bluuebunny/crossref_metadata_2025 huggingface dataset:
Diffusion‐weighted radial fast spin‐echo for high‐resolution diffusion tensor imaging at 3T
Authors: Sarlls Joelle E. , Pierpaoli Carlo
Published: July 2008

There is a need for an imaging sequence that can provide high‐resolution diffusion tensor images at 3T near air–tissue interfaces. By employing a radial fast spin‐echo (FSE) collection in conjunction with magnitude filtered back‐projection reconstruction, high‐resolution diffusion‐weighted images can be produced without susceptibility artifacts. However, violation of the Carr‐Purcell‐Meiboom‐Gill (CPMG) condition of diffusion prepared magnetization is a prominent problem for FSE trains that is magnified at higher fields. The unique aspect of violating the CPMG condition in trajectories that oversample the center of k‐space and the implications for choosing the solution are examined. For collecting diffusion‐weighted radial‐FSE data at 3T we propose mixed‐CPMG phase cycling of RF refocusing pulses combined with a 300% wider refocusing than excitation slice. It is shown that this approach produces accurate diffusion values in a phantom, and can be used to collect undistorted, high‐resolution diffusion tensor images of the human brain. Magn Reson Med 60:270–276, 2008. © 2008 Wiley‐Liss, Inc.
DWI of the spinal cord with reduced FOV single‐shot EPI
Authors: Saritas Emine Ulku , Cunningham Charles H. , Lee Jin Hyung , Han Eric T. , Nishimura Dwight G.
Published: July 2008

Single‐shot echo‐planar imaging (ss‐EPI) has not been used widely for diffusion‐weighted imaging (DWI) of the spinal cord, because of the magnetic field inhomogeneities around the spine, the small cross‐sectional size of the spinal cord, and the increased motion in that area due to breathing, swallowing, and cerebrospinal fluid (CSF) pulsation. These result in artifacts with the usually long readout duration of the ss‐EPI method. Reduced field‐of‐view (FOV) methods decrease the required readout duration for ss‐EPI, thereby enabling its practical application to imaging of the spine. In this work, a reduced FOV single‐shot diffusion‐weighted echo‐planar imaging (ss‐DWEPI) method is proposed, in which a 2D spatially selective echo‐planar RF excitation pulse and a 180° refocusing pulse reduce the FOV in the phase‐encode (PE) direction, while suppressing the signal from fat simultaneously. With this method, multi slice images with higher in‐plane resolutions (0.94 × 0.94 mm2 for sagittal and 0.62 × 0.62 mm2 for axial images) are achieved at 1.5 T, without the need for a longer readout. Magn Reson Med 60:468–473, 2008. © 2008 Wiley‐Liss, Inc.
Zigzag sampling for improved parallel imaging
Authors: Breuer Felix A. , Moriguchi Hisamoto , Seiberlich Nicole , Blaimer Martin , Jakob Peter M. , Duerk Jeffrey L. , Griswold Mark A.
Published: July 2008

Conventional Cartesian parallel MRI methods are limited to the sensitivity variations provided by the underlying receiver coil array in the dimension in which the data reduction is carried out, namely, the phase‐encoding directions. However, in this work an acquisition strategy is presented that takes advantage of sensitivity variations in the readout direction, thus improving the parallel imaging reconstruction process. This is achieved by employing rapidly oscillating phase‐encoding gradients during the actual readout. The benefit of this approach is demonstrated in vivo using various zigzag‐shaped gradient trajectory designs. It is shown that zigzag type sampling, in analogy to CAIPIRINHA, modifies the appearance of aliasing in 2D and 3D imaging, thereby utilizing additional sensitivity variations in the readout direction directly resulting in improved parallel imaging reconstruction performance. Magn Reson Med 60:474–478, 2008. © 2008 Wiley‐Liss, Inc.
A general framework for experiment design in diffusion MRI and its application in measuring direct tissue‐microstructure features
Authors: Alexander Daniel C.
Published: July 2008

This article introduces a new and general framework for optimizing the experiment design for diffusion MRI of samples with unknown orientation. An illustration then uses the framework to study the feasibility of measuring direct features of brain‐tissue microstructure in vivo. The study investigates the accuracy and precision with which we can estimate potentially important new biomarkers such as axon density and radius in white matter. Simulation experiments use a simple model of white matter based on CHARMED (composite hindered and restricted model of diffusion). The optimization finds acquisition protocols achievable on modern human and animal systems that consist of 120 measurements with fixed maximum gradient strengths. Axon radii in brain tissue are typically in the range 0.25–10 μm. Simulations suggest that estimates of radii in the range 5–10 μm have highest precision and that a maximum gradient strength of 0.07 T m−1 is sufficient to distinguish radii of 5, 10, and 20 μm. Smaller radii are more difficult to distinguish from one another but are identifiable as small. A maximum gradient strength of 0.2 T m−1 distinguishes radii of 1 and 2 μm. The simulations also suggest that axon densities and diffusivity parameters in the normal range for white matter are recoverable. The experiment‐design optimization has applications well beyond the current work to optimize the protocol for fitting any model of the diffusion process. Magn Reson Med 60:439–448, 2008. © 2008 Wiley‐Liss, Inc.
13C MR spectroscopy measurements of glutaminase activity in human hepatocellular carcinoma cells using hyperpolarized 13C‐labeled glutamine
Authors: Gallagher Ferdia A. , Kettunen Mikko I. , Day Sam E. , Lerche Mathilde , Brindle Kevin M.
Published: July 2008

Dynamic nuclear polarization (DNP) is an emerging technique for increasing the sensitivity of 13C MR spectroscopy (MRS). [5‐13C1]Glutamine was hyperpolarized using this technique by up to 5%, representing a 6000‐fold increase in sensitivity. The conversion of hyperpolarized glutamine to glutamate by mitochondrial glutaminase was demonstrated using 13C‐MRS measurements in cultured human hepatoma cells (HepG2). These results represent the first step in developing an imaging technique for detecting glutamine metabolism in vivo. Furthermore, since glutamine utilization has been correlated with cell proliferation, the study suggests a new technique for detecting changes in tumor cell proliferation. Magn Reson Med 60:253–257, 2008. © 2008 Wiley‐Liss, Inc.
Lactate imaging with Hadamard‐encoded slice‐selective multiple quantum coherence chemical‐shift imaging
Authors: Pickup Stephen , Lee Seung‐Cheol , Mancuso Anthony , Glickson Jerry D.
Published: July 2008

The ability to generate in vivo maps of lactate may have significant diagnostic utility in staging and treatment planning of a wide variety of cancers. The double selective multiple quantum filter technique (SelMQC) has been shown to be effective for nonlocalized detection of lactate with little or no interference from other signals. Here the SelMQC technique has been combined with longitudinal Hadamard slice selection and chemical shift imaging (CSI) to yield slice‐selective images of lactate. The technique is shown to be effective in phantoms and in WSU‐DLCL2 xenografts implanted in flanks of SCID mice. Tumors exhibited an annulus of elevated lactate concentration surrounding a necrotic tumor core. Magn Reson Med 60:299–305, 2008. © 2008 Wiley‐Liss, Inc.
Diffusion‐weighted NMR spectroscopy allows probing of 13C labeling of glutamate inside distinct metabolic compartments in the brain
Authors: Valette Julien , Chaumeil Myriam , Guillermier Martine , Bloch Gilles , Hantraye Philippe , Lebon Vincent
Published: July 2008

In the present work, diffusion‐weighted (DW)‐NMR spectroscopy of glutamate was performed during a 13C‐labeled glucose infusion in monkey brain (six experiments). It is shown that glutamate 13C labeling occurs significantly faster at higher diffusion weightings—slightly for glutamate in position C4, and more markedly for glutamate in position C3. This demonstrates the existence of different diffusion compartments for glutamate, associated with different metabolic rates. Metabolic modeling of 13C enrichment time‐courses suggests that these compartments might be gray and white matter, each having a specific oxidative metabolism rate possibly paralleled by a specific glutamate diffusion coefficient. Magn Reson Med 60:306–311, 2008. © 2008 Wiley‐Liss, Inc.
High resolution localized two‐dimensional MR spectroscopy in mouse brain in vivo
Authors: Braakman Niels , Oerther Thomas , de Groot Huub J.M. , Alia A.
Published: July 2008

Localized two‐dimensional MR spectroscopy (2D MRS) is impacting the in vivo studies of brain metabolites due to improved spectral resolution and unambiguous assignment opportunities. Despite the large number of transgenic mouse models available for neurological disorders, localized 2D MRS has not yet been implemented in the mouse brain due to size constraints. In this study we optimized a localized 2D proton chemical shift correlated spectroscopic sequence at field strength of 9.4T to obtain highly resolved 2D spectra from localized regions in mouse brains in vivo. The combination of the optimized 2D sequence, high field strength, strong gradient system, efficient water suppression, and the use of a short echo time allowed clear detection of cross‐peaks of up to 16 brain metabolites, allowing their direct chemical shift assignments in vivo. To our knowledge this is the first in vivo 2D MRS study of the mouse brain, demonstrating its feasibility to resolve and simultaneously assign several metabolite resonances in the mouse brain in vivo. Implementation of 2D MRS will be invaluable in the identification of new biomarkers during disease progression and treatment using the various available mouse models. Magn Reson Med 60:449–456, 2008. © 2008 Wiley‐Liss, Inc.
Asymmetric quadrature split birdcage coil for hyperpolarized 3He lung MRI at 1.5T
Authors: De Zanche Nicola , Chhina Navjeet , Teh Kevin , Randell Chris , Pruessmann Klaas P. , Wild Jim M.
Published: July 2008

An asymmetric quadrature birdcage body coil for hyperpolarized (HP) 3He lung imaging at 1.5T is presented. The coil is designed to rest on top of the patient support and be used as a temporary insert in a clinical system. A two‐part construction facilitates patient access and the asymmetric design makes maximal use of available bore space to ensure comfort. Highly homogeneous, circularly polarized RF magnetic fields are produced at 48.5 MHz using a conformal mapping method for the geometrical design, combined with an algebraic method to calculate the individual capacitance values on the birdcage coil's ladder network. Efficiency and isolation from the system's proton body coil are ensured by an integrated RF screen. The design methodology is readily applicable to other field strengths or nuclei. Improvements over existing 3He coils were found in terms of sensitivity and transmit field homogeneity, an important feature in HP MRI. Magn Reson Med 60:431–438, 2008. © 2008 Wiley‐Liss, Inc.
Forward‐looking intravascular orthogonal‐solenoid coil for imaging and guidance in occlusive arterial disease
Authors: Anderson Kevan J.T. , Leung General , Dick Alexander J. , Wright Graham A.
Published: July 2008

Recent intravascular imaging coil configurations have focused on side‐viewing catheters capable of imaging the vessel wall of a patent vessel. These designs suffer from the presence of signal nulls and the inability to image in front of a device when it is oriented along the main static field. This is of particular importance when a device is being navigated through an occlusive lesion. To address these limitations we propose a new intravascular coil design consisting of two independent orthogonal solenoids located at the catheter tip. The two coils are oriented in such a way that signal nulls are eliminated and imaging is possible in planes located directly in front of the catheter. Complete characterization of the spatial signal‐to‐noise ratio (SNR) distribution of the design is presented. The coil configuration was fabricated on a 6F guide catheter, and its use is demonstrated in phantoms and in vivo. Magn Reson Med 60:489–495, 2008. © 2008 Wiley‐Liss, Inc.
Sensitivity of diffusion weighted steady state free precession to anisotropic diffusion
Authors: McNab Jennifer A. , Miller Karla L.
Published: July 2008

Diffusion‐weighted steady‐state free precession (DW‐SSFP) accumulates signal from multiple echoes over several TRs yielding a strong sensitivity to diffusion with short gradient durations and imaging times. Although the DW‐SSFP signal is well characterized for isotropic, Gaussian diffusion, it is unclear how the DW‐SSFP signal propagates in inhomogeneous media such as brain tissue. This article presents a more general analytical expression for the DW‐SSFP signal which accommodates Gaussian and non‐Gaussian spin displacement probability density functions. This new framework for calculating the DW‐SSFP signal is used to investigate signal behavior for a single fiber, crossing fibers, and reflective barriers. DW‐SSFP measurements in the corpus callosum of a fixed brain are shown to be in good agreement with theoretical predictions. Further measurements in fixed brain tissue also demonstrate that 3D DW‐SSFP out‐performs 3D diffusion weighted spin echo in both SNR and CNR efficiency providing a compelling example of its potential to be used for high resolution diffusion tensor imaging. Magn Reson Med 60:405–413, 2008. © 2008 Wiley‐Liss, Inc.
Linear least‐squares method for unbiased estimation of T1 from SPGR signals
Authors: Chang Lin‐Ching , Koay Cheng Guan , Basser Peter J. , Pierpaoli Carlo
Published: July 2008

The longitudinal relaxation time, T1, can be estimated from two or more spoiled gradient recalled echo images (SPGR) acquired with different flip angles and/or repetition times (TRs). The function relating signal intensity to flip angle and TR is nonlinear; however, a linear form proposed 30 years ago is currently widely used. Here we show that this linear method provides T1 estimates that have similar precision but lower accuracy than those obtained with a nonlinear method. We also show that T1 estimated by the linear method is biased due to improper accounting for noise in the fitting. This bias can be significant for clinical SPGR images; for example, T1 estimated in brain tissue (800 ms < T1 < 1600 ms) can be overestimated by 10% to 20%. We propose a weighting scheme that correctly accounts for the noise contribution in the fitting procedure. Monte Carlo simulations of SPGR experiments are used to evaluate the accuracy of the estimated T1 from the widely‐used linear, the proposed weighted‐uncertainty linear, and the nonlinear methods. We show that the linear method with weighted uncertainties reduces the bias of the linear method, providing T1 estimates comparable in precision and accuracy to those of the nonlinear method while reducing computation time significantly. Magn Reson Med 60:496–501, 2008. © 2008 Wiley‐Liss, Inc.
Baseline blood oxygenation modulates response amplitude: Physiologic basis for intersubject variations in functional MRI signals
Authors: Lu Hanzhang , Zhao Chenguang , Ge Yulin , Lewis‐Amezcua Kelly
Published: July 2008

Although BOLD functional MRI (fMRI) provides a useful tool for probing neuronal activities, large intersubject variations in signal amplitude are commonly observed. Understanding the physiologic basis for these variations will have a significant impact on many fMRI studies. First, the physiologic modulator can be used as a regressor to reduce variations across subjects, thereby improving statistical power for detecting group differences. Second, if a pathologic condition or a drug treatment is shown to change fMRI responses, monitoring this modulatory parameter is useful in correctly interpreting the fMRI changes to neuronal deficits/recruitments. Here we present evidence that the task‐evoked fMRI signals are modulated by baseline blood oxygenation. To measure global blood oxygenation, we used a recently developed technique, T2 relaxation under spin‐tagging (TRUST) MRI, which yielded baseline oxygenation of 63.7% ± 7.2% in the sagittal sinus with an estimation error of 1.3%. It was found that individuals with higher baseline oxygenation tend to have a smaller fMRI signal, and vice versa. For every 10% difference in baseline oxygenation across subjects, BOLD and cerebral blood flow (CBF) signals differ by –0.4% and –30.0%, respectively, when using visual stimulation. TRUST MRI is a useful measurement for fMRI studies to control for the modulatory effects of baseline oxygenation that are unique to each subject. Magn Reson Med 60:364–372, 2008. © 2008 Wiley‐Liss, Inc.
Spherical harmonic inductive detection coils for dynamic pre‐emphasis
Authors: Edler Karl , Hoult David
Published: July 2008

The issue of eddy currents induced by the rapid switching of magnetic field gradients is a long‐standing problem. A new method for dealing with this problem is presented whereby spatial harmonic components of the magnetic field are continuously sensed, through their temporal rates of change, and corrected. In this way, the effects of the eddy currents on the magnetic field can be detected and correction currents applied to the appropriate gradient or shim coils in a time much less than the rise time of the gradients. This new methodology has the potential to dynamically shape eddy current corrections for multiple spatial harmonic components of the field. Magn Reson Med 60:277–287, 2008. © 2008 Wiley‐Liss, Inc.
Relaxation time measurements of bone marrow protons in the calcaneus using a compact MRI system at 0.2 Tesla field strength
Authors: Tomiha Sadanori , Iita Nachiko , Okada Fumi , Handa Shinya , Kose Katsumi
Published: July 2008

Relaxation times (T1 and T2) of the bone marrow protons and trabecular bone volume fraction (TBVF) in the calcaneus were measured for 100 female volunteers using a compact MRI system at 0.2 T field strength. The speed of sound (SOS) through the calcaneus was measured also for the same subjects using a quantitative ultrasound system. Both relaxation times were found to have positive correlations with age (R = 0.40; P < 0.0001 and R = 0.31; P < 0.002, respectively) and negative correlations with SOS (R = −0.38; P < 0.0001 and R = −0.38; P < 0.0001, respectively). Although TBVF had a fairly high positive correlation with the SOS (R = 0.67), neither T1 nor T2 were correlated with TBVF (R = −0.062 and −0.024, respectively). These results suggest that the age dependence of both T1 and T2 is caused by the microdynamic properties of the lipid molecules in bone marrow observed using acoustic or elastic modalities. Magn Reson Med 60:485–488, 2008. © 2008 Wiley‐Liss, Inc.
Combination of standard Galerkin and subspace methods for the time‐dependent Navier‐Stokes equations with nonsmooth initial data
Authors: He Yinnian
Published: July 2008

We consider a combination of the standard Galerkin method and the subspace decomposition methods for the numerical solution of the two‐dimensional time‐dependent incompressible Navier‐Stokes equations with nonsmooth initial data. Because of the poor smoothness of the solution near t = 0, we use the standard Galerkin method for time interval [0, 1] and the subspace decomposition method time interval [1, ∞). The subspace decomposition method is based on the solution into the sum of a low frequency component integrated using a small time step Δt and a high frequency integrated using a larger time step pΔt with p > 1. From the H1‐stability and L2‐error analysis, we show that the subspace decomposition method can yield a significant gain in computing time. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2009
The use of Chebyshev cardinal functions for solution of the second‐order one‐dimensional telegraph equation
Authors: Dehghan Mehdi , Lakestani Mehrdad
Published: July 2008

A numerical technique is presented for the solution of the second order one‐dimensional linear hyperbolic equation. This method uses the Chebyshev cardinal functions. The method consists of expanding the required approximate solution as the elements of Chebyshev cardinal functions. Using the operational matrix of derivative, the problem is reduced to a set of algebraic equations. Some numerical examples are included to demonstrate the validity and applicability of the technique. The method is easy to implement and produces very accurate results. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
The development and regulation of lobbying in the new member states of the European Union
Authors: McGrath Conor
Published: July 2008

This paper focuses on lobbying as a political activity and the emergence of lobbying regulation in 10 new member states of the European Union (EU). The analysis begins with general observations about lobbying in post‐communist states and on the development of lobbying in three of the larger new member states: Hungary, Poland and the Czech Republic. Key to how lobbying will continue to develop in the future in these 10 countries is how it will be regulated and controlled. Therefore, the paper examines this in some detail. The analysis concludes with some recommendations on the role that could be played by professional bodies, which represent lobbyists in gaining more acceptance for interest groups in these new member states.

Copyright © 2008 John Wiley & Sons, Ltd.
Understanding interest groups, lobbying and lobbyists in developing democracies
Authors: Thomas Clive S. , Hrebenar Ronald J.
Published: July 2008

This introductory article sets the scene for understanding the seven articles that follow in this Special Issue of the Journal. It lays the groundwork in five areas. First, it explains key terms and concepts important for understanding interests, interest groups and lobbying in developing democracies and goes into some detail about the concept of democracy. Second, it offers insights into the characteristics of interest group systems in developing democracies. Third, it briefly reviews the form and extent of the existing work written on interest groups in these political systems. Fourth, it argues that viewing developing democracies through the role of interest groups is a valuable analytical tool but must be adapted from the study of interest groups in developed and well‐established democracies to be of use in understanding these developing systems. And fifth, it points out how the seven articles that follow help illustrate the definitions and explanations presented in the previous four sections and the promise and challenges faced by interests and interest groups in these political systems.

Copyright © 2008 John Wiley & Sons, Ltd.
Nutritional status at admission of children with cancer in Malawi
Authors: Israëls Trijn , Chirambo Chawanangwa , Caron Huib N. , Molyneux Elizabeth M.
Published: July 2008

Background

Malnutrition at diagnosis is found in 10–50% of children with cancer in industrialized countries. In developing countries a large proportion of the normal paediatric population is undernourished and children with cancer often present late with advanced disease. Therefore it would be expected that many children with cancer are malnourished at admission. Malnutrition is associated with more severe chemotherapy toxicity and infectious complications.

Methods

All new paediatric oncology patients admitted in the Queen Elizabeth Central Hospital, Blantyre, Malawi between 1, January 2007 and 1, January 2008 were included. We documented age, clinical diagnosis, HIV status, weight, height, mid‐upper‐arm‐circumference (MUAC) and triceps skinfold (TSF), and calculated arm muscle area (AMA). Nutritional data were compared with the 1978 NCHS growth curves.

Results

Of 128 children, 70 (55.1%) had an AMA for age <5th percentile and 76 (59.3%) had a TSF and MUAC below the 5th percentile, both parameters indicating acute malnutrition. Fifty seven patients (44.5%) had a height for age <−2 SD (indicative of stunting), and 22 patients (17.2%) had a weight for height (WFH) <−2 SD.

Conclusion

Arm anthropometry shows that more than half of Malawian children with cancer are severely acutely malnourished at diagnosis. WFH, in children with large tumour masses, is less sensitive than arm anthropometry in detecting acute malnutrition. Forty‐five percent of paediatric oncology patients in Malawi are stunted, making interpretation of weight for age (WFA) very difficult. Pediatr Blood Cancer 2008;51:626–628. © 2008 Wiley‐Liss, Inc.
Complete second look operation and radiotherapy in locally advanced non‐alveolar rhabdomyosarcoma in children: A report from the AIEOP soft tissue sarcoma committee
Authors: Cecchetto Giovanni , Carretto Elena , Bisogno Gianni , Dall'Igna Patrizia , Ferrari Andrea , Scarzello Giovanni , Donfrancesco Alberto , Alaggio Rita , Indolfi Paolo , Carli Modesto
Published: July 2008

Background

To evaluate the effect of radiotherapy (RT) in association with complete second look operation, histologically confirmed, on outcome of patients with IRS Gr.III non‐alveolar RMS.

Procedure

We analyzed data from 39 patients (age: 0.5–194 months, median 52) who were enrolled between 1988 and 2005 in 2 consecutive Italian Studies, RMS 88 and RMS 96. All achieved a complete resection of the residual tumor after neoadjuvant chemotherapy; 27 did not receive any other local treatment: pelvic 8, extremities 6, head‐neck‐non‐parameningeal 5, orbit 1, genito‐urinary‐bladder‐prostate 3, trunk 2, abdomen 1, vagina 1; 12 were given RT (32–45 Gy), 5 before and 7 after the operation: genito‐urinary‐bladder‐prostate 3, pelvic 3, abdominal 1, extremities 1, head‐neck‐parameningeal 1, head‐neck‐non‐parameningeal 1, vagina 1, orbit 1. All received postoperative chemotherapy.

Results

Median follow‐up was 81 months (range 17–219 months). With RT: 10/12 patients are in first complete remission; 2/12 had a metastatic relapse (1 also local relapse), and both of them died of disease. Without RT: 16/27 maintained the first complete remission, however 1/16 died due to a second tumor; 8 suffered from local relapse (4 pelvic, 1 orbit, 1 vagina, 1 head‐neck‐non‐parameningeal, 1 abdomen) and 3 of them died, 3 showed a metastatic recurrence (2 extremities, 1 pelvic) and 1 died.

Conclusions

Local relapses were more frequent for patients without RT, especially in pelvic sites. The two relapses after RT occurred in huge bladder‐prostate RMS. Although the limited number of patients does not allow statistically significant conclusions, our experience suggests that RT may have a positive influence on local control for completely resected non‐alveolar RMS. Pediatr Blood Cancer 2008;51:593–597. © 2008 Wiley‐Liss, Inc.
The guardians' perspective on paediatric cancer treatment in Malawi and factors affecting adherence
Authors: Israëls Trijn , Chirambo Chawanangwa , Caron Huib , de Kraker Jan , Molyneux Elizabeth , Reis Ria
Published: July 2008

Background

Abandonment of paediatric cancer treatment is a common problem in developing countries. Little is known about the guardians' perspective on cancer treatment in these countries, especially the factors that affect adherence.

Methods

Following a pilot study enquiring into the possible causes of abandonment, a problem analysis diagram was drawn which helped to develop the questionnaires. Semi‐structured interviews (n = 83) and focus group discussions (n = 8) were held with the guardians of 25 Burkitt lymphoma patients and 7 Wilms tumour patients at different phases of therapy in Malawi.

Results

Parents in Malawi are very motivated to continue treatment if they think that it will cure their child. Financial costs are important concerns. Not all tasks at home are assumed by other household members. The diagnosis of cancer was unknown before being told about it in hospital and caused fear of recurrence and death. Guardians are reluctant to ask the health personnel questions. They worry that taking frequent blood samples will weaken their child. The side effects of the chemotherapy are seen as a proof of efficacy.

Conclusion

It is important to appreciate the guardians' concerns when offering treatment that requires their sustained commitment. It is necessary to provide not only medical treatment, but also travel allowances and adequate nutritional support during long hospital stays to impoverished families. Information should be given proactively. Pediatr Blood Cancer 2008;51:639–642. © 2008 Wiley‐Liss, Inc.
AC conductivity and positive temperature coefficient effect in microcellular EPDM vulcanizates
Authors: Mahapatra S.P. , Sridhar V. , Chaudhary R.N.P. , Tripathy D.K.
Published: July 2008

Dielectric relaxation spectra of conductive carbon black reinforced microcellular EPDM vulcanizates were used to study their relaxation behavior in the frequency range of 0.01–105Hz over a wide range of temperature from 30 to 120°C. The effect of variation in filler loading and blowing agent loading (density) on dielectric characteristics such as impedance, dielectric constant, and conductivity has been studied. The experimental results show that the relative dielectric permittivity of the composites depends strongly on the extent of carbon black and blowing agent concentrations. The frequency dependence of AC conductivity has been investigated by using Percolation theory. The permittivity and conductivity of the microcellular composites have been analyzed based on scaling theory at increasing temperatures. The applicability of Lichtenecker‐Rother's “rule of mixture” to describe the complex permittivity of the composite has also been investigated. Irrespective of the blowing agent loading and temperature, the percolation threshold as studied by DC conductivity was found to be at 40 phr loading of the filler. Scanning electron microphotographs showed agglomeration of the filler above this concentration and formation of a continuous network structure. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Studies on morphologies and thermal properties of poly(lactic acid)/polycaprolactone/organic‐modified montmorillonite nanocomposites
Authors: Ren Jie , Yu Tao , Li Hang , Ren Tianbin , Yang Shuang
Published: July 2008

Poly(lactic acid)/organic montmorillonite (PLA/OMMT) nanocomposites were prepared via twin‐screw extrusion. Montmorillonite (MMT) was firstly organically modified to improve the compatibility between polyester and MMT. The effects of ratio between PLA and OMMT and the addition of polycaprolactone (PCL), as a compatilizer, on the properties of PLA/OMMT nanocomposites were studied. The morphology and the properties of the nanocomposites were characterized by XRD, DSC, and TEM. Using OMMT, the intercalated structure was formed during the extrusion process and the OMMT interlayers space was enlarged. More OMMT content was apt to form thicker structure with more stacked individual silicate layers, which led to lower degree of crystallinity of PLA. It showed that 1 phr OMMT could result in the largest interlayers space and the best crystallization state. PCL can effectively increase the binding force between two phases and improve the order of the nanocomposites. In addition, the annealing after treatment can form regular structure and enhance the thermal properties of nanocomposites. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Preparation and characterization of core‐shell PS/Ni composite microspheres
Authors: Zhao Wen , Zhang Qiuyu , Zhang Junping , Gu Junwei , Guo Feige
Published: July 2008

PS/Ni microspheres were prepared by electroless nickel plating on PS microspheres. Several parameters for plating were optimized in order to obtain integrated and uniform nickel coatings. The properties of obtained composite microspheres, such as chemical composition and crystal texture of the coating, mechanical property, density, and magnetism, were characterized by SEM, EDS, XRD, and VSM. It was revealed that several parameters, such as thiourea dosage, reaction temperature, and load, had significant influence on fabrication of integrated and homogeneous nickel shell. It was also demonstrated that the properties of the PS/Ni microspheres, such as nickel weight ratio, density, and magnetism, can be tuned by adjusting the load. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Numerical investigation on flow through porous media in the post‐infusion process
Authors: Song Young Seok , Youn Jae Ryoun
Published: July 2008

During the vacuum‐assisted resin transfer molding (VARTM) processing, the post‐infusion behavior after complete wet‐out and before gelation of the resin is critical for the development of the thickness and fiber volume fraction distribution in the cured composite part. The pressure gradient developed during infusion results in a thickness gradient due to the flexible nature of the bagging approach. After full infusion, the resin typically bleeds into a vacuum trap, allowing redistribution of pressure and preform thickness. In this study, a non‐rigid control volume is used to formulate a set of governing equations for analysis of the post‐infusion process. The model is used to investigate the effects of processing parameters and different processing scenarios on resin flow, resin pressure, and thickness variation of the composite laminate. This work provides a tool for optimization of the VARTM process to reduce final part variability. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Two steps synthesis and conductivity of polyacrylamide/Cu conducting hydrogel
Authors: Lin Jianming , Tang Qunwei , Wu Jihuai , Sun Hui , Fan Shijun , Hu De
Published: July 2008

Cu microparticles are dispersed in a polyacrylamide (PAM) superabsorbent by a two steps aqueous solution polymerization. Based on the electrical conductivity of Cu and the water absorbency of PAM, a novel conducting hydrogel (PAM/Cu) with a conductivity of 6.12 mS cm−1 and percolation threshold of 3 wt% is prepared. An appended network structure model for explaining the electrical conduction of PAM/Cu hydrogel is proposed. And the effects of crosslinker, initiator, monomer concentration, Cu content, reaction temperature, water absorbency on the electrical conductivity are also investigated according to the structure model. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Tensile creep of a long‐fiber glass mat thermoplastic composite. I. Short‐term tests
Authors: Dasappa Prasad , Lee‐Sullivan Pearl , Xiao Xinran , Foss Peter H
Published: July 2008

This work is part of a larger experimental program aimed at developing a semi‐empirical constitutive model for predicting creep in random glass mat thermoplastic (GMT) composites. The tensile creep response of a long‐fiber GMT material has been characterized for 3‐ and 6‐mm thick material. Tensile tests showed that the variability within and between plaques are comparable with an overall variability of about 6% and 8% for the 3‐ and 6‐mm thick materials, respectively. The thicker material exhibited slightly higher variability and directional dependence due to greater flow during molding of the plaques. Short‐term creep tests consisting of 30 min creep and recovery, respectively, were performed over the stress range between 5 and 60 MPa. Three tests for determining the linear viscoelastic region were considered which showed that the 3‐ and 6‐mm thick GMT are linear viscoelastic up to 20 and 25 MPa respectively. The 6‐mm thick GMT consisting of a higher fiber weight fraction was linear over wider stress range. Furthermore, it was found that plastic strains were accumulated during creep, which suggests that a nonlinear viscoelastic–viscoplastic model would be more appropriate for long‐term creep at relatively high stresses, which will be presented in our companion paper. The magnitude of the plastic strains developed in the creep tests presented here was lower because a single specimen was loaded at multiple stress level over short durations. Hence, a nonlinear viscoelastic constitutive model has been developed for the two thickness materials. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Dynamic response of Free–Free laminated curved panels subjected to explosive blast
Authors: Nezami M. , Jam J.E. , Nia N.G.
Published: July 2008

The dynamic response of Free–Free boundary conditions laminated curved panels subjected explosive blast loading is considered. The Rayleigh–Ritz method is employed to obtain the eigen‐frequencies of the curved panels by using a set of simple polynomials as admissible functions. The mode superposition method is then in the analysis of the dynamic response. A few examples of the difference geometries and staking sequence for showing the ability and performance of this technique are presented. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Thermal, electrical, and mechanical properties of Si3N4 filled LLDPE composite
Authors: An Qunli , Qi Shuhua , Zhou Wenying
Published: July 2008

Silicon nitride (Si3N4) filled linear low‐density polyethylene (LLDPE) composite was prepared. The effects of Si3N4 filler content, dispersion, and LLDPE particle size on the thermal conductivity, and Si3N4 filled content on the mechanical and electrical properties of Si3N4 reinforced LLDPE composites prepared using powder mixing were investigated. The results indicate that there existed a unique dispersion state of Si3N4 particles in LLDPE, shell‐kernel structure, in which Si3N4 particles surrounded LLDPE matrix particles. With increasing filler content and LLDPE particles size, thermal conductivity increased, and reached 1.42 W/m K at 30 vol% of filler, seven times as that of unfilled LLDPE. Furthermore, the examinations of Agari model demonstrate that larger size LLDPE particles form thermal conductive networks easily compared with smaller ones. The values predicted by theoretical model underestimate the thermal conductivity of Si3N4/LLDPE composites. In addition, the composites still possessed rather higher electrical resistivity and dielectric properties, but the mechanical properties decreased. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Preparation and properties of cellulose/silica hybrid composites
Authors: Sequeira Sónia , Evtuguin Dmitry V. , Portugal Inês
Published: July 2008

Cellulose/silica hybrid (CSH) composites were prepared from bleached Eucalyptus globulus kraft pulp or primary treatment sludge cellulose fibers by a sol–gel method, using solely tetraethoxysilane or with the addition of trimethoxyoctylsilane as the silica precursors and heteropoly acid (H3PW12O40) as the catalyst. Silica aging was accomplished during the hot pressing of preformed CSHs plates, and the properties of the resulting materials have been evaluated. The incorporation of a silica network in cellulosic materials increased their dimensional stability significantly during soaking in water, hydrophobicity, thermal stability, and bending strength. The thermal conductivity of these hybrid materials is comparable to commercially available insulation foams. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Pattern of intravenous bisphosphonate use in outpatient care in Germany
Authors: Hoffmann Falk , Jung Tatjana I. , Felsenberg Dieter , Glaeske Gerd
Published: July 2008

Purpose

Intravenous bisphosphonate therapy has recently been associated with the development of an osteonecrosis of the jaws (ONJ). If new adverse events have been linked to drugs, basic information on drug exposure in routine care is essential. The aim of this study was to investigate prevalence as well as duration and cumulative doses of intravenous bisphosphonate treatment.

Methods

We analysed data of the statutory health insurance company Gmünder ErsatzKasse (GEK) over the years 2000–2006. We first estimated treatment prevalence in 2006. We further studied a cohort of new users of intravenous bisphosphonates who initiated treatment between 1 January 2001 and 31 December 2005. We used the Kaplan–Meier method to estimate the time to end of treatment (composite of discontinuation and death).

Results

A total of 1024 patients received at least one dose of intravenous bisphosphonates in 2006. The most commonly prescribed agent was zoledronate (53.7%). After standardizing for sex and age, an estimated 0.1% of the German population would have been treated in 2006. Of 1259 new users in 2001–2005, an estimated 40% of men and 22% of women died within 12 months. The median treatment duration was 3.5 months in men and 5.7 months in women. This difference disappears when studying only survivors.

Conclusions

Although our study suggests that intravenous bisphosphonates were prescribed mainly for short durations, this result is strongly influenced by the fact that new users had a poor prognosis with a short life expectancy. Copyright © 2008 John Wiley & Sons, Ltd.
Discrepancies between GPs' and psychiatrists' medication records
Authors: Robinson Julie
Published: July 2008

Clear communication between primary and secondary care is essential to prevent prescribing errors, especially in the case of psychiatry where medication is frequently altered and prescribing may be the responsibility of either the GP or the specialist. Here, Dr Robinson describes an audit carried out at the local elderly day treatment service to examine the discrepancies between GPs' records of medication and those of the day service, and to investigate how improvements could be made. Copyright © 2008 Wiley Interface Ltd
The future of reversible addition fragmentation chain transfer polymerization
Authors: Barner‐Kowollik Christopher , Perrier Sébastien
Published: July 2008

We examine the reversible addition fragmentation chain transfer (RAFT) process with regard to its potential and limits in future industrial applications (including those conducted on a larger scale) as well as materials science. The outlook for the RAFT process is bright: Its unrivaled inherent process simplicity coupled with a wide tolerance to monomer classes and functionalities makes it a prime candidate for the use in large reactors. At the same time, it allows for ready access to complex macromolecular architectures of variable shape and size. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5715–5723, 2008
Thermosensitive and control release behavior of poly (N‐isopropylacrylamide‐co‐acrylic acid) latex particles
Authors: Lee Chia‐Fen , Lin Chia‐Cheng , Chiu Wen‐Yen
Published: July 2008

In this work, poly(N‐isopropylacrylamide‐co‐acrylic acid) (poly(NIPAAm‐AA)) copolymer latex particles (microgels) were synthesized by the method of soapless emulsion polymerization. Poly(NIPAAm‐AA) copolymer microgels have the property of being thermosensitive. The concentration of acrylic acid (AA) and crosslinking agent N,N′‐methylenebisacrylamide were important factors to influence the lower critical solution temperature (LCST) of poly(NIPAAm‐AA) microgels. The effects of AA and crosslinking agent on the swelling behavior of poly(NIPAAm‐AA) microgels were also studied. The poly(NIPAAm‐AA) copolymer microgels were then used as a thermosensitive drug carrier to load caffeine. The effects of concentration of AA and crosslinking agent on the control release of caffeine were investigated. How the AA content and crosslinking agent influenced the morphology and LCST of the microgels was discussed in detail. The relationship of morphology, swelling, and control release behavior of these thermosensitive microgels was established. A new scheme was proposed to interpret the control release of the microgels with different morphological structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5734–5741, 2008
A phosphorus‐containing thermotropic liquid crystalline copolyester with low mesophase temperature and high flame retardance
Authors: Zhao Cheng‐Shou , Chen Li , Wang Yu‐Zhong
Published: July 2008

A novel phosphorus‐containing thermotropic liquid crystalline copolyester with flexible spacers (P‐TLCP‐FS) was synthesized by melt transesterification from p‐acetoxybenzoic acid (p‐ABA), terephthalic acid (TPA), ethylene glycol, and acetylated 2‐(6‐oxid‐6H‐dibenz(c,e) (1,2) oxaphosphorin 6‐yl) 1,4‐benzenediol (AODOPB). The chemical structure and properties of the obtained P‐TLCP‐FS were characterized by Fourier‐transform infrared spectroscopy (FT‐IR), proton nuclear magnetic resonance spectroscopy (1H‐NMR), inherent viscosity measurements, differential scanning calorimetry (DSC), thermogravimetry (TGA), polarizing light microscopy (PLM), and X‐ray diffraction (XRD) analysis. P‐TLCP‐FS had inherent viscosities of 0.92–1.12 dL/g and exhibited low and wide mesophase temperatures, ranging from 185 to 330 °C, which can match with the processing temperatures of most conventional polymers and high flame retardancy with a limiting oxygen index value of 70% and UL‐94 V‐0 rating. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5752–5759, 2008
Photoreactive main chain liquid crystalline polyesters containing oxadiazole and bis(benzylidene) cycloalkanone units
Authors: Balamurugan Rathinam , Kannan Palaninathan
Published: July 2008

Photoreactive main chain liquid crystalline polyesters containing oxadiazole and bis(benzylidene)cycloalkanone moieties were synthesized and characterized by structural, thermal, mesomorphic, and optical measurements. The bis(benzylidene) cycloalkanone chromophores in the main chain can constitute both as a mesogen and photoreactive center, whereas 1,3,4‐oxadiazole is a well‐known fluorophore. The thermal properties of polymers were found to be inversely proportional not only to the spacer length but also to ring‐size of cycloalkanones. Hot stage polarized optical microscopic investigations displayed enantiotropic nematic liquid crystalline phases and development of grainy to schlieren textures depends on the length of flexible spacer in the polymer backbone which was in accordance with DSC analysis. Both photoisomerization and photodimerization are observed from the absorption spectra and discussed. The fluorescence spectra in solution state at various concentrations showed that the polymers show blue‐emission maxima and the Stokes shifts being 48–49 nm. The energy transfer occurred when increasing the concentration of the solution. The band gap energies calculated from the absorption spectra are in the range of 3.17–3.41 eV. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5760–5775, 2008
A single versus multiple doses of dexamethasone in infants wheezing for the first time
Authors: Schuh Suzanne , Coates Allan L. , Dick Paul , Stephens Derek , Lalani Amina , Nicota Erika , Mokanski Matthew , Khaikin Svetlana , Allen Upton
Published: July 2008

Rationale:

Corticosteroid therapy is not routinely recommended in true bronchiolitis. However, since bronchiolitis and the first asthma attack are impossible to distinguish, some infants with the first wheezing episode receive corticosteroids. Optimal duration of corticosteroid therapy in this scenario is unknown. This study compared efficacy of multiple administrations and a single dose of dexamethasone in bronchiolitis.

Methods:

In this randomized double blind trial, previously healthy outpatients 2–23 months of age with bronchiolitis and Respiratory Disease Assessment Instrument (RDAI) score 6 or more received 1 mg/kg of oral dexamethasone in the Emergency Department. Prior to discharge at 4 hr they were randomized to either 4 daily doses of dexamethasone 0.15 mg/kg or placebo equivalent. Primary outcome was the proportion of subsequent hospitalizations or prescribed trials of bronchodilator/corticosteroid therapy for dyspnea by day 6 in the groups. Secondary outcomes were changes in the RDAI to day 6, and proportions with unscheduled visits by days 6 and 28.

Results:

The rate of primary outcome in the single dose group (SDG, N = 64) was 9/64 or 14.1% versus 7/61 or 11.5% in the multiple dose group (MDG, N = 61) [95% CI 0.09; 0.14]. Twelve (18.8%) children in the SDG had unscheduled medical visits by day 6 versus 11 (18.0%) children in the MDG [95% CI 0.13; 0.14]. On day 6 the RDAI decreased from 9.5 ± 2.1 to 2.1 ± 2.4 in the SDG and from 9.8 ± 2.2 to 1.6 ± 2.3 in the MDG [95% CI 0.36; 2.06]. Between days 7–28, 24/64 (37.5%) SDG infants returned for care versus 20/61 (32.8%) of the MDG [95% CI 0.12; 0.21].

Conclusions:

Our study suggests that, in outpatients with bronchiolitis who receive dexamethasone, continuation of this agent beyond the initial dose does not provide significant benefit. Pediatr Pulmonol. 2008; 43:844–850. © 2008 Wiley‐Liss, Inc.