bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Impeller Blade Trimming on the Performance of a 5.5:1 Pressure Ratio Centrifugal Compressor
Authors: Swain Daniel , Engeda Abraham 
Published: October 2013

Centrifugal compressor blade trimming can be used for the purpose of changing the performance characteristics of an impeller or allowing a single impeller design to be used for a range of operating conditions. There are a number of methods of impeller blade trimming that may be employed to change the impeller flowrate, the pressure ratio, or both; however, the limitations of blade trimming and the effect on the flow field are not well understood.
In this study, CFD is used to model the effects of three different methods of blade trimming on a single centrifugal compressor design. Impeller performance characteristics and analysis of the flow field are presented for a series of trims for each of the three trimming methods.
Each method of trimming was found to be limited at some point by choke. Shifting the original shroud profile both axially and radially in proportion to the desired flow coefficient allowed the pressure ratio and efficiency of the original impeller to be maintained while changing the flow coefficient. Trimming the blades along the meridional length in proportion to the desired new flow coefficient without regard to the original shroud profile produced similar results, but allowed the impeller to be trimmed further than was practical using the radial-axial shroud offset method. Trimming the blades axially so that the original shroud profile is maintained produced a change in pressure ratio while maintaining the original impeller flow coefficient.
Effect of Erodent Particle Initial Velocity on the Erosion of Propeller Blades for Turboprop Engines
Authors: Farghaly Mohamed B. , El-Sayed Ahmed F. , Salem Galal B. 
Published: October 2013

Propeller driven-engines operate efficiently at low speeds, and ground maneuvers, but its performance is affected by operating in unsuitable environment. Actually, it is susceptible to encounter many physical problems such as erosion, corrosion, foreign object damage, and icing. These problems not only cause changes in air path boundaries but also yield changes in the aerodynamic performance of the engine components due to the change of the propeller profile shape and increase in the overall surface roughness.
This work aims to study the effect of the particle initial velocity on the propeller erosion phenomena and the subsequent deterioration for the blades profile. Particle trajectory, erosion rate, frequency and the critical erosion area on the blade are the main issues under investigation.
The domain selected for computational study is a periodic sector through the propeller bounding and the boundary conditions are set corresponding to that exist in the propeller manuals. A three dimensional unstructured grid was generated and adopted using commercial turbomachinery grid generator GAMBIT software. The governing equations are solved using FLUENT6.3.26 a commercial CFD code, which uses a control volume approach on a grid over the computational domain. A Lagrangian-formulated particle equation of motion is added to predict particle velocity and trajectories once the air flow field is obtained.
Interplay effects between dose distribution quality and positioning accuracy in total marrow irradiation with volumetric modulated arc therapy
Authors: Mancosu Pietro , Navarria Piera , Castagna Luca , Reggiori Giacomo , Sarina Barbara , Tomatis Stefano , Alongi Filippo , Nicolini Giorgia , Fogliata Antonella , Cozzi Luca , Scorsetti Marta 
Published: October 2013

Purpose:To evaluate the dosimetric consequences of inaccurate isocenter positioning during treatment of total marrow (lymph‐node) irradiation (TMI‐TMLI) using volumetric modulated arc therapy (VMAT).Methods:Four patients treated with TMI and TMLI were randomly selected from the internal database. Plans were optimized with VMAT technique. Planning target volume (PTV) included all the body bones; for TMLI, lymph nodes and spleen were considered into the target, too. Dose prescription to PTV was 12 Gy in six fractions, two times per day for TMI, and 2 Gy in single fraction for TMLI. Ten arcs on five isocenters (two arcs for isocenter) were used to cover the upper part of PTV (i.e., from cranium to middle femurs). For each plan, three series of random shifts with values between −3 and +3 mm and three between −5 and +5 mm were applied to the five isocenters simulating involuntary patient motion during treatment. The shifts were applied separately in the three directions: left–right (L‐R), anterior–posterior (A‐P), and cranial–caudal (C‐C). The worst case scenario with simultaneous random shifts in all directions simultaneously was considered too. Doses were recalculated for the 96 shifted plans (24 for each patient).Results:For all shifts, differences <0.5% were found for mean doses to PTV, body, and organs at risk with volumes >100 cm3. Maximum doses increased up to 15% for C‐C shifted plans. PTV covered by the 95% isodose decreased of 2%–8% revealing target underdosage with the highest values in C‐C direction.Conclusions:The correct isocenter repositioning of TMI‐TMLI patients is fundamental, in particular in C‐C direction, in order to avoid over‐ and underdosages especially in the overlap regions. For this reason, a dedicated immobilization system was developed in the authorsˈ center to best immobilize the patient.
Urinary bladder segmentation in CT urography (CTU) using CLASS
Authors: Hadjiiski Lubomir , Chan Heang‐Ping , Cohan Richard H. , Caoili Elaine M. , Law Yuen , Cha Kenny , Zhou Chuan , Wei Jun 
Published: October 2013

Purpose:The authors are developing a computerized system for bladder segmentation on CTU, as a critical component for computer aided diagnosis of bladder cancer.Methods:A challenge for bladder segmentation is the presence of regions without contrast (NC) and filled with intravenous contrast (C). The authors have designed a Conjoint Level set Analysis and Segmentation System (CLASS) specifically for this application. CLASS performs a series of image processing tasks: preprocessing, initial segmentation, 3D and 2D level set segmentation, and postprocessing, designed according to the characteristics of the bladder in CTU. The NC and the C regions of the bladder were segmented separately in CLASS. The final contour is obtained in the postprocessing stage by the union of the NC and C contours. With Institutional Review Board (IRB) approval, the authors retrospectively collected 81 CTU scans, in which 40 bladders contained lesions, 26 contained diffuse wall thickening, and 15 were considered to be normal. The bladders were segmented by CLASS and the performance was assessed by rating the quality of the contours on a 10‐point scale (1 = “very poor,” 5 = “fair,” 10 = “perfect”). For 30 bladders, 3D hand‐segmented contours were obtained and the segmentation accuracy of CLASS was evaluated and compared to that of a single level set method in terms of the average minimum distance, average volume intersection ratio, average volume error and Jaccard index.Results:Of the 81 bladders, the average quality rating for CLASS was 6.5 ± 1.3. Thirty nine bladders were given quality ratings of 7 or above. Only five bladders had ratings under 5. The average minimum distance, average volume intersection ratio, average volume error, and average Jaccard index for CLASS were 3.5 ± 1.3 mm, (79.0 ± 8.2)%, (16.1 ± 16.3)%, and (75.7 ± 8.4)%, respectively, and for the single level set method were 5.2 ± 2.6 mm, (78.8 ± 16.3)%, (8.3 ± 33.1)%, (71.0 ± 15.4)%, respectively.Conclusions:The results demonstrate the potential of CLASS for segmentation of the bladder.
Development and validation of a measurement‐based source model for kilovoltage cone‐beam CT Monte Carlo dosimetry simulations
Authors: McMillan Kyle , McNitt‐Gray Michael , Ruan Dan 
Published: October 2013

Purpose:The purpose of this study is to adapt an equivalent source model originally developed for conventional CT Monte Carlo dose quantification to the radiation oncology context and validate its application for evaluating concomitant dose incurred by a kilovoltage (kV) cone‐beam CT (CBCT) system integrated into a linear accelerator.Methods:In order to properly characterize beams from the integrated kV CBCT system, the authors have adapted a previously developed equivalent source model consisting of an equivalent spectrum module that takes into account intrinsic filtration and an equivalent filter module characterizing the added bowtie filtration. An equivalent spectrum was generated for an 80, 100, and 125 kVp beam with beam energy characterized by half‐value layer measurements. An equivalent filter description was generated from bowtie profile measurements for both the full‐ and half‐bowtie. Equivalent source models for each combination of equivalent spectrum and filter were incorporated into the Monte Carlo software package MCNPX. Monte Carlo simulations were then validated against in‐phantom measurements for both the radiographic and CBCT mode of operation of the kV CBCT system. Radiographic and CBCT imaging dose was measured for a variety of protocols at various locations within a body (32 cm in diameter) and head (16 cm in diameter) CTDI phantom. The in‐phantom radiographic and CBCT dose was simulated at all measurement locations and converted to absolute dose using normalization factors calculated from air scan measurements and corresponding simulations. The simulated results were compared with the physical measurements and their discrepancies were assessed quantitatively.Results:Strong agreement was observed between in‐phantom simulations and measurements. For the radiographic protocols, simulations uniformly underestimated measurements by 0.54%–5.14% (mean difference = −3.07%, SD = 1.60%). For the CBCT protocols, simulations uniformly underestimated measurements by 1.35%–5.31% (mean difference = −3.42%, SD = 1.09%).Conclusions:This work demonstrates the feasibility of using a measurement‐based kV CBCT source model to facilitate dose calculations with Monte Carlo methods for both the radiographic and CBCT mode of operation. While this initial work validates simulations against measurements for simple geometries, future work will involve utilizing the source model to investigate kV CBCT dosimetry with more complex anthropomorphic phantoms and patient specific models.
A new concept of pencil beam dose calculation for 40–200 keV photons using analytical dose kernels
Authors: Bartzsch Stefan , Oelfke Uwe 
Published: October 2013

Purpose:The advent of widespread kV‐cone beam computer tomography in image guided radiation therapy and special therapeutic application of keV photons, e.g., in microbeam radiation therapy (MRT) require accurate and fast dose calculations for photon beams with energies between 40 and 200 keV. Multiple photon scattering originating from Compton scattering and the strong dependence of the photoelectric cross section on the atomic number of the interacting tissue render these dose calculations by far more challenging than the ones established for corresponding MeV beams. That is why so far developed analytical models of kV photon dose calculations fail to provide the required accuracy and one has to rely on time consuming Monte Carlo simulation techniques.Methods:In this paper, the authors introduce a novel analytical approach for kV photon dose calculations with an accuracy that is almost comparable to the one of Monte Carlo simulations. First, analytical point dose and pencil beam kernels are derived for homogeneous media and compared to Monte Carlo simulations performed with the Geant4 toolkit. The dose contributions are systematically separated into contributions from the relevant orders of multiple photon scattering. Moreover, approximate scaling laws for the extension of the algorithm to inhomogeneous media are derived.Results:The comparison of the analytically derived dose kernels in water showed an excellent agreement with the Monte Carlo method. Calculated values deviate less than 5% from Monte Carlo derived dose values, for doses above 1% of the maximum dose. The analytical structure of the kernels allows adaption to arbitrary materials and photon spectra in the given energy range of 40–200 keV.Conclusions:The presented analytical methods can be employed in a fast treatment planning system for MRT. In convolution based algorithms dose calculation times can be reduced to a few minutes.
Genome Sequence of
Halomonas
sp. Strain A3H3, Isolated from Arsenic-Rich Marine Sediments
Authors: Koechler Sandrine , Plewniak Frédéric , Barbe Valérie , Battaglia-Brunet Fabienne , Jost Bernard , Joulian Catherine , Philipps Muriel , Vicaire Serge , Vincent Stéphanie , Ye Tao , Bertin Philippe N. 
Published: October 2013

ABSTRACT

We report the genome sequence of
Halomonas
sp. strain A3H3, a bacterium with a high tolerance to arsenite, isolated from multicontaminated sediments of the l'Estaque harbor in Marseille, France. The genome is composed of a 5,489,893-bp chromosome and a 157,085-bp plasmid.
Draft Genome Sequence of a Meningitic Isolate of Cronobacter sakazakii Clonal Complex 4, Strain 8399
Authors: Masood Naqash , Moore Karen , Farbos Audrey , Hariri Sumyya , Block Colin , Paszkiewicz Konrad , Dickins Ben , McNally Alan , Forsythe Stephen 
Published: October 2013

ABSTRACT

The
Cronobacter sakazakii
clonal lineage defined as clonal complex 4 (CC4), composed of nine sequence types, is associated with severe cases of neonatal meningitis. To date, only closely related
C. sakazakii
sequence type 4 (ST4) strains have been sequenced.
C. sakazakii
strain 8399, isolated from a case of neonatal meningitis, was sequenced as the first non-ST4
C. sakazakii
strain.
Draft Genome Sequence of
Bacillus
sp. Strain NSP9.1, a Moderately Halophilic Bacterium Isolated from the Salt Marsh of the Great Rann of Kutch, India
Authors: Dey Rinku , Pal Kamal Krishna , Sherathia Dharmesh , Dalsania Trupti , Savsani Kinjal , Patel Ilaxi , Thomas Manesh , Ghorai Sucheta , Vanpariya Sejal , Rupapara Rupal , Rawal Priya , Sukhadiya Bhoomika , Mandaliya Mona , Saxena Anil Kumar 
Published: October 2013

ABSTRACT

We report the 4.52-Mbp draft genome sequence of
Bacillus
sp. strain NSP9.1, a moderately halophilic bacterium isolated from the salt marsh of the Great Rann of Kutch, India. Analysis of the genome of this organism will lead to a better understanding of the genes and metabolic pathways involved in imparting osmotolerance.
New Connections between Old Pathways: PDK1 Signaling Promotes Cellular Transformation through PLK1-Dependent MYC Stabilization
Authors: Cunningham John T. , Ruggero Davide 
Published: October 2013

Abstract
Summary: Limited understanding of the functional link between multiple oncogenic pathways is a major barrier in the ongoing effort of cancer biologists to design an effective therapeutic approach to treat malignancies characterized by driver oncogenic network signals. In this issue of Cancer Discovery, Tan and colleagues elucidate a novel PDK1–PLK1–MYC signaling pathway connecting two fundamental oncogenic programs, phosphoinositide 3-kinase and MYC. They define the functional role for PDK1–PLK1–MYC signaling in cancer cell survival and tumor formation and show the therapeutic benefit of inhibiting PDK1 and PLK1 pharmacologically in cancer, tackling the most undruggable tumors defined by elevated levels of the MYC oncoprotein. Cancer Discov; 3(10); 1099–1102. ©2013 AACR.
See related article by Tan et al., p. 1156
Soluble Concentrations of the Interleukin Receptor Family Member ST2 and β-Blocker Therapy in Chronic Heart Failure
Authors: Gaggin Hanna K. , Motiwala Shweta , Bhardwaj Anju , Parks Kimberly A. , Januzzi James L. 
Published: October 2013

Background—
Concentrations of soluble (s)ST2 predict prognosis in heart failure. We recently found changing doses of β-blocker (BB) may affect sST2 concentrations. It remains unclear whether sST2 concentrations identify benefit of BB therapy, however.

Methods and Results—

A total of 151 subjects with heart failure attributable to left ventricular systolic dysfunction were examined in this post hoc analysis; >96% were taking BB at enrollment. Medication regimen and sST2 values were obtained during 10 months. Cardiovascular events were examined as a function of baseline sST2 status (low ≤35 versus high >35 ng/mL) and final achieved BB dose (high ≥50 versus low <50 mg daily equivalent dose of metoprolol succinate). Patients with low sST2 titrated to high-dose BB had the lowest cardiovascular event rate at 0.53 events (
P
=0.001), and lowest cumulative hazard (
P
=0.003). Those with low sST2/low-dose BB, or high sST2/high-dose BB had intermediate outcomes (0.92 and 1.19 events). Patients with high sST2 treated with low-dose BB had the highest cardiovascular event rate (2.08 events) and the highest cumulative hazard. Compared with low sST2/high-dose BB, those with high sST2 treated with low-dose BB had an odds ratio of 6.77 (
P
<0.001) for a cardiovascular event. Patients with low sST2/low-dose BB or high sST2/high-dose BB had intermediate odds ratios for cardiovascular events (
P
=0.18 and 0.02). Similar results were found for heart failure hospitalization and cardiovascular death.

Conclusions—
Although BB therapy exerted dose-related benefits across all study participants, sST2 measurement identifies patients with chronic heart failure who may particularly benefit from higher BB doses.

Clinical Trial Registration—

URL:
http://www.clinicaltrials.gov
. Unique identifier: NCT00351390.
Age and Ethnic Disparities in Incidence of Stroke Over Time
Authors: Wang Yanzhong , Rudd Anthony G. , Wolfe Charles D.A. 
Published: October 2013

Background and Purpose—
Data on continuous monitoring of stroke risk among different age and ethnic groups are lacking. We aimed to investigate age and ethnic disparities in stroke incidence over time from an inner-city population–based stroke register.

Methods—
Trends in stroke incidence and before-stroke risk factors were investigated with the South London Stroke Register, a population-based register covering a multiethnic population of 357 308 inhabitants. Age-, ethnicity-, and sex-specific incidence rates with 95% confidence intervals were calculated, assuming a Poisson distribution and their trends over time tested by the Cochran–Armitage test.

Results—

Four thousand two hundred forty-five patients with first-ever stroke were registered between 1995 and 2010. Total stroke incidence reduced by 39.5% during the 16-year period from 247 to 149.5 per 100 000 population (
P
<0.0001). Similar declines in stroke incidence were observed in men, women, white groups, and those aged >45 years, but not in those aged 15 to 44 years (12.6–10.1;
P
=0.2034) and black groups (310.1–267.5;
P
=0.3633). The mean age at stroke decreased significantly from 71.7 to 69.6 years (
P
=0.0001). The reduction in prevalence of before-stroke risk factors was mostly seen in white patients aged >55 years, whereas an increase in diabetes mellitus was observed in younger black patients aged 15 to 54 years.

Conclusions—
Total stroke incidence decreased during the 16-year time period. However, this was not seen in younger age groups and black groups. The advances in risk factor reduction observed in white groups aged >55 years failed to be transferred to younger age groups and black groups.
CoCoTools: Open-source Software for Building Connectomes Using the CoCoMac Anatomical Database
Authors: Blumenfeld Robert S. , Bliss Daniel P. , Perez Fernando , D'Esposito Mark 
Published: October 2013

Abstract
Neuroanatomical tracer studies in the nonhuman primate macaque monkey are a valuable resource for cognitive neuroscience research. These data ground theories of cognitive function in anatomy, and with the emergence of graph theoretical analyses in neuroscience, there is high demand for these data to be consolidated into large-scale connection matrices (“macroconnectomes”). Because manual review of the anatomical literature is time consuming and error prone, computational solutions are needed to accomplish this task. Here we describe the “CoCoTools” open-source Python library, which automates collection and integration of macaque connectivity data for visualization and graph theory analysis. CoCoTools both interfaces with the CoCoMac database, which houses a vast amount of annotated tracer results from 100 years (1905–2005) of neuroanatomical research, and implements coordinate-free registration algorithms, which allow studies that use different parcellations of the brain to be translated into a single graph. We show that using CoCoTools to translate all of the data stored in CoCoMac produces graphs with properties consistent with what is known about global brain organization. Moreover, in addition to describing CoCoTools' processing pipeline, we provide worked examples, tutorials, links to on-line documentation, and detailed appendices to aid scientists interested in using CoCoTools to gather and analyze CoCoMac data.
Clinical Results and MRI Evolution of a Nano-Composite Multilayered Biomaterial for Osteochondral Regeneration at 5 Years
Authors: Kon Elizaveta , Filardo Giuseppe , Di Martino Alessandro , Busacca Maurizio , Moio Antonio , Perdisa Francesco , Marcacci Maurilio 
Published: October 2013

Background: Several cartilage lesions involve the subchondral bone, and there is a need for biphasic scaffolds to treat the entire osteochondral unit to reproduce the different biological and functional requirements and guide the growth of the 2 tissues. Purpose: To evaluate the results of a cell-free collagen-hydroxyapatite osteochondral scaffold at midterm, and to use magnetic resonance imaging (MRI) analysis to document the imaging evolution of the tissue regeneration process through 5 years of follow-up. Study Design: Case series; Level of evidence, 4. Methods: Twenty-seven patients (9 women, 18 men; mean age, 34.9 ± 10.2 years) treated for knee chondral or osteochondral lesions (size, 1.5-6 cm2) were followed for 2 and 5 years and were clinically evaluated using the International Knee Documentation Committee (IKDC) and Tegner scores. An MRI evaluation was performed at both follow-ups in 23 lesions, and the magnetic resonance observation of cartilage repair tissue (MOCART) score and specific subchondral bone parameters (bone regeneration, bone signal quality, osteophytes or upcoming bone front, sclerotic areas, and edema) were analyzed. Results: A statistically significant improvement in all clinical scores was observed from the initial evaluation to the 2- and 5-year follow-ups, and the results were stable over time. The mean IKDC subjective score improved from 40.0 ± 15.0 to 76.5 ± 14.5 (2-year follow-up) and 77.1 ± 18.0 (5-year follow-up) and the mean Tegner score from 1.6 ± 1.1 to 4.0 ± 1.8 (2-year follow-up) and 4.1 ± 1.9 (5-year follow-up). The MRI evaluation showed a significant improvement in both the MOCART score and subchondral bone status from 2 to 5 years. At 5 years, complete filling of the cartilage was shown in 78.3% of the lesions, complete integration of the graft was detected in 69.6% of cases, the repair tissue surface was intact in 60.9%, and the structure of the repair tissue was homogeneous in 60.9% of the cases. No correlation was found between MRI findings and clinical outcome. Conclusion: This osteochondral scaffold was used for the treatment of chondral and osteochondral knee defects with a single-step procedure. The study results highlighted the safety and potential of this procedure, which offered a good clinical outcome with stable results at midterm follow-up. Although the MRI findings improved over time, some abnormalities persisted, but no correlation was found between the imaging and clinical results.