bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Configuration in the Design of Geared Transmission Systems
Authors: Olver A. V.
Published: June 2009

It has been widely observed that the mass (or weight) and cost of geared transmission systems is a relatively simple function of the maximum continuous torques to be transmitted. This fact may be used to derive simple design tools, which allow rapid comparison of the size and mass of a wide range of designs. Particularly influential is the effect of the configuration: the ratio, number, and disposition of the stages of gearing. In the present paper, a “configuration factor” is developed for the design of multistage, multiple layshaft gearboxes, based on a simplified mass comparison of gearsets designed for the same duty. The results are used to explore the effects of ratio-split, thin-rim designs, and layshaft numbers.
Equation-Free/Galerkin-Free Reduced-Order Modeling of the Shallow Water Equations Based on Proper Orthogonal Decomposition
Authors: Esfahanian Vahid , Ashrafi Khosro
Published: June 2009

In this paper, two categories of reduced-order modeling (ROM) of the shallow water equations (SWEs) based on the proper orthogonal decomposition (POD) are presented. First, the traditional Galerkin-projection POD/ROM is applied to the one-dimensional (1D) SWEs. The result indicates that although the Galerkin-projection POD/ROM is suitable for describing the physical properties of flows (during the POD basis functions’ construction time), it cannot predict that the dynamics of the shallow water flows properly as it was expected, especially with complex initial conditions. Then, the study is extended to applying the equation-free/Galerkin-free POD/ROM to both 1D and 2D SWEs. In the equation-free/Galerkin-free framework, the numerical simulation switches between a fine-scale model, which provides data for construction of the POD basis functions, and a coarse-scale model, which is designed for the coarse-grained computational study of complex, multiscale problems like SWEs. In the present work, the Beam & Warming and semi-implicit time integration schemes are applied to the 1D and 2D SWEs, respectively, as fine-scale models and the coefficients of a few POD basis functions (reduced-order model) are considered as a coarse-scale model. Projective integration is applied to the coarse-scale model in an equation-free framework with a time step grater than the one used for a fine-scale model. It is demonstrated that equation-free/Galerkin-free POD/ROM can resolve the dynamics of the complex shallow water flows. Moreover, the computational cost of the approach is less than the one for a fine-scale model.
Active pixel imagers incorporating pixel‐level amplifiers based on polycrystalline‐silicon thin‐film transistors
Authors: El‐Mohri Youcef , Antonuk Larry E. , Koniczek Martin , Zhao Qihua , Li Yixin , Street Robert A. , Lu Jeng‐Ping
Published: June 2009

Active matrix, flat‐panel imagers (AMFPIs) employing a 2D matrix of ‐Si addressing TFTs have become ubiquitous in many x‐ray imaging applications due to their numerous advantages. However, under conditions of low exposures and/or high spatial resolution, their signal‐to‐noise performance is constrained by the modest system gain relative to the electronic additive noise. In this article, a strategy for overcoming this limitation through the incorporation of in‐pixel amplification circuits, referred to as active pixel (AP) architectures, using polycrystalline‐silicon (poly‐Si) TFTs is reported. Compared to ‐Si, poly‐Si offers substantially higher mobilities, enabling higher TFT currents and the possibility of sophisticated AP designs based on both ‐ and ‐channel TFTs. Three prototype indirect detection arrays employing poly‐Si TFTs and a continuous ‐Si photodiode structure were characterized. The prototypes consist of an array (PSI‐1) that employs a pixel architecture with a single TFT, as well as two arrays (PSI‐2 and PSI‐3) that employ AP architectures based on three and five TFTs, respectively. While PSI‐1 serves as a reference with a design similar to that of conventional AMFPI arrays, PSI‐2 and PSI‐3 incorporate additional in‐pixel amplification circuitry. Compared to PSI‐1, results of x‐ray sensitivity demonstrate signal gains of and 20.9 for PSI‐2 and PSI‐3, respectively. These values are in reasonable agreement with design expectations, demonstrating that poly‐Si AP circuits can be tailored to provide a desired level of signal gain. PSI‐2 exhibits the same high levels of charge trapping as those observed for PSI‐1 and other conventional arrays employing a continuous photodiode structure. For PSI‐3, charge trapping was found to be significantly lower and largely independent of the bias voltage applied across the photodiode. MTF results indicate that the use of a continuous photodiode structure in PSI‐1, PSI‐2, and PSI‐3 results in optical fill factors that are close to unity. In addition, the greater complexity of PSI‐2 and PSI‐3 pixel circuits, compared to that of PSI‐1, has no observable effect on spatial resolution. Both PSI‐2 and PSI‐3 exhibit high levels of additive noise, resulting in no net improvement in the signal‐to‐noise performance of these early prototypes compared to conventional AMFPIs. However, faster readout rates, coupled with implementation of multiple sampling protocols allowed by the nondestructive nature of pixel readout, resulted in a significantly lower noise level of (rms) for PSI‐3.
An exposure indicator for digital radiography: AAPM Task Group 116 (Executive Summary)
Authors: Shepard S. Jeff , Wang Jihong , Flynn Michael , Gingold Eric , Goldman Lee , Krugh Kerry , Leong David L. , Mah Eugene , Ogden Kent , Peck Donald , Samei Ehsan , Wang Jihong , Willis Charles E.
Published: June 2009

Digital radiographic imaging systems, such as those using photostimulable storage phosphor, amorphous selenium, amorphous silicon, CCD, and MOSFET technology, can produce adequate image quality over a much broader range of exposure levels than that of screen/film imaging systems. In screen/film imaging, the final image brightness and contrast are indicative of over‐ and underexposure. In digital imaging, brightness and contrast are often determined entirely by digital postprocessing of the acquired image data. Overexposure and underexposures are not readily recognizable. As a result, patient dose has a tendency to gradually increase over time after a department converts from screen/film‐based imaging to digital radiographic imaging. The purpose of this report is to recommend a standard indicator which reflects the radiation exposure that is incident on a detector after every exposure event and that reflects the noise levels present in the image data. The intent is to facilitate the production of consistent, high quality digital radiographic images at acceptable patient doses. This should be based not on image optical density or brightness but on feedback regarding the detector exposure provided and actively monitored by the imaging system. A standard beam calibration condition is recommended that is based on RQA5 but uses filtration materials that are commonly available and simple to use. Recommendations on clinical implementation of the indices to control image quality and patient dose are derived from historical tolerance limits and presented as guidelines.
General strategy for the protection of organs at risk in IMRT therapy of a moving body
Authors: Abolfath Ramin M. , Papiez Lech
Published: June 2009

We investigated protection strategies of organs at risk (OARs) in intensity modulated radiation therapy (IMRT). These strategies apply to delivery of IMRT to moving body anatomies that show relative displacement of OAR in close proximity to a tumor target. We formulated an efficient genetic algorithm which makes it possible to search for global minima in a complex landscape of multiple irradiation strategies delivering a given, predetermined intensity map to a target. The optimal strategy was investigated with respect to minimizing the dose delivered to the OAR. The optimization procedure developed relies on variability of all parameters available for control of radiation delivery in modern linear accelerators, including adaptation of leaf trajectories and simultaneous modification of beam dose rate during irradiation. We showed that the optimization algorithms lead to a significant reduction in the dose delivered to OAR in cases where organs at risk move relative to a treatment target.
Prospective cardiac gating of carotid three‐dimensional ultrasound
Authors: Mallett Christiane , Gardi Lori , Fenster Aaron , Parraga Grace
Published: June 2009

Quantitative measurements of carotid atherosclerosis can be determined using three‐dimensional ultrasound (3DUS). This pilot study involved the development of prospective cardiac gating of 3DUS carotid images to reduce cardiac cycle‐derived arterial pulsatility. The method developed uses electrocardiograph signal detection of the cardiac cycle wave with imaging acquisition delayed in time after the wave is detected. Pulsatility of the common carotid artery was measured by calculating the mean percentage change in arterial cross‐sectional area in moderate atherosclerosis (MA) patients and healthy volunteers (HVs) and found that was significantly higher for HV than for MA when no cardiac gating was used. The cardiac gating method was tested with and in young healthy volunteers and rheumatoid arthritis (RA) patients. For all 3DUS measurements acquired without gating, there was a significant association between and age (, ), and mean (in HV and RA) was [95% confidence interval ]. For mean was significantly different and decreased to (95% ) and for it was significantly different and decreased to (95% ) ( for both comparisons). There was no significant difference in mean between gating conditions ; however, the 95% CI for was decreased for as compared to . Both gating methods also significantly decreased to below the reference standard of for MA ( for both comparisons), suggesting that prospective cardiac gating of carotid 3DUS reduces pulsatility effects in HV and RA to levels lower than observed for much older MA patients.
Fractionated stereotactic radiotherapy: A method to evaluate geometric and dosimetric uncertainties using radiochromic films
Authors: Coscia Gianluca , Vaccara Elena , Corvisiero Roberta , Cavazzani Paolo , Ruggieri Filippo Grillo , Taccini Gianni
Published: June 2009

In the authors’ hospital, stereotactic radiotherapy treatments are performed with a Varian Clinac 600C equipped with a BrainLAB micro‐multileaf‐collimator generally using the dynamic conformal arc technique. Patient immobilization during the treatment is achieved with a fixation mask supplied by BrainLAB, made with two reinforced thermoplastic sheets fitting the patient's head. With this work the authors propose a method to evaluate treatment geometric accuracy and, consequently, to determine the amount of the margin to keep in the CTV‐PTV expansion during the treatment planning. The reproducibility of the isocenter position was tested by simulating a complete treatment on the anthropomorphic phantom Alderson Rando, inserting in between two phantom slices a high sensitivity Gafchromic EBT film, properly prepared and calibrated, and repeating several treatment sessions, each time removing the fixing mask and replacing the film inside the phantom. The comparison between the dose distributions measured on films and computed by TPS, after a precise image registration procedure performed by a commercial piece of software (FILMQA, 3cognition LLC (Division of ISP), Wayne, NJ), allowed the authors to measure the repositioning errors, obtaining about 0.5 mm in case of central spherical PTV and about 1.5 mm in case of peripheral irregular PTV. Moreover, an evaluation of the errors in the registration procedure was performed, giving negligible values with respect to the quantities to be measured. The above intrinsic two‐dimensional estimate of treatment accuracy has to be increased for the error in the third dimension, but the 2 mm margin the authors generally use for the CTV‐PTV expansion seems adequate anyway. Using the same EBT films, a dosimetric verification of the treatment planning system was done. Measured dose values are larger or smaller than the nominal ones depending on geometric irradiation conditions, but, in the authors’ experimental conditions, always within 4%.
Dosimetric effects of rotational output variation and x‐ray target degradation on helical tomotherapy plans
Authors: Staton Robert J. , Langen Katja M. , Kupelian Patrick A. , Meeks Sanford L.
Published: June 2009

In this study, two potential sources of IMRT delivery error have been identified for helical tomotherapy delivery using the HiART system (TomoTherapy, Inc., Madison, WI): Rotational output variation and target degradation. The HiArt system is known to have output variation, typically about ±2%, due to the absence of a dose servo system. On the HiArt system, x‐ray target replacement is required approximately every 10–12 months due to target degradation. Near the end of target life, the target thins and causes a decrease in the beam energy and a softening of the beam profile at the lateral edges of the beam. The purpose of this study is to evaluate the dosimetric effects of rotational output variation and target degradation by modeling their effects and incorporating them into recalculated treatment plans for three clinical scenarios: Head and neck, partial breast, and prostate. Models were created to emulate both potential sources of error. For output variation, a model was created using a sine function to match the amplitude (±2%), frequency, and phase of the measured rotational output variation data. A second model with a hypothetical variation of ±7% was also created to represent the largest variation that could exist without violating the allowable dose window in the delivery system. A measured beam profile near the end of target life was used to create a modified beam profile model for the target degradation. These models were then incorporated into the treatment plan by modifying the leaf opening times in the delivery sinogram. A new beam model was also created to mimic the change in beam energy seen near the end of target life. The plans were then calculated using a research version of the PLANNED ADAPTIVE treatment planning software from TomoTherapy, Inc. Three plans were evaluated in this study: Head and neck, partial breast, and prostate. The of organs at risk, the for planning target volumes (PTVs), and the local dose difference were used to evaluate the changes in the modified treatment plans. Dosimetric effects from rotational variation were found to be low (less than 1%) for a typical variation of ±2%. Even using a variation of ±7%, DVH values and dose distributions were altered by less than 2% for all scenarios. The dosimetric effects of target degradation were found to be slightly more significant. For a model using data taken just before target failure, dosimetric differences of 2%–4% were observed in the recalculated plans when compared to the original plans. The largest effects (up to 4.5%) were observed for PTVs that were located at deeper depths as seen in the prostate plan. Overall, the recalculated plans show that the dosimetric effects of rotational variation and target degradation are on the order of 1%–4% for helical tomotherapy on the HiART system and do not pose a risk for significant deviations from the original treatment plan.
Classification of trabeculae into three‐dimensional rodlike and platelike structures via local inertial anisotropy
Authors: Vasilić Branimir , Rajapakse Chamith S. , Wehrli Felix W.
Published: June 2009

Trabecular bone microarchitecture is a significant determinant of the bone's mechanical properties and is thus of major clinical relevance in predicting fracture risk. The three‐dimensional nature of trabecular bone is characterized by parameters describing scale, topology, and orientation of structural elements. However, none of the current methods calculates all three types of parameters simultaneously and in three dimensions. Here the authors present a method that produces a continuous classification of voxels as belonging to platelike or rodlike structures that determines their orientation and estimates their thickness. The method, dubbed local inertial anisotropy (LIA), treats the image as a distribution of mass density and the orientation of trabeculae is determined from a locally calculated tensor of inertia at each voxel. The orientation entropies of rods and plates are introduced, which can provide new information about microarchitecture not captured by existing parameters. The robustness of the method to noise corruption, resolution reduction, and image rotation is demonstrated. Further, the method is compared with established three‐dimensional parameters including the structure‐model index and topological surface‐to‐curve ratio. Finally, the method is applied to data acquired in a previous translational pilot study showing that the trabecular bone of untreated hypogonadal men is less platelike than that of their eugonadal peers.
Skeletal dosimetry in cone beam computed tomography
Authors: Walters B. R. B. , Ding G. X. , Kramer R. , Kawrakow I.
Published: June 2009

Cone beam computed tomography (CBCT) is a relatively new patient imaging technique that has proved invaluable for treatment target verification and patient positioning during image‐guided radiotherapy (IGRT). It has been shown that CBCT results in additional dose to bone that may amount to 10% of the prescribed dose. In this study, voxelized human phantoms, FAX06 (adult female) and MAX06 (adult male), are used together with phase‐space data collected from a realistic model of a CBCT imager to calculate dose in the red bone marrow (RBM) and bone surface cells (BSCs), the two organs at risk within the bone spongiosa, during simulated head and neck, chest and pelvis CBCT scans. The FAX06/MAX06 phantoms model spongiosa based on micro‐CT images, filling the relevant phantom voxels, which are , with microvoxels to form a micromatrix of trabecular bone and bone marrow. FAX06/MAX06 have already been implemented in an EGSnrc‐based Monte Carlo code to simulate radiation transport in the phantoms; however, this study required significant modifications of the code to allow use of phase‐space data from a simulated CBCT imager as a source and to allow scoring of total dose, RBM dose and BSC dose on a voxel‐by‐voxel basis. In simulated CBCT scans, the BSC dose is significantly greater than the dose to other organs at risk. For example, in a simulated head and neck scan, the average BSC dose is 25% higher than the average dose to eye lens , and 80% greater than the average dose to brain . Average dose to RBM, on the other hand, is typically only of the average BSC dose and less than the dose to other organs at risk (54% of the dose to eye lens and 76% of dose to brain in a head and neck scan). Thus, elevated dose in bone due to CBCT results in elevated BSC dose. This is potentially of concern when using CBCT in conjunction with radiotherapy treatment.
Pharmacokinetic analysis of tissue microcirculation using nested models: Multimodel inference and parameter identifiability
Authors: Brix Gunnar , Zwick Stefan , Kiessling Fabian , Griebel Jürgen
Published: June 2009

The purpose of this study is to evaluate the identifiability of physiological tissue parameters by pharmacokinetic modeling of concentration‐time curves derived under conditions that are realistic for dynamic‐contrast‐enhanced (DCE) imaging and to assess the information‐theoretic approach of multimodel inference using nested models. Tissue curves with a realistic noise level were simulated by means of an axially distributed multipath reference model using typical values reported in literature on plasma flow, permeability‐surface area product, and volume fractions of the intravascular and interstitial space. The simulated curves were subsequently analyzed by a two‐compartment model containing these physiological quantities as fit parameters as well as by two reduced models with only three and two parameters formulated for the case of a permeability‐limited and a flow‐limited scenario, respectively. The competing models were ranked according to Akaike's information criterion (AIC), balancing the bias versus variance trade‐off. To utilize the information available from all three models, model‐averaged parameters were estimated using Akaike weights that quantify the relative strength of evidence in favor of each model. As compared to the full model, the reduced models yielded equivalent or even superior AIC values for scenarios where the structural information in the tissue curves on either the plasma flow or the capillary permeability was limited. Multimodel inference took effect to a considerable extent in half of the curves and improved the precision of the estimated tissue parameters. As theoretically expected, the plasma flow was subject to a systematic (but largely correctable) overestimation, whereas the other three physiological tissue parameters could be determined in a numerically robust and almost unbiased manner. The presented concept of pharmacokinetic analysis of noisy DCE data using three nested models under an information‐theoretic paradigm offers promising prospects for the noninvasive quantification of physiological tissue parameters.
Automatic lung segmentation from thoracic computed tomography scans using a hybrid approach with error detection
Authors: van Rikxoort Eva M. , de Hoop Bartjan , Viergever Max A. , Prokop Mathias , van Ginneken Bram
Published: June 2009

Lung segmentation is a prerequisite for automated analysis of chest CT scans. Conventional lung segmentation methods rely on large attenuation differences between lung parenchyma and surrounding tissue. These methods fail in scans where dense abnormalities are present, which often occurs in clinical data. Some methods to handle these situations have been proposed, but they are too time consuming or too specialized to be used in clinical practice. In this article, a new hybrid lung segmentation method is presented that automatically detects failures of a conventional algorithm and, when needed, resorts to a more complex algorithm, which is expected to produce better results in abnormal cases. In a large quantitative evaluation on a database of 150 scans from different sources, the hybrid method is shown to perform substantially better than a conventional approach at a relatively low increase in computational cost.
A simple backprojection algorithm for 3D in vivo EPID dosimetry of IMRT treatments
Authors: Wendling Markus , McDermott Leah N. , Mans Anton , Sonke Jan‐Jakob , van Herk Marcel , Mijnheer Ben J.
Published: June 2009

Treatment plans are usually designed, optimized, and evaluated based on the total 3D dose distribution, motivating a total 3D dose verification. The purpose of this study was to develop a 2D transmission‐dosimetry method using an electronic portal imaging device (EPID) into a simple 3D method that provides 3D dose information. In the new method, the dose is reconstructed within the patient volume in multiple planes parallel to the EPID for each gantry angle. By summing the 3D dose grids of all beams, the 3D dose distribution for the total treatment fraction is obtained. The algorithm uses patient contours from the planning CT scan but does not include tissue inhomogeneity corrections. The 3D EPID dosimetry method was tested for IMRT fractions of a prostate, a rectum, and a head‐and‐neck cancer patient. Planned and in vivo‐measured dose distributions were within 2% at the dose prescription point. Within the 50% isodose surface of the prescribed dose, at least 97% of points were in agreement, evaluated with a 3D method with criteria of 3% of the prescribed dose and . Full 3D dose reconstruction on a grid and 3D evaluation took less than for one fraction on a standard PC. The method allows in vivo determination of 3D dose‐volume parameters that are common in clinical practice. The authors conclude that their EPID dosimetry method is an accurate and fast tool for in vivo dose verification of IMRT plans in 3D. Their approach is independent of the treatment planning system and provides a practical safety net for radiotherapy.
An enhanced sector integration model for output and dose distribution calculation of irregular concave shaped electron beams
Authors: Gajewski Romuald
Published: June 2009

A comprehensive method of output factor and dose distribution calculation for electron beams has been developed. It allows one to calculate the output factors and isodose distributions in water of arbitrary shaped electron fields with excellent accuracy even for the cases of concaved, small, elongated beams, and extended source to surface distances (SSDs). The method requires two sets of data: Depth dose distribution per monitor unit for circular cutouts and depth dose distributions per monitor unit for circular blocks (plugs), both for two SSDs, one reference ofand second extended one. The method has been extensively tested using a combination of different irregular cutouts and various SSDs for the 6 andelectron beams. The calculated values agreed with the measured data well within 1% for output factors and below 1 for(gamma test) for isodose distributions. The computer program has been developed to facilitate the method for practical application. The method has been used for almostconsiderably cutting workload in the department.
A real‐time prostate cancer detection technique using needle insertion force and patient‐specific criteria during percutaneous intervention
Authors: Yan K. , Podder T. , Li L. , Joseph J. , Rubens D. R. , Messing E. M. , Liao L. , Yu Y.
Published: June 2009

In this article, the authors present a novel real‐time cancer detection technique by using needle insertion forces in conjunction with patient‐specific criteria during percutaneous interventions. Needle insertion experiments and pathological analysis were performed for developing a computer‐aided detection (CAD) model. Backward stepwise regression method was performed to identify the statistically significant patient‐specific factors. A baseline force model was then developed using these significant factors. The threshold force model that estimated the lower bound of the cancerous tissue forces was formulated by adding an adjustable classifier to the baseline force model. Trade‐off between sensitivity and specificity was obtained by varying the threshold value of the classifier, from which the receiver‐operating characteristic (ROC) curve was generated. Sequential quadratic programming was used to optimize the CAD model by maximizing the area under the ROC curve (AUC) using a set of model‐training patient data. When the CAD model was evaluated using an independent set of model‐validation patient data, an AUC of 0.90 was achieved. The feasibility of cancer detection in real time during percutaneous interventions was established.
Quantitative contrast‐enhanced myocardial perfusion magnetic resonance imaging: Simulation of bolus dispersion in constricted vessels
Authors: Graafen Dirk , Münnemann Kerstin , Weber Stefan , Kreitner Karl‐Friedrich , Schreiber Laura M.
Published: June 2009

Quantification of myocardial blood flow (MBF) by means of ‐weighted first‐pass magnetic resonance imaging (MRI) requires knowledge of the arterial input function (AIF), which is usually estimated from the left ventricle (LV). Dispersion of the contrast agent bolus may occur between the LV and the tissue of interest, which leads to systematic underestimation of the MBF. The aim of this study was to simulate the dispersion along a simplified coronary artery with different stenoses. To analyze the dispersion in vessels with typical dimensions of coronary arteries, simulations were performed using the computational fluid dynamics approach. Simulations were accomplished on straight vessels with integrated stenoses of different degrees of area reduction and length as well as two different shapes—an axial symmetric and an asymmetric. Two boundary conditions were used representing myocardial blood flow at rest and under hyperemic conditions. The results under steady boundary conditions show that the dispersion is more pronounced in resting condition than during hyperemia yielding an underestimation of the MBF around 15% in the resting state and around 8% under stress conditions. At the outlet of the vessel an axial symmetric stenosis results in increased dispersion whereas an asymmetric stenosis yields a reduction. Due to the more severe dispersion, resting MBF may be more underestimated in quantitative myocardial perfusion MRI studies compared with MBF under stress conditions. In consequence the myocardial perfusion reserve may be overestimated. The amount of systematic error depends in a complex way on the shape and degree of stenoses.
DICER1
Mutations in Familial Pleuropulmonary Blastoma
Authors: Hill D. Ashley , Ivanovich Jennifer , Priest John R. , Gurnett Christina A. , Dehner Louis P. , Desruisseau David , Jarzembowski Jason A. , Wikenheiser-Brokamp Kathryn A. , Suarez Brian K. , Whelan Alison J. , Williams Gretchen , Bracamontes Dawn , Messinger Yoav , Goodfellow Paul J.
Published: June 2009

A rare form of lung cancer in children is associated with mutational disruption of an enzyme that generates small noncoding RNAs.
String Theory, Quantum Phase Transitions, and the Emergent Fermi Liquid
Authors: Čubrović Mihailo , Zaanen Jan , Schalm Koenraad
Published: June 2009

String Theory and Condensed Matter

The complex interactions involving highly correlated electron systems can give rise to “exotic behavior” in electronic systems, such as quantum criticality and superconductivity. The usual theoretical tools, however, are limited when describing these states. String theory is a highly mathematical approach initially developed to describe gravity and high-energy particle physics. Certain aspects of string theory may be relevant to describe condensed matter systems.

Čubrović
et al.

(p.
439
; published online 25 June) take one such approach, and show that the characteristic properties of a Fermi liquid can emerge from string theory. The formulation may provide an approach to describing the exotic states of matter that arise in condensed matter systems.
Duplex PCR Assay Simultaneously Detecting and Differentiating
Bartonella quintana
,
B
.
henselae
, and
Coxiella burnetii
in Surgical Heart Valve Specimens
Authors: Tang Yi-Wei
Published: June 2009

A duplex PCR (dPCR) assay was developed to simultaneously detect and differentiate
Bartonella quintana
,
Bartonella henselae
, and
Coxiella burnetii
from surgical heart valve tissue specimens with an analytic sensitivity of 10 copies/reaction. Among 17 specimens collected from patients with a clinical diagnosis of culture-negative endocarditis, 2, 4, and 2 were positive for
B
.
quintana
,
B
.
henselae
, and
C
.
burnetii
, respectively, by the dPCR assay, which matched the results obtained by universal bacterial 16S rRNA gene amplification and sequencing.
An EMA negative, desmin positive malignant mesothelioma: limitations of immunohistochemistry?
Authors: Salman W D , Eyden B , Shelton D , Howat A , Al-Dawoud A , Twaij Z
Published: June 2009

Histopathologists in the current environment of medical negligence and litigation are more likely to use immunohistochemical investigations in their day-to-day practice to support their diagnosis and avoid future litigation. The caveat is that relying on immunohistochemistry is a double-edged sword and pathologists should be familiar with its limitations. We present a case of primary malignant peritoneal mesothelioma with an unusual immunohistochemical profile—desmin positive, EMA negative—and wish to highlight the importance of cautiously interpreting immunohistochemistry profiles when they do not fit the clinical history and histological appearance.
Spontaneous regression of natural killer cell lymphoma
Authors: Isobe Y , Aritaka N , Sasaki M , Oshimi K , Sugimoto K
Published: June 2009

Spontaneous tumour regression is extremely rare in aggressive lymphoma. A case of natural killer (NK) cell lymphoma with cutaneous manifestation showed an indolent clinical course, and the relapsed nodular lesion disappeared spontaneously without any treatment. Although only small number of T cells were present in the primary skin lesion, there was massive CD8-positive cytotoxic T cell infiltration in the relapsed lesion. This is believed to be the first report of an abscopal effect on NK cell lymphoma. Infiltration of cytotoxic T cells strongly suggests immunological attack against the lymphoma cells.
Cardiac pathology of systemic lupus erythematosus
Authors: Jain D , Halushka M K
Published: June 2009

Systemic lupus erythematosus is a common chronic autoimmune disorder causing injury to many organ systems. Cardiac complications of lupus affect most parts of the heart. These include pericarditis, myocarditis, endocarditis and coronary artery disease. While many histopathological findings in lupus-related cardiac diseases are non-specific, there are a few important findings which pathologists should be aware of. This review provides pathological descriptions of these entities.
An upflow fixed-bed anaerobic–aerobic reactor for removal of organic matter and nitrogen from L-lysine plant wastewaterA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Messias de Araújo Moacir , Zaiat Marcelo
Published: June 2009

This paper reports on the design of a new reactor configuration — an upflow fixed-bed combined anaerobic–aerobic reactor — can operate as a single treatment unit for the removal of nitrogen (≈150 mg N/L) and organic matter (≈1300 mg COD/L) from Lysine plant wastewater. L-Lysine, an essential amino acid for animal nutrition, is produced by fermentation from natural raw materials of agricultural origin, thus generating wastewater with high contents of organic matter and nitrogen. The best operational condition of the reactor was obtained with a hydraulic retention time of 35 h (21 h in the anaerobic zone and 14 h in the aerobic zone) and a recycling ratio (R) of 3.5. In this condition, the COD, total Kjeldahl nitrogen (TKN), and total nitrogen (TN) removal efficiencies were 97%, 96%, and 77%, respectively, with average effluent concentrations of 10 ± 36 mg COD/L, 2 ± 1 mg NH4+-N/L, 8 ± 3 mg Org-N/L, 1 ± 1 mg NH2–-N/L, and 26 ± 23 mg NH3–-N/L.
Use of a stacked drop manhole for energy dissipation: a case study in Edmonton, Alberta
Authors: Camino G. Adriana , Zhu David Z. , Rajaratnam Nallamuthu , Shome Manas
Published: June 2009

This paper reports on a laboratory investigation into the performance of a novel stacked drop manhole design where two identical rectangular manholes are stacked one beside the other but at different heights so that there is a drop in elevation from one to the other. The focus of the study was to estimate the energy dissipation that occurs in such stacked manholes during diverse inflow conditions. Flow regimes inside the structure were identified and the effectiveness of the design was assessed under variable inflow conditions. Total energy dissipation in the stacked manhole was found to range from about 50% to 90%, and the contribution of each manhole chamber to the overall energy dissipation was assessed. A relationship between water depths in the manhole chambers and the corresponding outflow conditions was established. In addition, an analysis of the flow patterns and flow regimes highlighted the relevant parameters involved in the mechanisms of energy dissipation.
0-1 Piecewise linearization approach for interval-parameter nonlinear programming: application to environmental management under uncertaintyA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Li Y.P. , Huang G.H. , Yang Z.F. , Nie S.L.
Published: June 2009

Interval-parameter nonlinear programming (INP) is an extension of conventional nonlinear optimization methods for handling both nonlinearities and uncertainties. However, challenges exist in its solution method, leading to difficulties in obtaining a global optimum. In this study, a 0-1 piecewise approximation approach is provided for solving the INP, through integration with an interactive algorithm for interval-parameter optimization problems. Thus, the INP model can be transformed into two deterministic submodels that correspond to the lower and upper bounds of the objective-function value. By solving the two submodels, interval solutions can be obtained, which are used for generating a range of decision options. The developed method is applied to a case of long-term municipal solid waste (MSW) management planning. Not only uncertainties expressed as interval values but also nonlinearities in the objective function can be tackled. Moreover, economies of scale (EOS) effects on waste-management cost can also be reflected. The results obtained can be used for generating decision alternatives and thus help waste managers to identify desired policies for MSW management and planning. Compared with the conventional interval-parameter linear and quadratic programs, the developed INP can better reflect system-cost variations and generate more robust solutions.
Probabilistic design of a riverine early warning source water monitoring systemA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Sim Heather P. , Burn Donald H. , Tolson Bryan A.
Published: June 2009

Source water protection involves safeguarding water supplies from contamination and depletion. Despite best efforts, spills cannot always be prevented from entering a source water body. However, many spills can be prevented from entering a drinking water treatment plant if an early warning source water monitoring station is used. These stations provide downstream water utilities with advanced notification of spills so the utilities have time to implement their responses. This paper addresses the design of an early warning monitoring station for a riverine source of drinking water. Riverine water supplies face many threats related to accidental spills, which are inherently uncertain in nature. Therefore, designing a monitoring station for the detection of these events requires a probabilistic modelling approach. The design objectives include maximizing the probabilities of detection and of having a threshold amount of warning time. The methodology is applied to a water supply intake on the Grand River in southern Ontario.
Earthquake time histories compatible with the 2005National building code of Canadauniform hazard spectrum
Authors: Atkinson Gail M.
Published: June 2009

The seismic design provisions of the 2005 National building code of Canada (NBCC) (NRC 2005) describe earthquake ground motions for which structures are to be designed in terms of a uniform hazard spectrum (UHS) having a 2% chance of being exceeded in 50 years. The “target” UHS depends on location and site condition, where site condition is described by a classification scheme based on the time-averaged shear-wave velocity in the top 30 m of the deposit. For some applications, such as dynamic analysis by time history methods, it is useful to have time histories that represent the types of earthquake motions expected and match the target UHS from the NBCC over some prescribed period range. In this study, the stochastic finite-fault method is used to generate earthquake time histories that may be used to match the 2005 NBCC UHS for a range of Canadian sites. Records are provided for site classes A, C, D, and E. They are freely available at www.seismotoolbox.ca .
EFFICIENT ALGORITHM FOR OPTIMAL MATRIX ORTHOGONAL DECOMPOSITION PROBLEM IN INTENSITY-MODULATED RADIATION THERAPY
Authors: WU XIAODONG , DOU XIN , BAYOUTH JOHN E. , BUATTI JOHN M.
Published: June 2009

In this paper, we study an interesting matrix decomposition problem that seeks to decompose a "complicated" matrix into two "simpler" matrices while minimizing the sum of the horizontal complexity of the first sub-matrix and the vertical complexity of the second sub-matrix. The matrix decomposition problem is crucial for improving the "step-and-shoot" delivery efficiency in Intensity-Modulated Radiation Therapy, which aims to deliver a highly conformal radiation dose to a target tumor while sparing the surrounding normal tissues. Our algorithm is based on a non-trivial graph construction scheme, which enables us to formulate the decomposition problem as computing a minimum s-t cut in a 3-D geometric multi-pillar graph. Experiments on randomly generated intensity map matrices and on clinical data demonstrated the efficacy of our algorithm.
MECHANICS, BIOLOGY AND MEDICINE AND THE CHALLENGES OF METAMECHANICS: A PERSONAL REFLECTION
Authors: BUGLIARELLO GEORGE
Published: June 2009

A brief retrospective of the evolution of mechanics and its reciprocal impacts on medicine and biology is offered, from the limited viewpoint of an early contributor to some aspects of biomechanics. The development of the field after World War II, and particularly in the nineteen sixties and seventies, set the foundation for today's remarkable achievements. Looking ahead, the expanding complexity and challenges of the interaction of mechanics with biology and medicine, together with the loss of centrality of the mechanistic view in the physical sciences, compel a reexamination of the role, potential and limits of mechanics in this context. Future advances call for a broader metamechanics conception encompassing forces, energies, fields, information, network and systems theory, as well as for models spanning the range of scales from atom and molecule to cell, organ and organism.
FLOW DYNAMIC COMPARISON BETWEEN RECESSED HINGE AND OPEN PIVOT BI-LEAFLET HEART VALVE DESIGNS
Authors: GOVINDARAJAN V. , UDAYKUMAR H. S. , CHANDRAN K. B.
Published: June 2009

The flow dynamics through the peripheral and hinge regions of a bi-leaflet mechanical heart valve are complex and result in abnormally high shear stresses particularly during the closing phase of the valve function. It has been observed that the late stages of closure are more significant in the dynamics of platelet activation; therefore, the later stages of closure are simulated by solving the two-dimensional Navier–Stokes equations using an Eulerian Levelset-based sharp interface Cartesian grid method. Using a fixed Cartesian mesh incorporating local mesh refinement for solution accuracy and efficiency, the flow-through within a recessed hinge design and an open pivot hinge design is compared. Platelets are modeled as point particles by Lagrangian particle tracking algorithm with one way coupling. A dilute particle flow is assumed and particle–particle interactions are neglected. It was observed that the hinge region of the open pivot valve indicated a lower potential for activation of platelets compared to that in valves with a recessed hinge design.
BIOMECHANICS OF WHEELCHAIR PROPULSION
Authors: LIN CHIEN-JU , LIN PO-CHOU , SU FONG-CHIN , AN KAI-NAN
Published: June 2009

With progress of modern technology, manually-propelled wheelchairs are still of importance for individuals with mobility impairments. The repeated wheelchair propulsion and strenuous daily activities cause high loads and thus injuries on the upper extremity joints. Over the past few years, a considerable number of studies have been made on biomechanical analysis of wheelchair propulsion and wheelchair-related activities. Thorough investigation of biomechanics during wheelchair propulsion enhances comprehension of mechanism of injuries and provides information to improve wheelchair design and fitting. Numerous investigations have been made to demonstrate factors which cause low effectiveness of force application and inefficiency of movements. Emphasis was also placed on developing analytical models to simulate wheelchair propulsion.
The Primate Cortical Auditory System and Neural Representation of Conspecific Vocalizations
Authors: Romanski Lizabeth M. , Averbeck Bruno B.
Published: June 2009

Over the past decade, renewed interest in the auditory system has resulted in a surge of anatomical and physiological research in the primate auditory cortex and its targets. Anatomical studies have delineated multiple areas in and around primary auditory cortex and demonstrated connectivity among these areas, as well as between these areas and the rest of the cortex, including prefrontal cortex. Physiological recordings of auditory neurons have found that species-specific vocalizations are useful in probing the selectivity and potential functions of acoustic neurons. A number of cortical regions contain neurons that are robustly responsive to vocalizations, and some auditory responsive neurons show more selectivity for vocalizations than for other complex sounds. Demonstration of selectivity for vocalizations has prompted the question of which features are encoded by higher-order auditory neurons. Results based on detailed studies of the structure of these vocalizations, as well as the tuning and information-coding properties of neurons sensitive to these vocalizations, have begun to provide answers to this question. In future studies, these and other methods may help to define the way in which cells, ensembles, and brain regions process communication sounds. Moreover, the discovery that several nonprimary auditory cortical regions may be multisensory and responsive to vocalizations with corresponding facial gestures may change the way in which we view the processing of communication information by the auditory system.
The Economics of Genetically Modified Crops
Authors: Qaim Matin
Published: June 2009

Genetically modified (GM) crops have been used commercially for more than 10 years. Available impact studies of insect-resistant and herbicide-tolerant crops show that these technologies are beneficial to farmers and consumers, producing large aggregate welfare gains as well as positive effects for the environment and human health. The advantages of future applications could even be much bigger. Given a conducive institutional framework, GM crops can contribute significantly to global food security and poverty reduction. Nonetheless, widespread public reservations have led to a complex system of regulations. Overregulation has become a real threat for the further development and use of GM crops. The costs in terms of foregone benefits may be large, especially for developing countries. Economics research has an important role to play in designing efficient regulatory mechanisms and agricultural innovation systems.
Supply and Demand of Electricity in the Developing World
Authors: Khanna Madhu , Rao Narasimha D.
Published: June 2009

This paper reviews the literature that has sought to quantify the determinants of electricity demand and supply efficiency in developing countries. We examine the causal relationship between electricity consumption and economic growth, price and income elasticities of demand, and the barriers to adoption of energy-efficient equipment. We also examine the performance outcomes of economic policies affecting the electricity sector, including institutional reforms such as privatization and regulation. We find that electricity demand is driven by GDP, prices, income, the level and characteristics of economic activity/urbanization, and seasonal factors. The magnitude of their effects differs across countries, time periods, and studies even for the same country. These demand studies suffer from a number of limitations, including data availability and price distortions that limit responsiveness of demand to price signals. The literature is inconclusive on whether reforms, particularly privatization, improved supply efficiency. Effective regulation, competitive markets, and appropriate sequencing of reforms are important factors that influence the outcomes of privatization. There is a need for more quantitative analysis of the social welfare and distributional impacts of privatization of the electricity sector in developing countries.