bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbial production of docosahexaenoic acid by a low temperature‐adaptive strain Thraustochytriidae sp. Z105: screening and optimization
Authors: Zhou Peng‐Peng , Lu Ming‐Bo , Li Wei , Yu Long‐Jiang
Published: May 2010

As an alternative source in addition to fish oil, microbial production of docosahexaenoic acid has been recieved more and more attentions owing to their culture advantage. A unicellular eukaryotic microbe with high DHA production and capable of low temperature‐adaptive growth was isolated from seawater and identified as Thraustochytriidae sp. Z105. The siginificant effect of temperature on cell growth and DHA synthesis by the strain was revealed. It could grow and produce DHA even at 4 °C, but hardly grow above 35 °C. Low temperature (15–25 °C) was favorable for formation of biomass, lipids and DHA, but DHA synthesis was completely blocked above 30 °C. Conditions for high level DHA production by Thraustochytriidae sp. Z105 in flask culture were optimized as follows: medium containing glucose 80 g/l, yeast extract 5.0 g/l, K2HPO4 · 3 H2O 1.0 g/l, MgSO4 · 7 H2O 0.5 g/l, seawater crystal 20 g/l, pH 6.0, liquid volume 30 ml/250 ml, temperature 20 °C, agitation speed of 200 r/min, and culture for 120 h. Under the optimal conditions, biomass of 16.72 g/l, total lipids of 5.35 g/l, DHA yield of 1.71 g/l (accounting for 32% of the total lipids) were achieved, respectively. In flask cluture level, the DHA productivity of Thraustochytriidae sp. Z105 was higher than most reported results, which suggested the wild type strain was a potential superior candidate for industrialization of DHA production. Moreover, the strain is an unique and valuable resource for investigation of the low temperature adaptive mechanism related to DHA synthesis. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The polymorphism of protein phosphatase Z1 gene in Candida albicans
Authors: Kovács László , Farkas Ilona , Majoros László , Miskei Márton , Pócsi István , Dombrádi Viktor
Published: May 2010

The gene of protein phosphatase Z1 (CaPPZ1)1 that codes a fungus specific regulatory enzyme was investigated in Candida albicans. After cloning and sequencing CaPPZ1 we revealed the heterozygous nature of the ATCC 10231 reference strain, and identified two new alleles termed CaPPZ1‐2 and CaPPZ1‐3. The genetic polymorphism in CaPPZ1 was extended by finding a fourth allele CaPPZ1‐4 in a clinical isolate. Single nucleotide replacements and short in/del mutations were identified in the gene, some of which resulted in amino acid changes in the protein. The analysis of the hypervariable 3′‐noncoding gene region in 27 DNA sequences obtained from reference strains and clinical samples confirmed the presence of four distinct DNA sequence‐groups that correspond to the four main alleles of CaPPZ1. In addition to the allelic combinations, we detected individual mutations elevating genetic variability of the opportunistic pathogen. We utilized the hypervariable gene region for genotyping C. albicans in clinical isolates by sequencing the cloned amplified region, by direct sequencing of the PCR products, or by RFLP analysis. The comparison of the genotypes of the strains originating from different body parts of the same patient proved to be useful in delineating the origin of the infection. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of oxidative stress and grains on sclerotial biomass and carotenoid yield of Penicillium sp. PT95
Authors: Chen Shu‐Jun , Wang Qi , Han Jian‐Rong
Published: May 2010

Oxidative stress and grains were evaluated for carotenoid production by solid‐state fermentation using Penicillium sp. PT95. When the fungus was grown at high oxidative stress, its sclerotial biomass and carotenoid content in sclerotia increased significantly with respect to low oxidative stress (P < 0.01). High oxidative stress also caused a statistically significant increase in carotenoid yield as compared with low oxidative stress (P < 0.01). Both the sclerotial biomass and the amount of carotenoid accumulated in sclerotia of strain PT95 were strongly dependent on the grain medium used. Among the grain media tested under high oxidative stress, buckwheat medium gave the highest content of carotenoid in sclerotia (828 μg/g dry sclerotia), millet medium gave respectively the highest sclerotial biomass (12.69 g/100 g grain) and carotenoid yield (10.152 mg/100 g grain). (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of Mn‐related Raman modes in Mn‐doped ZnO thin films
Authors: Hu Y. M. , Wang C. Y. , Lee S. S. , Han T. C. , Chou W. Y. , Chen G. J.
Published: May 2010

This article aims to investigate the Raman modes present in Mn‐doped ZnO thin films that are deposited using the magnetron co‐sputtering method. A broad band ranging from 500 to 590 cm−1 is present in the Raman spectra of heavily Mn‐doped ZnO films. The multi‐peak‐fitting results show that this broad band may be composed of six peaks, and the peak at 528 cm−1 could be a characteristic mode of Mn2O3. The results of this study suggest that the origin of the Raman peaks in Mn‐doped ZnO films may be due to three major types: structural disorder and morphological changes caused by the Mn dopant, Mn‐related oxides and intrinsic host‐lattice defects. Copyright © 2010 John Wiley & Sons, Ltd.
The ‘stakeholder view’ approach: an untapped opportunity to manage corporate performance and wealth
Authors: Sachs Sybille , Groth Hans , Schmitt Ruth
Published: May 2010

Management should focus on interacting and partnering with all stakeholders to enhance corporate performance and firm's value.
Strategic planning implementation and creation of value in the firm
Authors: Aldehayyat Jehad S. , Anchor John R.
Published: May 2010

A clear relationship between the existence of strategic planning implementation problems and organizational performance has been identified.
Heterogeneity in the course of posttraumatic stress disorder: Trajectories of symptomatology
Authors: Dickstein Benjamin D. , Suvak Michael , Litz Brett T. , Adler Amy B.
Published: May 2010

Unconditional and conditional trajectories of posttraumatic stress disorder (PTSD) symptomatology were examined using a sample of U.S. soldiers deployed on a NATO‐led peacekeeping mission to Kosovo. Data were collected at 4 time points, ranging from the weeks leading up to deployment to 9‐months postdeployment. Latent class growth analysis revealed 4 unique symptom trajectories: resilience, recovery, delayed, and unrealized anxiety. Variables identified as significant predictors of trajectory class included previous traumatic events, combat exposure, peacekeeping daily hassles, depression, alcohol use, aggressive behavior, stress reactivity, and military rank. Results from this study add to the literature detailing the variability in PTSD course, as well as to the literature pertaining to predictors of PTSD onset and course.
Parenting behaviors and posttraumatic symptoms in relation to children's symptomatology following a traumatic event
Authors: Valentino Kristin , Berkowitz Steven , Stover Carla Smith
Published: May 2010

Child‐ and caregiver‐report about parenting behaviors, and caregiver‐report of their own symptoms were examined in relation to children's symptomatology following a potentially traumatic event (PTE) among 91 youth. Child‐report of hostile and coercive parenting was a salient predictor of child posttraumatic stress disorder (PTSD), internalizing symptoms, and personal adjustment. Caregivers' own trauma symptoms predicted caregiver‐report of child PTSD, internalizing and externalizing symptoms, but not child‐reported child symptoms. Implications for assessment and intervention following exposure to a PTE are emphasized.
Safety of Small-For-Size Grafts in Adult-To-Adult Living Donor Liver Transplantation Using the Right Lobe
Authors: Moon Ju Ik , Kwon Choon Hyuck David , Joh Jae-Won , Jung Gum O. , Choi Gyu-Seong , Park Jae Berm , Kim Jong Man , Shin Milljae , Kim Sung-Joo , Lee Suk-Koo
Published: May 2010

The problem of graft size is one of the critical factors limiting the expansion of adult-to-adult living donor liver transplantation (LDLT). We compared the outcome of LDLT recipients who received grafts with a graft-to-recipient weight ratio (GRWR) < 0.8% or a GRWR ≥ 0.8%, and we analyzed the risk factors affecting graft survival after small-for-size grafts (SFSGs) were used. Between June 1997 and April 2008, 427 patients underwent LDLT with right lobe grafts at the Department of Surgery of Samsung Medical Center. Recipients were divided into 2 groups: group A with a GRWR < 0.8% (n = 35) and group B with a GRWR ≥ 0.8% (n = 392). We retrospectively evaluated the recipient factors, donor factors, and operative factors through the medical records. Small-for-size dysfunction (SFSD) occurred in 2 of 35 patients (5.7%) in group A and in 14 of 392 patients (3.6%) in group B (P = 0.368). Graft survival rates at 1, 3, and 5 years were not different between the 2 groups (87.8%, 83.4%, and 74.1% versus 90.7%, 84.5%, and 79.4%, P = 0.852). However, when we analyzed risk factors within group A, donor age and middle hepatic vein tributary drainage were significant risk factors for graft survival according to univariate analysis (P = 0.042 and P = 0.038, respectively). Donor age was the only significant risk factor for poor graft survival according to multivariate analysis. The graft survival rates of recipients without SFSD tended to be higher than those of recipients with SFSD (85.3% versus 50.0%, P = 0.074). The graft survival rates of recipients with grafts from donors < 44 years old were significantly higher than those of recipients with grafts from donors ≥ 44 years old (92.2% versus 53.6%, P = 0.005). In conclusion, an SFSG (GRWR < 0.8%) can be used safely in adult-to-adult right lobe LDLT when a recipient is receiving the graft from a donor younger than 44 years. Liver Transpl 16:864–869, 2010. © 2010 AASLD.
Analysis of liver transplant outcomes for United Network for Organ Sharing recipients 60 years old or older identifies multiple model for end-stage liver disease-independent prognostic factors
Authors: Aloia Thomas A. , Knight Richard , Gaber Osama A. , Ghobrial Mark R. , Goss John A.
Published: May 2010

Older recipient age is associated with worse posttransplant survival. Although the median age of liver disease patients undergoing orthotopic liver transplantation (OLT) continues to rise, prognostic factors for posttransplant survival specific to older patients have not been defined. To address this issue, the United Network for Organ Sharing/Organ Procurement and Transplantation Network outcome database was searched to identify prognostic factors for the 8070 liver recipients 60 years old or older who underwent transplantation from 1994 to 2005. Prognostic factors were assessed with univariate analysis and multivariate modeling. The 5 strongest prognostic variables (ventilator status, diabetes mellitus, hepatitis C virus, creatinine levels ≥1.6 mg/dL, and recipient and donor age ≥120 years) were aggregated to define a novel older recipient prognostic score (ORPS). The overall 1- and 5-year posttransplant survival rates were 83% and 67%, respectively. The risk model, created by the assignment of 1 point to each ORPS factor, stratified patient outcomes into distinct prognostic groups at the 1-, 3-, and 5-year posttransplant time points (P < 0.001). The 5-year survival rates for patients with ORPS values of 0, 1, and 2 points were 75%, 69%, and 58%, respectively. Patients who underwent transplantation with an ORPS > 2 points consistently experienced 5-year survival rates of less than 50%. In conclusion, in liver transplant recipients 60 years old or older, the ORPS was able to predict significant and clinically relevant differences in posttransplant survival. By optimization of donor selection for recipients over the age of 60 years, clinical utilization of the ORPS model may enhance organ utilization for all patients awaiting OLT. Liver Transpl, 2010. © 2010 AASLD.
Factors affecting hepatocyte isolation, engraftment, and replication in an in vivo model
Authors: Kawahara Toshiyasu , Toso Christian , Douglas Donna N. , Nourbakhsh Mahra , Lewis Jamie T. , Tyrrell David Lorne , Lund Garry A. , Churchill Thomas A. , Kneteman Norman M.
Published: May 2010

Human hepatocyte transplantation is an alternative treatment for acute liver failure and liver diseases involving enzyme deficiencies. Although it has been successfully applied in selected recipients, both isolation and transplantation outcomes have the potential to be improved by better donor selection. This study assessed the impact of various donor variables on isolation outcomes (yield and viability) and posttransplant engraftment, using the SCID/Alb-uPA (severe combined immunodeficient/urokinase type plasminogen activator under the control of an albumin promoter) human liver chimeric mouse model. Human hepatocytes were obtained from 90 human liver donor specimens and were transplanted into 3942 mice. Multivariate analysis revealed improved viability with younger donors (P = 0.038) as well as with shorter warm ischemic time (P = 0.012). Hepatocyte engraftment, assessed by the posttransplant level of serum human α1-antitrypsin, was improved with shorter warm ischemia time. Hepatocytes isolated from older donors (≥60 years) had lower viability and posttransplant engraftment (P ≤ 0.01). In conclusion, the selection of young donors (<60 years) and rapid liver specimen retrieval, allowing for shorter warm ischemia time, are key determinants for the success of both the isolation of high viability human hepatocytes and their subsequent posttransplantation capacity for engraftment and expansion. Liver Transpl 16:974-982, 2010. © 2010 AASLD.
Brand‐consumer storytelling theory and research: Introduction to a Psychology & Marketing special issue
Authors: Woodside Arch G.
Published: May 2010

This introduction reviews core principles of storytelling theory. The article explains basic propositions of good storytelling. A brief summary of each of the six articles that follow appears. The article extends a note of appreciation to the members of the special editorial board for this issue and to Rajan Nataraajan. © 2010 Wiley Periodicals, Inc.
Movement disorders associated with moyamoya disease: A report of 4 new cases and a review of literatures
Authors: Baik Jong Sam , Lee Myung Sik
Published: May 2010

The aim of this study was to define the clinical characteristics of patients who developed movement disorders in association with moyamoya disease (MMD). Using PubMed and medical records of our hospital from 1985 to 2008, we searched for patients who developed movement disorders in association with MMD. This study included 38 patients described in previous studies and 4 patients found in the medical records. The onset of movement disorders was thought to be sudden. In 13 patients, the movement disorders were precipitated by hyperventilation or emotional stress. Twenty‐seven of the 42 patients developed chorea, 4 patients developed dystonia, and 4 developed a mixture of both. The movement disorders of the remaining 7 patients were described as dyskinesia. A third of the 42 patients developed bilateral movement disorders, and their mean age was younger than that of those with unilateral movement disorders. In 37 of the 42 patients, brain imaging studies showed ischemic lesions, but the remaining 5 patients showed no parenchymal lesions. Cerebral perfusion studies showed hypoperfusion in the basal ganglia and in the cerebral cortical areas. Most patients improved whether they were treated or not. MMD must be included in the differential diagnosis of the sudden onset of dyskinesias, particularly chorea and focal dystonia. Even in patients with no parenchymal lesion in brain imaging studies, cerebral angiography and cerebral blood perfusion studies must be performed, if they develop a sudden onset or recurrent movement disorders preceded by emotional stress or hyperventilation. © 2010 Movement Disorder Society
Speech disturbances in patients with dystonia or chorea due to neurometabolic disorders
Authors: Flamand‐Rouvière Constance , Guettard Emilie , Moreau Caroline , Bahi‐Buisson Nadia , Valayannopoulos Vassili , Grabli David , Motte Jacques , Rodriguez Diana , Roubertie Agathe , Maintigneux Lisa , Kemlin Isabelle , Ceballos‐Picot Irène , Adams David , Vidailhet Marie , Roze Emmanuel
Published: May 2010

Speech disturbances are frequent and potentially disabling in patients with dystonia or chorea due to neurometabolic disorders (DCND), but their precise characteristics are poorly documented. We prospectively studied 29 consecutive patients with DCND. A detailed description of their speech patterns was obtained by using the Frenchay dysarthria assessment test and the apraxia of speech evaluation test of Wertz. Gross motor function and intelligibility were each scored on 5‐point scales to identify a possible correlation between the severity of the speech and motor disorders. All the patients were found to have complex speech alterations with combined features of hyperkinetic dysarthria and speech apraxia. We also noted a correlation between the severity of the speech disorders and the motor disorders. These findings have important implications for speech rehabilitation, and may provide new insights into the pathophysiology of dystonia due to neurometabolic disorders. © 2010 Movement Disorder Society
Parkinson's disease symptoms: The patient's perspective
Authors: Politis Marios , Wu Kit , Molloy Sophie , G. Bain Peter , Chaudhuri K. Ray , Piccini Paola
Published: May 2010

Patients suffering from Parkinson's disease (PD) will typically experience a range of motor and nonmotor symptoms during the course of their illness, each of which will affect a particular individual to varying degrees. However, patients' perceptions of troublesome symptoms often differ from the clinician's view, and these discrepancies can hamper effective management of PD. In this study, we have assessed 265 consecutive PD patients by asking them to rank their three most troublesome symptoms in the last 6 months, so to gain further insight from the impact of illness on patients' quality of life. Patients were divided into early (<6 years) and late PD groups (≥6 years) from symptom onset. The division at 6 years was based on the mean time from symptom onset to the development of motor complications. In the early PD group, the 5 most prevalent complaints (ranked in descending order) are slowness, tremor, stiffness, pain, and loss of smell and/or taste. In the advanced PD group, fluctuating response to their medication (most common: wearing‐off phenomenon followed by dyskinesia), mood changes, drooling, sleep problems (most common: middle and late night insomnia followed by daytime sleepiness), and tremor were the top 5. Our findings provide further evidence for the diversity of experience in PD and suggest that as the disease advances the most troublesome issues that patients perceive are the lack of response to medication and the nonmotor aspects of the disease, highlighting the importance of assessment and patient‐centered management in the follow‐up of these patients. © 2010 Movement Disorder Society
Application of Random Forest and Multiple Linear Regression Techniques to QSPR Prediction of an Aqueous Solubility for Military Compounds
Authors: Kovdienko Nikolay A. , Polishchuk Pavel G. , Muratov Eugene N. , Artemenko Anatoly G. , Kuz'min Victor E. , Gorb Leonid , Hill Frances , Leszczynski Jerzy
Published: May 2010

The relationship between the aqueous solubility of more than two thousand eight hundred organic compounds and their structures was investigated using a QSPR approach based on Simplex Representation of Molecular Structure (SiRMS). The dataset consists of 2537 diverse organic compounds. Multiple Linear Regression (MLR) and Random Forest (RF) methods were used for statistical modeling at the 2D level of representation of molecular structure. Statistical characteristics of the best models are quite good (MLR method: R2=0.85, Q2=0.83; RF method: R2=0.99, R2oob=0.88). The external validation set of 301 compounds (including 47 nitro‐, nitroso‐ and nitrogen‐rich compounds of military interest) which were not included in the training set and modeling process, was used for evaluation of the models predictivity. Thus, well‐fitted and robust (R2test(MLR)=0.76 and R2test(RF)=0.82) models were obtained for both statistical techniques using descriptors based on the topological structural information only. The predicted solubility values for military compounds are in good agreement with experimental ones. Developed QSPR models represent powerful and easy‐to‐use virtual screening tool that can be recommended for prediction of aqueous solubility.
Multiplex RARE: A simultaneous multislice spin‐echo sequence that fulfils CPMG conditions
Authors: Lee Kuan J. , Zahneisen Benjamin , Hennig Jürgen , Weigel Matthias , Leupold Jochen
Published: May 2010

This work presents a new imaging sequence in which multiple slices are simultaneously excited and refocused in a spin‐echo train. The multiple spin‐echo trains are interleaved in such a manner that (i) the Carr‐Purcell‐Meiboom‐Gill conditions are fulfilled at all times, and (ii) the signals from slices can be separated, preventing aliasing. This paper also demonstrates how the sequence may be used in a novel fat‐water Dixon method that enables fast volume coverage. The technique is demonstrated in phantoms and in vivo. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Data convolution and combination operation (COCOA) for motion ghost artifacts reduction
Authors: Huang Feng , Lin Wei , Börnert Peter , Li Yu , Reykowski Arne
Published: May 2010

A novel method, data convolution and combination operation, is introduced for the reduction of ghost artifacts due to motion or flow during data acquisition. Since neighboring k‐space data points from different coil elements have strong correlations, a new “synthetic” k‐space with dispersed motion artifacts can be generated through convolution for each coil. The corresponding convolution kernel can be self‐calibrated using the acquired k‐space data. The synthetic and the acquired data sets can be checked for consistency to identify k‐space areas that are motion corrupted. Subsequently, these two data sets can be combined appropriately to produce a k‐space data set showing a reduced level of motion induced error. If the acquired k‐space contains isolated error, the error can be completely eliminated through data convolution and combination operation. If the acquired k‐space data contain widespread errors, the application of the convolution also significantly reduces the overall error. Results with simulated and in vivo data demonstrate that this self‐calibrated method robustly reduces ghost artifacts due to swallowing, breathing, or blood flow, with a minimum impact on the image signal‐to‐noise ratio. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Contrast agent influences MRI phase‐contrast flow measurements in small vessels
Authors: Lagerstrand Kerstin M. , Vikhoff‐Baaz Barbro , Starck Göran , Forssell‐Aronsson Eva
Published: May 2010

Contrast‐enhanced MR angiography is often combined with phase contrast (PC) flow measurement to answer a particular clinical question. The contrast agent that is administered during contrast‐enhanced MR angiography may still be present in the blood during the consecutive PC flow measurement. The aim of this work was to evaluate the influence of contrast agent on PC flow measurements in small vessels. For that purpose, both in vivo measurements and computer simulations were performed. The dependence of the PC flow quantification on the signal amplitude difference between blood and stationary background tissue for various vessel sizes was characterized. Results show that the partial‐volume effect strongly affects the accuracy of the PC flow quantification when the imaged vessel is small compared to the spatial resolution. A higher blood‐to‐background‐contrast level during imaging significantly increases the partial‐volume effect and thereby reduces the accuracy of the flow quantification. On the other hand, a higher blood‐to‐background‐contrast level facilitated the segmentation of the vessel for flow rate determination. PC flow measurements should therefore be performed after contrast agent administration in large vessels, but before contrast agent administration in small vessels. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Accelerated 3D catheter visualization from triplanar MR projection images
Authors: Schirra Carsten Oliver , Weiss Steffen , Krueger Sascha , Caulfield Denis , Pedersen Steen F. , Razavi Reza , Kozerke Sebastian , Schaeffter Tobias
Published: May 2010

One major obstacle for MR‐guided catheterizations is long acquisition times associated with visualizing interventional devices. Therefore, most techniques presented hitherto rely on single‐plane imaging to visualize the catheter. Recently, accelerated three‐dimensional (3D) imaging based on compressed sensing has been proposed to reduce acquisition times. However, frame rates with this technique remain low, and the 3D reconstruction problem yields a considerable computational load. In X‐ray angiography, it is well understood that the shape of interventional devices can be derived in 3D space from a limited number of projection images. In this work, this fact is exploited to develop a method for 3D visualization of active catheters from multiplanar two‐dimensional (2D) projection MR images. This is favorable to 3D MRI as the overall number of acquired profiles, and consequently the acquisition time, is reduced. To further reduce measurement times, compressed sensing is employed. Furthermore, a novel single‐channel catheter design is presented that combines a solenoidal tip coil in series with a single‐loop antenna, enabling simultaneous tip tracking and shape visualization. The tracked tip and catheter properties provide constraints for compressed sensing reconstruction and subsequent 2D/3D curve fitting. The feasibility of the method is demonstrated in phantoms and in an in vivo pig experiment. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Deep venous thrombosis: Diagnostic value of non‐contrast‐enhanced MR venography using electrocardiography‐triggered three‐dimensional half‐fourier FSE
Authors: Ono Atsushi , Murase Kenya , Taniguchi Toshitaka , Shibutani Osamu , Takata Satoru , Kobashi Yasuyuki , Hashiguchi Yusuke , Miyazaki Mitsue
Published: May 2010

We prospectively assessed the diagnostic accuracy of non‐contrast‐enhanced MR venography using both the flow‐refocused fresh‐blood imaging (FR‐FBI) and the swap phase‐encode arterial double‐subtraction elimination (SPADE) techniques for detecting deep vein thrombosis (DVT), as compared using conventional X‐ray venography as the reference standard. Forty‐one legs of 32 consecutive patients (eight men, 24 women; mean age ± standard deviation, 69.4 ± 15.3 years) suspected of having deep vein thrombosis and thus examined using conventional X‐ray venography underwent MR FR‐FBI and SPADE. Twenty‐five of the 32 patients had nonmagnetizing, metal implants they had received during hip or leg surgery. Two radiologists independently assessed the MR venograms as either diagnostic or nondiagnostic and with either the presence or absence of thrombi. The sensitivities of FR‐FBI and SPADE for diagnosing thrombus were 100% (53 of 53) for both reviewers. Nondiagnostic segments were excluded from this analysis. The corresponding specificities were 100% (238 of 238 for reviewer A) and 99.6% (237 of 238 for reviewer B). The interobserver agreement regarding the MR images for the assessment of thrombosis was high (κ = 0.92). Non‐contrast‐enhanced MR venography using SPADE and FR‐FBI is highly accurate and reproducible for diagnosing DVT. This is especially advantageous for patients who have received nonmagnetizing, metal implants during orthopedic surgery. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Measurement of perfusion and permeability from dynamic contrast‐enhanced MRI in normal and pathological vertebral bone marrow
Authors: Biffar Andreas , Sourbron Steven , Schmidt Gerwin , Ingrisch Michael , Dietrich Olaf , Reiser Maximilian F. , Baur‐Melnyk Andrea
Published: May 2010

Dynamic contrast‐enhanced MRI data in vertebral bone marrow (vBM) are currently analyzed with descriptive indices. The purpose of this study was to develop and evaluate a quantitative approach, considering the tissue composition of vBM. Therefore, a measurement of the water fraction, fwat, and the precontrast relaxation times, T10 wat, T10 fat, was added to the routine protocol. Signal analysis was generalized by allowing for an arbitrary fraction of fat. Plasma flow, plasma volume, extraction flow, and interstitial volume were determined from dynamic contrast‐enhanced‐MRI data. Simulations were used to determine the sensitivity to the precontrast values and to retrospectively verify the choice of the sequence parameters. Measurements were performed in healthy vertebral bodies (n = 30) and lesions of 15 patients with vertebral fractures. Extraction flow (milliliters per 100 mL/min) provided the strongest normal/abnormal separation: mean (standard deviation) was 0.3 (0.8) in healthy vBM and 6(4) in the fractures. Neglecting the fat component and the approximated signal analysis using relative signal enhancement produced significant differences. We conclude that correcting for the fat component in the signal and parametrization by tracer‐kinetic analysis is necessary to avoid misinterpretation and/or systematic errors. The quantitative analysis is equally well suited as a descriptive parameter for the differentiation between normal and abnormal vertebral bone marrow. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
O‐space imaging: Highly efficient parallel imaging using second‐order nonlinear fields as encoding gradients with no phase encoding
Authors: Stockmann Jason P. , Ciris Pelin Aksit , Galiana Gigi , Tam Leo , Constable R. Todd
Published: May 2010

Recent improvements in parallel imaging have been driven by the use of greater numbers of independent surface coils placed so as to minimize aliasing along the phase‐encode direction(s). However, gains from increasing the number of coils diminish as coil coupling problems begin to dominate and the ratio of acceleration gain to expense for multiple receiver chains becomes prohibitive. In this work, we redesign the spatial‐encoding strategy in order to gain efficiency, achieving a gradient encoding scheme that is complementary to the spatial encoding provided by the receiver coils. This approach leads to “O‐space” imaging, wherein the gradient shapes are tailored to an existing surface coil array, making more efficient use of the spatial information contained in the coil profiles. In its simplest form, for each acquired echo the Z2 spherical harmonic is used to project the object onto sets of concentric rings, while the X and Y gradients are used to offset this projection within the imaging plane. The theory is presented, an algorithm is introduced for image reconstruction, and simulations reveal that O‐space encoding achieves high encoding efficiency compared to sensitivity encoding (SENSE) radial k‐space trajectories, and parallel imaging technique with localized gradients (PatLoc), suggesting that O‐space imaging holds great potential for accelerated scanning. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Prospective motion correction for single‐voxel 1H MR spectroscopy
Authors: Keating Brian , Deng Weiran , Roddey J. Cooper , White Nathan , Dale Anders , Stenger V. Andrew , Ernst Thomas
Published: May 2010

Head motion during 1H MR spectroscopy acquisitions may compromise the quality and reliability of in vivo metabolite measurements. Therefore, a three‐plane image‐based motion‐tracking module was integrated into a single‐voxel 1H MR spectroscopy (point‐resolved spectroscopy) sequence. A series of three orthogonal spiral navigator images was acquired immediately prior to the MR spectroscopy water suppression module in order to estimate head motion. By applying the appropriate rotations and translations, the MR spectroscopy voxel position can be updated such that it remains stationary with respect to the brain. Frequency and phase corrections were applied during postprocessing to reduce line width and restore coherent averaging. Spectra acquired during intentional head motion in 11 volunteers demonstrate reduced lipid contamination and increased spectral reproducibility when motion correction is applied. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Analytical solutions for advective–dispersive solute transport in double‐layered finite porous media
Authors: Li Yu‐Chao , Cleall Peter John
Published: May 2010

Analytical solutions for advection and dispersion of a conservative solute in a one‐dimensional double‐layered finite porous media are presented. The solutions are applicable to five scenarios that have various combinations of fixed concentration, fixed flux and zero concentration gradient conditions at the inlet and outlet boundaries that provide a wide number of options. Arbitrary initial solute concentration distributions throughout the media can be considered via explicit formulations or numerical integration. The analytical solutions presented have been verified against numerical solutions from a finite‐element‐based approach and an existing closed‐form solution for double‐layered media with an excellent correlation being found in both cases. A practical application pertaining to advective transport induced by consolidation of underlying sediment layers on contaminant movement within a capped contaminated sediment system is presented. Comparison of the calculated concentrations and fluxes with alternative approaches clearly illustrates the need to consider advection processes. Consideration of the different features of contaminant transport due to varying pore‐water velocity fields in primary consolidation and secondary consolidation stages is achieved via the use of non‐uniform initial concentration distributions within the proposed analytical solutions. Copyright © 2010 John Wiley & Sons, Ltd.
Anisotropic model of damage for geomaterials and concrete
Authors: Alliche Abdenour , Dumontet Helene
Published: May 2010

A damage model for geomaterials and concrete is proposed. This model expresses the anisotropic character induced by the degradation of material. The law of behavior obtained by differentiation of the free energy shows the dissymmetry effect observed in traction–compression loading and the residual strains caused by the damage.

The present approach requires the identification of a reduced number of parameters having a clear physical significance. An application to the case of the uniaxial traction–compression loading shows a good adequacy with the experimental observations. Copyright © 2010 John Wiley & Sons, Ltd.
A macroelement formulation for shallow foundations on cohesive and frictional soils
Authors: Chatzigogos C. T. , Figini R. , Pecker A. , Salençon J.
Published: May 2010

The scope of this paper is to present a macroelement model for shallow foundations encompassing the majority of combinations of soil and foundation–soil interface conditions that are interesting for practical applications. The basic idea of the formulation is to raise the common assumption that the surface of ultimate loads of the foundation is identified as a yield surface in the space of force parameters which the footing is subjected to. Instead, each non‐linear mechanism participating in the global response of the system is modelled independently and the surface of ultimate loads is retrieved as the combined result of all active mechanisms. This allows formulating each mechanism by respecting its particular characteristics and offers the possibility of activating, modifying or deactivating each mechanism according to the context of application. The model comprises three non‐linear mechanisms: (a) the mechanism of sliding at the soil–footing interface, (b) the mechanism of soil yielding in the vicinity of the footing and (c) the mechanism of uplift as the footing may get detached from the soil. The first two are irreversible and dissipative and are combined within a multi‐mechanism plasticity formulation. The third mechanism is reversible and non‐dissipative. It is reproduced with a phenomenological non‐linear hyperelastic model. The model is validated with respect to the existing results for shallow foundations under quasi‐static loading tests. It is shown that although the ultimate surface of the foundation is not explicitly used in the formulation of the model, the obtained force states by the model are always contained within it. Copyright © 2010 John Wiley & Sons, Ltd.
Developing elasto‐plastic models without establishing any expression for the yield function
Authors: Sands C. M. , Chandler H. W. , Guz I. A.
Published: May 2010

This paper presents a procedure for developing elasto‐plastic material models from a dissipation function and kinematic constraint that obviates the need to establish an expression for the yield function. This method could be applied to a wide range of different materials, but it is particularly suitable for testing new models of granular materials. This is because there is often a difficulty associated with finding an algebraic expression for the yield function for appropriate dissipation functions combined with realistic dilatancy rules. The procedure presented in this paper allows the approach to fulfill its potential for the easy incorporation of physical insight into the dissipation function and kinematic constraint without being hindered by algebraic complexity. The method is applied to the familiar von Mises model and also to a model for granular materials that incorporates a realistic dilatancy rule and extends into three dimensions a model presented in earlier work. Copyright © 2010 John Wiley & Sons, Ltd.
Preconditioners in computational geomechanics: A survey
Authors: Gambolati G. , Ferronato M. , Janna C.
Published: May 2010

The finite element (FE) solution of geomechanical problems in realistic settings raises a few numerical issues depending on the actual process addressed by the analysis. There are two basic problems where the linear solver efficiency may play a crucial role: 1. fully coupled consolidation and 2. faulted uncoupled consolidation. A class of general solvers becoming increasingly popular relies on the Krylov subspace (or Conjugate Gradient‐like) methods, provided that an efficient preconditioner is available. For both problems mentioned above, the possible preconditioners include the diagonal scaling (DS), the Incomplete LU decomposition (ILU), the mixed constraint preconditioning (MCP) and the multilevel incomplete factorization (MIF). The development and the performance of these algorithms have been the topic of several recent works. The present paper aims at providing a survey of the preconditioners available to date in computational geomechanics. In particular, a review and a critical discussion of DS, ILU, MCP and MIF are given along with some comparative numerical results. Copyright © 2010 John Wiley & Sons, Ltd.
Robust reliable control for discrete‐time‐delay systems with stochastic nonlinearities and multiplicative noises
Authors: Liu Yisha , Wang Zidong , Wang Wei
Published: May 2010

This paper is concerned with the reliable control problem against actuator failures for a class of uncertain discrete‐time stochastic nonlinear time‐delay systems. The failures of actuators are quantified by a variable varying in a given interval. The stochastic nonlinearities described by statistical means cover several well‐studied nonlinear functions as special cases. The time‐varying delay is unknown with given lower and upper bounds. The multiplicative stochastic disturbances are in the form of a scalar Gaussian white noise with unit variance. Attention is focused on the analysis and design of a stable controller such that, for all possible actuator failures, stochastic nonlinearities and disturbances, time delays and admissible parameter uncertainties, the closed‐loop system is exponentially mean‐square stable. A linear matrix inequality approach is developed to solve the addressed problem. A numerical example is given to demonstrate the effectiveness of the proposed design approach. Copyright © 2010 John Wiley & Sons, Ltd.
Elevated TGFβ–Smad signalling in experimental Pkd1 models and human patients with polycystic kidney disease
Authors: Hassane Sabrine , Leonhard Wouter N , van der Wal Annemieke , Hawinkels Lukas JAC , Lantinga‐van Leeuwen Irma S , Dijke Peter ten , Breuning Martijn H , Heer Emile de , Peters Dorien JM
Published: May 2010

Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited renal disease characterized by many fluid‐filled cysts and interstitial fibrosis in the kidneys, leading to chronic renal failure. During cystogenesis the renal tubules undergo extensive structural alterations that are accompanied by altered cellular signalling, directly and/or indirectly regulated by the PKD1 and PKD2 proteins. Since transforming growth factor (TGF)‐β signalling modulates cell proliferation, differentiation, apoptosis, adhesion and migration of various cell types, we studied the activation of this signalling pathway in Pkd1‐mutant mouse models at different stages of the disease. Therefore, we analysed expression of the TGFβ–Smad signalling pathway and its target genes in different Pkd1 mutant mouse models in various stages of polycystic disease. Nuclear accumulation of P‐Smad2 in cyst lining epithelial cells was not observed in the initiation phase but was observed at mild and more advanced stages of PKD. This coincides with mild fibrosis and increased mRNA levels of TGFβ target genes, such as fibronectin, collagen type I, plasminogen activator inhibitor 1 and matrix metalloproteinase‐2. At this stage many interstitial fibroblasts were found around cysts, which also showed nuclear localization for P‐Smad2. However, bone morphogenetic protein (BMP) signalling, which can antagonize TGFβ signalling, is not affected, since nuclear expression of P‐Smad1/5/8 and expression of the BMP target gene, inhibitor of DNA binding/differential‐1 (ID‐1) is not altered compared to wild‐type controls. Also, human kidneys with progressive ADPKD showed increased nuclear localization of P‐Smad2, while in general expression of P‐Smad1/5/8 was weak. These results exclude TGFβ signalling at the initiation of cystogenesis, but indicate an important role during cyst progression and in fibrogenesis of progressive ADPKD. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Factors associated with the use of corticosteroids in the initial management of idiopathic pulmonary fibrosis
Authors: Munson Jeffrey C. , Kreider Maryl , Chen Zhen , Christie Jason D. , Kimmel Stephen E.
Published: May 2010

Purpose

Idiopathic pulmonary fibrosis (IPF) has not been shown to respond to corticosteroid therapy; however, many patients receive these drugs at the time of diagnosis. The factors that are associated with the decision to prescribe corticosteroids have not been examined.

Methods

We conducted a retrospective cohort study of 1126 patients with a new diagnosis of IPF using The Health Improvement Network (THIN) database from the United Kingdom. We used generalized estimating equation (GEE) regression models to test the association of patient characteristics, co‐morbid diseases, and disease characteristics with the use of corticosteroids within 30 days of IPF diagnosis.

Results

Bivariable analyses demonstrated an association between female sex, the presence of dyspnea, the need for oxygen, past steroid use, and the use of corticosteroids immediately prior to diagnosis with the use of corticosteroids at the time of diagnosis. After adjustment with multivariable GEE regression, only the use of oxygen at the time of diagnosis (OR 1.69, CI 1.14–2.49), the past use of corticosteroids (OR 1.50, CI 1.04–2.15), and use of corticosteroids immediately prior to diagnosis (OR 5.72, CI 3.80–8.60) remained significantly associated with the use of corticosteroids immediately following diagnosis. No association was found between prior diabetes, osteoporosis, glaucoma, hypertension, congestive heart failure, obesity, or peptic ulcer disease and use of corticosteroids at diagnosis.

Conclusions

The decision to prescribe corticosteroids is associated with oxygen use and past corticosteroid use but is not influenced by factors such as age, gender, or common co‐morbid conditions that may pre‐dispose patients to adverse events of therapy. Copyright © 2010 John Wiley & Sons, Ltd.
Drift‐diffusion model for intermediate band solar cells including photofilling effects
Authors: Strandberg Rune , Reenaas Turid Worren
Published: May 2010

A novel drift‐diffusion model for intermediate band solar cells (IBSC) is presented. The model differs from previous drift‐diffusion models by allowing the carrier concentrations in all three bands to vary. It is developed for the idealized case where only radiative recombination occurs and where the IB has zero width. The model is used to compare the performance of IBSCs where the IB‐region is doped to get a partially filled IB (prefilled IBSC) to IBSCs where the IB‐region is not doped to partially fill the IB (photofilled IBSC). Numerical results show that a photofilled IBSC can achieve high efficiencies when operated under concentrated light. In fact, for some particular cases, a photofilled cell will perform better than a prefilled cell. The optimal degree of prefilling, i.e. the ratio of the concentration of doping atoms to the total number of IB‐states, is found for a particular example. It is also examined how the carrier concentrations in all three bands, the conduction, the intermediate and the valence bands, vary in prefilled and photofilled IBSCs. Finally, the band diagrams of a prefilled and photofilled IBSC are discussed. Copyright © 2010 John Wiley & Sons, Ltd.
Investigation of bulk and solar cell properties of ingots cast from compensated solar grade silicon
Authors: Modanese Chiara , Di Sabatino Marisa , Søiland Anne‐Karin , Peter Kristian , Arnberg Lars
Published: May 2010

In this work, the effect of the concurrent presence of B and P on bulk and solar cell properties of directionally solidified multicrystalline ingots from commercially compensated solar grade silicon (SoG‐Si) feedstock produced by Elkem Solar was investigated. The initial B and P content prior to the directional solidification experiment was 1260 and 762 ppba, respectively. Two reference ingots have been solidified in a silica crucible from 100% electronic grade silicon (EG‐Si) feedstock, with 332 ppba of boron added. All ingots have been cast under similar process parameters. The resistivity measurements by Four Point Probe (FPP) are in good agreement with the net dopant content, i.e., NA − ND for p‐type material, measured by Glow Discharge Mass Spectrometer (GDMS). Bulk lifetime measurements show a decrease in the values compared to the EG reference. Lifetime distributions show the highest values of 13 and 19 µs at approximately half ingot height, compared to 30 and 44 µs in the reference ingots. This decrease can be due to the concurrent effect of compensation and of other impurities present in the ingot. However, the content of several transition metals measured by GDMS at half ingot height was not significantly higher than that of the reference ingots. Oxygen content as measured by Fourier Transform Infra‐Red (FTIR) spectroscopy shows no significant difference compared to the references. Solar cells made from the compensated ingots and processed under standard process conditions show efficiency values up to 15.5% and fill factor values up to 78%, comparable to conventional multicrystalline silicon cells. Copyright © 2010 John Wiley & Sons, Ltd.