bluuebunny/crossref_metadata_2025 huggingface dataset:
Vision: are models of object recognition catching up with the brain?
Authors: Poggio Tomaso , Ullman Shimon
Published: June 2013

Object recognition has been a central yet elusive goal of computational vision. For many years, computer performance seemed highly deficient and unable to emulate the basic capabilities of the human recognition system. Over the past decade or so, computer scientists and neuroscientists have developed algorithms and systems—and models of visual cortex—that have come much closer to human performance in visual identification and categorization. In this personal perspective, we discuss the ongoing struggle of visual models to catch up with the visual cortex, identify key reasons for the relatively rapid improvement of artificial systems and models, and identify open problems for computational vision in this domain.
Development of ipilimumab: a novel immunotherapeutic approach for the treatment of advanced melanoma
Authors: Wolchok Jedd D. , Hodi F. Stephen , Weber Jeffrey S. , Allison James P. , Urba Walter J. , Robert Caroline , O'Day Steven J. , Hoos Axel , Humphrey Rachel , Berman David M. , Lonberg Nils , Korman Alan J.
Published: June 2013

The immunotherapeutic agent ipilimumab has helped address a significant unmet need in the treatment of advanced melanoma. Ipilimumab is a fully human monoclonal antibody that targets cytotoxic T‐lymphocyte antigen‐4 (CTLA‐4), thereby augmenting antitumor immune responses. After decades in which a number of clinical trials were conducted, ipilimumab was the first therapy to improve overall survival in a randomized, controlled phase III trial of patients with advanced melanoma. These results led to the regulatory approval of ipilimumab at 3 mg/kg for the treatment of unresectable or metastatic melanoma. More than 17,000 patients worldwide have received ipilimumab, either as a commercial drug at 3 mg/kg or in clinical trials and expanded access programs at different doses. Consistent with its proposed mechanism of action, the most common toxicities associated with ipilimumab therapy are inflammatory in nature. These immune‐related adverse events were mostly reversible when effective treatment guidelines were followed. Importantly, long‐term follow‐up of patients who received ipilimumab in a phase III trial showed that 24% survived at least two years, and in phase II studies, a proportion of patients survived at least five years. Evaluation of ipilimumab is ongoing in the adjuvant setting for melanoma, and for advanced disease in nonsmall cell lung, small cell lung, prostate, ovarian, and gastric cancers.
Oral osteolipoma: a case report
Authors: Shabbir F. , Putnam G.
Published: June 2013

We present the case of a 58‐year‐old female with an oral osteolipoma. Radiographic and histological features are discussed, along with a differential diagnosis and review of the literature.
Micafungin versus fluconazole for prophylaxis against fungal infections in premature infants
Authors: Maede Yoshinobu , Ibara Satoshi , Nagasaki Hiraku , Inoue Takeshi , Tokuhisa Takuya , Torikai Motofumi , Ishihara Chie , Matsui Takako , Kodaira Yuichi
Published: June 2013

Background

We conducted a comparative clinical study to evaluate the prophylactic effects of micafungin (MCFG) and fluconazole (FLCZ) on the incidence of fungal infections in extremely low‐birthweight infants who were born at a gestational age of less than 26 weeks and weighed less than 1000 g.

Methods

With a combination of enteral administration of miconazole (6 mg/kg/day), FLCZ and MCFG were administered intravenously at a dose of 5 mg/kg/day and 3 mg/kg/day, respectively. The prophylaxis was classified as a failure when fungal infections were identified within the first 21 days after birth.

Results

The prophylaxis was successful in seven of 18 cases (39%) in the FLCZ group and 15 of 21 cases (71%) in the MCFG group, indicating that the success rate was significantly higher in the latter group.

Conclusion

MCFG was superior to FLCZ as prophylaxis against fungal infections in extremely low‐birthweight infants.
EBV‐positive low‐grade marginal zone lymphoma in the breast with massive amyloid deposition arising in a heart transplant patient: A report of an unusual case
Authors: Nassif Samer , Ozdemirli Metin
Published: June 2013

According to the 2008 World Health Organization classification, low‐grade lymphomas arising in transplant recipients are not considered as specific types of PTLD. Most such cases are not associated with EBV infections, although rare reports of post‐transplant marginal zone lymphoma have been described. We describe the case of an 18‐yr‐old female with history of heart transplant who developed a breast mass, but was otherwise completely asymptomatic. Surgical excision of the mass and histopathologic examination showed a low‐grade B‐cell lymphoma most consistent with marginal zone lymphoma with massive amyloid deposition; furthermore, numerous tumor cells were positive for EBV by in situ hybridization for EBV‐encoded RNA. The patient was treated with reduction in immunosuppression, and no additional lesions developed. This case describes an atypical presentation of post‐transplant low‐grade B‐cell lymphoma, unusual in its location, histopathologic features, and association with EBV, thereby adding to the rare previous accounts of such an entity, suggesting the need to include post‐transplant marginal zone lymphomas in the current classification of PTLD, and helping in determining the optimal treatment modalities for such tumors.
Pregnancy and Birth Cohort Resources in Europe: a Large Opportunity for Aetiological Child Health Research
Authors: Larsen Pernille Stemann , Kamper‐Jørgensen Mads , Adamson Ashley , Barros Henrique , Bonde Jens Peter , Brescianini Sonia , Brophy Sinead , Casas Maribel , Devereux Graham , Eggesbø Merete , Fantini Maria Pia , Frey Urs , Gehring Ulrike , Grazuleviciene Regina , Henriksen Tine Brink , Hertz‐Picciotto Irva , Heude Barbara , Hryhorczuk Daniel O. , Inskip Hazel , Jaddoe Vincent W.V. , Lawlor Debbie A , Ludvigsson Johnny , Kelleher Cecily , Kiess Wieland , Koletzko Berthold , Kuehni Claudia Elisabeth , Kull Inger , Kyhl Henriette Boye , Magnus Per , Momas Isabelle , Murray Dierdre , Pekkanen Juha , Polanska Kinga , Porta Daniela , Poulsen Gry , Richiardi Lorenzo , Roeleveld Nel , Skovgaard Anne Mette , Sram Radim J. , Strandberg‐Larsen Katrine , Thijs Carel , Van Eijsden Manon , Wright John , Vrijheid Martine , Andersen Anne‐Marie Nybo
Published: June 2013

Background

During the past 25 years, many pregnancy and birth cohorts have been established. Each cohort provides unique opportunities for examining associations of early‐life exposures with child development and health. However, to fully exploit the large amount of available resources and to facilitate cross‐cohort collaboration, it is necessary to have accessible information on each cohort and its individual characteristics. The aim of this work was to provide an overview of European pregnancy and birth cohorts registered in a freely accessible database located at http://www.birthcohorts.net.

Methods

European pregnancy and birth cohorts initiated in 1980 or later with at least 300 mother–child pairs enrolled during pregnancy or at birth, and with postnatal data, were eligible for inclusion. Eligible cohorts were invited to provide information on the data and biological samples collected, as well as the timing of data collection.

Results

In total, 70 cohorts were identified. Of these, 56 fulfilled the inclusion criteria encompassing a total of more than 500 000 live‐born European children. The cohorts represented 19 countries with the majority of cohorts located in Northern and Western Europe. Some cohorts were general with multiple aims, whilst others focused on specific health or exposure‐related research questions.

Conclusion

This work demonstrates a great potential for cross‐cohort collaboration addressing important aspects of child health. The web site, http://www.birthcohorts.net, proved to be a useful tool for accessing information on European pregnancy and birth cohorts and their characteristics.
Hydrothermal dolomitization in a complex geodynamic setting (Lower Palaeozoic, northern Spain)
Authors: lapponi Fabio , Bechstädt Thilo , Boni Maria , Banks David A. , Schneider Jens
Published: June 2013

Burial hydrothermal dolomitization is a common diagenetic modification in sedimentary basins with implications for oil and gas reservoir performance. Outcrop analogues represent an easily accessible source of data to refine the genetic models and assess risk in hydrocarbon exploration and production. The Palaeozoic succession of northern Spain contains numerous excellent exposures of epigenetically dolomitized limestones, particularly in the Carboniferous and Cambrian. The epigenetic dolomites in the Cambrian carbonates of the Láncara Formation are volumetrically small, but have a large aerial distribution across different tectonic units of the Variscan fold and thrust belt. Coarse crystals, abundant saddle dolomite cement, negative δ18O and fluid inclusion homogenization temperatures between 80°C and 120°C characterize these dolomites, which are petrographically and geochemically similar to the tens of kilometre‐sized hydrothermal dolomites replacing the Upper Carboniferous succession in the same area. In both cases, the dolomitizing fluids are derived from highly evaporated sea water, modified to a limited degree through fluid‐rock interaction. The dolomitization events affecting both Cambrian and Carboniferous strata are probably related to the same post‐orogenic hydrothermal fluid flow. The formation of the post‐collisional (latest Carboniferous) Cantabrian arc fostered dolomitization: the extension related to bending of the arc generated deep‐reaching faults and strike‐slip movements, which favoured the circulation of hot dolomitizing fluids in the outer parts of this orocline. A similar dolomitization process affected other areas of Europe after the main stages of the Variscan orogeny. Dolomitization was a continuous, uninterrupted, isochemical process. Limestone replacement resulted in a major porosity redistribution and focused the fluid flow into the newly created porous zones. Replacement was followed immediately by partial to complete cementation of the pores (including zebra fabrics and vugs) with saddle dolomite. The amount of porosity left depends on the volume of cement and therefore on the volume of fluids available.
Zero Tolerance forGMFlax and the Rules of Trade
Authors: Viju Crina , Yeung May T. , Kerr William A.
Published: June 2013

Trade in genetically modified products is a longstanding and contentious issue in agricultural trade. One issue has not, as yet, received much attention. This is the mingling of unapprovedGMproducts with conventional products. This issue is likely to gain more prominence in the future as newGMproduct development accelerates. Until recently, problems with mingling were largely one‐off events. Recently, however, an ongoing case of mingling has arisen – the case of CanadianGMflax in theEU. The case led to an embargo of imports from Canada and subsequently the bilateral negotiation of a protocol to allow exports to resume. The case raises a number of important issues pertaining to the objective of zero tolerance policies forGMproducts, the operationalisation of zero tolerance, the role of the testing industry, the design of testing regimes and the risks associated with the absence of transparency and/or international standardisation. It is concluded that mingling is a topic that is deserving of multilateral attention.
State‐owned Enterprises, Exporting and Productivity inChina: A Stochastic Dominance Approach
Authors: Elliott Robert , Zhou Ying
Published: June 2013

A popular explanation forChina's rapid economic growth in recent years has been the dramatic increase in the number of private domestic‐ and foreign‐owned firms and a decline in the state‐owned sector. However, recent evidence suggests thatChina's state‐owned enterprises (SOEs) are in fact stronger than ever. In this paper, we examine over 78,000 manufacturing firms between 2002 and 2006 to investigate the relationship between ownership structure and the degree of firm‐level exposure to export markets and firm‐level productivity. Using a conditional stochastic dominance approach, we reveal that although our results largely adhere to prior expectations, the performance ofSOEs differs markedly between those that export and those that supply the domestic market only. It appears thatChina's internationally focusedSOEs have become formidable global competitors.
Evaluation of a test for its suitability in the diagnosis of variant Creutzfeldt–Jakob disease
Authors: Cooper J. K. , Andrews N. , Ladhani K. , Bujaki E. , Minor P. D.
Published: June 2013

Background and Objectives

Evaluation of variant Creutzfeldt–Jakob disease (vCJD) diagnostic/donor screening tests is made complicated by the very limited supply of blood samples from clinically confirmed cases of vCJD. To determine appropriate access for test developers to rare Creutzfeldt–Jakob disease (CJD) blood samples, the oversight committee of the NIBSC CJD Resource Centre has developed a process and protocols detailing minimum requirements for both test sensitivity and specificity. This protocol is broadly similar to that outlined in the common technical specification (European Directive 98/79/EC).

Materials and Methods

Tests are subjected to a stepwise evaluation (step 1). vCJD tissue homogenates spiked into pooled human plasma (step 2). Blood samples from animals known to be incubating (Transmissible spongiform encephalopathy) TSE disease (scrapie/Bovine Spongiform encephalopathy (BSE)‐infected sheep, BSE‐infected primates) and appropriate controls (step 3). Fresh or frozen plasma from normal UK blood donors and (step 4). Plasma samples from individuals with confirmed clinical stage variant CJD (transfusion transmission) or sporadic CJD (no evidence of blood transmission).

Results

The assay evaluated performed with good sensitivity with vCJD‐spiked tissue homogenates, poor sensitivity for ovine TSE‐infected blood samples and failed with plasma from BSE‐infected non‐human primates and with true vCJD clinical samples.

Conclusions

The test evaluated here is currently unsuitable for use in blood donor screening or diagnosis using blood.
Anti‐leucocyte antibodies in platelet apheresis donors with and without prior immunizing events: implications for TRALI prevention
Authors: Sigle J.‐P. , Thierbach J. , Infanti L. , Muriset M. , Hunziker G. , Chassot K. , Niederhauser C. , Gowland P. , Holbro A. , Sunic K. , Buser A. , Fontana S.
Published: June 2013

Background and Objectives

Transfusion‐related acute lung injury (TRALI) prevention strategies in platelet (PLT) apheresis donors focus on identifying antileucocyte antibody‐positive donors. The use of microbead based assays for screening purposes is hampered by the lack of a consensus cut‐off for TRALI prevention and the undefined role of anti‐leucocyte antibodies in never‐alloexposed donors. This study evaluated anti‐leucocyte antibody assays in PLT apheresis donors with and without prior immunizing events with special focus on microbead assay cut‐offs, antibody specificities and their potential significance in never‐alloexposed donors.

Material and Methods

Blood samples of male and female PLT apheresis donors with and without history of prior immunization were tested for anti‐leucocyte antibodies.

Results

Of 262 female and 118 male PLT apheresis donors, 37·4% had prior immunizing events. Fifty‐eight of 238 (24·4%) donors without prior immunizing event had anti‐HLA antibodies confirmed in microbead single antigen assay (mean fluorescence intensity (MFI) >500). Even with a cut‐off MFI >3000, anti‐HLA antibodies were detected in 10·6% of female and 4·3% of male donors without history of immunization. Of the antibody specificities found, 6 of 17 (35·3%) anti‐HLA‐A, 4 of 8 (50·0%) anti‐HLA‐B and 4 of 6 (66·6%) anti‐HLA class II antibodies have been detected in donors associated with TRALI cases in the literature.

Conclusion

Platelet apheresis donors without history of immunization have anti‐leucocyte antibodies that potentially can cause TRALI. In our opinion, this cohort should be included in screening strategies for TRALI prevention. As references and consensus cut‐offs have not yet been established, it is premature to use microbead assays as standard for donor screening.
Erythropoietin‐stimulated endothelial cells support erythroid cell differentiation of CD34(+) haematopoietic progenitors
Authors: Zaid T. , Frömmel C. , Lun A. , Moldenhauer A.
Published: June 2013

Background and Objectives

Endothelial cells provide a unique medium for the proliferation and white lineage differentiation of haematopoietic progenitor cells (HPC). Whether this quality can be exploited to facilitate the differentiation of erythroid precursors is not yet known.

Materials and Methods

Haematopoietic progenitor cells derived from cord blood were cultured for 3 weeks in erythropoietin‐stimulated supernatants with (n = 6) or without cyclosporine A (CSA, n = 6). Cell count, phenotype and morphology were assessed on a weekly basis, and the haemoglobin content was analysed. These cultures were compared with erythroid differentiation induced by cytokines only (n = 6).

Results

Endothelial supernatants combined with CSA led to equivalent numbers of CD71(+) erythroblasts after 1 week as cytokines only. The purity of glycophorin‐positive, CD45‐negative cells was higher in cells generated in endothelial supernatants than in cytokine‐based media. Additional prostaglandin E2 induced a change from fetal to adult haemoglobin.

Conclusion

For the generation of erythroblasts from HPC, endothelial supernatants are a simple and cost‐effective alternative to culture conditions based on cytokines.
Evaluating Wildlife as a Potential Source of Salmonella serotype Newport (JJPX01.0061) Contamination for Tomatoes on the Eastern Shore of Virginia
Authors: Gruszynski K. , Pao S. , Kim C. , Toney D. , Wright K. , Ross P. G. , Colon A. , Levine S.
Published: June 2013

Eastern Shore of Virginia red, round tomatoes contaminated with Salmonella serotype Newport pattern JJPX01.0061 have been a source of several multistate outbreaks within the last 10 years. No source of the contamination has yet been identified. The goal of this study was to evaluate wildlife as a potential source of contamination. Faecal samples from deer, turtles and birds were collected between November 2010 and July 2011 from seventeen locations on the Eastern Shore of Virginia. A total of 262 samples were tested for the presence of Salmonella using an enzyme‐linked immunosorbent assay (ELISA). A total of 23 (8.8%) samples tested positive for Salmonella spp. and were further characterized by serotyping and pulsed‐field gel electrophoresis (PFGE) subtyping. Overall, twelve serotypes were identified, including Salmonella serotype Javiana, another common serotype associated with tomato‐related outbreaks. Only one avian sample collected in July 2011 was determined to be positive for S. Newport pattern 61. This sample was collected from the ground at a site where birds, mostly gulls, were congregating. Although many of the avian samples from this site were dry, the site yielded eleven positive Salmonella samples. This suggests that certain Salmonella serotypes may persist in the environment despite extreme conditions. The recovery of one Newport pattern 61 isolate alone does not yield much information regarding the environmental reservoirs of this pathogen, but when combined with other data including the recovery of several isolates of Javiana from birds, it suggests that birds might be a potential source of Salmonella contamination for tomatoes on the Eastern Shore.
Unsteady Flow of Magneto Thermomicropolar Fluid in a Porous Channel With Peristalsis: Unsteady Separation
Authors: Abd Elmaboud Y.
Published: June 2013

The magneto thermodynamic aspects of micropolar fluid (blood model) through an isotropic porous medium in a nonuniform channel with rhythmically contracting walls have been investigated. The flow analysis has been discussed under long wavelength and low Reynolds number approximations. The closed form solutions are obtained for velocity components, microrotation, heat transfer, as well as the wall vorticity. The modified Newton–Raphson method is used to predict the unsteady flow separation points along the peristaltic wall. Numerical computations have been carried out for the pressure rise per wavelength. The study shows that peristaltic transport, fluid velocity, microrotation velocity, and wall shear stress are significantly affected by the nonuniform geometry of the blood vessels. Moreover, the amplitude ratio, the coupling number, the micropolar parameter, and the magnetic parameter are important parameters that affect the flow behavior.
Comparison of Performance Losses Between Ultrasonic and Thermal Bonding of Membrane Electrode Assemblies in Proton Exchange Membrane Fuel Cells
Authors: Beck Joseph , Walczyk Daniel , Buelte Steve , Hoffman Casey
Published: June 2013

Ultrasonic bonding of low-temperature PEM membrane electrode assembly (MEA) components together has been shown previously to cut both cycle time and energy input of that manufacturing step by over an order of magnitude as compared to the industry standard of thermal pressing. This paper compares performance between ultrasonically and thermally bonded low-temperature MEAs and characterizes the performance losses from the new bonding process. A randomized, full factorial experiment was designed and conducted to examine performance of MEAs with 10 cm2 active area while varying three factors: bonding method (ultrasonically and thermally pressed using previously optimized bonding parameters), membrane condition (dry and conditioned Nafion® 115), and electrode catalyst loading (0.16 and 0.33 mg Pt/cm2). Ultrasonic MEAs performed as well as their thermal MEAs across all tested current densities with pure oxygen supplied to the cathode. However, thermal MEAs outperformed ultrasonic MEAs at current densities above 0.4 A/cm2 with air supplied to the cathode. Impedance spectroscopy, cyclic voltammetry, and flow sensitivity analyses were used to characterize the performance losses of the ultrasonic MEAs. The data suggest the presence of oxygen diffusion losses above 0.4 A/cm2 when air was supplied to the cathode. Ultrasonic MEAs were three times more sensitive to changes in air flow rate on the cathode than the thermally MEAs. Increasing the platinum catalyst loading from 0.16 to 0.33 mg Pt/cm2 resulted in a performance enhancement of approximately 20 mV and 65% greater electrochemical surface area. Understanding the effect of ultrasonic bonding on various performance losses will help optimize the MEA bonding process. Analysis of specific losses present for ultrasonic MEAs may also provide insight into the design of MEA components for ultrasonic bonding.
Slot-Die Coating: A New Preparation Method for Direct Methanol Fuel Cells Catalyst Layers
Authors: Glüsen Andreas , Müller Martin , Stolten Detlef
Published: June 2013

Manufacturing of catalyst layers is one of the key processing steps in making membrane electrode assemblies (MEAs) for direct methanol fuel cells (DMFCs). The catalyst ink, which usually contains catalysts, ionomers, solvents, and additives, is generally applied to the substrate by a wet-coating technique. Established coating techniques which are used for manufacturing catalyst layers for fuel cells are knife-coating, screen-printing, and spraying. Slot-die coating is also an established coating technique, but not currently used for making fuel cell electrodes. For each coating technique the properties of the catalyst layer will depend on the properties of the coating technique and the properties of the substrate. Also each coating technique requires the catalyst ink to be adjusted to its specific rheological requirements. In this study, slot-die coating is developed as a new method for the continuous manufacture of catalyst layers for direct methanol fuel cells. The rheological demands for a homogeneous layer thickness are studied with model inks and a suitable catalyst ink is prepared. With this ink, decal electrodes are fabricated and CCM-type MEAs are made. Fuel cell tests show that the performance of the slot-die coated electrodes is comparable to electrodes made by knife-coating.
Use of Gait-Kinematics in Sensor-Based Gait Monitoring: A Feasibility Study
Authors: Ketema Yohannes , Gebre-Egziabher Demoz , Schwartz Michael , Matthews Chris , Kirker Ryan
Published: June 2013

A concept for fusing information from the kinematics describing human locomotion with body-fixed sensors for the purpose of in situ gait monitoring is studied. This is done by using an individual's gait patterns (as captured by a simplified kinematic model) with acceleration measurements made at key points on the body. The gait patterns are expressed as nominal relations between shank, thigh, and stance leg angles during normal walking. It is shown how the use of known gait patterns reduces the required number of sensors attached to the body that are required for a sensor-based monitoring of gait. The feasibility of the approach is demonstrated using a single acceleration measurement at the ankle to estimate limb angles and step size in situ. Such gait monitoring may be used for the evaluations of a subject's overall quality of gait through the determination of flexions at the knees and hip. In addition, step sizes, distance walked, and speed can be estimated. Apart from gait analysis, the method can be used for remotely monitoring the safety of individuals to the extent this can be done through consideration of the state of gait.
Comprehensive Solutions for the Response of Freestanding Beams With Tensile Residual Stress Subject to Point-Loading
Authors: Gaskins John , Scott Barker N. , Begley Matthew R.
Published: June 2013

This paper provides comprehensive solutions for the load-deflection response of an elastic beam with tensile residual stresses subjected to point-loading. A highly accurate explicit approximation is derived from the exact implicit solution for moderate rotations, which greatly facilitates property extraction and the design of devices for materials characterization, actuation, and sensing. The approximation has less than 6% error across the entire range of loads, displacements, geometry, and residual stress levels. An illustration of the application of the theory is provided for microfabricated nickel beams. The explicit form provides straightforward estimates for the critical loads and deflection defining the limits where classical asymptotic limits (e.g., pretensioned membrane, plate, and nonlinear membrane) will be accurate. Regimes maps are presented that identify critical loads, displacements, and properties correspond to these behaviors. Finally, the explicit form also enables straightforward estimations of bending strains relative to stretching, which is useful in the design of materials experiments that can be approximated as uniform straining of the beams.
Theoretical Solution for Thick Plate Resting on Pasternak Foundation by Symplectic Geometry Method
Authors: Zhong Yang , Heng Liu
Published: June 2013

Based on the analogy of structural mechanics and optimal control, the theory of the Hamilton system can be applied in the analysis of problem solving using the theory of elasticity and in the solution of elliptic partial differential equations. With this technique, this paper derives the theoretical solution for a thick rectangular plate with four free edges supported on a Pasternak foundation by the variable separation method. In this method, the governing equation of the thick plate was first transformed into state equations in the Hamilton space. The theoretical solution of this problem was next obtained by applying the method of variable separation based on the Hamilton system. Compared with traditional theoretical solutions for rectangular plates, this method has the advantage of not having to assume the form of deflection functions in the solution process. Numerical examples are presented to verify the validity of the proposed solution method.
Multiphasic Finite Element Framework for Modeling Hydrated Mixtures With Multiple Neutral and Charged Solutes
Authors: Ateshian Gerard A. , Maas Steve , Weiss Jeffrey A.
Published: June 2013

Computational tools are often needed to model the complex behavior of biological tissues and cells when they are represented as mixtures of multiple neutral or charged constituents. This study presents the formulation of a finite element modeling framework for describing multiphasic materials in the open-source finite element software febio.1 Multiphasic materials may consist of a charged porous solid matrix, a solvent, and any number of neutral or charged solutes. This formulation proposes novel approaches for addressing several challenges posed by the finite element analysis of such complex materials: The exclusion of solutes from a fraction of the pore space due to steric volume and short-range electrostatic effects is modeled by a solubility factor, whose dependence on solid matrix deformation and solute concentrations may be described by user-defined constitutive relations. These solute exclusion mechanisms combine with long-range electrostatic interactions into a partition coefficient for each solute whose value is dependent upon the evaluation of the electric potential from the electroneutrality condition. It is shown that this electroneutrality condition reduces to a polynomial equation with only one valid root for the electric potential, regardless of the number and valence of charged solutes in the mixture. The equation of charge conservation is enforced as a constraint within the equation of mass balance for each solute, producing a natural boundary condition for solute fluxes that facilitates the prescription of electric current density on a boundary. It is also shown that electrical grounding is necessary to produce numerical stability in analyses where all the boundaries of a multiphasic material are impermeable to ions. Several verification problems are presented that demonstrate the ability of the code to reproduce known or newly derived solutions: (1) the Kedem–Katchalsky model for osmotic loading of a cell; (2) Donnan osmotic swelling of a charged hydrated tissue; and (3) current flow in an electrolyte. Furthermore, the code is used to generate novel theoretical predictions of known experimental findings in biological tissues: (1) current-generated stress in articular cartilage and (2) the influence of salt cation charge number on the cartilage creep response. This generalized finite element framework for multiphasic materials makes it possible to model the mechanoelectrochemical behavior of biological tissues and cells and sets the stage for the future analysis of reactive mixtures to account for growth and remodeling.
Assessment of a Virtual Functional Prototyping Process for the Rapid Manufacture of Passive-Dynamic Ankle-Foot Orthoses
Authors: Schrank Elisa S. , Hitch Lester , Wallace Kevin , Moore Richard , Stanhope Steven J.
Published: June 2013

Passive-dynamic ankle-foot orthosis (PD-AFO) bending stiffness is a key functional characteristic for achieving enhanced gait function. However, current orthosis customization methods inhibit objective premanufacture tuning of the PD-AFO bending stiffness, making optimization of orthosis function challenging. We have developed a novel virtual functional prototyping (VFP) process, which harnesses the strengths of computer aided design (CAD) model parameterization and finite element analysis, to quantitatively tune and predict the functional characteristics of a PD-AFO, which is rapidly manufactured via fused deposition modeling (FDM). The purpose of this study was to assess the VFP process for PD-AFO bending stiffness. A PD-AFO CAD model was customized for a healthy subject and tuned to four bending stiffness values via VFP. Two sets of each tuned model were fabricated via FDM using medical-grade polycarbonate (PC-ISO). Dimensional accuracy of the fabricated orthoses was excellent (average 0.51 ± 0.39 mm). Manufacturing precision ranged from 0.0 to 0.74 Nm/deg (average 0.30 ± 0.36 Nm/deg). Bending stiffness prediction accuracy was within 1 Nm/deg using the manufacturer provided PC-ISO elastic modulus (average 0.48 ± 0.35 Nm/deg). Using an experimentally derived PC-ISO elastic modulus improved the optimized bending stiffness prediction accuracy (average 0.29 ± 0.57 Nm/deg). Robustness of the derived modulus was tested by carrying out the VFP process for a disparate subject, tuning the PD-AFO model to five bending stiffness values. For this disparate subject, bending stiffness prediction accuracy was strong (average 0.20 ± 0.14 Nm/deg). Overall, the VFP process had excellent dimensional accuracy, good manufacturing precision, and strong prediction accuracy with the derived modulus. Implementing VFP as part of our PD-AFO customization and manufacturing framework, which also includes fit customization, provides a novel and powerful method to predictably tune and precisely manufacture orthoses with objectively customized fit and functional characteristics.
BrachyView, A novel inbody imaging system for HDR prostate brachytherapy: Design and Monte Carlo feasibility study
Authors: Safavi‐Naeini M. , Han Z. , Cutajar D. , Guatelli S. , Petasecca M. , Lerch M. L. F. , Franklin D. R. , Jakubek J. , Pospisil S. , Bucci J. , Zaider M. , Rosenfeld A. B.
Published: June 2013

Purpose:

High dose rate (HDR) brachytherapy is a form of radiation therapy for treating prostate cancer whereby a high activity radiation source is moved between predefined positions inside applicators inserted within the treatment volume. Accurate positioning of the source is essential in delivering the desired dose to the target area while avoiding radiation injury to the surrounding tissue. In this paper,HDR BrachyView, a novel inbody dosimetric imaging system for real time monitoring and verification of the radioactive seed position in HDR prostate brachytherapy treatment is introduced. The current prototype consists of a 15 × 60 mm2 silicon pixel detector with a multipinhole tungsten collimator placed 6.5 mm above the detector. Seven identical pinholes allow full imaging coverage of the entire treatment volume. The combined pinhole and pixel sensor arrangement is geometrically designed to be able to resolve the three‐dimensional location of the source. The probe may be rotated to keep the whole prostate within the transverse plane. The purpose of this paper is to demonstrate the efficacy of the design through computer simulation, and to estimate the accuracy in resolving the source position (in detector plane and in 3D space) as part of the feasibility study for the BrachyView project.

Methods:

Monte Carlo simulations were performed using the GEANT4 radiation transport model, with a192Ir source placed in different locations within a prostate phantom. A geometrically accurate model of the detector and collimator were constructed. Simulations were conducted with a single pinhole to evaluate the pinhole design and the signal to background ratio obtained. Second, a pair of adjacent pinholes were simulated to evaluate the error in calculated source location.

Results:

Simulation results show that accurate determination of the true source position is easily obtainable within the typical one second source dwell time. The maximum error in the estimated projection position was found to be 0.95 mm in the imaging (detector) plane, resulting in a maximum source positioning estimation error of 1.48 mm.

Conclusions:

HDR BrachyView is a feasible design for real‐time source tracking in HDR prostate brachytherapy. It is capable of resolving the source position within a subsecond dwell time. In combination with anatomical information obtained from transrectal ultrasound imaging, HDR BrachyView adds a significant quality assurance capability to HDR brachytherapy treatment systems.
Dosimetric comparison of helical tomotherapy treatment plans for total marrow irradiation created using GPU and CPU dose calculation engines
Authors: Nalichowski Adrian , Burmeister Jay
Published: June 2013

Purpose:

To compare optimization characteristics, plan quality, and treatment delivery efficiency between total marrow irradiation (TMI) plans using the new TomoTherapy graphic processing unit (GPU) based dose engine and CPU/cluster based dose engine.

Methods:

Five TMI plans created on an anthropomorphic phantom were optimized and calculated with both dose engines. The planning treatment volume (PTV) included all the bones from head to mid femur except for upper extremities. Evaluated organs at risk (OAR) consisted of lung, liver, heart, kidneys, and brain. The following treatment parameters were used to generate the TMI plans: field widths of 2.5 and 5 cm, modulation factors of 2 and 2.5, and pitch of either 0.287 or 0.43. The optimization parameters were chosen based on the PTV and OAR priorities and the plans were optimized with a fixed number of iterations. The PTV constraint was selected to ensure that at least 95% of the PTV received the prescription dose. The plans were evaluated based on D80 and D50 (dose to 80% and 50% of the OAR volume, respectively) and hotspot volumes within the PTVs. Gamma indices (Γ) were also used to compare planar dose distributions between the two modalities. The optimization and dose calculation times were compared between the two systems. The treatment delivery times were also evaluated.

Results:

The results showed very good dosimetric agreement between the GPU and CPU calculated plans for any of the evaluated planning parameters indicating that both systems converge on nearly identical plans. All D80 and D50 parameters varied by less than 3% of the prescription dose with an average difference of 0.8%. A gamma analysis Γ(3%, 3 mm) < 1 of the GPU plan resulted in over 90% of calculated voxels satisfying Γ < 1 criterion as compared to baseline CPU plan. The average number of voxels meeting the Γ < 1 criterion for all the plans was 97%. In terms of dose optimization/calculation efficiency, there was a 20‐fold reduction in planning time with the new GPU system. The average optimization/dose calculation time utilizing the traditional CPU/cluster based system was 579 vs 26.8 min for the GPU based system. There was no difference in the calculated treatment delivery time per fraction. Beam‐on time varied based on field width and pitch and ranged between 15 and 28 min.

Conclusions:

The TomoTherapy GPU based dose engine is capable of calculating TMI treatment plans with plan quality nearly identical to plans calculated using the traditional CPU/cluster based system, while significantly reducing the time required for optimization and dose calculation.
Correction Techniques in Emission Tomography.
Authors: Erwin William D.
Published: June 2013

Correction Techniques in Emission Tomography., Dawood M., Jiang X., Schäfers K., CRC Press, Taylor & Francis Group, Boca Raton, FL, 2012. 287 pp. Price: $119.95. ISBN: 9781439812983 (hardcover). © 2013 Doody's Review Service. Doody's Review Service
Conditions for reliable time‐resolved dosimetry of electronic portal imaging devices for fixed‐gantry IMRT and VMAT
Authors: Yeo Inhwan Jason , Jung Jae Won , Patyal Baldev , Mandapaka Anant , Yong Yi Byong , Oh Kim Jong
Published: June 2013

Purpose:

The continuous scanning mode of electronic portal imaging devices (EPID) that offers time‐resolved information has been newly explored for verifying dynamic radiation deliveries. This study seeks to determine operating conditions (dose rate stability and time resolution) under which that mode can be used accurately for the time‐resolved dosimetry of intensity‐modulated radiation therapy (IMRT) beams.

Methods:

The authors have designed the following test beams with variable beam holdoffs and dose rate regulations: a 10 × 10 cm open beam to serve as a reference beam; a sliding window (SW) beam utilizing the motion of a pair of multileaf collimator (MLC) leaves outside the 10 × 10 cm jaw; a step and shoot (SS) beam to move the pair in step; a volumetric modulated arc therapy (VMAT) beam. The beams were designed in such a way that they all produce the same open beam output of 10 × 10 cm. Time‐resolved ion chamber measurements at isocenter and time‐resolved and integrating EPID measurements were performed for all beams. The time‐resolved EPID measurements were evaluated through comparison with the ion chamber and integrating EPID measurements, as the latter are accepted procedures. For two‐dimensional, time‐resolved evaluation, a VMAT beam with an infield MLC travel was designed. Time‐resolved EPID measurements and Monte Carlo calculations of such EPID dose images for this beam were performed and intercompared.

Results:

For IMRT beams (SW and SS), the authors found disagreement greater than 2%, caused by frame missing of the time‐resolved mode. However, frame missing disappeared, yielding agreement better than 2%, when the dose rate of irradiation (and thus the frame acquisition rates) reached a stable and planned rate as the dose of irradiation was raised past certain thresholds (a minimum 12 s of irradiation per shoot used for SS IMRT). For VMAT, the authors found that dose rate does not affect the frame acquisition rate, thereby causing no frame missing. However, serious inplanar nonuniformities were found. This could be overcome by sacrificing temporal resolution (10 frames or 0.95 s/image): the continuous images agreed with ion chamber responses at the center of EPID and the calculation two‐dimensionally in a time‐resolved manner.

Conclusions:

The authors have determined conditions under which the continuous mode can be used for time‐resolved dosimetry of fixed‐gantry IMRT and VMAT and demonstrated it for VMAT.
In vivo evaluation of a breast‐specific magnetic resonance guided focused ultrasound system in a goat udder model
Authors: Payne A. , Todd N. , Minalga E. , Wang Y. , Diakite M. , Hadley R. , Merrill R. , Factor R. , Neumayer L. , Parker D. L.
Published: June 2013

Purpose:

This work further evaluates the functionality, efficacy, and safety of a new breast‐specific magnetic resonance guided high intensity focused ultrasound (MRgFUS) system in anin vivo goat udder model.

Methods:

Eight female goats underwent an MRgFUS ablation procedure using the breast‐specific MRgFUS system. Tissue classification was achieved through the 3D magnetic resonance imaging (MRI) acquisition of several contrasts (T1w, T2w, PDw, 3‐point Dixon). The MRgFUS treatment was performed with a grid trajectory executed in one or two planes within the glandular tissue of the goat udder. Temperature was monitored using a 3D proton resonance frequency (PRF) MRI technique. Delayed contrast enhanced‐MR images were acquired immediately and 14 days post MRgFUS treatment. A localized tissue excision was performed in one animal and histological analysis was performed. Animals were available for adoption at the conclusion of the study.

Results:

The breast‐specific MRgFUS system was able to ablate regions ranging in size from 0.4 to 3.6 cm3 in the goat udder model. Tissue damage was confirmed through the correlation of thermal dose measurements obtained with realtime 3D MR thermometry to delayed contrast enhanced‐MR images immediately after the treatment and 14 days postablation. In general, lesions were longer in the ultrasound propagation direction, which is consistent with the dimensions of the ultrasound focal spot. Thermal dose volumes had better agreement with nonenhancing areas of the DCE‐MRI images obtained 14 days after the MRgFUS treatment.

Conclusions:

The system was able to successfully ablate lesions up to 3.6 cm3. The thermal dose volume was found to correlate better with the 14‐day postablation nonenhancing delayed contrast enhanced‐MR image volumes. While the goat udder is not an ideal model for the human breast, this study has proven the feasibility of using this system on a wide variety of udder shapes and sizes, demonstrating the flexibility that would be required in order to treat human subjects.
Acoustic measurements and the individual subjective evaluation for sound fields
Authors: Sakai Hiroyuki
Published: June 2013

Acoustical measurements and individual subjective evaluations for sound fields were performed based on a model of the human auditory-brain system and subjective preference theory. In the acoustic measurement section, orthogonal factors in historical opera houses and outdoor sound fields in forests are discussed. In the subjective evaluation section, individual differences and intra-individual changes of subjective preference are described in terms of the orthogonal factors. The main conclusions are as follows: (1) In acoustic measurements in a forest and in a bamboo forest, it is found that multiple scattering effects between trees or bamboo improve IACC; (2) Results of a preference test in an existing opera house show that subjective preference theory can be applied to opera houses, including the orchestra pit and the box seats; (3) Coefficient is introduced for individual preference in a sound field; and (4) The investigations of preference tests in relation to listening level (LL) and subsequent reverberation time (Tsub) for a simulated sound field show that subjects with a large value of α have small intra-individual changes, so the range of its preferred value is small. On the other hand, subjects with small value have minor preference as its parameter is changed.

Thesis advisor: Yoichi Ando

Copies of this thesis written in English can be obtained from Hiroyuki Sakai, Graduate School of Science and Technology, Kobe University, Rokkodai, Nada, Kobe 657-8501 Japan. E-mail address: sakaih@kobe-u.ac.jp.
Never too early for the opportunists!
Authors: Subedee Anup , Kimmel William , Donato Anthony A
Published: June 2013

Primary HIV infection can occur in 40–90% of individuals recently infected with HIV. Variable symptoms usually suggestive of a flu-like illness as well as high-level HIV viraemia and steep decline in CD4 cell count are often noted. We report a case of a previously healthy homosexual man who presented with symptoms suspicious of primary HIV infection as well as non-productive cough associated with chest CT finding of diffuse ground glass appearance in lungs. Recent HIV seroconversion was confirmed. Diagnosis ofPneumocystis jiroveciipneumonia was made on transbronchial lung biopsy. The symptoms improved rapidly after initiation of treatment with trimethoprim-sulfamethoxazole. It is important to recognise that althoughPneumocystispneumonia is generally seen in the setting of AIDS, it can occasionally also occur during primary HIV infection.
Acute mesenteric ischaemia with infective endocarditis: is there a role for anticoagulation?
Authors: Waqas Muhammad , Waheed Shahan , Haider Zishan , Shariff Amir Hafeez
Published: June 2013

A case of a 30-year-old woman with an end-stage renal disease and recently diagnosed with infective endocarditis, who presented with acute abdominal pain. An initial assessment of acute appendicitis was made. A CT scan of the abdomen showed a partially occluded superior mesenteric artery with radiographic evidence of ischaemia in an ileal loop. Intraoperatively, a 5–6 cm segment of the distal ileum was found to be non-viable. The segment was resected with the creation of a double-barrel ileostomy. This case report draws attention to the question of a need for anticoagulation for a septic embolus in the superior mesenteric artery. We could not find evidence on the use of postoperative anticoagulation in this scenario. In this case, the patient was started on oral anticoagulation.