bluuebunny/crossref_metadata_2025 huggingface dataset:
Mutations of the PTPN11 and RAS genes in rhabdomyosarcoma and pediatric hematological malignancies
Authors: Chen Yuyan , Takita Junko , Hiwatari Mitsuteru , Igarashi Takashi , Hanada Ryoji , Kikuchi Akira , Hongo Teruaki , Taki Tomohiko , Ogasawara Mizuho , Shimada Akira , Hayashi Yasuhide
Published: March 2006

PTPN11 has been identified as a causative gene in Noonan syndrome (NS), responsible for about 50% of cases of NS. Given the association between NS and an increased risk of some malignancies, notably leukemia and probably some solid tumors including neuroblastoma (NB) and rhabdomyosarcoma (RMS), recent studies have reported that gain‐of‐function somatic mutations in PTPN11 occur in some hematological malignancies, especially de novo juvenile myelomonocytic leukemia (JMML) and in some solid tumors such as NB, although at a low frequency. In a screen for mutations of PTPN11 in 7 cell lines and 30 fresh tumors of RMS and in 25 cell lines and 40 fresh tumors of NB, we identified a missense mutation (A72T) in an embryonal RMS patient. In the RMS samples, we also detected mutations of NRAS in 1 cell line and 1 patient; both mutations were in embryonal RMSs and had no PTPN11 mutations. No mutations of PTPN11 were detected in NB. In 95 leukemia cell lines and 261 fresh leukemia samples including 22 JMMLs, 9 kinds of missense mutations were detected in 17 leukemia samples, which included 11 (50.0%) mutations in JMML samples and lower frequencies in other hematological malignancies. Furthermore, we identified 4 (18.2%) NRAS mutations and 1 (4.5%) KRAS mutation in 5 JMML samples, 1 of which had a concomitant PTPN11 mutation. Our data suggest that mutations of PTPN11 as well as RAS play a role in the pathogenesis of not only myeloid hematological malignancies but also a subset of RMS malignancies. © 2006 Wiley‐Liss, Inc.
Geoarchaeological insights from Indian Sands, a Late Pleistocene site on the southern northwest coast, USA
Authors: Davis Loren G.
Published: March 2006

Geoarchaeological investigations of site 35CU67C at the Indian Sands locality, along Oregon's southern coast, provide many insights useful for considering various aspects of a Late Pleistocene coastal migration hypothesis. The geographic and geomorphic setting of terminal Pleistocene human occupation at Indian Sands provides important contextual examples that may aid in the discovery of other early coastal sites. During the Terminal Pleistocene, hunter–gatherers exploited naturally occurring sources of chert toolstone available at the Indian Sands locality.

Stratigraphic records at Indian Sands show changes in aeolian sedimentation, pedogenesis, and landscape evolution. Taken together, these records reflect the presence of nonanalogous Terminal Pleistocene paleoenvironmental conditions, suggesting a coastline much colder and drier than today. Developing paleoenvironmental proxy records from Pleistocene‐age terrestrial deposits in coastal settings will help improve our understanding of early coastal cultural ecology. © 2006 Wiley Periodicals, Inc.
Towards a better QALY model
Authors: Abellán‐Perpiñán José‐María , Pinto‐Prades José‐Luis , Méndez‐Martínez Ildefonso , Badía‐Llach Xabier
Published: March 2006

This paper presents a test of the predictive validity of various classes of QALY models (i.e. linear, power and exponential models). We first estimated TTO utilities for 43 EQ‐5D chronic health states and next these states were embedded in nonchronic health profiles. The chronic TTO utilities were then used to predict the responses to TTO questions with nonchronic health profiles. We find that thepower QALY modelclearly outperformslinearandexponential QALY models. Optimal power coefficient is 0.65. Our results suggest that TTO‐based QALY calculations may be biased. This bias can be corrected using apower QALY model. Copyright © 2006 John Wiley & Sons, Ltd.
Empirical implications of response acquiescence in discrete‐choice contingent valuation
Authors: Yeung Raymond Y. T. , Smith Richard D. , Ho Lai‐Ming , Johnston Janice M. , Leung Gabriel M.
Published: March 2006

The use of discrete‐choice contingent valuation (CV) to elicit individuals' preference, expressed as maximum willingness‐to‐pay (WTP), although primarily developed in environmental economics, has been popular in the economic evaluation of health and healthcare. However, a concern with this method is the potential for ‘over‐estimating’ WTP values due to the presence of response acquiescence, or ‘yea‐saying’ bias. Based on a CV survey conducted to estimate physicians' valuation of clinic computerization, the extent of such bias was estimated from a within‐sample open‐ended valuation question following the respondents' discrete choice response. Analysis of this data suggests that not only was response acquiescence an issue, but also that the parametric estimation of mean and median WTP, the most common approach to estimating WTP from discrete‐choice data, would potentially magnify such bias (to various degrees depending on the distributional assumptions applied). The possible extent of CV design versus analysis in discrete‐choice methods therefore warrants further exploration. Copyright © 2006 John Wiley & Sons, Ltd.
The role of economics in irrigation water management
Authors: Hellegers Petra J. G. J.
Published: March 2006

Economic literature and international conferences have extensively discussed the importance of treating irrigation water as an economic good, but there is still confusion about the role of economics in irrigation water management. Economics provides us with two contributions: analytical tools that help predict and interpret implications of various allocation procedures, and economic instruments that can assist in guiding users towards socially desirable outcomes. In this article the potential role of both contributions to improved irrigation water management is discussed, which is an extension of conventional work in this field. It becomes clear that, at this point in time, there is little empirical evidence of the effectiveness of economic instruments in irrigation water management. Economics mainly plays a role in understanding the implications of different procedures for allocating water, and guiding policymakers in defining appropriate allocation rules. Copyright © 2006 John Wiley & Sons, Ltd.
Functional characterization of human mesenchymal stem cells that maintain osteochondral fates
Authors: Romero‐Prado Marina , Blázquez Cristina , Rodríguez‐Navas Carmen , Muñoz Jaime , Guerrero Isabel , Delgado‐Baeza Emilio , García‐Ruiz Josefa P.
Published: March 2006

Adult stem cells are essential for tissue renewal, regeneration and repair, and their expansion in defined culture medium is on focus for regenerative medicine and genetic pathologies. The bone marrow has been shown to be very rich is pluripotent mesenchymal stem cells (MSCs) capable of forming bone, cartilage and also may give rise, to neurons and astrocytes in vivo and in vitro. MSCs can be isolated and expanded in culture, but human cells cannot be verified for a cartilage or a bone fate by transfer experiments. Accordingly, here we used different approaches to characterize hMSCs osteoblastic differentiation in vitro. hMSCs grown in culture in the presence of fetal bovine serum (FBS) expressed the bone‐specific transcription factor Runx2/AML3. When cells were incubated in osteoblastic differentiation medium, cells expressed transcripts belonging to the signaling of Indian HH‐PTHrP axis, GLI transcription factors, and bone target genes including osteopontin. The HH pathway proved to be functional since it induced cells to grow. Cells growing or differentiating to osteoblasts presented the Runx2/AML3 transcription factor, its partner CBFB, and Smad2/3 at the nuclei associated with the nuclear matrix. Furthermore, Runx2/AML3 was observed to co‐localize with SC35 to the nuclear intermediary filaments. These data support the notion that hMSCs isolated from human bone are or become bone progenitor cells upon culture. In the absence of FBS and in the presence of insulin or prolactin, cells show cytoskeletal organization and an AP‐1 transcription site activity resembling proliferative osteochondrocytes while cells in the presence of dexamethasone and added prolactin or TGF‐β resembled differentiated osteoblasts. These specific cellular conditions match those observed during endochondral bone formation. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
RETRACTED: Increased expression of LGI1 gene triggers growth inhibition and apoptosis of neuroblastoma cells
Authors: Gabellini Nadia. , Masola V. , Quartesan S. , Oselladore B. , Nobile C. , Michelucci R. , Curtarello M. , Parolin C. , Palù G.
Published: March 2006

The LGI1 gene has been implicated in the malignant progression of glioblastoma and it has also been genetically linked to a form of partial epilepsy (ADLTE). In this study, we investigated the relevance of LGI1 expression for neuroblastoma cells. The analysis of two cell lines (SH‐SY5Y and SK‐N‐BE) revealed unpredictably low levels of LGI1 and stable cell transfection with LGI1 cDNA yielded moderate increases of LGI1 expression. Neuroblastoma cell clones exhibited impaired cell growth and survival ability in relation to LGI1 levels. The process of growth inhibition could be discerned under experimental conditions of low cell density, since conditions of elevated cell density, which enhance the requirement for survival stimuli, resulted in massive cellular death. At high cell density, spontaneous apoptosis of LGI1 cells was clearly shown by the release of cytochrome c and apoptosis inducing factor (AIF) from mitochondria and by phosphatydil serine exposure and nuclear fragmentation. Activation of apoptotic effectors caspase‐3/7 also occurred, however, the broad caspase inhibitor Z‐VAD‐FMK substantially failed to block cell death. Thus the possibility that LGI1‐triggered apoptosis may involve initiator caspases linked to activation of death receptors, appears unlikely. The decreased ratio of Bcl‐2 to Bax suggests that apoptosis is initiated by the intrinsic mitochondrial pathway through the release of caspase‐dependent and ‐independent apoptogenic molecules. This study provides the first evidence that LGI1 controls neuronal cell survival, suggesting its role in the development of the nervous system in relation to the pathogenesis of neuroblastoma and ADLTE. J. Cell. Physiol. © 2006 Wiley‐Liss, Inc.
Cover Picture: Macromol. Chem. Phys. 5/2006
Authors: Bamford David , Dlubek Günter , Lüpke Thomas , Kilburn Duncan , Stejny Jarda , Menke Tammo J. , Alam M. Ashraf
Published: March 2006

Cover: Positron annihilation lifetime spectroscopy (PALS) is used to study n‐alkyl branching (C3, C4, C8) in polyethylene. It is found that the mean size of local free volumes, vh, increases linearly with the number and the length of n‐alkyl branches. A linear relation between vh and Tg is observed. Further details can be found in the Full Paper by D. Bamford, G. Dlubek,* T. Lüpke, D. Kilburn, J. Stejny, T. J. Menke, and M. A. Alam on page 492.
Mono‐components for decomposition of signals
Authors: Qian Tao
Published: March 2006

This note further carries on the study of the eigenfunction problem: Find f(t)=ρ(t)eiθ(t) such that Hf=−if, ρ(t)⩾0 and θ′(t)⩾0, a.e. where H is Hilbert transform. Functions satisfying the above conditions are called mono‐components, that have been sought in time‐frequency analysis. A systematic study for the particular case ρ≡1 with demonstrative results in relation to Möbius transform and Blaschke products has been pursued by a number of authors. In this note, as a key step, we characterize a fundamental class of solutions of the eigenfunction problem for the general case ρ⩾0. The class of solutions is identical to a special class of starlike functions of one complex variable, called circular H‐atoms. They are building blocks of circular mono‐components. We first study the unit circle context, and then derive the counterpart results on the line. The parallel case of dual mono‐components is also studied. Copyright © 2006 John Wiley & Sons, Ltd.
Single muscle fiber size and contractility after spinal cord injury in rats
Authors: Frontera Walter R. , Choi Howard , Krishnan Gomathi , Krivickas Lisa S. , Sabharwal Sunil , Teng Yang D.
Published: March 2006

Spinal cord injury (SCI) results in muscle weakness but the degree of impairment at the level of single fibers is not known. The purpose of this study was to examine the effects of T9–level SCI on single muscle fibers from the tibialis anterior of rats. Significant decreases in cross‐sectional area (CSA), maximal force (Po), and specific force (SF = Po/CSA) were noted at 2 weeks. Atrophy and force‐generating capacity were reversed at 4 weeks, but SF remained impaired. Maximum shortening velocity (Vo) did not change after injury. SCI thus appears to affect various contractile properties of single muscle fibers differently. Normal cage activity may partially restore function but new interventions are needed to restore muscle fiber quality. Muscle Nerve, 2006
Unmyelinated tactile afferents underpin detection of low‐force monofilaments
Authors: Cole Jonathan , Bushnell M. Catherine , McGlone Francis , Elam Mikael , Lamarre Yves , Vallbo Åke , Olausson Håkan
Published: March 2006

Human hairy but not glabrous skin has unmyelinated (C) tactile (CT) afferents that project to insular cortex. We studied two subjects with the rare sensory neuronopathy syndrome who lack A‐beta fibers but have relatively preserved C‐fiber function. Weak monofilaments were detected on hairy skin alone. Hence, the ability to detect light touch does not depend entirely on the A‐beta somatosensory system; CT afferents may contribute to the detection of weak monofilaments. Muscle Nerve, 2006
Obtaining online approximation algorithms for facility dispersion from offline algorithms
Authors: Rosenkrantz Daniel J. , Tayi Giri K. , Ravi S.S.
Published: March 2006

Facility dispersion problems arise in the context of placing obnoxious facilities and retail outlets. In the offline version of such a problem, the input consists of a complete graph on n nodes, a nonnegative weight (distance) for each edge, and the number k ⩽ n of facilities to be placed. The goal is to choose a facility placement consisting of k nodes so as to maximize a given measure of the distances among the facilities. Here, we consider an online version of the problem where the value of k is not known apriori; instead, requests for facilities arrive one at a time. It is also required that previously placed facilities cannot be moved or eliminated. Our main result is that for any objective that satisfies two properties, namely monotonicity and graceful degradation, any offline approximation algorithm with a performance guarantee ρ can be used to develop an algorithm with competitive ratio cρ for the online version, where c is a constant independent of the problem instance. Objectives for which our result applies include the average edge weight and average weight of a star subgraph. The result holds even when the edge weights do not satisfy the triangle inequality. We also identify dispersion objectives for which the offline and online versions have different behaviors when only one of the above two properties is satisfied. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 47(4), 206–217 2006
Mode‐I fracture behavior of carbon/epoxy plain‐weave composites containing double‐edge through‐the‐thickness cracks
Authors: Lee Dongyeon , Gowayed Yasser
Published: March 2006

A stress method to evaluate the stress intensity factor at the ends of a discontinuity contained by an orthotropic medium is developed. Unlike the classic stress method, of which determination of the stress intensity factor (SIF) is largely dependent on data collected from singularity‐dominated zone, the proposed stress method is based on a stress expression in the form of multiterm expansion, including two higher‐order terms. By adopting higher‐order terms, far‐field effect can be taken into consideration. Carbon/epoxy plain‐weave textile composites are prepared and tensile‐tested with double‐edge notched (DEN) configuration. Effective crack length (a/W) ranges from 0.064 to 0.624. Prediction of the proposed model matches the definition, $\sigma_{\infty}\sqrt{\pi a}$, with errors less than 5% for 0.064 < a/W < 0.402, whereas errors are reported up to 45.78% for 0.413 < a/W < 0.624. It is postulated that the errors beyond a/W = 0.4 results from finite geometry and interaction between cracks. A strain‐gage test is carried out to verify the proposed stress method, utilizing two strain gages to realize the three‐parameter strain gage method. The test result exhibits good agreement with the proposed method. POLYM. COMPOS. 27:213–220, 2006. © 2006 Society of Plastics Engineers
Synthesis and properties of epoxy/TiO2 composite materials
Authors: Huang K. S. , Nien Y. H. , Chen J. S. , Shieh T. R. , Chen J. W.
Published: March 2006

Epoxy/TiO2 composites were prepared by solution mixture method, in which epoxy resin and nano‐TiO2 liquid were mixed in the presence of methyl isobutylketone. According to the experimental results, hydrogen bonds can be formed by mixing TiO2 particles and epoxy resin. The SEM analysis suggests that TiO2 particles are uniformly distributed within the material, while some silver streaks occur at the surface of materials. Besides, thermo‐resistance and mechanical property of materials are found to improve with the addition of TiO2, but degrades if the nano‐TiO2 is the excess of 3%. Furthermore, these properties can be improved with the increasing concentration of methyl isobutylketone. POLYM. COMPOS., 27:195–200, 2006. © 2006 Society of Plastics Engineers.
Preparation of conductive polyaniline/epoxy composite
Authors: Yang Qinghao , Wei Shenggui , Cheng Guangxu
Published: March 2006

Conductive PANI (polyaniline)/epoxy composites were prepared by curing of the premix of PANI, which was synthesized in a multiple sulfonic acid system containing toluenesulfonic acid and dodecylbenzenesulfonic acid, and epoxy resin with methyl tetrahydrogen phenyl anhydride/triethylamine. The effects of the loadings of the curing agent, the accelerants as well as their types, and the PANI on the conductivities of the composites were studied. With increasing loadings of curing agent, conductivities of the composites increased first and decreased then, which is a synergistic effect of the PANI loading and its doping states. Under relatively lower loading of accelerant, conductivities of the composites increased with increase of PANI loading, whereas with higher loading of accelerant, the conductivities were affected by both the PANI and the accelerant loadings. Conductivity as high as 3 × 10−5 S/cm was achieved for curing of the composite containing 7.5 wt% of PANI and 4 wt% of accelerant at 80°C, which is suffice in application of electrostatic discharging. POLYM. COMPOS. 27:201–204, 2006. © 2006 Society of Plastics Engineers
Profile extrusion and mechanical properties of crosslinked wood–thermoplastic composites
Authors: Bengtsson Magnus , Oksman Kristiina , Stark Nicole M.
Published: March 2006

Challenges for wood‐thermoplastic composites to be utilized in structural applications are to lower product weight and to improve the long‐term load performance. Silane crosslinking of the composites is one way to reduce the creep during long‐term loading and to improve the mechanical properties. In this study, silane crosslinked wood‐polyethylene composites were produced by reactive extrusion and subsequently manufactured into rectangular profiles. The silane crosslinked composites were stored in a sauna at 90 °C to increase the degree of crosslinking. The toughness of the silane crosslinked composites was significantly higher than for the non‐crosslinked composites. Improved adhesion between the wood and polyethylene phases is most likely the reason for the improved toughness of the crosslinked composites. There was no significant difference in flexural modulus between the crosslinked and non‐crosslinked composites. In addition, impact testing showed that the impact strength of the crosslinked composites was considerable higher (at least double) than the non‐crosslinked. The effect of temperature on the impact strength of the composites indicated slightly higher impact strength at −30 °C than at 0° and at 25 °C, and then an incrase in impact strength at 60 °C. Crosslinking also reduced the creep response during short‐term loading. Moreover, scanning electron microscopy on the fracture surface of the crosslinked composites revealed good adhesion between the polyethylene and wood phases. POLYM. COMPOS. 27:184–194, 2006. © 2006 Society of Plastics Engineers
Fluorinated and oxyfluorinated short Kevlar fiber‐reinforced ethylene propylene polymer
Authors: Mukherjee M. , Das C.K. , Kharitonov A.P.
Published: March 2006

The thermomechanical behavior of fluorinated and oxyfluorinated Kevlar fiber‐reinforced ethylene propylene (EP) composites has been studied. The composites have been prepared using brabender mixer and are cured using compression molding technique. FTIR study has been performed to understand the chemical reaction occurred due to modification of composites. Thermal behavior and crystallinity have been studied by DSC, TGA, DMTA, and XRD. These studies show that thermal stability, storage modulus, as well as crystallinity of the treated Kevlar fiber‐reinforced EP increases in comparison to the untreated derivative because the surface‐modified Kevlar fiber results in good adhesion between the fiber surface and EP matrix. Tensile strength increases in case of treated Kevlar fiber‐reinforced EP in comparison to the untreated one. SEM study supports all the above results. AFM results show that surface roughness increases because of the surface modification resulting from the incorporation of functional group‐induced Kevlar fiber. Polym. Compos. 27:205–212, 2006. © 2006 Society of Plastics Engineers
Preparation and characterization of mesoporous silica thin films from polyethoxysiloxanes
Authors: Gunji Takahiro , Shimano Ryosuke , Arimitsu Koji , Abe Yoshimoto
Published: March 2006

Tetraethoxysilane (TEOS) and polyethoxysiloxanes (PEOSs; prepared by the acid‐catalyzed hydrolytic polycondensation of TEOS) were subjected to the sol–gel process in the presence of cetyltrimethylammonium bromide (CTAB), respectively. The PEOSs with Mw 700–26,000, as prepared by sol–gel coating of TEOS and PEOS under various conditions, were used. Uniform and crack‐free thin films of thickness 276–613 nm were prepared by spin‐coating of a PEOS solution containing CTAB. When the coating films were sintered at 400 °C, the combustion of ethoxy groups and CTAB took place to provide porous silica thin films. The structure of the thin films was found to be dependent on the molecular weight of PEOS and the molar ratio of CTAB/Si: lamellar or hexagonal phase was observed for Mw less than 15,000 and for CTAB/Si molar ratios greater than 0.10. Honeycomb structures were observed for Mw less than 5000 and for CTAB/Si molar ratios of 0.15. The honeycomb structure was also observed by atomic force microscopy and transmission electron microscope. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2542–2550, 2006
Effect of iodine on morphology changes of spray deposited nanocrystalline CdSe:I, CdTe:I and HgTe:I thin films
Authors: RangaRao A. , Dutta V.
Published: March 2006

The low‐temperature preparation of nanofibres and nanotubes in iodine‐doped CdX (X = Se, Te) and HgTe thin films is reported. Iodine was used as an n‐type dopant in CdX and HgTe. The films were deposited on glass substrates at 200 °C by spray deposition of iodine‐doped nanoparticles prepared using a solvothermal method. The surface morphology of iodine‐doped CdX films shows the formation of nanofibers and that of iodine‐doped HgTe films shows the formation of nanotubes ∼4 µm long with an average diameter of ∼45 nm. Selected‐area diffraction patterns show the formation of cubic HgTe nanotubes with lattice parameter a = 0.6467 nm. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Doping effects of a nano‐nitride layer at the interfaces of a NiO/Co/Cu/Co/Cu structure
Authors: Zhao Z. C. , Wang H. , Xiao S. Q. , Zhong X. X. , Gu Y. Z. , Xia Y. X. , Jin Q. Y. , Wu X. S.
Published: March 2006

NiO/Co/Cu/Co/Cu spin valves with a doped nano‐nitride layer (NNL) at different interfaces have been investigated. The positions of the NNL have a significant influence on magnetoresistance (MR). When the NNL is doped at the top interface with the resulting structure of NiO/Co/Cu/Co/NNL/Cu, the MR is higher than that of the non‐doped structure, while MR becomes relatively small when the NNL is doped at the bottom interface between NiO and Co. A detailed analysis is given. This study might be considered as useful for furthering understanding of how to tailor MR with NNLs. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mg‐doped AlGaN grown on an AlN/sapphire template by metalorganic chemical vapour deposition
Authors: Yu Hongbo , Strupinski Wlodek , Butun Serkan , Ozbay Ekmel
Published: March 2006

The growth of high‐performance Mg‐doped p‐type Alx Ga1–x N (x = 0.35) layers using low‐pressure metalorganic chemical vapour deposition on an AlN/sapphire template is reported. The influence of growth conditions on the p‐type conductivity of the Alx Ga1–x N (x = 0.35) alloy was investigated. It was found that the p‐type resistivity of the AlGaN alloy demonstrates a marked dependence on the Mg concentration, V/III ratio and group III element flow rate. A minimum p‐type resistivity of 3.5 Ω cm for Alx Ga1–x N (x = 0.35) epilayers was achieved. A Ni/Au (10 nm/100 nm) ohmic contact was also fabricated and a specific contact resistivity of 8.1 × 10–2 Ω cm2 was measured. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear absorption in silicon and the prospects of mid‐infrared silicon Raman lasers
Authors: Raghunathan Varun , Shori Ramesh , Stafsudd Oscar M. , Jalali Bahram
Published: March 2006

We present the first experimental results of nonlinear absorption in silicon at the mid infrared wavelengths. Nonlinear losses due to two‐photon and free‐carrier absorption that are found to degrade near infrared silicon Raman devices become negligible at photon energies less than half the bandgap (i.e., λ > 2.2 µm in wavelength). Moreover, the low loss window for linear absorption in silicon extends from 1.2 to 6.5 µm. These factors along with the excellent thermal conductivity and high optical damage threshold renders silicon an ideal material for building Raman lasers and amplifiers that operate in the mid infrared wavelengths. This new technology will expand the application space of silicon photonics beyond data communication and into biochemical sensing, laser medicine, and LIDAR. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the nonmagnetic impurities on the spin‐1 Heisenberg chain SrNi2V2O8 system
Authors: Giapintzakis J. , Androulakis J. , Syskakis E. , Papageorgiou Th. P. , Apostolopoulos G. , Thanos S. , Papastaikoudis C.
Published: March 2006

Dc‐magnetization and heat capacity measurements on polycrystalline samples of SrNi2–x Mgx V2O8 (x = 0 and 0.05) are reported. The magnetization data suggest that both compounds are S = 1 quasi one‐dimensional Heisenberg antiferromagnets. The substitution of non‐magnetic impurity Mg2+ ions for Ni2+ induces a magnetic phase transition at ∼3.7 K. A simple Hamiltonian model is proposed for these systems giving good quantitative agreement with the experimental magnetization data. The intrachain magnetic exchange constant (J 1/k B) and the Haldane gap (Δ ) for both compounds are estimated to be ∼105 K and ∼58.3 K (5.02 meV), respectively. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature dependence effective activation energy in Tl2Ba2CaCu2O8 thin film
Authors: Liu S. L. , Wu G. J. , Shan L. , Wu J. , Xu X. B. , Jin X. , Shao H. M.
Published: March 2006

By considering the competition of thermal activation and effective pinning, a general description of temperature dependence resistivity under magnetic fields has been deduced on high temperature superconductors. The temperature dependence resistivity is a function of the energy ratio of thermal actviation and pinning. Based on vortex glass phase transition analysis, the temperature dependence activation energy can be obtained from the resistivity transition under magnetic fields. It is found that the activation energy can be scaled onto a single parabola. The experiments on Tl‐2212 thin film and other superconductors support our model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect contributions to conductivity in poly(3‐hexylthiophene)?
Authors: Caruso A. N. , Feng D.‐Q. , Losovyj Ya. B. , Schulz D. L. , Balaz Snjezana , Rosa Luis G. , Sokolov A. , Doudin B. , Dowben P. A.
Published: March 2006

We find evidence for a gradual change in the electronic properties of spin coated poly(3‐hexylthiophene) thin films with temperature. The conduction properties appears to be mediated by hopping conduction dominated by a low density of defects states within the highest occupied molecular orbital to lowest unoccupied molecular orbital gap, not by a change in band gap. The photoemission and transport measurements indicate a loss of charge mobility or carrier concentration occurs with decreasing temperature, while the molecular configuration (through chain conjugation) also changes with temperature. The defects states identified by photoemission (–1.7 eV) as well as others contributing to the transport properties are believed to be very heterogeneous along the polymer backbone. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
X‐ray absorption and luminescence properties of metallic copper nanoparticles embedded in a glass matrix
Authors: Roqué J. , Poolton N. R. J. , Molera J. , Smith A. D. , Pantos E. , Vendrell‐Saz M.
Published: March 2006

A new method of ion‐exchange between raw compounds containing copper oxide and alkali glasses has been used to grow copper nanoparticles within a glass matrix, forming a metal–glass nanocomposite that is the structure on which both ancient and modern lustre glazes are based. When excited by X‐rays at 300 K, two dominant emission bands appear in the material in the visible region, peaking at 2.60 eV and 1.98 eV. Synchrotron radiation methods are deployed that enables the luminescence and structural properties of the nanocomposite to be interlinked. Standard Extended X‐ray Absorption Fine Structure (EXAFS) shows that both metallic copper and copper oxide local sites structure are present in the glass matrix, and the detailed atomic arrangement of each are derived; however, the method provides no information as to whether either structures are actually involved in the luminescence processes. In order to provide this direct link, Optically Detected X‐ray Absorption Spectroscopy (OD‐XAS) has been deployed, and this provides strong evidence that copper metal nanoparticles are responsible for the red emission. The method also shows that the X‐ray absorption processes of the metal particles and silicate lattice (that result in the red and blue emissions respectively) are distinctly different. This is the first report of OD‐XAS involving metallic nanoparticles, and opens the possibility of using the method more generally for metal nanoparticle research. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
ONETEP: linear‐scaling density‐functional theory with local orbitals and plane waves
Authors: Haynes Peter D. , Skylaris Chris‐Kriton , Mostofi Arash A. , Payne Mike C.
Published: March 2006

An overview of the ONETEP (Order‐N Electronic Total Energy Package) code is presented, focusing on the twin aims of overall linear scaling and controlled accuracy. The method is outlined, including a description of the density‐matrix formulation of density‐functional theory, and the optimisation procedures for both the density‐kernel and the local orbitals or non‐orthogonal generalised Wannier functions. Results of applying the method to a variety of systems are presented to demonstrate the accomplishment of the original aims. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Population inversion, temperature, and photon distributions of the generalized fermionic Ising ferromagnetic model: Path‐integral representation of the spin system
Authors: Grinberg Horacio
Published: March 2006

The quantum partition function and the emerging energy of a fermionic Ising ferromagnetic model involving all possible interactions (generalized Ising model) are obtained from an appropriate tracing of the analytic propagator path integral over Grassmann variable coherent nonorthogonal states in the imaginary time domain. The dynamics derived from the interaction of this system with a single‐mode cavity field in the rotating wave approximation is investigated for nonresonant states within the framework of the Jaynes–Cummings two‐level model consisting of the vacuum state and a thermally averaged manifold of excited states. Time evolution of the population inversion is computed in the nanosecond time scale, assuming that the initial coherent state of the field is given by a Poisson distribution. The limit of high temperatures characterizing the manifold of excited states becomes chaotic with rapid oscillations, whereas the ground state is described correctly in the thermodynamic limit by the vacuum state. A breakup is seen in the photon distribution into a series of peaks because of the detuning between the spin system and the field. However, this structure is smeared out, and the general shape is preserved in the computation emerging from the Laplace transform of the photon distribution. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Conjugated chemical trees with minimal energy and prescribed diameter
Authors: Ou Jianping
Published: March 2006

The energy of a molecular graph G is defined as the sum of the absolute values of the eigenvalues of A(G), where A(G) is the adjacency matrix of this graph. This article characterizes conjugated chemical trees with prescribed diameter and minimal energies and presents explicit expressions of their Hosoya indices. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Severe acute respiratory syndrome (SARS) coronavirus: application of monoclonal antibodies and development of an effective vaccine
Authors: Tsunetsugu‐Yokota Yasuko , Ohnishi Kazuo , Takemori Toshitada
Published: March 2006

SARS‐CoV is a new type of human coronavirus identified as a causative agent of severe acute respiratory syndrome (SARS). On the occasion of the SARS outbreak, various monoclonal antibodies (mAbs) against SARS‐CoV have been developed and applied for diagnosis, clinical management and basic research. In this review, we overview the biochemical and functional properties and applications of these SARS‐CoV mAbs. We also focus on a variety of vaccines currently under development and discuss the immune response elicited by these vaccines in animal models, hopefully to better understand what we need to do next to fight against newly emerging pathogens in the future. Copyright © 2006 John Wiley & Sons, Ltd.
Gain‐scheduled H∞ filtering of parameter‐varying systems
Authors: Zhou Shaosheng , Zhang Baoyong , Xing Zheng Wei
Published: March 2006

This paper deals with the gain‐scheduled H∞ filtering problem for a class of parameter‐varying systems. A sufficient condition for the existence of a gain‐scheduled filter, which guarantees the asymptotic stability with an H∞ noise attenuation level bound for the filtering error system, is given in terms of a finite number of linear matrix inequalities (LMIs). The filter is designed to be parameter‐varying and have a nonlinear fractional transformation structure. A numerical example is presented to demonstrate the application of the proposed method. Copyright © 2006 John Wiley & Sons, Ltd.
Energizing the island community: a review of policy standpoints for energy in small island states and territories
Authors: Stuart E. Kathy
Published: March 2006

Small island states and island territories of larger countries tend to have ample renewable energy potential from sun, wind, waves, biomass and other sources. Nevertheless, they rely heavily on fossil fuels to generate electricity. Fluctuations in fossil fuel prices may impact significantly upon small island economies. This paper aims to help researchers and decision‐makers better understand the unique features of small islands in relation to the power industry. The paper identifies public policy influencing production of electricity and limitations to energy policy reform in small islands. A range of conventional and renewable energy options available to small island policy‐makers is presented using anecdotal evidence. It is argued that small islands need to build upon their energy resource potentials and by this exert more control over their energy futures. The paper concludes by recommending holistic strategies that small islands can use to enhance their long‐term energy security and sustainability. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
Teaching nature of science explicitly in a first‐grade internship setting
Authors: Akerson Valarie L. , Volrich Morgan L.
Published: March 2006

This case study focused on a preservice teachers' (Morgan) efforts to explicitly emphasize nature of science (NOS) elements in her first‐grade internship classroom. The study assessed the change in first grade students' views of the inferential, tentative, and creative NOS as a result of the explicit instruction. Morgan held appropriate views of NOS, had the intention and motivation to teach NOS, and had a supporting experience explicitly emphasizing NOS embedded in physics content to peer college students. Data sources included weekly classroom observations of explicit NOS science lessons taught by Morgan, interview of Morgan to determine that her views of NOS were informed and that she would have the NOS content knowledge to teach in line with recommended reforms, and interviews of the first‐grade students pre‐ and postinstruction to determine the influence of Morgan's instruction on their views of observation and inference, the tentative NOS, and the creative and imaginative NOS. Data were analyzed to determine (a) the approaches Morgan used to emphasize NOS in her instruction, and (b) students' views of NOS pre‐ and postinstruction to track change in their views. It was found that Morgan was able to explicitly emphasize NOS using three teacher‐designed methods, and that the influence on student views of the inferential, tentative, and creative NOS was positive. Implications for teacher development are provided. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 43: 377–394, 2006
Adenylyl cyclase signaling mechanisms of relaxin and insulin action: Similarities and differences
Authors: Pertseva Marianna , Shpakov Alexander , Kuznetsova Ludmila , Plesneva Svetlana , Omeljaniuk Evgeniya
Published: March 2006

The adenylyl cyclase signaling mechanism (ACSM) of relaxin H2 action was discovered and deciphered in mammalian muscles. A study of signaling blocks involved in ACSM of relaxin in comparison with that of insulin previously detected showed a close similarity throughout the post‐receptor signaling chain of both hormones. The inhibitory action of tyrosine kinase blockers on the hormone AC activating effect indicates that the relaxin receptor involved in ACSM is likely to be of the tyrosine kinase type. However, a recent discovery of a relaxin receptor with serpentine architecture leaves open the question concerning the existence of receptor of the tyrosine kinase type. The structural‐functional organization of the ACSM due to the action of relaxin—shown here for the first time—can be presented as the following signaling sequence: relaxin receptor ⇒ Gi protein (βγ‐dimer) ⇒ phosphatidylinositol 3‐kinase ⇒ protein kinase Cζ ⇒ Gs protein ⇒ adenylyl cyclase. According to our hypothesis, the regulatory action of the insulin superfamily peptides on cell processes (proliferation, apoptosis, and metabolism) is mediated via ACSM.
Stabilization of hypoxia inducible factor rather than modulation of collagen metabolism improves cardiac function after acute myocardial infarction in rats
Authors: Philipp Sebastian , Jürgensen Jan Steffen , Fielitz Jens , Bernhardt Wanja M. , Weidemann Alexander , Schiche Astrid , Pilz Bernhard , Dietz Rainer , Regitz‐Zagrosek Vera , Eckardt Kai‐Uwe , Willenbrock Roland
Published: March 2006

Prolyl hydroxylase domain‐containing enzymes (PHD) hydroxylate a proline residue that controls the degradation of hypoxia inducible factor (HIF). Hypoxia inhibits this hydroxylation thus increasing HIF levels. HIF is upregulated in ischemic tissues, growing tumors and in nonischemic, mechanically stressed myocardium. Pharmacological inhibition of prolyl 4‐hydroxylase (P4‐H) stabilizes HIF‐protein in vitro and may modulate collagen turnover. The aims of this study were to investigate whether inhibition of P4‐H protects myocardium against ischemia, and whether the observed effects are related to modulation of collagen metabolism or due to the stabilization of HIF.

Methods:

Rats were treated with a specific P4‐H inhibitor (P4‐HI) or vehicle starting 2 days before induction of myocardial infarction (MI). Rats were investigated 7 or 30 days after MI. Induction of HIF‐1α and −2α was visualized by immunohistochemistry. Expression of growth factors (connective tissue growth factor, Osteopontin) and mRNA expression and protein levels of Collagen I and III as well as HIF‐2α were measured.

Results:

P4‐HI augments HIF in the myocardium as early as 24 h after treatment. P4‐HI did not alter the MI‐induced enhanced expression of growth factors and collagen. Treatment with P4‐HI significantly reduced heart and lung weight, improved left ventricular contractility, prevented left ventricular enlargement and improved left ventricular ejection fraction without affecting infarct size after 30 days.

Conclusions:

Specific inhibition of the P4‐H improved cardiac function without affecting the infarct size after experimental myocardial infarction in rats. Stabilization of HIF rather than inhibition of collagen maturation by P4‐HI may prevent cardiac remodeling after MI.
Influence of cardiac‐resynchronization therapy on heart rate and blood pressure variability: 1‐year follow‐up
Authors: Piccirillo Gianfranco , Magrí Damiano , di Carlo Silvia , De Laurentis Tiziana , Torrini Alessia , Matera Sabrina , Magnanti Marzia , Bernardi Leda , Barillà Franco , Quaglione Raffaele , Ettorre Evaristo , Marigliano Vincenzo
Published: March 2006

Background:

Several studies have shown that cardiac‐resynchronization therapy (CRT) improves haemodynamic function, cardiac symptoms, and heart rate variability (HRV) and reduces the risk of mortality and sudden death in subjects with chronic heart failure (CHF). In subjects with CHF, power spectral values for the low‐frequency (LF) component of RR variability ≥13 ms2, are associated with an increased risk of sudden death.

Aims and methods:

To assess whether spectral indexes obtained by power spectral analysis of HRV and systolic blood pressure (SBP) variability could predict malignant ventricular arrhythmias in patients with severe CHF treated with an implantable cardioverter–defibrillator (ICD) alone or with ICD+CRT. In addition, changes in non‐invasive spectral indices using short‐term power spectral analysis of HRV and SBP variability during controlled breathing in 15 patients with CHF treated with an ICD alone and 16 patients receiving ICD+CRT, were assessed pre‐treatment and at 1 year.

Results:

Arrhythmias necessitating an appropriate ICD shock were more frequent in subjects who had low LF power. CRT improved all spectral components, including LF power.

Conclusions:

Low LF power values predict an increased risk of malignant ventricular arrhythmias; after 1 year of CRT most non‐spectral and spectral data, including LF power, improved. Whether these improvements lead to better long‐term survival in patients with CHF remains unclear.
Holocene environmental change and vegetation contraction in the Sonoran Desert
Authors: McAuliffe Joseph R. , McDonald Eric V.
Published: March 2006

Two types of microtopographic features (plant scar mounds and plant scar depressions) on surfaces of barren desert pavements provide a unique record of the former presence of large perennial plants. Evidence of bioturbation by burrowing animals extends more than 1 m beneath each type of plant scar, indicating that both features originated as large bioturbation mounds. Formation of bioturbation mounds in desertscrub environments is generally restricted to areas beneath widely separated, large perennial plants. The contrasting forms of plant scars (mounds vs. depressions) represent time-dependent changes following disappearance of the large plants and eventual cessation of bioturbation. Plant scar mounds represent a geologically recent episode of plant mortality, whereas plant scar depressions represent the disappearance of plants at a considerably earlier time, possibly at the Pleistocene–Holocene transition. Contrasting spatial distributions of the two kinds of plant scars indicate that vegetation on alluvial fans has progressively contracted from a more diffuse, former vegetation cover, yielding the wide, barren pavement surfaces present today. In less arid portions of the Sonoran Desert, spatial distribution of recent plant mortality due to persistent, severe drought provides an analog of the progressive loss of plants from different parts of the landscape in the past.
Detecting changes in epiphytic lichen communities at sites affected by atmospheric ammonia from agricultural sources
Authors: WOLSELEY Patricia A. , JAMES Peter W. , THEOBALD Mark R. , SUTTON Mark A.
Published: March 2006

Lichens were recorded on Quercus petraea trunks and twigs near ammonia recording stations in ‘continental’ Norfolk, and ‘oceanic’ Devon in order to test indicator values developed for epiphytic lichens in areas of high atmospheric ammonia in the Netherlands. Lichens on trunks in Norfolk showed a similar correlation of nitrophyte indices with ammonia concentration and bark pH as those in Holland, whereas in Devon there was no correlation with nitrophyte indices on trunks and a negative correlation with acidophyte indices. Results on twigs in both sites suggest that lichens on twigs respond more rapidly to recent changes in ammonia concentrations while trunks may maintain relict lichen communities due to either a legacy of previous acidification or ecological continuity. The results suggest that loss of acidophytes is taking place prior to the establishment of nitrophytes indicating the importance of establishing levels of ammonia at which sensitive communities are at risk.