bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of variations in structural, optical parameters and bulk etch rate of CR-39 polymer due to electron irradiation
Authors: Sahoo G. S. , Tripathy S. P. , Joshi D. S. , Bandyopadhyay T.
Published: July 2016

In this work, electron induced modifications on the bulk etch rate, structural and optical parameters of CR-39 polymer were studied using gravimetric, FTIR (Fourier Transform Infrared) and UV–vis (Ultraviolet–Visible) techniques, respectively. CR-39 samples were irradiated with 10 MeV electron beam for different durations to have the absorbed doses of 1, 10, 550, 5500, 16 500, and 55 000 kGy. From the FTIR analysis, the peak intensities at different bands were found to be changing with electron dose. A few peaks were observed to shift at high electron doses. From the UV-vis analysis, the optical band gaps for both direct and indirect transitions were found to be decreasing with the increase in electron dose whereas the opacity, number of carbon atoms in conjugation length, and the number of carbon atoms per cluster were found to be increasing. The bulk etch rate was observed to be increasing with the electron dose. The primary objective of this investigation was to study the response of CR-39 to high electron doses and to determine a suitable pre-irradiation condition. The results indicated that, the CR-39 pre-irradiated with electrons can have better sensitivity and thus can be potentially applied for neutron dosimetry.
An optical tweezer in asymmetrical vortex Bessel-Gaussian beams
Authors: Kotlyar V. V. , Kovalev A. A. , Porfirev A. P.
Published: July 2016

We study an optical micromanipulation that comprises trapping, rotating, and transporting 5-μm polystyrene microbeads in asymmetric Bessel-Gaussian (BG) laser beams. The beams that carry orbital angular momentum are generated by means of a liquid crystal microdisplay and focused by a microobjective with a numerical aperture of NA = 0.85. We experimentally show that given a constant topological charge, the rate of microparticle motion increases near linearly with increasing asymmetry of the BG beam. Asymmetric BG beams can be used instead of conventional Gaussian beam for trapping and transferring live cells without thermal damage.
Radiation from laser-microplasma-waveguide interactions in the ultra-intense regime
Authors: Yi Longqing , Pukhov Alexander , Shen Baifei
Published: July 2016

When a high-contrast ultra-relativistic (>1020 W/cm2) laser beam enters a micro-sized plasma waveguide, the pulse energy is coupled into waveguide modes, which significantly modifies the interaction between the electrons and electromagnetic wave. Electrons pulled out from the walls of the waveguide form a dense helical bunch inside the channel and are efficiently accelerated by the transverse magnetic modes to hundreds of MeV. The asymmetry in the transverse electric and magnetic fields drives strong oscillations, which lead to the emission of bright, well-collimated, hard X-rays. In this paper, we present our study on the underlying physics in the aforementioned process using 3D particle-in-cell simulations. The mechanism of electron acceleration and the dependence of radiation properties on different laser plasma parameters are addressed. An analytic model and basic scalings for X-ray emission are also presented by considering the lowest optical modes in the waveguide, which is adequate to describe the basic phenomenon. In addition, the effects of high-order modes as well as laser polarization are also qualitatively discussed. The considered X-ray source has promising features, potentially making it a competitive candidate for a future tabletop synchrotron source.
The impact of positrons beam on the propagation of super freak waves in electron-positron-ion plasmas
Authors: Ali Shan S. , El-Tantawy S. A.
Published: July 2016

In this work, we examine the nonlinear propagation of planar ion-acoustic freak waves in an unmagnetized plasma consisting of cold positive ions and superthermal electrons subjected to cold positrons beam. For this purpose, the reductive perturbation method is used to derive a nonlinear Schrödinger equation (NLSE) for the evolution of electrostatic potential wave. We determine the domain of the plasma parameters where the rogue waves exist. The effect of the positron beam on the modulational instability of the ion-acoustic rogue waves is discussed. It is found that the region of the modulational stability is enhanced with the increase of positron beam speed and positron population. Second as positrons beam increases the nonlinearities of the plasma system, large amplitude ion acoustic rogue waves are pointed out. The present results will be helpful in providing a good fit between the theoretical analysis and real applications in future laboratory plasma experiments.
A Ka-band radial relativistic backward wave oscillator with GW-class output power
Authors: Zhu Jiaxin , Zhang Xiaoping , Dang Fangchao
Published: July 2016

A novel radial relativistic backward wave oscillator with a reflector is proposed and designed to generate GW-level high power microwaves at Ka-band. The segmented radial slow wave structure and the reflector are matched to enhance interaction efficiency. We choose the volume wave TM01 mode as the working mode due to the volume wave characteristic. The main structural parameters of the novel device are optimized by particle-in-cell simulation. High power microwaves with power of 2 GW and a frequency of 29.4 GHz are generated with 30% efficiency when the electron beam voltage is 383 kV, the beam current is 17 kA, and the guiding magnetic field is only 0.6 T. Simultaneously, the highest electric field in the novel Ka-band device is just about 960 kV/cm in second slow wave structure.
The direct criterion of Newcomb for the ideal MHD stability of an axisymmetric toroidal plasma
Authors: Glasser A. H.
Published: July 2016

A method is presented for determining the ideal magnetohydrodynamic stability of an axisymmetric toroidal plasma, based on a toroidal generalization of the method developed by Newcomb for fixed-boundary modes in a cylindrical plasma. For toroidal mode number n≠0, the stability problem is reduced to the numerical integration of a high-order complex system of ordinary differential equations, the Euler-Lagrange equation for extremizing the potential energy, for the coupled amplitudes of poloidal harmonics m as a function of the radial coordinate ψ in a straight-fieldline flux coordinate system. Unlike the cylindrical case, different poloidal harmonics couple to each other, which introduces coupling between adjacent singular intervals. A boundary condition is used at each singular surface, where m = nq and q(ψ) is the safety factor, to cross the singular surface and continue the solutions beyond it. Fixed-boundary instability is indicated by the vanishing of a real determinant of a Hermitian complex matrix constructed from the fundamental matrix of solutions, the generalization of Newcomb's crossing criterion. In the absence of fixed-boundary instabilities, an M × M plasma response matrix WP, with M the number of poloidal harmonics used, is constructed from the Euler-Lagrange solutions at the plasma-vacuum boundary. This is added to a vacuum response matrix WV to form a total response matrix WT. The existence of negative eigenvalues of WT indicates the presence of free-boundary instabilities. The method is implemented in the fast and accurate DCON code.
A novel pyroelectric generator utilising naturally driven temperature fluctuations from oscillating heat pipes for waste heat recovery and thermal energy harvesting
Authors: Zabek D. , Taylor J. , Ayel V. , Bertin Y. , Romestant C. , Bowen C. R.
Published: July 2016

Low temperature thermal to electrical energy converters have the potential to provide a route for recovering waste energy. In this paper, we propose a new configuration of a thermal harvester that uses a naturally driven thermal oscillator free of mechanical motion and operates between a hot heat source and a cold heat sink. The system exploits a heat induced liquid-vapour transition of a working fluid as a primary driver for a pyroelectric generator. The two-phase instability of a fluid in a closed looped capillary channel of an oscillating heat pipe (OHP) creates pressure differences which lead to local high frequency temperature oscillations in the range of 0.1–5 K. Such temperature changes are suitable for pyroelectric thermal to electrical energy conversion, where the pyroelectric generator is attached to the adiabatic wall of the OHP, thereby absorbing thermal energy from the passing fluid. This new pyroelectric-oscillating heat pipe (POHP) assembly of a low temperature generator continuously operates across a spatial heat source temperature of 55 °C and a heat sink temperature of 25 °C, and enables waste heat recovery and thermal energy harvesting from small temperature gradients at low temperatures. Our electrical measurements with lead zirconate titanate (PZT) show an open circuit voltage of 0.4 V (AC) and with lead magnesium niobate–lead titanate (PMN-PT) an open circuit voltage of 0.8 V (AC) at a frequency of 0.45 Hz, with an energy density of 95 pJ cm−3 for PMN-PT. Our novel POHP device therefore has the capability to convert small quantities of thermal energy into more desirable electricity in the nW to mW range and provides an alternative to currently used batteries or centralised energy generation.
Thickness-dependent physical properties of La1/3Sr2/3FeO3 thin films grown on SrTiO3 (001) and (111) substrates
Authors: Minohara Makoto , Kitamura Miho , Wadati Hiroki , Nakao Hironori , Kumai Reiji , Murakami Youichi , Kumigashira Hiroshi
Published: July 2016

We have investigated the thickness-dependent transport properties of La1/3Sr2/3FeO3 thin films grown on SrTiO3 (001) and (111) substrates. At a thickness of ∼40 nm, both films show a clear transition in resistivity associated with the characteristic charge disproportionation at approximately 190 K. The transition temperature of the charge disproportionation is nearly unchanged with decreasing film thickness down to a certain thickness of ∼13 nm for both orientations, while the change in resistivity gradually decreases. Below this thickness, the transition becomes unclear, strongly suggesting the suppression of the charge disproportionation at the critical thickness of ∼13 nm. Furthermore, there is no significant difference in the thickness dependence of La1/3Sr2/3FeO3 thin films between the (001) and (111) orientations. The negligible crystallographic-orientation dependence may reflect the isotropic nature for the domain of charge disproportionation states in La1/3Sr2/3FeO3.
Degradation and annealing effects caused by oxygen in AlGaN/GaN high electron mobility transistors
Authors: Jiang R. , Shen X. , Chen J. , Duan G. X. , Zhang E. X. , Fleetwood D. M. , Schrimpf R. D. , Kaun S. W. , Kyle E. C. H. , Speck J. S. , Pantelides S. T.
Published: July 2016

Hot-carrier degradation and room-temperature annealing effects are investigated in unpassivated ammonia-rich AlGaN/GaN high electron mobility transistors. Devices exhibit a fast recovery when annealed after hot carrier stress with all pins grounded. The recovered peak transconductance can exceed the original value, an effect that is not observed in control passivated samples. Density functional theory calculations suggest that dehydrogenation of pre-existing ON-H defects in AlGaN plays a significant role in the observed hot carrier degradation, and the resulting bare ON can naturally account for the “super-recovery” in the peak transconductance.
Ion velocities in the presheath of electronegative, radio-frequency plasmas measured by low-energy cutoff
Authors: Sobolewski Mark A. , Wang Yicheng , Goyette Amanda
Published: July 2016

Simple kinematic considerations indicate that, under certain conditions in radio-frequency (rf) plasmas, the amplitude of the low-energy peak in ion energy distributions (IEDs) measured at an electrode depends sensitively on ion velocities upstream, at the presheath/sheath boundary. By measuring this amplitude, the velocities at which ions exit the presheath can be determined and long-standing controversies regarding presheath transport can be resolved. Here, IEDs measured in rf-biased, inductively coupled plasmas in CF4 gas determined the presheath exit velocities of all significant positive ions: CF3+, CF2+, CF+, and F+. At higher bias voltages, we detected essentially the same velocity for all four ions. For all ions, measured velocities were significantly lower than the Bohm velocity and the electropositive ion sound speed. Neither is an accurate boundary condition for rf sheaths in electronegative gases: under certain low-frequency, high-voltage criteria defined here, either yields large errors in predicted IEDs. These results indicate that many widely used sheath models will need to be revised.
Temperature dependence of contact resistance at metal/MWNT interface
Authors: Lee Sang-Eui , Moon Kyoung-Seok , Sohn Yoonchul
Published: July 2016

Although contact resistance of carbon nanotube (CNT) is one of the most important factors for practical application of electronic devices, a study regarding temperature dependence on contact resistance of CNTs with metal electrodes has not been found. Here, we report an investigation of contact resistance at multiwalled nanotube (MWNT)/Ag interface as a function of temperature, using MWNT/polydimethylsiloxane (PDMS) composite. Electrical resistance of MWNT/PDMS composite revealed negative temperature coefficient (NTC). Excluding the contact resistance with Ag electrode, the NTC effect became less pronounced, showing lower intrinsic resistivity with the activation energy of 0.019 eV. Activation energy of the contact resistance of MWNT/Ag interface was determined to be 0.04 eV, two times larger than that of MWNT-MWNT network. The increase in the thermal fluctuation assisted electron tunneling is attributed to conductivity enhancement at both MWNT/MWNT and MWNT/Ag interfaces with increasing temperature.
A MEMS thermal shear stress sensor produced by a combination of substrate-free structures with anodic bonding technology
Authors: Ou Yi , Qu Furong , Wang Guanya , Nie Mengyan , Li Zhigang , Ou Wen , Xie Changqing
Published: July 2016

By combining substrate-free structures with anodic bonding technology, we present a simple and efficient micro-electro-mechanical system (MEMS) thermal shear stress sensor. Significantly, the resulting depth of the vacuum cavity of the sensor is determined by the thickness of the silicon substrate at which Si is removed by the anisotropic wet etching process. Compared with the sensor based on a sacrificial layer technique, the proposed MEMS thermal shear-stress sensor exhibits dramatically improved sensitivity due to the much larger vacuum cavity depth. The fabricated MEMS thermal shear-stress sensor with a vacuum cavity depth as large as 525 μm and a vacuum of 5 × 10−2 Pa exhibits a sensitivity of 184.5 mV/Pa and a response time of 180 μs. We also experimentally demonstrate that the sensor power is indeed proportional to the 1/3-power of the applied shear stress. The substrate-free structures offer the ability to precisely measure the shear stress fluctuations in low speed turbulent boundary layer wind tunnels.
Copper vapor-assisted growth of hexagonal graphene domains on silica islands
Authors: Li Jun , Shen Chengmin , Que Yande , Tian Yuan , Jiang Lili , Bao Deliang , Wang Yeliang , Du Shixuan , Gao Hong-Jun
Published: July 2016

Silica (SiO2) islands with a dendritic structure were prepared on polycrystalline copper foil, using silane (SiH4) as a precursor, by annealing at high temperature. Assisted by copper vapor from bare sections of the foil, single-layer hexagonal graphene domains were grown directly on the SiO2 islands by chemical vapor deposition. Scanning electron microscopy, atomic force microscopy, Raman spectra, and X-ray photoelectron spectroscopy confirm that hexagonal graphene domains, each measuring several microns, were synthesized on the silica islands.
Numerical studies of nonlinear ultrasonic guided waves in uniform waveguides with arbitrary cross sections
Authors: Zuo Peng , Zhou Yu , Fan Zheng
Published: July 2016

Nonlinear guided waves have been investigated widely in simple geometries, such as plates, pipe and shells, where analytical solutions have been developed. This paper extends the application of nonlinear guided waves to waveguides with arbitrary cross sections. The criteria for the existence of nonlinear guided waves were summarized based on the finite deformation theory and nonlinear material properties. Numerical models were developed for the analysis of nonlinear guided waves in complex geometries, including nonlinear Semi-Analytical Finite Element (SAFE) method to identify internal resonant modes in complex waveguides, and Finite Element (FE) models to simulate the nonlinear wave propagation at resonant frequencies. Two examples, an aluminum plate and a steel rectangular bar, were studied using the proposed numerical model, demonstrating the existence of nonlinear guided waves in such structures and the energy transfer from primary to secondary modes.
Pressure-induced Td to 1T′ structural phase transition in WTe2
Authors: Zhou Yonghui , Chen Xuliang , Li Nana , Zhang Ranran , Wang Xuefei , An Chao , Zhou Ying , Pan Xingchen , Song Fengqi , Wang Baigeng , Yang Wenge , Yang Zhaorong , Zhang Yuheng
Published: July 2016

WTe2 is provoking immense interest owing to its extraordinary properties, such as large positive magnetoresistance, pressure-driven superconductivity and possible type-II Weyl semimetal state. Here we report results of high-pressure synchrotron X-ray diffraction (XRD), Raman and electrical transport measurements on WTe2. Both the XRD and Raman results reveal a structural transition upon compression, starting at 6.0 GPa and completing above 15.5 GPa. We have determined that the high-pressure lattice symmetry is monoclinic 1T′ with space group of P21/m. This transition is related to a lateral sliding of adjacent Te-W-Te layers and results in a collapse of the unit cell volume by ∼20.5%. The structural transition also casts a pressure range with the broadened superconducting transition, where the zero resistance disappears.
Effect of different rice establishment methods on soil physical properties in drought-prone, rainfed lowlands of Bihar, India
Authors: Mondal Surajit , Kumar Santosh , Haris A. Abdul , Dwivedi S. K. , Bhatt B. P. , Mishra J. S.
Published: July 2016

To enhance productivity, alleviate environmental and management constraints, and enhance farmers’ incomes in the rice–wheat cropping system of the Indo Gangetic Plains, new approaches that are labour-saving, more productive and sustainable need to be developed. Most systems of rice cultivation use puddling to prepare the seedbed and control weeds in rice fields of rainfed, stress-prone environments. This practice might be helpful to reduce weed pressure and obtain slightly higher productivity, but might have negative impacts on soil physical properties. A better understanding is needed of the comparative advantage of unpuddled rice fields for maintaining good soil physical properties. To study the effect of different rice establishment methods on soil physical properties in a rice–wheat cropping system, we analysed soil samples in 2 years (2012–13 and 2013–14) from an experiment testing puddled and unpuddled rice-establishment methods. The treatments were: (i) puddled, transplanted with best management practices; (ii) puddled, transplanted with the system of rice intensification; (iii) unpuddled, transplanted; and (iv) unpuddled, direct-seeded. Omission of puddling improved soil physical properties such as bulk density, penetration resistance, aggregation stability and cracking behaviour. The absence of soil disturbance also improved soil aggregation, average mean-weight diameter and water-stable aggregates. Thus, unpuddled conditions increased the macro-aggregate fraction by 18–33%. By contrast, the higher frequency of smaller macro-aggregates (0.053–0.25 mm diameter) in puddled conditions clearly indicated the breakdown of larger macro-aggregates (>0.25 mm) into smaller size fractions. Puddled treatments were also characterised by a hard pan and wider, longer and deeper cracks, with a crack volume more than three times higher in puddled conditions. Unpuddled treatments recorded slightly higher nutrient contents in the topsoil. The study reveals that puddling deteriorates soil health. However, a long-term study is required for a better understanding of the soil changes related to different rice establishment technologies.
Lmx1a and Lmx1b regulate mitochondrial functions and survival of adult midbrain dopaminergic neurons
Authors: Doucet-Beaupré Hélène , Gilbert Catherine , Profes Marcos Schaan , Chabrat Audrey , Pacelli Consiglia , Giguère Nicolas , Rioux Véronique , Charest Julien , Deng Qiaolin , Laguna Ariadna , Ericson Johan , Perlmann Thomas , Ang Siew-Lan , Cicchetti Francesca , Parent Martin , Trudeau Louis-Eric , Lévesque Martin
Published: July 2016

Significance

Degeneration of midbrain dopamine neurons is the main pathological hallmark of Parkinson’s disease. Identifying transcriptional programs that maintain these neurons in the adult brain will help us understand their specific vulnerability. Here, we show that the survival of dopaminergic neurons requires the ongoing action of LIM-homeodomain transcription factors Lmx1a and Lmx1b. We discovered an Lmx1a/b-dependent pathway maintaining mitochondrial functions in midbrain dopaminergic neurons. Accordingly, ablation of
Lmx1a/b
results in impaired respiratory chain activity, increased oxidative stress, and mitochondrial DNA damage and causes Lewy neurite-like pathology. Importantly, deletion of
Lmx1a/b
links metabolic impairment, α-synuclein inclusions, and progressive neuronal loss. Modulation of this pathway opens new strategies to slow down or prevent the death of vulnerable neurons in Parkinson’s disease.
Single-molecule imaging reveals a common mechanism shared by G-quadruplex–resolving helicases
Authors: Tippana Ramreddy , Hwang Helen , Opresko Patricia L. , Bohr Vilhelm A. , Myong Sua
Published: July 2016

Significance

G-quadruplex (GQ) is a four-stranded DNA structure that forms in the human genome and influences gene expression and DNA replication. Stably formed GQ structures can act as a physical blockade to disrupt genomic processes. To counteract such an effect, cells possess special helicases dedicated to unfolding GQ structures. In our study, we examined three such GQ-resolving helicases, using single-molecule imaging, that show distinct binding preference to different conformations (folding directions) of GQ DNA. Nevertheless, all three GQ resolvases use the same mechanism, which involves repetitive cycles of GQ unfolding in successive runs. Such activity leads to efficient GQ hybridization with a complementary DNA and dislodging chemical GQ ligand. Our findings have implications for designing new GQ ligands for therapeutic purposes.
The novel regulatory ncRNA, NfiS, optimizes nitrogen fixation via base pairing with the nitrogenase gene
nifK
mRNA in
Pseudomonas stutzeri
A1501
Authors: Zhan Yuhua , Yan Yongliang , Deng Zhiping , Chen Ming , Lu Wei , Lu Chao , Shang Liguo , Yang Zhimin , Zhang Wei , Wang Wei , Li Yun , Ke Qi , Lu Jiasi , Xu Yuquan , Zhang Liwen , Xie Zhihong , Cheng Qi , Elmerich Claudine , Lin Min
Published: July 2016

Significance

The biological nitrogen fixation process responsible for the reduction of atmospheric nitrogen to ammonia represents the primary source of nitrogen supporting extant life. We have identified a novel noncoding RNA (ncRNA) in the
Pseudomonas stutzeri
core genome, called NfiS, that is involved in the stress response and controls the expression of genes located in a genomic nitrogen-fixing (
nif
) island. NfiS was found to optimize nitrogen fixation by the direct posttranscriptional regulation of nitrogenase gene
nifK
mRNA. The acquisition of the
nif
island and the recruitment of NfiS by
nifK
mRNA are evolutionary events that seem to contribute to fine-tuned regulation of nitrogenase activity in
P. stutzeri
. This study provides a new regulatory pathway, mediated by an ncRNA for optimal nitrogen fixation, that may operate in other diazotrophs.
DNA damage tolerance pathway involving DNA polymerase ι and the tumor suppressor p53 regulates DNA replication fork progression
Authors: Hampp Stephanie , Kiessling Tina , Buechle Kerstin , Mansilla Sabrina F. , Thomale Jürgen , Rall Melanie , Ahn Jinwoo , Pospiech Helmut , Gottifredi Vanesa , Wiesmüller Lisa
Published: July 2016

Significance

DNA damage tolerance pathways like translesion synthesis and recombination facilitate the bypass of replication-blocking lesions. Such events are crucial for the survival of rapidly proliferating cells, including cancer and stem cells undergoing active duplication during tissue renewal. Herein, we characterize an unprecedented damage tolerance pathway that requires the combined function of a highly enigmatic translesion DNA polymerase ι (POLι) and the so-called guardian-of-the-genome, p53. We provide evidence demonstrating that p53 complexed with POLι triggers idling events that decelerate nascent DNA elongation at replication barriers, facilitating the resolution of stalled forks by specialized structure-specific enzymes. Our findings implicate p53 in the protection of quickly growing cancer and stem cells from endogenous and exogenous sources of replication stress.
Minimal basilar membrane motion in low-frequency hearing
Authors: Warren Rebecca L. , Ramamoorthy Sripriya , Ciganović Nikola , Zhang Yuan , Wilson Teresa M. , Petrie Tracy , Wang Ruikang K. , Jacques Steven L. , Reichenbach Tobias , Nuttall Alfred L. , Fridberger Anders
Published: July 2016

Significance

To perceive speech, the brain relies on inputs from sensory cells located near the top of the spiral-shaped cochlea. This low-frequency region of the inner ear is anatomically difficult to access, and it has not previously been possible to study its mechanical response to sound in intact preparations. Here, we used optical coherence tomography to image sound-evoked vibration inside the intact cochlea. We show that low-frequency sound moves a small portion of the basilar membrane, and that the motion declines in an exponential manner across the basilar membrane. Hence, the response of the hearing organ to speech-frequency sounds is different from the one evident in high-frequency cochlear regions.
Referring expressions and executive functions in bilingualism
Authors: Sorace Antonella
Published: July 2016

Recent research has shown that the bilingual experience has positive effects on non-linguistic cognition (Bialystok 2009; Costa and Sebastian-Gallés 2014) but also negative effects on language, for example on vocabulary size and lexical fluency (Pearson et al. 1993). While most of the linguistic ‘disadvantages’ of bilingualism have been discussed in the lexical domain, this question is scaled up here to the sentence level and a novel theoretical framework is proposed which explicitly connects psychological and linguistic research. It is suggested that the bilingual experience may (a) affect the reciprocal interactions between language and general cognition, and (b) modulate the relation between components of executive functions. These effects may in turn influence the processing of particular linguistic structures, such as anaphoric expressions, and lead to bilingual-monolingual differences that could be regarded as ‘disadvantages’ but are in fact the result of normal adaptive changes due to the bilingual experience. Future experimental research validating this proposal may benefit both linguistic models of anaphora resolution and psychological models of cognitive control in monolinguals and bilinguals.
Naming Patterns in Rural South-Central Nebraska
Authors: Obasi Sharon N.
Published: July 2016

A common strategy in naming a newborn is “namesaking,” that is, the practice of naming the newborn after a specific family member. Namesaking may be considered a unique form of parental investment, advertising the connection between the newborn and specific kinfolk. Namesaking patterns were assessed in rural, south-central Nebraska by examining 841 birth announcements printed in a local newspaper during the calendar years 1994 and 2014. Results indicated that male newborns were significantly more likely to be namesaked than female newborns; first-born children were more likely to be namesaked than later-born children; and namesaked newborns were more likely to be named after paternal relatives than maternal relatives. These findings suggest that namesaking may be a way of preserving familial connections within rural, south-central Nebraska.
Electropolishing of surfaces: theory and applications
Authors: Yang G. , Wang B. , Tawfiq K. , Wei H. , Zhou S. , Chen G.
Published: July 2016

Electropolishing is the electrochemical process to remove the metallic material from the workpiece, in order to obtain a smoother metal surface. It has found vast engineering applications in many fields, such as food, medical, pharmaceutical and semiconductor industries. This review is aimed to provide the readership with insightful understanding of the electropolishing process, from the fundamental aspects as well as from the application aspects. The general aspects of electropolishing, including its definition, the classic setup, the fundamentals behind it and methods used to evaluate the electropolishing finishes are reviewed here. Various electropolishing theories, be them quantitative or qualitative are briefly discussed. Based on those theories, important parameters evolved in the electropolishing process are enumerated. Many microscopic technologies are used to evaluate the electropolishing surface finishes. This includes optical microscope, electron microscope and atomic force microscope. Some key features of electropolishing are briefly outlined in the end.
Bromine doping effect on some properties of CdS films
Authors: Narasimman V. , Nagarethinam V. S. , Selvan G. , Abubacker M. P. , Balu A. R.
Published: July 2016

The suitability of bromine as an anionic dopant influencing the properties of CdS thin films is discussed in this paper. The as-deposited films were characterised respectively by XRD, SEM, UV-vis-NIR spectrophotometer and two-point probe setup. All the films appear to be polycrystalline in nature exhibiting hexagonal crystal structure with a (002) preferential growth texture. The 2 θ value of the (002) plane shifts towards lower Bragg angle with doping inferring an expansion in their lattice volumes. Increased transparency and blue shift in optical band gap value are observed for the doped films. Electrical resistivity decreased with increase in Br-doping concentration. Increased transparency, widened band gap and decreased electrical resistivity values achieved confirm that Br is a suitable anionic dopant that can strongly influence the physical properties of pure CdS towards future optoelectronic devices.
Optimal welding parameters for small-scale resistance spot welding with response surface methodology
Authors: Yue X. K. , Tong G. Q. , Chen F. , Ma X. L. , Gao X. P.
Published: July 2016

In this study, Ti–1Al–1Mn thin foils with thickness of 0.05 mm were welded by small-scale resistance spot welding. Welding current, electrode force and welding time have been changed while other welding parameters remained constant. The welded joints were subjected to tensile shear tests for determining the values of shear force and absorption energy. A quadratic model of response surface methodology based on Box–Behnken design was employed in establishing regression equations between input variables (current, electrode force and time) and output variables (shear force, absorption energy, variance of shear force and variance of absorption energy). The models were satisfied in optimising the welding parameters. Besides, the microstructure analysis on the typical spot welds was also conducted.

GRAPHICAL ABSTRACT
Combined effects of crystallography, heat treatment and surface polishing on blistering in tungsten exposed to high-flux deuterium plasma
Authors: Zayachuk Y. , Tanyeli I. , Van Boxel S. , Bystrov K. , Morgan T.W. , Roberts S.G.
Published: July 2016

For tungsten exposed to low-energy hydrogen-plasmas, it has been thought that grains with

〈

1
 
 
1
 
 
1

〉

surface normal are most susceptible to blistering while those with

〈

0
 
0
 
 
1

〉

surface normal are virtually impervious to it. Here, we report results showing that non-uniformity of blister distribution depends on the state of the surface due to polishing. In electrochemically polished material blisters appear on the grains with all orientations, while in mechanically polished material blister-free areas associated with particular orientations emerge. On the other hand, blistering is shown to have a strong dependence on the level of deformation within particular grains in partially recrystallized material.
Short relaxation times but long transient times in both simple and complex reaction networks
Authors: Henry Adrien , Martin Olivier C.
Published: July 2016

When relaxation towards an equilibrium or steady state is exponential at large times, one usually considers that the associated relaxation time
τ
, i.e. the inverse of the decay rate, is the longest characteristic time in the system. However, that need not be true, other times such as the
lifetime
of an infinitesimal perturbation can be much longer. In the present work, we demonstrate that this paradoxical property can arise even in quite simple systems such as a linear chain of reactions obeying mass action (MA) kinetics. By mathematical analysis of simple reaction networks, we pin-point the reason why the standard relaxation time does not provide relevant information on the potentially long transient times of typical infinitesimal perturbations. Overall, we consider four characteristic times and study their behaviour in both simple linear chains and in more complex reaction networks taken from the publicly available database ‘Biomodels’. In all these systems, whether involving MA rates, Michaelis–Menten reversible kinetics, or phenomenological laws for reaction rates, we find that the characteristic times corresponding to lifetimes of tracers and of concentration perturbations can be significantly longer than
τ
.
Allosteric inhibition of Aurora-A kinase by a synthetic vNAR domain
Authors: Burgess Selena G. , Oleksy Arkadiusz , Cavazza Tommaso , Richards Mark W. , Vernos Isabelle , Matthews David , Bayliss Richard
Published: July 2016

The vast majority of clinically approved protein kinase inhibitors target the ATP-binding pocket directly. Consequently, many inhibitors have broad selectivity profiles and most have significant off-target effects. Allosteric inhibitors are generally more selective, but are difficult to identify because allosteric binding sites are often unknown or poorly characterized. Aurora-A is activated through binding of TPX2 to an allosteric site on the kinase catalytic domain, and this knowledge could be exploited to generate an inhibitor. Here, we generated an allosteric inhibitor of Aurora-A kinase based on a synthetic, vNAR single domain scaffold, vNAR-D01. Biochemical studies and a crystal structure of the Aurora-A/vNAR-D01 complex show that the vNAR domain overlaps with the TPX2 binding site. In contrast with the binding of TPX2, which stabilizes an active conformation of the kinase, binding of the vNAR domain stabilizes an inactive conformation, in which the αC-helix is distorted, the canonical Lys-Glu salt bridge is broken and the regulatory (R-) spine is disrupted by an additional hydrophobic side chain from the activation loop. These studies illustrate how single domain antibodies can be used to characterize the regulatory mechanisms of kinases and provide a rational basis for structure-guided design of allosteric Aurora-A kinase inhibitors.
Gestational experience alters sex allocation in the subsequent generation
Authors: Edwards A. M. , Cameron E. Z. , Pereira J. C. , Wapstra E. , Ferguson-Smith M. A. , Horton S. R. , Thomasson K.
Published: July 2016

Empirical tests of adaptive maternal sex allocation hypotheses have presented inconsistent results in mammals. The possibility that mothers are constrained in their ability to adjust sex ratios could explain some of the remaining variation. Maternal effects, the influence of the maternal phenotype or genotype on her developing offspring, may constrain sex allocation through physiological changes in response to the gestational environment. We tested if maternal effects constrain future parental sex allocation through a lowered gestational stress environment in laboratory mice. Females that experienced lowered stress as embryos
in utero
gave birth to female-biased litters as adults, with no change to litter size. Changes in offspring sex ratio was linked to peri-conceptual glucose, as those females that had increasing blood glucose peri-conceptionally gave birth to litters with a higher male to female sex ratio. There was, however, no effect of the lowered prenatal stress for developing male embryos and their sperm sex ratio when adult. We discuss the implications of maternal effects and maternal stress environment on the lifelong physiology of the offspring, particularly as a constraint on later maternal sex allocation.
Social networks predict selective observation and information spread in ravens
Authors: Kulahci Ipek G. , Rubenstein Daniel I. , Bugnyar Thomas , Hoppitt William , Mikus Nace , Schwab Christine
Published: July 2016

Animals are predicted to selectively observe and learn from the conspecifics with whom they share social connections. Yet, hardly anything is known about the role of different connections in observation and learning. To address the relationships between social connections, observation and learning, we investigated transmission of information in two raven (
Corvus corax
) groups. First, we quantified social connections in each group by constructing networks on affiliative interactions, aggressive interactions and proximity. We then seeded novel information by training one group member on a novel task and allowing others to observe. In each group, an observation network based on who observed whose task-solving behaviour was strongly correlated with networks based on affiliative interactions and proximity. Ravens with high social centrality (strength, eigenvector, information centrality) in the affiliative interaction network were also central in the observation network, possibly as a result of solving the task sooner. Network-based diffusion analysis revealed that the order that ravens first solved the task was best predicted by connections in the affiliative interaction network in a group of subadult ravens, and by social rank and kinship (which influenced affiliative interactions) in a group of juvenile ravens. Our results demonstrate that not all social connections are equally effective at predicting the patterns of selective observation and information transmission.
A topological study of gravity free-surface waves generated by bluff bodies using the method of steepest descents
Authors: Trinh Philippe H.
Published: July 2016

The standard analytical approach for studying steady gravity free-surface waves generated by a moving body often relies upon a linearization of the physical geometry, where the body is considered asymptotically small in one or several of its dimensions. In this paper, a methodology that avoids any such geometrical simplification is presented for the case of steady-state flows at low speeds. The approach is made possible through a reduction of the water-wave equations to a complex-valued integral equation that can be studied using the method of steepest descents. The main result is a theory that establishes a correspondence between different bluff-bodied free-surface flow configurations, with the topology of the Riemann surface formed by the steepest descent paths. Then, when a geometrical feature of the body is modified, a corresponding change to the Riemann surface is observed, and the resultant effects to the water waves can be derived. This visual procedure is demonstrated for the case of two-dimensional free-surface flow past a surface-piercing ship and over an angled step in a channel.
Nonlinear stratospheric variability: multifractal de-trended fluctuation analysis and singularity spectra
Authors: Badin Gualtiero , Domeisen Daniela I. V.
Published: July 2016

Characterizing the stratosphere as a turbulent system, temporal fluctuations often show different correlations for different time scales as well as intermittent behaviour that cannot be captured by a single scaling exponent. In this study, the different scaling laws in the long-term stratospheric variability are studied using multifractal de-trended fluctuation analysis (MF-DFA). The analysis is performed comparing four re-analysis products and different realizations of an idealized numerical model, isolating the role of topographic forcing and seasonal variability, as well as the absence of climate teleconnections and small-scale forcing. The Northern Hemisphere (NH) shows a transition of scaling exponents for time scales shorter than about 1 year, for which the variability is multifractal and scales in time with a power law corresponding to a red spectrum, to longer time scales, for which the variability is monofractal and scales in time with a power law corresponding to white noise. Southern Hemisphere (SH) variability also shows a transition at annual scales. The SH also shows a narrower dynamical range in multifractality than the NH, as seen in the generalized Hurst exponent and in the singularity spectra. The numerical integrations show that the models are able to reproduce the low-frequency variability but are not able to fully capture the shorter term variability of the stratosphere.
Influence of dopant substitution mechanism on catalytic properties within hierarchical architectures
Authors: Newland Stephanie H. , Sinkler Wharton , Mezza Thomas , Bare Simon R. , Raja Robert
Published: July 2016

A range of hierarchically porous (HP) AlPO-5 catalysts, with isomorphously substituted transition metal ions, have been synthesized using an organosilane as a soft template. By employing a range of structural and spectroscopic characterization protocols, the properties of the dopant-substituted species within the HP architectures have been carefully evaluated. The resulting nature of the active site is shown to have a direct impact on the ensuing catalytic properties in the liquid-phase Beckmann rearrangement of cyclic ketones.
Interaction between mean flow and turbulence in two dimensions
Authors: Falkovich Gregory
Published: July 2016

This short note is written to call attention to an analytic approach to the interaction of developed turbulence with mean flows of simple geometry (jets and vortices). It is instructive to compare cases in two and three dimensions and see why the former are solvable and the latter are not (yet). We present the analytical solutions for two-dimensional mean flows generated by an inverse turbulent cascade on a sphere and in planar domains of different aspect ratios. These solutions are obtained in the limit of small friction when the flow is strong while turbulence can be considered weak and treated perturbatively. I then discuss when these simple solutions can be realized and when more complicated flows may appear instead. The next step of describing turbulence statistics inside a flow and directions of possible future progress are briefly discussed at the end.
Larval food quantity affects the capacity of adult mosquitoes to transmit human malaria
Authors: Shapiro Lillian L. M. , Murdock Courtney C. , Jacobs Gregory R. , Thomas Rachel J. , Thomas Matthew B.
Published: July 2016

Adult traits of holometabolous insects are shaped by conditions experienced during larval development, which might impact interactions between adult insect hosts and parasites. However, the ecology of larval insects that vector disease remains poorly understood. Here, we usedAnopheles stephensimosquitoes and the human malaria parasitePlasmodium falciparum,to investigate whether larval conditions affect the capacity of adult mosquitoes to transmit malaria. We reared larvae in two groups; one group received a standard laboratory rearing diet, whereas the other received a reduced diet. Emerging adult females were then provided an infectious blood meal. We assessed mosquito longevity, parasite development rate and prevalence of infectious mosquitoes over time. Reduced larval food led to increased adult mortality and caused a delay in parasite development and a slowing in the rate at which parasites invaded the mosquito salivary glands, extending the time it took for mosquitoes to become infectious. Together, these effects increased transmission potential of mosquitoes in the high food regime by 260–330%. Such effects have not, to our knowledge, been shown previously for human malaria and highlight the importance of improving knowledge of larval ecology to better understand vector-borne disease transmission dynamics.
Proline as a fuel for insect flight: enhancing carbohydrate oxidation in hymenopterans
Authors: Teulier Loïc , Weber Jean-Michel , Crevier Julie , Darveau Charles-A.
Published: July 2016

Bees are thought to be strict users of carbohydrates as metabolic fuel for flight. Many insects, however, have the ability to oxidize the amino acid proline at a high rate, which is a unique feature of this group of animals. The presence of proline in the haemolymph of bees and in the nectar of plants led to the hypothesis that plants may produce proline as a metabolic reward for pollinators. We investigated flight muscle metabolism of hymenopteran species using high-resolution respirometry performed on permeabilized muscle fibres. The muscle fibres of the honeybee,Apis mellifera, do not have a detectable capacity to oxidize proline, as those from the migratory locust,Locusta migratoria, used here as an outgroup representative. The closely related bumblebee,Bombus impatiens, can oxidize proline alone and more than doubles its respiratory capacity when proline is combined with carbohydrate-derived substrates. A distant wasp species,Vespula vulgaris, exhibits the same metabolic phenotype as the bumblebee, suggesting that proline oxidation is common in hymenopterans. Using a combination of mitochondrial substrates and inhibitors, we further show that inB. impatiens, proline oxidation provides reducing equivalents and electrons directly to the electron transport system. Together, these findings demonstrate that some bee and wasp species can greatly enhance the oxidation of carbohydrates using proline as fuel for flight.
Unravelling anisogamy: egg size and ejaculate size mediate selection on morphology in free-swimming sperm
Authors: Monro Keyne , Marshall Dustin J.
Published: July 2016

Gamete dimorphism (anisogamy) defines the sexes in most multicellular organisms. Theoretical explanations for its maintenance usually emphasize the size-related selection pressures of sperm competition and zygote survival, assuming that fertilization of all eggs precludes selection for phenotypes that enhance fertility. In external fertilizers, however, fertilization is often incomplete due to sperm limitation, and the risk of polyspermy weakens the advantage of high sperm numbers that is predicted to limit sperm size, allowing alternative selection pressures to target free-swimming sperm. We asked whether egg size and ejaculate size mediate selection on the free-swimming sperm of
Galeolaria caespitosa
, a marine tubeworm with external fertilization, by comparing relationships between sperm morphology and male fertility across manipulations of egg size and sperm density. Our results suggest that selection pressures exerted by these factors may aid the maintenance of anisogamy in external fertilizers by limiting the adaptive value of larger sperm in the absence of competition. In doing so, our study offers a more complete explanation for the stability of anisogamy across the range of sperm environments typical of this mating system and identifies new potential for the sexes to coevolve via mutual selection pressures exerted by gametes at fertilization.