bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and electrical properties of CNT/PP conductive composites with low percolation threshold by solid state alloying
Authors: Gao D.L. , Zhan M.S.
Published: August 2009

The carbon nanotube/polypropylene conductive composites with a percolation threshold as low as 0.25 wt% were fabricated by solid state alloying. This solid state alloying method uses the super‐high speed mechanical shearing (at 10,000 rpm) to process the entangled catalytically grown carbon nanotubes (CNTs) and the polymer matrix in solid state. The electrical properties of the nanocomposites and the structure and distribution of CNTs were investigated. The results indicated that via the shear‐intensive process, CNTs were truncated and dispersed effectively, and their length could be controlled properly to fully exert the advantage of high aspect ratios (length‐to‐diameter ratios). At the same time, a linear structure conductive network which may considerably lower the percolation threshold was also formed by this method. Moreover, the CNTs could be further dispersed under the action of thermo energy provided by increasing the processing temperature. The super‐high speed solid state alloying method is a favorable approach for the production of low percolation threshold conductive composites of CNTs filled high viscosity resins. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Aspirin increases mortality in diabetic patients without cardiovascular disease: a Swedish record linkage study
Authors: Welin Lennart , Wilhelmsen Lars , Björnberg Arne , Odén Anders
Published: August 2009

Purpose

Aspirin is effective in secondary prevention of cardiovascular disease. The results are less convincing when aspirin is used for primary prevention even in high‐risk patients (i.e., patients with diabetes). We therefore analyzed the effect of aspirin on mortality and serious bleeding in diabetic patients with and without cardiovascular disease.

Methods

We performed a record linkage study of the patient registry of the Västra Götaland region in south‐western Sweden, the Swedish mortality register and the Swedish register of dispensed drugs. All diabetic patients (n = 58 465) from 1 July 2005 to 30 June 2006 were followed up with respect to bleeding until 31 October 2006, and mortality until 31 December 2006.

Results

When 19 confounding factors (diseases and interventions) were assessed, aspirin significantly increased mortality in diabetic patients without cardiovascular disease from 17% (95% confidence interval; 95%CI, 1–36) at age 50 years to 29% (16–43) at age 85 years. In contrast aspirin tended to decrease mortality among elderly diabetic patients with cardiovascular disease. Theoretical calculations indicated that aspirin caused 107 excess deaths among diabetic patients without cardiovascular disease and prevented 164 deaths among diabetic patients with cardiovascular disease. Aspirin also increased the risk of serious bleeding by 46% (95%CI, 22–75) in diabetic patients without cardiovascular disease but decreased the risk among those with cardiovascular disease.

Conclusion

Aspirin use in diabetes patients without cardiovascular disease remains controversial and current guidelines should be revised until results from ongoing large randomized controlled trials become available. Copyright © 2009 John Wiley & Sons, Ltd.
A systematic narrative review of the studies on structured child‐centred interventions for families with a parent with cancer
Authors: Niemelä Mika , Hakko Helinä , Räsänen Sami
Published: August 2009

Objective: To perform a systematic narrative review of the current state of published articles on the structured interventions targeted at children with a parent suffering from cancer.

Methods: The study was based on a narrative synthesis approach. Eleven structured child‐centred intervention studies were systematically searched through PubMed, PsycINFO and MEDLINE. The interventions were grouped into two main categories: ‘structured family interventions’ and ‘structured peer group interventions’. Special attention was focused on the preventive purpose of the interventions.

Results: The participants (children, parents and health professionals) reported several positive impacts of interventions on children's and parents' psychosocial well‐being, although no improvement or changes were also observed. The effect of interventions on the children was evaluated by structured methods only in five studies.

Conclusions: This review showed the lack of valid psychosocial preventive intervention methods focusing on children with parental cancer and highlighted the need of intervention research with controlled study designs and long follow‐up periods. However, an intervention method should be easy to train and applicable to the clinical practice of healthcare professionals. By refining the practice‐based experiences with scientific research evidence it is possible to move to the next level in providing psychosocial support and prevention for children living in families with parental cancer. Copyright © 2009 John Wiley & Sons, Ltd.
Role of Chlamydophila pneumoniae in children hospitalized for community‐acquired pneumonia in Vienna, Austria
Authors: Kurz Herbert , Göpfrich Hubert , Wabnegger Leila , Apfalter Petra
Published: August 2009

Background

No recent Austrian data are available on the epidemiology and morbidity of Chlamydophila pneumoniae (C. pneumoniae) as causative agent in youths and children hospitalized with community‐acquired pneumonia (CAP). These data would serve as a rationale for empiric antimicrobial therapy.

Methods

During winter months 2006/7 112 immunocompetent youths and children between 2 months and 18 years hospitalized consecutively with CAP were prospectively enrolled. Microbiological detection of conventional bacteria, Mycoplasma pneumoniae as well as respiratory viruses was performed, and clinical signs as well as indices of inflammation were documented. Diagnosis of C. pneumoniae was performed by means of species‐specific real‐time PCR as well as cell culture from respiratory secretions.

Results

PCR for C. pneumoniae was performed in 60 patients. In 4 cases (6.7%) C. pneumoniae was found as causative agent. In 1 case C. pneumoniae could be confirmed by cell‐culture. All children with C. pneumonia were ≥5 years of age. All but 1 child received clarithromycin together with cefuroxime. The number of days with fever >38,5°C was between 1 and 7, the number of days in hospital was between 4 and 7, all children recovered completely.

Conclusion

C. pneumoniae was found in 6.7% of children and youths hospitalized with CAP in a community hospital during the winter months 2006/07. Children and youths with lower respiratory infections should further be tested for C. pneumoniae to elucidate the actual epidemiological situation and to guide empiric antimicrobiotic therapy. Pediatr Pulmonol. 2009; 44:873–876. © 2009 Wiley‐Liss, Inc.
Analysis of the plasticity of location of the Arg244 positive charge within the active site of the TEM‐1 β‐lactamase
Authors: Marciano David C. , Brown Nicholas G. , Palzkill Timothy
Published: August 2009

A large number of β‐lactamases have emerged that are capable of conferring bacterial resistance to β‐lactam antibiotics. Comparison of the structural and functional features of this family has refined understanding of the catalytic properties of these enzymes. An arginine residue present at position 244 in TEM‐1 β‐lactamase interacts with the carboxyl group common to penicillin and cephalosporin antibiotics and thereby stabilizes both the substrate and transition state complexes. A comparison of class A β‐lactamase sequences reveals that arginine at position 244 is not conserved, although a positive charge at this structural location is conserved and is provided by an arginine at positions 220 or 276 for those enzymes lacking arginine at position 244. The plasticity of the location of positive charge in the β‐lactamase active site was experimentally investigated by relocating the arginine at position 244 in TEM‐1 β‐lactamase to positions 220, 272, and 276 by site‐directed mutagenesis. Kinetic analysis of the engineered β‐lactamases revealed that removal of arginine 244 by alanine mutation reduced catalytic efficiency against all substrates tested and restoration of an arginine at positions 272 or 276 partially suppresses the catalytic defect of the Arg244Ala substitution. These results suggest an evolutionary mechanism for the observed divergence of the position of positive charge in the active site of class A β‐lactamases.
The Drosophila G protein‐coupled receptor, Methuselah, exhibits a promiscuous response to peptides
Authors: Ja William W. , Carvalho Gil B. , Madrigal Marisol , Roberts Richard W. , Benzer Seymour
Published: August 2009

Methuselah (Mth) is a G protein‐coupled receptor (GPCR) associated with longevity in Drosophila melanogaster. Previously, Stunted (Sun) was identified as a peptide agonist of Mth. Here, we identify two additional activators of Mth signaling: Drosophila Sex Peptide (SP) and a novel peptide (Serendipitous Peptide Activator of Mth, SPAM). Minimal functional sequences and key residues were identified from Sun and SPAM by studying truncation and alanine‐scanning mutations. These peptide agonists share little sequence homology and illustrate the promiscuity of Mth for activation. mth mutants exhibit no defects in behaviors controlled by SP, casting doubt on the biological significance of Mth activation by any of these agonists, and illustrating the difficulty in applying in vitro studies to their relevance in vivo. Future studies of Mth ligands will help further our understanding of the functional interaction of agonists and GPCRs.
Thermochromic VO2‐based multilayer films with enhanced luminous transmittance and solar modulation
Authors: Mlyuka Nuru R. , Niklasson Gunnar A. , Granqvist Claes G.
Published: August 2009

Vanadium dioxide (VO2) shows an abrupt and reversible change in optical and electrical properties when the temperature is raised beyond a critical point of ∼68 °C. Films made from this material have a potential to be used in energy efficient “smart” windows with temperature‐dependent throughput of solar radiation. Two of the drawbacks of this material have been its low luminous transmittance and limited solar modulation of transmittance during switching. In this work we report calculations and experiments on multilayers of VO2 and TiO2, produced by reactive DC magnetron sputtering, that significantly improve the luminous transmittance and solar modulation of the films during switching. We also explore the angular‐dependent transmittance of five‐layer TiO2/VO2/TiO2/VO2/TiO2 films and demonstrate that the modulation of luminous and solar transmittance can be enhanced at non‐normal angles of incidence.
Thermal conductivity reduction in fullerene‐enriched p‐type bismuth telluride composites
Authors: Gothard N. , Spowart J. E. , Tritt T. M.
Published: August 2009

We present a systematic study of the effects of fullerene nanoinclusions upon a p‐type bismuth–antimony–telluride matrix, where the ultimate goal is maximizing the figure of merit by reducing the thermal conductivity (TC). Nanocomposites consisting of a bismuth–telluride matrix with fullerene inclusions have been prepared both by mechanical mixing and ball milling, with the final consolidation in each case achieved by uniaxial hot pressing. A series of samples was produced with fullerene concentrations ranging from fractional levels to several molar percent, and the effects of the fullerene additions upon the resulting microstructure have been considered. Thermal and electrical transport properties have been measured from 10 to 300 K, and the data are discussed in light of the underlying physical mechanisms.
Anomalous ferromagnetic behaviour of Y2O3 and CuO nanoparticles in YBa2Cu3Oy superconductor
Authors: Yanmaz E. , Basoglu M. , Grovenor C. R. M.
Published: August 2009

Anomalous ferromagnetic behaviour of the Y2O3 and CuO components in YBa2Cu3Oy (Y123) was observed after severe reduction of particle size. The particle size reduction was performed in two ways. First, Y2O3, BaCO3 and CuO were ground for different times to reduce the particle size to the nanoscale. It was found that the superconducting phase could not be obtained without heat treatment, but a weak ferromagnetic behaviour of the mixture was observed at liquid and room temperatures. Second, preheated Y123 powders were subjected to grinding for various times followed by a second sintering process. It was found that the superconducting transition temperature, Tc, was strongly suppressed by increasing grinding time, and ferromagnetic behaviour at both room and liquid nitrogen temperatures was also observed. In order to understand which compound is responsible for this weak ferromagnetism, the Y2O3, BaCO3 and CuO powders were separately ground and M‐H loops taken at 290 K. The results indicated that both Y2O3 and CuO powders showed weak ferromagnetism, but BaCO3 showed anti ferromagnetism. It is thought that energy transfer to the powder particles by grinding results in severe plastic deformation of the particles to produce dislocations, vacancies and atomic disorder. We discuss then the observations in the context of recent studies of the magnetic properties of nanoscale oxide materials.
Saturation of luminescence from Si nanocrystals embedded in SiO2
Authors: Timmerman D. , Izeddin I. , Gregorkiewicz T.
Published: August 2009

We present a photoluminescence excitation study of silicon nanocrystals in a SiO2 matrix. We show that although the excitation cross‐section is wavelength‐dependent and increases for shorter excitation wavelengths, the maximum time‐integrated photoluminescence signal for a given sample saturates at the same level independent of excitation wavelength or amount of generated electron‐hole pairs per nanocrystal after a laser pulse. We demonstrate explicitly that saturation is achieved when every nanocrystal has absorbed at least one photon. In nanocrystals where several electron‐hole pairs have been created during the excitation pulse, fast non‐radiative recombinations reduce their number, leading to the situation that only a single electron‐hole pair per nanocrystal can recombine radiatively, producing a photon and contributing to the photoluminescence. In this way a natural limit is set for photoluminescence intensity from an ensemble of Si nanocrystals excited with a laser pulse with a short duration in comparison with the radiative recombination time.
Ferrimagnetic magnetizations in a thin film described by the transverse Ising model
Authors: Kaneyoshi T.
Published: August 2009

The two surfaces of a thin film with a thickness L described by the transverse Ising model are coupled to the inner next layer with a negative exchange interaction, so that the spin direction at the surfaces is opposite to that of the inner layers. The influences of exchange interactions, transverse fields and thickness on the longitudinal and transverse magnetizations of the thin film are investigated by the use of the standard mean‐field theory. The longitudinal magnetization of a thin film is strongly affected by the ratios of the exchange interactions and the transverse fields between the surfaces and the bulk. In particular, some typical ferrimagnetic behaviours are found for the temperature dependence of longitudinal magnetization in the thin film, depending on these ratios and the transverse field in the bulk. The possibility of two compensation points is also found for the system with L = 10.
On rotating rigid parallelograms and their potential for exhibiting auxetic behaviour
Authors: Attard Daphne , Manicaro Elaine , Grima Joseph N.
Published: August 2009

Auxetic systems have the anomalous property of becoming wider when uniaxially stretched, i.e. exhibit a negative Poisson's ratio. One of the mechanisms which can give rise to this property is based on rotating rigid units, in particular 2D rigid polygons which are connected together at their corners through hinges and rotate relative to each other when uniaxially stretched. This work extends earlier preliminary work on connected rigid parallelograms and presents expressions for the mechanical properties for all the types of planar systems that can be constructed from rigid parallelograms of equal size connected at their vertices through flexible hinges. In particular, we derive and discuss the mechanical properties for the Type Iα, Iβ and IIβ rotating parallelograms which were not previously analysed and compare them with the properties of the Type IIα systems. We show that despite being rather similar to each other, the different types of ‘rotating parallelograms’ have very different mechanical properties and different abilities to exhibit auxetic behaviour.
A geometric confidence ellipse approach to the estimation of the ratio of two variables. Statistics in Medicine 2008; 27:5956–5974.
Authors: Walter S. D. , Gafni A. , Birch S.
Published: August 2009

We are grateful to Dr Etienne Kaelin for pointing out four typographic errors in the equations for this paper. These are as follows:

The term xy in equation (1) should be replaced by:

Equation (3) should be

The first term of the unnumbered equation after equation (3) should be µy rather than µx.

The correct version of equation (4) is

The numerical results of this paper as shown in the various tables are not affected by these errors because correct versions of the equations were used in their calculation.

Dr Kaelin has offered to make available an Excel spreadsheet that will carry out the calculations for the method described in this paper. It is available to interested readers by contacting him at Etienne.Kaelin@pmintl.com.
Performance of analytical methods for overdispersed counts in cluster randomized trials: Sample size, degree of clustering and imbalance
Authors: Durán Pacheco Gonzalo , Hattendorf Jan , Colford John M. , Mäusezahl Daniel , Smith Thomas
Published: August 2009

Many different methods have been proposed for the analysis of cluster randomized trials (CRTs) over the last 30 years. However, the evaluation of methods on overdispersed count data has been based mostly on the comparison of results using empiric data; i.e. when the true model parameters are not known. In this study, we assess via simulation the performance of five methods for the analysis of counts in situations similar to real community‐intervention trials. We used the negative binomial distribution to simulate overdispersed counts of CRTs with two study arms, allowing the period of time under observation to vary among individuals. We assessed different sample sizes, degrees of clustering and degrees of cluster‐size imbalance. The compared methods are: (i) the two‐sample t‐test of cluster‐level rates, (ii) generalized estimating equations (GEE) with empirical covariance estimators, (iii) GEE with model‐based covariance estimators, (iv) generalized linear mixed models (GLMM) and (v) Bayesian hierarchical models (Bayes‐HM). Variation in sample size and clustering led to differences between the methods in terms of coverage, significance, power and random‐effects estimation. GLMM and Bayes‐HM performed better in general with Bayes‐HM producing less dispersed results for random‐effects estimates although upward biased when clustering was low. GEE showed higher power but anticonservative coverage and elevated type I error rates. Imbalance affected the overall performance of the cluster‐level t‐test and the GEE's coverage in small samples. Important effects arising from accounting for overdispersion are illustrated through the analysis of a community‐intervention trial on Solar Water Disinfection in rural Bolivia. Copyright © 2009 John Wiley & Sons, Ltd.
A comparison of model choices for the continual reassessment method in phase I cancer trials
Authors: Paoletti X. , Kramar A.
Published: August 2009

Determination of the maximum tolerated dose (MTD) is the main objective of phase I trials. Trials are typically carried out with restricted sample sizes. Model‐based approaches proposed to identify the MTD (including the Continual Reassessment Method or CRM) suppose a simple model for the dose‐toxicity relation. At this early stage of clinical development, the true family of models is not known and several proposals have been done. Asymptotic convergence of the recommendation to the true MTD can be obtained with a one‐parameter model even in case of model misspecification. Nevertheless, operating characteristics with finite sample sizes can be largely affected by the choice of the model.

In this paper, we evaluate and compare several models in a simulation framework. This framework includes a large class of dose‐toxicity relations against which to test the competing models, an ‘optimal’ method that provides efficient non‐parametric estimates of the probability of dose limiting toxicity to serve as a benchmark and as a graphic representation. In particular we explore the use of a one‐parameter versus a two‐parameter model, we compare the power and the logistic models and finally we investigate the impact of dose recoding on the operating characteristics. Comparisons are carried out with both a likelihood approach and a Bayesian approach for model estimations. We show that average performances of a one‐parameter model are superior and that the power model has good operating characteristics. Some models can speed up dose escalation and lead to more aggressive designs.

We derive some behavior related to the choice of model and insist on the use of simulations under several scenarios before the initiation of each new trial in order to determine the best model to be used. Copyright © 2009 John Wiley & Sons, Ltd.
A methodology for estimating and optimizing effectiveness of Non‐Independent Layered Defense
Authors: Kaminer Boaz I. , Ben‐Asher Joseph Z.
Published: August 2009

For many years, systems, developed to be integrated into a layered defense array, were planned through the “Stand Alone” paradigm, assuming that the layers of defense are independent. Almost all published literature dealing with Layered Defense automatically assumes that the layers of defense are independent of each other. The fact is they are not! Defense layers may influence one another in positive and/or negative ways. We attempt to initiate a new look at developing and deploying systems in an integrated array of defense systems, based on the understanding that influences between systems must be taken into account. A methodology for modeling the dependencies between defense systems engagements, of a single attacker, or of a salvo of attackers, is developed in this paper through an “Influence Decay Function” model. A tractable algorithm is developed to compute the complex effectiveness objective functions. The Non Independent Layered Defense Problem (NILDP) is formulated as a Mixed Integer Non Linear Programming problem. The optimization problem for maximum layered defense effectiveness is solved through powerful heuristic methods. The discussion deals with engineering defense systems to operate within complex environments which include not only threat from an opponent but also friendly systems to which integration is not at all trivial. © 2009 Wiley Periodicals, Inc. Syst Eng
Quantitative elemental analysis of individual particles with the use of micro‐beam X‐ray fluorescence method and Monte Carlo simulation
Authors: Czyzycki Mateusz , Bielewski Marek , Lankosz Marek
Published: August 2009

The aim of the work was to develop a Monte Carlo (MC) method and combine it with micro‐beam X‐ray fluorescence (XRF) technique for determination of chemical composition of individual particles. A collection of glass micro‐spheres, made of NIST (National Institute of Standards and Technoly) K3089 material of known chemical composition, with diameters in the range of 25–45 µm was investigated. The micro‐spheres were measured in a scanning micro‐beam XRF spectrometer utilising X‐ray tube as a source of primary radiation. Results obtained for low Z elements showed high dependence on particle size. It was found that the root mean square of concentration uncertainty, for the all elements present in the particle, increases with growing sample size. More accurate results were obtained for high Z elements such as Fe–Pb, as compared to others. The elemental percentage uncertainty did not exceed 14% for any particular sample and 6% for the whole group of the measured micro‐spheres as an average. Results obtained by the Monte Carlo method were compared with other analytical approaches. Copyright © 2009 John Wiley & Sons, Ltd.
Ein neuartiger Zugang zu reduzierten Polyoxomolybdaten mit komplexen Gegenionen – Synthese und Struktur von [Mn(CH3OH)6][Mo8O16(OCH3)8(C2O4)]
Authors: Sterzik Anke , Görls Helmar , Spielberg Eike T. , Plass Winfried , Imhof Wolfgang
Published: August 2009

The tetranuclear compound [Mo2(O2C‐tBu)3]2(μ‐C2O4) (1) that is prepared from [Mo2(O2C‐tBu)3]4 and oxalic acid, was reacted with MnI2·2THF to form the polyoxomolybdate compound [Mn(CH3OH)6] [Mo8O16(OCH3)8(C2O4)] (2) in a complex redox reaction. Crystals of 2 were analyzed by single‐crystal X‐ray diffraction showing a octanuclear polyoxomolybdate dianion in which the Mo=O moieties are alternately connected through μ‐oxo and μ‐methoxo units. Charge balance in 2 is realized by a manganese(II) cation that is octahedrally coordinated by methanol ligands. The crystal structure is dominated by strong hydrogen bond interactions of the O–H···O type of methanol molecules coordinated to manganese as well as additional methanol molecules in the crystal lattice.
Solvothermal Synthesis and Structural Characterization of an Organic‐Templated New Aluminogermanate with the GIS Topology
Authors: Sun Xiaochang , Liu Yanbo , Chen Qi , Liu Bing , Zhu Dunru , Xu Yan
Published: August 2009

A new organic‐templated aluminogermanate [C4H12N][AlGe3O8] (1) has been prepared under solvothermal conditions by using 2‐propanol as solvent. The structure of the title compound was characterized by IR spectroscopic, elemental analysis, TG, single‐crystal X‐ray diffraction and powder X‐ray diffraction. Compound 1 crystallizes in the tetragonal space group I41/a, a = b = 10.7754(8) Å, c = 9.9116(14) Å, V = 1150.8(2) Å3, Z = 4. The structure of the title compound shows eight‐membered ring channels along a and b axes with a typical GIS topology, and – most importantly – the structure of the inorganic framework is retained when the organic amine is removed by calcination.
Synthesis and Crystal Structures of InGaO3(ZnO)m (m = 2 and 3)
Authors: Keller Isabelle , Assenmacher Wilfried , Schnakenburg Gregor , Mader Werner
Published: August 2009

An optimized high temperature route in sealed platinum tubes was used for synthesis of pure powders of members of the homologues series InGaO3(ZnO)m. Single crystals of InGaO3(ZnO)2 were grown from a K2MoO4 flux. InGaO3(ZnO)2 crystallises in the hexagonal crystal system (P63/mmc; No. 194), deduced from convergent beam electron diffraction (CBED). Single crystal structure refinement from XRD data (a = 3.2909(2) Å; c = 22.485(2) Å; Z = 2; 1603 data, R1 = 0.0237) revealed a compound which consists of an alternate stacking of [InO{}^‐_6/3]{}^\infty_2 and [(Ga,Zn)O{}^+_4/4]{}^\infty_3 corresponding to CdI2 and wurtzite type structure motifs, respectively. Inversions of the ZnO4 tetrahedra occurs (i) at the InO6 octahedral layer and (ii) halfway in the wurtzite type region where the inversion boundary is built by Ga3+ in trigonal bipyramidal coordination with a long Ga–Oapical distance of 2.138 Å. The site occupation of Zn2+ and Ga3+, respectively, was confirmed by valence sum calculations. The structure of InGaO3(ZnO)3 was refined from powder X‐ray diffraction data. InGaO3(ZnO)3 crystallises trigonal (R\bar{3}m; No. 166; a = 3.2871(9) Å; c = 41.589(1) Å, RBragg = 0.0506). The space group was confirmed by CBED. The structure of InGaO3(ZnO)3 is similar to InGaO3(ZnO)2, however, the wurtzite type part of the structure has an even number of closed packed oxygen layers and thus the inversion boundary within this area is different. The compounds described here have the structural charactistics as other known members of general formula (ARO3)·(ZnO)m with m = integer.
Charge Disproportionation and Charge Transfer in A‐site Ordered Perovskites Containing Iron
Authors: Shimakawa Yuichi , Takano Mikio
Published: August 2009

New A‐site ordered perovskite structure oxides, CaCu3Fe4O12 and LaCu3Fe4O12, were synthesized under high‐pressure and high‐temperature conditions. The compounds contain unusually high valence states of iron: Fe4+ in CaCu3Fe4O12 and Fe3.75+ in LaCu3Fe4O12. Instabilities of the high oxidation states at low temperatures are resolved in CaCu3Fe4O12 by charge disproportionation from Fe4+ to Fe3+ and Fe5+ and in LaCu3Fe4O12 by charge transfer between A‐site copper and B‐site iron ions. The charge disproportionation and the charge transfer are accompanied by significant changes in structural, transport, and magnetic properties.
Rapid Colonization with Methicillin‐Resistant Coagulase‐Negative Staphylococci After Surgery
Authors: Zingg Walter , Demartines Nicolas , Imhof Alexander , Senn Gabriela , Ruef Christian
Published: August 2009

Background

Antimicrobial resistance may compromise the efficacy of antibiotic prophylaxis before surgery. The aim of this study was to measure susceptibility and clonal distribution of coagulase‐negative staphylococci (CoNS) colonizing the skin around the surgery access site before and after the procedure.

Methods

From March to September 2004, a series of 140 patients undergoing elective major abdominal surgery were screened for CoNS colonization at admission and 5 days after surgery. All isolates were tested for antibiotic susceptibility and genotyped by pulsed‐field gel electrophoresis (PFGE).

Results

Colonization rates with CoNS at admission and after surgery were 85% and 55%, respectively. The methicillin‐resistant CoNS rate increased from 20% at admission to 47% after surgery (P = 0.001). The PFGE pattern after surgery revealed more patients colonized with identical clones: 8/140 patients (8/119 strains) and 26/140 patients (26/77 strains), respectively (P < 0.001).

Conclusions

Our results suggest rapid recolonization of disinfected skin by resistant nosocomial CoNS. Larger studies, preferably among orthopedic or cardiovascular patients, are required to clarify whether standard antibiotic prophylaxis with first‐ or second‐generation cephalosporins for CoNS infections may be compromised if the patient requires an additional intervention 5 days or more after the initial surgery.
Initial Management of Extensive Mesenteric Venous Thrombosis: Retrospective Study of Nine Cases
Authors: Cenedese Alice , Monneuse Olivier , Gruner Laurent , Tissot Etienne , Mennesson Nicolas , Barth Xavier
Published: August 2009

Background

The development of mesenteric venous thrombosis (MVT) does not necessarily require surgical intervention. The aim of this study was to assess the efficacy of avoiding early operative intervention, which can lead to significant sacrifice of the small bowel.

Methods

Patients with MVT were identified using the inpatient registry for the years between 2003 and 2007. Each patient’s past medical history, history of prior deep venous thrombosis or hypercoagulable state, clinical and biologic presentation, and computed tomography (CT) results were analyzed. The proportion of ischemic bowel observed on the CT scans was compared with the length of the bowel resected.

Results

Nine patients were admitted for extensive MVT during the time period evaluated (six men, three women). All CT scans demonstrated signs of severe bowel ischemia, with a mean ischemic bowel proportion of 21% (range 5–45%). Four patients received medical management alone. Five patients underwent surgery. The mean admission time for these patients prior to the operation was 14.8 days (6–36 days). Surgery was required only in cases of intestinal perforation. The mean length of the bowel resections was 33 cm (20–45 cm). At 6 months after admission, none of the patients required parenteral nutrition. The mean follow‐up evaluation period was 27 months (15–38 months). One patient died secondary to amyotrophic lateral sclerosis during the follow‐up.

Conclusions

Initial nonsurgical management comprised of inpatient observation on a surgical ward along with systemic anticoagulation must be considered an alternative treatment strategy for MVT. This strategy delays surgery and therefore avoids short bowel syndrome.
Helicopter Evacuation of Trauma Victims in Los Angeles: Does it Improve Survival?
Authors: Talving Peep , Teixeira Pedro G. R. , Barmparas Galinos , DuBose Joseph , Inaba Kenji , Lam Lydia , Demetriades Demetrios
Published: August 2009

Background

The purpose of this study was to investigate the relationship between the method of transport after injury and survival among trauma patients admitted to a Level 1 trauma facility in Los Angeles, California.

Methods

The trauma registry of LAC+USC Medical Center was reviewed to identify all injured patients evacuated by emergency medical service (EMS) from the injury scene from 1998 to 2007. The study population was divided into those who were airlifted (HEMS) and those who were transported by ground emergency medical service (GEMS) with transportation time that exceeded 30 minutes (GEMS > 30 minutes).

Results

During the 10‐year study period, 1,836 patients were airlifted (helicopters for emergency medical service (HEMS)) and 1,537 patients were ground transported (GEMS > 30 minutes). HEMS patients suffered more frequently a penetrating injury (19% vs. 11%, p < 0.001), presented more often hypotensive to the emergency department (4% vs. 1%, p < 0.001), had more frequently a Glasgow Coma Scale (GCS) ≤ 8 (9% vs. 3%, p < 0.001) and required more often an intubation at the injury scene (1.6% vs. 0.4%, p < 0.001). However, the transportation time and the total prehospital time were significantly shorter for airlifted patients. After multivariable analysis, the difference in mortality between the two transport modalities was not significant (adjusted odds ratio (95% confidence interval, 0.72 (0.22, 2.35); p = 0.596).

Conclusions

In a metropolitan Los Angeles trauma system, EMS helicopter transportation of injured patients does not appear to improve overall adjusted survival after injury. There is however a potential benefit for severely injured subgroups of patients due to the shorter prehospital times.
Doppler Ultrasound Could Predict Varices Progression and Rebleeding After Portal Hypertension Surgery: Lessons from 146 EGDS and 10 Years of Follow‐Up
Authors: Ferreira Fabio Gonçalves , Ribeiro Maurício Alves , de Fátima Santos Maria , Assef José César , Szutan Luiz Arnaldo
Published: August 2009

Background

Surgical treatment of variceal hemorrhagic complications for patients with schistosomal portal hypertension in our group comprised an esophagogastric devascularization procedure with splenectomy (EGDS). There are two different kinds of postoperative follow‐up: prophylactic or on‐demand endoscopic program of varices eradication. This program implies risks and costs and only proves necessary in 6–29% of cases. This study was designed to assess portal vein Doppler ultrasound data in these patients, and to verify correlations with progression in the number and size of varices, as well as the appearance of red spots and rebleeding during the postoperative period after EGDS.

Methods

Data on portal vein Doppler ultrasound from 146 patients with schistosomal portal hypertension and previous history of upper digestive bleeding due to esophagogastric varices rupture was analyzed. All subjects underwent EGDS and were analyzed before and after the procedure and compared postoperatively at four time points: 1 year, 2 years, up to 5 years, and up to 10 years. The following portal hemodynamic parameters were analyzed: diameter and mean blood flow velocity. Variceal size and number, presence of red spots, and rebleeding were all determined by endoscopic examination. Patients were divided into two groups at the each of the four time points, according to esophagogastric varices progression.

Results

Patients with variceal progression had significantly higher values of portal blood flow velocity. At time points I, II, III, and IV, the measured flow velocity from first postoperative year was 17.64 ± 4.84 vs. 13.81 ± 5.61 (p = 0.025); 16.74 ± 4.8 vs. 13.75 ± 5.8 (p = 0.039); 16.01 ± 5.00 vs. 13.23 ± 5.86 (p = 0.036); and 16.01 ± 5.00 vs. 13.23 ± 5.86 (p = 0.036), respectively.

Conclusions

Patients with schistosomal portal hypertension submitted to EGDS who had portal blood flow velocity >15.5 cm per second at the first postoperative year ha d progression of esophagogastric varices and a greater chance of rebleeding and, therefore, should be included in the endoscopic program for varices eradication.
SDS-PAGE-Based Quantitative Assay for Screening of Kidney Stone Disease
Authors: Wai-Hoe Lau , Wing-Seng Leong , Ismail Zhari , Lay-Harn Gam
Published: August 2009

Kidney stone disease is a common health problem in industrialised nations. We developed a SDS-PAGE-based method to quantify Tamm Horsfall glycoprotein (THP) for screening of kidney stone disease. Urinary proteins were extracted by using ammonium sulphate precipitation at 0.27 g salt/mL urine. The resulted pellet was dissolved in TSE buffer. Ten microliters of the urinary proteins extract was loaded and separated on 10% SDS-PAGE under reducing condition. THP migrated as single band in SDS-PAGE. The assay reproducibility and repeatability were 4.8% CV and 2.6% CV, respectively. A total of 117 healthy subjects and 58 stone patients were tested using this assay, and a distinct cut-off (P< 0.05) at 5.6 μg/mL THP concentration was used to distinguish stone patients from healthy subjects. The sensitivity and specificity of the method were 92.3% and 83.3%, respectively.
The relationship between patient and practitioner expectations and preferences and clinical outcomes in a trial of exercise and acupuncture for knee osteoarthritis
Authors: Foster Nadine E. , Thomas Elaine , Hill Jonathan C. , Hay Elaine M.
Published: August 2009

We investigated the relationship between patient and therapist preferences and expectations and clinical outcomes in a trial of exercise and acupuncture for clinical knee osteoarthritis.

352 Patients were randomised to advice and exercise or advice and exercise plus true or non‐penetrating acupuncture. Before randomisation, patients recorded their general outcome expectations, treatment‐specific preferences and expectations. Clinical outcome was (a) change scores on the Western Ontario and McMaster Osteoarthritis Index (WOMAC) and (b) treatment response according to the OMERACT‐OARSI criteria. Physiotherapists recorded their treatment expectations and preferences for each patient following an assessment prior to randomisation. We investigated the relationship between (a) patient, (b) therapist and (c) matched patient–therapist preferences and expectations on clinical outcomes using univariate and multivariate analyses.

There was no significant relationship between patients’ treatment preferences and clinical outcomes at 6 or 12months nor between patients’ expectations and pain (WOMAC) at 6 or 12months. Using our secondary outcome (OMERART‐OARSI), those who received the treatment for which they had high expectations of benefit were almost twice as likely to be classified as a treatment responder at 6months (odds ratio (OR) 1.7 (95% Confidence Interval 1.06, 2.79)) and 12months (OR) 1.9 (1.13, 3.13). Therapists’ preferences and expectations for individual patients did not add further explanation of outcomes.

There was no evidence of a relationship between patients’ treatment preferences or expectations and pain reduction. We found weak evidence, from secondary outcomes, that patients’ expectations, both general and treatment‐specific, are related to clinical outcome from exercise and acupuncture.
Restricted growth and insulin‐like growth factor‐1 deficiency in mice lacking presenilin‐1 in the neural crest cell lineage
Authors: Nakajima Mitsunari , Watanabe Sono , Okuyama Satoshi , Shen Jie , Furukawa Yoshiko
Published: August 2009

Presenilin‐1 (PS1) is a transmembrane protein that is in many cases responsible for the development of early‐onset familial Alzheimer's disease. PS1 is essential for neurogenesis, somitogenesis, angiogenesis, and cardiac morphogenesis. We report here that PS1 is also required for maturation and/or maintenance of the pituitary gland. We generated PS1‐conditional knockout (PS1‐cKO) mice by crossing floxed PS1 and Wnt1‐cre mice, in which PS1 was lacking in the neural crest‐derived cell lineage. Although the PS1‐cKO mice exhibited no obvious phenotypic abnormalities for several days after birth, reduced body weight in the mutant was evident by the age of 3–5 weeks. Pituitary weight and serum insulin‐like growth factor (IGF)‐1 level were also reduced in the mutant. Histologic analysis revealed severe atrophy of the cytosol in the anterior and intermediate pituitary lobes of the mutant. Immunohistochemistry did not reveal clear differences in the expression levels of thyroid‐stimulating hormone, adrenocorticotropic hormone, or prolactin in the mutant pituitary. In contrast, growth hormone expression levels were reduced in the anterior lobe of the mutant. PS1 was defective in the posterior lobe, but not the anterior or intermediate lobes, in the mutant pituitary. These findings suggest that PS1 indirectly mediates the development and/or maintenance of the anterior and intermediate lobes in the pituitary gland via actions in other regions, such as the posterior lobe.
Assessment of obstruction level and selection of patients for obstructive sleep apnoea surgery: an evidence-based approach
Authors: Georgalas C , Garas G , Hadjihannas E , Oostra A
Published: August 2009

Introduction:

Obstructive sleep apnoea has long been recognised as a clinical syndrome; however, high quality evidence on the effects of surgery for this condition is still missing. Despite this, a consensus seems to be evolving, albeit based on limited evidence, that surgery should be offered as a second line treatment to suitable patients with obstructive sleep apnoea.

Aims:

This article aims to assess the different methods of investigating upper airway obstruction in patients with obstructive sleep apnoea, in respect to these methods' relevance to surgical treatment, via a systematic review of the literature.

Methods:

The Cochrane Controlled Trials Register, Medline and EMBASE were searched from 1966 onwards. The search was performed in August 2008. A total of 2001 citations were retrieved.

Results and conclusion:

There is not yet a generally accepted way to assess surgical candidacy based on the level of obstruction. Better organised clinical studies with well defined endpoints are needed. In the meanwhile, it appears that sleep nasendoscopy, acoustic reflectometry and pressure catheters can all provide useful information, and their use may be decided upon based on the experience and resources available in individual departments.
Echinococcus species in African wildlife
Authors: HÜTTNER M. , ROMIG T.
Published: August 2009

Cystic echinococcosis, caused by different species of the Echinococcus granulosus complex, is an important zoonotic disease with a particular impact on pastoralist societies. In addition to the widespread taxa with synanthropic transmission, a number of Echinococcus species were described from African wild carnivores early in the 20th century. For lack of study material, most of these were later tentatively synonymized with E. granulosus. Early infection experiments with wildlife isolates gave ambiguous results due to the use of unspecified parasite material, and only recently molecular methods provided the opportunity to shed light on the confusing scenery e.g. by characterizing E. felidis from the African lion. Here we will summarize the convoluted history of Echinococcus research in sub-Saharan Africa and highlight the necessity of molecular surveys to establish the life cycles and estimate the zoonotic potential of these parasites.
Convergence analysis for the uncalibrated robotic hand–eye coordination based on the unmodeled dynamics observer
Authors: Su Jianbo
Published: August 2009

The uncalibrated robotic hand–eye coordination problem is firstly modeled by a dynamic system, where the unknown hand–eye relationship is regarded as the system's unmodeled dynamics. A state observer is then designed to estimate impacts of this modeling error together with the system's external disturbances. With the estimation results as the compensation, the system control is thus accomplished based on a nonlinear combination of the system state errors. Convergence analysis of the whole system under the proposed control scheme is emphasized. Simulations and experiment results are presented to verify the performance of the proposed approach.
A biologically inspired method for robot navigation in a cluttered environment
Authors: Teimoori Hamid , Savkin Andrey V.
Published: August 2009

The problem of wheeled mobile robot (WMR) navigation toward an unknown target in a cluttered environment has been considered. The biologically inspired navigation algorithm is the equiangular navigation guidance (ENG) law combined with a local obstacle avoidance technique. The collision avoidance technique uses a system of active sensors which provides the necessary information about obstacles in the vicinity of the robot. In order for the robot to avoid collision and bypass the enroute obstacles, the angle between the instantaneous moving direction of the robot and a reference point on the surface of the obstacle is kept constant. The performance of the navigation strategy is confirmed with computer simulations and experiments with ActivMedia Pioneer 3-DX wheeled robot.
Dynamic modeling of planar parallel robots considering passive joint sensor data
Authors: Zubizarreta Asier , Cabanes Itziar , Marcos Marga , Pinto Charles
Published: August 2009

Model-based advanced control approaches are needed to achieve high speed and acceleration and precision in robotic operations. These control schemes need a proper dynamic model. Many approaches have been proposed by different authors in order to obtain the dynamic model of these structures. However, most of them do not consider the possibility to introduce redundant sensor data. In this paper, a methodology for obtaining a compact dynamic model considering passive joint sensor data is proposed. The dynamic model is defined in compact and structured form, which makes it appropriate to be used in advanced control techniques.
Landmark detection and localization for mobile robot applications: a multisensor approach
Authors: Amarasinghe Dilan , Mann George K. I. , Gosine Raymond G.
Published: August 2009

This paper describes a landmark detection and localization using an integrated laser-camera sensor. Laser range finder can be used to detect landmarks that are direction invariant in the laser data such as protruding edges in walls, edges of tables, and chairs. When such features are unavailable, the dependant processes will fail to function. However, in many instances, larger number of landmarks can be detected using computer vision. In the proposed method, camera is used to detect landmarks while the location of the landmark is measured by the laser range finder using laser-camera calibration information. Thus, the proposed method exploits the beneficial aspects of each sensor to overcome the disadvantages of the other sensor. While highlighting the drawbacks and limitations of single sensor based methods, an experimental results and important statistics are provided for the verification of the affectiveness sensor fusion method using Extended Kalman Filter (EKF) based simultaneous localization and mapping (SLAM) as an example application.