bluuebunny/crossref_metadata_2025 huggingface dataset:
Steinkohle in Deutschland 2012
Authors: van de Loo Kai , Sitte Andreas‐Peter
Published: June 2013

Im Jahr 2012 war international, aber auch national ein Zuwachs des Steinkohlenverbrauchs zu verzeichnen. Weltweit ist die Steinkohle weiterhin der Energieträger Nr. 1 in der Stromerzeugung, was zu einem steigenden Bedarf an Kraftwerkskohle führt. In Deutschland nahm die Steinkohlenverstromung in diesem Jahr ebenfalls zu. Dagegen war die Kokskohlen‐ und Koksnachfrage der Stahlindustrie konjunkturell bedingt rückläufig. Der erhöhte Einsatz der Kohle zur Stromerzeugung hierzulande erklärte sich neben dem Rückgang der Kernkraft aus einem relativ schlechten “Windjahr” sowie gesunkenen Einfuhrpreisen und niedrigen CO2‐Preisen, die zusammen einen deutlichen Preisvorteil für die Kohle gegenüber dem Kraftwerkseinsatz von Erdgas begründeten. Dahinter stand vor allem der Preisdruck billiger US‐Kohle, die auf ihrem Heimatmarkt teilweise durch die Expansion des Shale Gas verdrängt wurde und sich ein Absatzventil in Europa suchte. Die heimische Steinkohle hat ihren Anpassungs‐ und Auslaufprozess planmäßig fortgeführt, weitere zwei von bis dahin noch fünf deutschen Bergwerken sind 2012 stillgelegt worden. Die RAG Aktiengesellschaft, die den Steinkohlenbergbau hierzulande betreibt, beginnt mit den Vorbereitungen auf die Nachbergbauzeit.

Hard coal in Germany 2012

Coal consumption increased internationally in 2012, and also in Germany. Coal remains the leading source of energy for electricity generation, which led to increasing demand for coal for power stations. Germany also saw increased coal consumption in power stations this year. In contrast, the demand for coking coal and coke for the steel industry fell in line with reduced production. The increased use of coal for electricity generation in Germany can be explained not only by the reduction of atomic power but also by a relatively poor “wind year” and lower import prices and low CO2 prices, which combined to give coal a considerable price advantage over gas for use in power stations. This is due above all to the influence on prices of cheaper US coal, which has been partially displaced in its home market by the expansion of shale gas and found an outlet in Europe. Coal production in Germany has continued the process of adaptation and phasing out, with a further two of the five German mines being closed in 2012. The RAG AG, which operates coal mines in Germany, is already preparing for the era without coal mines.
Relaxation and gas drainage boreholes for high performance longwall operations in low permeability coal seams
Authors: Imgrund Thomas , Bauer Frank
Published: June 2013

With an increasing depth of cover, gas emission control and gas outbursts prevention has become an increasingly important issue in coal mining. Deep multi‐seam mining often requires operation in an environment characterised by a high gas content and gas pressure. Control of gas related risks has to be realised during heading and close to the longwall by proper risk assessment and flexible drilling schemes. These cover exploration and relaxation drilling, in‐seam drilling for pre‐drainage and cross measure drilling for drainage of roof and the floor gas emissions. DMT provides comprehensive solutions based on a scientific background. These solutions are engineered considering their technical feasibility. Hazemag Mining offers a large number of complete machinery including tools systems for the implementation of those solutions.
FAB‐Länderworkshop – Rohstoffpartnerschaft und ‐kooperation
Authors: Wedig Martin
Published: June 2013

Am 19. und 20. März 2013 hat die Fachvereinigung Auslandsbergbau und internationale Rohstoffaktivitäten in der Vereinigung Rohstoffe und Bergbau e.V. in Berlin einen Länderworkshop zum Thema “Rohstoffpartnerschaft und ‐kooperation” veranstaltet. Mehr als 45 Teilnehmer aus unterschiedlichen Geschäftsbereichen waren der Einladung gefolgt und trugen zu außerordentlich interessanten Diskussionsrunden zu den jeweiligen Vorträgen bei. Der folgende Bericht spiegelt die Aspekte der Rohstoffpartnerschaften aus den Bereichen der Politik und Verwaltung, der Wirtschaft und der Wissenschaft wider und fasst die wesentlichen Ergebnisse des Workshops zusammen.
Ohne Braunkohle kein Fortschritt
Authors: Pasche Eckart
Published: June 2013

Der Einladung des Deutschen Braunkohlen‐Industrie‐Vereins (Debriv) folgten am 16. Mai 2013 rund 450 Fachleute aus Politik, Industrie und Organisationen. Das Motto “Braunkohle – Partner und Impulsgeber” deutet schon auf die lokale und regionale Verankerung der deutschen Braunkohlenindustrie hin. So stellten alle Redner Partnerschaft, Kooperation und Akzeptanz als Mittelpunkt ihres unternehmerischen Handelns heraus.
bauma 2013 – Entwicklungen und Trends auf dem Gebiet der Gewinnungstechnik
Authors: Nienhaus Karl , Hahn Martin , Zingsheim Moritz , Röllinger Dennis
Published: June 2013

Vom 15. bis 21. April 2013 fand in München die bauma 2013, Internationale Fachmesse für Baumaschinen, Baustoffmaschinen, Bergbaumaschinen, Baufahrzeuge und Baugeräte, zum 30. Mal statt. Über 3.300 Aussteller präsentieren auf einer erweiterten Ausstellungsfläche von 570.000 m2 neue und bewährte Produkte der internationalen Bau‐, Baustoff‐ und Bergbaumaschinenindustrie. Der vorliegende Beitrag gibt eine Übersicht zu den neuesten Entwicklungen und Trends aus den Bereichen der untertägigen Gewinnungstechnik, des Tunnelbaus sowie des Tagebaus
Joint inventory and pricing decisions for perishable products with two‐period lifetime
Authors: Chen Li‐Ming , Sapra Amar
Published: June 2013

We consider a periodic review model over a finite horizon for a perishable product with fixed lifetime equal to two review periods. The excess demand in a period is backlogged. The optimal replenishment and demand management (using price) decisions for such a product depend on the relative order of consumption of fresh and old units. We obtain insights on the structure of these decisions when the order of consumption is first‐in, first‐out and last‐in, first‐out. For the FIFO system, we also obtain bounds on both the optimal replenishment quantity as well as expected demand. We compare the FIFO system to two widely analyzed inventory systems that correspond to nonperishable and one‐period lifetime products to understand if demand management would modify our understanding of the relationship among the three systems. In a counterintuitive result, we find that it is more likely that bigger orders are placed in the FIFO system than for a nonperishable product when demand is managed. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013
Positron annihilation lifetime spectroscopy for miscibility investigations of styrene–butadiene–styrene copolymer/polystyrene blends
Authors: Meng Xiaoyu , Liu Xu , Li Zhuoxi , Zhou Qiong
Published: June 2013

The free volume parameters of styrene–butadiene–styrene copolymer/polystyrene (SBS/PS) blends were investigated with positron annihilation lifetime spectroscopy (PALS) in this study. The behaviors of free volume distribution, average free volume, and relative fractional free volume revealed the difference of interfacial miscibility. Based on different models, inter‐chain interaction parameter β, geometric factor γ, and hydrodynamic interaction parameter α obtained from free volume data were employed to further determine the effect of molecular architecture and styrene content on the miscibility. The results suggest the better miscibility in star‐shaped SBS/PS blends than that of corresponding linear SBS/PS systems, even than that of systems containing more styrene unit. In addition, differential scanning calorimetry, dynamic mechanical analysis, and scanning electron microscopy, which are sensitive to heterogeneities in larger domain size, give different results of miscibility from free volume data. It should be attributed the difference of characterization scale. The mechanical property corroborates the results of miscibility. POLYM. ENG. SCI., 54:785–793, 2014. © 2013 Society of Plastics Engineers
Radical copolymerization of acrylonitrile with 2,2,2‐trifluoroethyl acrylate for dielectric materials: Structure and characterization
Authors: Atlas Salima , Raihane Mustapha , Hult Anders , Malkoch Michael , Lahcini Mohammed , Ameduri Bruno
Published: June 2013

Radical copolymerization based on acrylonitrile (AN) and 2,2,2‐Trifluoroethyl acrylate (ATRIF) initited by AIBN was investigated in acetonitrile solution. The resulting poly(AN‐co‐ATRIF) copolymers were characterized by 1H, 13C, and 19F NMR and IR spectroscopy, and size exclusion chromatography (SEC). Their compositions were assessed by 1H NMR. The kinetics of radical copolymerization of AN with ATRIF was investigated from sereval experiments achieved at 70 °C from initial [AN]0/[ATRIF]0 molar ratios ranging between 20/80 and 80/20 and was enabled to determine the reactivity ratios of both comonomers. From the monomer—polymer copolymerization curve, the Fineman–Ross and Kelen–Tüdos laws enabled to assess the reactivity ratios (rAN= r1 = 1.25 ± 0.04 and rATRIF = r2 = 0.93 ± 0.05 at 70 °C) while the revised patterns scheme led to r12 = rAN = 1.03, and r21 = rATRIF = 0.78 at 70 °C. In all cases, rAN x rATRIF product was close to unity, which indicates that poly(AN‐co‐ATRIF) copolymers exhibit a random structure. This was also confirmed by the Igarashi's and Pyun's laws which revealed the presence of AN‐ATRIF, AN‐AN, and ATRIF‐ATRIF dyads. The Q and e values for ATRIF were also assessed (Q2 = 0.62 and e2 = 0.93). The glass transition temperature values, Tg, of these copolymers increased from 17 to 61 °C as the molar percentage of ATRIF decreased from 77 to 16% in the copolymer. Thermogravimetry analysis of poly(AN‐co‐ATRIF) copolymers showed a good thermal stability compared to that of poly(ATRIF) homopolymer due to incorporation of AN comonomer. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3856–3866
High‐performance In–Zn–O thin‐film transistors with a soluble processed ZrO2 gate insulator
Authors: Son Byeong‐Geun , Je So Yeon , Kim Hyo Jin , Lee Chul‐Kyu , Lee Chang‐Kyu , Hwang Ah Young , Won Ju Yeon , Song Ji Hun , Choi Rino , Jeong Jae Kyeong
Published: June 2013

Spin‐coated zirconium oxide films were used as a gate dielectric for low‐voltage, high performance indium zinc oxide (IZO) thin‐film transistors (TFTs). The ZrO2 films annealed at 400 °C showed a low gate leakage current density of 2 × 10–8 A/cm2 at an electric field of 2 MV/cm. This was attributed to the low impurity content and high crystalline quality. Therefore, the IZO TFTs with a soluble ZrO2 gate insulator exhibited a high field effect mobility of 23.4 cm2/V s, excellent subthreshold gate swing of 70 mV/decade and a reasonable Ion/off ratio of ∼106. These TFTs operated at low voltages (∼3.0 V) and showed high drain current drive capability, enabling oxide TFTs with a soluble processed high‐k dielectric for use in backplane electronics for low‐power mobile display applications. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the interface equation for the inversion of balance equations
Authors: Ren Shuzhan
Published: June 2013

Balance equations (BEs) which describe the balance constraints among balanced variables have wide applications in data assimilation and diagnosing balanced motions. In the applications an additional equation serving as an interface to connect the balanced variables and full ﬁelds (data assimilation analyses or ﬁelds of primitive equations) is required for the inversion of BEs to obtain the balanced variables.

The interface equation is often constructed through the potential vorticity (PV) based on the argument that PV of the full ﬁelds should be preserved in the balanced motion. However, it is not clear that for the given balance constraints this prescribed PV‐based interface equation can lead to the optimal solutions for the BEs.

To search for the interface equation which can produce the optimal solutions for the BEs under given balance constraints, the variational approach is proposed to derive instead of ‘prescribing’ the interface equation by minimizing an energy‐like norm under both geostrophic and Charney balance constraints. The derived interface equations are compared against the PV‐based interface equation for the two‐dimensional (2D) shallow‐water model and three‐dimensional (3D) baroclinic system. Analytical results show that the two kinds of interface equation are diﬀerent in general but are close when the Rossby number and the departure of geopotential/temperature from its reference value are small. The accuracy associated with the derived interface equation is examined by comparing the balanced variables obtained by inverting the BEs with the derived and PV‐based interface equations numerically in a hemisphere shallow‐water system. The results show that under the same balance constraint the derived interface equation leads to better global accuracy of balanced variables.
Revisiting the reactivity of different carbon bases: A theoretical study
Authors: Guha Ankur Kanti , Gogoi Ujjal , Phukan Ashwini K.
Published: June 2013

Quantum chemical calculations are performed on different carbon bases to understand the origin of their reactivity. Both carbon(0) and carbon(II) bases may show very high values of second proton affinity as well as bond dissociation energies for gem‐dimetallation. Thus, their distinction becomes blurred when subjected to electrophilic attack. However, unlike carbon(0) bases, carbon(II) bases are ambiphilic in nature owing to the presence of a σ symmetric lone pair and a vacant π orbital concentrated on the central carbon atom. Thus, they may show different reactivity when subjected to nucleophilic attack. This reactivity difference may be considered as another distinction between these two classes of compounds. © 2013 Wiley Periodicals, Inc.
Surface‐Layer Lattices as Patterning Element for Multimeric Extremozymes
Authors: Ferner‐Ortner‐Bleckmann Judith , Gelbmann Nicola , Tesarz Manfred , Egelseer Eva M. , Sleytr Uwe B.
Published: June 2013

A promising new approach for the production of biocatalysts comprises the use of surface‐layer (S‐layer) lattices that present functional multimeric enzymes on their surface, thereby guaranteeing most accurate spatial distribution and orientation, as well as maximal effectiveness and stability of these enzymes. For proof of concept, a tetrameric and a trimeric extremozyme are chosen for the construction of S‐layer/extremozyme fusion proteins. By using a flexible peptide linker, either one monomer of the tetrameric xylose isomerase XylA from the thermophilic Thermoanaerobacterium strain JW/SL‐YS 489 or, in another approach, one monomer of the trimeric carbonic anhydrase from the methanogenic archaeon Methanosarcina thermophila are genetically linked to one monomer of the S‐layer protein SbpA of Lysinibacillus sphaericus CCM 2177. After isolation and purification, the self‐assembly properties of both S‐layer fusion proteins as well as the specific activity of the fused enzymes are confirmed, thus indicating that the S‐layer protein moiety does not influence the nature of the multimeric enzymes and vice versa. By recrystallization of the S‐layer/extremozyme fusion proteins on solid supports, the active enzyme multimers are exposed on the surface of the square S‐layer lattice with 13.1 nm spacing.
Design Considerations for Semiconductor Nanowire–Plasmonic Nanoparticle Coupled Systems for High Quantum Efficiency Nanowires
Authors: Mokkapati Sudha , Saxena Dhruv , Tan Hark Hoe , Jagadish Chennupati
Published: June 2013

The optimal geometries for reducing the radiative recombination lifetime and thus enhancing the quantum efficiency of III–V semiconductor nanowires by coupling them to plasmonic nanoparticles are established. The quantum efficiency enhancement factor due to coupling to plasmonic nanoparticles reduces as the initial quality of the nanowire increases. Significant quantum efficiency enhancement is observed for semiconductors only within about 15 nm from the nanoparticle. It is also identified that the modes responsible for resonant enhancement in the quantum efficiency of an emitter in the nanowire are geometric resonances of surface plasmon polariton modes supported at the nanowire/nanoparticle interface.
Crystal Structures and Luminescent Properties of Two Zinc(II) Coordination Compounds with a β‐Diketonate Derivative Ligand
Authors: Zhang Hong‐Na , Wang Jin , Hu Huai‐Ming , Yuan Fei , Song Juan , Xue Gang‐Lin
Published: June 2013

The β‐diketonate derivative ligand [H2L = 6‐(3‐hydroxy‐1‐oxo‐3‐pyrryl‐2‐propen‐1‐yl)‐2‐pyridinecarboxylic acid] and its zinc(II) coordination complexes, [Zn(H2L)Cl2]·(EtOH)(H2O) (1) and [Zn4(L)4(H2O)2]·5H2O (2), were prepared and characterized by elemental analysis, IR and NMR spectroscopy, and single‐crystal X‐ray diffraction. Complex 1 is a mononuclear structure. Complex 2 is a [2 × 2] grid tetranuclear structure. The luminescent properties of the free ligand H2L and complexes 1 and 2 in methanol solution were studied.
Improving biobutanol production in engineered Saccharomyces cerevisiae by manipulation of acetyl-CoA metabolism
Authors: Krivoruchko Anastasia , Serrano-Amatriain Cristina , Chen Yun , Siewers Verena , Nielsen Jens
Published: June 2013

Recently, butanols (1-butanol, 2-butanol and iso-butanol) have generated attention as alternative gasoline additives. Butanols have several properties favorable in comparison to ethanol, and strong interest therefore exists in the reconstruction of the 1-butanol pathway in commonly used industrial microorganisms. In the present study, the biosynthetic pathway for 1-butanol production was reconstructed in the yeast Saccharomyces cerevisiae. In addition to introducing heterologous enzymes for butanol production, we engineered yeast to have increased flux toward cytosolic acetyl-CoA, the precursor metabolite for 1-butanol biosynthesis. This was done through introduction of a plasmid-containing genes for alcohol dehydrogenase (ADH2), acetaldehyde dehydrogenase (ALD6), acetyl-CoA synthetase (ACS), and acetyl-CoA acetyltransferase (ERG10), as well as the use of strains containing deletions in the malate synthase (MLS1) or citrate synthase (CIT2) genes. Our results show a trend to increased butanol production in strains engineered for increased cytosolic acetyl-CoA levels, with the best-producing strains having maximal butanol titers of 16.3 mg/l. This represents a 6.5-fold improvement in butanol titers compared to previous values reported for yeast and demonstrates the importance of an improved cytosolic acetyl-CoA supply for heterologous butanol production by this organism.
Biomass production, relative competitive ability and water use efficiency of two dominant species in semiarid Loess Plateau under different water supply and fertilization treatments
Authors: Xu Bing‐Cheng , Xu Wei‐Zhou , Gao Zhi‐Juan , Wang Jing , Huang Jin
Published: June 2013

Water stress and nutrient deficiency are considered to be the main environmental factors limiting plant growth and species interaction in semiarid regions. However, less is known about the interactive effects of soil water, nitrogen and phosphorus on native species growth and relative competitive ability. A replacement series design method was used with 12 mixed plants of Bothriochloa ischaemum and Lespedeza davurica grown in a pot experiment under three water regimes and four fertility treatments. Intercropping systems were assessed on the basis of indices such as biomass production and allocation, relative competitive ability, aggressivity, relative yield total and water use efficiency (WUE). Water stress decreased significantly the total biomass production for each species, either in monoculture or in mixtures. N, P, or NP application can significantly improve biomass production of the two species in their mixtures. There was no obvious change trend in root/shoot ratio of B. ischaemum or L. davurica in different mixture proportions. Relative yield total (RYT) values ranged from 0.98 to 1.39. Aggressivity values of B. ischaemum to L. davurica were positive in all water regimes and fertilizations, implying that B. ischaemum was the dominant species. Relative competition intensity values of B. ischaemum (i.e., RCIB) were less than zero, while greater than zero for L. davurica (i.e., RCIL), indicating that the effects of intraspecific competition with L. davurica were stronger for B. ischaemum, and the opposite for L. davurica. WUE increased gradually as the proportion of B. ischaemum increased in mixtures, and a 10:2 B. ischaemum:L. davurica mixture proportion had significantly higher WUE. Results suggest that it is advantageous to grow the two species together to maximize biomass production and the recommended mixture ratio was 10:2 of B. ischaemum to L. davurica because it gave higher RYT and significantly higher WUE under conditions of water deficit.
Rating Scales as Predictors—The Old Question of Scale Level and Some Answers
Authors: Tutz Gerhard , Gertheiss Jan
Published: June 2013

Rating scales as predictors in regression models are typically treated as metrically scaled variables or, alternatively, are coded in dummy variables. The first approach implies a scale level that is not justified, the latter approach results in a large number of parameters to be estimated. Therefore, when rating scales are dummy-coded, applications are often restricted to the use of a few predictors. The penalization approach advocated here takes the scale level serious by using only the ordering of categories but is shown to work in the high dimensional case. We consider the proper modeling of rating scales as predictors and selection procedures by using penalization methods that are tailored to ordinal predictors. In addition to the selection of predictors, the clustering of categories is investigated. Existing methodology is extended to the wider class of generalized linear models. Moreover, higher order differences that allow shrinkage towards a polynomial as well as monotonicity constraints and alternative penalties are introduced. The proposed penalization approaches are illustrated by use of the Motivational States Questionnaire.
Synthesis of Bio‐based Polyurethane from Modified Prosopis juliflora Oil
Authors: Tathe Dipak S. , Jagtap Ramanand N.
Published: June 2013

Studies on the epoxidation of Prosopis juliflora seed oil were carried out to evaluate the optimum level of oxirane formation. On optimization of epoxidation of Prosopis juliflora oil (PJO), it was observed that at 60 °C and the mole ratio of double bond to the hydrogen peroxide to the acetic acid was 1:1.1:0.5 and at 2 wt% catalyst loading gave the maximum oxirane conversion. Further, epoxidized Prosopis juliflora oil (EPJO) was reacted with aminopropyltrimethoxysilane. Aminopropyltrimethoxysilanated Prosopis juliflora oil (ASPJO) was used as a polyol and was allowed to react with varying concentrations of isophorone diisocyanate resulting in polyurethane. The polyurethane films biodegradability was studied using phosphate buffer and proteinase K. The epoxidized oil was characterized by its epoxy value and FT‐IR spectroscopy. Similarly, ASPJO was characterized by its amine value, FT‐IR and 1H‐NMR spectroscopy. Whereas the polyurethane coating was characterized by gel content, FT‐IR spectroscopy, scanning electron microscopic analysis and also evaluated for its chemical resistance, optical and mechanical properties.
Influence of synovia constituents on tribological behaviors of articular cartilage
Authors: Murakami Teruo , Yarimitsu Seido , Nakashima Kazuhiro , Sawae Yoshinori , Sakai Nobuo
Published: June 2013

The extremely low friction and minimal wear in natural synovial joints appear to be established by effective lubrication mechanisms based on appropriate combination of articular cartilage and synovial fluid. The complex structure of cartilage composed of collagen and proteoglycan with high water content contributes to high load-carrying capacity as biphasic materials and the various constituents of synovial fluid play important roles in various lubrication mechanisms. However, the detailed differences in functions of the intact and damaged cartilage tissues, and the interaction or synergistic action of synovia constituents with articular cartilage have not yet been clarified. In this study, to examine the roles of synovia constituents and the importance of cartilage surface conditions, the changes in friction were observed in the reciprocating tests of intact and damaged articular cartilage specimens against glass plate lubricated with lubricants containing phospholipid, protein and/or hyaluronic acid as main constituents in synovial fluid. The effectiveness of lubricant constituents and the influence of cartilage surface conditions on friction are discussed. In addition, the protectiveness by synovia constituents for intact articular cartilage surfaces is evaluated.
Recent advances in gecko adhesion and friction mechanisms and development of gecko-inspired dry adhesive surfaces
Authors: Zhou Ming , Pesika Noshir , Zeng Hongbo , Tian Yu , Israelachvili Jacob
Published: June 2013

The remarkable ability of geckos to climb and run rapidly on walls and ceilings has recently received considerable interest from many researchers. Significant progress has been made in understanding the attachment and detachment mechanisms and the fabrication of articulated gecko-inspired adhesives and structured surfaces. This article reviews the direct experiments that have investigated the properties of gecko hierarchical structures, i.e., the feet, toes, setae, and spatulae, and the corresponding models to ascertain the mechanical principles involved. Included in this review are reports on gecko-inspired surfaces and structures with strong adhesion forces, high ratios of adhesion and friction forces, anisotropic hierarchical structures that give rise to directional adhesion and friction, and “intelligent” attachment and detachment motions.
Green tribology: Fundamentals and future development
Authors: Zhang Si-wei
Published: June 2013

As green tribology is a new field of tribology still in its infancy, understanding its fundamentals is essential for its further development. In this article, a brief historical retrospective on the emergence of green tribology is introduced first, and then the definition, objectives, and disciplinary features of green tribology are clarified. In particular, the technological connotations of green tribology are expounded comprehensively. Also, the developing directions of this new area are envisaged. These findings may contribute to laying the foundation of further advancement in green tribology.
Potential hydrodynamic origin of frictional transients in sliding mesothelial tissues
Authors: Loring Stephen H. , Butler James P.
Published: June 2013

Steady-state and transient variations in frictional force observed in tribological experiments of mesothelial tissues sliding in lubricant were analyzed with a mathematical model to test the hypothesis that such phenomena are manifestations of elastohydrodynamic lubrication and, importantly, do not require physical contact between the sliding surfaces. The model incorporates three phenomena characteristic of elastohydrodynamic lubrication: thinning of the liquid layer between sliding surfaces under a normal load (“squeeze-out”), thickening of the liquid layer due to hydrodynamic pumping, and smoothing of the elastic surfaces caused by hydrodynamic pressure gradients. Observations in soft mesothelial tissues sliding in lubricant showed variations in steady state friction with velocity, load, and lubricant viscosity. In non-steady sliding, the decay rate of frictional transients at the start of rotation varied with velocity, the amplitudes of these transients varied with the preceding periods without rotation, and frictional force varied during sinusoidal sliding. Model simulations were qualitatively similar to experimental results, supporting these mechanisms. Higher lubricant viscosity increased lubricating layer thickness and lowered friction at low speeds and increased friction at high speeds, supporting hydrodynamic pumping. We conclude that the frictional variations seen with sliding mesothelial tissues are consistent with elastohydrodynamic lubrication without contact between the sliding surfaces.
Damage due to rolling in total knee replacement—The influence of tractive force
Authors: Wimmer Markus A. , Birken Lars , Sellenschloh Kay , Schneider Erich
Published: June 2013

The femoral condyles of a knee prosthesis articulate with a combination of rolling and sliding on the tibial polyethylene plateau. Little is known about potential polyethylene damage due to rolling motion. Since rolling does not exclude the presence of tangential surface loads, this study sought to investigate the influence of tractive rolling on the wear of polyethylene. A “wheel-on-flat” apparatus, consisting of a metal wheel and a polyethylene flat, mimicked contact conditions present in total knee replacement. An increasingly tractive force under conditions of pure rolling was applied. It was found that under rolling kinematics a tangential surface load of up to 17% of the normal load could be transferred through the contact. Surface damage was dependent on the amount of tractive force and appeared more severe with higher forces. In the region of highest tractive force, wear features were identified that resembled perpendicular ridges on surfaces of retrieved tibial polyethylene devices. This suggests that tractive rolling may be a relevant wear mode in total knee replacement.
Skin tribology: Science friction?
Authors: Van Der Heide E. , Zeng X. , Masen M. A.
Published: June 2013

The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is frequently one of the interacting surfaces in relative motion. People seem to solve these problems related to skin friction based upon a trial-and-error strategy and based upon on our sense for touch. The question of course rises whether or not a trained tribologist would make different choices based upon a science based strategy? In other words: Is skin friction part of the larger knowledge base that has been generated during the last decades by tribology research groups and which could be referred to as Science Friction? This paper discusses the specific nature of tribological systems that include the human skin and argues that the living nature of skin limits the use of conventional methods. Skin tribology requires in vivo, subject and anatomical location specific test methods. Current predictive friction models can only partially be applied to predict in vivo skin friction. The reason for this is found in limited understanding of the contact mechanics at the asperity level of product-skin interactions. A recently developed model gives the building blocks for enhanced understanding of friction at the micro scale. Only largely simplified power law based equations are currently available as general engineering tools. Finally, the need for friction control is illustrated by elaborating on the role of skin friction on discomfort and comfort. Surface texturing and polymer brush coatings are promising directions as they provide way and means to tailor friction in sliding contacts without the need of major changes to the product.
Prophylactic catheter ablation for ventricular tachycardia reduces morbidity and mortality in patients with implantable cardioverter–defibrillator devices
Authors: Niwano Shinichi , Oikawa Jun , Fukaya Hidehira
Published: June 2013

Background

Although the use of implantable cardioverter–defibrillator/cardiac resynchronization therapy device with a defibrillator (ICD/CRT‐D) is the principal therapy for patients with life‐threatening ventricular tachyarrhythmias/ventricular fibrillation (VT/VF), prophylactic VT ablation may reduce arrhythmic episodes and mortality in patients with an ICD/CRT‐D. In this retrospective study, the prognoses among patient groups with different results of attempted VT ablation were compared.

Methods

The study population consisted of 151 consecutive patients with an ICD/CRT‐D and structural heart disease. The mean age was 64±9 years, and 63 of the 151 patients were women. Of the 151 patients, 117 cases underwent catheter ablation procedure for elimination of monomorphic VT. The 151 patients were divided into 3 groups based on the results of the ablation or whether ablation was attempted, i.e., success, failure, and not‐attempted groups (n=87, 30, and 34, respectively). The event rate of VT/VF and total mortality were compared among the 3 groups.

Results

During a follow‐up period of 31±22 months, VT/VF episodes and death occurred in 45 (30%) and 16 (11%) patients, respectively. When comparing the 3 groups, the rates of VT/VF episodes and death were significantly lower in the success group than in the failure and not‐attempted groups (16.1%, 46.7%, 50.0%, p=0.0001 and 6.9%, 20.0%, 11.8%, p=0.0213, respectively).

Conclusion

In patients with an ICD/CRT‐D implant for VT/VF, prophylactic ablation of monomorphic VT may reduce morbidity and mortality.
Interfacial waves and the dynamics of backflow in falling liquid films
Authors: Doro Emmanuel O. , Aidun Cyrus K.
Published: June 2013

By studying the dynamics of the streamwise pressure gradient at the wavefront of travelling interfacial waves, we investigate the formation and evolution of backflow regions for the sinusoidal and teardrop-shaped surface wave regimes of laminar falling liquid films. The magnitude of the wavefront streamwise pressure gradient grows as the flow inlet disturbance increases in amplitude and steepness. At large enough values, the adverse pressure gradient induces flow separation and subsequently backflow at the large-amplitude wavefront. The backflow region evolves from a closed circulation to an open vortex as the wave grows to saturation. The dynamics of the streamwise pressure gradient at the sinusoidal wavefront approaches a stable fixed point at saturation. Thus, the open vortex retains its structure as the wave continues downstream. The streamwise pressure gradient at the wavefront of the teardrop-shaped pulse evolves similarly to a time-periodic function with multiple minima/maxima. This phenomenon is a consequence of the interaction between the teardrop-shaped wave and newly formed preceding capillary waves. The nature of the teardrop pulse–capillary wave interaction is such that a decrease in magnitude of the streamwise pressure gradient at the teardrop-shaped wavefront is followed by an increase at the capillary wavefront and vice versa. The increased adverse pressure gradient at the capillary wavefront induces a second open vortex backflow, while the teardrop-shaped wavefront’s open vortex reverts to a closed circulation. This interaction between the waves continues as the teardrop pulse–capillary wavetrain travels downstream, leading to multiple capillary waves and backflow regions.
Low-Reynolds-number swimming in a capillary tube
Authors: Zhu L. , Lauga E. , Brandt L.
Published: June 2013

We use the boundary element method to study the low-Reynolds-number locomotion of a spherical model microorganism in a circular tube. The swimmer propels itself by tangential or normal surface motion in a tube whose radius is of the order of the swimmer size. Hydrodynamic interactions with the tube walls significantly affect the average swimming speed and power consumption of the model microorganism. In the case of swimming parallel to the tube axis, the locomotion speed is always reduced (respectively, increased) for swimmers with tangential (respectively, normal) deformation. In all cases, the rate of work necessary for swimming is increased by confinement. Swimmers with no force dipoles in the far field generally follow helical trajectories, solely induced by hydrodynamic interactions with the tube walls, and in qualitative agreement with recent experimental observations forParamecium. Swimmers of the puller type always display stable locomotion at a location which depends on the strength of their force dipoles: swimmers with weak dipoles (small$\alpha $) swim in the centre of the tube while those with strong dipoles (large$\alpha $) swim near the walls. In contrast, pusher swimmers and those employing normal deformation are unstable and end up crashing into the walls of the tube. Similar dynamics is observed for swimming into a curved tube. These results could be relevant for the future design of artificial microswimmers in confined geometries.
Voting Made Safe and Easy: The Impact of e-voting on Citizen Perceptions
Authors: Alvarez R. Michael , Levin Ines , Pomares Julia , Leiras Marcelo
Published: June 2013

Voting technologies frame the voting experience. Different ways of presenting information to voters, registering voter choices and counting ballots may change the voting experience and cause individuals to re-evaluate the legitimacy of the electoral process. Yet few field experiments have evaluated how voting technologies affect the voting experience. This article uses unique data from a recent e-voting field experiment in Salta, Argentina to study these questions. It employs propensity-score matching methods to measure the causal effect of replacing traditional voting technology with e-voting on the voting experience. The study's main finding is that while e-voters perceive the new technology as easier to use and more likely to register votes as intended—and support replacing traditional voting technologies with e-voting—the new technologies also raise some concerns about ballot secrecy.
Political Depolarization in German Public Opinion, 1980–2010
Authors: Munzert Simon , Bauer Paul C.
Published: June 2013

Little is known about political polarization in German public opinion. This article offers an issue-based perspective and explores trends of opinion polarization in Germany. Public opinion polarization is conceptualized and measured as alignment of attitudes. Data from the German General Social Survey (1980 to 2010) comprise attitudes towards manifold issues, which are classified into several dimensions. This study estimates multilevel models that reveal general and issue- as well as dimension-specific levels and trends in attitude alignment for both the whole German population and sub-groups. It finds that public opinion polarization has decreased over the last three decades in Germany. In particular, highly educated and more politically interested people have become less polarized over time. However, polarization seems to have increased in attitudes regarding gender issues. These findings provide interesting contrasts to existing research on the American public.
SOLUTIONS TO POLYNOMIAL CONGRUENCES IN WELL-SHAPED SETS
Authors: KERR BRYCE
Published: June 2013

We use a generalisation of Vinogradov’s mean value theorem of Parsell et al. [‘Near-optimal mean value estimates for multidimensional Weyl sums’, arXiv:1205.6331] and ideas of Schmidt [‘Irregularities of distribution. IX’, Acta Arith. 27 (1975), 385–396] to give nontrivial bounds for the number of solutions to polynomial congruences, when the solutions lie in a very general class of sets, including all convex sets.
Fair's Fair? Principles, Partisanship, and Perceptions of the Fairness of Campaign Rhetoric
Authors: Stevens Daniel , Allen Barbara , Sullivan John , Lawrence Eric
Published: June 2013

This article considers the role of principles in perceptions of what constitutes acceptable rhetoric in election campaigns. Previous research suggests that citizens use principles of what is an acceptable attack in campaigns when evaluating charges and countercharges, while acknowledging that under some circumstances citizens accept rhetoric that would seem to breach their principles. This research has not adequately considered how partisanship can affect a respondent's proclivity to call upon principles in assessing campaign rhetoric. This article draws on three original surveys to test competing models of the role of partisanship and finds robust results in support of a strong partisan bias. It concludes that it is not that citizens are resilient to violations of their principles, but that nearly the opposite is the case: citizens’ sensitivity to attacks on their preferred candidate leads them to take a very partial view of when to apply their principles faithfully to a judgment and when not to.
Nasolacrimal duct tumours in the era of endoscopic dacryocystorhinostomy: literature review
Authors: Tanweer F , Mahkamova K , Harkness P
Published: June 2013

Background:

Nasolacrimal duct tumours are rare and are often found inadvertently during dacryocystorhinostomy. Anecdotal case reports have been published, mostly in ophthalmology journals. Since the era of endoscopic dacryocystorhinostomy, such cases are more frequently encountered by ENT surgeons.

Method:

This paper reports a retrospective chart review of patients who underwent endoscopic dacryocystorhinostomy over the last 10 years in our dedicated epiphora clinic. It also provides a systematic literature review of nasolacrimal duct tumour cases published in English over the last 16 years.

Results:

Four of 525 endoscopic dacryocystorhinostomy procedures exposed a tumour (inverted papilloma, oncocytoma, lymphoma and solitary fibrous tumour). The literature review revealed 118 published case reports. Papilloma was the most frequently reported benign tumour and lymphoma was the most common malignant tumour.

Conclusion:

Since the advent of endoscopic dacryocystorhinostomy, tumours are being diagnosed relatively early when smaller in size. Because of the rarity of this condition, it is advisable that such cases are managed through a dedicated epiphora service framework.
Increased susceptibility of a triclabendazole (TCBZ)-resistant isolate of Fasciola hepatica to TCBZ following co-incubation in vitro with the P-glycoprotein inhibitor, R(+)-verapamil
Authors: MEANEY M. , SAVAGE J. , BRENNAN G. P. , HOEY E. , TRUDGETT A. , FAIRWEATHER I.
Published: June 2013

A study was carried out to investigate whether the action of triclabendazole sulphoxide (TCBZ.SO) against the liver fluke, Fasciola hepatica is altered by inhibition of P-glycoprotein (Pgp)-linked drug efflux pumps. The Oberon TCBZ-resistant and Cullompton TCBZ-susceptible fluke isolates were used for this in vitro study and the Pgp inhibitor selected was R(+)-verapamil [R(+)-VPL]. For experiments with the Oberon isolate, flukes were incubated for 24 h with either R(+)-VPL (1×10−4m) on its own, TCBZ.SO (15 μg mL−1) alone, a combination of R(+)-VPL (1×10−4m) plus TCBZ.SO (15 μg mL−1), TCBZ.SO (50 μg mL−1) on its own, or a combination of TCBZ.SO (50 μg mL−1) plus R(+)-VPL (1×10−4m). They were also incubated in TCBZ.SO (50 μg mL−1) alone or in combination with R(+)-VPL (1×10−4m) until they became inactive; and in TCBZ.SO (50 μg mL−1) alone for a time to match that of the combination inactivity time. Flukes from the Cullompton isolate were treated with either TCBZ.SO (50 μg mL−1) alone or in combination with R(+)-VPL (1×10−4m) until they became inactive, or with TCBZ.SO (50 μg mL−1) alone time-matched to the combination inactivity time. Morphological changes resulting from drug treatment and following Pgp inhibition were assessed by means of scanning electron microscopy. Incubation in R(+)-VPL alone had a minimal effect on either isolate. TCBZ.SO treatment had a relatively greater impact on the TCBZ-susceptible Cullompton isolate. When R(+)-VPL was combined with TCBZ.SO in the incubation medium, however, the surface disruption to both isolates was more severe than that seen after TCBZ.SO treatment alone; also, the time taken to reach inactivity was shorter. More significantly, though, the potentiation of drug activity was greater in the Oberon isolate; also, it was more distinct at the higher concentration of TCBZ.SO. So, the Oberon isolate appears to be particularly sensitive to efflux pump inhibition. The results of this study suggest that enhanced drug efflux in the Oberon isolate may be involved in the mechanism of resistance to TCBZ.
Leader–follower-based dynamic trajectory planning for multirobot formation
Authors: Liu Shuang , Sun Dong
Published: June 2013

The present paper presents a new approach to a leader–follower-based dynamic trajectory planning for multirobot formation. A near-optimal trajectory is generated for each robot in a decentralized manner. The main contributions of the current paper are the proposal of a new objective function that considers both collision avoidance and formation requirement for the trajectory generation, and an analytical solution of trajectory parameters in the trajectory optimization. Simulations and experiments on multirobots are performed to demonstrate the effectiveness of the proposed approach to the multirobot formation in a dynamic environment.
COLLABORATION IN HEALTH TECHNOLOGY ASSESSMENT (EUnetHTA JOINT ACTION, 2010–2012): FOUR CASE STUDIES
Authors: Huić Mirjana , Nachtnebel Anna , Zechmeister Ingrid , Pasternak Iris , Wild Claudia
Published: June 2013

Objectives: The aim of this study was to present the first four collaborative health technology assessment (HTA) processes on health technologies of different types and life cycles targeted toward diverse HTA users and facilitators, as well as the barriers of these collaborations.

Methods: Retrospective analysis, through four case studies, was performed on the first four collaboration experiences of agencies participating in the EUnetHTA Joint Action project (2010–12), comprising different types and life cycles of health technologies for a diverse target audience, and different types of collaboration. The methods used to initiate collaboration, partner contributions, the assessment methodology, report structure, time frame, and factors acting as possible barriers to and facilitators of this collaboration were described.

Results: Two ways were used to initiate collaboration in the first four collaborative HTA processes: active brokering of information, so-called “calls for collaboration,” and individual contact between agencies after identifying a topic common to two agencies in the Planned and Ongoing Projects database. Several success factors are recognized: predefined project management, high degree of commitment to the project; adherence to timelines; high relevance of technology; a common understanding of the methods applied and advanced experience in HTA; finally, acceptance of English-written reports by decision makers in non–English-speaking countries. Barriers like late identification of collaborative partners, nonacceptance of English language and different methodology of assessment should be overcome.

Conclusions: Timely and efficient, different collaborative HTA processes on relative efficacy/effectiveness and safety on different types and life cycles of health technologies, targeted toward diverse HTA users in Europe are possible. There are still barriers to overcome.
On a generalisation of Roth's theorem for arithmetic progressions and applications to sum-free subsets
Authors: DOUSSE JEHANNE
Published: June 2013

We prove a generalisation of Roth's theorem for arithmetic progressions to d-configurations, which are sets of the form {ni+nj+a}1 ≤ i ≤ j ≤ d with a, n1,. . .,nd ∈ $\mathbb{N}$, using Roth's original density increment strategy and Gowers uniformity norms. Then we use this generalisation to improve a result of Sudakov, Szemerédi and Vu about sum-free subsets [10] and prove that any set of n integers contains a sum-free subset of size at least logn(log(3)n)1/32772 − o(1).
Two types of case variation
Authors: Jónsson Jóhannes Gísli
Published: June 2013

Building on data from Icelandic, this article argues that there are two kinds of case variation, formal and semantic. The first type features lexical case as one of the variants whereas the second type involves structural vs. inherent case. The semantic effect found with the latter kind of variation follows from the semantic requirements associated with inherent case and these may cut across different uses of the same verb. It is also shown how the weak status of disappearing lexical case manifests itself in the grammar of Icelandic and Faroese.