bluuebunny/crossref_metadata_2025 huggingface dataset:
Why is there no Coastal Cordillera at the Arica Bend (Western Central Andes)?
Authors: Madella Andrea , Delunel Romain , Audin Laurence , Schlunegger Fritz
Published: August 2016

The architecture of the Western Andes is remarkably constant between southern Peru and northern Chile. An exception, however, is present near Arica at 18°S, where the Andes change their strike direction by ca. 50° and the Coastal Cordillera is absent over an along‐strike width of 50 km. Although this feature has been mentioned in several previous studies, no effort has been made yet to describe and explain this peculiar morphology of the Western Central Andean forearc. Here, we propose a large‐scale model to explain the Myr‐long low uplift rate of the Arica Bend concerning seismic coupling and continental wedge‐top basin evolution. New geomorphic and sedimentologic data are integrated with seismicity and structural data from the literature to interpret the post‐Oligocene pattern of uplift, erosion and sediment transport to the trench. Results show that the Arica Bend has been marked by exceptionally low coastal uplift rates over post‐Oligocene timescales. In addition, this uplift anomaly at the Arica Bend correlates with relatively high sediment discharge to the corresponding trench segment since late Oligocene time. We interpret that before 25 Ma, the forming seaward concavity of the subduction zone induced trench‐parallel extension at the curvature apex of the overriding forearc. The subsequent low uplift rate would have then triggered a feedback mechanism, where the interplay between relatively low interplate friction, low coastal uplift and relatively high sediment discharge favoured Myr‐long relative subsidence at the Arica Bend, in contrast to Myr‐long uplift of the Coastal Cordillera north and south of it.
Neuroprotective effect of propofol against excitotoxic injury to locomotor networks of the rat spinal cord in vitro
Authors: Kaur Jaspreet , Flores Gutiérrez Javier , Nistri Andrea
Published: August 2016

Although neuroprotection to contain the initial damage of spinal cord injury (SCI) is difficult, multicentre studies show that early neurosurgery under general anaesthesia confers positive benefits. An interesting hypothesis is that the general anaesthetic itself might largely contribute to neuroprotection, although in vivo clinical settings hamper studying this possibility directly. To further test neuroprotective effects of a widely used general anaesthetic, we studied if propofol could change the outcome of a rat isolated spinal cord SCI model involving excitotoxicity evoked by 1 h application of kainate with delayed consequences on neurons and locomotor network activity. Propofol (5 μm; 4–8 h) enhanced responses to GABA and depressed those to NMDA together with decrease in polysynaptic reflexes that partly recovered after 1 day washout. Fictive locomotion induced by dorsal root stimuli or NMDA and serotonin was weaker the day after propofol application. Kainate elicited a significant loss of spinal neurons, especially motoneurons, whose number was halved. When propofol was applied for 4–8 h after kainate washout, strong neuroprotection was observed in all spinal areas, including attenuation of motoneuron loss. Although propofol had minimal impact on recovery of electrophysiological characteristics 24 h later, it did not further depress network activity. A significant improvement in disinhibited burst periodicity suggested potential to ameliorate neuronal excitability in analogy to histological data. Functional recovery of locomotor networks perhaps required longer time due to the combined action of excitotoxicity and anaesthetic depression at 24 h. These results suggest propofol could confer good neuroprotection to spinal circuits during experimental SCI.
Risks to Effective Knowledge Sharing in Agile Software Teams: A Model for Assessing and Mitigating Risks
Authors: Ghobadi Shahla , Mathiassen Lars
Published: August 2016

We present an empirically grounded and theoretically informed model for the assessment and mitigation of risks to effective knowledge sharing in agile development. The model is anchored in empirical insights from four agile projects across two software companies and in extant research on risk‐strategy analysis and knowledge sharing in software development. We develop the model as part of the long‐standing tradition of presenting risk management models dedicated to specific issues in software development and confirm its practical usefulness in one of the software companies studied. The model offers concepts and processes to assess a project's knowledge sharing risk profile and articulate an overall resolution strategy plan to mitigate the risks. The results highlight how different knowledge sharing risk management profiles can lead to different project performance outcomes. We conclude with a discussion of research opportunities that the results offer software development scholarship. © 2016 John Wiley & Sons Ltd
Treatment of vitiligo with 308‐nm excimer laser: our experience from a 2‐year follow‐up of 979 Chinese patients
Authors: Fa Y. , Lin Y. , Chi X.J. , Shi W.H. , Wang J.L. , Guo X. , Geng J.H. , Liu H.X. , Zhang F.R.
Published: August 2016

Background

The 308‐nm excimer laser had been proved to be a time‐efficient and potent therapeutic alternative for the management of vitiligo. Different results had been reported in different ethnic populations.

Objective

To investigate the efficacy and related contributing factors of 308‐nm excimer laser in Chinese vitiligo patients.

Methods

A total of 979 Chinese patients (3478 lesions) with progressive‐stage vitiligo who had received 308‐nm excimer laser treatment were recruited from the vitiligo clinic of Shandong Provincial Hospital of Dermatology &Venereology from 2012 to 2014. Efficacy of treatment was evaluated at the end of session by two independent dermatologists based on the before and after images taken. Repigmentation was graded on a 4‐point scale: grade 1, poor repigmentation (0–25%); grade 2, moderate repigmentation (26–50%); grade 3, good repigmentation (51–75%); grade 4, excellent repigmentation (76–100%).

Results

The mean grade of repigmentation was 2.29, 44.22% showed less than 25% repigmentation, 16.27% showed 26–50% repigmentation, 5.95% showed 51–75% repigmentation and 33.55% showed more than 76% repigmentation. The repigmentation of facial lesions was better than lesions located elsewhere (P < 0.0001), the best response was noted in the periorbital region, while lesions on hands and feet showed poor repigmentation (P < 0.0001). The degree of repigmentation was negatively correlated with disease duration (r = −0.268, P < 0.001), age (r = −0.095, P < 0.001) and shape of lesions (r = −0.114, P < 0.001), whereas it was positively correlated with treatment frequency (r = 0.270, P < 0.001). Lesions with concurrent poliosis were more likely resistant to treatments.

Conclusion

308‐nm excimer laser appears to be an effective and safe treatment in Chinese vitiligo patients. The clinical response and treatment efficacy was affected by many factors such as age, affected anatomical area, shape of the lesion, disease duration and treatment frequencies.
Patterns of Functional Disability in the Oldest Adults in China
Authors: Fong Joelle H. , Feng Jun
Published: August 2016

This study examined patterns of onset of activity of daily living (ADL) disability in a nationally representative sample of older adults in mainland China. Using longitudinal data from the Chinese Longitudinal Healthy Longevity Survey from 1998 to 2008 (N = 5,570), nonparametric methods were used to evaluate median age at onset of various ADL disabilities and differences in the incidence of disabilities according to sex. The sampled older Chinese adults developed ADL disabilities, on average, between the ages of 89 and 94. Women were likely to experience later onset than men. The results also show that the oldest adults generally lose bathing ability, followed by toileting, transferring, dressing, eating, and finally, continence. This order—derived from estimated median age at onset—was also found to be highly prevalent in subsequently disabled respondents in the sample. The disability experience of older adults in China is somewhat similar to that of older adults in Western developed countries; elderly adults tend to lose ability in activities that require lower extremity strength earlier than those that require upper extremity strength. The relative importance of the various ADL items in the hierarchical ordering has implications for early intervention to reduce the risk of functional disability in older adults and those at risk of transitions of care.
Place of Death of Individuals with Terminal Cancer: New Insights from Medicare Hospice Place‐of‐Service Codes
Authors: Jarosek Stephanie L. , Shippee Tetyana P. , Virnig Beth A.
Published: August 2016

Objectives

To use place‐of‐service (POS) codes in the Medicare hospice claims files to document where elderly hospice users with cancer die.

Design

Retrospective cohort study.

Setting

Surveillance, Epidemiology, and End Results (SEER) cancer registry areas.

Participants

Elderly Medicare beneficiaries who died of lung, breast, colorectal, or pancreatic cancer in 2007 and 2008 (N = 46,037).

Measurement

Use of hospice, place of service at death (home, nursing home, hospital, inpatient hospice, other), length of stay in hospice.

Results

Two‐thirds of the beneficiaries used hospice. Younger, male, black, Asian, and unmarried beneficiaries and those enrolled in fee‐for‐service Medicare or from areas with lower income were less likely to use hospice. Hospice enrollment also varied significantly according to SEER registry. Thirty percent of the hospice users were not receiving home‐based care at the time of death, and 17% were enrolled for less than 3 days. Factors associated with hospice death in the home mirrored those associated with hospice use. Individuals dying in hospitals (odds ratio (OR) = 5.13, 95% confidence interval (CI) = 4.63–5.69), inpatient hospice (OR = 1.86, 95% CI = 1.70–2.02), and nursing homes (OR = 1.19, 95% CI = 1.10–1.28) had greater odds of a short hospice stay (≤7 days) than those dying at home, after controlling for all other measured factors, whereas those dying in nursing homes had greater odds of long stays (>180 days) (OR = 1.46, 95% CI = 1.28–1.67).

Conclusion

New hospice POS codes are useful for understanding place of death for hospice users. Hospice deaths cannot be assumed to happen at home.
Reflections on 60 years of publication of the Journal of Neurochemistry
Authors: Turner Anthony J. , Nalivaeva Natalia N. , Fonnum Frode , Tipton Keith F. , Hausmann Laura , Schulz Jörg B.
Published: August 2016

This review reflects on the origins, development, publishing trends, and scientific directions of the Journal of Neurochemistry over its 60 year lifespan as seen by key contributors to the Journal's production. The Journal first appeared in May 1956 with just two issues published in that inaugural year. By 1963, it appeared monthly and, by 2002, 24 hard copy issues were published yearly. In 2014, the Journal became online only. For much of its time, the Journal was managed through two separate editorial offices each with their respective Chief Editor (the ‘Western’ and ‘Eastern’ hemispheres). The Journal was restructured to operate through a single editorial office and Editor‐in‐Chief from 2013. Scientifically, the Journal progressed through distinct scientific eras with the first two decades generally centered around developments in methodology followed by a period when publications delved deeper into underlying mechanisms. By the late 1980s, the Journal had entered the age of genetics and beyond, with an increasing focus on neurodegenerative diseases. Reviews have played a regular part in the success of J Neurochem with focused special and virtual issues being a highlight of recent years. Today, 60 years and onwards, J Neurochem continues to be a leading source of top‐quality, original and review articles in neuroscience. We look forward to its continued success at the forefront of neurochemistry in the decades to come.

image

This article celebrates 60 years of publication of Journal of Neurochemistry including personal reminiscences from some of the Chief Editors, past and present, as well as input from some of the key contributors to the Journal over this period. We highlight the scientific, technological, and publishing developments along the way, with reference to key papers published in the Journal. The support of the Journal toward the aims and objectives of the International Society for Neurochemistry (ISN) is also emphasized.

This article is part of the 60th Anniversary special issue.
How can group‐based multidisciplinary rehabilitation for patients with fibromyalgia influence patients' self‐efficacy and ability to cope with their illness: a grounded theory approach
Authors: Rasmussen Marianne Uggen , Amris Kirstine , Rydahl‐Hansen Susan
Published: August 2016

Aims and objectives

To describe how group‐based multidisciplinary rehabilitation for patients with fibromyalgia can influence patients' self‐efficacy and ability to cope with their illness.

Background

Multidisciplinary rehabilitation is recommended in the management of fibromyalgia. Self‐efficacy is said to influence and predict adaptive coping behaviours and functioning. However, knowledge is lacking on how rehabilitation programmes may influence self‐efficacy and ability to cope, from the patients' perspective.

Design

Grounded theory study of semi‐structured focus group interviews.

Methods

Participants (n = 17) were included in four focus groups that had completed a two‐week multidisciplinary rehabilitation programme together. Interviews were conducted four weeks after each group had completed the programme. The analysis was conducted constant comparatively applying open, axial and selective coding.

Results

Categories (in italics) were derived from data in which the explanatory core category was identified: Learning to accept and live with pain as a life condition, and linked to three categories mutually influencing each other: Increased self‐acceptance of living with the illness, experiencing acceptance from others and developing new coping strategies. Thus, patients benefitted from multidisciplinary rehabilitation with stronger self‐efficacy and expectations to their future coping. However, limitations in the programme were identified, as the programme was short and intensive with no subsequent follow‐up, and social welfare was not sufficiently addressed. Participants also found it difficult to maintain knowledge and were lacking individual sessions with the psychologist and had waited long to receive rehabilitation.

Conclusion

Multidisciplinary rehabilitation may advantageously be offered to patients with fibromyalgia. However, earlier action with longer programmes, in which patients' social situation is addressed, comprising individual sessions with the psychologist, with multiple repetitions of the content and follow‐up sessions, may further enhance the patients' self‐efficacy and coping with their illness.
Blood flow responses over sacrum in nursing home residents during one hour bed rest
Authors: Källman Ulrika , Bergstrand Sara , Ek Anna‐Christina , Engström Maria , Lindgren Margareta
Published: August 2016

Objectives

To describe individual BF responses in a nursing home resident population for one‐hour periods of bed rest.

Methods

BF was measured for one hour over the sacrum in 0° supine position and 30° supine tilt position in 25 individuals aged 65 y or older while lying on a pressure‐redistributing mattress. Measurements were made at three tissue depths (1, 2, and 10 mm) using the noninvasive optical techniques, LDF and PPG.

Results

Eleven participants had a PIV response at 1 mm depth in both positions and seven participants had a lack of this response at this depth and positions. The BF response at 1 mm depth appeared immediately and remained over, or below, baseline for the entire 60 min of loading in both positions. These BF patterns were also seen in deeper tissue layers.

Conclusions

The cutaneous BF response among the nursing home residents was distinct, appeared early, and remained during the one hour of loading.
How can we reduce costs of solid‐phase multiplex‐bead assays used to determine anti‐HLA antibodies?
Authors: Kamburova E. G. , Wisse B. W. , Joosten I. , Allebes W. A. , van der Meer A. , Hilbrands L. B. , Baas M. C. , Spierings E. , Hack C. E. , van Reekum F. E. , van Zuilen A. D. , Verhaar M. , Bots M. L. , Drop A. C. A. D. , Plaisier L. , Seelen M. A. J. , Sanders J. S. F. , Hepkema B. G. , Lambeck A. J. , Bungener L. B. , Roozendaal C. , Tilanus M. G. J. , Vanderlocht J. , Voorter C. E. , Wieten L. , van Duijnhoven E. M. , Gelens M. , Christiaans M. H. L. , van Ittersum F. J. , Nurmohamed A. , Lardy N. M. , Swelsen W. , van der Pant K. A. , van der Weerd N. C. , ten Berge I. J. M. , Bemelman F. J. , Hoitsma A. , van der Boog P. J. M. , de Fijter J. W. , Betjes M. G. H. , Heidt S. , Roelen D. L. , Claas F. H. , Otten H. G.
Published: August 2016

Solid‐phase multiplex‐bead assays are widely used in transplantation to detect anti‐human leukocyte antigen (HLA) antibodies. These assays enable high resolution detection of low levels of HLA antibodies. However, multiplex‐bead assays are costly and yield variable measurements that limit the comparison of results between laboratories. In the context of a Dutch national Consortium study we aimed to determine the inter‐assay and inter‐machine variability of multiplex‐bead assays, and we assessed how to reduce the assay reagents costs. Fifteen sera containing a variety of HLA antibodies were used yielding in total 7092 median fluorescence intensities (MFI) values. The inter‐assay and inter‐machine mean absolute relative differences (MARD) of the screening assay were 12% and 13%, respectively. The single antigen bead (SAB) inter‐assay MARD was comparable, but showed a higher lot‐to‐lot variability. Reduction of screening assay reagents to 50% or 40% of manufacturers' recommendations resulted in MFI values comparable to 100% of the reagents, with an MARD of 12% or 14%, respectively. The MARD of the 50% and 40% SAB assay reagent reductions were 11% and 22%, respectively. From this study, we conclude that the reagents can be reliably reduced at least to 50% of manufacturers' recommendations with virtually no differences in HLA antibody assignments.
Development of the Prediction Technology of Cable Disconnection of In-Core Neutron Detector for the Future High-Temperature Gas-Cooled Reactors
Authors: Shimazaki Yosuke , Sawahata Hiroaki , Kawamoto Taiki , Suzuki Hisashi , Shinohara Masanori , Honda Yuki , Katsuyama Kozo , Takada Shoji , Sawa Kazuhiro
Published: August 2016

Maintenance technologies for the reactor system have been developed by using the High Temperature engineering Test Reactor (HTTR). One of the important purposes of development is to accumulate the experiences and data to satisfy the availability of operation up to 90% by shortening the duration of the periodical maintenance for future high-temperature gas-cooled reactors (HTGRs) by shifting from time-based maintenance to condition-based maintenance. The technical issue of the maintenance of the in-core neutron detector, wide range monitor (WRM), is to predict the malfunction caused by cable disconnection to plan the replacement schedule. This is because it is difficult to observe directly inside the WRM in detail. The electrical inspection method was proposed to detect and predict the cable disconnection of the WRM by remote monitoring from outside the reactor using the time-domain reflectometry (TDR). The disconnection position, which was specified by the electrical method, was identified by nondestructive and destructive inspection. The accumulated data are expected to be contributed for advanced maintenance of future HTGRs.
Classification of Solutions to the Plane Extremal Distance Problem for Bodies With Smooth Boundaries
Authors: Damerau Jochen , Low Robert J.
Published: August 2016

The determination of the contact points between two bodies with analytically described boundaries can be viewed as the limiting case of the extremal point problem, where the distance between the bodies is vanishing. The advantage of this approach is that the solutions can be computed efficiently along with the generalized state during time integration of a multibody system by augmenting the equations of motion with the corresponding extremal point conditions. Unfortunately, these solutions can degenerate when one boundary is concave or both boundaries are nonconvex. We present a novel method to derive degeneracy and nondegeneracy conditions that enable the determination of the type and codimension of all the degenerate solutions that can occur in plane contact problems involving two bodies with smooth boundaries. It is shown that only divergence bifurcations are relevant, and thus, we can simplify the analysis of the degeneracy by restricting the system to its one-dimensional center manifold. The resulting expressions are then decomposed by applying the multinomial theorem resulting in a computationally efficient method to compute explicit expressions for the Lyapunov coefficients and transversality conditions. Furthermore, a procedure to analyze the bifurcation behavior qualitatively at such solution points based on the Tschirnhaus transformation is given and demonstrated by examples. The application of these results enables in principle the continuation of all the solutions simultaneously beyond the degeneracy as long as their number is finite.
Insights Into Lithium-Ion Battery Degradation and Safety Mechanisms From Mesoscale Simulations Using Experimentally Reconstructed Mesostructures
Authors: Roberts Scott A. , Mendoza Hector , Brunini Victor E. , Trembacki Bradley L. , Noble David R. , Grillet Anne M.
Published: August 2016

Battery performance, while observed at the macroscale, is primarily governed by the bicontinuous mesoscale network of the active particles and a polymeric conductive binder in its electrodes. Manufacturing processes affect this mesostructure, and therefore battery performance, in ways that are not always clear outside of empirical relationships. Directly studying the role of the mesostructure is difficult due to the small particle sizes (a few microns) and large mesoscale structures. Mesoscale simulation, however, is an emerging technique that allows the investigation into how particle-scale phenomena affect electrode behavior. In this manuscript, we discuss our computational approach for modeling electrochemical, mechanical, and thermal phenomena of lithium-ion batteries at the mesoscale. We review our recent and ongoing simulation investigations and discuss a path forward for additional simulation insights.
Computational Studies of Interfacial Reactions at Anode Materials: Initial Stages of the Solid-Electrolyte-Interphase Layer Formation
Authors: Ramos-Sanchez G. , Soto F. A. , Martinez de la Hoz J. M. , Liu Z. , Mukherjee P. P. , El-Mellouhi F. , Seminario J. M. , Balbuena P. B.
Published: August 2016

Understanding interfacial phenomena such as ion and electron transport at dynamic interfaces is crucial for revolutionizing the development of materials and devices for energy-related applications. Moreover, advances in this field would enhance the progress of related electrochemical interfacial problems in biology, medicine, electronics, and photonics, among others. Although significant progress is taking place through in situ experimentation, modeling has emerged as the ideal complement to investigate details at the electronic and atomistic levels, which are more difficult or impossible to be captured with current experimental techniques. Among the most important interfacial phenomena, side reactions occurring at the surface of the negative electrodes of Li-ion batteries, due to the electrochemical instability of the electrolyte, result in the formation of a solid-electrolyte interphase layer (SEI). In this work, we briefly review the main mechanisms associated with SEI reduction reactions of aprotic organic solvents studied by quantum mechanical methods. We then report the results of a Kinetic Monte Carlo method to understand the initial stages of SEI growth.
Effect of Flow Velocity and Impact Angle on Erosion–Corrosion Behavior of Chromium Carbide Coating
Authors: Hemmati A. R. , Soltanieh M. , Masoudpanah S. M.
Published: August 2016

In this study, the effect of flow velocity (4–7.5 m s−1) and impact angle (30–90 deg) on erosion–corrosion behavior of chromium carbide coating was investigated under impingement by silica containing NaCl solution. Chromium carbide coating was deposited on low carbon steel by thermal reactive deposition/diffusion method at 1050 °C for 12 h in a molten salt bath. Mass loss measurement and potentiodynamic polarization tests were employed in order to determine coating performance under impingement. Polarization curves showed that the coated samples had less corrosion current density and high chemical stability. High mass loss at low impact angle indicated ductile behavior for the uncoated sample, while the mass loss for the coated sample changes less than 30% with impact angle up to 60 deg. Furthermore, the erosion–corrosion behavior of the coated sample was slightly dependent on flow velocity. Scanning electron micrographs showed that at lower impact angle, the Cr7C3 coating eroded with flake fragmentation mechanism, while at high impact angle, fatigue fracture is the main degradation mechanism.
A Methodology for the Derivation of Unloaded Abdominal Aortic Aneurysm Geometry With Experimental Validation
Authors: Chandra Santanu , Gnanaruban Vimalatharmaiyah , Riveros Fabian , Rodriguez Jose F. , Finol Ender A.
Published: August 2016

In this work, we present a novel method for the derivation of the unloaded geometry of an abdominal aortic aneurysm (AAA) from a pressurized geometry in turn obtained by 3D reconstruction of computed tomography (CT) images. The approach was experimentally validated with an aneurysm phantom loaded with gauge pressures of 80, 120, and 140 mm Hg. The unloaded phantom geometries estimated from these pressurized states were compared to the actual unloaded phantom geometry, resulting in mean nodal surface distances of up to 3.9% of the maximum aneurysm diameter. An in-silico verification was also performed using a patient-specific AAA mesh, resulting in maximum nodal surface distances of 8 μm after running the algorithm for eight iterations. The methodology was then applied to 12 patient-specific AAA for which their corresponding unloaded geometries were generated in 5–8 iterations. The wall mechanics resulting from finite element analysis of the pressurized (CT image-based) and unloaded geometries were compared to quantify the relative importance of using an unloaded geometry for AAA biomechanics. The pressurized AAA models underestimate peak wall stress (quantified by the first principal stress component) on average by 15% compared to the unloaded AAA models. The validation and application of the method, readily compatible with any finite element solver, underscores the importance of generating the unloaded AAA volume mesh prior to using wall stress as a biomechanical marker for rupture risk assessment.
Biomechanical Studies on Patterns of Cranial Bone Fracture Using the Immature Porcine Model
Authors: Haut Roger C. , Wei Feng
Published: August 2016

This review was prepared for the American Society of Mechanical Engineers Lissner Medal. It specifically discusses research performed in the Orthopaedic Biomechanics Laboratories on pediatric cranial bone mechanics and patterns of fracture in collaboration with the Forensic Anthropology Laboratory at Michigan State University. Cranial fractures are often an important element seen by forensic anthropologists during the investigation of pediatric trauma cases litigated in courts. While forensic anthropologists and forensic biomechanists are often called on to testify in these cases, there is little basic science developed in support of their testimony. The following is a review of studies conducted in the above laboratories and supported by the National Institute of Justice to begin an understanding of the mechanics and patterns of pediatric cranial bone fracture. With the lack of human pediatric specimens, the studies utilize an immature porcine model. Because much case evidence involves cranial bone fracture, the studies described below focus on determining input loading based on the resultant bone fracture pattern. The studies involve impact to the parietal bone, the most often fractured cranial bone, and begin with experiments on entrapped heads, progressing to those involving free-falling heads. The studies involve head drops onto different types and shapes of interfaces with variations of impact energy. The studies show linear fractures initiating from sutural boundaries, away from the impact site, for flat surface impacts, in contrast to depressed fractures for more focal impacts. The results have been incorporated into a “Fracture Printing Interface (FPI),” using machine learning and pattern recognition algorithms. The interface has been used to help interpret mechanisms of injury in pediatric death cases collected from medical examiner offices. The ultimate aim of this program of study is to develop a “Human Fracture Printing Interface” that can be used by forensic investigators in determining mechanisms of pediatric cranial bone fracture.
Linearized Euler Equations for the Prediction of Linear High-Frequency Stability in Gas Turbine Combustors
Authors: Schulze Moritz , Hummel Tobias , Klarmann Noah , Berger Frederik , Schuermans Bruno , Sattelmayer Thomas
Published: August 2016

A novel methodology for linear stability analysis of high-frequency thermoacoustic oscillations in gas turbine combustors is presented. The methodology is based on the linearized Euler equations (LEEs), which yield a high-fidelity description of acoustic wave propagation and damping in complex, nonuniform, reactive mean flow environments, such as encountered in gas turbine combustion chambers. Specifically, this work introduces three novelties to the community: (1) linear stability analysis on the basis of linearized Euler equations. (2) Explicit consideration of three-dimensional, acoustic oscillations at screech level frequencies, particularly the first-transversal mode. (3) Handling of noncompact flame coupling with LEE, that is, the spatially varying coupling dynamics between perturbation and unsteady flame response due to small acoustic wavelengths. Two different configurations of an experimental model combustor in terms of thermal power and mass flow rates are subject of the analysis. Linear flame driving is modeled by prescribing the unsteady heat release source term of the linearized Euler equations by local flame transfer functions, which are retrieved from first principles. The required steady-state flow field is numerically obtained via computational fluid dynamics (CFD), which is based on an extended flamelet-generated manifold (FGM) combustion model, taking into account heat transfer to the environment. The model is therefore highly suitable for such types of combustors. The configurations are simulated, and thermoacoustically characterized in terms of eigenfrequencies and growth rates associated with the first-transversal mode. The findings are validated against experimentally observed thermoacoustic stability characteristics. On the basis of the results, new insights into the acoustic field are discussed.
Equivalent Clearance Model for Solving Thermohydrodynamic Lubrication of Slider Bearings With Steps
Authors: Ogata Hideki , Sugimura Joichi
Published: August 2016

This study focuses on the thermohydrodynamic lubrication (THD) analysis of fluid film bearings with steps on the bearing surface, such as Rayleigh step. In general, the Reynolds equation does not satisfy the continuity of fluid velocity components at steps. This discontinuity results in the difficulty to solve the energy equation for the lubricants by finite differential method (FDM), because the energy equation needs the velocity components explicitly. The authors have solved this issue by introducing the equivalent clearance height and the equivalent gradient of the clearance height at steps. These parameters remove the discontinuity of velocity components, and the Reynolds equations can be solved for any bearing surfaces with step regions by FDM. Moreover, this method results in pseudocontinuous velocity components, which enables the energy equation to be solved as well. This paper describes this method with one-dimensional and equal grids model. The numerical results of pressure and temperature distributions by the proposed method for an infinite width Rayleigh step bearing agree well with the results obtained by solving full Navier–Stokes equations with semi-implicit method for pressure-linked equations revised (SIMPLER) method.
Sci‐Thur AM: YIS – 01: New technologies for astatine‐211 targeted alpha therapy research
Authors: Crawford Jason , Yang Hua , Schaffer Paul , Ruth Thomas
Published: August 2016

Purpose:

The short‐range, densely ionizing α‐particles emitted by 211At (t1/2=7.2h) are well suited for the treatment of diffuse microscopic disease, using cancer targeting biomolecules. 211At availability is limited by the rarity of α‐cyclotrons required for standard production. Image‐based dosimetry is also limited for 211At, which emits low intensity X‐rays. Our goal was to leverage state‐of‐the‐art infrastructure at TRIUMF to produce and evaluate two related isotopes, 211Rn (t1/2=14.6h, 73% decay to 211At) as a generator for 211At, and 209At (t1/2=5.4h, X‐ray/gamma‐ray emitter) as a novel 211At surrogate for preclinical imaging studies.

Methods:

Produced by spallation of uranium with 480 MeV protons, mass separated ion beams of short‐lived francium isotopes were implanted into NaCl targets where 211Rn or 209At were produced by radioactive decay, in situ. 211Rn was transferred to dodecane from which 211At was efficiently extracted and evaluated for clinical applicability. High energy SPECT/CT was evaluated for measuring 209At activity distributions in mice and phantoms.

Results:

Our small scale 211Rn/211At generator system provided high purity 211At samples. The methods are immediately scalable to the level of radioactivity required for in vivo experiments with 211At. 209At‐based high energy SPECT imaging was determined suitable for pursuing image‐based dosimetry in mouse tumour models. In the future, we will utilize quantitative 209At‐SPECT for image‐based dose calculations.

Conclusion:

These early studies provided a foundation for future endeavours with 211At‐based α‐therapy. Canada is now significantly closer to clinical targeted α‐therapy of cancer.
Sci‐Thur AM: YIS – 02: Imaging dose distributions through the detection of radiation‐induced acoustic waves
Authors: Hickling Susannah , Lei Hao , Hobson Maritza , Leger Pierre , Wang Xueding , El Naqa Issam
Published: August 2016

Purpose:

X‐ray acoustic computed tomography (XACT) is an emerging technique that images the dose deposited within an object following linac irradiation by detecting acoustic waves induced via the photoacoustic effect. This work shows that XACT images can be formed in soft‐tissue equivalent material and that dosimetric information can be extracted from such images.

Methods:

Acoustic waves induced in a water tank following irradiation by a 10 MV flattening filter free photon beam were detected with an immersion ultrasound transducer at 60 angles surrounding the radiation field. A back‐projection algorithm was used to reconstruct an XACT image from the detected transducer signals. Profiles extracted from XACT images were compared to profiles measured with ion chambers as per the current clinical protocol.

Results:

XACT images were successfully formed of simple 4 cm × 4 cm and 6 cm × 3 cm fields, as well as of more complicated multi‐leaf collimator defined fields. For the 6 cm × 3 cm field, 74% and 87% of the XACT profile points in the 6 cm and 3 cm dimensions, respectively, passed a 7% / 4 mm gamma test when compared to ion chamber measurements. In a complicated puzzle piece shaped field, 86% of the pixels in an extracted profile passed a 7% / 4 mm gamma test.

Conclusions:

XACT is capable of imaging the dose distribution delivered by a variety of field sizes and shapes in water, and is a viable technique for both water tank and in vivo dosimetry.
Sci‐Thur AM: YIS – 04: Stopping power‐to‐Cherenkov power ratios and beam quality specification for clinical Cherenkov emission dosimetry of electrons: beam‐specific effects and experimental validation
Authors: Zlateva Yana , Seuntjens Jan , El Naqa Issam
Published: August 2016

Purpose:

To advance towards clinical Cherenkov emission (CE)‐based dosimetry by investigating beam‐specific effects on Monte Carlo‐calculated electron‐beam stopping power‐to‐CE power ratios (SCRs), addressing electron beam quality specification in terms of CE, and validating simulations with measurements.

Methods:

The EGSnrc user code SPRRZnrc, used to calculate Spencer‐Attix stopping‐power ratios, was modified to instead calculate SCRs. SCRs were calculated for 6‐ to 22‐MeV clinical electron beams from Varian TrueBeam, Clinac 21EX, and Clinac 2100C/D accelerators. Experiments were performed with a 20‐MeV electron beam from a Varian TrueBeam accelerator, using a diffraction grating spectrometer with optical fiber input and a cooled back‐illuminated CCD. A fluorophore was dissolved in the water to remove CE signal anisotropy.

Results:

It was found that angular spread of the incident beam has little effect on the SCR (≤ 0.3% at dmax), while both the electron spectrum and photon contamination increase the SCR at shallow depths and decrease it at large depths. A universal data fit of R50 in terms of C50 (50% CE depth) revealed a strong linear dependence (R2 > 0.9999). The SCR was fit with a Burns‐type equation (R2 = 0.9974, NRMSD = 0.5%). Below‐threshold incident radiation was found to have minimal effect on beam quality specification (< 0.1%). Experiments and simulations were in good agreement.

Conclusions:

Our findings confirm the feasibility of the proposed CE dosimetry method, contingent on computation of SCRs from additional accelerators and on further experimental validation. This work constitutes an important step towards clinical high‐resolution out‐of‐beam CE dosimetry.
Sci‐Thur PM ‐ Colourful Interactions: Highlights 06: Patient‐specific calibration of cone‐beam computed tomographic (CBCT) image sets for on‐line dose tracking and plan assessment
Authors: MacFarlane Michael , Wong Daniel , Johnson Carol , Bzdusek Karl , Battista Jerry , Chen Jeff
Published: August 2016

Purpose:

To develop a radiotherapy dose tracking and plan evaluation technique using cone‐beam computed tomography (CBCT) images.

Methods:

We developed a patient‐specific method of calibrating CBCT image sets for dose calculation. The planning CT was first registered with the CBCT using deformable image registration (DIR). A scatter plot was generated between the CT numbers of the planning CT and CBCT for each slice. The CBCT calibration curve was obtained by least‐square fitting of the data, and applied to each CBCT slice. The calibrated CBCT was then merged with original planning CT to extend the small field of view of CBCT. Finally, the treatment plan was copied to the merged CT for dose tracking and plan evaluation. The proposed patient‐specific calibration method was also compared to two methods proposed in literature. To evaluate the accuracy of each technique, 15 head‐and‐neck patients requiring plan adaptation were arbitrarily selected from our institution. The original plan was calculated on each method's data set, including a second planning CT acquired within 48 hours of the CBCT (serving as gold standard). Clinically relevant dose metrics and 3D gamma analysis of dose distributions were compared between the different techniques.

Results:

Compared to the gold standard of using planning CTs, the patient‐specific CBCT calibration method was shown to provide promising results with gamma pass rates above 95% and average dose metric agreement within 2.5%.

Conclusions:

The patient‐specific CBCT calibration method could potentially be used for on‐line dose tracking and plan evaluation, without requiring a re‐planning CT session.
Sci‐Thur PM – Colourful Interactions: Highlights 07: Canadian Computed Tomography Survey: National Diagnostic Reference Levels
Authors: Wardlaw Graeme M , Martel Narine
Published: August 2016

Purpose:

The Canadian Computed (CT) Tomography Survey sought to collect CT technology and dose index data (CTDI and DLP) at the national level in order to establish national diagnostic reference levels (DRLs) for seven common CT examinations of standard‐sized adults and pediatric patients.

Methods:

A single survey booklet (consisting of four sections) was mailed to and completed for each participating CT scanner. Survey sections collected data on (i) General facility and scanner information, (ii) routine protocols (as available), (iii) individual patient data (as applied) and (iv) manual CTDI measurements.

Results:

Dose index (CTDIvol and DLP) and associated patient data from 24 280 individual patient exam sequences was analyzed for seven common CT examinations performed in Canada: Adult Head, Chest, Abdomen/Pelvis, and Chest/Abdomen/Pelvis, and Pediatric Head, Chest, and Abdomen. Pediatric examination data was sub‐divided into three age ranges: 0–3, 3–7 and 7–13 years.

DRLs (75th percentile of dose index distributions) were found for all thirteen groups. Further analysis also permitted segmentation of examination data into 8 sub‐groups, whose dose index data was displayed along with group histograms – showing relative contribution of axial vs. helical, contrast use (C+ vs. C‐), and application of fixed current vs. dose reduction (DR) – 75th percentiles of DR sub‐groups were, in almost all cases, lower than whole group (examination) DRLs.

Conclusions:

The analysis and summaries presented in the pending survey report can serve to aid local CT imaging optimization efforts within Canada and also contribute further to international efforts in radiation protection of patients.
Sci‐Thur PM – Brachytherapy 03: Identifying the impact of seroma visualization on permanent breast seed implant brachytherapy
Authors: Morton Daniel , Batchelar Deidre , Hilts Michelle , Tetreault‐Laflamme Audrey , Mou Benjamin , Lucas Sarah , Crook Juanita
Published: August 2016

Purpose:

Uncertainties in target identification can reduce treatment accuracy in permanent breast seed implant (PBSI) brachytherapy. This study evaluates the relationship between seroma visualization and seed placement accuracy.

Methods:

Spatially co‐registered CT and 3D ultrasound (US) images were acquired for 10 patients receiving PBSI. Seromas were retrospectively contoured independently by 3 radiation oncologists on both CT and US and respective consensus volumes were defined, CTVCT and CTVUS. The seroma clarity and inter‐user conformity index (CI), as well as inter‐modality CI, volume, and positional differences were evaluated. Correlations with seed placement accuracy were then assessed. CTVs were expanded by 1.25cm to create PTVCT and PTVUS and evaluate the conformity with PTVClinical (CTVClinical+1.25cm) used in treatment planning. The change in PTV coincidence by expanding PTVClinical by 0.25cm was determined.

Results:

CTVUS were a mean 68 ± 12% smaller than CTVCT and generally had improved clarity and inter‐user conformity. No correlations between seed displacement and CTVUS‐CTVCT positional difference or CI were observed. Greater seed displacements were associated with larger CTVUS‐CTVCT volume differences (r=−0.65) and inter‐user CT CI (r=−0.74). A median (range) 88% (71–99%) of PTVCT and 83% (69–100%) of PTVUS were contained within PTVClinical. Expanding treatment margins to 1.5cm increased coincidence to 98% (86–100%) and 94% (82–100%), respectively.

Conclusions:

Differences in seroma visualization impacts seed displacement in PBSI. Reducing dependence on CT by incorporating 3DUS into target identification, or expanding CT‐based treatment margins to 1.5cm may reduce or mitigate uncertainties related to seroma visualization.
Sci‐Thur PM – Brachytherapy 06: 3D Printed Surface Applicators for High Dose Rate Brachytherapy
Authors: Clarke Scott , Yewondwossen Mammo , Robar James
Published: August 2016

Purpose:

The purpose of this work is to develop a new applicator for administering high dose rate (HDR) brachytherapy using 3D printing technology. Primary advantages of using a 3D printed applicator will be to offer a more streamlined approach for therapists and patients while achieving better conformity, reproducibility, and patient specific applicators.

Methods:

A phantom study was conducted to measure the effectiveness of a 3D printed surface applicator by analyzing tumours on three locations of the body: the foot, nose, and scalp. The applicator was designed using Eclipse and further modified using Blender to create the catheter tunnels before being printed on a Lulzbot Taz 5 3D printer. A radiation plan was made using Oncentra Brachytherapy for a control treatment option using Freiburg Flaps and one with the novel method of a 3D printed applicator. A comparative analysis was made using D90, D100, V100, V150, and V200

Results:

The 3D printed applicator showed comparable dose coverage with significant improvements on highly irregular surfaces when analyzed against a plan made using Freiburg Flaps. Although both plans exhibited complete tumour coverage, the 3D applicator showed improvements in D90 and V150 and the 3D applicator had a dose homogeneity index (DHI) of 0.99 compared to a DHI of 0.97 for the control. Therapist prep time also dropped significantly due to the lack of need for a thermoplastic mesh.

Conclusions:

3D printed applicators for treatment of superficial sites proved to offer more patient convenience, less prep time, better conformity and tighter margins.
Poster ‐ 17: Characterization and correction of radiation induced background in scanning water tanks
Authors: Ali Elsayed
Published: August 2016

Purpose:

To characterize and correct for radiation‐induced background (RIB) observed in the signals from a class of scanning water tanks.

Methods:

A method was developed to isolate the RIB through detector measurements in the background‐free linac console area. Variation of the RIB against a large number of parameters was characterized, and its impact on basic clinical data for photon and electron beams was quantified. Different methods to minimize and/or correct for the RIB were proposed and evaluated.

Results:

The RIB is due to the presence of the electrometer and connection box in a low background radiation field (by design). The absolute RIB current with a biased detector is up to 2 pA, independent of the detector size, which is 0.6% and 1.5% of the central axis reference signal for a standard and a mini scanning chamber, respectively. The RIB monotonically increases with field size, is three times smaller for detectors that do not require a bias (e.g., diodes), is up to 80% larger for positive (versus negative) polarity, decreases with increasing photon energy, exhibits a single curve versus dose rate at the electrometer location, and is negligible for electron beams. Data after the proposed field‐size correction method agree with point measurements from an independent system to within a few tenth of a percent for output factor, head scatter, depth dose at depth, and out‐of‐field profile dose. Manufacturer recommendations for electrometer placement are insufficient and sometimes incorrect.

Conclusions:

RIB in scanning water tanks can have a non‐negligible effect on dosimetric data.