bluuebunny/crossref_metadata_2025 huggingface dataset:
Endothelial Nuclear Factor-κB–Dependent Regulation of Arteriogenesis and Branching
Authors: Tirziu Daniela , Jaba Irina M. , Yu Pengchun , Larrivée Bruno , Coon Brian G. , Cristofaro Brunella , Zhuang Zhen W. , Lanahan Anthony A. , Schwartz Martin A. , Eichmann Anne , Simons Michael
Published: October 2012

Background—

Arteriogenesis and collateral formation are complex processes requiring integration of multiple inputs to coordinate vessel branching, growth, maturation, and network size. Factors regulating these processes have not been determined.

Methods and Results—

We used an inhibitor of NFκB activation (IκBαSR) under control of an endothelial-specific inducible promoter to selectively suppress endothelial nuclear factor-κB activation during development, in the adult vasculature, or in vitro. Inhibition of nuclear factor-κB activation resulted in formation of an excessively branched arterial network that was composed of immature vessels and provided poor distal tissue perfusion. Molecular analysis demonstrated reduced adhesion molecule expression leading to decreased monocyte influx, reduced hypoxia-inducible factor-1α levels, and a marked decrease in δ-like ligand 4 expression with a consequent decrease in Notch signaling. The latter was the principal cause of increased vascular branching as treatment with Jagged-1 peptide reduced the size of the arterial network to baseline levels.

Conclusions—

These findings identify nuclear factor-κB as a key regulator of adult and developmental arteriogenesis and collateral formation. Nuclear factor-κB achieves this by regulating hypoxia-inducible factor-1α–dependent expression of vascular endothelial growth factor-A and platelet-derived growth factor-BB, which are necessary for the development and maturation of the arterial collateral network, and by regulating δ-like ligand 4 expression, which in turn determines the size and complexity of the network.
B Vitamins and Magnetic Resonance Imaging–Detected Ischemic Brain Lesions in Patients With Recent Transient Ischemic Attack or Stroke
Authors: Cavalieri Margherita , Schmidt Reinhold , Chen Christopher , Mok Vincent , de Freitas Gabriel R. , Song Swithin , Yi Qilong , Ropele Stefan , Grazer Anja , Homayoon Nina , Enzinger Christian , Loh Katherine , Wong Ka Sing Lawrence , Wong Adrian , Xiong Yunyun , Chang Hui Meng , Wong Meng Cheong , Fazekas Franz , Eikelboom John W. , Hankey Graeme J.
Published: October 2012

Background and Purpose—

Elevated concentrations of homocysteine are associated with cerebral small vessel disease (CSVD). b-vitamin supplementation with folate and vitamins b
12
and b
6
reduces homocysteine concentrations. In a substudy of the VITAmins TO Prevent Stroke (VITATOPS) trial, we assessed the hypothesis that the addition of once-daily supplements of b vitamins would reduce the progression of CSVD-related brain lesions.

Methods—

A total of 359 patients with recent stroke or transient ischemic attack, who were randomly allocated to double-blind treatment with placebo or b vitamins, underwent brain MRI at randomization and after 2 years of b-vitamin supplementation. MR images were analyzed blinded to treatment allocation. Outcomes related to the prespecified hypothesis were progression of white matter hyperintensities and incident lacunes. We also explored the effect of b-vitamin supplementation on the incidence of other ischemic abnormalities.

Results—

After 2 years of treatment with b vitamins or placebo, there was no significant difference in white matter hyperintensities volume change (0.08 vs 0.13cm
3
;
P
=0.419) and incidence of lacunes (8.0% vs 5.9%,
P
=0.434; odds ratio=1.38). In a subanalysis of patients with MRI evidence of severe CSVD at baseline, b-vitamin supplementation was associated with a significant reduction in white matter hyperintensities volume change (0.3 vs 1.7cm
3
;
P
=0.039).

Conclusions—

Daily b-vitamin supplementation for 2 years did not significantly reduce the progression of brain lesions resulting from presumed CSVD in all patients with recent stroke or transient ischemic attack but may do so in the subgroup of patients with recent stroke or transient ischemic attack and severe CSVD.

Clinical Trial Registration—

http://vitatops.highway1.com.au/
. Unique identifier: NCT00097669 and ISRCTN74743444.
Driftsonde Observations to Evaluate Numerical Weather Prediction of the Late 2006 African Monsoon
Authors: Drobinski Philippe , Karbou Fatima , Bauer Peter , Cocquerez Philippe , Lavaysse Christophe , Hock Terry , Parsons David , Rabier Florence , Redelsperger Jean-Luc , Vénel Stéphanie
Published: October 2012

During the international African Monsoon Multidisciplinary Analysis (AMMA) project, stratospheric balloons carrying gondolas called driftsondes capable of dropping meteorological sondes were deployed over West Africa and the tropical Atlantic Ocean. The goals of the deployment were to test the technology and to study the African easterly waves, which are often the forerunners of hurricanes. Between 29 August and 22 September 2006, 124 sondes were dropped over the seven easterly waves that moved across Africa into the Atlantic between about 10° and 20°N, where almost no in situ vertical information exists. Conditions included waves that developed into Tropical Storm Florence and Hurricanes Gordon and Helene. In this study, a selection of numerical weather prediction model outputs has been compared with the dropsondes to assess the effect of some developments in data assimilation on the quality of analyses and forecasts. By comparing two different versions of the Action de Recherche Petite Echelle Grande Echelle (ARPEGE) model of Météo-France with the dropsondes, first the benefits of the last data assimilation updates are quantified. Then comparisons are carried out using the ARPEGE model and the Integrated Forecast System (IFS) model of the European Centre for Medium-Range Weather Forecasts. It is shown that the two models represent very well the vertical structure of temperature and humidity over both land and sea, and particularly within the Saharan air layer, which displays humidity below 5%–10%. Conversely, the models are less able to represent the vertical structure of the meridional wind. This problem seems to be common to ARPEGE and IFS, and its understanding still requires further investigations.
A New HadGEM3-A-Based System for Attribution of Weather- and Climate-Related Extreme Events
Authors: Christidis Nikolaos , Stott Peter A. , Scaife Adam A. , Arribas Alberto , Jones Gareth S. , Copsey Dan , Knight Jeff R. , Tennant Warren J.
Published: October 2012

A new system for attribution of weather and climate extreme events has been developed based on the atmospheric component of the latest Hadley Centre model. The model is run with either observational data of sea surface temperature and sea ice or estimates of what their values would be without the effect of anthropogenic climatic forcings. In that way, ensembles of simulations are produced that represent the climate with and without the effect of human influences. A comparison between the ensembles provides estimates of the change in the frequency of extremes due to anthropogenic forcings. To evaluate the new system, reliability diagrams are constructed, which compare the model-derived probability of extreme events with their observed frequency. The ability of the model to reproduce realistic distributions of relevant climatic variables is another key aspect of the system evaluation. Results are then presented from analyses of three recent high-impact events: the 2009/10 cold winter in the United Kingdom, the heat wave in Moscow in July 2010, and floods in Pakistan in July 2010. An evaluation assessment indicates the model can provide reliable results for the U.K. and Moscow events but not for Pakistan. It is found that without anthropogenic forcings winters in the United Kingdom colder than 2009/10 would be 7–10 times (best estimate) more common. Although anthropogenic forcings increase the likelihood of heat waves in Moscow, the 2010 event is found to be very uncommon and associated with a return time of several hundred years. No reliable attribution assessment can be made for high-precipitation events in Pakistan.
The Efficiency of Assimilating Satellite Soil Moisture Retrievals in a Land Data Assimilation System Using Different Rainfall Error Models
Authors: Maggioni Viviana , Reichle Rolf H. , Anagnostou Emmanouil N.
Published: October 2012

The efficiency of assimilating near-surface soil moisture retrievals from Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) observations in a Land Data Assimilation System (LDAS) is assessed using satellite rainfall forcing and two different satellite rainfall error models: a complex, multidimensional satellite rainfall error model (SREM2D) and the simpler (control) model (CTRL) used in the NASA Goddard Earth Observing System Model, version 5 LDAS. For the study domain of Oklahoma, LDAS soil moisture estimates improve over the satellite retrievals and the open-loop (no assimilation) land surface model estimates, exhibiting higher daily anomaly correlation coefficients (e.g., 0.36 in the open loop, 0.38 in the AMSR-E, and 0.50 in LDAS for surface soil moisture). The LDAS soil moisture estimates also match the performance of a benchmark model simulation forced with high-quality radar precipitation. Compared to using the CTRL rainfall error model in LDAS, using the more complex SREM2D exhibits only slight improvements in soil moisture estimates.
Mapping Mean Monthly Temperatures over a Coastal Hilly Area Incorporating Terrain Aspect Effects
Authors: Guan Huade , Zhang Xinping , Makhnin Oleg , Sun Zhian
Published: October 2012

Efforts in the past two decades on air temperature mapping based on sparse monitoring networks reveal that algorithms based on multiple linear regressions with geographical and topographical parameters perform promisingly. In this study, a multiple-regression model, previously for precipitation characterization using autosearched orographic and atmospheric effects (PCASOA), is applied to analyze spatial distribution of mean monthly daily maximum and minimum temperatures (at 33 stations) in Adelaide and the Mount Lofty Ranges (9000 km2), a coastal hilly area in South Australia. Terrain aspect (or slope orientation) is transformed and explicitly incorporated in the model, together with some other topographic variables. Overall, PCASOA captures 91% and 70% observed spatial variability for mean monthly maximum (Tmax) and minimum (Tmin) temperature, respectively. The regression also infers some physical processes influencing the air temperature distribution. The results indicate horizontal gradients of Tmax in the east–west and north–south directions, which can be related to the effects of dominant wind directions in the study area. The effect of terrain ruggedness on Tmax is likely related to the blockage of sea breeze in the complex terrain. Cold air drainage potential only influences Tmin during winter months in the study area. Terrain slope and aspect significantly contribute to interpreting Tmin spatial distribution and can be related to their sheltering effect from the dominant cool inland winds. They also contribute to interpreting Tmax spatial distribution, while the physical mechanism is not clear.
Influence of a Radome on Antenna Performance
Authors: Frech Michael , Lange Bertram , Mammen Theo , Seltmann Joerg , Morehead Chris , Rowan Joshua
Published: October 2012

The German Meteorological Service [Deutscher Wetterdienst (DWD)] operates the German weather radar network and is currently replacing all radar systems with new dual-polarization radars. One of the key components of a radar system is its antenna. The quality of the dual-polarized (dual-pol) moments is dependent on the quality of the antenna and its proper characterization. Dedicated on-site antenna pattern measurements with and without radome are performed in order to verify the antenna and radome specification of the new Hohenpeissenberg radar. Those on-site measurements are carried out from three different source sites in the far field of the antenna. The pattern measurements show that the main antenna specifications, such as the 3-dB beamwidth, beam squint, and sidelobe levels, are met. This is also true if a radome is in place. However, the data suggest that the manufacturer’s specifications are not fulfilled completely. This study finds a substantial increase of the copolar power level off the main beam. The homogeneity of the main beam with respect to differential power and phase is degraded with the radome. The measurements based on the three source sites indicate that a small (but negligible) radome-induced azimuthal variability of the radar moments can be expected. The integrated cross-polarization ratio based on the pattern measurement suggests that 1.4 dB of sensitivity is lost in the linear depolarization ratio (LDR) due to the dry radome.
A Cooling Climate for Change? Party Polarization and the Politics of Global Warming
Authors: Guber Deborah Lynn
Published: October 2012

Analysis of three cross-sectional polls administered by the Gallup Organization at 10-year intervals—in 1990, 2000, and 2010—demonstrates that partisan identification has become an increasingly important determinant of environmental concern within the American mass public. Polarization on global warming is especially clear, even when compared to a variety of other social, economic, and political problems, but party sorting seems to occur only as citizens acquire information and become familiar with elite cues. The implications of this for the U.S. environmental movement and the strategies it employs are discussed.
Design of dye-sensitized solar cells integrated in composite panel subjected to bending
Authors: Nagata Morio , Baldwin Eli , Kim Sooyeun , Taya Minoru
Published: October 2012

This article discusses the design of airborne dye-sensitized solar cell (DSSC) panel integrated in the airplane composite panel which is subjected to mechanical dynamic loading so that the DSSC will function continuously as airborne energy harvester. This article consists of two parts, first synthesis of more rubut DSSC, and then its integration into a composite panel with durability demonstrated.
Strain energy based failure criterion: Comparison of numerical predictions and experimental observations for symmetric composite laminates subjected to triaxial loading
Authors: Doudican Bradley M , Zand Behrad , Amaya Peter , Butalia Tarunjit S , Wolfe William E , Schoeppner Gregory A
Published: October 2012

An analytical model to predict the constitutive response, failure initiation and post-initial failure behavior of fibrous composites under triaxial loading has been developed based on a strain energy formulation. This paper highlights the means of developing several key parameters in the model and extends the model to include the effects of in-plane thermal residual stresses accumulated during the curing of composite laminates. The derivations of a set of consistent model input parameters for several composite material systems are described. A series of comparative stress-strain curves and failure envelopes are provided comparing model predictions to published experimental data. The strain energy based failure model is found to provide good agreement with the experimental observations studied in this work.
Dynamic mechanical analysis and free vibration behavior in chemical modifications of coconut sheath/nano-clay reinforced hybrid polyester composite
Authors: Rajini N , Jappes JT Winowlin , Rajakarunakaran S , Jeyaraj P
Published: October 2012

Naturally woven coconut sheath, a new natural fiber available in the form of woven mat is used as fiber reinforcement in polyester matrix. The hybridization effect of montmorillonite (MMT) on naturally woven coconut sheath/polyester composite has been investigated experimentally for free vibration characteristics using impulse excitation technique (IET). In the present study, naturally woven coconut sheath/clay-reinforced hybrid polyester composites were fabricated using a compression molding machine. The effect of organoclay addition (1, 2, 3 and 5 wt%), alkali (ATC) and silane treatment (STC) of the coconut sheath surface on free vibration characteristics were analyzed. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques were used to characterize the morphology of coconut sheath and structure of clay dispersed polyester. The dynamic mechanical analysis (DMA) and Fourier transform infrared (FTIR) analysis were carried out to analyze the effect of surface topology on chemically treated coconut sheath. The mechanism of chemical modifications on natural frequencies and the resultant improvement in the temperature dependence mechanical properties have also been reported. Enhanced vibration properties are observed up to 3 wt% of clay dispersion in hybrid composites, then it gets reduced for higher clay (>3 wt%) content. Modal damping of the hybrid composite is influenced by the addition of nanoclay and the surface treatments of the coconut sheath. Experimentally obtained natural frequencies are in good agreement with analytical and numerical results.
Hybrid polyethylene/polypropylene blended fiber-reinforced cement composite
Authors: Silva ER , Coelho JFJ , Bordado JC
Published: October 2012

This article reports the results of a study related to the reinforcement of mortar-based composites with newly developed polyethylene/polypropylene blended fibers. The study showed the hybrid fibers to have a mechanical/reinforcing effect in the cement-based matrix. Mechanical strengths improvements, as high as 40 ± 2%, were obtained for composites with a fiber length of 24 mm and a fiber volume fraction of 2.9%.

The mechanical enhancement was associated with a strong mechanical interlocking between the fibers/cement matrix interfaces promoted by the fibers’ surface ridges and fibrillation ability. Macro/microstructure and morphological observations showed a post-cracking ductility improvement of composites by the hybrid (bridge effect) fibers, also evidenced a multi-cracking mechanism.
Examining the Acquisition of Phonological Word Forms with Computational Experiments
Authors: Vitevitch Michael S , Storkel Holly L
Published: October 2012

It has been hypothesized that known words in the lexicon strengthen newly formed representations of novel words, resulting in words with dense neighborhoods being learned more quickly than words with sparse neighborhoods. Tests of this hypothesis in a connectionist network showed that words with dense neighborhoods were learned better than words with sparse neighborhoods when the network was exposed to the words all at once (Experiment 1), or gradually over time, like human word-learners (Experiment 2). This pattern was also observed despite variation in the availability of processing resources in the networks (Experiment 3). A learning advantage for words with sparse neighborhoods was observed only when the network was initially exposed to words with sparse neighborhoods and exposed to dense neighborhoods later in training (Experiment 4). The benefits of computational experiments for increasing our understanding of language processes and for the treatment of language processing disorders are discussed.
Linking Survey and Administrative Records
Authors: Sakshaug Joseph W. , Couper Mick P. , Ofstedal Mary Beth , Weir David R.
Published: October 2012

Survey records are increasingly being linked to administrative databases to enhance the survey data and increase research opportunities for data users. A necessary prerequisite to linking survey and administrative records is obtaining informed consent from respondents. Obtaining consent from all respondents is a difficult challenge and one that faces significant resistance. Consequently, data linkage consent rates vary widely from study to study. Several studies have found significant differences between consenters and nonconsenters on sociodemographic variables, but no study has investigated the underlying mechanisms of consent from a theory-driven perspective. In this study, we describe and test several hypotheses related to respondents’ willingness to consent to an earnings and benefit data linkage request based on mechanisms related to financial uncertainty, privacy concerns, resistance toward the survey interview, level of attentiveness during the interview, the respondents’ preexisting relationship with the administrative data agency, and matching respondents and interviewers on observable characteristics. The results point to several implications for survey practice and suggestions for future research.
Symbolic modelling and predictive assessment of air source heat pumps
Authors: Murphy Gavin , Counsell John , Baster Eric , Allison John , Counsell Sean
Published: October 2012

This article extends a novel advanced dynamic calculation method (IDEAS – Inverse Dynamics based Energy Analysis and Simulation) of assessing the controllability of a building and its servicing systems. IDEAS allows confident (i.e. calibrated in SAP) predictions to be made regarding the impact of novel heating and renewable energy systems. IDEAS can be used as a dynamic sizing tool for a heating system in a building and can be used to benchmark control systems performance as it can represent near perfect control. The addition of an air source heat pump model to IDEAS is described. This allows for detailed analysis to be made of air source heat pumps in a SAP-compliant framework, taking into account the dynamic nature of the system efficiency and thermal capacity.

Practical applications: ASHPs are still a relatively novel technology in the UK, yet it has been suggested they could play a significant role in efforts to de-carbonise the heating sector. However field trials have found performance varies widely from installation to installation. Whilst some of this variation is due to user behaviour, ASHP systems are also very sensitive to design and commissioning. Fundamental methodologies which can provide detailed analysis of ASHP performance, such as that presented in this article, could contribute to improving system design standards. This would ensure more installations achieve a good level of performance, boosting confidence in the technology.
Data Envelopment Analysis modeling for measuring knowledge management performance in Malaysian higher educational institutions
Authors: Kuah Chuen Tse , Wong Kuan Yew
Published: October 2012

The paper aims to propose a new Knowledge Management (KM) performance measurement model based on Data Envelopment Analysis (DEA). The proposed model was constructed using a two-level DEA model. It measures KM using 17 proxy measures correlated with the major KM processes. Data from 19 Malaysian higher educational institutions were collected using a questionnaire and analyzed using the proposed model. For every institution, the model provides a single KM performance score together with performance scores of the major KM processes. Furthermore, the results indicate the specific KM areas that an organization should improve. The results can also be used by the institutions to determine their future KM strategies and targets. Finally, directions for future research are identified and suggested.
The Deliberate Low-Wage, High-Insecurity Economic Model
Authors: Madrick Jeff
Published: October 2012

In contrast to the general biases of orthodox economists, the jobs crisis in America is not inevitable or natural—and more important, does not contribute to more economic efficiency through lower wages or more productivity. It is the result of deliberate political policy choices the nation has made at least since the early 1980s, when productivity was rising on a secular basis at a slow rate. Also, the policy choices were made before the rise of very low-wage emerging markets like China’s. In sum, there has been a low-wage, high-unemployment policy regime in the rich world, and especially in the United States, for a generation.
The Politics of Job Quality
Authors: Osterman Paul , Chimienti Elizabeth
Published: October 2012

In Good Jobs, Bad Jobs Arne Kalleberg provides an extremely useful portrait of job quality in America. This paper addresses the politics of job quality via a case study of weatherization jobs. Weatherization workers are typical of employees in many low wage jobs in America. The stimulus bill (the American Recovery and Reinvestment Act) substantially increased weatherization funding and a political struggle emerged over the quality of these jobs. We find that the variable strength of progressive coalitions, legislative politics and timing all contributed to the development of an uneven set of regulations at the federal and local level. Groups that are putative allies often worked at cross-purposes. More strikingly government at both the local and Federal level has been conservative and even timid about establishing job standards. There are also more positive lessons. Training standards are being formalized. This stands to benefit both homeowners and workers. While there have been conflicts, it is also true that interests that have been historically at each other’s throats notably unions and community groups–found a way to work together more constructively than in the past.
Dualism, Job Polarization, and the Social Construction of Precarious Work
Authors: Vallas Steven , Prener Christopher
Published: October 2012

Publication of Arne Kalleberg’s Good Jobs, Bad Jobs provides a welcome opportunity to re-examine the theoretical and conceptual frameworks that scholars bring to bear on precarious employment. An exemplar of what was once called the “new structuralism,” Kalleberg’s book provides a rigorous, multidimensional analysis of the changes impinging on job stability and security. Although it identifies a vitally important trend toward a growing polarization in the distribution of job rewards, it does so in ways that illustrate the limits of the genre of research to which it belongs. Constrained to view the subjective experience of work as merely dependent variables, the book cannot explore how social, political, and cultural processes have both shaped and legitimated the rise of precarious employment. Drawing on recent studies of the popular business press and other media representations, we document the rise of a culture of enterprise that has idealized the uncertainties that have come to grip the labor market, defining the latter as a site on which individual agency can freely unfold. Only by addressing the interplay between job structures and such discursive and political developments can we hope to understand the rise of labor market precarity, let alone expand workers’ rights to protection against market uncertainty.
Job Quality and Precarious Work
Authors: Kalleberg Arne L.
Published: October 2012

In this article, the author engages with the authors of the articles in this Special Issue by clarifying some aspects of the arguments in Good Jobs, Bad Jobs: The Rise of Polarized and Precarious Employment Systems in the United States, 1970s to 2000s; addressing selected matters of controversy; and highlighting central policy challenges raised by the rise of polarized and precarious employment systems. The author organizes his comments around several key themes raised by these authors: The causes of changes in job quality; the polarization model; cross-national differences in precarious work; and policy recommendations and the politics of job quality.
Thermal, dielectric and compressive properties of hollow glass microsphere filled epoxy-matrix composites
Authors: Zhu Bailin , Ma Jing , Wang Jian , Wu Jun , Peng Dongsheng
Published: October 2012

Four types of hollow glass microspheres, having the density of 0.125–0.60 g/cm3, were filled into epoxy-matrix, and volume fraction of hollow glass microsphere was varied from 0% to 60%. The thermal, dielectric and compressive properties of the composites were investigated. The results show that the thermal conductivity, dielectric constant (Dk) and loss (Df) and compressive modulus and strength of the composites show decreased trend with increasing hollow glass microsphere content or decreasing hollow glass microsphere density, which indicates that the properties of the composites are mainly dependent on the characteristics of hollow glass microsphere. By comparing the experimental data and theoretical predictions, it is found that the properties of the composites, especially for thermal conductivity, are also related to the voids in epoxy-matrix. To conveniently predict thermal conductivity and Dk in the investigated materials system, theoretical models reported in the literature are analyzed and compared with the experimental data. Finally, suitable models are recommended. In addition, the thermal conductivity and dielectric properties of the composites were investigated as a function of testing temperature. This work indicates that thermal, dielectric and compressive properties of epoxy-matrix composites can be tailored by adjusting hollow glass microsphere content and density, which makes hollow glass microsphere filled composites a promising candidate in related fields.
Effect of water glass treatment on the mechanical and thermooxidative properties of kenaf and sisal fibres
Authors: Khoathane Moshibudi C , Sadiku Emmanuel R , Wambua Paul M
Published: October 2012

In this article, the effect of water glass on the mechanical and thermooxidative properties of kenaf and sisal fibres has been investigated. Single fibres were manually separated from the bundles and immersed in liquid water glass that produced a thick polysilicate coating. The water glass treatment significantly improved the tensile strength and the Young’s modulus of the kenaf and sisal fibres, in relation to the untreated fibres. The improved failure strain of sisal fibre could have occurred because the axial splitting is promoted and the transverse cracking is delayed by the water glass treatment. The reduced thermal resistance of the water glass treated sisal is even more interesting when considering that NaOH treatment (major constituent of water glass) of sisal caused an opposite effect. The thermogravimetric analysis results showed that the water glass treatment strongly affected the chemical composition of the kenaf and sisal fibres. The water glass based thick polysilicate coating was about 40 wt%, which was unusually high.
Mechanical and free vibration properties of montmorillonite clay dispersed with naturally woven coconut sheath composite
Authors: Rajini N , Jappes JT Winowlin , Rajakarunakaran S , Jeyaraj P
Published: October 2012

In this investigation, naturally woven coconut sheath is used as a new type of reinforcement. The hybrid composites are developed with the combination of naturally woven coconut sheath/E-glass/nanoclay using unsaturated polyester matrix and the effect of nanoclay on the mechanical and free vibration behavior is studied. It is found that the addition of nanoclay improved the mechanical and damping properties of the composite owing to the improved stiffness of the matrix by better dispersion of clay. In addition, the effect of alkali and silane treatments on fibers and different stacking sequence were investigated. It was observed that the alkali treatment of fibers improved the mechanical properties of the composites when cellulose fiber was present. This investigation presented a peculiar result in the case of silane treatment with the nanoclay, which is in contradiction with the earlier works. The stacking sequence of coconut sheath/coconut sheath/glass with alkali treatment of fibers provides the optimum increase in mechanical strength and free vibration characteristics. X-ray diffraction and transmission electron microscope were performed to understand the dispersion of nanoclay and its strengthening mechanism. In addition, scanning electron microscopy was used for fractography analysis. This investigation suggests an alternative material for the field of composites.
Polylactide/modified layered silicates nanocomposites: A critical analysis of morphological, mechanical and thermal properties
Authors: Prakalathan K , Mohanty Smita , Nayak Sanjay K
Published: October 2012

Polylactide/organically modified layered silicate nanocomposites were fabricated using melt blending technique in a twin screw extruder. Variation in mechanical properties and thermal stability with the addition of three types of commercial nanoclays namely Cloisite 15A, Cloicite 25A, Cloicite 93A in polylactide were investigated. It was observed that the tensile, flexural and impact properties of polylactide increase with increase in organically modified layered silicate from 1 to 7 wt%. Nanocomposites prepared with 5 wt% organically modified layered silicate exhibited optimum mechanical performance. Polylactide/C93A nanocomposites exhibited optimum mechanical performance as compared with virgin polylactide. Dynamic mechanical analysis indicated an increase in storage modulus (E′) with the incorporation of organically modified organoclays. Differential scanning calorimetry and thermogravimetric analysis thermogram in the nanocomposites also showed improved thermal stability when compared with virgin polylactide. X-ray diffraction studies showed an increase in overall d-spacing in polylactide/C93A nanocomposites indicating intercalated structure.
Influence of processing temperatures on fiber dimensions and microstructure of polypropylene/hemp fiber composites
Authors: Gong Yuewu , Niu Pengfei , Wang Xiaojun , Long Shengru , Yang Jie
Published: October 2012

The processing characteristic of polypropylene/hemp fiber composite, at various melt-compounding temperatures between 180 and 230°C, was characterized by torque rheometry. Hemp fibers were extracted from polypropylene/hemp fibers composites (melt-compounded at 180, 200, and 230°C, respectively), in a Soxhlet extractor with xylene. The length distribution, aspect ratio distribution, and the diameter of hemp fibers were measured, and the relationship between fiber dimensions and the processing temperature was investigated. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were employed to characterize the changes in fiber morphology and microstructure after melt-compounding. Fiber dimensions statistical results show that fiber length and aspect ratio distribution become narrow and shift to short average values as the processing temperature is raised. In addition, elevated processing temperature induces a remarkable decrease of fiber average diameter. Fourier transform infrared spectroscopy and X-ray diffraction results reveal that heat and shear forces applied to hemp fibers cause the reduction of cellulose relative content and the formation of amorphous components. When the processing temperature is higher than 200°C, irregular fracture morphology of hemp fibers and remarkable decrease in fiber average diameter indicate that hemp fibers’ amorphous components, such as hemicellulose and lignin, undergo apparent decomposition at higher processing temperature.
Influence of pre-treatments on the mechanical properties of palmyra palm leaf stalk fiber–polyester composites
Authors: Thiruchitrambalam M , Shanmugam D
Published: October 2012

Palmyra palm leaf stalk fibers were subjected to various chemical pre-treatments like Mercerization, benzoylation, and permanganate treatment with the aim of improving the adhesion with the matrix. Composites were prepared by reinforcing untreated and pre-treated fibers in unsaturated polyester matrix and mechanical performances are studied. The Mercerized and benzoyl-treated fiber composites had an improvement of around 60% in tensile strength while the tensile modulus increased by 37% and 60%, respectively. In the case of permanganate-treated fiber composites, the flexural strength increased by 70% and flexural modulus increased by 110% in comparison to the untreated composites. The impact strength for the Mercerized and permanganate-treated fiber composite improved by 55% and 42% in comparison to the untreated fiber composites, respectively. Chemical pre-treatment of fibers reduced water absorption of the composites. The benzoyl chloride treated fibers absorbed less water in comparison to the untreated fiber composites. Thermogravimetric analysis showed that the reinforcing-treated fiber has enhanced the thermal stability of the composites. Scanning electron microscope fractographs of the composites revealed the presence of good adhesion between the fibers and matrix compared to the untreated fiber composites. The composites exhibited comparable properties with other composites based on natural fibers.
Structure–electrical conductivity of polyvinylidene fluoride/graphite composites
Authors: Salam MH Abd-El , Elkomy GM , Osman H , Nagy MR , El-Sayed F
Published: October 2012

Graphite powder was introduced into polyvinylidene fluoride via the solution mixing technique. The composites were then subjected to hot compression molding. The effect of dispersion of graphite particles and electrical conductivity of the composites were investigated. Solution mixing enabled homogeneous dispersion of graphite powder within the polyvinylidene fluoride matrix as revealed by transmission electron microscopy. X-ray diffraction and Fourier transform infrared spectroscopy analysis revealed that graphite incorporation induced the α-phase of polyvinylidene fluoride. The DC conductivity results showed that the conductivity increased with an increase in graphite content. Beyond a critical concentration of graphite, percolation threshold, (Φ c = 2.3 vol%) the conductivity increases by five orders of magnitude at 3.9 vol% of graphite powder composite. The electrical conductivity was approximately constant for the composites with the higher graphite loading. Consequently, adding more graphite powder did not significantly alter the electrical conductivity. The correlation between the dispersion of graphite particles and electrical conductivity was discussed. The AC conductivity of composites was investigated in a wide range of frequencies from 50 Hz to 5 MHz and at temperatures ranging from room temperature to 180°C. The conductivity of the composites exhibited strong frequency dependence particularly in the vicinity of the electrical percolation threshold. σAC obeyed the power law of the form: [Formula: see text], where ω is the angular frequency and s and A the characteristic parameters. The values of the exponent ( s) were found to decrease with increasing temperature which is consistent with the correlated barrier-hopping model.
A Pilot Study to Explore the Safety of Perioperative Postpyloric Enteral Nutrition
Authors: McElroy Lisa M. , Codner Panna A. , Brasel Karen J.
Published: October 2012

Background: The practice of holding enteral nutrition (EN) 8 hours prior to surgery is common. We hypothesized that it was safe to continue postpyloric EN, and we developed an institutional practice pattern to investigate our hypothesis. Methods: Our pilot study included intubated patients in the surgical intensive care unit at Froedtert Memorial Lutheran Hospital who received EN via a nasojejunal (NJ) feeding tube and underwent 1 or more surgical procedures. Demographic, illness, and injury information were collected as well as length of time to NJ placement, time to initiation of EN, EN interruptions, and complications. Additional hours of EN were calculated by totaling the number of hours a patient received EN past midnight on the day of surgery. Results: A total of 14 patients with mean (SD) age 44.3 (19.9) were included. Patients had a mean (SD) Injury Severity Score (ISS) of 26.1 (9.2) on admission and underwent a total of 38 operations following placement of a feeding tube. The most frequent operation performed was an orthopedic procedure (n = 17; 46.1%). The mean (SD) length of EN interruptions for a single procedure was 222.4 (206.9) minutes. Patients received an additional 11.9 (4.7) hours of EN over the course of their hospitalization and an additional 1064.9 (490) kcal/d per operation. There were no adverse events. Conclusion: Perioperative continuation of postpyloric EN is feasible in some critically ill surgical patients and can result in additional calories provided. A multidisciplinary approach and an institutional policy can increase the likelihood of meeting nutrition goals in these patients.
Electoral agency in the lab: Learning to throw out the rascals
Authors: Helland Leif , Monkerud Lars
Published: October 2012

Models of electoral agency address the levels of discipline and selection that voters can achieve in elections. The models are demanding in terms of individual belief formation and consistency of behavior. We investigate a baseline model of electoral agency in a controlled laboratory environment. This baseline model, although simple, forms the central plank of more complex electoral agency models. Our design seeks to limit the behavioral impact of social preferences. We find little support for the baseline model in our data. However, simple (non-rational) learning rules explain behavioral patterns well. Simulations indicate that non-rational learning drives behavior most forcefully towards equilibrium in situations that are favorable to Bayesian updating.
‘CONGRATS!! You had an orgasm’: Constructing orgasm on an internet discussion board
Authors: Frith Hannah
Published: October 2012

Drawing on insights from conversation analysis, this article explores a discussion about orgasm on an internet forum. Critical of sex education for failing to address young women as sexual subjects with embodied desires, some feminists believe the internet offers alternative spaces for young women to discuss pleasure. I argue that the micro-political work done by offering ‘congratulations’ on one such site serves to mark young women’s orgasms as both ‘newsworthy’ and ‘good news’ in ways which simultaneously disrupt the idea that sexuality is inappropriate for young women while paradoxically reaffirming conventional ideas about the centrality of orgasm to sexuality.
Numerical modeling of arch dam under blast loading
Authors: Xue Xinhua , Yang Xingguo , Zhang Wohua
Published: October 2012

The damage of unallowable blast induced vibrations on the concrete structures results in a decrease in the safety of its structures. This paper develops a three dimensional anisotropic dynamic damage model for Dagangshan arch dam subjected to blast loading. The multiple damage failure criteria are adopted as the failure criteria of the dynamic damage evolution of concrete. From the simulation of the dynamic damage process in the arch dam due to the blast loading, some process fields of the dynamic displacement, the dynamic stress, dynamic damage distribution and other necessary information for the safety evaluation are obtained. The results obtained using the proposed model show that the nonlinear behavior of concrete dams can be satisfactorily predicted. This will provide a reasonable theoretical support on the safety evaluation of the capability of concrete arch dams against blast loading and useful information for further research in these areas.
Parametric excitation and wavelet transform analysis of a ground vehicle propeller shaft
Authors: Alugongo Alfayo A
Published: October 2012

This paper proposes a numerical model for analyzing torsional vibration of a ground vehicle propeller shaft system. By considering the elasticity and energy of the propeller system, a Lagrangian approach has been used to derive the equation of motion, yielding a highly nonlinear three degree-of-freedom system with five coupled inertias. The model takes into account the dynamics of a Hooke’s joint, a crack-induced parametric excitation, tractive torque at the driving wheels and transient vibration of a rear drive ground vehicle transmission. The forces exciting the vibrations of the propeller shaft system are evaluated by quantifying the tractive forces at the road wheels, Hooke’s joint force, the crack force and the forces emanating from the engine through the clutch and gear box. Subsequently, the forces are projected onto the propeller shaft by either direct coupling or by gearing. Consequently, the nonstationary response of the system in various scenarios has been determined and evaluated by a wavelet transform. By analysis, it is demonstrated that the model is useful for investigating nonlinear vibration of a typical propeller shaft system used in light ground vehicles.
The effect of aspect ratios and edge conditions on the optimal damping design of thin soft core sandwich plates and beams
Authors: Li Jinqiang , Narita Yoshihiro
Published: October 2012

An optimal design is presented to maximize the fundamental damping loss factor of sandwich rectangle plates and beams with general boundary conditions. With an extensive development of the classical laminate theory and energy method, the loss factor of sandwich laminate with a thin viscoelastic core is deduced. For sandwich-laminated plates and beams, the effect of fiber orientation of the orthotropic layer on the loss factor has been studied. The aspect ratio is very important in structural design for plates and beams. In this work, the effects of aspect ratios of sandwich laminates on optimal fundamental loss factors are investigated. The maximum fundamental loss factor and optimal fiber orientation have been obtained and analyzed for different sandwich laminates with the aspect ratio as a variable.
Ultrasonography of the feline kidney
Authors: Debruyn Katrien , Haers Hendrik , Combes Anais , Paepe Dominique , Peremans Kathelijne , Vanderperren Katrien , Saunders Jimmy H
Published: October 2012

Practical relevance:

Ultrasonography is an important tool for the detection of kidney disorders, which are among the most common health problems suffered by cats. It is more accurate than radiography for this purpose and is considered to be the reference modality for imaging the feline kidney, providing excellent visualisation of renal size, shape and internal architecture. Compared with more advanced imaging modalities, such as computed tomography or magnetic resonance imaging, ultrasonography is more accessible, less expensive, does not require general anaesthesia and allows real-time procedures to be performed.

Clinical challenges:

On ultrasound examination, focal or multifocal disorders may be readily identified, but diffuse changes are more challenging. B-mode ultrasonography is of limited use for differentiating between benign and malignant focal lesions. However, based on the presence and pattern of vascularity as an indicator of malignancy, contrast-enhanced ultrasonography allows distinction between benign and malignant focal renal lesions.

Audience:

This review provides a framework for the ultrasonographic approach to feline renal and perirenal disorders for the general practitioner.

Evidence base:

Drawing on current literature relating to ultrasonographic examination of feline kidneys, the aim is to summarise ultrasonographic technique, anatomy and changes associated with renal and perirenal diseases.
Study on the frictional properties of micro-magnet arrayed surface lubricated with ferrofluids
Authors: Huang Wei , Wang Jingqiu , Wang Xiaolei
Published: October 2012

Ferrofluids (FF) are stable colloids exhibiting normal liquid behavior coupled with magnetic properties. As a kind of lubricant, the most obvious advantage is that FF can be maintained in the desired position without any leakage by applying a permanent magnet. For the above characteristics, a kind of micro-magnet arrayed surface for FF lubrication was introduced in this article. The tribological performances of the surface were tested under plane contact conditions using FF as a lubricant. Flat SUS316 steel and polytetrafluoroethylene (PTFE) were used as opposite pairs, respectively, for their different wetting properties with FF. The experimental results show that compared with normal surface/PTFE frictional pair, the magnetic surface/PTFE couple expresses distinct friction increasing, while the magnetic surface/SUS316 steel pair presents obvious advantages of antifriction especially at high sliding speeds. The higher the surface magnetic flux is, the better is the tribological performance it displays especially at a higher sliding speed.