bluuebunny/crossref_metadata_2025 huggingface dataset:
A Theology of the Table
Authors: Furnal Joshua
Published: February 2011

This paper explores the meal scenes in Mark's gospel and examines the theme of Divine Hospitality in the Old Testament. In doing so, a connection is made between the table fellowship of Jesus and the Kingdom of God. The article concludes by reflecting upon ecclesiological practices of the Eucharist in light of the inclusivity of table fellowship. The argument is that by attending to the meal scenes in the gospel of Mark, an understanding of the Kingdom of God manifests and should shape the way the Church practices hospitality.
Reflections on the Teaching of Philosophy in Clerical Seminaries
Authors: Theron Stephen
Published: February 2011

People cannot receive information about philosophy while being themselves dispensed from philosophising, thinking. This requirement is reasonable, since “all men desire to know”. A dualist approach to philosophy and theology obscures that they are the same. Revelation is immanent within the thinking person and grace, pace Thomas, is not extrinsic. Ecumenism, the principle, underpins this. So the philosophy of theology transcends external confessionalism, as does Christian faith itself.
Happiness and Rationality
Authors: Theron Stephen
Published: February 2011

Happiness and rationality are the same. Philosophy and Religion (and Art) have the same Content. There is no absolute contingency. The world is rational. A philosophy of theology is premised to any theology of philosophy. Revelation of glory, manifestation of manifestation as such, not of anything else, fulfils religion, “interpreting spiritual things spiritually”.
Examination of denture‐cleaning methods based on the quantity of microorganisms adhering to a denture
Authors: Nishi Yasuhiro , Seto Katsura , Kamashita Yuuji , Take Chiaki , Kurono Asutsugu , Nagaoka Eiichi
Published: February 2011

doi: 10.1111/j.1741‐2358.2011.00461.x

Examination of denture‐cleaning methods based on the quantity of microorganisms adhering to a denture

Objectives:  To investigate effective denture‐cleaning methods, we examined the relationships between the quantity of microorganisms adhering to dentures and the use of a denture brush and the frequency of use of a denture cleanser.

Subjects and Methods:  Denture plaque was collected from the mucosal surface of the examined dentures, which were 142 and 80 upper and lower complete dentures, respectively, worn by 96 outpatients (mean age: 71.9 years) of a university hospital and 41 nursing home residents (mean age: 84.8 years). The collected microorganisms were counted in terms of isolated representative colonies that were cultured and identified using standard methods. The use of a denture brush, the frequency of use, and the type and soaking time of denture cleansers as denture‐cleaning methods were surveyed.

Results:  The quantity of microorganisms was significantly lower in dentures of denture brush users than in those of non‐users in the outpatients (p < 0.01, Mann–Whitney U test). The quantity of microorganisms was significantly lower in the dentures of outpatients who used a denture cleanser daily or 3–4 times a week than in those who used one once or less per month and in the dentures of nursing home residents who used one daily than in those who used one at other frequencies (p < 0.05, Kruskal–Wallis test, followed by Dunn’s Multiple Comparison test).

Conclusion:  Within the limitations of this study, it was concluded that the use of a denture brush and daily use of denture cleanser should be recommended to complete dentures wearers as denture‐cleaning methods that effectively reduce the quantity of microorganisms adhering to dentures.
Effect of water storage and heat treatment on the cytotoxicity of soft liners
Authors: Tay Lidia Yileng , Herrera Daniel Rodrigo , Quishida Cristiane Campos Costa , Carlos Iracilda Zeppone , Jorge Janaina Habib
Published: February 2011

doi: 10.1111/j.1741‐2358.2011.00463.x

Effect of water storage and heat treatment on the cytotoxicity of soft liners

Objective:  To evaluate the effect of water storage time on the cytotoxicity of soft liners.

Methods:  Sample discs of soft liners Dentusoft, Dentuflex, Trusoft, Ufi‐Gel‐P and denture base acrylic resin Lucitone‐550 were prepared and divided into four groups: GN: No treatment, G24: Stored in water at 37°C for 24 h; G48: Stored in water at 37°C for 48 h, GHW: Immersed in water at 55°C for 10 min. To analyse the cytotoxic effect, three samples of each group were placed in tubes with Dubelcco’s Modified Eagle Mediums and incubated at 37°C for 24 h. During this period, the toxic substances were leached to the culture medium. The cytotoxicity was analysed quantitatively by the incorporation of radioactivity 3H‐thymidine checking the number of viable cells (synthesis of DNA). The data were statistically analysed using two‐way anova and Tukey’s honestly significant difference tests (α = 0.05).

Results:  Treatments did not reduce the cytotoxicity effect of the soft liners (p > 0.05). It was found that Ufi‐Gel‐P had a non‐cytotoxic effect, Trusoft had a slightly cytotoxic effect, Dentuflex had a moderated cytotoxic effect, Dentusoft alternated between slightly and non‐cytotoxic effect, and Lucitone‐550 had non‐cytotoxic effect when stored in water for 48 h.

Conclusion:  The effect of water storage and the heat treatment did not reduce the cytotoxicity of the soft liners.
Shelley’s ‘Mask of Anarchy’ and the Problem of Modern Sovereignty
Authors: Kuiken Kir
Published: February 2011

Shelley’s political poem, ‘The Mask of Anarchy’, was written in 1819 after the event known as the ‘massacre at Peterloo’. It attempts to galvanize the reform movement’s resistance to what he saw as the illegitimate power of the British government. Because the poem was deemed too radical to publish in the wake of government repression after the massacre, it raises the question of how to judge the political efficacy of a text beyond the immediate historical context for which it was intended. Recent criticism has sought to locate this efficacy in the tensions between the poem’s formal poetics and the specific political proposals that it seems to advance. This article revisits the need for this approach by proposing that the political efficacy of the ‘Mask of Anarchy’ must also be measured in terms of the way that it articulates two different relations to the paradox of modern political sovereignty which, no longer based on a transcendent foundation such as divine right, must include within its institution a finite act of self‐grounding. Drawing on recent theoretical debates about the nature of modern sovereignty, I argue that Shelley’s poem demonstrates two different relationships to this act of self‐grounding: one that produces an illegitimate form of sovereignty, and a second that recognizes the contingency of its own institution. I then go on to consider how these two different conceptions of sovereignty help clarify and sharpen the specific nature of the poem’s political efficacy.
A ZZ/ZW‐type sex determination in Xenopus laevis
Authors: Yoshimoto Shin , Ito Michihiko
Published: January 2011

Genetic sex‐determining systems in vertebrates include two basic types of heterogamety, which are represented by the XX/XY and ZZ/ZW types. Both types occur among amphibian species. Little is known, however, about the molecular mechanisms underlying amphibian sex determination. Recently, a W‐linked gene, DM‐W, was isolated as a paralog of DMRT1 in the African clawed frog Xenopus laevis, which has a female heterogametic ZZ/ZW‐type sex‐determining system. The DNA‐binding domain of DM‐W shows high sequence identity with that of DMRT1, but DM‐W does not contain a domain with homology to DMRT1’s transactivation domain. Importantly, phenotypic analysis of transgenic individuals bearing a DM‐W‐expression or ‐knockdown vector strongly suggested that DM‐W acts as a female sex‐determining gene in this species. In this minireview, we briefly describe the sex‐determining systems in amphibians, discuss recent findings from the discovery of the DM‐W gene in terms of its molecular evolution and its function in sex determination and ovary formation, and introduce a new model for the ZZ/ZW‐type sex determination elicited by DM‐W and DMRT1 in X. laevis. Finally, we discuss sex‐determining systems and germ‐cell development during vertebrate evolution, especially in view of a conserved role of DMRT1 in gonadal masculinization.
Sex determination and sexual differentiation in the avian model
Authors: Chue Justin , Smith Craig A.
Published: January 2011

The sex of birds is determined by the inheritance of sex chromosomes (ZZ male and ZW female). Genes carried on one or both of these sex chromosomes control sexual differentiation during embryonic life, producing testes in males (ZZ) and ovaries in females (ZW). This minireview summarizes our current understanding of avian sex determination and gonadal development. Most recently, it has been shown that sex is cell autonomous in birds. Evidence from gynandromorphic chickens (male on one side, female on the other) points to the likelihood that sex is determined directly in each cell of the body, independently of, or in addition to, hormonal signalling. Hence, sex‐determining genes may operate not only in the gonads, to produce testes or ovaries, but also throughout cells of the body. In the chicken, as in other birds, the gonads develop into ovaries or testes during embryonic life, a process that must be triggered by sex‐determining genes. This process involves the Z‐linked DMRT1 gene. If DMRT1 gene activity is experimentally reduced, the gonads of male embryos (ZZ) are feminized, with ovarian‐type structure, downregulation of male markers and activation of female markers. DMRT1 is currently the best candidate gene thought to regulate gonadal sex differentiation. However, if sex is cell autonomous, DMRT1 cannot be the master regulator, as its expression is confined to the urogenital system. Female development in the avian model appears to be shared with mammals; both the FOXL2 and RSPO1/WNT4 pathways are implicated in ovarian differentiation.
A progenitor for the extremely luminous Type Ic supernova 2007bi
Authors: Yoshida T. , Umeda H.
Published: February 2011

SN 2007bi is an extremely luminous Type Ic supernova. This supernova is thought to be evolved from a very massive star, and two possibilities have been proposed for the explosion mechanism. One possibility is a pair-instability supernova with an MCO∼ 100 M⊙ CO core progenitor. Another possibility is a core-collapse supernova with MCO∼ 40 M⊙. We investigate the evolution of very massive stars with main-sequence mass MMS= 100–500 M⊙ and Z0= 0.004, which is in the metallicity range of the host galaxy of SN 2007bi, to constrain the progenitor of SN 2007bi. The supernova type relating to the surface He abundance is also discussed. The main-sequence mass of the progenitor exploding as a pair-instability supernova could be MMS∼ 515–575 M⊙. The minimum main-sequence mass could be 310 M⊙ when uncertainties in the mass-loss rate are considered. A star with MMS∼ 110–280 M⊙ evolves to a CO star, appropriate for the core-collapse supernova of SN 2007bi. Arguments based on the probability of pair-instability and core-collapse supernovae favour the hypothesis that SN 2007bi originated from a core-collapse supernova event.
Mendelian genetics of male infertility
Authors: Hwang Kathleen , Yatsenko Alexander N. , Jorgez Carolina J. , Mukherjee Sarmistha , Nalam Roopa Lata , Matzuk Martin M. , Lamb Dolores J.
Published: January 2011

Infertility is defined as the inability of a couple to conceive despite trying for a year, and it affects approximately 15% of the reproductive‐age population. It is considered a genetically lethal factor, as the family lineage stops at that individual with no progeny produced. A genetic defect associated with an infertile individual cannot be transmitted to the offspring, ensuring the maintenance of reproductive fitness of the species. However, with the advent of assisted reproductive techniques (ART), we are now able to overcome sterility and bypass nature's protective mechanisms that developed through evolution to prevent fertilization by defective or deficient sperm.
Mapping Black Theology Globally
Authors: Antonio Edward P.
Published: February 2011

This essay is a survey of the global presence of black theology in three regions of the world: South Africa, Britain, and the Caribbean. The essay privileges theological anthropology as a framework within which black theology has emerged as a critique of modern racist views of the human self. By showing the globality of black theology it not only aims at dispelling a common misunderstanding that black theology is a peculiarly African–American phenomenon, it also constructs its international presence as a summons to recognize the extent to which black theology itself is riven by the internal differences which always constitute it in the specific idiom of its local responses to the ubiquity of racism in modernity. It is suggested that we take the global reality of black theology as heralding the end of white history and its false (racist) narratives of a universal humanism.
A Really Big Picture of Personality
Authors: Mayer John D. , Korogodsky Maria
Published: February 2011

How do you describe personality? One way is to begin with a picture of where personality is in relation to its neighboring systems. For example, a biopsychosocial model is often used to position personality between a lower‐level brain and higher‐level social groups. A more complete model, however, would also distinguish what is inside personality from what is outside of it. An enlarged model that accomplishes that goal is presented. After personality is positioned, models that focus on the system’s inner function can be used to complete the picture. One such model, called the systems set, divides personality into such key areas as energy development and knowledge guidance. Both the positional and functional models are illustrated with examples from the life of the composer Wolfgang Amadeus Mozart. Using such models is one way to provide an organized description of a person.
Toxoplasma gondii in Switzerland: A Serosurvey Based on Meat Juice Analysis of Slaughtered Pigs, Wild Boar, Sheep and Cattle
Authors: Berger‐Schoch A. E. , Bernet D. , Doherr M. G. , Gottstein B. , Frey C. F.
Published: January 2011

Toxoplasmosis is one of the most important zoonotic diseases worldwide and is caused by the protozoan Toxoplasma gondii. Besides vertical infection during pregnancy, humans can get infected post‐natally either by peroral uptake of sporulated Toxoplasma oocysts or by ingestion of tissue cysts upon consumption of raw or undercooked meat. The aim of this study was to approximate the risk of human infection via meat consumption by estimating the seroprevalence of T. gondii in slaughtered animals in Switzerland and to compare data with prevalences assessed 10 years ago. The study included pigs, cattle, sheep and wild boar of different age groups and housing conditions whenever possible and applicable. A P‐30‐ELISA was used to detect T. gondii‐specific antibodies and to determine seroprevalences in meat juice of slaughtered animals. A total of 270 domestic pigs (120 adults, 50 finishing, 100 free‐ranging animals), 150 wild boars, 250 sheep (150 adults, 100 lambs) and 406 cattle (47 calves, 129 heifers, 100 bulls, 130 adult cows) were tested. Seropositivity increased with the age of the assessed animals. Independent of the age‐group, the overall seroprevalence was lowest in wild boars (6.7%), followed by pigs (23.3%), cattle (45.6%) and sheep (61.6%), respectively. Conventional fattening pigs and free‐ranging pigs surprisingly had comparable seroprevalences (14.0% and 13.0%, respectively). Unlike in other European countries, where generally a decrease in the number of seropositive animals had been observed, we found that the prevalence of seropositive animals, when compared with that of 10 years ago, had increased for most species/age groups. Conclusively, the results demonstrated a high seroprevalence of T. gondii in animals slaughtered for meat production and revealed that increasing age of the animals is a more important risk factor than housing conditions in Switzerland.
Methods for collaboratively identifying research priorities and emerging issues in science and policy
Authors: Sutherland William J. , Fleishman Erica , Mascia Michael B. , Pretty Jules , Rudd Murray A.
Published: February 2011

1. There is a widely recognized gap between the data generated by researchers and the information required by policy makers. In an effort to bridge the gap between conservation policy and science, we have convened in several countries multiple groups of policy makers, practitioners and researchers to identify priority information needs that can be met by new research in the social and natural sciences.

2. The exercises we have coordinated included identification of priority policy‐relevant research questions in specific geographies (UK, USA, Canada); questions relating to global conservation; questions relating to global agriculture; policy opportunities in the United Kingdom; and emerging global conservation issues or ‘horizon scanning’.

3. We outline the exercises and describe our methods, which are based on principles of inclusivity, openness and democracy. Methods to maximize inclusiveness and rigour in such exercises include solicitation of questions and priorities from an extensive community, online collation of material, repeated voting and engagement with policy networks to foster uptake and application of the results.

4. These methods are transferable to a wide range of policy or research areas within and beyond the conservation sciences.
Measuring amphibian immunocompetence: validation of the phytohemagglutinin skin‐swelling assay in the cane toad, Rhinella marina
Authors: Brown Gregory P. , Shilton Catherine M. , Shine Richard
Published: February 2011

1. Measuring the degree of skin‐swelling induced by intradermal injection of phytohemagglutinin (PHA) is simple, quick and inexpensive, does not require specialized equipment and is easily conducted under field conditions.

2. PHA is perhaps the most frequently used assay of immunocompetence in field studies of birds. However, the method has rarely been used, and never validated, for studies on ectothermic vertebrates.

3. Here, we document its use in an amphibian. In response to PHA injected into a toe web, cane toads exhibited a 35% increase in web thickness 24 h postinjection.

4. Histologically, PHA injection initiated a rapid (<12 h) infiltration of neutrophils, eosinophils and macrophages at the injection site, followed by an influx of lymphocytes by 24 h postinjection. A second exposure to PHA stimulated a faster, more intense swelling response.

5. In cane toads, PHA injection elicits a rapid innate immune response, followed by a secondary response that may reflect cell‐mediated immune activity. Both components are easily quantifiable by the degree of skin‐swelling.

6. Hence, PHA injection offers a convenient assay to quantify immune function in anurans and could usefully be incorporated into studies on the reasons for global amphibian declines.
Mechanical Expansion of Thick-Walled Microgroove Tube for High Pressure ACR System
Authors: Tang Ding , Li Dayong , Peng Yinghong , Du Zhaohui
Published: January 2011

This paper presents a study on the expansion process, which joins fins to thick-walled microgroove tubes for high pressure air conditioning and refrigeration (ACR) heat exchanger. Experiments of the tube expansion process have been carried out. An FE model with explicit algorithm is established to study the forming quality of the tube and a novel FE model with implicit algorithm is developed to investigate the local tube-fin joining status. Evaluation of the joining quality along the longitudinal axis of the tube is tried. Both FE and experimental results show that in longitudinal section, tube-fin contact is far from full contact status and internal gaps are observed. Accordingly, process parameters and expanding die geometry are examined. Results show that among the processing factors, the expanding ratio is the major factor influencing the joining status and comprehensively beneficial range of the expanding ratio is discussed.
Investigation on Intertube Falling-Film Heat Transfer and Mode Transitions of Aqueous-Alumina Nanofluids
Authors: Ruan Binglu , Jacobi Anthony M.
Published: January 2011

Horizontal-tube falling-film heat transfer characteristics of aqueous aluminum oxide nanofluids at concentrations of 0 vol %, 0.05 vol %(0.20 wt %), 0.5 vol %(1.96 wt %), 1 vol %(3.86 wt %) (with and without sodium dodecylbenzene sulfonate), and 2 vol %(7.51 wt %) are investigated and compared with predictions developed for conventional fluids. The thermophysical properties of the nanofluids, including thermal conductivity, kinematic viscosity, and surface tension, are reported, as is the mode transition behavior of the nanofluids. The experimental results for heat transfer are in good agreement with predictions for falling-film flow and no unusual Nu enhancement was observed in the present studies. Additionally, a 20% mode transitional Reynolds number increase was recorded for transitions between sheets and jets and jet-droplet mode to droplet mode. Although the findings with water-alumina nanofluids are not encouraging with respect to heat transfer, the results extend nanofluid data to a new type of flow and may help improve our understanding of nanofluid behavior. Moreover, this work provides a basis for further work on falling-film nanofluids.
Visualization of Two-Phase Flows in Nanofluid Oscillating Heat Pipes
Authors: Li Qi-Ming , Zou Jiang , Yang Zhen , Duan Yuan-Yuan , Wang Bu-Xuan
Published: February 2011

Two-phase flows in an oscillating heat pipe (OHP) charged with deionized (DI) water and a nanofluid (0.268% v/v) were experimentally investigated. The OHP was made of quartz glass tube (with an inner diameter of 3.53 mm and an outer diameter of 5.38 mm) and coated with a transparent heating film in its evaporating section. The internal two-phase flows at different heat loads were recorded by a charge-coupled device (CCD) camera. Only column flow was observed in the DI water OHP while in the nanofluid OHP the flow first was column, then slug and annular flows as the heat load was steadily increased. Heat transfer in the OHP was strongly related to the two-phase regime. The flow regime transitions effectively increased the operating allowable heat loads in the nanofluid OHP two- to threefold relative to the DI water OHP. The nanofluid OHP had a much lower thermal resistance than the DI water OHP with the most effective heat transfer in the nanofluid OHP occurring in the slug flow regime.
Maximal Bound for Output Feedback Gain in Stabilization of Fixed Points of Fractional-Order Chaotic Systems
Authors: Tavazoei Mohammad Saleh
Published: February 2011

This paper deals with the problem of stabilizing the unstable fixed points of a class of fractional-order chaotic systems via using static output feedback. At first, a static output feedback controller designed to stabilize a fixed point of a fractional-order chaotic system is considered. Then, the maximal allowable perturbation bound around the nominal value of the output feedback gain of the designed controller, such that the stability of the intended fixed point in the closed-loop system is guaranteed, is analytically determined. Also, some numerical examples are presented to confirm the validity of the analytical results of the paper.
Influence of thermally diffused aluminum atoms from sapphire substrate on the properties of ZnO epilayers grown by metal-organic chemical vapor deposition
Authors: Tang Kun , Gu Shulin , Li Shuzhen , Ye Jiandong , Zhu Shunming , Chen Hui , Liu Jiagao , Zhang Rong , Shi Yi , Zheng Youdou
Published: February 2011

In this study, the authors investigate the evolution of the structural and electrical properties of ZnO epilayers grown by the metal-organic chemical vapor deposition method on c-sapphire substrates. The inserting of a low-temperature ZnO buffer layer not only significantly improves the structural quality of the high-temperature (HT)-grown ZnO epilayer on a sapphire substrate but also results in high background electron concentration in it from the Hall-effect measurement. After subtracting the conductive contribution from a thin degenerated layer mostly formed between the buffer layer and the substrate based on the two-layer model, the deduced electron-carrier concentration is still in the order of 1018 cm−3, which is much larger than the 1016 cm−3 obtained from capacitance-voltage measurement near the top surface. This indicates that a much thicker layer with high carrier concentration should be formed in the HT-grown ZnO epilayer, which is significantly different from that observed in GaN epitaxy, where only a thin degenerated interfacial layer is suggested to form in the GaN buffer layer. Al atoms’ distribution acquired from secondary-ion mass spectrometry shows a strong dependence on the temperature of the ZnO growth process, indicating that a thermally enhanced diffusion mechanism should be responsible for the observation of the enhanced Al atom concentration in the HT-grown ZnO epilayer. As substituted Al atoms on the Zn site act as donors in ZnO, the one-to-one correspondence between Al content and the carrier concentration, as well as the analysis of temperature-dependent Hall-effect measurement, indicates that diffusion-induced gradient-distributed AlZn shallow donors should be the main origin of the high background-carrier concentration in the HT-grown ZnO epilayers.
Surface melting and recrystallization of a self-assembled octanethiol monolayer on Au(111)
Authors: Li Fangsen , Zhou Wan-cheng , Tang Lin , Guo Quanmin
Published: January 2011

The authors have studied the response of a self-assembled octanethiol monolayer on Au(111) to temperature using a variable temperature scanning tunneling microscope. By cycling the sample temperature from room temperature to a point where the monolayer melts and back to room temperature again, the authors observed the formation of a two-dimensional liquidlike phase at 345 K. Upon cooling down from the melted phase, recrystallization takes place first leading to the formation of a monolayer consisting of the (3×3)R30° phase and a mixed striped/disordered phase. Partial desorption takes place during melting of the self-assembled monolayer.
Highly textured growth of AlN films on sapphire by magnetron sputtering for high temperature surface acoustic wave applications
Authors: Aubert T. , Assouar M. B. , Legrani O. , Elmazria O. , Tiusan C. , Robert S.
Published: January 2011

Piezoelectric aluminum nitride films were deposited onto 3 in. [0001] sapphire substrates by reactive magnetron sputtering to explore the possibility of making highly (002)-textured AlN films to be used in surface acoustic wave (SAW) devices for high temperature applications. The synthesized films, typically 1 μm thick, exhibited a columnar microstructure and a high c-axis texture. The relationship between the microstructures and process conditions was examined by x-ray diffraction (XRD), transmission electron microscopy, and atomic force microscopy analyses. The authors found that highly (002)-textured AlN films with a full width at half maximum of the rocking curve of less than 0.3° can be achieved under high nitrogen concentration and moderate growth temperature, i.e., 250 °C. The phi-scan XRD reveals the high in-plane texture of deposited AlN films. The SAW devices, based on the optimized AlN films on sapphire substrate, were characterized before and after an air annealing process at 800 °C for 90 min. The frequency response, recorded after the annealing process, confirmed that the thin films were still strong in a high temperature environment and that they had retained their piezoelectric properties.
Low temperature processing of indium-tin-zinc oxide channel layers in fabricating thin-film transistors
Authors: Lee Ki Chang , Jo Kwang-Min , Sung Sang-Yun , Lee Joon-Hyung , Kim Jeong-Joo , Jeong Byoung-Seong , Pearton S. J. , Norton D. P. , Heo Young-Woo
Published: February 2011

The authors report on the fabrication of thin-film transistors (TFTs) using indium-tin-zinc oxides (ITZOs) as active channel layers. Transparent amorphous ITZO semiconductors were deposited at room temperature by rf-magnetron sputtering, followed by an annealing treatment at 100 °C. The electrical properties of the ITZO channel layers deposited at room temperature using rf-magnetron sputtering were investigated by controlling the oxygen partial pressure during deposition and introducing postannealing treatments. The devices operated in an n-type enhancement mode exhibited a clear pinch-off behavior and had an on-to-off ratio of ∼108 with a low off current of 3×10−13 A. A field-effect mobility of 17 cm2/V s and a subthreshold slope of 0.5 V/decade were extracted from the device characteristics. These results suggest that ITZO semiconductors show potential as channel materials that are applicable in flexible transparent TFTs.
Radiation doses in cone‐beam breast computed tomography: A Monte Carlo simulation study
Authors: Yi Ying , Lai Chao‐Jen , Han Tao , Zhong Yuncheng , Shen Youtao , Liu Xinming , Ge Shuaiping , You Zhicheng , Wang Tianpeng , Shaw Chris C.
Published: February 2011

Purpose:

In this article, we describe a method to estimate the spatial dose variation, average dose and mean glandular dose (MGD) for a real breast using Monte Carlo simulation based on cone beam breast computed tomography (CBBCT) images. We present and discuss the dose estimation results for 19 mastectomy breast specimens, 4 homogeneous breast models, 6 ellipsoidal phantoms, and 6 cylindrical phantoms.

Methods:

To validate the Monte Carlo method for dose estimation in CBBCT, we compared the Monte Carlo dose estimates with the thermoluminescent dosimeter measurements at various radial positions in two polycarbonate cylinders (11‐ and 15‐cm in diameter). Cone‐beam computed tomography (CBCT) images of 19 mastectomy breast specimens, obtained with a bench‐top experimental scanner, were segmented and used to construct 19 structured breast models. Monte Carlo simulation of CBBCT with these models was performed and used to estimate the point doses, average doses, and mean glandular doses for unit open air exposure at the iso‐center. Mass based glandularity values were computed and used to investigate their effects on the average doses as well as the mean glandular doses. Average doses for 4 homogeneous breast models were estimated and compared to those of the corresponding structured breast models to investigate the effect of tissue structures. Average doses for ellipsoidal and cylindrical digital phantoms of identical diameter and height were also estimated for various glandularity values and compared with those for the structured breast models.

Results:

The absorbed dose maps for structured breast models show that doses in the glandular tissue were higher than those in the nearby adipose tissue. Estimated average doses for the homogeneous breast models were almost identical to those for the structured breast models. Normalized average doses estimated for the ellipsoidal phantoms were similar to those for the structured breast models (root mean square (rms) percentage;), whereas those for the cylindrical phantoms were significantly lower (rms percentage;). Normalized MGDs were found to decrease with increasing glandularity.

Conclusions:

Our results indicate that it is sufficient to use homogeneous breast models derived from CBCT generated structured breast models to estimate the average dose. This investigation also shows that ellipsoidal digital phantoms of similar dimensions (diameter and height) and glandularity to actual breasts may be used to represent a real breast to estimate the average breast dose with Monte Carlo simulation. We have also successfully demonstrated the use of structured breast models to estimate the true MGDs and shown that the normalized MGDs decreased with the glandularity as previously reported by other researchers for CBBCT or mammography.
Large breast compressions: Observations and evaluation of simulations
Authors: Tanner Christine , White Mark , Guarino Salvatore , Hall‐Craggs Margaret A. , Douek Michael , Hawkes David J.
Published: February 2011

Purpose:

Several methods have been proposed to simulate large breast compressions such as those occurring during x‐ray mammography. However, the evaluation of these methods against real data is rare. The aim of this study is to learn more about the deformation behavior of breasts and to assess a simulation method.

Methods:

Magnetic resonance (MR) images of 11 breasts before and after applying a relatively largein vivo compression in the medial direction were acquired. Nonrigid registration was employed to study the deformation behavior. Optimal material properties for finite element modeling were determined and their prediction performance was assessed. The realism of simulated compressions was evaluated by comparing the breast shapes on simulated and real mammograms.

Results:

Following image registration, 19 breast compressions from 8 women were studied. An anisotropic deformation behavior, with a reduced elongation in the anterior‐posterior direction and an increased stretch in the inferior‐superior direction was observed. Using finite element simulations, the performance of isotropic and transverse isotropic material models to predict the displacement of internal landmarks was compared. Isotropic materials reduced the mean displacement error of the landmarks from 23.3 to 4.7 mm, on average, after optimizing material properties with respect to breast surface alignment and image similarity. Statistically significantly smaller errors were achieved with transverse isotropic materials (4.1 mm,). Homogeneous material models performed substantially worse (transverse isotropic: 5.5 mm; isotropic: 6.7 mm). Of the parameters varied, the amount of anisotropy had the greatest influence on the results. Optimal material properties varied less when grouped by patient rather than by compression magnitude (mean: 0.72 vs 1.44). Employing these optimal materials for simulating mammograms from ten MR breast images of a different cohort resulted in more realistic breast shapes than when using established material models.

Conclusions:

Breasts in the prone position exhibited an anisotropic compression behavior. Transverse isotropic materials with an increased stiffness in the anterior‐posterior direction improved the prediction of these deformations and produced more realistic mammogram simulations from MR images.
A comparison of four skull models for independent dose calculations for Gamma Knife® PERFEXION™
Authors: Wright G. , Bownes P. , Reiner B.
Published: February 2011

Purpose:

It is recommended to have a method for independently verifying planned doses in stereotactic radiosurgery. The problem is one of how to model the geometry of a skull sampled by a limited number of points and how to subsequently calculate numerous attenuation pathlengths through the modeled skull. While methods of verification have been previously published for model B and C Gamma Knife® units, the aims of the current work were to apply the principles of these previously published techniques for the verification of plans for Gamma Knife® PERFEXION™, to present a new method of verification, and to compare all methods in terms of their agreement with GammaPlan®.

Methods:

Four algorithms were implemented: the previously published spherical approximation method (SAM) and bubble helmet skull (BHS), plus a modified BHS named interpolated BHS (IBHS) and a newly developed variable radius SAM (VRSAM). Reference point doses calculated by the four algorithms were compared to those reported by GammaPlan® for 54 simple test plans and for 35 targets in 20 recent patient plans.

Results:

For test plans, the mean (standard deviation) discrepancies against GammaPlan®‐reported doses were 0.3(1.3)%, 0.3(1.3)%, −1.6(3.4)%, and −0.4(1.0)% for SAM, VRSAM, BHS, and IBHS, respectively. For patient plans both the VRSAM and IBHS showed insignificant ( and ) discrepancies against GammaPlan® of 0.38(1.86)% and −0.11(1.86)%, respectively. More significant discrepancies against GammaPlan® of 2.64(2.98)% and −4.43(3.39)% were observed for the SAM and BHS.

Conclusions:

The SAM can lead to large discrepancies against GammaPlan® when a sphere is a poor approximation of the true skull surface, and in peripheral locations can lead to nonreal solutions to the attenuation pathlength calculations. While the BHS does not suffer the same geometric assumptions of the SAM, it can underestimate dose for peripherally located shots. The IBHS exhibits better agreement with GammaPlan® than does the BHS, but requires two‐dimensional interpolation that was found to be impractical to implement in the Excel‐based software used in the current work. Combining aspects of both the previously published SAM and BHS algorithms, the newly presented VRSAM exhibits comparable results to the IBHS but without the need for interpolation and is therefore considered the preferred technique of the four implemented.
A dosimetric uncertainty analysis for photon‐emitting brachytherapy sources: Report of AAPM Task Group No. 138 and GEC‐ESTRO
Authors: DeWerd Larry A. , Ibbott Geoffrey S. , Meigooni Ali S. , Mitch Michael G. , Rivard Mark J. , Stump Kurt E. , Thomadsen Bruce R. , Venselaar Jack L. M.
Published: February 2011

This report addresses uncertainties pertaining to brachytherapy single‐source dosimetry preceding clinical use. The International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) and the National Institute of Standards and Technology (NIST) Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties in using detectors to measure or utilizing Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. Uncertainties provided are based on published observations and cited when available. The uncertainty propagation from the primary calibration standard through transfer to the clinic for air‐kerma strength is covered first. Uncertainties in each of the brachytherapy dosimetry parameters of the TG‐43 formalism are then explored, ending with transfer to the clinic and recommended approaches. Dosimetric uncertainties during treatment delivery are considered briefly but are not included in the detailed analysis. For low‐ and high‐energy brachytherapy sources of low dose rate and high dose rate, a combined dosimetric uncertainty is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and source and treatment planning system manufacturers. These recommendations include the use of the GUM and NIST reports, a requirement of constancy of manufacturer source design, dosimetry investigator guidelines, provision of the lowest uncertainty for patient treatment dosimetry, and the establishment of an action level based on dosimetric uncertainty. These recommendations reflect the guidance of the American Association of Physicists in Medicine (AAPM) and the Groupe Européen de Curiethérapie–European Society for Therapeutic Radiology and Oncology (GEC‐ESTRO) for their members and may also be used as guidance to manufacturers and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments.
Performance evaluation of real‐time motion tracking using positron emission fiducial markers
Authors: Chamberland Marc , Wassenaar Richard , Spencer Benjamin , Xu Tong
Published: February 2011

Purpose:

Tumor motion due to patient breathing is a factor that limits the accuracy of dose distribution in radiotherapy. One of the methods to improve the accuracy is by applying respiratory gating or tumor tracking. Both techniques require a precise determination of the spatial location of the tumor. We present an experimental evaluation of the performance of PeTrack, a technique that can track internal fiducial markers in real‐time for tumor tracking

Methods:

PeTrack uses position sensitive detectors to record annihilation coincidence gamma rays from fiducial positron emission markers implanted in or around the tumor. It uses an expectation‐maximization clustering algorithm to track the position of the markers. A normalized least mean square adaptive filter was used to predict the position of the markers 100 and 200 ms in the future. We evaluated the performance of the tracking and of the prediction by using a dynamic anthropomorphic thorax phantom to generate three‐dimensional (3D) motion of three fiducial markers. The algorithm was run with four different data sets. In the first run, the motion of the markers was based on a sinusoidal model of respiratory motion. Three additional runs were done with motion based on patient breathing data.

Results:

In the case of the sinusoidal model, the average 3D root mean square error for all markers was 0.44 mm. For the three runs based on patient breathing data, the precision of the 3D localization was 0.49 mm. At a latency of 100 ms, the average 3D prediction error was for the sinusoidal model and for the three patient breathing runs. At a latency of 200 ms, the average 3D prediction errors were for the sinusoidal model and for the breathing runs.

Conclusions:

We conclude that PeTrack can track multiple fiducial markers in real‐time with an accuracy and precision smaller than 2 mm. PeTrack can have a direct application in tumor tracking for radiation therapy.
A multiple points method for 4D CT image sorting
Authors: Gianoli Chiara , Riboldi Marco , Spadea Maria Francesca , Travaini Laura Lavinia , Ferrari Mahila , Mei Riccardo , Orecchia Roberto , Baroni Guido
Published: February 2011

Purpose:

Artifacts affect 4D CT images due to breathing irregularities or incorrect breathing phase identification. The purpose of this study is the reduction of artifacts in sorted 4D CT images. The assumption is that the use of multiple respiratory related signals may reduce uncertainties and increase robustness in breathing phase identification.

Methods:

Multiple respiratory related signals were provided by infrared 3D localization of a configuration of markers placed on the thoracoabdominal surface. Multidimensional K‐means clustering was used for retrospective 4D CT image sorting, which was based on multiple marker variables, in order to identify clusters representing different breathing phases. The proposed technique was tested on computational simulations, phantom experimental acquisitions, and clinical data coming from two patients. Computational simulations provided a controlled and noise‐free condition for testing the clustering technique on regular and irregular breathing signals, including baseline drift, time variant amplitude, time variant frequency, and end‐expiration plateau. Specific attention was given to cluster initialization. Phantom experiments involved two moving phantoms fitted with multiple markers. Phantoms underwent 4D CT acquisition while performing controlled rigid motion patterns and featuring end‐expiration plateau. Breathing cycle period and plateau duration were controlled by means of weights leaned upon the phantom during repeated 4D CT scans. The implemented sorting technique was applied to clinical 4D CT scans acquired on two patients and results were compared to conventional sorting methods.

Results:

For computational simulations and phantom studies, the performance of the multidimensional clustering technique was evaluated by measuring the repeatability in identifying the breathing phase among adjacent couch positions and the uniformity in sampling the breathing cycle. When breathing irregularities were present, the clustering technique consistently improved breathing phase identification with respect to conventional sorting methods based on monodimensional signals. In patient studies, a qualitative comparison was performed between corresponding breathing phases of 4D CT images obtained by conventional sorting methods and by the described clustering technique. Artifact reduction was clearly observable on both data set especially in the lower lung region.

Conclusions:

The implemented multiple point method demonstrated the ability to reduce artifacts in 4D CT imaging. Further optimization and development are needed to make the most of the availability of multiple respiratory related variables and to extend the method to 4D CT‐PET hybrid scan.
CT image artifacts from brachytherapy seed implants: A postprocessing 3D adaptive median filter
Authors: Basran Parminder S. , Robertson Andrew , Wells Derek
Published: February 2011

Purpose:

To design a postprocessing 3D adaptive median filter that minimizes streak artifacts and improves soft‐tissue contrast in postoperative CT images of brachytherapy seed implantations.

Methods:

The filter works by identifying voxels that are likely streaks and estimating more reflective voxel intensity by using voxel intensities in adjacent CT slices and applying a median filter over voxels not identified as seeds. Median values are computed over a region of interest (ROI) within the CT volume. An acrylic phantom simulating a clinical seed implant arrangement and containing nonradioactive seeds was created. Low contrast subvolumes of tissuelike material were also embedded in the phantom. Pre‐ and postprocessed image quality metrics were compared using the standard deviation of ROIs between the seeds, the CT numbers of low contrast ROIs embedded within the phantom, the signal to noise ratio (SNR), and the contrast to noise ratio (CNR) of the low contrast ROIs. The method was demonstrated with a clinical postimplant CT dataset.

Results:

After the filter was applied, the standard deviation of CT values in streak artifact regions was significantly reduced from 76.5 to 7.2 HU. Within the observable low contrast plugs, the mean of all ROI standard deviations was significantly reduced from 60.5 to 3.9 HU, SNR significantly increased from 2.3 to 22.4, and CNR significantly increased from 0.2 to 4.1 (all). The mean CT in the low contrast plugs remained within 5 HU of the original values.

Conclusion:

An efficient postprocessing filter that does not require access to projection data, which can be applied irrespective of CT scan parameters has been developed, provided the slice thickness and spacing is 3 mm or less.
A planning quality evaluation tool for prostate adaptive IMRT based on machine learning
Authors: Zhu Xiaofeng , Ge Yaorong , Li Taoran , Thongphiew Danthai , Yin Fang‐Fang , Wu Q Jackie
Published: February 2011

Purpose:

To ensure plan quality for adaptive IMRT of the prostate, we developed a quantitative evaluation tool using a machine learning approach. This tool generates dose volume histograms (DVHs) of organs‐at‐risk (OARs) based on prior plans as a reference, to be compared with the adaptive plan derived from fluence map deformation.

Methods:

Under the same configuration using seven‐field 15 MV photon beams, DVHs of OARs (bladder and rectum) were estimated based on anatomical information of the patient and a model learned from a database of high quality prior plans. In this study, the anatomical information was characterized by the organ volumes and distance‐to‐target histogram (DTH). The database consists of 198 high quality prostate plans and was validated with 14 cases outside the training pool. Principal component analysis (PCA) was applied to DVHs and DTHs to quantify their salient features. Then, support vector regression (SVR) was implemented to establish the correlation between the features of the DVH and the anatomical information.

Results:

DVH/DTH curves could be characterized sufficiently just using only two or three truncated principal components, thus, patient anatomical information was quantified with reduced numbers of variables. The evaluation of the model using the test data set demonstrated its accuracy in prediction and effectiveness in improving ART planning quality.

Conclusions:

An adaptive IMRT plan quality evaluation tool based on machine learning has been developed, which estimates OAR sparing and provides reference in evaluating ART.