bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of the matched spot size in a capillary discharge waveguide with a collimated laser
Authors: Liu Jiaqi , Li Wentao , Liu Jiansheng , Qin Zhiyong , Wang Wentao , Qi Rong , Zhang Zhijun , Yu Changhai , Fang Ming , Feng Ke , Wu Ying , Wang Cheng , Li Ruxin
Published: October 2018

Measurement of the matched spot size in the hydrogen-filled capillary discharge waveguide based on the spot size oscillation of a collimated laser is presented in this paper. The spot size oscillation trace is retrieved from the laser modes measured at the exits of discharged capillaries of different lengths under the same discharge conditions. With the gas pressure, peak discharge electric current and capillary radius fixed, the radial density profiles are identical in all the discharged capillaries. The measured laser modes are equivalent to the evolution at discrete positions in a long plasma channel. Compared to former researches based on the spot size at the capillary exit, this method is not affected by the multiple solution problem. The use of a collimated laser eliminates the influences of the divergence angle on the fitting accuracy. By this means, the matched spot sizes of hydrogen-filled capillary discharge waveguides under different gas pressures (5-20mbar) are measured. The results can provide a spot size reference for the laser wakefield accelerator guided in a plasma channel.
Possibility for observing Hawking-like effects via the interaction of multi-PW class laser pulses with underdense plasmas
Authors: Yano Masahiro , Zhidkov Alexei , Hosokai Tomonao , Kodama Ryosuke
Published: October 2018

Regular electron bunches undergoing extremely high acceleration emulating the behavior of electrons near black holes are shown to occur in underdense plasmas irradiated by multi-PW laser pulses with the intensity over 1022 W/cm2. The interaction of multi-PW laser pulses with underdense plasma, in the regime of strong relativistic wave-breaking, is investigated via fully relativistic 3D particle-in-cell simulations including ion motion and radiation reaction. The effect of a transverse cylindrical plasma wave in laser pulse wakes on the formation of regular electron bunches under extremely high acceleration, w, suitable for the detection of Hawking-Unruh temperature TH=ℏw/2πkBc is shown and analyzed.
Wind load analysis of a new linear Fresnel receiver assembly design
Authors: Parikh Abhishek , Martinek Janna , Mungas Greg , Kramer Nicholas , Zhu Guangdong
Published: October 2018

A linear Fresnel collector includes a low-profile reflector array and a receiver assembly with one or more absorber tubes and an optional secondary reflector. This combined optical system concentrates sunlight and converts it into thermal energy. The design of a receiver assembly is critical to the performance of a linear Fresnel collector. A position deviation of a few centimeters for the receiver assembly can result in notably reduced performance, thus leading to a direct loss in revenue associated with thermal power production. Wind load is one of the most significant environmental factors that can alter the optical—and therefore thermal—performance of a solar power system due to displacements after installation. At the same time, an over-designed receiver assembly may add unnecessary construction cost to a typically high-cost-constrained system. Thus, wind load analysis is particularly important when considering optimal engineering design of a receiver assembly and its supporting structure to cost-effectively mitigate the impacts of wind. In this study, a detailed computational fluid dynamics (CFD) model is adopted to derive the wind load of a commercial linear Fresnel receiver assembly. This wind load is then used as a reference to optimize the detailed engineering design. The CFD model is first carefully developed and benchmarked within a critical regime toward turbulence. The drag force, lift force, and vortex-shedding frequencies are derived at both the operating and survival wind-speed limits for target project deployment locations. The wind load analysis results provide a valuable reference for future engineering design and prototyping.
Jet outflow and open field line measurements on the C-2W advanced beam-driven field-reversed configuration plasma experiment
Authors: Sheftman D. , Schmitz L. , Gupta D. , Thompson M. C. ,   TAE Team
Published: October 2018

Accurate operation and high performance of the open field line plasma surrounding the field reversed configuration is crucial to achieving the goals of successful temperature ramp up and confinement improvement on C-2W. Knowledge and control of the open field line plasma requires extensive diagnostic efforts. A suite of diagnostics, which consists of microwave interferometry, dispersive spectroscopy, and spatial heterodyne spectroscopy, is being developed to measure electron density, ion temperature, and particle outflow velocity at various locations along the open magnetic field lines. A detailed overview of these diagnostics is presented.
Large depth focus-tunable photoacoustic tomography based on clinical ultrasound array transducer
Authors: Liu Ruian , Xiang Liangzhong , Xing Da , Li Jiandong , Qin Huan , Zhang Weicheng , Yang Sihua
Published: October 2018

Multi-element photoacoustic tomography systems have either a non-movable focus or a non-uniform light field distribution over the region of interest, significantly limiting the depth-of-field and resolution of images. In this study, focus-tunable photoacoustic tomography (FT-PAT) based on a clinical ultrasound array transducer with uniform laser excitation was developed to achieve high-resolution imaging in deep tissue. An adjustable line-focusing structure was used to condense the laser beam, and the excited photoacoustic signal was processed via a synthetic-aperture focusing technique. Carbon rods at different depths were used to evaluate the focus-tunable ability in a tissue phantom. In vivo focus-tunable imaging performance was demonstrated by an experiment involving imaging of carbon nanoparticle-labeled living nude mouse covered by chicken breast. The signal-to-noise ratio of targets at different depths was changed by focus adjustment, which demonstrates that the FT-PAT system has potential clinical applications in deep tumor imaging and subsequent diagnoses.
Polytetrahedral structure and glass-forming ability of simulated Ni–Zr alloys
Authors: Klumov B. A. , Ryltsev R. E. , Chtchelkatchev N. M.
Published: October 2018

Binary Cu–Zr system is a representative bulk glassformer demonstrating high glass-forming ability (GFA). From the first glance, the Ni–Zr system is the most natural object to expect the same behavior because nickel and copper are neighbors in the periodic table and have similar physicochemical properties. However, it is known that the Ni–Zr system has worse GFA than the Cu–Zr one. To understand the underlying physics, we investigate the NiαZr1−α system in whole concentration range α ∈ [0, 1]. Doing molecular dynamic simulations with a reliable embedded atom model potential, we show that the simulated Ni–Zr system also has relatively low GFA, which is comparable to that for an additive binary Lennard-Jones mixture without any chemical interaction. Icosahedral local ordering in Ni–Zr alloys is known to be less pronounced than that in the Cu–Zr ones; we see that as well. However, the icosahedron is not the only structural motif responsible for GFA. We find that the local structure of glassy NiαZr1−α alloys at 0.3 < α < 0.65 can be described in terms of Z11-Z16 Kasper polyhedra with high density of topological defects including icosahedra as a part of this family. Concentration of topologically perfect Kasper polyhedra appears to be several times smaller than that in Cu–Zr. This is the reason for relatively poor GFA of the Ni–Zr system.
Influence of carbon impurities and oxygen vacancies in Al2O3 film on Al2O3/GaN MOS capacitor characteristics
Authors: Uenuma Mutsunori , Takahashi Kiyoshi , Sonehara Sho , Tominaga Yuta , Fujimoto Yuta , Ishikawa Yasuaki , Uraoka Yukiharu
Published: October 2018

Effects of carbon impurities and oxygen vacancies in Al2O3 film on the characteristics of Al2O3/GaN MOS capacitors were studied using the different atomic layer deposition (ALD) precursor and high-pressure water vapor annealing (HPWVA). Trimethyl aluminum (TMA: Al(CH3)3) and dimethyl aluminum hydride (DMAH: Al(CH3)2H) were used as ALD precursors to control the carbon impurities. On the other hand, oxygen vacancies in Al2O3 film were suppressed using the HPWVA. The DMAH precursor reduced the concentration of carbon impurities in the ALD Al2O3 film. It was found that the interface trap density (Dit) was mainly affected by the carbon impurities rather than the oxygen vacancies at the Al2O3/GaN interface. On the other hand, voltage stress induced flat band voltage (VFB) shift was attributed to both the carbon impurities and the oxygen vacancies.
Resonate and fire neuron with fixed magnetic skyrmions
Authors: Azam Md. Ali , Bhattacharya Dhritiman , Querlioz Damien , Atulasimha Jayasimha
Published: October 2018

In the brain, the membrane potential of many neurons oscillates in a subthreshold damped fashion and fire when excited by an input frequency that nearly equals their eigen frequency. In this work, we investigate theoretically the artificial implementation of such “resonate-and-fire” neurons by utilizing the magnetization dynamics of a fixed magnetic skyrmion in the free layer of a magnetic tunnel junction (MTJ). To realize firing of this nanomagnetic implementation of an artificial neuron, we propose to employ voltage control of magnetic anisotropy or voltage generated strain as an input (spike or sinusoidal) signal, which modulates the perpendicular magnetic anisotropy. This results in continual expansion and shrinking (i.e., breathing) of a skyrmion core that mimics the subthreshold oscillation. Any subsequent input pulse having an interval close to the breathing period or a sinusoidal input close to the eigen frequency drives the magnetization dynamics of the fixed skyrmion in a resonant manner. The time varying electrical resistance of the MTJ layer due to this resonant oscillation of the skyrmion core is used to drive a Complementary Metal Oxide Semiconductor buffer circuit, which produces spike outputs. By rigorous micromagnetic simulation, we investigate the interspike timing dependence and response to different excitatory and inhibitory incoming input pulses. Finally, we show that such resonate and fire neurons have potential application in coupled nanomagnetic oscillator based associative memory arrays.
Ultra-fast logic devices using artificial “neurons” based on antiferromagnetic pulse generators
Authors: Sulymenko Olga , Prokopenko Oleksandr , Lisenkov Ivan , Åkerman Johan , Tyberkevych Vasyl , Slavin Andrei N. , Khymyn Roman
Published: October 2018

It has been shown previously that spin-Hall oscillators based on current-driven bi-layered film structures containing an antiferromagnet (AFM) and a normal metal can generate ultra-short (∼2 ps) “spike-like” pulses in response to an external current stimulus of a sufficient amplitude, thus operating as ultra-fast artificial “neurons.” Here, we report the results of numerical simulations demonstrating that a single AFM “neuron” can perform the logic functions of or, and, majority, or q-gates, while a circuit consisting of a small number n<5 of AFM “neurons” can function as a full-adder or as a dynamic memory loop with variable clock frequency. The clock frequencies of such AFM-based logic devices could reach tens of GHz, which make them promising as base elements of future ultra-fast high-efficiency neuromorphic computing.
Anomalous pressure effect on the Nèel temperature and volume of DyB6
Authors: Eto Tetsujiro , Oomi Gendo , Sakai Takeshi , Uwatoko Yoshiya , Kunii Satoru
Published: October 2018

The pressure effect on the Nèel temperature TN of DyB6 has been investigated by measuring the temperature dependence of electrical resistivity (ρ) at various pressures up to 8 GPa. It was found that TN increases almost linearly with pressure in the range of 0-2 GPa and then tends to saturate above 2 GPa. The pressure derivative of TN below 2 GPa was estimated to be 2.6 K/GPa. The pressure effect on the volume of DyB6 has also been measured at high pressure up to 14 GPa at room temperature using X-ray diffraction and diamond anvil cell. The pressure dependence of volume of LaB6 was also measured for the comparison. It is revealed that DyB6 is more compressible than LaB6. The origin for this observation is suggested to be due to the difference of the ionic size of the rare earth elements, or the strong electron-phonon interaction in DyB6.
Topological features of the thermal Hall conductivity in a chiral p-wave superconductor under strain
Authors: Imai Y. , Sigrist M.
Published: October 2018

Motivated by experimental studies on the effect of tensile and compressive strain or uniaxial pressure in the superconducting phase of the transition metal oxide Sr2RuO4, the pairing symmetry assuming the chiral p-wave superconducting state and the transport property are investigated theoretically by means of the self-consistent Bogoliubov-de Gennes approach. The uniaxial strain leads to the Fermi surface deformation. The topological properties are sensitive to the Fermi surface geometry induced by the strain and switch around the Lifshitz transition in the γ band. The temperature dependence of the thermal Hall conductivity is connected with the amplitude of the strain. While the topological number is reflected in the temperature linear contribution in the low-temperature limit of the thermal Hall conductivity, the deviation from this behavior depends on the pairing channel. Our result may enable us to provide information on the gap function of the chiral p-wave phase.
Pressure effect on the antiferromagnetic compound Ce2Ni3Ge5
Authors: Gouchi Jun , Nakamura Yuki , Nakashima Miho , Amako Yasushi , Kumar Ravhi , Uwatoko Yoshiya
Published: October 2018

In this study, the electrical resistivity and magnetization of a single crystal of Ce2Ni3Ge5 heavy fermion compound were performed under pressure. The resistivity and magnetization showed two antiferromagnetic transitions at ambient pressure. On applying pressure, the transitions merged at 1 GPa. At higher pressures, the antiferromagnetic transition temperature decreases, and disappears. It is suggesting that the critical pressure of Ce2Ni3Ge5 was 4.1 GPa.
Simultaneous arrayed formation of single-electron transistors using electromigration in series-connected nanogaps
Authors: Ito Mitsuki , Yagi Mamiko , Shimada Moe , Shirakashi Jun-ichi
Published: October 2018

A field-emission-induced electromigration method (activation) is reported for integrating single-electron transistors operating at T = 298 K. The field emission currents between the two opposite electrodes of each series-connected nanogap are tuned to accumulate Ni atoms within the gaps. For ten series-connected nanogaps, the resistance (VD/ID), obtained using the current-voltage (ID-VD) properties of these nanogaps during the activation procedure, is observed to decrease on activation. As a result, island structures are formed within the gaps, and the nanogap-based single-electron transistors can be integrated, when atom migration occurs at the tip of each nanogap electrode. After activating the ten series-connected nanogaps with a preset current, IS = 1 nA, current suppression (representative of coulomb blockade) is not observed in the fabricated devices. On the other hand, coulomb blockade, which depicts the charging and discharging of the nanoislands, can be observed at room temperature, after activation with a preset current, IS = 150 nA. Furthermore, the modulation properties of the coulomb blockade voltage by the gate voltage are also determined at room temperature. These results experimentally demonstrate the arrayed formation of ten single-electron transistors operating at room temperature, constituting a significant step toward the practical realization of single-electron-transistor-based systems.
Theoretical study of fluorine-induced surface segregation of Cr in non-passivated Ni-based alloys
Authors: Yin Ya-Ru , Ren Cui-Lan , Han Han , So Kang Pyo , Ye Xiang-Xi , Zhang Xun , Huai Ping , Zhu Zhi-Yuan
Published: October 2018

The effects of fluorine adsorption on the surface segregation behaviors of chromium in nickel-based alloys are systematically investigated by selecting three typical low-index Cr-doped Ni (111), (100), and (110) surfaces based on the first-principles calculations. The Cr doped in the nickel substrate is identified to possess a local trapping effect for fluorine in the full space and contributes to the more exothermic adsorption of fluorine. In turn, the chemisorption of fluorine on the Cr-doped Ni surfaces can dramatically incur the preferential top-surface segregation for Cr from nickel bulk. The increased adsorption energy of fluorine on Cr-doped Ni surfaces compensates for the larger surface energy of Cr relative to Ni. The strong F-Cr bonding from the deeper hybrid state of F 2p-Cr 3d helps to release strain energy caused by atomic size mismatch. At higher fluorine coverage, the driving force for Cr to segregate at nickel surfaces is significantly increased, as the fluorine starts to agglomerate in the vicinity of Cr. Such chemisorption-induced surface abnormal segregation of Cr to the top-most surface plays a critical role in the preferential dealloying of Cr at the early-stage corrosion of non-passivated nickel-based alloys in molten fluoride salts.
Microwave generation of X-waves by means of a planar leaky-wave antenna
Authors: Comite D. , Fuscaldo W. , Podilchak S. K. , Gómez-Guillamón Buendía V. , Hilario Re P. D. , Baccarelli P. , Burghignoli P. , Galli A.
Published: October 2018

We analyze and experimentally demonstrate the possibility of generating X-waves at microwave and millimeter-wave frequencies by means of a partially open radial parallel-plate waveguide antenna. The structure is azimuthally symmetric and fed in the center by means of a simple vertical coaxial probe, which excites a cylindrical leaky wave. Radially periodic annular slots etched in the upper metal plate allow the propagation of a backward leaky wave, as required for generating Bessel beams in the near-field region. Since X-waves are polychromatic superpositions of Bessel beams, the wavenumber frequency dispersion of the relevant leaky mode is accounted for by the antenna design. In particular, a dispersion-engineering approach is used to properly select the operating fractional bandwidth for the antenna. Even if the beneficial effect of a large bandwidth is partially neutralized by the dispersive character of the resulting pulse, this being more prominent as the bandwidth increases, the experimental results demonstrate the capability of this simple planar design of generating X-waves in the microwave regime. The antenna can be of interest for the design of next-generation medical imaging devices, for non-destructive evaluations, as well as for wideband near-field secure communications and wireless power transfer systems at microwaves and millimeter waves.
Electrostatic design and conditioning of a triple point junction shield for a −200 kV DC high voltage photogun
Authors: Palacios-Serrano G. , Hannon F. , Hernandez-Garcia C. , Poelker M. , Baumgart H.
Published: October 2018

Nuclear physics experiments performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at the Jefferson Lab require a DC high voltage photogun to generate polarized electron beams from GaAs photocathodes. The photogun uses a tapered ceramic insulator that extends into the vacuum chamber and mechanically holds the cathode electrode. Increasing the operating voltage from nominal −130 kV to −200 kV will provide lower beam emittance, better transmission through injector apertures, and improved photocathode lifetime. This desire to increase the photogun operating voltage led to the design of a triple-point-junction shield electrode which minimizes the electric field at the delicate insulator-metal-vacuum interface and linearizes the potential across the insulator, thus reducing the risk of arcing along the ceramic insulator. This work describes the results obtained using COMSOL® electrostatic-field simulation software and presents the high voltage conditioning results of the upgraded −200 kV CEBAF photogun.
Microfluidic platforms for rapid screening of cancer affinity reagents by using tissue samples
Authors: Hung Lien-Yu , Fu Chien-Yu , Wang Chih-Hung , Chuang Yuan-Jhe , Tsai Yi-Cheng , Lo Yi-Ling , Hsu Pang-Hung , Chang Hwan-You , Shiesh Shu-Chu , Hsu Keng-Fu , Lee Gwo-Bin
Published: October 2018

Cancer is the most serious disease worldwide, and ovarian cancer (OvCa) is the second most common type of gynecological cancer. There is consequently an urgent need for early-stage detection of OvCa, which requires affinity reagent biomarkers for OvCa. Systematic evolution of ligands by exponential enrichment (SELEX) and phage display technology are two powerful technologies for identifying affinity reagent biomarkers. However, the benchtop protocols for both screening technologies are relatively lengthy and require well-trained personnel. We therefore developed a novel, integrated microfluidic system capable of automating SELEX and phage display technology. Instead of using cancer cell lines, it is the first work which used tissue slides as screening targets, which possess more complicated and uncovered information for affinity reagents to recognize. This allowed for the identification of aptamer (nucleic acid) and peptide probes specific to OvCa cells and tissues. Furthermore, this developed system could be readily modified to uncover affinity reagents for diagnostics or even target therapy of other cancer cell types in the future.
Balanced Polymorphisms With Unlinked Loci
Authors: Moran PAP
Published: October 2018

The stationary states of a genetic population whose fitness is controlled by two independent loci, with two alleles each, are considered. It is shown that apart from degenerate cases there are at most five such states. It is also shown that there are at most three stationary states which are stable. Examples are given where these bounds are attained.
Relationship Between Effective Nodulation and Time to Initial Nodulation in a Diploid Line of Trifolium Ambiguum M. Bieb.
Authors: Hely FW
Published: October 2018

Investigations conducted with random populations of a diploid line of' Trifolium ambiguum M. Bieh., inoculated with a stable strain of Rhizobium trifoMi, effective on this clover, and grown under microbiologically controlled conditions, revealed considerable symbiotic variation within the host.
The Root Rot-Fusarium Wilt Complex of Peas
Authors: Kerr A
Published: October 2018

At least four fungal pathogens are involved in the root rot-Fusarium wilt complex of peas which is a serious problem following intensive cropping of peas in South Australia. The pathogens are Fusarium oxysporum f. pisi race 2 Snyder & Hansen, F. solani f. pisi Snyder & Hansen, Pythium ultimum Trow, and Ascochyta pinodella L. K. Jones. In susceptible pea cultivars there is a marked interaction between F. oxysporum and P. ultimum. P. ultimum alone causes initial stunting from which plants gradually recover; F. OX1Jsporum alone probably CRuses little damage; both fungi together CRuse initial stunting followed by severe wilt symptom about 6 weeks after sowing and death 2 weeks later. The importance ofF. solani and A. pinodella has not been fully determined, but they probably cause only minor damage.
Estimation of Diffusion Pressure Deficit by Correlation With Relative Turgidity and Beta-Radiation Absorption
Authors: Whiteman PC , Wilson GL
Published: October 2018

Difficulties of technique prevent extensive measurement of the diffusion pressure deficit (DPD) of plant tissues. The possibility of estimation by correlation with more easily measured indices of water status has been examined for leaf tissue of Sorghum l.,'ulgare.
Studies on Endemic Goitre II. The Behaviour of 3-Methylsulphonylpropyl Isothiooyanate (Cheirolin) and Other Isothiocyanates in Bovine Rumen Liquor
Authors: Bachelard HS , Trikojus VM
Published: October 2018

When incubated with bovine rumen liquor cheirolin (3-methylsulphonylpropyl isothiocyanate) has been shown to be converted into the disubstituted thiourea, dicheirolin thiourea, with traces of other identified compounds. At the pH tested, only one other isothiocyanate was found to undergo a similar conversion. The reaction is not enzyme dependent but appears to be catalysed by a metal ion. During studies of the behaviour of thioglucosides in rumen liquor the presence of thioglucosidases could not be demonstrated in this medium.
Some Effects of Sulphur-Containing Amino Acids on the Growth and Composition of Wool
Authors: Reis PJ , Schinckel PG
Published: October 2018

The effect on wool growth and the sulphur content of wool of supplements of L-oyswine, DL-methionine, and casein, given per abomasum a�s a continuous infusion, has been examined.
Dissolution of Amyloid Aggregates in Aqueous Ionic Liquid Solutions: A Case Study of Insulin Amyloid
Authors: Takekiyo Takahiro , Ishikawa Yuka , Yamaguchi Erika , Yamada Natsuki , Yoshimura Yukihiro
Published: October 2018

Dissolution of amyloid aggregates with high β-sheet content is required for the correct refolding of ordered protein aggregates. The dissolution of bovine insulin amyloid aggregates in five different ionic liquids (ILs) is investigated. These were comprised of three 1-butyl-3-methylimidazolium ([bmim])-based ILs, containing either SCN−, NO3−, or Cl− anions, and two alkylammonium nitrate-based ILs, ethyl- and propylammonium nitrate (EAN and PAN). A broad IL concentration range (x=0–30mol-% IL) was analysed using FTIR spectroscopy combined with the Congo red assay. On the whole, the [bmim]-based ILs showed a higher dissolution ability than EAN and PAN for all concentrations of x. It is notable that the dissolution ability of dilute aqueous IL solutions (x<15) for insulin amyloid was different to that of concentrated aqueous IL solutions (x>15). The former condition for insulin amyloid may affect dissolution based on the denaturant effect of cations and anions in the ILs. The latter condition may affect this dissolution based on the hydrogen-bonding ability (α and β values) of the ILs, as described by the Kamlet–Taft parameters. Moreover, the difference between these α and β values (α–β) was found to be a good indicator of the dissolution ability of ILs for insulin amyloid aggregates in concentrated conditions above x=20 (α–β<0, strong dissolution ability; α–β>0, weak dissolution ability). These findings may assist the future design of aqueous IL-based dissolution agents for ordered aggregated proteins.
Grid-like hexadirectional modulation of human entorhinal theta oscillations
Authors: Maidenbaum Shachar , Miller Jonathan , Stein Joel M. , Jacobs Joshua
Published: October 2018

Significance

The entorhinal cortex plays a critical role in allowing organisms to navigate and represent spatial memories using grid-like representations. Given the importance of spatial processing for everyday life, we examined the patterns of neuronal oscillations in the entorhinal cortex, which are thought to underlie grid cells, in humans using intracranial recordings from neurosurgical patients as they navigated in virtual reality. We show that the power of entorhinal theta oscillations shows a distinctive six-way symmetric directional modulation, suggesting they correlate with grid representations, and that this signal correlates with spatial memory performance. Our findings thus show that the human entorhinal grid network is associated with theta oscillations and indicate that it is possible to measure properties of grid-like neural representations by recording oscillations.
Nonsaturating large magnetoresistance in semimetals
Authors: Leahy Ian A. , Lin Yu-Ping , Siegfried Peter E. , Treglia Andrew C. , Song Justin C. W. , Nandkishore Rahul M. , Lee Minhyea
Published: October 2018

Significance

The intensive recent investigations of topological semimetals have revealed a large number of semimetal compounds that exhibit very large nonsaturating magnetoresistance. Multiple mechanisms for this magnetoresistance phenomenon have been theoretically proposed, but experimentally it is unclear how to identify which mechanism is responsible in a particular sample or how to make a clean connection between experimental observations and theoretical models. Our results show that the magnetic susceptibility and the tangent of the Hall angle successfully capture the fundamental differences in seemingly similar nonsaturating large magnetoresistance, where charge compensation, energy dispersion, and the roles of disorder are markedly distinct, and provide empirical templates to characterize the origins of the extraordinary magnetotransport properties in the newly discovered topological semimetals and beyond.
Abscisic acid-independent stomatal CO
2
signal transduction pathway and convergence of CO
2
and ABA signaling downstream of OST1 kinase
Authors: Hsu Po-Kai , Takahashi Yohei , Munemasa Shintaro , Merilo Ebe , Laanemets Kristiina , Waadt Rainer , Pater Dianne , Kollist Hannes , Schroeder Julian I.
Published: October 2018

Significance

Elevated CO
2
and abscisic acid (ABA) induce rapid stomatal closure, but the underlying signal transduction mechanisms of CO
2
/ABA interaction remain unclear. Here we show that elevated CO
2
-induced stomatal closure is not abolished but is slowed in higher-order ABA biosynthesis and receptor mutants. Physiological CO
2
elevations activate anion channels in these mutants. In vivo time-resolved ABA nanoreporter imaging indicates that CO
2
elevation does not change ABA concentrations in guard cells. Unexpectedly, CO
2
signaling proceeds without direct OST1/SnRK2 kinase activation in guard cells. This study points to a model that elevated CO
2
triggers stomatal closure through an ABA-independent pathway downstream of OST1/SnRK2 kinases and that basal ABA signaling and OST1/SnRK2 activity enhance stomatal closure in response to CO
2
elevation.
A novel ultra-strong hot stamping steel treated by quenching and partitioning process
Authors: Liang Jiangtao , Zhao Zhengzhi , Sun Binhan , Lu Hongzhou , Liang Juhua , He Qing , Chen Weijian , Tang Di
Published: October 2018

In the present study, we design a novel hot stamping steel containing high amounts of C and Si and micro-alloying element (i.e. Nb). The steel was subjected to quenching and partitioning (Q&P) process. The new Q&P treated hot stamping steel exhibits a significantly improved mechanical property in terms of strength, ductility and impact toughness compared with the traditional 22MnB5 hot stamping steel. The influence of partitioning time on the microstructure and mechanical properties was investigated. The retained austenite (RA) fraction and the carbon content of RA significantly increased with higher partitioning times. With increasing partitioning time, the uniform elongation, total elongation, strength-ductility balance and impact energy was also remarkably enhanced. The maximum strength-ductility balance achieves around 23 GPa %.
Lost in legation: the gap between rhetoric and reality in international human rights law governing women’s rights
Authors: DeLaet Debra L.
Published: October 2018

This article weaves together insights from political science, human rights scholarship, feminist legal theory, and other critical perspectives to explore the limits of global legalism as a primary mechanism for promoting women's rights. Specifically, it examines international human rights law governing women's rights to consider the limitations of law as a mechanism for improving the status of women globally. Although its development has been prolific, formal international human rights law is characterized by a significant gap between aspirational rhetoric and the reality of limited implementation and enforcement. This gap between rhetoric and reality demonstrates the limitations of a universalistic legal framework as a mechanism for promoting significant gains for women's equality and rights. The article investigates the limitations of international human rights law as a tool for promoting women's rights through a close examination of human rights treaty systems, specifically theConvention on the Elimination of Discrimination Against Women.
Aneuploidy in intestinal stem cells promotes gut dysplasia in Drosophila
Authors: Resende Luís Pedro , Monteiro Augusta , Brás Rita , Lopes Tatiana , Sunkel Claudio E.
Published: October 2018

Aneuploidy is associated with different human diseases including cancer. However, different cell types appear to respond differently to aneuploidy, either by promoting tumorigenesis or causing cell death. We set out to study the behavior of adult Drosophila melanogaster intestinal stem cells (ISCs) after induction of chromosome missegregation either by abrogation of the spindle assembly checkpoint or through kinetochore disruption or centrosome amplification. These conditions induce moderate levels of aneuploidy in ISCs, and we find no evidence of apoptosis. Instead, we observe a significant accumulation of ISCs associated with increased stem cell proliferation and an excess of enteroendocrine cells. Moreover, aneuploidy causes up-regulation of the JNK pathway throughout the posterior midgut, and specific inhibition of JNK signaling in ISCs is sufficient to prevent dysplasia. Our findings highlight the importance of understanding the behavior of different stem cell populations to aneuploidy and how these can act as reservoirs for genomic alterations that can lead to tissue pathologies.
Progress on the multi bunch FEL performance at FLASH
Authors: Hellert Thorsten , Schmidt Christian
Published: October 2018

At the SASE-FEL user facility FLASH, superconducting TESLA-type cavities are used for acceleration. The high achievable duty cycle allows for operating with long bunch-trains, hence considerably increasing the efficiency of the machine. However, RF induced intra-bunch-train trajectory variations were found to be responsible for significant variations of the SASE intensity within one bunch train. This work presents the latest achievements in improving the multi-bunch FEL performance by reducing the intra-bunch-train variation of RF parameters. Particular attention is given to the static and dynamic detuning of the cavities. It will be shown that the current level of LLRF control is suitable to limit the variation of RF parameters considerably.
Development of a new modular switch using a next-generation semiconductor
Authors: Takayanagi T , Ueno T , Horino K
Published: October 2018

An ultra-high-speed short pulse switch for high power devices has been developed by using SiC - MOSFET which is one of the next generation semiconductors. Semiconductor switches using SiC-MOSFETs are expected to substitute the thyratron, and they are designed by connecting many semiconductor switches in parallel-series for high power operation. In order to suppress the common-mode noise caused by switching, it is common to form a symmetrical circuit. How-ever, as the number of parallel connections in the horizontal direction increases, the length of the parallel circuit becomes longer, and the output waveform is distorted due to time lag between the circuits. There-fore, we propose a radially-symmetrical type module switch which can equalize the circuit length regardless of the number of parallel circuit. The design and preliminary test results of two types of switch circuits, radially-symmetrical type and general line-symmetrical type are presented here.
Development of a proton-to-neutron converter for radioisotope production at ISAC-TRIUMF
Authors: Egoriti L. , Augusto R. , Bricault P. , Day Goodacre T. , Delonca M. , Dierckx M. , Houngbo D. , Popescu L. , Ramos J.P. , Rothe S. , Stora T. , Gottberg A.
Published: October 2018

At ISAC-TRIUMF, a 500 MeV proton beam is impinged upon “thick” targets to induce nuclear reactions to produce reaction products that are delivered as a Radioactive Ion Beam (RIB) to experiments. Uranium carbide is among the most commonly used target materials which produces a vast radionuclide inventory coming from both spallation and fission-events. This can also represent a major limitation for the successful delivery of certain RIBs to experiments since, for a given mass, many isobaric isotopes are to be filtered by the dipole mass separator. These contaminants can exceed the yield of the isotope of interest by orders of magnitude, often causing a significant reduction in the sensitivity of experiments or even making them impossible.

The design of a 50 kW proton-to-neutron (p2n) converter-target is ongoing to enhance the production of neutron-rich nuclei while significantly reducing the rate of neutron-deficient contaminants. The converter is made out of a bulk tungsten block which converts proton beams into neutrons through spallation. The neutrons, in turn, induce pure fission in an upstream UCx target. The present target design and the service infra-structure needed for its operation will be discussed in this paper.
Quasisymmetric uniformization and heat kernel estimates
Authors: Murugan Mathav
Published: October 2018

We show that the circle packing embedding in

R

2

\mathbb {R}^2

of a one-ended, planar triangulation with polynomial growth is quasisymmetric if and only if the simple random walk on the graph satisfies sub-Gaussian heat kernel estimate with spectral dimension two. Our main results provide a new family of graphs and fractals that satisfy sub-Gaussian estimates and Harnack inequalities.
Cdt1 variants reveal unanticipated aspects of interactions with cyclin/CDK and MCM important for normal genome replication
Authors: Pozo Pedro N. , Matson Jacob P. , Cole Yasemin , Kedziora Katarzyna M. , Grant Gavin D. , Temple Brenda , Cook Jeanette Gowen
Published: October 2018

The earliest step in DNA replication is origin licensing, which is the DNA loading of minichromosome maintenance (MCM) helicase complexes. The Cdc10-dependent transcript 1 (Cdt1) protein is essential for MCM loading during the G1 phase of the cell cycle, but the mechanism of Cdt1 function is still incompletely understood. We examined a collection of rare Cdt1 variants that cause a form of primordial dwarfism (the Meier–Gorlin syndrome) plus one hypomorphic Drosophila allele to shed light on Cdt1 function. Three hypomorphic variants load MCM less efficiently than wild-type (WT) Cdt1, and their lower activity correlates with impaired MCM binding. A structural homology model of the human Cdt1–MCM complex positions the altered Cdt1 residues at two distinct interfaces rather than the previously described single MCM interaction domain. Surprisingly, one dwarfism allele ( Cdt1-A66T) is more active than WT Cdt1. This hypermorphic variant binds both cyclin A and SCFSkp2poorly relative to WT Cdt1. Detailed quantitative live-cell imaging analysis demonstrated no change in the stability of this variant, however. Instead, we propose that cyclin A/CDK inhibits the Cdt1 licensing function independent of the creation of the SCFSkp2phosphodegron. Together, these findings identify key Cdt1 interactions required for both efficient origin licensing and tight Cdt1 regulation to ensure normal cell proliferation and genome stability.
Cognitive control involves theta power within trials and beta power across trials in the prefrontal-subthalamic network
Authors: Zavala Baltazar , Jang Anthony , Trotta Michael , Lungu Codrin I , Brown Peter , Zaghloul Kareem A
Published: October 2018

There is increasing evidence that the medial prefrontal cortex participates in conflict and feedback monitoring while the subthalamic nucleus adjusts actions. Yet how these two structures coordinate their activity during cognitive control remains poorly understood. We recorded from the human prefrontal cortex and the subthalamic nucleus simultaneously while participants (n = 22) performed a novel task involving high conflict trials, complete response inhibition trials, and trial-to-trial behavioural adaptations to conflict and errors. Overall, we found that within-trial adaptions to both conflict and complete response inhibition involved changes in the theta band while across-trial behavioural adaptations to both conflict and errors involved changes in the beta band (P < 0.05). Yet the role each region’s theta and beta oscillations played during the task differed significantly between the two sites. Trials that involved either within-trial conflict or complete response inhibition were associated with increased theta phase synchrony between the medial prefrontal cortex and the subthalamic nucleus (P < 0.05). Despite increased synchrony, however, increases in prefrontal theta power were associated with response inhibition, while increases in subthalamic theta power were associated with response execution (P < 0.05). In the beta band, post-response increases in prefrontal beta power were suppressed when the completed trial contained either conflict or an erroneous response (P < 0.05). Subthalamic beta power, on the other hand, was only modified during the subsequent trial that followed a conflict or error trial. Notably, these adaptation trials exhibited slower response times (P < 0.05), suggesting that both brain regions contribute to across-trial adaptations but do so at different stages of the adaptation process. Taken together, our data shed light on the mechanisms underlying within-trial and across-trial cognitive control and how disruption of this network can negatively impact cognition. More broadly, however, our data also demonstrate that the specific role of a brain region, rather than the frequency being utilized, governs the behavioural correlates of oscillatory activity.
The Effect of Negative Aging Self-Stereotypes on Satisfaction With Social Support
Authors: Cheng Sheung-Tak
Published: October 2018

Objectives

Previous studies have demonstrated a relationship between negative age self-stereotypes and social support satisfaction. This study examined whether negative age stereotype plays a causal role, and whether health anxiety is a possible mediator, in this relationship.

Methods

A total of 114 Chinese older persons were randomly assigned into three experimental conditions. In two of the conditions, participants were primed with either negative or positive age stereotypes using a sentence unscrambling task, before responding to measures of self-perception of aging, health anxiety, and satisfaction with family and nonfamily support. Those in the control condition responded to the same questions without priming.

Results

Main effects of priming were found across the board except for satisfaction with nonfamily support. In general, participants primed with negative age stereotypes reported more negative self-perception of aging, higher health anxiety, and lower satisfaction with family support, compared with control or those primed with positive age stereotypes. However, the effect on family support satisfaction could not be explained by concomitant experimental effect on health anxiety.

Discussion

The central role of the family as a support provider might be the reason why the activation of negative age stereotypes led to less satisfaction with family, but not nonfamily.
Residual Deterrence
Authors: Dilmé Francesc , Garrett Daniel F
Published: October 2018

Successes of law enforcement in apprehending offenders are often publicized events. Such events have been found to result in temporary reductions in offending, or “residual deterrence”. We provide a theory of residual deterrence that accounts for the incentives of both enforcement officials and potential offenders. We do so by introducing to a standard inspection framework costs that must be incurred to commence enforcement. Such costs in practice include hiring specialized staff, undertaking targeted research and coordinating personnel. We illustrate how our model can be used to address a number of policy questions regarding the optimal design of enforcement authorities.
Spatially resolved star formation and metallicity profiles in post-merger galaxies from MaNGA
Authors: Thorp Mallory D , Ellison Sara L , Simard Luc , Sánchez Sebastian F , Antonio Braulio
Published: October 2018

Large galaxy surveys have demonstrated that galaxy–galaxy mergers can dramatically change the morphologies, star formation rates (SFRs), and metallicities of their constituents. However, most statistical studies have been limited to the measurement of global quantities, through large fibres or integrated colours. In this work, we present the first statistically significant study of spatially resolved star formation and metallicity profiles using integral field spectroscopy, using a sample of ∼20 000 spaxels in 36 visually selected post-merger galaxies from the Mapping Nearby Galaxies at Apache Point Observatory survey. By measuring offsets from SFR and metallicity scaling relations on a spaxel-by-spaxel basis, we are able to quantify where in the galaxy these properties are most affected by the interaction. We find that the SFR enhancements are generally centrally peaked, by a factor of 2.5 on average, in agreement with predictions from simulations. However, there is considerable variation in the SFR behaviour in the galactic outskirts, where both enhancement and suppression are seen. The median SFR remains enhanced by 0.1 dex out to at least 1.9 Re. The metallicity is also affected out to these large radii, typically showing a suppression of ∼−0.04 dex.
Probing the fluctuating ultraviolet background using the Hubble Frontier Fields
Authors: Choudhury Tirthankar Roy , Dayal Pratika
Published: October 2018

In recent years, the rise in the number of Lyman Break Galaxies detected at high redshifts $z$ ≥ 6 has opened up the possibility of understanding early galaxy formation physics in great detail. In particular, the faint-end slope (α) of the ultraviolet luminosity function (UV LF) of these galaxies is a potential probe of feedback effects that suppress star formation in low-mass haloes. In this work, we propose a proof-of-concept calculation for constraining the fluctuating UV background during reionization by constraining α in different volumes of the Universe. Because of patchy reionization, different volumes will experience different amount of photoheating which should lead to a scatter in the measured α. Our approach is based on a simple model of the UV LF that is a scaled version of the halo mass function combined with an exponential suppression in the galaxy luminosity at the faint end because of UV feedback. Although current data are not sufficient to constrain α in different fields, we expect that, in the near future, observations of the six-lensed Hubble Frontier Fields with the James Webb Space Telescope will offer an ideal test of our concept.