bluuebunny/crossref_metadata_2025 huggingface dataset:
Ab initio ro-vibronic spectroscopy of SiCCl ($\tilde{X}^2\Pi$X̃2Π)
Authors: Brites Vincent , Mitrushchenkov Alexander O. , Peterson Kirk A. , Léonard Céline
Published: July 2014

The full dimensional potential energy surfaces of the 2A′ and 2A′′ electronic components of \documentclass[12pt]{minimal}\begin{document}$\tilde{X}^2\Pi$\end{document}X̃2Π SiCCl have been computed using the explicitly correlated coupled cluster method, UCCSD(T)-F12b, combined with a composite approach taking into account basis set incompleteness, core-valence correlation, scalar relativity, and higher order excitations. The spin-orbit and dipole moment surfaces have also been computed ab initio. The ro-vibronic energy levels and absorption spectrum at 5 K have been determined from variational calculations. The influence of each correction on the fundamental frequencies is discussed. An assignment is proposed for bands observed in the LIF experiment of Smith et al. [J. Chem. Phys. 117, 6446 (2002)]. The overall agreement between the experimental and calculated ro-vibronic levels is better than 7 cm−1 which is comparable with the 10–20 cm−1 resolution of the emission spectrum.
Radiation induces turbulence in particle-laden fluids
Authors: Zamansky Rémi , Coletti Filippo , Massot Marc , Mani Ali
Published: July 2014

When a transparent fluid laden with solid particles is subject to radiative heating, non-uniformities in particle distribution result in local fluid temperature fluctuations. Under the influence of gravity, buoyancy induces vortical fluid motion which can lead to strong preferential concentration, enhancing the local heating and more non-uniformities in particle distribution. By employing direct numerical simulations this study shows that the described feedback loop can create and sustain turbulence. The velocity and length scale of the resulting turbulence is not known a priori, and is set by balance between viscous forces and buoyancy effects. When the particle response time is comparable to a viscous time scale, introduced in our analysis, the system exhibits intense fluctuations of turbulent kinetic energy and strong preferential concentration of particles.
Determination of the electron–phonon coupling constant in tungsten
Authors: Daraszewicz Szymon L. , Giret Yvelin , Tanimura Hiroshi , Duffy Dorothy M. , Shluger Alexander L. , Tanimura Katsumi
Published: July 2014

We used two methods to determine the effective electron-phonon coupling constant (G0) in tungsten. Our first principles calculations predict G0 = 1.65 × 1017 W m−3 K−1. The temporal decay of the femtosecond-resolution optical reflectivity for a (100) surface of bulk W was measured using a pump-probe scheme and analysed using ab initio parameterised two temperature model, which includes both the effects of the electron-phonon coupling and thermal conduction into bulk. This analysis gives G0 = 1.4(3) × 1017 W m−3 K−1, in good agreement with the theoretical prediction. The described effective method of calculating and measuring G0 in bulk materials can be easily extended to other metals.
Room temperature performance of mid-wavelength infrared InAsSb nBn detectors
Authors: Soibel Alexander , Hill Cory J. , Keo Sam A. , Hoglund Linda , Rosenberg Robert , Kowalczyk Robert , Khoshakhlagh Arezou , Fisher Anita , Ting David Z.-Y. , Gunapala Sarath D.
Published: July 2014

In this work, we investigate the high temperature performance of mid-wavelength infrared InAsSb-AlAsSb nBn detectors with cut-off wavelengths near 4.5 μm. The quantum efficiency of these devices is 35% without antireflection coatings and does not change with temperature in the 77–325 K temperature range, indicating potential for room temperature operation. The current generation of nBn detectors shows an increase of operational bias with temperature, which is attributed to a shift in the Fermi energy level in the absorber. Analysis of the device performance shows that operational bias and quantum efficiency of these detectors can be further improved. The device dark current stays diffusion limited in the 150 K–325 K temperature range and becomes dominated by generation-recombination processes at lower temperatures. Detector detectivities are D*(λ) = 1 × 109 (cm Hz0.5/W) at T = 300 K and D*(λ) = 5 × 109 (cm Hz0.5/W) at T = 250 K, which is easily achievable with a one stage TE cooler.
Bias dependence and correlation of the cathodoluminescence and electron beam induced current from an InGaN/GaN light emitting diode
Authors: Wallace M. J. , Edwards P. R. , Kappers M. J. , Hopkins M. A. , Oehler F. , Sivaraya S. , Allsopp D. W. E. , Oliver R. A. , Humphreys C. J. , Martin R. W.
Published: July 2014

Micron-scale mapping has been employed to study a contacted InGaN/GaN LED using combined electroluminescence (EL), cathodoluminescence (CL), and electron beam induced current (EBIC). Correlations between parameters, such as the EBIC and CL intensity, were studied as a function of applied bias. The CL and EBIC maps reveal small areas, 2–10 μm in size, which have increased nonradiative recombination rate and/or a lower conductivity. The CL emission from these spots is blue shifted, by 30–40 meV. Increasing the reverse bias causes the size of the spots to decrease, due to competition between in-plane diffusion and drift in the growth direction. EL mapping shows large bright areas (∼100 μm) which also have increased EBIC, indicating domains of increased conductivity in the p and/or n-GaN.
Growth temperature effect on the structural and magnetic properties of Fe3O4 films grown by the self-template method
Authors: Takahashi R. , Misumi H. , Lippmaa M.
Published: July 2014

We have investigated the effect of growth temperature on the structure, surface morphology, and magnetic properties of Fe3O4 thin films grown on SrTiO3(001) substrates by a self-template method. To eliminate the intermixing of (001) and (111) orientations that usually occurs in spinel films grown on perovskite substrates, a thin self-template layer of (001)-oriented Fe3O4 was deposited on a SrTiO3(001) substrate at 400 °C prior to the main film growth at temperatures of up to 1100 °C. Increasing the growth temperature from 400 °C to 1100 °C resulted in greatly improved crystallinity of the Fe3O4 thin films, with the rocking curve width dropping from 1.41° to 0.28°. Surface analysis by atomic force microscopy showed that raising the growth temperature increased the grain size and the surface roughness, ultimately leading to the formation of regular nanopyramid arrays at 1100 °C. The surface roughening and pyramid formation are caused by the dominance of the lowest surface energy spinel (111) crystal facet. The nanopyramids were fully relaxed but still perfectly (001)-oriented in the out-of-plane direction. The largest pyramids had the lowest coercivity due to a reduction of the demagnetization effect.
A conversion model of graphite to ultrananocrystalline diamond via laser processing at ambient temperature and normal pressure
Authors: Ren X. D. , Yang H. M. , Zheng L. M. , Yuan S. Q. , Tang S. X. , Ren N. F. , Xu S. D.
Published: July 2014

The synthesis mechanism of ultrananocrystalline diamond via laser shock processing of graphite suspension was presented at room temperature and normal pressure, which yielded the ultrananocrystalline diamond in size of about 5 nm. X-ray diffraction, high-resolution transmission electron microscopy, and laser Raman spectroscopy were used to characterize the nano-crystals. The transformation model and growth restriction mechanism of high power density with short-pulsed laser shocking of graphite particles in liquid was put forward.
Magneto-Rayleigh-Taylor instability in solid media
Authors: Sun Y. B. , Piriz A. R.
Published: July 2014

A linear analysis of the magneto-Rayleigh-Taylor instability at the interface between a Newtonian fluid and an elastic-plastic solid is performed by considering a uniform magnetic B→, parallel to the interface, which has diffused into the fluid but not into the solid. It is found that the magnetic field attributes elastic properties to the viscous fluid which enhance the stability region by stabilizing all the perturbation wavelengths shorter than λ0∝B2 for any initial perturbation amplitude. Longer wavelengths are stabilized by the mechanical properties of the solid provided that the initial perturbation wavelength is smaller than a threshold value determined by the yield strength and the shear modulus of the solid. Beyond this threshold, the amplitude grows initially with a growth rate reduced by the solid strength properties. However, such properties do not affect the asymptotic growth rate which is only determined by the magnetic field and the fluid viscosity. The described physical situation intends to resemble some of the features present in recent experiments involving the magnetic shockless acceleration of flyers plates.
Single photon emission at 1.55 μm from charged and neutral exciton confined in a single quantum dash
Authors: Dusanowski Ł. , Syperek M. , Mrowiński P. , Rudno-Rudziński W. , Misiewicz J. , Somers A. , Höfling S. , Kamp M. , Reithmaier J. P. , Sęk G.
Published: July 2014

We investigate charged and neutral exciton complexes confined in a single self-assembled InAs/InGaAlAs/InP quantum dash emitting at 1.55 μm. The emission characteristics have been probed by measuring high-spatial-resolution polarization-resolved photoluminescence and cross-correlations of photon emission statistics at T = 5 K. The photon auto-correlation histogram of the emission from both the neutral and charged exciton indicates a clear antibunching dip with as-measured g(2)(0) values of 0.18 and 0.31, respectively. It proves that these exciton complexes confined in single quantum dashes of InP-based material system can act as true single photon emitters being compatible with standard long-distance fiber communication technology.
Argon-ion-induced formation of nanoporous GaSb layer: Microstructure, infrared luminescence, and vibrational properties
Authors: Datta D. P. , Kanjilal A. , Satpati B. , Dhara S. , Das T. D. , Kanjilal D. , Som T.
Published: July 2014

Room temperature implantation of 60 keV Ar+-ions in GaSb to the fluences of 7 × 1016 to 3 × 1018 ions cm−2 is carried out at two incidence angles, viz 0° and 60°, leading to formation of a nanoporous layer. As the ion fluence increases, patches grow on the porous layer under normal ion implantation, whereas the porous layer gradually becomes embedded under a rough top surface for oblique incidence of ions. Grazing incidence x-ray diffraction and cross-sectional transmission electron microscopy studies reveal the existence of nanocrystallites embedded in the ion-beam amorphized GaSb matrix up to the highest fluence used in our experiment. Oxidation of the nanoporous layers becomes obvious from x-ray photoelectron spectroscopy and Raman mapping. The correlation of ion-beam induced structural modification with photoluminescence signals in the infrared region has further been studied, showing defect induced emission of additional peaks near the band edge of GaSb.
Resonant nature of intrinsic defect energy levels in PbTe revealed by infrared photoreflectance spectroscopy
Authors: Zhang Bingpo , Cai Chunfeng , Jin Shuqiang , Ye Zhenyu , Wu Huizhen , Qi Zhen
Published: July 2014

Step-scan Fourier-transform infrared photoreflectance and modulated photoluminescence spectroscopy were used to characterize the optical transitions of the epitaxial PbTe thin film grown by molecular beam epitaxy on BaF2 (111) substrate in the vicinity of energy gap of lead telluride at 77 K. It is found that the intrinsic defect energy levels in the electronic structure are of resonant nature. The Te-vacancy energy level is located above the conduction band minimum by 29.1 meV. Another defect (VX) energy level situated below valance band maximum by 18.1 meV is also revealed. Whether it is associated with the Pb vacancy is still not clear. It might also be related to the misfit dislocations stemming from the lattice mismatch between PbTe and BaF2 substrate. The experimental results support the theory prediction (N. J. Parada and G. W. Pratt, Jr., Phys. Rev. Lett. 22, 180 (1969), N. J. Parada, Phys. Rev. B 3, 2042 (1971)) and are consistent with the reported Hall experimental results (G. Bauer, H. Burkhard, H. Heinrich, and A. Lopez-Otero, J. Appl. Phys. 47, 1721 (1976)).
Magnetic ordering in TbMn0.5Cr0.5O3 studied by neutron diffraction and first-principles calculations
Authors: Staruch M. , Sharma V. , dela Cruz C. , Ramprasad R. , Jain M.
Published: July 2014

The structure and magnetic ordering of bulk TbMn0.5Cr0.5O3 was revealed through bulk magnetization and neutron diffraction measurements, and first-principles calculations, respectively. G-type antiferromagnetic ordering of Mn3+ and Cr3+ moments was observed in the neutron diffraction data below Néel temperature TN ∼ 84 K. In addition, below ∼40 K, short-range magnetic ordering was identified correlating to a ferromagnetic component due to the canting of the moments along the c-axis. The spin configuration is consistent with the first-principles calculations. The magnetic structure revealed in the present TbMn0.5Cr0.5O3 sample is distinct from that observed for both end members TbMnO3 and TbCrO3.
Optical properties and energy transfer processes of Ho3+/Er3+- codoped fluorotellurite glass under 1550 nm excitation for 2.0 μm applications
Authors: Huang Feifei , Liu Xueqiang , Hu Lili , Chen Danping
Published: July 2014

This paper investigates 2.0 μm emission properties and energy transfer processes in the Er3+/Ho3+ codoped fluorotellurite glass. The measured absorption spectra demonstrate that the codoped sample can be pumped by 1550 nm excitation efficiently. Judd-Ofelt and radiative parameters are calculated and discussed. Intensive 2.0 μm emission originating from Ho3+: 5I7→5I8 transition is observed and a long lifetime (11 ms) of the 5I7 level is measured when Ho3+ ions are sensitized by Er3+ ions. Meanwhile, the upconversion spectra of the Er3+ singly and codoped samples are obtained and the energy transfer processes of the two ions is discussed based on the change of the upconversion emissions. The microscopic interaction parameters of the phonon-assisted (Er3+: 4I13/2→Ho3+:5I7) process are calculated and the microparameter reaches as high as 10.1 × 10−41 cm6/s. Hence, these results indicate that this Ho3+/Er3+ codoped fluorotellurite glass will be a suitable material for developing solid state laser around 2.0 μm.
Thermal transport along Bi2Te3 topological insulator nanowires
Authors: Yu ChenXi , Zhang Gang , Peng Lian-Mao , Duan Wenhui , Zhang Yong-Wei
Published: July 2014

Using molecular dynamics simulations, we investigate the thermal conductivity and local heat flux distribution of Bi2Te3 nanowires. It is found that at room temperature, the converged length-independent thermal conductivity of Bi2Te3 nanowires is only 0.89 W/m K, which is about 2-fold lower than their bulk counterpart. Interestingly, the local heat flux density along the quintet boundary layer is only about 18% of that along the central layers due to different phonon edge scattering intensities. Our work demonstrates that topological insulator nanostructures are promising candidates for the development of high-performance thermoelectric devices for applications in nanoscale energy generation and temperature management.
Laser-direct-driven quasi-isentropic experiments on aluminum
Authors: Xue Quanxi , Wang Zhebin , Jiang Shaoen , Wang Feng , Ye Xisheng , Liu Jingru
Published: July 2014

Laser-direct-driven ramp compression experiments were performed on long temporally shaped laser pulses based on an analytical isentropic compression model. Upper pressure limits, the ablation pressure scaling law, and stress-density curves were studied. The validity of the analytical model used, the ablation pressure scaling law, and the phenomena of missing line-imaging velocity interferometer (VISAR) fringes in the experimental results are discussed.
Modulating patterns of two-phase flow with electric fields
Authors: Liu Dingsheng , Hakimi Bejan , Volny Michael , Rolfs Joelle , Anand Robbyn K. , Turecek Frantisek , Chiu Daniel T.
Published: July 2014

This paper describes the use of electro-hydrodynamic actuation to control the transition between three major flow patterns of an aqueous-oil Newtonian flow in a microchannel: droplets, beads-on-a-string (BOAS), and multi-stream laminar flow. We observed interesting transitional flow patterns between droplets and BOAS as the electric field was modulated. The ability to control flow patterns of a two-phase fluid in a microchannel adds to the microfluidic tool box and improves our understanding of this interesting fluid behavior.
The creation of knowledge: local building, global accessing and economic
development—toward an agenda
Authors: Bathelt Harald , Cohendet Patrick
Published: July 2014

This article argues that local knowledge building and global (nonlocal) knowledge-accessing practices in economic development are intrinsically interwoven. They generate fundamental feedback loops, which are channeled through and lead to ongoing knowledge circulation. To better understand the nature of the specific mechanisms and conditions underlying these processes, three key areas of research are identified for current and future research. These are related to (i) creative agents and the nature of local creative processes, (ii) community formation and local creativity from ideas to market penetration and (iii) temporary gatherings as translocal knowledge platforms.
Stability analysis of strange-modes in hot massive stars with time-dependent convection
Authors: Sonoi Takafumi , Shibahashi Hiromoto
Published: July 2014

We carry out a nonadiabatic analysis of strange-modes in hot massive stars with time-dependent convection (TDC). In the envelopes of such stars, convective luminosity is not so dominant as it is in the envelopes of stars on the redder side of the classical instability strip. Around the Fe opacity bump, however, convection contributes nonnegligibly to energy transfer. Indeed, we find that the instability of modes excited at the Fe bump is likely to be weaker with TDC as compared with the case of adopting the frozen-in convection (FC) approximation. But we confirm that unstable strange-modes certainly remain in hot massive stars even by taking into account TDC. We also examine properties of the strange-mode instability, which is related to destabilization of strange-modes without adiabatic counterparts. In this type of instability, a phase lag between density and pressure varies from 0° to 180° in an excitation zone, unlike the case of the κ-mechanism. In addition, we confirm by comparing two models with Z = 0 and Z = 0.02 that the dominance of radiation pressure is important for this type of instability.
Use of the 5′ untranslated region and VP1 region to examine the molecular diversity in enterovirus B species
Authors: Zhou Fei , Wang Qinning , Sintchenko Vitali , Gilbert Gwendolyn L. , O’Sullivan Matthew V. N. , Iredell Jonathan R. , Dwyer Dominic E.
Published: July 2014

Human enteroviruses evolve quickly. The 5′ untranslated region (UTR) is fundamentally important for efficient viral replication and for virulence; the VP1 region correlates well with antigenic typing by neutralization, and can be used for virus identification and evolutionary studies. In order to investigate the molecular diversity in EV-B species, the 5′ UTR and VP1 regions were analysed for 208 clinical isolates from a single public-health laboratory (serving New South Wales, Australia), representing 28 EV-B types. Sequences were compared with the 5′ UTR and VP1 regions of 98 strains available in GenBank, representing the same 28 types. The genetic relationships were analysed using two types of software (megaand BioNumerics). The sequence analyses of the 5′ UTR and VP1 regions of 306 EV-B strains demonstrated that: (i) comparing the two regions gives strong evidence of epidemiological linkage of strains in some serotypes; (ii) the intraserotypic genetic variation within each gene reveals that they evolve distinctly largely due to their different functions; and (iii) mutation and possible recombination in the two regions play significant roles in the molecular diversity of EV-B. Understanding the tempo and pattern of molecular diversity and evolution is of great importance in the pathogenesis of EV-B enteroviruses, information which will assist in disease prevention and control.
Outbreaks due to Mycobacterium abscessus subsp. bolletii in southern Brazil: persistence of a single clone from 2007 to 2011
Authors: Nunes Luciana de S. , Baethgen Ludmila F. , Ribeiro Marta O. , Cardoso Cássia M. , de Paris Fernanda , De David Simone M. M. , da Silva Marlei G. , Duarte Rafael S. , Barth Afonso L.
Published: July 2014

Outbreaks associated with rapidly growing mycobacteria (RGM) have been increasingly reported worldwide, including in Brazil. Among the RGM, theMycobacterium abscessuscomplex is the most pathogenic and related to multidrug resistance. The aim of this study was to evaluate the antimicrobial susceptibility and molecular profile of RGM isolates involved in new postsurgical infection outbreaks in Brazil since 2007. Of the 109 cases reported in the state of Rio Grande do Sul between 2007 and 2011, 43 (39 %) had confirmed mycobacterial growth in culture. Clinical isolates were obtained from biopsy specimens or abscess aspirates. PRA-hsp65restriction pattern identified the isolates asM. abscessustype 2, and partialrpoBsequencing confirmed the identification asM. abscessussubsp.bolletii. All isolates were susceptible to amikacin and resistant to ciprofloxacin, doxycycline, sulfamethoxazole, moxifloxacin and tobramycin. Most isolates (72 %) were fully susceptible to cefoxitin but six isolates (14 %) were fully resistant to clarithromycin. The latter differed from the susceptibility profiles of the previously described BRA100 clone from other Brazilian regions. Nevertheless, pulsed-field gel electrophoresis analysis revealed that these isolates belonged to a single BRA100 clone. In conclusion, our study reports the persistence of an emergent single and highly resistant clone ofM. abscessussubsp.bolletiifor several years even after national implementation of infection control measures.
Expression levels of transcription factors in Escherichia coli: growth phase- and growth condition-dependent variation of 90 regulators from six families
Authors: Yamamoto Kaneyoshi , Watanabe Hiroki , Ishihama Akira
Published: July 2014

The expression pattern of the genome in Escherichia coli is controlled by regulating the utilization of a limited number of RNA polymerases between a total of 4600 genes on its genome. The distribution pattern of RNA polymerase on the genome changes after two steps of protein–protein interaction with seven sigma subunits and about 300 transcription factors (TFs). Based on a systematic search for the regulation target promoters recognized by each TF, we propose two novel concepts: each TF regulates a number of target promoters; and each promoter is regulated by many TFs. In parallel, attempts have been made to determine the intracellular concentrations of all TFs using two systems: quantitative immunoblot analysis using TF-specific antibodies; and reporter assay of TF promoter activities. The direct measurement of TF protein level has so far been published for a set of 60 regulators with known functions. This study describes the determination of growth phase-dependent expression levels of 90 TFs using the reporter assay system. The translational fusion vector was constructed from the TF promoter sequence including an N-terminal proximal TF segment and the reporter GFP. At the beginning of cell growth, high-level expression was observed only for a small number of TFs. In the exponential phase, approximately 80 % TFs are expressed, but the expressed TF species change upon transfer to the stationary phase. Significant changes in the pattern of TF expression were observed between aerobic and anaerobic conditions. The list of intracellular levels of TFs provides further understanding to the transcription regulation of the E. coli genome under various stressful conditions.
CPK13, a Noncanonical Ca2+-Dependent Protein Kinase, Specifically Inhibits KAT2 and KAT1 Shaker K+ Channels and Reduces Stomatal Opening
Authors: Ronzier Elsa , Corratgé-Faillie Claire , Sanchez Frédéric , Prado Karine , Brière Christian , Leonhardt Nathalie , Thibaud Jean-Baptiste , Xiong Tou Cheu
Published: July 2014

Ca2  +-dependent protein kinases (CPKs) form a large family of 34 genes in Arabidopsis (Arabidopsis thaliana). Based on their dependence on Ca2+, CPKs can be sorted into three types: strictly Ca2+-dependent CPKs, Ca2+-stimulated CPKs (with a significant basal activity in the absence of Ca2+), and essentially calcium-insensitive CPKs. Here, we report on the third type of CPK, CPK13, which is expressed in guard cells but whose role is still unknown. We confirm the expression of CPK13 in Arabidopsis guard cells, and we show that its overexpression inhibits light-induced stomatal opening. We combine several approaches to identify a guard cell-expressed target. We provide evidence that CPK13 (1) specifically phosphorylates peptide arrays featuring Arabidopsis K+ Channel KAT2 and KAT1 polypeptides, (2) inhibits KAT2 and/or KAT1 when expressed in Xenopus laevis oocytes, and (3) closely interacts in plant cells with KAT2 channels (Förster resonance energy transfer-fluorescence lifetime imaging microscopy). We propose that CPK13 reduces stomatal aperture through its inhibition of the guard cell-expressed KAT2 and KAT1 channels.
Dynamic Transcriptome Landscape of Maize Embryo and Endosperm Development
Authors: Chen Jian , Zeng Biao , Zhang Mei , Xie Shaojun , Wang Gaokui , Hauck Andrew , Lai Jinsheng
Published: July 2014

Maize (Zea mays) is an excellent cereal model for research on seed development because of its relatively large size for both embryo and endosperm. Despite the importance of seed in agriculture, the genome-wide transcriptome pattern throughout seed development has not been well characterized. Using high-throughput RNA sequencing, we developed a spatiotemporal transcriptome atlas of B73 maize seed development based on 53 samples from fertilization to maturity for embryo, endosperm, and whole seed tissues. A total of 26,105 genes were found to be involved in programming seed development, including 1,614 transcription factors. Global comparisons of gene expression highlighted the fundamental transcriptomic reprogramming and the phases of development. Coexpression analysis provided further insight into the dynamic reprogramming of the transcriptome by revealing functional transitions during maturation. Combined with the published nonseed high-throughput RNA sequencing data, we identified 91 transcription factors and 1,167 other seed-specific genes, which should help elucidate key mechanisms and regulatory networks that underlie seed development. In addition, correlation of gene expression with the pattern of DNA methylation revealed that hypomethylation of the gene body region should be an important factor for the expressional activation of seed-specific genes, especially for extremely highly expressed genes such as zeins. This study provides a valuable resource for understanding the genetic control of seed development of monocotyledon plants.
Functional Evidence for the Critical Amino-Terminal Conserved Domain and Key Amino Acids of Arabidopsis 4-HYDROXY-3-METHYLBUT-2-ENYL DIPHOSPHATE REDUCTASE
Authors: Hsieh Wei-Yu , Sung Tzu-Ying , Wang Hsin-Tzu , Hsieh Ming-Hsiun
Published: July 2014

The plant 4-HYDROXY-3-METHYLBUT-2-ENYL DIPHOSPHATE REDUCTASE (HDR) catalyzes the last step of the methylerythritol phosphate pathway to synthesize isopentenyl diphosphate and its allyl isomer dimethylallyl diphosphate, which are common precursors for the synthesis of plastid isoprenoids. The Arabidopsis (Arabidopsis thaliana) genomic HDR transgene-induced gene-silencing lines are albino, variegated, or pale green, confirming that HDR is essential for plants. We used Escherichia coli isoprenoid synthesis H (Protein Data Bank code 3F7T) as a template for homology modeling to identify key amino acids of Arabidopsis HDR. The predicted model reveals that cysteine (Cys)-122, Cys-213, and Cys-350 are involved in iron-sulfur cluster formation and that histidine (His)-152, His-241, glutamate (Glu)-242, Glu-243, threonine (Thr)-244, Thr-312, serine-379, and asparagine-381 are related to substrate binding or catalysis. Glu-242 and Thr-244 are conserved only in cyanobacteria, green algae, and land plants, whereas the other key amino acids are absolutely conserved from bacteria to plants. We used site-directed mutagenesis and complementation assay to confirm that these amino acids, except His-152 and His-241, were critical for Arabidopsis HDR function. Furthermore, the Arabidopsis HDR contains an extra amino-terminal domain following the transit peptide that is highly conserved from cyanobacteria, and green algae to land plants but not existing in the other bacteria. We demonstrated that the amino-terminal conserved domain was essential for Arabidopsis and cyanobacterial HDR function. Further analysis of conserved amino acids in the amino-terminal conserved domain revealed that the tyrosine-72 residue was critical for Arabidopsis HDR. These results suggest that the structure and reaction mechanism of HDR evolution have become specific for oxygen-evolving photosynthesis organisms and that HDR probably evolved independently in cyanobacteria versus other prokaryotes.
Strigolactone Involvement in Root Development, Response to Abiotic Stress, and Interactions with the Biotic Soil Environment
Authors: Kapulnik Yoram , Koltai Hinanit
Published: July 2014

Strigolactones, recently discovered as plant hormones, regulate the development of different plant parts. In the root, they regulate root architecture and affect root hair length and density. Their biosynthesis and exudation increase under low phosphate levels, and they are associated with root responses to these conditions. Their signaling pathway in the plant includes protein interactions and ubiquitin-dependent repressor degradation. In the root, they lead to changes in actin architecture and dynamics as well as localization of the PIN-FORMED auxin transporter in the plasma membrane. Strigolactones are also involved with communication in the rhizosphere. They are necessary for germination of parasitic plant seeds, they enhance hyphal branching of arbuscular mycorrhizal fungi of the Glomus and Gigaspora spp., and they promote rhizobial symbiosis. This review focuses on the role played by strigolactones in root development, their response to nutrient deficiency, and their involvement with plant interactions in the rhizosphere.
Customer Franchise—A Hidden, Yet Crucial, Asset
Authors: Bonacchi Massimiliano , Kolev Kalin , Lev Baruch
Published: July 2014

We introduce a measure of customer franchise value for subscription‐based companies—a fast growing and vital sector of the economy. This measure is based on information voluntarily disclosed by some, but not all, firms. Controlling for self‐selection, we examine the measure's information content and find that customer value is significantly positively associated with stock price and this association is incremental to both GAAP and a set of non‐GAAP variables typically considered in valuation tests. Furthermore, we show that the customer value measure is positively associated with future earnings and analysts' forecast errors. Importantly, we find that the documented results are robust to controlling for the individual inputs used to derive the measure, highlighting the need to consider the interaction between stand‐alone value drivers in assessing a firm's performance. These findings indicate that the proposed measure of customer value is an important valuation tool that quantifies and summarizes the main trends and factors underlying the performance of subscription‐based enterprises. This study informs researchers and investors, as well as accounting policymakers, about a major value‐generating asset currently missing from corporate financial reports.
Contact sensitizer 2,4‐dinitrochlorobenzene is a highly potent human TRPA1 agonist
Authors: Saarnilehto M. , Chapman H. , Savinko T. , Lindstedt K. , Lauerma A. I. , Koivisto A.
Published: July 2014

2,4‐Dinitrochlorobenzene (DNCB) is widely used in human clinical studies and in experimental animal studies to evoke allergic contact dermatitis. 2,4‐Dinitrochlorobenzene is a potent immunogen capable of inducing contact sensitization in all humans exposed. However, the mechanism by which DNCB evokes such symptoms is presently unknown. TRPA1 is a nonselective cation channel that is expressed in peptidergic sensory neurons and fibroblasts. TRPA1 activation was recently implicated in the pathophysiology of atopic dermatitis especially in transducing cutaneous itch signals. Here, we test the hypothesis that DNCB acts as a TRPA1 agonist and thereby evokes allergic symptoms. We found that DNCB activates human TRPA1 dose dependently in FLIPR experiments with an EC50 of 167 nM, an effect that was fully blocked by selective TRPA1 antagonists Chembridge‐5861528 and A‐967079. Similarly, DNCB activated nonselective TRPA1 current in patch clamp studies. Neutralization of 3 critical cysteines in TRPA1 resulted in a loss of DNCB agonism.
Volumetric bone mineral density and bone geometry assessed by peripheral quantitative computed tomography in women with differentiated thyroid cancer under TSH suppression
Authors: Tournis Symeon , Antoniou Julia D. , Liakou Chrysoula G. , Christodoulou John , Papakitsou Evangellia , Galanos Antonios , Makris Konstantinos , Marketos Helen , Nikopoulou Stamatina , Tzavara Ioanna , Triantafyllopoulos Ioannis K. , Dontas Ismene , Papaioannou Nikolaos , Lyritis Georgios P. , Alevizaki Maria
Published: July 2014

Objective

TSH suppression therapy in patients with differentiated thyroid cancer (DTC) has been associated with adverse effects on areal bone mineral density (aBMD) only in postmenopausal women. The purpose of study was to examine the effect of TSH suppression therapy on skeletal integrity using peripheral quantitative computed tomography (pQCT) at the radius and tibia in pre‐ and postmenopausal women with DTC and controls.

Study design and patients

Subjects included 80 women with DTC (40 pre‐ and 40 postmenopausal) and 89 (29 and 60, respectively) controls. pQCT was performed at the radius and tibia, Dual‐energy X‐ray absorptiometry (DXA) at the hip and lumbar spine, while samples were taken for calciotropic hormones and bone markers.

Results

No differences were observed concerning aBMD by DXA. In premenopausal women, there were no significant differences concerning vBMD, while cortical thickness was higher at the radius in patients with DTC (P < 0·01) compared with controls. In postmenopausal women with DTC trabecular bone mineral content (BMC), area and vBMD were lower at the radius (all P < 0·05), while at the tibia trabecular BMC and vBMD were lower at the mixed transition zone (14% from the distal end, P < 0·05) compared with controls. Cortical thickness was lower at the radius (P < 0·01) in postmenopausal patients compared with controls. Serum CTX was higher in postmenopausal women with DCT (P < 0·01), while in premenopausal patients, parathyroid hormone (PTH) was lower (P = 0·01) compared with controls.

Conclusions

TSH suppression therapy is associated with higher bone resorption only in postmenopausal women; this adversely affects trabecular and cortical bone properties especially at nonweight‐bearing sites such as the radius.
Quality of life of patients with 46,XX and 46,XY disorders of sex development
Authors: Amaral Rita Cassia , Inacio Marlene , Brito Vinicius N. , Bachega Tania A. S. S. , Domenice Sorahia , Arnhold Ivo J. P. , Madureira Guiomar , Gomes Larissa , Costa Elaine M. F. , Mendonca Berenice B.
Published: July 2014

Disorders of sex development (DSD) result from abnormalities in the complex process of sex determination and differentiation. An important consideration to guide the assignment of social sex in newborns with ambiguous genitalia is the quality of life (QoL) of these patients in adulthood. The rarity of most DSD conditions makes it difficult to conduct a long‐term follow‐up of affected patients through adulthood. This review of papers on the QoL of DSD patients evaluated in developing and developed countries by qualitative and quantitative instruments revealed a large spectrum of QoL, ranging from very poor to similar to, or even better than, the normal population. A more adequate QoL was found in patients from tertiary centres, indicating that the medical care of DSD patients should be multidisciplinary and carried out by specialized teams.
A cut‐off value of basal serum calcitonin for detecting macroscopic medullary thyroid carcinoma
Authors: Kwon Hyemi , Kim Won Gu , Choi Yun Mi , Jang Eun Kyung , Jeon Min Ji , Song Dong Eun , Baek Jung Hwan , Ryu Jin‐Sook , Hong Suck Joon , Kim Tae Yong , Kim Won Bae , Shong Young Kee
Published: July 2014

Objective

Serum calcitonin (CT) level is used to detect medullary thyroid carcinoma (MTC), but the cut‐off level is unclear. We aimed at identifying the optimal cut‐off value of basal serum CT levels for detecting MTC.

Design and patients

We retrospectively enrolled patients with hypercalcitoninemia (≥2·9 pmol/l) who had undergone thyroid ultrasonography (US) and subsequent work‐up between 2001 and 2013 at Asan Medical Center. We divided patients into four groups: proven MTC (group 1, n = 93), pathologically proven non‐MTC after surgery (group 2, n = 57), benign single nodule by cytology (group 3, n = 68) and patients without nodules on US (group 4, n = 24).

Measurement

Basal serum CT levels were evaluated.

Results

The median CT level of group 1 (119·5 pmol/l) was significantly higher than those of other groups (4·0, 3·8 and 3·8 pmol/l, P < 0·001). When we adopted 19·0 pmol/l of CT level as a cut‐off value, the sensitivity, specificity, and positive and negative predictive values were 77·4%, 98·7%, 97·3% and 87·8%, respectively. When we compared 29·2 pmol/l (100 pg/ml) and 19·0 pmol/l (65 pg/ml) as cut‐off values, 19·0 pmol/l was more sensitive and accurate than 29·2 pmol/l. Factors associated with hypercalcitoninemia in non‐MTC groups were autoimmune thyroiditis, chronic kidney disease, proton pump inhibitors and other malignancies. Serum CT levels tended to decrease spontaneously in non‐MTC groups.

Conclusion

Basal serum CT levels higher than 19·0 pmol/l can be a useful cut‐off value for detecting macroscopic MTC, even though values below 19·0 pmol/l cannot exclude the presence of MTC like small volume MTC or premalignant C‐cell hyperplasia.
Latitudinal variation in growth and otolith‐inferred field metabolic rates of Canadian young‐of‐the‐year Arctic charr
Authors: Niloshini Sinnatamby R. , Brian Dempson J. , Reist James D. , Power Michael
Published: July 2014

Countergradient variation (CGV) is defined as genetic variation that counteracts the negative influences of the physical environment, minimising phenotypic variability along an environmental gradient. CGV is thought to have relevance in predicting the response of organisms to climate variability and change. To test the hypothesis that growth rate increased with latitude, consistent with CGV, young‐of‐the‐year (YOY) Arctic charr, Salvelinus alpinus, were examined along a ~27° latitudinal gradient in central and eastern Canada. Growth rates were estimated from fork lengths standardised by the thermal opportunity for growth based on experienced water temperatures derived using otolith oxygen stable isotopes. Results demonstrated patterns consistent with CGV, where northern populations demonstrated faster growth rates. A secondary aim was to test for similar geographical patterns in otolith‐inferred metabolic rates, which reflect the energetic costs of standard metabolic rate (SMR) and other processes such as feeding, locomotion, thermoregulation, reproduction and growth. Results demonstrated a significant, positive relationship between otolith‐inferred metabolic rate and latitude, which may reflect an increase in one, or a combination, of the above‐noted physiological processes. The similar latitudinal pattern in growth and otolith‐inferred metabolic rates suggests greater intake of food per unit of time by northern fish. The phenotypic variation in physiological traits observed here demonstrates the significant adaptability of Arctic charr to different thermal regimes with different growing season lengths. Determining the relative contributions of phenotypic plasticity and genetic variation to the observed latitudinal variation will be critical to predicting the responses of Arctic charr to climate change more accurately.
DC–T cell virological synapses and the skin: novel perspectives in dermatology
Authors: Shimauchi Takatoshi , Piguet Vincent
Published: July 2014

Virological synapses (VS) increase cell‐to‐cell viral transmission and facilitate propagation of human immunodeficiency virus type 1 (HIV‐1) and human T‐cell leukaemia virus type 1 (HTLV‐1). VS formation also plays a more general role in viral replication and dissemination. VS have been observed in vitro and ex vivo between uninfected T cells and T cells infected with HIV‐1 or HTLV‐1. In addition, dendritic cells (DC) infected with HIV‐1 also play an important role in viral transmission to uninfected CD4+ T cells via VS formation. Recent studies revealed that several DC subsets are also infected with HTLV‐1. These findings may help explain the rapid dissemination of both viruses within secondary lymphoid tissues in vivo. VS also explain, at least in part, why HIV‐1 can propagate in the mucosal sites during sexual transmission. Furthermore, in the case of HTLV‐1, VS can potentially explain some of the features of HTLV‐1‐associated dermatitis as infected T cells in the skin contribute to the pathogenesis of this condition.
Herbage production and persistence of two tropical perennial grasses and forage sorghum under different nitrogen fertilization and defoliation regimes in a summer‐dominant rainfall environment, Australia
Authors: Boschma S. P. , Murphy S. R. , Harden S.
Published: July 2014

An experiment was conducted in inland northern New South Wales (NSW) to assess the response of tropical perennial grasses Chloris gayana (Rhodes grass) cv. Katambora and Digitaria eriantha (digit grass) cv. Premier and annual forage sorghum (Sorghum bicolor ssp. bicolor × S. bicolor ssp. drummondii hybrid) cv. Sweet Jumbo fertilized with five rates of nitrogen (N; 0, 50, 100, 150 and 300 kg N ha−1) and defoliated every 2 or 6 weeks over two growing seasons. Tropical perennial grasses were highly responsive to N fertilizer, while there was no significant response by forage sorghum. Herbage production of Rhodes grass increased linearly whereas digit grass had a high response at 50–100 kg N ha−1. Nitrogen‐use efficiency was highest during the growing season when rainfall was higher. During this season, digit grass had the highest N efficiency (148 kg DM kg−1 N applied) at 50 kg N ha−1, and Rhodes grass (66 kg DM kg−1 N applied) at 100 kg N ha−1. Plant frequency of both perennial species increased and then stabilized at high levels (>84%, cell size 0·1 by 0·1 m) during the two growing seasons. Plant frequency of Rhodes grass declined over the winter period, but recovered within 6 weeks of commencement of the growing season. Soil nitrate levels indicated that unused nitrate moved down the soil profile during wet winters. Implications of leaching below the rooting zone are discussed.
Prospective Study of Effects of Endogenous Estrogens on Myocardial No‐Reflow Risk in Postmenopausal Women with Acute Myocardial Infarction
Authors: DONG MEI , MU NAN , REN FAXIN , SUN XIAOJIAN , LI FENGLI , ZHANG CHUANHUAN , YANG JUN
Published: July 2014

The relationship between endogenous estrogens and cardiovascular disease in menopausal women remains poorly understood. Studies examining the relationship have yielded conflicting results. Therefore, we performed this study to prospectively assess the effects of endogenous estrogen on the risk of myocardial no‐reflow in postmenopausal women with ST‐elevation myocardial infarction (STEMI). Consecutive 100 postmenopausal women diagnosed with STEMI and who had undergone emergence percutaneous coronary intervention (PCI) were included in this study. Blood samples were obtained before PCI and assayed for endogenous sex hormones. Logistic regression models were developed with adjustment for confounders. Compared with normal‐reflow group, the circulating levels of estrone, estradiol, sex hormone binding globulin (SHBG), and hypersensitive C‐reaction protein (Hs‐CRP) were significantly higher in the no‐reflow group (P < 0.05). In univariable logistic regression models, lesion length, reference luminal diameter, thrombus score ≥ 4, and the levels of estrone, estradiol, and SHBG were all found to be positively associated with the risk of no‐reflow (P < 0.05). After adjusting for these factors, thrombus score ≥ 4 (OR = 4.994, CI 1.987–10.518; P = 0.035), SHBG (OR = 0.800, CI 0.341–0.983; P = 0.047), and estradiol levels (OR 4.091, CI 1.105–8.582; P = 0.046) continued to demonstrate strong positive associations with the risk of no‐reflow. Our data showed that high circulating levels of endogenous estrogens have a positive and statistically significant relationship with no‐reflow in postmenopausal women with STEMI. It has been suggested that estrogens may have a potential detrimental effect on myocardial no‐reflow. However, our results need to be confirmed in a larger population. (J Interven Cardiol 2014;27:437–443)
Switching Patients from Clopidogrel to Prasugrel in Acute Coronary Syndrome: Impact of the Clopidogrel Loading Dose on Platelet Reactivity
Authors: LHERMUSIER THIBAULT , LIPINSKI MICHAEL J. , DRENNING DAVID , MARSO STEVEN , CHEN FANG , TORGUSON REBECCA , WAKSMAN RON
Published: July 2014

Objectives

The present study aimed to assess the pharmacodynamic response of a prasugrel 60‐mg loading dose (LD) alone compared with prasugrel 60 mg added to clopidogrel 600 mg.

Background

Patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) commonly receive a clopidogrel LD prior to angiography. Switching these patients to prasugrel may be desirable because higher platelet inhibition is expected.

Methods

In this open‐label, multicenter, nonrandomized trial, 75 patients were categorized into 2 treatment strategies: Those who received a clopidogrel 600‐mg LD and received a reloading dose of prasugrel 60 mg (clopidogrel/prasugrel group) and those who did not receive a clopidogrel LD and received a prasugrel 60‐mg LD (prasugrel group). Platelet reactivity was assessed using VerifyNow P2Y12 reaction units (PRU) and Platelet Reactivity Index vasodilator‐stimulated phosphoprotein phosphorylation (PRI‐VASP) at 3 different times: at the sheath insertion prior to prasugrel LD, 4 hours after prasugrel LD, and at discharge.

Results

Four hours after prasugrel LD, platelet reactivity did not differ between the clopidogrel/prasugrel group and the prasugrel group according to the VerifyNow assay (median PRU 23 [5–71] vs. 54 [5–91], respectively; P = 0.18) and the VASP assay (median PRI 8.67 [4.51–16.85] versus 8.03 [4.82–21.72], respectively; P = 1.0). No significant differences in PRU and PRI were observed at discharge. Few bleeding events were reported without any significant differences between the 2 groups.

Conclusions

Platelet reactivity with prasugrel 60 mg added to a clopidogrel 600‐mg LD was not significantly different compared with prasugrel 60 mg alone in ACS patients undergoing PCI. (J Interven Cardiol 2014;27:365–372)