bluuebunny/crossref_metadata_2025 huggingface dataset:
A Material Model for TRIP‐Steels and its Application to a CrMnNi Cast Alloy
Authors: Prüger Stefan , Kuna Meinhard , Wolf Steffen , Krüger Lutz
Published: July 2011

A material model is presented that accounts for strain rate dependent inelastic deformation and strain‐induced phase transformation in TRIP‐steels. Modifications for the kinetics equations of the strain‐induced phase transformation, introduced by Stringfellow, are proposed to overcome a drawback of Stringfellow's model. A parameter identification strategy that relies on Gauss‐Markov estimates is used to determine the model parameters from experimental data of a recently developed cast TRIP‐steel. Good agreement is observed between experimental results of the compression test and the corresponding finite element simulation employing the proposed model. This forms the basis for future applications of the material model in the design of composites and structures.
Interfacial Reactions in TRIP‐Steel/ZrO2 Composites
Authors: Franke P. , Ksyta M. , Seifert H.J.
Published: July 2011

The interfaces between stainless TRIP steel and three types of zirconia ceramics were investigated after sintering the samples for 48 h at 1400 °C. The samples were prepared by embedding compact pieces of ceramics into steel powder and densifying them with a spark plasma equipment. In all experiments the same steel was used but the zirconia ceramics was stabilised with CaO, MgO, or non‐stabilised, respectively. It was found that no reaction product was formed in the samples with non‐stabilised or CaO‐stabilised ceramics. At the interface of MgO‐stabilised zirconia and steel, a layer of forsterite, Mg2SiO4, was formed. The silicate layer resulted from the reaction of MgO which was dissolved in the zirconia with Si which was an impurity in the steel. In a thermodynamic analysis the reasons are explained which lead to the formation of a silicate in the samples with MgO‐stabilised zirconia. Accordingly, thermodynamic calculations are in accord with the absence of a reaction layer in the cases of the non‐stabilised and the CaO‐stabilised zirconia, even though the Gibbs energy of formation of calcium silicates is much higher than that of the corresponding magnesium silicates. The maximum impurity level for silicon in the given steel is calculated which avoids the formation of a silicate layer at the interface of the MgO‐stabilised ceramics.
Factors Predicting the Success of Extracorporeal Shock Wave Lithotripsy in the Treatment of Ureteric Calculi
Authors: Farrands R. , Turney B.W. , Kumar P.V.S.
Published: July 2011

Objective:

To evaluate the success of extracorporeal shock wave lithotripsy (ESWL) in the treatment of ureteric calculi and determine the factors which influence outcome. Patients and methods: A retrospective audit of patients with a single ureteric stone receiving ESWL was performed. Success was defined as complete stone clearance on post-treatment imaging. Patient demographics and stone characteristics were correlated to ESWL outcome. Results: 108 patients met the inclusion criteria for this study. The mean age of the patients was 52.5 years (range 24–89 years). 80% (86/108) of patients were male. Stone sizes varied from 4 to 19 mm (mean 7.92 mm). The overall ESWL success rate for ureteric stones was 79%. Treatment was more effective for smaller ( p = 0.003) and more located stones ( p = 0.035). Stone size correlated with number of treatments required ( p =0.005). A JJ stent in situ at the time of ESWL reduced the success rate ( p = 0.002). Conclusions: Stone size, site in the ureter, and the presence of a JJ stent were predictors of ESWL success. Our study from a District General Hospital in the UK demonstrates that ESWL may be used with high efficacy to treat ureteric stones.
‘TE NYƆGEYƐNG GBENGBENG!’ (‘WE ARE HOLDING THE UMBRELLA VERY TIGHT!’): EXPLAINING THE POPULARITY OF THE NDC IN THE UPPER WEST REGION OF GHANA
Authors: Bob-Milliar George M.
Published: July 2011

This article analyses the reasons why, since the beginning of the Fourth Republic in 1992, the Upper West Region (UWR) has become one of the strongholds of the National Democratic Congress (NDC) in northern Ghana. In all five general elections to date, the NDC has won more than half of the presidential vote and over 70 per cent of the parliamentary seats. The article explores the factors that explain the NDC's electoral dominance in the UWR. At the regional level the accepted argument has been that the NDC's predecessor extended developments to the area. However, if voting preferences are based on development considerations, why didn't loyalty shift to the NPP? I argue that political loyalty is generational and that the popularity of the NDC in the UWR can be understood through an appreciation of the recent history of the region. On 14 January 1983, PNDC Law 41 decreed the creation of the Upper West Region, carved out of what was then the Upper Region. I conclude that the political and socio-economic opportunities that came along with decentralization are historical memories of high value, which the NDC capitalizes on in its electioneering campaigns.
DESCRIBING URBAN ‘NO MAN'S LAND’ IN AFRICA
Authors: Guyer Jane I.
Published: July 2011

Cities as elusive, invisible, yet to come. ‘[T]he city is no-man's land’ (Grace Khunou, p. 240 in Mbembe and Nuttall). ‘Lagos is no man's land’ (heard in Lagos by the present writer, August 2010). A picture of a strangely empty and disrupted man-made landscape (William Kentridge, pp. 349–350 in Mbembe and Nuttall), balanced by a dense but also personless urban scene (by the same author, pp. 35–6 in the same text). … The slippage between conventional social scientific terms of runaway urbanization, the teeming human vitality of African cities, and the elusiveness of the titles, sayings and images of these three books, opens up the rich vein for research and writing into which these authors work their ways. Johannesburg. Kinshasa. Pikine (Dakar). Winterveld (a South African urban area outside Pretoria). Douala. Jeddah. The books reviewed here are based on detailed field research in six particular cities. They all juxtapose the categories of ‘metropolis’ and ‘modernity’ to the category of ‘Africa’, all positing the anomaly this move may represent in the categorical social scientific mind. The subtitles immediately indicate a different starting point from the analytics of population, geography and governance. With an approach through ‘tales’ (De Boeck and Plissart) and ‘reading the city’ (Mbembe and Nuttall), the authors indicate an alternative intellectual reach. They start from visual imagery, the language arts and the social mediations through which the lives lived in urban ‘modern’ Africa are expressed, communicated, understood, configured and conserved. Their aims evoked in my mind the modern art – rather than the analytics – of other cities. So here we have ‘circulation’ and vehicles as symbols and sounds without too much attention to traffic (the Lagos ‘go slow’; the accidents); ‘bodies’ without much attention to food or toilet needs or aging; ‘authority’ evaded or permeating rather than personified in mayors, town councils and multitudes of other officials and employees. In the ether of the invisible, what circulates are symbols and expressions; what emanates from bodies is sexual tension, aesthetic sensibility and physical vulnerability (‘bodies in danger’, De Boeck and Plissart, p. 117); what bears down oppressively is constraint and neglect of all kinds. In brief, what strikes the perceptive mind is precisely what bursts out of the conventional forms and has not yet taken a newly conventionalized shape. Through this orientation, all three books bring the humanities and artistic sensibilities to the question of the spirits, souls, inspirations, dangers, images and memories that inhabit the crowded spaces between buildings and people, insects and people, people and people.
PEACEFUL MEMORIES: REMEMBERING AND FORGETTING POLITICAL VIOLENCE IN KANGWANE, SOUTH AFRICA
Authors: Ally Shireen
Published: July 2011

Despite its manifest, if largely undocumented, histories of menacing violence and perilous politics, the thrust of popular memory in the former apartheid bantustan of KaNgwane insists that it was a peaceful, even apolitical, place. In a contemporary South African memorial culture that idealizes memories of victimization by (and resistance to) apartheid and its political violence, why would some in KaNgwane persistently narrate the past through tropes of peaceful order and disavowals of the political? Are these mnemonic effacements in KaNgwane best conceived of as forms of forgetting? This article challenges such a proposition. First, it recovers the hitherto unrecognized politics and violence in KaNgwane, in part (and paradoxically) out of the very same narratives that deny such histories. Second, it explores the dialectical co-implication of remembering and forgetting, and of memory and history, in KaNgwane's supposed anamnesis. And third, it proposes that the occlusions and assurances of memory in KaNgwane are structured by a localized semiotics in which politics is retrospectively signified by order and restraint, and negated by disorder and revolt. In this ‘memory work’, KaNgwane's past is anaesthetized of violence, and heroism is recovered not from rehearsals of victimization and resistance, but from memories of pacified civility instead.
Density of larval and adult forms of the burrowing crustaceansLepidophthalmus siriboia(Callianassidae) andUpogebia vasquezi(Upogebiidae) in an Amazon estuary, northern Brazil
Authors: de Oliveira Danielly Brito , Silva Dalila Costa , Martinelli Jussara Moretto
Published: July 2011

Although thalassinidean shrimps exert considerable influence over the structure of benthic communities no ecological studies have been conducted on the larvae and adults ofLepidophthalmus siriboiaandUpogebia vasqueziin the equatorial region. The aim of the present study was to identify the reproductive period of these species in an Amazonian estuary. Monthly collections were performed in the estuary of the Marapanim River (northern coast of Brazil) over the course of one year (August 2006 to July 2007) and adults were obtained from bare sandy substrate and between boulders in the intertidal zone of the estuary at four sites. Thalassinidean larvae were also sorted from plankton samples (200 μm mesh) collected monthly at six sites. Larvae of the speciesCallichirus major, Lepidophthalmus siriboiaandUpogebia vasqueziwere collected, whereas adults of only the latter two species were found.Upogebia vasqueziwas the most abundant species. There was no correlation between larval density and abiotic factors (water temperature, salinity and pH); however, the density ofU. vasqueziadults was negatively correlated with salinity in the burrows.Lepidophthalmus siriboiaandU. vasquezireproduce throughout the year in the Marapanim River estuary, with peaks of greater intensity in some reproductive periods of the year, mainly correlated with changes in salinity.
Factors controlling juvenile growth and population structure of the starfishAsterias rubensin intertidal habitats: field and experimental approaches
Authors: Guillou Monique , Joly-Turquin Guillemette , Leyzour Sandra , Pernet Philippe , Dubois Philippe
Published: July 2011

The dynamics of intertidal populations of the starfishAsterias rubens, living in contrasted habitats and over a broad geographical range, were studied from March 2000 to November 2002 using modal analysis. As only 1 juvenile (first year after recruitment) and 1 adult (subsequent years) modes could be distinguished; only juvenile growth was quantified. Concomitantly, experiments were carried out to test several factors assumed to influence juvenile growth: food quantity and quality, emersion, salinity variations and temperature. Three different juvenile growth patterns were evidenced: (1) a fast and protracted growth linked to high food availability and lack of disturbance; (2) a winter cessation of growth likely due to a seasonal increase of emersion-related stress and salinity variations; and (3) disrupted juvenile dynamics, which was encountered in 2 populations. In the first one, estuarine salinity conditions limited growth and, combined with food depletion, led to the extinction of the population. In the second one, wave action confined most of the population to a restricted area with low food levels. In the third scenario, intraspecific competition for food was probably at the source of an unusual growth pattern in which most juveniles did not grow while a small proportion achieved a medium growth rate.
Identification and biochemical characterization of two novel peroxiredoxins in a liver fluke,Clonorchis sinensis
Authors: BAE Y.-A. , KIM S.-H. , LEE E.-G. , SOHN W.-M. , KONG Y.
Published: July 2011

We identified 2 novel genes encoding different 2-Cys peroxiredoxins (PRxs), designated CsPRx2 and CsPRx3, inClonorchis sinensis, which invades the human hepatobiliary tracts. TheCsPRx2gene expression was temporally increased along with the parasite's development and its protein product was detected in almost all parts of adult worms including subtegument, as well as excretory-secretory products. Conversely,CsPRx3expression was temporally maintained at a basal level and largely restricted within interior parts of various tissues/organs. The recombinant forms of CsPRx proteins exhibited reducing activity against various hydroperoxides in the presence of either thioredoxin or glutathione (GSH) as a reducing equivalent, although they preferred H2O2and GSH as a catalytic substrate and electron donor, respectively. A steady-state kinetic study demonstrated that the CsPRx proteins followed a saturable, Michaelis-Menten-type equation with the catalytic efficiencies (kcat/Km) ranging from 103to 104M−1s−1, somewhat lower than those for other PRxs studied (104–105M−1s−1). The expression patterns and histological distributions specific to CsPRx2 and CsPRx3 might suggest different physiological functions of the antioxidant enzymes in protecting the worms against oxidative damage.
The Prudent Dissident: Unheroic Resistance in Sophocles'Antigone
Authors: Kirkpatrick Jennet
Published: July 2011

Most contemporary political theorists who have interpreted Sophocles'Antigonehave focused on the fearsome clash between Antigone and Creon. The relationship between Antigone and her weaker, more cautious sister Ismene has not garnered similar attention. This essay addresses this gap by revisiting the tantalizing possibility that Ismene played a more significant role in resisting Creon than has often been assumed. The essay shifts the analysis ofAntigone, first, by illuminating the complex and fraught relationship between two women and emphasizing the political and legal challenges that they face together as women. Second, the essay shifts focus from vertical power relations—that is, between the individual and government—to horizontal power relations between disempowered outsiders. On this reading,Antigonereveals less about the downfall of a character than it does about the political power of the weak and disadvantaged.
Kant on the Role of the Retributive Outlook in Moral and Political Life
Authors: Shuster Arthur
Published: July 2011

Kant is regarded as one of the staunchest advocates of retributive punishment in the modern tradition. This essay makes the case that a careful reexamination of Kant's account of punishment is necessary, especially in light of liberalism's characteristic inability to give the powerful moral appeal of retribution its due. Kant attempted to provide a clear analysis of what we mean when we say that morality demands that punishment be “proportional” to the crime. According to Kant, punishment's retributive aspect—as distinguished from its deterrent or restorative effects—is primarily concerned with redeeming (negative) moral worth. This paper attempts to unpack this claim by examining Kant's discussions of judicial punishment, the conscience, and divine punishment, respectively. It concludes that as a result of serious unresolved difficulties in his arguments for retribution, Kant manages only to deepen the question of the morality of retribution rather than to give it a decisive answer.
Evaluation of cowpea germplasm lines for protein and mineral concentrations in grains
Authors: Boukar Ousmane , Massawe Festo , Muranaka Satoru , Franco Jorge , Maziya-Dixon Bussie , Singh Bir , Fatokun Christian
Published: July 2011

Cowpea, an indigenous crop to sub-Saharan Africa, is found mainly in the dry savanna regions along with cereals such as millets and sorghum. Cowpea is grown primarily for human consumption of the grains, which are rich in protein, carbohydrates and contain some minerals. The development and deployment of cowpea varieties with higher nutritional value will be of immense benefit to consumers. As a first step in the enhancement of mineral content in cowpea grains, several germplasm lines (1541) of different origins and obtained from the genetic resources unit at IITA were sown in the experimental field in Minjibir, Kano State, Nigeria. The grains were analysed for protein and nine mineral contents. However, in this study, we shall report data on crude protein, Fe, Zn, Ca, Mg, K and P. The data generated from the chemical analysis were subjected to the ‘mixture of normal distributions’ clustering method, which distributed the cowpea lines into nine groups. Groups G7 and G9 contained 174 genotypes and these were characterized by high mineral concentrations. The mean nutritional content values for group G9 were 24.7% for protein, and 58.9, 41.5, 1107, 2132, 15,282 and 5664 mg/kg for Fe, Zn, Ca, Mg, K and P, respectively. On the other hand, the 363 lines making up groups G2, G3 and G6 showed low amounts of nutrients in their grains. Some of the lines in G7 and G9 would be good as parents to use in breeding programmes that aimed at developing nutrient-dense cowpea varieties.
Soil fertility and the yield response to the System of Rice Intensification
Authors: Turmel Marie-Soleil , Turner Benjamin L. , Whalen Joann K.
Published: July 2011

The System of Rice Intensification (SRI) is a low-input rice (Oryza sativa L.) production system that differs from conventional systems in several ways: seedlings are transplanted earlier and are more widely spaced, organic fertilizer is often used in addition to mineral fertilizer, and soils are irrigated intermittently rather than flooded for long periods. The yield benefits of SRI compared to conventional systems can be substantial, and yet are regionally variable and have been the subject of considerable debate, due partly to a lack of mechanistic understanding. Here we show that soil properties may in part explain the variability in yield response to SRI. A meta-analysis of data from 72 field studies where SRI was compared with conventional systems indicates that yields increased significantly (P<0.0001) when SRI was implemented on highly weathered infertile soils rich in iron and aluminum oxides (Acrisols and Ferralsols), but there was no difference in yield between SRI and conventional systems in more fertile favorable soils for rice production (Gleysols, Luvisols and Fluvisols). The yield difference between SRI and conventional rice production therefore appears to be related in part to soil properties linked to weathering. This should help resolve the debate about the value of SRI and allow research to be targeted toward understanding the biological and chemical processes in soils under SRI management.
A capacity assessment of New England's large animal slaughter facilities as relative to meat production for the regional food system
Authors: Lewis Chelsea Bardot , Peters Christian J.
Published: July 2011

Demand for locally and regionally produced meat has stimulated increased interest in livestock production among New England farmers. The region's livestock producers lament lack of access to slaughter and processing infrastructure. However, there is very little research on New England's slaughter industry to document this perceived problem. For this reason, we tested the hypothesis that a shortage of slaughter and processing infrastructure constrains the production of livestock for meat in New England. The region's large animal slaughter facility owners and managers were surveyed to determine current slaughter and processing capacity and identify challenges facilities face in meeting increased producer demand. The estimates of current capacity were then compared to USDA data on livestock slaughter and large animal marketings. The region's existing abattoirs could slaughter 63–84% of all animals marketed, but could process only 29–43%. New England's infrastructure for slaughter operated at only 38% of total physical capacity in 2009, while on-site processing infrastructure operated at 66% of total physical capacity (78% if only on-site inspected capacity is considered). Moreover, surveys with facility operators showed that the primary constraints faced by existing slaughterhouses are a shortage of skilled labor and the seasonality of the livestock industry, with periods of very high demand for slaughter in the fall and very low demand in the spring and early summer. Additional infrastructure, particularly for processing, would be needed were regional livestock production to increase. However, simply increasing physical capacity will not address the issues of labor availability and demand seasonality expressed by slaughter facility owners.
Study Of Phenothiazine On p53 Core Domain Mutant Y220C: Finding The Anti-tumor Activity Of Phenothiazine
Authors: Naqvi Asif Husain , Sheth Hardik , Kumar Vijay , H S Suchindran , Gupta Vivek
Published: July 2011

The tumor suppressor protein p53 is a transcription factor that plays a key role in the prevention of cancer development. The p53 cancer mutation Y220C induces formation of a cavity on the protein's surface that can accommodate stabilizing small molecules. We have attempted with the help of virtual screening and molecular docking approach using Lamarckian Genetic Algorithm to elucidate the extent of specificity of p53 cancer mutation Y220C towards different class of Phenothiazines (an anti-cancer agent).The 393 residue p53 tumor suppressor protein exists in a dynamic equilibrium to form homotetramers. Each chain comprises several functional domains. The N terminal part of the protein consists of the trans-activation domain (residues 1–63) followed by a proline rich region (64– 92). The central (core) domain (p53 core domain) is responsible for binding. The C terminal part of p53 contains the tetramerization domain (residues 326–355) and the negative regulatory domain at the extreme C terminus (363–393), which contains phosphorylation and acetylation sites and regulates the DNA binding activity of p53.The docking result of the study of 2,000 Phenothiazines demonstrated that the binding energies were in the range of -10.54 kcal/mol to -1.14 kcal/mol, with 8 molecules showing hydrogen bonds with the active site residues (Lys 164). All the selected 2000 inhibitors were selected on the basis of the structural specificity to the enzyme towards its substrate and inhibitors. Our research provides a blueprint for the design of more potent and specific drugs that rescue p53-Y220C.
Retention in the Golgi apparatus and expression on the cell surface of Cfr/Esl-1/Glg-1/MG-160 are regulated by two distinct mechanisms
Authors: Miyaoka Yuichiro , Kato Hidenori , Ebato Kazuki , Saito Shigeru , Miyata Naoko , Imamura Toru , Miyajima Atsushi
Published: July 2011

Cfr (cysteine-rich fibroblast growth factor receptor) is an Fgf (fibroblast growth factor)-binding protein without a tyrosine kinase. We have shown previously that Cfr is involved in Fgf18 signalling via Fgf receptor 3c. However, as Cfr is also known as Glg (Golgi apparatus protein)-1 or MG-160 and occurs in the Golgi apparatus, it remains unknown how the distribution of Cfr is regulated. In the present study, we performed a mutagenic analysis of Cfr to show that two distinct regions contribute to its distribution and stability. First, the C-terminal region retains Cfr in the Golgi apparatus. Secondly, the Cfr repeats in the extracellular juxtamembrane region destabilizes Cfr passed through the Golgi apparatus. This destabilization does not depend on the cleavage and secretion of the extracellular domain of Cfr. Furthermore, we found that Cfr with a GPI (glycosylphosphatidylinositol) anchor was predominantly expressed on the cell surface in Ba/F3 cells and affected Fgf18 signalling in a similar manner to the full-length Cfr, indicating that the interaction of Cfr with Fgfs on the cell surface is important for its function in Fgf signalling. These results suggest that the expression of Cfr in the Golgi apparatus and on the plasma membrane is finely tuned through two distinct mechanisms for exhibiting different functions.
Mutants of protein kinase A that mimic the ATP-binding site of Aurora kinase
Authors: Pflug Alexander , de Oliveira Taianá Maia , Bossemeyer Dirk , Engh Richard A.
Published: July 2011

We describe in the present paper mutations of the catalytic subunit α of PKA (protein kinase A) that introduce amino acid side chains into the ATP-binding site and progressively transform the pocket to mimic that of Aurora protein kinases. The resultant PKA variants are enzymatically active and exhibit high affinity for ATP site inhibitors that are specific for Aurora kinases. These features make the Aurora-chimaeric PKA a valuable tool for structure-based drug discovery tasks. Analysis of crystal structures of the chimaera reveal the roles for individual amino acid residues in the binding of a variety of inhibitors, offering key insights into selectivity mechanisms. Furthermore, the high affinity for Aurora kinase-specific inhibitors, combined with the favourable crystallizability properties of PKA, allow rapid determination of inhibitor complex structures at an atomic resolution. We demonstrate the utility of the Aurora-chimaeric PKA by measuring binding kinetics for three Aurora kinase-specific inhibitors, and present the X-ray structures of the chimaeric enzyme in complex with VX-680 (MK-0457) and JNJ-7706621 [Aurora kinase/CDK (cyclin-dependent kinase) inhibitor].
Matrix assisted pulsed laser deposition of melanin thin films
Authors: Bloisi F. , Pezzella A. , Barra M. , Chiarella F. , Cassinese A. , Vicari L.
Published: July 2011

Melanins constitute a very important class of organic pigments, recently emerging as a potential material for a new generation of bioinspired biocompatible electrically active devices. In this paper, we report about the deposition of synthetic melanin films starting from aqueous suspensions by matrix assisted pulsed laser evaporation (MAPLE). In particular, we demonstrate that it is possible to deposit melanin films by MAPLE even if melanin (a) is not soluble in water and (b) absorbs light from UV to IR. AFM images reveal that the film surface features are highly depending on the deposition parameters. UV-VIS and FTIR spectra show both the optical properties and the molecular structure typical of melanins are preserved.
Evolution of cell resistance, threshold voltage and crystallization temperature during cycling of line-cell phase-change random access memory
Authors: Oosthoek J. L. M. , Attenborough K. , Hurkx G. A. M. , Jedema F. J. , Gravesteijn D. J. , Kooi B. J.
Published: July 2011

Doped SbTe phase change (PRAM) line cells produced by e-beam lithography were cycled 100 million times. During cell cycling the evolution of many cell properties were monitored, in particular the crystalline and amorphous resistance, amorphous resistance drift exponent, time-dependent threshold voltage, threshold voltage as a function of RESET pulse height, crystallization temperature, and activation energy of crystal growth. The power of the present approach is that all these properties were measured simultaneously during the life of single cells. The evolution of the cell properties can be summarized by (i) an initialization phase characterized by settle-in effect of the material surrounding the programmable region, (ii) a usable life phase where initially the cell properties remain fairly constant until after ∼5 × 105 cycles decomposition of the programmed region caused degradation of the cell properties, and (iii) finally an end of life phase where the cell is stuck in the SET state after typically 108 cycles. Although generally the threshold voltage is directly related to the amorphous resistance it was found that during cycling this relation is not constant but evolved as well. Instead, the crystallization temperature could be linked to the threshold voltage throughout the complete life cycle of the cell which could lead to new insights to the nature of the threshold event.
Comment on “Photonic bands in two-dimensional microplasma array. I. Theoretical derivation of band structures of electromagnetic waves” [J. Appl. Phys. 101, 073304 (2007)]
Authors: Zhang Hai-feng , Liu Shao-bin , Kong Xiang-kun , Zhou Liang , Li Chun-zao , Bian Bo-rui
Published: July 2011

Recently, theoretical derivation of band structures of electromagnetic waves in two-dimensional microplasma array has been induced by Osamu Sakai et al. [J. Appl. Phys. 101, 073304 (2007)] using a modified plane wave expansion (PWE) method and a frequency-dependent finite difference time–domain (FDTD) method. This report reveals band diagrams with the effects of plasma electron collision frequency, especially focuses on the TE wave by nonmagnetized plasma. Although the band diagrams of TE wave and formulas of calculation look correct at first glance, there are some mistakes in the report which are unfortunately ignored by the authors. The correct formulas of the modified PWE method and FDTD method will be proposed.
Analysis of a static undulation on the surface of a thin dielectric liquid layer formed by dielectrophoresis forces
Authors: Brown Carl V. , McHale Glen , Mottram Nigel J.
Published: July 2011

A layer of insulating liquid of dielectric constant ɛOil and average thickness h− coats a flat surface at y = 0 at which a one-dimensional sinusoidal potential V(x,0)=VOcos(πx/p) is applied. Dielectrophoresis forces create a static undulation (or “wrinkle”) distortion h(x) of period p at the liquid/air interface. Analytical expressions have been derived for the electrostatic energy and the interfacial energy associated with the surface undulation when h(x)=h−-(1/2)Acos(2πx/p) yielding a scaling relationship for A as a function of h−, p, VO, ɛOil and the surface tension. The analysis is valid as A/p → 0, and in this limit convergence with numerical simulation of the system is shown.
Mapping the spatial overlap of excitons in a photosynthetic complex via coherent nonlinear frequency generation
Authors: Dawlaty Jahan M. , Bennett Doran I. G. , Huxter Vanessa M. , Fleming Graham R.
Published: July 2011

We experimentally demonstrate a nonlinear spectroscopic method that is sensitive to exciton-exciton interactions in a Frenkel exciton system. Spatial overlap of one-exciton wavefunctions leads to coupling between them, resulting in two-exciton eigenstates that have the character of many single-exciton pairs. The mixed character of the two-exciton wavefunctions gives rise to a four-wave-mixing nonlinear frequency generation signal. When only part of the linear excitation spectrum of the complex is excited with three spectrally tailored pulses with separate spatial directions, a frequency-shifted third-order nonlinear signal emerges in the phase-matched direction. We employ the nonlinear response function formalism to show that the emergence of the signal is mediated by and carries information about the two-exciton eigenstates of the system. We report experimental results for nonlinear frequency generation in the Fenna-Matthews-Olson (FMO) photosynthetic pigment-protein complex. Our theoretical analysis of the signal from FMO confirms that the emergence of the frequency-shifted signal is due to the interaction of spatially overlapped excitons. In this method, the signal intensity is directly measured in the frequency domain and does not require scanning of pulse delays or signal phase retrieval. The wavefunctions of the two-exciton states contain information about the spatial overlap of excitons and can be helpful in identifying coupling strengths and relaxation pathways. We propose this method as a facile experimental means of studying exciton correlations in systems with complicated electronic structures.
Generation of small mono-disperse bubbles in axisymmetric T-junction: The role of swirl
Authors: Herrada Miguel A. , Gañán-Calvo Alfonso M. , López-Herrera José M.
Published: July 2011

The dynamics of micro-bubble formation in an axisymmetric T-junction for a gas-liquid system is analyzed. The approach adopted involves the creation of a tapering gas-liquid meniscus from which a steady gas ligament issues by the introduction of a coaxial swirl in the liquid stream. A simple and easy geometry (an axisymmetric T-junction) suffices to introduce the swirl and to stabilize the meniscus, leading to the formation of small monodisperse bubbles. Full three-dimensional simulations (3D) have also been conducted to show that, even when the liquid injection is not perfectly axisymmetric, the bubbles generated under conditions of some focusing swirl are distinctively smaller than bubbles created in the absence of swirl. In such cases, the bubbles, produced at the trail of the vortex axis, become a serendipitous tool to visualize the non-axisymmetrical behavior of the vortex core, as shown by the simulations.
High-k InGaAs metal-oxide-semiconductor field-effect-transistors with various barrier layer materials
Authors: Xue Fei , Zhao Han , Chen Yen-Ting , Wang Yanzhen , Zhou Fei , Lee Jack C.
Published: July 2011

Improved device performance of InGaAs channel metal-oxide-semiconductor field-effect-transistors (MOSFETs) has been achieved by utilizing InP and InAlAs barrier layer. In0.7Ga0.3As buried-channel MOSFETs with various InP barrier thicknesses and InP/InAlAs double barrier have been fabricated and compared in terms of performances parameters such as drive current, transconductance, subthreshold swing (SS), and effective mobility. Devices with 1 nm InP barrier exhibits 59% increase in drive current and 65% increase in peak effective channel mobility compared to devices without barrier layer. With thicker barrier, devices show higher drive current and higher mobility. Devices with InP/InAlAs double barrier exhibit the highest effective channel mobility.
Femtosecond electron deflectometry for measuring transient fields generated by laser-accelerated fast electrons
Authors: Inoue Shunsuke , Tokita Shigeki , Otani Kazuto , Hashida Masaki , Sakabe Shuji
Published: July 2011

The temporal evolution of the electric field generated near the surface of a solid target by a femtosecond laser pulse with intensity of 1 × 1016 W/cm2 has been investigated by electron deflectometry; in this technique, ultrashort electron pulses generated by intense femtosecond laser pulses are used as probes. We found that electric field of the order of 108 V/m along the target surface was generated and decayed within 400 fs. The results of this study demonstrate the potential of electron deflectometry for measuring ultrafast phenomena in the femtosecond time domain.
Electronic properties of metal-arene functionalized graphene
Authors: Plachinda Paul , Evans David R. , Solanki Raj
Published: July 2011

We have employed first-principles density-functional calculations to study the electronic characteristics of covalently functionalized graphene by metal-bis-arene chemistry. It is shown that functionalization with M-bis-arene (M = Ti, V, Cr, Mn, Fe) molecules leads to an opening in the bandgap of graphene (up to 0.81 eV for the Cr derivative), and as a result, transforms it from a semimetal to a semiconductor. The bandgap induced by attachment of a metal atom topped by a benzene ring is attributed to modification of π-conjugation and depends on the concentration of functionalizing molecules. This approach offers a means of tailoring the band structure of graphene and potentially its applications for future electronic devices.
Surface energy density of metal nanostructures by Thomas-Fermi model
Authors: Soon Lai Weng , Chiu Cheng-Hsin
Published: July 2011

This letter examines the surface energy density of metal nanostructures with different morphologies by taking into account the effects of the electrostatic screening on the systems. The results show that the surface energy density is higher on concave nanostructures than on convex ones. The finding implies voids are more effective for the physisorption process than particles and wires.
Inductively coupled plasma grown semiconductor films for low cost solar cells with improved light-soaking stability
Authors: Shen Chang-Hong , Shieh Jia-Min , Huang Jung Y. , Kuo Hao-Chung , Hsu Chih-Wei , Dai Bau-Tong , Lee Ching-Ting , Pan Ci-Ling , Yang Fu-Liang
Published: July 2011

We investigate the performance of a single-junction amorphous Si (a-Si) solar cell fabricated with inductively coupled plasma (ICP) deposition technique. The high-density plasma resulting from high dissociation capacity of ICP enables good-quality hydrogenated Si films to be synthesized at low temperatures. High-density ICP also promotes the diffusion of reactive radicals on substrates and forms a-Si:H films with low defect density (∼3 × 1015 cm−3). We demonstrate single-junction a-Si solar cells with a conversion efficiency of 9.6% and improved light-soaking stability. This low thermal-budget thin-film technique could open up the feasibility of efficient thin film solar cells on flexible substrates.
Ultra-smooth microcylindrical resonators fabricated from the silicon optical fiber platform
Authors: Vukovic Natasha , Healy Noel , Horak Peter , Sparks Justin R. , Sazio Pier J. A. , Badding John V. , Peacock Anna C.
Published: July 2011

High quality hydrogenated amorphous silicon microcylindrical resonators are fabricated using the recently developed semiconductor optical fiber platform. The resonators are shown to have ultra-smooth surfaces that minimize the effects of scattering losses and exhibit localized whispering gallery modes with loaded quality factors of up to ∼2.8 × 104. Coupled mode theory indicates that the system quality factor is limited by both the bulk material loss of the resonator and the tapered fiber coupling scheme. The large extinction ratios and thermal nonlinearities measured in these microcylindrical resonators suggest that they should find application for low-power all-optical processing.
On the validity of the Navier-Stokes equations for nanoscale liquid flows: The role of channel size
Authors: Liu Chong , Li Zhigang
Published: July 2011

In this work, we investigate the validity of the Navier-Stokes (NS) equations for nanoscale liquid flows through molecular dynamics simulations. We focus on the role of channel size by considering the fluid-wall interaction. Liquid flows between two planar parallel walls driven by an external force with channel size ranging from 2 to 80 nm are studied. The volumetric flux is computed and the dependence of the volumetric flux on the channel size is explained both qualitatively and quantitatively. It is found that the flow is sensitive to the fluid-wall binding energy and the classical fluid mechanics falls apart in small nanochannels. However, the wall effects become insignificant and the NS equations are valid when the channel size is larger than about 150 molecular diameters (∼ 50 nm).
VEGF is essential for hypoxia-inducible factor-mediated neovascularization but dispensable for endothelial sprouting
Authors: Oladipupo Sunday , Hu Song , Kovalski Joanna , Yao Junjie , Santeford Andrea , Sohn Rebecca E. , Shohet Ralph , Maslov Konstantin , Wang Lihong V. , Arbeit Jeffrey M.
Published: July 2011

Although our understanding of the molecular regulation of adult neovascularization has advanced tremendously, vascular-targeted therapies for tissue ischemia remain suboptimal. The master regulatory transcription factors of the hypoxia-inducible factor (HIF) family are attractive therapeutic targets because they coordinately up-regulate multiple genes controlling neovascularization. Here, we used an inducible model of epithelial HIF-1 activation, the TetON-HIF-1 mouse, to test the requirement for VEGF in HIF-1 mediated neovascularization. TetON-HIF-1, K14-Cre, and VEGF
flox/flox
alleles were combined to create TetON-HIF-1:VEGF
Δ
mice to activate HIF-1 and its target genes in adult basal keratinocytes in the absence of concomitant VEGF. HIF-1 induction failed to produce neovascularization in TetON-HIF-1:VEGF
Δ
mice despite robust up-regulation of multiple proangiogenic HIF targets, including PlGF, adrenomedullin, angiogenin, and PAI-1. In contrast, endothelial sprouting was preserved, enhanced, and more persistent, consistent with marked reduction in Dll4-Notch-1 signaling. Optical-resolution photoacoustic microscopy, which provides noninvasive, label-free, high resolution, and wide-field vascular imaging, revealed the absence of both capillary expansion and arteriovenous remodeling in serially imaged individual TetON-HIF-1:VEGF
Δ
mice. Impaired TetON-HIF-1:VEGF
Δ
neovascularization could be partially rescued by 12-
O
-tetradecanoylphorbol-13-acetate skin treatment. These data suggest that therapeutic angiogenesis for ischemic cardiovascular disease may require treatment with both HIF-1 and VEGF.
Tapping natural reservoirs of homing endonucleases for targeted gene modification
Authors: Takeuchi Ryo , Lambert Abigail R. , Mak Amanda Nga-Sze , Jacoby Kyle , Dickson Russell J. , Gloor Gregory B. , Scharenberg Andrew M. , Edgell David R. , Stoddard Barry L.
Published: July 2011

Homing endonucleases mobilize their own genes by generating double-strand breaks at individual target sites within potential host DNA. Because of their high specificity, these proteins are used for “genome editing” in higher eukaryotes. However, alteration of homing endonuclease specificity is quite challenging. Here we describe the identification and phylogenetic analysis of over 200 naturally occurring LAGLIDADG homing endonucleases (LHEs). Biochemical and structural characterization of endonucleases from one clade within the phylogenetic tree demonstrates strong conservation of protein structure contrasted against highly diverged DNA target sites and indicates that a significant fraction of these proteins are sufficiently stable and active to serve as engineering scaffolds. This information was exploited to create a targeting enzyme to disrupt the endogenous monoamine oxidase B gene in human cells. The ubiquitous presence and diversity of LHEs described in this study may facilitate the creation of many tailored nucleases for genome editing.
3D effects on RWM physics in RFX-mod
Authors: Baruzzo M. , Bolzonella T. , Guo S.C. , Liu Y.Q. , Marchiori G. , Paccagnella R. , Soppelsa A. , Villone F. , Wang Z.R.
Published: July 2011

In this paper insights into the behaviour of resistive wall modes (RWMs) in the RFX-mod reversed field pinch device are given, with a focus on 3D issues in the characterization of the m spectrum of the mode and on the study of multi-harmonic coupling.

In the first part of the paper the interaction between multiple unstable RWMs is studied and the presence of a coupling between different poloidal components of the most unstable RWM is demonstrated, taking advantage of the flexibility of the RFX-mod control system.

In the second part of the work, the dependence of the growth rates of RWMs on a complete set of plasma parameters is studied in order to create a complete and homogeneous database, which permits a careful validation of stability codes.

Finally, the experimental data are compared with the code predictions which take into account the 3D structure of conductors around the plasma. The different effects that modify the simple description, where unstable modes can be identified with single Fourier harmonics, appear to be explained by a mixture of toroidicity-induced and 3D eddy current effects.
Hydrothermal synthesis of Fe-doped TiO2 nanostructure photocatalyst
Authors: Nguyen Van Nghia , Nguyen Ngoc Khoa Truong , Nguyen Phi Hung
Published: July 2011

Fe-doped TiO
2 catalyst was prepared by the hydrothermal method. The resulting nanopowders were characterized by x-ray diffraction, transmission electron microscopy and Raman and UV-visible spectroscopies. The photocatalytic activity of the Fe-doped TiO
2 was tested by decomposition of methylene orange with a concentration of 10 mg 
l
−1 in aqueous solution. The obtained results showed that methylene orange was significantly degraded after irradiation for 90 min under a halogen lamp and sunlight. The doping effect on the photocatalytic activity of the iron-doped catalyst samples are discussed.
Milk Marketing Order Winners and Losers
Authors: Chouinard Hayley H. , Davis David E. , LaFrance Jeffrey T. , Perloff Jeffrey M.
Published: July 2011

Determining the impacts on consumers of governmental policies that affect the demand for food products requires a theoretically consistent micro‐level demand model. We estimate a system of demands for weekly city‐level dairy product purchases by nonlinear three‐stage least squares to account for joint determination between quantities and prices. We analyze the distributional effects of federal milk marketing orders, and find results that vary substantially across demographic groups. Families with young children suffer, while wealthier, childless couples benefit. We also find that households with lower incomes bear a greater regulatory burden due to marketing orders than those with higher income levels.
The Adequacy of Speculation in Agricultural Futures Markets: Too Much of a Good Thing?
Authors: Sanders Dwight R. , Irwin Scott H. , Merrin Robert P.
Published: July 2011

This paper revisits the “adequacy of speculation” debate in agricultural futures markets using the positions held by index funds in the Commitment of Traders reports. Index fund positions were a relatively stable percentage of total open interest from 2006–2008. Traditional speculative measures do not show any material shifts over the sample period. Even after adjusting speculative indices for commodity index fund positions, values are within the historical ranges reported in prior research. One implication is that long‐only index funds may be beneficial in markets traditionally dominated by short hedging.
The Social Costs and Benefits of Biofuels: The Intersection of Environmental, Energy and Agricultural Policy
Authors: de Gorter Harry , Just David R.
Published: July 2011

The efficacy of alternative biofuel policies in achieving energy, environmental and agricultural policy goals is assessed using economic cost‐benefit analysis. Government mandates are superior to consumption subsidies, especially with suboptimal fuel taxes and the higher costs involved with raising tax revenues. But subsidies with mandates cause adverse interaction effects; oil consumption is subsidized instead. This unique result also applies to renewable electricity that faces similar policy combinations. Ethanol policy can have a significant impact on corn prices; if not, inefficiency costs rise sharply. Ethanol policy can increase the inefficiency of farm subsidies and vice‐versa. Policies that discriminate against trade, such as production subsidies and tariffs, can more than offset any benefits of a mandate. Sustainability standards are ineffective and illegal according to the WTO, and so should be re‐designed.