bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear magnetosonic waves in dense plasmas with non-relativistic and ultra-relativistic degenerate electrons
Authors: Hussain S. , Mahmood S. , Rehman Aman-ur-
Published: November 2014

Linear and nonlinear propagation of magnetosonic waves in the perpendicular direction to the ambient magnetic field is studied in dense plasmas for non-relativistic and ultra-relativistic degenerate electrons pressure. The sources of nonlinearities are the divergence of the ions and electrons fluxes, Lorentz forces on ions and electrons fluids and the plasma current density in the system. The Korteweg-de Vries equation for magnetosonic waves propagating in the perpendicular direction of the magnetic field is derived by employing reductive perturbation method for non-relativistic as well as ultra-relativistic degenerate electrons pressure cases in dense plasmas. The plots of the magnetosonic wave solitons are also shown using numerical values of the plasma parameters such a plasma density and magnetic field intensity of the white dwarfs from literature. The dependence of plasma density and magnetic field intensity on the magnetosonic wave propagation is also pointed out in dense plasmas for both non-relativistic and ultra-relativistic degenerate electrons pressure cases.
Surface sensitive microfluidic optomechanical ring resonator sensors
Authors: Kim Kyu Hyun , Fan Xudong
Published: November 2014

The microfluidic optomechanical ring resonator (μFOMRR) based on a thin-walled glass capillary supports high Q-factor (>103) mechanical modes in the presence of liquids. In this letter, the sensitivity of the μFOMRR to the surface change is studied by layer-by-layer removal of SiO2 molecules from the μFOMRR inner surface using various concentrations of hydrofluoric acid solutions. A frequency downshift is observed with a sensitivity for the surface density change of 1.2 Hz/(pg/mm2), which translates to a detection limit of 83 pg/mm2. This work opens a door to using the optomechanical mode for detection and characterization of molecules near the resonator surface.
Anti-Stokes luminescence in the light of second order perturbation theory
Authors: Bhattacharya Rupak , Pal Bipul , Bansal Bhavtosh
Published: November 2014

Anti-Stokes photoluminescence is measured in high-quality GaAs quantum wells. The primary pathway for interband optical absorption and hence emission under subbandgap photoexcitation is the optical phonon-mediated second-order electric dipole transition. This conclusion is drawn from the remarkable agreement between predictions of second-order perturbation calculation and the measured intensity of anti-Stokes photoluminescence, both as function of the detuning wavelength and temperature. The results are of direct relevance to laser cooling of solids where phonon-assisted upconversion is a necessary condition.
Greybody factors for Myers–Perry black holes
Authors: Boonserm Petarpa , Chatrabhuti Auttakit , Ngampitipan Tritos , Visser Matt
Published: November 2014

The Myers–Perry black holes are higher-dimensional generalizations of the usual (3+1)-dimensional rotating Kerr black hole. They are of considerable interest in Kaluza–Klein models, specifically within the context of brane-world versions thereof. In the present article, we shall consider the greybody factors associated with scalar field excitations of the Myers–Perry spacetimes, and develop some rigorous bounds on these greybody factors. These bounds are of relevance for characterizing both the higher-dimensional Hawking radiation, and the super-radiance, that is expected for these spacetimes.
Phase transitions in BaTiO3 thin films and BaTiO3/BaZrO3 superlattices
Authors: Yuzyuk Yu. I. , Sakhovoy R. A. , Maslova O. A. , Shirokov V. B. , Zakharchenko I. N. , Belhadi J. , El Marssi M.
Published: November 2014

Using pulsed laser deposition, we grew a ferroelectric [BaTiO3]Λ/2/[BaZrO3]Λ/2 (BT/BZ) superlattice with a stacking periodicity of Λ = 256 Å and a BT single film on a La1/2Sr1/2CoO3-buffered (001)MgO substrate, and then studied the phase transitions of these materials. At room temperature, the polarized Raman spectra of the BT film corresponded to a ferroelectric orthorhombic C2V14 phase with the polar axis oriented in the plane of the substrate. A ferroelectric-paraelectric phase transition in the BT film occurred at ∼450 K. Upon cooling to ∼300 K, a phase transition to the monoclinic Cs3 phase occurred. These experimental results agree well with a theoretical “temperature-misfit strain” phase diagram of the BT film. We found no evidence of phase transitions in the BT/BZ superlattice below room temperature. The phase transition to the paraelectric phase in the BT/BZ superlattice increased in temperature because of lattice mismatch between the BT and BZ layers. A desirable Curie temperature can be tailored rather precisely by varying the layer thicknesses or the BT/BZ ratio in the superlattice. The BT/BZ superlattices are very good for device applications because their ferroelectric phase with in-plane polarization can remain stable at least from 0 K up to 723 K, and even at higher temperatures in superlattices with smaller periodicities.
Formation energy of oxygen vacancies in ZnO determined by investigating thermal behavior of Al and In impurities
Authors: Komatsuda S. , Sato W. , Ohkubo Y.
Published: November 2014

Thermal behavior and interacting nature of 100-ppm Al and ∼100-ppt In impurities doped in zinc oxide (ZnO) were investigated by means of the time-differential perturbed angular correlation method with the 111In(→111Cd) probe. Contrasting interactions between Al and In impurities were observed depending on different atmospheric conditions: (1) in air, Al and In impurities irreversibly associate with each other in the process of their thermal diffusion, but (2) in vacuum, their bound state formed in air dissociates by heat treatment at temperatures higher than 873 K, and this process is enhanced with increasing temperature. Detailed investigation of the thermal behavior of the impurities has revealed that the dissociation reaction is triggered by the formation of oxygen vacancies in the vicinity of the locally associated In-Al structure. A unique method to determine the activation energy of the oxygen-vacancy formation is presented with the estimated experimental value of Ea = 0.72(6) eV.
Communication: On the consistency of approximate quantum dynamics simulation methods for vibrational spectra in the condensed phase
Authors: Rossi Mariana , Liu Hanchao , Paesani Francesco , Bowman Joel , Ceriotti Michele
Published: November 2014

Including quantum mechanical effects on the dynamics of nuclei in the condensed phase is challenging, because the complexity of exact methods grows exponentially with the number of quantum degrees of freedom. Efforts to circumvent these limitations can be traced down to two approaches: methods that treat a small subset of the degrees of freedom with rigorous quantum mechanics, considering the rest of the system as a static or classical environment, and methods that treat the whole system quantum mechanically, but using approximate dynamics. Here, we perform a systematic comparison between these two philosophies for the description of quantum effects in vibrational spectroscopy, taking the Embedded Local Monomer model and a mixed quantum-classical model as representatives of the first family of methods, and centroid molecular dynamics and thermostatted ring polymer molecular dynamics as examples of the latter. We use as benchmarks D2O doped with HOD and pure H2O at three distinct thermodynamic state points (ice Ih at 150 K, and the liquid at 300 K and 600 K), modeled with the simple q-TIP4P/F potential energy and dipole moment surfaces. With few exceptions the different techniques yield IR absorption frequencies that are consistent with one another within a few tens of cm−1. Comparison with classical molecular dynamics demonstrates the importance of nuclear quantum effects up to the highest temperature, and a detailed discussion of the discrepancies between the various methods let us draw some (circumstantial) conclusions about the impact of the very different approximations that underlie them. Such cross validation between radically different approaches could indicate a way forward to further improve the state of the art in simulations of condensed-phase quantum dynamics.
Inviscid evolution of large amplitude filaments in a uniform gravity field
Authors: Angus J. R. , Krasheninnikov S. I.
Published: November 2014

The inviscid evolution of localized density stratifications under the influence of a uniform gravity field in a homogeneous, ambient background is studied. The fluid is assumed to be incompressible, and the stratification, or filament, is assumed to be initially isotropic and at rest. It is shown that the center of mass energy can be related to the center of mass position in a form analogous to that of a solid object in a gravity field g by introducing an effective gravity field geff, which is less than g due to energy that goes into the background and into non-center of mass motion of the filament. During the early stages of the evolution, geff is constant in time and can be determined from the solution of a 1D differential equation that depends on the initial, radially varying density profile of the filament. For small amplitude filaments such that ρ0 ≪ 1, where ρ0 is the relative amplitude of the filament to the background, the early stage geff scales linearly with ρ0, but as ρ0→∞, geff→g and is thus independent of ρ0. Fully nonlinear simulations are performed for the evolution of Gaussian filaments, and it is found that the time tmax, which is defined as the time for the center of mass velocity to reach its maximum value Umax, occurs very soon after the constant acceleration phase and so Umax≈geff(t=0)tmax. The simulation results show that Umax∼1/tmax∼ρ0 for ρ0 ≪ 1, in agreement with theory and results from previous authors, but that Umax and tmax both scale approximately with ρ0 for ρ0 ≫ 1. The fact that Umax and tmax have the same scaling with ρ0 for large amplitude filaments is in agreement with the theory presented in this paper.
Short-circuit current density imaging of crystalline silicon solar cells via lock-in thermography: Robustness and simplifications
Authors: Fertig Fabian , Greulich Johannes , Rein Stefan
Published: November 2014

Spatially resolved determination of solar cell parameters is beneficial for loss analysis and optimization of conversion efficiency. One key parameter that has been challenging to access by an imaging technique on solar cell level is short-circuit current density. This work discusses the robustness of a recently suggested approach to determine short-circuit current density spatially resolved based on a series of lock-in thermography images and options for a simplified image acquisition procedure. For an accurate result, one or two emissivity-corrected illuminated lock-in thermography images and one dark lock-in thermography image have to be recorded. The dark lock-in thermography image can be omitted if local shunts are negligible. Furthermore, it is shown that omitting the correction of lock-in thermography images for local emissivity variations only leads to minor distortions for standard silicon solar cells. Hence, adequate acquisition of one image only is sufficient to generate a meaningful map of short-circuit current density. Beyond that, this work illustrates the underlying physics of the recently proposed method and demonstrates its robustness concerning varying excitation conditions and locally increased series resistance. Experimentally gained short-circuit current density images are validated for monochromatic illumination in comparison to the reference method of light-beam induced current.
Modelling of illuminated current–voltage characteristics to evaluate leakage currents in long wavelength infrared mercury cadmium telluride photovoltaic detectors
Authors: Gopal Vishnu , Qiu WeiCheng , Hu Weida
Published: November 2014

The current–voltage characteristics of long wavelength mercury cadmium telluride infrared detectors have been studied using a recently suggested method for modelling of illuminated photovoltaic detectors. Diodes fabricated on in-house grown arsenic and vacancy doped epitaxial layers were evaluated for their leakage currents. The thermal diffusion, generation–recombination (g-r), and ohmic currents were found as principal components of diode current besides a component of photocurrent due to illumination. In addition, both types of diodes exhibited an excess current component whose growth with the applied bias voltage did not match the expected growth of trap-assisted-tunnelling current. Instead, it was found to be the best described by an exponential function of the type, Iexcess = Ir0 + K1 exp (K2 V), where Ir0, K1, and K2 are fitting parameters and V is the applied bias voltage. A study of the temperature dependence of the diode current components and the excess current provided the useful clues about the source of origin of excess current. It was found that the excess current in diodes fabricated on arsenic doped epitaxial layers has its origin in the source of ohmic shunt currents. Whereas, the source of excess current in diodes fabricated on vacancy doped epitaxial layers appeared to be the avalanche multiplication of photocurrent. The difference in the behaviour of two types of diodes has been attributed to the difference in the quality of epitaxial layers.
Enhanced thermal radiation in terahertz and far-infrared regime by hot phonon excitation in a field effect transistor
Authors: Chung Pei-Kang , Yen Shun-Tung
Published: November 2014

We demonstrate the hot phonon effect on thermal radiation in the terahertz and far-infrared regime. A pseudomorphic high electron mobility transistor is used for efficiently exciting hot phonons. Boosting the hot phonon population can enhance the efficiency of thermal radiation. The transistor can yield at least a radiation power of 13 μW and a power conversion efficiency higher than a resistor by more than 20%.
A portable optical human sweat sensor
Authors: Al-omari Mahmoud , Liu Gengchen , Mueller Anja , Mock Adam , Ghosh Ruby N. , Smith Kyle , Kaya Tolga
Published: November 2014

We describe the use of HNQ (2-hydroxy-1,4-naphthoquinone or Lawsone) as a potential sweat sensor material to detect the hydration levels of human beings. We have conducted optical measurements using both artificial and human sweat to validate our approach. We have determined that the dominant compound that affects HNQ absorbance in artificial sweat is sodium. The presence of lactate decreases the reactivity of HNQ while urea promotes more interactions of sodium and potassium ions with HNQ. The interactions between the hydroxyl group of HNQ and the artificial sweat components (salts, lactic acid, and urea) were investigated comprehensively. We have also proposed and developed a portable diode laser absorption sensor system that converts the absorbance at a particular wavelength range (at 455 ± 5 nm, where HNQ has an absorbance peak) into light intensity measurements via a photocell. The absorbance intensity values obtained from our portable sensor system agrees within 10.4% with measurements from a laboratory based ultraviolet-visible spectrometer. Findings of this research will provide significant information for researchers who are focusing on real-time, in-situ hydration level detection.
Single-step gas phase synthesis of stable iron aluminide nanoparticles with soft magnetic properties
Authors: Vernieres Jerome , Benelmekki Maria , Kim Jeong-Hwan , Grammatikopoulos Panagiotis , Bobo Jean-François , Diaz Rosa E. , Sowwan Mukhles
Published: November 2014

Soft magnetic alloys at the nanoscale level have long generated a vivid interest as candidate materials for technological and biomedical purposes. Consequently, controlling the structure of bimetallic nanoparticles in order to optimize their magnetic properties, such as high magnetization and low coercivity, can significantly boost their potential for related applications. However, traditional synthesis methods stumble upon the long standing challenge of developing true nanoalloys with effective control over morphology and stability against oxidation. Herein, we report on a single-step approach to the gas phase synthesis of soft magnetic bimetallic iron aluminide nanoparticles, using a versatile co-sputter inert gas condensation technique. This method allowed for precise morphological control of the particles; they consisted of an alloy iron aluminide crystalline core (DO3 phase) and an alumina shell, which reduced inter-particle interactions and also prevented further oxidation and segregation of the bimetallic core. Remarkably, the as-deposited alloy nanoparticles show interesting soft magnetic properties, in that they combine a high saturation magnetization (170 emu/g) and low coercivity (less than 20 Oe) at room temperature. Additional functionality is tenable by modifying the surface of the particles with a polymer, to ensure their good colloidal dispersion in aqueous environments.
Negative effective mass density of acoustic metamaterial plate decorated with low frequency resonant pillars
Authors: Oudich Mourad , Djafari-Rouhani Bahram , Pennec Yan , Assouar M. Badreddine , Bonello Bernard
Published: November 2014

We investigate the elastic wave dispersion by a phononic metamaterial plate containing low frequency resonator stubs arranged periodically over the plate. We show that this system not only provides stop bands for wavelengths much larger than the periodicity but also displays negative behavior of its effective mass density under the homogenization assumption. A numerical method is used to calculate the plate's effective dynamic mass density as function of the frequency where the metamaterial is considered as homogeneous plate for these large wavelengths. Strong anisotropy of the effective mass density matrix is observed around the resonance frequencies where the gaps are opened. In these regions, we demonstrate that the effective matrix density components take negative values. For each of these components, the negative behavior is studied by taking into account the polarization of the involved resonant modes as well as their associated partial band gaps opened for each specific Lamb symmetry modes. We found that coupling between Lamb waves and resonant modes strongly affects the effective density of the whole plate especially in the coupling frequency regions of the gaps.
Self-limited underdense microplasmas in bulk silicon induced by ultrashort laser pulses
Authors: Mouskeftaras Alexandros , Rode Andrei V. , Clady Raphaël , Sentis Marc , Utéza Olivier , Grojo David
Published: November 2014

Two-photon ionization by focused femtosecond laser pulses initiates the development of micrometer-scale plasmas in the bulk of silicon. Using pump-and-probe transmission microscopy with infrared light, we investigate the space-time characteristics of these plasmas for laser intensities up to 1012 W/cm2. The measurements reveal a self-limitation of the excitation at a maximum free-carrier density of ≅1019 cm−3, which is more than one order of magnitude below the threshold for permanent modification. The plasmas remain unchanged in the ∼100 ps timescale revealing slow carrier kinetics. The results underline the limits in local control of silicon dielectric permittivity, which are inherent to the use of single near-infrared ultrashort Gaussian pulses.
Interfacial wicking dynamics and its impact on critical heat flux of boiling heat transfer
Authors: Kim Beom Seok , Lee Hwanseong , Shin Sangwoo , Choi Geehong , Cho Hyung Hee
Published: November 2014

Morphologically driven dynamic wickability is essential for determining the hydrodynamic status of solid-liquid interface. We demonstrate that the dynamic wicking can play an integral role in supplying and propagating liquid through the interface, and govern the critical heat flux (CHF) against surface dry-out during boiling heat transfer. For the quantitative control of wicking, we manipulate the characteristic lengths of hexagonally arranged nanopillars within sub-micron range through nanosphere lithography combined with top-down metal-assisted chemical etching. Strong hemi-wicking over the manipulated interface (i.e., wicking coefficients) of 1.28 mm/s0.5 leads to 164% improvement of CHF compared to no wicking. As a theoretical guideline, our wickability-CHF model can make a perfect agreement with improved CHF, which cannot be predicted by the classic models pertaining to just wettability and roughness effects, independently.
Coherence of a spin-polarized electron beam emitted from a semiconductor photocathode in a transmission electron microscope
Authors: Kuwahara Makoto , Kusunoki Soichiro , Nambo Yoshito , Saitoh Koh , Jin Xiuguang , Ujihara Toru , Asano Hidefumi , Takeda Yoshikazu , Tanaka Nobuo
Published: November 2014

The brightness and interference fringes of a spin-polarized electron beam extracted from a semiconductor photocathode excited by laser irradiation are directly measured via its use in a transmission electron microscope. The brightness was 3.8 × 107 A cm−2 sr−1 for a 30-keV beam energy with the polarization of 82%, which corresponds to 3.1 × 108 A cm−2 sr−1 for a 200-keV beam energy. The resulting electron beam exhibited a long coherence length at the specimen position due to the high parallelism of (1.7 ± 0.3) × 10−5 rad, which generated interference fringes representative of a first-order correlation using an electron biprism. The beam also had a high degeneracy of electron wavepacket of 4 × 10−6. Due to the high polarization, the high degeneracy and the long coherence length, the spin-polarized electron beam can enhance the antibunching effect.
Capital Fixity and Mobility in Response to the 2008–09 Crisis: Variegated Neoliberalism in Mexico and Turkey
Authors: Martinez Hepzibah Munoz , Marois Thomas
Published: November 2014

This paper examines the responses to the 2008–09 global financial crisis in Mexico and Turkey as examples of variegated neoliberalism. The simultaneous interests of corporations and banks in the national fixing of capital and their mobility in the form of global investment heavily influenced these states' policy responses to the crisis at the expense of the interests of the poor, workers, and peasantry. Rather than pitching this as evidence of either persistent national differentiation or some Keynesian state resurgence, we argue from a historical materialist geographical framework that the responses of capital and state authorities in Mexico and Turkey actively constitute and reconstitute the global parameters of market regulatory design and neoliberal class rule through each state's distinct domestic policy formation and crisis management processes. The latter is influenced by capitalists' ties to the fixity and motion of capital. While differing in specific content, the form of Mexico's and Turkey's official responses to the crisis ensured continuity in their neoliberal strategies of development and capital accumulation.
Differences in Perceptual Latency Estimated from Judgments of Temporal Order, Simultaneity and Duration are Inconsistent
Authors: Linares Daniel , Holcombe Alex O.
Published: November 2014

Differences in perceptual latency (Δ L) for two stimuli, such as an auditory and a visual stimulus, can be estimated from temporal order judgments (TOJ) and simultaneity judgments (ΔJ), but previous research has found evidence that Δ L estimated from these tasks do not coincide. Here, using an auditory and a visual stimulus we confirmed this and further show that Δ L as estimated from duration judgments also does not coincide with Δ L estimated from TOJ or SJ. These inconsistencies suggest that each judgment is subject to different processes that bias 4 L in different ways: TOJ might be affected by sensory interactions, a bias associated with the method of single stimuli and an order difficulty bias; SJ by sensory interactions and an asymmetrical criterion bias; duration judgments by an order duration bias.
Synthesis and Bioevaluation of Novel Oxa-Caged Garcinia Xanthones as Anti-Tumour Agents
Authors: Miao Guangqiang , Ma Junhai , Yang Kan , Huang Zhipeng , Gu Qinlan , Wang Yanjie , Guo Qinglong , You Qidong , Wang Jinxin
Published: November 2014

Gambogic acid (GA), a special category of Garcinia xanthones, has attracted great attention owing to its striking bioactivities and unique structure. To further explore its structure–activity relationship, we prepared seven novel oxa-caged Garcinia xanthones that were for the first time varied at the C-2 position of B ring and at the C-21/22 or C-23 position of the prenyl group in the caged scaffold. Some compounds exhibited strong anti-proliferation activities in different cancer cell lines. Particularly, compound 8 showed more potent cytotoxic activity and better selectivity towards the A549 cell line than GA. Oxa-caged xanthones 8 was identified as an A549 cell apoptosis inducer through observations of morphological changes and Annexin-V/PI double-staining assay. Additionally, the structure–activity relationships of these new analogues were discussed.
Historical distribution of Sundaland’s Dipterocarp rainforests at Quaternary glacial maxima
Authors: Raes Niels , Cannon Charles H. , Hijmans Robert J. , Piessens Thomas , Saw Leng Guan , van Welzen Peter C. , Slik J. W. Ferry
Published: November 2014

Significance

The effect of glacial cycles on Southeast Asian (SEA) rainforest during the Quaternary is unresolved. Some historical evidence suggests rainforests were confined to small refugia during glacial maxima, but dynamic vegetation models suggest evergreen rainforests were widespread. Because Dipterocarpaceae dominate current SEA rainforests, their distributions closely reflect general rainforest extent. Here, we use an extensive georeferenced database of collection records for 317 Dipterocarpaceae species to model their climatic niches, based on current climatic conditions. These distribution models were then hindcast onto historical climatic conditions of the last glacial maximum. The results indicate that central Sundaland, exposed because of lower sea levels at glacial maxima, harbored suitable environmental conditions for Dipterocarpaceae and was probably covered by rainforest.
DNA topology confers sequence specificity to nonspecific architectural proteins
Authors: Wei Juan , Czapla Luke , Grosner Michael A. , Swigon David , Olson Wilma K.
Published: November 2014

Significance

The organization of long genomes in the confined spaces of a cell requires special facilitating mechanisms. A variety of architectural proteins play key roles in these processes. The bacterial heat-unstable (HU) protein helps to condense DNA by introducing sharp turns along its pathway. The protein binds in a sequence-neutral fashion, randomly distorting linear DNA when introduced in computer-simulated structures at levels comparable to those found in the cell. The natural resistance of DNA to severe deformation, however, restricts the nonspecific protein to specific loci when the molecule is covalently closed or looped by a protein. The interplay of DNA topology and protein-induced bending provides insights into ways in which gene fragments may be organized and linked to biological function.
Spontaneous regeneration of cochlear supporting cells after neonatal ablation ensures hearing in the adult mouse
Authors: Mellado Lagarde Marcia M. , Wan Guoqiang , Zhang LingLi , Gigliello Angelica R. , McInnis John J. , Zhang Yingxin , Bergles Dwight , Zuo Jian , Corfas Gabriel
Published: November 2014

Significance

The auditory sensory epithelium contains two major cell types: hair cells and supporting cells. Mammalian auditory hair cells do not regenerate after damage or loss, resulting in permanent hearing impairment. How supporting cell loss affects auditory function remains to be determined. Here, we demonstrate that inner border and inner phalangeal cells, the two types of supporting cells surrounding inner hair cells, can be replenished completely after selective ablation in the neonatal cochlea, allowing hearing to be preserved. Our findings challenge the view that mammalian auditory sensory epithelium has limited intrinsic regenerative capacity and provide previously unindetified opportunities for replacement of damaged auditory cells and restoration of hearing.
The ecology of religious beliefs
Authors: Botero Carlos A. , Gardner Beth , Kirby Kathryn R. , Bulbulia Joseph , Gavin Michael C. , Gray Russell D.
Published: November 2014

Significance

Here we show that the spatial prevalence of human societies that believe in moralizing high gods can be predicted with a high level of accuracy (91%) from historical, social, and ecological data. Using high-resolution datasets, we systematically estimate the relative effects of resource abundance, ecological risk, cultural diffusion, shared ancestry, and political complexity on the global distribution of beliefs in moralizing high gods. The methods presented in this paper provide a blueprint for how to leverage the increasing wealth of ecological, linguistic, and historical data to understand the forces that have shaped the behavior of our own species.
Stress and the dynamic genome: Steroids, epigenetics, and the transposome
Authors: Hunter Richard G. , Gagnidze Khatuna , McEwen Bruce S. , Pfaff Donald W.
Published: November 2014

Stress plays a substantial role in shaping behavior and brain function, often with lasting effects. How these lasting effects occur in the context of a fixed postmitotic neuronal genome has been an enduring question for the field. Synaptic plasticity and neurogenesis have provided some of the answers to this question, and more recently epigenetic mechanisms have come to the fore. The exploration of epigenetic mechanisms recently led us to discover that a single acute stress can regulate the expression of retrotransposons in the rat hippocampus via an epigenetic mechanism. We propose that this response may represent a genomic stress response aimed at maintaining genomic and transcriptional stability in vulnerable brain regions such as the hippocampus. This finding and those of other researchers have made clear that retrotransposons and the genomic plasticity they permit play a significant role in brain function during stress and disease. These observations also raise the possibility that the transposome might have adaptive functions at the level of both evolution and the individual organism.
Nonsensory target-dependent organization of piriform cortex
Authors: Chen Chien-Fu F. , Zou Dong-Jing , Altomare Clara G. , Xu Lu , Greer Charles A. , Firestein Stuart J.
Published: November 2014

Significance

The mammalian olfactory system is capable of detecting and discriminating a vast and diverse array of small organic molecules or odorants. Complex blends of these chemicals are finally perceived as a unified odor object—for example, a rose contains dozens of active compounds. The piriform cortex (PCX) is the largest component of the olfactory cortex and has been hypothesized to be the locus of odor object formation. However, the PCX shows a distributed odorant representation that contrasts sharply with the topographical representation typically seen in the other primary sensory cortices. In this article, we explore an alternative organizational principle for the PCX based on where neurons are sending their output, rather than where these neurons are receiving their input.
High-speed odor transduction and pulse tracking by insect olfactory receptor neurons
Authors: Szyszka Paul , Gerkin Richard C. , Galizia C. Giovanni , Smith Brian H.
Published: November 2014

Significance

How fast can animals smell? Whereas we know how fast our eyes are (in the cinema, images at 24 Hz fuse for humans, whereas our retina can resolve flickers at more than 100 Hz), olfactory perception is believed to be slow. After all, we take a sniff and later another one. Odor plumes in the air, however, can fluctuate at a millisecond time scale. Here, we show that insect olfactory receptor neurons can have response latencies shorter than 2 ms and resolve odorant fluctuations at more than 100 Hz. This high temporal resolution could facilitate odor-background segregation, and it has important implications for underlying cellular processes (transduction), ecology (odor recognition), and technology (development of fast sensors).
Putative chanzyme activity of TRPM2 cation channel is unrelated to pore gating
Authors: Tóth Balázs , Iordanov Iordan , Csanády László
Published: November 2014

Significance

Ion channels are protein pores that allow passive transmembrane ion flow. These pores are opened and closed (gated) by various cellular signals. Typically, the mechanism of gating conformational changes is an equilibrium process, but for some channels, gating is an irreversible cycle, for example, linked to an enzymatic activity. For equilibrium mechanisms, channel activity is readily modulated by energetic stabilization of closed or open states, whereas for cyclic gating, alteration of transition-state stabilities most effectively modulates activity. Transient receptor potential melastatin 2 (TRPM2), a cation channel involved in multiple physiologic and pathophysiologic processes, possesses enzymatic activity, which cleaves its activating ligand. This work addresses, and rules out, a suggested link between that catalysis and pore gating in TRPM2, classifying it among the channels that gate at equilibrium.
New insights into Eastern Beringian mortuary behavior: A terminal Pleistocene double infant burial at Upward Sun River
Authors: Potter Ben A. , Irish Joel D. , Reuther Joshua D. , McKinney Holly J.
Published: November 2014

Significance

Two interred infants with associated grave goods and a third cremated child represent the earliest known human remains from the North American subarctic, and they provide evidence for novel mortuary behaviors at the end of the last Ice Age. Two bifacial points with decorated foreshafts represent hafted projectiles, confirming earlier conclusions about Paleoindian weapon system form and function. Excellent faunal and other contextual data indicate broad-spectrum foraging behaviors.
Sample processing obscures cancer-specific alterations in leukemic transcriptomes
Authors: Dvinge Heidi , Ries Rhonda E. , Ilagan Janine O. , Stirewalt Derek L. , Meshinchi Soheil , Bradley Robert K.
Published: November 2014

Significance

An important goal of cancer biology is to identify molecular differences between normal and cancer cells. Accordingly, many large-scale initiatives to characterize both solid and liquid tumor samples with genomics technologies are currently underway. Here, we show that standard blood collection procedures cause rapid changes to the transcriptomes of hematopoietic cells. The resulting transcriptional and posttranscriptional artifacts are visible in most published leukemia genomics datasets and hinder the identification and interpretation of cancer-specific alterations.
Selective oral ROCK2 inhibitor down-regulates IL-21 and IL-17 secretion in human T cells via STAT3-dependent mechanism
Authors: Zanin-Zhorov Alexandra , Weiss Jonathan M. , Nyuydzefe Melanie S. , Chen Wei , Scher Jose U. , Mo Rigen , Depoil David , Rao Nishta , Liu Ben , Wei Jianlu , Lucas Sarah , Koslow Matthew , Roche Maria , Schueller Olivier , Weiss Sara , Poyurovsky Masha V. , Tonra James , Hippen Keli L. , Dustin Michael L. , Blazar Bruce R. , Liu Chuan-ju , Waksal Samuel D.
Published: November 2014

Significance

Rho-associated kinase 2 (ROCK2) is implicated in the regulation of proinflammatory cytokines, such as IL-17 and IL-21, and the development of autoimmunity in mice. However, the role of ROCK2 signaling pathway in regulation of immune responses in humans is still an enigma. Here we show that targeted ROCK2 inhibition down-regulates proinflammatory responses via concurrent regulation of STAT3/STAT5 phosphorylation and shifting Th17/Treg balance in human T cells with a minimal effect on the rest of the immune response. This work provides previously unidentified insights into the molecular mechanism of ROCK2-mediated modulation of the immune response in man and has profound implications for development of a selective ROCK2 inhibitor as a new therapeutic target for autoimmunity treatment.
Synergy between Piezo1 and Piezo2 channels confers high-strain mechanosensitivity to articular cartilage
Authors: Lee Whasil , Leddy Holly A. , Chen Yong , Lee Suk Hee , Zelenski Nicole A. , McNulty Amy L. , Wu Jason , Beicker Kellie N. , Coles Jeffrey , Zauscher Stefan , Grandl Jörg , Sachs Frederick , Guilak Farshid , Liedtke Wolfgang B.
Published: November 2014

Significance

Cartilage, a mechanically sensitive tissue that covers joints, is essential for vertebrate locomotion by sustaining skeletal mobility. Transduction of mechanical stimuli by cartilage cells, chondrocytes, leads to biochemical–metabolic responses. Such mechanotransduction can be beneficial for tissue maintenance when evoked by low-level mechanical stimuli, or can have health-adverse effects via cartilage-damaging high-strain mechanical stress. Thus, high-strain mechanotransduction by cartilage mechanotrauma is relevant for the pathogenesis of osteoarthritis. Molecular mechanisms of high-strain mechanotransduction of chondrocytes have been elusive. Here we identify Piezo1 and Piezo2 mechanosensitive ion channels in chondrocytes as transduction channels for high-strain mechanical stress. We verify their functional link to the cytoskeleton as important for their concerted function and offer a remedial strategy by application of a Piezo1/2 blocking peptide, GsMTx4, from tarantula venom.
H19 long noncoding RNA controls the mRNA decay promoting function of KSRP
Authors: Giovarelli Matteo , Bucci Gabriele , Ramos Andres , Bordo Domenico , Wilusz Carol J. , Chen Ching-Yi , Puppo Margherita , Briata Paola , Gherzi Roberto
Published: November 2014

Significance

Long noncoding RNAs (lncRNAs) provide new layers of complexity to gene expression control. We report on the functional consequences of the interaction between the ssRNA-binding protein K homology-type splicing regulatory protein (KSRP) with H19 lncRNA (H19) in multipotent C2C12 cells able to differentiate in culture toward myotubes in response to activation of cell signaling pathways, including AKT. KSRP and H19 interact exclusively in undifferentiated C2C12 cells, and this favors KSRP’s ability to interact with the promyogenic transcript myogenin and to favor its degradation. AKT activation induces KSRP dissociation from H19 and, as a consequence, from myogenin mRNA that is stabilized. H19 likely acts as a scaffold that favors KSRP-mediated degradation of myogenin to contribute to the maintenance of the undifferentiated state of C2C12 cells.
Reversals of national fortune, and social science methodologies
Authors: Diamond Jared
Published: November 2014

Among non-European regions colonized by Europeans, regions that were relatively richer five centuries ago (like Mexico, Peru, and India) tend to be poorer today, while regions that originally were relatively poorer (like the United States, Chile, and Australia) tend now to be richer. Acemoglu, Johnson, and Robinson (abbreviated AJR) established the generality of this reversal of fortune. Chanda, Cook, and Putterman (abbreviated CCP) have now reanalyzed it, taking as a unit of analysis populations rather than geographic regions. That is, India's population was Indian 500 y ago and is still overwhelmingly Indian today, whereas the United States' population was Native American 500 years ago but is overwhelmingly Old World (especially European) today. Reversals of fortune disappeared when CCP analyzed populations rather than geographic regions: for instance, the geographic region of the modern United States has become relatively richer since AD 1500, but the predominantly European population now occupying the United States was already relatively rich in AD 1500. Evidently, European colonists carried ingredients of wealth with them. I discuss the biological and cultural baggage transported by European immigrants and associated with wealth. Among that baggage, AJR emphasize institutions, CCP emphasize social capital, and I identify many different elements only loosely coupled to each other. This paper discusses the problem, especially acute in the social sciences, of “operationalizing” intuitive concepts (such as mass, temperature, wealth, and innovation) so that they can be measured. Basic concepts tend to be harder to define, operationalize, and measure in the social sciences than in the laboratory sciences.
Influenza A virus nucleoprotein selectively decreases neuraminidase gene-segment packaging while enhancing viral fitness and transmissibility
Authors: Brooke Christopher B. , Ince William L. , Wei Jiajie , Bennink Jack R. , Yewdell Jonathan W.
Published: November 2014

Significance

The influenza A virus (IAV) genome consists of eight unique RNA segments, each of which is required for productive infection. IAV is believed to copackage its individual gene segments into virions with nearly perfect efficiency to maximize replicative potential. We contradict this view by demonstrating that decreased gene packaging can be associated with increased in vivo fitness and transmissibility. Incomplete packaging likely is facilitated by the extensive coinfection that we demonstrate in vivo, which promotes complementation and explains the frequent reassortment reported previously. We also reveal roles for the viral nucleoprotein in modulating glycoprotein function and gene packaging during host adaptation. These findings necessitate a major shift in how we think about the infectious and evolutionary potential of IAV populations.
Synchronized renal tubular cell death involves ferroptosis
Authors: Linkermann Andreas , Skouta Rachid , Himmerkus Nina , Mulay Shrikant R. , Dewitz Christin , De Zen Federica , Prokai Agnes , Zuchtriegel Gabriele , Krombach Fritz , Welz Patrick-Simon , Weinlich Ricardo , Vanden Berghe Tom , Vandenabeele Peter , Pasparakis Manolis , Bleich Markus , Weinberg Joel M. , Reichel Christoph A. , Bräsen Jan Hinrich , Kunzendorf Ulrich , Anders Hans-Joachim , Stockwell Brent R. , Green Douglas R. , Krautwald Stefan
Published: November 2014

Significance

Cell death by regulated necrosis causes tremendous tissue damage in a wide variety of diseases, including myocardial infarction, stroke, sepsis, and ischemia–reperfusion injury upon solid organ transplantation. Here, we demonstrate that an iron-dependent form of regulated necrosis, referred to as ferroptosis, mediates regulated necrosis and synchronized death of functional units in diverse organs upon ischemia and other stimuli, thereby triggering a detrimental immune response. We developed a novel third-generation inhibitor of ferroptosis that is the first compound in this class that is stable in plasma and liver microsomes and that demonstrates high efficacy when supplied alone or in combination therapy.
Action video game play facilitates the development of better perceptual templates
Authors: Bejjanki Vikranth R. , Zhang Ruyuan , Li Renjie , Pouget Alexandre , Green C. Shawn , Lu Zhong-Lin , Bavelier Daphne
Published: November 2014

Significance

Recent advances in the field of learning have identified improvement of perceptual templates as a key mechanism underlying training-induced performance enhancements. Here, using a combination of psychophysics and neural modeling, we demonstrate that this mechanism—improved learning of perceptual templates—is also engaged after action video game play. Habitual action gamers or individuals trained to play action games demonstrate perceptual templates better tuned to the task and stimulus at hand than control groups, a difference shown to emerge as learning proceeds. This work further illustrates the importance of the development of improved perceptual templates as a mechanism mediating training and transfer effects and provides a novel account for the surprisingly broad transfer of performance enhancements noted after action game play.
Selective degeneration of a physiological subtype of spinal motor neuron in mice with SOD1-linked ALS
Authors: Hadzipasic Muhamed , Tahvildari Babak , Nagy Maria , Bian Minjuan , Horwich Arthur L. , McCormick David A.
Published: November 2014

Significance

We describe a method that allows, for the first time to our knowledge, the preparation of viable acute spinal cord slices from adult mice, enabling patch-clamp recording from fluorescent motor neurons. From electrophysiological parameters, four subtypes of motor neurons were identified. Two fast firing subtypes innervated fast twitch muscle, whereas the two slow firing subtypes innervated slow twitch muscle. In superoxide dismutase 1-linked amyotrophic lateral sclerosis mice, the same four firing types were observed before the onset of symptoms, but the fastest firing type was lost after symptoms developed.
Pharmacological protection of retinal pigmented epithelial cells by sulindac involves PPAR-α
Authors: Sur Arunodoy , Kesaraju Shailaja , Prentice Howard , Ayyanathan Kasirajan , Baronas-Lowell Diane , Zhu Danhong , Hinton David R. , Blanks Janet , Weissbach Herbert
Published: November 2014

Significance

Oxidative stress-induced damage to retinal pigmented epithelial (RPE) cells is implicated in the progression of age-related macular degeneration (AMD), which is one of the primary causes of vision loss in the elderly. The present studies show that sulindac, a known nonsteroidal antiinflammatory drug, can protect an established RPE cell line, low-passage human fetal RPE, and polarized primary human fetal RPE cells against oxidative damage. The results with the RPE cell line indicate that the protective response is similar to that seen with ischemic preconditioning. Our results suggest that preventing oxidative damage in RPE cells by this drug-induced protective mechanism could be an inexpensive and relatively nontoxic therapeutic approach for AMD treatment.
Single mutations in
sasA
enable a simpler Δ
cikA
gene network architecture with equivalent circadian properties
Authors: Shultzaberger Ryan K. , Boyd Joseph S. , Katsuki Takeo , Golden Susan S. , Greenspan Ralph J.
Published: November 2014

Significance

Complex cellular phenotypes are dependent upon a large underlying network of genes. Determining the number of interacting genes, the nature of their interactions, and the robustness of their encompassing network to cellular and genomic perturbations is important for understanding how genotype determines phenotype. Here, we approached these questions in the cyanobacterial circadian gene network by knocking out circadian input kinase A (
cikA
), a gene involved in synchronizing and relaying temporal signals within the cell, and screening for second-site suppressor mutations that rescue the severely altered
cikA-
null circadian phenotype. We identified two independent mutations in
sasA
(
Synechococcus
adaptive sensor A), a known clock-associated gene, that restore normal rhythms. These results change our conception of the circadian gene network architecture and show how easily the network can adapt to severe perturbations.
(Non-)signalling of coherence structures in English learner writing
Authors: Schiftner Barbara
Published: November 2014

This study explores different realisations of discourse relations in a corpus of

English learner writing. A sample of 30 essays produced by upper intermediate

learners of English (mean age: 23) is subjected to a multi-method analysis

incorporating (1) global coherence ratings, (2) rhetorical structure analysis

(RST), and (3) features at the linguistic surface level. The focus is on explicit

signalling vs. implicitness of discourse relations in essays rated high vs. low in

coherence. The results show differences in the type of connectives used in highrated

vs. low-rated texts as well as in the use of connectives to signal relations at

higher and lower levels of the discourse structure.