bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of Transcription by Synthetic DNA‐Bending Agents
Authors: Bednarski David , Firestine Steven M.
Published: September 2006

Gene expression is regulated by a complex interplay between binding and the three‐dimensional arrangement of transcription factors with RNA polymerase and DNA. Previous studies have supported a direct role for DNA bending and conformation in gene expression, which suggests that agents that induce bends in DNA might be able to control gene expression. To test this hypothesis, we examined the effect of triple‐helix‐forming oligonucleotide (TFO) bending agents on the transcription of luciferase in an in vitro transcriptional/translational system. We find that transcription is regulated only by a TFO that induces a bend in the DNA. Related TFOs that do not induce bends in DNA have no effect on transcription. Reporter expression can be increased by as much as 80 % or decreased by as much as 50 % depending on the phasing of the upstream bend relative to the promoter. We interpret the results as follows: when the bend is positioned such that the upstream DNA is curved toward the RNA polymerase on the same DNA face, transcription is enhanced. When the upstream DNA is curved away, transcription is attenuated. These results support the hypothesis that DNA‐bending agents might have the capability to regulate gene expression, thereby opening up a previously undervalued avenue in research on the artificial control of gene expression.
Imaging by Sensitized Oxygenations of Photochromic Anthracene Films: Examination of Effects That Improve Performance and Reversibility
Authors: Fudickar Werner , Linker Torsten
Published: September 2006

The aliphatic anthracene compound 1 and the oligomeric anthracene 2 were synthesized. Thin films of 1 and 2 mixed with the sensitizers tetraphenylporphyrin (TPP) and methylene blue (MB) were irradiated with visible light in air. Upon formation of singlet oxygen, the anthracene units were converted quantitatively to the corresponding endoperoxides. Heating of the irradiated samples afforded the parent anthracenes with high yields. Here, we demonstrate that the kinetics and reversibility of this reaction strongly depend on the microenvironment of the anthracene groups in the two compounds. The photooxidation of thin films of 1 is accompanied by interesting changes in the morphology of the film and allows the first application of 1 as a nondestructive negative‐tone photoresist for lithography and as an oxidizing ink. The morphology of 2 remained unchanged after photooxidation as a result of the stabilizing oligomer backbone. This stabilizing effect significantly improves the photochromic performance of 2. The reversibility of the photooxidation is very high (>90 %) for oligomeric films of 2 after several cycles of irradiation and heating. Decomposition of the anthracene and a loss of the activity of the sensitizer diminish slightly the performance of the monomeric species.
Studies on Pd0‐Catalyzed Cyclization of N‐3,4‐Alkadienyl Toluenesulfonamides with Organic Halides: Selective Synthesis of 2,3‐Dihydropyrroles, 1,2,3,6‐Tetrahydropyrridines, and Azetidines
Authors: Ma Shengming , Yu Fei , Li Jing , Gao Wenzhong
Published: September 2006

The palladium‐catalyzed coupling–cyclization of β‐amino allenes with organic halides ranging from aryl halide to 1‐alkenyl halide was studied. 2,3‐Dihydro‐1H‐pyrroles were obtained by reaction of 3‐substituted‐5‐unsubstituted‐3,4‐allenyl amides under conditions A, while the reaction of 5‐substituted‐3,4‐allenyl amides afforded 1,2,5,6‐tetrahydropyridines and/or azetidines with high de under conditions B or C. The skeleton and relative configuration of the six‐membered products were established by the X‐ray diffraction studies of 10 ka. Allenyl amide 4 q reacted with 1,4‐diiodobenzene 6 r to afford double cyclization product 15. The structure of its major stereoisomer was also determined by the X‐ray diffraction study.
Supported Ionic‐Liquid Films (SILF) as Two‐Dimensional Nanoreactors for Enantioselective Reactions: Surface‐Mediated Selectivity Modulation (SMSM)
Authors: Castillo María R. , Fousse Leslie , Fraile José M. , García José I. , Mayoral José A.
Published: September 2006

Supported ionic‐liquid films (SILF) of nanometric thickness containing bis(oxazoline)–copper complexes can be used as recoverable catalysts for enantioselective cyclopropanation reactions. When a thin film of ionic liquid is supported on a clay, the system behaves as a nearly two‐dimensional nanoreactor in which the restrictions in rotational mobility and the close proximity to the surface support produce variations in the stereo‐ and enantioselectivities, leading to a complete reversal of the overall selectivity of the reaction. As an example, the cyclopropanation of styrene changes from a preference for the (1S,2S)‐trans isomer in bulk solution to the (1R,2S)‐cis isomer in the SILF. This variation is strongly dependent on both the thickness of the film and the nature of the support. Only layered solids with negative charges in the layers (clays) give rise to this type of behaviour, showing that the formation of ion pairs may be a decisive factor. This unexpected effect also shows the existence of differences between bulk and supported ionic liquids.
Water‐Soluble Carbosilane Dendrimers: Synthesis Biocompatibility and Complexation with Oligonucleotides; Evaluation for Medical Applications
Authors: Bermejo Jesus F. , Ortega Paula , Chonco Louis , Eritja Ramon , Samaniego Rafael , Müllner Matthias , de Jesus Ernesto , de la Mata F. Javier , Flores Juan Carlos , Gomez Rafael , Muñoz‐Fernandez Angeles
Published: September 2006

Novel amine‐ or ammonium‐terminated carbosilane dendrimers of type nG‐[Si{OCH2(C6H3)‐3,5‐(OCH2CH2NMe2)2}]x, nG‐[Si{O(CH2)2N(Me)(CH2)2NMe2}]x and nG‐[Si{(CH2)3NH2}]x or nG‐[Si{OCH2(C6H3)‐3,5‐(OCH2CH2NMe3+I−)2}]x, nG‐[Si{O(CH2)2N(Me)(CH2)2NMe3+I−}]x, and nG‐[Si{(CH2)3NH3+Cl−}]x have been synthesized and characterized up to the third generation by two strategies: 1) alcoholysis of SiCl bonds with amino alcohols and subsequent quaternization with MeI, and 2) hydrosilylation of allylamine with SiH bonds of the dendritic systems and subsequent quaternization with HCl. Quaternized carbosilane dendrimers are soluble in water, although degradation is apparent due to hydrolysis of SiO bonds. However, dendrimers containing SiC bonds are water‐stable. The biocompatibility of the second‐generation dendrimers in primary cell cultures of peripheral blood mononuclear cells (PBMCs) and erythrocytes have been analyzed, and they show good toxicity profiles over extended periods. In addition, we describe a study on the interactions between the different carbosilane dendrimers and DNA oligodeoxynucleotides (ODNs) and plasmids along with a comparative analysis of their toxicity. They can form complexes with DNA ODNs and plasmids at biocompatible doses via electrostatic interaction. Also a preliminary transfection assay has been accomplished. These results demonstrate that the new ammonium‐terminated carbosilane dendrimers are good base molecules to be considered for biomedical applications.
Temperature Effects on Ion Association and Hydration in MgSO4 by Dielectric Spectroscopy
Authors: Akilan Chandrika , Rohman Nashiour , Hefter Glenn , Buchner Richard
Published: September 2006

A detailed investigation of aqueous solutions of magnesium sulfate has been made by dielectric relaxation spectroscopy (DRS) over a wide range of frequencies (0.2≤ν/GHz≤89), concentrations (0.02≤m/mol kg−1≤2.3) and temperatures (5≤ϑ/°C≤65). Consistent with literature data from other techniques, the spectra show clear evidence at all temperatures for the simultaneous existence of double solvent‐separated (2SIP), solvent‐shared (SIP) and contact (CIP) ion pairs and a triple ion (TI), Mg2SO42+(aq). Increased formation of CIPs and especially TIs occurs with increasing temperature. The overall standard ion‐association constant, KA°, corresponding to the equilibrium: Mg2+(aq)+SO42−(aq)⇌MgSO40(aq) is in good agreement with literature data at lower temperatures but is overestimated at higher temperatures due to processing difficulties. Despite the limited precision of the spectra, analysis of the individual steps in the ion‐association process is possible for the first time. The 2SIPs are formed with little disturbance to their hydration shells, the (partial) destruction of which appears to occur mostly during the formation of SIPs. Effective hydration numbers derived from the DRS spectra indicate that both Mg2+ and SO42− influence solvent water molecules beyond their first hydration spheres but that MgSO4(aq) is less strongly hydrated than the previously studied CuSO4(aq).
Seismic response of critical interdependent networks
Authors: Dueñas‐Osorio Leonardo , Craig James I. , Goodno Barry J.
Published: September 2006

During the last decade, critical infrastructure systems such as electric power, water distribution, transportation and telecommunications have been stressed by significant natural hazards and human errors leading to malfunction. Earthquakes, blackouts and satellite failures have evidenced the vulnerability of these growing networked systems threatening the continuity of the United States' economy. The potential for malicious perturbations to these systems is also an important current concern. However, the underlying susceptibility of these networks to disruptive events is in large part due to the increasingly complex pattern of interdependencies that tie these civil infrastructures together. This paper mainly investigates the effect of seismic disruptions on the performance of real interdependent networks. Maintenance‐induced malfunctions and coordinated attacks are also studied for completeness. Several degrees of interconnectedness are explored. Interdependent network fragility curves are introduced to display the effect of these different strengths of coupling. Characterization of the performance displayed by the networks is utilized to propose mitigation actions and study propagation of their effects. It is shown that minimal strategic interventions propagated through the network can generate a more resilient interdependent entity. Copyright © 2006 John Wiley & Sons, Ltd.
Experimental study of dynamic damage of an arch dam
Authors: Wang Haibo , Li Deyu
Published: September 2006

Seismic responses of a 292‐m high arch dam were studied by experiment on a shaking table. The model system included the arch dam with contraction joints, a part of a reservoir, and a partial foundation with a topographic feature near the dam. Potential rock wedges on the abutments and the mechanical properties including uplift on the kinematic planes were carefully simulated. A damping boundary consisting of a viscous liquid was introduced to simulate the effect of dynamic energy emission to far field, which made the dynamic interaction between the dam and the foundation be adequately represented in the model test of an arch dam system. Dynamic responses of the arch dam system under a sequence of seismic loadings in increasing strength were examined. Eleven cracks or overstresses on the model dam due to the earthquake excitations were observed, and consequently, its natural frequency dropped by about 14%, but the model dam was stable under the hydrostatic load of the impounded water after the test. Copyright © 2006 John Wiley & Sons, Ltd.
Energy dissipation in rocking bridge piers under free vibration tests
Authors: Cheng Chin‐Tung
Published: September 2006

This research aims to investigate the dynamic characteristic of rocking bridge columns subjected to quick release loads. Precast columns anchored by unbonded steel bars at the centre of each column can rock on the foundation surface without inducing any residual deformation after earthquakes. The restoring force of columns relies on gravity load from the superstructure and tensile strength in anchor bars. Radiation damping is evaluated through each impact of column rocking. To validate the theoretical damping proposed by previous researchers, four columns were constructed. Research parameters included steel or plastic materials used as rocking interfaces, area of anchor bars, aspect ratio and size effect of columns. Test results revealed that stocky columns slid apparently in the first impact then rocked, but taller columns rocked with minor slips in the entire motion. And freestanding columns slid significantly in the first impact that led to a higher damping. Radiation damping due to impact in the entire motion for all tests was within 5%. Copyright © 2006 John Wiley & Sons, Ltd.
Shaking‐table tests on reinforced concrete frames with different isolation systems
Authors: Dolce Mauro , Cardone Donatello , Ponzo Felice C.
Published: September 2006

The effectiveness of seismic isolation in protecting structural and non‐structural elements from damage has been assessed in an extensive programme of shaking‐table tests, carried out on four identical 1/3.3‐scale, two‐dimensional, reinforced concrete (R/C) frames. Four different isolation systems were considered, namely: (i) rubber‐based, (ii) steel‐based, (iii) shape memory alloy (SMA)‐based and (iv) hybrid, i.e. based on both SMA and steel components, isolation systems.

This paper presents a comprehensive overview of the main results of the experimental tests on base‐isolated models, whose structural response is described through: (i) maximum base displacements; (ii) maximum interstorey drifts; (iii) maximum storey accelerations and (iv) maximum storey shear forces. The evolution of the fundamental frequency of vibration of the R/C frame during the tests is also described.

The beneficial effects of using base isolation resulted in no or slight damage, under strong earthquakes, to both structural and non‐structural members, as well as to the internal content of the building. The comparison with the experimental results obtained in shaking‐table tests on similar fixed‐base models emphasizes these positive aspects. Finally, advantages and drawbacks related to the use of each isolation system are discussed in the paper. Copyright © 2006 John Wiley & Sons, Ltd.
A non‐diffusive, divergence‐free, finite volume‐based double projection method on non‐staggered grids
Authors: Aprovitola A. , Denaro F. M.
Published: September 2006

Second‐order accurate projection methods for simulating time‐dependent incompressible flows on cell‐centred grids substantially belong to the class either of exact or approximate projections. In the exact method, the continuity constraint can be satisfied to machine‐accuracy but the divergence and Laplacian operators show a four‐dimension nullspace therefore spurious oscillating solutions can be introduced. In the approximate method, the continuity constraint is relaxed, the continuity equation being satisfied up to the magnitude of the local truncation error, but the compact Laplacian operator has only the constant mode. An original formulation for allowing the discrete continuity equation to be satisfied to machine‐accuracy, while using a finite volume based projection method, is illustrated. The procedure exploits the Helmholtz–Hodge decomposition theorem for deriving an additional velocity field that enforces the discrete continuity without altering the vorticity field. This is accomplished by solving a second elliptic field for a scalar field obtained by prescribing that its additional discrete gradients ensure discrete continuity based on the previously adopted linear interpolation of the velocity. The resulting numerical scheme is applied to several flow problems and is proved to be accurate, stable and efficient.

This paper has to be considered as the companion of: 'F. M. Denaro, A 3D second‐order accurate projection‐based finite volume code on non‐staggered, non‐uniform structured grids with continuity preserving properties: application to buoyancy‐driven flows. IJNMF 2006; 52(4):393–432. Now, we illustrate the details and the rigorous theoretical framework. Copyright © 2006 John Wiley & Sons, Ltd.
Edge‐based data structures for a symmetric stabilized finite element method for the incompressible Navier–Stokes equations with heat transfer
Authors: Kraft R. A. , Coutinho A. L. G. A. , de Sampaio P. A. B.
Published: September 2006

This work presents a new implementation of the De Sampaio–Coutinho formulation (Int. J. Numer. Meth. Fluids 1999; 29:289–309), a segregated Petrov–Galerkin/generalized least‐squares method, for the solution of the incompressible Navier–Stokes equations with heat transfer. Such a formulation produces symmetric, positive‐definite matrices, allowing the use of a preconditioned conjugate gradient solver for each unknown. The formulation also intrinsically introduces streamline upwinding by the choice of adequate time steps, providing a suitable description of convective dominated flows. The code was primarily written using element‐based data structures, making use of parallel/vector techniques and mesh adaptivity. However, schemes based on edge‐based data structures have been introduced with the aim of reducing flop count, memory demands and indirect addressing. In this work, the De Sampaio–Coutinho formulation has been re‐written considering an edge‐based arrangement. The effectiveness of the new scheme was observed solving some standard test cases, as shown in this paper, with a comparatively high gain in computational efficiency. Copyright © 2006 John Wiley & Sons, Ltd.
Compatibility between finite volumes and finite elements using solutions of shallow water equations for substance transport
Authors: Postma Leo , Hervouet Jean‐Michel
Published: September 2006

This paper formulates a finite volume analogue of a finite element schematization of three‐dimensional shallow water equations. The resulting finite volume schematization, when applied to the continuity equation, exactly reproduces the set of matrix equations that is obtained by the application of the corresponding finite element schematization to the continuity equation. The procedure allows the consistent and mass conserving coupling of the finite element Telemac model for three‐dimensional flow with the finite volume Delft3D‐WAQ model for water quality. The work has been carried out as part of a joint development by LNHE and WL∣Delft Hydraulics to explore the mutual interaction of their software. Copyright © 2006 John Wiley & Sons, Ltd.
Calcium signaling in specialized glial cells
Authors: Metea Monica R. , Newman Eric A.
Published: September 2006

This article reviews calcium signaling in three specialized types of glial cells: Müller cells of the retina, Bergmann glial cells of the cerebellum, and radial glial cells of the developing cortex. Müller cells generate spontaneous and neuronal activity‐evoked increases in Ca2+. Neuron to Müller cell signaling is mediated by neuronal release of ATP and activation of glial P2Y receptors. Müller cells, in turn, modulate neuronal excitability and mediate vasomotor responses. Bergmann glial cells also generate spontaneous and activity‐evoked Ca2+ increases. Neuron to Bergmann glia signaling is mediated by neuronal release of nitric oxide, noradrenaline, and glutamate. In Bergmann glia, Ca2+ increases control the structural and functional interactions between these cells and Purkinje cell synapses. In the ventricular zone of the developing cortex, radial glial cells generate spontaneous Ca2+ increases that propagate as Ca2+ waves through clusters of neighboring glial cells. These Ca2+ increases control cell proliferation and neurogenesis. © 2006 Wiley‐Liss, Inc.
Molecular determinants ofD‐serine‐mediated gliotransmission: From release to function
Authors: Oliet Stéphane H. R. , Mothet Jean‐Pierre
Published: September 2006

Since the late 80s, it is recognized that functional activation ofN‐methylD‐aspartate receptors (NMDARs) requires the binding of both glutamate and glycine. However, the surprising discovery that the wrong isomer of serine,D‐serine, is present in mammals has profoundly challenged this dogmatic model of NMDARs activation. Indeed, there are accumulating evidence indicating thatD‐serine is the endogenous ligand for the glycine modulatory binding site in many brain areas.D‐Serine is synthesized in glial cells by serine racemase (SR) and released upon activation of glutamate receptors. Here, we will provide an overview of recent findings on the molecular and cellular mechanisms involved in the synthesis and release of this gliotransmitter. We will also emphasize the function of this novel messenger in regulating synaptic excitatory transmission and plasticity in different brain areas. Because it fulfils all criteria for a gliotransmitter,D‐serine regulatory action on glutamatergic transmission further illustrates the emerging concept of the “tripartite synapse”. © 2006 Wiley‐Liss, Inc.
Haplotype matching is not an essential requirement to achieve remyelination of demyelinating CNS lesions
Authors: Tepavcević V. , Blakemore W. F.
Published: September 2006

Transplantation of oligodendrocyte precursor cells (OPCs) results in efficient remyelination in animal models of demyelination. However, the experiments so far undertaken have not addressed the need for tissue‐type matching to achieve graft‐mediated remyelination. Examination of MHC expression (main determinant of allograft rejection) by OPCs showed nondetectable levels under standard culture conditions and upregulation of MHC Class I expression only upon exposure to interferon γ. We therefore hypothesized that MHC matching of OPC grafts may not be crucial to achieve transplant‐mediated remyelination. Transplant experiments performed using a nonself repairing toxin‐induced demyelination model showed that, similarly to allogeneic neurons, survival of allogeneic oligodendrocyte lineage cells is influenced by donor–host haplotype combination and graft composition. Transplantation of allogeneic mixed glial cell cultures resulted in remyelination failure by 1 month postengraftment due to a rejection response targeting both myelinating oligodendrocytes and OPCs, suggesting that inflammation‐induced upregulation of OPC MHC I expression results in susceptibility to cytotoxic T cell attack. In contrast, remyelination persisted for at least 2 months following transplantation of OPC‐enriched cultures whose overall MHC expression level was significantly decreased. While OPC‐enriched preparations elicited delayed type hypersensitivity responses in hosts sensitized to alloantigens, allografting of such preparations into a central nervous system demyelinating lesion did not result in recipient priming. We conclude that while allografted oligodendrocyte lineage cells become targets of a graft rejection response once this response has been initiated, transplantation of OPC‐enriched preparations can evade priming against alloantigens and graft rejection. This finding indicates that close tissue matching may not be an essential requirement for successful transplant‐mediated remyelination. © 2006 Wiley‐Liss, Inc.
Cognitive and psychiatric predictors of medical treatment adherence among older adults in primary care clinics
Authors: Mackin R. Scott , Areán Patricia A.
Published: September 2006

Objectives

Medical treatment non‐adherence among older adults is common and represents a significant public health care concern. Treatment non‐adherence has been associated with a number of factors in older adults; however few studies have delineated the role of cognition and psychiatric status.

Participants

Data were collected from 212 ethnically diverse older primary care patients as part of a larger study.

Measurements

Cognitive status was evaluated with the Mattis Dementia Rating scale (DRS). Psychiatric status was evaluated using the Geriatric Depression Scale (GDS) and the Beck Anxiety Inventory (BAI). Treatment adherence was assessed by the total number of missed healthcare appointments and by physician and patient ratings. Physician ratings of patients' understanding of medical instructions were also obtained.

Design

A series of multiple regression analyses were conducted to determine cognitive and psychiatric predictors for each measure of treatment adherence.

Results

GDS and DRS memory scores were both independent predictors of the total number of missed medical appointments, F(7,55) = 2.34, p = 0.038. GDS score was also shown to be a significant predictor of physician ratings of patients' understanding of medical instructions, F(7,33) = 0.89, p = 0.031. Neither cognitive performance nor psychiatric status was associated with patient or physician ratings of treatment adherence.

Conclusions

Measures of cognitive functioning and depression severity were supported as predictors of objective measures of treatment adherence but they were not associated with physician or patient ratings of adherence. Patient depression may influence physician ratings of patients' comprehension of medical instructions. Copyright © 2006 John Wiley & Sons, Ltd.
A review of the experience of hospital autonomy in Pakistan
Authors: Abdullah M. Tanweer , Shaw Jane
Published: September 2006

This paper examines the recent trends in public hospital autonomy as an integral part of health systems reforms. It reviews literature produced on the subject across a range of developing countries and explores varying viewpoints, arguments, and rationale for hospital autonomy developed over the past two decades. It then leads onto a discussion of two experiences of autonomy reforms in Pakistan: the provinces of Punjab and NWFP. Derived from the lessons learned from these initiatives, a set of guidelines is suggested as sustainable frameworks for reviewing the current measures and for designing future autonomy initiatives in Pakistan. Copyright © 2006 John Wiley & Sons, Ltd.
Credit spread volatility, bond ratings and the risk reduction effect of watchlistings
Authors: Heinke Volker G.
Published: September 2006

This article examines the relationship between the volatility of the credit risk premium of a plain vanilla bond and its credit rating. We calculate volatilities over different time windows and test for differences in the mean volatility depending on the bond rating. We check for the influence of further factors that are theoretically relevant for the explanation of the credit spread volatility. Moreover, we check the dynamic effect of rating changes on bond spread volatility. Finally, we test whether credit watchlistings influence credit spread volatility. We confirm prior studies in that, generally, credit ratings rank the risk of bonds according to credit spread volatility. We further find that rating changes have a dynamic influence on spread volatilities. Additionally it is shown that credit watchlistings significantly reduce the volatility. Thus, watchlistings are perceived to offer valuable information. Copyright © 2006 John Wiley & Sons, Ltd.
A tale of two ‘globalizations’: capital flows from rich to poor in two eras of global finance
Authors: Schularick Moritz
Published: September 2006

In this paper we take a comparative look at the patterns of capital flows from rich to poor countries in two eras of financial globalization. The paper extends recent research on the developmental effects of international financial integration, long‐term trends in capital mobility and ‘globalization in historical perspective’. Analysing the patterns of international financial integration in the three decades of the classical gold standard and after 1990 we show that investment in developing countries was a central element of 19th century financial globalization, but plays only a minor role today. The Lucas paradox of capital failing to flow from rich to poor has grown much stronger. In historical perspective, today's financial globalization is marked by massive diversification flows between high‐income economies and a relative marginalization of less‐developed economies. Copyright © 2006 John Wiley & Sons, Ltd.
The out‐of‐sample forecasts of nonlinear long‐memory models of the real exchange rate
Authors: Chung Sang‐Kuck
Published: September 2006

We consider a new time series model that can describe long memory and nonlinearity simultaneously and can be used to assess an extensive evaluation of the out‐of‐sample forecasting performance of the nonlinear long‐memory model. Upon fitting it to the real exchange rate, we find that a parsimonious version of the model captures the salient features of the data rather well. We then use this nonlinear long‐memory model to forecast dynamically out‐of‐sample over the sample period for OECD countries. Overall, we find clear evidence that favours the nonlinear long‐memory model over any other estimated models. Copyright © 2006 John Wiley & Sons, Ltd.
Regime switching and artificial neural network forecasting of the Cyprus Stock Exchange daily returns
Authors: Constantinou Eleni , Georgiades Robert , Kazandjian Avo , Kouretas Georgios P.
Published: September 2006

This paper provides an analysis of regime switching in volatility and out‐of‐sample forecasting of the Cyprus Stock Exchange by using daily data for the period 1996–2002. We first model volatility regime switching within a univariate Markov switching framework. Modelling stock returns within this context can be motivated by the fact that the change in regime should be considered as a random event and not predictable. The results show that linearity is rejected in favour of an MS specification, which forms statistically an adequate representation of the data. Two regimes are implied by the model, the high‐volatility regime and the low‐volatility one, and they provide quite accurately the state of volatility associated with the presence of a rational bubble in the capital market of Cyprus. Another implication is that there is evidence of regime clustering. We then provide out‐of‐sample forecasts of the CSE daily returns by using two competing nonlinear models, the univariate Markov switching model and the Artificial Neural Network Model. The comparison of the out‐of‐sample forecasts is done on the basis of forecast accuracy, using the Diebold and Mariano test and forecast encompassing, using the Clements and Hendry test. The results suggest that both nonlinear models are equivalent in forecasting accuracy and forecasting encompassing, and therefore on forecasting performance. Copyright © 2006 John Wiley & Sons, Ltd.
Neuronal precursors within the adult rat subventricular zone differentiate into dopaminergic neurons after substantia nigra lesion and chromaffin cell transplant
Authors: Arias‐Carrión Oscar , Hernández‐López Salvador , Ibañez‐Sandoval Osvaldo , Bargas José , Hernández‐Cruz Arturo , Drucker‐Colín René
Published: September 2006

Neurogenesis in the adult mammalian brain continues in the subventricular zone (SVZ). Neuronal precursors from the SVZ migrate along the rostral migratory stream to replace olfactory bulb interneurons. After the destruction of the nigro‐striatal pathway (SN‐lesion), some SVZ precursors begin to express tyrosine hydroxylase (TH) and neuronal markers (NeuN). Grafting of chromaffin cells (CCs) into the denervated striatum increases the number of TH+ cells (SVZ TH+ cells; Arias‐Carrión et al., 2004). This study examines the functional properties of these newly differentiating TH+ cells. Under whole‐cell patch‐clamp, most SVZ cells recorded from lesioned and grafted animals (either TH+ or TH−) were non‐excitable. Nevertheless, a small percentage of SVZ TH+ cells had the electrophysiologic phenotype of mature dopaminergic neurons and showed spontaneous postsynaptic potentials. Dopamine (DA) release was measured in SVZ and striatum from both control and SN‐lesioned rats. As expected, 12 weeks after SN lesion, DA release decreased drastically. Nevertheless, 8 weeks after CCs graft, release from the SVZ of SN‐lesioned rats recovered, and even surpassed that from control SVZ, suggesting that newly formed SVZ TH+ cells release DA. This study shows for the first time that in response to SN‐lesions and CC grafts neural precursors within the SVZ change their developmental program, by not only expressing TH, but more importantly by acquiring excitable properties of mature dopaminergic neurons. Additionally, the release of DA in a Ca2+‐dependent manner and the attraction of synaptic afferents from neighboring neuronal networks gives further significance to the overall findings, whose potential importance is discussed. © 2006 Wiley‐Liss, Inc.
Late Quaternary palaeoceanography of the Circumpolar Deep Water from the South Tasman Rise
Authors: Moy Andrew D. , Howard William R. , Gagan Michael K.
Published: September 2006

We use sediment cores from the South Tasman Rise (STR) to reconstruct deep‐ water circulation in the southwest Pacific sector of the Southern Ocean. Sediment cores MD972106 (45° 09′ S, 146° 17′ E, 3310 m water depth) and GC34 (45° 06′ S, 147° 45′ E, 4002 m water depth) preserve records covering the last 160 k yr, with chronology controlled by calibrated accelerator mass spectrometry radiocarbon dates and benthic foraminiferal δ18O tied to SPECMAP. The STR benthic foraminiferal δ13C records provide new δ13C values for Southern Ocean deep water spanning the last 160 k yr at sites unlikely to be affected by variations in productivity. The records establish that glacial benthic foraminifera (Cibicidoides spp.) δ13C values are lower relative to interglacial values and are comparable to previous glacial benthic δ13C records in the Indian and Pacific sectors of the Southern Ocean. Comparisons of the benthic foraminiferal δ13C time series at the STR are made with the equatorial Pacific (V19‐30 and Site 846) and the equatorial Atlantic (GeoB1115). The similarity of benthic δ13C records at the STR to the equatorial Pacific suggest the Southern Ocean deep‐water mass closely tracked those of the deep Pacific, and the presence of a δ13C gradient between the STR and the equatorial Atlantic suggests there was continual production of northern source deep water over the past 160 k yr. Copyright © 2006 John Wiley & Sons, Ltd.
The vegetation history of the last glacial–interglacial cycle in eastern New South Wales, Australia
Authors: Williams N. J. , Harle K. J. , Gale S. J. , Heijnis H.
Published: September 2006

We present a reconstruction of the vegetation history of the last glacial–interglacial cycle (ca. 75 k cal. yr BP–present) at Redhead Lagoon, an enclosed lake basin in coastal, eastern New South Wales, Australia. The sequence of vegetation change at the site is broadly comparable with the pattern of climatically induced changes observed in many other pollen records in southeast Australia. Open woodland–herbland and woodland–forest communities correspond with glacial and interglacial periods respectively, with an additional change towards a more open understorey vegetation assemblage over the last 40 000 yr. The driest conditions appear to have occurred during the height of the last glacial (some time between 30 and 20 k cal. yr BP). This is consistent with other records from southeast Australia, and provides support for a poleward shift in the subtropical anticyclone belt and, less certainly, for the thesis that the Southern Hemisphere westerlies intensified during this period. In marked contrast to most sites in southeast Australia, Casuarinaceae dominates the pollen record through the height of the last glacial period and into the Holocene. The postglacial climatic amelioration is accompanied by the general reappearance of tree pollen in the record, by the disappearance of several open and disturbed environment indicator taxa, by increases in organic sediment deposition and pollen taxon diversity, and by higher water balances. While climate appears to have been the major control on patterns of vegetation change at this site throughout most of the last glacial–interglacial cycle, changes in depositional environment and hydrology have also played a role. Significantly, substantial increases in the rate and magnitude of many indicators of environmental disturbance since European settlement suggest that humans are now the most important mechanism for environmental change. Copyright © 2006 John Wiley & Sons, Ltd.
Millennia‐long tree‐ring records from Tasmania and New Zealand: a basis for modelling climate variability and forcing, past, present and future
Authors: Cook Edward R. , Buckley Brendan M. , Palmer Jonathan G. , Fenwick Pavla , Peterson Michael J. , Boswijk Gretel , Fowler Anthony
Published: September 2006

Progress in the development of millennia‐long tree‐ring chronologies from Australia and New Zealand is reviewed from the perspective of modelling long‐term climate variability there. Three tree species have proved successful in this regard: Huon pine (Lagarostrobos franklinii) from Tasmania, silver pine (L. colensoi) from the South Island of New Zealand, and kauri (Agathis australis) from the North Island of New Zealand. Each of these species is very long‐lived and produces abundant quantities of well‐preserved wood for extending their tree‐ring chronologies back several millennia into the past. The growth patterns on these chronologies strongly correlate with both local and regional warm‐season temperature changes over significant areas of the Southern Hemisphere (especially Huon and silver pine) and to ENSO variability emanating from the equatorial Pacific region (especially kauri). In addition, there is evidence for significant, band‐limited, multi‐decadal and centennial timescale variability in the warm‐season temperature reconstruction based on Huon pine tree rings that may be related to slowly varying changes in ocean circulation dynamics in the southern Indian Ocean. This suggests the possibility of long‐term climate predictability there. Copyright © 2006 John Wiley & Sons, Ltd.
Extension of New Zealand kauri (Agathis australis) tree‐ring chronologies into Oxygen Isotope Stage (OIS) 3
Authors: Palmer Jonathan , Lorrey Andrew , Turney Chris S. M. , Hogg Alan , Baillie Mike , Fifield Keith , Ogden John
Published: September 2006

New Zealand kauri (Agathis australis) is both long‐lived and sensitive to climate so during the past two decades an extensive network of sites has been sampled for dendrochronological analyses. The network can be divided into three general groups based on the time period they cover—‘modern’ kauri (MK), late‐Holocene kauri (HK) and ‘ancient’ kauri (AK) from before the Last Glacial Maximum (LGM). Although the groups are restricted to northern New Zealand (i.e. having overlapping ranges) they occur at different elevations. Modern kauri sites tend to be along ridges and much higher than the two subfossil groups (i.e. HK and AK sites). We propose the modern kauri situation to be a typical artefact of anthropogenic activities. In contrast, the subfossil groups are the result of a complex process of dune migration, levee formation and water‐table rise leading to bog formation driven by rising sea levels. Most of the 16 AK sites have radiocarbon ages clearly within Oxygen Isotope Stage (OIS) 3 and a preliminary group of chronologies have been developed that collectively cover 10 719 yr. Analysis is ongoing, but there is clear potential to span a much greater time period and recover detailed palaeoclimatic information. Copyright © 2006 John Wiley & Sons, Ltd.
Shear‐Induced Crystallization in a Blend of Isotactic Poly(propylene) and Poly(ethylene‐co‐octene)
Authors: Meng Kun , Dong Xia , Zhang Xiaohua , Zhang Chenggui , Han Charles C.
Published: September 2006

Summary: Shear‐induced crystallization in a blend of isotactic poly(propylene) and poly(ethylene‐co‐octene) (iPP/PEOc) has been investigated by means of in‐situ optical microscopy and a shear hot stage under various thermal and shear histories. Cylindrites are observed after shear in the phase‐separated iPP/PEOc blends for the first time. The nuclei (shish) come from the orientation of the entangled network chains, and the relationship between the shear rate and the network relaxation time of the oriented iPP chains is a very important factor that dominates the formation of the cylindrites after liquid‐liquid phase separation. The cylindrites can grow through phase‐separated domains with proper shear rate and shear time. In addition, the number of spherulites increases with shear rate, which is consistent with the notion of fluctuation‐induced nucleation/crystallization.

Phase‐contrast optical micrograph of the iPP/PEOc = 50/50 (wt.‐%) sample sheared during cooling with shear rate of 10 s−1 and isothermally crystallized at 140 °C for 142 s after isothermal annealing at 170 °C for 420 min. The shear time is 180 s.

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Phase‐contrast optical micrograph of the iPP/PEOc = 50/50 (wt.‐%) sample sheared during cooling with shear rate of 10 s−1 and isothermally crystallized at 140 °C for 142 s after isothermal annealing at 170 °C for 420 min. The shear time is 180 s.
Shear‐Controlled Micro/Nanometer‐Scaled Super‐Hydrophobic Surfaces with Tunable Sliding Angles from Single Component Isotactic Poly(propylene)
Authors: Yao Yonghua , Dong Xia , Hong Song , Ge Hongli , Han Charles C.
Published: September 2006

Summary: With the proper selection of shear and thermal conditions, super‐hydrophobic polymeric surfaces (contact angle > 150°) with tunable sliding angles (from less than 1° to higher than 90°) can be prepared from pure isotactic poly(propylene) (iPP) without any further modification with low‐surface‐energy components under ambient atmosphere. The formed surfaces have naturally good thermal properties, chemical and moisture resistance, low density, and potentially low manufacturing cost.

SEM images of formed super‐hydrophobic surfaces and related two extreme sliding angles (contact angles of these surfaces are higher than 150°).

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SEM images of formed super‐hydrophobic surfaces and related two extreme sliding angles (contact angles of these surfaces are higher than 150°).
The Relationship between Craze Structure and Molecular Weight in Polystyrene as Revealed by µSAXS Experiments
Authors: Zafeiropoulos Nikolaos E. , Davies Richard J. , Schneider Konrad , Burghammer Manfred , Riekel Christian , Stamm Manfred
Published: September 2006

Summary: The phenomenon of crazing in polymers has received considerable attention in the past as it is thought to play a pivotal role in determining the performance of polymers under load. One aspect of particular interest has been the interconnection between molecular structure, craze characteristics, and macromechanical properties. In the present study, three different grades of polystyrene (PS) with different molecular weights have been systematically investigated in situ with synchrotron radiation microfocus small‐angle X‐ray scattering (µSAXS). The results suggest that there are different mechanisms operating in PS samples with low and very high molecular weights, compared to those of medium‐to‐high molecular weight. Previously it was thought that, above the critical molecular weight of entanglement, the effect of molecular weight on PS's mechanical behaviour at room temperature was negligible.

Craze evolution as a function of strain in PS.

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Craze evolution as a function of strain in PS.
Efficient Homogeneous Chemical Modification of Bacterial Cellulose in the Ionic Liquid 1‐N‐Butyl‐3‐methylimidazolium Chloride
Authors: Schlufter Kerstin , Schmauder Hans‐Peter , Dorn Susann , Heinze Thomas
Published: September 2006

Summary: Bacterial cellulose (BC), a unique type of cellulose, with high degree of polymerization of 6 500 could be dissolved easily in the ionic liquid 1‐N‐butyl‐3‐methylimidazolium chloride. For the first time, well‐soluble BC acetates and carbanilates of high degree of substitution (up to a complete modification of all hydroxyl groups) were accessible under homogeneous and mild reaction conditions. Characterization of the new BC derivatives by NMR and FTIR spectroscopy shows an unexpected distribution of the acetyl moieties in the order O‐6 > O‐3 > O‐2.

13C NMR spectrum (DMSO‐d6) of a cellulose acetate with a DS of 2.25 synthesized in 1‐N‐butyl‐3‐methylimidazolium chloride.

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13C NMR spectrum (DMSO‐d6) of a cellulose acetate with a DS of 2.25 synthesized in 1‐N‐butyl‐3‐methylimidazolium chloride.
The Effect of [CuI]/[CuII] Ratio on the Kinetics and Conformation of Polyelectrolyte Brushes by Atom Transfer Radical Polymerization
Authors: Cheng Nan , Azzaroni Omar , Moya Sergio , Huck Wilhelm T. S.
Published: September 2006

Summary: The atom transfer radical polymerization of [2‐(methacryloyloxy)ethyl]trimethylammonium chloride (METAC) has been studied under different [CuI]/[CuII] ratios. The reaction kinetics is followed by ellipsometry and quartz crystal microbalance and it was found that the reaction speed influences the grafting density of the polymer brushes. High [CuI]/[CuII] ratios, i.e., fast polymerizations, lead to less dense polymer brushes.

Plot of the frequency change of wet brushes on a QCM crystal (Δf) versus the dry thickness of brushes synthesized at different [CuI]/[CuII] ratios.

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Plot of the frequency change of wet brushes on a QCM crystal (Δf) versus the dry thickness of brushes synthesized at different [CuI]/[CuII] ratios.
Prediction of chemotherapeutic response of colorectal liver metastases with dynamic gadolinium‐DTPA‐enhanced MRI and localized 19F MRS pharmacokinetic studies of 5‐fluorouracil
Authors: van Laarhoven H. W. M. , Klomp D. W. J. , Rijpkema M. , Kamm Y. L. M. , Wagener D. J. Th. , Barentsz J. O. , Punt C. J. A. , Heerschap A.
Published: September 2006

Systemic chemotherapy is effective in only a subset of patients with metastasized colorectal cancer. Therefore, early selection of patients who are most likely to benefit from chemotherapy is desirable. Response to treatment may be determined by the delivery of the drug to the tumor, retention of the drug in the tumor and by the amount of intracellular uptake, metabolic activation and catabolism, as well as other factors. The first aim of this study was to investigate the predictive value of DCE‐MRI with the contrast agent Gd‐DTPA for tumor response to first‐line chemotherapy in patients with liver metastases of colorectal cancer. The second aim was to investigate the predictive value of 5‐fluorouracil (FU) uptake, retention and catabolism as measured by localized 19F MRS for tumor response to FU therapy. Since FU uptake, retention and metabolism may depend on tumor vascularization, the relationship between 19F MRS and the DCE‐MRI parameters kep, Ktrans and ve was also examined (1). In this study, 37 patients were included. The kinetic parameters of DCE‐MRI, kep, Ktrans and ve, before start of treatment did not predict tumor response after 2 months, suggesting that the delivery of chemotherapy by tumor vasculature is not a major factor determining response in first‐line treatment. No evident correlations between 19F MRS parameters and tumor response were found. This suggests that in liver metastases that are not selected on the basis of their tumor diameter, FU uptake and catabolism are not limiting factors for response. The transfer constant Ktrans, as measured by DCE‐MRI before start of treatment, was negatively correlated with FU half‐life in the liver metastases, which suggests that, in metastases with a larger tumor blood flow or permeability surface area product, FU is rapidly washed out from the tumor. Copyright © 2006 John Wiley & Sons, Ltd.
The effect of initiator system on acrylate emulsion copolymerization with higher hydroxyl monomer content
Authors: Zhang Fa‐Ai , Yu Cai‐Li , Zhu Xing‐Hua , Wei Chun
Published: September 2006

The influence of the initiator (ammonium persulfate, APS) and APS/reducer system on the acrylate emulsion copolymerization of methyl methacrylate/butyl acrylate/acrylic acid/hydroxylethyl methacrylate (HEMA) was studied. The initiator level, reaction temperature, reducer type and reducer level on the effect of polymerization rate, particle size and size distribution were investigated. It was found that with the existence of hydrophilic monomer HEMA, polymerization rate increased but the particle size decreased and the size distribution became narrowed with the increase of initiator level, reaction temperature and reducer sodium hydrogen carbonate (NaHSO3) level. The APS/NaHSO3 system had better initiation efficiency than the APS/FeSO4 system. Copyright © 2006 John Wiley & Sons, Ltd.