bluuebunny/crossref_metadata_2025 huggingface dataset:
Estuarine phase during seaward migration for allis shad Alosa alosa and twaite shad Alosa fallax future spawners
Authors: Lochet A. , Boutry S. , Rochard E.
Published: February 2009

Abstract –  The timing and duration of the estuarine phase during seaward migration were addressed for allis shad and twaite shad, closely related sympatric species in the Gironde system. Otolith Sr:Ca and daily growth increments were used to retrospectively estimate the age at entrance in the estuary, the time spent in estuary and the age at seaward exit from returning adults. The two species exhibited different seaward migration strategies: allis shad entered the estuary at an older age than twaite shad (88 days vs. 59 days), stayed shorter in the estuary (11 days vs. 17 days) and exited to the sea at an older age (99 days vs. 77 days). In the Gironde system, the estuarine phase is very short and occurs within a particular time ‘window’ for the juveniles that will become future spawners. In this context, it might be suggested that the estuarine phase is a bottleneck for these sympatric shad populations.
Trichoblastomas with Merkel cell proliferation in nevi sebacei in Schimmelpenning‐Feuerstein‐Mims syndrome – Histological differentiation between trichoblastomas and basal cell carcinomas
Authors: Wiedemeyer Katharina , Hartschuh Wolfgang
Published: February 2009

The hallmark of Schimmelpenning‐Feuerstein‐Mims syndrome (SFMS) is a systematized nevus sebaceous that follows Blaschko lines and usually involves the face. It represents a rare congenital nevus syndrome with alterations of skin, bones, CNS, eyes and heart. Nevi sebacei can proliferate and develop into epithelial tumors like trichoblastoma, syringocystadenoma and basal cell carcinoma. The histological differentiation between basal cell carcinoma and trichoblastoma is difficult. We present an adult woman with SFMS who was followed by multiple specialties since birth without the correct diagnosis being made. She was referred to us with the diagnosis of multiple basal cell carcinomas of head and face. Our diagnosis of systematized nevus sebaceus was crucial for the correct classification of SFMS. We identified multiple trichoblastomas in the nevi sebacei and could exclude basal cell carcinomas. The essential clue was the detection of multiple Merkel cells within the epidermal layer by cytokeratin 20 staining.
De novo tuberculosis during infliximab therapy in a patient with Behçet disease
Authors: Skvara Hans , Duschek Nikolaus , Karlhofer Franz
Published: February 2009

A woman with oculocutaneous Behçet disease developed primary tuberculosis while being treated with infliximab. A latent tuberculosis infection had been excluded before therapy. After more than 80 weeks of treatment, the patient complained of fevers, night sweats, shivering and vigorous cough. The chest x‐ray showed miliary shadowing. Mycobacterium tuberculosis was identified. The history revealed recent contact to an individual with smear‐positive tuberculosis. This constellation speaks in favor of a de novo tuberculosis infection with a fulminant course.
OBSERVATIONS ON SOCIAL GERONTOLOGY IN FRANCE
Authors: Pitaud Philippe
Published: February 2009

During the past three years we have focused our research activities on the retirement and social aging of women. We were thus provided with the opportunity to review the contributions made by all those connected with the field of gerontology in France who had shown an interest, albeit at varying degrees, in our topic as well as in the problems of the aged in general.

In this paper, we have attempted to assess some of the most important French contributions to social gerontology, isolating the main characteristics of the works we encountered. Successively, we will review the few studies concerning old women and studies dealing more generally with the social and economic aspects of aging.
OLDER WOMEN: HOUSING ISSUES AND PERSPECTIVES
Authors: Coleman Lisa , Watson Sophie
Published: February 2009

This article examines the housing circumstances of 70 women over sixty living independently in Sydney, Canberra and Queanbeyan. The four major housing alternatives for older women — home ownership, public rental, private rental and retirement villages —were explored from the women's point of view. Although in line with other studies private rental was revealed as the worst housing option for the aged, important issues were raised concerning problems in the other three sectors. Particular emphasis in the article is placed on the impact of women's social and economic status on their housing experiences in old age.
POLICIES FOR CARERS
Authors: Rossiter Chris
Published: February 2009

Negotiations on the future of the Home and Community Care Program provide an ideal opportunity to implement policies aimed at assisting those caring for frail and confused elderly people.

The principal source of community care is, in fact, informal care by families and this article describes the experiences of a group of caring families. It then pro‐poses a range of services, benefits and other means of alleviating some problems of home‐based care. It is emphasised that the reorganisation of community care services under HACC must recognise carers' needs.
Novel modified version of nonphosphorylated sugar metabolism – an alternative l‐rhamnose pathway of Sphingomonas sp.
Authors: Watanabe Seiya , Makino Keisuke
Published: February 2009

Several bacteria, including Azotobacter vinelandii, possess an alternative pathway of l‐rhamnose metabolism, which is different from the known bacterial pathway. In a previous article, a gene cluster related to this pathway was identified, consisting of the genes encoding the four metabolic enzymesl‐rhamnose‐1‐dehydrogenase (LRA1), l‐rhamnono‐γ‐lactonase (LRA2), l‐rhamnonate dehydratase (LRA3) and l‐2‐keto‐3‐deoxyrhamnonate (l‐KDR) aldolase (LRA4), by which l‐rhamnose is converted into pyruvate and l‐lactaldehyde, through analogous reaction steps to the well‐known Entner‐Doudoroff (ED) pathway. In this study, bioinformatic analysis revealed that Sphingomonas sp. possesses a gene cluster consisting of LRA1–3 and two genes of unknown function, LRA5 and LRA6. LRA5 catalyzed the NAD+‐dependent dehydrogenation of several l‐2‐keto‐3‐deoxyacid‐sugars, including l‐KDR. Furthermore, the reaction product was converted to pyruvate and l‐lactate by LRA6; this is different from the pathway of Azotobacter vinelandii. Therefore, LRA5 and LRA6 were assigned as the novel enzymes l‐KDR 4‐dehydrogenase and l‐2,4‐diketo‐3‐deoxyrhamnonate hydrolase, respectively. Interestingly, both enzymes were phylogenetically similar to l‐rhamnose‐1‐dehydrogenase and d‐2‐keto‐3‐deoxyarabinonate dehydratase, respectively, and the latter was involved in the archeal nonphosphorylative d‐arabinose pathway, which is partially analogous to the ED pathway. The introduction of LRA1–4 or LRA1–3, LRA5 and LAR6 compensated for the l‐rhamnose‐defective phenotype of an Escherichia coli mutant. Metabolic evolution and promiscuity between the alternative l‐rhamnose pathway and other sugar pathways analogous to the ED pathway are discussed.
Transcriptome profiling analysis reveals multiple modulatory effects of Ginkgo biloba extract in the liver of rats on a high‐fat diet
Authors: Gu Xiaomei , Xie Zuoquan , Wang Qi , Liu Gang , Qu Yi , Zhang Lu , Pan Jiahu , Zhao Guoping , Zhang Qinghua
Published: February 2009

Leaf extract of Ginkgo biloba (GBE) is increasingly used as a herbal medicine for the treatment of neurodegenerative, cardiovascular and cerebrovascular diseases. Several studies have demonstrated many protective effects of GBE in neurons, the endothelium and liver. In this study, we investigated the molecular mechanisms underlying the effects of GBE in disorders induced by long‐term exposure to a high‐fat diet (HFD). Rats were fed an HFD with or without the GBE product GBE50 for 19 weeks. We found that GBE50 reduced the development of fatty liver induced by an HFD and inhibited the commonly observed elevation of serum cholesterol and lactate dehydrogenase levels. Transcriptome profiling analysis showed that several genes were modulated by GBE50 in liver, including those involved in lipid metabolism, carbohydrate metabolism, vascular constriction, ion transportation, neuronal systems and drug metabolism. Notably, a number of genes coding for proteins involved in cholesterol metabolism were repressed, and some were upregulated. Fatty acid biosynthesis appeared to be repressed, whereas fatty acid metabolism appeared to be enhanced. In conclusion, using transcriptome profiling analysis, we demonstrated the molecular basis for the pleiotropic effects of GBE50, particularly those involved in lipid metabolism. This study provided new clues for further pharmacological study of GBEs.
Impact of Sea‐Level Rise on Sea Water Intrusion in Coastal Aquifers
Authors: Werner Adrian D. , Simmons Craig T.
Published: February 2009

Despite its purported importance, previous studies of the influence of sea‐level rise on coastal aquifers have focused on specific sites, and a generalized systematic analysis of the general case of the sea water intrusion response to sea‐level rise has not been reported. In this study, a simple conceptual framework is used to provide a first‐order assessment of sea water intrusion changes in coastal unconfined aquifers in response to sea‐level rise. Two conceptual models are tested: (1) flux‐controlled systems, in which ground water discharge to the sea is persistent despite changes in sea level, and (2) head‐controlled systems, whereby ground water abstractions or surface features maintain the head condition in the aquifer despite sea‐level changes. The conceptualization assumes steady‐state conditions, a sharp interface sea water‐fresh water transition zone, homogeneous and isotropic aquifer properties, and constant recharge. In the case of constant flux conditions, the upper limit for sea water intrusion due to sea‐level rise (up to 1.5 m is tested) is no greater than 50 m for typical values of recharge, hydraulic conductivity, and aquifer depth. This is in striking contrast to the constant head cases, in which the magnitude of salt water toe migration is on the order of hundreds of meters to several kilometers for the same sea‐level rise. This study has highlighted the importance of inland boundary conditions on the sea‐level rise impact. It identifies combinations of hydrogeologic parameters that control whether large or small salt water toe migration will occur for any given change in a hydrogeologic variable.
Distinguishing Iron‐Reducing from Sulfate‐Reducing Conditions
Authors: Chapelle Francis H. , Bradley Paul M. , Thomas Mary Ann , McMahon Peter B.
Published: February 2009

Ground water systems dominated by iron‐ or sulfate‐reducing conditions may be distinguished by observing concentrations of dissolved iron (Fe2+) and sulfide (sum of H2S, HS−, and S= species and denoted here as “H2S”). This approach is based on the observation that concentrations of Fe2+ and H2S in ground water systems tend to be inversely related according to a hyperbolic function. That is, when Fe2+ concentrations are high, H2S concentrations tend to be low and vice versa. This relation partly reflects the rapid reaction kinetics of Fe2+ with H2S to produce relatively insoluble ferrous sulfides (FeS). This relation also reflects competition for organic substrates between the iron‐ and the sulfate‐reducing microorganisms that catalyze the production of Fe2+ and H2S. These solubility and microbial constraints operate in tandem, resulting in the observed hyperbolic relation between Fe2+ and H2S concentrations. Concentrations of redox indicators, including dissolved hydrogen (H2) measured in a shallow aquifer in Hanahan, South Carolina, suggest that if the Fe2+/H2S mass ratio (units of mg/L) exceeded 10, the screened interval being tapped was consistently iron reducing (H2∼0.2 to 0.8 nM). Conversely, if the Fe2+/H2S ratio was less than 0.30, consistent sulfate‐reducing (H2∼1 to 5 nM) conditions were observed over time. Concomitantly high Fe2+ and H2S concentrations were associated with H2 concentrations that varied between 0.2 and 5.0 nM over time, suggesting mixing of water from adjacent iron‐ and sulfate‐reducing zones or concomitant iron and sulfate reduction under nonelectron donor–limited conditions. These observations suggest that Fe2+/H2S mass ratios may provide useful information concerning the occurrence and distribution of iron and sulfate reduction in ground water systems.
Students' perceptions of school meals: a challenge for schools, school‐meal providers, and policymakers
Authors: Lülfs‐Baden Frederike , Spiller Achim
Published: February 2009

School‐meal programmes in Germany are of growing public interest and are gaining in importance, not least because of their ability to influence pupils' eating habits and thereby establish sustainable nutrition patterns. It is in this context that it is important to understand adolescents' perceptions of school food in order to enable policymakers, schools and school‐meal providers to fulfil their nutritional requirements. Therefore, the aim of this study is to create a theoretical model to measure students' satisfaction and to identify the underlying dimensions. The results show that the main predictors of customer satisfaction are service, quality of food and atmosphere, which underlines and reinforces the importance of service quality. Other factors, such as canteen organisation and the foods' nutritional value, influence satisfaction indirectly. Finally, a higher satisfaction level leads to a higher willingness to participate in school‐meal programmes.
Incorporation of ground flaxseed into bakery products and its effect on sensory and nutritional characteristics – a pilot study
Authors: Lipilina Elina , Ganji Vijay
Published: February 2009

We determined the optimum amount of ground flaxseed substitution for flour in bakery products and evaluated the effect of flaxseed on sensory and nutritional qualities of those bakery products using a consumer panel (n = 45). Flaxseed was added to yeast breads at 15, 25 and 30% and to muffins at 33, 50 and 66% substitution levels for flour on a weight for weight basis. Breads containing 30% and muffins containing 50% flaxseed were rated better than their counterparts regarding overall acceptability scores. Linolenic acid, fiber and folate contents were improved by 28 g, 16 g and 387‐µg dietary folate equivalents (DFE), respectively, in 30% flaxseed bread compared to control. In 50% flaxseed muffins compared to control, linolenic acid, fiber and folate contents were improved by 21 g, 17 g and 341‐µg DFE, respectively. Flaxseed at 30–50% substitution for flour greatly enhanced the nutritional qualities of some nutrients without affecting the overall acceptability of bakery products.
Agreement Features
Authors: Wechsler Stephen
Published: February 2009

Grammatical agreement in features such as person, number, and gender presents several puzzles that are of ongoing interest to the linguist. What is the nature of the grammatical mechanism responsible for agreement, and how does it relate to other aspects of syntax? The two main alternative approaches, lexicalist and derivational, will be contrasted. A second question is whether agreement is determined by the form or the meaning of the subject or other phrase that triggers agreement. The answer seems to vary between these two options, and so we must explain how the grammar negotiates between them. Finally, we consider the phenomenon of agreement mismatches, in which conflicting features appear in the same sentence. We consider how to explain these cases, and what they tell us about normal agreement.
Data‐Driven Dialectology
Authors: Nerbonne John
Published: February 2009

Most studies of language variation proceed from the geographic or social distribution of single elements (features), and find it difficult to proceed further. Data‐driven dialectology, and more generally, data‐driven variationist studies, begin instead from an aggregate view of language variation and reap immediate benefits in dealing with well‐known exceptions in the distributions of single features and in avoiding the need to select which features to use as the basis of characterizations. But the major advance is the opportunity to characterize general tendencies in linguistic variation.
Typology of Ergativity
Authors: McGregor William B.
Published: February 2009

Ergativity refers to patterning in a language whereby the subject of a transitive clause behaves differently to the subject of an intransitive clause, which behaves like the object of a transitive clause. Ergativity can be manifested in morphology, lexicon, syntax, and discourse organisation. This article overviews what is known about ergativity in the world's languages, with a particular focus on one type of morphological ergativity, namely in case‐marking. While languages are rarely entirely consistent in ergative case‐marking, and the inconsistencies vary considerably across languages, they are nevertheless not random. Thus splits in case‐marking, in which ergative patterning is restricted to certain domains, follow (with few exceptions) universal tendencies. So also are there striking cross‐linguistic commonalities among systems in which ergative case‐marking is optional, although systematic investigation of this domain is quite recent. Recent work on the diachrony of ergative systems and case‐markers is overviewed, and issues for further research are identified.
Watching the Word Go by: On the Time‐course of Component Processes in Visual Word Recognition
Authors: Grainger Jonathan , Holcomb Phillip J.
Published: February 2009

We describe a functional architecture for word recognition that focuses on how orthographic and phonological information cooperates in initial form‐based processing of printed word stimuli prior to accessing semantic information. Component processes of orthographic processing and orthography‐to‐phonology translation are described, and the behavioral evidence in favor of such mechanisms is briefly summarized. Our theoretical framework is then used to interpret the results of a large number of recent experiments that have combined the masked priming paradigm with electrophysiological recordings. These experiments revealed a series of components in the event‐related potential (ERP), thought to reflect the cascade of underlying processes involved in the transition from visual feature extraction to semantic activation. We provide a tentative mapping of ERP components onto component processes in the model, hence specifying the relative time‐course of these processes and their functional significance.
Best Practices in Technology and Language Teaching
Authors: Hoopingarner Dennie
Published: February 2009

Language teaching can be enhanced by effective uses of educational technology. Based on research findings in language acquisition and computer‐assisted language learning, best practices take into account effective language pedagogy, and appropriate roles of technology. Best practices in using technology to support language teaching and learning see technology as a tool that can enhance teaching and learning by augmenting input, providing additional opportunities for language practice, and serving as a platform for interaction and tasks‐based learning activities.
Genetic diversity and divergence among coastal and offshore reefs in a hard coral depend on geographic discontinuity and oceanic currents
Authors: Underwood Jim N.
Published: February 2009

Understanding the evolutionary processes that have shaped existing patterns of genetic diversity of reef‐building corals over broad scales is required to inform long‐term conservation planning. Genetic structure and diversity of the mass‐spawning hard coral, Acropora tenuis, were assessed with seven DNA microsatellite loci from a series of isolated and discontinuous coastal and offshore reef systems in northwest Australia. Significant subdivision was detected among all sites (FST = 0.062, RST = 0.090), with the majority of this variation due to genetic differentiation among reef systems. In addition, genetic divergence was detected between the coastal and offshore zones that cannot be adequately explained by geographic distance, indicating that transport of larvae between these zones via large‐scale oceanic currents is rare even over time frames that account for connectivity over multiple generations. Significant differences in the amount of genetic diversity at each system were also detected, with higher diversity observed on the lower latitude reefs. The implications are that these reef systems of northwest Australia are not only demographically independent, but that they will also have to rely on their own genetic diversity to adapt to environmental change over the next few decades to centuries.
Oestrogenicity of prenylflavonoids from hops: activation of pro‐oestrogens by intestinal bacteria
Authors: Possemiers Sam , Verstraete Willy
Published: February 2009

For many centuries, hops (Humulus lupulus L.) have been used as essential ingredient in beers, providing the typical bitterness and hoppy flavour. However, the last few years the plant has gained increasing attention as a source of prenylflavonoids and in 1999, 8‐prenylnaringenin (8‐PN) was identified as the most potent phyto‐oestrogen known so far. Hop extracts are therefore now marketed to reduce menopausal complaints. However, 8‐PN concentrations in hops are very low, and variable efficiency of these extracts was observed. Yet, hops also contain isoxanthohumol (IX) in much higher amounts (IX/8‐PN ratio in hop extracts is typically 10–20). This article reviews our recent findings on how the human intestinal microbiota may activate IX. Depending on inter‐individual differences in the intestinal transformation potential, this conversion could easily increase the 8‐PN exposure 10‐fold. The variability in efficacy of hop extracts may therefore be explained by variable intestinal metabolism. Based on this scientific knowledge, an innovative strategy was developed to decrease this variability. First, Eubacterium limosum, capable of rapidly metabolizing all IX into 8‐PN, was isolated from the complex intestinal ecosystem. This bacterium was then used to develop a new generation of hop products with increased reliability in effect. This strategy involves the use of the bacterium as probiotic, in which the bacterium is administered in combination with the original hop extract. This leads to efficient intestinal 8‐PN production, also in individuals who originally did not harbour the appropriate bacteria. The findings presented in this review can therefore be considered as a typical example that good insight in the specific metabolic potential of complex microbial communities and individual bacterial species may offer important opportunities for the management and modulation of the microbial organization towards a certain metabolic function.
Comparative study of hematologic and plasma biochemical variables in Eastern Atlantic juvenile and adult nesting loggerhead sea turtles (Caretta caretta)
Authors: Casal Ana B. , Camacho María , López‐Jurado Luis F. , Juste Candelaria , Orós Jorge
Published: February 2009

Background:Plasma biochemical and hematologic variables are important in the management of endangered sea turtles, such as loggerheads. However, studies on blood biochemistry and hematology of loggerheads are limited, and different concentrations according to variable criteria have been reported.

Objective:The purpose of this study was to establish and compare baseline plasma chemistry and hematology values in Eastern Atlantic juvenile and adult nesting loggerhead sea turtles (Caretta caretta).

Methods:Blood samples were collected from 69 healthy juvenile loggerhead sea turtles after their rehabilitation in captivity, and from 34 adult nesting loggerheads after oviposition. Fresh blood was used for leukocyte differential count and PCV determination. Heparinized blood was used for RBC and WBC counts. Plasma biochemical concentrations were measured using an automated biochemical analyzer. For the comparative study, nonparametric statistical analysis was done using the Mann–WhitneyU‐test.

Results:Minimum, maximum, and median concentrations were obtained for 14 hematologic and 15 plasma chemistry variables. Statistically significant differences between juvenile and adult turtles were found for PCV; RBC, WBC, and leukocyte differential counts; total protein, albumin, globulins, calcium, triglycerides, glucose, total cholesterol and urea concentrations; and lactate dehydrogenase activity.

Conclusions:Age, size, and reproductive status cause important variations in the hematologic and plasma biochemical results of loggerheads. The reference values obtained in this study may be used as a standard profile, useful for veterinary surgeons involved in sea turtle conservation.
Multiscale deformable registration for dual‐energy x‐ray imaging
Authors: Gang G. J. , Varon C. A. , Kashani H. , Richard S. , Paul N. S. , Van Metter R. , Yorkston J. , Siewerdsen J. H.
Published: February 2009

Dual‐energy (DE) imaging of the chest improves the conspicuity of subtle lung nodules through the removal of overlying anatomical noise. Recent work has shown double‐shot DE imaging (i.e., successive acquisition of low‐ and high‐energy projections) to provide detective quantum efficiency, spectral separation (and therefore contrast), and radiation dose superior to single‐shot DE imaging configurations (e.g., with a CR cassette). However, the temporal separation between high‐energy (HE) and low‐energy (LE) image acquisition can result in motion artifacts in the DE images, reducing image quality and diminishing diagnostic performance. This has motivated the development of a deformable registration technique that aligns the HE image onto the LE image before DE decomposition. The algorithm reported here operates in multiple passes at progressively smaller scales and increasing resolution. The first pass addresses large‐scale motion by means of mutual information optimization, while successive passes (2–4) correct misregistration at finer scales by means of normalized cross correlation. Evaluation of registration performance in 129 patients imaged using an experimental DE imaging prototype demonstrated a statistically significant improvement in image alignment. Specific to the cardiac region, the registration algorithm was found to outperform a simple cardiac‐gating system designed to trigger both HE and LE exposures during diastole. Modulation transfer function (MTF) analysis reveals additional advantages in DE image quality in terms of noise reduction and edge enhancement. This algorithm could offer an important tool in enhancing DE image quality and potentially improving diagnostic performance.
A low‐cost density reference phantom for computed tomography
Authors: Levine Zachary H. , Li Mingdong , Reeves Anthony P. , Yankelevitz David F. , Chen Joseph J. , Siegel Eliot L. , Peskin Adele , Zeiger Diana N.
Published: February 2009

The authors characterized a commercially available foam composed of polyurethane and polyisocyanurate which is marketed for modeling parts in the aircraft, automotive, and related industries. The authors found that the foam may be suitable for use as a density reference standard in the range below Hounsfield units. This range is coincident with the density of lung tissue. The foam may be helpful in making the diagnosis of lung disease more systematic.
Microbeam radiation therapy: A Monte Carlo study of the influence of the source, multislit collimator, and beam divergence on microbeams
Authors: Nettelbeck H. , Takacs G. J. , Lerch M. L. F. , Rosenfeld A. B.
Published: February 2009

Microbeam radiation therapy (MRT) is a new oncology method currently under development for the treatment of inoperable pediatric brain tumors. Monte Carlo simulation, or the computational study of radiation transport in matter, is often used in radiotherapy to theoretically estimate the dose required for treatment. However, its potential use in MRT dose planning systems is currently hindered by the significant discrepancies that have been observed between measured and theoretical dose and the PVDR (peak to valley dose ratio). The need to resolve these discrepancies is driven by the desirability of making MRT available to humans in the next few years. This article aims to resolve some of the discrepancies by examining the simplifications adopted in previous MRT Monte Carlo studies, such as the common practice of commencing microbeam transport on the surface of the target which neglects the influence of the distributed synchrotron source, multislit collimator, and the beam divergence between them. This article uses PENELOPE Monte Carlo simulation to investigate the influence of these beamline components upstream of the target on the lateral dose profiles and PVDRs of an array of 25 microbeams. It also compares the dose profiles and PVDRs of a microbeam array produced from a single simulation (full array) to those produced from the superposition of a single microbeam profile (sup array). The effect of modeling the distributed source and the beam divergence was an increase in the absorbed dose in the penumbral and valley regions of the microbeam profiles. Inclusion of the multislit collimator resulted in differences of up to in the FWHM of microbeam profiles across the array, which led to minor variations in the corresponding PVDR yields.
A modified gradient correlation filter for image segmentation: Application to airway and bowel
Authors: Sensakovic William F. , Starkey Adam , Armato Samuel G.
Published: February 2009

The segmentation of structures of interest from medical images may incorrectly include adjacent structures in the segmented image (i.e., false positives). This study introduces a family of gradient correlation filters that reduce false positives in the segmented image by comparing the segmented region gradients with a user‐defined model. A gradient correlation filter was applied to a database of clinical computed tomography scans for the task of differentiating airway from lung regions and bowel from lung regions. The results were evaluated using receiver‐operating characteristic analysis and demonstrated excellent results for both the airway/lung and bowel/lung classification tasks.
Monte Carlo radiation dose simulations and dosimetric comparison of the model 6711 and 9011 brachytherapy sources
Authors: Rivard Mark J.
Published: February 2009

Smaller diameter brachytherapy seeds for permanent interstitial implantation allow for use of smaller diameter implant needles. The use of smaller diameter needles may provide a lower incidence of healthy‐tissue complications. This study determines the brachytherapy dosimetry parameters for the smaller diameter source (model 9011) and comments on the dosimetric comparison between this new source and the conventional brachytherapy seed (model 6711).
Range and modulation dependencies for proton beam dose per monitor unit calculations
Authors: Hsi Wen C. , Schreuder Andries N. , Moyers Michael F. , Allgower Chris E. , Farr Jonathan B. , Mascia Anthony E.
Published: February 2009

Calculations of dose per monitor unit (D∕MU) are required in addition to measurements to increase patient safety in the clinical practice of proton radiotherapy. As in conventional photon and electron therapy, the D∕MU depends on several factors. This study focused on obtaining range and modulation dependence factors used in D∕MU calculations for the double scattered proton beam line at the Midwest Proton Radiotherapy Institute. Three dependencies on range and one dependency on modulation were found. A carefully selected set of measurements was performed to discern these individual dependencies. Dependencies on range were due to: (1) the stopping power of the protons passing through the monitor chamber; (2) the reduction of proton fluence due to nuclear interactions within the patient; and (3) the variation of proton fluence passing through the monitor chamber due to different source‐to‐axis distances (SADs) for different beam ranges. Different SADs are produced by reconfigurations of beamline elements to provide different field sizes and ranges. The SAD effect on the D∕MU varies smoothly as the beam range is varied, except at the beam range for which the first scatterers are exchanged and relocated to accommodate low and high beam ranges. A geometry factor was devised to model the SAD variation effect on the D∕MU. The measured D∕MU variation as a function of range can be predicted within 1% using the three modeled dependencies on range. Investigation of modulated beams showed that an analytical formula can predict the D∕MU dependency as a function of modulation to within 1.5%. Special attention must be applied when measuring the D∕MU dependence on modulation to avoid interplay between range and SAD effects.
Microscintigraphy with high resolution collimators and radiographic detectors
Authors: Mail N. , MacDonald C. A. , Gibson W. M.
Published: February 2009

The potential use of high resolution collimators with standard radiographic detectors in place of conventional gamma cameras for high resolution microscintigraphy is presented. Polycapillary multiple hole collimators are shown to provide scale spatial resolution. A series of images from arrays of brachytherapy seeds in Lucite phantoms display resolution better than with good sensitivity and a field of view. In addition to application to brachytherapy seed localization, such “cellular” level resolution is necessary for high‐resolution in vivo imaging in mouse models. The system could also enable the use of a wider variety of isotopes, including much lower photon energy isotopes in nuclear medicine, as the high resolution collimator allows more flexibility in detector constraints.
Vision : Proton therapy
Authors: Smith Alfred R.
Published: February 2009

The first patients were treated with proton beams in 1955 at the Lawrence Berkeley Laboratory in California. In 1970, proton beams began to be used in research facilities to treat cancer patients using fractionated treatment regimens. It was not until 1990 that proton treatments were carried out in hospital‐based facilities using technology and techniques that were comparable to those for modern photon therapy. Clinical data strongly support the conclusion that proton therapy is superior to conventional radiation therapy in a number of disease sites. Treatment planning studies have shown that proton dose distributions are superior to those for photons in a wide range of disease sites indicating that additional clinical gains can be achieved if these treatment plans can be reliably delivered to patients. Optimum proton dose distributions can be achieved with intensity modulated protons (IMPT), but very few patients have received this advanced form of treatment. It is anticipated widespread implementation of IMPT would provide additional improvements in clinical outcomes. Advances in the last decade have led to an increased interest in proton therapy. Currently, proton therapy is undergoing transitions that will move it into the mainstream of cancer treatment. For example, proton therapy is now reimbursed, there has been rapid development in proton therapy technology, and many new options are available for equipment, facility configuration, and financing. During the next decade, new developments will increase the efficiency and accuracy of proton therapy and enhance our ability to verify treatment planning calculations and perform quality assurance for proton therapy delivery. With the implementation of new multi‐institution clinical studies and the routine availability of IMPT, it may be possible, within the next decade, to quantify the clinical gains obtained from optimized proton therapy. During this same period several new proton therapy facilities will be built and the cost of proton therapy is expected to decrease, making proton therapy routinely available to a larger population of cancer patients.
In vitro in‐stent restenoses evaluated by 3D ultrasound
Authors: Lécart Myriam , Cardinal Marie‐Hélène Roy , Qin Zhao , Soulez Gilles , Cloutier Guy
Published: February 2009

The purpose of this study was to quantify in‐stent restenoses with 3D B mode and power Doppler ultrasound (U.S.) imaging. In‐stent restenoses were mimicked with vascular phantoms in which a nonferromagnetic prototype stent (Boston Scientific) and a ferromagnetic clinical stainless steel stent (Palmaz P295) were embedded. Each phantom had an 80% in‐stent stenosis and a 75% stenosis located outside the stent. These phantoms were compared to a reference phantom reproducing both stenoses without stent. Data sets of 2D cross‐sectional U.S. images were acquired in freehand scanning using a magnetic sensor attached to the U.S. probe and in mechanical linear scanning with the probe attached to a step motor device. Each 2D image was automatically segmented before 3D reconstruction of the vessel. Results indicate that the reference phantom (without stent) was accurately assessed with errors below 1.8% for the 75% stenosis and 3.2% for the 80% stenosis in both B mode and power Doppler for the two scanning methods. The 80% in‐stent stenoses in Boston Scientific and Palmaz stents were, respectively, evaluated at and in B mode and at and in power Doppler when freehand scans were used. For comparison, when linear scans were selected, in‐stent stenoses in the Boston Scientific or Palmaz stent were, respectively, evaluated at and in B mode and at and in power Doppler. To conclude, 3D freehand U.S. is a valuable method to quantify in‐stent restenoses, particularly in B mode. It is thus hoped that, in the clinical setting, noninvasive 3D U.S. may provide sufficient precision to grade in‐stent restenoses.
Quantitative simultaneous cardiac SPECT using MC‐JOSEM
Authors: Ouyang Jinsong , Zhu Xuping , Trott Cathryn M. , El Fakhri Georges
Published: February 2009

Simultaneous rest cardiac SPECT imaging has the potential to replace current clinical ‐Sestamibi rest/stress imaging and therefore has great potential in the case of patients with chest pain presenting to the emergency department. Separation of images of these two radionuclides is difficult, however, because their emission energies are close. The authors previously developed a fast Monte Carlo (MC)‐based joint ordered‐subset expectation maximization (JOSEM) iterative reconstruction algorithm (MC‐JOSEM), which simultaneously compensates for scatter and cross talk as well as detector response within the reconstruction algorithm. In this work, the authors evaluated the performance of MC‐JOSEM in a realistic population of studies using cardiac phantom data on a Siemens e.cam system using a standard cardiac protocol. The authors also compared the performance of MC‐JOSEM for estimation tasks to that of two other methods: standard OSEM using photopeak energy windows without scatter correction (NSC‐OSEM) and standard OSEM using a Compton‐scatter energy window for scatter correction (SC‐OSEM). For each radionuclide the authors separately acquired high‐count projections of radioactivity in the myocardium wall, liver, and soft tissue background compartments of a water‐filled torso phantom, and they generated synthetic projections of various dual‐radionuclide activity distributions. Images of different combinations of myocardium wall/background activity concentration ratios for each radionuclide were reconstructed by NSC‐OSEM, SC‐OSEM, and MC‐JOSEM. For activity estimation in the myocardium wall, MC‐JOSEM always produced the best relative bias and relative standard deviation compared with NSC‐OSEM and SC‐OSEM for all the activity combinations. On average, the relative biases after 100 iterations were 8.1% for and 3.7% for with MC‐JOSEM, 39.4% for and 23.7% for with NSC‐OSEM, and 20.9% for with SC‐OSEM. The relative standard deviations after 30 iterations were 0.7% for and 1.0% for with MC‐JOSEM, as compared to 1.1% for and 1.2% for with NSC‐OSEM and 1.3% for with SC‐OSEM. Finally, the authors compared the relative standard deviation after 30 iterations with the minimum theoretical variance on activity estimation, the Cramer–Rao lower bound (CRB), and with the biased CRB. The measured precision was larger than the biased bound values by factors of 2–4, suggesting that further improvement could be made to the method.
Investigation of PVA cryogel Young's modulus stability with time, controlled by a simple reliable technique
Authors: Duboeuf François , Basarab Adrian , Liebgott Hervé , Brusseau Elisabeth , Delachartre Philippe , Vray Didier
Published: February 2009

We describe a quasistatic method for mechanical characterization of tissue‐mimicking material used in elastography. We demonstrate that it is possible to assess the elasticity modulus with a reasonable reproducibility using simple and easy tools and methods. Possessing a simple relevant technique with evaluated relative error to assess Young's modulus of these phantoms could deeply improve the quality of the research in the field of elastography. The method was tested and validated with four samples of polyvinyl alcohol (PVA) cryogel with different elasticity values corresponding to those of stiffer soft biological tissues. Young's moduli, varying from depending on the number of freeze‐thaw cycles (two to five), were measured within strict measurement conditions and found to have a reproducibility varying from 4% to 8%. Relative error, estimated as the ratio between observed and reference values, varied from 16% to 32%. Besides, measurement stability over was evaluated. The method demonstrated good feasibility and acceptable reproducibility for mechanically characterizing and controlled over time phantoms used for validating new potential ultrasound imaging techniques in the field of elastography. Nevertheless, in this study, investigation was performed on gel possessing young's modulus values ranging from . Some tissue values of Young'modulus were reported to be lower, ranging from as liver or glandular values. Consequently, further validation of this static method for mechanical characterization of phantom gels should be performed using softer PVA cryogel.
BOUND STATES OF THE KLEIN–GORDON EQUATION FOR VECTOR AND SCALAR GENERAL HULTHÉN-TYPE POTENTIALS IN D-DIMENSION
Authors: IKHDAIR SAMEER M.
Published: February 2009

We solve the Klein–Gordon equation in any D-dimension for the scalar and vector general Hulthén-type potentials with any l by using an approximation scheme for the centrifugal potential. Nikiforov–Uvarov method is used in the calculations. We obtain the bound-state energy eigenvalues and the corresponding eigenfunctions of spin-zero particles in terms of Jacobi polynomials. The eigenfunctions are physical and the energy eigenvalues are in good agreement with those results obtained by other methods for D = 1 and 3 dimensions. Our results are valid for q = 1 value when l ≠ 0 and for any q value when l = 0 and D = 1 or 3. The s-wave (l = 0) binding energies for a particle of rest mass m0= 1 are calculated for the three lower-lying states (n = 0, 1, 2) using pure vector and pure scalar potentials.
CRITICAL BEHAVIOR OF THE QUENCHED RANDOM MIXED-SPIN ISING MODEL
Authors: GODOY M. , FIGUEIREDO W.
Published: February 2009

In this work, we simulated a quenched random mixed-spin Ising model on the square lattice. The model system consists of two different particles with spins σ = 1/2 (states ±1/2) and S = 1 (states ±1, 0). These particles are randomly distributed on the lattice, and we considered only nearest-neighbor interactions. This model can represent a random magnetic binary alloy AxB1-x, obtained from the high-temperature quenching of a liquid mixture. We performed Monte Carlo simulations for several lattice sizes and temperatures, and we found its critical temperature through the reduced fourth-order cumulant. We also determined the magnetization, the susceptibility, and the specific heat as a function of temperature. We used finite-size scaling arguments to estimate the critical exponents β, γ, and ν of the model. We showed that the quenched model is in the same universality class of the two-dimensional pure Ising model. We also investigated the sample to sample fluctuations that occur in the values of the thermodynamic quantities in order to describe the self-averaging properties at the critical point.
SPATIAL PATTERN IN A PREDATOR-PREY SYSTEM WITH BOTH SELF- AND CROSS-DIFFUSION
Authors: SUN GUI-QUAN , JIN ZHEN , ZHAO YI-GUO , LIU QUAN-XING , LI LI
Published: February 2009

The vast majority of models for spatial dynamics of natural populations assume a homogeneous physical environment. However, in practice, dispersing organisms may encounter landscape features that significantly inhibit their movement. And spatial patterns are ubiquitous in nature, which can modify the temporal dynamics and stability properties of population densities at a range of spatial scales. Thus, in this paper, a predator-prey system with Michaelis-Menten-type functional response and self- and cross-diffusion is investigated. Based on the mathematical analysis, we obtain the condition of the emergence of spatial patterns through diffusion instability, i.e., Turing pattern. A series of numerical simulations reveal that the typical dynamics of population density variation is the formation of isolated groups, i.e., stripe-like or spotted or coexistence of both. The obtained results show that the interaction of self-diffusion and cross-diffusion plays an important role on the pattern formation of the predator-prey system.
CONTROL OF SPIRAL WAVES AND SPATIOTEMPORAL CHAOS WITH PERIODICAL SUBTHRESHOLD ORDERED WAVE PERTURBATIONS
Authors: YU LIANCHUN , ZHANG GUOYONG , MA JUN , CHEN YONG
Published: February 2009

In this paper, we investigate the possibility to control the spiral waves and spatiotemporal chaos in an excitable media by subthreshold ordered waves, which is by definition in this paper the spatially ordered periodical subthreshold fluctuations of system variables. It is found that both the spiral wave and the spatiotemporal chaos could be driven out of the control domain by perturbation of periodical subthreshold ordered waves. The effective control time declines as the amplitude of subthreshold ordered waves are increased, or their frequencies are decreased. Furthermore, we show that the effectiveness of this method is also dependent on the spatial arrangement of the subthreshold ordered waves. We discuss the possible applications of this method, especially in the control of heart fibrillation.
CLUSTER GEOMETRY AND EXTINCTION
Authors: WINDUS ALASTAIR L. , JENSEN HENRIK JELDTOFT
Published: February 2009

We introduce a simple lattice model for a population in which the individuals are capable of reproducing both bi- and uni-parentally with density-dependent rates proportional to the parameters pb and k, respectively. We examine the stochastic nature of the model as well as the different spatial structures that are formed when we change the relative rates of reproduction type. In particular, we see how these spatial structures can affect the probability of survival for the population. When the rate of bi-parental reproduction is much larger than that of uni-parental, large, dense clusters are more advantageous to the population, whereas sparse distributions give a greater chance of survival when the reverse is true. In addition, for a fixed pb, we find a cut-off value of k, separating these two preferable structures, where the survival probability is completely independent of the spatial structure.
WAVELET LOSSY COMPRESSION OF RANDOM DATA
Authors: ANDRECUT M.
Published: February 2009

A discrete wavelet multiresolution approach to the problem of lossy compression of random data is described. Also, numerical and analytical estimations of the compression rate and of the relative reconstruction error are given.