better coping with mobile nodes and domains, this work presents a new design and implementation of the VTS, adapted to the AN environment. The new VTS stores resource reservation information to enable the reuse of these reservations when re‐establishing QoS after a node/domain movement. This implementation was tested on a real NGN prototype and showed considerable time saving when compared to QoS re‐establishment without reusing the reservations. Copyright © 2009 John Wiley & Sons, Ltd.
Depression in family caregivers of elders: A theoretical model of caregiver burden, sociotropy, and autonomy
Authors: Clark Michele C. , Diamond Pamela M. 
Published: November 2009

AbstractTo test the diathesis‐stress model for family caregivers, two structural equation models were developed to explain depression measured by the Center for Epidemiologic Studies Depression Scale. A cross‐sectional convenience sample of 112 caregivers completed questionnaires to measure burden, personality traits, dysfunctional attitudes, and depression. The final model included direct paths from caregiver burden to autonomy and sociotropy, and indirect paths from burden to depression through sociotropy and autonomy. The final model fit adequately (χ2 [224, N = 112] = 308.60, p < .00; CFI = .951; RMSEA = .058). Levels of burden influenced caregiver depression scores. One pathway to depression was though the personality traits of sociotropy and autonomy; both had a larger influence on depression scores than burden alone. © 2009 Wiley Periodicals, Inc. Res Nurs Health 33:20–34, 2010
Binary and ternary blends of high‐density polyethylene with poly(ethylene terephthalate) and polystyrene based on recycled materials
Authors: Razavi S. , Shojaei A. , Bagheri R. 
Published: November 2009

AbstractBinary blends of recycled high‐density polyethylene (R‐HDPE) with poly(ethylene terephthalate) (R‐PET) and recycled polystyrene (R‐PS), as well as the ternary blends, i.e. R‐HDPE/R‐PET/R‐PS, with varying amounts of the constituents were prepared by twin screw extruder. The mechanical, rheological, thermal, and scanning electron microscopy (SEM) analyses were utilized to characterize the samples. The results revealed that both R‐HDPE/R‐PET and R‐HDPE/R‐PS blends show phase inversion but at different compositions. The R‐PET was found to have much higher influence on the properties enhancement of the R‐HDPE compared to R‐PS, but at the phase inverted situation, a significant loss in the tensile strength of R‐HDPE/R‐PET blend was observed due to the weak interaction at this morphological state. However, the ternary blends with higher loading of second phase, namely greater than 50 wt% of R‐PET+R‐PS, demonstrated better mechanical properties than the binary blends with the same content of either R‐PET or R‐PS. Copyright © 2009 John Wiley & Sons, Ltd.
Vapor phase polymerization of 3,4‐ethylenedioxythiophene on flexible substrate and its application on heat generation
Authors: Yang Xiaoming , Shang Songmin , Li Liang , Tao Xiao‐Ming , Yan Feng 
Published: November 2009

AbstractAn oxidative chemical vapor phase polymerization process is applied to coat flexible polyethylene terephthalate (PET) fabrics with a uniform poly(3,4‐ethylenedioxythiophene) (PEDOT) film. This vapor phase polymerization method is a solventfree technique, which could yield a low resistance in the PEDOT‐coated PET fabric. The resistance as low as 52 Ω square−1 is achieved. The polymerization conditions, such as the concentration of oxidant, reaction time, and temperature, have been systematically investigated. The coated fabric samples exhibit an increase in temperature when subjected to a fixed DC voltage. This result indicates a potential application of these PEDOT‐coated fabrics as electric heating materials. Copyright © 2009 John Wiley & Sons, Ltd.