bluuebunny/crossref_metadata_2025 huggingface dataset:
Ring bands in fish skeletal muscle: Reorienting the myofibrils and microtubule cytoskeleton within a single cell
Authors: Priester Carolina , Braude Jeremy P. , Morton Lindsay C. , Kinsey Stephen T. , Watanabe Wade O. , Dillaman Richard M.
Published: July 2012

Skeletal muscle cells (fibers) contract by shortening their parallel subunits, the myofibrils. Here we show a novel pattern of myofibril orientation in white muscle fibers of large black sea bass, Centropristis striata. Up to 48% of the white fibers in fish >1168 g had peripheral myofibrils undergoing an ∼90o shift in orientation. The resultant ring band wrapped the middle of the muscle fibers and was easily detected with polarized light microscopy. Transmission electron microscopy showed that the reoriented myofibrils shared the cytoplasm with the central longitudinal myofibrils. A microtubule network seen throughout the fibers surrounded nuclei but was mostly parallel to the long‐axis of the myofibrils. In the ring band portion of the fibers the microtubule cytoskeleton also shifted orientation. Sarcolemmal staining with anti‐synapsin was the same in fibers with or without ring bands, suggesting that fibers with ring bands have normal innervation and contractile function. The ring bands appear to be related to body‐mass or age, not fiber size, and also vary along the body, being more frequent at the midpoint of the anteroposterior axis. Similar structures have been reported in different taxa and appear to be associated with hypercontraction of fibers not attached to a rigid structure (bone) or with fibers with unusually weak links between the sarcolemma and cytoskeleton, as in muscular dystrophy. Fish muscle fibers are attached to myosepta, which are flexible and may allow for fibers to hypercontract and thus form ring bands. The consequences of such a ring band pattern might be to restrict the further expansion of the sarcolemma and protect it from further mechanical stress. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.
Spatial organization of tettigoniid auditory receptors: Insights from neuronal tracing
Authors: Strauß Johannes , Lehmann Gerlind U. C. , Lehmann Arne W. , Lakes‐Harlan Reinhard
Published: July 2012

The auditory sense organ of Tettigoniidae (Insecta, Orthoptera) is located in the foreleg tibia and consists of scolopidial sensilla which form a row termed crista acustica. The crista acustica is associated with the tympana and the auditory trachea. This ear is a highly ordered, tonotopic sensory system. As the neuroanatomy of the crista acustica has been documented for several species, the most distal somata and dendrites of receptor neurons have occasionally been described as forming an alternating or double row. We investigate the spatial arrangement of receptor cell bodies and dendrites by retrograde tracing with cobalt chloride solution. In six tettigoniid species studied, distal receptor neurons are consistently arranged in double‐rows of somata rather than a linear sequence. This arrangement of neurons is shown to affect 30–50% of the overall auditory receptors. No strict correlation of somata positions between the anterio‐posterior and dorso‐ventral axis was evident within the distal crista acustica. Dendrites of distal receptors occasionally also occur in a double row or are even massed without clear order. Thus, a substantial part of auditory receptors can deviate from a strictly straight organization into a more complex morphology. The linear organization of dendrites is not a morphological criterion that allows hearing organs to be distinguished from nonhearing sense organs serially homologous to ears in all species. Both the crowded arrangement of receptor somata and dendrites may result from functional constraints relating to frequency discrimination, or from developmental constraints of auditory morphogenesis in postembryonic development. J. Morphol. © 2012 Wiley Periodicals, Inc.
Exogenous phytoestrogenic molecule icaritin incorporated into a porous scaffold for enhancing bone defect repair
Authors: Wang Xin‐Luan , Xie Xin‐Hui , Zhang Ge , Chen Shi‐Hui , Yao Dong , He Kai , Wang Xiao‐Hong , Yao Xin‐Sheng , Leng Yang , Fung Kwok‐Pui , Leung Kwok‐Sui , Qin Ling
Published: July 2012

This study was designed to develop a bioactive scaffold to enhance bone defect repair in steroid‐associated osteonecrosis (SAON). Icaritin, a metabolite of the herb Epimedium, has been identified as an angiogenic and osteogenic phytomolecule. Icaritin was homogenized into poly lactic‐co‐glycolic acid/tricalcium phosphate (PLGA/TCP) to form an icaritin‐releasing porous composite scaffold (PLGA/TCP/icaritin) by fine‐spinning technology. In vitro, high performance liquid chromatography was used to determine the release of icaritin during degradation of PLGA/TCP/icaritin. The osteogenic effects of PLGA/TCP/icaritin were evaluated using rat bone marrow mesenchymal stem cells (BMSCs). In vivo, the osteogenic effect of PLGA/TCP/icaritin was determined within a bone tunnel after core decompression in SAON rabbits and angiography within scaffolds was examined in rabbit muscle pouch model. In vitro study confirmed the sustainable release of icaritin from PLGA/TCP/icaritin with the bioactive scaffold promoting the proliferation and osteoblastic differentiation of rat BMSCs. In vivo study showed that PLGA/TCP/icaritin significantly promoted new bone formation within the bone defect after core decompression in SAON rabbits and enhanced neovascularization in the rabbit muscle pouch experiment. In conclusion, PLGA/TCP/icaritin is an innovative local delivery system that demonstrates sustainable release of osteogenic phytomolecule icaritin enhancing bone repair in an SAON rabbit model. The supplement of scaffold materials with bioactive phytomolecule(s) might improve treatment efficiency in challenging orthopedic conditions. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:164–172, 2012
Trajectories of PTSD symptoms following sexual assault: Is resilience the modal outcome?
Authors: Steenkamp Maria M. , Dickstein Benjamin D. , Salters‐Pedneault Kristalyn , Hofmann Stefan G. , Litz Brett T.
Published: July 2012

Theoretical frameworks positing qualitatively distinct trajectories of posttrauma outcome have received initial empirical support, but have not been investigated in cases of severe interpersonal trauma. To address this limitation, we conducted latent class growth analysis with longitudinal data collected from 119 female sexual assault survivors at 1‐, 2‐, 3‐, and 4‐months postassault. Participants' mean age was 33 years; 63% were White. We hypothesized that given the severity of exposure associated with sexual assault, resilience would not be the modal course of adaptation. Four distinct PTSD growth trajectories, representing unique latent classes of participants, best fit the data: a high chronic trajectory, a moderate chronic trajectory, a moderate recovery trajectory, and a marked recovery trajectory. Contrary to previous studies and recent theoretical models, resilience and resistance trajectories were not observed, as high levels of distress were evident in nearly all participants at 1‐month postassault. These results suggest that theoretical models of posttrauma response positing resilience as the modal outcome may not generalize to cases of sexual assault.
Stabilization of Peptide‐Based Vesicles via in situ Oxygen‐Mediated Cross‐Linking
Authors: Sulistio Adrian , Blencowe Anton , Wang Jiapei , Bryant Gary , Zhang Xiaoqing , Qiao Greg G.
Published: July 2012

Reversible vesicles from poly(L‐glutamic acid)65‐block‐poly[(L‐lysine)‐ran‐(L‐3,4‐dihydroxyphenylalanine)]75 [PLGA65‐b‐P(LL‐r‐DOPA)75] block copolypeptide adopt different configurations depending on the surrounding pH. At pH = 3, AFM and TEM images show ellipsoidal morphologies, whereas at pH = 12 both TEM and AFM reveal the formation of hollow vesicles. At pH = 12, the P(LL‐r‐DOPA) block forms the internal layer of the vesicle shell and the subsequent oxygen‐mediated oxidation of the phenolic groups of the DOPA lead to the formation of quinonic intermediates, which undergo intermolecular dimerization to stabilize the vesicles via in situ cross‐linking. Consequently, the vesicles maintain their shape even when the pH is reversed back to 3, as confirmed by AFM and TEM.

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Flexible Superhydrophobic Polymeric Surfaces with Micro‐/Nanohybrid Structures Using Black Silicon
Authors: Lee Sang Eon , Lee Dongjin , Lee Phillip , Ko Seung Hwan , Lee Seung S. , Hong Seong Uk
Published: July 2012

A novel way to fabricate flexible superhydrophobic PDMS surfaces using a microfabricated SU‐8 template on black silicon is demonstrated. The SU‐8 mold is fabricated on top of black silicon that has nanoscale features. The static water contact angle is generally 7° larger on PDMS surfaces created on black silicon than on bare silicon, presumably due to the presence of nanoscale bumps. The highest static contact angle of 157° and the lowest contact angle hysteresis of 3° are obtained on molded PDMS surfaces with the cylindrical posts possessing a diameter of 40 µm, spacing distance of 10 µm, and height of greater than 15 µm. The fabrication of superhydrophobic PDMS surfaces by means of black silicon is highly reproducible and may be suitable for many applications.

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Mechanical Performance of Injection‐Molded Poly(propylene): Characterization and Modeling
Authors: van Erp Tim B. , Govaert Leon E. , Peters Gerrit W. M.
Published: July 2012

It is shown that predictions of local mechanical properties in a product can be made from the orientation only using an anisotropic viscoplastic model. Due to processing‐induced crystalline orientations, the mechanical properties of injection‐molded polymer products are anisotropic and exhibit strong variations within a product. The tensile response and the mechanical lifetime under static loading depend strongly on the direction of loading and the location. The deformation kinetics are described with an anisotropic viscoplastic model, and quantitative predictions are made based on coupling of the orientation factor in direction of loading and model parameters. A limited characterization of the morphology within a product is sufficient to determine its local mechanical performance.

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Graft Copolymerization of Styrene and Acrylonitrile in the Presence of Poly(propylene glycol): Kinetics and Modeling
Authors: Li Li , Wu Linbo , Bu Zhiyang , Gong Cheng , Li Bo‐Geng , Hungenberg Klaus‐Dieter
Published: July 2012

A heterogeneous polymerization model, including an initial solution polymerization model and a later two‐phase polymerization model, is developed to describe graft free‐radical copolymerization of styrene and acrylonitrile in the presence of poly(propylene glycol). The diffusion‐controlled termination, initiation, propagation, and transfer in the dispersed phase are considered reasonably. The model describes the polymeriztion kinetics well. The main polymerization locus shifts from the continuous phase into the dispersed phase at monomer conversion of ≈0.03–0.05, leading to sharp increase in polymerization rate and molecular weight, decrease in graft efficiency and broadening of the MWD.

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Effect of Cocatalyst in Ethylene/Styrene Copolymerization by Aryloxo‐Modified Half‐Titanocene–Cocatalyst Systems for Exclusive Synthesis of Copolymers at High Styrene Concentrations
Authors: Nomura Kotohiro , Suzuki Naohiro , Kim Dong‐Hyun , Kim Hyun Joon
Published: July 2012

Factors affecting the product distributions in ethylene/styrene copolymerizations catalyzed by Cp*TiCl2(O‐2,6‐iPr2C6H3) are explored in the presence of various cocatalysts at high styrene/ethylene feed ratios (at 40 and 55 °C). Ethylene/styrene copolymers were the sole product when the reactions were conducted in the presence of [PhN(H)Me2][B(C6F5)4] and AliBu3/Al(octyl)3 even at 55 and 70 °C, whereas syndiotactic polystyrene was by‐produced when the polymerizations were performed at >40 °C in the presence of MAO; the ratios of the copolymer/SPS were affected by the reaction temperature as well as Al cocatalyst employed.

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Genetics and epigenetics of hepatoblastoma
Authors: Tomlinson Gail E. , Kappler Roland
Published: July 2012

A number of unique genetic features are observed in hepatoblastoma that have provided insights into the origins of hepatoblastoma. Hallmark cytogenetic changes in hepatoblastoma include the acquisition of additional copies of whole chromosomes and a recurring unbalanced translocation involving 1q. Genetic syndromes are associated with approximately 15% of hepatoblastoma and the understanding and recognition of these syndromes will be important in determining future surveillance studies needed to prevent additional cancers in survivors as well as in some case guide the care of family members. This article will review the genetic changes, both germ line and acquired, that are recurring events in hepatoblastoma, with emphasis on how these genetic changes could work together with other developmental factors and influence cancer predisposition, tumor growth, as well as aid in prognosis. Tumor‐specific signatures based on transcriptional or epigenetic alterations will be reviewed that might be used in the future to better diagnose and subtype the disease as well as predict prognosis and response to therapy. Pediatr Blood Cancer 2012; 59: 785–792. © 2012 Wiley Periodicals, Inc.
An optimization method with experimental validation for the design of extrusion wire coating dies for a range of different materials and operating conditions
Authors: Lebaal N. , Puissant S. , Schmidt F.M. , Schläfli D.
Published: July 2012

The objective of this article is to determine a wire coating‐hanger melt distributor geometry to ensure a homogenous exit velocity distribution that will best accommodate a wide material range and multiple operating conditions (i.e., die wall temperature and flow rate change). The computational approach incorporates finite element (FE) analysis to evaluate the performance of a die design and includes a nonlinear constrained optimization algorithm based on the Kriging interpolation and sequential quadratic programming algorithm to update the die geometry. Two optimization problems are then solved, and the best solution is taken into account to manufacture the optimal distributor. The Taguchi method is used to investigate the effect of the operating conditions, i.e., melt and die wall temperature, flow rate and material change, on the velocity distribution for the optimal die. In the example chosen, the wire coating die geometry is optimized by taking into account the geometrical limitations imposed by the tool geometry. Finally, the FE analysis and optimization results are validated by comparison with the experimental data obtained with the optimal die. The purpose of the experiments described below is to investigate the effect of material change. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers
Effect of accelerated ultraviolet and thermal exposure on nanoscale mechanical properties of nylon fibers
Authors: Wanasekara Nandula D. , Chalivendra Vijaya , Calvert Paul
Published: July 2012

Nanoindentation using atomic force microscopy was used to examine the mechanical properties of fibers at nanoscale. The effect of accelerated aging of nylon fibers under ultraviolet (UV) and thermal‐oxidative conditions on mechanical property gradients across the fiber cross‐section was investigated. It was identified that UV degradation produces bulk degradation up to 48 h of exposure and later surface degradation predominates with lower values of Young's modulus at surface compared to center. Wide angle X‐ray scattering shows a decrease of crystallinity with UV exposure. Unlike UV degradation, the thermal degradation was predominant at the surface for the first 3 weeks of exposure and was homogeneous after 4 weeks of exposure. These results support the idea that property gradients arise at high levels of degradation of nylon fiber as a result of UV and thermal‐oxidative conditions, and ultimately lead to embrittlement of the fibers. These results are in contrast to polypropylene, where the nanoindentation modulus increased with degradation and increased from the core to the surface after degradation. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers
Theoretical modeling and experiments on the piezoelectric coefficient in cellular polymer films
Authors: Qaiss A. , Saidi H. , Fassi‐Fehri O. , Bousmina M.
Published: July 2012

This article presents an analytical model allowing the determination of the, d33, piezoelectric coefficient in cellular polymer films. The cellular film is identified to an equivalent effective layered structure made of alternating gas and solid layers that are electrically charged at their interfaces. The model expresses the d33 piezoelectric coefficient as a function of porosity, film thickness, free‐stress surface charge density, and the film modulus, which depends on frequency. The temperature is indirectly taken into account as it is involved in the parameters appearing in the final equation of the model. The obtained results showed that the piezoelectric activity of charged cellular polymer films decreases with the film thickness and increases with the film expansion and the surface charge density. The variation with the percentage of porosity shows a nonlinear trend, with an increase in the d33 piezoelectric coefficient with the void fraction, and then a decrease when such a percentage exceeds a thickness‐dependent critical value. Such quantitative description of the piezoelectric activity can help the design of cellular films with enhanced piezoelectric performances. The model predictions were also compared with some experimental results obtained on cellular piezoelectric films made of polypropylene filled with 10% of calcium carbonate microparticles. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Thermal, mechanical, and rheological properties of polylactide/poly(1,2‐propylene glycol adipate)
Authors: Zhang Huiliang , Fang Jianyong , Ge Huanhuan , Han Lijing , Wang Xuemei , Hao Yanping , Han Changyu , Dong Lisong
Published: July 2012

Polylactide (PLA) was melt blended with poly(1,2‐propylene glycol adipate) (PPA) in a Thermo‐Haake mixer. Thermal, mechanical, and rheological properties of the blends were investigated by means of differential scanning calorimetry, dynamic mechanical analysis, tensile test, and small amplitude oscillatory shear rheometry. PPA lowered the glass transition temperature and increased the ability of PLA to cold crystallization. With the increase in PPA content (5–25 wt%), the blends showed decreased tensile strength and Young's modulus; however, impact strength and elongation‐at‐break along were dramatically increased due to the plastic deformation. Morphological results of PLA/PPA blends showed that PPA was good compatible with PLA. The plasticization effect of PPA was also manifested by the lowering of dynamic storage modulus and viscosity in the melt state of the blends compared with neat PLA. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Optical properties of europium (2,2′‐bipyridine‐N,N‐dioxide)2 (NO3)3 complex‐doped poly(methyl methacrylate)
Authors: Puthiyottil R. , Varghese S. , Gopalakrishnapanicker U. , Guthrie J.T.
Published: July 2012

A complex of Eu(C10H8N2O2)2 (NO3)3, in different amounts [0.1, 0.3, 0.5, 1, 2 wt % with respect to the poly(methyl methacrylate) (PMMA)], was doped into PMMA matrix and the resulting formulation deposited by a solvent casting technique. Each complex‐doped PMMA composition was characterized by UV‐visible spectroscopy, fluorescence spectroscopy, fluorescence lifetime analysis, X‐ray diffraction and infrared spectroscopy. The structural properties of the composites are discussed on the basis of the results from these analyses. The chelate‐doped PMMA shows good luminescence properties with relatively long life times. It has been shown that the fluorescence life time of the complex‐doped PMMA composites varies with the amount of the chelate molecule in the composite. The results from the fluorescence analyses suggest that, in the doped systems, the microenvironment around the central metal ion changes with composition. The optical properties of the system vary with composition. The observations should be of value to the development of superior luminescent materials. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
In situ studies on the temperature‐related deformation behavior of isotactic polypropylene spherulites with uniaxial stretching: The effect of crystallization conditions
Authors: Huo Hong , Yao Xuemin , Zhang Yao , Li Jingqing , Shang Yingrui , Jiang Shichun
Published: July 2012

The deformation behavior of isotactic polypropylene (iPP) spherulites with uniaxial stretching was investigated at different drawing temperatures via in situ polarized optical microscope (POM) observation. The iPP spherulites were prepared by two procedures: cooled to the room temperature from melt and annealed at 135, 140, and 145°C for 3 h. It was found that the crystallization conditions dominate the crystalline morphology and even the tensile properties of iPP. For iPP which crystallized during cooling progress, the spherulites were imperfect and the boundaries of the spherulites were diffuse, displaying good toughness at various drawing temperatures. For iPP annealed at high temperatures displayed the brittle fracture‐modes and the crack happened between spherulites, which due to the large and perfective spherulites have thick lamellas and weak connection at interspherulitic boundary. The shape and size of the iPP spherulites formed at 140 and 145°C are affected with uniaxial stretching till to the fracture of the samples at different drawing temperatures. The spherulites obtained at 135°C are deformed along the drawing direction at 100°C but not affected at low drawing temperatures, indicating the toughness increased with the increase of the drawing temperatures. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Glycerol and esterified products of palmitic acid as a mixed plasticizer for thermoplastic tapioca starch
Authors: Ekabutr Pongpol , Lerdwijitjarud Wanchai , Sittattrakul Amnard
Published: July 2012

In this work, a mixture of glycerol (Gly) and derivatives of pentaerythritol or α,α′‐diglycerol is used as a plasticizer for preparing a thermoplastic starch (TPS). A coplasticizer containing both hydroxyl group and a long aliphatic chain was synthesized by esterification reaction between pentaerythritol or α,α′‐diglycerol and palmitoyl chloride in two different molar ratios, that is, 1:1 (PT1 and DG1), 1:2 (PT2 and DG2). The esterification products were characterized using Fourier transform infrared spectroscopy, 1H, and 13C nuclear magnetic resonance spectroscopy. The starch and the mixed plasticizer were blended in an internal mixer. The morphology and miscibility of the blends were investigated by scanning electron microscope. The mechanical properties, moisture adsorption, and retrogradation phenomenon of the TPS specimens were studied. The results indicated that the TPS specimen containing a mixed plasticizer in a weight ratio of 80% Gly: 20% PT1 showed the highest values of Young's modulus and tensile strength, because this mixed plasticizer system could form stronger hydrogen bonds with starch molecules. Moreover, thermoplastic starch with higher content of pentaerythritol or α,α′‐diglycerol derivatives as a coplasticizer showed lower moisture adsorption, because its long aliphatic chain (hydrophobic part) of pentaerythritol derivatives may prevent starch molecules to reform hydrogen bonding and to recrystallize. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Reinforcing effect of nanosilica on the properties of natural rubber/reclaimed ground rubber tire vulcanizates
Authors: De Debapriya , Panda Prabir Kr. , Roy Madhusudan , Bhunia Satyaban , Jaman Abu Ismail
Published: July 2012

In this investigation, incorporation of silica into natural rubber (NR)‐reclaim rubber (RR) blend system was carried out by sol‐gel technique at various sol‐gel reaction temperatures. The effect of RR on silica reinforcement, hitherto unexplored, was studied for different NR/RR blend systems. The degree of reinforcement of sol‐gel vulcanizates by equilibrium swelling method indicates that the reinforcing efficiency of the in situ generated silica by sol‐gel technique increases with increasing reclaim rubber content. The reinforcing efficiency, tensile properties and thermal stability of sol gel vulcanizates (SGV) prepared at 50°C become maxima as compared to SGV prepared at 30°C and 70°C. The amount of silica incorporated by sol‐gel technique was determined by thermogravimetry analysis. It indicates that the thermal stability increases with silica content. Attenuated total reflection study indicates that RR forms bond with silica particles due to the presence of active functional site on RR. Scanning electron microscopy studies further indicate the coherency and homogeneity in the silica filled NR/RR vulcanizates. The microwave diagnosis of different SGVs was also carried out and the frequency dependence of dielectric permittivity (E') and loss (E”) were measured. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Production of double‐walled nanoparticles containing meloxicam
Authors: Albuquerque Bruna , Costa Mariana Sousa , Peça Inês N. , Cardoso M. Margarida
Published: July 2012

Double‐walled nanospheres, containing meloxicam, were fabricated with poly‐(D,L‐lactide‐co‐glycolide) (PLGA) and poly(L‐lactide) (PLLA) using the solvent evaporation technique. This article discusses the effect of formulation variables [sonication power, sonication time, concentration of poly(vinyl alcohol), organic/aqueous volume ratio in the first emulsion] on the production of double‐walled nanospheres. The involved phase separation of these two polymers was investigated using differential scanning calorimetry. Double‐walled microspheres containing meloxicam were also produced to determine the composition of the shell and core polymer, based on different solubilities of polymers in ethyl acetate, and to examine the inner morphology and drug distribution using optical and fluorescence microscopy. The produced microparticles have shown a double‐walled structure with meloxicam solubilized in the PLGA‐rich phase. Therefore, adjusting the selected formulation variables and using a mass ratio of 1:1 PLLA/PLGA, double‐walled nanospheres where meloxicam is dispersed within the core can be produced. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Using NSGA‐II and TOPSIS Methods for Interior Ballistic Optimization Based on One‐Dimensional Two‐Phase Flow Model
Authors: Li Kejing , Zhang Xiaobing
Published: July 2012

In order to meet the design demands of new gun systems or new types of projectiles, the interior ballistic charge design seems especially important. In this paper, a one‐dimensional two‐phase flow model is presented. The model describes the transient combustion of granular propellants in a gun, and pressure waves are considered as an objective. This study adopts a hybrid method to solve the problem. In the first stage, the non‐dominated sorting genetic algorithm (NSGA‐II) with “a “filter” is employed to approximate a set of Pareto‐optimal solutions. In the subsequent stage, a multi‐attribute decision‐making (MADM) approach is adopted to rank these solutions from the best to the worst. The ranking of Pareto‐optimal solutions is based on the technique ordered preference by similarity to ideal solution (TOPSIS) method. In TOPSIS method each objective needs a corresponding weight coefficient, and a practical problem is introduced. Both the entropy method and linear analysis method are adopted to get two sets of weights for the objectives, respectively. The two pairs of final, best compromise solutions are compared for satisfying the designer’s aim. For the analysis of the results, a two‐phase flow interior ballistic model for design optimization is established, and the hybrid approach could get a reasonable design scenario.
Experimental results from a linear wave power generator connected to a resonance circuit
Authors: Ekergård Boel , Boström Cecilia , Hagnestål Anders , Waters Rafael , Leijon Mats
Published: July 2012

The output voltage from a direct‐driven permanent magnet linear generator installed in a wave power plant varies both in amplitude and frequency. Electrical conversion is therefore necessary before grid connection can be achieved. The aim of this paper is to present an electrical conversion system based on the electric resonance phenomena. As one of the first steps in the development, and to gain further knowledge and understanding of the proposed resonance circuit, experimental tests with a single‐phase permanent magnet linear generator connected to a resonance circuit were performed. The experimental results presented in this paper indicated that a successful resonance between the generator and external circuit was achieved. The research regarding the wave energy converters lies within The Lysekil Wave Power Project at Uppsala University and has been ongoing since 2002.

This article is categorized under:

Wind Power > Science and Materials

Energy Infrastructure > Systems and Infrastructure
Forest bioenergy feedstock harvesting effects on water supply
Authors: Neary Daniel G. , Koestner Karen A.
Published: July 2012

Water flowing from forested catchments, both unmanaged and managed, is highly valued in terms of both quantity and quality. Increasing energy production using wood feedstocks produces varying degrees of impacts and thereby raises concerns about environmental impacts on the highly valued water supply resources of forest ecosystems. The term water supply encompasses both key components of water quantity and water quality. Water quantity considers the amount of increases or decreases, timing, consistency, and relative magnitude of water yields. Plant nutrients (anions and cations), fertilizers, herbicides, ash additions, temperature, dissolved oxygen, pH, bacteria, and sediment comprise water quality. Within the life cycle of forest bioenergy, operational activities during stand establishment, midrotation silviculture, harvesting, product transportation, wood storage, energy production, and ash recycling create variable levels of impacts. Disturbance levels associated with bioenergy operations depend on their type, intensity, frequency, duration, timing, area of extent, and the level of best management practices (BMPs) employed for mitigating of soil disturbances. Feedstock growing, stand tending, harvesting, and wood transportation are considered nonpoint source disturbances since they occur over larger landscapes than energy production activities, which are usually localized at power plants. Water‐quantity effects of forest bioenergy production are normally associated with vegetation management and related soil disturbances. Water‐quality effects mostly occur as a result of soil disturbances during harvesting, the use of intra‐rotation silvicultural chemicals (ash, fertilizers, and herbicides), and inter‐rotation site preparation for forest regeneration. Using existing practices designed for environmental protection (BMPs), forest bioenergy programs are completely compatible with maintaining high‐quality water supplies in forested catchments.

This article is categorized under:

Bioenergy > Climate and Environment

Energy Policy and Planning > Climate and Environment

Energy and Development > Climate and Environment
NLO Higgs boson production plus one and two jets using the POWHEG BOX, MadGraph4 and MCFM
Authors: Campbell John M. , Ellis R. Keith , Frederix Rikkert , Nason Paolo , Oleari Carlo , Williams Ciaran
Published: July 2012

Abstract

We present a next-to-leading order calculation of Higgs boson production plus one and two jets via gluon fusion interfaced to shower Monte Carlo programs, implemented according to the POWHEG method. For this implementation we have used a new interface of the POWHEG BOX with MadGraph4, that generates the codes for generic Born and real processes automatically. The virtual corrections have been taken from the MCFM code. We carry out a simple phenomenological study of our generators, comparing them among each other and with fixed next-to-leading order results.
Vulnerability and Resilience in a Socio-Spatial Perspective
Authors: Christmann Gabriela B. , Ibert Oliver
Published: July 2012

This paper argues that the conceptions of “vulnerability” and “resilience”, which have been strongly influenced by ecology and natural hazards research, have been widely used in an essentialist manner. Thus, vulnerability is treated as the factual susceptibility and resilience as the factual adaptive capacity of systems, which are measurable by certain indicators. Although in the meantime social dimensions have received greater consideration than previously and although both notions have been transferred to a wider field of phenomena ranging from technology to economy and society, the conception of vulnerability and resilience still lacks the dimension of the social construction of reality that implies that actors may develop different perceptions of potential threats and of the precautionary measures that are to be adopted—even though the nature of an endangerment seems clear and proven. In this contribution we identify major conceptual desiderata and suggest a social science based conception of vulnerability and resilience addressing them. We take up ideas from social constructivism in the form pointed out in actor-network theory. We dissolve the tired dichotomy between social and material entities and instead emphasise that all kinds of entities have the same ontological status and thus interact directly with one another on the same level (‘flat ontology’). Against the background of a generic definition of governance, questions of agency in networks will be addressed. Based on a relational understanding of space, a spatial research perspective will be developed also taking into account the dimension of time. Finally the conception comprises an empirical strategy for investigating vulnerability and resilience.
The IVP for the dispersion generalized Benjamin–Ono equation in weighted Sobolev spaces
Authors: Fonseca Germán , Linares Felipe , Ponce Gustavo
Published: July 2012

We study the initial value problem associated to the dispersion generalized Benjamin–Ono equation. Our aim is to establish persistence properties of the solution flow in weighted Sobolev spaces and to deduce from them some sharp unique continuation properties of solutions to this equation. In particular, we shall establish optimal decay rate for the solutions of this model.

Nous étudions le problème de Cauchy associé à lʼéquation de Benjamin–Ono avec dispersion généralisée. Notre objectif est dʼétablir les propriétés de persistance de la solution dans des espaces de Sobolev avec poids et dʼen déduire quelques propriétés de prolongement unique pour ses solutions. En particulier, nous établirons un taux de décroissance optimal pour les solutions de ce modèle.
Control of the secondary cross-flow instability using localized suction
Authors: Friederich Tillmann , Kloker Markus J.
Published: July 2012

Transition control by suction in a three-dimensional boundary-layer flow subject to cross-flow instability is investigated using direct numerical simulation. Whereas the classical application of (homogeneous) suction at the wall is aimed at modifying the quasi-two-dimensional base flow to weaken primary cross-flow instability, here the three-dimensional nonlinear disturbance state with large-amplitude steady cross-flow vortices (CFVs) is controlled. Strong, localized ‘pinpoint’ suction is shown to be suitable for altering the CFVs and the associated flow field such that secondary instability is weakened or even completely suppressed. Thus significant delay of transition to turbulence can be achieved.
Interaction of a laminar vortex ring with a thin permeable screen
Authors: Naaktgeboren Christian , Krueger Paul S. , Lage José L.
Published: July 2012

The canonical case of a vortex ring interacting with a solid surface orthogonal to its symmetry axis exhibits a variety of intricate behaviours, including stretching of the primary vortex ring and generation of secondary vorticity, which illustrate key features of vortex interactions with boundaries. Replacing the solid boundary with a permeable screen allows for new behaviour by relaxing the no-through-flow condition, and can provide a useful analogue for the interaction of large-scale vortices with permeable structures or closely spaced obstructions. The present investigation considers the interaction of experimentally generated vortex rings with a thin permeable screen. The vortex rings were generated using a piston-in-cylinder mechanism using piston stroke-to-diameter ratios ($L/ D$) of 1.0 and 3.0 (nominal) with jet Reynolds numbers ($R{e}_{j} $) of 3000 and 6000 (nominal). Planar laser-induced fluorescence and digital particle image velocimetry (DPIV) were used to study the interaction with wire-mesh screens having surface open-area ratios ($\phi $) in the range 0.44–0.79. Solid surfaces ($\phi = 0$) and free vortex rings ($\phi = 1$) were also included as special cases. Measurement of the vortex trajectories showed expansion of the vortex ring diameter as it approached the boundary and generation of secondary vorticity similar to the case of a solid boundary, but the primary vortex diameter then began to contract towards the symmetry axis as the flow permeated the screen and reorganized into a transmitted vortex downstream. The trajectories were highly dependent on $\phi $, with little change in the incident ring trajectory for $\phi = 0. 79$. Measurement of the hydrodynamic impulse and kinetic energy using DPIV showed that the change between the average upstream and downstream values of these quantities also depended primarily on $\phi $, with a slight decrease in the relative change as $L/ D$ and/or ${\mathit{Re}}_{j} $ were increased. The kinetic energy dissipation ($ \mrm{\Delta} E$) was much more sensitive to $\phi $, with a strongly nonlinear dependence, while the decrease in impulse ($ \mrm{\Delta} I$) was nearly linear in $\phi $. A simple model is proposed to relate $ \mrm{\Delta} E$ and $ \mrm{\Delta} I$ in terms of bulk flow parameters. The model incorporates the decrease in flow velocity during the interaction due to the drag force exerted by the screen on the flow.
Inertial dynamics of air bubbles crossing a horizontal fluid–fluid interface
Authors: Bonhomme Romain , Magnaudet Jacques , Duval Fabien , Piar Bruno
Published: July 2012

The dynamics of isolated air bubbles crossing the horizontal interface separating two Newtonian immiscible liquids initially at rest are studied both experimentally and computationally. High-speed video imaging is used to obtain a detailed evolution of the various interfaces involved in the system. The size of the bubbles and the viscosity contrast between the two liquids are varied by more than one and four orders of magnitude, respectively, making it possible to obtain bubble shapes ranging from spherical to toroidal. A variety of flow regimes is observed, including that of small bubbles remaining trapped at the fluid–fluid interface in a film-drainage configuration. In most cases, the bubble succeeds in crossing the interface without being stopped near its undisturbed position and, during a certain period of time, tows a significant column of lower fluid which sometimes exhibits a complex dynamics as it lengthens in the upper fluid. Direct numerical simulations of several selected experimental situations are performed with a code employing a volume-of-fluid type formulation of the incompressible Navier–Stokes equations. Comparisons between experimental and numerical results confirm the reliability of the computational approach in most situations but also points out the need for improvements to capture some subtle but important physical processes, most notably those related to film drainage. Influence of the physical parameters highlighted by experiments and computations, especially that of the density and viscosity contrasts between the two fluids and of the various interfacial tensions, is discussed and analysed in the light of simple models and available theories.
Self-similar transport of inertial particles in a turbulent boundary layer
Authors: Sardina G. , Schlatter P. , Picano F. , Casciola C. M. , Brandt L. , Henningson D. S.
Published: July 2012

Results are presented from a direct numerical simulation of a particle-laden spatially developing turbulent boundary layer up to ${\mathit{Re}}_{\theta } = 2500$. The peculiar feature of a boundary-layer flow seeded with heavy particles is the variation of the local dimensionless parameters defining the fluid–particle interactions along the streamwise direction. Two different Stokes numbers can be defined, one using inner flow units and the other with outer units. Since these two Stokes numbers exhibit different decay rates in the streamwise direction, we find a decoupled particle dynamics between the inner and the outer region of the boundary layer. Preferential near-wall particle accumulation is similar to that observed in turbulent channel flow, while different behaviour characterizes the outer region. Here the concentration and the streamwise velocity profiles are found to be self-similar and to depend only on the local value of the outer Stokes number and the rescaled wall-normal distance. These new results are powerful in view of engineering and environmental applications and corresponding flow modelling.
Nagata compactification for algebraic spaces
Authors: Conrad Brian , Lieblich Max , Olsson Martin
Published: July 2012

We prove the Nagata compactification theorem for any separated map of finite type between quasi-compact and quasi-separated algebraic spaces, generalizing earlier results of Raoult. Along the way we also prove (and use) absolute noetherian approximation for such algebraic spaces, generalizing earlier results in the case of schemes.
How (Not) to measure institutions
Authors: VOIGT STEFAN
Published: July 2012

The statement ‘institutions matter’ has become commonplace. A precondition for it to be supported by empirical evidence is, however, that institutions are measurable. Some of the difficulties in measuring institutions are described and some ways of measuring them are proposed.
Revisiting the role of process incentives as a determinant of university students’ protest
Authors: Dinas Elias , Gemenis Kostas
Published: July 2012

Drawing on the original data collected during a period of university student protest in Greece, we explore whether the expected gains from the act of protesting itself influence an individual's decision to participate in collective action. More particularly, we investigate the extent to which the process incentives qualify the weight individuals attach to the primary elements of the original cost–benefit equation of rational choice theory as well as other considerations in their decision-making process. Our findings point out that the magnitude of the effect of the process incentives is very strong and its inclusion in a rational choice model improves our understanding of students’ participation in protest activities. Turning to indirect effects, we show that process incentives behave as a first stage precondition for the students’ decision to participate in collective action. In the absence of perceived benefits associated with the process of protesting, the importance of attaining the public good becomes much less important in their decision-making process.
Using Redundant Visual Information From Different Dimensions for Attentional Selection
Authors: Berti Stefan , Wühr Peter
Published: July 2012

The present study investigated the use of redundant information for attentional selection of a visual object. Each display contained two overlapping objects, and participants had to report the color of the occluding object. A baseline condition did not require object selection because the objects were identical. A single-cue condition required object selection based on spatial arrangement (i.e., occlusion) because the objects had the same shape. A double-cue condition afforded object selection by occlusion and shape because the objects consistently differed in shape. Behavioral results showed that the redundant shape cue facilitated attentional selection, although participants were never supposed to respond to shape. The Event-Related Brain Potential (ERP) results showed a posterior N2 effect in both selection conditions, and a frontal N2 effect in the double-cue condition only. These results suggest that the redundancy gain in the double-cue condition relied on processes of voluntary attention, presumably the increase of attentional weights for visual shape information.
Handicapped Due to Age?
Authors: Getzmann Stephan
Published: July 2012

Older individuals often find it hard to communicate under difficult listening conditions, for example, in the presence of background noise or competing speakers. However, there is increasing evidence that this age-related decline in speech perception can be – at least in part – compensated by an increased recruitment of more general cognitive functions. The interplay of age-related declines and compensatory mechanisms in spoken language understanding under naturalistic and demanding listening conditions was tested here in a word detection task. Pairs of different coherent stories were presented dichotically to 14 younger and 14 older listeners (age ranges 19–25 and 54–64 years, respectively). The listeners had to respond to target words in one story, while suppressing distracting information in the other. In addition, the listeners had to pay attention to the content of the attended story. Older listeners outperformed the younger listeners in target detection and produced less missing responses. However, high performance in target detection came along with low performance in text recall. The analyses of event-related potentials indicated a reduction in parietal P3b of older, relative to younger, listeners. In turn, older listeners showed a prominent frontal P3a that was absent in younger listeners. In line with the so-called decline-compensation hypothesis, these results support the idea that, in order to perform well, older listeners compensate a potential decline by extra allocation of mental resources. One potential mechanism of compensation could be a selective attentional orientation to the target stimuli.
Surface hopping trajectory simulations with spin-orbit and dynamical couplings
Authors: Granucci Giovanni , Persico Maurizio , Spighi Gloria
Published: July 2012

In this paper we consider the inclusion of the spin-orbit interaction in surface hopping molecular dynamics simulations to take into account spin forbidden transitions. Two alternative approaches are examined. The spin-diabatic one makes use of eigenstates of the spin-free electronic Hamiltonian and of \documentclass[12pt]{minimal}\begin{document}$\hat{S}^2$\end{document}Ŝ2 and is commonly applied when the spin-orbit coupling is weak. We point out some inconsistencies of this approach, especially important when more than two spin multiplets are coupled. The spin-adiabatic approach is based on the eigenstates of the total electronic Hamiltonian including the spin-orbit coupling. Advantages and drawbacks of both strategies are discussed and illustrated with the help of two model systems.