bluuebunny/crossref_metadata_2025 huggingface dataset:
Two high accuracy digital integrators for Rogowski current transducers
Authors: Luo Pan-dian , Li Hong-bin , Li Zhen-hua
Published: January 2014

The Rogowski current transducers have been widely used in AC current measurement, but their accuracy is mainly subject to the analog integrators, which have typical problems such as poor long-term stability and being susceptible to environmental conditions. The digital integrators can be another choice, but they cannot obtain a stable and accurate output for the reason that the DC component in original signal can be accumulated, which will lead to output DC drift. Unknown initial conditions can also result in integral output DC offset. This paper proposes two improved digital integrators used in Rogowski current transducers instead of traditional analog integrators for high measuring accuracy. A proportional-integral-derivative (PID) feedback controller and an attenuation coefficient have been applied in improving the Al-Alaoui integrator to change its DC response and get an ideal frequency response. For the special design in the field of digital signal processing, the improved digital integrators have better performance than analog integrators. Simulation models are built for the purpose of verification and comparison. The experiments prove that the designed integrators can achieve higher accuracy than analog integrators in steady-state response, transient-state response, and temperature changing condition.
Seleno groups control the energy-level alignment between conjugated organic molecules and metals
Authors: Niederhausen Jens , Duhm Steffen , Heimel Georg , Bürker Christoph , Xin Qian , Wilke Andreas , Vollmer Antje , Schreiber Frank , Kera Satoshi , Rabe Jürgen P. , Ueno Nobuo , Koch Norbert
Published: January 2014

The charge injection from metallic electrodes into hole transporting layers of organic devices often suffers from deviations from vacuum-level alignment at the interface. Even for weakly interacting cases, Pauli repulsion causes an interface dipole between the metal and conjugated organic molecules (COMs) (so called “push-back” or “cushion” effect), which leads notoriously to an increase of the hole injection barrier. On the other hand, for chalcogenol self assembled monolayers (SAMs) on metal surfaces, chemisorption via the formation of chalcogen-metal bonds is commonly observed. In these cases, the energy-level alignment is governed by chalcogen-derived interface states in the vicinity of the metal Fermi-level. In this work, we present X-ray and ultraviolet photoelectron spectroscopy data that demonstrate that the interfacial energy-level alignment mechanism found for chalcogenol SAMs also applies to seleno-functionalized COMs. This can be exploited to mitigate the push-back effect at metal contacts, notably also when COMs with low ionization energies are employed, permitting exceedingly low hole injection barriers, as shown here for the interfaces of tetraseleno-tetracene with Au(111), Ag(111), and Cu(111).
Microwave power absorption of magnetic composites filled with surface coated Fe-Al-Si flakes
Authors: Lee Joonsik , Ho Cho Sang , Yoon Sanghoon , Hyeon Kim Ki
Published: January 2014

The Al2O3 coated Fe-Al-Si flakes were employed as a magnetic filler in 150 μm-thick dielectric matrix. The saturation magnetizations of the coated Fe-Al-Si flakes were decreased down to 98 emu/g with the increment of the coating thickness (170 nm, 250 nm, 350 nm) in comparison with that of uncoated Fe-Al-Si flakes (130 emu/g). The power absorptions for Al2O3 coated Fe-Al-Si flakes composites were decreased from 62.7% to 57.4% (at 5 GHz) with the increment of coating thickness in comparison with that of uncoated Fe-Al-Si flakes composite (80% at 5 GHz). The thermal conductivities of Al2O3 coated composites were increased up to 0.249 W/m K in comparison with that of uncoated composite of 0.096 W/m K.
Ferromagnetic resonance study of eightfold artificial ferromagnetic quasicrystals
Authors: Bhat V. S. , Sklenar J. , Farmer B. , Woods J. , Ketterson J. B. , Hastings J. T. , De Long L. E.
Published: January 2014

We have performed broadband (10 MHz–18 GHz) and narrowband (9.7 GHz) ferromagnetic resonance (FMR) measurements on permalloy thin films patterned with quasiperiodic Ammann tilings having eightfold rotational symmetry. We observed highly reproducible mode structures in the low-frequency, hysteretic regime in which domain walls and unsaturated magnetization textures exist. A minimum of 10 robust modes were observed in patterned samples, compared to the single uniform mode observed in unpatterned permalloy films. The field dependence and approximate eightfold rotational symmetry of the FMR spectra are in good agreement with micromagnetic simulations that confirm the importance of patterning for controlling static and dynamic magnetic response.
Coupling mid-infrared light from a photonic crystal waveguide to metallic transmission lines
Authors: Blanco-Redondo Andrea , Sarriugarte Paulo , Garcia-Adeva Angel , Zubia Joseba , Hillenbrand Rainer
Published: January 2014

We propose and theoretically study a hybrid structure consisting of a photonic crystal waveguide (PhC-wg) and a two-wire metallic transmission line (TL), engineered for efficient transfer of mid-infrared (mid-IR) light between them. An efficiency of 32% is obtained for the coupling from the transverse magnetic (TM) photonic mode to the symmetric mode of the TL, with a predicted intensity enhancement factor of 53 at the transmission line surface. The strong coupling is explained by the small phase velocity mismatch and sufficient spatial overlapping between the modes. This hybrid structure could find applications in highly integrated mid-IR photonic-plasmonic devices for biological and gas sensing, among others.
Equivalences of the multi-indexed orthogonal polynomials
Authors: Odake Satoru
Published: January 2014

Multi-indexed orthogonal polynomials describe eigenfunctions of exactly solvable shape-invariant quantum mechanical systems in one dimension obtained by the method of virtual states deletion. Multi-indexed orthogonal polynomials are labeled by a set of degrees of polynomial parts of virtual state wavefunctions. For multi-indexed orthogonal polynomials of Laguerre, Jacobi, Wilson, and Askey-Wilson types, two different index sets may give equivalent multi-indexed orthogonal polynomials. We clarify these equivalences. Multi-indexed orthogonal polynomials with both type I and II indices are proportional to those of type I indices only (or type II indices only) with shifted parameters.
Low energy C+ ion embedment induced structural disorder in L1 FePt
Authors: Kundu Shreya , Rismani-Yazdi Ehsan , Saifullah M. S. M. , Ru Tan Hui , Yang Hyunsoo , Bhatia C. S.
Published: January 2014

Shallow embedding of C+ ions (<2 nm) into commercial CoCrPt-based magnetic media using the filtered cathodic vacuum arc technique improves its anti-oxidation and anti-wear properties which are comparable to the conventionally used thicker carbon overcoats of ∼3 nm. The next generation L10 FePt media subjected to low energy embedment of C+ ions have the potential to provide reduced magnetic spacing along with smaller and thermally stable grains, which is pivotal for achieving areal densities beyond 1 Tb/in.2 However, the impact of low energy C+ ions embedding on the magnetics of FePt media is not known. Here, the magnetic properties of L10 FePt, post-shallow C+ ion embedment at 350 eV, were investigated. It was observed that bombardment of C+ ions in the 5 nm thick FePt films produced a monumental reduction of ∼86% in the out-of-plane coercivity value. Increasing the FePt film thickness did not significantly suppress the impact of these C+ ions on the media. Structural and elemental analyses attributed this alteration caused in the magnetic properties of the well-ordered FePt films to the penetration of >2 nm by the C+ ions into the FePt film. The media's crystallography with respect to the size and direction of the incoming ions has emerged to be accountable for the deeper distribution of the C+ ions and the associated widespread cascade damages within the magnetic layer. The consequences of low energy C+ ions embedding to attain high storage densities using high anisotropy L10 FePt media are discussed.
Precise determination of phonon constants in lead-free monoclinic (K0.5Na0.5)NbO3 single crystals
Authors: Asif Rafiq Muhammad , Supancic Peter , Elisabete Costa M. , Vilarinho Paula M. , Deluca Marco
Published: January 2014

A polarized Raman analysis of ferroelectric (K0.5Na0.5)NbO3 (KNN) single crystals is presented. The Raman modes of KNN single crystals are assigned to the monoclinic symmetry. Angular-dependent intensities of A′, A″, and mixed A′ + A″ phonons have been theoretically calculated and compared with the experimental data, allowing the precise determination of the Raman tensor coefficients for (non-leaking) modes in single-domain monoclinic KNN. This study is the basis for non-destructive assessments of domain distribution by Raman spectroscopy in KNN-based lead-free ferroelectrics.
Dielectric relaxation in ionic liquids: Role of ion-ion and ion-dipole interactions, and effects of heterogeneity
Authors: Daschakraborty Snehasis , Biswas Ranjit
Published: January 2014

A semi-molecular theory for studying the dielectric relaxation (DR) dynamics in ionic liquids (ILs) has been developed here. The theory predicts triphasic relaxation of the generalized orientational correlation function in the collective limit. Relaxation process involves contributions from dipole-dipole, ion-dipole, and ion-ion interactions. While the dipole-dipole and ion-ion interactions dictate the predicted three relaxation time constants, the relaxation amplitudes are determined by dipole-dipole, ion-dipole, and ion-ion interactions. The ion-ion interaction produces a time constant in the range of 5-1000μs which parallels with the conductivity dominated dielectric loss peak observed in broadband dielectric measurements of ILs. Analytical expressions for two time constants originating from dipolar interactions in ILs match exactly with those derived earlier for dipolar solvents. The theory explores relations among single particle rotational time, collective rotational time, and DR time for ILs. Use of molecular volume for the rotating dipolar ion of a given IL leads to a predicted DR time constant much larger than the slowest DR time constant measured in experiments. In contrast, similar consideration for dipolar liquids produces semi-quantitative agreement between theory and experiments. This difference between ILs and common dipolar solvents has been understood in terms of extremely low effective rotational volume of dipolar ion, argued to arise from medium heterogeneity. Effective rotational volumes predicted by the present theory for ILs are in general agreement with estimates from experimental DR data and simulation results. Calculations at higher temperatures predict faster relaxation time constants reducing the difference between theory and experiments.
Trapping on demand: External regulation of excitation energy transfer in a photoswitchable smart matrix
Authors: Schmidt R. , Pärs M. , Weller T. , Thelakkat M. , Köhler J.
Published: January 2014

A thin film of polystyrene has been doped with small amounts of dithienylcyclopentene (DCP) based molecular switches and perylene bisimide (PBI) chromophores to obtain a photoswitchable smart matrix. The photochromic DCP can be converted by light between two bistable conformations and thereby changes the energetic position of its lowest excited singlet state. We exploit this feature to regulate the transfer of excitation energy between PBI and DCP as a function of the externally controllable illumination conditions in such a blend.
Insights into ultraviolet-induced electrical degradation of thermally grown SiO2/4H-SiC(0001) interface
Authors: Ikeguchi Daisuke , Hosoi Takuji , Nakano Yuki , Nakamura Takashi , Shimura Takayoshi , Watanabe Heiji
Published: January 2014

The harmful impact of ultraviolet (UV) light irradiation on thermally grown SiO2/4H-SiC structures was investigated by means of electrical measurements of metal-oxide-semiconductor (MOS) capacitors. Unlike Si-based MOS devices, significant electrical degradation, such as positive flatband voltage (VFB) shift and hysteresis in the capacitance-voltage (C-V) curves of SiC-MOS capacitors was induced by UV irradiation with a low-pressure mercury lamp. The interfacial fixed charge density increased with UV-irradiation (22.6 mW/cm2 for 16 h) to 1.7 × 1012 cm−2, which was an order of magnitude larger than that of the as-grown SiO2/SiC interface. A detailed study based on single wavelength solid-state UV lasers revealed that there was a threshold photon energy at around 5 eV and a moderate dependence of UV-induced degradation on temperature. These experimental findings imply that pre-existing inactive defects accumulated at the thermally grown SiO2/SiC interface were transformed to active carrier traps with high-energy UV irradiation through transparent SiO2 layers.
Single and two-photon fluorescence control of Er3+ ions by phase-shaped femtosecond laser pulse
Authors: Zhang Shian , Xu Shuwu , Ding Jingxin , Lu Chenhui , Jia Tianqing , Qiu Jianrong , Sun Zhenrong
Published: January 2014

We experimentally demonstrate the control of the single and two-photon fluorescence (SPF and TPF) in Er3+ ions by shaping the femtosecond laser pulse with a π or square phase modulation. With the low laser intensity (8.4 × 1010 W/cm2), SPF keeps a constant while TPF is effectively suppressed by the two control schemes. With the high laser intensity (1.2 × 1013 W/cm2), both SPF and TPF are simultaneously enhanced or suppressed by the π phase modulation, and SPF is enhanced while TPF is effectively suppressed by the square phase modulation. The up/down-conversion fluorescence enhancement, suppression, or tuning by the optical control method can greatly expand its applications in various related fields.
Investigation of buffer traps in AlGaN/GaN-on-Si devices by thermally stimulated current spectroscopy and back-gating measurement
Authors: Yang Shu , Zhou Chunhua , Jiang Qimeng , Lu Jianbiao , Huang Baoling , Chen Kevin J.
Published: January 2014

Thermally stimulated current (TSC) spectroscopy and high-voltage back-gating measurement are utilized to study GaN buffer traps specific to AlGaN/GaN lateral heterojunction structures grown on a low-resistivity Si substrate. Three dominating deep-level traps in GaN buffer with activation energies of ΔET1 ∼ 0.54 eV, ΔET2 ∼ 0.65 eV, and ΔET3 ∼ 0.75 eV are extracted from TSC spectroscopy in a vertical GaN-on-Si structure. High back-gate bias applied to the Si substrate could influence the drain current in an AlGaN/GaN-on-Si high-electron-mobility transistor in a way that cannot be explained with a simple field-effect model. By correlating the trap states identified in TSC with the back-gating measurement results, it is proposed that the ionization/deionization of both donor and acceptor traps are responsible for the generation of buffer space charges, which impose additional modulation to the 2DEG channel.
Quantum pumping of valley current in strain engineered graphene
Authors: Wang Jing , Chan K. S. , Lin Zijing
Published: January 2014

We studied the generation of valley dependent current by adiabatic quantum pumping in monolayer graphene in the presence of electric potential barriers, ferromagnetic field and strain. The pumped currents in the two valleys have same magnitudes and opposite directions; thus, a pure valley current is generated. The oscillation of the pumped pure valley current is determined by the Fabry-Perot resonances formed in the structure. In our calculation, the pumped pure valley current can be as high as 50 nA, which is measurable using present technologies. The proposed device is useful for the development of graphene valleytronic devices.
Bauschinger effect in thin metal films: Discrete dislocation dynamics study
Authors: Davoudi Kamyar M. , Nicola Lucia , Vlassak Joost J.
Published: January 2014

The effects of dislocation climb on plastic deformation during loading and unloading are studied using a two-dimensional discrete dislocation dynamics model. Simulations are performed for polycrystalline thin films passivated on both surfaces. Dislocation climb lowers the overall level of the stress inside thin films and reduces the work hardening rate. Climb decreases the density of dislocations in pile-ups and reduces back stresses. These factors result in a smaller Bauschinger effect on unloading compared to simulations without climb. As dislocations continue to climb at the onset of unloading and the dislocation density continues to increase, the initial unloading slope increases with decreasing unloading rate. Because climb disperses dislocations, fewer dislocations are annihilated during unloading, leading to a higher dislocation density at the end of the unloading step.
Study of gain and photoresponse characteristics for back-illuminated separate absorption and multiplication GaN avalanche photodiodes
Authors: Wang Xiaodong , Hu Weida , Pan Ming , Hou Liwei , Xie Wei , Xu Jintong , Li Xiangyang , Chen Xiaoshuang , Lu Wei
Published: January 2014

The gain and photoresponse characteristics have been numerically studied for back-illuminated separate absorption and multiplication (SAM) GaN avalanche photodiodes (APDs). The parameters of fundamental models are calibrated by simultaneously comparing the simulated dark and light current characteristics with the experimental results. Effects of environmental temperatures and device dimensions on gain characteristics have been investigated, and a method to achieve the optimum thickness of charge layer is obtained. The dependence of gain characteristics and breakdown voltage on the doping concentration of the charge layer is also studied in detail to get the optimal charge layer. The bias-dependent spectral responsivity and quantum efficiency are then presented to study the photoresponse mechanisms inside SAM GaN APDs. It is found the responsivity peak red-shifts at first due to the Franz-Keldysh effect and then blue-shifts due to the reach-through effect of the absorption layer. Finally, a new SAM GaN/AlGaN heterojunction APD structure is proposed for optimizing SAM GaN APDs.
A low-power magnetic-field-assisted plasma jet generated by dielectric-barrier discharge enhanced direct-current glow discharge at atmospheric pressure
Authors: Jiang Weiman , Tang Jie , Wang Yishan , Zhao Wei , Duan Yixiang
Published: January 2014

A magnetic field is introduced to the dielectric-barrier discharge enhanced direct-current glow discharge for efficient plasma generation, with the discharge power of 2.7 W and total energy consumption reduced to 34% of the original. By spatially examining the emission spectra and plasma temperature, it is found that their peaks shift from edges to the center and the negative and anode glows merge into the positive column and disappear, accompanied by improvement of uniformity and chemical activity of the enlarged plasma. This lies in the enhancement of ionization in the curved and lengthened electron path and the dispersion of discharge domains.
Phosphorus-doping-induced rectifying behavior in armchair graphene nanoribbons devices
Authors: Zhou Yuhong , Zhang Jianbing , Zhang Daoli , Ye Cong , Miao Xiangshui
Published: January 2014

Based on nonequilibrium Green's functions in combination with density-functions theory, the transport properties of armchair graphene nanoribbon (AGNR) devices were investigated, in which one lead is undoped armchair graphene nanoribbons, and the other is phosphorus (P)-doped armchair graphene nanoribbons. The results manifest that there is the rectification behavior with large rectifying ratio in the AGNR devices and the rectification characteristics can be modulated by changing the width of the graphene nanoribbons. On the contrary, for the same width of the graphene nanoribbons, the position of P dopant has little or no effect on changing I-V characteristics.
Polymer piezoelectric energy harvesters for low wind speed
Authors: Jun Li Dong , Hong Seungbum , Gu Shiyuan , Choi YoonYoung , Nakhmanson Serge , Heinonen Olle , Karpeev Dmitry , No Kwangsoo
Published: January 2014

We fabricated polymer piezoelectric energy harvesters (PEHs) that can generate electric power at wind speed of less than 4.7 m/s due to their high sensitivity to wind. In order to optimize their operating conditions, we evaluated three distinct PEH operation modes under the boundary conditions of single-side clamping. We found that a PEH connected to an external load of 120 kΩ shows the largest output power of 0.98 μW at 3.9 m/s, with wind incident on its side (mode I). We attribute this result to large bending and torsion involved in this operation mode.
Ion-induced dynamical change of supercurrent flow in superconducting strip ion detectors with parallel configuration
Authors: Zen Nobuyuki , Shiki Shigetomo , Ukibe Masahiro , Koike Masaki , Ohkubo Masataka
Published: January 2014

Superconducting strip ion detectors are promising for realizing ideal ion detection in time-of-flight mass spectrometry. To realize large sensitive area for practical use, parallel configurations of superconducting strips are mandatory. In a previous parallel configuration design, however, we have found that a non-negligible number of ion impact events were lost because a large number of output current pulses for single ions were fatally small. An alternative parallel configuration design has solved this critical problem. It has been revealed that ion impact events induce dynamical change of bias current flow among parallel superconducting strips. Furthermore, output current distributions of larger bias current have shown another dynamical phenomenon: multi-strip switching triggered by single ion impact.
Study of the temperature dependent immuno-reaction kinetics for the bio-functionalized magnetic nanoparticle assay of bio-markers of colorectal cancer
Authors: Yang S. Y. , Chang J. F. , Chen T. C. , Yang C. C. , Ho C. S.
Published: January 2014

By conjugating antibodies on magnetic nanoparticles, target antigens can be quantitatively detected by measuring the magnetic signals of the magnetic nanoparticles due to their association with target antigens. This method of detection is called magnetically labeled immunoassay. The assay characteristics of magnetically labeled immunoassay have been reported widely. However, the immuno-reaction kinetics of magnetically labeled immunoassay has not been studied. In this work, the reaction rates between magnetic nanoparticles and target antigens are measured at various temperatures. It is found that the temperature dependent reaction rate obeys Arrhenius's equation, which shows the collision frequency and activation energy for the immuno-reaction between antibody-functionalized magnetic nanoparticles and target antigens. The carcinoembryonic antigen, which is a regular blood bio-marker for in-vitro diagnosis of colorectal cancer, is used as a target antigen for the example.
Structural details of Early Devonian dipnoans
Authors: Campbell K. S. W. , Wragg Sharyn
Published: January 2014

The evolution of the Dipnoi is displayed in the Early Devonian in south-eastern Australia. The main points at issue are as follows. (a) The development of the tubercles in the two-layered rostral region of the skull. (b) The nerves ophthalmicus profundus V and opthalmicus superficialis VII, and their sensory function. (c) The abundance of fine tubules between these tubules and the dermal plates of the skull roof extending posterior to the pineal region. (d) The massive pterygoids and the restriction of the parasphenoids to a small posterior position. (e) The position of the bucco-hypophysial canal running to a buccal opening near the posterior of the pterygoids. (f) The presence of a rostral region, misnamed the ‘dentary’, in the mandible, with abundant tubercles serving sensory systems. (g) The presence of an anterior furrow in the mandible. Dipnoans form a separate evolutionary lineage that began in the Early Devonian. Diabolepis and associated genera are not Dipnomorphs, but are isolated genera formed by gene regulation in the early Devonian.
Perfect genetic correlation between number of offspring and grandoffspring in an industrialized human population
Authors: Zietsch Brendan P. , Kuja-Halkola Ralf , Walum Hasse , Verweij Karin J. H.
Published: January 2014

Significance

Reproductive success (offspring quantity) is widely used as a measure of fitness (genetic contribution to future generations). Accurate predictions of the direction and magnitude of evolutionary change using this measure depend on the untested assumption that the genes influencing number of offspring are the same as those influencing number of grandoffspring. Using a population sample of identical and nonidentical Swedish twins and their descendants, we show that the genetic influences on number of offspring and grandoffspring are identical, supporting the use of reproductive success as a measure of fitness in comparable human populations.
Molecular insight into bacterial cleavage of oceanic dimethylsulfoniopropionate into dimethyl sulfide
Authors: Li Chun-Yang , Wei Tian-Di , Zhang Sheng-Hui , Chen Xiu-Lan , Gao Xiang , Wang Peng , Xie Bin-Bin , Su Hai-Nan , Qin Qi-Long , Zhang Xi-Ying , Yu Juan , Zhang Hong-Hai , Zhou Bai-Cheng , Yang Gui-Peng , Zhang Yu-Zhong
Published: January 2014

Significance

DMS is an important participant in the global sulfur and carbon cycles. DMS oxidation products cause the formation of cloud condensation nuclei and hence may influence weather and climate. DMS is produced through the cleavage of dimethylsulfoniopropionate (DMSP) mainly by marine bacterial DMSP lyases. The molecular mechanism of DMSP cleavage to generate DMS remains unclear. In this study, the crystal structure of DddQ, a DMSP lyase, was solved, and detailed biochemical and structural analyses were performed. Our results also provided a foremost insight into the catalytic mechanism of the DMSP cleavage reaction. This study offers a better understanding of how marine bacteria cleave DMSP to generate the climatically important gas DMS.
Genetic drift opposes mutualism during spatial population expansion
Authors: Müller Melanie J. I. , Neugeboren Beverly I. , Nelson David R. , Murray Andrew W.
Published: January 2014

Significance

Species expand from where they evolved or migrate in response to climate change. Such spatial expansions can impede mutualistic interactions (beneficial for both partners). Mutualism selects for species coexistence and genetic diversity, but spatial expansion creates regions of low diversity due to repeated founder effects. We show both theoretically and experimentally, using the colony expansion of cross-feeding yeast as a model system, that a critical mutualistic strength is required to “survive” spatial expansions. This constraint may have shaped the evolution of mutualisms, allowing only the spread of very beneficial mutualisms (e.g., the invasion of land by plants with mycorrhizal fungi and flowering plants with pollen-dispersing insects) or leading to additional mechanisms for coordinated partner dispersal (e.g., endosymbionts and lichens).
Environmental enrichment extends ocular dominance plasticity into adulthood and protects from stroke-induced impairments of plasticity
Authors: Greifzu Franziska , Pielecka-Fortuna Justyna , Kalogeraki Evgenia , Krempler Katja , Favaro Plinio D. , Schlüter Oliver M. , Löwel Siegrid
Published: January 2014

Significance

Experimental animals are usually raised in small, so-called standard cages, depriving them of numerous natural stimuli. We show that raising mice in an enriched environment, allowing enhanced physical, social, and cognitive stimulation, preserved a juvenile brain into adulthood. Enrichment also rejuvenated the visual cortex after extended periods of standard cage rearing and protected adult mice from stroke-induced impairments of cortical plasticity. Because the local inhibitory tone in the visual cortex of adult enriched mice was not only significantly reduced compared with nonenriched animals but at juvenile levels, the plasticity-promoting effect of enrichment is most likely mediated by preserving low juvenile levels of inhibition into adulthood and thereby, extending sensitive phases of enhanced neuronal plasticity into an older age.
Species interactions and the structure of complex communication networks
Authors: Tobias Joseph A. , Planqué Robert , Cram Dominic L. , Seddon Nathalie
Published: January 2014

Significance

Social signals used in multispecies choruses are generally assumed to be partitioned across temporal, spatial, or design axes to minimize the costs of misidentification. In contrast, we show that Amazonian bird species signaling in temporal and spatial proximity use acoustic signals that are more similar in design than expected by chance. We also show evidence that this pattern emerges because phylogenetically conserved (or potentially convergent) signals mediate interspecific competition among species with similar ecological niches. Together, these results suggest that acoustic choruses can be fundamentally organized by social communication extending beyond species boundaries and that such communication networks are inherently clustered by increased stereotypy and synchrony among species.
Tuberculosis vaccine with high predicted population coverage and compatibility with modern diagnostics
Authors: Knudsen Niels Peter H. , Nørskov-Lauritsen Sara , Dolganov Gregory M. , Schoolnik Gary K. , Lindenstrøm Thomas , Andersen Peter , Agger Else Marie , Aagaard Claus
Published: January 2014

Significance

Despite the availability of a number of antibiotics and extensive use of the live vaccine bacillus Calmette–Guérin, tuberculosis remains a major global health problem. Antigen 85 is by far the most popular antigen in current clinical trials vaccines. However, a recent failure of a virus-based vaccine expressing antigen 85 emphasizes the continued need for identifying antigens, testing their protective efficacy, and learning from this process to develop a protective vaccine. The H65 vaccine demonstrates that it is possible to develop antigen 85-free vaccines that does not interfere with current immune-based diagnostic assays.
MAB4-induced auxin sink generates local auxin gradients in
Arabidopsis
organ formation
Authors: Furutani Masahiko , Nakano Yasukazu , Tasaka Masao
Published: January 2014

Significance

The dynamic auxin transport driven by the auxin efflux carrier PIN-FORMED1 (PIN1) is the key element in organ formation at the shoot apical meristem. Auxin transport during organ formation consists of two distinct types: the convergence of auxin flow at the organ initiation site and the following auxin sink. Our results show that NONPHOTOTROPIC HYPOCOTYL 3-like proteins establish auxin sink, but not auxin convergence, through the control of PIN1 localization. Our study uncovers the molecular mechanism involved in auxin sink and to show its importance in organ development. Besides, we propose a model for polar auxin transport during organ formation, which has the potential to describe on a molecular level the auxin canalization hypothesis.
Engineered temperature compensation in a synthetic genetic clock
Authors: Hussain Faiza , Gupta Chinmaya , Hirning Andrew J. , Ott William , Matthews Kathleen S. , Josić Krešimir , Bennett Matthew R.
Published: January 2014

Significance

Synthetic gene circuits are often fragile, as perturbations to cellular conditions frequently alter their behavior. This lack of robustness limits the utility of engineered gene circuits and hinders advances in synthetic biology. Here, we demonstrate that environmental sensitivity can be reduced by simultaneously engineering circuits at the protein and network levels. Specifically, we designed and constructed a synthetic genetic clock that exhibits temperature compensation—the clock’s period does not depend on temperature. This feature is nontrivial since biochemical reactions speed up with increasing temperature. To accomplish this goal, we engineered thermal-inducibility into the clock’s regulatory structure. Computational modeling predicted and experiments confirmed that this thermal-inducibility results in a clock with a stable period across a large range of temperatures.
TRAIL-coated leukocytes that kill cancer cells in the circulation
Authors: Mitchell Michael J. , Wayne Elizabeth , Rana Kuldeepsinh , Schaffer Chris B. , King Michael R.
Published: January 2014

Significance

This paper describes a unique approach to target and kill cancer cells in the bloodstream, in which the extensive surface area of circulating leukocytes is used to display the cancer-specific TNF-related apoptosis inducing ligand (TRAIL) and E-selectin adhesion receptor to the surrounding fluid. The approach is inspired by the cytotoxic activity of natural killer cells and is quite effective at killing cancer cells both in vitro with human blood samples and in mouse blood circulation. The mechanism is surprising and unexpected in that this repurposing of leukocytes in flowing blood is more effective than directly targeting the cancer cells with liposomes or soluble protein.
Mycobacterial mistranslation is necessary and sufficient for rifampicin phenotypic resistance
Authors: Javid Babak , Sorrentino Flavia , Toosky Melody , Zheng Wen , Pinkham Jessica T. , Jain Nina , Pan Miaomiao , Deighan Padraig , Rubin Eric J.
Published: January 2014

Significance

Although error rates in protein translation, particularly under stress, are high, it is not known if these errors are inherent to the system, or if they may have an adaptive function. Here, we provide evidence that specific mistranslation of mycobacterial proteins is important for phenotypic resistance to the antibiotic rifampicin. This raises the possibility that errors in protein translation play a role in adapting to stress through increasing proteomic diversity.
Earliest evidence for caries and exploitation of starchy plant foods in Pleistocene hunter-gatherers from Morocco
Authors: Humphrey Louise T. , De Groote Isabelle , Morales Jacob , Barton Nick , Collcutt Simon , Bronk Ramsey Christopher , Bouzouggar Abdeljalil
Published: January 2014

Significance

We present early evidence linking a high prevalence of caries to a reliance on highly cariogenic wild plant foods in Pleistocene hunter-gatherers from North Africa. This evidence predates other high caries populations and the first signs of food production by several thousand years. We infer that increased reliance on wild plants rich in fermentable carbohydrates caused an early shift toward a disease-associated oral microbiota. Systematic harvesting and processing of wild food resources supported a more sedentary lifestyle during the Iberomaurusian than previously recognized. This research challenges commonly held assumptions that high rates of caries are indicative of agricultural societies.
Inflammasome-independent IL-1β mediates autoinflammatory disease in Pstpip2-deficient mice
Authors: Cassel Suzanne L. , Janczy John R. , Bing Xinyu , Wilson Shruti P. , Olivier Alicia K. , Otero Jesse E. , Iwakura Yoichiro , Shayakhmetov Dmitry M. , Bassuk Alexander G. , Abu-Amer Yousef , Brogden Kim A. , Burns Trudy L. , Sutterwala Fayyaz S. , Ferguson Polly J.
Published: January 2014

Significance

Chronic recurrent multifocal osteomyelitis (CRMO) is a human disorder of the innate immune system that causes bone inflammation that mimics infectious osteomyelitis. There is a spontaneous mutant mouse model of the disease that is caused by homozygous mutations in the genePstpip2. Our studies show that bone inflammation in this model is mediated by the cytokine IL-1β, but that the disease is independent of the nucleotide-binding domain, leucine-rich repeat-containing family, pyrin domain-containing 3 (NLRP3) inflammasome and caspase-1, which is different from most other IL-1–mediated disorders. Further, we implicate neutrophils and neutrophil serine proteases in disease pathogenesis. These data provide a rationale for directly targeting the IL-1 receptor or IL-1β as a therapeutic strategy in CRMO.
Critical role for inflammasome-independent IL-1β production in osteomyelitis
Authors: Lukens John R. , Gross Jordan M. , Calabrese Christopher , Iwakura Yoichiro , Lamkanfi Mohamed , Vogel Peter , Kanneganti Thirumala-Devi
Published: January 2014

Significance

The IL-1 cytokines, IL-1α and IL-1β, are proinflammatory cytokines that are implicated in numerous inflammatory and autoimmune diseases. This study demonstrates that dysregulated immune responses centrally contribute to the pathogenesis of osteomyelitis and identifies a critical role for IL-1β in driving the inflammatory cascade that provokes bone destruction. Caspase-1 activation in the inflammasome complex is the most well established mechanism for IL-1β secretion. Interestingly, inflammasome-independent sources of IL-1β were found to provoke inflammation and osteolytic bone disease. Our findings establish a unique role for inflammasome-independent IL-1β in autoinflammatory bone disease and osteomyelitis, and identify proline–serine–threonine phosphatase interacting protein 2 as a negative regulator of inflammasome-autonomous IL-1β.
Frequent mutation of receptor protein tyrosine phosphatases provides a mechanism for STAT3 hyperactivation in head and neck cancer
Authors: Lui Vivian Wai Yan , Peyser Noah D. , Ng Patrick Kwok-Shing , Hritz Jozef , Zeng Yan , Lu Yiling , Li Hua , Wang Lin , Gilbert Breean R. , General Ignacio J. , Bahar Ivet , Ju Zhenlin , Wang Zhenghe , Pendleton Kelsey P. , Xiao Xiao , Du Yu , Vries John K. , Hammerman Peter S. , Garraway Levi A. , Mills Gordon B. , Johnson Daniel E. , Grandis Jennifer R.
Published: January 2014

Significance

Most cancers are characterized by increased STAT3 activation where phosphorylated STAT3 levels are associated with reduced survival. The molecular mechanisms underlying aberrant STAT3 phosphorylation/activation in human malignancies have been elusive. Our findings provide a mechanistic basis for tumor-specific STAT3 hyperactivation in head and neck squamous cell carcinoma (HNSCC). We demonstrate that receptor-like protein tyrosine phosphatases, encoded by
PTPR
genes, including
PTPRT
, are commonly mutated in HNSCC where
PTPR
mutations are associated with increased phosphorylation of STAT3 in tumors. Several cancer-related
PTPRT
mutations localize to the substrate interaction surface of the enzyme catalytic domains. Expression of mutated
PTPRT
in HNSCC models markedly increases STAT3 activation, promoting cellular survival.
PTPRT
mutations may therefore serve as predictive biomarkers for STAT3 pathway inhibitors, suggesting new therapeutic opportunities.
Calcium phosphate-bearing matrices induce osteogenic differentiation of stem cells through adenosine signaling
Authors: Shih Yu-Ru V. , Hwang YongSung , Phadke Ameya , Kang Heemin , Hwang Nathaniel S. , Caro Eduardo J. , Nguyen Steven , Siu Michael , Theodorakis Emmanuel A. , Gianneschi Nathan C. , Vecchio Kenneth S. , Chien Shu , Lee Oscar K. , Varghese Shyni
Published: January 2014

Significance

A mechanistic understanding of how calcium phosphate (CaP) minerals contribute to osteogenic commitment of stem cells and bone tissue formation is a necessary requirement for developing efficient CaP-based synthetic matrices to treat bone defects. This study unravels a previously unknown mechanism, phosphate-ATP-adenosine metabolic signaling, by which the CaP-rich mineral environment in bone tissues promotes osteogenic differentiation of human mesenchymal stem cells. In addition to a mechanical perspective on how biomaterials can influence stem cell differentiation through metabolic pathways, this discovery opens up new avenues for treating critical bone defects and bone metabolic disorders.
Genome-wide evidence of Austronesian–Bantu admixture and cultural reversion in a hunter-gatherer group of Madagascar
Authors: Pierron Denis , Razafindrazaka Harilanto , Pagani Luca , Ricaut François-Xavier , Antao Tiago , Capredon Mélanie , Sambo Clément , Radimilahy Chantal , Rakotoarisoa Jean-Aimé , Blench Roger M. , Letellier Thierry , Kivisild Toomas
Published: January 2014

Significance

The Mikea are the last known Malagasy population reported to be still practicing a hunter-gatherer lifestyle. Earlier writers thought the Mikea were descended from ancient forager groups who have maintained their way of life up to the present. However, our analyses show that the Mikea are not a remnant population and, to the contrary, derived from a recent admixture of two agriculturalist populations: the Bantu (from Africa) and the Austronesian (from east-Asia). Thus, it is probable that the Mikea have adopted their hunter-gatherer way of life through a recent cultural reversion.
SAD kinases control the maturation of nerve terminals in the mammalian peripheral and central nervous systems
Authors: Lilley Brendan N. , Krishnaswamy Arjun , Wang Zhi , Kishi Masashi , Frank Eric , Sanes Joshua R.
Published: January 2014

Significance

Synapses between neurons are the primary means by which information flows through the nervous system. The molecular and functional complexity of synapses has been appreciated for some time, but the mechanisms by which synapses assemble remain unclear. We previously identified a conserved pair of signaling proteins, SAD kinases, required for two early events in the formation of axons by developing neurons. Here, we demonstrate that this same pair of signaling molecules acts in a later step to promote the maturation of axonal segments into presynaptic nerve terminals. Thus, SAD kinases may serve to coordinate multiple aspects of neuronal development.
Attosecond vacuum UV coherent control of molecular dynamics
Authors: Ranitovic Predrag , Hogle Craig W. , Rivière Paula , Palacios Alicia , Tong Xiao-Ming , Toshima Nobuyuki , González-Castrillo Alberto , Martin Leigh , Martín Fernando , Murnane Margaret M. , Kapteyn Henry
Published: January 2014

Significance

We show that we can precisely control molecular dynamics on both nuclear (i.e., femtosecond) and electronic (i.e., attosecond) timescales. By using attosecond vacuum UV light pulse trains that are tunable in the frequency domain, we show that it is possible to switch population between electronically excited states of a neutral molecule on attosecond time scales, and use this ability to coherently control excitation and ionization through specific pathways. This paper represents a milestone advance because almost two decades after attosecond physics was demonstrated, attosecond chemistry has not yet been fully established because the wavelength and bandwidth of attosecond pulses did not well match molecular quantum states. The richness and complexity of the dynamics, even in a simple molecule, is remarkable and daunting.
Human breast cancer metastases to the brain display GABAergic properties in the neural niche
Authors: Neman Josh , Termini John , Wilczynski Sharon , Vaidehi Nagarajan , Choy Cecilia , Kowolik Claudia M. , Li Hubert , Hambrecht Amanda C. , Roberts Eugene , Jandial Rahul
Published: January 2014

Significance

Breast cancer patients typically develop brain metastases years after their initial diagnosis. During this clinical latency, cancer cells must evolve and adapt to the neural microenvironment to colonize. We hypothesized that breast cancer cells may assume brain-like properties to survive in the brain. Our results suggest that metastases overexpress many variables related to the γ-aminobutyric acid (GABA) and were able to proliferate by metabolizing GABA as a biosynthetic energy source. The expression of brain-like properties by breast cancer cells could be a malignant adaptation required for metastasis to the brain, which could potentially be exploited to develop new therapy for breast cancer patients.
p85α deficiency protects β-cells from endoplasmic reticulum stress-induced apoptosis
Authors: Winnay Jonathon N. , Dirice Ercument , Liew Chong Wee , Kulkarni Rohit N. , Kahn C. Ronald
Published: January 2014

Significance

In type 2 diabetes, peripheral insulin resistance challenges the pancreatic β-cell to augment insulin synthesis and secretion. This compensatory mechanism eventually fails due to β-cell dysfunction, an increase in β-cell apoptosis, and a resultant decrease in β-cell mass. One mechanism contributing to this decline in β-cell mass is the development of endoplasmic reticulum (ER) stress. We have elucidated a role for the p85α regulatory subunit of PI3K as a modulator of ER stress-dependent apoptosis in β-cells by virtue of its ability to positively regulate the proapoptotic actions of x-box binding protein 1. The ablation of p85α specifically in the β-cell in a mouse model of ER stress-dependent β-cell apoptosis delays the decline in β-cell mass and subsequent development of diabetes.
Tau pathology involves protein phosphatase 2A in Parkinsonism-dementia of Guam
Authors: Arif Mohammad , Kazim Syed Faraz , Grundke-Iqbal Inge , Garruto Ralph M. , Iqbal Khalid
Published: January 2014

Significance

Parkinsonism-dementia (PD) of Guam is a classical tauopathy in which abnormal hyperphosphorylation of tau leads to neurodegeneration and dementia. A key unresolved question is the mechanism of abnormal hyperphosphorylation of tau in this disease. This study reports the involvement of a signaling pathway in which the inhibition of protein phosphatase 2A (PP2A) through phosphorylation of its catalytic subunit PP2Ac at Tyr
307
induced by the activation of metabotropic glutamate receptor 5 (mGluR5) leads to hyperphosphorylation of tau. These findings suggest that the mGluR5–PP2A axis has a central role in neurofibrillary degeneration in Guam PD and thus may be a therapeutic target for the treatment of this disease and related tauopathies.
Loss of liver E-cadherin induces sclerosing cholangitis and promotes carcinogenesis
Authors: Nakagawa Hayato , Hikiba Yohko , Hirata Yoshihiro , Font-Burgada Joan , Sakamoto Kei , Hayakawa Yoku , Taniguchi Koji , Umemura Atsushi , Kinoshita Hiroto , Sakitani Kosuke , Nishikawa Yuji , Hirano Kenji , Ikenoue Tsuneo , Ijichi Hideaki , Dhar Debanjan , Shibata Wataru , Akanuma Masao , Koike Kazuhiko , Karin Michael , Maeda Shin
Published: January 2014

Significance

The precise roles of E-cadherin in the liver and liver carcinogenesis are still unknown. Here we show that mice lacking E-cadherin in the liver develop spontaneous periportal inflammation via an impaired intrahepatic biliary network, as well as periductal fibrosis, which resembles primary sclerosing cholangitis. Inducible gene knockout studies identified E-cadherin loss in biliary epithelial cells as a causal factor of cholangitis induction, and dysregulated E-cadherin expression was also seen in patients with primary sclerosing cholangitis. E-cadherin loss also significantly accelerates genetically and chemically engineered liver cancer through epithelial–mesenchymal transition, up-regulation of stem cell markers, and ERK activation. Thus, E-cadherin plays critical roles in maintaining homeostasis and suppressing carcinogenesis in the liver.
The estrogen receptor antagonist ICI 182,780 can act both as an agonist and an inverse agonist when estrogen receptor α AF-2 is modified
Authors: Movérare-Skrtic Sofia , Börjesson Anna E. , Farman Helen H. , Sjögren Klara , Windahl Sara H. , Lagerquist Marie K. , Andersson Annica , Stubelius Alexandra , Carlsten Hans , Gustafsson Jan-Åke , Ohlsson Claes
Published: January 2014

Significance

Estrogen exerts important effects in the skeleton, which are primarily mediated via estrogen receptor (ER)α, which stimulates target gene transcription through two activation functions (AFs), AF-1 in the N-terminal and AF-2 in the ligand-binding domain. Previous studies demonstrate that ERα ligands might act as agonists, partial agonists, or antagonists. We demonstrate that the ERα antagonist ICI 182,780 (ICI) acts in a tissue-dependent manner in mice lacking ERαAF-2, resulting in no effect, agonistic activity, or inverse agonistic activity. Importantly, ICI exerted a pronounced inverse agonistic activity in the growth plate of mice lacking ERαAF-2. We propose that ERα lacking AF-2 is constitutively active in the absence of ligand in the growth plate, enabling ICI to act as an inverse agonist.