bluuebunny/crossref_metadata_2025 huggingface dataset:
Classical and New Procedures of Whole Rock Dissolution for Trace Element Determination by ICP‐MS
Authors: Cotta Aloísio J. B. , Enzweiler Jacinta
Published: June 2011

Sample digestion is a critical stage in the process of chemical analysis of geological materials by ICP‐MS. We present a new HF/HNO3 procedure to dissolve silicate rock samples using a high pressure asher system. The formation of insoluble AlF3 was the major obstacle in achieving full recoveries. This was overcome by setting an appropriate digestion temperature and adding Mg to the samples before digestion. Sodium peroxide sintering was also investigated and the inclusion of a heating step to the alkaline sinter solution improved the recoveries of thirteen elements other than the lanthanides. The results of these procedures were compared with data sets generated by common acid decomposition techniques. Forty‐one trace elements were determined using an ICP‐QMS equipped with a collision cell. Under optimum conditions of gas flow and kinetic energy discrimination, polyatomic interferences were eliminated or attenuated. The measurement bias obtained for eight reference materials (BCR‐2, BHVO‐2, BIR‐1, BRP‐1, OU‐6, GSP‐2, GSR‐1 and RGM‐1) and intermediate precision (RSD) were generally better than ± 5%. The expanded measurement uncertainties estimated for two certified reference materials were mostly between 7 and 15%. New data sets for the reference materials are provided, including constituents with previously unavailable values and also for the USGS candidate reference material G‐3.
Maxillofacial fractures in Jordan; a 5 year retrospective review
Authors: Al Khawalde M.
Published: June 2011

Aim:  Maxillofacial fractures constitute a major part of trauma cases. This retrospective study was carried out to assess the causes, types, incidence and associated regional complications of maxillofacial fractures managed at three Royal Medical Services hospitals during a 5 year period and to compare them with the existing related literature.

Materials and methods:  The medical records and radiographs of 620 patients treated for maxillofacial fractures at three Jordanian Royal Medical Services hospitals over a 5 year period (from 2001 to 2006) were retrospectively reviewed. A number of parameters, including the patient's age, gender, mechanism of injury, type of facial injuries, treatment modality and associated complications were recorded and assessed.

Results:  The majority of fractures were caused by road traffic accidents (75%), followed by falls (12%), violent assaults (8%) and others (5%). There were 395 (54%) mandibular, 264 (36%) maxillary, 44 (6%) naso‐orbital and 29 (4%) zygomatic fractures. Different treatment modalities were used according to the site of fracture. Males 18 to 35 years of age sustained the most maxillofacial fractures. The ratio of males to females was 9:1. Various types of regional complications were recorded in 68 patients (10.9%)

Conclusion:  The findings of this study, compared with similar studies reported in the literature, support the view that the causes and incidence of maxillofacial fractures vary from one country to another with the road traffic accidents being the leading cause. Greater efforts toward prevention and treatment programmes are highly recommended.
Context‐dependent effects of induced resistance under co‐infection in a plant–pathogen interaction
Authors: Laine Anna‐Liisa
Published: June 2011

The ability of a parasite strain to establish and grow on its host may be drastically altered by simultaneous infection by other parasite strains, and dynamics under multiple infection have been suggested to be a major force driving pathogen evolution. Here, I studied whether hosts’ induced defenses mediate dynamics of multiple infection of the fungal pathogen,Podosphaera plantaginis, infectingPlantago lanceolata. A laboratory study of sequential infections, where interaction between pathogen strains was prevented, showed that ability to establish remained unaffected, but prior infection elevates the host’s resistance to the degree that subsequent infection development is significantly reduced. However, when inoculated plants and their healthy controls were planted back into their natural populations, hosts with prior infection became more heavily infected by the subsequent infections than the initially healthy plants. Hence, a controlled short‐term laboratory study is a poor predictor of the host’s ability to mediate multiple infection during the course of natural epidemics. These results have applied implications for priming where the plants’ defenses are elicited to provide protection against further attack, highlighting the importance of testing priming under natural conditions for relevant time scales.
Happiness, Well‐being, and Their Relation to Virtue in Descartes' Ethics*
Authors: SVENSSON FRANS
Published: June 2011

My main thesis in this article is that Descartes' ethics should be understood as involving a distinction between happiness and well‐being. The distinction I have in mind is never clearly stated or articulated by Descartes himself, but I argue that we nevertheless have good reason to embrace it as an important component in a charitable reconstruction of his ethical thought. In section I, I present Descartes' account of happiness and of how he thinks happiness can (and cannot) be acquired. Then, in section II, I introduce and develop the distinction between happiness and well‐being. I do this via a discussion of a difficult passage in one of Descartes' letters to Elisabeth, where he may seem first to grant and then immediately to reject the view that people's happiness can vary in degree depending on the possession of goods or perfections that are outside their power to control. I believe my proposed distinction can help us make good sense of this passage. In the last two sections (III and IV), I then offer some further grounds or reasons for why the proposed distinction should be ascribed to Descartes.
Propositional Functions in Extension
Authors: TRUEMAN ROBERT
Published: June 2011

In his “The Foundations of Mathematics”, Ramsey attempted to marry the Tractarian idea that all logical truths are tautologies and vice versa, and the logicism of the Principia. In order to complete his project, Ramsey was forced to introduce propositional functions in extension (PFEs): given Ramsey's definitions of 1 and 2, without PFEs even the quantifier‐free arithmetical truth that 1 ≠ 2 is not a tautology. However, a number of commentators have argued that the notion of PFEs is incoherent. This response was first given by Wittgenstein but has been best developed by Sullivan. While I agree with Wittgenstein and Sullivan's common conclusion, I believe that even the most compelling of Sullivan's arguments is importantly mistaken and that Wittgenstein's remarks are too opaque to be left as the end of the matter. In this article I uncover the fault in Sullivan's argument and present an alternative criticism of PFEs which is Wittgensteinian in spirit without being too mystifying.
Making Sense of Doubt: Strawson's Anti‐Scepticism
Authors: CALLANAN JOHN. J.
Published: June 2011

Strawson's philosophical attitude towards scepticism is frequently thought to have undergone a significant shift from the “strong” or “robust” employment of transcendental arguments in Individuals to a more “modest” understanding of the efficacy of such arguments in Skepticism and Naturalism: Some Varieties. I argue that this interpretation is based upon a misunderstanding of the function of transcendental arguments in Strawson's earlier works. Examining the continuity of Strawson's modest naturalistic approach to scepticism can offer some insight as to the continuing overestimation of the anti‐sceptical efficacy of transcendental arguments.
Action‐Individuation and Doxastic Agency
Authors: BUCKAREFF ANDREI A.
Published: June 2011

In this article, I challenge the dominant view of the importance of the debate over action‐individuation. On the dominant view, it is held that the conclusions we reach about action‐individuation make little or no difference for other debates in the philosophy of action, much less in other areas of philosophy. As a means of showing that the dominant view is mistaken, I consider the implications of accepting a given theory of action‐individuation for thinking about doxastic agency. In particular, I am interested in the implications for thinking about the variety of evaluative control we can exercise over the formation of our doxastic attitudes. I show that our assumptions about how to individuate actions matters for how we think about doxastic agency and, hence, the conclusions we reach about action‐individuation are of greater significance than some have thought.
Symptoms Predictive for Efficacy of Naftopidil in Patients with Benign Prostate Hyperplasia
Authors: FUNAHASHI Yasuhito , HATTORI Ryohei , YOSHINO Yasushi , MATSUKAWA Yoshihisa , SASSA Naoto , GOTOH Momokazu
Published: June 2011

Objectives: To evaluate the lower urinary tract symptoms predicting the efficacy of the α1‐adrenoreceptor (AR) antagonist naftopidil in patients with benign prostate hyperplasia.

Methods: The efficacy of naftopidil was examined on the basis of changes in the international prostate symptom score (IPSS). All patients received naftopidil (50 mg/day) for 12 weeks. We defined a “responder” as a patient whose total IPSS improved by five or more points and assessed the lower urinary tract symptoms predicting the efficacy of treatment by performing multivariate and probit analyses.

Results: Among 132 patients whose data could be analyzed, the efficacy rate was 50.8%. All IPSS items except the urgency score were significantly higher in the responders than the non‐responders before treatment, and all IPSS items were lower in the responders after treatment. In the responder group, significant improvements were observed in the total IPSS score, quality of life (QOL) index, maximum flow rate (Qmax), residual urine volume, and all IPSS items after treatment. In contrast, in the non‐responder group, no parameter except the QOL index improved significantly. The probit analysis demonstrated that the score for weak stream (≥3) or nocturia (≥4) in the IPSS were factors predicting an effective response to naftopidil treatment.

Conclusions: Weak stream and/or nocturia are the key symptoms that predict the efficacy of naftopidil treatment in patients with benign prostatic hyperplasia. Those with a score of ≥3 for weak stream or of ≥4 for nocturia are expected to achieve a good response in the subjective symptoms with administration of naftopidil.
Bayesian age‐period‐cohort prediction of lung cancer incidence in China
Authors: Chen Wan‐Qing , Zheng Rong‐Shou , Zeng Hong‐Mei
Published: June 2011

Background:  Lung cancer is one of the most common cancers in China. Estimation of future cancer trends is important for cancer control planning. The aim of this study was to examine the trend of lung cancer incidence from 1998 to 2007 and predict the lung cancer burden up to 2020 in China.

Materials and methods:  Lung cancer incidence data were retrieved from the national cancer registration database from 1998 to 2007. Annual population projection for the same period was obtained from the National Statistics Bureau. The Bayesian Age‐Period‐Cohort Modeling and Prediction package (Institute of Biomedical Engineering, Imperial College, London, UK) was used to describe the trend of lung cancer incidence and to predict the incidence rate and number of cases until the year 2020.

Results:  The crude incidence rates of lung cancer increased from 43.39 per 100 000 in 1998 to 51.25 per 100 000 in 2007. After age standardization, the incidence rates remained stable over the 10‐year period. The trends were mainly caused by aging, no obvious period effects and cohort effects were observed. Our projection showed that the age‐standardized lung cancer incidence rate would remain steady until 2020. The estimated number of new incident cases was predicted to increase to 693 727 in 2020.

Conclusion:  The burden of lung cancer incidence is likely to continue increasing. Effective policies such as smoking cessation and environmental protection are imperative for lung cancer control and prevention.
High prevalence of hepatitis C virus infection in Airin district, Osaka, Japan: A hospital‐based study of 1162 patients
Authors: Yamaguchi Yasunori , Enomoto Masaru , Fujii Hideki , Tamori Akihiro , Sakaguchi Hiroki , Tanigawa Tetsuya , Watanabe Kenji , Fujiwara Yasuhiro , Arakawa Tetsuo , Harihara Shigeyoshi , Monna Takeyuki , Kawada Norifumi
Published: June 2011

Aim:  The Airin district, located in Nishinari‐ku, Osaka, is known as Japan's largest slum area, and has the largest concentration of day laborers in the country. We conducted a large hospital‐based study to determine the prevalence of hepatitis C virus (HCV) infection in the district.

Methods:  The subjects were 1162 men (mean age, 57 ± 9 years) admitted to the Osaka Socio‐Medical Center Hospital between April 2005 and March 2008. Their case records were retrospectively reviewed.

Results:  Anti‐HCV antibodies were found in 218 (18.8%) patients; in contrast, only 24 (2.1%) patients had hepatitis B surface antigen. The prevalence of anti‐HCV antibodies was 59% among the 122 patients admitted for liver diseases and 14% among the 1040 patients with other diseases. Among 927 patients with normal alanine aminotransferase levels (≤40 IU/L), 128 (13.8%) had anti‐HCV antibodies. The prevalence of anti‐HCV antibodies increased with age significantly (P < 0.001). At least 33 of the 218 (15%) patients with anti‐HCV antibodies admitted to having a history of injection drug use. Interferon therapy was initiated in 26 patients (11 with genotype 1, 14 with genotype 2 and one unclassifiable), but only six completed their scheduled regimens. Hepatocellular carcinoma was diagnosed in 20 patients, but only seven had early‐stage disease in which curative treatment, such as surgical hepatectomy or percutaneous ablation, was indicated.

Conclusion:  The prevalence of HCV infection in the Airin district is extremely higher than that in the Japanese general population. Patient education and strict action against illegal drug use are indispensable to prevent the spread of HCV infection from the district.
Researchers' Perspectives on Supply Chain Risk Management
Authors: Sodhi ManMohan S. , Son Byung‐Gak , Tang Christopher S.
Published: June 2011

Supply chain risk management (SCRM) is a nascent area emerging from a growing appreciation for supply chain risk by practitioners and by researchers. However, there is diverse perception of research in supply chain risk because these researchers have approached this area from different domains. This paper presents our study of this diversity from the perspectives of operations and supply chain management scholars: First, we reviewed the researchers' output, i.e., the recent research literature. Next, we surveyed two focus groups (members of Supply Chain Thought Leaders and International SCRM groups) with open‐ended questions. Finally, we surveyed operations and supply chain management researchers during the 2009 INFORMS meeting in San Diego. Our findings characterize the diversity in terms of three “gaps”: a definition gap in how researchers define SCRM, a process gap in terms of inadequate coverage of response to risk incidents, and a methodology gap in terms of inadequate use of empirical methods. We also list ways to close these gaps as suggested by the researchers.
Space radiation processing of sulfides and silicates in primitive solar systems materials: Comparative insights from in situ TEM ion irradiation experiments
Authors: CHRISTOFFERSEN Roy , KELLER Lindsay P.
Published: June 2011

Abstract– Mineral grains that comprise dust particles in circumstellar, interstellar, and protostellar environments can potentially undergo amorphization and other solid‐state transformations from exposure to energetic ions from space plasmas. The Fe‐sulfide minerals troilite (FeS) and pyrrhotite (Fe1−xS) are important known dust components, but their potential to undergo structural changes, including amorphization, from space radiation processing in dusty space environments has not been experimentally evaluated relative to silicates. We used a transmission electron microscope (TEM) with capabilities for in situ ion irradiation to precisely follow structural changes in troilite and pyrrhotite exposed to 1.0 MeV Kr++ ions selected to optimize the probability of inducing amorphization from nuclear elastic collisional processes. No indication of amorphization was found in either mineral up to an experimentally practical ion dose of 1 × 1016 Kr++ ions cm−2, indicating that both structures can remain crystalline up to a modeled collisional damage level of at least 26 displacements‐per‐atom. This behavior matches that of some of the most radiation‐resistant nonmetallic phases known, and is two orders of magnitude higher than the levels at which Mg‐rich olivine and enstatite become amorphous under the same irradiation conditions. Although pyrrhotite retained short‐range crystalline order during irradiation, its longer range vacancy‐ordered superstructure is removed at modeled damage levels equivalent to those at which olivine and enstatite become amorphous. This suggests that space radiation conditions sufficient to amorphize olivine and enstatite in circumstellar and interstellar environments would convert coexisting pyrrhotite to its disordered structural form, thereby changing magnetic and possibly other properties that determine how pyrrhotite will behave in these environments.
Sorting nexin 19 regulates the number of dense core vesicles in pancreatic β‐cells
Authors: Harashima Shin‐ichi , Horiuchi Takahiko , Wang Yu , Notkins Abner Louis , Seino Yutaka , Inagaki Nobuya
Published: June 2011

Aims/Introduction:  Insulinoma‐associated protein 2 (IA‐2) regulates insulin secretion and the number of dense core vesicles (DCV). However, the mechanism of regulation of DCV number by IA‐2 is unknown. We examined the effect of sorting nexin 19 (SNX19), an IA‐2 interacting protein, on insulin secretion and the number of dense core vesicles (DCV).

Materials and Methods:  Stable SNX19 knockdown (SNX19KD) MIN6, a mouse pancreatic β‐cell line, and stable SNX19‐reintroduced SNX19KD MIN6 were established. Quantification of DCV, and lysosomes was carried out using electron micrographs. The half‐life of DCV was detected by pulse‐chase experiment.

Results:  Insulin secretion and content were decreased in stable SNX19KD MIN6 cells compared with those in control MIN6 cells. Electron micrographs showed that DCV number in SNX19KD cells was decreased by approximately 75% and that DCV size was decreased by approximately 40% compared with those in control cells, respectively. Furthermore, when SNX19 was reintroduced in SNX19KD cells, insulin content, insulin secretion and DCV number were increased. The half‐life of DCV was decreased in SNX19KD cells, but was increased in SNX19KD cells in which SNX19 was reintroduced. The number of lysosomes and the activity of lysosome enzyme cathepsin D were increased by approximately threefold in SNX19KD cells compared with those in control cells. In contrast, they were decreased to approximately half to one‐third in SNX19‐reintroduced SNX19KD cells.

Conclusions:  SNX19 regulates the number of DCV and insulin content by stabilizing DCV in β‐cells. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00138.x, 2012)
Association of human papillomavirus with denture wearing
Authors: Saini Rajan , Osman Nurainina Binti , Ismail Mazian , Sobri Farini Mohd , Tang Thean Hock , Santhanam Jacinta
Published: June 2011

Aim:  To determine the prevalence of human papillomavirus in the oral cavity of denture wearers.

Methods:  Swabs were collected from 72 denture wearers and 72 controls (non‐denture wearers) to obtain DNA. Amplification of the β‐globin gene was performed by polymerase chain reaction to check the integrity of extracted DNA. The presence of human papillomavirus in the DNA sample was detected by nested polymerase chain reaction.

Results:  The prevalence of human papillomavirus was found to be significantly higher in the oral cavity of denture wearers (38/72, 52.8%) than in the controls (17/72, 23.6%; odds ratio = 3.612, confidence interval = 1.771/7.385, P = <0.001). When adjusted for variables, including age, sex, ethnicity, and smoking habit, human papillomavirus was still found to be significantly associated with denture wearing, with an adjusted odds of 3.2 (P = 0.008). No association of human papillomavirus positivity was found with denture variables, including denture type, denture material type, duration of denture wearing, and denture hygiene (P > 0.05). Low‐risk human papillomavirus types were found to be more frequent in both groups.

Conclusions:  The prevalence of human papillomavirus in the oral cavity of denture wearers was found to be significantly higher compared to controls; however, it was mainly low‐risk types.
How safe is mist netting? evaluating the risk of injury and mortality to birds
Authors: Spotswood Erica N. , Goodman Kari Roesch , Carlisle Jay , Cormier Renée L. , Humple Diana L. , Rousseau Josée , Guers Susan L. , Barton Gina G.
Published: June 2011

1. The capture of birds using mist nets is a widely utilized technique for monitoring avian populations. While the method is assumed to be safe, very few studies have addressed how frequently injuries and mortalities occur and the associated risks have not been formally evaluated.

2. We quantified the rates of mortality and injury at 22 banding organizations in the United States and Canada and used capture data from five organizations to determine what kinds of incidents occur most frequently. Analyses focused on passerines and near‐passerines, but other groups were included. We evaluated whether body mass, age, sex, mist net mesh size, month and time of day or frequency of capture are related to the risk or type of incident. We also compared the recapture histories over time between birds that were injured and those that were never injured for 16 species.

3. The average rate of injury was 0·59%, while mortality was 0·23%. Birds captured frequently were less at risk to incident. Body mass was positively correlated with incident and larger birds were at greater risk to predation, leg injuries, broken legs, internal bleeding and cuts, while smaller birds were more prone to stress, tangling‐related injuries and wing strain. Rates of incident varied among species, with some at greater risk than others. We found no evidence for increased mortality over time of injured birds compared with uninjured birds.

4. We provide the first comprehensive evaluation of the risks associated with mist netting. Our results indicate that (1) injury and mortality rates below one percent can be achieved during mist netting and (2) injured birds are likely to survive in comparable numbers to uninjured birds after release. While overall risks are low, this study identified vulnerable species and traits that may increase a bird’s susceptibility to incident that should be considered in banding protocols aimed at minimizing injury and mortality. Projects using mist nets should monitor their performance and compare their results to those of other organizations.
MOTMOT: models of trait macroevolution on trees
Authors: Thomas Gavin H. , Freckleton Robert P.
Published: June 2011

1. Models of trait macroevolution on trees (MOTMOT) is a new software package that tests for variation in the tempo and mode of continuous character evolution on phylogenetic trees. MOTMOT provides tools to fit a range of models of trait evolution with emphasis on variation in the rate of evolution between clades and character states.

2. We introduce a new method, trait MEDUSA, to identify the location of major changes in the rate of evolution of continuous traits on phylogenetic trees. We demonstrate trait MEDUSA and the other main functions of MOTMOT, using body size of Anolis lizards.

3. MOTMOT is open source software written in the R language and is freely available from CRAN (http://cran.r‐project.org/web/packages/).
Developing procedural flexibility: Are novices prepared to learn from comparing procedures?
Authors: Rittle‐Johnson Bethany , Star Jon R. , Durkin Kelley
Published: June 2011

Background.  A key learning outcome in problem‐solving domains is the development of procedural flexibility, where learners know multiple procedures and use them appropriately to solve a range of problems (e.g., Verschaffel, Luwel, Torbeyns, & Van Dooren, 2009). However, students often fail to become flexible problem solvers in mathematics. To support flexibility, teaching standards in many countries recommend that students be exposed to multiple procedures early in instruction and be encouraged to compare them.

Aims.  We experimentally evaluated this recommended instructional practice for supporting procedural flexibility during a classroom lesson, relative to two alternative conditions. The alternatives reflected the common instructional practice of delayed exposure to multiple procedures, either with or without comparison of procedures.

Sample.  Grade 8 students from two public schools (N= 198) were randomly assigned to condition. Students had not received prior instruction on multi‐step equation solving, which was the topic of our lessons.

Method.  Students learned about multi‐step equation solving under one of three conditions in math class for about 3 hr. They also completed a pre‐test, post‐test, and 1‐month‐retention test on their procedural knowledge, procedural flexibility, and conceptual knowledge of equation solving.

Results.  Novices who compared procedures immediately were more flexible problem solvers than those who did not, even on a 1‐month retention test. Although condition had limited direct impact on conceptual and procedural knowledge, greater flexibility was associated with greater knowledge of both types.

Conclusions.  Comparing procedures can support flexibility in novices and early introduction to multiple procedures may be one important reason.
General knowledge monitoring as a predictor of in‐class exam performance
Authors: Hartwig Marissa K. , Was Chris A. , Isaacson Randy M. , Dunlosky John
Published: June 2011

Background. Current theories of self‐regulated learning predict a positive link between student monitoring accuracy and performance: students who more accurately monitor their knowledge of a particular set of materials are expected to more effectively regulate their subsequent study of those materials, which in turn should lead to higher test performance.

Aims. The present study further explored the link between monitoring accuracy and performance by investigating whether monitoring of one set of materials would predict performance on a different set of materials.

Sample. The participants were college students (N= 379) enrolled in an educational psychology course.

Method. Students’ monitoring accuracy was measured at the start of the semester; the monitoring task involved materials that were not related to class content (i.e., general knowledge vocabulary) and that were related to class content (i.e., terms from educational psychology). Target performance was students’ scores on the final exam.

Results. Monitoring accuracy significantly predicted student performance on the final exam, even when the monitoring task and final test were based on materials from different content domains. Also, the class‐related (vs. unrelated) materials in the monitoring task did not improve the predictive validity of monitoring accuracy, suggesting a limited role for domain specificity in the relationship between monitoring skill and performance.

Conclusions. This study establishes a critical link between general monitoring accuracy and exam performance within a classroom setting.
Rejection as a call to arms: Inter‐racial hostility and support for political action as outcomes of race‐based rejection in majority and minority groups
Authors: Barlow Fiona Kate , Sibley Chris G. , Hornsey Matthew J.
Published: June 2011

Both majority and minority group members fear race‐based rejection, and respond by disparaging the groups that they expect will reject them. It is not clear, however, how this process differs in minority and majority groups. Using large representative samples of White (N= 4,618) and Māori (N= 1,163) New Zealanders, we found that perceptions of race‐based rejection predicted outgroup negativity in both groups, but in different ways and for different reasons. For White (but not Māori) New Zealanders, increased intergroup anxiety partially mediated the relationship between cognitions of rejection and outgroup negativity. Māori who expected to be rejected on the basis of their race reported increased ethnic identification and, in part through this, increased support for political action benefiting their own group. This finding supports collective‐action models of social change in historically disadvantaged minority groups.
Block-Spectral Approach to Film-Cooling Modeling
Authors: He L.
Published: June 2011

Gas turbine performance improvement requires efficient and accurate prediction tools for film-cooling of high pressure turbine blades. Use of computational fluid dynamics in the cooling design faces a challenge due to a wide range of length scales to be resolved. The difficulty is also seriously compounded by the basic feature that each blade has a large number of cooling holes. In the present paper, a new spectral approach is proposed to address this modeling difficulty. The motivation is to resolve the aerothermal flow field and mixing process of film-cooling by the numerical solution to the first principle based governing equations while avoiding large computational resources required in directly solving a large number of cooling holes. By using a spectral representation for each corresponding mesh point, the block-to-block (hole-to-hole) variation can be accurately and efficiently modeled. The number of mesh blocks (cooling holes) to be solved is then dictated by the number of unknowns required to determine the spectrum. Consequently, the aerothermal field for a large number of cooling hole blocks can be obtained by solving a much smaller set of blocks. The modeling consideration, method formulation, validation, and demonstration results will be presented.
Control of Tip-Clearance Flow in a Low Speed Axial Compressor Rotor With Plasma Actuation
Authors: Jothiprasad Giridhar , Murray Robert C. , Essenhigh Katherine , Bennett Grover A. , Saddoughi Seyed , Wadia Aspi , Breeze-Stringfellow Andrew
Published: June 2011

This research investigates different dielectric barrier discharge (DBD) actuator configurations for affecting tip leakage flow and suppressing stall inception. Computational investigations were performed on a low speed rotor with a highly loaded tip region that was responsible for stall-onset. The actuator was mounted on the casing upstream of the rotor leading edge. Plasma injection had a significant impact on the predicted tip-gap flow and improved stall margin. The effect of changing the actuator forcing direction on stall margin was also studied. The reduction in stalling flow was closely correlated with a reduction in loading parameter that quantifies mechanisms responsible for end-wall blockage generation. The actuation reduced end-wall losses by increasing the static pressure of tip-gap flow emerging from blade suction-side. Lastly, an approximate speed scaling developed for the DBD force helped estimate force requirements for stall margin enhancement of transonic rotors.
Blade Tip Heat Transfer and Aerodynamics in a Large Scale Turbine Cascade With Moving Endwall
Authors: Palafox P. , Oldfield M. L. G. , Ireland P. T. , Jones T. V. , LaGraff J. E.
Published: June 2011

High resolution Nusselt number distributions were measured on the blade tip surface of a large, 1.0 m chord, low-speed cascade representative of a high-pressure turbine. Data were obtained at a Reynolds number of 4.0×105 based on exit velocity and blade axial chord. Tip clearance levels ranged from 0.56% to 1.68% design span or equally from 1% to 3% of the blade chord. An infrared camera, looking through the hollow blade, made detailed temperature measurements on a constant heat flux tip surface. The relative motion between the endwall and the blade tip was simulated by a moving belt. The moving belt endwall significantly shifts the region of high Nusselt number distribution and reduces the overall averaged Nusselt number on the tip surface by up to 13.3%. The addition of a suction side squealer tip significantly reduced local tip heat transfer and resulted in a 32% reduction in averaged Nusselt number. Analysis of pressure measurements on the blade airfoil surface and tip surface along with particle image velocimetry velocity flow fields in the gap gives an understanding of the heat transfer mechanism.
Monte Carlo Investigation of Particle Properties Affecting TPB Formation and Conductivity in Composite Solid Oxide Fuel Cell Electrode-Electrolyte Interfaces
Authors: Martinez Andrew , Brouwer Jacob
Published: June 2011

A previously developed microstructure model of a solid oxide fuel cell (SOFC) electrode-electrolyte interface has been applied to study the impacts of particle properties on these interfaces through the use of a Monte Carlo simulation method. Previous findings that have demonstrated the need to account for gaseous phase percolation have been confirmed through the current investigation. In particular, the effects of three-phase percolation critically affect the dependence of TPB formation and electrode conductivity on (1) conducting phase particle size distributions, (2) electronic:ionic conduction phase contrast, and (3) the amount of mixed electronic-ionic conductor (MEIC) included in the electrode. In particular, the role of differing percolation effectiveness between electronic and ionic phases has been shown to counteract and influence the role of the phase contrast. Porosity, however, has been found to not be a significant factor for active TPB formation in the range studied, but does not obviate the need for modeling the gas phase. In addition, the current work has investigated the inconsistencies in experimental literature results concerning the optimal particle size distribution. It has been found that utilizing smaller particles with a narrow size distribution is the preferable situation for electrode-electrolyte interface manufacturing. These findings stress the property-function relationships of fuel cell electrode materials.
Advances in Finite Element Simulations of Elastosonography for Breast Lesion Detection
Authors: Celi Simona , Di Puccio Francesca , Forte Paola
Published: June 2011

Among the available tools for the early diagnosis of breast cancer, the elastographic technique based on ultrasounds has many advantages such as the noninvasive measure, the absence of ionizing effects, the high tolerability by patients, and the wide diffusion of the ecographic machines. However this diagnostic procedure is strongly affected by many subjective factors and is considered not reliable enough even to reduce the number of biopsies used to identify the nature of lesions. Therefore in the literature experimental and numerical simulations on physical and virtual phantoms are presented to test and validate procedures and algorithms and to interpret elastosonographic results. In this work, first a description of the elastographic technique and a review of the principal finite element (FE) models are provided and second diagnostic indexes employed to assess the nature of a lump mass are presented. As advances in FE simulations of elastosonography, axisymmetric phantom, and anthropomorphic models are described, which, with respect to the literature, include some features of breast mechanics. In particular deterministic analyses were used to compare the various details of virtual elastograms and also to investigate diagnostic indexes with respect to the regions where strains were considered. In order to improve the reliability of the elastosonographic procedure, univariate and multivariate sensitivity analyses, based on a probabilistic FE approach, were also performed to identify the parameters that mostly influence the deformation contrast between healthy and cancerous tissues. Moreover, synthetic indicators of the strain field, such as the strain contrast coefficient, were evaluated in different regions of interest in order to identify the most suitable for lesion type assessment. The deterministic analyses show that the malignant lesion is characterized by a uniform strain inside the inclusion due to the firmly bonding condition, while in the benign inclusion (loosely bonded) a strain gradient is observed independently from the elastic modulus contrast. The multivariate analyses reveal that the strain contrast depends linearly on the relative stiffness between the lesion and the healthy tissue and not linearly on the interface friction coefficient. The anthropomorphic model shows other interesting features, such as the layer or curvature effects, which introduce difficulties in selecting a reference region for strain assessment. The results show that a simple axisymmetric model with linear elastic material properties can be suitable to simulate the elastosonographic procedure although the breast curvature and layer distinction play a significant role in the strain assessment.
Surface templates fabricated using a focused ion beam for lateral positioning of nanoscale islands on Si (001) substrates
Authors: Wang Hao , Gray Jennifer L.
Published: June 2011

The authors have explored using a gallium focused ion beam (FIB) as a method of integrating lattice mismatched materials with silicon by creating template patterns directly on Si with nanoscale resolution. This is one method for arranging materials at nanoscale dimensions that could potentially provide better properties or new functionalities to overcome limits in current device technologies. The FIB patterned templates are of interest as a means of locally controlling topography at nanoscale dimensions or as a means of locally implanting Ga, the ion source for these experiments, at specific surface sites. The authors have annealed these templates in vacuum to study the effects of ion dosage on local Ga concentration and surface topography. They have also used magnetron sputtering to deposit SiGe on the FIB patterned Si substrates after ex situ cleaning in order to understand how the template influences the resulting surface morphology that evolves. This morphology generally consists of pits and/or islands whose size and location are influenced by the patterning and growth conditions. The templates are characterized using atomic force microscopy (AFM) and transmission electron microscopy characterization. AFM of the resulting nanostructures are also shown after SiGe deposition.
Thermal simulation of laser lift-off AlGaN/GaN high electron mobility transistors mounted on AlN substrates
Authors: Kang T. S. , Lo C. F. , Liu L. , Finch R. , Ren F. , Wang X. T. , Douglas E. , Pearton S. J. , Hung S. T. , Chang C.-J.
Published: June 2011

A finite element simulation was used to estimate the temperature rise of laser lift-off AlGaN/GaN high electron mobility transistors (HEMTs) mounted on AlN substrates via silicone elastomer under various conditions of power density on the transistor and for a range of elastomer thicknesses. The thermal response was compared to HEMTs fabricated on SiC and sapphire substrates. The maximum temperature of the transistor occurred in the gate area at a power level of 15 W, and was only 25 K higher than HEMTs fabricated on SiC. The transit time required for steady-state temperature of the flip-chip bonding device is in the range of a millisecond, which is faster than that of most power switch applications.
Deep traps and thermal measurements on AlGaN/GaN on Si transistors
Authors: Lo C. F. , Ren Fan , Pearton S. J. , Polyakov A. Y. , Smirnov N. B. , Govorkov A. V. , Belogorokhov I. A. , Belogorokhov A. I. , Reznik V. Y. , Johnson J. W.
Published: June 2011

AlGaN/GaN structures grown on Si substrates by metal organic chemical vapor deposition have been processed into high power transistors with maximum input power density of 12 W/mm. The transistor showed low concentration of bulk electron traps in the GaN buffer and of interfacial traps at the AlGaN/GaN interface. A new version of contactless thermography method based on microcathodoluminescence spectra for transistors under operation was shown to produce similar results to more established techniques based on measurements of the E2(high) phonon frequency shift in the GaN buffer and of the TO phonons in the Si substrate. The results of temperature measurements are in good agreement with modeling results.
2D/3D fetal cardiac dataset segmentation using a deformable model
Authors: Dindoyal Irving , Lambrou Tryphon , Deng Jing , Todd‐Pokropek Andrew
Published: June 2011

Purpose:

To segment the fetal heart in order to facilitate the 3D assessment of the cardiac function and structure.

Methods:

Ultrasound acquisition typically results in drop‐out artifacts of the chamber walls. The authors outline a level set deformable model to automatically delineate the small fetal cardiac chambers. The level set is penalized from growing into an adjacent cardiac compartment using a novel collision detection term. The region based model allows simultaneous segmentation of all four cardiac chambers from a user defined seed point placed in each chamber.

Results:

The segmented boundaries are automatically penalized from intersecting at walls with signal dropout. Root mean square errors of the perpendicular distances between the algorithm's delineation and manual tracings are within 2 mm which is less than 10% of the length of a typical fetal heart. The ejection fractions were determined from the 3D datasets. We validate the algorithm using a physical phantom and obtain volumes that are comparable to those from physically determined means. The algorithm segments volumes with an error of within 13% as determined using a physical phantom.

Conclusions:

Our original work in fetal cardiac segmentation compares automatic and manual tracings to a physical phantom and also measures inter observer variation.
A quality assurance protocol for diffusion tensor imaging using the head phantom from American College of Radiology
Authors: Wang Zhiyue J. , Seo Youngseob , Chia Jonathan M. , Rollins Nancy K.
Published: June 2011

Purpose:

To propose a quality assurance procedure for routine clinical diffusion tensor imaging (DTI) using the widely available American College of Radiology (ACR) head phantom.

Methods:

Analysis was performed on the data acquired at 1.5 and 3.0 T on whole body clinical MRI scanners using the ACR phantom and included the following: (1) the signal‐to‐noise ratio (SNR) at the center and periphery of the phantom, (2) image distortion by EPI readout relative to spin echo imaging, (3) distortion of high‐b images relative to the b = 0 image caused by diffusion encoding, and (4) determination of fractional anisotropy (FA) and mean diffusivity (MD) measured with region‐of‐interest (ROI) and pixel‐based approaches. Reproducibility of the measurements was assessed by five repetitions of data acquisition on each scanner.

Results:

The SNR at the phantom center was approximately half of that near the periphery at both 1.5 and 3 T. The image distortion by the EPI readout was up to 7 mm at 1.5 T and 10 mm at 3 T. The typical distortion caused by eddy currents from diffusion encoding was on the order of 0.5 mm. The difference between ROI‐based and pixel‐based MD quantification was 1.4% at 1.5 T and 0.3% at 3 T. The ROI‐based MD values were in close agreement (within 2%) with the reference values. The ROI‐based FA values were approximately a factor of 10 smaller than pixel‐based values and less than 0.01. The measurement reproducibility was sufficient for quality assurance (QA) purposes.

Conclusions:

This QA approach is simple to perform and evaluates key aspects of the scanner performance for DTI data acquisition using a widely available phantom.
Modeling diffusion‐weighted MRI as a spatially variant Gaussian mixture: Application to image denoising
Authors: Gonzalez Juan Eugenio Iglesias , Thompson Paul M. , Zhao Aishan , Tu Zhuowen
Published: June 2011

Purpose:

This work describes a spatially variant mixture model constrained by a Markov random field to model high angular resolution diffusion imaging (HARDI) data. Mixture models suit HARDI well because the attenuation by diffusion is inherently a mixture. The goal is to create a general model that can be used in different applications. This study focuses on image denoising and segmentation (primarily the former).

Methods:

HARDI signal attenuation data are used to train a Gaussian mixture model in which the mean vectors and covariance matrices are assumed to be independent of spatial locations, whereas the mixture weights are allowed to vary at different lattice positions. Spatial smoothness of the data is ensured by imposing a Markov random field prior on the mixture weights. The model is trained in an unsupervised fashion using the expectation maximization algorithm. The number of mixture components is determined using the minimum message length criterion from information theory. Once the model has been trained, it can be fitted to a noisy diffusion MRI volume by maximizing the posterior probability of the underlying noiseless data in a Bayesian framework, recovering a denoised version of the image. Moreover, the fitted probability maps of the mixture components can be used as features for posterior image segmentation.

Results:

The model‐based denoising algorithm proposed here was compared on real data with three other approaches that are commonly used in the literature: Gaussian filtering, anisotropic diffusion, and Rician‐adapted nonlocal means. The comparison shows that, at low signal‐to‐noise ratio, when these methods falter, our algorithm considerably outperforms them. When tractography is performed on the model‐fitted data rather than on the noisy measurements, the quality of the output improves substantially. Finally, ventricle and caudate nucleus segmentation experiments also show the potential usefulness of the mixture probability maps for classification tasks.

Conclusions:

The presented spatially variant mixture model for diffusion MRI provides excellent denoising results at low signal‐to‐noise ratios. This makes it possible to restore data acquired with a fast (i.e., noisy) pulse sequence to acceptable noise levels. This is the case in diffusion MRI, where a large number of diffusion‐weighted volumes have to be acquired under clinical time constraints.