bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of sodium/hydrogen exchange in the teratogenic response to acetazolamide
Authors: Scott William J. , Bell Sheila M. , Schreiner Claire M.
Published: May 2008

ABSTRACT Administration of acetazolamide to pregnant rodents leads to postaxial forelimb ectrodactyly, generally right‐sided, in the offspring. We previously postulated that this uniquely localized malformation was caused by a reduction of intracellular PH(pHi) in the embryonic limb bud cells. The hypothesis is supported by numerous lines of evidence including the exacerbation of forelimb ectrodactyly by co‐administration of amiloride. One action of amiloride is to inhibit the activity of Na+/H+ exchangers (NHEs), the major mechanism by which most eukaryotic cells regulate their internal pH. A mouse without this exchange mechanism should theoretically be hypersensitive to acetazolamide‐induced postaxial forelimb ectrodactyly because the limb bud cells should be less able to recover from reduction of intracellular pH. To test this hypothesis we created a targeted knockout of NHE‐1 (Na+/H+ Exchanger‐1), to which we administered acteazolamide. The frequency and/or severity of forelimb ectrodactyly was no worse in NHE‐1 null fetuses than in wild type or heterozygous littermates. We interpret this negative result to suggest that there are compensatory pathways by which embryonic cells can rid themselves of excess protons. We examined this idea by co‐administration of acetazolamide and DIDS. This latter agent inhibits CI‐/HCO3 exchange, a common mechanism for regulation of pHi against acidosis. Although malformation frequency and severity were high after this combination treatment, NHE‐1 null embryos were not more affected with postaxial fore‐limb ectrodactyly than their heterozygous and wild type littermates. We presume that embryonic limb bud cells possess another pathway through which they can regulate cytoplasmic proton concentration under acidotic conditions.
PSK, a biological response modifier, modifies p53 expression, mitosis and apoptosis in X‐ray irradiated mouse embryos: Possible cellular mechanism of the anti‐terato‐genic effect
Authors: Kagohashi Yukiko , Naora Hiroyuki , Otani Hiroki
Published: May 2008

ABSTRACT  We previously showed that PSK, a biological response modifier, suppressed X‐ray irradiation induced ocular anomalies in mouse embryos. In the present study, in mouse embryos irradiated at E7.5, PSK, when administered immediately after irradiation, suppressed mitosis and increased apoptosis as compared with embryos not treated with PSK at 12 hrs after irradiation. In the irradiated embryos, p53, which is normally expressed at a high level in early embryos, increased at 6 hrs and decreased at 12 hrs after irradiation. In the irradiated and PSK‐treated embryos, the p53 level did not change at 6 hrs, increased at 12 hrs and decreased at 24 hrs after irradiation. This timing of PSK‐induced delayed increase of p53 coincided with that of the PSK‐induced decrease in mitosis and increase in apoptosis. These results suggested that PSK modified the p53 level and affected cell proliferation and apoptosis, which might contribute to the suppression of teratogenesis.
Endocrine disruptor issues in Japan
Authors: Iguchi Taisen , Sumi Manabu , Tanabe Shinsuke
Published: May 2008

ABSTRACT  Monitoring of environmental chemicals in Japan has revealed that several endocrine active chemicals are in river water, sediments, and wildlife as well as in the human umbilical cord. In 2001, risk assessments of tributyltin and nonylphenol have been conducted by the Ministry of the Environment, Japan. Risk assessments of di(2‐ethylhexyl)phthalate and di‐isononyl phthalate have also been performed by the Ministry of Health, Labour and Welfare using a toxicological point of view in 2001. In this review, an overview of recent progress in endocrine disruptor research in Japan will be provided.
A selective loss of small‐diameter myelinated optic nerve axons in rats prenatally exposed to ethanol
Authors: Sawada Kazuhiko , Sakata‐Haga Hiromi , Komatsu Suguru , Ohta Kyoko , Jeong Young‐Gil , Fukui Yoshihiro
Published: May 2008

ABSTRACT  Pregnant rats were fed an ethanol‐containing liquid diet between gestational days 10 and 21. The optic nerves of their litters at 49 days of age were examined using quantitative stereological procedures. Cross‐sectional areas of the optic nerve in ethanol‐exposed rats were significantly smaller than those in controls. This was reflected in the reduced number of myelinated fibers, but not of non‐myelinated fibers. The size distribution histogram indicated a decreased number of small axonal‐diameter myelinated fibers in ethanol‐exposed rats. The results suggested optic nerve hypoplasia hi ethanol‐exposed rats characterized by a selective loss of small‐diameter myelinated fibers.
Architectural changes in the developing human brain based on the matrix cell theory
Authors: Nakamura Yasuhiro
Published: May 2008

ABSTRACT  Architectural changes in the developing human brain are discussed based on the matrix cell theory. Neural stem cells/matrix cells with self‐renewing ability and multipotency exist in the developing human brain in vivo. The brain development is divided into three stages and the cell differentiation is time regulated. Immunohistochemical distribution of various markers for brain development is summarized and categorized along with differentiation lineages. Particularly, the existence of glial fibrillary acidic protein is re‐evaluated in the developing human brain. The commonly used terms and concepts “radial glial fiber” or “subventricular zone” are also re‐evaluated.
Immunological evaluation and clinical aspects of children with congenital cytomegalovirus infection
Authors: Numazaki Kei , Fujikawa Tomoko , Asanuma Hideomi
Published: May 2008

ABSTRACT  To determine the ability of immunological response to human cytomegalovirus (CMV), the flow cytometric assay was evaluated as a tool for real‐time monitoring of specific cellular immunity in children with congenital CMV infection. Longitudinal cohort study of 2 children with asymptomatic and 2 with symptomatic congenital CMV infection evaluated at birth and followed up with serial age‐appropriate neurodevelopmental testing. Frequencies of CMV‐specific CD4+ T cell in these children were detected by intracellular cytokines (ICC), interferon (IFN)‐γ and tumor necrosis factor (TNF)‐α, staining.

Findings detected by CT and MRI were the most sensitive predictor for neurodevelopmental prognosis. Frequencies of CMV‐specific CD4+ T cells detected by ICC, both IFN‐γ and TNF‐α, were higher in 2 children with symptomatic congenital CMV infection than those in 2 children with asymptomatic congenital infection. Frequencies of CMV‐specific CD4+ T cells in 2 children with symptomatic congenital infection were significantly higher than those in 6 healthy children of 1 to 5‐years of age with serum anti‐CMV IgG antibody without serum anti‐CMV IgM antibody and viral excretion in to urine (p < 0.01). The ICC assay reflects immunological activity against CMV infection in children with asymptomatic or symptomatic congenial infection. Categorizing findings obtained by the ICC assay may helps to determine the prognosis of children with congenital CMV infection.
An experimental model using guinea pigs to reduce accumulated dioxins in the body
Authors: Sakurai Kenichi , Todaka Emiko , Suzuki Yoshifumi , Mori Chisato
Published: May 2008

ABSTRACT  Dioxins are one of the accumulative endocrine disruptors that are detected from the human body. They are known to induce a wide range of adverse effects, however there are only a few methods that have been reported to reduce them. Consequently, a new effective method to reduce the dioxins in our body needs to be developed. To develop such a method, animal models are needed to be experimented on in order to evaluate each method required. In this study, an animal model using guinea pigs was made to evaluate the methods. Three weeks after the administration of 0.05 μg/kg/day of TCDD for 5 days, the serum TCDD level in the guinea pigs was almost equal to the relatively high dioxin level among human serum. Our present study suggests that the guinea pig model used in this research can be effective for further study in the method to reduce accumulated dioxins in the body.
Observation of X‐Y chromosomal configuration in spermatocytes of infertile PD strain male rats
Authors: Hojo Hitoshi , Aoyama Hiroaki , Teramoto Shoji
Published: May 2008

ABSTRACT  PD strain male rats that carry an autosomal recessive gene, preaxial duplication (gene symbol: pd), are sterile in the homozygous condition (pd/pd) due to a spermatogenic breakdown in the process of spermatogenesis at the spermatocyte and/or spermatid stage(s), although heterozygotes (pd/+) are normal. In this study, pd/pd males were examined for the presence of abnormal association of the sex chromosomes that might lead to spermatogenic breakdown. Light and electron microscopic observations of the chromosomes at meiotic prophase and metaphase in primary spermatocytes revealed several types of abnormal X‐Y association and configurations in pd/pd males. However, the incidences of the abnormal configuration were comparable to those in pd/+ males. These results suggest that abnormal X‐Y chromosome association in the germ cells is not a significant cause of spermatogenic breakdown in pd/pd males.
Ultrastructure of the tegument of the cestode Paraechinophallus japonicus (Bothriocephalidea: Echinophallidae), a parasite of the bathypelagic fish Psenopsis anomala
Authors: Levron Céline , Poddubnaya Larisa G. , Kuchta Roman , Freeman Mark , Wang Yan‐Hai , Scholz Tomáš
Published: May 2008

Abstract. The ultrastructure of the tegument in Paraechinophallus japonicus (Bothriocephalidea: Echinophallidae), a cestode parasite of the bathypelagic fish Psenopsis anomala, was studied using scanning and transmission electron microscopy. Paraechinophallus japonicus lacks a true scolex. Four different types of microtriches have been observed on the tegumental surface of P. japonicus. Capilliform (∼2.3‐μm long) and blade‐like spiniform (∼1.4‐μm long) microtriches are intermingled on the surface of the pseudoscolex. Capilliform microtriches are distinct in possessing a short base and a long electron‐lucent cap. The strobila is covered with two types of microtriches, namely filiform (∼2.1‐μm long) and tusk‐shaped microtriches (≤4.5‐μm long). Tusk‐shaped microtriches are limited to the posterior border of each proglottid and are characterized by a short and narrow base, and a large and wide, sharply pointed, electron‐dense cap. Similar tusk‐shaped microtriches were previously found in members of the family Echinophallidae and may represent an autapomorphy of echinophallid cestodes, all of them being parasitic in centrolophid fish. A unified terminology of microthrix parts is proposed.
Seasonal reproduction and sexual maturity in Odontocymbiola magellanica (Neogastropoda, Volutidae)
Authors: Bigatti Gregorio , Marzinelli Ezequiel M. , Penchaszadeh Pablo E.
Published: May 2008

Abstract. Members of Odontocymbiola magellanica (Volutidae, Odontocymbiolinae) inhabit Argentinean waters from 35°S to the Magallanes Strait. The reproductive biology of this potential fishery resource has not been studied before. Male individuals reach maturity at 80 mm and females at 90 mm, corresponding to ∼7 and 8 years of age, respectively. Mating was observed in the field in all seasons and females possess live spermatozoa in the bursa copulatrix all year round, suggesting that living sperm can be preserved for several months. Major oviposition events occurred July (winter) to December (summer) during the 5 years sampled, as characterized by aggregation of females coincident with increasing photoperiod from winter to summer solstices, and not, apparently, by increase in water temperature. Males showed gametogenic activity throughout the year. Gamete resorption occurred in both sexes. Ultrastructural studies showed that oocytes are attached to companion cells, which enables cell–cell communication and provides support until evacuation; males showed normal sperm cells and two types of parasperms. If populations of O. magellanica are commercially exploited in the future, we propose a minimum catch size of 100 mm, and a ban on the collection of females and egg capsules during the reproductive season.
The nebulosity and distance of the Cepheid RS Puppis
Authors: Feast Michael W.
Published: May 2008

Adopting a distance for RS Pup derived from a period-luminosity relation based on Cepheid parallaxes, it is shown that the phase-lag observations of the surrounding nebulosity by Kervella et al. are well fitted by a model of an equatorial disc at an angle of to the plane of the sky. The astrophysical implications of this are briefly mentioned.
An accretion disc model for quasar optical variability
Authors: Li Shuang-Liang , Cao Xinwu
Published: May 2008

Some different correlations between optical-ultraviolet (UV) variability and other quasar properties, such as luminosity, black hole mass and rest-frame wavelength, were discovered. The positive correlation between optical-UV variability amplitude and black hole mass was first found by Wold et al., and this was confirmed by Wilhite et al. We suggest that the accretion disc model can explain these correlations, provided the optical-UV variability is triggered by the change of accretion rate. The disc temperature of accretion discs decreases with increasing black hole mass, which leads to systematical spectral shape difference with black hole mass even if the black hole is accreting at the same rate . The observed positive correlation between optical-UV variability and black hole mass can be well reproduced by our model calculations, if the mean accretion rate with variation of . We also found that the observed correlations of optical-UV variability amplitude with luminosity or rest-frame wavelength can be qualitatively explained by this accretion disc model.
Pediatric overweight or obesity: Does the label really matter?
Authors: Waldrop Julee , Ferguson Laurie Anne
Published: May 2008

Purpose: To discuss the issue of early identification of overweight and obesity in infants and young children and provide some clinical recommendations based on the current evidence and the World Health Organization’s (WHO) newly released guidelines for growth and development.

Data sources: Comparison of the growth charts from the WHO and the Centers for Disease Control as well as current literature.

Conclusions: Although healthcare providers and the general public recognize overweight and obesity as serious problems, there is still disagreement on what constitutes obesity in infants and young children and when and how to intervene. More research on interventions and outcomes is particularly needed.

Implications for practice: The primary care provider deals with the sequelae of obesity on a daily basis. Some recommendations are provided for nurse practitioners who care for infants and children based on current evidence and expert opinion.
The prevalence and pattern of gastroesophageal reflux symptoms in perimenopausal and menopausal women
Authors: Infantino Mary
Published: May 2008

Purpose: To determine the prevalence and describe the pattern of gastroesophageal reflux disease (GERD) symptoms in premenopausal‐, perimenopausal‐, and menopausal‐age women.

Data sources: Three tools were used to collect data: the Menopause Rating Scale, a standardized, self‐administered 11‐item scale that assesses the presence of menopausal symptoms and their impact on quality of life; the Gastrointestinal Symptom Rating Scale, a standardized, self‐administered 15‐question survey that inquires about both lower and upper gastrointestinal (GI) symptoms; and the Reflux Disease Questionnaire (RDQ), a self‐administered 14‐question survey currently being evaluated in the United States as a specific diagnostic tool for GERD that specifically addresses upper GI symptoms of discomfort. Additionally, GERD were correlated with vasomotor, vaginal, genitourinary, and other menopausal symptoms using multiple regression analysis to assess the relationships between GERD and menopausal symptoms.

Conclusions: Approximately 497 women between the ages of 25 and 60 years completed the surveys. The prevalence of GERD symptoms was high in this sample. Almost 42% of perimenopausal and 47% of menopausal participants complained of upper GI symptoms. Although perimenopausal and menopausal women had higher percentages of GERD diagnosis as compared to premenopausal women, 80% of the perimenopausal and menopausal groups had never been diagnosed with an upper GI disorder. A post hoc analysis of RDQ results demonstrated that patients with menopause had significantly more upper GI discomfort. Overall, this study found that menopausal women were 2.9 times more likely to have GERD symptoms.

Implications for practice: These findings are strongly suggestive of a hormonal link between perimenopausal and menopausal states and increasing GERD symptoms. Women of all ages should be screened for symptoms of GERD, especially in the perimenopausal and menopausal population of women because diagnosis of GERD is often not made or misdiagnosed. The impact on the quality of life of women experiencing GERD symptoms cannot be underestimated.
Limits to non‐state market regulation: A qualitative comparative analysis of the international sport footwear industry and the Fair Labor Association
Authors: Marx Axel
Published: May 2008

Non‐state market regulation has become a central focus and continues to receive scholarly attention. The present paper provides an assessment of the conditions under which multinational firms join a multi‐stakeholder certification initiative. The cases of the Fair labor Association and 17 international sport footwear companies have been selected for this purpose. A Qualitative Comparative Analysis of the 17 cases is performed. The paper argues that the combination of sustained NGO pressure and public ownership of a firm is a necessary precondition for firms joining a multi‐stakeholder certification initiative. The theoretical and policy implications of this result are discussed.
Geology and Re‐Os Geochronology of Mineralization of the Miduk Porphyry Copper Deposit, Iran
Authors: Taghipour Nader , Aftabi Alijan , Mathur Ryan
Published: May 2008

The Miduk porphyry copper deposit is located in Kerman province, 85 km northwest of the Sar Cheshmeh porphyry copper deposit, Iran. The deposit is hosted by Eocene volcanic rocks of andesitic–basaltic composition. The porphyry‐type mineralization is associated with two Miocene calc‐alkaline intrusive phases (P1 and P2, respectively). Five hypogene alteration zones are distinguished at the Miduk deposit, including magnetite‐rich potassic, potassic, potassic–phyllic, phyllic and propylitic. Mineralization occurs as stockwork, dissemination and nine generations (magnetite, quartz–magnetite, barren quartz, quartz‐magnetite‐chalcopyrite‐anhydrite, chalcopyrite–anhydrite, quartz‐chalcopyrite‐anhydrite‐pyrite, quartz‐molybdenite‐anhydrite ± chalcopyrite ± magnetite, pyrite, and quartz‐pyrite‐anhydrite ± sericite) of veinlets and veins. Early stages of mineralization consist of magnetite rich veins in the deepest part of the deposit and the main stage of mineralization contains chalcopyrite, magnetite and anhydrite in the potassic zone. The high intensity of mineralization is associated with P2 porphyry (Miduk porphyry). Based on petrography, mineralogy, alteration halos and geochemistry, the Miduk porphyry copper deposit is similar to those of continental arc setting porphyry copper deposits. The Re‐Os molybdenite dates provide the timing of sulfide mineralization at 12.23 ± 0.07 Ma, coincident with U/Pb zircon ages of the P2 porphyry. This evidence indicates a direct genetic relationship between the Miduk porphyry stock and molybdenite mineralization. The Re‐Os age of the Miduk deposit marks the main stage of magmatism and porphyry copper formation in the Central Iranian volcano‐plutonic belt.
Evaluating Thickness of Bauxite Deposit Using Indicator Geostatistics and Fuzzy Estimation
Authors: Dag Ahmet , Mert Bayram A.
Published: May 2008

Evaluating the geological properties of a mineral deposit is a fundamental task for mine planning and it requires an assessment of reserve parameters such as thickness and grade. This paper presents a linguistic model for estimating bauxite thickness within a deposit in a fuzzy environment using indicator geostatistics and fuzzy modeling. The proposed model consists of two main stages: determining the orebody boundary and estimating the thickness. In order to estimate the thickness, a rule‐based fuzzy inference mechanism has been developed based on data statistics. Results and performance of the model have been compared with that of a well‐known conventional technique, geostatistics (kriging), and it is shown that the proposed model has bigger estimation power. In addition, the fuzzy approach is more flexible than the kriging approach. The fuzzy methodology used in the present paper is convenient for modeling reserve parameters.
Newer Combination Therapies in the Management of Hypertension: An Update
Authors: Gradman Alan H. , Weir Matthew R. , Bakris George L.
Published: May 2008

A panel was convened to discuss current combination therapy for hypertension. Alan H. Gradman, MD, of the Western Pennsylvania Hospital, Temple University School of Medicine (Clinical Campus), Pittsburgh, PA, moderated the discussion. Participants included Matthew R. Weir, MD, University of Maryland School of Medicine, Baltimore, MD, and George L. Bakris, MD, University of Chicago, Chicago, IL.
Retracted: Predictive Validity of a Medication Adherence Measure in an Outpatient Setting
Authors: Morisky Donald E. , Ang Alfonso , Krousel‐Wood Marie , Ward Harry J.
Published: May 2008

This study examines the psychometric properties and tests the concurrent and predictive validity of a structured, self‐reported medication adherence measure in patients with hypertension. The authors also assessed various psychosocial determinants of adherence, such as knowledge, social support, satisfaction with care, and complexity of the medical regimen. A total of 1367 patients participated in the study; mean age was 52.5 years, 40.8% were male, 76.5% were black, 50.8% graduated from high school, 26% were married, and 54.1% had income <$5,000. The 8‐item medication adherence scale was reliable (α=.83) and significantly associated with blood pressure control (P<.05). Using a cutpoint of <6, the sensitivity of the measure to identify patients with poor blood pressure control was estimated to be 93%, and the specificity was 53%. The medication adherence measure proved to be reliable, with good concurrent and predictive validity in primarily low‐income, minority patients with hypertension and might function as a screening tool in outpatient settings with other patient groups.
Cardiovascular Disease in Blacks: Can We Stop the Clock?
Authors: Ferdinand Keith C.
Published: May 2008

Blacks have the highest rates of hypertension and cardiovascular disease, with earlier onset, greater severity, and more target organ damage including coronary disease, heart failure, stroke, and end‐stage renal disease. A major reason is the greater prevalence of other cardiovascular disease risk factors, particularly obesity, inactivity, and diabetes mellitus, along with socioeconomic differences, adherence, and achievement of goals. This review focuses on the burden of cardiovascular disease in blacks. Therapeutic lifestyle changes and pharmacologic interventions to decrease clinical events in this high‐risk group are described. Intensive blood pressure control is a primary means of “stopping the clock” in the progression of cardiovascular disease and renal disease. Thiazide diuretics remain primary first‐step agents, especially for uncomplicated hypertension; calcium channel blockers are also efficacious. However, renin‐angiotensin system modulators may also be beneficial, especially with a diuretic, considering the high prevalence in this group of patients of compelling indications for use of such agents.
Optimum Location of an Internal Hinge of a Uniform Column on an Elastic Foundation
Authors: Wang C. Y.
Published: May 2008

The buckling of a column affected by both an internal hinge and an elastic foundation is studied analytically. It is found that the elastic foundation raises the buckling force, but nonlinearly. The optimum locations for the hinge are determined.
Modeling of a One-Sided Bonded and Rigid Constraint Using Beam Theory
Authors: Ryan Peter J. , Adams George G. , McGruer Nicol E.
Published: May 2008

In beam theory, constraints can be classified as fixed/pinned depending on whether the rotational stiffness of the support is much greater/less than the rotational stiffness of the freestanding portion. For intermediate values of the rotational stiffness of the support, the boundary conditions must account for the finite rotational stiffness of the constraint. In many applications, particularly in microelectromechanical systems and nanomechanics, the constraints exist only on one side of the beam. In such cases, it may appear at first that the same conditions on the constraint stiffness hold. However, it is the purpose of this paper to demonstrate that even if the beam is perfectly bonded on one side only to a completely rigid constraining surface, the proper model for the boundary conditions for the beam still needs to account for beam deformation in the bonded region. The use of a modified beam theory, which accounts for bending, shear, and extensional deformation in the bonded region, is required in order to model this behavior. Examples are given for cantilever, bridge, and guided structures subjected to either transverse loads or residual stresses. The results show significant differences from the ideal bond case. Comparisons made to a three-dimensional finite element analysis show a good agreement.
Exact Response of a Translating String With Arbitrarily Varying Length Under General Excitation
Authors: Zhu W. D. , Zheng N. A.
Published: May 2008

The exact response of a translating string with constant tension and arbitrarily varying length is determined under general initial conditions and external excitation. The governing equation is transformed to a standard hyperbolic equation using characteristic transformation. The domain of interest for the transformed equation is divided into groups of subdomains according to the properties of wave propagation. d’Alembert’s solution for any point in the zeroth subdomain group is obtained by using the initial conditions. The solution is extended to the whole domain of interest by using the boundary conditions, and a recursive mapping is found for the solution in the second and higher groups of subdomains. The least upper bound of the displacement of the freely vibrating string is obtained for an arbitrary movement profile. The forced response of the string with nonhomogeneous boundary conditions is obtained using a transformation method and the direct wave method. A new method is used to derive the rate of change of the vibratory energy of the translating string from the system viewpoint. Three different approaches are used to derive and interpret the rate of change of the vibratory energy of the string within a control volume, and the energy growth mechanism of the string during retraction is elucidated. The solution methods are applied to a moving elevator cable with variable length. An interesting parametric instability phenomenon in a translating string with sinusoidally varying length is discovered.
Transient Wave Propagation in Multilayered Viscoelastic Media: Theory, Numerical Computation, and Validation
Authors: Sun Lu , Luo Feiquan
Published: May 2008

This paper extends the classical problem of transient wave propagation in multilayered solids to transient wave propagation in multilayered viscoelastic solids. Laplace and Hankel transforms and the transfer-matrix approach are used in the formulation together with the elastic-viscoelastic correspondence principle in linear viscoelasticity. The derived formula provides a theoretical basis to allow effective and efficient numerical algorithms to be developed. MATLAB is used to develop a computer program DYNALAYERT that implements the theory developed. The numerical results are compared with the existing data available in literature and those obtained from finite element analysis using ANSYS. Excellent agreement has been observed from comprehensive comparisons, which verifies the validity of the theory, algorithm, and computer program developed in this study. The conclusion and findings of this study may result in a number of engineering applications, such as nondestructive evaluation of highway and airport pavements, petroleum exploration, countermine technology, geophysical inversion, structural health monitoring, and vehicle weigh-in-motion systems.
A Microcontact Non-Gaussian Surface Roughness Model Accounting for Elastic Recovery
Authors: Liou Jeng Luen , Lin Jen Fin
Published: May 2008

Most statistical contact analyses assume that asperity height distributions (g(z*)) follow a Gaussian distribution. However, engineered surfaces are frequently non-Gaussian with the type dependent on the material and surface state being evaluated. When two rough surfaces experience contact deformations, the original topography of the surfaces varies with different loads, and the deformed topography of the surfaces after unloading and elastic recovery is quite different from surface contacts under a constant load. A theoretical method is proposed in the present study to discuss the variations of the topography of the surfaces for two contact conditions. The first kind of topography is obtained during the contact of two surfaces under a normal load. The second kind of topography is obtained from a rough contact surface after elastic recovery. The profile of the probability density function is quite sharp and has a large peak value if it is obtained from the surface contacts under a normal load. The profile of the probability density function defined for the contact surface after elastic recovery is quite close to the profile before experiencing contact deformations if the plasticity index is a small value. However, the probability density function for the contact surface after elastic recovery is closer to that shown in the contacts under a normal load if a large initial plasticity index is assumed. How skewness (Sk) and kurtosis (Kt), which are the parameters in the probability density function, are affected by a change in the dimensionless contact load, the initial skewness (the initial kurtosis is fixed in this study) or the initial plasticity index of the rough surface is also discussed on the basis of the topography models mentioned above. The behavior of the contact parameters exhibited in the model of the invariant probability density function is different from the behavior exhibited in the present model.
4D laser camera for accurate patient positioning, collision avoidance, image fusion and adaptive approaches during diagnostic and therapeutic procedures
Authors: Brahme Anders , Nyman Peter , Skatt Björn
Published: May 2008

A four‐dimensional (4D) laser camera (LC) has been developed for accurate patient imaging in diagnostic and therapeutic radiology. A complementary metal‐oxide semiconductor camera images the intersection of a scanned fan shaped laser beam with the surface of the patient and allows real time recording of movements in a three‐dimensional (3D) or four‐dimensional (4D) format . The LC system was first designed as an accurate patient setup tool during diagnostic and therapeutic applications but was found to be of much wider applicability as a general 4D photon “tag” for the surface of the patient in different clinical procedures. It is presently used as a 3D or 4D optical benchmark or tag for accurate delineation of the patient surface as demonstrated for patient auto setup, breathing and heart motion detection. Furthermore, its future potential applications in gating, adaptive therapy, 3D or 4D image fusion between most imaging modalities and image processing are discussed. It is shown that the LC system has a geometrical resolution of about 0, and that the rigid body repositioning accuracy is about 0, below displacements, below and better than at . This indicates a slight need for repeated repositioning when the initial error is larger than about . The positioning accuracy with standard patient setup procedures for prostate cancer at Karolinska was found to be about when independently measured using the LC system. The system was found valuable for positron emission tomography‐computed tomography (PET‐CT) in vivo tumor and dose delivery imaging where it potentially may allow effective correction for breathing artifacts in 4D PET‐CT and image fusion with lymph node atlases for accurate target volume definition in oncology. With a LC system in all imaging and radiation therapy rooms, auto setup during repeated diagnostic and therapeutic procedures may save around per session, increase accuracy and allow efficient image fusion between all imaging modalities employed.
Fourier transform infrared imaging and small angle x‐ray scattering as a combined biomolecular approach to diagnosis of breast cancer
Authors: Ooi Geraldine J. , Fox Jane , Siu Karen , Lewis Rob , Bambery Keith R. , McNaughton Don , Wood Bayden R.
Published: May 2008

Fourier transform infrared (FTIR) microspectroscopic imaging and small angle x‐ray scattering (SAXS) were combined to investigate the supramolecular structure of collagen from 27 tissue sections from patients undergoing mastectomy, excisional biopsy, or mammoplasty. Both techniques were correlated by matching the scattering profile from the SAXS data with the integrated area of the infrared collagen region . The FTIR spectral profiles and multivariate analysis of various tissue components showed consistent differences between all major tissue components, particularly between cancer and normal tissue cells. Analysis of the SAXS data revealed broad differences between cancer and normal tissue, but were inconclusive due to the small sample size. Parameters were extracted from each technique in relation to their characterization of collagen to reveal a good correlation between the two techniques, which diagnostically parallels with gold‐standard Hematoxylin and Eosin (H&E) stained sections. The results show that the integrated area of collagen region in the FTIR spectrum for cancerous samples is greater than that for noncancerous samples indicating collagen disorder. This supports the notion that collagen is structurally disrupted in cancer tissue consistent with the interpretation of the SAXS data. Overall, both these techniques successfully distinguished cancer from normal breast tissue. Integration of these two techniques was able to better segregate cancer as well as provide a more complete understanding of the differences in collagen on all structural levels during breast cancer development.
Eigendetection of masses considering false positive reduction and breast density information
Authors: Freixenet Jordi , Oliver Arnau , Martí Robert , Lladó Xavier , Pont Josep , Pérez Elsa , Denton Erika R. E. , Zwiggelaar Reyer
Published: May 2008

The purpose of this article is to present a novel algorithm for the detection of masses in mammographic computer‐aided diagnosis systems. Four key points provide the novelty of our approach: (1) the use of eigenanalysis for describing variation in mass shape and size; (2) a Bayesian detection methodology providing a mathematical sound framework, flexible enough to include additional information; (3) the use of a two‐dimensional principal components analysis approach to facilitate false positive reduction; and (4) the incorporation of breast density information, a parameter correlated with the performance of most mass detection algorithms and which is not considered in existing approaches. To study the performance of the system two experiments were carried out. The first is related to the ability of the system to detect masses, and thus, free‐response receiver operating characteristic analysis was used, showing that the method is able to give high accuracy at a high specificity (80% detection at 1.40 false positives per image). Second, the ability of the system to highlight the pixels belonging to a mass is studied using receiver operating characteristic analysis, resulting in . In addition, the robustness of the approach is demonstrated in an experiment where we used the Digital Database for Screening Mammography database for training and the Mammographic Image Analysis Society database for testing the algorithm.
Maximum dose angle for oblique incidence on primary beam protective barriers in the design of medical radiation therapy facilities
Authors: Fondevila Damián , Arbiser Silvio , Sansogne Rosana , Brunetto Mónica , Dosoretz Bernardo
Published: May 2008

Primary barrier determinations for the shielding of medical radiation therapy facilities are generally made assuming normal beam incidence on the barrier, since this is geometrically the most unfavorable condition for that shielding barrier whenever the occupation line is allowed to run along the barrier. However, when the occupation line (for example, the wall of an adjacent building) runs perpendicular to the barrier (especially roof barrier), then two opposing factors come in to play: increasing obliquity angle with respect to the barrier increases the attenuation, while the distance to the calculation point decreases, hence, increasing the dose. As a result, there exists an angle for which the equivalent dose results in a maximum, constituting the most unfavorable geometric condition for that shielding barrier. Based on the usual NCRP Report No. 151 model, this article presents a simple formula for obtaining , which is a function of the thickness of the barrier and the equilibrium tenth‐value layer of the shielding material for the nominal energy of the beam. It can be seen that increases for increasing (hence, beam energy) and decreases for increasing , with a range of variation that goes from 13 to 40 deg for concrete barriers thicknesses in the range of 50–300 cm and most commercially available teletherapy machines. This parameter has not been calculated in the existing literature for radiotherapy facilities design and has practical applications, as in calculating the required unoccupied roof shielding for the protection of a nearby building located in the plane of the primary beam rotation.
The spatial resolution in dosimetry with normoxic polymer‐gels investigated with the dose modulation transfer approach
Authors: Bayreder Christian , Schön Robert , Wieland M. , Georg Dietmar , Moser Ewald , Berg Andreas
Published: May 2008

The verification of dose distributions with high dose gradients as appearing in brachytherapy or stereotactic radiotherapy for example, calls for dosimetric methods with sufficiently high spatial resolution. Polymer gels in combination with a MR or optical scanner as a readout device have the potential of performing the verification of a three‐dimensional dose distribution within a single measurement. The purpose of this work is to investigate the spatial resolution achievable in MR‐based polymer gel dosimetry. The authors show that dosimetry on a very small spatial scale (voxel size: ) can be performed with normoxic polymer gels using parameter selective imaging. In order to prove the spatial resolution obtained we are relying on the dose‐modulation transfer function (DMTF) concept based on very fine dose modulations at half periods of . Very fine periodic dose modulations of a photon field were achieved by means of an absorption grid made of tungsten‐carbide, specifically designed for quality control. The dose modulation in the polymer gel is compared with that of film dosimetry in one plane via the DMTF concept for general access to the spatial resolution of a dose imaging system. Additionally Monte Carlo simulations were performed and used for the calculation of the DMTF of both, the polymer gel and film dosimetry. The results obtained by film dosimetry agree well with those of Monte Carlo simulations, whereas polymer gel dosimetry overestimates the amplitude value of the fine dose modulations. The authors discuss possible reasons. The in‐plane resolution achieved in this work competes with the spatial resolution of standard clinical film‐scanner systems.
A dual modality phantom for cone beam CT and ultrasound image fusion in prostate implant
Authors: Ng Angela , Beiki‐Ardakan Akbar , Tong Shidong , Moseley Douglas , Siewerdsen Jeffrey , Jaffray David , Yeung Ivan W. T.
Published: May 2008

In transrectal ultrasound (TRUS) guided prostate seed brachytherapy, TRUS provides good delineation of the prostate while x‐ray imaging, e.g., C‐arm, gives excellent contrast for seed localization. With the recent availability of cone beam CT (CBCT) technology, the combination of the two imaging modalities may provide an ideal system for intraoperative dosimetric feedback during implantation. A dual modality phantom made of acrylic and copper wire was designed to measure the accuracy and precision of image coregistration between a C‐arm based CBCT and 3D TRUS. The phantom was scanned with TRUS and CBCT under the same setup condition. Successive parallel transverse ultrasound (US) images were acquired through manual stepping of the US probe across the phantom at an increment of over . The CBCT imaging was done with three reconstructed slice thicknesses (0.4, 0.8, and ) as well as at three different tilt angles (0°, 15°, 30°), and the coregistration between CBCT and US images was done using the Variseed system based on four fiducial markers. Fiducial localization error (FLE), fiducial registration error (FRE), and target registration error (TRE) were calculated for all registered image sets. Results showed that FLE were typically less than , FRE were less than , and TRE were typically less than within the range of operation for prostate implant (i.e., to surface of US probe). An analysis of variance test showed no significant difference in TRE for the CBCT–US fusion among the three slice thicknesses . As a comparison, the experiment was repeated with a US‐conventional CT scanner combination. No significant difference in TRE was noted between the US‐conventional CT fusion and that for all three CBCT image slice thicknesses . CBCT imaging was also performed at three different C‐arm tilt angles of 0°, 15°, and 30° and reconstructed at a slice thickness of . There is no significant difference in TRE between 0° and 15° as well as between 0° and 30° , which suggests that the C‐arm may be tilted intraoperatively to acquire CBCT images without compromising the quality of image fusion. The results conclude a high degree of accuracy and precision for the CBCT–TRUS fusion, which could be useful toward achieving real time intraoperative dosimetry in prostate brachytherapy.
Attenuator design for organs at risk in total body irradiation using a translation technique
Authors: Lavallée Marie‐Claude , Aubin Sylviane , Chrétien Mario , Larochelle Marie , Beaulieu Luc
Published: May 2008

Total body irradiation (TBI) is an efficient part of the treatment for malignant hematological diseases. Dynamic TBI techniques provide great advantages (e.g., dose homogeneity, patient comfort) while overcoming treatment room space restrictions. However, with dynamic techniques come additional organs at risk (OAR) protection challenges. In most dynamic TBI techniques, lead attenuators are used to diminish the dose received by the OARs. The purpose of this study was to characterize the dose deposition under various shapes of attenuators in static and dynamic treatments. This characterization allows for the development of a correction method to improve attenuator design in dynamic treatments. The dose deposition under attenuators at different depths in dynamic treatment was compared with the static situation based on two definitions: the coverage areas and the penumbra regions. The coverage area decreases with depth in dynamic treatment while it is stable for the static situation. The penumbra increases with depth in both treatment modes, but the increasing rate is higher in the dynamic situation. Since the attenuator coverage is deficient in the dynamic treatment mode, a correction method was developed to modify the attenuator design in order to improve the OAR protection. The correction method is divided in two steps. The first step is based on the use of elongation charts, which provide appropriate attenuator coverage and acceptable penumbra for a specific depth. The second point is a correction method for the thoracic inclination, which can introduce an orientation problem in both static and dynamic treatments. This two steps correction method is simple to use and personalized to each patient's anatomy. It can easily be adapted to any dynamic TBI techniques.
Stepwise multi‐criteria optimization for robotic radiosurgery
Authors: Schlaefer A. , Schweikard A.
Published: May 2008

Achieving good conformality and a steep dose gradient around the target volume remains a key aspect of radiosurgery. Clearly, this involves a trade‐off between target coverage, conformality of the dose distribution, and sparing of critical structures. Yet, image guidance and robotic beam placement have extended highly conformal dose delivery to extracranial and moving targets. Therefore, the multi‐criteria nature of the optimization problem becomes even more apparent, as multiple conflicting clinical goals need to be considered coordinate to obtain an optimal treatment plan. Typically, planning for robotic radiosurgery is based on constrained optimization, namely linear programming. An extension of that approach is presented, such that each of the clinical goals can be addressed separately and in any sequential order. For a set of common clinical goals the mapping to a mathematical objective and a corresponding constraint is defined. The trade‐off among the clinical goals is explored by modifying the constraints and optimizing a simple objective, while retaining feasibility of the solution. Moreover, it becomes immediately obvious whether a desired goal can be achieved and where a trade‐off is possible. No importance factors or predefined prioritizations of clinical goals are necessary. The presented framework forms the basis for interactive and automated planning procedures. It is demonstrated for a sample case that the linear programming formulation is suitable to search for a clinically optimal treatment, and that the optimization steps can be performed quickly to establish that a Pareto‐efficient solution has been found. Furthermore, it is demonstrated how the stepwise approach is preferable compared to modifying importance factors.