bluuebunny/crossref_metadata_2025 huggingface dataset:
Twin Study of Impulsive Buying and its Overlap with Personality
Authors: Bratko Denis , Butkovic Ana , Bosnjak Michael
Published: February 2013

This study explores the origins of individual differences in impulsive buying from a behavioral genetics perspective. It also assesses whether phenotypic associations between personality and impulsive buying tendency can be attributed to overlapping genetic factors. Data were collected via mail for 339 twin pairs. Personality traits according to a five-factor model and impulsive buying were measured. The results indicate that additive genetic, shared environmental, and nonshared environmental influences may be important for individual differences in impulsive buying. Phenotypic correlations with Impulsivity (r = .32), Neuroticism (r = .23), and Extraversion (r = .20) are largely driven by the overlapping genetic influences. Together with age and sex personality traits explain 25% of individual differences in impulsive buying tendency. These results add to our understanding of individual differences in impulsive buying and the nature of its relationship with personality.
If I Cry, Do You Care?
Authors: Lockwood Patricia , Millings Abigail , Hepper Erica , Rowe Angela C.
Published: February 2013

Crying is a powerful solicitation of caregiving, yet little is known about the cognitive processes underpinning caring responses to crying others. This study examined (1) whether crying (compared to sad and happy) faces differentially elicited semantic activation of caregiving, and (2) whether individual differences in cognitive and emotional empathy moderated this activation. Ninety participants completed a lexical decision task in which caregiving, neutral, and nonwords were presented after subliminal exposure (24 ms) to crying, sad, and happy faces. Individuals low in cognitive empathy had slower reaction times to caregiving (vs. neutral) words after exposure to crying faces, but not after sad or happy faces. Results are discussed with respect to the role of empathy in response to crying others.
UPPS Dimensions of Impulsivity
Authors: Gagnon Jean , Daelman Sacha , McDuff Pierre , Kocka Andrea
Published: February 2013

Although cognitive distortions are widely acknowledged in the explanation of impulsivity-related psychopathologies (and more recently in the explanation of specific impulsive behaviors), no study has systematically verified whether they can also explain the cognitive processes underlying these impulsivity traits of personality: urgency, lack of premeditation, lack of perseverance, and sensation seeking (UPPS). Moreover, childhood maltreatment has been frequently associated with both cognitive distortions and impulsive behaviors but never with UPPS traits. A study was conducted on undergraduate students to examine the influence of cognitive distortions and childhood maltreatment on four dimensions of impulsivity from the UPPS Impulsive Behavior Scale. Regression analyses revealed that Premature Processing, a term applied to a group of seven cognitive distortions such as emotional reasoning and confusing needs and wants, as well as childhood maltreatment, was able to predict significantly and independently the Negative Urgency dimension of impulsivity, above and beyond gender and the three other subscales of the UPPS Impulsive Behavior Scale. Coherent with Beck’s cognitive model, these results suggest that the Negative Urgency trait is associated with cognitive distortions that can undermine thought processes in a variety of ways, increasing the likelihood of acting rashly. However, more studies are needed to develop instruments and identify specific forms of cognitive distortions associated with impulsivity traits.
The frequency stabilization method of laser feedback interferometer based on external cavity modulation
Authors: Zeng Zhaoli , Zhang Shulian , Tan Yidong , Wu Yun , Li Yan
Published: February 2013

Laser frequency stabilization is one of the foremost factors that influence the accuracy of measurement using a laser feedback interferometer, especially when the system is in the presence of strong optical feedback. In this paper, we use external cavity modulation to demonstrate a simple and effective method of frequency stabilization for laser feedback interferometer with strong optical feedback. The external cavity modulation is realized by oscillating a feedback mirror driven by a piezoelectric ceramic, the stable feedback optical field is obtained that has strong performance of anti-disturbance. Meanwhile, we stabilize the laser frequency by the thermal frequency-stabilizing. These lead to the realization of stable laser feedback interferometer. The relative uncertainty of the frequency stabilization is less than 1 part in 107.
Scanning droplet cell for high throughput electrochemical and photoelectrochemical measurements
Authors: Gregoire John M. , Xiang Chengxiang , Liu Xiaonao , Marcin Martin , Jin Jian
Published: February 2013

High throughput electrochemical techniques are widely applied in material discovery and optimization. For many applications, the most desirable electrochemical characterization requires a three-electrode cell under potentiostat control. In high throughput screening, a material library is explored by either employing an array of such cells, or rastering a single cell over the library. To attain this latter capability with unprecedented throughput, we have developed a highly integrated, compact scanning droplet cell that is optimized for rapid electrochemical and photoeletrochemical measurements. Using this cell, we screened a quaternary oxide library as (photo)electrocatalysts for the oxygen evolution (water splitting) reaction. High quality electrochemical measurements were carried out and key electrocatalytic properties were identified for each of 5456 samples with a throughput of 4 s per sample.
A modular optically powered floating high voltage generator
Authors: Antonini P. , Borsato E. , Carugno G. , Pegoraro M. , Zotto P.
Published: February 2013

The feasibility of fully floating high voltage (HV) generation was demonstrated producing a prototype of a modular HV system. The primary power source is provided by a high efficiency semiconductor power cell illuminated by a laser system ensuring the floating nature of each module. The HV is then generated by dc-dc conversion and a HV multiplier. The possibility of series connection among modules was verified.
Extraordinary magnetoresistance in two and three dimensions: Geometrical optimization
Authors: Pugsley Lisa M. , Ram-Mohan L. R. , Solin S. A.
Published: February 2013

The extraordinary magnetoresistance (EMR) in metal-semiconductor hybrid structures was first demonstrated using a van der Pauw configuration for a circular semiconductor wafer with a concentric metallic inclusion in it. This effect depends on the orbital motion of carriers in an external magnetic field, and the remarkably high magnetoresistance response observed suggests that the geometry of the metallic inclusion can be optimized to further significantly enhance the EMR. Here, we consider the theory and simulations to achieve this goal by comparing both two-dimensional (2D) and three-dimensional (3D) structures in an external magnetic field to evaluate the EMR in them. New results for 3D structures are presented to show the feasibility of such modeling. Examples of structures that are compatible with present day technological capabilities are given together with their expected responses in terms of EMR. For a 10 μm 2D square structure with a square metallic inclusion, we find an MR up to 107 percent for an applied magnetic field of 1 T. In 3D, for a 10 μm cube with a 5 μm centered metallic inclusion, we obtain an MR of ∼104 percent, which is comparable with the 2D structure of equivalent dimensions. The results presented here for specific geometries are scalable to smaller dimensions down to the onset of ballistic effects in the transport. The present calculations open up the possibility of 3D magnetic field sensors capable of determining the magnitude and also direction of the magnetic field once a full characterization of the sensor response is performed.
A note on weakly discontinuous dynamical transitions
Authors: Franz Silvio , Parisi Giorgio , Ricci-Tersenghi Federico , Rizzo Tommaso , Urbani Pierfrancesco
Published: February 2013

We analyze mode coupling discontinuous transition in the limit of vanishing discontinuity, approaching the so called “A3” point. In these conditions structural relaxation and fluctuations appear to have universal form independent from the details of the system. The analysis of this limiting case suggests new ways for looking at the mode coupling equations in the general case.
Building the isotropic acoustic potential well with strong constraint boundary to improve the stability of ultrasonic transportation
Authors: Jia Kun , Meng Jianxin , Yang Keji , Fan Zongwei , Ju Bing-Feng
Published: February 2013

A quantitative analysis of the acoustic potential well has been proposed for the purpose of realizing stability improvement of ultrasonic transportation. It was found that the boundary Rp and elastic constant kl(l,θ) of the acoustic potential well, acoustic radiation force offset ratio βfl, and elastic constant offset ratio βkl are the critical parameters that define the trapping ability. They were made clear both their intrinsic significance. The stability of the ultrasonic transportation using three transducers is theoretically studied. Long range ultrasonic transportation of silica beads with better stability is realized by optimizing the acoustic parameters to get the well-defined acoustic potential wells. No slip-off the equilibrium position has been observed, which proved its strong ability of trapping and transportation. Because of its simplicity, flexibility, and non-destructivity, the ultrasonic transportation offered a competitive micro-manipulation technology and will provide a promising tool for life science, chemistry and micro-assembly.
Tunneling spectroscopy of chiral states in ultra-thin topological insulators
Authors: Yin Gen , Wickramaratne Darshana , Lake Roger K.
Published: February 2013

The temperature, Fermi-level, and bias dependencies of the inter-surface tunneling current in thin-film topological insulators show unique, identifying signatures of the surface states and their opposite chiralities. The opposite chiralities of the surface states limit the tunneling to the band edges of the gapped Dirac cones. As a result, the tunneling conductance is sensitive to the temperature, the Fermi level, and the surface-surface potential difference. The temperature dependence of the tunneling conductance changes sign as the Fermi level scans through the Dirac point. The tunneling transmission is a minimum when the opposing surface Dirac cones are perfectly aligned in energy. This minimum state of the tunneling channel can result in negative differential resistance (NDR) in the presence of a built-in Rashba-like splitting. The unique thermal response of the tunneling conductance and the existence of NDR suggest a tunneling spectroscopy experiment to demonstrate the opposite chiralities of the opposing surface states.
Theoretical prediction of hydrogen storage on Li-decorated boron nitride atomic chains
Authors: Wang Yusheng , Wang Fei , Xu Bin , Zhang Jing , Sun Qiang , Jia Yu
Published: February 2013

Ab initio first-principles calculations were carried out to investigate Li-decorated boron nitride atomic chains (BNACs) for their applications as hydrogen storage materials. We have shown that the interaction between hydrogen molecules and the pristine chains is too weak to be used at room temperature, and the hydrogen adsorption energies and storage capacities can be obviously increased by decorating Li atoms on the ends of the BNACs. Moreover, the bonding energy between Li and BNAC is much greater than the cohesive energy of bulk Li so that the clustering of Li atoms will not occur once Li is bonded with BNAC. Our studies also revealed that the van der Waals interaction plays an important role in the adsorption of the H2 molecules. Therefore, with two Li atoms binding to each end of the BNACs, the hydrogen storage capacity can reach up to 29.2 wt % theoretically.
Erosion evolution in mono-crystalline silicon surfaces caused by acoustic cavitation bubbles
Authors: Fernandez Rivas David , Betjes Joris , Verhaagen Bram , Bouwhuis Wilco , Bor Ton C. , Lohse Detlef , Gardeniers Han J. G. E.
Published: February 2013

The early stages (<180 min) of cavitation erosion of silicon surfaces were studied for three different crystallographic orientations. We introduce a quantity defined as the ratio of the relative eroded area to the number of pits, αp, to evaluate the evolution of erosion among the different substrates used. Different erosion evolution was observed for (100), (110), and (111) silicon surfaces when exposed to cavitation bubbles generated by an ultrasound signal of 191 kHz. (100) silicon substrates showed the most erosion damage, with an eroded area 2.5 times higher than the other two crystallographic orientation substrates after 180 min sonication. An apparent incubation period of 50 min was measured. The number of erosion pits increased monotonically for (110) and (111), but for (100) no increase was detected after 120 min. The collapse of a spherical bubble was simulated using an axisymmetry boundary integral method. The calculated velocity of the jet from the collapsing bubble was used to estimate the pressure P that is induced by the jet upon impact on the silicon substrate.
High resolution switching magnetization magnetic force microscopy
Authors: Cambel V. , Precner M. , Fedor J. , Šoltýs J. , Tóbik J. , Ščepka T. , Karapetrov G.
Published: February 2013

We introduce switching magnetization magnetic force microscopy based on two-pass scanning atomic force microscopy with reversed tip magnetization between the scans. Within this approach the sum of the scanned data with reversed tip magnetization depicts local van der Waals forces, while their differences map the local magnetic forces. Here we implement this method by fabricating low-momentum magnetic probes that exhibit magnetic single domain state, which can be easily reversed in low external field during the scanning. Measurements on high-density parallel and perpendicular magnetic recording media show enhanced spatial resolution of magnetization.
Anomalous magnetoresistance and magnetocaloric properties of NdRu2Ge2
Authors: Maji Bibekananda , Suresh K. G. , Nigam A. K.
Published: February 2013

It is found that the polycrystalline NdRu2Ge2 undergoes two successive magnetic transitions at Tt = 10 K and TN = 19 K. Evidence of metamagnetic transition is detected in the magnetization isotherm data in the antiferromagnetic regime. Temperature dependence of magnetoresistance (MR) shows that the relative magnitudes of MR at TN and Tt change considerably as the field is increased from 10 kOe to 30 kOe. Moreover, the MR is found to be positive below 9 K for 30 kOe field although the material is ferromagnetic at these temperatures. The highest value of negative MR near TN is about 42% in a field of 30 kOe, while the positive MR is about 35% at 3 K in a field of 50 kOe. Like MR, the magnetocaloric effect (MCE) at TN and Tt also shows anomalous behavior. The relative magnitudes of MCE at these temperatures are found to change with increase in field. It appears that the high field (>10 kOe) magnetic state below TN is complex, giving rise to some antiferromagnetic-like fluctuations, affecting the MR and MCE behavior.
Structural and electrical characteristics of high-k/metal gate metal oxide semiconductor capacitors fabricated on flexible, semi-transparent silicon (100) fabric
Authors: Rojas Jhonathan P. , Torres Sevilla Galo , Hussain Muhammad M.
Published: February 2013

In pursuit of flexible computers with high performance devices, we demonstrate a generic process to fabricate 10 000 metal-oxide-semiconductor capacitors (MOSCAPs) with semiconductor industry's most advanced high-k/metal gate stacks on widely used, inexpensive bulk silicon (100) wafers and then using a combination of iso-/anisotropic etching to release the top portion of the silicon with the already fabricated devices as a mechanically flexible (bending curvature of 133 m−1), optically semi-transparent silicon fabric (1.5 cm × 3 cm × 25 μm). The electrical characteristics show 3.7 nm effective oxide thickness, −0.2 V flat band voltage, and no hysteresis from the fabricated MOSCAPs.
The multiferroic perovskite YFeO3
Authors: Shang Mingyu , Zhang Chenyang , Zhang Tingsong , Yuan Lin , Ge Lei , Yuan Hongming , Feng Shouhua
Published: February 2013

The orthoferrite YFeO3 with orthorhombic perovskite structure (Pnma) has been synthesized by mild hydrothermal method. The temperature-dependent magnetization and hysteresis loops indicate that, due to the superexchange and Dzyaloshinskii-Moriya interactions in the crystals, the Fe spins order antiferromagnetically at the Néel temperature 655 K with a weak ferromagnetic moment. The observation of saturation polarization loops at room temperature and 77 K provide evidence for the ferroelectric character of the polycrystalline samples. Its Curie temperature has been obtained from the temperature dependence of the relative permittivities and thermal analysis. As a result, the structure exhibits simultaneously weak ferromagnetic and ferroelectric behavior.
Optical manipulation of electron spin coherence in colloidal CdS quantum dots
Authors: Feng D. H. , Shan L. F. , Jia T. Q. , Pan X. Q. , Tong H. F. , Deng L. , Sun Z. R. , Xu Z. Z.
Published: February 2013

We report experimental studies of optical manipulation of electron spin coherence by linearly or circularly polarized short laser pulses at room temperature, in an ensemble of colloidal CdS quantum dots. In addition to a conventional pump-probe configuration, a linearly polarized prepump pulse before the pump could significantly enhance the amplitude of pump-induced electron spin coherence, owing to the fact that prepump pulses produce more resident electrons. And a linearly or circularly polarized control pulse after the pump will efficiently suppress the spin coherence, because of the re-excitation of spin-polarized electrons to trion states by the absorption of control photons.
Oxygen stoichiometry and magnetic properties of LuFe2O4+δ
Authors: Wang Fan , Kim Jungho , Gu G. D. , Lee Yongjae , Bae Saebyok , Kim Young-June
Published: February 2013

We report a comprehensive investigation of the magnetic properties of LuFe2O4 (LFO) samples with different oxygen stoichiometries. Samples with excess oxygen exhibit spin glass behavior without long-range magnetic order, while three-dimensional ferrimagnetic order exists in a stoichiometric sample. Dissimilar experimental observations reported in several papers can be understood consistently when oxygen stoichiometry is taken into account. The stoichiometric sample orders magnetically below TN = 243 K, and a monoclinic lattice distortion sets in below TL = 175 K. This structural change is sensitive to the applied magnetic field, indicating strong spin-lattice coupling in this material. Unusual low-field thermal magnetization behavior was observed near TL, and its origin is discussed.
Stable thrust on a finite-sized magnet above a Meissner superconducting torus
Authors: Perez-Diaz Jose-Luis , Diez-Jimenez Efren , Valiente-Blanco Ignacio , Herrero-de-Vicente Javier
Published: February 2013

Forces and torques exerted by a superconducting torus on a permanent magnet have been mapped. It is demonstrated that stable orbits exist. Moreover, provided that the magnet remains in any of these orbits, the first critical field in the superconductor is never overpassed and the superconductor remains in the Meissner state. The consequent absence of hysteresis makes these kinds of device perfect candidates for non-frictional bearings or gyroscopes.
Communication: Van der Waals corrections for an improved structural description of telluride based materials
Authors: Micoulaut M.
Published: February 2013

Density functional theory (DFT), using the generalized gradient approximation, fails to reproduce the structure of liquid tellurides, which manifests by an overestimation of the interatomic bond distances. Here, we take into account dispersion forces in a semi-empirical way and apply such DFT simulations to liquid Ge15Te85. Substantial improvement of the simulated structure factor and pair distribution function is found, together with a change in the diffusion constant. A detailed analysis shows that such dispersion forces strongly affect the local geometry and first coordination shell of the atoms, whereas angular distributions remain unchanged.
Influence of structural anisotropy to anisotropic electron mobility in a-plane InN
Authors: Ahn H. , Chia J.-W. , Lee H.-M. , Gwo S.
Published: February 2013

This study reports on the anisotropic electron transport properties and a correlation between the electron mobility (μ) and the stacking faults (SFs) in the a-plane InN film. Electron mobilities measured by terahertz time-domain spectroscopy and Hall effect measurement along the in-plane [1¯100] (c⊥) orientation were much higher than those of the in-plane [0001] (c∥) orientation. This result shows a sharp contrast to higher defect density for the c⊥ orientation as measured by x-ray diffraction. The electrons transporting through the planar SFs aligned along the c⊥ direction are expected to experience more scattering by defects, resulting in lower μ for the c∥ orientation.
Material selection considerations for coaxial, ferrimagnetic-based nonlinear transmission lines
Authors: Bragg J.-W. B. , Dickens J. C. , Neuber A. A.
Published: February 2013

The growing need for solid-state high power microwave sources has renewed interest in nonlinear transmission lines (NLTLs). This article focuses specifically on ferrimagnetic-based NLTLs in a coaxial geometry. Achieved peak powers exceed 30 MW at 30 kV incident voltage with rf power reaching 4.8 MW peak and pulse lengths ranging from 1–5 ns. The presented NLTL operates in S-band with the capability to tune the center frequency of oscillation over the entire 2–4 GHz band and bandwidths of approximately 30%, placing the NLTL into the ultra-wideband–mesoband category of microwave sources. Several nonlinear materials were tested and the relationship between NLTL performance and material parameters is discussed. In particular, the importance of the material's ferromagnetic resonance linewidth and its relationship to microwave generation is highlighted. For a specific nonlinear material, it is shown that an optimum relation between incident pulse magnitude and static bias magnitude exists. By varying the nonlinear material's bias magnetic field, active delay control was demonstrated.
Frequency-modulated light scattering in colloidal suspensions
Authors: Mei Liang , Svanberg Sune , Somesfalean Gabriel
Published: February 2013

Frequency-modulated light field fluctuations due to moving particles in colloidal suspensions are examined using heterodyne interferometry. The power spectrum is the combined result of a time-of-flight-related frequency distribution due to light scattering and frequency shifts due to the Doppler effect. An approximation model is developed based on diffusion theory and verified experimentally. The potential for application towards comprehensive diagnosis of both particle dynamics and optical properties of the examined media is discussed.
Mobility enhancement of top contact pentacene based organic thin film transistor with bi-layer GeO/Au electrodes
Authors: Waqas Alam Mir , Wang Zhaokui , Naka Shigeki , Okada Hiroyuki
Published: February 2013

The enhancement of the charge injection and field effect mobility by inserting a thin (5 nm) germanium oxide (GeO) interlayer between the Au electrode and pentacene layer in a top contact pentacene based organic thin-film transistor (OTFTs) was reported. In comparison with the pentacene-based OTFT with only-Au electrode, the device performance has been considerably improved, which exhibits the highest field effect mobility of 0.96 cm2/Vs. The improvement was attributed to significant reduction of barrier height at Au/pentacene interfaces and smoothed surface of pentacene layer after inserting a thin GeO layer.
Highly tunable-emittance radiator based on semiconductor-metal transition of VO2 thin films
Authors: Hendaoui Ali , Émond Nicolas , Chaker Mohamed , Haddad Émile
Published: February 2013

This paper describes a VO2-based smart structure with an emittance that increases with the temperature. A large tunability of the spectral emittance, which can be as high as 0.90, was achieved. The transition of the total emittance with the temperature was fully reversible according to a hysteresis cycle, with a transition temperature of 66.5 °C. The total emittance of the device was found to be 0.22 and 0.71 at 25 °C and 100 °C, respectively. This emittance performance and the structure simplicity are promising for the next generation of energy-efficient cost-effective passive thermal control systems of spacecrafts.
Flood hazard modelling and risk assessment in the Nadi River Basin, Fiji, using GIS and MCDA
Authors: Paquette Jessy , Lowry John
Published: February 2013

This paper presents a simple and affordable approach to flood hazard assessment in a region where primary data are scarce. Using a multicriteria decision analysis (MCDA) approach coupled with GIS layers for elevation, catchments, land-use, slope, distance from channel, and soil types, we model the spatial extent of flood hazard in the Nadi River basin in western Fiji. Based on the flood hazard model results we assess risk to flood hazards in the greater Nadi area. This is carried out using 2007 census data and building location data obtained from aerial photography. The flood model reveals that the highest hazard areas in Nadi are the Narewa, Sikituru and Yavusania villages followed by the Nadi central business district (Nadi CBD). Closer examination of the data suggests that the Nadi River is not the only flood vector in the area. Several poorly designed storm drains also present a hazard since they get clogged by rubbish and cannot properly evacuate runoff thus creating water build-up. We conclude that the MCDA approach provides a simple and effective means to model flood hazard using basic GIS data. This type of model can help decision makers focus their flood risk awareness efforts, and gives important insights to disaster management authorities.
Species diversity, composition and the regeneration potential of native plants at the Wainiveiota Mahogany Plantation, Viti Levu, Fiji Islands
Authors: Tuiwawa Senilolia H. , Keppel Gunnar
Published: February 2013

Mahogany (Swietenia macrophylla King) plantations cover a considerable area on the south-eastern parts of Viti Levu, Fiji. The understorey of these plantations often comprise a diverse, but undocumented, assemblage of native plant species. This study investigates the diversity, composition and regeneration potential of native plant species in the Wainiveiota mahogany plantation 40?50 years after establishment. Ten 10 m x 10 m plots were alternately placed at 10 m intervals perpendicular to a 200 m line transect. A total of 491 individual plants with dbh ≥ 1 cm, comprising 69 species, 51 genera and 34 families, were sampled. In addition to the exotic mahogany, there were 68 native (39 endemic, 24 indigenous and 5 identified to genus only) species recorded. Girronniera celtidifolia Gaud., Dillenia biflora (A.Gray) Martelli ex Dur. & Jacks and Barringtonia edulis Seem. had the highest recruitment and Endospermum macrophyllum (Muell.Arg.) Pax & Hoffm. was the dominant native species. Syzygium Gaertn. (Myrtaceae) was the most diverse genus and Myrtaceae the most diverse
family. With 98% of the sapling recruitment consisting of native species, there is potential for re-establishment of a lowland rainforest dominated by native species over time.
Antidiabetogenic MHC class II promotes the differentiation of MHC-promiscuous autoreactive T cells into FOXP3+regulatory T cells
Authors: Tsai Sue , Serra Pau , Clemente-Casares Xavier , Yamanouchi Jun , Thiessen Shari , Slattery Robyn M. , Elliott John F. , Santamaria Pere
Published: February 2013

Polymorphisms in MHC class II molecules, in particular around β-chain position-57 (β57), afford susceptibility/resistance to multiple autoimmune diseases, including type 1 diabetes, through obscure mechanisms. Here, we show that the antidiabetogenic MHC class II molecule I-Abaffords diabetes resistance by promoting the differentiation of MHC-promiscuous autoreactive CD4+T cells into disease-suppressing natural regulatory T cells, in a β56–67-regulated manner. We compared the tolerogenic and antidiabetogenic properties of CD11c promoter-driven transgenes encoding I-Abor a form of I-Abcarrying residues 56–67 of I-Aβg7(I-Ab-g7) in wild-type nonobese diabetic (NOD) mice, as well as NOD mice coexpressing a diabetogenic and I-Ag7–restricted, but MHC-promiscuous T-cell receptor (4.1). Both I-A transgenes protected NOD and 4.1-NOD mice from diabetes. However, whereas I-Abinduced 4.1-CD4+thymocyte deletion and 4.1-CD4+Foxp3+regulatory T-cell development, I-Ab-g7promoted 4.1-CD4+Foxp3+Treg development without inducing clonal deletion. Furthermore, non–T-cell receptor transgenic NOD.CD11cP-I-Aband NOD.CD11cP-IAb-g7mice both exported regulatory T cells with superior antidiabetogenic properties than wild-type NOD mice. We propose that I-Ab, and possibly other protective MHC class II molecules, afford disease resistance by engaging a naturally occurring constellation of MHC-promiscuous autoreactive T-cell clonotypes, promoting their deviation into autoregulatory T cells.
Reversal of age-related neural timing delays with training
Authors: Anderson Samira , White-Schwoch Travis , Parbery-Clark Alexandra , Kraus Nina
Published: February 2013

Neural slowing is commonly noted in older adults, with consequences for sensory, motor, and cognitive domains. One of the deleterious effects of neural slowing is impairment of temporal resolution; older adults, therefore, have reduced ability to process the rapid events that characterize speech, especially in noisy environments. Although hearing aids provide increased audibility, they cannot compensate for deficits in auditory temporal processing. Auditory training may provide a strategy to address these deficits. To that end, we evaluated the effects of auditory-based cognitive training on the temporal precision of subcortical processing of speech in noise. After training, older adults exhibited faster neural timing and experienced gains in memory, speed of processing, and speech-in-noise perception, whereas a matched control group showed no changes. Training was also associated with decreased variability of brainstem response peaks, suggesting a decrease in temporal jitter in response to a speech signal. These results demonstrate that auditory-based cognitive training can partially restore age-related deficits in temporal processing in the brain; this plasticity in turn promotes better cognitive and perceptual skills.
Surface exposure to sunlight stimulates CO2release from permafrost soil carbon in the Arctic
Authors: Cory Rose M. , Crump Byron C. , Dobkowski Jason A. , Kling George W.
Published: February 2013

Recent climate change has increased arctic soil temperatures and thawed large areas of permafrost, allowing for microbial respiration of previously frozen C. Furthermore, soil destabilization from melting ice has caused an increase in thermokarst failures that expose buried C and release dissolved organic C (DOC) to surface waters. Once exposed, the fate of this C is unknown but will depend on its reactivity to sunlight and microbial attack, and the light available at the surface. In this study we manipulated water released from areas of thermokarst activity to show that newly exposed DOC is >40% more susceptible to microbial conversion to CO2when exposed to UV light than when kept dark. When integrated over the water column of receiving rivers, this susceptibility translates to the light-stimulated bacterial activity being on average from 11% to 40% of the total areal activity in turbid versus DOC-colored rivers, respectively. The range of DOC lability to microbes seems to depend on prior light exposure, implying that sunlight may act as an amplification factor in the conversion of frozen C stores to C gases in the atmosphere.
Captured retroviral envelope syncytin gene associated with the unique placental structure of higher ruminants
Authors: Cornelis Guillaume , Heidmann Odile , Degrelle Séverine A. , Vernochet Cécile , Lavialle Christian , Letzelter Claire , Bernard-Stoecklin Sibylle , Hassanin Alexandre , Mulot Baptiste , Guillomot Michel , Hue Isabelle , Heidmann Thierry , Dupressoir Anne
Published: February 2013

Syncytins are envelope genes of retroviral origin that have been co-opted for a role in placentation and likely contribute to the remarkable diversity of placental structures. Independent capture events have been identified in primates, rodents, lagomorphs, and carnivores, where they are involved in the formation of a syncytium layer at the fetomaternal interface via trophoblast cell–cell fusion. We searched for similar genes within the suborder Ruminantia where the placenta lacks an extended syncytium layer but displays a heterologous cell-fusion process unique among eutherian mammals. An
in silico
search for intact envelope genes within the
Bos taurus
genome identified 18 candidates belonging to five endogenous retrovirus families, with one gene displaying both placenta-specific expression, as assessed by quantitative RT-PCR analyses of a large panel of tissues, and conservation in the
Ovis aries
genome. Both the bovine and ovine orthologs displayed fusogenic activity by conferring infectivity on retroviral pseudotypes and triggering cell–cell fusion. In situ hybridization of placenta sections revealed specific expression in the trophoblast binucleate cells, consistent with a role in the formation—by heterologous cell fusion with uterine cells—of the trinucleate cells of the cow and the syncytial plaques of the ewe. Finally, we show that this gene, which we named “
Syncytin-Rum1
,” is conserved among 16 representatives of higher ruminants, with evidence for purifying selection and conservation of its fusogenic properties, over 30 millions years of evolution. These data argue for syncytins being a major driving force in the emergence and diversity of the placenta.
Olfactory receptor responding to gut microbiota-derived signals plays a role in renin secretion and blood pressure regulation
Authors: Pluznick Jennifer L. , Protzko Ryan J. , Gevorgyan Haykanush , Peterlin Zita , Sipos Arnold , Han Jinah , Brunet Isabelle , Wan La-Xiang , Rey Federico , Wang Tong , Firestein Stuart J. , Yanagisawa Masashi , Gordon Jeffrey I. , Eichmann Anne , Peti-Peterdi Janos , Caplan Michael J.
Published: February 2013

Olfactory receptors are G protein-coupled receptors that mediate olfactory chemosensation and serve as chemosensors in other tissues. We find that Olfr78, an olfactory receptor expressed in the kidney, responds to short chain fatty acids (SCFAs). Olfr78 is expressed in the renal juxtaglomerular apparatus, where it mediates renin secretion in response to SCFAs. In addition, both Olfr78 and G protein-coupled receptor 41 (Gpr41), another SCFA receptor, are expressed in smooth muscle cells of small resistance vessels. Propionate, a SCFA shown to induce vasodilation ex vivo, produces an acute hypotensive response in wild-type mice. This effect is differentially modulated by disruption of Olfr78 and Gpr41 expression. SCFAs are end products of fermentation by the gut microbiota and are absorbed into the circulation. Antibiotic treatment reduces the biomass of the gut microbiota and elevates blood pressure in
Olfr78
knockout mice. We conclude that SCFAs produced by the gut microbiota modulate blood pressure via Olfr78 and Gpr41.
Trio engagement via plasma membrane phospholipids and the myristoyl moiety governs HIV-1 matrix binding to bilayers
Authors: Vlach Jiri , Saad Jamil S.
Published: February 2013

Localization of the HIV type-1 (HIV-1) Gag protein on the plasma membrane (PM) for virus assembly is mediated by specific interactions between the N-terminal myristoylated matrix (MA) domain and phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P
2
]. The PM bilayer is highly asymmetric, and this asymmetry is considered crucial in cell function. In a typical mammalian cell, the inner leaflet of the PM is enriched in phosphatidylserine (PS) and phosphatidylethanolamine (PE) and contains minor populations of phosphatidylcholine (PC) and PI(4,5)P
2
. There is strong evidence that efficient binding of HIV-1 Gag to membranes is sensitive not only to lipid composition and net negative charge, but also to the hydrophobic character of the acyl chains. Here, we show that PS, PE, and PC interact directly with MA via a region that is distinct from the PI(4,5)P
2
binding site. Our NMR data also show that the myristoyl group is readily exposed when MA is bound to micelles or bicelles. Strikingly, our structural data reveal a unique binding mode by which the 2′-acyl chain of PS, PE, and PC lipids is buried in a hydrophobic pocket whereas the 1′-acyl chain is exposed. Sphingomyelin, a major lipid localized exclusively on the outer layer of the PM, does not bind to MA. Our findings led us to propose a trio engagement model by which HIV-1 Gag is anchored to the PM via the 1′-acyl chains of PI(4,5)P
2
and PS/PE/PC and the myristoyl group, which collectively bracket a basic patch projecting toward the polar leaflet of the membrane.
Neuronal long-range temporal correlations and avalanche dynamics are correlated with behavioral scaling laws
Authors: Palva J. Matias , Zhigalov Alexander , Hirvonen Jonni , Korhonen Onerva , Linkenkaer-Hansen Klaus , Palva Satu
Published: February 2013

Scale-free fluctuations are ubiquitous in behavioral performance and neuronal activity. In time scales from seconds to hundreds of seconds, psychophysical dynamics and the amplitude fluctuations of neuronal oscillations are governed by power-law-form long-range temporal correlations (LRTCs). In millisecond time scales, neuronal activity comprises cascade-like neuronal avalanches that exhibit power-law size and lifetime distributions. However, it remains unknown whether these neuronal scaling laws are correlated with those characterizing behavioral performance or whether neuronal LRTCs and avalanches are related. Here, we show that the neuronal scaling laws are strongly correlated both with each other and with behavioral scaling laws. We used source reconstructed magneto- and electroencephalographic recordings to characterize the dynamics of ongoing cortical activity. We found robust power-law scaling in neuronal LRTCs and avalanches in resting-state data and during the performance of audiovisual threshold stimulus detection tasks. The LRTC scaling exponents of the behavioral performance fluctuations were correlated with those of concurrent neuronal avalanches and LRTCs in anatomically identified brain systems. The behavioral exponents also were correlated with neuronal scaling laws derived from a resting-state condition and with a similar anatomical topography. Finally, despite the difference in time scales, the scaling exponents of neuronal LRTCs and avalanches were strongly correlated during both rest and task performance. Thus, long and short time-scale neuronal dynamics are related and functionally significant at the behavioral level. These data suggest that the temporal structures of human cognitive fluctuations and behavioral variability stem from the scaling laws of individual and intrinsic brain dynamics.
Vaccinia virus-mediated melanin production allows MR and optoacoustic deep tissue imaging and laser-induced thermotherapy of cancer
Authors: Stritzker Jochen , Kirscher Lorenz , Scadeng Miriam , Deliolanis Nikolaos C. , Morscher Stefan , Symvoulidis Panagiotis , Schaefer Karin , Zhang Qian , Buckel Lisa , Hess Michael , Donat Ulrike , Bradley William G. , Ntziachristos Vasilis , Szalay Aladar A.
Published: February 2013

We reported earlier the delivery of antiangiogenic single chain antibodies by using oncolytic vaccinia virus strains to enhance their therapeutic efficacy. Here, we provide evidence that gene-evoked production of melanin can be used as a therapeutic and diagnostic mediator, as exemplified by insertion of only one or two genes into the genome of an oncolytic vaccinia virus strain. We found that produced melanin is an excellent reporter for optical imaging without addition of substrate. Melanin production also facilitated deep tissue optoacoustic imaging as well as MRI. In addition, melanin was shown to be a suitable target for laser-induced thermotherapy and enhanced oncolytic viral therapy. In conclusion, melanin as a mediator for thermotherapy and reporter for different imaging modalities may soon become a versatile alternative to replace fluorescent proteins also in other biological systems. After ongoing extensive preclinical studies, melanin overproducing oncolytic virus strains might be used in clinical trials in patients with cancer.
Spatially clustered neuronal assemblies comprise the microstructure of synchrony in chronically epileptic networks
Authors: Feldt Muldoon Sarah , Soltesz Ivan , Cossart Rosa
Published: February 2013

Epilepsy is characterized by recurrent synchronizations of neuronal activity, which are both a cardinal clinical symptom and a debilitating phenomenon. Although the temporal dynamics of epileptiform synchronizations are well described at the macroscopic level using electrophysiological approaches, less is known about how spatially distributed microcircuits contribute to these events. It is important to understand the relationship between micro and macro network activity because the various mechanisms proposed to underlie the generation of such pathological dynamics are united by the assumption that epileptic activity is recurrent and hypersynchronous across multiple scales. However, quantitative analyses of epileptiform spatial dynamics with cellular resolution have been hampered by the difficulty of simultaneously recording from multiple neurons in lesioned, adult brain tissue. We have overcome this experimental limitation and used two-photon calcium imaging in combination with a functional clustering algorithm to uncover the functional network structure of the chronically epileptic dentate gyrus in the mouse pilocarpine model of temporal lobe epilepsy. We show that, under hyperexcitable conditions, slices from the epileptic dentate gyrus display recurrent interictal-like network events with a high diversity in the activity patterns of individual neurons. Analysis reveals that multiple functional clusters of spatially localized neurons comprise epileptic networks, and that network events are composed of the coactivation of variable subsets of these clusters, which show little repetition between events. Thus, these interictal-like recurrent macroscopic events are not necessarily recurrent when viewed at the microcircuit scale and instead display a patterned but variable structure.
Incommensurate antiferromagnetism in a pure spin system via cooperative organization of local and itinerant moments
Authors: Feng Yejun , Wang Jiyang , Silevitch D. M. , Mihaila B. , Kim J. W. , Yan J.-Q. , Schulze R. K. , Woo Nayoon , Palmer A. , Ren Y. , van Wezel Jasper , Littlewood P. B. , Rosenbaum T. F.
Published: February 2013

Materials with strong correlations are prone to spin and charge instabilities, driven by Coulomb, magnetic, and lattice interactions. In materials that have significant localized and itinerant spins, it is not obvious which will induce order. We combine electrical transport, X-ray magnetic diffraction, and photoemission studies with band structure calculations to characterize successive antiferromagnetic transitions in GdSi. GdSi has both sizable local moments and a partially nested Fermi surface, without confounding contributions from orbital effects. We identify a route to incommensurate order where neither type of moment dominates, but is rooted in cooperative feedback between them. The nested Fermi surface of the itinerant electrons induces strong interactions between local moments at the nesting vector, whereas the ordered local moments in turn provide the necessary coupling for a spin-density wave to form among the itinerant electrons. This mechanism echoes the cooperative interactions between electrons and ions in charge-density–wave materials, and should be germane across a spectrum of transition-metal and rare-earth intermetallic compounds.
Integrating indigenous livelihood and lifestyle objectives in managing a natural resource
Authors: Plagányi Éva Elizabeth , van Putten Ingrid , Hutton Trevor , Deng Roy A. , Dennis Darren , Pascoe Sean , Skewes Tim , Campbell Robert A.
Published: February 2013

Evaluating the success of natural resource management approaches requires methods to measure performance against biological, economic, social, and governance objectives. In fisheries, most research has focused on industrial sectors, with the contributions to global resource use by small-scale and indigenous hunters and fishers undervalued. Globally, the small-scale fisheries sector alone employs some 38 million people who share common challenges in balancing livelihood and lifestyle choices. We used as a case study a fishery with both traditional indigenous and commercial sectors to develop a framework to bridge the gap between quantitative bio-economic models and more qualitative social analyses. For many indigenous communities, communalism rather than capitalism underlies fishers’ perspectives and aspirations, and we find there are complicated and often unanticipated trade-offs between economic and social objectives. Our results highlight that market-based management options might score highly in a capitalistic society, but have negative repercussions on community coherence and equity in societies with a strong communal ethic. There are complex trade-offs between economic indicators, such as profit, and social indicators, such as lifestyle preferences. Our approach makes explicit the “triple bottom line” sustainability objectives involving trade-offs between economic, social, and biological performance, and is thus directly applicable to most natural resource management decision-making situations.
Geometry of Miura-folded metamaterials
Authors: Schenk Mark , Guest Simon D.
Published: February 2013

This paper describes two folded metamaterials based on the Miura-ori fold pattern. The structural mechanics of these metamaterials are dominated by the kinematics of the folding, which only depends on the geometry and therefore is scale-independent. First, a folded shell structure is introduced, where the fold pattern provides a negative Poisson’s ratio for in-plane deformations and a positive Poisson’s ratio for out-of-plane bending. Second, a cellular metamaterial is described based on a stacking of individual folded layers, where the folding kinematics are compatible between layers. Additional freedom in the design of the metamaterial can be achieved by varying the fold pattern within each layer.