bluuebunny/crossref_metadata_2025_split huggingface dataset:
Secular Sediment Waves, Channel Bed Waves, and Legacy Sediment
Authors: Allan James L. 
Published: June 2010

AbstractThe concept of sediment waves is reviewed and clarifications are proposed for nomenclature concerning vertical channel responses to large fluvial sediment fluxes over a period of a decade or longer. Gilbert’s (1917) original sediment waves are re‐evaluated at their type locale and used to develop a consistent set of definitions. A ‘sediment wave’ represents a transient sediment flux that includes but is not necessarily identical to a ‘channel bed wave’ that represents the rise and fall of the bed in response to sedimentation. A large‐scale sediment wave results when a major sediment‐delivery event generates an aggradation–degradation episode (ADE). It may leave a legacy of sediment deposited on valley bottoms. Gilbert’s classic sediment‐wave model was empirically based on changes in bed elevations but was described as a sediment flux. He described downstream translation of an attenuating symmetrical wave although it was too large and disjointed to have a coherent waveform. Rapid return of bed elevations to pre‐sedimentation levels in Gilbert’s wave should not be mistaken for exhaustion of sediment. The common concept of a symmetrical sediment wave representing the time series of sediment loads is not accurate for large‐scale sedimentation events that store and slowly release sediment on floodplains. Large sediment waves composed of relatively fine material and limited bed armoring tend to be right‐skewed owing to rapid vertical readjustments relative to slow lateral recruitment of stored sediment. A revised right‐skewed conceptual model of large sediment and bed waves is presented that fits modern observations and incorporates stochastic elements of flood events. Large sediment waves may be linked to legacy sediment; that is, large repositories of anthropogenic alluvium stored on valley bottom floodplains, wetlands, mill ponds, and reservoirs. This illustrates the ubiquity and importance of secular sediment waves to river management.
Revisiting the Medieval Black Death of 1347–1351: Spatiotemporal Dynamics Suggestive of an Alternate Causation
Authors: Welford Mark , Bossak Brian H. 
Published: June 2010

AbstractRecent research points to multiple inconsistencies regarding modernYersinia pestis(in Bubonic, Pneumonic, or Septicemic Plague variants) as a causative agent for the Medieval Black Death (MBD). Published arguments at odds with aY. pestis‐caused epidemic include differences in recorded periodicity, seasonal mortality peaks, relevant biogeographical details, genetic findings, and spatiotemporal dynamics, among other inconsistencies. Here, we describe and expand on some of the recent literature noting these items. In addition, we discuss preliminary research related to our recently published theory, in which we agree with research suggesting that the MBD was caused by a virus, not a bacterium, and elucidate our contention that seasonal changes and medieval human trade patterns controlled the timing of peak mortality during the MBD and subsequent ‘plagues’. Epidemic evidence from the first epidemic wave and later outbreaks is presented in support of our hypothesis.
The Design and Experimental Validation of an Ultrafast Shape Memory Alloy ResetTable (SMART) Latch
Authors: Redmond John A. , Brei Diann , Luntz Jonathan , Browne Alan L. , Johnson Nancy L. , Strom Kenneth A. 
Published: June 2010

Abstract
Latches are essential machine elements utilized by all sectors (military, automotive, consumer, manufacturing, etc.) with a growing need for active capabilities such as automatic release and reset, which require actuation. Shape memory alloy (SMA) actuation is an attractive alternative technology to conventional actuation (electrical, hydraulic, etc.) because SMA, particularly in the wire form, is simple, inexpensive, lightweight, and compact. This paper introduces a fundamental latch technology, referred to as the T-latch, which is driven by an ultrafast SMA wire actuator that employs a novel spool-packaged architecture to produce the necessary rotary release motion within a compact footprint. The T-latch technology can engage passively, maintain a strong structural connection in multiple degrees of freedom with zero power consumption, actively release within a very short timeframe (&lt;20 ms, utilizing the SMA spooled actuator), and then repeat operation with automatic reset. The generic architecture of the T-latch and governing operational behavioral models discussed within this paper provide the background for synthesizing basic active latches across a broad range of applications. To illustrate the utility and general operation of the T-latch, a proof-of-concept prototype was designed, built, and experimentally characterized regarding the basic functions of engagement, retention, release, and reset for a common case study of automotive panel lockdown. Based on the successful demonstration and model validation presented in this study, the T-latch demonstrates its promise as an attractive alternative technology to conventional technologies with the potential to enable simple, low-cost, lightweight, and compact active latches across a broad range of industrial applications.
Investigation of three radiation detectors for accurate measurement of absorbed dose in nonstandard fields
Authors: Chung Eunah , Bouchard Hugo , Seuntjens Jan 
Published: June 2010

PurposeTo establish accurate experimental dosimetry techniques for reference dose measurements in nonstandard composite fields.MethodsA cylindrical PMMA phantom filled with water was constructed, at the center of which reference absorbed dose to water for a head and neck IMRT delivery was measured. Based on the proposed new formalism for reference dosimetry of nonstandard fields [Alfonso et al., Med. Phys. 35, 5179–5186 (2008)], a candidate plan‐class specific reference (pcsr) field for a typical head and neck IMRT delivery was created on the CT images of the phantom. The absorbed dose to water in the pcsr field normalized to that in a reference field was measured using three radiation detectors: Gafchromic® EBT films, a diamond detector, and a guarded liquid‐filled ionization chamber developed in‐house (GLIC‐03). Pcsr correction factors were determined for five different types of air‐filled ionization chambers (Exradin A12, NE2571, Exradin A1SL, Exradin A14, and PinPoint® 31006) in a fully rotated delivery and in a delivery with the same MLC settings and weights but from a single gantry angle (a collapsed delivery).ResultsThe combined standard uncertainty in measuring the correction factor using the three dosimetry techniques was 0.3%. For all the air‐filled ionization chambers and the pcsr field tested, the correction factor was not different from unity by more than ±0.8%. For the fully rotated delivery, the correction factors were in a narrow range of 0.9955–0.9986, while in the collapsed delivery, they were in a slightly broader range of 0.9922–1.0048. In the collapsed delivery, the Farmer‐type chambers (Exradin A12 and NE2571) had very similar correction factors (0.9922 and 0.9931, respectively), whereas the correction factors for the smaller chambers showed more distinct chamber‐type dependence.ConclusionsThe authors have established three experimental dosimetry techniques that allow reference measurements of nonstandard field correction factors for air‐filled ionization chambers at the 0.3% uncertainty level. These techniques can be used to determine criteria for the selection of plan‐class specific reference fields and ultimately improve clinical reference dosimetry of nonstandard fields.
Generalized fractal dimensions of laser Doppler flowmetry signals recorded from glabrous and nonglabrous skin
Authors: Buard Benjamin , Mahé Guillaume , Chapeau‐Blondeau François , Rousseau David , Abraham Pierre , Humeau Anne 
Published: June 2010

PurposeThe technique of laser Doppler flowmetry (LDF) is commonly used to have a peripheral view of the cardiovascular system. To better understand the microvascular perfusion signals, the authors herein propose to analyze and compare the complexity of LDF data recorded simultaneously in glabrous and nonglabrous skin. Glabrous zones are physiologically different from the others partly due to the presence of a high density of arteriovenous anastomoses.MethodsFor this purpose, a multifractal analysis based on the partition function and generalized fractal dimensions computation is proposed. The LDF data processed are recorded simultaneously on the right and left forearms and on the right and left hand palms of healthy subjects. The signal processing method is first tested on a multifractal binomial measure. The generalized fractal dimensions of the normalized LDF signals are then estimated. Furthermore, for the first time, the authors estimate the generalized fractal dimensions from a range of scales corresponding to factors influencing the microcirculation flow (cardiac, respiratory, myogenic, neurogenic, and endothelial).ResultsDifferent multifractal behaviors are found between normalized LDF signals recorded in the forearms and in the hand palms of healthy subjects. Thus, the variations in the estimated generalized fractal dimensions of LDF signals recorded in the hand palms are higher than those of LDF signals recorded in the forearms. This shows that LDF signals recorded in glabrous zones may be more complex than those recorded in nonglabrous zones. Furthermore, the results show that the complexity in the hand palms could be more important at scales corresponding to the myogenic control mechanism than at the other studied scales.ConclusionsThese findings suggest that the multifractality of the normalized LDF signals is different on glabrous and nonglabrous skin. This difference may rely on the density of arteriovenous anastomoses and differences in nerve supply or biochemical properties. This study provides useful information for an in‐depth understanding of LDF data and a more detailed knowledge of the peripheral cardiovascular system.
Monte Carlo calculation of dosimetry parameters for the IR08‐ brachytherapy source
Authors: Saidi Pooneh , Sadeghi Mahdi , Shirazi Alireza , Tenreiro Claudio 
Published: June 2010

PurposeFor the treatment of some cancerous tumors using brachytherapy methods and low‐energy photon sources, such as and , the American Association of Physicists in Medicine Task Group No. 43U1 report recommends that the dosimetric parameters of a new brachytherapy source must be determined in two experimental and Monte Carlo theoretical methods before using each new source clinically. This study presents the results of Monte Carlo calculations of the dosimetric parameters for IR08‐ brachytherapy source design. IR08‐ seed has been manufactured at the Agricultural, Medical and Industrial Research School.MethodsVersion 5 of the (MCNP) Monte Carlo radiation transport code was used to calculate the dosimetry parameters around the source. Three geometric models of the seed, based on different locations of beads inside the titanium capsule, were simulated. The seed contains five resin beads of 0.6 mm diameter having uniformly absorbed in the bead volume, which were contained within a cylindrical titanium capsule having 0.8 mm outside diameter and 4.8 mm length.ResultsThe Monte Carlo calculated dose rate constant of the IR08‐ seed was found to be . Also in this study, the geometry function , line and point‐source radial dose functions and , and the anisotropy function , have been calculated at distances from 0.25 to 7 cm. The results of these calculations have been compared with measured values for an actual IR08‐ seed.ConclusionsThere are no statistical significant dosimetric differences among the three seed orientations in this study (i.e., ideal, vertical, and diagonal). However, the observed differences between the calculated and measured values could be explained by the measurement uncertainty and the configuration of the resin beads within the capsule and capsule orientation.
Performance evaluation of polycrystalline photoconductors for radiation therapy imaging
Authors: Zhao Qihua , Antonuk Larry E. , El‐Mohri Youcef , Wang Yi , Du Hong , Sawant Amit , Su Zhong , Yamamoto Jin 
Published: June 2010

PurposeElectronic portal imaging devices based on megavoltage (MV), active matrix, flat‐panel imagers (AMFPIs) are presently regarded as the gold standard in portal imaging for external beam radiation therapy. These devices, employing indirect detection of incident radiation by means of a metal plate plus phosphor screen combination, offer a quantum efficiency of only at 6 MV, leading to a detective quantum efficiency (DQE) of only . In order to significantly improve the DQE performance of MV AMFPIs, a strategy based on the development of direct detection imagers incorporating thick films of polycrystalline mercuric iodide photoconductor was undertaken and is reported.MethodsTwo MV AMFPI prototypes, one incorporating an thick layer created through physical vapor deposition (PVD) and a second incorporating an thick layer created through screen‐printing of particle‐in‐binder (PIB) material, were quantitatively evaluated using a 6 MV photon beam. The reported measurements include empirical determination of x‐ray sensitivity, lag, modulation transfer function (MTF), noise power spectrum, and DQE.ResultsFor both prototypes, MTF and DQE results were found to be consistent with theoretical expectations and the MTFs were also found to be higher than that measured from a conventional MV AMFPI. In addition, the DQE results exhibit input‐quantum‐limited behavior, even at extremely low doses. Compared to PVD, the PIB prototype exhibits much lower dark current, slightly higher lag, and similar DQE. Finally, the challenges associated with this approach, as well as strategies for achieving considerably higher DQE through thicker layers, are discussed.ConclusionsThe DQE of each of the prototypes is found to be comparable to that of conventional MV AMFPIs, commensurate with the modest photoconductor thicknesses of these early samples. It is anticipated that thicker layers of based on PIB deposition can provide higher DQE while maintaining good material properties.
Assessment of the individual fracture risk of the proximal femur by using statistical appearance models
Authors: Schuler Benedikt , Fritscher Karl D. , Kuhn Volker , Eckstein Felix , Link Thomas M. , Schubert Rainer 
Published: June 2010

PurposeStandard diagnostic techniques to quantify bone mineral density (BMD) include dual‐energy x‐ray absorptiometry (DXA) and quantitative computed tomography. However, BMD alone is not sufficient to predict the fracture risk for an individual patient. Therefore, the development of tools, which can assess the bone quality in order to predict individual biomechanics of a bone, would mean a significant improvement for the prevention of fragility fractures. In this study, a new approach to predict the fracture risk of proximal femora using a statistical appearance model will be presented.Methods100 CT data sets of human femur cadaver specimens are used to create statistical appearance models for the prediction of the individual fracture load (FL). Calculating these models offers the possibility to use information about the inner structure of the proximal femur, as well as geometric properties of the femoral bone for FL prediction. By applying principal component analysis, statistical models have been calculated in different regions of interest. For each of these models, the individual model parameters for each single data set were calculated and used as predictor variables in a multilinear regression model. By this means, the best working region of interest for the prediction of FL was identified. The accuracy of the FL prediction was evaluated by using a leave‐one‐out cross validation scheme. Performance of DXA in predicting FL was used as a standard of comparison.ResultsThe results of the evaluative tests demonstrate that significantly better results for FL prediction can be achieved by using the proposed model‐based approach than using DXA‐BMD for the prediction of fracture load.ConclusionsThe results of the evaluation show that the presented model‐based approach is very promising and also comparable to studies that partly used higher image resolutions for bone quality assessment and fracture risk prediction.
Accuracy estimation for projection‐to‐volume targeting during rotational therapy: A feasibility study
Authors: Long Yong , Fessler Jeffrey A. , Balter James M. 
Published: June 2010

PurposeEstimating motion and deformation parameters from a series of projection radiographs acquired during arc therapy using a reference CT volume has become a promising technique for targeting treatment. The purpose of this work is to investigate the influence of rotational arc length on maximum achievable accuracy of motion estimation.MethodsThe projection‐to‐volume alignment procedure used a nonrigid model to describe motion in thorax area, a cost function consisting of a least‐squared error metric and a simple regularizer that encourages local invertibility, and a four‐level multiresolution scheme with a conjugate gradient method to optimize the cost function. The authors tested both small and large scale deformations typically found in the thorax of a radiotherapy patient at different breathing states and limited‐angle scans of six angular widths (12°, 18°, 24°, 36°, 60°, and 90°) centered at three angles (0°, 45°, and 90°).ResultsThe experiments illustrate the potential accuracy of limited‐angle projection‐to‐volume alignment. Registration accuracy can be sensitive to angular center, tends to be lower along direction of the projection set, and tends to decrease away from the rotation center. The studies of small as well as large but realistically scaled deformations show similar dependencies. These trends appear to have fairly low sensitivity to quantum noise effects.ConclusionsThere is potentially sufficient information present in a small spread of projections to monitor the configuration of reasonably high contrast tumors without implanted markers.
Simulation study on the heating of the surrounding anatomy during transurethral ultrasound prostate therapy: A 3D theoretical analysis of patient safety
Authors: Burtnyk Mathieu , Chopra Rajiv , Bronskill Michael 
Published: June 2010

PurposeMRI‐guided transurethral ultrasound therapy can generate highly accurate volumes of thermal coagulation conforming to 3D human prostate geometries. This work simulated, quantified, and evaluated the thermal impact of these treatments on the rectum, pelvic bone, neurovascular bundles (NVBs), and urinary sphincters because damage to these structures can lead to complications.MethodsTwenty 3D anatomical models of prostate cancer patients were used with detailed bioacoustic simulations incorporating an active feedback algorithm which controlled a rotating, planar ultrasound transducer (17, elements, ). Heating of the adjacent surrounding anatomy was evaluated at 4.7, 9.7, and 14.2 MHz using thermal tolerances reported in literature.ResultsHeating of the rectum posed the most important safety concern, influenced largely by the water temperature of an endorectal cooling device (ECD); depending on anatomy, temperatures of were required to limit potential damage to less than on the outer 1 mm layer of the rectal wall. Heating of the pelvic bone could be important at 4.7 MHz. A smaller sized ECD or a higher ultrasound frequency in sectors where the bone was less than 10 mm from the prostate reduced heating in all cases below the threshold for irreversible damage. Heating of the NVB was significant in 75% of the patient models in the absence of treatment planning; this proportion was reduced to 5% by increasing treatment margins up to 4 mm. To avoid damaging the urinary sphincters, the transducer should be positioned at least 2–4 mm from the sphincters, depending on the transurethral cooling temperature.ConclusionsSimulations show that MRI‐guided transurethral therapy can treat the prostate accurately, but in the absence of treatment planning, some thermal impact can be predicted on the surrounding anatomy. Treatment planning strategies have been developed, which reduce thermal injury to the surrounding anatomy.
Repeatability in computer‐aided diagnosis: Application to breast cancer diagnosis on sonography
Authors: Drukker Karen , Pesce Lorenzo , Giger Maryellen 
Published: June 2010

PurposeThe aim of this study was to investigate the concept of repeatability in a case‐based performance evaluation of two classifiers commonly used in computer‐aided diagnosis in the task of distinguishing benign from malignant lesions.MethodsThe authors performed bootstrap analyses using a data set of 1251 sonographic lesions of which 212 were malignant. Several analyses were performed investigating the impact of sample size and number of bootstrap iterations. The classifiers investigated were a Bayesian neural net (BNN) with five hidden units and linear discriminant analysis (LDA). Both used the same four input lesion features. While the authors did evaluate classifier performance using receiver operating characteristic (ROC) analysis, the main focus was to investigate case‐based performance based on the classifier output for individual cases, i.e., the classifier outputs for each test case measured over the bootstrap iterations. In this case‐based analysis, the authors examined the classifier output variability and linked it to the concept of repeatability. Repeatability was assessed on the level of individual cases, overall for all cases in the data set, and regarding its dependence on the case‐based classifier output. The impact of repeatability was studied when aiming to operate at a constant sensitivity or specificity and when aiming to operate at a constant threshold value for the classifier output.ResultsThe BNN slightly outperformed the LDA with an area under the ROC curve of 0.88 versus 0.85 . In the repeatability analysis on an individual case basis, it was evident that different cases posed different degrees of difficulty to each classifier as measured by the by‐case output variability. When considering the entire data set, however, the overall repeatability of the BNN classifier was lower than for the LDA classifier, i.e., the by‐case variability for the BNN was higher. The dependence of the by‐case variability on the average by‐case classifier output was markedly different for the classifiers. The BNN achieved the lowest variability (best repeatability) when operating at high sensitivity and low specificity , while the LDA achieved this at moderate sensitivity and specificity . When operating at constant 90% sensitivity or constant 90% specificity, the width of the 95% confidence intervals for the corresponding classifier output was considerable for both classifiers and increased for smaller sample sizes. When operating at a constant threshold value for the classifier output, the width of the 95% confidence intervals for the corresponding sensitivity and specificity ranged from 9 percentage points (pp) to 30 pp.ConclusionsThe repeatability of the classifier output can have a substantial effect on the obtained sensitivity and specificity. Knowledge of classifier repeatability, in addition to overall performance level, is important for successful translation and implementation of computer‐aided diagnosis in clinical decision making.