bluuebunny/crossref_metadata_2025 huggingface dataset:
THICKNESS DEPENDENCE OF THE COERCIVE FIELD IN FERROELECTRIC THIN FILMS
Authors: HU ZHAN-NING , LO V. C.
Published: September 2006

By considering the effects of the space charges and domain boundaries in ferroelectric thin films, the thickness dependence of coercive field (Ec) is numerically simulated based on the four-state Potts model with the nearest-neighbor interactions between dipole moments. For large thickness, experimental results where Ec decreases with thickness can be produced from our Monte-Carlo simulation. On the other hand, when the thickness is very small, our simulation gets that Ec increases with thickness by the study of the polarization switching in the film. This gives an explanation of the experimental result by Zhu et al. in J. Appl. Phys.83, 1 (1998) for SBT-BTN film, and a similar report by Bune et al. in Nature391, 874 (1998) for the crystalline film. The critical temperature of the thin film is also discussed.
EFFECTIVE PHOTON EXCHANGE CORRELATIONS IN FERROELECTRICS
Authors: KOO JE HUAN , CHO GUANGSUP , KIM JONG-JEAN
Published: September 2006

We propose a photon correlation theory for ferroelectrics especially focused on KDP-type where we consider a photon field from its constituent electrons and ions. We derive a Curie–Weiss type dielectric susceptibility from the microscopic Hamiltonian and we obtain the ferroelectric transition temperature, Tc. We calculate the free energy by applying the bosonic operator formalism to the Hamiltonian. A linear temperature-dependent specific heat Cvconforming with experimental data for some ferroelectric materials is obtained. We calculate the isotope exponent, α, on Tc. We also derive phonon dispersion relations in the presence of electron-phonon interactions to show soft modes at Tc.
BAND COLLAPSE AND THE QUANTUM HALL EFFECT IN GRAPHENE
Authors: ANDREI BERNEVIG B. , HUGHES TAYLOR L. , ZHANG SHOU-CHENG , CHEN HAN-DONG , WU CONGJUN
Published: September 2006

The recent quantum Hall experiments in graphene have confirmed the theoretically well-understood picture of the quantum Hall (QH) conductance in fermion systems with continuum Dirac spectrum. In this paper we take into account the lattice and perform an exact diagonalization of the Landau problem on the hexagonal lattice. At very large magnetic fields the Dirac argument fails completely and the Hall conductance, given by the number of edge states present in the gaps of the spectrum, is dominated by lattice effects. As the field is lowered, the experimentally observed situation is recovered through a phenomenon which we call band collapse. As a corollary, for low magnetic fields, graphene will exhibit two qualitatively different QHE's: at low filling, the QHE will be dominated by the "relativistic" Dirac spectrum and the Hall conductance will be odd-integer; above a certain filling, the QHE will be dominated by a non-relativistic spectrum, and the Hall conductance will span all integers, even and odd.
A BRIEF ANALYSIS OF MAY 2004 CRASH IN THE INDIAN MARKET
Authors: GIORDANO MATTEO , MANNELLA RICCARDO
Published: September 2006

Following the victory of the Congress Party, the Indian SENSEX index crashed in May 2004. We present a brief analysis of the crash, showing that very likely the crash was due to the outcome of the Indian elections, but in a situation of very high instability, with the market already past a transition point, well described by the Sornette-Johansen model.
Pathobiology of Neutrophil Transepithelial Migration: Implications in Mediating Epithelial Injury
Authors: Chin Alex C. , Parkos Charles A.
Published: September 2006

Neutrophil (also known as polymorphonuclear leukocyte, or PMN) transepithelial migration and accumulation at mucosal surfaces is a hallmark of many inflammatory conditions. This process correlates directly with clinical disease activity and epithelial injury. Currently, the mechanisms that define PMN epithelial interactions during an inflammatory response are not completely understood. This review provides an overview of the consequences of PMN infiltration into epithelial tissues and highlights molecular details of PMN epithelial interactions during transmigration. A better understanding of this process will likely provide new insights into developing organ-specific treatment strategies to reduce the deleterious consequences of epithelial inflammation.
Carotid artery intima-media thickness is associated with insulin-mediated glucose disposal in nondiabetic normotensive offspring of type 2 diabetic patients
Authors: Cardellini Marina , Marini Maria Adelaide , Frontoni Simona , Hribal Marta Letizia , Andreozzi Francesco , Perticone Francesco , Federici Massimo , Lauro Davide , Sesti Giorgio
Published: September 2006

The aim of this study was to investigate whether insulin resistance is independently associated with early manifestations of atherosclerosis. To this end, 176 normotensive offspring of type 2 diabetic patients were subjected to euglycemic hyperinsulinemic clamp to assess insulin sensitivity. Early atherosclerosis was studied by ultrasonography of the common carotid artery. Of the total 176 subjects, 145 were glucose tolerant, 18 had impaired fasting glucose, and 13 had impaired glucose tolerance. Univariate correlations showed that age, body mass index, waist, blood pressure, 2-h postchallenge glucose, fasting insulin, triglycerides, interleukin-6, fibrinogen, and white blood cell count were significantly correlated with carotid intima-media thickness (IMT), whereas HDL cholesterol and glucose disposal showed a negative correlation. A stepwise multivariate regression analysis including sex, age, waist circumference, smoking status, systolic blood pressure, diastolic blood pressure, triglyceride, HDL cholesterol, 2-h postchallenge glucose, plasma IL-6, fibrinogen, white blood cell count, insulin-stimulated glucose disposal, and fasting insulin showed that the four variables that remained significantly associated with carotid IMT were waist circumference, insulin-stimulated glucose disposal, white blood cell count, and diastolic blood pressure, accounting for 33.7% of its variation. These findings support the concept that insulin sensitivity, rather than plasma insulin levels, is associated with early atherosclerosis in nondiabetic normotensive offspring of type 2 diabetic patients.
Association of hormonal dysregulation with metabolic syndrome in older women: data from the InCHIANTI study
Authors: Maggio Marcello , Lauretani Fulvio , Ceda Gian Paolo , Bandinelli Stefania , Basaria Shehzad , Paolisso Giuseppe , Ble Alessandro , Egan Josephine M. , Metter E. Jeffrey , Abbatecola Angela M. , Zuliani Giovanni , Ruggiero Carmelinda , Valenti Giorgio , Guralnik Jack M. , Ferrucci Luigi
Published: September 2006

Metabolic syndrome (MetS) is a strong risk factor for type 2 diabetes and cardiovascular disease. Conditions associated with hyperandrogenism are often associated with glucose intolerance and other features of MetS in young women. As the prevalence of MetS increases with age and is probably multifactorial, it is reasonable to hypothesize that age-related changes in androgens and other hormones might contribute to the development of MetS in older persons. However, this hypothesis has never been tested in older women. We hypothesized that high levels of testosterone, dehydroepiandrosterone sulfate (DHEA-S), and cortisol and low levels of sex hormone-binding globulin (SHBG) and IGF-I would be associated with MetS in a representative cohort of older Italian women independently of confounders (including inflammatory markers). After exclusion of participants on hormone replacement therapy and those with a history of bilateral oophorectomy, 512 women (≥65 yr) had complete data on testosterone, cortisol, DHEA-S, SHBG, fasting insulin, total and free IGF-I, IL-6, and C-reactive protein (CRP). MetS was defined according to ATP-III criteria. Insulin resistance was calculated according to HOMA. MetS was found in 145 women (28.3%). Participants with vs. those without MetS had higher age-adjusted levels of bioavailable testosterone ( P < 0.001), IL-6 ( P < 0.001), CRP ( P < 0.001), and HOMA ( P < 0.001) and lower levels of SHBG ( P < 0.001). After adjustment for potential confounders, participants with decreased SHBG had an increased risk of MetS ( P < 0.0001) vs. those with low SHBG. In a further model including all hormones and confounders, log SHBG was the only independent factor associated with MetS (OR: 0.44, 95% CI 0.21–0.91, P = 0.027). In older women, SHBG is negatively associated with MetS independently of confounders, including inflammatory markers and insulin resistance. Further studies are needed to support the notion that raising SHBG is a potential therapeutic target for prevention and treatment of MetS.
Renal upregulation of HO-1 reduces albumin-driven MCP-1 production: implications for chronic kidney disease
Authors: Murali Narayana S. , Ackerman Allan W. , Croatt Anthony J. , Cheng Jingfei , Grande Joseph P. , Sutor Shari L. , Bram Richard J. , Bren Gary D. , Badley Andrew D. , Alam Jawed , Nath Karl A.
Published: September 2006

Proteinuria contributes to chronic kidney disease by stimulating renal tubular epithelial cells to produce cytokines such as monocyte chemoattractant protein-1 (MCP-1). The present study determined whether cellular overexpression of heme oxygenase-1 (HO-1) can influence albumin-stimulated MCP-1 production. In response to bovine serum albumin, NRK-52E cells constitutively overexpressing HO-1 (HO-1 OE cells) exhibit less induction of MCP-1 mRNA and less production of MCP-1 protein compared with similarly treated, control NRK-52E cells (CON cells). In wild-type NRK-52E cells, and under these conditions, we demonstrate that the induction of MCP-1 is critically dependent on intact NF-κB binding sites in the MCP-1 promoter. In response to albumin, CON cells exhibit activation of NF-κB, and this is reduced in HO-1 OE cells. Albumin also activates ERK1/2 and increases ERK activity, both of which are exaggerated in HO-1 OE cells. Studies with an inhibitor of MAPK/ERK kinase (U0126) demonstrate that the inhibitory effects of U0126 on MCP-1 production are attenuated in HO-1 OE cells. We conclude that HO-1 overexpression in the proximal tubule reduces MCP-1 production in response to albumin, and this occurs, at least in part, by inhibiting an ERK-dependent, NF-κB-dependent pathway at a site that is distal to the activation of ERK. These findings suggest that the induction of HO-1 in the proximal tubule, as occurs in chronic kidney disease, may be a countervailing response that reduces albumin-stimulated production of cytokines such as MCP-1.
Calcium-Activated Afterhyperpolarizations Regulate Synchronization and Timing of Epileptiform Bursts in Hippocampal CA3 Pyramidal Neurons
Authors: de Sevilla David Fernández , Garduño Julieta , Galván Emilio , Buño Washington
Published: September 2006

Calcium-activated potassium conductances regulate neuronal excitability, but their role in epileptogenesis remains elusive. We investigated in rat CA3 pyramidal neurons the contribution of the Ca2+-activated K+-mediated afterhyperpolarizations (AHPs) in the genesis and regulation of epileptiform activity induced in vitro by 4-aminopyridine (4-AP) in Mg2+-free Ringer. Recurring spike bursts terminated by prolonged AHPs were generated. Burst synchronization between CA3 pyramidal neurons in paired recordings typified this interictal-like activity. A downregulation of the medium afterhyperpolarization (mAHP) paralleled the emergence of the interictal-like activity. When the mAHP was reduced or enhanced by apamin and EBIO bursts induced by 4-AP were increased or blocked, respectively. Inhibition of the slow afterhyperpolarization (sAHP) with carbachol, t-ACPD, or isoproterenol increased bursting frequency and disrupted burst regularity and synchronization between pyramidal neuron pairs. In contrast, enhancing the sAHP by intracellular dialysis with KMeSO4 reduced burst frequency. Block of GABAA–B inhibitions did not modify the abnormal activity. We describe novel cellular mechanisms where 1) the inhibition of the mAHP plays an essential role in the genesis and regulation of the bursting activity by reducing negative feedback, 2) the sAHP sets the interburst interval by decreasing excitability, and 3) bursting was synchronized by excitatory synaptic interactions that increased in advance and during bursts and decreased throughout the subsequent sAHP. These cellular mechanisms are active in the CA3 region, where epileptiform activity is initiated, and cooperatively regulate the timing of the synchronized rhythmic interictal-like network activity.
Large-Scale Organization of Preferred Directions in the Motor Cortex. I. Motor Cortical Hyperacuity for Forward Reaching
Authors: Naselaris Thomas , Merchant Hugo , Amirikian Bagrat , Georgopoulos Apostolos P.
Published: September 2006

We used statistical methods for spherical density estimation to evaluate the distribution of preferred directions of motor cortical cells recorded from monkeys making reaching movements in 3D space. We found that this distribution, although broad enough to represent the entire 3D continuum of reaching directions, exhibited an enrichment for reaching forward from the body and, to a lesser degree, for reaching backward toward the body. The distribution of preferred directions of cells in the motor cortex may have important implications for motor cortical function and for the decoding of arm trajectories from population activity.
Neurosteroids Involved in Regulating Inhibition in the Inferior Colliculus
Authors: Saalmann Yuri B. , Morgan Ian G. , Calford Mike B.
Published: September 2006

Fast inhibitory neurotransmission in the brain is largely mediated by the γ-aminobutyric acid-type A (GABAA) receptor. The 3α,5α-reduced neurosteroids (e.g., allopregnanolone) are the most potent endogenous modulators of the GABAA receptor. Although it is known that 3α,5α-reduced neurosteroid levels change during stress or depression and over the estrus cycle, a basic physiological role consistent with their pharmacological action remains elusive. We used the unique architecture of the auditory midbrain to reveal a role for 3α,5α-reduced neurosteroids in regulating inhibitory efficacy. After blocking the massive GABAergic projection from the dorsal nucleus of the lateral lemniscus (DNLL) to the contralateral central nucleus of the inferior colliculus (ICC) in anesthetized rats, a reactive increase in the efficacy of other inhibitory circuits in the ICC (separable because of the dominant ear that drives each circuit) was demonstrated with physiological measures—single-neuron activity and a neural-population-evoked response. This effect was prevented by blocking 3α,5α-reduced neurosteroid synthesis with a 5α-reductase inhibitor: finasteride. Immunohistochemistry confirmed that the DNLL blockade induced an increase in 3α,5α-reduced neurosteroids in the contralateral ICC. This study shows that when GABAergic inhibition is reduced, the brain compensates within minutes by locally increasing synthesis of neurosteroids, thereby balancing excitatory and inhibitory inputs in complex neural circuits.
Design and Synthesis of Redox‐Switched Lariat Ethers and Their Application for Transport of Alkali and Alkaline‐Earth Metal Cations Across Supported Liquid Membrane
Authors: Awasthy Anubhuti , Bhatnagar Mamta , Tomar Jyoti , Sharma Uma
Published: September 2006

A new class of redox‐switched anthraquinone derived lariat ethers
1‐(1‐anthraquinonyloxy) 3, 6, 9 trioxaundecane 11‐ol
(M1), 1‐(1‐anthraquinonyloxy) 3, 6 dioxaoctane 9‐ol
(M2), 1‐(1‐anthraquinonyloxy) 3 oxapentane 5‐ol
(M3), 1‐(1‐anthraquinonyloxy) 3 oxapentane 5‐butane
(M4), 1‐(1‐anthraquinonyloxy) 3, 6 dioxaoctane 9‐methane
(M5) and 1‐(1‐anthraquinonyloxy) 3 oxapentane 5‐methane
(M6) have been synthesized and characterized by spectral
analysis. These ionophores were used in liquid membrane carrier
facilitated transport of main group metal cations across supported
liquid membrane (SLM). Cellulose nitrate membrane was used as
membrane support. Effect of various parameters such as variation
in concentration of metal as well as ionophore, effect of chain
length and end group of ionophore have been studied. The sequence
of metal ions transported by ionophore M1 is
Na+ > Li+ > K+ > Ca2+ > Mg2+
and the order of metal ions transported by ionophores
(M2–M6) is
Li+ > Na+ > K+ > Ca2+ > Mg2+.
Ionophore M1 is selective for Na+,
Li+, and K+ and ionophores
(M2–M6) are selective for Li+ and
Na+.
One‐dimensional and two‐dimensional dynamics of cubic maps
Authors: Ilhem Djellit , Amel Kara
Published: September 2006

We concentrate on the dynamics of one‐dimensional and two‐dimensional cubic maps, it describes how complex behaviors can possibly arise as a system parameter changes. This is a large class of diffeomorphisms which provide a good starting point for understanding polynomial diffeomorphisms with constant Jacobian and equivalent to a composition of generalized Hénon maps. Due to the theoretical and practical difficulties involved in the study, computers will presumably play a role in such efforts.
Global attractivity of positive periodic solutions for an impulsive delay periodic “food limited” population model
Authors: Song Jian
Published: September 2006

We will consider the following nonlinear impulsive delay
differential equation N′(t) = r(t)N(t)((K(t) − N(t − mw))/(K(t) + λ(t)N(t − mw))), a.e. t > 0, t ≠ tk, , K = 1, 2, …, where m is a positive integer, r(t), K(t), λ(t) are positive periodic functions of periodic ω. In the nondelay case (m = 0), we show that the above equation has a unique positive periodic solution N*(t) which is globally asymptotically stable. In the delay case, we present sufficient
conditions for the global attractivity of N*(t). Our results imply that under the appropriate periodic impulsive perturbations, the impulsive delay equation preserves the original periodic property of the nonimpulsive delay equation. In particular, our work extends and improves some known results.
Rational expectations and the Cournot‐Theocharis problem
Authors: Puu Tönu
Published: September 2006

In dynamic models in economics, often “rational expectations” are
assumed. These are meant to show that the agents can correctly foresee the result of their own and the other agents′ actions. In this paper, it is shown that this cannot happen in a simple oligopoly model with a linear demand function and constant marginal costs. “Naive expectations,” that is, where each agent assumes the other agents to retain their previous period action, are shown to result in a 2‐period cycle. However, adapting to the observed periodicity always doubles the actual resulting periodicity. In general, it is impossible for the agents to learn any periodicity except
the trivial case of a fixed point. This makes the whole idea of “rational expectations” untenable in Cournot oligopoly models.
Weighted power mean discrete dynamical systems: Fast convergence properties
Authors: Solis Francisco J.
Published: September 2006

We studied families of discrete dynamical systems obtained by using iteration functions given by weighted power mean in order to understand the role of hyperrapid convergence in nonlinear maps. Our interest resides in concepts related to the velocity of convergence. We introduce new concepts regarding the time of convergence and we provide an ordering of these families according to their dependence on parameters.
Constructing chaotic transformations with closed functional forms
Authors: Huang Weihong
Published: September 2006

The properties of complete chaotic unimodal transformations with closed
functional forms are examined and the necessary and sufficient conditions are
provided to construct such transformations. Theoretical findings are verified
with computer simulations.
Novel, useful, and effective definitions for fuzzy linguistic hedges
Authors: Chandramohan Aarthi , Rao M. V. C.
Published: September 2006

The main emphasis of this paper is on fuzzy linguistic hedging, used to modify membership functions. This paper investigates the issues of obtaining new definitions for hedges which exceed the traditional definitions given by Zadeh (and others), particularly seeing that the effect of applying these hedges does not cross beyond the reasonable limits of membership values [0, 1] and is still meaningful from the point of view of magnitude of membership value and hence be really effective for an application. Some of the most commonly used hedges are presented, these hedges are very, positively, negatively, slightly more, and slightly less. The effects of these hedges on numeric examples are charted.
Equivalence between subshrubs and chaotic bands in the Mandelbrot set
Authors: Pastor G. , Romera M. , Alvarez G. , Arroyo D. , Montoya F.
Published: September 2006

We study in depth the equivalence between subshrubs and chaotic
bands in the Mandelbrot set. In order to do so, we introduce the
rules for chaotic bands and the rules for subshrubs, as well as
the transformation rules that allow us to interchange them. From
all the denominations of a chaotic band, we show the canonical
form; that is, the one associated to the hyperbolic component that
generates such a chaotic band. Starting from the study of the
one‐dimensional route, we fulfil an inductive study that gives a
generalization of the shrub concept.
Merging of degree and index theory
Authors: Väth Martin
Published: September 2006

The topological approaches to find solutions of a coincidence equation "Equation missing" can roughly be divided into degree and index theories. We describe how these methods can be combined. We are led to a concept of an extended degree theory for function triples which turns out to be natural in many respects. In particular, this approach is useful to find solutions of inclusion problems "Equation missing". As a side result, we obtain a necessary condition for a compact AR to be a topological group.
Intervention Models in Functional Connectivity Identification Applied to fMRI
Authors: Sato João Ricardo , Takahashi Daniel Yasumasa , Cardoso Ellison Fernando , Martin Maria da Graça Morais , Amaro Júnior Edson , Morettin Pedro Alberto
Published: September 2006

Recent advances in neuroimaging techniques have provided precise spatial localization
of brain activation applied in several neuroscience subareas. The development of functional
magnetic resonance imaging (fMRI), based on the BOLD signal, is one of the most popular
techniques related to the detection of neuronal activation. However, understanding the
interactions between several neuronal modules is also an important task, providing a better
comprehension about brain dynamics. Nevertheless, most connectivity studies in fMRI are based
on a simple correlation analysis, which is only an association measure and does not provide the
direction of information flow between brain areas. Other proposed methods like structural
equation modeling (SEM) seem to be attractive alternatives. However, this approach assumes
prior information about the causality direction and stationarity conditions, which may not be
satisfied in fMRI experiments. Generally, the fMRI experiments are related to an activation task;
hence, the stimulus conditions should also be included in the model. In this paper, we suggest an intervention analysis, which includes stimulus condition, allowing a nonstationary modeling. Furthermore, an illustrative application to real fMRI
dataset from a simple motor task is presented.
Extending Three‐Dimensional Weighted Cone Beam Filtered Backprojection (CB‐FBP) Algorithm for Image Reconstruction in Volumetric CT at Low Helical Pitches
Authors: Tang Xiangyang , Hsieh Jiang , Nilsen Roy A. , McOlash Scott M.
Published: September 2006

A three‐dimensional (3D) weighted helical cone beam filtered backprojection (CB‐FBP) algorithm (namely, original 3D weighted helical CB‐FBP algorithm) has already been proposed to reconstruct images from the projection data acquired along a helical trajectory in angular ranges up to [0, 2π]. However, an overscan is usually employed in the clinic to reconstruct tomographic images with superior noise characteristics at the most challenging anatomic structures, such as head and spine, extremity imaging, and CT angiography as well. To obtain the most achievable noise characteristics or dose efficiency in a helical overscan, we extended the 3D weighted helical CB‐FBP algorithm to handle helical pitches that are smaller than 1 : 1 (namely extended 3D weighted helical CB‐FBP algorithm). By decomposing a helical over scan with an angular range of [0, 2π+Δβ] into a union of full scans corresponding to an angular range of [0, 2π], the extended 3D weighted function is a summation of all 3D weighting functions corresponding to each full scan. An experimental evaluation shows that the extended 3D weighted helical CB‐FBP algorithm can improve noise characteristics or dose efficiency of the 3D weighted helical CB‐FBP algorithm at a helical pitch smaller than 1 : 1, while its reconstruction accuracy and computational efficiency are maintained. It is believed that, such an efficient CB reconstruction algorithm that can provide superior noise characteristics or dose efficiency at low helical pitches may find its extensive applications in CT medical imaging.
A Review on MR Image Intensity Inhomogeneity Correction
Authors: Hou Zujun
Published: September 2006

Intensity inhomogeneity (IIH) is often encountered in MR imaging, and a number of techniques have been devised to correct this artifact. This paper attempts to review some of the recent developments in the mathematical modeling of IIH field. Low‐frequency models are widely used, but they tend to corrupt the low‐frequency components of the tissue. Hypersurface models and statistical models can be adaptive to the image and generally more stable, but they are also generally more complex and consume more computer memory and CPU time. They are often formulated together with image segmentation within one framework and the overall performance is highly dependent on the segmentation process. Beside these three popular models, this paper also summarizes other techniques based on different principles. In addition, the issue of quantitative evaluation and comparative study are discussed.
Analysis of Cone‐Beam Artifacts in off‐Centered Circular CT for Four Reconstruction Methods
Authors: Valton S. , Peyrin F. , Sappey-Marinier D.
Published: September 2006

Cone‐beam (CB) acquisition is increasingly used for truly three‐dimensional X‐ray computerized tomography (CT). However, tomographic reconstruction from data collected along a circular trajectory with the popular Feldkamp algorithm is known to produce the so‐called CB artifacts. These artifacts result from the incompleteness of the source trajectory and the resulting missing data in the Radon space increasing with the distance to the plane containing the source orbit. In the context of the development of integrated PET/CT microscanners, we introduced a novel off‐centered circular CT cone‐beam geometry. We proposed a generalized Feldkamp formula (α‐FDK) adapted to this geometry, but reconstructions suffer from increased CB artifacts. In this paper, we evaluate and compare four different reconstruction methods for correcting CB artifacts in off‐centered geometry. We consider theα‐FDK algorithm, the shift‐variant FBP method derived from the T‐FDK, an FBP method based on the Grangeat formula, and an iterative algebraic method (SART). The results show that the low contrast artifacts can be efficiently corrected by the shift‐variant method and the SART method to achieve good quality images at the expense of increased computation time, but the geometrical deformations are still not compensated for by these techniques.
Preparation of TiO2‐nitrogen‐doped photocatalyst active under visible light
Authors: Wawrzyniak Beata , Morawski Antoni Waldemar , Tryba Beata
Published: September 2006

This study examined the photocatalytic degradation of phenol and azo dyes such as Reactive Red 198 and Direct Green 99 by photocatalysis over amorphous hydrated titanium dioxide (TiO2 · H2O) obtained directly from the sulphate technology installation modified in gaseous ammonia atmosphere. The photocatalysts were used in the solution and coated on the glass plate after sandblasting. The highest rate of phenol degradation in the solution was obtained for catalysts calcinated at 700°C (6.5% wt.), and the highest rate of dye decolorization was found for catalysts calcinated at 500°C and 600°C (ca. 40%–45%). Some TOC measurements of dye solutions were performed to check the rate of mineralization. On the glass plate, the decomposition of DG99 on TiO2/N 500 contrary to TiO2‐P25 proceeded completely after 120 hours of visible light irradiation. The prolongation of the time of irradiation did not enhance DG99 degradation on TiO2‐P25. The decomposition of the Direct Green 99 on TiO2/N 500 coated on the glass plate covered with liquid glass took place up to 24 hours of irradiation. The liquid layer on the glass plate which was covered with the photocatalyst reduced its activity. The nitrogen doping during calcinations under ammonia atmosphere is a new way of obtaining a photocatalyst which could have a practical application in water treatment system under broadened solar light spectrum as well as self‐cleaning coatings.
Nonparametric analysis of blocked ordered categories data:
some examples revisited
Authors: Best D. J. , Rayner J. C. W. , Thas O.
Published: September 2006

Nonparametric analysis for general block designs can be given by
using the Cochran-Mantel-Haenszel (CMH) statistics. We demonstrate
this with four examples and note that several well-known
nonparametric statistics are special cases of CMH statistics.
Mapping the convergence of genetic algorithms
Authors: Drezner Zvi , Marcoulides George A.
Published: September 2006

This paper examines the convergence of genetic algorithms using a
cluster-analytic-type procedure. The procedure is illustrated with
a hybrid genetic algorithm applied to the quadratic assignment
problem. Results provide valuable insight into how population
members are selected as the number of generations increases and how
genetic algorithms approach stagnation after many generations.
Loss protection in pairs trading through minimum profit bounds: A cointegration approach
Authors: Lin Yan-Xia , McCrae Michael , Gulati Chandra
Published: September 2006

Pairs trading is a comparative-value form of statistical arbitrage designed to exploit temporary random departures from equilibrium pricing between two shares. However, the strategy is not riskless. Market events as well as poor statistical modeling and parameter estimation may all erode potential profits. Since conventional loss limiting trading strategies are costly, a preferable situation is to integrate loss limitation within the statistical modeling itself. This paper uses cointegration principles to develop a procedure that embeds a minimum profit condition within a pairs trading strategy. We derive the necessary conditions for such a procedure and then use them to define and implement a five-step procedure for identifying eligible trades. The statistical validity of the procedure is verified through simulation data. Practicality is tested through actual data. The results show that, at reasonable minimum profit levels, the protocol does not greatly reduce trade numbers or absolute profits relative to an unprotected trading strategy.
An analytical characterization for an optimal change of Gaussian measures
Authors: Schellhorn Henry
Published: September 2006

We consider two Gaussian measures. In the “initial”
measure the state variable is Gaussian, with zero drift and
time-varying volatility. In the “target measure” the state
variable follows an Ornstein-Uhlenbeck process, with a free set of
parameters, namely, the time-varying speed of mean reversion. We
look for the speed of mean reversion that minimizes the variance
of the Radon-Nikodym derivative of the target measure with respect
to the initial measure under a constraint on the time integral of
the variance of the state variable in the target measure. We show
that the optimal speed of mean reversion follows a Riccati
equation. This equation can be solved analytically when the
volatility curve takes specific shapes. We discuss an application
of this result to simulation, which we presented in an earlier
article.
An Automated Method for the Determination of Intestinal Disaccharidase and Glucoamylase Activities
Authors: He Zhaoping , Bolling Laura , Tonb Dalal , Nadal Tracey , Mehta Devendra I.
Published: September 2006

Determination of disaccharidase and glucoamylase activities is
important for the diagnosis of intestinal diseases. We adapted a
widely accepted manual method to an automated system that uses the
same reagents reaction volumes, incubation times, and biopsy size
as the manual method. A dye was added to the homogenates as the
internal quality control to monitor the pipetting precision of the
automated system. When the automated system was tested using human
intestinal homogenates, the activities of all the routinely tested
disaccharidases, including lactase, maltase, sucrase, and
palatinase, as well as the activity of glucoamylase, showed
perfect agreement with the manual method and were highly
reproducible. The automated analyzer can perform the same routine
assays of disaccharidases and glucoamylase with high consistency
and accuracy and reduce testing costs by performing a larger
sample size with the same number of staff. Additional
developments, such as barcoding and built‐in plate reading, would
result in a completely automated system.
Moderate deviations for bounded subsequences
Authors: Stoica George
Published: September 2006

We study Davis′ series of moderate deviations probabilities for Lp‐bounded sequences of random variables (p > 2). A certain subseries therein is convergent for the same range of parameters as in the case of martingale difference or i.i.d. sequences.
Molecular Basis for the Immunostimulatory Potency of Small Interfering RNAs
Authors: Sioud Mouldy , Furset Gro
Published: September 2006

Small interfering RNAs (siRNAs) represent a new class of antigene agents, which has emerged as a powerful tool for functional genomics and might serve as a potent therapeutic approach. However, several studies have showed that they could trigger several bystander effects, including immune activation and inhibition of unintended target genes. Although activation of innate immunity by siRNAs might be beneficial for therapy in some instances, uncontrolled activation can be toxic, and is therefore a major challenging problem. Interestingly, replacement of uridines in siRNA sequences with their 2′‐modified counterparts abrogated siRNA bystander effects. Here we highlight these important findings that are expected to facilitate the rational design of siRNAs that avoid the induction of bystander effects.
Targeting Gonadotropins: An Alternative Option for Alzheimer Disease Treatment
Authors: Casadesus Gemma , Puig Emma Ramiro , Webber Kate M. , Atwood Craig S. , Escuer Margarida Castell , Bowen Richard L. , Perry George , Smith Mark A.
Published: September 2006

Recent evidence indicates that, alongside oxidative stress, dysregulation of the cell cycle in neurons susceptible to degeneration in Alzheimer disease may play a crucial role in the initiation of the disease. As such, the role of reproductive hormones, which are closely associated with the cell cycle both during development and after birth, may be of key import. While estrogen has been the primary focus, the protective effects of hormone replacement therapy on cognition and dementia only during a “crucial period” led us to expand the study of hormonal influences to other members of the hypothalamic pituitary axis. Specifically, in this review, we focus on luteinizing hormone, which is not only increased in the sera of patients with Alzheimer disease but, like estrogen, is modulated by hormone replacement therapy and also influences cognitive behavior and pathogenic processing in animal models of the disease. Targeting gonadotropins may be a useful treatment strategy for disease targeting multiple pleiotropic downstream consequences.
Specific Immunoassays for Placental Alkaline Phosphatase As a Tumor Marker
Authors: Stinghen Sérvio T. , Moura Juliana F. , Zancanella Patrícia , Rodrigues Giovanna A. , Pianovski Mara A. , Lalli Enzo , Arnold Dodie L. , Minozzo João C. , Callefe Luis G. , Ribeiro Raul C. , Figueiredo Bonald C.
Published: September 2006

Human placental (hPLAP) and germ cell (PLAP‐like) alkaline
phosphatases are polymorphic and heat‐stable enzymes. This study
was designed to develop specific immunoassays for quantifying
hPLAP and PLAP‐like enzyme activity (EA) in sera of cancer
patients, pregnant women, or smokers. Polyclonal sheep anti‐hPLAP
antibodies were purified by affinity chromatography with whole
hPLAP protein (ICA‐PLAP assay) or a synthetic peptide (aa 57–71)
of hPLAP (ICA‐PEP assay); the working range was 0.1–11 U/L and cutoff value was 0.2 U/L EA for nonsmokers. The intra‐ and interassay coefficients of variation were 3.7%–6.5% (ICA‐PLAP assay) and 9.0%–9.9% (ICA‐PEP assay). An
insignificant cross‐reactivity was noted for high levels of
unheated intestinal alkaline phosphatase in ICA‐PEP assay. A
positive correlation between the regression of tumor size and EA
was noted in a child with embryonal carcinoma. It can be concluded
that ICA‐PEP assay is more specific than ICA‐PLAP, which is still
useful to detect other PLAP/PLAP‐like phenotypes.
Dicer‐Derived MicroRNAs Are Utilized by the Fragile X Mental Retardation Protein for Assembly on Target RNAs
Authors: Plante Isabelle , Davidovic Laetitia , Ouellet Dominique L. , Gobeil Lise-Andrée , Tremblay Sandra , Khandjian Edouard W. , Provost Patrick
Published: September 2006

In mammalian cells, fragile X mental retardation protein (FMRP)
has been reported to be part of a microRNA (miRNA)‐containing
effector ribonucleoprotien (RNP) complex believed to mediate
translational control of specific mRNAs. Here, using recombinant
proteins, we demonstrate that human FMRP can act as a miRNA
acceptor protein for the ribonuclease Dicer and facilitate the
assembly of miRNAs on specific target RNA sequences. The miRNA
assembler property of FMRP was abrogated upon deletion of its
single‐stranded (ss) RNA binding K‐homology domains. The
requirement of FMRP for efficient RNA interference (RNAi) in vivo
was unveiled by reporter gene silencing assays using various small
RNA inducers, which also supports its involvement in an ss small
interfering RNA (siRNA)‐containing RNP (siRNP) effector complex in
mammalian cells. Our results define a possible role for FMRP in
RNA silencing and may provide further insight into the molecular
defects in patients with the fragile X syndrome.
Fractal Dimension of Active‐Site Models of Zeolite Catalysts
Authors: Torrens Francisco , Castellano Gloria
Published: September 2006

A method for the calculation of fractal surfaces of
crystals is presented. The fractal dimension
D of
fragments of zeolites is calculated. Results compare well with
reference calculations (GEPOL). The active site of Brønsted
acid zeolites is modeled by a set of
Al–OH–Si units. These units form
2–12‐membered rings. Topological indices for the different
active‐site models are calculated. The comparison between GEPOL
and SURMO2 allows calculating the active‐site indices. Most
cavities show no fractal character, while for the 6–8‐unit
rings, D lies in the range 4.0–4.3. The 6‐ring shows the
greatest D and is expected to be the most reactive.
Synthesis and Characterization of Strontium Titanate Nanoparticles as Potential High Temperature Oxygen Sensor Material
Authors: Voigts Florian , Damjanovic Tanja , Borchardt Günter , Argirusis Christos , Maus-Friedrichs Wolfgang
Published: September 2006

We present a simple and highly reproductive method
for the preparation of thin films consisting of strontium titanate
nanoparticles. The films are produced by spin coating of a sol on
silicon targets and subsequent annealing under ambient conditions.
Analysis by atomic force microscopy shows particles with typical
sizes between 10 nm and 50 nm. X‐ray photoelectron
spectroscopy displays a stoichiometry of the films as anticipated
from preliminary experiments with strontium titanate single
crystals. Metastable‐induced electron spectroscopy and ultraviolet
photoelectron spectroscopy are used as tools to give evidence to
the similar electronic properties of nanoparticle film and single
crystal. These results support the prospect for an application of
the nanoparticle films as high temperature oxygen sensor with
superior properties.
Application of Intracellular Alkaline Phosphatase Activity Measurement in Detection of Neutrophil Adherence In Vitro
Authors: Bednarska Katarzyna , Klink Magdalena , Sulowska Zofia
Published: September 2006

We have proposed the use of the fluorimetric method with 4‐methylumbelliferyl
phosphate (4‐MUP) specific substrate for the alkaline phosphatase determination in the
neutrophil adhesion assay. We provide evidence that the endogenous neutrophil alkaline
phosphatase (NAP) activity evaluation is reliable to quantify neutrophil adhesion at a wide range of cell numbers (104–106). The results obtained by fluorimetric NAP activity test
correlate to the results of adherence evaluated using the MTT reduction assay. The
fluorimetric NAP activity test may be applied for resting as well as activated neutrophils
without the risk of the activators interferences into the test. The alkaline phosphatase survey
with the use of 4‐MUP substrate is recommended herein as a sensitive, repeatable, simple, and
reliable method of the neutrophil adherence determination in vitro.
On the solvability of a class of reaction‐diffusion systems
Authors: Bouziani Abdelfatah , Mounir Ilham
Published: September 2006

We deal with a class of parabolic reaction‐diffusion systems. We use an iterative process based on results obtained for a linearized problem,
then we derive some a priori estimates to establish the existence, uniqueness, and continuous dependence of the weak solution for a class of quasilinear systems.
Ion slip effect on unsteady Hartmann flow with heat transfer under exponential decaying pressure gradient
Authors: Attia Hazem A.
Published: September 2006

The unsteady Hartmann flow of an electrically conducting, viscous, incompressible fluid bounded by two parallel nonconducting porous plates is studied with heat transfer taking the ion slip into consideration. An external uniform magnetic field and a uniform suction and injection are applied perpendicular to the plates, while the fluid motion is subjected to an exponential decaying pressure gradient. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are included in the energy equation. The effect of the ion slip and the uniform suction and injection on both the velocity and temperature distributions is examined.
Angioleiomyoma: A Rare Cause of Fixed Flexion Contracture of the Elbow
Authors: Dramis Asterios , Grimer Robert J.
Published: September 2006

We describe an unusual case of a patient presented with a painless fixed flexion contracture of the elbow due to an angioleiomyoma. This benign smooth muscle tumour should be considered in the differential diagnosis of flexion contractures of the elbow.
Italian Survey of Organizational Functioning and Readiness for Change: A Cross-Cultural Transfer of Treatment Assessment Strategies
Authors: Rampazzo Lorenzo , De Angeli Monica , Serpelloni Giovanni , Simpson D. Dwayne , Flynn Patrick M.
Published: September 2006

To better understand why some drug abuse treatment programs are more effective than others, USA research about organizational functioning and its role in the provision of treatment services was extended through a study of a delivery system in another country. The Texas Christian University (TCU) organizational functioning and readiness for change instrument (ORC) was translated into Italian and administered to 405 treatment program directors and staff from both public and private sectors in the Veneto Region of Northern Italy. Results indicated that the psychometric properties of the ORC in the USA and Italy are consistent. Some general differences in staff attributes were found between USA and Italian programs, but organizational climates were remarkably similar.
Intercity Differences in Drug Use by Pre-Teenage School Children
Authors: McArdle Paul , Gilvarry Eilish , McCarthy Steve , McIntosh James , McKeganey Neil
Published: September 2006

Background: Regional variations in rates of drug use have been described previously in relation to adolescents. However, reasons for these differences are not clear. Previous publications pointed to higher rates of drug use by Glasgow children compared to children living in Newcastle upon Tyne. This paper explores the hypothesis that a higher rate of drug use in Glasgow is due to higher availability there. Method: School surveys were conducted in Glasgow and Newcastle upon Tyne on a total of 2,318 children aged 10–12. These concerned aspects of behaviour, lifestyle, family life and drug use. Findings: The data indicate that the higher rate of drug use by Glasgow children was attributable to greater opportunities for children to gather at leisure centres and other venues and activities facilitating exposure to more drug-experienced young people.
Substance Use and Substance Use Disorders in a Community Sample of Adolescents and Young Adults: Incidence, Age Effects and Patterns of Use
Authors: Perkonigg Axel , Pfister Hildegard , Höfler Michael , Fröhlich Christine , Zimmermann Petra , Lieb Roselind , Wittchen Hans-Ulrich
Published: September 2006

Objective: We present the prevalence and incidence rates of alcohol, nicotine, and illicit substance use, abuse, and dependence in a sample of German adolescents and young adults. Patterns of onset, cohort trends, and use of various substance classes are also analyzed. Method: A prospective longitudinal epidemiological study with a representative sample of adolescents and young adults (n = 3,021; baseline age range = 14–24 years) was conducted in Munich, Germany. Participants were assessed between 1995 and 1999 with the Munich-Composite International Diagnostic Interview. Results: Cumulative lifetime incidence (up to age 28) of any substance abuse or dependence was 43.8%, and 12-month prevalence of any substance abuse or dependence was 24.4%. The lifetime incidence of nicotine dependence was most frequent (24.8%), followed by alcohol abuse (19.3%) and alcohol dependence (9.2%); 61.7% endorsed the regular use of a substance for at least one circumscribed period during their lifetime. Age-specific incidence rates and age at onset of substance use disorders differed by age cohorts. Furthermore, nicotine dependence was significantly associated with illicit substance use disorders (HR = 2.6, 95% CI 1.7–4.0). An interactive relationship between age, age at onset of nicotine dependence, and subsequent onset of illicit substance use disorders was found. Conclusions: Since the baseline investigation in 1995, high incidence rates of substance use disorders and substance use have been observed in this young German sample. Especially younger cohorts report significantly earlier ages at onset of abuse and dependence. There also seems to be a trend towards a secondary age at onset peak of nicotine dependence after the onset of illicit drug use disorders. Further investigations are needed to study these patterns in younger samples. However, results emphasize the need for a combined prevention of illicit drugs and nicotine dependence.