bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial Impacts of Stream and Wetland Restoration on Riparian Soil Properties in the North Carolina Piedmont
Authors: Unghire Joshua M. , Sutton‐Grier Ariana E. , Flanagan Neal E. , Richardson Curtis J.
Published: August 2010

Hydric soil development of riparian wetlands is primarily influenced by the hydrologic connection between the floodplains and the stream channel. Often, the goal of riparian restoration is to revitalize this connectivity through a restructuring of the stream channel and the floodplain; however, the effects of this restructuring on the physical and spatial characteristics of soil properties are rarely considered. The objective of this study was to quantify the impacts of restoration efforts on the spatial characteristics of soil properties by means of a pre‐ and post‐restoration comparison. We determined that the spatial patterns of soil organic matter (SOM) and exchangeable phosphorus (Pex) appeared less variable in the years following restoration than in the years before restoration. Mean SOM significantly decreased after restoration, whereas mean Pex significantly increased. The spatial characteristics and mean concentrations of NO2–NO3 did not differ much between sampling dates. The loss of this spatial patterning in SOM and Pex and the decrease in SOM pools may represent negative impacts of restoration on important ecosystem characteristics. This study demonstrates that soil properties and spatial patterns can be negatively affected by restoration activities potentially hindering ecosystem development and function.
Cyber Security Risk Management: Public Policy Implications of Correlated Risk, Imperfect Ability to Prove Loss, and Observability of Self‐Protection
Authors: Öğüt Hulisi , Raghunathan Srinivasan , Menon Nirup
Published: August 2010

The correlated nature of security breach risks, the imperfect ability to prove loss from a breach to an insurer, and the inability of insurers and external agents to observe firms’ self‐protection efforts have posed significant challenges to cyber security risk management. Our analysis finds that a firm invests less than the social optimal levels in self‐protection and in insurance when risks are correlated and the ability to prove loss is imperfect. We find that the appropriate social intervention policy to induce a firm to invest at socially optimal levels depends on whether insurers can verify a firm's self‐protection levels. If self‐protection of a firm is observable to an insurer so that it can design a contract that is contingent on the self‐protection level, then self‐protection and insurance behave as complements. In this case, a social planner can induce a firm to choose the socially optimal self‐protection and insurance levels by offering a subsidy on self‐protection. We also find that providing a subsidy on insurance does not provide a similar inducement to a firm. If self‐protection of a firm is not observable to an insurer, then self‐protection and insurance behave as substitutes. In this case, a social planner should tax the insurance premium to achieve socially optimal results. The results of our analysis hold regardless of whether the insurance market is perfectly competitive or not, implying that solely reforming the currently imperfect insurance market is insufficient to achieve the efficient outcome in cyber security risk management.
Catheter Ablation of Ventricular Tachycardias Due to Forward and Reverse Propagation Across a Reentrant Circuit Inside a Nonischemic Biventricular Aneurysm
Authors: CHINUSHI MASAOMI , IZUMI DAISUKE , FURUSHIMA HIROSHI , AIZAWA YOSHIFUSA
Published: August 2010

Ablation of Bidirectional VT. A 64‐year‐old recipient of implantable cardioverter defibrillator presenting with a 4.7 × 3.3 cm nonischemic, biventricular aneurysm developed multiple electrical storms due to ventricular tachycardia (VT) with 2 distinct QRS morphologies. Endocardial electroanatomical mapping revealed the presence of a low‐voltage area corresponding to the aneurysm, where multiple delayed potentials were recorded. Activation mapping and entrainment pacing of both VT revealed the, respectively, forward and reverse propagation of the wavefront across a single reentrant circuit inside the ventricular aneurysm. Delivery of 3 applications of radiofrequency energy to a critical segment of the reentrant pathway eliminated both VT and the electrical storms. (J Cardiovasc Electrophysiol, Vol. 22, pp. 467‐467)
Hybrid Two‐Phase Magnetic Nanorod Grains
Authors: Yang Yaodong , Wang Zhiguang , Ge Wenwei , Li Jie‐Fang , Viehland Dwight
Published: August 2010

Two‐phase CoFe2O4 and BaTiO3 (BTO) nanocomposites were fabricated by a solid‐state reaction. Following a similar process in a reducing environment, we have prepared Ni–BTO, a hybrid metal–ceramic nanocomposite with a nanorod grain morphology. We discuss the growth mechanism and demonstrate that our metal–ceramic nanorods are magnetic. Ni foil can reach saturation magnetization at magnetic fields of 700 G, whereas the Ni–BTO nanorods need 3000 G. In the future, this method may offer a convenient and inexpensive way to fabricate new types of multiferroic materials.
Negative regulation of stress‐induced matrix metalloproteinase‐9 by Sirt1 in skin tissue
Authors: Lee Ji‐Seon , Park Keung‐Young , Min Hyung‐Geun , Lee Seung Jae , Kim Jin‐Ju , Choi Joon‐Seok , Kim Won‐Serk , Cha Hyuk‐Jin
Published: August 2010

Please cite this paper as: Negative regulation of stress‐induced matrix metalloproteinase‐9 by Sirtuin 1 (Sirt1) in skin tissue. Experimental Dermatology 2010; 19: 1060–1066.

Abstract:  Solar ultra‐violet (UV) radiation and the ensuing photo‐damage are adverse factors affecting human skin directly exposed to the sun. Stress responses induced by UV radiation (UVR) elicit premature skin ageing (photoageing), resulting in extensive damage to dermal connective tissue. Disruption of the normal dermal structure of skin connective tissue, primarily collagen, impairs a variety of skin functions and is considered to be the main cause of wrinkle formation. Matrix metalloproteases (MMPs) may be responsible for the degradation of collagen and other extracellular matrix proteins, which are major targets for relieving skin photoageing. Herein, we demonstrated that Sirt1, a putative anti‐ageing enzyme, reduced MMP‐9 transcriptional expression in skin. The known agonists of Sirt1, resveratrol and metformin, also significantly inhibited MMP‐9 expression and appeared to protect collagen from degradation after UVR. These studies suggest that the Sirt1 activator could be used as a novel therapeutic agent to delay skin photoageing.
Testosterone and Metabolic Syndrome: A Meta-Analysis Study
Authors: Corona Giovanni , Monami Matteo , Rastrelli Giulia , Aversa Antonio , Tishova Yuliya , Saad Farid , Lenzi Andrea , Forti Gianni , Mannucci Edoardo , Maggi Mario
Published: August 2010

Introduction

Metabolic syndrome (MetS) is often associated with male hypogonadism. Despite the well-known link, the role of testosterone replacement therapy (TRT) in MetS has not been completely clarified.

Aim

To systematically analyse the relationship between androgen levels and MetS we performed a review and meta-analyses of available prospective and cross-sectional studies. In addition, a specific meta-analysis on the metabolic effects of TRT in available randomized clinical trials (RCTs) was also performed.

Methods

An extensive Medline search was performed including the following words “testosterone,” “metabolic syndrome,” and “males”.

Main Outcome Measures

Out of 323 retrieved articles, 302 articles were excluded for different reasons. Among the 20 published studies included, 13, 3, and 4 were cross-sectional, longitudinal, and RCTs, respectively. Another unpublished RCT was retrieved on http://www.clinicaltrials.gov.

Results

MetS patients showed significantly lower T plasma levels, as compared with healthy individuals. Similar results were obtained when MetS subjects with and without erectile dysfunction were analyzed separately or when NCEP-ATPIII MetS criteria were compared with other definitions. Meta-regression analysis demonstrated that type 2 diabetes (T2DM) increased the MetS-associated T fall. In a multiple regression model, after adjusting for age and BMI, both T2DM and MetS independently predicted low testosterone (adj. r = −0.752; P < 0.001 and −0.271; P < 0.05, respectively). Analysis of longitudinal studies demonstrated that baseline testosterone was significantly lower among patients with incident MetS in comparison with controls (2.17 [−2.41;−1.94] nmol/L; P < 0.0001). Combining the results of RCTs, TRT was associated with a significant reduction of fasting plasma glucose, homeostatic model assessment index, triglycerides, and waist circumference. In addition, an increase of high-density lipoprotein cholesterol was also observed.

Conclusions

The meta-analysis of the available cross-sectional data suggests that MetS can be considered an independent association of male hypogonadism. Although only few RCTs have been reported, TRT seems to improve metabolic control, as well as central obesity.
Sexual Rehabilitation and Penile Pain Associated with Intracavernous Alprostadil After Radical Prostatectomy
Authors: Yiou René , Cunin Patrick , de la Taille Alexandre , Salomon Laurent , Binhas Michele , Lingombet Odile , Paul Murielle , Abbou Claude
Published: August 2010

Introduction

Intracavernous alprostadil injection (IAI) is widely used for sexual rehabilitation (SR) after radical prostatectomy (RP). However, the rate of spontaneous erection recovery with IAI remains unclear, and IAI causes pain that may hinder SR.

Aims

To assess SR in IAI users after RP and to evaluate the course and impact on SR of postinjection penile pain.

Methods

We prospectively studied 87 patients who underwent nerve-sparing laparoscopic RP, reported normal preoperative erectile function, and used IAI for 12 months. Patients started with 2.5 µg alprostadil and were advised to increase the dose gradually until erection hardness allowed vaginal penetration.

Main Outcome Measures

At 6 and 12 months, the International Index of Erectile Function (IIEF-15) and Erection Hardness Score (EHS) were determined with and without IAI, and injection-related penile pain was assessed using a numeric rating scale. Correlations linking penile pain, IIEF-15, and EHS scores were evaluated.

Results

The mean alprostadil dose was 8.1 µg after 6 months and 9.9 µg after 12 months. With/without IAI, mean IIEF-15 scores for erectile and orgasmic function and mean EHS score were 14.6/4.6, 4.1/2.1, and 2.5/0.4, respectively, after 6 months; and 17.2/5.4, 4.9/2.6, and 2.7/0.9 after 12 months. Pain scores were 3.2 ± 2.5/10 and 2.5 ± 2.5/10 after 6 and 12 months, respectively. Pain intensity correlated with erectile function (r = −0.23), intercourse satisfaction (r = −0.23), and overall satisfaction (r = −0.24) after 6 months but not after 12 months. Follow-up was short and only patients who used IAI for 12 months were included.

Conclusions

In patients who were willing and able to use IAI, erectile function improved after 1 year but remained below preoperative levels. The adverse impact of pain on SR was significant during the first 6 months and diminished over time. These data may help to counsel IAI users with painful erections.
The α,5‐Dicarboxy‐2‐nitrobenzyl Caging Group, a Tool for Biophysical Applications with Improved Hydrophilicity: Synthesis, Photochemical Properties and Biological Characterization
Authors: Schaper Klaus , Madani Mobarekeh Sayed Abdollah , Doro Peter , Maydt Daniela
Published: August 2010

Earlier we reported on the synthesis of α,4‐dicarboxy‐2‐nitrobenyzl caged compounds (Schaper, K. et al. [2002] Eur. J. Org. Chem., 1037–1046). These compounds have the advantage of an increased hydrophilicity compared with the well‐established α‐carboxy‐2‐nitrobenzyl caged compounds; however, the release of the active compound becomes slower due to the introduction of the additional carboxy group. Based upon theoretical calculations we predicted that the release would become faster when the additional carboxy group is moved to the 5‐position. Here we describe the synthesis and the photochemical and biological characterization of an α,5‐dicarboxy‐2‐nitrobenyzl caged compound. The high hydrophilicity of the new caging group is maintained due to the fact that the additional carboxy moiety is preserved, while the release of the active species from the new derivative is even faster than for the reference, an α‐CNB caged compound.
Draba longiciliata sp. nov. (Brassicaceae) from Ecuador
Authors: Al‐Shehbaz Ihsan A. , Sklenář Petr
Published: August 2010

Draba longiciliata Al‐Shehbaz & Sklenář, a new species from the Ecuadorian páramo, is described and illustrated. It is readily distinguished from the remaining South American species by a combination of linear leaves, glabrous on both surfaces and long‐ciliate along the entire margin and apex, and by the slender, many‐branched, slightly woody lower stems, densely covered with persistent leaf bases.
Design of iterative ROI transmission tomography reconstruction procedures and image quality analysis
Authors: Hamelin Benoit , Goussard Yves , Dussault Jean‐Pierre , Cloutier Guy , Beaudoin Gilles , Soulez Gilles
Published: August 2010

Purpose:

An iterative edge‐preserving CT reconstruction algorithm for high‐resolution imaging of small regions of the field of view is investigated. It belongs to a family of region‐of‐interest reconstruction techniques in which a low‐cost pilot reconstruction of the whole field of view is first performed and then used to deduce the contribution of the region of interest to the projection data. These projections are used for a high‐resolution reconstruction of the region of interest (ROI) using a regularized iterative algorithm, resulting in significant computational savings. This paper examines how the technique by which the pilot reconstruction of the full field of view is obtained affects the total runtime and the image quality in the region of interest.

Methods:

Previous contributions to the literature have each focused on a single approach for the pilot reconstruction. In this paper, two such approaches are compared: the filtered backprojection and a low‐resolution regularized iterative reconstruction method. ROI reconstructions are compared in terms of image quality and computational cost over simulated and physical phantom (Catphan600©) studies, in order to assess the compromises that most impact the quality of the ROI reconstruction.

Results:

With the simulated phantom, new artifacts that appear in the ROI images are caused by significant errors in the pilot reconstruction. These errors include excessive coarseness of the pilot image grid and beam‐hardening artifacts. With the Catphan600 phantom, differences in the imaging model of the scanner and that of the iterative reconstruction algorithm cause dark border artifacts in the ROI images.

Conclusions:

Inexpensive pilot reconstruction techniques (analytical algorithms, very‐coarse‐grid penalized likelihood) are practical choices in many common cases. However, they may yield background images altered by edge degradation or beam hardening, inducing projection inconsistency in the data used for ROI reconstruction. The ROI images thus have significant streak and speckle artifacts, which adversely affect the resolution‐to‐noise compromise. In these cases, edge‐preserving penalized‐likelihood methods on not‐too‐coarse image grids prove to be more robust and provide the best ROI image quality.
Automated registration of diagnostic to prediagnostic x‐ray mammograms: Evaluation and comparison to radiologists’ accuracy
Authors: Pinto Pereira Snehal M. , Hipwell John H. , McCormack Valerie A. , Tanner Christine , Moss Sue M. , Wilkinson Louise S. , Khoo Lisanne A. L. , Pagliari Catriona , Skippage Pippa L. , Kliger Carole J. , Hawkes David J. , dos Santos Silva Isabel M.
Published: August 2010

Purpose:

To compare and evaluate intensity‐based registration methods for computation of serial x‐ray mammogram correspondence.

Methods:

X‐ray mammograms were simulated from MRIs of 20 women using finite element methods for modeling breast compressions and employing a MRI/x‐ray appearance change model. The parameter configurations of three registration methods, affine, fluid, and free‐form deformation (FFD), were optimized for registering x‐ray mammograms on these simulated images. Five mammography film readers independently identified landmarks (tumor, nipple, and usually two other normal features) on pairs of diagnostic and corresponding prediagnostic digitized images from 52 breast cancer cases. Landmarks were independently reidentified by each reader. Target registration errors were calculated to compare the three registration methods using the reader landmarks as a gold standard. Data were analyzed using multilevel methods.

Results:

Between‐reader variability varied with landmark and screen , with between‐reader mean distance (mm) in point location on the diagnostic/prediagnostic images of 2.50 (95% CI 1.95, 3.15)/2.84 (2.24, 3.55) for nipples and 4.26 (3.43, 5.24)/4.76 (3.85, 5.84) for tumors. Registration accuracy was sensitive to the type of landmark and the amount of breast density. For dense breasts , the affine and fluid methods outperformed FFD. For breasts with lower density, the affine registration surpassed both fluid and FFD. Mean accuracy (mm) of the affine registration varied between 3.16 (95% CI 2.56, 3.90) for nipple points in breasts with density 20%–39% and 5.73 (4.80, 6.84) for tumor points in breasts with density .

Conclusions:

Affine registration accuracy was comparable to that between independent film readers. More advanced two‐dimensional nonrigid registration algorithms were incapable of increasing the accuracy of image alignment when compared to affine registration.
Optimization in hyperthermia treatment planning: The impact of tissue perfusion uncertainty
Authors: de Greef M. , Kok H. P. , Correia D. , Bel A. , Crezee J.
Published: August 2010

Purpose:

Hyperthermia treatment planning (HTP) potentially provides a valuable tool for monitoring and optimization of treatment. However, one of the major problems in HTP is that different sources of uncertainty degrade its reliability. Perfusion uncertainty is one of the largest uncertainties and hence there is an ongoing debate whether optimization should be limited to power‐based strategies. In this study a systematic analysis is carried out addressing this question.

Methods:

The influence of perfusion uncertainty on optimization was analyzed for five patients with cervix uteri carcinoma heated with the AMC‐8 70 MHz phased‐array waveguide system. The effect of variations (up to ±50%) in both the muscle and tumor perfusion level was investigated. For every patient, reference solutions were calculated using constrained temperature‐based optimization for 25 different and known perfusion distributions. Reference solutions were compared to those found by temperature‐based optimization using standard perfusion values and four SAR‐based optimization methods. The effect of heterogeneity was investigated by creating perfusion distributions for different levels of local variation (±25% and ±50%) and scale (1 and 2 cm). Here the performance of the temperature‐based optimization method was compared to a SAR‐based method that showed good performance in the previous analysis.

Results:

Solutions found with temperature‐based optimization using a deviating perfusion distribution during optimization were found within from the true optimum. For the SAR‐based methods, deviations up to were found. The spread found in these deviations was comparable, typically . When applying intramuscle variation to the perfusion, temperature‐based optimization proved to be the best strategy in 95% of the evaluated cases applying ±50% local variation.

Conclusions:

Temperature‐based optimization proves to be superior to SAR‐based optimization both under variation of perfusion level as well as under the application of intratissue variation. The spread in achieved temperatures is comparable. These results are valid under the assumption of constant perfusion at hyperthermic levels. Although similar results are expected from models including thermoregulation, additional analysis is required to confirm this. In view of uncertainty in tissue perfusion and other modeling uncertainties, the authors propose feedback guided temperature‐based optimization as the best candidate to improve thermal dose delivery during hyperthermia treatment.
Computerized assessment of pulmonary fissure integrity using high resolution CT
Authors: Pu Jiantao , Fuhrman Carl , Durick Janet , Leader Joseph K. , Klym Amy , Sciurba Frank C. , Gur David
Published: August 2010

Purpose:

Knowledge of pulmonary interlobar fissure integrity is of interest in a number of clinical and investigational applications. The authors developed and tested a high resolution CT based automated computerized scheme for this purpose.

Methods:

The fissure integrity assessment scheme consists of the following steps: (1) Fissure detection, (2) individual fissure identification, (3) fissure type determination, (4) “complete” interlobe surface estimation, and (5) fissure integrity estimation. For evaluation purposes, 50 anonymized chest CT examinations were ascertained and the complete and “incomplete” regions of the fissures of interest were manually marked by two experienced radiologists. After applying the scheme to the same examinations, differences among fissure percent completeness estimates based on the radiologists’ manual markings and the automated computerized scheme were computed and compared.

Results:

Average differences in estimated fissure percent completeness (integrity) between the results of the computerized scheme and that based on each of the two radiologists’ markings were, , and for the right major fissures, the right minor fissures, and the left major fissures, respectively. The differences between results based on radiologists’ markings for the same fissures were , , and , respectively. The difference among the three matched measurement sets for each fissure were statistically significant (Friedman's test, ) but paired comparisons showed that much of the observed difference was related to inter‐reader differences rather than reader‐computerized scheme differences. Computerized estimates were correlated with each of the radiologist's estimates (Spearman, ).

Conclusions:

While variability between readers‐based estimates of fissure integrity was smaller than differences between the computerized scheme and each of the readers, the result reported here are quite encouraging in that the magnitude of these differences were in the same magnitude, demonstrating the feasibility of using a computerized scheme for this purpose.
Comparison between diffusion‐weighted imaging, ‐weighted, and postcontrast ‐weighted imaging after MR‐guided, high intensity, focused ultrasound treatment of uterine leiomyomata: Preliminary results
Authors: Jacobs Michael A. , Gultekin David H. , Kim Hyun S.
Published: August 2010

Purpose

: To investigate the comparison between diffusion‐weighted imaging (DWI),‐weighted imaging, and contrast ‐weighted imaging in uterine leiomyoma following treatment by magnetic resonance imaging‐guided, high intensity focused ultrasound surgery (MRg‐HIFUS).

Methods

: Twenty one patients with clinical symptoms of uterine leiomyoma (fibroids) were treated by MRg‐HIFUS using an integrated 1.5T MRI‐HIFUS system. MRI parameters consisted of DWI, , and ‐weighted fast spoiled gradient echo before and after contrast. The post‐MRg‐HIFUS treatment volume in the fibroid was assessed by and DWI. Trace apparent diffusion coefficient maps were constructed for quantitative analysis. The regions of the treated uterine tissue were defined by a semisupervised segmentation method called the “eigenimage filter,” using both and DWI. Signal‐to‐noise ratios were determined for the pretreatment images. Segmented regions were tested by a similarity index for congruence. Descriptive, regression, and Bland–Altman statistics were calculated.

Results

: All the patients exhibited heterogeneously increased DWI signal intensity localized in the treated fibroid regions and were colocalized with the defined area. The mean pretreatment signal intensity ratios were and . The congruence between the regions was significant, with a similarity of 84% and a difference of 8% between the regions. Regression analyses of the and DWI segmented treatment volumes were found to be significantly correlated with the linear equation, . There is good agreement between the regions defined by cT1WI and DWI in most of the cases as shown from the Bland–Altman plots.

Conclusions

: Diffusion‐weighted imaging exhibited excellent agreement, congruence, and correlation with the‐defined region of treatment in uterine fibroid. Therefore, DWI could be useful as an adjunct for assessing treatment of uterine fibroids by MRg‐HIFUS.
Lung dosimetry in a linac‐MRI radiotherapy unit with a longitudinal magnetic field
Authors: Kirkby C. , Murray B. , Rathee S. , Fallone B. G.
Published: August 2010

Purpose

: There is interest in developing linac‐MR systems for MRI‐guided radiation therapy. To date, the designs for such linac‐MR devices have been restricted to a transverse geometry where the static magnetic field is oriented perpendicular to the direction of the incident photon beam. This work extends possibilities in this field by proposing and examining by Monte Carlo simulations, a probable longitudinal configuration where the magnetic field is oriented in the same direction as the photon beam.

Methods

: The EGSnrc Monte Carlo (MC) radiation transport codes with algorithms implemented to account for the magnetic field deflection of charged particles were used to compare dose distributions for linac‐MR systems in transverse and longitudinal geometries. Specifically, the responses to a 6 MV pencil photon beam incident on water and lung slabs were investigated for 1.5 and 3.0 T magnetic fields. Further a five field lung plan was simulated in the longitudinal and transverse geometries across a range of magnetic field strengths from 0.2 through 3.0 T.

Results

: In a longitudinal geometry, the magnetic field is shown to restrict the radial spread of secondary electrons to a small degree in water, but significantly in low density tissues such as lung in contrast to the lateral shift in dose distribution seen in the transverse geometry. These effects extend to the patient case, where the longitudinal configuration demonstrated dose distributions more tightly confined to the primary photon fields, which increased dose to the planning target volume (PTV), bettered dose homogeneity within a heterogeneous (in density) PTV, and reduced the tissue interface effects associated with the transverse geometry.

Conclusions

: Dosimetry issues observed in a transverse linac‐MR geometry such as changes to the depth dose distribution and tissue interface effects were significantly reduced or eliminated in a longitudinal geometry on a representative lung plan. Further, an increase in dose to the PTV, resulting from the magnetic field confining electrons to the forward direction, shows potential for a reduction in dose to the surrounding tissues.
A wavelet‐based SPECT reconstruction algorithm for nonuniformly attenuated Radon transform
Authors: Wen Junhai , Kong Lingkai
Published: August 2010

Purpose:

Single photon emission computed tomography (SPECT) is a tomography technique that can greatly show information about the metabolic activity in the body and improve the clinical diagnosis. In SPECT, because of photoelectric absorption and Compton scattering, the emitted gamma photons are attenuated inside the body before arriving at the detector. The goal of quantitative SPECT reconstruction is to obtain an accurate image of the radioactivity distribution in the interested area of a human body, so the compensation for nonuniform attenuation and the treatment of Poisson noise are necessary in the quantitative SPECT reconstruction.

Methods:

The authors know that the wavelet transform has characteristics of multiresolution and localized nature, and these characteristics can be applied for denoising and localized reconstruction. Based on the explicit inversion formula for the attenuated Radon transform, the authors present a wavelet‐based SPECT reconstruction algorithm with compensation for nonuniform attenuation.

Results:

The wavelet‐based SPECT reconstruction algorithm offers the ability for denoising in the reconstruction processing. In simulation, 128 projections were simulated evenly spaced over 360° by a circular orbit, each with 128 bins. Simulation results show that the wavelet‐based denoising is effective in SPECT reconstruction.

Conclusions:

The authors present a wavelet‐based SPECT reconstruction algorithm with compensation for nonuniform attenuation. The reconstruction results from computer simulations show that the wavelet‐based SPECT reconstruction algorithm is accurate.
Clinical application and validation of an iterative forward projection matching algorithm for permanent brachytherapy seed localization from conebeam‐CT x‐ray projections
Authors: Pokhrel Damodar , Murphy Martin J. , Todor Dorin A. , Weiss Elisabeth , Williamson Jeffrey F.
Published: August 2010

Purpose:

To experimentally validate a new algorithm for reconstructing the 3D positions of implanted brachytherapy seeds from postoperatively acquired 2D conebeam‐CT (CBCT) projection images.

Methods:

The iterative forward projection matching (IFPM) algorithm finds the 3D seed geometry that minimizes the sum of the squared intensity differences between computed projections of an initial estimate of the seed configuration and radiographic projections of the implant. In‐house machined phantoms, containing arrays of 12 and 72 seeds, respectively, are used to validate this method. Also, four postimplant patients are scanned using an ACUITY digital simulator. Three to ten x‐ray images are selected from the CBCT projection set and processed to create binary seed‐only images. To quantify IFPM accuracy, the reconstructed seed positions are forward projected and overlaid on the measured seed images to find the nearest‐neighbor distance between measured and computed seed positions for each image pair. Also, the estimated 3D seed coordinates are compared to known seed positions in the phantom and clinically obtained VariSeed planning coordinates for the patient data.

Results:

For the phantom study, seed localization error is. For all four patient cases, the mean registration error is better than 1 mm while compared against the measured seed projections. IFPM converges in 20–28 iterations, with a computation time of about 1.9–2.8 min/iteration on a 1 GHz processor.

Conclusions:

The IFPM algorithm avoids the need to match corresponding seeds in each projection as required by standard back‐projection methods. The authors’ results demonstrate accuracy in reconstructing the 3D positions of brachytherapy seeds from the measured 2D projections. This algorithm also successfully localizes overlapping clustered and highly migrated seeds in the implant.
Optimizing principal component models for representing interfraction variation in lung cancer radiotherapy
Authors: Badawi Ahmed M. , Weiss Elisabeth , Sleeman William C. , Yan Chenyu , Hugo Geoffrey D.
Published: August 2010

Purpose:

To optimize modeling of interfractional anatomical variation during active breath‐hold radiotherapy in lung cancer using principal component analysis (PCA).

Methods:

In 12 patients analyzed, weekly CT sessions consisting of three repeat intrafraction scans were acquired with active breathing control at the end of normal inspiration. The gross tumor volume (GTV) and lungs were delineated and reviewed on the first week image by physicians and propagated to all other images using deformable image registration. PCA was used to model the target and lung variability during treatment. Four PCA models were generated for each specific patient: (1) Individual models for the GTV and each lung from one image per week (week to week, W2W); (2) a W2W composite model of all structures; (3) individual models using all images (weekly plus repeat intrafraction images, allscans); and (4) composite model with all images. Models were reconstructed retrospectively (using all available images acquired) and prospectively (using only data acquired up to a time point during treatment). Dominant modes representing at least 95% of the total variability were used to reconstruct the observed anatomy. Residual reconstruction error between the model‐reconstructed and observed anatomy was calculated to compare the accuracy of the models.

Results:

An average of 3.4 and 4.9 modes was required for the allscans models, for the GTV and composite models, respectively. The W2W model required one less mode in 40% of the patients. For the retrospective composite W2W model, the average reconstruction error was, which increased to when the allscans model was used. Individual and composite models did not have significantly different errors (, paired ‐test). The average reconstruction error for the prospective models of the GTV stabilized after four measurements at and for the composite model after five measurements at .

Conclusions:

Retrospective PCA models were capable of reconstructing original GTV and lung shapes and positions within several millimeters with three to four dominant modes, on average. Prospective models achieved similar accuracy after four to five measurements.
Detectability of perfusion defect in five‐dimensional gated‐dynamic cardiac SPECT images
Authors: Niu Xiaofeng , Yang Yongyi , King Michael A. , Wernick Miles N.
Published: August 2010

Purpose:

In previous work, the authors developed and demonstrated the concept of an image reconstruction procedure aimed to unify gated and dynamic nuclear cardiac imaging, which the authors have termedfive‐dimensional (5D) SPECT. Gated imaging permits the clinician to evaluate wall motion and, through the use of stress and rest scans, allows perfusion defects to be observed. Dynamic imaging depicts kinetics in the myocardium, which can be used to evaluate perfusion, but traditional dynamic images are motionless and do not depict wall motion. In this article, the authors investigate the degree to which perfusion defects can be detected from the dynamic information conveyed by 5D images, a problem that is particularly challenging in the absence of multiple fast camera rotations.

Methods:

The authors first demonstrate the usefulness of dynamic reconstructed images for perfusion detection by using linear discriminant analyses (Fisher linear discriminant analysis and principal component analysis) and a numerical channelized Hotelling observer. The authors then derive three types of discriminant metrics for characterizing the temporal kinetic information in reconstructed dynamic images for differentiating perfusion defects from normal cardiac perfusion, which are the Fisher linear discriminant map, temporal derivative map, and kinetic parametric images.

Results:

Results are based on the NURBS‐based cardiac‐torso phantom with simulation of Tc99m‐teboroxime as the imaging agent. The derived metric maps and quantitative contrast‐to‐noise ratio results demonstrate that the reconstructed dynamic images could yield higher detectability of the perfusion defect than conventional gated reconstruction while providing wall motion information simultaneously.

Conclusions:

The proposed metrics can be used to produce new types of visualizations, showing wall motion and perfusion information, that may potentially be useful for clinical evaluation. Since 5D imaging permits wall motion and kinetics to be observed simultaneously, it may ultimately obviate the need for separate stress and rest scans.
A DEETerrent Against Feeding
Authors: Wong Wei
Published: August 2010

The insecticide DEET activates gustatory receptors to induce aversive responses in
Drosophila
.
Plants’ Modified SOS Call
Authors: Zahn Laura M.
Published: August 2010

Damage caused by a caterpillar releases compounds that are transformed by the pest’s saliva into a predator attractant.
Prevalence, Mutation Patterns, and Effects on Protease Inhibitor Susceptibility of the L76V Mutation in HIV-1 Protease
Authors: Young Thomas P. , Parkin Neil T. , Stawiski Eric , Pilot-Matias Tami , Trinh Roger , Kempf Dale J. , Norton Michael
Published: August 2010

Patterns of HIV-1 protease inhibitor (PI) resistance-associated mutations (RAMs) and effects on PI susceptibility associated with the L76V mutation were studied in a large database. Of 20,501 sequences with ≥1 PI RAM, 3.2% contained L76V; L76V was alone in 0.04%. Common partner mutations included M46I, I54V, V82A, I84V, and L90M. L76V was associated with a 2- to 6-fold decrease in susceptibility to lopinavir, darunavir, amprenavir, and indinavir and a 7- to 8-fold increase in susceptibility to atazanavir and saquinavir.
Peptidoglycan Deacetylation in
Helicobacter pylori
Contributes to Bacterial Survival by Mitigating Host Immune Responses
Authors: Wang Ge , Maier Susan E. , Lo Leja F. , Maier George , Dosi Shruti , Maier Robert J.
Published: August 2010

An oxidative stress-induced enzyme, peptidoglycan deacetylase (PgdA), in the human gastric pathogen
Helicobacter pylori
was previously identified and characterized. In this study, we constructed
H. pylori pgdA
mutants in two mouse-adapted strains, X47 and B128, to investigate the role of PgdA
in vivo
(to determine the mutants’ abilities to colonize mice and to induce an immune response).
H. pylori pgdA
mutant cells showed increased sensitivity to lysozyme compared to the sensitivities of the parent strains. We demonstrated that the expression of PgdA was significantly induced (3.5-fold) when
H. pylori
cells were in contact with macrophages, similar to the effect observed with oxidative stress as the environmental inducer. Using a mouse infection model, we first examined the mouse colonization ability of an
H. pylori pgdA
mutant in X47, a strain deficient in the major pathway (
cag
pathogenicity island [PAI] encoded) for delivery of peptidoglycan into host cells. No animal colonization difference between the wild type and the mutant was observed 3 weeks after inoculation. However, the
pgdA
mutant showed a significantly attenuated ability to colonize mouse stomachs (9-fold-lower bacterial load) at 9 weeks postinoculation. With the
cag
PAI-positive strain B128, a significant colonization difference between the wild type and the
pgdA
mutant was observed at 3 weeks postinoculation (1.32 × 10
4
versus 1.85 × 10
3
CFU/gram of stomach). To monitor the immune responses elicited by
H. pylori
in the mouse infection model, we determined the concentrations of cytokines present in mouse sera. In the mice infected with the
pgdA
mutant strain, we observed a highly significant increase in the level of MIP-2. In addition, significant increases in interleukin-10 and tumor necrosis factor alpha in the
pgdA
mutant-infected mice compared to the levels in the wild-type
H. pylori
-infected mice were also observed. These results indicated that
H. pylori
peptidoglycan deacetylation is an important mechanism for mitigating host immune detection; this likely contributes to pathogen persistence.
Automated monitoring of clusters of falls associated with severe winter weather using the BioSense system
Authors: Dey Achintya N , Hicks Peter , Benoit Stephen , Tokars Jerome I
Published: August 2010

Objectives

To identify and characterise clusters of emergency department (ED) visits for fall injuries during the 2007–2008 winter season.

Methods

Hospital ED chief complaints and diagnoses from hospitals reporting to the Centers for Disease Control and Prevention BioSense system were analysed. The authors performed descriptive analyses, used time series charts on data aggregated by metropolitan statistical areas (MSAs), and used SaTScan to find spatial–temporal clusters of visits from falls.

Results

In 2007–2008, 17 clusters of falls in 13 MSAs were found; the median number of excess ED visits for falls was 71 per day. SaTScan identified 11 clusters of falls, of which seven corresponded to MSA clusters found by time series and five included more than one state/district. Most clusters coincided with known periods of snowfall or freezing rain.

Conclusion

The results show the role that a national automated system can play in tracking widespread injuries. Such a system could be harnessed to assist with prevention strategies.
Determinants of agricultural injury: a novel application of population health theory
Authors: Pickett William , Hagel Louise M , Day Andrew G , Day Lesley , Sun Xiaoqun , Brison Robert J , Marlenga Barbara L , King Matthew , Crowe Trever , Pahwa Punam , Koehncke Niels , Dosman James
Published: August 2010

Objectives

(1) To apply novel population health theory to the modelling of injury experiences in one particular research context. (2) To enhance understanding of the conditions and practices that lead to farm injury.

Design

Prospective, cohort study conducted over 2 years (2007–09).

Setting

50 rural municipalities in the Province of Saskatchewan, Canada.

Subjects

5038 participants from 2169 Saskatchewan farms, contributing 10 092 person-years of follow-up.

Main measures

Individual exposure: self-reported times involved in farm work. Contextual factors: scaled measures describe socioeconomic, physical, and cultural farm environments. Outcome: time to first self-reported farm injury.

Results

450 farm injuries were reported for 370 individuals on 338 farms over 2 years of follow-up. Times involved in farm work were strongly and consistently related to time to first injury event, with strong monotonic increases in risk observed between none, part-time, and full-time work hour categories. Relationships between farm work hours and time to first injury were not modified by the contextual factors. Respondents reporting high versus low levels of physical farm hazards at baseline experienced increased risks for farm injury on follow-up (HR 1.54; 95% CI 1.16 to 1.47).

Conclusions

Based on study findings, firm conclusions cannot be drawn about the application of population health theory to the study of farm injury aetiology. Injury prevention efforts should continue to focus on: (1) sound occupational health and safety practices associated with long work hours; (2) physical risks and hazards on farms.
THE ENERGY GAPS OF QUADRATIC HAMILTONIANS USING METHOD OF INVARIANT EIGENOPERATOR (IEO)
Authors: CHEN JUN-HUA , FAN HONG-YI
Published: August 2010

Based on the invariant eigen-operator method3 we developed a general way to calculate the energy gaps of quadratic Boson or Fermion Hamiltonians. As an application, we calculated the energy gaps of an electron in uniform magnetic field (UMF) and a quadratic potential. We also checked the gauge invariance of electromagnetic field.
GOSSAMER SUPERFLUID AND ANTIFERROMAGNETIC STATE OF COLD ATOMS IN OPTICAL LATTICES
Authors: YU HONG-YI , SUN FA-DI , JI AN-CHUN
Published: August 2010

We propose a scheme to simulate the t–J–U model and investigate the quantum phase transitions using cold atoms confined in a two-dimensional optical lattice. By adjusting the parameters of external laser fields, we find a phase transition from antiferromagnetic phase to Gossamer superfluid. The Gossamer superfluid has a d-wave or mixed d- and s-wave symmetry, depending on the hopping parameters which can be adjusted by tuning the laser field. Experimental protocol to observe these new phenomena for future experiments has also been briefly discussed.
Computers in patient care
Authors: Cantrill Stephen V.
Published: August 2010

Information technology has the potential to radically transform health care. Why has progress been so slow?
Efficient asynchronous event handling in the real-time specification for Java
Authors: Kim Minseong , Wellings Andy
Published: August 2010

The Real-Time Specification for Java (RTSJ) is becoming mature. It has been implemented, formed the basis for research and used in serious applications. Some strengths and weaknesses are emerging. One of the areas that requires further elaboration is asynchronous event handling (AEH). The primary goal for handlers in the RTSJ is to have a lightweight concurrency mechanism. Some implementation will, however, simply map a handler to a real-time thread and this results in undermining the original motivations and introduces performance penalties. However it is generally unclear how to map handlers to real-time threads effectively. Also the support for nonblocking handlers in the RTSJ is criticized as lacking in configurability as implementations are unable to take advantage of them. This article, therefore, examines the AEH techniques used in some popular RTSJ implementations and proposes two efficient AEH models for the RTSJ. We then define formal models of the RTSJ AEH implementations using the automata formalism provided by the UPPAAL model checking tool. Using the automata models, their properties are explored and verified. In the proposed models, blocking and nonblocking handlers are serviced by different algorithms. In this way, it is possible to assign a real-time thread to a handler at the right time in the right place while maintaining the fewest possible threads overall and to give a certain level of configurability to AEH. We also have implemented the proposed models on an existing RTSJ implementation, jRate and executed a set of performance tests that measure their respective dispatch and multiple-handler completion latencies. The results from the tests and the verifications indicate that the proposed models require fewer threads on average with better performance than other approaches.
A real-time Java chip-multiprocessor
Authors: Pitter Christof , Schoeberl Martin
Published: August 2010

Chip-multiprocessors are an emerging trend for embedded systems. In this article, we introduce a real-time Java multiprocessor called JopCMP. It is a symmetric shared-memory multiprocessor, and consists of up to eight Java Optimized Processor (JOP) cores, an arbitration control device, and a shared memory. All components are interconnected via a system on chip bus. The arbiter synchronizes the access of multiple CPUs to the shared main memory. In this article, three different arbitration policies are presented, evaluated, and compared with respect to their real-time and average-case performance: a fixed priority, a fair-based, and a time-sliced arbiter.

Tasks running on different CPUs of a chip-multiprocessor (CMP) influence each others' execution times when accessing a shared memory. Therefore, the system needs an arbiter that is able to limit the worst-case execution time of a task running on a CPU, even though tasks executing simultaneously on other CPUs access the main memory. Our research shows that timing analysis is in fact possible for homogeneous multiprocessor systems with a shared memory. The timing analysis of tasks, executing on the CMP using time-sliced memory arbitration, leads to viable worst-case execution time bounds.

The time-sliced arbiter divides the memory access time into equal time slots, one time slot for each CPU. This memory arbitration scheme allows for a calculation of upper bounds of Java application worst-case execution times, depending on the number of CPUs, the time slot size, and the memory access time. Examples of worst-case execution time calculation are presented, and the analyzed results of a real-world application task are compared to measured execution time results. Finally, we evaluate the tradeoffs when using a time-predictable solution compared to using average-case optimized chip-multiprocessors, applying three different benchmarks. These experiments are carried out by executing the programs on the CMP prototype.