bluuebunny/crossref_metadata_2025 huggingface dataset:
Polyethylene‐Montmorillonite Nanocomposites: Preparation, Characterization and Properties
Authors: Cui Liqiang , Cho Hyun Yong , Shin Joong‐Won , Tarte Naresh Hiralal , Woo Seong Ihl
Published: January 2008

Polyethylene(PE)/clay nanocomposites have been successfully prepared by in situ polymerization with an intercalation catalyst titanium‐montmorillonite (Ti‐MMT) and analyzed by X‐ray diffraction analysis (XRD), Fourier transform infrared analysis (FT‐IR), Transmission electron microscopy (TEM), differentail scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and tensile testing. XRD and TEM indicate that the clay is exfoliated into nanometer size and disorderedly dispersed in the PE matrix, and the PE crystallinity of PE/clay nanocomposite declines to 15∼30%. Compared with pure PE, PE/clay nanocomposites behave higher thermal, physical and mechanical properties; the layer structure of the clay decreases the polymerization activity and produce polymer with a high molecular weight. For PE/clay nanocomposites, the highest tensile strength of 33.4 MPa and Young's modulus of 477.4 MPa has been achieved when clay content is 7.7 wt %. The maximum thermal decomposition temperature is up to 110 °C higher, but the thermal decomposition temperature of the PE/clay nanocomposites decreases with the increases of the clay contents in the PE matrix.
Growth and Evolution of Particle Morphology: An Experimental & Modelling Study
Authors: McKenna Timothy F. L.
Published: January 2008

In order to fully understand the crucial issues of how particles grow during olefin polymerisation, how the morphology evolves, how fines are formed, as well as related key issues it is necessary to develop more sophisticated single particle models than those currently available. Such models should ideally allow us to calculate how force, or stress, develops and is released in the growing polymer particles. However, it is shown that before such models can be developed with confidence, it is necessary to develop experimental techniques that allow us to study particle growth under precise conditions. Parallel development of well‐adapted experimental techniques and well‐conceived models is proving to be a useful means of achieving the above‐mentioned goals.
The Advantages of Metal Complexes as Catalysts toward Polyolefins ‐ The Vinyl Polymerization of Norbornene
Authors: Shi Qisong , Jie Suyun , Zhang Shu , Yang Haijian , Sun Wen‐Hua
Published: January 2008

Various nickel complexes bearing [N,O], [P,N] ligands as well as the supported nickel complexes were prepared and showed moderate to high catalytic activities for vinyl polymerization of norbornene. The formed polynorbornenes (PNBs) are soluble for measuring both the molecular weights and the molecular weight distributions. Comparing the results in homogeneous catalysis, the PNBs produced by supported catalysts possessed higher molecular weights and slightly broader molecular weight distributions. The reactor fouling generally happens in homogeneous catalytic systems, while spherical polymer particle morphology could be obtained without reactor fouling by using MgCl2‐supported nickel catalysts.
Development of an Unsteady‐State Model for Control of Polymer Grade Transitions in Ziegler‐Natta Catalyzed Reactor Systems
Authors: Rawatlal Randhir , Tincul Ioan
Published: January 2008

The dynamics of the activity and polymer growth in Ziegler‐Natta catalysts has been well established in the literature.1,2 The corresponding dynamic behaviour of the reactor system is predicted using a segregation model approach and the unsteady state model of residence time distribution previously developed.3 The model is therefore able to predict reactor performance for a time‐varying catalyst flow rate through the reactor, as well as time‐varying concentrations of monomer, co‐catalyst and chain termination agent. A method of determining grade transition policies by the use of the developed reactor models is then presented. It is demonstrated that the reactor productivity, catalyst efficiency, average chain length and polydispersity can be controlled by the catalyst flow rate and reactor monomer and hydrogen concentrations. The relationship between the required polymer product properties and the system flow rates is determined. Case studies are presented that evaluate various transition strategies for a specific polymer grades.
An Empirical Correction Term to Density Functional Theory for the Description of the TiCl4‐Lewis Base Complexes
Authors: Cavallo Luigi , Fedele Rosalisa , Morini Giampiero , Ducéré Jean‐Marie , Melchior Andrea , Correa Andrea , Piemontesi Fabrizio , Tolazzi Marilena
Published: January 2008

Calorimetric and computational investigation on the interaction of TiCl4 with some Lewis bases (esters and ethers) is presented. The bases were chosen for their relevance in heterogeneous Ziegler‐Natta polymerization of propene. Comparison of the theoretical data with the calorimetric data indicates that calculations consistently underestimate the experimental binding energies. In light of this consistency, we propose that an empirical correction term added to the theoretical binding energies could represent an empirical solution for the prediction of the TiCl4/donor binding energies with reasonable accuracy.
Synthesis of Titanatranes Containing Bis(aryloxo)‐(alkoxo)amines and their Use in Catalysis for Ethylene Polymerization
Authors: Padmanabhan Sudhakar , Wang Wei , Katao Shohei , Nomura Kotohiro
Published: January 2008

Syntheses of titanatranes containing [(O‐2,4‐Me2C6H2‐6‐CH2)2‐{O(CH2)nCH2}]N3− (n = 1,2) have been explored. Catalytic activity for ethylene polymerization by Ti2(OiPr)2{[(O‐2,4‐Me2C6H2‐6‐CH2)2(µ2‐OCH2‐CH2)]N}2 (1a) ‐ MAO catalyst increased at high temperature; the activity also increased upon addition of AlMe3. Ti(O‐ 2,6‐iPr2C6H3){[(O‐2,4‐Me2C6H2‐6‐CH2)2(OCH2CH2)]N} (1c) showed higher activity than 1a under the same conditions. Ti{[(O‐2,4‐Me2C6H2‐6‐CH2)2(HOCH2CH2CH2)]N}2 was isolated from the reaction of Ti(OiPr)4 with bis(2‐hydroxy‐3,5‐dimethylbenzyl)‐propanolamine; the structure was determined by X‐ray crystallography.
A Flat Model Approach to Tethered Bis(imino)pyridyl Iron Ethylene Polymerization Catalysts
Authors: Han Wei , Niemantsverdriet Hans (J.W.) , Thune Peter C.
Published: January 2008

A surface science model for a silica supported bis(imino)pyridyl iron complexes is applied to reveal the surface chemistry of these heterogeneous polymerization catalysts. The polymerization activity of these models and the molecular weight distribution of the resulting polymer are comparable to similar catalysts supported on amorphous silica. The catalyst deactivates partially during the first hour of ethylene polymerization. Based on photoelectron spectroscopy (XPS) we attribute this deactivation to iron extrusion by the aluminium alkyl activator.
Octahedral Complexes in the Polymerization of α‐Olefins
Authors: Aharonovich Sinai , Volkis Victoria , Eisen Moris S.
Published: January 2008

Summary: A series of dimethyl titanium benzamidinate complexes has been prepared containing various functional groups at the aromatic ring. These functional groups were selected to study their electronic or steric effects at the cationic metal center in the polymerization of propylene. Quantitative structure activity relationship (QSAR) studies showed that a linear relationship is observed only for the Taft Parameter (Es). Mono‐ and bis‐benzamidinate complexes were found to produce similar polymers indicating that alike active species are obtained regardless of the starting complex. Deuterium labeled 2‐D‐propene showed that a new epimerization mechanism for this type of complexes is operative.
Hydrogen Effects for Propylene Polymerization with Ultra Low TiCl3 Loading MgCl2‐Supported Catalyst
Authors: Kouzai Iku , Wada Tooru , Taniike Toshiaki , Terano Minoru
Published: January 2008

Hydrogen effects for propylene polymerization were investigated with ultra low TiCl3 loading MgCl2‐supported catalysts in which the electric states of Ti species can be almost uniform. Hydrogen did not affect the catalyst activity, while the efficiency of hydrogen as a chain transfer agent was found to depend on the Ti content of the catalyst and the stereospecificity of the polymerization sites: Hydrogen was effective for isospecific sites independent of Ti contents, but inert for aspecific sites only at the extremely low Ti content. These results were explained within the island model, where isospecific sites may be located in the islands with other Ti species in their surroundings acting, as a steric hindrance for isospecific polymerization and as hydrogen dissociation sites after deactivation. Most of the aspecific sites should be isolated only at the extremely low Ti content. These isolated sites have no other Ti species in their surroundings, i.e. no hydrogen dissociation sites, and are inert to hydrogen.
Huntington's disease phenocopies are clinically and genetically heterogeneous
Authors: Wild Edward J. , Mudanohwo Ese E. , Sweeney Mary G. , Schneider Susanne A. , Beck Jon , Bhatia Kailash P. , Rossor Martin N. , Davis Mary B. , Tabrizi Sarah J.
Published: January 2008

Huntington's disease (HD) classically presents with movement disorder, cognitive dysfunction and behavioral problems but is phenotypically variable. One percent of patients with HD‐like symptoms lack the causative mutation and are considered HD phenocopies. Genetic diseases known to cause HD phenocopies include HD‐like syndromes HDL1, HDL2, and HDL4 (SCA17). HD has phenotypic overlap with dentatorubral‐pallidoluysian atrophy, the spinocerebellar ataxias and neuroferritinopathy. Identifying the genetic basis of HD phenocopies is important for diagnosis and may inform the search for HD genetic modifiers. We sought to identify neurogenetic diagnoses in the largest reported cohort of HD phenocopy patients. Two hundred eighty‐five patients with syndromes consistent with HD, who were HD expansion‐negative, were screened for mutations in PRNP, JPH3, TBP, DRPLA, SCA1, SCA2, SCA3, FTL and FRDA. Genetic diagnoses were made in 8 subjects: we identified 5 cases of HDL4, 1 of HDL1 and 1 of HDL2. One patient had Friedreich's ataxia. There were no cases of DRPLA, SCA1, SCA2, SCA3, or neuroferritinopathy. HD phenocopies are clinically and genetically diverse and a definitive genetic diagnosis is currently possible in only a minority of cases. When undertaken, it should be clinically directed and patients and clinicians should be prepared for the low probability of reaching a genetic diagnosis in this group of patients. © 2008 Movement Disorder Society
Perceived imbalance and risk of Parkinson's disease
Authors: Gao Xiang , Chen Honglei , Schwarzschild Michael A. , Logroscino Giancarlo , Ascherio Alberto
Published: January 2008

We prospectively examined associations between perceived imbalance and Parkinson's disease (PD) risk in the Health Professional Follow‐up Study (HPFS), and Nurses' Health Study (NHS). We included 39,087 men and 82,299 women free of PD at baseline (1990) in the current analyses. We documented 449 incident PD cases during 12 years follow‐up. Subjects who reported difficulty with balance before 1990 (baseline) were 1.8 more times likely to develop PD, relative to those who reported no balance difficulty (pooled multivariate RR = 1.8; 95% CI: 1.3, 2.5; P < 0.0001). When we further examined associations between perceived imbalance at baseline and PD onset during different time periods, we found a significant elevation of PD risk only during the first 4 years of follow‐up. This result suggests that the imbalance may in some cases be an early sign of PD, and may represent the onset of motor symptoms although they have not been clinically recognized. © 2008 Movement Disorder Society
Domain decomposition preconditioners for elliptic equations with jump coefficients
Authors: Zhu Yunrong
Published: January 2008

This paper provides a proof of the robustness of the overlapping domain decomposition preconditioners for the linear finite element approximation of second‐order elliptic boundary value problems with strongly discontinuous coefficients. By analyzing the eigenvalue distribution of the domain decomposition preconditioned system, we prove that only a small number of eigenvalues may deteriorate with respect to the discontinuous jump or mesh size, and all the other eigenvalues are bounded below and above nearly uniformly with respect to the jump and mesh size. As a result, we prove that the convergence rate of the preconditioned conjugate gradient methods is nearly uniform with respect to the large jump and mesh size. Copyright © 2008 John Wiley & Sons, Ltd.
Plasma oscillations in nanotransistors for room temperature detection and emission of terahertz radiation
Authors: El Fatimy A. , Tauk R. , Boubanga S. , Teppe F. , Dyakonova N. , Knap W. , Lyonnet J. , Meziani Y. M. , Otsuji T. , Poisson M.‐A. , Morvan E. , Bollaert S. , Shchepetov A. , Roelens Y. , Gaquiere Ch. , Theron D. , Cappy A.
Published: January 2008

In this work we present experimental results on room temperature terahertz (THz) detection/emission from nanotransistors as well as double grating gates structures. It shows that the emission spectra from GaN/AlGaN HEMT transistor can be successfully interpreted in the frame of the Dyakonov‐Shur model which predicts that by heating/accelerating the electrons up to velocities comparable with plasma wave velocity can lead to instability and generation of plasma waves in the transistor channel. Studies of the current dependence of THz detection by InGaAs based HEMT is also presented. It is shown that in realistic transistor structures the room temperature resonant THz detection can be observed only upon applying a current high enough to produce fast/hot electrons. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The correlation effect of carrierinduced magnetic solitons in diluted magnetic semiconductors
Authors: Kanazawa I.
Published: January 2008

We have discussed the localization mechanism in the transport property in the random potentials due to the alloy potential fluctuations in diluted magnetic semiconductors, taking into account the long‐range interactions among magnetic solitons, by using the effective Lagrangian of diffusion modes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of easy magnetization axis orientation on magnetization reversal in permalloy strips
Authors: Kim Dong Ho , Hwang Tae‐Jong , Ryu Kwang‐Su , Shin Sung‐Chul
Published: January 2008

We studied the effect of easy magnetization axis orientation with respect to the strip direction on magnetization reversal process in permalloy strips by measuring the magnetoresistance (MR), the magneto‐optic Kerr effect (MOKE), and the real‐time domain evolution. The three strips were patterned on a single chip with the easy‐axis orientation of each strip relative to the longitudinal direction by around 0, 30, and 60°, respectively. The overall shape of field‐dependent MR was mostly governed by the anisotropic magnetoresistance. The longitudinal MR ratio was significantly increased with increasing angle between the easy axis and the bar direction. Several MR steps were observed during the magnetization reversal in 0 and 30° bars, and the simultaneous measurement of the MOKE and the domain images identified that the MR steps were associated with evolution of the magnetic domains. In addition a resistance contribution from the domain walls was also observed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ring signatures for benzenoids with up to seven rings, Part 1: Catacondensed systems
Authors: Randić Milan , Balaban Alexandru T.
Published: January 2008

We revisited the π‐electron ring partitions in catacondensed benzenoids and re‐examined structural regularities reported for the ring partitions in these compounds, seeking the origin of the observed regularities. We examined the distribution of the π‐electron ring partitions by counting the contributions arising from benzene rings having different assigned numbers of π‐electrons. This has led to a better insight into the underlying structure of the π‐electron ring partitions and also to a novel and unique π‐electron “signature” of individual rings in benzenoid hydrocarbons. The physical interpretation of the local π‐electron ring partition represents the local π‐electron density of benzenoid molecules, and is not an alternative index of local aromaticity as one may erroneously assume. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Plasma chemical reactions of thin nickel films
Authors: Quaas M. , Wulff H. , Ivanova O. , Helm C. A.
Published: January 2008

Nickel clusters of about 20 nm in diameter were treated in a microwave plasma (SLAN, 2.45 GHz) using different gas compositions. The Ni films were exposed to argon/oxygen and argon/hydrogen plasma to study oxidation and reductions reactions, especially the oxidation kinetics. The films were investigated by grazing incidence X‐ray diffractometry (GIXD) to control the phase formation. Thickness and density were determined by X‐ray reflectometry (XR); sample topology was studied by atomic force microscopy (AFM). A combination of these techniques allowed a detailed analysis of the plasma chemical processes.

Oxygen plasma treatment results in the formation of NiO on the Ni particles. The effect of hydrogen plasma depends on the used negative substrate voltage. Metallic Ni is formed without an external voltage. The oxidation kinetics can be described using the ‘shrinking core’ model. The oxide formation rate depends on the sample history, i.e. on the number of oxidation/reduction cycles carried out. While the first oxidation process is clearly found to be diffusion controlled, the kinetics of the subsequent cycles is obviously more reaction controlled. Copyright © 2008 John Wiley & Sons, Ltd.
Tribological testing and optimisation of electroless Ni‐P coatings based on Taguchi method and grey relational analysis
Authors: Sahoo Prasanta , Pal Sujan Kumar
Published: January 2008

This paper presents an experimental study of tribological characteristics of electroless Ni‐P (EN) coatings and optimisation of coating process parameters based on Taguchi method coupled with grey relational analysis. A grey relational grade obtained from the grey relational analysis is used as performance index to study the deposition of EN coating with multiple tribological performance characteristics. Experiments are carried out by utilising the combination of process parameters based on L27 Taguchi orthogonal design with four process parameters, namely, bath temperature, concentration of nickel source solution, concentration of reducing agent and annealing temperature. It has been observed that concentrations of nickel source solution and bath temperature are the most significant parameters for controlling the friction and wear behaviour of EN coating. The surface morphology, composition and wear mechanism of coatings are also studied with the help of scanning electron microscopy, energy dispersed X‐ray analysis and X‐ray diffraction analysis. Copyright © 2008 John Wiley & Sons, Ltd.
iPTT: peer‐to‐peer push‐to‐talk for VoIP
Authors: Lin Jiun‐Ren , Pang Ai‐Chun , Wang Yung‐Chi
Published: January 2008

This paper proposes iPTT, a peer‐to‐peer (P2P) Push‐to‐Talk (PTT) service for Voice over IP (VoIP). In iPTT, a distributed and mobile‐operator independent network architecture is presented to accelerate the deployment of the PTT service. Based on the serverless architecture, we develop two mechanisms, that is, flooding‐based floor control mechanism (FFC) and tree‐based floor control mechanism (TFC), for real‐time talk‐burst determination. The determination algorithms and the corresponding message flows for these two mechanisms are designed to show the feasibility of FFC and TFC. The performance of FFC and TFC is investigated through our analytical and simulation models in terms of the determination latency and the number of floor‐control message exchanges. Copyright © 2008 John Wiley & Sons, Ltd.
HAWT near‐wake aerodynamics, Part I: axial flow conditions
Authors: Haans Wouter , Sant Tonio , van Kuik Gijs , van Bussel Gerard
Published: January 2008

An improved physical understanding of the rotor aerodynamics of a horizontal axis wind turbine (HAWT) is required to reduce the uncertainties associated with today's design codes. Wind tunnel experiments contribute to increased knowledge and enable validation and construction of models. The present study focuses on the near‐wake of a model HAWT in both axial and yawed flow conditions. At three downstream planes parallel to the rotor plane, single‐sensor hot‐film traverses are made. The phase‐locked unsteady three‐dimensional flow velocity vector is determined by a novel data reduction method. A series of two papers discusses the near‐wake aerodynamics of a model HAWT. The main goals are to obtain a detailed understanding of the near‐wake development and to arrive at a base for model construction and validation. The first paper presents the experimental setup, data reduction and the results for the baseline case (axial flow conditions). In the second paper, the results for the yawed flow cases are presented and the effect of yaw misalignment on the near‐wake development is discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Graph transformations for object-oriented refinement
Authors: Zhao Liang , Liu Xiaojian , Liu Zhiming , Qiu Zongyan
Published: January 2008

An object-oriented program consists of a section of
class declarations
and a
main method
. The class declaration section represents the structure of an object-oriented program, that is the data, the classes and relations among them. The execution of the main method realizes the application by invoking methods of objects of the classes defined in the class declarations. Class declarations define the general properties of objects and how they collaborate with each other in realizing the application task programmed as the main method. Note that for one class declaration section, different main methods can be programmed for different applications, and this is an important feature of reuse in object-oriented programming. On the other hand, different class declaration sections may support the same applications, but these different class declaration sections can make significant difference with regards to understanding, reuse and maintainability of the applications. With a UML-like modeling language, the class declaration section of a program is represented as a
class diagram
, and the instances of the class diagram are represented by
object diagrams
, that form the
state space
of the program. In this paper, we define a class diagram and its object diagrams as
directed labeled graphs
, and investigate what changes in the class structure maintain the capability of providing
functionalities
(or
services
). We formalize such a structure change by the notion of
structure refinement
. A structure refinement is a transformation from one graph to another that preserves the
capability
of providing services, that is, the resulting class graph should be able to provide at least as many, and as good, services (in terms of functional refinement) as the original graph. We then develop a
calculus of object-oriented refinement
, as an extension to the classical
theory of data refinement
, in which the refinement rules are classified into four categories according to their natures and uses in object-oriented software design. The soundness of the calculus is proved and the completeness of the refinement rules of each category is established with regard to normal forms defined for object-oriented programs. These completeness results show the power of the simple refinement rules. The normal forms and the completeness results together capture the essence of polymorphism, dynamic method binding and object sharing by references in object-oriented computation.
Pulmonary artery hypertension in a child with MELAS due to a point mutation of the mitochondrial tRNA(Leu) gene (m.3243A>G)
Authors: Sproule D. M. , Dyme J. , Coku J. , de Vinck D. , Rosenzweig E. , Chung W. K. , De Vivo D. C.
Published: January 2008

Although linked with cardiac dysfunction, the association of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke‐like episodes) and pulmonary artery hypertension (PAH) has not been previously described. PAH and right ventricular heart failure were identified by echocardiography in a 3‐year‐old boy with a history of hypotonia, microcephaly and developmental delay. He initially presented with a 10‐day history of dyspnoea, dependent oedema and reduced oral intake. Lactic acidosis was noted on serial arterial blood sampling and cerebrospinal fluid. Muscle biopsy demonstrated cytochrome‐c oxidase‐positive ‘ragged‐red’ fibres consistent with MELAS; subsequent analyses revealed the m.3243A>G point mutation most commonly associated with MELAS. The mutation was heteroplasmic, representing 92% of the total mtDNA from a lung sample. Nitric oxide and epoprostenol were administered without significant clinical or echocardiographic improvement of his PAH. A ‘mitochondrial cocktail’ including biotin, riboflavin, carnitine and coenzyme Q10 also was provided. Five months after presentation, he developed seizures; MRI imaging of his brain demonstrated multiple focal lesions. His clinical status worsened with increasing cardiopulmonary failure. He died two months later. Although therapy for both MELAS and PAH remains limited, recent investigations suggest a beneficial role for l‐arginine in both conditions, implying a possible common pathophysiology. Mitochondrial diseases such as MELAS should be considered in cases of idiopathic PAH, particularly when associated with multisystem involvement including short stature, hearing loss, renal dysfunction, retinopathy, diabetes mellitus, migraines, seizures, ophthalmoplegia, fatigability and weakness.
Amnionless (AMN) mutations in Imerslund–Gräsbeck syndrome may be associated with disturbed vitamin B12 transport into the CNS
Authors: Luder A. S. , Tanner S. M. , de la Chapelle A. , Walter J. H.
Published: January 2008

Familial selective vitamin B12 (cobalamin, Cbl) malabsorption (Imerslund–Gräsbeck syndrome, IGS, OMIM 261100) is a group of autosomal recessive disorders characterized by selective malabsorption of Cbl from the terminal ileum in the presence of normal histology. Mutations in the amnionless (AMN) and cubilin (CUBN) genes are known to be causes of IGS. Their gene products combine to form a receptor complex (cubam), which is instrumental in the binding and transport of Cbl in the gut. As opposed to Cbl transport in the terminal ileum, normal transport of Cbl into the CNS is poorly understood and little is known regarding its molecular basis. Studies in adults with neuropsychiatric disease have suggested the presence of an active transport mechanism into the central nervous system constituting a blood–brain barrier (BBB) for Cbl. A child with IGS, compound heterozygous for a missense and a nonsense mutation in the amnionless (AMN) protein gene, was noted to have a high daily cobalamin (Cbl) requirement for neuropsychiatric, but not for systemic metabolic and haematological, remission. Measurements of CSF Cbl revealed evidence that the transport of Cbl into the central nervous system was impaired, and a standard Schilling test was consistent with a dose response of cobalamin transport across the terminal ileum. Amnionless protein is known to be expressed in the fetal and postnatal central nervous system, and is known to be involved in Cbl transport in other tissues such as kidney as well as the gut. It is possible that an active Cbl transport mechanism at the BBB exists, and that the amnionless (AMN) protein may be part of this mechanism, as it is in cobalamin transport in the terminal ileum.
“Are You at Risk for Hereditary Breast Cancer?”: Development of a Personal Risk Assessment Tool for Hereditary Breast and Ovarian Cancer
Authors: Cohn Wendy F. , Jones Susan M. , Miesfeldt Susan
Published: January 2008

Identification of risk for the hereditary breast and ovarian cancer syndrome (HBOC) is important, as research has demonstrated the benefits of risk‐reducing interventions for women with or at risk for this disorder. Knowledge among women regarding risk factors for hereditary breast cancer and the existence of cancer genetics services appears limited. The goal of this project was to develop a tool to broaden women's awareness regarding their potential risk for HBOC. A formal instructional design process was used to develop a brochure to facilitate recognition of HBOC risk among women attending a no‐cost breast and cervical cancer screening clinic. Brochure development was guided by gathering feedback from potential users early and often. The resulting brochure included four parts: (1) a brief description of the impact of hereditary breast cancer risk on one's health; (2) a personal and family history collection table; (3) a series of questions enabling the user to self‐assess HBOC risk; (4) a list of resources for women at risk for HBOC. User feedback indicated that the brochure was easy to use. The project demonstrated that women can self‐evaluate their risk for HBOC. Future work will evaluate this tool among a broader population of women.
Up‐regulation of PPARγ in myocardial infarction
Authors: Fliegner Daniela , Westermann Dirk , Riad Alexander , Schubert Carola , Becher Eva , Fielitz Jens , Tschöpe Carsten , Regitz‐Zagrosek Vera
Published: January 2008

Background:

Peroxisome proliferator activated receptors (PPARs) are key regulators for cardiac energy metabolism after myocardial injury. We hypothesized, that PPARs are regulated in myocardial infarction (MI) and their activity is modulated by angiotensin receptor blockers (ARBs).

Methods:

Following induction of MI, male rats were treated with placebo or the ARB irbesartan for three weeks. PPARα, β/δ and γ protein expression and gene expression of PPAR target genes and glucose transporters were measured. PPARγ‐protein expression was analyzed by immunofluorescence.

Results:

MI decreased LVP and dp/dtmax and increased LVEDP, this effect was counteracted by irbesartan. PPARα and PPARβ/δ protein expression was not altered in MI and was not affected by irbesartan. PPARγ protein content was increased in the infarcted area and localized to cardiac myocytes and fibroblasts. In parallel, expression of CTGF was increased 10‐fold in the infarcted zone. PPAR target genes (CD36, MCAD, ACO and GLUT4) were significantly decreased in infarcted tissue, and this was unaffected by irbesartan. However, CD36 and ACO in the non‐infarcted areas were up‐regulated by irbesartan.

Conclusion:

Endogenous up‐regulation of PPARγ in MI is insufficient to counteract the decrease in metabolic genes, but parallels an increase in the profibrotic mediator CTGF. Irbesartan increases fatty acid oxidating enzymes after MI independent of PPARγ regulation.
Role of β adrenergic receptor polymorphisms in heart failure: Systematic review and meta‐analysis
Authors: Muthumala Amal , Drenos Fotios , Elliott Perry M. , Humphries Steve E.
Published: January 2008

Heart Failure (HF) is a common disorder associated with substantial morbidity and mortality. β adrenergic receptors (βAR) are the primary pathway through which cardiac function is influenced. Chronic β1AR activation is implicated in the pathogenesis of HF and βAR blockade improves survival in left ventricular systolic dysfunction. Common functional polymorphisms in β adrenergic receptor genes (ADRB) have been associated with HF phenotypes, and with pharmacogenetic interaction with β adrenergic receptor blockers (β blockers). However, these associations have not been consistently replicated. The evidence forADRBvariant involvement in pathogenesis, progression and response to β blockers in HF is reviewed. In addition, a meta‐analysis of three studies analysing the effect ofADRB1Arg389Gly polymorphism on left ventricular remodelling with the use of β blockers, demonstrating a 5% improvement in left ventricular ejection fraction in Arg389 homozygotes, is presented. There is now accumulating molecular evidence for a different functional response to β blockers associated with this polymorphism. In the future, confirmed genotypic associations may enable patients to be identified who are either at greater risk of developing HF, whose HF may rapidly progress, or who are unlikely to benefit from β blockers, and such patients may benefit from targeted aggressive therapy.
What do different databases tell about the use of opioids in seven European countries in 2002?
Authors: Hamunen Katri , Laitinen‐Parkkonen Pirjo , Paakkari Pirkko , Breivik Harald , Gordh Torsten , Jensen Niels Henrik , Kalso Eija
Published: January 2008

Objective: The objective of this paper was to analyse opioid consumption in a number European countries using different sources of data.

Methods: Data were extracted from the United Nations’ International Narcotics Control Board Report (INCB) 2003 and from the registers of the national health authorities in seven countries where data were available for 2002. The amount of opioid used was calculated as daily defined doses per 1000 inhabitants per day (DDD/1000/day). Danish Register of Medicinal Products Statistics was further explored for characteristics of opioid consumption (age, gender, type of opioids consumed) by patients in primary care. Total opioid consumption and consumption of 11 selected opioids (7 strong and 4 weak) were analysed. The amount of opioids consumed by outpatients was also examined.

Results: There were considerable differences in the number of opioids reported and significant discrepancies in the amounts of opioids consumed between the national data and the INCB report. The source of data for the national registers on drug consumption varied (pharmacies or wholesale). The INCB data provide information on opioid import and estimated need rather than on medical consumption.

Conclusions: Caution is required when interpreting the data on opioid consumption between countries because of differences in the collection and reporting of data. Better recording of opioid consumption is needed for meaningful analysis of opioid consumption and its possible effect on pain management in different countries. Data on opioids consumed for cancer‐related pain in comparison with chronic non‐malignant pain are needed. A uniform method of collection of data on analgesic consumption should be established for all European countries.
Non‐linear morphine‐induced depression of spinal excitation following long‐term potentiation of C fibre‐evoked spinal field potentials
Authors: Buesa Itsaso , Urrutia Andrés , Bilbao Juan , Aguilera Luciano , Zimmermann Manfred , Azkue Jon Jatsu
Published: January 2008

Reduced efficacy of opioid analgesics in some abnormal pain states is a common clinical observation. We tested whether the depressing effect of spinally administered morphine (MOR) on C fibre‐evoked spinal field potentials is diminished during long‐term potentiation (LTP) induced in the spinal dorsal horn by high‐frequency stimulation (HFS). MOR distinctly reduced evoked field potentials 2h after LTP induction, yet MOR doses suppressing spinal responses in control rats (500μM) failed to achieve so in HFS‐receiving rats. However, HFS and MOR administration at the 0.01–0.1mM range were found to interact positively as independent variables, suggesting that LTP induction may trigger an endogenous factor enhancing the effectiveness of spinally applied MOR.

The present findings suggest that LTP‐like, long‐lasting enhancement of synaptic strength in the spinal dorsal horn can contribute to increasing MOR doses required for antinociception in some forms of abnormal pain.
Early maturation of GABAergic synapses in mouse retinal ganglion cells
Authors: Unsoeld Thomas , Stradomska Alicja M. , Wang Rui , Rathjen Fritz G. , Jüttner Rene
Published: January 2008

This study was aimed to characterize the earliest phases of synapse development in mouse retinal ganglion cells (RGCs) by recording spontaneous postsynaptic currents (PSCs). First PSCs were detected at embryonic day 17 and completely suppressed by bicuculline, demonstrating their GABAergic nature. Starting from postnatal day 3 a small fraction of RGCs had rapidly decaying, most likely glutamatergic currents.

The present results suggest that functional GABAergic synapses with RGCs appear before birth and that GABAergic synaptic transmission precedes that of glutamate in the retina. In this early period GABA acts in a depolarizing manner and takes over an excitatory function.
Development of 5‐HT1B, SERT and thalamo‐cortical afferents in early nutrionally restricted rats: An emerging explanation for delayed barrel formation
Authors: Medina‐Aguirre Ivett , Gutiérrez‐Ospina Gabriel , Hernández‐Rodríguez Jorge , Boyzo Alfonso , Manjarrez‐Gutiérrez Gabriel
Published: January 2008

Barrel formation is delayed in nutritionally restricted rats. The underlying cause of such delay is yet unclear. Because barrels appear upon the arrival of somatosensory thalamo‐cortical afferents and the reorientation of the dendritic arborizations of cortical spiny stellate neurons, it is likely that at least one of these processes is altered by nutritional restriction. Also, the serotoninergic afferent system has been implicated in regulating barrel segregation and growth during early postnatal life. We then evaluated the pattern of immunostaining of the serotonin transporter (SERT) and of the serotonin receptor 1B (5‐HT1B), as well as the growth and arrival time of somatosensory thalamo‐cortical afferents, to infer the contribution of these elements in the delayed formation of barrels observed in nutritionally restricted rats. It was found that the rates of development and the segregation of thalamo‐cortical fibers were normal in nutritionally restricted rats. SERT, but not 5‐HT1B immunoreactivity, was decreased in the primary somatosensory cortex during barrel specification. The availability of both proteins in nutritionally restricted rats was lower than that observed in their well fed counterparts at later developmental times. It is concluded that the delayed formation of barrels observed in nutritionally restricted rats is due to a retarded reorientation of dendritic arbors of cortical neurons. This might happen as a secondary effect of decreasing the availability of SERT and/or increasing the availability of 5‐HT1B receptor early in postnatal life.
Abelson tyrosine kinase and Calmodulin interact synergistically to transduce midline guidance cues in the Drosophila embryonic CNS
Authors: Hsouna Anita , VanBerkum Mark F.A.
Published: January 2008

Calmodulin and Abelson tyrosine kinase are key signaling molecules transducing guidance cues at the Drosophila embryonic midline. A reduction in the signaling strength of either pathway alone induces ectopic midline crossing errors in a few segments. When Calmodulin and Abelson signaling levels are simultaneously reduced, the frequency of ectopic crossovers is synergistically enhanced as all segments exhibit crossing errors. But as the level of signaling is further reduced, commissures begin to fuse and large gaps form in the longitudinal connectives. Quantitative analysis suggests that the level of Abelson activity is particularly important. Like Calmodulin, Abelson interacts with son‐of‐sevenless to increase ectopic crossovers suggesting all three contribute to midline repulsive signaling. Axons cross the midline in almost every segment if Frazzled is co‐overexpressed with the Calmodulin inhibitor, but the crossovers induced by the Calmodulin inhibitor itself do not require endogenous Frazzled. Thus, Calmodulin and Abelson tyrosine kinase are key signaling molecules working synergistically to transduce both midline attractive and repulsive cues. While they may function downstream of specific receptors, the emergence of commissural and longitudinal connective defects point to a novel convergence of Calmodulin and Abelson signaling during the regulation of actin and myosin dynamics underlying a guidance decision.
Distinct climate change synchronous with Heinrich event one, recorded by stable oxygen and carbon isotopic compositions in stalagmites from China
Authors: Zhou Houyun , Zhao Jianxin , Feng Yuexing , Gagan Michael K. , Zhou Guoqing , Yan Jun
Published: January 2008

Uranium-series dating of oxygen and carbon isotope records for stalagmite SJ3 collected in Songjia Cave, central China, shows significant variation in past climate and environment during the period 20–10 ka. Stalagmite SJ3 is located more than 1000 km inland of the coastal Hulu Cave in East China and more than 700 km north of the Dongge Cave in Southwest China and despite minor differences, displays a clear first-order similarity with the Hulu and Dongge records. The coldest climatic phase since the Last Glacial Maximum, which is associated with the Heinrich Event 1 in the North Atlantic region, was clearly recorded in SJ3 between 17.6 and 14.5 ka, in good agreement in timing, duration and extent with the records from Hulu and Dongge caves and the Greenland ice core. The results indicate that there have been synchronous and significant climatic changes across monsoonal China and strong teleconnections between the North Atlantic and East Asia regions during the period 20–10 ka. This is much different from the Holocene Optimum which shows a time shift of more than several thousands years from southeast coastal to inland China. It is likely that temperature change at northern high latitudes during glacial periods exerts stronger influence on the Asian summer monsoon relative to insolation and appears to be capable of perturbing large-scale atmospheric/oceanic circulation patterns in the Northern Hemisphere and thus monsoonal rainfall and paleovegetation in East Asia. Climatic signals in the North Atlantic region propagate rapidly to East Asia during glacial periods by influencing the winter land–sea temperature contrast in the East Asian monsoon region.
High resolution magnetostratigraphy and deposition cycles in the Nihewan Basin (North China) and their significance for stone artifact dating
Authors: Huamei Li , Xiaoqiang Yang , Heller Friedrich , Haitao Li
Published: January 2008

Three lacustrine sections in the Nihewan Basin, Xiaodukou, Donggutuo and Xiaochangliang (40.1–40.4°N; 114.6–114.7°E), were closely sampled for magnetostratigraphic and deposition cycle analysis. Rock magnetic investigations show that the characteristic remanent magnetization of the sediments is mainly carried by magnetite and hematite. The Xiaodukou sequence is one of the most complete sections in the basin and has recorded substantial parts of the Brunhes and Matuyama chrons back to the termination of the Olduvai subchron. Several subchrons within the Matuyama period have been documented such as the Jaramillo, the Cobb Mt. and others. The Matuyama/Brunhes boundary, the Jaramillo, as well as the Cobb Mountain events were observed also at Donggutuo. On the basis of grain size and susceptibility data and of field investigations, the sections are divided into two longer lasting lacustrine episodes with a fluvio-lacustrine deposit in between. They are structured by 15 high-frequency deposition sub-cycles. In each cycle, the grain size fines upwards, while magnetic susceptibility decreases. This behavior is due to cyclic water level change of the ancient lake Nihewan. At Xiaodukou, the variations of the 0.2 to 7.5 μm grain size fraction can be correlated with the marine oxygen isotope stages OIS 64–OIS 11. The grey-green clayey to silty Paleolithic stone artifact layers at Xiaochangliang and Donggutuo are located at depths of 55.4 m and 43–38.7 m, respectively. They were buried when the lake-level was rising. The artifact layers have been deposited around the Cobb Mountain event during the sedimentary sub-cycle 6 of the older lacustrine phase corresponding to OIS 35, 36. Thus in contrast to the results of other studies, the estimated age of the Xiaochangliang stone artifact layer does not exceed 1.26 Ma, while the Donggutuo stone artifact layers date back to 1.21–1.15 Ma. This age determination brings the Nihewan hominids in close relation to the findings of Homo Erectus at Lantian on the Chinese Loess Plateau.
When the South Emulates the North: Energy Policies and Nationalism in the Twentieth Century
Authors: MADUREIRA NUNO LUÍS
Published: January 2008

Differences in natural endowments, in geographical conditions and in per capita income set up an historical bifurcation between northern states, with abundant renewable hydrological resources, and less well-endowed southern states. While the first embraced a model of electricity adding, with the embodiment of this form of energy in capital goods and intermediate goods, the second followed a path of electricity substitution, with mixed strategies of replacing inputs in established sectors of industry, public utilities, transport and private consumption. This article examines the different plans for and achievements of economic nationalism in the twentieth century and its consequences, discussing the possibility of reproducing in Portugal the pattern of the stimulus to industrial manufacturing of cheap electricity.
Glücksfall Bundesrepublik: New Germany and the 1960s
Authors: LAMMERS KARL CHRISTIAN
Published: January 2008

The downfall and disappearance of the German Democratic Republic, the GDR, and the unification in 1990 of the two German states into the Federal Republic of Germany, the FRG, marked the end of an era. Forty years of divided and non-simultaneous German history had been brought to an end, and the national or German question had at last been solved. Since 1990 German history has continued as the history of the Federal Republic. From this perspective 1990 marked not an absolute end, but the continuity of the Federal Republic and to some degree even the triumph of the political, economic and social system of the FRG, as the inhabitants of the socialist GDR, when they had the opportunity, voted for joining the successful and wealthy West German state. The end of divided history, however, has had another consequence. Even if the era of the GDR, because of the very favourable archive situation, attracted great attention among historians, the focus of historical research has turned more and more to the history of the Federal Republic in order to analyse and explain why the FRG ended as a success, while the socialist GDR failed in its ambitions and aspirations as an alternative Germany. History demonstrated that the GDR was no German option, although for some time it was a German reality.
Quasirandom Groups
Authors: GOWERS W. T.
Published: January 2008

Babai and Sós have asked whether there exists a constant c > 0 such that every finite group G has a product-free subset of size at least c|G|: that is, a subset X that does not contain three elements x, y and z with xy = z. In this paper we show that the answer is no. Moreover, we give a simple sufficient condition for a group not to have any large product-free subset.
An Elementary Construction of Constant-Degree Expanders
Authors: ALON NOGA , SCHWARTZ ODED , SHAPIRA ASAF
Published: January 2008

We describe a short and easy-to-analyse construction of constant-degree expanders. The construction relies on the replacement product, applied by Reingold, Vadhan and Wigderson (2002) to give an iterative construction of bounded-degree expanders. Here we give a simpler construction, which applies the replacement product (only twice!) to turn the Cayley expanders of Alon and Roichman (1994), whose degree is polylog n, into constant-degree expanders. This enables us to prove the required expansion using a simple new combinatorial analysis of the replacement product (instead of the spectral analysis used by Reingold, Vadhan and Wigderson).
«Teamwork, that’s what we need!»
Authors: Horn Benedikt
Published: January 2008

Die Bruchlandung einer amerikanischen «Dakota» im November 1946 löste eine bis dahin nie da gewesene Rettungsaktion aus, die von allen Beteiligten das Letzte verlangte. Zahlreiche Probleme und Forderungen sind bis heute unverändert geblieben.