bluuebunny/crossref_metadata_2025 huggingface dataset:
Targeting Species-Specific Low-Affinity 16S rRNA Binding Sites by Using Peptide Nucleic Acids for Detection of Legionellae in Biofilms
Authors: Wilks Sandra A. , Keevil C. William
Published: August 2006

Using fluorescence in situ hybridization to detect bacterial groups has several inherent limitations. DNA probes are generally used, targeting sites on the 16S rRNA. However, much of the 16S rRNA is highly conserved, with variable regions often located in inaccessible areas where secondary structures can restrict probe access. Here, we describe the use of peptide nucleic acid (PNA) probes as a superior alternative to DNA probes, especially when used for environmental samples. A complex bacterial genus (
Legionella
) was studied, and two probes were designed, one to detect all species and one targeted to
Legionella pneumophila
. These probes were developed from existing sequences and are targeted to low-binding-affinity sites on the 16S rRNA. In total, 47 strains of
Legionella
were tested. In all cases, the
Legionella
spp. PNA probe labeled cells strongly but did not bind to any non-
Legionella
species. Likewise, the specific
L. pneumophila
PNA probe labeled only strains of
L. pneumophila
. By contrast, the equivalent DNA probes performed poorly. To assess the applicability of this method for use on environmental samples, drinking-water biofilms were spiked with a known concentration of
L. pneumophila
bacteria. Quantifications of the
L. pneumophila
bacteria were compared using PNA hybridization and standard culture methods. The culture method quantified only 10% of the number of
L. pneumophila
bacteria found by PNA hybridization. This illustrates the value of this method for use on complex environmental samples, especially where cells may be in a viable but noncultivable state.
Skin adnexal neoplasms—part 2: An approach to tumours of cutaneous sweat glands
Authors: Obaidat Nidal A , Alsaad Khaled O , Ghazarian Danny
Published: August 2006

Tumours of cutaneous sweat glands are uncommon, with a wide histological spectrum, complex classification and many different terms often used to describe the same tumour. Furthermore, many eccrine/apocrine lesions coexist within hamartomas or within lesions with composite/mixed differentiation. In addition to the eccrine and apocrine glands, two other skin sweat glands have recently been described: the apoeccrine and the mammary-like glands of the anogenital area. In this review (the second of two articles on skin adnexal neoplasms), common as well as important benign and malignant lesions of cutaneous sweat glands are described, and a summary for differentiating primary adnexal neoplasms from metastatic carcinoma is outlined, striving to maintain a common and acceptable terminology in this complex subject. Composite/mixed adnexal tumours are also discussed briefly.
Chunghyul-Dan (Qingxie-Dan) Improves Arterial Stiffness in Patients with Increased baPWV
Authors: Park Seong Uk , Jung Woo Sang , Moon Sang Kwan , Ko Chang Nam , Cho Ki Ho , Kim Young Suk , Bae Hyung Sup
Published: August 2006

Arterial stiffness is an important, independent determinant of cardiovascular risk. Pulse wave velocity (PWV) has been used as a valuable index of arterial stiffness and as a surrogate marker for atherosclerosis. Chunghyul-dan (CHD) has anti-hyperlipidemic activity, anti-inflammatory activity and anti-atherogenic effects. To determine its clinical effect on increased arterial stiffness, we examined whether CHD improves arterial stiffness in patients with increased brachial-ankle PWV (baPWV). Thirty-five subjects with increased baPWV (> 1400 cm/sec) were recruited and randomized to a treatment group (20 subjects) or a control group (15 subjects). The treatment group was administered CHD at a dose of 600 mg three times a day for 8 weeks, and the control group received no medication (observation only). baPWV was assessed using a pulse pressure analyzer at baseline and after 8 weeks. Blood pressure and serum lipid profile were monitored in the treatment group. Our results indicate that baPWV was lowered significantly in the treatment group after 8 weeks of medication ( p < 0.05), but not in the control group. Moreover, there were no significant changes in blood pressure and serum lipids profile except triglyceride level suggesting that the effect is largely independent of CHD's lipid-lowering effect or a blood pressure change. In conclusion, CHD appears to improve arterial stiffness in patients with increased PWV.
Effect of Resveratrol on NF-κB Activity in Rat Peritoneal Macrophages
Authors: Ma Zhen-Hua , Ma Qing-Yong , Wang Lian-Cai , Sha Huan-Chen , Wu Sheng-Li , Zhang Mei
Published: August 2006

This study was to investigate the inhibitive effect of resveratrol (RESV) on nuclear factor kappa B (NF-κB) expression and activity induced by lipopolysaccharide (LPS) in rat peritoneal macrophages (PMA). Male Sprague-Dawley (SD) rats were randomly divided into 7 groups, including control group, LPS group and RESV I-V group. In the LPS group, PMA were incubated in DMEM containing LPS (10 μg/ml), whereas in control group, PMA were incubated in DMEM only. In the RESV I-V groups, PMA were incubated in DMEM containing LPS (10 μg/ml) and different concentrations of RESV. After 24 hours of incubation, NF-κB activity in PMA, and the levels of tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1) and nitric oxide (NO) in the culture medium were measured. In the concentrations of 1.25-5 μg/ml, RESV had a dose- dependent inhibitive effect on NF-κB activity in PMA as well as the expressions of TNF-α, IL-1 and NO in the culture medium contrasted with the LPS group. There was no significant difference in the levels of these pro-inflammatory factors between the groups of 5 μg/ml and 10 μg/ml RESV. In conclusion, RESV has the potential for the future application of preventing inflammatory diseases involving PMA.
Rubus coreanusMiq. Extract Promotes Osteoblast Differentiation and Inhibits Bone-Resorbing Mediators in MC3T3-E1 Cells
Authors: Lee Kyung-Hee , Choi Eun-Mi
Published: August 2006

To prevent bone loss that occurs with increasing age, certain nutritional and pharmacological factors are needed. In the present study, the ethanol extract from the fruit of Rubus coreanus Miq. (RCE) was investigated for its effect on the function of osteoblastic MC3T3-E1 cells. RCE (10~50 μg/ml) caused a significant elevation in cell viability, alkaline phosphatase (ALP) activity, collagen content, and osteocalcin secretion in the cells. The effect of RCE (50 μg/ml) in increasing cell viability, ALP activity, and collagen content was prevented by the presence of 10-6M cycloheximide and 10-6M tamoxifen, suggesting that RCE's effect results from a newly synthesized protein component and might be partly involved in estrogen action. We then examined the effect of RCE on the H2O2-induced apoptosis and production of local factors in osteoblasts. Treatment with RCE (10~50 μg/ml) decreased the 0.2 mM H2O2-induced apoptosis and production of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and nitric oxide (NO) in osteoblasts. Our data indicate that the enhancement of osteoblast function by Rubus coreanus Miq. may result in the prevention of osteoporosis and inflammatory bone diseases.
Morin Promotes the Production of Th2 Cytokine by Modulating Bone Marrow-Derived Dendritic Cells
Authors: Li Chia-Yang , Suen Jau-Ling , Chiang Bor-Luen , Chao Pei-Dawn Lee , Fang Shih-Hua
Published: August 2006

Our previous studies had reported that morin decreased the interleukin-12 (IL-12) and tumor necrosis factor-alpha (TNF-α) production in lipopolysaccharide (LPS)-activated macrophages, suggesting that morin may promote helper T type 2 (Th2) response in vivo. Dendritic cells (DCs) are the most potent antigen presenting cells and known to play a major role in the differentiation of helper T type 1 (Th1) and Th2 responses. This study aimed to reveal whether morin is able to control the Th differentiation through modulating the maturation and functions of DCs. Bone marrow-derived dendritic cells (BM-DCs) were incubated with various concentrations of morin and their characteristics were studied. The results indicated that morin significantly affects the phenotype and cytokine expression of BM-DCs. Morin reduced the production of IL-12 and TNF-α in BM-DCs, in response to LPS stimulation. In addition, the proliferative response of stimulated alloreactive T cells was significantly decreased by morin in BM-DCs. Furthermore, allogeneic T cells secreted higher IL-4 and lower IFN-γ in response to morin in BM-DCs. In conclusion, these results suggested that morin favors Th2 cell differentiation through modulating the maturation and function of BM-DCs.
Antioxidant Properties of Glossogyne tenuifolia
Authors: Yang Joan-Hwa , Tsai Shu-Yao , Han Ching-Mei , Shih Chun-Chien , Mau Jeng-Leun
Published: August 2006

Glossogyne tenuifolia (Labill) Cass. (Compositae) is a special medicinal plant in the Pescadores Islands. Ethanolic, cold and hot water extracts were prepared from the dried herb and their antioxidant properties and components were studied. Ascorbic acid, α-tocopherol, butylated hydroxyanisole, citric and ethylenediaminetetraacetic acids were used in assays for comparison. With regard to EC50 values in antioxidant activity, ethanolic and hot water extracts (0.08 and 0.09 mg/ml) were much more effective than the cold water extract (0.76 mg/ml). At 1.0 mg/ml, reducing capacities were 1.57, 0.31 and 1.04 for ethanolic, cold water and hot water extracts, respectively. Scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl radicals were in descending order: ethanolic > cold water > hot water extracts. At 20 mg/ml, the hot water extract chelated all hydroxyl ions (100%) whereas the scavenging ability of the cold water extract was 68.86%. Chelating abilities on ferrous ions were in descending order: cold water > hot water > ethanolic extracts. Phenols were found to be the major antioxidant components. All EC50 values were below 20 mg/ml, and some even below 0.1 mg/ml, indicating that all three extracts from G. tenuifolia were rich in antioxidant properties.
JAZZ MELODY GENERATION USING RECURRENT NETWORKS AND REINFORCEMENT LEARNING
Authors: FRANKLIN JUDY A.
Published: August 2006

Recurrent (neural) networks have been deployed as models for learning musical processes, by computational scientists who study processes such as dynamic systems. Over time, more intricate music has been learned as the state of the art in recurrent networks improves. One particular recurrent network, the Long Short-Term Memory (LSTM) network shows promise for learning long songs, and generating new songs. We are experimenting with a module containing two inter-recurrent LSTM networks to cooperatively learn several human melodies, based on the songs' harmonic structures, and on the feedback inherent in the network. We show that these networks can learn to reproduce four human melodies. We then present as input new harmonizations, so as to generate new songs. We describe the reharmonizations, and show the new melodies that result. We also present a hierarchical structure for using reinforcement learning to choose LSTM modules during the course of melody generation.
LUMINESCENT AND TUNABLE 3D PHOTONIC CRYSTAL STRUCTURES
Authors: SUMMERS C. J. , GRAUGNARD E. , GAILLOT D. P. , KING J. S.
Published: August 2006

We report an investigation of luminescent and tunable photonic crystal structures formed by the infiltration and inversion of opal templates with high index and luminescent materials. Protocols are reported for the deposition of these materials and the properties of the resulting structures investigated by conventional structural and optical measurements. The properties of multi-layered and backfilled structures are reported and demonstrate the potential to modulate and statically tune the luminescence from photonic crystals.
DOPED POLY(METHYL METHACRYLATE) PHOTOPOLYMERS FOR HOLOGRAPHIC DATA STORAGE
Authors: LIN SHIUAN HUEI , LIN JUNE-HUA , CHEN PO-LIN , SHIAO YI-NAN , HSU KEN Y.
Published: August 2006

In this paper, we report our investigations on thick holographic recording material of the phenanthrenequinone doped poly(methyl methacrylate) (PQ:PMMA) photopolymer. The design strategy and fabrication technique for making thick polymer samples with negligible shrinkage and good optical quality are presented. The physical mechanism for holographic recording in PQ:PMMA material is described, and methods for improving are proposed. Based on these methods, photopolymer samples with different compositions are fabricated and experimentally characterized. The results show that by modifying compositions, the material sensitivity and dynamic range for volume holographic recording have been improved.
LITHIUM NIOBATE STEP-INDEX WAVEGUIDES FOR BROADBAND SECOND HARMONIC GENERATION
Authors: DE SANDE J. C. G. , STIVALA S. , GONZALO J. , ASSANTO G.
Published: August 2006

We investigate modal phase matching in lithium niobate step-index waveguides for second harmonic generation. We predict doubling bandwidths as large as 110 nm and show that temperature tuning can compensate for any deviation from the designed film thickness.
OPTICAL NONLINEARITY IN AZO-ANTHRAQUINONE DOPED LIQUID CRYSTALS
Authors: TRUSHKEVYCH OKSANA , COLLINGS NEIL , CROSSLAND WILLIAM A. , WILKINSON TIMOTHY D.
Published: August 2006

The optical nonlinearity in liquid crystals doped with 2,5 azo-substituted anthraquinone (ASAQ) dye is studied. Dynamic holographic grating formation is observed under conditions of low power laser light and no external fields. This new dye is an interesting alternative to methyl red (MR) dopant for liquid crystals (LCs) as materials for single-layer optically addressed spatial light modulators (OASLMs). The thickness and concentration dependence are explored in ASAQ-doped LCs. Stability and suitability for device applications are researched. In MR-doped LC systems the performance of the devices deteriorates quickly, while ASAQ devices are remarkably stable.
SYNTHESIS OF NOVEL CROSS-LINKED POLYURETHANE CONTAINING MODIFIED STILBENE AND SCHIFF BASE CHROMOPHORES FOR SECOND-ORDER NONLINEAR OPTICS
Authors: YE MINGXIN , XU LEI , JI LIYONG , LIU LIYING , WANG WENCHENG
Published: August 2006

The cyano and nitro groups were chosen as acceptor groups, and the substituent amino or ether groups as donor groups to the matrix. Polyurethane (PU) was modified by glycerol to increase the content of chromophore and to improve the stability of the nonlinearity. T g and T m were raised and solubility, film-forming ability and other physical properties were improved. The average functional groups of the reactant can be adjusted to ≥ 2 with polygroups and monogroups mixture. These poled polymers show high second-order optical nonlinearity and would have potential application in frequency-doubling or electro-optical controlling devices.
Prenatal betamethasone exposure results in pituitary-adrenal hyporesponsiveness in adult sheep
Authors: Sloboda Deborah M. , Moss Timothy J. M. , Li Shaofu , Doherty Dorota , Nitsos Ilias , Challis John R. G. , Newnham John P.
Published: August 2006

Fetal exposure to synthetic glucocorticoids in sheep results in increased fetal hypothalamic-pituitary-adrenal (HPA) activity persisting to one year of age. We aimed to determine the effects of single or repeated maternal or fetal betamethasone injections on offspring HPA activity at 2 and 3 yr of age and whether changes in adrenal mediators of steroidogenesis contribute to changes in pituitary-adrenal function. Pregnant ewes or their fetuses received either repeated intramuscular saline or betamethasone injections (0.5 mg/kg) at 104, 111, 118, and 124 days of gestation (dG) or a single betamethasone injection at 104 dG followed by saline at 111, 118, and 124 dG. Offspring were catheterized at 2 and 3 yr of age and given corticotrophin-releasing hormone + arginine vasopressin challenges. Adrenal tissue was collected for quantitative RT-PCR mRNA determination at 3.5 yr of age. In 2-yr-old offspring, maternal betamethasone injections did not alter basal ACTH or cortisol levels, but repeated injections elevated ACTH responses. At 3 yr of age, basal ACTH was elevated, and both basal and stimulated cortisol levels were suppressed by repeated maternal injections. Basal and stimulated cortisol-to-ACTH ratios and basal cortisol-to-cytochrome P-450 17α-hydroxylase (P450c17) mRNA ratios were suppressed by repeated injections. Repeated fetal betamethasone injections attenuated basal ACTH and cortisol levels in offspring at 2 but not 3 yr of age. Plasma changes were not associated with altered adrenal P450c17, ACTH receptor, β-hydroxysteroid dehydrogenase, or glucocorticoid receptor mRNA levels. These data suggest that maternal, but not fetal, betamethasone administration results in adrenal suppression in adulthood.
Microarray analysis of Akt1 activation in transgenic mouse hearts reveals transcript expression profiles associated with compensatory hypertrophy and failure
Authors: Schiekofer Stephan , Shiojima Ichiro , Sato Kaori , Galasso Gennaro , Oshima Yuichi , Walsh Kenneth
Published: August 2006

To investigate molecular mechanisms involved in the development of cardiac hypertrophy and heart failure, we developed a tetracycline-regulated transgenic system to conditionally switch a constitutively active form of the Akt1 protein kinase on or off in the adult heart. Short-term activation (2 wk) of Akt1 resulted in completely reversible hypertrophy with maintained contractility. In contrast, chronic Akt1 activation (6 wk) induced extensive cardiac hypertrophy, severe contractile dysfunction, and massive interstitial fibrosis. The focus of this study was to create a transcript expression profile of the heart as it undergoes reversible Akt1-mediated hypertrophy and during the transition from compensated hypertrophy to heart failure. Heart tissue was analyzed before transgene induction, 2 wk after transgene induction, 2 wk of transgene induction followed by 2 days of repression, 6 wk after transgene induction, and 6 wk of transgene induction followed by 2 wk of repression. Acute overexpression of Akt1 (2 wk) leads to changes in the expression of 826 transcripts relative to noninduced hearts, whereas chronic induction (6 wk) led to changes in the expression of 1,611, of which 65% represented transcripts that were regulated during the pathological phase of heart growth. Another set of genes identified was uniquely regulated during heart regression but not growth, indicating that nonoverlapping transcription programs participate in the processes of cardiac hypertrophy and atrophy. These data define the gene regulatory programs downstream of Akt that control heart size and contribute to the transition from compensatory hypertrophy to heart failure.
Global stability of Hopfield neural networks under dynamical thresholds with distributed delays
Authors: Zhang Fei-Yu , Huo Hai-Feng
Published: August 2006

We study the dynamical behavior of a class of Hopfield neural
networks with distributed delays under dynamical thresholds. Some
new criteria ensuring the existence, uniqueness, and global
asymptotic stability of equilibrium point are derived. In the
results, we do not require the activation functions to satisfy the
Lipschitz condition, and also not to be bounded, differentiable,
or monotone nondecreasing. Moreover, the symmetry of the
connection matrix is not also necessary. Thus, our results improve
some previous works in the literature. These conditions have great
importance in designs and applications of the global asymptotic
stability for Hopfield neural networks involving distributed
delays under dynamical thresholds.
Adaptive control of time‐invariant systems with discrete delays subject to multiestimation
Authors: De la Sen M. , Alonso S.
Published: August 2006

This paper deals with a robustly stable adaptive pole‐placement‐based controller for time‐delay linear systems with unknown point delays within known intervals of sufficiently small lengths under unmodeled dynamics and bounded disturbances. A multiestimation scheme is used to improve the identification error and then to deal with possible errors between the true basic delays compared to that used in the regressor of the adaptive scheme. Each estimation scheme possess a relative dead zone for each estimation scheme which freezes the adaptation for small sizes of the adaptation error compared with the estimated size of the contribution of the uncertainties to the filtered output. All the estimation schemes run in parallel but only that, which is currently in operation, parameterizes the adaptive controller to generate the plant input at each time. A supervisory scheme chooses in real time the appropriate estimator subject to a minimum residence time which is the tool to ensure closed‐loop stability under switching between the estimators in the estimation scheme. The dead zone adaptation mechanism prevents the closed‐loop system against potential instability caused by uncertainties.
On the new quantifiers and their use in multicriteria decision functions via ordered weighted aggregations
Authors: Chandramohan Aarthi , Rao M. V. C.
Published: August 2006

The goal of this paper is to present new and different quantifiers
for ordered weighted aggregation and illustrate their
applicability by a real‐life example. The role of these operators
in the formulation of multicriteria decision making functions,
using the concept of quantifier guided aggregation, is also
discussed.
Stability of limit cycle in a delayed model for tumor immune system competition with negative immune response
Authors: Yafia Radouane
Published: August 2006

This paper is devoted to the study of the stability of limit cycles of a system of nonlinear delay differential equations with a discrete delay. The system arises from a model of population dynamics describing the competition between tumor and immune system with negative immune response. We study the local asymptotic stability of the unique nontrivial equilibrium of the delay equation and we show that its stability can be lost through a Hopf bifurcation. We establish an explicit algorithm for determining the direction of the Hopf bifurcation and the stability or instability of the bifurcating branch of periodic solutions, using the methods presented by Diekmann et al.
Computation of the topological entropy in chaotic biophysical bursting models for excitable cells
Authors: Duarte Jorge , Silva Luís , Ramos J. Sousa
Published: August 2006

One of the interesting complex behaviors in many cell
membranes is bursting, in which a rapid oscillatory state
alternates with phases of relative quiescence. Although there is
an elegant interpretation of many experimental results in terms of
nonlinear dynamical systems, the dynamics of bursting
models is not completely described. In the present paper, we study
the dynamical behavior of two specific three‐variable models from
the literature that replicate chaotic bursting. With results from
symbolic dynamics, we characterize the topological entropy of
one‐dimensional maps that describe the salient dynamics on the
attractors. The analysis of the variation of this important
numerical invariant with the parameters of the systems allows us
to quantify the complexity of the phenomenon and to distinguish
different chaotic scenarios. This work provides an example of how
our understanding of physiological models can be enhanced by the
theory of dynamical systems.
A new view on one problem of asymptotic behavior of solutions of delay difference equations
Authors: Shaikhet L.
Published: August 2006

One known theorem on the asymptotic behavior of solution of linear delay difference equation is considered where a stability criterion is derived via a positive root of the corresponding characteristic equation. Two new directions for further investigation are proposed. The first direction is connected with a weakening of the known stability criterion; the second one is connected with consideration of negative and complex roots of the characteristic equation. A lot of pictures with stability regions and trajectories of considered processes are presented for visual demonstration of the proposed directions.
Universality and scaling in networks of period‐doubling maps with a pacemaker
Authors: Ivanova Anna S. , Kuznetsov Sergey P. , Osbaldestin Andrew H.
Published: August 2006

The networks of globally coupled maps with a pacemaker
have been introduced. We consider a generalization of
the Kaneko model with a pacemaker represented by a single
period‐doubling element coupled unidirectionally with a set of
other mutually coupled cells. We also investigate the
dynamics of a system of two unidirectionally coupled
elements, which manifests a special type of critical
behaviour, known as bicriticality, at the point of
simultaneous transition to chaos in both subsystems. With the help
of the renormalization group (RG), we show for a case of two
mutually coupled bicritical maps with a pacemaker that
there are two types of coupling: dissipative
and inertial. We investigate the dynamics of a network with a
pacemaker with two types of global coupling and the
properties of universality and scaling in this system.
Delay‐dependent asymptotic stability for neural networks with time‐varying delays
Authors: Liao Xiaofeng , Yang Xiaofan , Zhang Wei
Published: August 2006

We study the dynamical behavior of a class of neural network models with time‐varying delays. By constructing suitable Lyapunov functionals, we obtain sufficient delay‐dependent criteria to
ensure local and global asymptotic stability of the equilibrium of the neural network. Our results are applied to a two‐neuron system with delayed connections between neurons, and some novel asymptotic stability criteria are also derived. The obtained conditions are shown to be less conservative and restrictive than those reported in the known literature. Some numerical examples are included to demonstrate our results.
On the Navier‐Stokes equations with temperature‐dependent transport coefficients
Authors: Feireisl Eduard , Málek Josef
Published: August 2006

We establish long‐time and large‐data existence of a weak solution
to the problem describing three‐dimensional unsteady flows of an
incompressible fluid, where the viscosity and heat‐conductivity
coefficients vary with the temperature. The approach reposes on
considering the equation for the total energy rather than the
equation for the temperature. We consider the spatially periodic
problem.
Weak and strong convergence of finite family with errors of nonexpansive nonself-mappings
Authors: Plubtieng S , Ungchittrakool K
Published: August 2006

We are concerned with the study of a multistep iterative scheme with errors involving a finite family of nonexpansive nonself-mappings. We approximate the common fixed points of a finite family of nonexpansive nonself-mappings by weak and strong convergence of the scheme in a uniformly convex Banach space. Our results extend and improve some recent results, Shahzad (2005) and many others.
On the orbits of "Equation missing" -closure points of ultimately nonexpansive mappings
Authors: Kiang MoTak
Published: August 2006

Let "Equation missing" be a closed subset of a Banach space and "Equation missing" an ultimately nonexpansive commutative semigroup of continuous selfmappings. If the "Equation missing"-closure of "Equation missing" is nonempty, then the closure of the orbit of any "Equation missing"-closure point is a commutative topological group.
BOLD Noise Assumptions in fMRI
Authors: Wink Alle Meije , Roerdink Jos B. T. M.
Published: August 2006

This paper discusses the assumption of Gaussian noise in the
blood‐oxygenation‐dependent (BOLD) contrast for functional MRI
(fMRI). In principle, magnitudes in MRI images follow a Rice
distribution. We start by reviewing differences between Rician and
Gaussian noise. An analytic expression is derived for the null
(resting‐state) distribution of the difference between two Rician
distributed images. This distribution is shown to be symmetric,
and an exact expression for its standard deviation is derived.
This distribution can be well approximated by a Gaussian, with
very high precision for high SNR, and high precision for lower
SNR. Tests on simulated and real MR images show that subtracting
the time‐series mean in fMRI yields asymmetrically distributed
temporal noise. Subtracting a resting‐state time series from the
first results in symmetric and nearly Gaussian noise. This has
important consequences for fMRI analyses using standard
statistical tests.
Assessment of Left Ventricular Function in Cardiac MSCT Imaging by a 4D Hierarchical Surface‐Volume Matching Process
Authors: Garreau Mireille , Simon Antoine , Boulmier Dominique , Coatrieux Jean-Louis , Le Breton Hervé
Published: August 2006

Multislice computed tomography (MSCT) scanners offer new perspectives for cardiac kinetics evaluation with 4D dynamic sequences of high contrast and spatiotemporal resolutions. A new method is proposed for cardiac motion extraction in multislice CT. Based on a 4D hierarchical surface‐volume matching process, it provides the detection of the heart left cavities along the acquired sequence and the estimation of their 3D surface velocity fields. A Markov random field model is defined to find, according to topological descriptors, the best correspondences between a 3D mesh describing the left endocardium at one time and the 3D acquired volume at the following time. The global optimization of the correspondences is realized with a multiresolution process. Results obtained on simulated and real data show the capabilities to extract clinically relevant global and local motion parameters and highlight new perspectives in cardiac computed tomography imaging.
Unsupervised Detection of Suspicious Tissue Using Data Modeling and PCA
Authors: Abdel-Qader Ikhlas , Shen Lixin , Jacobs Christina , Abu Amara Fadi , Pashaie-Rad Sarah
Published: August 2006

Breast cancer is a major cause of death and morbidity among women all over the world, and it is a fact that early detection is a key in improving outcomes. Therefore development of algorithms that aids radiologists in identifying changes in breast tissue early on is essential. In this work an algorithm that investigates the use of principal components analysis (PCA) is developed to identify suspicious regions on mammograms. The algorithm employs linear structure and curvelinear modeling prior to PCA implementations. Evaluation of the algorithm is based on the percentage of correct classification, false positive (FP) and false negative (FN) in all experimental work using real data. Over 90% accuracy in block classification is achieved using mammograms from MIAS database.
A Newton‐type method and its application
Authors: Vijesh V. Antony , Subrahmanyam P. V.
Published: August 2006

We prove an existence and uniqueness theorem for solving the
operator equation F(x) + G(x) = 0, where F
is a continuous and
Gâteaux differentiable operator and the operator G
satisfies
Lipschitz condition on an open convex subset of a Banach space. As
corollaries, a recent theorem of Argyros (2003) and the classical
convergence theorem for modified Newton iterates are deduced. We
further obtain an existence theorem for a class of nonlinear
functional integral equations involving the Urysohn operator.
Dual Szegö pairs of sequences of rational matrix‐valued functions
Authors: Lasarow Andreas
Published: August 2006

We study certain sequences of rational matrix‐valued functions with poles outside the unit circle. These sequences are recursively constructed based on a sequence of complex numbers with norm less than one and a sequence of strictly contractive matrices. We present some basic facts on the rational matrix‐valued functions belonging to such kind of sequences and we will see that the validity of some Christoffel‐Darboux formulae is an essential property. Furthermore, we point out that the considered dual pairs consist of orthogonal systems. In fact, we get similar results as in the classical theory of Szegö′s orthogonal polynomials on the unit circle of the first and second kind.
On the 2‐orthogonal polynomials and the generalized birth and death processes
Authors: Ebtissem Zerouki , Ammar Boukhemis
Published: August 2006

We discuss the connections between the 2‐orthogonal polynomials and the generalized birth and death processes. Afterwards, we find the sufficient conditions to give an integral representation of the transition probabilities from these processes.
Some existence and uniqueness results for first‐order boundaryvalue problems for impulsive functional differential equationswith infinite delay in Fréchet spaces
Authors: Graef John R. , Ouahab Abdelghani
Published: August 2006

A recent nonlinear alternative for contraction maps in
Fréchet spaces due to Frigon and Granas is used to
investigate the existence and uniqueness of solutions to
first‐order boundary value problems for impulsive functional
differential equations with infinite delay. An example to
illustrate the results is included.
Multipliers and operators on the temperedultradistribution spaces of Roumieu type for thedistributional Hankel‐type transformation spaces
Authors: Banerji P. K. , Al-Omari S. K.
Published: August 2006

The tempered ultradistribution space of Roumieu type for the
space Hμ,ν is defined, which is a subspace of the
Hausdörff locally convex topological linear space. Further,
results are obtained for the multipliers and operators on the
tempered ultradistribution spaces for the distributional
Hankel‐type transformation spaces.
Some results on (δ‐pre, s)‐continuous functions
Authors: Kiliçman Adem , Salleh Zabidin
Published: August 2006

We study some properties of (δ‐pre, s)‐continuous
functions. Basic characterizations and several properties
concerning (δ‐pre, s)‐continuous functions are studied.
The general cases for the composition of functions under specific
conditions which yield (δ‐pre, s)‐continuous functions are also studied and we obtained some results.
Error estimates for scalar conservation laws by a kinetic approach
Authors: Omrane A.
Published: August 2006

We use the kinetic approach of Perthame and Tadmor
(1991) to calculate the error estimates for general
scalar conservation laws governing problems in gas dynamics or
fluid mechanics in general. The Kružkov and Kuznetsov
techniques are generalized to this method, and an error bound of
order (where ε is the mean free path) is obtained.
Dickson curves
Authors: Gomez-Calderon Javier
Published: August 2006

Let kq
denote the finite field of order q
and odd
characteristic p. For a ∈ kq, let gd(x, a)
denote the
Dickson polynomial of degree d
defined by . Let f(x)
denote a monic
polynomial with coefficients in kq. Assume that f2(x) − 4

is not a perfect square and gcd⁡(p, d) = 1. Also assume that
f(x)
and g2(f(x), 1)
are not of the form gd(h(x), c). In this note, we show that the polynomial gd(y, 1) − f(x) ∈ kq[x, y]
is absolutely irreducible.
Measure of noncompactness of operators and matrices on the spaces c and c0
Authors: De Malafosse Bruno , Malkowsky Eberhard , Rakocevic Vladimir
Published: August 2006

In this note, using the Hausdorff measure of noncompactness,
necessary and sufficient conditions are formulated for a linear
operator and matrices between the spaces c and c0 to be compact. Among other things, some results of Cohen and Dunford are
recovered.
Three‐dimensional fluctuating Couette flow through the porous plates with heat transfer
Authors: Guria M. , Jana R. N.
Published: August 2006

Unsteady Couette flow of a viscous incompressible fluid between two horizontal porous flat plates is considered. The stationary plate is subjected to a periodic suction and the plate in uniform motion is subjected to uniform injection. Approximate solutions have been obtained for the velocity and the temperature fields, skin friction by using perturbation technique. The heat transfer characteristic has also been studied on taking viscous dissipation into account. It is found that the main flow velocity decreases with increase in frequency parameter. On the other hand, the magnitude of the cross‐flow velocity increases with increase in frequency parameter. It is seen that the amplitude of the shear stress due to main flow decreases while that due to cross‐flow increases with increase in frequency parameter. It is also seen that the tangent of phase shifts both due to the main and cross‐flows decrease with increase in frequency parameter. It is observed that the temperature increases with increase in frequency parameter.
Cauchy′s functional equation in restricted complex domains
Authors: Pimsert Watcharapon , Laohakosol Vichian , Pianskool Sajee
Published: August 2006

Using a method modified from that used by Pisot and Schoenberg in 1964‐1965, a Cauchy′s functional equation with restricted domains in the complex field is solved for uniformly continuous solutions.
Maximal regular boundary value problems in Banach‐valuedfunction spaces and applications
Authors: Shakhmurov Veli B.
Published: August 2006

The nonlocal boundary value problems for differential operator
equations of second order with dependent coefficients are studied.
The principal parts of the differential operators generated by
these problems are non‐selfadjoint. Several conditions for the
maximal regularity and the Fredholmness in Banach‐valued
Lp‐spaces of these problems are given. By using these
results, the maximal regularity of parabolic nonlocal initial
boundary value problems is shown. In applications, the nonlocal
boundary value problems for quasi elliptic partial differential
equations, nonlocal initial boundary value problems for parabolic
equations, and their systems on cylindrical domain are
studied.
Inverted opal luminescent Ce‐doped silica glasses
Authors: Scotti R. , Canevali C. , Polizzi S. , Bettinelli M. , Speghini A. , Morazzoni F.
Published: August 2006

Inverted opal Ce‐doped silica glasses (Ce  :  Si molar ratio 1  ·  10−3 were prepared by a sol‐gel method using opals of latex microspheres as templates. The rare earth is homogeneously dispersed in silica host matrix, as evidenced by the absence of segregated CeO2, instead present in monolithic Ce‐doped SG with the same cerium content. This suggests that the nanometric dimensions of bridges and junctions of the host matrix in the inverted opal structures favor the RE distribution avoiding the possible segregation of CeO2.
Solution‐grown method of CdS film by ultrasonical colloid chemistry deposition technique
Authors: Cui Hai-Ning , Costa Manuel F. , Teixeira V. , Zhang Jun
Published: August 2006

A technique called ultrasonical colloid chemistry deposition (UCCD) has been used to produce bar‐shaped ultrafine particles (UFP) cadmium sulphide films. UV‐visible spectra and electron micrographic characterization results are presented and discussed. The thin films were analyzed by means of grazing incidence X‐ray diffraction (GIXD) and X‐ray diffraction (XRD). Detailed results about the amorphous characterization of the films during room temperature growth and post annealing are given.
Regio‐ and stereoselectivity in the Paternò‐Büchi reaction on furan derivatives
Authors: D′Auria Maurizio , Emanuele Lucia , Racioppi Rocco
Published: August 2006

The photochemical coupling reaction between 2,3‐dihydrofuran and benzaldehyde was studied by using DFT/B3LYP/6 − 31G + (d, p) method. The regiocontrol of the attack of the benzaldehyde on the double bond is related to the different stabilities of the biradical intermediates. The endo stereoselectivity of the reaction depends on the superposition between HSOMO and LSOMO in the biradical intermediate. In the photochemical reaction between furan and benzaldehyde also the regiocontrol depends on the relative stability of the possible biradical intermediates. The exo stereoselectivity of the coupling reaction depends on the superposition between the HSOMO and LSOMO of the biradical intermediate. The reaction of chiral phenylglyoxylates with furan gave the corresponding adducts with de = 15–95%. The stereocontrol can be explained considering the energy gap between the biradical intermediates in the coupling reaction. When the reaction was performed in the presence of zeolite, the diastereoisomeric excess increased. The reaction of benzoin and 2‐phenylpropiophenone with furan gave the cycloadduct with high diastereocontrol. All the products were obtained with de > 98%. The Paterrnò‐Büchi reaction between 2‐furylmethanols with aromatic carbonyl compounds also showed high regio‐ and stereocontrol. On the contrary, when 5‐methyl derivatives were used, a lack of regiocontrol was observed. Furthermore, with aliphatic carbonyl compounds, no diastereoselectivity was observed. These results were explained assuming the attack of the excited carbonyl compound on the same side as the hydroxyl group, through the formation of a hydrogen bond or of a complex. This type of attack gave the biradical intermediate in preferential conformations. The relative energies of these conformers account for the observed diastereoselectivity.
On the linearized stability of age‐structured multispecies populations
Authors: Farkas Jozsef Z.
Published: August 2006

We consider a general nonlinear age‐structured population model with n interacting species. We deduce the characteristic function in the form of a determinant of an n‐by‐n matrix. Then we formulate some biologically meaningful sufficient conditions for the stability (resp., instability) of positive stationary solutions of the system.
Martingale measures in the market with restricted information
Authors: Jianqi Yang , Haifeng Yan , Limin Liu
Published: August 2006

This paper considers the problem of the market with restricted
information. By constructing a restricted information market
model, the explicit relation of arbitrage and the minimal
martingale measure between two different information markets
are discussed. Also a link among all equivalent
martingale measures under restricted information market is given.
Abstract semilinear stochastic Itó‐Volterraintegrodifferential equations
Authors: Keck David N. , McKibben Mark A.
Published: August 2006

We consider a class of abstract semilinear stochastic Volterra
integrodifferential equations in a real separable Hilbert space.
The global existence and uniqueness of a mild solution, as well as
a perturbation result, are established under the so‐called
Caratheodory growth conditions on the nonlinearities. An
approximation result is then established, followed by an analogous
result concerning a so‐called McKean‐Vlasov integrodifferential
equation, and then a brief commentary on the extension of the main
results to the time‐dependent case. The paper ends with a
discussion of some concrete examples to illustrate the abstract
theory.
Euler‐Maruyama approximations in mean‐revertingstochastic volatility model under regime‐switching
Authors: Mao Xuerong , Truman Aubrey , Yuan Chenggui
Published: August 2006

Stochastic differential equations (SDEs) under regime‐switching
have recently been developed to model various financial
quantities. In general, SDEs under regime‐switching have no
explicit solutions, so numerical methods for approximations have
become one of the powerful techniques in the valuation of
financial quantities. In this paper, we will concentrate on the
Euler‐Maruyama (EM) scheme for the typical hybrid mean‐reverting
θ‐process. To overcome the mathematical difficulties
arising from the regime‐switching as well as the non‐Lipschitz
coefficients, several new techniques have been developed in this
paper which should prove to be very useful in the numerical
analysis of stochastic systems.
Attractivity of nonlinear impulsive delay differentialequations
Authors: Yang Zhichun , Xu Daoyi
Published: August 2006

The attractivity of nonlinear differential equations with time
delays and impulsive effects is discussed. We obtain some criteria
to determine the attracting set and attracting basin of the
impulsive delay system by developing an impulsive delay
differential inequality and introducing the concept of nonlinear
measure. Examples and their simulations illustrate the
effectiveness of the results and different asymptotical behaviors
between the impulsive system and the corresponding continuous
system.
Ni Hollow Nanospheres: Preparation and Catalytic Activity
Authors: Zhong Kaifu , Jin Pu , Chen Qianwang
Published: August 2006

A method to prepare monodispersed silica nanospheres as templates
for fabrication of nickel‐silica composite hollow spheres is
presented. The structures for both silica nanospheres and
nickel‐silica composite hollow spheres were characterized by X‐ray
diffraction (XRD), transmission electron microscopy (TEM), and
scanning electron microscopy (SEM). The catalytic activity for
acetone hydrogenation on nickel‐silica composite hollow spheres
was evaluated, and high conversion efficiency of 70% with good
selectivity of 82.7% to 2‐propanol was observed. The mechanism
of high catalytic activity and good selectivity in acetone
hydrogenation reaction was discussed.
Synthesis and Characterization of Nanocrystalline YSZ Powder by Smoldering Combustion Synthesis
Authors: Kaus Ingeborg , Dahl Paul Inge , Mastin Johann , Grande Tor , Einarsrud Mari-Ann
Published: August 2006

Nanocrystalline yttria‐stabilized zirconia (YSZ) powders with
8 mol% Y2O3 have been produced using
smoldering combustion synthesis with glycine as fuel and nitrate
as oxidizer. The YSZ powders prepared by using different glycine
to nitrate ratios (0.20–1.0) have been characterized by X‐ray
diffraction (crystallite size), thermogravimetry, infrared
spectroscopy, surface area analysis, transmission electron
microscopy, and dilatometry to determine the parameters giving the
powder the best properties when it comes to densification
properties. The influence of calcination temperature on
crystallite size, surface area, and carbonate species remaining
from the smoldering combustion reaction has been studied
especially for the G/N ratio of 0.23 to reveal the
optimal synthesis conditions. A G/N ratio of 0.23 and
calcination in the range 650–900ºC in oxygen flow gave
high quality powder with a crystallite size less than 10 nm.
Densities of sintered bodies exhibit an increase for calcination
temperatures above 600ºC, where most of the residual
carbonate species has been removed.
Is the Association Between TNF‐α‐308 A Allele and DMT1 Independent of HLA‐DRB1, DQB1 Alleles?
Authors: Deja Grazyna , Jarosz-Chobot Przemyslawa , Polanska Joanna , Siekiera Urszula , Malecka-Tendera Ewa
Published: August 2006

The aim of the study was to assess chosen factors of genetic
susceptibility to DMT1: DRB1, DQB1, and TNF‐α
polymorphisms‐308 (G/A) in children with DMT1 and their up‐to‐now
healthy siblings. Then we tested whether the association between
TNF‐α genes and DMT1 is independent of HLA. 87 diabetic
children, their 78 siblings, and 85 persons from healthy control
group were followed up. The highest risk of DMT1 was connected
with alleles: DRB1*0401 (OR = 3.39; CI: 1.55–7.41),
DRB1*0301 (OR = 2.72; CI: 1.48–5.01), DQB1*0201 (OR =
4.04; CI: 2.17–7.52), DQB1*0302 (OR = 5.08; CI: 2.54–10.14), and TNF‐α‐308 A allele (OR = 2.59; CI: 1.23–5.44). Moreover linkage disequilibrium for TNF‐α‐308 A allele with DRB1*0301 and DQB1*0201 was observed in both diabetic children and their siblings. Diabetic children and
their siblings present similar genetic risk factors for DMT1. The association between TNF‐α‐308 A allele and DMT1 is dependent of HLA‐DRB1 and DQB1 alleles.