bluuebunny/crossref_metadata_2025 huggingface dataset:
The stellar metallicity distribution in intermediate-latitude fields
Authors: Peng Xiyan , Du Cuihua , Wu Zhenyu
Published: July 2013

Based on BATC and SDSS photometric data, we adopt the spectral energy distribution (SED) fitting method to evaluate stellar metallicities in the Galaxy. We find that the mean metallicity shifts from metal-rich to metal-poor with the increase of distance from the Galactic Centre.
Gas, dust and star formation in nearby galaxies as seen with the JCMT
Authors: Sánchez-Gallego José Ramón , Knapen Johan H.
Published: July 2013

We presented results using the Nearby Galaxies Legacy Survey (NGLS), which is being carried out with the James Clerk Maxwell Telescope (JCMT) on Mauna Kea in Hawai'i. We have obtained CO J=3−2 data for 155 nearby galaxies to trace the dense molecular gas in which stars are believed to be born. The sample of this survey covers a wide morphological range and has been selected to include galaxies that have been thoroughly studied in the literature, and for which abundant observational data are available. In parallel, we have observed the same sample of galaxies using the Hα spectral line, which traces massive star formation.
Plasma diagnostics of emission-line galaxies in SDSS
Authors: Zhang Zhitai , Liang Yanchun , Hammer François
Published: July 2013

We analyse a sample of 15,019 narrow emission-line galaxies, i.e. Seyferts, LINERs, composites and star-forming galaxies, from SDSS DR7 to study the differences between the different emission-line classes. We report two clear sequences of electron temperature (Te) and density (ne): Te-LINER ≳ Te-composite > Te-Seyfert > Te-star-forming and ne-Seyfert ≳ ne-LINER > ne-composite > ne-star-forming. General transitions of ne and Te from central regions to disks are quantitatively confirmed.
Assembly Histories and Observational Properties of Simulated Early-type Galaxies
Authors: Johansson Peter H.
Published: July 2013

We demonstrate that massive simulated galaxies assemble in two phases, with the initial growth dominated by compact in situ star formation, whereas the late growth is dominated by accretion of old stars formed in subunits outside the main galaxy. We also show that 1) gravitational feedback strongly suppresses late star formation in massive galaxies contributing to the observed galaxy colour bimodality that 2) the observed galaxy downsizing can be explained naturally in the two-phased model and finally that 3) the details of the assembly histories of massive galaxies are directly connected to their observed kinematic properties.
Probing the mass assembly of massive nearby galaxies with deep imaging
Authors: Duc P.–A. , Cuillandre J.-C. , Alatalo K. , Blitz L. , Bois M. , Bournaud F. , Bureau M. , Cappellari M. , Côté P. , Davies R. L. , Davis T. A. , de Zeeuw P. T. , Emsellem E. , Ferrarese L. , Ferriere E. , Gwyn S. , Khochfar S. , Krajnovic D. , Kuntschner H. , Lablanche P.-Y. , McDermid R. M. , Michel-Dansac L. , Morganti R. , Naab T. , Oosterloo T. , Sarzi M. , Scott N. , Serra P. , Weijmans A. , Young L. M.
Published: July 2013

According to a popular scenario supported by numerical models, the mass assembly and growth of massive galaxies, in particular the Early-Type Galaxies (ETGs), is, below a redshift of 1, mainly due to the accretion of multiple gas–poor satellites. In order to get observational evidence of the role played by minor dry mergers, we are obtaining extremely deep optical images of a complete volume limited sample of nearby ETGs. These observations, done with the CFHT as part of the ATLAS3D, NGVS and MATLAS projects, reach a stunning 28.5 – 29 mag.arcsec−2 surface brightness limit in the g' band. They allow us to detect the relics of past collisions such as faint stellar tidal tails as well as the very extended stellar halos which keep the memory of the last episodes of galactic accretion. Images and preliminary results from this on-going survey are presented, in particular a possible correlation between the fine structure index (which parametrizes the amount of tidal perturbation) of the ETGs, their stellar mass, effective radius and gas content.
Adenosine A2A Receptor Contributes to Ischemic Brain Damage in Newborn Piglet
Authors: Yang Zeng-Jin , Wang Bing , Kwansa Herman , Heitmiller Kerry D , Hong Gina , Carter Erin L , Jamrogowicz Jessica L , Larson Abby C , Martin Lee J , Koehler Raymond C
Published: July 2013

Pharmacologic inactivation or genetic deletion of adenosine A2A receptors protects ischemic neurons in adult animals, but studies in neonatal hypoxia-ischemia (H-I) are inconclusive. The present study in neonatal piglets examined the hypothesis that A2A receptor signaling after reoxygenation from global H-I contributes to injury in highly vulnerable striatal neurons where A2A receptors are enriched. A2A receptor immunoreactivity was detected in striatopallidal neurons. In nonischemic piglets, direct infusion of the selective A2A receptor agonist CGS 21680 through microdialysis probes into putamen increased phosphorylation of N-methyl-D-aspartic acid (NMDA) receptor NR1 subunit and Na+, K+-ATPase selectively at protein kinase A (PKA)-sensitive sites. In ischemic piglets, posttreatment with SCH 58261, a selective A2A receptor antagonist, improved early neurologic recovery and preferentially protected striatopallidal neurons. SCH 58261 selectively inhibited the ischemia-induced phosphorylation of NR1, Na+, K+-ATPase, and cAMP-regulated phosphoprotein 32 KDa (DARPP32) at PKA-sensitive sites at 3 hours of recovery and improved Na+, K+-ATPase activity. SCH 58261 also suppressed ischemia-induced protein nitration and oxidation. Thus, A2A receptor activation during reoxygenation contributes to the loss of a subpopulation of neonatal putamen neurons after H-I. Its toxic signaling may be related to DARPP32-dependent phosphorylation of PKA-sensitive sites on NR1 and Na+, K+-ATPase, thereby augmenting excitotoxicity-induced oxidative stress after reoxygenation.
Disk Degeneration and Low Back Pain: Are They Fat-Related Conditions?
Authors: Samartzis Dino , Karppinen Jaro , Cheung Jason Pui Yin , Lotz Jeffrey
Published: July 2013

Low back pain (LBP) is the world's most debilitating condition. Disk degeneration has been regarded as a strong determinant associated with LBP. Overweight and obesity are public health concerns that affect every population worldwide and whose prevalence continues to rise. Studies have indicated strong associations between overweight/obesity and disk degeneration as well as with LBP. This broad narrative review article addresses the various mechanisms that may be involved leading to disk degeneration and/or LBP in the setting of overweight/obesity. In particular, our goal is to raise awareness of the role of fat cells and their involvement via altered metabolism or the release of adipokines as well as other pathways that may lead to the development of disk degeneration and LBP. Understanding the role of fat in this process may aid in the development of novel biological therapies and technologies to halt the progression or regenerate the disk. Moreover, with genetic advancements and the appreciation of genetic epidemiology, a more personalized approach to spine care may have to consider the role of fat in any preventative, therapeutic, and/or prognosis modalities toward the disk and LBP.
A pulsed-power generator merging inductive voltage and current adders and its switch trigger application example
Authors: Li Lee , Yafeng Ge , Heqin Zhong , Bin Yu , Longjun Xie
Published: July 2013

A pulsed-power generator using inductive adder technology is proposed for the case of a discharge gap. The merit of this generator is to merge the pulsed-voltage and pulsed-current adders via the dual secondary windings with special circuit. For the nonlinear impedance in any discharge gap, the standalone voltage-pulse and current-pulse can be outputted successively by this generator. The proposed generator is especially useful for the common resolution of implementing pulse discharge at less cost. As an application example, a compact trigger prototype was developed to compatibly use in the gas-insulated and vacuum switches. Experiments achieved good results that the triggered switches showed stable performance and long life. If the basic circuit of this proposed generator is regarded as a pulsed-generating unit, a certain number of such units connected in parallel can be expected to form a general device with generating greater breakdown-voltage and sustained-current pulses for discharge gaps.
Selective bond breaking mediated by state specific vibrational excitation in model HOD molecule through optimized femtosecond IR pulse: A simulated annealing based approach
Authors: Shandilya Bhavesh K. , Sen Shrabani , Sahoo Tapas , Talukder Srijeeta , Chaudhury Pinaki , Adhikari Satrajit
Published: July 2013

The selective control of O–H/O–D bond dissociation in reduced dimensionality model of HOD molecule has been explored through IR+UV femtosecond pulses. The IR pulse has been optimized using simulated annealing stochastic approach to maximize population of a desired low quanta vibrational state. Since those vibrational wavefunctions of the ground electronic states are preferentially localized either along the O–H or O–D mode, the femtosecond UV pulse is used only to transfer vibrationally excited molecule to the repulsive upper surface to cleave specific bond, O–H or O–D. While transferring from the ground electronic state to the repulsive one, the optimization of the UV pulse is not necessarily required except specific case. The results so obtained are analyzed with respect to time integrated flux along with contours of time evolution of probability density on excited potential energy surface. After preferential excitation from |0, 0⟩ (|m, n⟩ stands for the state having m and n quanta of excitations in O–H and O–D mode, respectively) vibrational level of the ground electronic state to its specific low quanta vibrational state (|1, 0⟩ or |0, 1⟩ or |2, 0⟩ or |0, 2⟩) by using optimized IR pulse, the dissociation of O–D or O–H bond through the excited potential energy surface by UV laser pulse appears quite high namely, 88% (O–H ; |1, 0⟩) or 58% (O–D ; |0, 1⟩) or 85% (O–H ; |2, 0⟩) or 59% (O–D ; |0, 2⟩). Such selectivity of the bond breaking by UV pulse (if required, optimized) together with optimized IR one is encouraging compared to the normal pulses.
Refinement of the Robert-Bonamy formalism: Considering effects from the line coupling
Authors: Ma Q. , Boulet C. , Tipping R. H.
Published: July 2013

Since it was developed in 1979, the Robert-Bonamy (RB) formalism has been widely used in calculating pressure broadened half-widths and induced shifts for many molecular systems. However, this formalism contains several approximations whose applicability has not been thoroughly justified. One of them is that lines of interest are well isolated. When these authors developed the formalism, they have relied on this assumption twice. First, in calculating the spectral density F(ω), they have only considered the diagonal matrix elements of the relaxation operator. Due to this simplification, effects from the line mixing are ignored. Second, when they applied the linked cluster theorem to remove the cutoff, they have assumed the matrix elements of the operator exp(–iS1 – S2) can be replaced by the exponential of the matrix elements of –iS1 – S2. With this replacement, effects from the line coupling are also ignored. Although both these two simplifications relied on the same approximation, their validity criteria are completely different and the latter is more stringent than the former. As a result, in many cases where the line mixing becomes negligible, significant effects from the line coupling have been completely missed. In the present study, we have developed a new method to evaluate the matrix elements of exp(–iS1 – S2) and have refined the RB formalism such that line coupling can be taken into account. Our numerical calculations of the half-widths for Raman Q lines of the N2–N2 pair have demonstrated that effects from the line coupling are important. In comparison with values derived from the RB formalism, new calculated values for these lines are significantly reduced. A recent study has shown that in comparison with the measurements and the most accurate close coupling calculations, the RB formalism overestimates the half-widths by a large amount. As a result, the refinement of the RB formalism goes in the right direction and these new calculated half-widths become closer to the “true” values.
Relativistic density functional theory modeling of plutonium and americium higher oxide molecules
Authors: Zaitsevskii Andréi , Mosyagin Nikolai S. , Titov Anatoly V. , Kiselev Yuri M.
Published: July 2013

The results of electronic structure modeling of plutonium and americium higher oxide molecules (actinide oxidation states VI through VIII) by two-component relativistic density functional theory are presented. Ground-state equilibrium molecular structures, main features of charge distributions, and energetics of AnO3, AnO4, An2On (An=Pu, Am), and PuAmOn, n = 6–8, are determined. In all cases, molecular geometries of americium and mixed plutonium–americium oxides are similar to those of the corresponding plutonium compounds, though chemical bonding in americium oxides is markedly weaker. Relatively high stability of the mixed heptoxide PuAmO7 is noticed; the Pu(VIII) and especially Am(VIII) oxides are expected to be unstable.
Collineations of a symmetric 2-covariant tensor: Ricci collineations
Authors: Llosa Josep
Published: July 2013

The infinitesimal transformations that leave invariant a two-covariant symmetric tensor are studied. The interest of these symmetry transformations lays in the fact that this class of tensors includes the energy-momentum and Ricci tensors. We find that in most cases the class of infinitesimal generators of these transformations is a finite dimensional Lie algebra, but in some cases exhibiting a higher degree of degeneracy, this class is infinite dimensional and may fail to be a Lie algebra. As an application, we study the Ricci collineations of a type B warped spacetime.
Diode assisted giant positive magnetoresistance in n-type GaAs at room temperature
Authors: Wang Jimin , Zhang Xiaozhong , Wan Caihua , Piao Hong-Guang , Luo Zhaochu , Xu Sheng-Yong
Published: July 2013

We have investigated a diode-assisted GaAs based magnetoresistance (MR) effect at room temperature. It is found that the introduction of diode effectively enhanced the MR effect of the GaAs device, and the MR increases with increasing the length/width ratio of the device. The MR can be achieved to about 2600% at 1.2 T with a high MR sense ability of about 44% at 0.06 T and an extremely low energy consumption of sub-micro Watt. This work may open a new way for the practical application of the semiconductor based magnetic sensing industry.
Magnetotransport properties of high equivalent Al composition AlGaN/GaN heterostructures using AlN/GaN superlattice as a barrier
Authors: Liu S. D. , Tang N. , Shen X. Q. , Duan J. X. , Lu F. C. , Yang X. L. , Xu F. J. , Wang X. Q. , Ide T. , Shimizu M. , Ge W. K. , Shen B.
Published: July 2013

Magnetotransport properties of the two-dimensional electron gas (2DEG) in high equivalent Al composition AlGaN/GaN heterostructures using AlN/GaN superlattice as a barrier have been studied at low temperatures and high magnetic fields. Well resolved Shubnikov-de Haas oscillations were observed, indicating excellent quality of the quasi-AlGaN/GaN heterostructures. It is measured that the energy separation between the two subbands in the GaN triangular quantum well can be as large as 180.5 meV, depicting strong quantum confinement at the heterointerface. The strong quantum confinement results in a high 2DEG density of 2 × 1013 cm−2. The persistent photoconductivity investigation also indicates that the superlattice barrier layer has a low density of impurities/defects. It is believed that the AlN/GaN superlattice, instead of high Al composition alloy AlGaN layer, could greatly improve the device performance.
Resonant microwave pulse compressor operating in two frequencies
Authors: Beilin L. , Shlapakovski A. , Krasik Ya. E.
Published: July 2013

A resonant microwave pulse compressor with a hybrid (Magic) waveguide tee as an interference switch was studied in numerical simulations and experimentally. In this compressor, the necessary condition for energy storage in the compressor cavity is frequency-independent, so that its operation in different cavity eigenmodes without mechanical tuning is possible. An S-band compressor operating in two different frequencies (neighboring modes) was investigated. Two characteristic geometries corresponding to different regimes of the microwave energy accumulation and release were tested using input pulses of 200–400 kW power, 2.4 μs duration, and variable frequency, 2.8 to 2.9 GHz. The geometries are characterized by an RF electric field in the interference switch that is higher or lower than the field in the cavity. The plasma discharge that switches the phases of compressor operation from energy storage to release was initiated by small metallic cones placed in the appropriate location. For both geometries, the nanosecond output pulses in two resonant frequencies were obtained; the maximal peak output power measured was ∼1.8 MW. The efficiency of the microwave extraction was limited by either an insufficient coupling to the tee output arm (in the case of a high field in the tee) or non-uniformity of the plasma discharge (in the case of low field in the tee).
Fabrication and characterization of a large-area metal nano-grid wave plate
Authors: Kravchenko A. , Shevchenko A. , Ovchinnikov V. , Grahn P. , Kaivola M.
Published: July 2013

We introduce a fast and cost-effective technique to fabricate large-area periodically nanopatterned metal samples and apply this technique to create reflective nano-grid wave plates for optical wavelengths. The technique makes use of azo-polymer-based interference lithography and a special imprint method that enables creating large-area metal nanopatterns with high vertical walls. We fabricate and experimentally test a gold nano-grid wave plate that operates as reflective λ/4-plate for λ = 604 nm and λ/2-plate for λ = 997 nm.
A resonant method for determining the residual stress and elastic modulus of a thin film
Authors: Ma Shujun , Wang Shiliang , Iacopi Francesca , Huang Han
Published: July 2013

By measuring the resonant frequencies of the first two symmetric vibration modes of a circular thin-film diaphragm and solving the Rayleigh-Ritz equation analytically, the residual stress and elastic modulus of the film were determined simultaneously. The results obtained employing this method are in excellent agreement with those obtained numerically in finite element modelling when tested using freestanding circular SiC diaphragms with residual tensile stress. The stress and modulus values are also in reasonably good agreement with those obtained from nanoindentation and wafer curvature measurements, respectively.
Direct comparison of traps in InAlN/GaN and AlGaN/GaN high electron mobility transistors using constant drain current deep level transient spectroscopy
Authors: Sasikumar A. , Arehart A. R. , Martin-Horcajo S. , Romero M. F. , Pei Y. , Brown D. , Recht F. , di Forte-Poisson M. A. , Calle F. , Tadjer M. J. , Keller S. , DenBaars S. P. , Mishra U. K. , Ringel S. A.
Published: July 2013

Traps in InAlN/GaN and AlGaN/GaN high electron mobility transistors (HEMTs) are identified and compared using constant drain-current deep level transient spectroscopy (CID-DLTS). For both structures with different barrier materials, the same drain-access electron trap at EC−0.57 eV dominates the drain-controlled CID-DLTS trap spectrum. This suggests that the physical source of this trap, previously associated with drain-lag, is not present in the barrier but instead is likely to reside in the GaN-buffer. Gate-controlled CID-DLS measurements, which are preferentially sensitive to the barrier under the gate, reveal different trap spectra for the two HEMTs, showing that choice of barrier materials can influence under-gate trap signatures.
Influence of the Purcell effect on the purity of bright single photon sources
Authors: Giesz V. , Gazzano O. , Nowak A. K. , Portalupi S. L. , Lemaître A. , Sagnes I. , Lanco L. , Senellart P.
Published: July 2013

Purcell effect is a powerful tool to efficiently collect single photons emitted by semiconductor quantum dots. However, it is common to observe a degraded single photon purity when a quantum dot is inserted in an optical microcavity. Here, we investigate the role of the cavity coupling on the single photon purity for a quantum dot deterministically coupled to a pillar cavity mode. We show that the degradation of the purity cannot be attributed to cavity feeding effects but is fully explained by recapture processes. A good single photon purity is therefore easily restored using an intra-dot excitation scheme.
High-quality Bi2Te3 thin films grown on mica substrates for potential optoelectronic applications
Authors: Wang K. , Liu Yanwen , Wang Weiyi , Meyer N. , Bao L. H. , He L. , Lang M. R. , Chen Z. G. , Che X. Y. , Post K. , Zou J. , Basov D. N. , Wang K. L. , Xiu Faxian
Published: July 2013

We report high-quality topological insulator Bi2Te3 thin films grown on muscovite mica substrates by molecular beam epitaxy. The topographic and structural analysis revealed that the Bi2Te3 thin films exhibited atomically smooth terraces over a large area and a high crystalline quality. Both weak antilocalization effect and quantum oscillations were observed in the magnetotransport of the relatively thin samples. A phase coherence length of 277 nm for a 6 nm thin film and a high surface mobility of 0.58 m2 V−1 s−1 for a 4 nm thin film were achieved. These results confirm that the thin films grown on mica are of high quality.
Quantitative characterization of interface traps in Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors by dynamic capacitance dispersion technique
Authors: Ma Xiao-Hua , Zhu Jie-Jie , Liao Xue-Yang , Yue Tong , Chen Wei-Wei , Hao Yue
Published: July 2013

In this letter, the interface traps of Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) were characterized quantitatively by dynamic capacitance dispersion technique. An analysis of Al2O3/AlGaN interface states demonstrated deep traps in the range of 0.53 eV-1.16 eV below the conduction band, with trap density nearly constant and two orders of magnitude smaller than that at AlGaN surface due to the use of atomic layer deposition-grown Al2O3 insulator. As much as 2.23 × 1013 eV−1 cm−2 fast traps with time constant smaller than 0.3 μs were observed at AlGaN/GaN interface of MOS-HEMTs, which was consistent with the qualitative prediction from pulsed I-V test.
Electrical transport in carbon black-epoxy resin composites at different temperatures
Authors: Macutkevic J. , Kuzhir P. , Paddubskaya A. , Maksimenko S. , Banys J. , Celzard A. , Fierro V. , Bistarelli S. , Cataldo A. , Micciulla F. , Bellucci S.
Published: July 2013

Results of broadband electric/dielectric properties of different surface area—carbon black/epoxy resin composites above the percolation threshold are reported in a wide temperature range (25–500 K). At higher temperatures (above 400 K), the electrical conductivity of composites is governed by electrical transport in polymer matrix and current carriers tunneling from carbon black clusters to polymer matrix. The activation energy of such processes decreases when the carrier concentration increases, i.e., with the increase of carbon black concentration. At lower temperatures, the electrical conductivity is governed by electron tunneling and hopping. The electrical conductivity and dielectric permittivity of composites strongly decrease after annealing composites at high temperatures (500 K); at the same time potential barrier for carriers tunneling strongly increases. All the observed peculiarities can be used for producing effective low-cost materials on the basis of epoxy resin working at different temperatures for electrical applications.
Interplay of different photoluminescence degradation mechanisms in InGaAlP light emitting diode structures investigated by intense laser excitation
Authors: Karl C. , Ebbecke J. , Lutz T. , Kauss C. , Zeisel R.
Published: July 2013

The interplay of different photoluminescence degradation mechanisms in InGaAlP light emitting diode structures is studied. We investigate the dependence of the photoluminescence degradation behavior on different stress and detection laser power densities. The aging experiments are carried out in an optical overstress setup via high power laser excitation. The experimental data are analyzed by a multicomponent defect evolution approach. Simultaneous growth and annealing of different kinds of defects during the photoluminescence degradation of the device are described by individual characteristic time constants for each of the defect evolution processes. This defect evolution approach is combined with a rate equation model covering radiative and non-radiative processes in the active layer as well as leakage effects into the confining layers.
Photoluminescence from single nitrogen isoelectronic centers in gallium phosphide produced by ion implantation
Authors: Éthier-Majcher G. , St-Jean P. , Bergeron A. , Phaneuf-L'Heureux A.-L. , Roorda S. , Francoeur S.
Published: July 2013

Single emitters formed from two nitrogen isoelectronic traps in GaP are created by low energy implantation. Several dyad configurations are individually resolved, establishing that ion implantation can produce multi-impurity single emitters with high luminescence yield. Measured dyad concentrations significantly exceed those predicted from simulations, suggesting that their formation is strongly enhanced by implantation defects. Annealing at 600 °C optimizes the luminescence yield and higher temperatures lead to the physical dissociation of dyads. The dissociation activation energy increases with interatomic separation, indicating that nearest neighbor dyads are energetically unfavorable and that their concentration can be adjusted with a simple temperature treatment.
Local electron field emission study of two-dimensional carbon
Authors: Wang Ying , Yang Yumeng , Zhao Zizheng , Zhang Chi , Wu Yihong
Published: July 2013

A systematic field-emission study has been carried out on different types of two-dimensional carbons in ultrahigh vacuum with the cathode-anode distance ranging from near-contact to about 124 nm. An analytical model has been developed to explain the increase of field enhancement factor with the cathode-anode distance. Good agreement has been achieved between the calculation results and experimental data, including those reported in literature. The work provides useful insights into the characteristics of field emission from two-dimensional carbon.
Atomic structure of (110) anti-phase boundaries in GaP on Si(001)
Authors: Beyer A. , Haas B. , Gries K. I. , Werner K. , Luysberg M. , Stolz W. , Volz K.
Published: July 2013

High quality III/V-layers grown on Si enable a variety of optoelectronic devices. The performance of such devices is limited by anti-phase domains forming at monoatomic steps on the Si-surface. To date the atomic structure of anti-phase boundaries, which affects the charge distribution at polar interfaces, is unknown. Here, we use CS-corrected scanning transmission electron microscopy to reveal the atomic structure of the anti-phase boundaries in III/V-semiconductors, choosing GaP as a model system. We observe boundaries on (110) lattice planes which are atomically abrupt and also facetted ones, which introduces locally charged regions influencing device performance.
Intrinsic optical gain in thin films of a conjugated polymer under picosecond excitation
Authors: Lampert Zach E. , Lappi Simon E. , Papanikolas John M. , Lewis Reynolds C.
Published: July 2013

A strong excitation pulse width dependence on optical gain is reported in thin films of the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV), which suggests that previously reported gain measurements have occurred in an excitation regime that cause damage to the polymer. Symmetric waveguides Si(100)/SiO2/MEH-PPV/poly(methyl methacrylate) are fabricated and optically pumped using laser pulses having temporal widths shorter and longer than the PL decay time, resulting in transient and quasi-steady-state excitation conditions, respectively. Under quasi-steady-state conditions (8 ns pulses), a maximum gain coefficient of ∼135 cm−1 is achieved at a fluence of 2250 μJ/cm2. However, extremely large optical gain is observed under transient pumping (25 ps), reaching 700 cm−1 at a fluence of only 85 μJ/cm2; this 5× improvement in optical gain performance is achieved at the same excitation density as that for ns pulses. It is clear that our ps gain measurements more accurately represent the intrinsic net gain of MEH-PPV than prior measurements in the quasi-steady-state regime.
Deterministic generation of single photons via multiplexing repetitive parametric downconversions
Authors: Glebov Boris L. , Fan J. , Migdall A.
Published: July 2013

We show through Monte Carlo simulation, under realistic experimental conditions, that a system composed of just a few repetitive spontaneous parametric downconversion processes can approximate an on-demand single-photon source with nearly deterministic single-photon emission.
Improved phase-change characteristics of Zn-doped amorphous Sb7Te3 films for high-speed and low-power phase change memory
Authors: Wang Guoxiang , Shen Xiang , Nie Qiuhua , Wang R. P. , Wu Liangcai , Lu Yegang , Dai Shixun , Xu Tiefeng , Chen Yimin
Published: July 2013

The superior performance of Zn-doped Sb7Te3 films might be favorable for the application in phase change memory. It was found that Zn dopants were able to suppress phase separation and form single stable Sb2Te crystal grain, diminish the grain size, and enhance the amorphous thermal stability of Sb7Te3 film. Especially, Zn30.19(Sb7Te3)69.81 film has higher crystallization temperature (∼258 °C), larger crystallization activation energy (∼4.15 eV), better data retention (∼170.6 °C for 10 yr), wider band gap (∼0.73 eV), and higher crystalline resistance. The minimum times for crystallization of Zn30.19(Sb7Te3)69.81 were revealed to be as short as ∼10 ns at a given proper laser power of 70 mW.
Optical and magnetic properties of PAA@Fe nanocomposite films
Authors: Zhang Jing-jing , Hou Xue , Liu Li-hu , Sun Hui-yuan
Published: July 2013

A simple method to fabricate porous anodic alumina films embedded with Fe is reported. The films exhibit vivid structural colors and magnetic properties after being synthesized by an ac electrodeposition method. The optical properties of the samples can be effectively tuned by varying the oxidation time of aluminum. The coercivity mechanism of the Fe nanowires in our case is consistent with fanning reversal mode. PAA@Fe films can be used in many areas including decoration, display and multifunctional anti-counterfeiting applications.
Artificial insemination in Payoya goats: factors affecting fertility
Authors: Arrebola Francisco , González Olga , Torres Rafael , Abecia José-Alfonso
Published: July 2013

The present study was conducted to determine the effect of different factors on pregnancy rate after artificial insemination (AI) with refrigerated and frozen semen in Payoya goats reared under commercial farm conditions. A total of 820 goats, belonging to 10 farms, was used. The total number of studied inseminations was 1384 over a 4-year period. Factors considered in the study were year, farm, month of AI, age of the goat at AI, dose of progestagen, eCG dose, buck, type of semen (refrigerated or frozen), technician, number of goats to be inseminated (group size), incidences at AI (problems, no problems, trans-cervical insemination), distance from semen collection to farm, number of previous kidding, kidding–AI interval, and milk production. The variable studied was fertility, expressed as successful kidding. Mean fertility was 59%. Six (farm, age, group size, transcervical AI, number of kidding and milk production) of the 15 factors studied presented a significant (P < 0.05) effect on fertility after AI. Our results demonstrated that it is difficult to control all the critical aspects of AI programs at the farm level. These factors should be controlled and the variations that could compromise the chance of being pregnant must be known by technicians. The good fertility results obtained during the non-breeding season emphasise the implementation of this technique so as to improve the competitiveness of the dairy Payoya breed flocks.
From socialist to post-socialist cities: Narrating the nation through urban space
Authors: Diener Alexander C. , Hagen Joshua
Published: July 2013

The development of post-socialist cities has emerged as a major field of study among critical theorists from across the social sciences. Originally constructed under the dictates of central planners and designed to serve the demands of command economies, post-socialist urban centers currently develop at the nexus of varied and often competing economic, cultural, and political forces. Among these, nationalist aspirations, previously simmering beneath the official rhetoric of communist fraternity and veneer of architectural conformity, have emerged as dominant factors shaping the urban landscape. This article examines patterns, processes, and practices concerning the cultural politics of architecture, urban planning, and identity in the post-socialist city. In addition to assessing the main contours of this burgeoning field of research, this article highlights how this special issue ofNationalities Paperscontributes to a broader understanding of contemporary cultural and political change in post-socialist urban settings.
Economic and Social Implications of Regulating Alcohol Availability in Grocery Stores
Authors: Rickard Bradley J. , Costanigro Marco , Garg Teevrat
Published: July 2013

The availability of alcoholic beverages in grocery stores varies across the United States due to state‐level regulations. Recently there have been a number of controversial legislative proposals to expand the distribution of certain alcoholic beverages, most notably wine. Our econometric results show that, holding constant the total quantity of alcohol consumed, a higher share of wine correlates with lower traffic fatality rates, while the opposite is true for beer. These findings suggest that arguments against the wider distribution of wine as an approach to reduce social problems may not be fully justified.
A new theoretical analysis of deindustrialisation
Authors: Tregenna Fiona
Published: July 2013

The analysis of deindustrialisation has been led by heterodox economists, especially those in the structuralist and Kaldorian traditions, based on a conception of sectoral specificity and the role of manufacturing in growth. Sectors are not the units of Marxian economic analysis, but thinking through the meaning of sectors in Marxian terms allows for an analysis of the meaning and implications of a change in sectoral structure. Deindustrialisation is the sectoral shift that has been most prominent in recent decades and which is likely to have significant implications for the future of capitalism. This article develops an original Marxian theorisation of deindustrialisation. This conceptualisation includes a distinction between two forms of deindustrialisation. As well as taking into account changes in sectoral structure, the proposed typology considers whether such changes are associated with a shift between those activities that produce surplus value and those that do not or only a shift in the composition of surplus-value-producing activities. The distinction between different forms of deindustrialisation allows for an arguably richer analysis of this phenomenon than in more narrowly sector-based approaches.
Kinematics of monodisperse and bidisperse granular flows in quasi-two-dimensional bounded heaps
Authors: Fan Yi , Umbanhowar Paul B. , Ottino Julio M. , Lueptow Richard M.
Published: July 2013

Quasi-two-dimensional bounded heap flow is a useful model for many granular flows in industry and nature. It belongs to a family of free surface flows—inclined chute flow, rotating tumbler flow and unbounded heap flow—but differs from the others in that uniform deposition of particles onto the static bed results in the uniform rise of the heap. The kinematics, however, are only partially understood. We performed discrete element method simulations to study granular flows in quasi-two-dimensional bounded heaps. The experimentally validated computational results show a universal functional form for the streamwise velocity profile for both monodisperse and bidisperse systems when velocities and coordinates are scaled by the local surface velocity and the local flowing layer thickness. This holds true regardless of streamwise location, feed rate, particle size distribution and, most surprisingly, the local particle concentration for bidisperse flows. The local surface velocity decreases linearly in the streamwise direction, while the flowing layer thickness remains nearly constant; both quantities depending only on local flow rate and local mean particle diameter. Additionally, the velocity profile normal to the overall flow, which is important in understanding segregation, can be predicted analytically from the streamwise velocity and matches the simulation results.
Travelling light: white sharks (Carcharodon carcharias) rely on body lipid stores to power ocean-basin scale migration
Authors: Del Raye Gen , Jorgensen Salvador J. , Krumhansl Kira , Ezcurra Juan M. , Block Barbara A.
Published: July 2013

Many species undertake long-distance annual migrations between foraging and reproductive areas. Such migrants depend on the efficient packaging, storage and utilization of energy to succeed. A diverse assemblage of organisms accomplishes this through the use of lipid reserves; yet, it remains unclear whether the migrations of elasmobranchs, which include the largest gill breathers on Earth, depend on such a mechanism. We examine depth records from pop-up satellite archival tags to discern changes in buoyancy as a proxy for energy storage in Eastern Pacific white sharks, and assess whether lipid depletion fuels long-distance (approx. 4000 km) migrations. We develop new algorithms to assess body condition, buoyancy and drift rate during drift dives and validate the techniques using a captive white shark. In the wild, we document a consistent increase in drift rate over the course of all migrations, indicating a decrease in buoyancy caused by the depletion of lipid reserves. These results comprise, to our knowledge, the first assessment of energy storage and budgeting in migrating sharks. The methods provide a basis for further insights into using electronic tags to reveal the energetic strategies of a wide range of elasmobranchs.
Colour cues proved to be more informative for dogs than brightness
Authors: Kasparson Anna A. , Badridze Jason , Maximov Vadim V.
Published: July 2013

The results of early studies on colour vision in dogs led to the conclusion that chromatic cues are unimportant for dogs during their normal activities. Nevertheless, the canine retina possesses two cone types which provide at least the potential for colour vision. Recently, experiments controlling for the brightness information in visual stimuli demonstrated that dogs have the ability to perform chromatic discrimination. Here, we show that for eight previously untrained dogs colour proved to be more informative than brightness when choosing between visual stimuli differing both in brightness and chromaticity. Although brightness could have been used by the dogs in our experiments (unlike previous studies), it was not. Our results demonstrate that under natural photopic lighting conditions colour information may be predominant even for animals that possess only two spectral types of cone photoreceptors.
Sphingomicrobium marinum sp. nov. and Sphingomicrobium flavum sp. nov., isolated from surface seawater, and emended description of the genus Sphingomicrobium
Authors: Shahina Mariyam , Hameed Asif , Lin Shih-Yao , Hsu Yi-Han , Liu You-Cheng , Huang Yu-Ming , Lin Jou-Chun , Young Chiu-Chung
Published: July 2013

Two Gram-staining-negative, yellow-pigmented, rod-shaped, strictly aerobic, non-flagellated and non-spore-forming amylolytic marine bacterial strains, designated CC-AMZ-30MTand CC-AMZ-30NT, were isolated from coastal surface seawater in Taiwan. Strain CC-AMZ-30MTshared pairwise 16S rRNA gene sequence similarities of 95.8, 95.0 and <94.0 % toSphingomicrobium lutaoenseCC-TBT-3T,Sphingomicrobium astaxanthinifaciensCC-AMO-30BTand other sphingomonads, respectively. Strain CC-AMZ-30NTshared 97.0, 96.7, 95.0 and <95.1 % similarities to strain CC-AMZ-30MT,Sphingomicrobium lutaoenseCC-TBT-3T,Sphingomicrobium astaxanthinifaciensCC-AMO-30BTand other sphingomonads, respectively. The common polar lipids of the two strains include a signature glycolipid (GL2), diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and sphingoglycolipid in major amounts besides moderate-to-trace amounts of an unidentified aminolipid and several unidentified glycolipids. Both strains contained C18 : 1ω7c/C18 : 1ω6c, C16 : 1ω7c/C16 : 1ω6c, C16 : 0and C18 : 12-OH as major (>5 % of the total) fatty acids. Strains CC-AMZ-30MTand CC-AMZ-30NThad DNA G+C contents of 64.2 and 65.2 mol%, respectively. The major polyamine was spermidine in strain CC-AMZ-30MTand triaminesym-homospermidine in strain CC-AMZ-30NT. Both strains contained ubiquinone Q-10 as the predominant respiratory quinone. Differential phylogenetic and chemotaxonomic evidence including the presence of characteristic GL2, C18 : 12-OH and several other phenotypic features supported the classification of strains CC-AMZ-30MTand CC-AMZ-30NTas two novel species of the genusSphingomicrobium, for which we propose the namesSphingomicrobium marinumsp. nov. andSphingomicrobium flavumsp. nov., respectively; corresponding type strains areSphingomicrobium marinumCC-AMZ-30MT( = JCM 18554T = BCRC 80466T) andSphingomicrobium flavumCC-AMZ-30NT( = JCM 18555T = BCRC 80467T). An emended description of the genusSphingomicrobiumis also proposed.
Flaviramulus ichthyoenteri sp. nov., an N-acylhomoserine lactone-degrading bacterium isolated from the intestine of a flounder (Paralichthys olivaceus), and emended descriptions of the genus Flaviramulus and Flaviramulus basaltis
Authors: Zhang Yunhui , Tang Kaihao , Shi Xiaochong , Zhang Xiao-Hua
Published: July 2013

A Gram-stain-negative, strictly aerobic, yellow-pigmented, rod-shaped andN-acylhomoserine lactone-degrading bacterium, designated strain Th78T, was isolated from the intestine of a cultured flounder (Paralichthys olivaceus). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain Th78Tbelonged to the genusFlaviramulus(familyFlavobacteriaceae) and showed the highest 16S rRNA gene sequence similarity toFlaviramulus basaltisH35T(96.70 %). Optimal growth occurred in the presence of 2–3 % (w/v) NaCl, at pH 7.0–8.0 and at 28 °C. The major fatty acids were iso-C15 : 03-OH, iso-C15 : 1G and iso-C17 : 03-OH. The major polar lipids were phosphatidylethanolamine, one unidentified aminolipid and three unidentified polar lipids. Menaquinone 6 (MK-6) was the only respiratory quinone. The DNA G+C content of strain Th78Twas 31.5 mol%. On the basis of polyphasic analysis, strain Th78Tis considered to represent a novel species of the genusFlaviramulus, for which the nameFlaviramulus ichthyoenterisp. nov. is proposed. The type strain is Th78T( = JCM 18634T = KCTC 32142T = DSM 26285T). Emended descriptions of the genusFlaviramulusandFlaviramulus basaltisare also proposed.
Natranaerobaculum magadiense gen. nov., sp. nov., an anaerobic, alkalithermophilic bacterium from soda lake sediment
Authors: Zavarzina Daria G. , Zhilina Tatyana N. , Kuznetsov Boris B. , Kolganova Tatyana V. , Osipov Georgy A. , Kotelev Mikhail S. , Zavarzin Georgy A.
Published: July 2013

An obligately alkaliphilic, anaerobic, thermo- and halotolerant, spore-forming bacterium was isolated from sediments of soda lake Magadi (Kenya) and designated strain Z-1001T. Cells of strain Z-1001Twere straight, Gram-positive rods, slowly motile. Strain Z-1001Twas found to be an obligate anaerobe. It grew within a pH range from 7.5 to 10.7 with an optimum at 9.25–9.5 (at 40 °C), a temperature range from 20 to 57 °C with an optimum at 45–50 °C, and a NaCl concentration range from 0 to 1.55 M with an optimum at 1.2–1.4 M. Peptides, such as meat and yeast extracts, peptone and tryptone, were fermented by Z-1001T. Carbohydrates did not support growth. With yeast extract as an electron donor, strain Z-1001TreducedS2O32−,NO3−,AsO43−, Fe(III) citrate and anthraquinone-2,6-disulfonate (AQDS) as electron acceptors. The isolate was able to grow oligotrophically with a very small amount of yeast extract: 0.03 g l−1. The main fatty acids were C16 : 0, C16 : 1ω7c, C18 : 0and C18 : 1ω9. The DNA G+C content of the isolate was 35.6 mol%. 16S rRNA gene sequence analysis showed that strain Z-1001Tis a member of familyNatranaerobiaceae, clustering with the type strain ofNatranaerobius thermophilus(95.8–96.0 % sequence similarity). On the basis of physiological and phylogenetic data it is proposed that strain Z-1001T( = DSM 24923T = VKM B-2666T) represents a novel genus and species,Natranaerobaculum magadiensegen. nov., sp. nov.
Antimicrobial susceptibility of animal and human isolates of Clostridium difficile by broth microdilution
Authors: Pirš Tina , Avberšek Jana , Zdovc Irena , Krt Brane , Andlovic Alenka , Lejko-Zupanc Tatjana , Rupnik Maja , Ocepek Matjaž
Published: July 2013

A total of 188 human (n = 92) and animal (n = 96) isolates ofClostridium difficileof different PCR ribotypes were screened for susceptibility to 30 antimicrobials using broth microdilution. When comparing the prevalence of antimicrobial resistance, the isolates of animal origin were significantly more often resistant to oxacillin, gentamicin and trimethoprim/sulfamethoxazole (P<0.01). The most significant difference between the animal and human populations (P = 0.0006) was found in the level of imipenem resistance, with a prevalence of 53.3 % in isolates of human origin and 28.1 % in isolates of animal origin. Overall, the results show similar MICs for the majority of tested antimicrobials for isolates from human and animal sources, which were collected from the same geographical region and in the same time interval. This supports the hypothesis thatC. difficilecould be transmissible between human and animal hosts. Resistant isolates have been found in all animal species tested, including food and companion animals, and also among non-toxigenic isolates. The isolates of the most prevalent PCR ribotype 014/020 had low resistance rates for moxifloxacin, erythromycin, rifampicin and daptomycin, but a high resistance rate for imipenem. Multiresistant strains were found in animals and humans, belonging to PCR ribotypes 012, 017, 027, 045, 046, 078 and 150, and also to non-toxigenic strains of PCR ribotypes 010 and SLO 080.