bluuebunny/crossref_metadata_2025 huggingface dataset:
An optically modulated zero-field atomic magnetometer with suppressed spin-exchange broadening
Authors: Jiménez-Martínez R. , Knappe S. , Kitching J.
Published: April 2014

We demonstrate an optically pumped 87Rb magnetometer in a microfabricated vapor cell based on a zero-field dispersive resonance generated by optical modulation of the 87Rb ground state energy levels. The magnetometer is operated in the spin-exchange relaxation-free regime where high magnetic field sensitivities can be achieved. This device can be useful in applications requiring array-based magnetometers where radio frequency magnetic fields can induce cross-talk among adjacent sensors or affect the source of the magnetic field being measured.
Mixtures composed of liquid crystals and carbon nanotubes
Authors: Popa-Nita V.
Published: April 2014

The phenomenological model to describe the liquid crystal–carbon nanotubes mixture presented in a previous paper [P. van der Schoot, V. Popa-Nita, and S. Kralj, J. Phys. Chem. B 112, 4512 (2008)] has been extended to include the isotropic carbon nanotubes–nematic thermotropic liquid crystal interaction. It is assumed that the carbon nanotubes in the isotropic phase act as an external random field on liquid crystal component. The influence of the randomly orientational disorder on the phase diagram of the mixture and orientational order parameters profiles of both components is theoretically analyzed for different values of temperature, volume fraction of carbon nanotubes, nematic carbon nanotubes–nematic liquid crystal coupling strength and the random field strength.
Preferential flow penetration in a network of identical channels
Authors: Al-Housseiny Talal T. , Hernandez Jesus , Stone Howard A.
Published: April 2014

It is intuitive to expect a fluid to evenly penetrate two identical daughter channels supplied by the same source when these channels experience the same back pressure. In this work, we show that this might not be the case. We consider the displacement of one fluid by another in a network composed of two identical channels that linearly vary in radius. When surface tension is important, this simple shape variation can cause the fluid to primarily enter only one of the two branches, i.e., we find that the even or uniform fluid penetration into the network is not always stable. Displacement flows in small channels exhibit an interplay between viscous forces and capillary forces. We analyze the dynamics of our system, which features a hydrodynamic instability that is governed by the viscosities of the fluids, their wetting properties, the flow penetration speed, and the gradient characterizing the channel shape.
Influence of spin-orbit effects on structures and dielectric properties of neutral lead clusters
Authors: Götz D. A. , Shayeghi A. , Johnston R. L. , Schwerdtfeger P. , Schäfer R.
Published: April 2014

Combining molecular beam electric deflection experiments and global optimization techniques has proven to be a powerful tool for resolving equilibrium structures of neutral metal and semiconductor clusters. Herein, we present electric molecular beam deflection experiments on PbN (N = 7–18) clusters. Promising structures are generated using the unbiased Birmingham Cluster Genetic Algorithm approach based on density functional theory. The structures are further relaxed within the framework of two-component density functional theory taking scalar relativistic and spin orbit effects into account. Quantum chemical results are used to model electric molecular beam deflection profiles based on molecular dynamics calculations. Comparison of measured and simulated beam profiles allows the assignment of equilibrium structures for the most cluster sizes in the examined range for the first time. Neutral lead clusters adopt mainly spherical geometries and resemble the structures of lead cluster cations apart from Pb10. Their growth pattern deviates strongly from the one observed for tin and germanium clusters.
Explosion-driven Rayleigh-Taylor instability in gas-particle mixtures
Authors: Balakrishnan Kaushik
Published: April 2014

The structure and growth of an explosion-driven Rayleigh-Taylor instability in gas-particle mixtures is investigated using two-dimensional numerical simulations. Particle concentration and diameter are varied and the growth of the ensuing mixing layer and its dependence on these parameters is investigated. The hydrodynamic structures are subdued and lose their coherence with increase in solid particle concentrations. When the solid particle concentration is fixed but particle diameter varied, a non-monotic behavior is observed. It is found that an intermediate particle size results in the widest mixing zone and degree of mixing. This is due to the differences in the spatial accumulation of the particles as they disperse. Small particles accumulate in the bubbles and around the spikes of the Rayleigh-Taylor structures; intermediate-sized particles in the tips of the spikes and as roots into the driver fluid; large particles accumulate primarily in the spikes and as thin, elongated roots into the driver fluid. Such differences are attributed to the response time or Stokes number of the particles. Finally, future directions for extending the current research are summarized.
Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range
Authors: Soltani A. , Stolz A. , Charrier J. , Mattalah M. , Gerbedoen J.-C. , Barkad H. A. , Mortet V. , Rousseau M. , Bourzgui N. , BenMoussa A. , De Jaeger J.-C.
Published: April 2014

Optical waveguiding properties of a thick wurtzite aluminum nitride highly [002]-textured hetero-epitaxial film on (001) basal plane of sapphire substrate are studied. The physical properties of the film are determined by X-ray diffraction, atomic force microscopy, microRaman, and photocurrent spectroscopy. The refractive index and the thermo-optic coefficients are determined by m-lines spectroscopy using the classical prism coupling technique. The optical losses of this planar waveguide are also measured in the spectral range of 450–1553 nm. The lower value of optical losses is equal to 0.7 dB/cm at 1553 nm. The optical losses due to the surface scattering are simulated showing that the contribution is the most significant at near infrared wavelength range, whereas the optical losses are due to volume scattering and material absorption in the visible range. The good physical properties and the low optical losses obtained from this planar waveguide are encouraging to achieve a wide bandgap optical guiding platform from these aluminum nitride thin films.
Note: Switching crosstalk on and off in Kelvin probe force microscopy
Authors: Polak Leo , de Man Sven , Wijngaarden Rinke J.
Published: April 2014

In Kelvin Probe Force Microscopy (KPFM) electronic crosstalk can occur between the excitation signal and probe deflection signal. Here, we demonstrate how a small modification to our commercial instrument enables us to literally switch the crosstalk on and off. We study in detail the effect of crosstalk on open-loop KPFM and compare with closed-loop KPFM. We measure the pure crosstalk signal and verify that we can correct for it in the data-processing required for open-loop KPFM. We also demonstrate that open-loop KPFM results are independent of the frequency and amplitude of the excitation signal, provided that the influence of crosstalk has been eliminated.
Experimental demonstration of a broadband all-dielectric metamaterial perfect reflector
Authors: Moitra Parikshit , Slovick Brian A. , Gang Yu Zhi , Krishnamurthy S. , Valentine Jason
Published: April 2014

All-dielectric metamaterials utilizing Mie resonances in high-permittivity dielectric resonators offer a low-loss alternative to plasmonic metamaterials. Here we present the demonstration of a single-negative all-dielectric metamaterial, comprised of a single layer of cylindrical silicon resonators on a silicon-on-insulator substrate, that possesses peak reflectance over 99% and an average reflectance over 98% across a 200 nm wide bandwidth in the short-wavelength infrared region. The study is also extended to disordered metamaterials, demonstrating a correlation between the degree of disorder and the reduction in reflectance. It is shown that near-unity reflection is preserved as long as resonator interaction is avoided. Realization of near-unity reflection from disordered metamaterials opens the door to large-area implementations using low-cost self-assembly based fabrication techniques.
Laser-generated ultrasound with optical fibres using functionalised carbon nanotube composite coatings
Authors: Colchester Richard J. , Mosse Charles A. , Bhachu Davinder S. , Bear Joseph C. , Carmalt Claire J. , Parkin Ivan P. , Treeby Bradley E. , Papakonstantinou Ioannis , Desjardins Adrien E.
Published: April 2014

Optical ultrasound transducers were created by coating optical fibres with a composite of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS). Dissolution of CNTs in PDMS to create the composite was facilitated by functionalisation with oleylamine. Composite surfaces were applied to optical fibres using dip coating. Under pulsed laser excitation, ultrasound pressures of 3.6 MPa and 4.5 MPa at the coated end faces were achieved with optical fibre core diameters of 105 and 200 μm, respectively. The results indicate that CNT-PDMS composite coatings on optical fibres could be viable alternatives to electrical ultrasound transducers in miniature ultrasound imaging probes.
Electronic structure evolution and energy level alignment at C60/4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine]/MoOx/indium tin oxide interfaces
Authors: Liu Xiaoliang , Yi Shijuan , Wang Chenggong , Wang Congcong , Gao Yongli
Published: April 2014

The electronic structure evolution and energy level alignment have been investigated at interfaces comprising fullerene (C60)/4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine] (TAPC)/ molybdenum oxide (MoOx)/ indium tin oxide with ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy. With deposition of TAPC upon MoOx, a dipole of 1.58 eV was formed at the TAPC/MoOx interface due to electron transfer from TAPC to MoOx. The highest occupied molecular orbital (HOMO) onset of TAPC was pinned closed to the Fermi level, leading to a p-doped region and thus increasing the carrier concentration at the very interface. The downward band bending and the resulting built-in field in TAPC were favorable for the hole transfer toward the TAPC/MoOx interface. The rigid downward shift of energy levels of TAPC indicated no significant interface chemistry at the interface. With subsequent deposition of C60 on TAPC, a dipole of 0.27 eV was observed at the C60/TAPC heterojunction due to the electron transfer from TAPC to C60. This led to a drop of the HOMO of TAPC near the C60/TAPC interface, and hence further enhanced the band bending in TAPC. The band bending behavior was also observed in C60, similarly creating a built-in field in C60 film and improving the electron transfer away from the C60/TAPC interface. It can be deduced from the interface analysis that a promising maximum open circuit voltage of 1.5 eV is achievable in C60/TAPC-based organic photovoltaic cells.
Phase instability and defect induced evolution of optical properties in Cd rich-CdS nanoparticles
Authors: Chandran Anoop , George K. C.
Published: April 2014

Although semiconductor nanostructures exhibit improved physical properties, their structural instability is be a problem for technological applications. This paper reports a temperature-induced low energy phase transformation that occurs in CdS nanoparticles which is ascribed to thermally generated stacking-faults. The phase transformation is found to change the nature of lattice strain in the samples. The formation of this defect-induced lattice strain and its influence on the physical properties of the samples are investigated. The modified optical absorption and emission properties of the samples are thoroughly studied. Using resonance Raman spectroscopy, the evolution of electron-phonon (e-p) coupling strength with structural changes is studied. An explanation to the contradictory nature of e-p coupling strength observed in the nano-regime is given.
Effect of surface charge on the dark current of InGaAs/InP avalanche photodiodes
Authors: Zeng Q. Y. , Wang W. J. , Wen J. , Huang L. , Liu X. H. , Li N. , Lu W.
Published: April 2014

The effects of surface charge on the dark current of the separate-absorption-grading-charge-multiplication InGaAs/InP avalanche photodiodes (APDs) are discussed using drift-diffusion simulation. The dark current increases exponentially with the increasing of surface charge density, and gets multiplied, thus influencing the performance of the APDs, especially in Geiger mode. The mechanism of the surface charge leakage current is discussed, and a floating guard ring structure is proposed to suppress the influence of surface charge effectively.
Photoluminescence spectroscopy of YVO4:Eu3+ nanoparticles with aromatic linker molecules: A precursor to biomedical functionalization
Authors: Senty T. R. , Yalamanchi M. , Zhang Y. , Cushing S. K. , Seehra M. S. , Shi X. , Bristow A. D.
Published: April 2014

Photoluminescence spectra of YVO4:Eu3+ nanoparticles are presented, with and without the attachment of organic molecules that are proposed for linking to biomolecules. YVO4:Eu3+ nanoparticles with 5% dopant concentration were synthesized via wet chemical synthesis. X-ray diffraction and transmission electron microscopy show the expected wakefieldite structure of tetragonal particles with an average size of 17 nm. Fourier-transform infrared spectroscopy determines that metal-carboxylate coordination is successful in replacing native metal-hydroxyl bonds with three organic linkers, namely, benzoic acid, 3-nitro 4-chloro-benzoic acid, and 3,4-dihydroxybenzoic acid, in separate treatments. UV-excitation photoluminescence spectra show that the position and intensity of the dominant 5D0 – 7F2 electric-dipole transition at 619 nm are unaffected by the benzoic acid and 3-nitro 4-chloro-benzoic acid treatments. Attachment of 3,4-dihydroxybenzoic acid produces an order-of-magnitude quenching in the photoluminescence, due to the presence of high-frequency vibrational modes in the linker. Ratios of the dominant electric- and magnetic-dipole transitions confirm infrared measurements, which indicate that the bulk crystal of the nanoparticle is unchanged by all three treatments.
The polarization trajectory of terahertz magnetic dipole radiation in (110)-oriented PrFeO3 single crystal
Authors: Song Gaibei , Jin Zuanming , Lin Xian , Jiang Junjie , Wang Xinyan , Wu Hailong , Ma Guohong , Cao Shixun
Published: April 2014

By using the polarized terahertz (THz) time-domain spectroscopy, the macro-magnetization motion in (110)-oriented PrFeO3 single crystal was constructed. We emphasize that the trajectory of the emitted THz waveforms relies on not only the motion of macroscopic magnetization vector, but also the spin configuration in the ground state and the propagation of THz pulse. The azimuthal angle (the incident THz pulse polarization with respect to the crystal axes) enables us to control the polarization trajectories of the quasiferromagnetic and quasiantiferromagnetic mode radiations that can lead to further applications on multiple information storing and quantum processing.
Enhancement of transport critical current density of SmFeAsO1−xFx tapes fabricated by an ex-situ powder-in-tube method with a Sn-presintering process
Authors: Zhang Qianjun , Yao Chao , Lin He , Zhang Xianping , Wang Dongliang , Dong Chiheng , Yuan Pusheng , Tang Shaopu , Ma Yanwei , Awaji Satoshi , Watanabe Kazuo , Tsuchiya Yuji , Tamegai Tsuyoshi
Published: April 2014

SmFeAsO1−xFx (Sm1111) tapes were prepared by an ex-situ powder-in-tube method with a Sn-presintering process. Scanning electron microscopy revealed apparent difference in microstructure between Sn-presintered tapes and the previously reported polycrystalline Sm1111 bulk, since Sn has reduced FeAs wetting phase and filled the voids between Sm1111 grains. The Sn-presintered tapes showed significant enhanced field dependences of transport Jc compared with Sn-added tapes. A highest transport critical current density (Jc) of 3.45 × 104 A cm−2 at 4.2 K and self-field is achieved. Magneto-optical imaging further confirmed large and well-distributed global and intergranular Jc in Sn-presintered Sm1111 tapes.
Superhydrophobic metallic glass surface with superior mechanical stability and corrosion resistance
Authors: Ma J. , Zhang X. Y. , Wang D. P. , Zhao D. Q. , Ding D. W. , Liu K. , Wang W. H.
Published: April 2014

Superhydrophobic surface with mechanical stability and corrosion resistance is long expected due to its practical applications. We show that a micro-nano scale hierarchical structured Pd-based metallic glass surface with superhydrophobic effect can be prepared by the thermoplastic forming, which is a unique and facile synthesis strategy for metallic glasses. The superhydrophobic metallic glass surface without modification of low surface energy chemical layer also exhibits superior mechanical stability and corrosion resistance compared with conventional superhydrophobic materials. Our results indicate that the metallic glass is a promising candidate superhydrophobic material for applications.
Low voltage reversible electrowetting exploiting lubricated polymer honeycomb substrates
Authors: Bormashenko Edward , Pogreb Roman , Bormashenko Yelena , Grynyov Roman , Gendelman Oleg
Published: April 2014

Low-voltage electrowetting-on-dielectric scheme realized with lubricated honeycomb polymer surfaces is reported. Polycarbonate honeycomb reliefs manufactured with the breath-figures self-assembly were impregnated with silicone and castor oils. The onset of the reversible electrowetting for silicone oil impregnated substrates occurred at 35 V, whereas for castor oil impregnated ones it took place at 80 V. The semi-quantitative analysis of electrowetting of impregnated surfaces is proposed.
Sport Expertise: The Role of Precise Timing of Verbal-Analytical Engagement and the Ability to Detect Visual Cues
Authors: Taliep Mogammad Sharhidd , John Lester
Published: April 2014

This study proposed that relative timing of high-alpha (10–12 Hz) left (T3) and right (T4) cortical temporal electroencephalographic (EEG) power levels would differentiate performance groups in a reactive sport such as cricket batting. The time course of EEG event-related alpha synchronisation (ERS) and desynchronisation was investigated in two groups (eight skilled and ten less skilled) of right-handed cricket batsmen whilst viewing projected video footage of a bowler delivering a randomised series of 24 deliveries repeated 10 times (total of 240 deliveries). Ball release from the bowler's hand was used as the corresponding reaction cue. Participants were instructed to press one of two buttons on a keypad to identify in-swingers or out-swingers. T3 ERS was significantly greater in skilled batsmen from approximately 1500 ms prior to ball release, but differences reduced close to ball release, reaching nonsignificance by 250 ms. There was no significant difference in T4 between the groups. This study uniquely highlights that the relative timing of the T3 high-alpha ERS state appears to differentiate batting skill groups in a reactive task.
Location Probability Learning Requires Focal Attention
Authors: Kabata Takashi , Yokoyama Takemasa , Noguchi Yasuki , Kita Shinichi
Published: April 2014

Target identification is related to the frequency with which targets appear at a given location, with greater frequency enhancing identification. This phenomenon suggests that location probability learned through repeated experience with the target modulates cognitive processing. However, it remains unclear whether attentive processing of the target is required to learn location probability. Here, we used a dual-task paradigm to test the location probability effect of attended and unattended stimuli. Observers performed an attentionally demanding central-letter task and a peripheral-bar discrimination task in which location probability was manipulated. Thus, we were able to compare performance on the peripheral task when attention was fully engaged to the target (single-task condition) versus when attentional resources were drawn away by the central task (dual-task condition). The location probability effect occurred only in the single-task condition, when attention resources were fully available. This suggests that location probability learning requires attention to the target stimuli.
The Effects of Rotating the Self Out of the Body in the Full Virtual Body Ownership Illusion
Authors: Blom Kristopher J , Arroyo-Palacios Jorge , Slater Mel
Published: April 2014

It has been shown that it is possible to induce a strong illusion that a virtual body (VB) is one's own body. However, the relative influence of a first-person-perspective (1PP) view of the VB and spatial coincidence of the real body and VB remains unclear. We demonstrate a method that permits separation of these two factors. It provides a 1PP view of a VB, supporting visuomotor synchrony between real body and VB movements, but where the entire scene including the body is rotated 15° upwards through the axis connecting the eyes, so that the VB and real body are coincident only through this axis. In a within-subjects study that compared this 15° rotation with a 0° rotation condition, participants reported only slightly diminished levels of perceived ownership of the VB in the rotated condition and did not detect the rotation of the scene. These results indicate that strong spatial coincidence of the virtual and real bodies is not necessary for a full-body ownership illusion. The rotation method used, similar to the effects of vertical prisms, did not produce significant negative side-effects, thus providing a useful methodology for further investigations of body ownership.
Where is Uphill? Exploring Sex Differences When Reorienting on a Sloped Environment Presented through 2-D Images
Authors: Nardi Daniele , Meloni Roberta , Orlandi Marco , Olivetti-Belardinelli Marta
Published: April 2014

One of the spatial abilities that has recently revealed a remarkable variability in performance is that of using terrain slope to reorient. Previous studies have shown a very large disadvantage for females when the slope of the floor is the only information useful for encoding a goal location. However, the source of this sex difference is still unclear. The slope of the environment provides a directional source of information that is perceived through dissociable visual and kinesthetic sensory modalities. Here we focused on the visual information, and examined whether there are sex differences in the perception of a slope presented through 2-D images with a desktop computer connected to an eye-tracking device. Participants had to identify and point to the uphill direction by looking at different orientations of two virtual, slanted environments (one indoor and one outdoor). Men were quicker and more accurate than women, indicating that the female difficulty with slope emerges at an early, unisensory, perceptual level. However, the eye-tracking data revealed no sex differences in the slope cues used, providing no support to the hypothesis of sex-specific, visual-processing strategies. Interestingly, performance correlated with a test of mental rotation, and we speculate that the disadvantage in mental rotation ability might be an important factor responsible for females' difficulty using slope.
CK2 activates kinesin via induction of a conformational change
Authors: Mattson-Hoss Michelle K. , Niitani Yamato , Gordon Elizabeth A. , Jun Yonggun , Bardwell Lee , Tomishige Michio , Gross Steven P.
Published: April 2014

Significance

Kinesin regulation by autoinhibition has been extensively studied. However, it is known that cargo-bound kinesin motion can be altered by various signaling pathways. How are these kinesins regulated? Kinesin regulation by the signaling kinase casein kinase 2 (CK2) was previously reported to activate inactive kinesin at the level of the single motor head domain, but the mechanism was unknown. Here, using a multidisciplinary approach, we discover that kinesin inactivation involves a specific conformational change in the molecule’s neck linker, which controls microtubule affinity and is reversed by CK2.
Differential regulation of staphylococcal virulence by the sensor kinase SaeS in response to neutrophil-derived stimuli
Authors: Flack Caralyn E. , Zurek Oliwia W. , Meishery Delisha D. , Pallister Kyler B. , Malone Cheryl L. , Horswill Alexander R. , Voyich Jovanka M.
Published: April 2014

Significance

Staphylococcus aureus
is a ubiquitous pathogen that causes disease in a variety of tissues. Our studies provide insight into how this pathogen uses the SaeS sensor kinase to recognize innate immunity signals and induce a transcriptional response tailored for its environment. Our results demonstrate that the specificity of these responses is determined by individual amino acids predicted to be in an extracellular domain. These amino acids include aromatic anchors and a methionine residue essential for activation of target gene transcription and virulence. Our findings provide a putative mechanism for the ability of bacterial sensory systems to integrate and diversify the responses to host stimuli. They underscore the exquisite nature of bacterial signaling and the complexity of host-pathogen interactions.
Phenotypic switching in gene regulatory networks
Authors: Thomas Philipp , Popović Nikola , Grima Ramon
Published: April 2014

Significance

Phenotypes of an isogenic cell population are determined by states of low and high gene expression. These are often associated with multiple steady states predicted by deterministic models of gene regulatory networks. Gene expression is, however, regulated via stochastic molecular interactions at transcriptional and translational levels. Here, we show that intrinsic noise can induce multimodality in a wide class of regulatory networks whose corresponding deterministic description lacks multistability, thus offering a plausible alternative mechanism for phenotypic switching without the need for ultrasensitivity or highly cooperative interactions. We derive a general analytical framework for quantifying this phenomenon, thereby elucidating how cells encode decisions, and how they retain memory of transient environmental signals, using common gene regulatory motifs.
Quantitative phosphoproteomic analysis reveals system-wide signaling pathways downstream of SDF-1/CXCR4 in breast cancer stem cells
Authors: Yi Tingfang , Zhai Bo , Yu Yonghao , Kiyotsugu Yoshikawa , Raschle Thomas , Etzkorn Manuel , Seo Hee-Chan , Nagiec Michal , Luna Rafael E. , Reinherz Ellis L. , Blenis John , Gygi Steven P. , Wagner Gerhard
Published: April 2014

Significance

Tumor metastasis is the major cause of cancer lethality, whereas the underlying mechanisms are obscure. Breast cancer stem cells (CSCs) are essential for breast cancer relapse and metastasis and stromal cell-derived factor 1 (SDF-1)/chemokine (C-X-C motif) receptor 4 (CXCR4) is a key regulator of tumor dissemination. We report a large-scale quantification of SDF-1/CXCR4–induced phosphoproteome events and identify several previously unidentified phosphoproteins and signaling pathways in breast CSCs. This study provides insights into the understanding of the mechanisms of breast cancer metastasis.
Moving gating charges through the gating pore in a Kv channel voltage sensor
Authors: Lacroix Jérôme J. , Hyde H. Clark , Campos Fabiana V. , Bezanilla Francisco
Published: April 2014

Significance

Voltage sensors are integral membrane protein domains that regulate ion channels and enzymes by transporting electrically charged residues across a narrow constriction that focuses the membrane electrical field. Here, we investigated how this constriction, also called the “gating pore,” controls this transport by studying the effects of a large number of point mutations. Our analysis indicates the presence of nonambiguous statistical correlations between specific amino acid lateral-chain physicochemical properties (size, hydrophobicity) and specific functional features of the voltage sensor (voltage sensitivity and transport kinetics). This study allowed us to propose engineering-like mechanisms by which gating pore residues control the voltage sensor operation.
Re-establishment of Achaemenid History and its Development in the Nineteenth and Twentieth Centuries
Authors: Imanpour Mohammad-Taqi
Published: April 2014

Iranians were aware of Sasanian history through traditional historical writings, but they knew nothing about Achaemenid history. Following European travelers to Persia from the fifteenth century, who were well prepared by reading the classical and biblical texts, Persepolis and Pasargadae were rediscovered and Achaemenid history re-established in the nineteenth century. The rise of Reza Khan to power and his grand emphasis on nationalism and ancient Iran that characterized his reign also left a deeper impact on Achaemenid studies in this period. In this paper the re-establishment of Achaemenid history and its development in nineteenth and twentieth centuries are discussed and reviewed.
Grotesque Corporeality and Literary Aesthetics in Sadeq Chubak's The Patient Stone
Authors: Hendelman-Baavur Liora
Published: April 2014

This article is concerned with ways in which grotesque corporeality shapes Sadeq Chubak's controversial novel The Patient Stone (Sang-e Sabur, 1966). Drawing on Mikhail Bakhtin's understanding of grotesque realism in Rabelais and His World, the discussion demonstrates that Chubak employed devices associated with grotesque aesthetics, and that these devices were used to invert and contest social and literary conventions in Iranian culture, although it seems he remains caught to a certain extent within the very systems he challenges. Grotesque realism involves estrangement of the familiar, and leads to degrading the abstract, spiritual and sublime to the material level of physicality and the body. In The Patient Stone, Chubak replicates motifs of classical Persian epics, religious scriptures and the myth of creation and debases them by excessive depictions of bodily conditions and grotesque corporeality (such as deformity, paralysis and decay). The use of grotesque corporeality embodied in the style, content and characters of Chubak's novel facilitates a variety of paradoxes of being and non-being, appearance and reality, death and rebirth, hope and anxiety of a fragmented and alienated society in desperate need of change.
Development of hypoallergenic galacto-oligosaccharides on the basis of allergen analysis
Authors: Kaneko Kimiyuki , Watanabe Yoko , Kimura Kazumasa , Matsumoto Keisuke , Mizobuchi Takahiro , Onoue Masaharu
Published: April 2014

Galacto-oligosaccharides (GOSs) are recognized as prebiotics beneficial to human health through their abilities to modulate gut microbiota. On the other hand, it has been reported that immediate allergic reactions are caused by a GOS product (Bc-GOS) produced by treating lactose with β-galactosidase derived from Bacillus circulans. The objective of this study was to create a safer GOS product that is less likely to cause GOS-induced allergy (GOS-AL). First, we identified two derivatives of tetrasaccharide sugar chains in Bc-GOS as the factors responsible for GOS-AL by histamine release test (HRT) using blood samples obtained from two GOS-AL patients. Through our search for non-allergic GOS, we developed a new GOS product, SK-GOS, which was produced by catalyzing lactose with β-galactosidase derived from Sporobolomyces singularis and Kluyveromyces lactis. We regard it as a hypoallergic and safe GOS product that does not cause GOS-AL.
Chemical ecology of insect–plant interactions: ecological significance of plant secondary metabolites
Authors: Nishida Ritsuo
Published: April 2014

Plants produce a diverse array of secondary metabolites as chemical barriers against herbivores. Many phytophagous insects are highly adapted to these allelochemicals and use such unique substances as the specific host-finding cues, defensive substances of their own, and even as sex pheromones or their precursors by selectively sensing, incorporating, and/or processing these phytochemicals. Insects also serve as pollinators often effectively guided by specific floral fragrances. This review demonstrates the ecological significance of such plant secondary metabolites in the highly diverse interactions between insects and plants.
Local Dirichlet forms, Hodge theory, and the Navier-Stokes equations on topologically one-dimensional fractals
Authors: Hinz Michael , Teplyaev Alexander
Published: April 2014

We consider finite energy and

L
2

L^2

differential forms associated with strongly local regular Dirichlet forms on compact connected topologically one-dimensional spaces. We introduce notions of local exactness and local harmonicity and prove the Hodge decomposition, which in our context says that the orthogonal complement to the space of all exact 1-forms coincides with the closed span of all locally harmonic 1-forms. Then we introduce a related Hodge Laplacian and define a notion of harmonicity for finite energy 1-forms. As a corollary, under a certain capacity-separation assumption, we prove that the space of harmonic 1-forms is nontrivial if and only if the classical Čech cohomology is nontrivial. In the examples of classical self-similar fractals these spaces typically are either trivial or infinitely dimensional. Finally, we study Navier-Stokes type models and prove that under our assumptions they have only steady state divergence free solutions. In particular, we solve the existence and uniqueness problem for the Navier-Stokes and Euler equations for a large class of fractals that are topologically one-dimensional but can have arbitrary Hausdorff and spectral dimensions.
Sevoflurane Induces Tau Phosphorylation and Glycogen Synthase Kinase 3β Activation in Young Mice
Authors: Tao Guorong , Zhang Jie , Zhang Lei , Dong Yuanlin , Yu Buwei , Crosby Gregory , Culley Deborah J. , Zhang Yiying , Xie Zhongcong
Published: April 2014

Background:

Children with multiple exposures to anesthesia and surgery may have an increased risk of developing cognitive impairment. Sevoflurane is a commonly used anesthetic in children. Tau phosphorylation contributes to cognitive dysfunction. The authors therefore assessed the effects of sevoflurane on Tau phosphorylation and the underlying mechanisms in young mice.

Methods:

Six-day-old wild-type and Tau knockout mice were exposed to sevoflurane. The authors determined the effects of sevoflurane anesthesia on Tau phosphorylation, levels of the kinases and phosphatase related to Tau phosphorylation, interleukin-6 and postsynaptic density protein-95 in hippocampus, and cognitive function in both young wild-type and Tau knockout mice.

Results:

Anesthesia with 3% sevoflurane 2 h daily for 3 days induced Tau phosphorylation (257 vs. 100%, P = 0.0025, n = 6) and enhanced activation of glycogen synthase kinase 3β, which is the kinase related to Tau phosphorylation in the hippocampus of postnatal day-8 wild-type mice. The sevoflurane anesthesia decreased hippocampus postsynaptic density protein-95 levels and induced cognitive impairment in the postnatal day-31 mice. Glycogen synthase kinase 3β inhibitor lithium inhibited the sevoflurane-induced glycogen synthase kinase 3β activation, Tau phosphorylation, increased levels of interleukin-6, and cognitive impairment in the wild-type young mice. Finally, the sevoflurane anesthesia did not induce an increase in interleukin-6 levels, reduction in postsynaptic density protein-95 levels in hippocampus, or cognitive impairment in Tau knockout young mice.

Conclusions:

These data suggested that sevoflurane induced Tau phosphorylation, glycogen synthase kinase 3β activation, increase in interleukin-6 and reduction in postsynaptic density protein-95 levels in hippocampus of young mice, and cognitive impairment in the mice. Future studies will dissect the cascade relation of these effects.
Genotypic variation in a foundation tree (
Populus tremula
L.) explains community structure of associated epiphytes
Authors: Davies Chantel , Ellis Christopher J. , Iason Glenn R. , Ennos Richard A.
Published: April 2014

Community genetics hypothesizes that within a foundation species, the genotype of an individual significantly influences the assemblage of dependent organisms. To assess whether these intra-specific genetic effects are ecologically important, it is required to compare their impact on dependent organisms with that attributable to environmental variation experienced over relevant spatial scales. We assessed bark epiphytes on 27 aspen (
Populus tremula
L.) genotypes grown in a randomized experimental array at two contrasting sites spanning the environmental conditions from which the aspen genotypes were collected. We found that variation in aspen genotype significantly influenced bark epiphyte community composition, and to the same degree as environmental variation between the test sites. We conclude that maintaining genotypic diversity of foundation species may be crucial for conservation of associated biodiversity.
Glassfrog embryos hatch early after parental desertion
Authors: Delia Jesse R. J. , Ramírez-Bautista Aurelio , Summers Kyle
Published: April 2014

Both parental care and hatching plasticity can improve embryo survival. Research has found that parents can alter hatching time owing to a direct effect of care on embryogenesis or via forms of care that cue the hatching process. Because parental care alters conditions critical for offspring development, hatching plasticity could allow embryos to exploit variation in parental behaviour. However, this interaction of parental care and hatching plasticity remains largely unexplored. We tested the hypothesis that embryos hatch early to cope with paternal abandonment in the glassfrogHyalinobatrachium fleischmanni(Centrolenidae). We conducted male-removal experiments in a wild population, and examined embryos' response to conditions with and without fathers. Embryos hatched early when abandoned, but extended development in the egg stage when fathers continued care. Paternal care had no effect on developmental rate. Rather, hatching plasticity was due to embryos actively hatching at different developmental stages, probably in response to deteriorating conditions without fathers. Our experimental results are supported by a significant correlation between the natural timing of abandonment and hatching in an unmanipulated population. This study demonstrates that embryos can respond to conditions resulting from parental abandonment, and provides insights into how variation in care can affect selection on egg-stage adaptations.
How (and why) the visual control of action differs from visual perception
Authors: Goodale Melvyn A.
Published: April 2014

Vision not only provides us with detailed knowledge of the world beyond our bodies, but it also guides our actions with respect to objects and events in that world. The computations required for vision-for-perception are quite different from those required for vision-for-action. The former uses relational metrics and scene-based frames of reference while the latter uses absolute metrics and effector-based frames of reference. These competing demands on vision have shaped the organization of the visual pathways in the primate brain, particularly within the visual areas of the cerebral cortex. The ventral ‘perceptual’ stream, projecting from early visual areas to inferior temporal cortex, helps to construct the rich and detailed visual representations of the world that allow us to identify objects and events, attach meaning and significance to them and establish their causal relations. By contrast, the dorsal ‘action’ stream, projecting from early visual areas to the posterior parietal cortex, plays a critical role in the real-time control of action, transforming information about the location and disposition of goal objects into the coordinate frames of the effectors being used to perform the action. The idea of two visual systems in a single brain might seem initially counterintuitive. Our visual experience of the world is so compelling that it is hard to believe that some other quite independent visual signal—one that we are unaware of—is guiding our movements. But evidence from a broad range of studies from neuropsychology to neuroimaging has shown that the visual signals that give us our experience of objects and events in the world are
not
the same ones that control our actions.
Low functional redundancy among mammalian browsers in regulating an encroaching shrub (
Solanum campylacanthum
) in African savannah
Authors: Pringle Robert M. , Goheen Jacob R. , Palmer Todd M. , Charles Grace K. , DeFranco Elyse , Hohbein Rhianna , Ford Adam T. , Tarnita Corina E.
Published: April 2014

Large herbivorous mammals play an important role in structuring African savannahs and are undergoing widespread population declines and local extinctions, with the largest species being the most vulnerable. The impact of these declines on key ecological processes hinges on the degree of functional redundancy within large-herbivore assemblages, a subject that has received little study. We experimentally quantified the effects of three browser species (elephant, impala and dik-dik) on individual- and population-level attributes of
Solanum campylacanthum
(
Solanum incanum sensu lato
), an encroaching woody shrub, using semi-permeable exclosures that selectively removed different-sized herbivores. After nearly 5 years, shrub abundance was lowest where all browser species were present and increased with each successive species deletion. Different browsers ate the same plant species in different ways, thereby exerting distinct suites of direct and indirect effects on plant performance and density. Not all of these effects were negative: elephants and impala also dispersed viable seeds and indirectly reduced seed predation by rodents and insects. We integrated these diffuse positive effects with the direct negative effects of folivory using a simple population model, which reinforced the conclusion that different browsers have complementary net effects on plant populations, and further suggested that under some conditions, these net effects may even differ in direction.
Characterizing a collective and dynamic component of chromatin immunoprecipitation enrichment profiles in yeast
Authors: Ward Lucas D. , Wang Junbai , Bussemaker Harmen J.
Published: April 2014

Recent chromatin immunoprecipitation (ChIP) experiments in fly, mouse, and human have revealed the existence of high-occupancy target (HOT) regions or hotspots that show enrichment across many assayed DNA-binding proteins. Similar co-enrichment observed in yeast so far has been treated as artifactual, and has not been fully characterized. Here we reanalyze ChIP data from both array-based and sequencing-based experiments to show that in the yeast S. cerevisiae, the collective enrichment phenomenon is strongly associated with proximity to noncoding RNA genes and with nucleosome depletion. DNA sequence motifs that confer binding affinity for the proteins are largely absent from these hotspots, suggesting that protein-protein interactions play a prominent role. The hotspots are condition-specific, suggesting that they reflect a chromatin state or protein state, and are not a static feature of underlying sequence. Additionally, only a subset of all assayed factors is associated with these loci, suggesting that the co-enrichment cannot be simply explained by a chromatin state that is universally more prone to immunoprecipitation. Together our results suggest that the co-enrichment patterns observed in yeast represent transcription factor co-occupancy. More generally, they make clear that great caution must be used when interpreting ChIP enrichment profiles for individual factors in isolation, as they will include factor-specific as well as collective contributions.
The H+-ATPase HA1 of Medicago truncatula Is Essential for Phosphate Transport and Plant Growth during Arbuscular Mycorrhizal Symbiosis
Authors: Krajinski Franziska , Courty Pierre-Emmanuel , Sieh Daniela , Franken Philipp , Zhang Haoqiang , Bucher Marcel , Gerlach Nina , Kryvoruchko Igor , Zoeller Daniela , Udvardi Michael , Hause Bettina
Published: April 2014

A key feature of arbuscular mycorrhizal symbiosis is improved phosphorus nutrition of the host plant via the mycorrhizal pathway, i.e., the fungal uptake of Pi from the soil and its release from arbuscules within root cells. Efficient transport of Pi from the fungus to plant cells is thought to require a proton gradient across the periarbuscular membrane (PAM) that separates fungal arbuscules from the host cell cytoplasm. Previous studies showed that the H+-ATPase gene HA1 is expressed specifically in arbuscule-containing root cells of Medicago truncatula. We isolated a ha1-2 mutant of M. truncatula and found it to be impaired in the development of arbuscules but not in root colonization by Rhizophagus irregularis hyphae. Artificial microRNA silencing of HA1 recapitulated this phenotype, resulting in small and truncated arbuscules. Unlike the wild type, the ha1-2 mutant failed to show a positive growth response to mycorrhizal colonization under Pi-limiting conditions. Uptake experiments confirmed that ha1-2 mutants are unable to take up phosphate via the mycorrhizal pathway. Increased pH in the apoplast of abnormal arbuscule-containing cells of the ha1-2 mutant compared with the wild type suggests that HA1 is crucial for building a proton gradient across the PAM and therefore is indispensible for the transfer of Pi from the fungus to the plant.
A H+-ATPase That Energizes Nutrient Uptake during Mycorrhizal Symbioses in Rice and Medicago truncatula
Authors: Wang Ertao , Yu Nan , Bano S. Asma , Liu Chengwu , Miller Anthony J. , Cousins Donna , Zhang Xiaowei , Ratet Pascal , Tadege Million , Mysore Kirankumar S. , Downie J. Allan , Murray Jeremy D. , Oldroyd Giles E.D. , Schultze Michael
Published: April 2014

Most plant species form symbioses with arbuscular mycorrhizal (AM) fungi, which facilitate the uptake of mineral nutrients such as phosphate from the soil. Several transporters, particularly proton-coupled phosphate transporters, have been identified on both the plant and fungal membranes and contribute to delivering phosphate from fungi to plants. The mechanism of nutrient exchange has been studied in plants during mycorrhizal colonization, but the source of the electrochemical proton gradient that drives nutrient exchange is not known. Here, we show that plasma membrane H+-ATPases that are specifically induced in arbuscule-containing cells are required for enhanced proton pumping activity in membrane vesicles from AM-colonized roots of rice (Oryza sativa) and Medicago truncatula. Mutation of the H+-ATPases reduced arbuscule size and impaired nutrient uptake by the host plant through the mycorrhizal symbiosis. Overexpression of the H+-ATPase Os-HA1 increased both phosphate uptake and the plasma membrane potential, suggesting that this H+-ATPase plays a key role in energizing the periarbuscular membrane, thereby facilitating nutrient exchange in arbusculated plant cells.