bluuebunny/crossref_metadata_2025 huggingface dataset:
A one-dimensional Fickian model to predict the Ga depth profiles in three-stage Cu(In,Ga)Se2
Authors: Rodriguez-Alvarez H. , Mainz R. , Sadewasser S.
Published: May 2014

We present a one-dimensional Fickian model that predicts the formation of a double Ga gradient during the fabrication of Cu(In,Ga)Se2 thin films by three-stage thermal co-evaporation. The model is based on chemical reaction equations, structural data, and effective Ga diffusivities. In the model, the Cu(In,Ga)Se2 surface is depleted from Ga during the deposition of Cu-Se in the second deposition stage, leading to an accumulation of Ga near the back contact. During the third deposition stage, where In-Ga-Se is deposited at the surface, the atomic fluxes within the growing layer are inverted. This results in the formation of a double Ga gradient within the Cu(In,Ga)Se2 layer and reproduces experimentally observed Ga distributions. The final shape of the Ga depth profile strongly depends on the temperatures, times and deposition rates used. The model is used to evaluate possible paths to flatten the marked Ga depth profile that is obtained when depositing at low substrate temperatures. We conclude that inserting Ga during the second deposition stage is an effective way to achieve this.
Theoretical research on ultrasonic sensors based on high-order Lamb waves
Authors: Chen Zhe , Fan Li , Zhang Shu-yi , Zhang Hui
Published: May 2014

In an ultrasonic sensor, the electromechanical coupling coefficient, sensitivities related to the mass load and conductivity variation, insert loss and minimum detectable mass are important parameters determining the performance of the sensor, while it is challenging to optimize the abovementioned five parameters simultaneously. In this paper, we show that the multi-mode characteristic of Lamb wave provides possibilities to improve the performance of ultrasonic sensors by simultaneously considering the five parameters. According to the simulated results, piezoelectric films, relative thicknesses of films and substrates, structures of interdigital transducers, operating wavelengths and frequencies are optimized based on properly selected operating modes of Lamb wave. Then, high performance of Lamb wave sensors can be realized, in which high electromechanical coupling coefficients, mass sensitivities and conductivity sensitivities in addition to low insert losses and minimum detectable masses are simultaneously achieved.
Theory of suppressing avalanche process of carrier in short pulse laser irradiated dielectrics
Authors: Deng H. X. , Zu X. T. , Zheng W. G. , Yuan X. D. , Xiang X. , Sun K. , Gao F.
Published: May 2014

A theory for controlling avalanche process of carrier during short pulse laser irradiation is proposed. We show that avalanche process of conduction band electrons (CBEs) is determined by the occupation number of phonons in dielectrics. The theory provides a way to suppress avalanche process and a direct judgment for the contribution of avalanche process and photon ionization process to the generation of CBEs. The obtained temperature dependent rate equation shows that the laser induced damage threshold of dielectrics, e.g., fused silica, increase nonlinearly with the decreases of temperature. Present theory predicts a new approach to improve the laser induced damage threshold of dielectrics.
Long and short term effects of plasma treatment on meristematic plant cells
Authors: Puač N. , Živković S. , Selaković N. , Milutinović M. , Boljević J. , Malović G. , Petrović Z. Lj.
Published: May 2014

In this paper, we will present results of plasma treatments of meristematic cells of Daucus carota. Plasma needle was used as an atmospheric pressure/gas composition source of non-equilibrium plasma in all treatments. Activity of antioxidant enzymes superoxide dismutase and catalase was measured immediately after plasma treatment and after two weeks following the treatment. Superoxide dismutase activity was increased in samples immediately after the plasma treatment. On the other hand, catalase activity was much higher in treated samples when measured two weeks after plasma treatment. These results show that there is a direct proof of the triggering of signal transduction in the cells by two reactive oxygen species H2O2 and O2−, causing enzyme activity and short and long term effects even during the growth of calli, where the information is passed to newborn cells over the period of two weeks.
Electronic transitions in GdN band structure
Authors: Vidyasagar R. , Kita T. , Sakurai T. , Ohta H.
Published: May 2014

Using the near-infrared (NIR) absorbance spectroscopy, electronic transitions and spin polarization of the GdN epitaxial film have been investigated; and the GdN epitaxial film was grown by a reactive rf sputtering technique. The GdN film exhibited three broad bands in the NIR frequency regimes; and those bands are attributable primarily to the minority and majority spin transitions at the X-point and an indirect transition along the Γ-X symmetric direction of GdN Brillouin zone. We experimentally observe a pronounced red-shift of the indirect band gap when cooling down below the Curie temperature which is ascribed to the orbital-dependent coulomb interactions of Gd-5dxy electrons, which tend to push-up the N-2p bands. On the other hand, we have evaluated the spin polarization of 0.17 (±0.005), which indicates that the GdN epitaxial film has almost 100% spin-polarized carriers. Furthermore, the experimental result of GdN electronic transitions are consistent with the previous reports and are thus well-reproduced. The Arrott plots evidenced that the Curie temperature of GdN film is 36 K and the large spin moment is explained by the nitrogen vacancies and the intra-atomic exchange interaction.
Ultrafast pressure-sensitive paint for shock compression spectroscopy
Authors: Banishev Alexandr A. , Dlott Dana D.
Published: May 2014

A pressure-sensitive paint (PSP) consisting of rhodamine 6G (R6G) dye in poly-methylacryate (PMMA) polymer is studied during nanosecond GPa shock compression created by km s−1 laser-launched layer plates. In contrast with conventional PSP, whose response time is limited to microseconds by diffusion of O2 in porous materials, the response time of this PSP is limited to ∼10 ns by fundamental photophysical processes. The mechanism of shock-induced PSP intensity loss is shown to be shock-enhanced intersystem crossing, which transfers some R6G population from the emissive S1 state to the dark T1 state. Simulations of dye photophysics and comparisons to experiment show that the PSP is sensitive to the complicated time-dependent density profiles produced in PMMA by different duration shocks. The risetime of the PSP response is limited by the S1 lifetime under shock compression. The fall time is limited by the T1 lifetime, which can be decreased by adding triplet quenchers. The PSP can function in two modes. When dissolved O2 (a triplet quencher) was eliminated, the fall time became relatively slow (microseconds), and the PSP sampled the peak shock pressure and held that value for a long time. When dissolved O2 was present, the intensity loss recovery became faster, so the PSP could function as a transient recorder of the shock-induced time-dependent density profile.
Particle transport inferences from density sawteeth
Authors: Chen J. , Li Q. , Zhuang G. , Liao K. , Gentle K. W.
Published: May 2014

Sawtooth oscillations in tokamaks are defined by their effect on electron temperature: a rapid flattening of the core profile followed by an outward heat pulse and a slow core recovery caused by central heating. Recent high-resolution, multi-chord interferometer measurements on JTEXT extend these studies to particle transport. Sawteeth only partially flatten the core density profile, but enhanced particle diffusion on the time scale of the thermal crash occurs over much of the profile, relevant for impurities. Recovery between crashes implies an inward pinch velocity extending to the center.
(Sr,Ba)(Si,Ge)2 for thin-film solar-cell applications: First-principles study
Authors: Kumar Mukesh , Umezawa Naoto , Imai Motoharu
Published: May 2014

In order to meet the increasing demand for electric power generation from solar energy conversion, the development of efficient light absorber materials has been awaited. To this end, the electronic and optical properties of advanced alkaline-earth-metals disilicides and digermanides (SrSi2, BaSi2, SrGe2, and BaGe2) are studied by means of the density functional theory using HSE06 exchange-correlation energy functional. Our calculations show that all these orthorhombic structured compounds have fundamental indirect band gaps in the range Eg ≈ 0.89–1.25 eV, which is suitable for solar cell applications. The estimated lattice parameters and band gaps are in good agreement with experiments. Our calculations show that the electronic band structures of all four compounds are very similar except in the vicinity of the Γ-point. The valence band of these compounds is made up by Si(Ge)-p states, whereas the conduction band is composed of Sr(Ba)-d states. Their band alignments are carefully determined by estimating the work function of each compound using slab model. The optical properties are discussed in terms of the complex dielectric function ε(ω) = ε1(ω) + iε2(ω). The static and high-frequency dielectric constants are calculated, taking into account the ionic contribution. The absorption coefficient α(ω) demonstrates that a low energy dispersion of the conduction band, which results in a flat conduction band minimum, leads to large optical activity in these compounds. Therefore, alkaline-earth-metals disilicides and digermanides possess great potential as light absorbers for applications in thin-film solar cell technologies.
Magnetization switching in a CoFeB/MgO magnetic tunnel junction by combining spin-transfer torque and electric field-effect
Authors: Kanai S. , Nakatani Y. , Yamanouchi M. , Ikeda S. , Sato H. , Matsukura F. , Ohno H.
Published: May 2014

We propose and demonstrate a scheme for magnetization switching in magnetic tunnel junctions, in which two successive voltage pulses are applied to utilize both spin-transfer torque and electric field effect. Under this switching scheme, a CoFeB/MgO magnetic tunnel junction with perpendicular magnetic easy axis is shown to switch faster than by spin-transfer torque alone and more reliably than that by electric fields alone.
Effect of band offset on carrier transport and infrared detection in InP quantum dots/Si nano-heterojunction grown by metalorganic chemical vapor deposition technique
Authors: Halder Nripendra N. , Biswas Pranab , Nagabhushan B. , Kundu Souvik , Biswas D. , Banerji P.
Published: May 2014

Epitaxy of III-V semiconductors on Si gets recent interest for next generation system on heterogeneous chip on wafer. The understanding of band offset is thus necessary for describing the charge transport phenomenon in these heterojunctions. In this work, x-ray photoemission spectroscopy has been used to determine the band offsets in a heterojunction made of InP quantum dots on Si. The valence and conduction band offset was found to be 0.12 eV and 0.35 eV, respectively, with a type-II band lineup. Deviation from theoretical prediction and previously published reports on quasi similar systems have been found and analyzed on the basis of the effect of strain, surface energy, shift in the electrostatic dipole and charge transfer at the interface. The carrier transport mechanisms along with different device parameters in the heterojunction have been studied for a temperature range of 180–300 K. This heterojunction is found to behave as an efficient infrared photodetector with an ON/OFF ratio of 21 at a reverse bias of 2 V. The corresponding rise and decay time was found to be 132 ms and 147 ms, respectively.
Assessment of the thermoelectric performance of polycrystalline p-type SnSe
Authors: Sassi S. , Candolfi C. , Vaney J.-B. , Ohorodniichuk V. , Masschelein P. , Dauscher A. , Lenoir B.
Published: May 2014

We report the evaluation of the thermoelectric performance of polycrystalline p-type SnSe, a material in which unprecedented values of the thermoelectric figure of merit ZT have been recently discovered in single crystals. Besides anisotropic transport properties, our results confirm that this compound exhibits intrinsically very low thermal conductivity values. The electrical properties show trends typical of lightly doped, intrinsic semiconductors with thermopower values reaching 500 μV K−1 in a broad temperature range. An orthorhombic-to-orthorhombic transition sets in at 823 K, a temperature at which the power factor reaches its maximum value. A maximum ZT of 0.5 was obtained at 823 K, suggesting that proper optimization of the transport properties of SnSe might lead to higher ZT values. These findings indicate that this system represents an interesting experimental platform for the search of highly efficient thermoelectric materials.
Synchronization of oscillators in a Kuramoto-type model with generic coupling
Authors: Vlasov Vladimir , Macau Elbert E. N. , Pikovsky Arkady
Published: May 2014

We study synchronization properties of coupled oscillators on networks that allow description in terms of global mean field coupling. These models generalize the standard Kuramoto–Sakaguchi model, allowing for different contributions of oscillators to the mean field and to different forces from the mean field on oscillators. We present the explicit solutions of self-consistency equations for the amplitude and frequency of the mean field in a parametric form, valid for noise-free and noise-driven oscillators. As an example, we consider spatially spreaded oscillators for which the coupling properties are determined by finite velocity of signal propagation.
Electric field effects on spin accumulation in Nb-doped SrTiO3 using tunable spin injection contacts at room temperature
Authors: Kamerbeek A. M. , de Vries E. K. , Dankert A. , Dash S. P. , van Wees B. J. , Banerjee T.
Published: May 2014

We report on features in charge transport and spin injection in an oxide semiconductor, Nb-doped SrTiO3. This is demonstrated using electrically tunable spin injection contacts which exploit the large electric field at the interface and its interplay with the relative permittivity of the semiconductor. We realize spin accumulation in Nb-doped SrTiO3 which displays a unique dependence of the spin lifetime with bias polarity. These findings suggest a strong influence of the interface electric field on the charge transport as well as on spin accumulation unlike in conventional semiconductors and opens up promising avenues in oxide spintronics.
Thermal annealing effect on ZnO surface acoustic wave-based ultraviolet light sensors on glass substrates
Authors: Wang Wenbo , Gu Hang , He Xingli , Xuan Weipeng , Chen Jinkai , Wang Xiaozhi , Luo J. K.
Published: May 2014

Surface acoustic wave (SAW) based ultraviolet (UV) light sensors have a high sensitivity and have been extensively studied and explored for application. However, all of them were made of piezoelectric (PE) bulk materials or PE thin films on crystalline substrates such as Si and sapphire. This paper reports the fabrication of ZnO thin film SAW UV-light sensors on glass substrates and the effect of post-deposition thermal annealing on the sensing performance. It was found that annealing at temperatures higher than 300 °C can improve the properties of ZnO films and the sensing performance of the UV-sensors remarkably. When the ZnO film annealed at 400 °C was used for sensors, the UV light induced resonant frequency shift increased more than 20 times with the response speed reduced to less than 2.4 s, much better than those made on ZnO films with lower temperature annealing.
Effective hole extraction using MoOx-Al contact in perovskite CH3NH3PbI3 solar cells
Authors: Zhao Yixin , Nardes Alexandre M. , Zhu Kai
Published: May 2014

We report an 11.4%-efficient perovskite CH3NH3PbI3 solar cell using low-cost molybdenum oxide/aluminum (i.e., MoOx/Al) as an alternative top contact to replace noble/precious metals (e.g., Au or Ag) for extracting photogenerated holes. The device performance of perovskite solar cells using a MoOx/Al top contact is comparable to that of cells using the standard Ag top contact. Analysis of impedance spectroscopy measurements suggests that using 10-nm-thick MoOx and Al does not affect charge-recombination properties of perovskite solar cells. Using a thicker (20-nm) MoOx layer leads to a lower cell performance caused mainly by a reduced fill factor. Our results suggest that MoOx/Al is promising as a low-cost and effective hole-extraction contact for perovskite solar cells.
Superconductivity observed in platinum-silicon interface
Authors: Kuo Pai-Chia , Chen Chun-Wei , Lee Ku-Pin , Shiue Jessie
Published: May 2014

We report the discovery of superconductivity with an onset temperature of ∼0.6 K in a platinum-silicon interface. The interface was formed by using a unique focused ion beam sputtering micro-deposition method in which the energies of most sputtered Pt atoms are ∼2.5 eV. Structural and elemental analysis by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy reveal a ∼ 7 nm interface layer with abundant Pt, which is the layer likely responsible for the superconducting transport behavior. Similar transport behavior was also observed in a gold-silicon interface prepared by the same technique, indicating the possible generality of this phenomenon.
High-efficiency micro-energy generation based on free-carrier-modulated ZnO:N piezoelectric thin films
Authors: Lee Eunju , Park Jaedon , Yim Munhyuk , Jeong Sangbeom , Yoon Giwan
Published: May 2014

The free-carrier-modulated ZnO:N thin film-based flexible nanogenerators (NZTF-FNGs) are proposed and experimentally demonstrated. The suggested flexible nanogenerators (FNGs) are fabricated using N-doped ZnO thin films (NZTFs) as their piezoelectric active elements, which are deposited by a radio frequency magnetron sputtering technique with an N2O reactive gas as an in situ dopant source. Considerable numbers of N atoms are uniformly incorporated into NZTFs overall during their growth, which would enable them to significantly compensate the unintentional background free electron carriers both in the bulk and at the surface of ZnO thin films (ZTFs). This N-doping approach is found to remarkably enhance the performance of NZTF-FNGs, which shows output voltages that are almost two orders of magnitude higher than those of the conventionally grown ZnO thin film-based FNGs. This is believed to be a result of both substantial screening effect suppression in the ZTF bulk and more reliable Schottky barrier formation at the ZTF interfaces, which is all mainly caused by the N-compensatory doping process. Furthermore, the NZTF-FNGs fabricated are verified via charging tests to be suitable for micro-energy harvesting devices.
Atomic and electronic structures of lattice mismatched Cu2O/TiO2 interfaces
Authors: Wang Shuzhi , Kavaipatti Balasubramaniam , Kim Sung-Joo , Pan Xiaoqing , Ramesh Ramamoorthy , Ager Joel W. , Wang Lin-Wang
Published: May 2014

Heterojunction interfaces between metal oxides are often highly lattice mismatched. The atomic and electronic structures of such interfaces, however, are not well understood. We have synthesized Cu2O/TiO2 heterojunction thin films with 13% lattice mismatch and studied the interface via experimental methods and large-scale density function theory calculations of supercells containing ∼1300 atoms. We find that an interface of epitaxial quality is formed via a coincidence site lattice of 8 Cu2O unit cells matching 9 TiO2 unit cells. Calculations reveal the existence of a dislocation core of the O sublattices at the interface and a random arrangement of one layer of interfacial Cu atoms. The interfacial electronic structure is found to be mostly determined by the interfacial Cu distribution, rather than by the O dislocation core. The conduction band minimum and valence band maximum states are spatially separated, and there is no strongly localized state near the core.
Ultralow-power all-optical tunable double plasmon-induced transparencies in nonlinear metamaterials
Authors: Zhu Yu , Hu Xiaoyong , Yang Hong , Gong Qihuang
Published: May 2014

An all-optical tunable double plasmon-induced transparency is realized in a photonic metamaterial coated on the surface of a nanocomposite layer made of polycrystalline indium-tin oxide doped with gold nanoparticles. The local-field effect, quantum confinement effect, and hot-electron injection ensure a large optical nonlinearity for the nanocomposite. A shift of 120 nm in the central wavelength of transparency windows is reached under excitation with a weak pump laser with an intensity of 21 kW/cm2. Compared with previous reports, the threshold pump intensity is reduced by five orders of magnitude, while an ultrafast response time of 34.9 ps is maintained.
Fast ion transport induced by saturated infernal mode
Authors: Marchenko V. S.
Published: May 2014

Tokamak discharges with extended weak-shear central core are known to suffer from infernal modes when the core safety factor approaches the mode ratio. These modes can cause an outward convection of the well-passing energetic ions deposited in the core by fusion reactions and/or neutral beam injection. Convection mechanism consists in collisional slowing down of energetic ions trapped in the Doppler-precession resonance with a finite-amplitude infernal mode. Convection velocity can reach a few m/s in modern spherical tori. Possible relation of this transport with the enhanced fast ion losses in the presence of “long lived modes” in the MAST tokamak [I. T. Chapman et al., Nucl. Fusion 50, 045007 (2010)] is discussed.
On the abrupt growth dynamics of nonlinear resistive tearing mode and the viscosity effects
Authors: Ali A. , Li Jiquan , Kishimoto Y.
Published: May 2014

The nonlinear evolution of the resistive tearing mode exhibits an abrupt growth after an X-point collapse once the magnetic island exceeds a certain critical width Δ′wc for large instability parameter Δ′, leading to a current sheet formation [N. F. Loureiro et al., Phys. Rev. Lett. 95, 235003 (2005)]. In this work, we investigate the underlying mechanism of the X-point collapse as well as the current sheet formation including the viscosity effects, based on a secondary instability analysis. The secondary instability is excited due to the quasilinear current modification by the zonal current. In particular, it is identified that the current peaking effect is plausibly responsible for the onset of the X-point collapse and the current sheet formation, leading to the explosive growth of reconnected flux. In the presence of finite viscosity, the Δ′wc scaling with the resistivity gets modified. A transition behavior is revealed at Pr≈1 for the viscosity dependence of Δ′wc and the linear tearing instability. However, the explosive growth seems to be independent of the viscosity in the magnetic Prandtl number Pr<1 regime, while large viscosity plays a strong dissipation role.
A new coaxial high power microwave source based on dual beams
Authors: Li Yangmei , Zhang Xiaoping , Qi Zumin , Dang Fangchao , Qian Baoliang
Published: May 2014

We present a new coaxial high power microwave source based on dual beams, which combines a relativistic backward wave oscillator (RBWO) (noted as the inner sub-source below) and a coaxial transit-time oscillator (TTO) (noted as the outer sub-source). The cathode consists of an inner and an outer annular cathode, which provides the inner and the outer annular electron beam for the sub-sources, respectively. Particle-in-cell (PIC) simulation results demonstrate that power conversion efficiencies of the two sub-sources with an identical frequency of 9.74 GHz are 29% and 25%, respectively. It is furthermore found that phase locking between the inner and the outer sub-sources can be realized, which suggests a feasibility to obtain a higher power output if the two microwave signals are coherently combined.
Simple compound manifests record-high thermoelectric performance
Authors: Levi Barbara Goss
Published: May 2014

Tin selenide, made of Earth-abundant elements, is a surprise contender in the race for a device to convert waste heat to useful energy.
A new kind of self-assembled monolayer
Authors: Miller Johanna L.
Published: May 2014

There’s a need for organic substances that can interface with metal surfaces under harsh laboratory conditions. A class of unusual, reactive molecules just might do the trick.
Turmoil at ITER continues
Authors: Kramer David
Published: May 2014

Council chair says a new director general, a halving of senior management, and improved relations between headquarters and the project’s seven partners are on the way.
Nuclear energy output slows as climate warms
Authors: Kramer David
Published: May 2014

New reports from the Intergovernmental Panel on Climate Change and the US government say the window is closing for actions to avert the worst effects of warming.
The art and science of forensic meteorology
Authors: Austin Elizabeth , Hildebrand Peter
Published: May 2014

When weather factors into a legal dispute, meteorologists use eyewitness accounts, troves of atmospheric data, and simulated reenactments to figure out what went awry.
From the archives: Analyzing atmospheric behavior
Authors: Panofsky Hans
Published: May 2014

Most meteorologists are really physicists in disguise. They use thermodynamics and hydrodynamics to understand snow squalls in Buffalo and typhoons in Japan.
Organic thin films: From monolayers on liquids to multilayers on solids
Authors: Greene J. E.
Published: May 2014

What began as curious ritual in the ancient world led to studies of surface tension, interface properties, phase transitions, and, eventually, sophisticated deposition techniques and a wealth of devices.
What’s in that bottle?
Authors: Espy Michelle , Hunter James , Schultz Larry
Published: May 2014

Nuclear magnetic resonance and x-ray imaging combine to offer a powerful tool for identifying liquids in sealed containers.
The GTPase-activating protein GIT2 protects against colitis by negatively regulating Toll-like receptor signaling
Authors: Wei Juncheng , Wei Chao , Wang Min , Qiu Xiao , Li Yang , Yuan Yanzhi , Jin Chaozhi , Leng Ling , Wang Jian , Yang Xiaoming , He Fuchu
Published: May 2014

Significance

Inflammatory bowel disease is generally thought to develop from an abnormal immune response to the gut luminal microbiota in genetically predisposed individuals. Previous studies on G protein-coupled receptor kinase-interactor 2 (GIT2) have suggested that it regulates thymocyte positive selection, neutrophil-direction sensing, and cell motility during immune responses by regulating the activity of the small GTPases ADP ribosylation factors and Ras-related C3 botulinum toxin substrate 1. Here, we show that GIT2 protects against severe colitis in mice by inhibiting the ubiquitination of TNF receptor associated factor 6 and negatively regulating Toll-like receptor (TLR) signaling. GIT2 is essential for the resolution of TLR signaling, and the deficiency of
Git2
leads to uncontrolled inflammation and severe immune diseases.
Experimental evidence of massive-scale emotional contagion through social networks
Authors: Kramer Adam D. I. , Guillory Jamie E. , Hancock Jeffrey T.
Published: June 2014

Significance

We show, via a massive (
N
= 689,003) experiment on Facebook, that emotional states can be transferred to others via emotional contagion, leading people to experience the same emotions without their awareness. We provide experimental evidence that emotional contagion occurs without direct interaction between people (exposure to a friend expressing an emotion is sufficient), and in the complete absence of nonverbal cues.
11β-HSD1 is the major regulator of the tissue-specific effects of circulating glucocorticoid excess
Authors: Morgan Stuart A. , McCabe Emma L. , Gathercole Laura L. , Hassan-Smith Zaki K. , Larner Dean P. , Bujalska Iwona J. , Stewart Paul M. , Tomlinson Jeremy W. , Lavery Gareth G.
Published: June 2014

Significance

Glucocorticoids are widely prescribed for their anti-inflammatory properties but have Cushingoid side effects that contribute significantly to patient morbidity and mortality. Here we present data to demonstrate that the adverse side-effect profile associated with exogenous active glucocorticoid (GC) administration (including glucose intolerance, hyperinsulinemia, hypertension, hepatic steatosis, increased adiposity, and myopathy) is prevented by global deletion of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in mice. This study not only defines a significant shift in our understanding of the physiological and molecular mechanisms underpinning the adverse side effects associated with GC use but also raises the possibility of targeting 11β-HSD1 as a novel adjunctive therapy in the treatment of Cushing syndrome.
Methylated glycans as conserved targets of animal and fungal innate defense
Authors: Wohlschlager Therese , Butschi Alex , Grassi Paola , Sutov Grigorij , Gauss Robert , Hauck Dirk , Schmieder Stefanie S. , Knobel Martin , Titz Alexander , Dell Anne , Haslam Stuart M. , Hengartner Michael O. , Aebi Markus , Künzler Markus
Published: May 2014

Significance

Defense mechanisms against predators, parasites, and pathogens are a hallmark of all multicellular life forms. A conserved defense mechanism is the production of toxic proteins. Because of the limited number of innate defense effectors in a specific host organism, the target epitopes of such toxins are usually highly conserved or occur in different molecular contexts to cover a large spectrum of antagonists. Because glycan epitopes are part of different surface-displayed glycoconjugates in different organisms, carbohydrate-binding proteins (lectins) are the prevailing type of protein toxins in many multicellular organisms. Here we provide evidence that defense lectins can be specific for secondary glycan modifications, such as O-methylation, thereby broadening the range of target organisms.
Skp1-Cullin-F-box (SCF)-type ubiquitin ligase FBXW7 negatively regulates spermatogonial stem cell self-renewal
Authors: Kanatsu-Shinohara Mito , Onoyama Ichiro , Nakayama Keiichi I. , Shinohara Takashi
Published: May 2014

Significance

Spermatogonial stem cells (SSCs) are at the foundation of spermatogenesis. Previous studies on SSC self-renewal have focused on the positive regulation, but we hypothesized that negative regulation of self-renewal is equally important in understanding SSC self-renewal. We show here that F-box and WD-40 domain protein 7 (FBXW7), a component of the Skp1-Cullin-F-box–type ubiquitin ligase, negatively regulates SSC self-renewal. FBXW7 is expressed only in the undifferentiated spermatogonia compartment, and its overexpression compromises SSC activity whereasFbxw7deficiency enhances SSC colonization and caused accumulation of undifferentiated spermatogonia. We also demonstrate that FBXW7 regulates stability of myelocytomatosis oncogene (MYC), which increased SSC activity upon overexpression. These results suggest that FBXW7 counteracts with positive regulators of self-renewal by degrading MYC and demonstrate the importance of negative regulators of self-renewal in understanding SSC homeostasis.
The Irish potato famine pathogen
Phytophthora infestans
originated in central Mexico rather than the Andes
Authors: Goss Erica M. , Tabima Javier F. , Cooke David E. L. , Restrepo Silvia , Fry William E. , Forbes Gregory A. , Fieland Valerie J. , Cardenas Martha , Grünwald Niklaus J.
Published: June 2014

Significance

The potato late blight pathogen was introduced to Europe in the 1840s and caused the devastating loss of a staple crop, resulting in the Irish potato famine and subsequent diaspora. Research on this disease has engendered much debate, which in recent years has focused on whether the geographic origin of the pathogen is South America or central Mexico. Different lines of evidence support each hypothesis. We sequenced four nuclear genes in representative samples from Mexico and the South American Andes. An Andean origin of
P. infestans
does not receive support from detailed analyses of Andean and Mexican populations. This is one of a few examples of a pathogen with a known origin that is secondary to its current major host.
Impact of Xpert MTB/RIF on Antiretroviral Therapy-Associated Tuberculosis and Mortality: A Pragmatic Randomized Controlled Trial
Authors: Mupfumi L. , Makamure B. , Chirehwa M. , Sagonda T. , Zinyowera S. , Mason P. , Metcalfe J. Z. , Mutetwa R.
Published: June 2014

Introduction.  GeneXpert® MTB/RIF (Xpert) is now widely distributed in high human immunodeficiency virus (HIV)/tuberculosis (TB)-burden countries. Yet, whether the test improves patient-important outcomes within HIV treatment programs in limited resource settings is unknown.

Methods.  To investigate whether use of Xpert for TB screening prior to initiation of antiretroviral treatment (ART) improves patient-important outcomes, in a pragmatic randomized controlled trial we assigned 424 patients to Xpert or fluorescence sputum smear microscopy (FM) at ART initiation. The primary endpoint was a composite of 3-month mortality and ART-associated TB.

Results.  There was no difference in overall TB diagnosis at ART initiation (20% [n = 43] Xpert vs 21% [n = 45] FM; P = .80), with most patients in both groups treated empirically. There was no difference in time to TB treatment initiation {5 days (interquartile range [IQR], 3–13) vs 8 days [IQR, 3–23; P = .26]} or loss to follow-up (32 [15%] vs 38 [18%]; P = 0.38). Although a nonsignificant reduction in mortality occurred in the Xpert group (11 [6%] vs 17 [10%]; 95% CI, −9% to 2%; P = .19), there was no difference in the composite outcome (9% [n = 17] Xpert vs 12% [n = 21] FM; difference −3%; 95% CI, −9% to 4%).

Conclusions.  Among HIV-infected initiating ART, centralized TB screening with Xpert did not reduce the rate of ART-associated TB and mortality, compared with fluorescence microscopy.
Biofeedback for Sport and Performance Enhancement
Authors: Blumenstein Boris , Orbach Iris
Published: June 2014

The technology of biofeedback has great promise for sport psychology and specifically for psychological skills training. Psychological skills learned through biofeedback training can be applied in practice and competition and can lead to improved athletic performance. This chapter includes a brief literature review of biofeedback and biofeedback training and describes the current state of biofeedback research in sport and its implications for athletic performance enhancement. Further, biofeedback training models such as the Wingate Five-Step Approach and the Learning-Modification-Application (LMA) Approach, based on the periodization principle, are presented. Finally, future directions and conclusions for the integration of biofeedback training as part of athletic preparation are presented.
Hagleromyces gen. nov., a yeast genus in the Saccharomycetaceae, and description of Hagleromyces aurorensis sp. nov., isolated from water tanks of bromeliads
Authors: Sousa Francisca M. P. , Morais Paula B. , Lachance Marc-André , Rosa Carlos A.
Published: May 2014

Three strains of a novel yeast species were isolated from water tanks (phytotelmata) of a bromeliad species collected in the state of Tocantins, Brazil. Analysis of sequences for the region spanning the SSU rRNA gene, the internal transcribed spacer, the 5.8S rRNA gene and the D1/D2 domains of the LSU rRNA gene and RNA polymerase II gene showed that these novel yeasts belong to a species that is distinct from all recognized ascomycetous yeast species. Based on the results of gene sequence analyses, a novel species representing a new genus in the Saccharomycetaceae is proposed. The novel species is assigned to the genus Hagleromyces gen. nov. The three isolates of the novel yeast species failed to form sexual spores alone or in mixtures. The name Hagleromyces aurorensis sp. nov. is proposed to accommodate these isolates. The type strain of H. aurorensis sp. nov. is UFMG-CM-Y311T ( = CBS 13264T).
RNA-binding region of Macrobrachium rosenbergii nodavirus capsid protein
Authors: Goh Zee Hong , Mohd Nur Azmina Syakirin , Tan Soon Guan , Bhassu Subha , Tan Wen Siang
Published: May 2014

White tail disease (WTD) kills prawn larvae and causes drastic losses to the freshwater prawn (Macrobrachium rosenbergii) industry. The main causative agent of WTD is Macrobrachium rosenbergii nodavirus (MrNV). The N-terminal end of the MrNV capsid protein is very rich in positively charged amino acids and is postulated to interact with RNA molecules. N-terminal and internal deletion mutagenesis revealed that the RNA-binding region is located at positions 20–29, where 80 % of amino acids are positively charged. Substitution of all these positively charged residues with alanine abolished the RNA binding. Mutants without the RNA-binding region still assembled into virus-like particles, suggesting that this region is not a part of the capsid assembly domain. This paper is, to the best of our knowledge, the first to report the specific RNA-binding region of MrNV capsid protein.
Highly pathogenic avian influenza A H5N1 and pandemic H1N1 virus infections have different phenotypes in Toll-like receptor 3 knockout mice
Authors: Leung Y. H. Connie , Nicholls John M. , Ho Chuk Kwan , Sia Sin Fun , Mok Chris K. P. , Valkenburg Sophie A. , Cheung Peter , Hui Kenrie P. Y. , Chan Renee W. Y. , Guan Y. , Akira S. , Peiris J. S. Malik
Published: May 2014

Toll-like receptors (TLRs) play an important role in innate immunity to virus infections. We investigated the role of TLR3 in the pathogenesis of H5N1 and pandemic H1N1 (pH1N1) influenza virus infections in mice. Wild-type mice and those defective in TLR3 were infected with influenza A/HK/486/97 (H5N1) or A/HK/415742/09 (pH1N1) virus. For comparison, mice defective in the gene for myeloid differential factor 88 (MyD88) were also infected with the viruses, because MyD88 signals through a TLR pathway different from TLR3. Survival and body weight loss were monitored for 14 days, and lung pathology, the lung immune-cell profile, viral load and cytokine responses were studied. H5N1-infected TLR3−/− mice had better survival than H5N1-infected WT mice, evident by significantly faster regain of body weight, lower viral titre in the lung and fewer pathological changes in the lung. However, this improved survival was not seen upon pH1N1 infection of TLR3−/− mice. In contrast, MyD88−/− mice had an increased viral titre and decreased leukocyte infiltration in the lungs after infection with H5N1 virus and poorer survival after pH1N1 infection. In conclusion, TLR3 worsens the pathogenesis of H5N1 infection but not of pH1N1 infection, highlighting the differences in the pathogenesis of these two viruses and the different roles of TLR3 in their pathogenesis.
Loss of transcriptional control over endogenous retroelements during reprogramming to pluripotency
Authors: Friedli Marc , Turelli Priscilla , Kapopoulou Adamandia , Rauwel Benjamin , Castro-Díaz Nathaly , Rowe Helen M. , Ecco Gabriela , Unzu Carmen , Planet Evarist , Lombardo Angelo , Mangeat Bastien , Wildhaber Barbara E. , Naldini Luigi , Trono Didier
Published: May 2014

Endogenous retroelements (EREs) account for about half of the mouse or human genome, and their potential as insertional mutagens and transcriptional perturbators is suppressed by early embryonic epigenetic silencing. Here, we asked how ERE control is maintained during the generation of induced pluripotent stem cells (iPSCs), as this procedure involves profound epigenetic remodeling. We found that all EREs tested were markedly up-regulated during the reprogramming of either mouse embryonic fibroblasts, human CD34+ cells, or human primary hepatocytes. At the iPSC stage, EREs of some classes were repressed, whereas others remained highly expressed, yielding a pattern somewhat reminiscent of that recorded in embryonic stem cells. However, variability persisted between individual iPSC clones in the control of specific ERE integrants. Both during reprogramming and in iPS cells, the up-regulation of specific EREs significantly impacted on the transcription of nearby cellular genes. While transcription triggered by specific ERE integrants at highly precise developmental stages may be an essential step toward obtaining pluripotent cells, the broad and unspecific unleashing of the repetitive genome observed here may contribute to the inefficiency of the reprogramming process and to the phenotypic heterogeneity of iPSCs.
In Planta Recognition of a Double-Stranded RNA Synthesis Protein Complex by a Potexviral RNA Silencing Suppressor
Authors: Okano Yukari , Senshu Hiroko , Hashimoto Masayoshi , Neriya Yutaro , Netsu Osamu , Minato Nami , Yoshida Tetsuya , Maejima Kensaku , Oshima Kenro , Komatsu Ken , Yamaji Yasuyuki , Namba Shigetou
Published: May 2014

RNA silencing plays an important antiviral role in plants and invertebrates. To counteract antiviral RNA silencing, most plant viruses have evolved viral suppressors of RNA silencing (VSRs). TRIPLE GENE BLOCK PROTEIN1 (TGBp1) of potexviruses is a well-characterized VSR, but the detailed mechanism by which it suppresses RNA silencing remains unclear. We demonstrate that transgenic expression of TGBp1 of plantago asiatica mosaic virus (PlAMV) induced developmental abnormalities in Arabidopsis thaliana similar to those observed in mutants of SUPPRESSOR OF GENE SILENCING3 (SGS3) and RNA-DEPENDENT RNA POLYMERASE6 (RDR6) required for the trans-acting small interfering RNA synthesis pathway. PlAMV-TGBp1 inhibits SGS3/RDR6-dependent double-stranded RNA synthesis in the trans-acting small interfering RNA pathway. TGBp1 interacts with SGS3 and RDR6 and coaggregates with SGS3/RDR6 bodies, which are normally dispersed in the cytoplasm. In addition, TGBp1 forms homooligomers, whose formation coincides with TGBp1 aggregation with SGS3/RDR6 bodies. These results reveal the detailed molecular function of TGBp1 as a VSR and shed new light on the SGS3/RDR6-dependent double-stranded RNA synthesis pathway as another general target of VSRs.
Conditional Depletion of the Chlamydomonas Chloroplast ClpP Protease Activates Nuclear Genes Involved in Autophagy and Plastid Protein Quality Control
Authors: Ramundo Silvia , Casero David , Mühlhaus Timo , Hemme Dorothea , Sommer Frederik , Crèvecoeur Michèle , Rahire Michèle , Schroda Michael , Rusch Jannette , Goodenough Ursula , Pellegrini Matteo , Perez-Perez Maria Esther , Crespo José Luis , Schaad Olivier , Civic Natacha , Rochaix Jean David
Published: May 2014

Plastid protein homeostasis is critical during chloroplast biogenesis and responses to changes in environmental conditions. Proteases and molecular chaperones involved in plastid protein quality control are encoded by the nucleus except for the catalytic subunit of ClpP, an evolutionarily conserved serine protease. Unlike its Escherichia coli ortholog, this chloroplast protease is essential for cell viability. To study its function, we used a recently developed system of repressible chloroplast gene expression in the alga Chlamydomonas reinhardtii. Using this repressible system, we have shown that a selective gradual depletion of ClpP leads to alteration of chloroplast morphology, causes formation of vesicles, and induces extensive cytoplasmic vacuolization that is reminiscent of autophagy. Analysis of the transcriptome and proteome during ClpP depletion revealed a set of proteins that are more abundant at the protein level, but not at the RNA level. These proteins may comprise some of the ClpP substrates. Moreover, the specific increase in accumulation, both at the RNA and protein level, of small heat shock proteins, chaperones, proteases, and proteins involved in thylakoid maintenance upon perturbation of plastid protein homeostasis suggests the existence of a chloroplast-to-nucleus signaling pathway involved in organelle quality control. We suggest that this represents a chloroplast unfolded protein response that is conceptually similar to that observed in the endoplasmic reticulum and in mitochondria.
Are leaf functional traits ‘invariant’ with plant size and what is ‘invariance’ anyway?
Authors: Price Charles A. , Wright Ian J. , Ackerly David D. , Niinemets Ülo , Reich Peter B. , Veneklaas Erik J.
Published: May 2014

Studies of size‐related plant traits have established a suite of mathematical functions describing whole plant investment and allocation. In parallel, studies of plant ‘economic spectra’ have measured the scaling and variance composition of traits related to the major dimensions of both structure and function. Here, we explore the intersection of these two broad areas by exploring the notion that many leaf economic traits are invariant with species differences in adult plant size. Invariant traits are those that do not change with plant size and are invoked as a key simplifying assumption of prominent models that purport to explain the scaling of plant size and metabolism. Unfortunately, leaf trait invariance is neither well defined nor understood and has never been critically evaluated.

Using a global plant trait data set, we evaluated whether nine key traits can be considered as effectively invariant as a function of the maximum height of plant species, within and across plant growth forms and within and across broad taxonomic groups. We also examine the influence of habitat, biome and global spatial scales on the size‐relative variance in plant functional traits.

We suggest that while invariance is an intuitive concept, an objective statistical definition is elusive. Expanding on ideas drawn from the study of life‐history invariants, we propose five criteria to identify traits that are effectively invariant, depending on the research question.

We show that all studied ‘leaf economic spectrum’ (LES) traits approach invariance within and between herbaceous and woody plant groups, angiosperms and gymnosperms, and within most biome and habitat types. Individual leaf area, however, shows a modest increase with plant size, and there are significant shifts in the averageLEStrait values at a given plant maximum height, among the plant growth forms and taxonomic groups.

Our results demonstrate that generally,LEStraits show little interspecific variation with maximum plant height, which provides some support for attempts to model plants with ‘average’ leaf properties. Our work also highlights the need for a better understanding of the drivers of leaf size variation within and across individuals, functional groups, clades, biomes and habitats.