bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Level of Presentation to Listeners on Scaled Speech Intelligibility of Speakers with Dysarthria
Authors: Kim Yunjung , Kuo Christina
Published: September 2011

Objective: This study examined the effect of intensity level of presentation on scaling of speech intelligibility in speakers with and without dysarthria. Patients and Methods: A total of 50 utterances produced by speakers with dysarthria and healthy speakers were played to 60 listeners in four conditions, which consisted of two different presentation levels (‘high’ vs. ‘low’) and equalization of levels across utterances (‘adjusted’ vs. ‘unadjusted’). Speech intelligibility was scaled by using a direct magnitude estimation technique with and without modulus. Results: A significant decrease in speech intelligibility was indicated when the stimuli were adjusted to have fixed intensity on the most intense vocalic nuclei of each word, while no significant change was found between ‘high’ and ‘low’ presentation level conditions. Conclusion: The findings suggest that an increase in presentation level alone does not result in significant improvement in speech intelligibility ratings. The results are discussed by considering clinical implications in conducting speech therapy with emphasis on intensity variation.
Apoptosis in Skeletal Myocytes: A Potential Target for Interventions against Sarcopenia and Physical Frailty – A Mini-Review
Authors: Marzetti Emanuele , Calvani Riccardo , Bernabei Roberto , Leeuwenburgh Christiaan
Published: September 2011

Background: Sarcopenia, the age-related loss of muscle mass and function, represents a relevant public health issue due to its high prevalence and detrimental consequences. While the exact mechanisms underlying the pathogenesis of sarcopenia are not clear, growing experimental evidence indicates that progressive myonuclear elimination over the course of aging via an apoptosis-like process may represent a converging mechanism through which muscle atrophy and loss of physical function develop. Notably, the proapoptotic environment taking place in aged muscle appears amenable to interventions. Objective: We aimed at providing (1) an overview of signaling pathways of apoptosis relevant to sarcopenia, and (2) a review of the literature supporting myocyte apoptosis as a target for interventions against muscle aging. Methods: We summarized findings from studies focused on skeletal myocyte apoptosis as a mechanism in the development of sarcopenia and reports supporting myonuclear apoptosis as a target for interventions against age-related muscle loss. Results: Advanced age is associated with increased signaling through extrinsic and intrinsic apoptotic pathways in skeletal myocytes. In contrast, downregulation of myocyte apoptosis through calorie restriction, exercise training, hormonal supplementation, drugs (e.g. angiotensin-converting enzyme inhibitors, acetaminophen, antimyostatin antibodies), nutraceuticals or genetic interventions (e.g. PGC-1α overexpression) is linked with preservation of muscle integrity and improved physical performance in late life. Preliminary data also indicate that skeletal myocyte apoptotic signaling may be downregulated by compounds, such as resveratrol, with calorie restriction-mimicking properties. Whether exercise mimetics exert a similar effect has not yet been investigated. Conclusions: Available evidence suggests that targeting myonuclear apoptosis might provide novel and effective therapeutic tools to combat sarcopenia. Further research is required to definitely establish if downregulating myonuclear apoptosis is effective in maintaining muscle mass and function in late life, identify the most relevant apoptotic pathway(s) to target, and determine the optimal timing for intervening.
Evaluation of Traumatic Optic Neuropathy in Patients with Optic Canal Fracture Using Diffusion Tensor Magnetic Resonance Imaging: A Preliminary Report
Authors: Yang Qin-Tai , Fan Yun-Ping , Zou Yan , Kang Zhuang , Hu Bing , Liu Xian , Zhang Ge-Hua , Li Yuan
Published: September 2011

Objective: To investigate the role of diffusion tensor magnetic resonance imaging (DT-MRI) in the evaluation of traumatic optic neuropathy (TON). Methods: Six patients with TON underwent DT-MRI prior to decompression surgery. DTV 2 and Volume One 1.44 software were used to measure the fractional anisotropy (FA) and the mean apparent diffusion coefficient (ADC) of the optic nerves. White matter fiber bundle tracking was used to display optic nerves. Results: Visual acuity was improved in 1 of the 6 patients after surgery. The mean FA of the injured eye declined significantly with regard to that of the normal eye (0.2438 ± 0.0670 vs. 0.4524 ± 0.0531; t = 8. 711; p = 0. 000). The mean ADC on the injured side increased significantly compared with that on the normal side [(1.4172 ± 0.1208) × 10–3 mm2/s vs. (1.0866 ± 0.1179) × 10–3 mm2/s; t = –5.316; p = 0. 003). The continuity of the intracanalicular segment of the optic nerve was interrupted in 3 patients without improved postoperative visual acuity. In 1 patient with improved postoperative visual acuity, the fiber bundle of the optic nerve was somewhat less dense in the injured eye than in the normal eye. Conclusions: DT-MRI provides valuable information for evaluating the fibers of optic nerves in TON.
Beta-Arrestin2 as a Competitor for GRK2 Interaction with the GLP-1 Receptor upon Receptor Activation
Authors: Jorgensen Rasmus , Norklit Roed Sarah , Heding Anders , Elling Christian E.
Published: September 2011

The signaling of seven transmembrane receptors/G-protein- coupled receptors (GPCRs) is regulated by a number of receptor interacting proteins, including βarrestins (βarrs) and GPCR kinases (GRKs). In the present report, we have analyzed the interaction pattern between the glucagon-like peptide-1 (GLP-1) receptor (GLP-1R), βarr2, and GRK2 using bioluminescence resonance energy transfer assays. We found that βarr2 interacts with the GLP-1R in a biphasic manner with a phosphorylation-independent and a phosphorylation-dependent component. In competition experiments, we observed βarr2 competing with GRK2 for interaction with GLP-1R. We propose a model were βarr2 competes with GRK2 for interaction with the activated and GRK phosphorylated GLP-1R, suggesting a new role of βarr2 in regulating the orchestration of GRK2 functionality.
Approach to Neonatal Seizures
Authors: Sivaswamy Lalitha
Published: September 2011

Neonatal seizures can be difficult to recognize given the variation in their presentation. Hence, diagnosis and appropriate treatment may be delayed. Morphology of seizures in this age group is discussed, followed by common etiological entities. Special emphasis is laid on treatable disease states such as vitamin responsive seizure disorders and benign conditions that may not warrant aggressive treatment. Conditions that may have devastating neurological consequences are discussed in some detail so that the treating pediatrician can provide realistic information to the parents of such newborns. Imaging and laboratory workup is outlined, followed by guidelines for ordering and interpreting an electroencephalogram in this age group. Finally, treatment options in the form of antiepileptics are discussed with mention of new avenues for diagnosis and treatment that may become commonly employed in the future.
Shadowing Ministers
Authors: Carroll Royce , Cox Gary W.
Published: September 2011

In this article the authors study delegation problems within multiparty coalition governments. They argue that coalition parties can use the committee system to “shadow” the ministers of their partners; that is, they can appoint committee chairs from other governing parties, who will then be well placed to monitor and/or check the actions of the corresponding ministers. The authors analyze which ministers should be shadowed if governing parties seek to minimize the aggregate policy losses they suffer as the result of ministers pursuing their own parties’ interests rather than the coalition’s. Based on data from 19 mostly European parliamentary democracies, the authors find that the greater the policy disagreement between a minister’s party and its partners, the more likely the minister is to be shadowed.
Layers of Ethnicity
Authors: Goodnow Regina , Moser Robert G.
Published: September 2011

What impact, if any, do ethnic federalism and the geographic concentration of ethnic minorities have on the political incorporation of minorities in democracies with single-member district elections? Many studies on ethnic voting in the United States have examined the impact of majority-minority districts on the turnout of minority voters and the election of minority candidates. However, few studies have explored the effects of similar institutions in other countries. The authors address this issue by applying insights on ethnic voting from the American politics literature to Russia’s 1995 parliamentary election. They use multilevel regression models and census and electoral data that are disaggregated at the subdistrict ( raion) level to systematically assess whether ethnic federalism and majority-minority districts increase the vote share of minority candidates and encourage the turnout of minority voters. The findings suggest that district-level characteristics—specifically, majority-minority districts—are more important than ethnic federalism for promoting minority representation in Russia.
An Irrational Party of Rational Members
Authors: Maeda Ko
Published: September 2011

This study presents a new explanation to a puzzle regarding the reluctance of the Japan Socialist Party (JSP) to moderate its hard-liner Marxist platform. The author does so by focusing on the preferences and strategies of individual JSP members, in contrast to previous studies that treat the party as a unitary actor. The author shows that Japan’s electoral system created a unique environment in which the electoral prospects for some JSP incumbents would be seriously jeopardized if their party increased its popular support. The analysis demonstrates that the degree of security JSP politicians had in retaining their own seats was a significant determinant in their attitudes toward a proposed policy moderation plan that was considered during a critical period in the early 1960s that could have increased support for the party.
Continuity of care for people with non-psychotic disorders
Authors: Catty Jocelyn , Cowan Naomi , Poole Zoe , Clement Sarah , Ellis Gemma , Geyer Connie , Lissouba Pascale , Molodynski Andrew , White Sarah , Burns Tom
Published: September 2011

Background:

Service users with non-psychotic disorders are rarely studied. How continuity of care functions for this group is unknown.

Aims:

To compare users of community mental health teams with non-psychotic disorders to those with psychotic disorders in terms of demographic and illness characteristics, continuity of care and clinical and social functioning.

Methods:

Service users with non-psychotic disorders ( N = 98) were followed up for one year and compared to 180 service users with psychotic disorders. Continuity of care factors were tested for association with user, illness and service variables.

Results:

Service users with non-psychotic disorders experienced more care transitions, but there were no differences in team practices in relation to these two different groups.

Conclusion:

The underlying concepts of continuity of care derived from users with psychotic disorders appear to be meaningful for users with non-psychotic disorders. Their greater likelihood of experiencing disruptive and distressing care transitions needs to be addressed.
‘Bringing Government Closer to the People’? The Daily Experience of Sub-councils in Cape Town
Authors: Buire Chloé
Published: September 2011

This article considers the ways in which sub-councils ‘bring government closer to the people’ by creating an intermediary level between local wards and the metropolitan council in Cape Town. Daily encounters between administrative staff, elected representatives and local communities within an impoverished formerly ‘black’ area demonstrate the intricacy of interactions and relationships between governing strategies from above and the tactics of the governed from below. Beyond conflicting objectives and rationalities, I argue that citizenship may be defined as a constant negotiation of legitimacy between stakeholders, never definitely trapped ‘below’ or ‘above’ the actual challenges of the city.
Perceptions of Corruption in the South African Housing Allocation and Delivery Programme: What It May Mean for Accessing the State
Authors: Rubin Margot
Published: September 2011

Evidence from a recent study suggests that perceptions of corruption within the South African housing programme are widespread. This paper explores the pervasiveness of such perceptions and argues that they may reflect a range of factors, including the opacity, clumsiness and arbitrariness of the housing programme. Offering both positive and negative accounts, the paper considers the ways in which perceptions of corruption shape the manner in which residents access and respond to the state.
A Politics of Land Occupation: State Practice and Everyday Mobilization in Zille Raine Heights, Cape Town
Authors: Thorn Jessica , Oldfield Sophie
Published: September 2011

In this paper we reflect on a contested land occupation in Cape Town, the informal settlement of Zille Raine Heights in the city’s southern suburbs, to explore the settlement’s struggle to gain a legal right to land and the state’s attempts to remove it. In occupying land and defending their right to a decent place in the city, Zille Raine Heights and other settlements like it challenge the state in precise ways. This paper explores the provisional and unstable ways in which land occupiers and the state access and defend resources such as land, and in the process, engage in a politics of occupation together.
‘Up Close and Personal’ – How does Local Democracy Help the Poor Access the State? Stories of Accountability and Clientelism in Johannesburg
Authors: Bénit-Gbaffou Claire
Published: September 2011

The paper revisits participation and decentralization in relation to local clientelism, arguing that they share the personalization of links between residents and the state and the local possibility to adapt state policies. The line between decentralization-participation on the one hand, and clientelism on the other, is therefore easily blurred. The paper then argues that clientelism is not per se anti-democratic, some forms allow for local and immediate accountability of politicians. However, in most cases, it contributes to fragment or sedate local organizations or social movements and it prevents contestation of existing policies and dominant power structures. The paper thus challenges the idea that the promotion of decentralization and participatory institutions intrinsically leads to more democratic forms of government.
Preparation and properties of thermoplastic honeycomb core sandwich structure with aluminum skin
Authors: Nurashikin S. , Hazizan Akil
Published: September 2011

The low-velocity impact response of thermoplastic honeycomb core sandwich structure with aluminum skin has been investigated by conducting drop-weight impact tests using an instrumented drop-weight impact tower. At first, the shear modulus of the thermoplastic honeycomb core and flexural modulus of the skin were investigated through a series of flexural test. Later in the study, the indentation test was conducted to the specimen in order to investigate the indentation characteristic. It was found that the indentation characteristic of this sandwich structure can be analyzed using a Meyer indentation law. The impact response of the thermoplastic honeycomb core sandwich structures was predicted using a simple energy-balance model which meant for energy absorption in bending, shear and contact effects. In addition, the energy-balance model was also used to identify the energy partitioning during the impact event. The result shows that the energy absorption profile was relatively constant over the range of impact energies, suggesting that the fraction of energies does not vary with impact conditions.
Modification of pineapple leaf fibers and graft copolymerization of acrylonitrile onto modified fibers
Authors: Maniruzzaman M. , Rahman M.A. , Gafur M.A. , Fabritius H. , Raabe D.
Published: September 2011

Raw pineapple leaf fibers (PALFs) were chemically modified by scouring, NaOH treatment, and bleaching (NaClO2). The graft copolymerization of synthetic acrylonitrile monomer onto bleached PALFs was carried out in aqueous medium using potassium persulfate (K2S2O8/FeSO4) as a redox initiator. The maximum grafting level at optimum conditions, namely, monomer concentration, initiator concentration, catalyst concentration, reaction time, and temperature have been determined. The main objective of this study is to decrease the amorphous region of lignocellulose in PALFs and improve its hydrophobic nature by incorporation of synthetic polymer of polyacrylonitrile and mechanical properties. The modified and grafted fibers were characterized by Fourier transform infrared spectroscopy, scanning electron microscope, thermogravimetric analysis, and X-ray diffraction study techniques. The moisture content and tensile strength properties were also evaluated for their environmental and mechanical performances.
Effect of water absorption on pultruded jute/glass fiber-reinforced unsaturated polyester hybrid composites
Authors: Zamri Mohd Hafiz , Akil Hazizan Md , Bakar Azhar Abu , Ishak Zainal Arifin Mohd , Cheng Leong Wei
Published: September 2011

The use of natural fibers in polymer composites has given renewed interest to the development of green composites today. However, the moisture absorption of natural fibers gives serious concern, especially for their potential outdoor applications. This article reports the study results on the water absorption of pultruded jute/glass fiber-reinforced unsaturated polyester hybrid composites, which was subjected to various water conditions and their effects on its mechanical properties. Water absorption tests were performed by immersing composite specimens into three different water conditions, namely: distilled water, sea water, and acidic water, which were at room temperature, for a period of 3 weeks. The characteristic parameter of diffusion coefficient ( D) and maximum moisture content ( Mm) were determined from the obtained water absorption curves. The water absorption behavior of the glass/jute fiber-reinforced unsaturated polyester hybrid composite was found to follow a non-Fickian behavior. The effects of the various aqueous environments on the flexural and compression characteristics were investigated in this study. The flexural and compression properties were found to decrease with an increasing percentage of water uptakes.
Thermal stability and electrical behavior of polydimethylsiloxane nanocomposites with carbon nanotubes and carbon black fillers
Authors: Norkhairunnisa M , Azizan A , Mariatti M , Ismail H , Sim LC
Published: September 2011

In this work, the performance of polydimethylsiloxane (PDMS) nanocomposites with carbon black (CB) and multi-walled carbon nanotube (MWCNT) fillers was studied. The carbon nanofillers were first introduced in the solvent to promote an adequate dispersion. The silicone rubber was then reinforced with the carbon nanofillers by a mechanical mixing process followed by film casting. It was found that only small amount of MWCNTs is required to reach the percolation threshold that produces high electrical conductivity. Filler size and segregation, as observed by scanning electron microscopy, play important roles in determining the electrical properties of silicone elastomer filled composites. Transmission electron microscopy was also performed to examine the tube–tube interaction of MWCNT in silicone rubber. The MWCNT/PDMS nanocomposites have higher electrical conductivity value compared to the CB/PDMS nanocomposite. The percolation threshold for MWCNT/PDMS nanocomposites was approximately 1.0 vol% of MWCNT loading with a value of –4.06 log σ (S/cm). On the contrary, no obvious percolation threshold of CB/PDMS nanocomposites was observed, as the CB fillers added from 0.5 to 2.0 vol% in the PDMS. The MWCNT/PDMS nanocomposite also showed better thermal stability than the CB/PDMS nanocomposite. The onset temperature for 0.5 vol% of MWCNT/PDMS and CB/PDMS nanocomposites were 528°C and 492°C, respectively.
Mechanical properties of electron beam treated carboxylated nitrile butadiene rubber (XNBR) composites reinforced by organic/inorganic hybrid filler
Authors: Mousa A , Heinrich G , Gohs U , Wagenknecht U
Published: September 2011

Two types of carboxylated nitrile butadiene rubber (XNBR) composites were prepared; one of which was XNBR reinforced with organic filler-based olive solid by-product (OSB) and the other was XNBR reinforced with a combination of OSB and organo-layered nanoclay. To enhance the interaction between both the fillers and the matrix, the samples were exposed to electron beam (EB) treatment under ambient conditions. The samples were inspected with reference to their mechanical and dynamic mechanical (DMA) properties. It has been found that the tensile strength at break was enhanced after EB treatment for both composites. Such scenario was attributed to the irradiation-induced vulcanization. To support the observed trend, the pulse nuclear magnetic resonance technique was implemented. It has been found that the relaxation time ( T2) was shortened after EB treatment. As further evidence on the fact that EB treatment was effective, the attenuated total reflectance infrared spectra were utilized as well. The IR results showed an increment in the spectra intensities after EB treatments. Scanning electron microscope revealed that EB treatment has turned their surface rough with an improved interaction between the matrix and the filler. DMA results were in harmony with the tensile properties in the sense that increased elastic modulus ( E′) with filler incorporation. The intensity of the mechanical loss factor (tan δ) was a sign on the reinforcing capability of the fillers as well as improved interaction between the composite components.
Thermal conductivity and microstructure of Al/diamond composites with Ti-coated diamond particles consolidated by spark plasma sintering
Authors: Liang Xuebing , Jia Chengchang , Chu Ke , Chen Hui , Nie Junhui , Gao Wenjia
Published: September 2011

Metal/diamond composites have been considered as the new generation of thermal management material. The critical challenge to obtain composites with high thermal conductivity (TC) is to improve the interfacial bonding between the matrix and diamond. In the present study, a titanium coating was plated on the surface of diamond particles via vacuum evaporation–deposition, and Al/diamond composites were consolidated by spark plasma sintering (SPS) technique. The TC and microstructure of composites, respectively, with coated and uncoated diamond particles are compared and discussed. The results show that the Ti coating can significantly increase the wetting property between Al and diamond, leading to a strong interfacial bonding. The diffusion of Ti into the matrix and the formation of TiC are detected at the Al–diamond interface. The properties of composites, respectively, with coated and uncoated diamond exhibit different trends with increasing sintering temperature or diamond volume fraction. Compared with composites with uncoated particles, the Al/Ti–diamond composites obtained the much higher relative density and TC as high as 491 W/mK. Based on the comparison between the experimental and theoretical values, it is found that the thermal conductivities of Al/Ti–diamond composites have reached or surpassed the theoretical calculations with the particle volume fraction not more than 50%.
Fatigue failure analysis of surface-cracked (±45°)3 filament-wound GRP pipes under internal pressure
Authors: Samanci A , Tarakçioğlu N , Akdemir A
Published: September 2011

In this study, the fatigue behavior of (±45°)3 filament-wound composite pipes with a surface crack under alternating internal pressure was investigated. Glass-reinforced plastic (GRP) pipes were made of E-glass/epoxy and tested in the open-ended condition. The pipes had a surface crack with a notch–aspect ratio of a/c = 0.2 and notch-to-thickness ratios of a/t = 0.25, 0.38, or 0.50 in the axial direction. Tests were carried out in accordance with ASTM D2992. This standard offers 25 cycles/min and a load ratio of R = 0.05. Tests were performed at three different load levels: 50%, 40%, and 30% of ultimate hoop stress. Whitening, leakage, and final failure of GRP pipes were observed, and fatigue test results were presented by means of S–N curves.
High strain-rate behavior of natural fiber-reinforced polymer composites
Authors: Kim Wonsuk , Argento Alan , Lee Ellen , Flanigan Cynthia , Houston Daniel , Harris Angela , Mielewski Deborah F
Published: September 2011

The high strain-rate constitutive behavior of polymer composites with various natural fibers is studied. Hemp, hemp/glass hybrid, cellulose, and wheat straw-reinforced polymeric composites have been manufactured, and a split-Hopkinson pressure bar apparatus has been designed to measure the dynamic stress–strain response of the materials. Using the apparatus, compressive stress–strain curves have been obtained that reveal the materials’ constitutive characteristics at strain rates between 600 and 2400 strain/s. Primary findings indicate that natural fibers in thermoset composites dissipate energy at lower levels of stress and higher strain than glass-reinforced composites. In the case of thermoplastic matrices, the effect on energy dissipation of natural fibers vs. conventional talc reinforcements is highly dependent on resin properties. Natural fibers in polypropylene homopolymer show improved reinforcement but have degraded energy dissipation compared to talc. Whereas in polypropylene copolymer, natural fibers result in improved energy dissipation compared to talc. These data are useful for proper design, analysis, and simulation of lightweight biocomposites.
Mechanical and dry sliding wear behavior of Al7075 alloy-reinforced with SiC particles
Authors: Kumar GB Veeresh , Rao CSP , Selvaraj N
Published: September 2011

In this article, the experimental results of the mechanical and tribological properties of Al7075–SiC composites are presented. The composites of Al7075 containing 2–6 wt% SiC were fabricated by liquid metallurgy route. The experimental results showed that the density of the composites increase with increased SiC contents and are in line with the values obtained by the rule of mixtures. The hardness and tensile strength of the Al7075–SiC composites are found to be increased by increased volume percentage of ceramic phase at the cost of reduced ductility. The wear properties of the composites containing SiC exhibited the superior wear-resistance properties.
Effects of vacuum pressure, inlet pressure, and mold temperature on the void content, volume fraction of polyester/e-glass fiber composites manufactured with VARTM process
Authors: Kedari Vishwanath R. , Farah Basil I. , Hsiao Kuang-Ting
Published: September 2011

Vacuum-assisted resin transfer molding (VARTM) process is one of the liquid composite molding (LCM) processes aimed at producing high-quality composite parts. The void content and fiber volume fraction of a VARTM part can be affected by many parameters and is critical to the mechanical properties and the quality of the part. In this paper, a series of experiments were conducted with a heated dual pressure control VARTM setup for investigating the effects of vacuum pressure, inlet pressure, and mold temperature on the void content and fiber volume fraction of polyester/E-glass fiber composite. It was found that stronger vacuum and higher mold temperature can better control and increase the fiber volume fraction; however, such a combination of strong vacuum and high mold temperature may also require a reduced inlet pressure for minimizing the void content. The need of pressure reduction can be explained with the compatibility between Darcy's flow and capillary flow in the fiber preform and can be calculated based on the room temperature VARTM results. The experimental results suggest that high mold temperature, high vacuum, and appropriately reduced inlet pressure can produce a VARTM part with high fiber volume fraction and low void content.
Determining the through-thickness properties of thick glass fiber reinforced polymers at high strain rates
Authors: Govender Reuben A , Louca Luke A , Pullen Andrew , Fallah Arash S , Nurick Gerald N
Published: September 2011

The use of thick fiber reinforced polymer (FRP) laminates in composite armor and naval structures requires thorough characterization of the through-thickness properties of said laminates, both quasi-statically and at high strain rates. Specimens cut from an E-Glass/vinyl ester FRP were tested in compression both quasi-statically and dynamically using a split Hopkinson pressure bar (SHPB). The SHPB tests utilized a conical striker for pulse shaping, to reduce the variation in strain rate during the test. The quasi-static through-thickness compressive strength was 417 MPa, while the SHPB tests produced a strength of 462 MPa at an average strain rate of 5.1 × 102 s−1. A single HPB configured for spalling tests was used to determine the dynamic through-thickness tensile strength (interlaminar tension). The interlaminar tensile strength was 125 MPa at an average strain rate of 1.8 × 103 s−1.
Experimental and numerical investigation of the VARTM process with a sandwich structure
Authors: Jhan Yu-Ti , Lee Ya-Jung , Chung Cheng-Hsien
Published: September 2011

A sandwich assembly with core material enhances the bending stiffness of a structure and achieves lightweight requirements. Resin flowing behavior inside a sandwich assembly consisting of fiber layers and a segmented core is more complex than that for a fibrous assembly consisting of only fiber layers. This study presents infusion experiments on sandwich assemblies in the VARTM process, and compares the results to simulations from a 3D sandwich model including circular pipe elements to substitute for core grooves. Using the concepts of equivalent thickness to define the porosity of a sandwich assembly and porous space helps derive permeability trends and predictive equations to simplify permeability calculation. The deck infusing experiment in this study not only proves the permeability rationality of a sandwich assembly, but also provides concepts and suggestions for infusion arrangements. Consequently, the permeant characteristics in the sandwich assembly are applicable to manufacturing sandwich structures with good saturation.
Effect of nanoclay addition on the fiber/matrix adhesion in epoxy/glass composites
Authors: Dorigato Andrea , Morandi Stefano , Pegoretti Alessandro
Published: September 2011

Various kinds of organo-modified clays were dispersed at different amounts in an epoxy matrix. After clay addition, the viscosity of the epoxy resin resulted still acceptable for a possible usage as matrices for fiber-reinforced composites. The formation of intercalated microstructures led to substantial improvements of the thermal (glass transition temperature) and mechanical (fracture toughness) properties of the epoxy matrix. E-glass fiber/matrix interfacial shear strength was evaluated by the single-fiber microdebonding method. The introduction of organo-modified clays led to the formation of a stronger fiber-matrix interface, with an increase of the interfacial shear strength of about 30%. Concurrently, the evaluation of the fiber/matrix contact angle revealed an improved wettability when organo-modified clays were added.
Thermal properties and phase transitions of Cu-coated ZrW2O8 composite powders
Authors: Wu Yi , Liu Qing , Wang Haowei
Published: September 2011

ZrW2O8/Cu composite powders were prepared by the electroless plating method. The phase transformation and the thermal expansion properties of the composite powders with different coating thicknesses were investigated. Differential scanning calorimetry and high-temperature X-ray diffraction analyses revealed that the copper coating had considerable influence on the phase transition of ZrW2O8, which further affected the thermal expansion properties of the composite powders. With proper coating thickness, composite powders exhibiting minimum coefficient of thermal expansion values can be obtained based on the results of this study.
Recyclability and reutilization of carbon fiber fabric/epoxy composites
Authors: Feraboli Paolo , Kawakami Hirohide , Wade Bonnie , Gasco Federico , DeOto Luciano , Masini Attilio
Published: September 2011

Solid carbon fiber/epoxy laminates manufactured by liquid resin infusion of twill fabric reinforcement are recycled in a bath of boiling sulfuric acid to separate the fibers from the matrix. The recycled reinforcement consists of long fibers arranged in a random, entangled mat. Using the same epoxy matrix and infusion materials and process, the recycled fibers are reutilized to manufacture solid laminates. The physical properties of the recycled laminates are evaluated by means of pulse-echo ultrasound, visual microscopy, and fiber volume content. The average fiber volume content of the recycled laminates is 33%, compared to the 62% of the twill laminates. The mechanical properties of the recycled composite include tension modulus and strength, compression modulus and strength, three-point bend flexure strength, and short beam shear strength. The properties are compared against the values of the twill reinforcement with quasi-isotropic stacking sequence. Results show that the recycled material offers promising elastic properties and strength values, similar to those of advanced carbon fiber sheet molding compounds, and therefore can be used as structural material.
Synthesis, characterization, and properties of silane-functionalized expandable graphite composites
Authors: Wu Tsung-Chih , Tsai Kuang-Chung , Lu Mu-Chen , Kuan Hsu-Chiang , Chen Chia-Hsun , Kuan Chen-Feng , Chiu Shao-Lung , Hsu Shu-Wei , Chiang Chin-Lung
Published: September 2011

In this study, synthesis and properties of green flame retardant of silane-functionalized expandable graphite (EG) composites were investigated. The coupling agent was used to improve the interface between the matrix and EG. Fourier transform infrared spectrophotometry and X-ray photoelectron spectroscopy were adopted to characterize the functionalized EG. It was affirmed that 3-aminopropyltriethoxsilane (APTS) has been grafted on EG. The modified EG composites improved thermal property, corresponding to functionalized EG. 29Si-nuclear magnetic resonance and scanning electron microscopies were used to study the structure and the morphology property of the modified EG composites. It showed that flake graphite existed in the matrix. Energy dispersive X-ray analysis indicated that Si atoms appeared due to APTS grafted on EG. The expanded structures of graphite were formed after burning. The foamed layer demonstrated the mechanism of protection of EG. The results present poly(methylmethacrylate)/silane-modified EG(PMMA, poly(methylmethacrylate) composites that have excellent thermal stability and flame-retardant property compared to pure PMMA resin.
Osteogenic Potential of Autogenous Bone Grafts Harvested with Four Different Surgical Techniques
Authors: Miron R.J. , Hedbom E. , Saulacic N. , Zhang Y. , Sculean A. , Bosshardt D.D. , Buser D.
Published: September 2011

The osteogenic potential of autogenous bone grafts is superior to that of allografts and xenografts because of their ability to release osteoinductive growth factors and provide a natural osteoconductive surface for cell attachment and growth. In this in vitro study, autogenous bone particles were harvested by four commonly used techniques and compared for their ability to promote an osteogenic response. Primary osteoblasts were isolated and seeded on autogenous bone grafts prepared from the mandibles of miniature pigs with a bone mill, piezo-surgery, bone scraper, and bone drill (bone slurry). The osteoblast cultures were compared for their ability to promote cell attachment, proliferation, and differentiation. After 4 and 8 hrs, significantly higher cell numbers were associated with bone mill and bone scraper samples compared with those acquired by bone slurry and piezo-surgery. Similar patterns were consistently observed up to 5 days. Furthermore, osteoblasts seeded on bone mill and scraper samples expressed significantly elevated mRNA levels of collagen, osteocalcin, and osterix at 3 and 14 days and produced more mineralized tissue as assessed by alizarin red staining. These results suggest that the larger bone graft particles produced by bone mill and bone scraper techniques have a higher osteogenic potential than bone slurry and piezo-surgery.
Genome-wide Association Scan for Childhood Caries Implicates Novel Genes
Authors: Shaffer J.R. , Wang X. , Feingold E. , Lee M. , Begum F. , Weeks D.E. , Cuenco K.T. , Barmada M.M. , Wendell S.K. , Crosslin D.R. , Laurie C.C. , Doheny K.F. , Pugh E.W. , Zhang Q. , Feenstra B. , Geller F. , Boyd H.A. , Zhang H. , Melbye M. , Murray J.C. , Weyant R.J. , Crout R. , McNeil D.W. , Levy S.M. , Slayton R.L. , Willing M.C. , Broffitt B. , Vieira A.R. , Marazita M.L.
Published: September 2011

Dental caries is the most common chronic disease in children and a major public health concern due to its increasing incidence, serious health and social co-morbidities, and socio-demographic disparities in disease burden. We performed the first genome-wide association scan for dental caries to identify associated genetic loci and nominate candidate genes affecting tooth decay in 1305 US children ages 3-12 yrs. Affection status was defined as 1 or more primary teeth with evidence of decay based on intra-oral examination. No associations met strict criteria for genome-wide significance (p < 10E-7); however, several loci ( ACTN2, MTR, and EDARADD, MPPED2, and LPO) with plausible biological roles in dental caries exhibited suggestive evidence for association. Analyses stratified by home fluoride level yielded additional suggestive loci, including TFIP11 in the low-fluoride group, and EPHA7 and ZMPSTE24 in the sufficient-fluoride group. Suggestive loci were tested but not significantly replicated in an independent sample (N = 1695, ages 2-7 yrs) after adjustment for multiple comparisons. This study reinforces the complexity of dental caries, suggesting that numerous loci, mostly having small effects, are involved in cariogenesis. Verification/replication of suggestive loci may highlight biological mechanisms and/or pathways leading to a fuller understanding of the genetic risks for dental caries.
Stability and change in the Freedom House political rights and civil liberties measures
Authors: Armstrong David A
Published: September 2011

Scholars have long attempted to make distinctions among states based on regime type. Two of the most commonly used measures by both scholars and policymakers are the Freedom House Freedom in the World political rights and civil liberties measures. Despite their popularity, little is known about the measurement properties of these variables. In 2006, Freedom House began releasing the subcategory indicators used to generate the seven-point political rights and civil liberties scales as well as the freedom status indicator. I investigate the measurement properties of these scales using Bayesian measurement models (factor analysis and latent class analysis) that explicitly incorporate the goals of the Freedom House organization (which I argue are rigor, appropriate precision, and temporal stability). I find that (a) there is considerable variation hiding in the seven-point political rights and civil liberties classifications (e.g. many countries that are coded one by Freedom House are interestingly different from each other), (b) some countries coded in different categories by Freedom House are not interestingly different from each other (e.g. some twos are not different from some threes), and (c) the subindicators are all reliable indicators of political rights and civil liberties. I show that these differences can be substantively and statistically consequential when using the Freedom House data if the researcher’s goals include comparison across space, comparison over time or predictive statistical modeling.
Who wants to be a major power? Explaining the expansion of foreign policy ambition
Authors: Fordham Benjamin O
Published: September 2011

Some states define their interests more broadly than others, looking beyond their immediate security and mobilizing their national wealth in pursuit of more ambitious goals. The most successful of these states come to be seen by others as major powers. Though major powers and states aspiring to attain this status are very important in world politics, relatively little explicit attention has been paid to the question of why some states expand their foreign policy ambitions, adopting what can be termed a major-power foreign policy. This article evaluates three explanations for this policy choice. Some international relations theory claims that potential power is itself a sufficient motivation for the adoption of major-power foreign policy. Other theorists suggest that some triggering condition is required, such as increasing international threat or expanding international economic interests. Evidence concerning the construction of military capabilities and diplomatic activism indicates that potential power alone does not offer a sufficient explanation for the adoption of major-power foreign policy. Both international threats and economic interests act as triggers for this choice, though they appear to push states toward different types of mobilization.
Understanding the co-existence of conflict and cooperation: Transboundary ecosystem management in the Virunga Massif
Authors: Martin Adrian , Rutagarama Eugene , Cascão Ana , Gray Maryke , Chhotray Vasudha
Published: September 2011

This article contributes to our understanding of transboundary environmental management regimes through the application of an analytical framework that facilitates an exploration of the co-existence of conflict and cooperation. Rather than framing conflict and cooperation as mutually exclusive states at opposite ends of a spectrum, we seek to understand the ways in which cooperation can exist at the same time as conflict. We apply this framework to a study of conservation management in a transboundary area at the intersection of the Democratic Republic of Congo, Rwanda and Uganda. We identify two actual and one hypothetical phase of conflict–cooperation relations, in a landscape notorious for some of the worst violence of the last two decades. We map the evolution of phases of transboundary protected area management against the evolving security context, and we find that this approach has greater explanatory power than previous approaches that polarize conflict and cooperation. In particular, it helps us to understand the drivers of environmental cooperation, including the evolving characteristics of that cooperation. This new way of understanding the relationship between environmental management and security also enables us to reconsider the potential for environmental management to be instrumental in working towards interstate security objectives, for example through peace parks. We don’t find that the ‘low politics’ of environmental management should be seen as a predictable and manageable determinant of international relations. But an understanding of the coexistence of conflict and cooperation does also point to a more complex, non-linear relationship between low and high politics.
Quantifying intelligence cooperation: The United States International Intelligence Behavior (USIIB) dataset
Authors: Aydinli Ersel , Tuzuner Musa
Published: September 2011

This report describes the creation of the United States International Intelligence Behavior dataset (USIIB). The USIIB represents the first collection of event data specifically intended for exploring in a quantifiable manner the international intelligence cooperation behaviors of the United States. A total of 293,615 events are recorded in the USIIB, covering the years 2000–09. The report first provides a detailed description of the steps involved in building such a dataset, including the development of search terms, the use of a machine coding program (TABARI – Text Analysis by Augmenting Replacement Instructions) to extract data from wire news releases, and the extension of an existing coding scheme (CAMEO) to include intelligence behaviors. Following a discussion of issues related to the reliability and validity of event datasets in general and the USIIB in particular, the report then includes suggestions and examples for how the data in the current USIIB dataset may be used in order to add to our understandings of patterns and anomalies in international intelligence cooperation behavior. As a specific example, it offers results from an empirical test exploring variation in intelligence cooperation behaviors among democracies and non-democracies, asking specifically whether the United States has been more likely in the early 21st century to cooperate on intelligence matters with democratic states, and finding this not to have been the case. Finally, it aims to provide a guide for others who would like to extend this dataset to explore intelligence cooperation activity of other countries or regions.
Economic load dispatch using population-variance harmony search algorithm
Authors: Panigrahi BK , Pandi V Ravikumar , Das Swagatam , Cui Zhihua , Sharma Renu
Published: September 2011

This paper presents a novel stochastic optimization approach to solve the constrained economic load dispatch (ELD) problem using the harmonic search algorithm (HS). HS is a recently developed derivative-free, meta-heuristic optimization algorithm, which draws inspiration from the musical process of searching for a perfect state of harmony. This work analyses the evolution of the population-variance over successive generations in HS and thereby draws some important conclusions regarding the explorative power of HS. The proposed methodology easily takes care of solving non-convex ELD problems along with different constraints like transmission losses, ramp rate limits of the generators and prohibited operating zones. Simulations were performed over various standard test systems with different number of generating units and a comparative study is carried out with other existing relevant approaches. The findings affirmed the robustness and proficiency of the proposed methodology over other existing techniques.
A co-ordinated dispatch model for electricity and heat in a Microgrid via particle swarm optimization
Authors: Xu Li Zhong , Yang Guang Ya , Xu Zhao , Bao Zhe Jing , Jiang Quan Yuan , Cao Yi Jia , Østergaard Jacob
Published: September 2011

This paper develops a co-ordinated electricity and heat dispatching model for a Microgrid under a day-ahead environment. In addition to operational constraints, network loss and physical limits are addressed in this model, which were always ignored in previous work. As an important component of the Microgrid, a detailed combined heat and power (CHP) model is developed. The part load performance of CHP is modelled by a curve fitting method. Furthermore, an electric heater is introduced into the model to improve the economy of the Microgrid operation and enhance the flexibility of the Microgrid by electricity–heat conversion. Particle swarm optimization is employed to solve this model for the operation schedule to minimize the total operational cost of the Microgrid by co-ordinating the CHP, electric heater, boiler and heat storage. The efficacy of the model and methodology is verified with different operation scenarios.