bluuebunny/crossref_metadata_2025 huggingface dataset:
Excess protons in water-acetone mixtures. II. A conductivity study
Authors: Semino Rocío , Longinotti M. Paula
Published: October 2013

In the present work we complement a previous simulation study [R. Semino and D. Laria, J. Chem. Phys. 136, 194503 (2012)] on the disruption of the proton transfer mechanism in water by the addition of an aprotic solvent, such as acetone. We provide experimental measurements of the mobility of protons in aqueous-acetone mixtures in a wide composition range, for water molar fractions, xw, between 0.05 and 1.00. Furthermore, new molecular dynamics simulation results are presented for rich acetone mixtures, which provide further insight into the proton transport mechanism in water-non-protic solvent mixtures. The proton mobility was analyzed between xw 0.05 and 1.00 and compared to molecular dynamics simulation data. Results show two qualitative changes in the proton transport composition dependence at xw ∼ 0.25 and 0.8. At xw < 0.25 the ratio of the infinite dilution molar conductivities of HCl and LiCl, Λ0HCl.Λ0LiCl−1, is approximately constant and equal to one, since the proton diffusion is vehicular and equal to that of Li+. At xw ∼ 0.25, proton mobility starts to differ from that of Li+ indicating that above this concentration the Grotthuss transport mechanism starts to be possible. Molecular dynamics simulation results showed that at this threshold concentration the probability of interconversion between two Eigen structures starts to be non-negligible. At xw ∼ 0.8, the infinite molar conductivity of HCl concentration dependence qualitatively changes. This result is in excellent agreement with the analysis presented in the previous simulation work and it has been ascribed to the interchange of water and acetone molecules in the second solvation shell of the hydronium ion.
Efficient continuous-duty Bitter-type electromagnets for cold atom experiments
Authors: Sabulsky Dylan O. , Parker Colin V. , Gemelke Nathan D. , Chin Cheng
Published: October 2013

We present the design, construction, and characterization of Bitter-type electromagnets which can generate high magnetic fields under continuous operation with efficient heat removal for cold atom experiments. The electromagnets are constructed from a stack of alternating layers consisting of copper arcs and insulating polyester spacers. Efficient cooling of the copper is achieved via parallel rectangular water cooling channels between copper layers with low resistance to flow; a high ratio of the water-cooled surface area to the volume of copper ensures a short length scale (∼1 mm) to extract dissipated heat. High copper fraction per layer ensures high magnetic field generated per unit energy dissipated. The ensemble is highly scalable and compressed to create a watertight seal without epoxy. From our measurements, a peak field of 770 G is generated 14 mm away from a single electromagnet with a current of 400 A and a total power dissipation of 1.6 kW. With cooling water flowing at 3.8 l/min, the coil temperature only increases by 7 °C under continuous operation.
Effect of image charge on the off-axis transport of intense beams in a small aperture quadrupole lattice
Authors: Goswami A. , Sing Babu P. , Pandit V. S.
Published: October 2013

This paper investigates the first order image charge effects of circular conducting pipe on an intense off-axis continuous charged particle beam propagating through an alternating-gradient focusing channel. The equations of motion for the centroid and envelopes of slightly off-axis beam are derived and used to determine the equilibrium and stability conditions for the beam transport. The envelope oscillation frequencies of the mismatched beam are obtained by the smooth approximation method and by numerical evaluation of the linearly perturbed envelope equations. Depending on the beam intensity and focusing parameters, it is found that the frequency of the out-of-phase mode of envelope oscillation is reduced due to the presence of the conducting wall. Detailed numerical results for off-axis beam transport in a quadrupole lattice are presented and the stable regimes in the parameter space are determined numerically. It is observed that the unstable region for the envelope evolution with image charge effects depends on beam intensity and external focusing strength and increases with the off centering of the beam.
Interdiffusion of Ni-Al multilayers: A continuum and molecular dynamics study
Authors: Xu Rong-Guang , Falk Michael L. , Weihs Timothy P.
Published: October 2013

Molecular dynamics simulation of Al/Ni multilayer foils reveals a range of different reaction pathways depending on the temperature of the reaction. At the highest temperatures, Fickian interdiffusion is the rate-limiting step in the intermixing process. At intermediate temperatures, Ni dissolution into the Al liquid becomes the rate-limiting mechanism for intermixing prior to formation of the B2 intermetallic phase. At lower temperatures, the B2 intermetallic forms early in the reaction process precluding both of these mechanisms. Interdiffusion and dissolution activation energies as well as diffusion prefactors are extracted from the simulations.
Efficient and accurate treatment of weak pairs in local CCSD(T) calculations
Authors: Masur Oliver , Usvyat Denis , Schütz Martin
Published: October 2013

Local coupled cluster theory is based on (i) a restriction of the list of pairs (or triples) of occupied molecular orbitals, and (ii) a truncation of the virtual space to orbital pair (or triple) specific subspaces. The latter is motivated by an exponential decay of the contributions to the pair energy with respect to the distance between related local occupied and virtual orbitals; the former only by a polynomial R−6 decay with respect to the distance R between the two occupied orbitals of the pair. Consequently, the restriction of the pair list is more critical, and contributions of pairs should not be neglected unless the corresponding interorbital distance is really large. In local coupled cluster theory pairs are usually discriminated on the basis of the interorbital distance, or the size of the 2nd order Møller-Plesset perturbation theory (MP2) estimate of the pair energy. Only strong pairs are treated at the full coupled cluster level, while weak pairs are treated just at the level of MP2. Yet MP2 might be problematic in certain cases, for example, π-stacking is badly described by MP2, etc. We propose to substitute the MP2 treatment of weak pairs by an approach based on ring-CCD by including third-order diagrams with R−6 decay behavior. Such an approach is clearly superior; it provides higher accuracy, while the computational cost is not significantly higher than that of a MP2 based treatment of weak pairs.
Transverse distribution of beam current oscillations of a 14 GHz electron cyclotron resonance ion source
Authors: Tarvainen O. , Toivanen V. , Komppula J. , Kalvas T. , Koivisto H.
Published: October 2013

The temporal stability of oxygen ion beams has been studied with the 14 GHz A-ECR at JYFL (University of Jyvaskyla, Department of Physics). A sector Faraday cup was employed to measure the distribution of the beam current oscillations across the beam profile. The spatial and temporal characteristics of two different oscillation “modes” often observed with the JYFL 14 GHz ECRIS are discussed. It was observed that the low frequency oscillations below 200 Hz are distributed almost uniformly. In the high frequency oscillation “mode,” with frequencies >300 Hz at the core of the beam, carrying most of the current, oscillates with smaller amplitude than the peripheral parts of the beam. The results help to explain differences observed between the two oscillation modes in terms of the transport efficiency through the JYFL K-130 cyclotron. The dependence of the oscillation pattern on ion source parameters is a strong indication that the mechanisms driving the fluctuations are plasma effects.
Ultraviolet detection from graphitic-C/Zn1−xMgxO Schottky devices fabricated at moderate temperatures
Authors: Mayes E. L. H. , McCulloch D. G. , Partridge J. G.
Published: October 2013

Ultraviolet (UV) Schottky detector devices were fabricated on polycrystalline wurtzite Zn1−xMgxO films energetically deposited onto a-plane sapphire at room-temperature (RT) and 200 °C. The unintentionally doped, transparent, n-Zn1−xMgxO films exhibit low surface roughness (<5% of film thickness), moderate carrier concentration, and Hall mobility up to 15 cm2 V−1 s−1. The direct bandgaps of the RT and 200 °C films (x = 0.24 and x = 0.20) were 3.57 eV and 3.40 eV. Schottky diodes with graphitic anodes formed on these films exhibited barrier heights up to 0.88 eV and ideality factors as low as 1.97. Spectral response measurements demonstrated UV/visible photo-current ratios up to ∼104.
Fabricatable nanopore sensors with an atomic thickness
Authors: Luan Binquan , Bai Jingwei , Stolovitzky Gustavo
Published: October 2013

When analyzing biological molecules (such as DNA and proteins) transported through a nanopore sensor, the pore length limits both the sensitivity and the spatial resolution. Atomically thin as a graphene nanopore is, it is difficult to make graphene pores and the scalable-fabrication of those pores has not yet been possible. We theoretically studied a type of atomically thin nanopores that are formed by intersection of two perpendicular nano-slits. Based on theoretical analyses, we demonstrate that slit nanopores behave similarly to graphene pores and can be manufactured at a wafer scale.
Comprehensive study of the influence of different environments on degradation processes in F8BT: Correlating optoelectronic properties with Raman measurements
Authors: Linde Sivan , Shikler Rafi
Published: October 2013

There is a growing interest in conjugated polymers from both industrial and academic points of views. The reasons are their tunable optoelectronic properties, ease of production, and excellent mechanical properties. However, the ease with which their optoelectronic properties are tunable make devices based on them prone to fast degradation and therefore, short life time. The issue of degradation of organic based optoelectronic devices is the topic of many ongoing researches. However, much less attention is given to degradation processes of the individual components of the devices and their dependence on the environmental conditions. In this work, we report on the degradation of a film of a polyfluorene block copolymer F8BT that is used in a variety of optoelectronic devices under different environments: Sun exposure, heating, and UV exposure in inert and ambient conditions. Degradation was observed in most of the optoelectronic properties of the film. Topographic measurements did not show observable changes of the film morphology following degradation. However, Raman spectroscopy measurements show changes that indicate degradation in one of the building blocks of the copolymer that is associated with electron's conduction. The absolute value of the correlation coefficient between the decrease in the Raman signal and the decrease in the optoelectronic properties is larger than 0.95 under sun exposure it is larger than 0.8 under all other ambient exposures and smaller than 0.65 under inert conditions. These results support the assumption that Oxygen, not necessarily through photo-oxidation, and also water play an important role in the degradation process and indicate the part of the polymer that is most susceptible to degradation.
Physical understanding of different drain-induced-barrier-lowering variations in high-k/metal gate n-channel metal-oxide-semiconductor-field-effect-transistors induced by charge trapping under normal and reverse channel hot carrier stresses
Authors: Luo Weichun , Yang Hong , Wang Wenwu , Zhao Lichuan , Xu Hao , Ren Shangqing , Tang Bo , Tang Zhaoyun , Xu Yefeng , Xu Jing , Yan Jiang , Zhao Chao , Chen Dapeng , Ye Tianchun
Published: October 2013

In this paper, the drain induced barrier lowering (DIBL) variations in High-k/Metal gate n-channel metal–oxide–semiconductor field effect transistor under the normal and reverse channel hot carrier (CHC) stress are studied. It is found that DIBL decreases under normal CHC stress mode while increases under reverse CHC mode. The different DIBL variation under normal and reverse CHC stresses is proposed to be attributed to stress-induced charge trapping by cold carriers from the channel rather than hot carriers from the pinch off region, which can be explained by energy band bending theory.
Highly efficient coupling from an optical fiber to a nanoscale silicon optomechanical cavity
Authors: Gröblacher Simon , Hill Jeff T. , Safavi-Naeini Amir H. , Chan Jasper , Painter Oskar
Published: October 2013

We demonstrate highly efficient coupling of light from an optical fiber to a silicon photonic crystal optomechanical cavity. The fiber-to-cavity coupling utilizes a compact (L ≈ 25 μm) intermediate adiabatic coupler. The optical coupling is lithographically controlled, broadband, relatively insensitive to fiber misalignment and allows for light to be transferred from an optical fiber to, in principle, any photonic chip with refractive index greater than that of the optical fiber. Here we demonstrate single-sided cavity coupling with a total fiber-to-cavity optical power coupling efficiency of 85%.
Ag-assisted lateral etching of Si nanowires and its application to nanowire transfer
Authors: Li Chuanbo , Fobelets Kristel , Liu Chang , Xue Chunlai , Cheng Buwen , Wang Qiming
Published: October 2013

Ag-assisted anisotropic lateral etching along the ⟨100⟩ directions in Si nanowire arrays (Si NWAs) is investigated. It is found that Ag ions, generated by H2O2 oxidation of Ag particles, re-nucleate on the sidewalls of the nanowires, causing side etching and tapering of the wires. By enhancing the side etching effect, fractures can be formed at specific positions along the nanowires. This technique is applied to transfer large-area Si NWAs onto a glass substrate.
Detecting ionizing radiation with optical fibers down to biomedical doses
Authors: Avino S. , D'Avino V. , Giorgini A. , Pacelli R. , Liuzzi R. , Cella L. , De Natale P. , Gagliardi G.
Published: October 2013

We report on a passive ionizing radiation sensor based on a fiber-optic resonant cavity interrogated by a high resolution interferometric technique. After irradiation in clinical linear accelerators, we observe significant variations of the fiber thermo-optic coefficient. Exploiting this effect, we demonstrate an ultimate detection limit of 160 mGy with an interaction volume of only 6 × 10−4 mm3. Thanks to its reliability, compactness, and sensitivity at biomedical dose levels, our system lends itself to real applications in radiation therapy procedures as well as in radiation monitoring and protection in medicine, aerospace, and nuclear power plants.
Higher-order harmonic effect of a three-dimensional helical wiggler on the Larmor rotation of the equilibrium electrons in a free-electron laser with a positive or a reversed guide magnetic field
Authors: Zhang Shi-Chang
Published: October 2013

Analytical formulas of the Larmor rotation are derived in detail for the equilibrium electrons motion in a free-electron laser with combination of a three-dimensional (3-D) helical wiggler and a positive or a reversed guide magnetic field. Generally, the Larmor radius in the configuration of a reversed guide field is much smaller than that in a positive guide field. At non-resonance, a helical orbit governed by the zero-order component of a 3-D wiggler field could hold; meanwhile, the higher-harmonic effect definitely influences those electrons with off-axis guiding centers and induces the electron-beam spreads. At resonance, the Larmor radius in the configuration of a positive guide field has a singularity with a limit tending to infinite, which causes all the electrons to hit the waveguide wall before the exit of the wiggler. Although Larmor-radius singularity does not exist in the configuration of a reversed guide field, at anti-resonance, the first-order harmonic of a 3-D wiggler field induces a transverse displacement which rapidly grows in proportion to a square of time, and leads part of the electron beam to hit the waveguide wall before reaching the wiggler exit, which depends on the specific parameters of the individual electrons. The analytical conclusions derived in the present paper are examined by the nonlinear simulations and the experimental observation. Disagreement with the previous literatures is discussed in detail.
Similarity theory of lubricated Hertzian contacts
Authors: Snoeijer J. H. , Eggers J. , Venner C. H.
Published: October 2013

We consider a heavily loaded, lubricated contact between two elastic bodies at relative speed U, such that there is substantial elastic deformation. As a result of the interplay between hydrodynamics and non-local elasticity, a fluid film develops between the two solids, whose thickness scales as U3/5. The film profile h is selected by a universal similarity solution along the upstream inlet. Another similarity solution is valid at the outlet, which exhibits a local minimum in the film thickness. The two solutions are connected by a hyperbolic problem underneath the contact. Our asymptotic results for a soft sphere pressed against a hard wall are shown to agree with both experiment and numerical simulations.
Note: Complementary metal–oxide–semiconductor high voltage pulse generation circuits
Authors: Sun Jiwei , Wang Pingshan
Published: October 2013

We present two types of on-chip pulse generation circuits. The first is based on CMOS pulse-forming-lines (PFLs). It includes a four-stage charge pump, a four-stacked-MOSFET switch and a 5 mm long PFL. The circuit is implemented in a 0.13 μm CMOS process. Pulses of ∼1.8 V amplitude with ∼135 ps duration on a 50 Ω load are obtained. The obtained voltage is higher than 1.6 V, the rated operating voltage of the process. The second is a high-voltage Marx generator which also uses stacked MOSFETs as high voltage switches. The output voltage is 11.68 V, which is higher than the highest breakdown voltage (∼10 V) of the CMOS process. These results significantly extend high-voltage pulse generation capabilities of CMOS technologies.
Efficiency enhancement of polymer solar cells by localized surface plasmon of Au nanoparticles
Authors: Gao H. L. , Zhang X. W. , Yin Z. G. , Zhang S. G. , Meng J. H. , Liu X.
Published: October 2013

We demonstrate the improvement of power conversion efficiency (PCE) in bulk heterojunction polymer solar cells based on blended poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester by introducing 40 nm Au nanoparticles (NPs) with various concentrations. The Au NPs were deposited on indium-tin-oxide (ITO) substrates by spin-coating from colloidal solution prior to deposition of poly (3,4-ethylene dioxythiophene:poly (styrene sulfonate) (PEDOT:PSS) buffer layer. It has been found that both short-circuit current density and PCE increase after incorporating Au NPs between ITO and PEDOT:PSS layer, and a suitable area density of Au NPs is required to achieve a maximum enhancement of device efficiency. The PCE of solar cells has been increased from 3.50% to 3.81% with 0.9 wt. % Au NPs. The PCE enhancement is attributed to the localized surface plasmon excitation of Au NPs. The method employed herein is a kind of simple and convenient solution process, and it has great potential in future practical applications.
Fixed charge and trap states of in situ Al2O3 on Ga-face GaN metal-oxide-semiconductor capacitors grown by metalorganic chemical vapor deposition
Authors: Liu X. , Kim J. , Yeluri R. , Lal S. , Li H. , Lu J. , Keller S. , Mazumder B. , Speck J. S. , Mishra U. K.
Published: October 2013

In situ Al2O3 on Ga-face GaN metal-oxide-semiconductor capacitors (MOSCAPs) were grown by metalorganic chemical vapor deposition and measured using capacitance-voltage techniques. The flat band voltage and hysteresis had a linear relationship with Al2O3 thickness, which indicates the presence of fixed charge and trap states that are located at or near the Al2O3/GaN interface. In addition, slow and fast near-interface states are distinguished according to their different electron emission characteristics. Atom probe tomography was used to characterize the in situ MOSCAPs to provide information on the Al/O stoichiometric ratios, Al2O3/GaN interface abruptnesses, and C concentrations. The in situ MOSCAPs with Al2O3 deposited at 700 °C exhibited an order of magnitude higher fast near-interface states density but a lower slow near-interface states density compared with those with Al2O3 deposited at 900 and 1000 °C. Furthermore, the 700 °C MOSCAPs exhibited a net negative fixed near-interface charge, whereas the 900 and 1000 °C MOSCAPs exhibited net positive fixed near-interface charges. The possible origins of various fixed charge and trap states are discussed in accordance with the experimental data and recently reported first-principals calculations.
Characteristics of AlN/GaN nanowire Bragg mirror grown on (001) silicon by molecular beam epitaxy
Authors: Heo Junseok , Zhou Zifan , Guo Wei , Ooi Boon S. , Bhattacharya Pallab
Published: October 2013

GaN nanowires containing AlN/GaN distributed Bragg reflector (DBR) heterostructures have been grown on (001) silicon substrate by molecular beam epitaxy. A peak reflectance of 70% with normal incidence at 560 nm is derived from angle resolved reflectance measurements on the as-grown nanowire DBR array. The measured peak reflectance wavelength is significantly blue-shifted from the ideal calculated value. The discrepancy is explained by investigating the reflectance of the nanoscale DBRs with a finite difference time domain technique. Ensemble nanowire microcavities with In0.3Ga0.7N nanowires clad by AlN/GaN DBRs have also been characterized. Room temperature emission from the microcavity exhibits considerable linewidth narrowing compared to that measured for unclad In0.3Ga0.7N nanowires. The resonant emission is characterized by a peak wavelength and linewidth of 575 nm and 39 nm, respectively.
Dynamics of laser-guided alternating current high voltage discharges
Authors: Daigle J.-F. , Théberge F. , Lassonde P. , Kieffer J.-C. , Fujii T. , Fortin J. , Châteauneuf M. , Dubois J.
Published: October 2013

The dynamics of laser-guided alternating current high voltage discharges are characterized using a streak camera. Laser filaments were used to trigger and guide the discharges produced by a commercial Tesla coil. The streaking images revealed that the dynamics of the guided alternating current high voltage corona are different from that of a direct current source. The measured effective corona velocity and the absence of leader streamers confirmed that it evolves in a pure leader regime.
High yield fabrication of multilayer polydimethylsiloxane devices with freestanding micropillar arrays
Authors: Gregory Christopher W. , Sellgren Katelyn L. , Gilchrist Kristin H. , Grego Sonia
Published: October 2013

A versatile method to fabricate a multilayer polydimethylsiloxane (PDMS) device with micropillar arrays within the inner layer is reported. The method includes an inexpensive but repeatable approach for PDMS lamination at high compressive force to achieve high yield of pillar molding and transfer to a temporary carrier. The process also enables micropillar-containing thin films to be used as the inner layer of PDMS devices integrated with polymer membranes. A microfluidic cell culture device was demonstrated which included multiple vertically stacked flow channels and a pillar array serving as a cage for a collagen hydrogel. The functionality of the multilayer device was demonstrated by culturing collagen-embedded fibroblasts under interstitial flow through the three-dimensional scaffold. The fabrication methods described in this paper can find applications in a variety of devices, particularly for organ-on-chip applications.
Surface passivation of n-type c-Si wafers by a-Si/SiO2/SiNx stack with <1 cm/s effective surface recombination velocity
Authors: Herasimenka Stanislau Y. , Tracy Clarence J. , Sharma Vivek , Vulic Natasa , Dauksher William J. , Bowden Stuart G.
Published: October 2013

The passivation quality of an a-Si/SiO2/SiNx (aSON) stack deposited by conventional PECVD at <250 °C with and without additional corona charging of SiNx is presented. <2 fA/cm2 surface dark saturation current density and <1 cm/s effective surface recombination velocity were demonstrated on both planar and textured n-type Czochralski (CZ) substrates. It was shown that very good passivation can be achieved using <5 nm a-Si layers to provide low parasitic absorption. We also report effective minority carrier lifetimes >60 ms on 5000 Ω-cm and 20.9 ms on 1.7 Ω-cm mirror polished float zone (FZ) material passivated with aSON stacks.
Trap density of states in n-channel organic transistors: variable temperature characteristics and band transport
Authors: Cho Joung-min , Akiyama Yuto , Kakinuma Tomoyuki , Mori Takehiko
Published: October 2013

We have investigated trap density of states (trap DOS) in n-channel organic field-effect transistors based on N,N ’-bis(cyclohexyl)naphthalene diimide (Cy-NDI) and dimethyldicyanoquinonediimine (DMDCNQI). A new method is proposed to extract trap DOS from the Arrhenius plot of the temperature-dependent transconductance. Double exponential trap DOS are observed, in which Cy-NDI has considerable deep states, by contrast, DMDCNQI has substantial tail states. In addition, numerical simulation of the transistor characteristics has been conducted by assuming an exponential trap distribution and the interface approximation. Temperature dependence of transfer characteristics are well reproduced only using several parameters, and the trap DOS obtained from the simulated characteristics are in good agreement with the assumed trap DOS, indicating that our analysis is self-consistent. Although the experimentally obtained Meyer-Neldel temperature is related to the trap distribution width, the simulation satisfies the Meyer-Neldel rule only very phenomenologically. The simulation also reveals that the subthreshold swing is not always a good indicator of the total trap amount, because it also largely depends on the trap distribution width. Finally, band transport is explored from the simulation having a small number of traps. A crossing point of the transfer curves and negative activation energy above a certain gate voltage are observed in the simulated characteristics, where the critical VG above which band transport is realized is determined by the sum of the trapped and free charge states below the conduction band edge.
Does generic entry lower the prices paid for pharmaceuticals in Australia? A comparison before and after the introduction of the mandatory price-reduction policy
Authors: Spinks Jean , Chen Gang , Donovan Lara
Published: October 2013

Objective We investigated the relationship between the number of generic medicines and pharmaceutical prices over time in Australia. Methods A dataset was utilised containing 76 items for 4 years (2003–2007) on the national subsidy scheme – the Pharmaceutical Benefits Scheme (PBS) – for which a generic brand is available. The PBS price was used as the dependent variable, and the number of generics available the key explanatory variable. The ordinary least-squares estimator was adopted for estimation. In the robustness analysis, an instrumental-variables method was used to account for potential endogeneity. Results Results suggested that the effect of increased generic medicine sellers on reducing the prices paid for generics is marginal but statistically significant. Conclusions It is suggested that structural changes to the way generic prices are determined needs to be reconsidered by the Australian government if the policy aim of using increased ‘competition’ to lower prices is to be maximised. What is known about the topic? There is scant empirical evidence that supports the notion that increased generic availability for pharmaceuticals, in heavily price-regulated markets such as Australia, has a significant effect on lowering the prices paid over time. Despite this, Australia has adopted a policy that promotes increased generic ‘competition’ as a means of controlling prices, without establishing if this policy has, or is likely to be, successful in the longer term. What does this paper add? Using longitudinal data from Medicare Australia, this paper quantifies the relationship between the number of branded and generic items of a given drug molecule and formulation, and prices paid over time, controlling for other explanatory variables. What are the implications for practitioners? The results suggest that although increased generic entry may lower prices over time in the Australian context, the price reduction gained is likely to be very small. Therefore, whilst generic entry should be encouraged, it is important not to assume that this price-lowering effect is realised without question and that the magnitude of such an effect is comparable with other price-regulated countries.
Use of introgression lines to determine the ecophysiological basis for changes in water use efficiency and yield in California processing tomatoes
Authors: Barrios-Masias Felipe H. , Chetelat Roger T. , Grulke Nancy E. , Jackson Louise E.
Published: October 2013

Field and greenhouse studies examined the effects of growth habit and chloroplast presence in leaf veins for their role in increasing agronomic water use efficiency and yields of California modern processing tomato (Solanum lycopersicum L.) cultivars. Five introgression lines (ILs), made with Solanum pennellii Cor. in the genetic background of cultivar M82, differ in genes that map to a region on Chromosome 5, including the SP5G gene (determinate vs. semideterminate (Det vs. SemiDet)) and the obv gene (presence (obscure) vs. absence (clear) of leaf vein chloroplasts (Obs vs. Clr)). The five ILs and M82 represented three of the four gene combinations (Det–Clr was unavailable). Det–Obs ILs had less leaf, stem and total aboveground biomass with earlier fruit set and ripening than SemiDet–Clr ILs. By harvest, total fruit biomass was not different among ILs. Photosynthetic rates and stomatal conductance were 4–7% and 13–26% higher, respectively, in Det–Obs ILs than SemiDet–Clr ILs. SemiDet–Obs ILs were intermediate for growth and gas exchange variables. The Det–Obs ILs had lower leaf N concentration and similar chlorophyll content per leaf area (but slightly higher per leaf mass) than SemiDet–Clr ILs. The Obs trait was associated with gains in leaf gas exchange-related traits. This study suggests that a more compact growth habit, less leaf biomass and higher C assimilation capacity per leaf area were relevant traits for the increased yields in cultivars with determinate growth. Developing new introgression libraries would contribute to understanding the multiple trait effects of desirable phenotypes.
The effect of habitat complexity on the contribution of some littoral–benthic Cladocera to the pelagic food web
Authors: Adamczuk Małgorzata
Published: October 2013

Littoral zones of lakes are settled by typical littoral animals, but they are also explored by mobile vertebrate and invertebrate predators. The relative importance of habitat complexity on the availability of littoral–benthic species of Cladocera, including Alonella exigua, A. excisa and A. nana (Chydoridae), to planktonic predators (Leptodora and cyclopoid copepods) was investigated in a series of laboratory experiments and under natural conditions (Lake Piaseczno, eastern Poland). The laboratory experiments showed that invertebrate predators influenced the density of cladocerans, but that predatory success was related to spatial complexity. A treatment imitating a habitat of water milfoil provided the highest survival rate, whereas a treatment imitating a habitat of macroalgae provided the lowest survival rate of the Alonella species, independently of the type of predators. Leptodora showed a higher predation pressure than did the cyclopoid copepods in a treatment imitating a habitat of common reed. In the field research, inverse correlations between the density of Alonella and potential invertebrate predators in distinct habitats were found. The species most strongly preyed on under the experimental conditions showed the highest fecundity, thus suggesting that the predation pressure by planktonic invertebrates influences the demography and life-history trade-offs of juvenile Alonella individuals in the lake. The obtained results extend our knowledge on the type and magnitude of interactions between the littoral–benthic and pelagic food webs.
Seasonal dynamics of Alexandrium tamarense and occurrence of paralytic shellfish poisoning toxins in bivalves in Nanji Islands, East China Sea
Authors: Jiang Tao , Xu Yixiao , Li Yang , Jiang Tianjiu , Wu Feng , Zhang Fan
Published: October 2013

A monitoring program for seasonal dynamics of A. tamarense and paralytic shellfish poisoning toxins (PSTs) in bivalves was carried out from April 2006 to March 2007 in Nanji Islands, East China Sea. Low abundances of A. tamarense (fewer than 4.0 × 102 cells L–1) were first observed on 15 April 2006. During middle May, blooms of A. tamarense were documented, with the mean density of 3.8 × 103 cells L–1 and 0.75 × 103 cells L–1, corresponding to surface and bottom water columns, respectively. Environmental conditions of temperature range 18–20°C and salinity range 29.5–31 coincided with a high abundance of A. tamarense in the region, and the bloom collapse was likely to be a response to P limitation. Toxin concentrations in cultured Patinopecten yessoensis, Mytilus galloprovincialis and wild Mytilus coruscus during A. tamarense blooms ranged from 68.9 to 96.3 μg STXeq per 100 g flesh. Toxin profiles were similar among bivalve shellfish samples, dominated by C1 and C2 in 51.4–64.6 mol% of toxins, with an average of 60.6 mol%, followed by GTX5, GTX1–GTX4, dcGTX2 and dcGTX3. However, from January to March 2007, lower toxin concentrations, 18.9–40.8 μg STXeq per 100 g were found only in the wild Oyster sp., comprising GTX4, GTX5 and GTX1.
New biological data on the rare, threatened shark Carcharhinus leiodon (Carcharhinidae) from the Persian Gulf and Arabian Sea
Authors: Moore Alec B. M. , Almojil Dareen , Harris Mark , Jabado Rima W. , White William T.
Published: October 2013

New biological data relevant to the conservation of the rare and threatened shark Carcharhinus leiodon are presented, based on specimens sampled in fish markets in Kuwait, the UAE and Yemen. The maximum size of this species is extended to 1648 mm total length (TL); females are mature by at least 1312 mm TL and demonstrate placental viviparity with litters of 4–6 embryos. In the north-western Persian Gulf there is evidence that parturition occurs in spring when embryos are ~350–515 mm TL, with at least some neonate individuals probably remaining in the area through the summer. Further records of C. leiodon from the western Arabian Sea indicate that adults are present in this region throughout the year. Landings of C. leiodon apparently caught in the eastern Persian Gulf may extend the highly fragmented known distribution of this species. Contrary to an earlier study, the first detailed examination of dissected adult C. leiodon jaws revealed that fine serrations are present on upper teeth, and characters are provided to separate the dentition and jaws of C. leiodon from congeners. The stomach of an adult C. leiodon contained bentho-demersal fish, and an individual with fin abnormalities is noted.
Comparative effectiveness and acceptability of home-based and clinic-based sampling methods for sexually transmissible infections screening in females aged 14–50 years: a systematic review and meta-analysis
Authors: Odesanmi Tolulope Y. , Wasti Sharada P. , Odesanmi Omolola S. , Adegbola Omololu , Oguntuase Olubukola O. , Mahmood Sajid
Published: October 2013

Background Home-based sampling is a strategy to enhance uptake of sexually transmissible infection (STI) screening. This review aimed to compare the screening uptake levels of home-based self-sampling and clinic-based specimen collection for STIs (chlamydia (Chlamydia trachomatis), gonorrhoea (Neisseria gonorrhoeae) and trichomoniasis) in females aged 14–50 years. Acceptability and effect on specimen quality were determined. Methods: Sixteen electronic databases were searched from inception to September 2012. Randomised controlled trials (RCTs) comparing the uptake levels of home-based self-sampling and clinic-based sampling for chlamydia, gonorrhoea and trichomoniasis in females aged 14–50 years were eligible for inclusion. The risk of bias in the trials was assessed. Risk ratios (RRs) for dichotomous outcomes were meta-analysed. Results: Of 3065 papers, six studies with seven RCTs contributed to the final review. Compared with clinic-based methods, home-based screening increased uptake significantly (P = 0.001–0.05) in five trials and was substantiated in a meta-analysis (RR: 1.55; 95% confidence interval: 1.30–1.85; P = 0.00001) of two trials. In three trials, a significant preference for home-based testing (P = 0.001–0.05) was expressed. No significant difference was observed in specimen quality. Sampling was rated as easy by a significantly higher number of women (P = 0.01) in the clinic group in one trial. Conclusions: The review provides evidence that home-based testing results in greater uptake of STI screening in females (14–50 years) than clinic-based testing without compromising quality in the developed world. Home collection strategies should be added to clinic-based screening programs to enhance uptake.
Microsatellite analysis of genetic variability in Waler horses from Australia
Authors: Khanshour Anas M. , Juras Rytis , Cothran E. Gus
Published: October 2013

The Waler horse breed is an integral part of Australian history. The purposes of this study were to analyse the genetic variability in Waler horses from Australia and to investigate genetic relationships with other horse breeds. We examined the genetic diversity of 70 Waler horses sampled from seven breeding stations in Australia. Also we analysed the relationships of these horses with 11 other horse breeds. Analysis of the genetic structure was carried out using 15 microsatellite loci, genetic distances, AMOVA, factorial correspondence analysis and a Bayesian method. We found that the genetic diversity in the Waler was greater than the domestic horse mean and exceeded that of all endangered horse breeds. Our findings also revealed moderate population subdivision rather than inbreeding. All genetic similarity measures indicated that the Thoroughbred might be a key ancestor to the Waler. This study indicates that there is no immediate concern for loss of variation in Waler horses. Also, there clearly has been a strong input from the Thoroughbred into the Waler horse breed. However, the genetic evidence suggests that this input was not just direct but also came through other types of horses with a Thoroughbred cross background.
Impaired apoptosis, extended duration of immune responses, and a lupus-like autoimmune disease in IEX-1-transgenic mice
Authors: Zhang Y. , Schlossman S. F. , Edwards R. A. , Ou Ching-Nan , Gu J. , Wu Mei X.
Published: October 2013

Susceptibility of activated T cells to apoptosis must be tightly regulated to ensure sufficient T cell progeny for an effective response, while allowing a rapid depletion of them at the end of the immune response. We show here that a previously isolated, NF-κB/rel target gene IEX-1 (Immediate Early response gene X-1) is highly expressed in T cells at early stages of activation, but declines with a prolonged period of activation time, coincident with an increased susceptibility of T cells to apoptosis during the late phases of an immune response. Transgenic expression of IEX-1 specifically in lymphocytes impaired apoptosis in activated T cells, extended a duration of an effector-phase of a specific immune response, and increased the accumulation of effector/memory-like T cells and the susceptibility to a lupus-like autoimmune disease. Our study demonstrated an antiapoptotic effect of IEX-1 on T cell apoptosis triggered by ligation of Fas and T cell receptor (TCR)/CD3 complex. The ability of extending life expectancy of T effectors, in line with a decrease in its expression following prolonged T cell activation, suggests a key role for IEX-1 in regulating T cell homeostasis during immune responses.
Tensin1 and a previously undocumented family member, tensin2, positively regulate cell migration
Authors: Chen Huaiyang , Duncan Ian C. , Bozorgchami Hormozd , Lo Su Hao
Published: October 2013

Tensin is a focal adhesion molecule that binds to actin filaments and participates in signaling pathways. In this study, we have characterized a previously undocumented tensin family member, tensin2/KIAA 1075. Human tensin2 cDNA encodes a 1,285-aa sequence that shares extensive homology with tensin1 at its amino- and carboxyl-terminal ends, which include the actin-binding domain, the Src homology 2 (SH2) domain, and the phosphotyrosine binding (PTB) domain. Analysis of the genomic structures of tensin1 and tensin2 further confirmed that they represent a single gene family. Examination of tensin2 mRNA distribution revealed that heart, kidney, skeletal muscle, and liver were tissues of high expression. The endogenous and recombinant tensin2 were expressed as a 170-kDa protein in NIH 3T3 cells. The subcellular localization of tensin2 was determined by transfection of green fluorescence protein (GFP)–tensin2 fusion construct. The results indicated that tensin2 is also localized to focal adhesions. Finally, functional analysis of tensin genes has demonstrated that expression of tensin genes is able to promote cell migration on fibronectin, indicating that the tensin family plays a role in regulating cell motility.
Effect of the human cytomegalovirus IE86 protein on expression of E2F-responsive genes: A DNA microarray analysis
Authors: Song Yoon-Jae , Stinski Mark F.
Published: October 2013

We have previously reported that the immediate early (IE)-86 protein of human cytomegalovirus (HCMV) pushes the cell cycle toward S phase but inhibits cell division [Murphy, E. A., Streblow, D. N., Nelson, J. A. & Stinski, M. F. (2000)
J. Virol.
74, 7108–7118]. We determined the cellular genes activated by the IE86 protein in permissive human fibroblast cells. A 4-fold or greater increase in the steady-state RNA from many cellular genes that regulate the cell cycle, the enzymes for DNA precursor synthesis, and the initiation of cellular DNA replication was detected by high-density DNA microarray analysis. Northern blot analysis confirmed the DNA microarray data. The viral IE86 protein induced a significant increase in the cellular steady-state RNA level from the B-myb, cyclin E, cdk-2, E2F-1, ribonucleotide reductase 1, ribonucleotide reductase 2, thymidylate synthetase, MCM3, and MCM7 genes, but actin RNA was not affected. Cellular genes regulated by the E2F transcription factors were strongly activated by the IE86 protein. In most cases, the cellular genes induced by the IE86 protein were also induced by HCMV infection. This study demonstrates the global array of cellular genes activated by the IE86 protein that pushes progression of the cell cycle from G
0
/G
1
toward the G
1
/S transition point.
Human Elongator facilitates RNA polymerase II transcription through chromatin
Authors: Kim Jae-Hyun , Lane William S. , Reinberg Danny
Published: October 2013

A human Elongator complex was purified from HeLa cells and found to be composed of three polypeptides. Human Elongator contains histone acetyltransferase activity with specificity to histone H3 and, to a much lesser extent, to histone H4. Although many reports have suggested a role for the yeast Elongator in transcription elongation through chromatin templates, no direct evidence supporting this function exists. In the present study, we demonstrate that the human Elongator facilitates transcription by RNA polymerase II in a chromatin- and acetyl-CoA-dependent manner. The complex was found to directly interact with RNA polymerase II but failed to interact with other factors that facilitated RNA polymerase II to traverse through nucleosomes. From our results, we postulate that different mechanisms operate to ensure efficient transcription by RNA polymerase II on chromatin templates.
Ischemic preconditioning acts upstream of GluR2 down-regulation to afford neuroprotection in the hippocampal CA1
Authors: Tanaka Hidenobu , Calderone Agata , Jover Teresa , Grooms Sonja Y. , Yokota Hidenori , Zukin R. Suzanne , Bennett Michael V. L.
Published: October 2013

Animals subjected to sublethal transient global ischemia (ischemic preconditioning) exhibit neuroprotection against subsequent global ischemia-induced neuronal death in the hippocampal CA1 (ischemic tolerance). The molecular mechanisms underlying ischemic tolerance are unclear. Here we report that ischemic preconditioning induced a small, transient down-regulation of GluR2 mRNA expression and greatly attenuated subsequent ischemia-induced GluR2 mRNA and protein down-regulation and neuronal death. Ischemic preconditioning and GluR2 antisense knockdown acted synergistically to increase cell death. Sublethal antisense knockdown did not protect against subsequent ischemic insults or antisense knockdown. These findings indicate that ischemic preconditioning acts at step(s) upstream from suppression of GluR2 gene expression to afford neuroprotection and implicate transcriptional regulation of GluR2 expression in the adaptive mechanisms associated with ischemic tolerance.
The transmission of nuclear pore complexes to daughter cells requires a cytoplasmic pool of Nsp1
Authors: Colombi Paolo , Webster Brant M. , Fröhlich Florian , Lusk C. Patrick
Published: October 2013

Nuclear pore complexes (NPCs) are essential protein assemblies that span the nuclear envelope and establish nuclear–cytoplasmic compartmentalization. We have investigated mechanisms that control NPC number in mother and daughter cells during the asymmetric division of budding yeast. By simultaneously tracking existing NPCs and newly synthesized NPC protomers (nups) through anaphase, we uncovered a pool of the central channel nup Nsp1 that is actively targeted to the bud in association with endoplasmic reticulum. Bud targeting required an intact actin cytoskeleton and the class V myosin, Myo2. Selective inhibition of cytoplasmic Nsp1 or inactivation of Myo2 reduced the inheritance of NPCs in daughter cells, leading to a daughter-specific loss of viability. Our data are consistent with a model in which Nsp1 releases a barrier that otherwise prevents NPC passage through the bud neck. It further supports the finding that NPC inheritance, not de novo NPC assembly, is primarily responsible for controlling NPC number in daughter cells.
Ensuring that yeast cells get their inheritance
Authors: Leslie Mitch
Published: October 2013

A nucleoporin allows nuclear pore complexes access to daughter cell during mitosis.