bluuebunny/crossref_metadata_2025 huggingface dataset:
Concept of modular flexure-based mechanisms for ultra-high precision robot design
Authors: Richard M. , Clavel R.
Published: June 2011

Abstract. This paper introduces a new concept of modular flexure-based mechanisms to design industrial ultra-high precision robots, which aims at significantly reducing both the complexity of their design and their development time. This modular concept can be considered as a robotic Lego, where a finite number of building bricks is used to quickly build a high-precision robot. The core of the concept is the transformation of a 3-D design problem into several 2-D ones, which are simpler and well-mastered. This paper will first briefly present the theoretical bases of this methodology and the requirements of both types of building bricks: the active and the passive bricks. The section dedicated to the design of the active bricks will detail the current research directions, mainly the maximisation of the strokes and the development of an actuation sub-brick. As for the passive bricks, some examples will be presented, and a discussion regarding the establishment of a mechanical solution catalogue will conclude the section. Last, this modular concept will be illustrated with a practical example, consisting in the design of a 5-degree of freedom ultra-high precision robot.
Precise Design of Artificial Cofactors for Enhancing Peroxidase Activity of Myoglobin: Myoglobin Mutant H64D Reconstituted with a “Single‐Winged Cofactor” Is Equivalent to Native Horseradish Peroxidase in Oxidation Activity
Authors: Matsuo Takashi , Fukumoto Kazuki , Watanabe Takuro , Hayashi Takashi
Published: June 2011

H64D myoglobin mutant was reconstituted with two different types of synthetic hemes that have aromatic rings and a carboxylate‐based cluster attached to the terminus of one or both of the heme‐propionate moieties, thereby forming a “single‐winged cofactor” and “double‐winged cofactor,” respectively. The reconstituted mutant myoglobins have smaller Km values with respect to 2‐methoxyphenol oxidation activity relative to the parent mutant with native heme. This suggests that the attached moiety functions as a substrate‐binding domain. However, the kcat value of the mutant myoglobin with the double‐winged cofactor is much lower than that of the mutant with the native heme. In contrast, the mutant reconstituted with the single‐winged cofactor has a larger kcat value, thereby resulting in overall catalytic activity that is essentially equivalent to that of the native horseradish peroxidase. Enhanced peroxygenase activity was also observed for the mutant myoglobin with the single‐winged cofactor, thus indicating that introduction of an artificial substrate‐binding domain at only one of the heme propionates in the H64D mutant is the optimal engineering strategy for improving the peroxidase activity of myoglobin.
Is Door‐to‐Balloon Time the Best Metric to Assess Successful Treatment of STEMI?
Authors: Conti C. Richard
Published: June 2011

In 2011, all cardiologists believe that rapid opening of the infarct‐related artery is critical to enhanced survival. The preferred way to open an occluded vessel is percutaneous intervention (PCI), but thrombolytic therapy remains a viable option in hospitals when PCI capability is not immediately available. © 2011 Wiley Periodicals, Inc.

The author has no funding, financial relationships, or conflicts of interest to disclose.
The Excited‐State Decay of 1‐Methyl‐2(1H)‐pyrimidinone is an Activated Process
Authors: Ryseck Gerald , Schmierer Thomas , Haiser Karin , Schreier Wolfgang , Zinth Wolfgang , Gilch Peter
Published: June 2011

The photophysics of 1‐methyl‐2(1H)‐pyrimidinone (1MP) dissolved in water is investigated by steady‐state and time‐resolved fluorescence, UV/Vis absorption, and IR spectroscopy. In the experiments, excitation light is tuned to the lowest‐energy absorption band of 1MP peaking at 302 nm. At room temperature (291 K) its fluorescence lifetime amounts to 450 ps. With increasing temperature this lifetime decreases and equals 160 ps at 338 K. Internal conversion (IC) repopulating the ground state and intersystem crossing (ISC) to a triplet state are the dominant decay channels of the excited singlet state. At room temperature both channels contribute equally to the decay, that is, the quantum yields of IC and ISC are both approximately 0.5. The temperature dependence of UV/Vis transient absorption signals shows that the activation energy of the IC process (2140 cm−1) is higher than that of the ISC process (640 cm−1).
Luminescence of Polyethylene Glycol Coated CdSeTe/ZnS and InP/ZnS Nanoparticles in the Presence of Copper Cations
Authors: Beaune Grégory , Tamang Sudarsan , Bernardin Aude , Bayle‐Guillemaud Pascale , Fenel Daphna , Schoehn Guy , Vinet Françoise , Reiss Peter , Texier Isabelle
Published: June 2011

The use of click chemistry for quantum dot (QD) functionalization could be very promising for the development of bioconjugates dedicated to in vivo applications. Alkyne–azide ligation usually requires copper(I) catalysis. The luminescence response of CdSeTe/ZnS nanoparticles coated with polyethylene glycol (PEG) is studied in the presence of copper cations, and compared to that of InP/ZnS QDs coated with mercaptoundecanoic acid (MUA). The quenching mechanisms appear different. Luminescence quenching occurs without any wavelength shift in the absorption and emission spectra for the CdSeTe/ZnS/PEG nanocrystals. In this case, the presence of copper in the ZnS shell is evidenced by energy‐filtered transmission electron microscopy (EF‐TEM). By contrast, in the case of InP/ZnS/MUA nanocrystals, a redshift of the excitation and emission spectra, accompanied by an increase in absorbance and a decrease in photoluminescence, is observed. For CdSeTe/ZnS/PEG nanocrystals, PL quenching is enhanced for QDs with 1) smaller inorganic‐core diameter, 2) thinner PEG shell, and 3) hydroxyl terminal groups. Whereas copper‐induced PL quenching can be interesting for the design of sensitive cation sensors, copper‐free click reactions should be used for the efficient functionalization of nanocrystals dedicated to bioapplications, in order to achieve highly luminescent QD bioconjugates.
Criticisms of and an alternative to the Shadish, Cook, and Campbell validity typology
Authors: Reichardt Charles S.
Published: June 2011

I give four criticisms of the Shadish, Cook, and Campbell (2002) typologyof validity. An alternative typology is proposed that avoids these criticisms. © Wiley Periodicals, Inc., and the American Evaluation Association.
Reframing validity in research and evaluation: A multidimensional, systematic model of valid inference
Authors: Julnes George
Published: June 2011

The importance of promoting valid conclusions from causal inquiry has animated efforts to be more systematic in our conceptions of validity. This chapter elaborates on the systematization of Shadish, Cook, and Campbell (2002) to offer a multidimensional framework of validity that is more comprehensive, more applicable to qualitative inquiry, and more flexible in guiding the progression of our understanding in specific contexts. © Wiley Periodicals, Inc., and the American Evaluation Association.
The construct(ion) of validity as argument
Authors: Greene Jennifer C.
Published: June 2011

The author presents an interpretive/constructivist perspective on outcome evaluation and on the warrants for our outcome‐evaluation conclusions. The perspective underscores the importance of developing warrants through argumentation, in addition to selected empirical evidence. Congruencies with Don Campbell's visions of validity are noted. © Wiley Periodicals, Inc., and the American Evaluation Association.
Terahertz sensing and imaging based on nanostructured semiconductors and carbon materials
Authors: Kawano Y.
Published: June 2011

The advantageous properties of terahertz (THz) waves, such as permeability through objects that are opaque for visible light and the energy spectrum in the microelectron‐volt range that are important in materials research, allow their potential use in various applications of sensing and imaging. However, since the THz region is located between the electronic and photonic bands, even the basic components such as detectors and sources have not been fully developed, unlike in other frequency regions. THz technology also has the problem of low imaging resolution, which results from a considerably longer wavelength than that of the visible light. However, the utilization of nanostructured electronic devices has recently opened up new horizons for THz sensing and imaging. This paper provides an overview of the THz detector and imaging techniques and tracks their recent progress. Specifically, two cutting‐edge techniques, namely, frequency‐selective THz‐photon detection and integrated near‐field THz imaging, are discussed in detail. Finally, the studies of superconductors and semiconductors with high‐resolution THz imaging are described.
CTGF/CCN‐2 over‐expression can directly induce features of skeletal muscle dystrophy
Authors: Morales María Gabriela , Cabello‐Verrugio Claudio , Santander Cristian , Cabrera Daniel , Goldschmeding Roel , Brandan Enrique
Published: June 2011

Muscular dystrophies are diseases characterized by muscle weakness together with cycles of degeneration and regeneration of muscle fibres, resulting in a progressive decrease of muscle mass, diminished muscle force generation and an increase in fibrosis. Fibrotic disorders are the endpoint of many chronic diseases in different tissues, where accumulation of the extracellular matrix (ECM) occurs. Connective tissue growth factor CTGF/CCN2, which is over‐expressed in muscular dystrophies, plays a major role in many progressive scarring conditions. To test the hypothesis that CTGF might not only contribute conversion of already damaged muscle into scar tissue, but that it could by itself also directly contribute to skeletal muscle deterioration, we evaluated the effect of CTGF over‐expression in tibialis anterior muscle of wild‐type mice, using an adenovirus containing the CTGF mouse sequence (Ad–mCTGF). CTGF over‐expression induced extensive skeletal muscle damage, which was followed by a massive regeneration of the damaged muscle, as evidenced by increased embryonic myosin and fibres with centrally located nuclei. It also induced strong fibrosis with increased levels of fibronectin, collagen, decorin and α‐smooth muscle actin (α‐SMA). Moreover, CTGF over‐expression caused a decrease of the specific isometric contractile force. Strikingly, when CTGF over‐expression stopped, the entire phenotype proved to be reversible, in parallel with normalization of CTGF levels. Thus, CTGF not merely acts downstream of muscle injury but also contributes directly to the deterioration of skeletal muscle phenotype and function. Moreover, normalization of expression levels led to spontaneous reversal of the CTGF‐induced phenotype and to full recovery of muscle structure. These observations underscore the importance of CTGF in the pathophysiology of muscular dystrophies and suggest that targeting CTGF might have significant potential in the development of novel therapies for Duchenne muscular dystrophy and related diseases. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Enhanced internal quantum efficiency of an InGaN/GaN quantum well as a function of silver thickness due to surface plasmon coupling
Authors: Renwick Paul , Tang Hao , Wang Qi , Smith Richard , Wang Tao
Published: June 2011

Excitation‐power‐dependent photoluminescence (PL) measurements have been carried out on a single InGaN quantum well structure with a different thickness of silver on its surface. This allows for investigation of surface plasmon (SP) coupling enhanced internal quantum efficiency as a function of the silver thickness. A maximal enhancement with a factor of up to 25 times in PL intensity has been observed on the sample with a silver film of 100 nm, compared with the as‐grown sample. A blue shift in peak energy has been observed as a function of silver thickness. Atomic force microscopy has been employed to examine the change in morphology of the silver films with different thickness. Finally an estimation of the internal quantum efficiency is made, showing ∼10.8 times enhancement on the sample with the 100 nm silver, compared to the as‐grown sample. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
3‐dimensional microscope analysis of bone and tooth surface modifications: comparisons of fossil specimens and replicas
Authors: Bello Silvia M. , Verveniotou Efstratia , Cornish Lorraine , Parfitt Simon A.
Published: June 2011

Cut‐marks on fossil bones and teeth are an important source of evidence in the reconstruction of ancient butchery practices. The analysis of butchery marks has allowed archaeologists to interpret aspects of past subsistence strategies and the behavior of early humans. Recent advances in optical scanning microscopy allow detailed measurements of cut‐mark morphology to be undertaken. An example of this technology is the Alicona 3D InfiniteFocus imaging microscope, which has been applied recently to the study of surface modifications on bones and teeth. Three‐dimensional models generated by the Alicona microscope have been used to identify cross‐sectional features of experimental cut‐marks that are characteristic for specific cutting actions (e.g., slicing, chopping, scraping) and different tool types (e.g., metal versus stone tools). More recently, this technology has been applied successfully to the analysis of ∼500,000 year‐old cut‐marked animal bones from Boxgrove (U.K.), as well as cannibalized 14,700 cal BP year‐old human bones from Gough's Cave (U.K.). This article describes molding methods used to replicate fragile prehistoric bones and teeth, where image quality was adversely affected by specimen translucency and reflectivity. Alicona images generated from molds and casts are often of better quality than those of the original specimen. SCANNING 33: 316–324, 2011. © 2011 Wiley Periodicals, Inc.
Rapid Method for the Determination of Moisture Content in Biodiesel Using FTIR Spectroscopy
Authors: Mirghani Mohamed E. S. , Kabbashi Nasreldin A. , Alam Md. Zahangir , Qudsieh Isam Y. , Alkatib Ma'an F. R.
Published: June 2011

A new, rapid, and direct method was developed for the determination of moisture content in biodiesel produced from various types of oils using Fourier transform infrared (FTIR) spectroscopy with an attenuated total reflectance (ATR) element. Samples of biodiesels used in this study were produced using sludge palm oil (SPO). The calibration set was prepared by spiking double‐distilled water into dried biodiesel samples in ratios (w/w) between 0 and 10% moisture. Absorbance values from the wavelength regions 3,700–3,075 and 1,700–1,500 cm−1, and the partial least square (PLS) regression method were used to derive a FTIR spectroscopic calibration model for moisture content in biodiesel samples. The coefficient of determinations (R2) for the models was computed by comparing the results obtained from FTIR spectroscopy against the values of the moisture concentrations (%) determined using the American Oil Chemists’ Society (AOCS) oven method Ca 2d‐25. Same comparison was done using International Union of Pure and Applied Chemistry (IUPAC) distillation method 2.602. R2 was 0.9793 and 0.9700 using AOCS and IUPAC methods, respectively. The standard error (SE) of calibration was 1.84. The calibration model was cross validated within the same set of samples, and the standard deviation (SD) of the difference for repeatability (SDDr) and accuracy (SDDa) of the FTIR method was determined. With its speed and ease of data manipulation, FTIR spectroscopy is a useful alternative method to other methods for rapid and routine determination of moisture content in biodiesel for quality control.
Une défense de l’approche simulationniste du souvenir épisodique
Authors: Perrin Denis
Published: June 2011

ABSTRACT: In this paper, I carry out an application of the debate between simulationism and theory theory to the issue of episodic memory. I first criticize the approach favored by the theory theory. Then I advance a simulationist conception of the relationship between the phenomenology of episodic memory and its specific kind of self-consciousness. On my view, subjectivity belongs to the very content of episodic memory, not as an element of its content, but as the perspective it gives to the content that makes the simulation of past experience possible. In support of that view, I provide an analysis inspired by J. Perry of the semantics of de se thought. It gives the remembering subject a non-representational presence in the mnesic content.
HEALTH CARE UTILIZATION, SOCIOECONOMIC FACTORS AND CHILD HEALTH IN INDIA
Authors: BHARGAVA ALOK , GUNTUPALLI ARAVINDA M. , LOKSHIN MICHAEL
Published: June 2011

This paper models the proximate determinants of height, weight and haemoglobin concentration of over 25,000 Indian children using data from the National Family Health Survey-3. The effects of public and private health care service utilization, food consumption patterns and maternal health status on child health were investigated in a multidisciplinary framework. Methodological issues such as potential endogeneity of explanatory variables and the appropriateness of combining height and weight as the body mass index were tackled. The results from models for children's heights and weight showed beneficial effects of child vaccinations against DPT, polio and measles, and negative effects of not utilizing government health facilities. The models for children's haemoglobin concentration indicated beneficial effects of food consumption patterns and treatment against intestinal parasites. The results provide several insights for improving child health in India.
Population dynamics and reproductive output of the non-indigenous crab Charybdis hellerii in the south-eastern Caribbean Sea
Authors: Bolaños Juan A. , Baeza J. Antonio , Hernandez Jesús E. , Lira Carlos , López Régulo
Published: June 2011

Charybdis hellerii is one of several poorly known non-indigenous crabs in the Caribbean. In this study we report on the reproductive dynamic of a shallow subtidal population that invaded Isla Margarita, Venezuela, south-eastern Caribbean Sea > 15 years ago and has persisted in the region up to date. Male and female crabs, both large and small, were found year-round at the study site. The size–frequency distribution indicated a lifespan of 2–3 years. Charybdis hellerii reproduces continuously but with very low intensity during the year. Small individuals (<25 mm carapace length) were uncommon and intermittently found during the study period. Sex-ratio varied between 0.1 and 0.65 (mean ± SD = of 0.46 ± 0.14) and did not differ significantly from 1:1 ratio during most of the year. The size of the smallest brooding female was 36.81 mm carapace width (CW). Behavioural size at first maturity (movable abdomen) in males and females was estimated to be 22.39 mm CW (confidence limits: 18.35–24.72) and 37.43 mm CW (35.55–39.09), respectively. Reproductive output, estimated as the ratio of embryo to female body dry mass, varied between 0.052 and 0.084 (0.07 ± 0.008). Also, reproductive output was size-dependent with large females allocating proportionally less resources to egg production than small females. The reproductive schedule here reported for C. hellerii disagrees with the generalized idea of exotic populations ‘thriving’ in an environment free of natural enemies (e.g. predators, competitors and diseases).
Cultivation of methanogenic community from subseafloor sediments using a continuous-flow bioreactor
Authors: Imachi Hiroyuki , Aoi Ken , Tasumi Eiji , Saito Yumi , Yamanaka Yuko , Saito Yayoi , Yamaguchi Takashi , Tomaru Hitoshi , Takeuchi Rika , Morono Yuki , Inagaki Fumio , Takai Ken
Published: June 2011

Microbial methanogenesis in subseafloor sediments is a key process in the carbon cycle on the Earth. However, the cultivation-dependent evidences have been poorly demonstrated. Here we report the cultivation of a methanogenic microbial consortium from subseafloor sediments using a continuous-flow-type bioreactor with polyurethane sponges as microbial habitats, called down-flow hanging sponge (DHS) reactor. We anaerobically incubated methane-rich core sediments collected from off Shimokita Peninsula, Japan, for 826 days in the reactor at 10 °C. Synthetic seawater supplemented with glucose, yeast extract, acetate and propionate as potential energy sources was provided into the reactor. After 289 days of operation, microbiological methane production became evident. Fluorescence in situ hybridization analysis revealed the presence of metabolically active microbial cells with various morphologies in the reactor. DNA- and RNA-based phylogenetic analyses targeting 16S rRNA indicated the successful growth of phylogenetically diverse microbial components during cultivation in the reactor. Most of the phylotypes in the reactor, once it made methane, were more closely related to culture sequences than to the subsurface environmental sequence. Potentially methanogenic phylotypes related to the genera Methanobacterium, Methanococcoides and Methanosarcina were predominantly detected concomitantly with methane production, while uncultured archaeal phylotypes were also detected. Using the methanogenic community enrichment as subsequent inocula, traditional batch-type cultivations led to the successful isolation of several anaerobic microbes including those methanogens. Our results substantiate that the DHS bioreactor is a useful system for the enrichment of numerous fastidious microbes from subseafloor sediments and will enable the physiological and ecological characterization of pure cultures of previously uncultivated subseafloor microbial life.
Colon Electrical Stimulation: Potential Use for Treatment of Obesity
Authors: Sallam Hanaa S. , Chen Jiande D.Z.
Published: June 2011

Obesity is one of the most prevalent health problems in the United States. Current therapeutic strategies for the treatment of obesity are unsatisfactory. We hypothesized the use of colon electrical stimulation (CES) to treat obesity by inhibiting upper gastrointestinal motility. In this preliminary study, we aimed at studying the effects of CES on gastric emptying of solid, intestinal motility, and food intake in dogs. Six dogs, equipped with serosal colon electrodes and a jejunal cannula, were randomly assigned to receive sham‐CES or CES during the assessment of: (i) gastric emptying of solids, (ii) postprandial intestinal motility, (iii) autonomic functions, and (iv) food intake. We found that (i) CES delayed gastric emptying of solids by 77%. Guanethidine partially blocked the inhibitory effect of CES on solid gastric emptying; (ii) CES significantly reduced intestinal contractility and the effect lasted throughout the recovery period; (iii) CES decreased vagal activity in both fasting and fed states, increased the sympathovagal balance and marginally increased sympathetic activity in the fasting state; (iv) CES resulted in a reduction of 61% in food intake. CES reduces food intake in healthy dogs and the anorexigenic effect may be attributed to its inhibitory effects on gastric emptying and intestinal motility, mediated via the autonomic mechanisms. Further studies are warranted to investigate the therapeutic potential of CES for obesity.
Suppression of in-plane tunneling anisotropic magnetoresistance effect in Co2MnSi/MgO/n-GaAs and CoFe/MgO/n-GaAs junctions by inserting a MgO barrier
Authors: Akiho Takafumi , Uemura Tetsuya , Harada Masanobu , Matsuda Ken-ichi , Yamamoto Masafumi
Published: June 2011

The effects of MgO tunnel barriers on both junction resistance and tunneling anisotropic magnetoresistance (TAMR) characteristics of Co2MnSi(CMS)/MgO/n-GaAs junctions and Co50Fe50(CoFe)/MgO/n-GaAs junctions were investigated. The resistance-area (RA) product of the CMS/MgO/n-GaAs junctions showed an exponential dependence on MgO thickness (tMgO), indicating that the MgO layer acts as a tunneling barrier. The RA product of CMS/MgO/n-GaAs with tMgO<1 nm was smaller than that of the sample without MgO. The observed spin-valvelike magnetoresistance of CMS/n-GaAs and CoFe/n-GaAs Schottky tunnel junctions attributed to the TAMR effect did not appear in the cases of CMS/MgO/n-GaAs and CoFe/MgO/n-GaAs tunnel junctions. The lowering of the RA product and the suppression of the TAMR effect caused by inserting a thin MgO layer between CMS and n-GaAs were both possibly due to suppression of the Fermi-level pinning of GaAs and lowering of the Schottky barrier height.
Generating random density matrices
Authors: Życzkowski Karol , Penson Karol A. , Nechita Ion , Collins Benoît
Published: June 2011

We study various methods to generate ensembles of random density matrices of a fixed size N, obtained by partial trace of pure states on composite systems. Structured ensembles of random pure states, invariant with respect to local unitary transformations are introduced. To analyze statistical properties of quantum entanglement in bi-partite systems we analyze the distribution of Schmidt coefficients of random pure states. Such a distribution is derived in the case of a superposition of k random maximally entangled states. For another ensemble, obtained by performing selective measurements in a maximally entangled basis on a multi-partite system, we show that this distribution is given by the Fuss-Catalan law and find the average entanglement entropy. A more general class of structured ensembles proposed, containing also the case of Bures, forms an extension of the standard ensemble of structureless random pure states, described asymptotically, as N → ∞, by the Marchenko-Pastur distribution.
Improvement of the low-frequency sensitivity of MgO-based magnetic tunnel junctions by annealing
Authors: Duan H. , Tseng H. W. , Li Y. , van Dover R. B.
Published: June 2011

Magnetic tunnel junctions can serve as ultrasensitive low-frequency magnetic sensors, however, their low-frequency performance is limited by low-frequency noise, i.e., 1/f noise. In this paper, we investigate the 1/f noise in MgO magnetic tunnel junctions (MTJs) with a tunneling magnetoresistance (TMR) of 160%, and examine the influence of annealing and MTJ size. The results show that the annealing process can not only dramatically improve the TMR, but can also strongly decrease the MTJ noise. The effect is discussed in terms of the structure of MgO barriers and tunneling probabilities. Increasing the MTJ area to 6400 μm2 yields a voltage spectral density as low as 11 nV/Hz1/2 at 1000 Hz. The possible reasons for the area dependence are discussed.
Medium-range icosahedral order in quasicrystal-forming Zr2Pd binary metallic glass
Authors: Huang Li , Fang X. W. , Wang C. Z. , Kramer M. J. , Ding Z. J. , Ho K. M.
Published: June 2011

Medium-range order in Zr2Pd metallic glass was studied using a combination of x-ray diffraction experiment and atomistic simulations. We show that, in contrast to earlier experimental interpretations, the icosahedral-like polyhedron is centered around Pd, rather than Zr. Furthermore, we find that the ordered icosahedral packing around Pd extends to the third shell in the way similar to that in the Bergman-type clusters. The existence of Bergman-type clusters sheds interesting light into the formation of nanoquasicrystal phase during crystallization process of Zr2Pd metallic glass.
Tunable metal–insulator transitions in bilayer graphene by thermal annealing
Authors: Kalon Gopinadhan , Shin Young Jun , Yang Hyunsoo
Published: June 2011

Tunable and highly reproducible metal–insulator transitions have been observed in bilayer graphene upon thermal annealing at 400 K under high vacuum conditions. Before annealing, the sample is metallic in the whole temperature regime of study. Upon annealing, the conductivity changes from metallic to that of an insulator and the transition temperature is a function of annealing time. The pristine metallic state can be reinstated by exposing to air thereby inducing changes in the electronic properties by adsorbing water vapor, which makes graphene a technologically promising material for sensor applications.
Acceptors in ZnO nanocrystals
Authors: Teklemichael S. T. , Oo W. M. Hlaing , McCluskey M. D. , Walter E. D. , Hoyt D. W.
Published: June 2011

While zinc oxide (ZnO) has potential for optoelectronic applications, the lack of reliable p-type doping remains a major challenge. We provide evidence that ZnO nanocrystals contain uncompensated acceptors. IR absorption peaks at liquid-helium temperatures suggest a hydrogenic acceptor with a hole binding energy of 0.4–0.5 eV. Electron paramagnetic resonance (EPR) measurements in the dark showed a resonance at g=2.003, characteristic of acceptors that involve a zinc vacancy. An EPR resonance due to vacancy hydrogen complexes was observed after exposure to light. Given the lack of alternatives, vacancy complexes may provide a feasible route toward p-type conductivity.
Nanopatterning on rough surfaces using optically trapped microspheres
Authors: Tsai Y.-C. , Fardel R. , Arnold C. B.
Published: June 2011

While nanofabricated structures find an increasingly large number of applications, few techniques are able to pattern rough or uneven surfaces, or surfaces with pre-existing structure. In this letter we show that optical trap assisted nanopatterning (OTAN), a near-field laser based technique, is able to produce nanoscale features on surfaces with large roughness but without the need for focus adjustment. Patterning on model surfaces of polyimide with vertical steps greater than 0.5 μm shows a high degree of uniformity, demonstrating that OTAN is a suitable technique to pattern nontraditional surfaces for emerging technologies.
Comparison of photothermal and piezoacoustic excitation methods for frequency and phase modulation atomic force microscopy in liquid environments
Authors: Labuda A. , Kobayashi K. , Kiracofe D. , Suzuki K. , Grütter P. H. , Yamada H.
Published: June 2011

In attempting to perform frequency modulation atomic force microscopy (FM-AFM) in liquids, a non-flat phase transfer function in the self-excitation system prevents proper tracking of the cantilever natural frequency. This results in frequency-and-phase modulation atomic force microscopy (FPM-AFM) which lies in between phase modulation atomic force microscopy (PM-AFM) and FM-AFM. We derive the theory necessary to recover the conservative force and damping in such a situation, where standard FM-AFM theory no longer applies. Although our recovery procedure applies to all cantilever excitation methods in principle, its practical implementation may be difficult, or even impossible, if the cantilever is driven piezoacoustically. Specifically, we contrast the piezoacoustic excitation method to the photothermal method in the context of force spectroscopy of hydration structures at the mica-water interface. The results clearly demonstrate that photothermal excitation is superior to piezoacoustic excitation, as it allows for accurate quantitative interpretation of the acquired data.
Glassy behaviour of random field Ising spins on Bethe lattice in external magnetic field
Authors: Khalid Bannora  , Galal Ismail  , Wafaa Hassan
Published: June 2011

The thermodynamics and the phase diagram of random field Ising model (RFIM) on Bethe lattice are studied by using a replica trick. This lattice is placed in an external magnetic field (B). A Gaussian distribution of random field (hi) with zero mean and variance 〈h2i〉 =HRF2is considered. The free-energy (F), the magnetization (M) and the order parameter (q) are investigated for several values of coordination number (z). The phase diagram shows several interesting behaviours and presents tricritical point at critical temperatureTC=J/kand whenHRF= 0 for finitez. The free-energy (F) values increase asTincreases for different intensities of random field (HRF) and finitez. The internal energy (U) has a similar behaviour to that obtained from the Monte Carlo simulations. The ground state of magnetization decreases as the intensity of random fieldHRFincreases. The ferromagnetic (FM)-paramagnetic (PM) phase boundary is clearly observed only whenz→ ∞. While FM—PM-spin glass (SG) phase boundaries are present for finitez. The magnetic susceptibility (χ) shows a sharp cusp atTCin a small random field for finitezand rounded different peaks on increasingHRF.
A laminopathic mutation disrupting lamin filament assembly causes disease-like phenotypes inCaenorhabditis elegans
Authors: Bank Erin M. , Ben-Harush Kfir , Wiesel-Motiuk Naama , Barkan Rachel , Feinstein Naomi , Lotan Oren , Medalia Ohad , Gruenbaum Yosef
Published: June 2011

Mutations in the human LMNA gene underlie many laminopathic diseases, including Emery-Dreifuss muscular dystrophy (EDMD); however, a mechanistic link between the effect of mutations on lamin filament assembly and disease phenotypes has not been established. We studied the ΔK46 Caenorhabditis elegans lamin mutant, corresponding to EDMD-linked ΔK32 in human lamins A and C. Cryo-electron tomography of lamin ΔK46 filaments in vitro revealed alterations in the lateral assembly of dimeric head-to-tail polymers, which causes abnormal organization of tetrameric protofilaments. Green fluorescent protein (GFP):ΔK46 lamin expressed in C. elegans was found in nuclear aggregates in postembryonic stages along with LEM-2. GFP:ΔK46 also caused mislocalization of emerin away from the nuclear periphery, consistent with a decreased ability of purified emerin to associate with lamin ΔK46 filaments in vitro. GFP:ΔK46 animals had motility defects and muscle structure abnormalities. These results show that changes in lamin filament structure can translate into disease-like phenotypes via altering the localization of nuclear lamina proteins, and suggest a model for how the ΔK32 lamin mutation may cause EDMD in humans.
A phosphodegron controls nutrient-induced proteasomal activation of the signaling protease Ssy5
Authors: Omnus Deike J. , Pfirrmann Thorsten , Andréasson Claes , Ljungdahl Per O.
Published: June 2011

Regulated proteolysis serves as a mechanism to control cellular processes. The SPS (Ssy1-Ptr3-Ssy5) sensor in yeast responds to extracellular amino acids by endoproteolytically activating transcription factors Stp1 and Stp2 (Stp1/2). The processing endoprotease Ssy5 is regulated via proteasomal degradation of its noncovalently associated N-terminal prodomain. We find that degradation of the prodomain requires a conserved phosphodegron comprising phosphoacceptor sites and ubiquitin-accepting lysine residues. Upon amino acid induction, the phosphodegron is modified in a series of linked events by a set of general regulatory factors involved in diverse signaling pathways. First, an amino acid–induced conformational change triggers phosphodegron phosphorylation by the constitutively active plasma membrane–localized casein kinase I (Yck1/2). Next the prodomain becomes a substrate for polyubiquitylation by the Skp1/Cullin/Grr1 E3 ubiquitin ligase complex (SCFGrr1). Finally, the modified prodomain is concomitantly degraded by the 26S proteasome. These integrated events are requisite for unfettering the Ssy5 endoprotease, and thus Stp1/2 processing. The Ssy5 phosphoacceptor motif resembles the Yck1/2- and Grr1-dependent degrons of regulators in the Snf3/Rgt2 glucose-sensing pathway. Our work defines a novel proteolytic activation cascade that regulates an intracellular signaling protease and illustrates how general signaling components are recruited to distinct pathways that achieve conditional and specific signaling outputs.
HAPGEN2: simulation of multiple disease SNPs
Authors: Su Zhan , Marchini Jonathan , Donnelly Peter
Published: June 2011

Motivation: Performing experiments with simulated data is an inexpensive approach to evaluating competing experimental designs and analysis methods in genome-wide association studies. Simulation based on resampling known haplotypes is fast and efficient and can produce samples with patterns of linkage disequilibrium (LD), which mimic those in real data. However, the inability of current methods to simulate multiple nearby disease SNPs on the same chromosome can limit their application.

Results: We introduce a new simulation algorithm based on a successful resampling method, HAPGEN, that can simulate multiple nearby disease SNPs on the same chromosome. The new method, HAPGEN2, retains many advantages of resampling methods and expands the range of disease models that current simulators offer.

Availability: HAPGEN2 is freely available from http://www.stats.ox.ac.uk/~marchini/software/gwas/gwas.html.

Contact:  zhan@well.ox.ac.uk

Supplementary information:  Supplementary data are available at Bioinformatics online.
A rep-based hairpin inhibits replication of diverse maize streak virus isolates in a transient assay
Authors: Owor Betty E. , Martin Darren P. , Rybicki Edward P. , Thomson Jennifer A. , Bezuidenhout Marion E. , Lakay Francisco M. , Shepherd Dionne N.
Published: June 2011

Maize streak disease, caused by the A strain of the African endemic geminivirus, maize streak mastrevirus (MSV-A), threatens the food security and livelihoods of subsistence farmers throughout sub-Saharan Africa. Using a well-established transient expression assay, this study investigated the potential of a spliceable-intron hairpin RNA (hpRNA) approach to interfere with MSV replication. Two strategies were explored: (i) an inverted repeat of a 662 bp region of the MSV replication-associated protein gene (rep), which is essential for virus replication and is therefore a good target for post-transcriptional gene silencing; and (ii) an inverted repeat of the viral long intergenic region (LIR), considered for its potential to trigger transcriptional silencing of the viral promoter region. After co-bombardment of cultured maize cells with each construct and an infectious partial dimer of the cognate virus genome (MSV-Kom), followed by viral replicative-form-specific PCR, it was clear that, whilst the hairpinrepconstruct (pHPrepΔI662) completely inhibited MSV replication, the LIR hairpin construct was ineffective in this regard. In addition, pHPrepΔI662inhibited or reduced replication of six MSV-A genotypes representing the entire breadth of known MSV-A diversity. Further investigation by real-time PCR revealed that the pHPrepΔI662inverted repeat was 22-fold more effective at reducing virus replication than a construct containing the sense copy, whilst the antisense copy had no effect on replication when compared with the wild type. This is the first indication that an hpRNA strategy targeting MSVrephas the potential to protect transgenic maize against diverse MSV-A genotypes found throughout sub-Saharan Africa.
The Arabidopsis Mitochondria-Localized Pentatricopeptide Repeat Protein PGN Functions in Defense against Necrotrophic Fungi and Abiotic Stress Tolerance
Authors: Laluk Kristin , AbuQamar Synan , Mengiste Tesfaye
Published: June 2011

Pentatricopeptide repeat (PPR) proteins (PPRPs) are encoded by a large gene family in Arabidopsis (Arabidopsis thaliana), and their functions are largely unknown. The few studied PPRPs are implicated in different developmental processes through their function in RNA metabolism and posttranscriptional regulation in plant organelles. Here, we studied the functions of Arabidopsis PENTATRICOPEPTIDE REPEAT PROTEIN  FOR GERMINATION ON NaCl (PGN) in plant defense and abiotic stress responses. Inactivation of PGN results in susceptibility to necrotrophic fungal pathogens as well as hypersensitivity to abscisic acid (ABA), glucose, and salinity. Interestingly, ectopic expression of PGN results in the same phenotypes as the pgn null allele, indicating that a tight regulation of the PGN transcript is required for normal function. Loss of PGN function dramatically enhanced reactive oxygen species accumulation in seedlings in response to salt stress. Inhibition of ABA synthesis and signaling partially alleviates the glucose sensitivity of pgn, suggesting that the mutant accumulates high endogenous ABA. Accordingly, induction of NCED3, encoding the rate-limiting enzyme in stress-induced ABA biosynthesis, is significantly higher in pgn, and the mutant has higher basal ABA levels, which may underlie its phenotypes. The pgn mutant has altered expression of other ABA-related genes as well as mitochondria-associated transcripts, most notably elevated levels of ABI4 and ALTERNATIVE OXIDASE1a, which are known for their roles in retrograde signaling induced by changes in or inhibition of mitochondrial function. These data, coupled with its mitochondrial localization, suggest that PGN functions in regulation of reactive oxygen species homeostasis in mitochondria during abiotic and biotic stress responses, likely through involvement in retrograde signaling.
Impact of the removal of misleading terms on cigarette pack on smokers' beliefs about ‘light/mild’ cigarettes: cross‐country comparisons
Authors: Yong Hua‐Hie , Borland Ron , Cummings K. Michael , Hammond David , O'Connor Richard J. , Hastings Gerard , King Bill
Published: June 2011

Aim  This paper examines how smokers' beliefs about ‘light/mild’ cigarettes in Australia, Canada and the United Kingdom were affected by the removal of misleading ‘light/mild’ terms from packs.

Design, setting and participants  The data come from the first seven waves (2002–09) of the International Tobacco Control Policy Evaluation (ITC) Four‐Country Survey, an annual cohort telephone survey of adult smokers in Canada, the United States, the United Kingdom and Australia (21 613 individual cases). ‘Light’ and ‘mild’ descriptors were removed in 2003 in the United Kingdom, in 2006 in Australia and in 2007 in Canada. We compare beliefs about ‘light’ cigarettes both before and after the bans, with those of smokers in the United States serving as the control condition.

Measures  Smokers' beliefs about ‘light’ cigarettes were assessed using a set of statements rated on a five‐point ‘agree’–‘disagree’ scale.

Findings  The proportions of respondents reporting misperceptions about light cigarettes declined between 2002 and 2009 in all four countries. There were marked temporary reductions in reported misperceptions in the United Kingdom and Australia, but not in Canada, following the removal of ‘light/mild’ descriptors.

Conclusions  Removal of ‘light/mild’ descriptors and tar, nicotine and carbon monoxide yield information from cigarette packs is insufficient to effectively eliminate false beliefs. The combination of alternative descriptors and design features that produce differences in taste strength and harshness, independent of actual intakes, are sufficient to produce or sustain the same misbeliefs.
Alfentanil/etomidate anaesthesia for endolaryngeal microsurgery
Authors: VERSICHELEN L. , ROLLY G. , BEERENS J.
Published: June 2011

Anaesthesia for laryngeal microsurgery by laser was conducted using etomidate and alfentanil. Patients' lungs were ventilated with air to avoid the danger of fire during the use of the laser. Thirty one patients received fentanyl/droperidol or pethidine for premedication. Anaesthesia was induced with etomidate 300 μg/kg and maintained with etomidate 30 μg/kg/minute. Alfentanil was given as an initial bolus of 40 μg/kg with subsequent increments of 15 μg/kg. Systolic arterial blood pressure and heart rate decreased significantly at some time intervals. Blood biochemistry and blood gases were within normal ranges, except for elevated Pao2 values during ventilation on pure oxygen. This technique adequately provided the requirements for prompt, smooth awakening, with a low incidence of nausea and vomiting.
The effectiveness of therapeutic play, using virtual reality computer games, in promoting the psychological well‐being of children hospitalised with cancer
Authors: Li William HC , Chung Joyce OK , Ho Eva KY
Published: June 2011

Aims.  To examine the effectiveness of therapeutic play, using virtual reality computer games, in minimising anxiety and reducing depressive symptoms in Hong Kong Chinese children hospitalised with cancer.

Background.  There has been an increase in the use of therapeutic play intervention to help children cope with the stress of hospitalisation. However, it is not clear whether therapeutic play is an appropriate psychological intervention for Chinese children hospitalised with cancer.

Design.  A non‐equivalent control group pretest–post‐test, between‐subject design was employed.

Method.  Hong Kong Chinese Children (8–16 years of age), admitted to a paediatric oncology ward for the treatment of cancer during a 14‐month period, were invited to participate in the study. Of the 122 children, 70 formed the control group receiving routine nursing care and 52 in the experimental group receiving therapeutic play interventions.

Results.  The results showed that children in the experimental group reported statistically significant fewer depressive symptoms than children in the control group on day 7. The results, however, find no differences in children’s anxiety scores between the two groups on day 7.

Conclusion.  The study provides empirical evidence to support the effectiveness of therapeutic play, using virtual reality computer games, in the psychological preparation of children hospitalised with cancer, thus charting a path towards promoting holistic and quality care.

Relevance to clinical practice.  The findings heighten the awareness in healthcare professionals that play is a very important part of children’s life and that they need play even when they are ill.
Using virtual interactions to enhance the teaching of communication skills to information technology students
Authors: Pineteh Ernest A.
Published: June 2011

This paper examines the use of virtual interactions in a Communication class at Cape Peninsula University of Technology (CPUT)‐South Africa. It demonstrates how synthesising virtual and other computer‐assisted exercises as well as traditional classroom‐based activities can enhance the teaching and learning of communication concepts. The paper is based on the experiences of 1st‐year Information Technology students at CPUT, and the data was gleaned from observations, questionnaires and course reflections during one semester of an academic year. The findings of the investigation revealed that despite the burgeoning interest in computer‐centered teaching and learning at CPUT, traditional methods of teaching are still valuable given the differences in the learning styles and technological experiences of students. In this light, this paper subscribes to “complementarity” as the most expedient teaching approach because it can cater for the student diversity in this learning space as well as promote quality peer interactions and collaborative learning. It can also transform the process of learning into an invigorating experience especially because these students are dispassionate about communication.

Practitioner notes

What is already known about this topic

Technology in education

Virtual teaching and learning

Collaborative teaching and learning

Traditional versus computer‐mediated teaching approaches

What this paper adds

Student diversity and teaching dynamics in South Africa

The challenges of university of technology students in South Africa and the value of computer‐mediated teaching and learning

The role of communication in developing cognitive skills of South African students.

The technological challenges at Cape Peninsula University of Technology (CPUT)‐South Africa and the implications for teaching and learning

Implications for practice and/or policy

Use computer‐mediated teaching and learning as a complementary tool in context of South Africa

Develop curricula that promote collaborative teaching and learning either in class or online.

Place communication at the core of teaching and learning in the Information Technology (IT) department at CPUT‐South Africa in order to develop critical soft skills.