bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance of diamond-like carbon-protected rubber under cyclic friction. II. Influence of substrate viscoelasticity on the friction evolution
Authors: Martinez-Martinez D. , van der Pal J. P. , Pei Y. T. , De Hosson J. Th. M.
Published: December 2011

In this paper, the influence of the mechanical properties of rubber substrate on frictional behavior of DLC-protected rubber is studied by numerical methods. The viscoelastic contribution to the friction during a tribotest was simulated according to a “mattress” approach composed by Voigt or standard linear solid units. The latter approach demonstrated more accurate predictions. In both cases, the results show an increase of the contact depth, which is in agreement with the experimental observations. The simulations also show a progressive reduction of the viscoelastic contribution of the coefficient of friction (CoF) with the number of laps due to the elongation of the front part of the contact area. This prediction does not agree with the experimentally observed increase of CoF, and suggests a dominant contribution of the adhesive component to the friction under real conditions.
Tunable and collimated terahertz radiation generation by femtosecond laser pulses
Authors: Malik Hitendra K. , Malik Anil K.
Published: December 2011

A mechanism is proposed for the generation of tunable terahertz (THz) radiation under the application of two femtosecond laser pulses and an external magnetic field, where quick tunnel ionization is achieved that leads to higher plasma density evolution and large residual current for the efficient THz radiation generation. With the optimization of magnetic field, phase difference, and amplitudes of lasers’ fields, a THz source can be obtained with tunable frequency and power along with a control on the direction of radiation emission.
Raman scattering from Ge-Si core-shell nanowires: Validity of analytical strain models
Authors: Singh Rachna , Dailey Eric J. , Drucker Jeff , Menéndez José
Published: December 2011

The Raman scattering spectra from Ge-Si core-shell nanowires have been computed using two alternative strain models: A simple analytical approach that assumes cylindrical symmetry and isotropic elastic constants, and a more realistic method that incorporates the actual nanowire geometry and the cubic-symmetry elastic constants of Si and Ge. The results show that the simple analytical model provides qualitatively correct descriptions of the strain and Raman spectra. In particular, both calculations predict that the strain is essentially uniform within the core section of the nanowire, suggesting that core Raman spectra are ideal for strain characterization. The quantitative agreement between the two methods is also surprisingly good, making it possible to use simple analytical expressions to estimate the strain in nanowires with errors not exceeding 10%.
Transition temperature from band to hopping direct current conduction in crystalline semiconductors with hydrogen-like impurities: Heat versus Coulomb attraction
Authors: Poklonski N. A. , Vyrko S. A. , Poklonskaya O. N. , Zabrodskii A. G.
Published: December 2011

For nondegenerate bulk semiconductors, we have used the virial theorem to derive an expression for the temperature Tj of the transition from the regime of “free” motion of electrons in the c-band (or holes in the υ-band) to their hopping motion between donors (or acceptors). Distribution of impurities over the crystal was assumed to be of the Poisson type, while distribution of their energy levels was assumed to be of the Gaussian type. Our conception of the virial theorem implementation is that the transition from the band-like conduction to hopping conduction occurs when the average kinetic energy of an electron in the c-band (hole in the υ-band) is equal to the half of the absolute value of the average energy of the Coulomb interaction of an electron (hole) with the nearest neighbor ionized donor (acceptor). Calculations of Tj according to our model agree with experimental data for crystals of Ge, Si, diamond, etc. up to the concentrations of a hydrogen-like impurity, at which the phase insulator-metal transition (Mott transition) occurs. Under the temperature Th ≈ Tj /3, when the nearest neighbor hopping conduction via impurity atoms dominates, we obtained expressions for the electrostatic field screening length Λh in the Debye-Hückel approximation, taking into account a nonzero width of the impurity energy band. It is shown that the measurements of quasistatic capacitance of the semiconductor in a metal-insulator-semiconductor structure in the regime of the flat bands at the temperature Th allow to determine the concentration of doping impurity or its compensation ratio by knowing Λh.
Oxygen-vacancy-mediated negative differential resistance in La and Mg co-substituted BiFeO3 thin film
Authors: Ke Qingqing , Kumar Amit , Lou Xiaojie , Zeng Kaiyang , Wang John
Published: December 2011

The conductive characteristics of Bi0.9La0.1Fe0.96Mg0.04O3 (BLFM) thin film are investigated at various temperatures and a negative differential resistance (NDR) is observed in the thin film, where a leakage current peak occurs upon application of a downward electric field above 80 °C. The origin of the NDR behavior is shown to be related to the ionic defect of oxygen vacancies (VO••) present in the film. On the basis of analyzing the leakage mechanism and surface potential behavior, the NDR behavior can be understood by considering the competition between the polarized distribution and neutralization of VO••.
Vertical cavity surface emitting lasers with the active layer position detuned from standing wave antinode for picosecond pulse generation by gain switching
Authors: Ryvkin Boris S. , Avrutin Eugene A. , Kostamovaara Juha T.
Published: December 2011

A vertical cavity surface emitting laser with the active layer position detuned from the standing wave antinode is proposed for the purpose of high energy picosecond pulse generation by gain switching and analysed using numerical simulations and a fully analytical model. An optimum value of the confinement factor for high-energy pulse generation is predicted and its origins discussed.
Texture vs morphology in ZnO nano-rods: On the x-ray diffraction characterization of electrochemically grown samples
Authors: Ariosa D. , Elhordoy F. , Dalchiele E. A. , Marotti R. E. , Stari C.
Published: December 2011

Texture characterization in thin films from standard powder x-ray diffraction (XRD) rely on the comparison between observed peak relative intensities with those of powder diffraction standards of the same compound, trough the so-called texture coefficient (TC). While these methods apply for polycrystalline materials with isotropic grains, they are less accurate—and even wrong—for anisotropic materials like ZnO oriented single-crystal nano-rods, which would require the use of dedicated XRD texture setups. By using simple geometrical considerations, we succeed in discriminating between texture and morphology contributions to the observed intensity ratios in powder diffraction patterns. On this basis, we developed a method that provides a quantitative determination of both texture (polar distribution) and morphology (aspect ratio of nano-rods), using simple x-ray powder diffraction. The method is illustrated on a typical sample from a series of Zinc oxide (ZnO) nano-rod arrays grown onto a gold thin film sputtered onto a F:SnO2-coated glass substrate (FTO) by using cathodic electro-deposition. In order to check the consistency of our method, we confronted our findings with scanning electron microscope (SEM) images, grazing incidence diffraction (GID), and XRD pole-figures of the same sample. Nevertheless, the proposed method is self-consistent and only requires the use of a standard powder diffractometer, nowadays available in most solid-state laboratories.
Diversity of electronic transitions and photoluminescence properties in nanocrystalline Mn/Fe-doped tin dioxide semiconductor films: An effect from oxygen pressure
Authors: Yu W. L. , Li W. W. , Wu J. D. , Sun J. , Hu Z. G. , Chu J. H.
Published: December 2011

Transition metal (TM: Mn or Fe) doped tin dioxide (SnO2) films with the compositions of 5% (Sn0.95TM0.05O2) have been deposited on sapphire substrates by pulsed laser deposition under oxygen pressure (Po) varied from 10−4 to 1 Pa. The x-ray diffraction, scanning electron microscopy, and infrared spectra analysis show that different TM dopants can affect the variations of crystallization and lattice distortion. Moreover, x-ray photoelectron spectroscopies indicate that the effective Po during the growth does not change the valence state of Sn4+ in the Sn0.95TM0.05O2 films. The spectral behaviors of the films have been investigated in the photon energy range of 0.47-6.5 eV (2650-190 nm). From transmittance spectra, the shoulder structures become more prominent for the Sn0.95Fe0.05O2 film than those for the Sn0.95Mn0.05O2 film due to the Fe repelling effect of a stronger p-d hybridization. The refractive index values for the Sn0.95Mn0.05O2 film are found to be larger than those for the Sn0.95Fe0.05O2 film at the photon energy of 0.47 eV. The main peaks at about 1.9 and 2.2 eV in photoluminescence (PL) emission spectra for both Sn0.95Mn0.05O2 and Sn0.95Fe0.05O2 films can be observed, and it could be explained by the fact that the electrons in the conduction band of SnO2 relax to defect states and then radiatively recombine with the holes. From direct comparison of PL and transmittance results for the films, the electronic transition energies, the emission peaks’ intensities and positions are shown to present the Po dependent behavior. The distinct trends indicate that the incorporation of Mn and Fe elements can provide a significant difference in the crystalline and electronic band structure. It can be concluded that the oxygen pressure and dopant contributions are responsible for the adjustment of electronic band structures and result in different optical response behaviors for the Sn0.95TM0.05O2 films.
Multiple time scale molecular dynamics for fluids with orientational degrees of freedom. II. Canonical and isokinetic ensembles
Authors: Omelyan Igor P. , Kovalenko Andriy
Published: December 2011

We have developed several multiple time stepping techniques to overcome the limitations on efficiency of molecular dynamics simulations of complex fluids. They include the modified canonical and isokinetic schemes, as well as the extended isokinetic Nosé-Hoover chain approach. The latter generalizes the method of Minary, Tuckerman, and Martyna for translational motion [Phys. Rev. Lett. 93, 150201 (2004)]10.1103/PhysRevLett.93.150201 to systems with both translational and orientational degrees of freedom. Although the microcanonical integrators are restricted to relatively small outer time steps of order of 16 fs, we show on the basis of molecular dynamics simulations of ambient water that in the canonical and isokinetic thermostats the size of these steps can be increased to 50 and 75 fs, respectively (at the same inner time step of 4 fs). Within the generalized isokinetic Nosé-Hoover chain algorithm we have derived, huge outer time steps of order of 500 fs can be used without losing numerical stability and affecting equilibrium properties
Thermal tuning of Lamb wave band structure in a two-dimensional phononic crystal plate
Authors: Yao Yuanwei , Wu Fugen , Zhang Xin , Hou Zhilin
Published: December 2011

Using supercell-plane-wave-expansion method, we have made a theoretical study of the temperature effects on the band structure of Lamb wave in a two-dimensional phononic crystal plate. The numerical results show that the Lamb wave bandgap is very sensitive to temperature. For the case of Ba0.7Sr0.3TiO3/epoxy phononic crystal, the width of bandgap becomes narrower in a hexagonal lattice system as the temperature increases, but it becomes wider in a phononic crystal plate with square lattice. On the other hand, for the case of air/Ba0.7Sr0.3TiO3 plate with square lattice, wider and higher complete bandgap can be created in a higher temperature. These results are quite different from that in the infinite phononic crystal and one-dimensional phononic crystal plate.
Tuning of dimensionless figure of merit via boundary scattering in In2O3-δ
Authors: Kinemuchi Yoshiaki , Guilmeau Emmanuel , Lebedev Oleg I. , Maignan Antoine
Published: December 2011

In this paper, the dimensionless figure of merit (ZT) is optimized using the scattering in nanocrystals (NCs) of Zr-doped In2O3-δ. The effect of boundary scattering on the thermoelectric properties of the NCs was analyzed using the Boltzmann transport equation and Debye-Callaway model. A ZT map computed based on these theories determined the optimum material parameters to improve the transport properties of the NCs. A theoretically predicted enhancement in ZT of ∼40% can be reproduced experimentally, indicating that engineering of ZT using NCs is promising.
Differential elastic electron scattering cross sections for CCl4 by 1.5–100 eV energy electron impact
Authors: Limão-Vieira P. , Horie M. , Kato H. , Hoshino M. , Blanco F. , García G. , Buckman S. J. , Tanaka H.
Published: December 2011

We report absolute elastic differential, integral and momentum transfer cross sections for electron interactions with CCl4. The incident electron energy range is 1.5–100 eV, and the scattered electron angular range for the differential measurements varies from 15°–130°. The absolute scale of the differential cross section was set using the relative flow technique with helium as the reference species. Comparison with previous total cross sections shows good agreement. Atomic-like behaviour in this scattering system is shown here for the first time, and is further investigated by comparing the CCl4 elastic cross sections to recent results on the halomethanes and atomic chlorine at higher impact energies [H. Kato, T. Asahina, H. Masui, M. Hoshino, H. Tanaka, H. Cho, O. Ingólfsson, F. Blanco, G. Garcia, S. J. Buckman, and M. J. Brunger, J. Chem. Phys. 132, 074309 (2010)]10.1063/1.3319761.
Tunable semiconductor metamaterials based on quantum cascade laser layout assisted by strong magnetic field
Authors: Ramović Sabina , Radovanović Jelena , Milanović Vitomir
Published: December 2011

We analyze the possibilities of constructing a novel metamaterial with the arrangement of structural layers as in quantum cascade laser. The starting point is the Lorentz model of atomic electrical susceptibility. Within this model, the total permittivity consists of two terms: the first term is the averaged permittivity of the background material, while the second one is proportional to the difference of electron occupation densities of corresponding energy levels. In case of a passive configuration (where upper levels are less occupied than the lower ones), the imaginary part of this second term of permittivity is always positive. However, if the occupation of levels is inverse (active configuration), the total permittivity could be made negative (both the real and the imaginary part), which is important for design of photonic heterostructures and effective manipulation of light. A favorable candidate for illustration of these effects of advanced dispersion engineering is the quantum cascade laser in a strong magnetic field. Considerable (negative) values of the second term of permittivity may be achieved even by low carrier charge sheet densities (on the order of 109 cm−2), owing to narrow absorption linewidths and large matrix elements. Numerical results obtained for GaAs/AlGaAs quantum cascade lasers illustrate significant potential for tuning of the sign and magnitude of the real and the imaginary part of the total permittivity with magnetic field.
Fluence dependence of ion implantation-induced exchange bias in face centered cubic Co thin films
Authors: Demeter J. , Menéndez E. , Temst K. , Vantomme A.
Published: December 2011

The fluence dependence of exchange bias induced by oxygen ion implantation has been studied in highly textured face centered cubic Co films. These films exhibit a strong magnetocrystalline anisotropy prior to implantation. Upon implantation, the crystalline order is strongly reduced, even for the lowest implantation fluence, as shown by an isotropic magnetic behavior. Detailed analysis of the structural changes shows that the crystallite size remains basically unaltered upon implantation, suggesting that CoxOy is formed at the Co grain boundaries. A large suppression of the magnetocrystalline anisotropy is observed after implantation. This anisotropy has no influence on the unidirectional anisotropy associated to the exchange bias effect. Our study identifies a narrow implantation fluence window in which exchange bias by oxygen ion implantation is established. With increasing oxygen fluence, an increase in the magnitude of the exchange bias effect for higher fluences and, finally, a saturation of the exchange bias effect is observed in the studied fluence window. Moreover, the particular shape of the measured hysteresis loop is ascribed to a distribution of switching fields, which results from the implantation depth profile of oxygen throughout the Co film.
Contactless electroreflectance study of E and E + ΔSO transitions in In0.53Ga0.47BixAs1−x alloys
Authors: Kudrawiec R. , Kopaczek J. , Misiewicz J. , Petropoulos J. P. , Zhong Y. , Zide J. M. O.
Published: December 2011

Energies of E0 and E0 + ΔSO transitions in In0.53Ga0.47BixAs1−x alloys with 0 < x ≤ 0.036 have been studied by contactless electroreflectance spectroscopy at room temperature. It has been clearly observed that the E0 transition shifts to longer wavelengths (∼50 meV/% of Bi), while the E0 + ΔSO transition is approximately unchanged with changes in Bi concentration. These changes in the energies of optical transitions are discussed in the context of the valence band anticrossing model as well as the common anion rule applied to III-V semiconductors.
Effects of cryogenic temperature on dynamic fragmentation of laser shock-loaded metal foils
Authors: de Rességuier T. , Lescoute E. , Loison D. , Chevalier J. M. , Ducasse F.
Published: December 2011

Although shock-induced fracture and fragmentation of materials at low temperatures are issues of considerable interest for many applications, such as the protection from hypervelocity impacts in outer space or the ongoing development of high energy laser facilities aiming at inertial confinement fusion, little data can be found on the subject yet. In this paper, laser driven shock experiments are performed on gold and aluminum samples at both ambient and cryogenic (down to about 30 K) temperatures. Complementary techniques including transverse optical shadowgraphy, time-resolved velocity measurements, and post-recovery analyses are combined to assess the effects of target temperature upon the processes of microjetting, spallation, and dynamic punching, which are expected to govern fragments generation and ejection. The results indicate that cryogenic temperature tends to reduce the resistance to tensile and shear stresses, promotes brittle fracture, and leads to slightly higher fragments ejection velocities.
Putting Reward in Art: A Tentative Prediction Error Account of Visual Art
Authors: Van de Cruys Sander , Wagemans Johan
Published: December 2011

The predictive coding model is increasingly and fruitfully used to explain a wide range of findings in perception. Here we discuss the potential of this model in explaining the mechanisms underlying aesthetic experiences. Traditionally art appreciation has been associated with concepts such as harmony, perceptual fluency, and the so-called good Gestalt. We observe that more often than not great artworks blatantly violate these characteristics. Using the concept of prediction error from the predictive coding approach, we attempt to resolve this contradiction. We argue that artists often destroy predictions that they have first carefully built up in their viewers, and thus highlight the importance of negative affect in aesthetic experience. However, the viewer often succeeds in recovering the predictable pattern, sometimes on a different level. The ensuing rewarding effect is derived from this transition from a state of uncertainty to a state of increased predictability. We illustrate our account with several example paintings and with a discussion of art movements and individual differences in preference. On a more fundamental level, our theorizing leads us to consider the affective implications of prediction confirmation and violation. We compare our proposal to other influential theories on aesthetics and explore its advantages and limitations.
Emotional Effects of Dynamic Textures
Authors: Toet Alexander , Henselmans Menno , Lucassen Marcel P , Gevers Theo
Published: December 2011

This study explores the effects of various spatiotemporal dynamic texture characteristics on human emotions. The emotional experience of auditory (eg, music) and haptic repetitive patterns has been studied extensively. In contrast, the emotional experience of visual dynamic textures is still largely unknown, despite their natural ubiquity and increasing use in digital media. Participants watched a set of dynamic textures, representing either water or various different media, and self-reported their emotional experience. Motion complexity was found to have mildly relaxing and nondominant effects. In contrast, motion change complexity was found to be arousing and dominant. The speed of dynamics had arousing, dominant, and unpleasant effects. The amplitude of dynamics was also regarded as unpleasant. The regularity of the dynamics over the textures' area was found to be uninteresting, nondominant, mildly relaxing, and mildly pleasant. The spatial scale of the dynamics had an unpleasant, arousing, and dominant effect, which was larger for textures with diverse content than for water textures. For water textures, the effects of spatial contrast were arousing, dominant, interesting, and mildly unpleasant. None of these effects were observed for textures of diverse content. The current findings are relevant for the design and synthesis of affective multimedia content and for affective scene indexing and retrieval.
Integration of genomic information into beef cattle and sheep genetic evaluations in Australia
Authors: Swan Andrew A. , Johnston David J. , Brown Daniel J. , Tier Bruce , Graser Hans-U.
Published: December 2011

Genomic information has the potential to change the way beef cattle and sheep are selected and to substantially increase genetic gains. Ideally, genomic data will be used in combination with pedigree and phenotypic data to increase the accuracy of estimated breeding values (EBVs) and selection indexes. The first example of this in Australia was the integration of four markers for tenderness into beef cattle breeding values. Subsequently, the availability of high-density single nucleotide polymorphism (SNP) panels has made selection using genomic information possible, while at the same time creating significant challenges for genetic evaluation with regard to both data management and statistical modelling. Reference populations have been established in both the beef cattle and sheep industries, in which an extensive range of phenotypes have been collected and animals genotyped mainly using 50K SNP panels. From this information, genomic predictions of breeding value have been developed, albeit with varying levels of accuracy. These predictions have been incorporated into routine genetic evaluations using three approaches and trial results are now available to breeders. In the first, genomic predictions have been included in genetic evaluation models as additional traits. The challenges with this method have been the construction of consistent genetic covariance matrices, and a significant increase in computing time. The second approach has been to use a selection index procedure to blend genomic predictions with existing EBVs. This method has been shown to produce very similar results, and has the advantage of being simple to implement and fast to operate, although consistent genetic covariance matrices are still required. Third, in sheep a single-step analysis combining a genomic relationship matrix with a standard pedigree-based relationship matrix has been used to estimate breeding values for carcass and eating-quality traits. It is likely that this procedure or one similar will be incorporated into routine evaluations in the near future. While significant progress has been made in implementing methods of integrating genomic information in both beef and sheep evaluations in Australia, the major challenges for the future will be to continue to collect the phenotypes needed to derive accurate genomic predictions, and in managing much larger volumes of genomic data as the number of animals genotyped and the density of markers increase.
Optimal Multiwavelength Source Detection: Experience Gained from the WISE Mission
Authors: Marsh K. A. , Jarrett T. H.
Published: December 2011

We discuss the optimal detection of point sources from multiwavelength imaging data using an approach, referred to as MDET, which requires no prior knowledge of the source spectrum. MDET may be regarded as a somewhat more general version of the so-called ‘chi-squared’ technique. We describe the theoretical basis of the technique, and show examples of its performance with four-channel infrared broadband imaging data from the WISE mission. We also discuss the potential benefits of applying it to the multifrequency data cubes of the ASKAP surveys, and suggest that it could increase the detection sensitivity of searches for neutral hydrogen emission at moderately high redshifts.
Correlates of Chlamydia trachomatis infection in a primary care sentinel surveillance network
Authors: Lim Megan S. C. , Goller Jane L. , Guy Rebecca , Gold Judy , Stoove Mark , Hocking Jane S. , Fairley Christopher K. , Henning Dot , McNamee Kathy , Owen Louise , Sheehan Penny , Hellard Margaret E.
Published: December 2011

Background Chlamydia is the most commonly notified infection in Australia. Prevention strategies should be informed by routine data on at-risk populations. Methods: We calculated chlamydia positivity and correlates of infection using multivariable logistic regression for data collected between April 2006 and June 2009. Results: Chlamydia positivity was 5.6% in 12 233 females, 7.7% in 10 316 heterosexual males and 6.2% in 7872 men who have sex with men (MSM). Correlates of chlamydia positivity among females included younger age (odds ratio (OR) 2.27, 95% confidence interval (CI) 1.92–2.69), being born overseas (OR 1.50, 95% CI 1.25–1.82), multiple sex partners in the past year (OR 1.72, 95% CI 1.40–2.11) and inconsistent condom use with regular sex partners (OR 3.44 ,95% CI 1.65–7.20). Sex work was protective for females (OR 0.68, 95% CI 0.53–0.86). Among heterosexual males, correlates of positivity were younger age (OR 1.87, 95% CI 1.62–2.17), being born overseas (OR 1.35, 95% CI 1.16–1.58), symptoms at the time of testing (OR 1.64, 95% CI 1.40–1.92) and multiple sex partners in the past year (OR 1.83, 95% CI 1.46–2.30). Correlates of positivity among MSM were being born overseas (OR 1.23, 95% CI 1.00–1.51), being HIV-positive (OR 1.80, 95%CI 1.32–2.47), and reporting six or more anal sex partners in the past 6 months (OR 4.45, 95% CI 1.37–14.5). Conclusions: Our analysis identified subgroups at the highest risk of chlamydia in Victoria. These estimates will provide important baseline information to measure the impact of chlamydia control strategies.
Preferences for condom placement in stores among young Dutch men and women: relationships with embarrassment and motives for having sex
Authors: Gebhardt Winifred A. , van der Doef Margot P. , Billingy Nicole , Carstens Malou , Steenhuis Ingrid
Published: December 2011

Background Condom purchasing is an important preparation for condom use. The present study examined if products surrounding condoms in the store play a role in preferences for where to buy condoms among young people. Methods: Sixty-nine men and 111 women (<30 years) completed an online questionnaire on their preferences for condom placement, associated embarrassment with these placements, and motives for having sex. Results: Fifty percent of men and 70% of women indicated the counter as least preferred placement. Two-fifths of men and women preferred the sensual context, including among sex toys and lubricants; however, the remainder of participants, particularly women, preferred other less sexual contexts. Both the counter and sensual placement were strongly associated with embarrassment, and this, in turn, was predictive of placement preference. Finally, the motive for having sex to experience intimacy was negatively related to counter preference, and the motive for having sex to experience pleasure was negatively related to the neutral placement and the female personal care placement preferences. Conclusion: The findings suggest that using multiple and alternative placements for condoms in stores may encourage condom purchasing behaviour among young people.
Modelling the epidemiological impact of scaling up HIV testing and antiretroviral treatment in China
Authors: Zhang Lei , Gray Richard T. , Wilson David P.
Published: December 2011

Background The HIV epidemic in China has been increasing. In response, a 5-year action plan in China has prioritised the scale-up of HIV testing and treatment. Methods: We use a mathematical model to reproduce HIV epidemic trends in China and to forecast epidemic trends according to current conditions or increases in the rate of HIV testing or roll-out of antiretroviral therapy. Results: We show that the epidemic in China could be expected to experience a 2.5-fold expansion over the next 5 years such that ~1.8 million people will be infected with HIV in China by 2015. However, increasing testing and treatment rates can have substantial epidemiological benefits. For example, a four-fold increase in testing rates may avert more than 42 000 HIV infections and 11 000 deaths over the next 5years. A 10-fold increase in the treatment rate could decrease the number of HIV-related deaths by 58% and the number of new infections by one-quarter by 2015. Conclusions: Increasing HIV testing and treatment are important public health strategies for prevention.
Isolation and molecular characterisation of diazotrophic growth-promoting bacteria from wheat rhizospheric soils of Punjab
Authors: Gosal S. K. , Saroa G. S. , Vikal Y. , Cameotra S. S. , Pathania Neemisha , Bhanot A.
Published: December 2011

Diazotrophs are nitrogen-fixing bacteria which possess the nifH gene that codes for the nitrogenase enzyme involved in reduction of atmospheric dinitrogen to ammonia. Seventy-two diazotrophic bacteria were isolated using eight nitrogen-free media from wheat rhizospheric soil. The diazotrophic population was found to be negatively related to soil nitrogen, whereas a positive correlation was observed with organic carbon and electrical conductivity of soil. The isolates were initially identified on the basis of cultural, morphological, and biochemical characterisation. Various diazotrophic isolates were screened for functional activities. Thirty-seven isolates were acetylene reduction assay positive, among which 28 isolates exhibited nitrogenase activity ranging from 22.3 to 72.0 nmol C2H4/h. The majority of isolates were able to produce indole acetic acid ranging from 11.2 to 23.0 µg/mL and only a few diazotrophs could solubilise phosphate. These isolates showed amplification with two nifH primers (nifH1 and nifH2), thereby confirming their diazotrophic potential. The positive nifH isolates were further characterised using restriction fragment length polymorphism of 16S rDNA to reveal diversity among them. Based on UPGMA clustering and partial sequencing of 16S rDNA, the isolates were identified as Azotobacter sp., Azospirillum sp., Stenotrophomonas maltophilia, Stenotrophomonas sp., Sphingomonas paucimobilis, Rhizobium larrymoorei, Pseudomonas aeruginosa, and Xanthomonas oryzae.
Impacts of Adfluvial Fish on the Ecology of Two Great Lakes Tributaries
Authors: Ivan Lori N. , Rutherford Edward S. , Johengen Thomas H.
Published: December 2011

Anadromous and adfluvial fish can transport high concentrations of nutrients and energy into streams during spawning runs. While the ecological effects of their spawning migrations are variable, in some instances these fish contribute to increased nutrient concentrations, primary productivity, invertebrate biomass, and resident fish growth and survival in the nutrient‐poor streams of the Pacific Northwest. In tributaries of the Great Lakes, the effects of introduced salmonid and native adfluvial fish are poorly documented. We conducted field experiments to determine the effects of a semelparous fall fish, Chinook salmon Oncorhynchus tshawytscha, and an iteroparous spring fish, steelhead O. mykiss, on the ecology and productivity of two tributaries to the Muskegon River, Michigan, a Lake Michigan tributary. We sampled stream biota and water chemistry before and after the introduction of Chinook salmon carcasses and eggs in the fall and steelhead eggs in the spring in a tributary stream with natural spawning runs and in another tributary stream without runs but with carcass and egg additions. There was no response in terms of invertebrate density or water chemistry to spawning migrations or salmon carcass introductions in either tributary. The density of resident brown trout Salmo trutta increased in both stream types after the introduction of salmon carcasses in the fall, and energy consumption increased after the addition of salmon eggs in the fall and spring in the manipulated stream. Based on stomach content analysis, fish that had eggs in their stomachs also consumed more energy than fish that did not consume eggs. The results suggest that adfluvial fish may affect some tributaries of the Great Lakes by providing high‐energy food sources to resident stream fish, but the potential effect of this egg consumption on resident fish growth and survival requires more research.
Concentration of Infectious Aquatic Rhabdoviruses from Freshwater and Seawater Using Ultrafiltration
Authors: Grant Amelia A. M. , Jakob Eva , Richard Jon , Garver Kyle A.
Published: December 2011

Infectious hematopoietic necrosis virus (IHNV), viral hemorrhagic septicemia virus, and spring viremia of carp virus were concentrated and detected from freshwater and seawater samples by using hollow-fiber ultrafiltration. Within 60 min, virus in a 50-L freshwater or saltwater sample was concentrated more than 70-fold, and virus retention efficiencies were consistently greater than 88%. Retention efficiency was highly dependent upon concentrations of column blocking and sample stabilization solutions. A large column with a surface area of 1.15 m2 and a filtration capacity of 5–200 L exhibited optimal viral retention when blocked with 2% fetal bovine serum (FBS) and when the samples were supplemented with 0.1% FBS. Conversely, a small column with 100-fold less surface area and a filtering capacity of 0.5–2.0 L was optimized when blocked with 1% FBS and when the samples were supplemented with 0.1% FBS. The optimized ultrafiltration procedure was further validated with water from a tank that contained IHNV-exposed juvenile sockeye salmon Oncorhynchus nerka, resulting in an average virus retention efficiency of 91.6 ± 4.1% (mean ± SE). Virus quantification of concentrated samples demonstrated that IHNV shedding in sockeye salmon preceded mortality; shedding of the virus was observed to increase significantly as early as 7 d postchallenge and peaked at day 14, when virus levels reached 4.87 × 103 plaque-forming units/mL. We conclude that ultrafiltration is a reliable and effective method for concentrating viable aquatic rhabdoviruses from large volumes of water and has application for the analysis of environmental water samples.

Received April 22, 2011; accepted August 4, 2011
Stimulus velocity effect in a complex interceptive task in right‐ and left‐handers
Authors: Rodrigues Paula C. , Barbosa Ricardo , Carita Ana Isabel , Barreiros João , Vasconcelos Olga
Published: December 2011

This study investigated stimulus velocity effect on manual asymmetry during planning and execution of a complex coincidence‐anticipation task. Left‐ and right‐handers were required to press six buttons sequentially in conjunction with visual stimulus provided by a coincidence‐anticipation device. Results showed that (1) stimulus velocity affected timing response and timing accuracy only for right‐handers, who responded faster but less accurately in the fast stimulus velocity, (2) manual asymmetries for both handedness groups revealed a left‐hand advantage for initiating the movement, and a preferred‐hand advantage for movement time. The preferred‐hand advantage in timing accuracy was only observed in the fast stimulus velocity. These findings are discussed in the framework of the hemispheric functional lateralisation.
Combustion synthesis and characterization of Er3+-doped and Er3+, Yb3+-codoped YVO4 nanophosphors oriented for luminescent biolabeling applications
Authors: Nguyen Vu , Chi Tran Thi Kim , Nguyen Duc Van
Published: December 2011

YVO
4:Er
3+ and YVO
4:Er
3+, Yb
3+ nanomaterials were prepared via combustion synthesis using urea as fuel and metal nitrates as precursor. The morphology and the structure of the prepared samples were characterized by x-ray diffraction, scanning electron microscopy and transmission electron microscopy. The average size of the prepared materials ranged from 20 to 30 nm in diameter. The effects of Er
3+ and Yb
3+ doping concentrations on structure and optical properties have been investigated. Optical properties of YVO
4:Er
3+ and YVO
4:Er
3+, Yb
3+ nanoparticles were measured by photoluminescent excitation and emission spectroscopies. For the YVO
4:Er
3+ and YVO
4:Er
3+, Yb
3+ samples, two strong green emissions centered at 524 and 552 nm are found, corresponding to the 2
H
11/2—4
I
15/2 and 4
S
11/2—4
I
15/2 transitions of Er
3+ ions, respectively. Upconversion emission in the green region of the YVO
4:Er
3+ nanoparticles under 980 nm excitation was also investigated. Strong emission from these materials is promising for luminescent biolabeling applications.
Cohesin-independent segregation of sister chromatids in budding yeast
Authors: Guacci Vincent , Koshland Douglas
Published: December 2011

Cohesin generates cohesion between sister chromatids, which enables chromosomes to form bipolar attachments to the mitotic spindle and segregate. Cohesin also functions in chromosome condensation, transcriptional regulation, and DNA damage repair. Here we analyze the role of acetylation in modulating cohesin functions and how it affects budding yeast viability. Previous studies show that cohesion establishment requires Eco1p-mediated acetylation of the cohesin subunit Smc3p at residue K113. Smc3p acetylation was proposed to promote establishment by merely relieving Wpl1p inhibition because deletion of WPL1 bypasses the lethality of an ECO1 deletion (eco1Δ wpl1Δ). We find that little, if any, cohesion is established in eco1Δ wpl1Δ cells, indicating that Eco1p performs a function beyond antagonizing Wpl1p. Cohesion also fails to be established when SMC3 acetyl-mimics (K113Q or K112R,K113Q) are the sole functional SMC3s in cells. These results suggest that Smc3p acetylation levels affect establishment. It is remarkable that, despite their severe cohesion defect, eco1Δ wpl1Δ and smc3-K112R,K113Q strains are viable because a cohesin-independent mechanism enables bipolar attachment and segregation. This alternative mechanism is insufficient for smc3-K113Q strain viability. Smc3-K113Q is defective for condensation, whereas eco1Δ wpl1Δ and smc3-K112R,K113Q strains are competent for condensation. We suggest that Smc3p acetylation and Wpl1p antagonistically regulate cohesin's essential role in condensation.
Combined use of high‐sensitivity ST2 and NTproBNP to improve the prediction of death in heart failure
Authors: Bayes‐Genis Antoni , de Antonio Marta , Galán Amparo , Sanz Héctor , Urrutia Agustin , Cabanes Roser , Cano Lucía , González Beatriz , Díez Cristanto , Pascual Teresa , Elosúa Roberto , Lupón Josep
Published: December 2011

Aims

To address the incremental usefulness of biomarkers from different disease pathways for predicting risk of death in heart failure (HF).

Methods and results

We used data from consecutive patients treated at a structured multidisciplinary HF unit to investigate whether a combination of biomarkers reflecting ventricular fibrosis, remodelling, and stretch [ST2 and N‐terminal pro brain natriuretic peptide (NTproBNP)] improved the risk stratification of a HF patient beyond an assessment based on established mortality risk factors (age, sex, ischaemic aetiology, left ventricular ejection fraction, New York Heart Association functional class, diabetes, glomerular filtration rate, sodium, haemoglobin, and beta‐blocker and angiotensin‐converting enzyme inhibitor/angiotensin II receptor blocker treatments). ST2 was measured with a novel high‐sensitivity immunoassay. During a median follow‐up time of 33.4 months, 244 of the 891 participants in the study (mean age 70.2 years at baseline) died. In the multivariable Cox proportional hazards model, both ST2 and NTproBNP significantly predicted the risk of death. The individual inclusion of ST2 and NTproBNP in the model with established mortality risk factors significantly improved the C statistic for predicting death [0.79 (0.76–0.81); P < 0.001]. The net improvement in reclassification after the separate addition of ST2 to the model with established risk factors and NTproBNP was estimated at 9.90% [95% confidence interval (CI) 4.34–15.46; P < 0.001] and the integrated discrimination improvement at 1.54 (95% CI 0.29–2.78); P = 0.015).

Conclusions

Our data suggest that in a real‐life cohort of HF patients, the addition of ST2 and NTproBNP substantially improves the risk stratification for death beyond that of a model that is based only on established mortality risk factors.
The European CRT Survey: 1 year (9–15 months) follow‐up results
Authors: Bogale Nigussie , Priori Silvia , Cleland John G.F. , Brugada Josep , Linde Cecilia , Auricchio Angelo , van Veldhuisen Dirk J. , Limbourg Tobias , Gitt Anselm , Gras Daniel , Stellbrink Christoph , Gasparini Maurizio , Metra Marco , Derumeaux Geneviève , Gadler Fredrik , Buga Laszlo , Dickstein Kenneth ,   on behalf of the Scientific Committee, National Coordinators, and Investigators
Published: December 2011

Aims

The European CRT Survey is a joint initiative of the Heart Failure Association (HFA) and the European Heart Rhythm Association (EHRA) of the European Society of Cardiology evaluating the contemporary implantation practice of cardiac resynchronization therapy (CRT) in Europe.

Methods and results

Patients who had a successful CRT implantation were enrolled from 141 centres in 13 countries between November 2008 and June 2009. Baseline demographics, clinical and implantation data were collected, with a follow‐up of ∼1 year (9–15 months). The current report describes clinical outcomes including symptom severity, cardiovascular (CV) hospitalization, and survival. A total of 2438 patients were enrolled, and follow‐up data were acquired from 2111 patients (87%). The population included important groups of patients poorly represented in randomized controlled trials, including very elderly patients and those with prior device implantation, atrial fibrillation, and/or QRS duration <120 ms. Investigators reported substantial improvement in New York Heart Association (NYHA) functional class at follow‐up. Patient self‐assessment indicated that 81% of the patients felt improved, 16% reported no change, and 4% reported deterioration. During follow‐up, 207 (10%) patients died, 346 (16%) had a CV hospitalization, and 501 (24%) died or had CV hospitalization. Worse NYHA functional class, atrial fibrillation, ischaemic aetiology, and device type (CRT‐P, i.e. CRT alone) were associated with poorer survival. Women had a better outcome, as did patients who had a CRT‐D (with an implantable cardioverter defibrillator function) device.

Conclusions

Outcomes including death and hospitalization in this European CRT survey were consistent with results from clinical trials of CRT. At 1 year follow‐up, most patients who received a CRT device considered their symptoms improved compared with their pre‐implant assessment. Although prospective, this is an observational study of successful CRT implantations, and outcomes in subgroup analyses must be interpreted with appropriate conservatism.

Clinical study no: NCT 01185392
Hydrodynamic principles of wave power extraction
Authors: Mei Chiang C.
Published: December 2011

The hydrodynamic principles common to many wave power converters are reviewed via two representative systems. The first involves one or more floating bodies, and the second water oscillating in a fixed enclosure. It is shown that the prevailing basis is impedance matching and resonance, for which the typical analysis can be illustrated for a single buoy and for an oscillating water column. We then examine the mechanics of a more recent design involving a compact array of small buoys that are not resonated. Its theoretical potential is compared with that of a large buoy of equal volume. A simple theory is also given for a two-dimensional array of small buoys in well-separated rows parallel to a coast. The effects of coastline on a land-based oscillating water column are examined analytically. Possible benefits of moderate to large column sizes are explored. Strategies for broadening the frequency bandwidth of high efficiency by controlling the power-takeoff system are discussed.
Key features of wave energy
Authors: Rainey R. C. T.
Published: December 2011

For a weak point source or dipole, or a small body operating as either, we show that the power from a wave energy converter (WEC) is the product of the particle velocity in the waves, and the wave force (suitably defined). There is a thus a strong analogy with a wind or tidal turbine, where the power is the product of the fluid velocity through the turbine, and the force on it. As a first approximation, the cost of a structure is controlled by the force it has to carry, which governs its strength, and the distance it has to be carried, which governs its size. Thus, WECs are at a disadvantage compared with wind and tidal turbines because the fluid velocities are lower, and hence the forces are higher. On the other hand, the distances involved are lower. As with turbines, the implication is also that a WEC must make the most of its force-carrying ability—ideally, to carry its maximum force all the time, the ‘100% sweating WEC’. It must be able to limit the wave force on it in larger waves, ultimately becoming near-transparent to them in the survival condition—just like a turbine in extreme conditions, which can stop and feather its blades. A turbine of any force rating can achieve its maximum force in low wind speeds, if its diameter is sufficiently large. This is not possible with a simple monopole or dipole WEC, however, because of the ‘
nλ
/2
π
’ capture width limits. To achieve reasonable ‘sweating’ in typical wave climates, the force is limited to about 1 MN for a monopole device, or 2 MN for a dipole. The conclusion is that the future of wave energy is in devices that are not simple monopoles or dipoles, but multi-body devices or other shapes equivalent to arrays.