bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the inner parsecs of active galactic nuclei using near-infrared high resolution polarimetric simulations with
MontAGN
Authors: Grosset L. , Rouan D. , Gratadour D. , Pelat D. , Orkisz J. , Marin F. , Goosmann R.
Published: December 2017

Aims. In this paper we aim to constrain the properties of dust structures in the central first parsecs of active galactic nuclei (AGN). Our goal is to study the required optical depth and composition of different dusty and ionised structures.

Methods. We developed a radiative transfer code called Monte Carlo for Active Galactic Nuclei (MontAGN), which is optimised for polarimetric observations in the infrared. With both this code and STOKES, designed to be relevant from the hard X-ray band to near-infrared wavelengths, we investigate the polarisation emerging from a characteristic model of the AGN environment. For this purpose, we compare predictions of our models with previous infrared observations of NGC 1068, and try to reproduce several key polarisation patterns revealed by polarisation mapping.

Results. We constrain the required dust structures and their densities. More precisely, we find that the electron density inside the ionisation cone is about 2.0 × 109 m−3. With structures constituted of spherical grains of constant density, we also highlight that the torus should be thicker than 20 in term of K-band optical depth to block direct light from the centre. It should also have a stratification in density: a less dense outer rim with an optical depth at 2.2 μm typically between 0.8 and 4 for observing the double scattering effect previously proposed.

Conclusions. We bring constraints on the dust structures in the inner parsecs of an AGN model supposed to describe NGC 1068. When compared to observations, this leads to an optical depth of at least 20 in the Ks band for the torus of NGC 1068, corresponding to τV ≈ 170, which is within the range of current estimation based on observations. In the future, we will improve our study by including non-uniform dust structures and aligned elongated grains to constrain other possible interpretations of the observations.
Orbital Paraganglioma: A Systematic Review
Authors: Huang Natalie , Rayess Hani , Svider Peter , Rayess Nadim , Folbe Adam , Langer Paul , Eloy Jean-Anderson , Carron Michael
Published: December 2017

Purpose The purpose of this study was to perform a systematic review of the literature on orbital paragangliomas, evaluating clinical presentation, diagnosis, management patterns, and prognosis.

Methods The systematic review was conducted based on the principles described in the Preferred Reporting Items for Systematic Reviews and Meta-Analysis. PubMed, Cochrane databases, Embase, and Web of Science were searched for articles related to orbital paragangliomas. Inclusion criteria included English language articles with original reports on human subjects. Data on clinical presentation, diagnosis, treatment, and prognosis were collected.

Results Twenty-seven articles met inclusion criteria (28 total patients). The mean patient age was 37.1 years (range, 3–75 years); 13 (46.4%) patients were male. The most common presenting symptoms were proptosis (89.2%), visual acuity changes (67.9%), and extraocular muscle restriction (64.2%). Lesions were most commonly intraconal (92.9%). Single modality therapy was employed in 19 patients (67.9%), including excision in 12 patients (42.9%) and exenteration in 5 patients (17.9%). Ten patients (35.7%) developed recurrence, and there was a 92.9% survival rate (mean follow-up, 29 months).

Conclusion Orbital paragangliomas are rare tumors with an excellent prognosis. These lesions commonly present with proptosis, and are primarily managed surgically with simple excision, although exenteration and adjuvant radiation may be necessary for invasive tumors. This series is the largest and most comprehensive systematic review of orbital paragangliomas conducted to date.
A critical analysis of some popular methods for the discretisation of the gradient operator in finite volume methods
Authors: Syrakos Alexandros , Varchanis Stylianos , Dimakopoulos Yannis , Goulas Apostolos , Tsamopoulos John
Published: December 2017

Finite volume methods (FVMs) constitute a popular class of methods for the numerical simulation of fluid flows. Among the various components of these methods, the discretisation of the gradient operator has received less attention despite its fundamental importance with regards to the accuracy of the FVM. The most popular gradient schemes are the divergence theorem (DT) (or Green-Gauss) scheme and the least-squares (LS) scheme. Both are widely believed to be second-order accurate, but the present study shows that in fact the common variant of the DT gradient is second-order accurate only on structured meshes whereas it is zeroth-order accurate on general unstructured meshes, and the LS gradient is second-order and first-order accurate, respectively. This is explained through a theoretical analysis and is confirmed by numerical tests. The schemes are then used within a FVM to solve a simple diffusion equation on unstructured grids generated by several methods; the results reveal that the zeroth-order accuracy of the DT gradient is inherited by the FVM as a whole, and the discretisation error does not decrease with grid refinement. On the other hand, use of the LS gradient leads to second-order accurate results, as does the use of alternative, consistent, DT gradient schemes, including a new iterative scheme that makes the common DT gradient consistent at almost no extra cost. The numerical tests are performed using both an in-house code and the popular public domain partial differential equation solver OpenFOAM.
Exact solutions for two-body problems in 1D deformed space with minimal length
Authors: Samar M. I. , Tkachuk V. M.
Published: December 2017

We reduce the two-body problem to the one-body problem in the general case of a deformed Heisenberg algebra leading to minimal length. Two-body problems with delta and Coulomb-like interactions are solved exactly. We obtain an analytical expression for the energy spectrum for partial cases of deformation function. The dependence of the energy spectrum on the center-of-mass momentum is found. For the special case of deformation function, which corresponds to a cutoff procedure in momentum space, it is shown that this dependence is more likely to be observed for identical particles.
Elasto-inertial migration of deformable capsules in a microchannel
Authors: Raffiee Amir Hossein , Dabiri Sadegh , Ardekani Arezoo M.
Published: December 2017

In this paper, we study the dynamics of deformable cells in a channel flow of Newtonian and polymeric fluids and unravel the effects of deformability, elasticity, inertia, and size on the cell motion. We investigate the role of polymeric fluids on the cell migration behavior and the performance of inertial microfluidic devices. Our results show that the equilibrium position of the cell is on the channel diagonal, in contrast to that of rigid particles, which is on the center of the channel faces for the same range of Reynolds number. A constant-viscosity polymeric fluid, modeled using an Oldroyd-B constitutive equation, drives the cells toward the channel centerline, while a shear-thinning polymeric fluid, modeled using a Giesekus constitutive equation, pushes the cells toward the channel wall. The findings of this paper suggest that the addition of polymers in microfluidic devices can be used to enhance the throughput of cell focusing and separation devices at a low cost. This study provides an insight on the role of rheological properties of the fluid and the ways that they can be tuned to control the focal position of the cells.
Water nanoelectrolysis: A simple model
Authors: Olives Juan , Hammadi Zoubida , Morin Roger , Lapena Laurent
Published: December 2017

A simple model of water nanoelectrolysis—defined as the nanolocalization at a single point of any electrolysis phenomenon—is presented. It is based on the electron tunneling assisted by the electric field through the thin film of water molecules (∼0.3 nm thick) at the surface of a tip-shaped nanoelectrode (micrometric to nanometric curvature radius at the apex). By applying, e.g., an electric potential V1 during a finite time t1, and then the potential −V1 during the same time t1, we show that there are three distinct regions in the plane (t1, V1): one for the nanolocalization (at the apex of the nanoelectrode) of the electrolysis oxidation reaction, the second one for the nanolocalization of the reduction reaction, and the third one for the nanolocalization of the production of bubbles. These parameters t1 and V1 completely control the time at which the electrolysis reaction (of oxidation or reduction) begins, the duration of this reaction, the electrolysis current intensity (i.e., the tunneling current), the number of produced O2 or H2 molecules, and the radius of the nanolocalized bubbles. The model is in good agreement with our experiments.
Energy production potential and economic viability of grid-connected wind/PV systems at Saudi Arabian coastal areas
Authors: Ramli Makbul A. M. , Twaha Ssennoga , Alghamdi Abdulaziz U.
Published: December 2017

This paper analyzes the electricity production potential and economic viability of grid-connected wind/photovoltaic (PV) energy systems at two coastal cities, Yanbu and Dhahran in Saudi Arabia. First, wind energy is assessed based on the hourly wind speed observation data recorded over the entire year 2013 in the selected locations. Electricity generation potential is estimated using two wind turbines: Vestas V82 and V90 models. The results indicate that both locations have sufficient wind resources for wind turbine operation. Strong wind resources are more common at Dhahran than at Yanbu with wind speeds above 3.5 m/s, accounting for 60.12% of the wind data at Dhahran, which is higher than 51.2% of Yanbu. Grid-connected hybrid systems using Vestas V90 wind turbines had the highest net present cost (NPC) compared with other configurations. The inclusion of battery storage units slightly increases the NPC. Surprisingly, systems with the highest NPC produced the least electricity. In contrast, cheaper V82-based systems had the lowest NPC and levelized cost of energy and produced the most electricity. Hence, a grid-connected wind/PV system using V82 turbines is most economically viable. Incorporating a small battery storage unit in the systems minimizes capacity shortages and improves reliability at minimal extra cost. Using different wind turbines with a lower cut-in speed of 3 m/s could increase the electricity production, as 9.1% and 10.3% of wind observations at Yanbu and Dhahran, respectively, had a wind speed of 3 m/s.
Supersonic plasma beams with controlled speed generated by the alternative low power hybrid ion engine (ALPHIE) for space propulsion
Authors: Conde L. , Domenech-Garret J. L. , Donoso J. M. , Damba J. , Tierno S. P. , Alamillo-Gamboa E. , Castillo M. A.
Published: December 2017

The characteristics of supersonic ion beams from the alternative low power hybrid ion engine (ALPHIE) are discussed. This simple concept of a DC powered plasma accelerator that only needs one electron source for both neutral gas ionization and ion beam neutralization is also examined. The plasma production and space charge neutralization processes are thus coupled in this plasma thruster that has a total DC power consumption of below 450 W, and uses xenon or argon gas as a propellant. The operation parameters of the plasma engine are studied in the laboratory in connection with the ion energy distribution function obtained with a retarding-field energy analyzer. The ALPHIE plasma beam expansion produces a mesothermal plasma flow with two-peaked ion energy distribution functions composed of low and high speed ion groups. The characteristic drift velocities of the fast ion groups, in the range 36.6–43.5 Km/s, are controlled by the acceleration voltage. These supersonic speeds are higher than the typical ion sound velocities of the low energy ion group produced by the expansion of the plasma jet. The temperatures of the slow ion population lead to ion Debye lengths longer than the electron Debye lengths. Furthermore, the electron impact ionization can coexist with collisional ionization by fast ions downstream the grids. Finally, the performance characteristics and comparisons with other plasma accelerator schemes are also discussed.
Modulation of structural, electrical, and magnetic features with dilute Zr substitution in Bi0.8La0.2Fe1-xZrxO3 system
Authors: Usama Hasan M. , Akter Ayesha , Zubair M. A.
Published: December 2017

A significant structural modification and enhancement of the electrical and magnetic properties with dilute substitution of Zr (≤1 mol. %) in the Bi0.8La0.2Fe1-xZrxO3 system has been reported. A mixture of rhombohedral and orthorhombic phases was detected in these conventionally sintered ceramics. Transition from a leaky state to an insulating state was observed upon Zr substitution. This is the first time that a drop in the electrical conductivity as large as 6 orders of magnitude for doping as small as 0.25 mol. % in bismuth ferrite systems has been reported. An investigation on the nature of this abrupt transition revealed the dominant role of defects. A proper consideration of possible defect reactions taking place during and after sintering satisfactorily accounts for the observed modulation in the electrical properties. Both AC and DC measurements indicate that, before Zr substitution, p-type hopping conduction prevails with an activation energy as low as ∼0.57 eV, whereas the Zr substitution makes oxide ion migration the central mechanism for conduction with the activation energy of ∼0.96–1.08 eV. In contrast to that, the magnetic properties of the compounds experience a more subtle effect; a gradual modification of saturation magnetization and coercivity with Zr substitution is observed. Curve fitting of the magnetic hysteresis loops not only allowed extraction of three separate contributions from the magnetic response but also helped to explain the effects of Zr on the magnetic properties. Modifications of structural characteristics and magnetic anisotropy of the samples are believed to be the primary driving force behind the improvement in the magnetic properties.
An integrated multi-source energy harvester based on vibration and magnetic field energy
Authors: Hu Zhengwen , Qiu Jing , Wang Xian , Gao Yuan , Liu Xin , Chang Qijie , Long Yibing , He Xingduo
Published: December 2017

In this paper, an integrated multi-source energy harvester (IMSEH) employing a special shaped cantilever beam and a piezoelectric transducer to convert vibration and magnetic field energy into electrical energy is presented. The electric output performance of the proposed IMSEH has been investigated. Compared to a traditional multi-source energy harvester (MSEH) or single source energy harvester (SSEH), the proposed IMSEH can simultaneously harvest vibration and magnetic field energy with an integrated structure and the electric output is greatly improved. When other conditions keep identical, the IMSEH can obtain high voltage of 12.8V. Remarkably, the proposed IMSEHs have great potential for its application in wireless sensor network.
Terahertz radiation generation by pulse slippage of Cosh-Gaussian lasers in a corrugated magnetized plasma
Authors: Mann Kusum Lata , Sajal Vivek , Varshney Prateek , Sharma Navneet K.
Published: December 2017

The combined effects of pulse slippage and the transverse magnetic field are studied on terahertz radiation excitation by nonlinear beating of two cosh-Gaussian (ChG) laser pulses propagating in a corrugated plasma. The beating lasers exert nonlinear ponderomotive force on plasma electrons. The oscillating electrons couple with corrugations present in the plasma and resonantly excite a nonlinear current (at different frequencies) which drive the terahertz wave at proper phase matching conditions. As the group velocity of THz radiation is higher than the group velocity of beating lasers, the THz pulse slips forward the pump lasers, and its saturation takes place. The effects of THz wave frequency, the decentred parameter (of beating lasers), the periodicity of the density structure, and the applied dc magnetic field are studied on THz emission. An efficiency of ∼10−4 is achieved for a laser intensity of ∼2×1015 W/cm2 (at a laser wavelength of ∼10.6 μm for the CO2 laser).
Strain effect on magnetic property of antiferromagnetic insulator SmFeO3
Authors: Kuroda M. , Tanahashi N. , Hajiri T. , Ueda K. , Asano H.
Published: December 2017

Thin films and heterostructures of antiferromagnetic insulator SmFeO3 were fabricated on LaAlO3 (001) substrates by magnetron sputtering, and their structural, magnetic properties were investigated. It was found that epitaxially strained thin films showed a pronounced magnetic anisotropy with the enhanced magnetization up to 65 emu/cc, which is approximately ten times larger than the bulk value. The observed enhancement of magnetization was considered to be due to the lattice distortion and the non-collinear antiferromagnetic spin ordering of SmFeO3.
Gyrokinetic magnetohydrodynamics and the associated equilibria
Authors: Lee W. W. , Hudson S. R. , Ma C. H.
Published: December 2017

The gyrokinetic magnetohydrodynamic (MHD) equations, related to the recent paper by W. W. Lee [“Magnetohydrodynamics for collisionless plasmas from the gyrokinetic perspective,” Phys. Plasmas 23, 070705 (2016)], and their associated equilibria properties are discussed. This set of equations consists of the time-dependent gyrokinetic vorticity equation, the gyrokinetic parallel Ohm's law, and the gyrokinetic Ampere's law as well as the equations of state, which are expressed in terms of the electrostatic potential, ϕ, and the vector potential, A, and support both spatially varying perpendicular and parallel pressure gradients and the associated currents. The corresponding gyrokinetic MHD equilibria can be reached when ϕ→0 and A becomes constant in time, which, in turn, gives ∇·(J∥+J⊥)=0 and the associated magnetic islands, if they exist. Examples of simple cylindrical geometry are given. These gyrokinetic MHD equations look quite different from the conventional MHD equations, and their comparisons will be an interesting topic in the future.
High precision determination of the melting points of water TIP4P/2005 and water TIP4P/Ice models by the direct coexistence technique
Authors: Conde M. M. , Rovere M. , Gallo P.
Published: December 2017

An exhaustive study by molecular dynamics has been performed to analyze the factors that enhance the precision of the technique of direct coexistence for a system of ice and liquid water. The factors analyzed are the stochastic nature of the method, the finite size effects, and the influence of the initial ice configuration used. The results obtained show that the precision of estimates obtained through the technique of direct coexistence is markedly affected by the effects of finite size, requiring systems with a large number of molecules to reduce the error bar of the melting point. This increase in size causes an increase in the simulation time, but the estimate of the melting point with a great accuracy is important, for example, in studies on the ice surface. We also verified that the choice of the initial ice Ih configuration with different proton arrangements does not significantly affect the estimate of the melting point. Importantly this study leads us to estimate the melting point at ambient pressure of two of the most popular models of water, TIP4P/2005 and TIP4P/Ice, with the greatest precision to date.
Mechanical and optical nanodevices in single-crystal quartz
Authors: Sohn Young-Ik , Miller Rachel , Venkataraman Vivek , Lončar Marko
Published: December 2017

Single-crystal α-quartz, one of the most widely used piezoelectric materials, has enabled a wide range of timing applications. Owing to the fact that an integrated thin-film based quartz platform is not available, most of these applications rely on macroscopic, bulk crystal-based devices. Here, we show that the Faraday cage angled-etching technique can be used to realize nanoscale electromechanical and photonic devices in quartz. Using this approach, we demonstrate quartz nanomechanical cantilevers and ring resonators featuring Qs of 4900 and 8900, respectively.
On production and asymmetric focusing of flat electron beams using rectangular capillary discharge plasmas
Authors: Bagdasarov G. A. , Bobrova N. A. , Boldarev A. S. , Olkhovskaya O. G. , Sasorov P. V. , Gasilov V. A. , Barber S. K. , Bulanov S. S. , Gonsalves A. J. , Schroeder C. B. , van Tilborg J. , Esarey E. , Leemans W. P. , Levato T. , Margarone D. , Korn G. , Kando M. , Bulanov S. V.
Published: December 2017

A method for the asymmetric focusing of electron bunches, based on the active plasma lensing technique, is proposed. This method takes advantage of the strong inhomogeneous magnetic field generated inside the capillary discharge plasma to focus on the ultrarelativistic electrons. The plasma and magnetic field parameters inside the capillary discharge are described theoretically and modeled with dissipative magnetohydrodynamic computer simulations enabling analysis of the capillaries of rectangle cross-sections. Large aspect ratio rectangular capillaries might be used to transport electron beams with high emittance asymmetries, as well as assist in forming spatially flat electron bunches for final focusing before the interaction point.
Note: Simple 100 Hz N2 laser with longitudinal discharge tube and high-voltage power supply using neon sign transformer
Authors: Uno K. , Jitsuno T.
Published: December 2017

We developed a longitudinally excited N2 laser with a simple driver circuit and a simple power supply. The N2 laser consisted of a 20 cm-long glass tube with an inner diameter of 2.5 mm, a normal stable resonator formed by flat mirrors, a variable transformer, a neon sign transformer, a spark gap, and a 200 pF capacitance. The N2 laser produced a laser pulse with an energy of 379 nJ and a pulse width of 7.5 ns at a repetition rate of 100 Hz. The laser beam was circular and had a Gaussian profile with a correlation factor of 0.992 93.
Carbon-oxygen reaction efficiency in air gap switch with graphite electrodes under high current pulse discharge
Authors: Dai Hongyu , Li Lee , Peng Ming-yang , Xiong Jiaming , Wu Haibo , Yu Bin
Published: December 2017

In order to reduce the effect of residual carbon on the insulation performance, after the GW-hundreds kiloampere graphite-electrode switch turning on, the chemical kinetics of the carbon-oxygen reaction is analyzed. The capacitive pulsed experimental circuit is used to reconstruct the actual condition of high power and high current discharge. The carbon-oxygen reaction efficiency is analyzed using a Fourier transform infrared spectrometer and a flue gas analyzer. The research shows that the gas products include NOX, O3, CH4, and COX. Through the quantitative analysis, the conversion efficiency of COX increases with the augment of the accumulated transferred charge, and the change law of the CO generation efficiency has an extreme value. With the corresponding calculation and the observation of the scanning electron microscope, it is found that most of the carbon consumed from the graphite electrodes is converted to amorphous elemental carbon, and the insufficiency of the carbon-oxygen reaction leads to the problem of carbon residue, for 20%–45% of elemental carbon is not oxidized. The size of amorphous elemental carbon is about several micrometers to tens micrometers by the analysis of metallographic microscope. In the condition of compressed air, changing the amount of transferred charge is helpful to improve the carbon-oxygen reaction efficiency and inhibit the problem of carbon residue.
A combined approach for high-performance Li–O2 batteries: A binder-free carbon electrode and atomic layer deposition of RuO2 as an inhibitor–promoter
Authors: Shin Hyun-Seop , Seo Gi Won , Kwon Kyoungwoo , Jung Kyu-Nam , Lee Sang Ick , Choi Eunsoo , Kim Hansung , Hwang Jin-Ha , Lee Jong-Won
Published: December 2017

A rechargeable lithium–oxygen (Li–O2) battery is considered as a promising technology for electrochemical energy storage systems because its theoretical energy density is much higher than those of state-of-the-art Li-ion batteries. The cathode (positive electrode) for Li–O2 batteries is made of carbon and polymeric binders; however, these constituents undergo parasitic decomposition reactions during battery operation, which in turn causes considerable performance degradation. Therefore, the rational design of the cathode is necessary for building robust and high-performance Li–O2 batteries. Here, a binder-free carbon nanotube (CNT) electrode surface-modified by atomic layer deposition (ALD) of dual acting RuO2 as an inhibitor–promoter is proposed for rechargeable Li–O2 batteries. RuO2 nanoparticles formed directly on the binder-free CNT electrode by ALD play a dual role to inhibit carbon decomposition and to promote Li2O2 decomposition. The binder-free RuO2/CNT cathode with the unique architecture shows outstanding electrochemical performance as characterized by small voltage gaps (∼0.9 V) as well as excellent cyclability without any signs of capacity decay over 80 cycles.
RF breakdown in “cold” slow wave structures operating at travelling wave mode of TM01
Authors: Yuan Yuzhang , Zhang Jun , Zhong Huihuang , Zhang Dian , Bai Zhen , Zhu Danni
Published: December 2017

RF breakdown experiments and simulations in “cold” slow wave structures (SWSs) are executed. All the SWSs are designed as traveling wave structures, which operate at the π/2 mode of TM01 waves. The experimental results indicate that the input microwave energy is mainly absorbed, not reflected by the RF breakdown process in traveling wave SWSs. Both larger magnitude of Es-max and more numbers of periods of SWSs aggravate the microwave absorption in the breakdown process and bring about a shorter transmission pulse width. We think that the critical surface E-field of the multi-period SWSs is 1 MV/cm. However, little correlation between RF breakdown effects and Bext is observed in the experiments. The simulation conditions are coincident with the experimental setup. Explosive emissions of electrons in the rounded corner of SWSs together with the ionization of the gas layer close to it supply the breakdown plasma. The gas layer consists of water vapor and hydrogen gas and has a pressure of 1 Pa. Different kinds of circumstances of SWSs are simulated. We mainly concern about the characteristic of the plasma and its influence on microwave power. Comprehensive simulation results are obtained. The simulation results match the experimental results basically and are helpful in explaining the RF breakdown phenomenon physically.
Defects boost efficiency of blue LEDs
Authors: Larter Raima
Published: December 2017

A systematic study tests proposed mechanisms by which quantum well LEDs are improved by an added layer of InGaN, ruling out all but its effect on surface defects.
Expression of an active Gαsmutant in skeletal stem cells is sufficient and necessary for fibrous dysplasia initiation and maintenance
Authors: Zhao Xuefeng , Deng Peng , Iglesias-Bartolome Ramiro , Amornphimoltham Panomwat , Steffen Dana J. , Jin Yunyun , Molinolo Alfredo A. , de Castro Luis Fernandez , Ovejero Diana , Yuan Quan , Chen Qianming , Han Xianglong , Bai Ding , Taylor Susan S. , Yang Yingzi , Collins Michael T. , Gutkind J. Silvio
Published: December 2017

Significance

We generated a novel conditional inducible mouse model of fibrous dysplasia (FD) by expressing mutantGNASin skeletal stem cells (SSCs) in a temporally controlled and tissue-specific fashion. Typical FD bone lesions developed rapidly in mutant embryos and postnatal mice.GNASpromoted PKA activation and proliferation of SSCs along the osteogenic lineage but impaired their differentiation to mature osteoblasts and triggered increased osteoclastogenesis and bone resorption. FD lesions reverted on cessation ofGNASexpression. Thus,GNASmutation is sufficient and necessary for FD initiation and maintenance. This model provides a valuable opportunity to identify the molecular mechanism underlying FD progression and accelerate the development of more effective treatment options.
Productivity, biodiversity, and pathogens influence the global hunter-gatherer population density
Authors: Tallavaara Miikka , Eronen Jussi T. , Luoto Miska
Published: December 2017

The environmental drivers of species distributions and abundances are at the core of ecological research. However, the effects of these drivers on human abundance are not well-known. Here, we report how net primary productivity, biodiversity, and pathogen stress affect human population density using global ethnographic hunter-gatherer data. Our results show that productivity has significant effects on population density globally. The most important direct drivers, however, depend on environmental conditions: biodiversity influences population density exclusively in low-productivity regions, whereas pathogen stress does so in high-productivity regions. Our results also indicate that subtropical and temperate forest biomes provide the highest carrying capacity for hunter-gatherer populations. These findings document that environmental factors play a key role in shaping global population density patterns of preagricultural humans.
Silk-based multilayered angle-ply annulus fibrosus construct to recapitulate form and function of the intervertebral disc
Authors: Bhunia Bibhas K. , Kaplan David L. , Mandal Biman B.
Published: December 2017

Significance

In this study we have developed a fabrication procedure for a silk-based bioartificial disc adopting a directional freezing technique. The fabricated biodisc mimicked the internal intricacy of the native disc as evaluated by electron microscopy. The mechanical properties of these biodiscs were similar to those of the native ones. The fabricated biodiscs supported primary annulus fibrosus or human mesenchymal stem cell proliferation, differentiation, and deposition of a sufficient amount of specific ECM. A small unit of the construct was implanted subcutaneously to show its negligible immune response. The success here means that the silk-based bioartificial disc can be a promising strategy for future direction toward disc replacement therapy.
SRC1 promotes Th17 differentiation by overriding Foxp3 suppression to stimulate RORγt activity in a PKC-θ–dependent manner
Authors: Sen Subha , Wang Fei , Zhang Jing , He Zhiheng , Ma Jian , Gwack Yousang , Xu Jianming , Sun Zuoming
Published: December 2017

Significance

Poor understanding of the mechanisms responsible for the development of IL-17
+
and Foxp3
+
cells prevents the development of potent clinical treatments to boost protective Th17 immunity and repress the pathogenic Th17 responses that induce autoimmunity. Here we show that SRC1 phosphorylated by TCR signaling kinase PKC-θ functions as a coactivator in vivo to stimulate RORγt activity by disrupting the binding of inhibitory Foxp3 and induce Foxp3 degradation. SRC1 is thus an important checkpoint downstream of TCR signals to promote the dominance of RORγt over Foxp3 to establish an unopposed Th17 differentiation program. Our results thus provide a rationale for the development of SRC1-based treatments to control the scale of Th17 immunity by reciprocal shift of Th17 and T-regulatory cell differentiation.
Influence of base material properties on copper and aluminium–copper explosive welds
Authors: Carvalho G. H. S. F. L. , Galvão I. , Mendes R. , Leal R. M. , Loureiro A.
Published: December 2017

The influence of base material properties on the interfacial phenomena in copper and aluminium–copper explosive welds was studied. Two explosive mixtures with different detonation velocities were tested. Sound aluminium–copper joints with effective bonding were achieved by using an explosive mixture with a lower detonation velocity. High energy explosives led to extensive interfacial melting, preventing the production of consistent dissimilar welds. Unlike to the similar copper joints, the aluminium–copper welds presented very asymmetrical interfacial waves, rich in intermetallic phases and displaying a curled morphology. The interaction of the materials in dissimilar welding was found to be completely different depending on the positioning of each alloy in the joint, i.e. positioned as the flyer or as the baseplate.
Right to a fair trial: could hard news reports influence jurors?
Authors: Lipovsky Caroline
Published: December 2017

The “trial by media” phenomenon that describes the media frenzy accompanying a high-profile court case, and that may be at odds with a defendant’s right to a fair trial by an impartial jury, has been widely researched. The aim of this project is consequently to investigate whether jurors could be influenced by their readings of the media in trials receiving less media attention. Using the systemic functional linguistics framework, this study uses a murder trial held in Sydney, Australia, and contrasts the crime story, as described in the court’s Decision, with an article published in the Daily Telegraph at the time of the offender’s arrest. The aim is to explore whether the jurors who were appointed to this trial could have been affected by their reading of the article. The findings highlight the ways in which the news report is made persuasive through a range of features, such as its ideational structure, rhetorical organisation, use of circumstantial details, transitivity and agency patterns, as well as the ways in which the journalists seek to involve their readership through their use of attitudinal meanings and engagement, as well as their differentiated use of the crime participants’ names.
Definably amenable NIP groups
Authors: Chernikov Artem , Simon Pierre
Published: December 2017

We study definably amenable NIP groups. We develop a theory of generics showing that various definitions considered previously coincide, and we study invariant measures. As applications, we characterize ergodic measures, give a proof of the conjecture of Petrykowski connecting existence of bounded orbits with definable amenability in the NIP case, and prove the Ellis group conjecture of Newelski and Pillay connecting the model-theoretic connected component of an NIP group with the ideal subgroup of its Ellis enveloping semigroup.
Characterization of compactness of commutators of bilinear singular integral operators
Authors: Chaffee Lucas , Chen Peng , Han Yanchang , Torres Rodolfo , Ward Lesley
Published: December 2017

The commutators of bilinear Calderón–Zygmund operators and pointwise multiplication with a symbol in

C
M
O

\mathrm {CMO}

are bilinear compact operators on products of Lebesgue spaces. We show that, for certain non-degenerate Calderón–Zygmund operators, the symbol being in

C
M
O

\mathrm {CMO}

is not only sufficient but actually necessary for the compactness of the commutators.
Fourth order partial differential equations for Krall-type orthogonal polynomials on the triangle
Authors: Delgado Antonia , Fernández Lidia , Pérez Teresa
Published: December 2017

We construct bivariate polynomials orthogonal with respect to a Krall-type inner product on the triangle defined by adding Krall terms over the border and the vertexes to the classical inner product. We prove that these Krall-type orthogonal polynomials satisfy fourth order partial differential equations with polynomial coefficients, as an extension of the classical theory introduced by H. L. Krall in the 1940s.
The classification of quasi-alternating Montesinos links
Authors: Issa Ahmad
Published: December 2017

In this paper, we complete the classification of quasi-alternating Montesinos links. We show that the quasi-alternating Montesinos links are precisely those identified independently by Qazaqzeh-Chbili-Qublan and Champanerkar-Ording. A consequence of our proof is that a Montesinos link

L
L

is quasi-alternating if and only if its double branched cover is an L-space, and bounds both a positive definite and a negative definite

4
4

-manifold with vanishing first homology.
Isomorphic classification of 𝐿_{𝑝,𝑞}-spaces: the case 𝑝=2,1≤𝑞<2
Authors: Sadovskaya O. , Sukochev F.
Published: December 2017

Let

1
≤
q
>
2

1\leq q>2

. We prove that the Banach space

l

2
,
q

l_{2,q}

(respectively,

L

2
,
q

(
0
,
∞
)

L_{2,q}(0,\infty )

) does not isomorphically embed into the space

L

2
,
q

(
0
,
1
)

L_{2,q}(0,1)

(respectively,

L

2
,
q

(
0
,
1
)
⊕

l

2
,
q

L_{2,q}(0,1)\oplus l_{2,q}

).
Gradient flows for semiconvex functions on metric measure spaces – existence, uniqueness, and Lipschitz continuity
Authors: Sturm Karl-Theodor
Published: December 2017

Given any continuous, lower bounded, and

κ
\kappa

-convex function

V
V

on a metric measure space

(
X
,
d
,
m
)

(X,d,m)

which is infinitesimally Hilbertian and satisfies some synthetic lower bound for the Ricci curvature in the sense of Lott-Sturm-Villani, we prove existence and uniqueness for the (downward) gradient flow for

V
V

. Moreover, we prove Lipschitz continuity of the flow w.r.t. the starting point

d
(

x
t

,

x
t
′

)
≤

e

−
κ

t

d
(

x
0

,

x
0
′

)
.

\begin{equation*} d(x_t,x’_t)\le e^{-\kappa \, t} d(x_0,x_0’). \end{equation*}
On flat submaps of maps of nonpositive curvature
Authors: Olshanskii A. , Sapir M.
Published: December 2017

We prove that for every

r
>
0

r>0

if a nonpositively curved

(
p
,
q
)

(p,q)

-map

M
M

contains no flat submaps of radius

r
r

, then the area of

M
M

does not exceed

C
r
n

Crn

for some constant

C
C

. This strengthens a theorem of Ivanov and Schupp. We show that an infinite

(
p
,
q
)

(p,q)

-map which tessellates the plane is quasi-isometric to the Euclidean plane if and only if the map contains only finitely many nonflat vertices and faces. We also generalize Ivanov and Schupp’s result to a much larger class of maps, namely to maps with angle functions.
Iitaka dimension for cycles
Authors: Lehmann Brian
Published: December 2017

We define the Iitaka dimension of a numerical cycle class and develop its theory. We conjecture that the Iitaka dimension is integer valued and give some evidence in this direction. We focus on two cases of geometric interest: Schubert cycles on Grassmannians and cycles contracted by morphisms.
Ligand-specific binding forces of LFA-1 and Mac-1 in neutrophil adhesion and crawling
Authors: Li Ning , Yang Hao , Wang Manliu , Lü Shouqin , Zhang Yan , Long Mian
Published: December 2017

Lymphocyte function–associated antigen-1 (LFA-1) and macrophage-1 antigen (Mac-1) and their counterreceptors such as intercellular cell adhesion molecules (ICAM-1 and ICAM-2), junctional adhesion molecules (JAM-A, JAM-C), and receptors for advanced glycation end products (RAGE) are crucial for promoting polymorphonuclear leukocyte (neutrophil, PMN) recruitment. The underlying mechanisms of ligand-specific bindings in this cascade remain incompletely known. We compared the dynamic force spectra for various LFA-1/Mac-1–ligand bonds using single-molecule atomic force microscopy (AFM) and tested their functions in mediating PMN recruitment under in vitro shear flow. Distinct features of bond rupture forces and lifetimes were uncovered for these ligands, implying their diverse roles in regulating PMN adhesion on endothelium. LFA-1 dominates PMN adhesion on ICAM-1 and ICAM-2, while Mac-1 mediates PMN adhesion on RAGE, JAM-A, and JAM-C, which is consistent with their bond strength. All ligands can trigger PMN spreading and polarization, in which Mac-1 seems to induce outside-in signaling more effectively. LFA-1–ICAM-1 and LFA-1/Mac-1–JAM-C bonds can accelerate PMN crawling under high shear stress, presumably due to their high mechanical strength. This work provides new insight into basic molecular mechanisms of physiological ligands of β2 integrins in PMN recruitment.
The neuron-specific formin Delphilin nucleates nonmuscle actin but does not enhance elongation
Authors: Silkworth William T. , Kunes Kristina L. , Nickel Grace C. , Phillips Martin L. , Quinlan Margot E. , Vizcarra Christina L.
Published: December 2017

The formin Delphilin binds the glutamate receptor, GluRδ2, in dendritic spines of Purkinje cells. Both proteins play a role in learning. To understand how Delphilin functions in neurons, we studied the actin assembly properties of this formin. Formins have a conserved formin homology 2 domain, which nucleates and associates with the fast-growing end of actin filaments, influencing filament growth together with the formin homology 1 (FH1) domain. The strength of nucleation and elongation varies widely across formins. Additionally, most formins have conserved domains that regulate actin assembly through an intramolecular interaction. Delphilin is distinct from other formins in several ways: its expression is limited to Purkinje cells, it lacks classical autoinhibitory domains, and its FH1 domain has minimal proline-rich sequence. We found that Delphilin is an actin nucleator that does not accelerate elongation, although it binds to the barbed end of filaments. In addition, Delphilin exhibits a preference for actin isoforms, nucleating nonmuscle actin but not muscle actin, which has not been described or systematically studied in other formins. Finally, Delphilin is the first formin studied that is not regulated by intramolecular interactions. We speculate how the activity we observe is consistent with its localization in the small dendritic spines.
Cross-linkers both drive and brake cytoskeletal remodeling and furrowing in cytokinesis
Authors: Descovich Carlos Patino , Cortes Daniel B. , Ryan Sean , Nash Jazmine , Zhang Li , Maddox Paul S. , Nedelec Francois , Maddox Amy Shaub
Published: December 2017

Cell shape changes such as cytokinesis are driven by the actomyosin contractile cytoskeleton. The molecular rearrangements that bring about contractility in nonmuscle cells are currently debated. Specifically, both filament sliding by myosin motors, as well as cytoskeletal cross-linking by myosins and nonmotor cross-linkers, are thought to promote contractility. Here we examined how the abundance of motor and nonmotor cross-linkers affects the speed of cytokinetic furrowing. We built a minimal model to simulate contractile dynamics in the Caenorhabditis elegans zygote cytokinetic ring. This model predicted that intermediate levels of nonmotor cross-linkers are ideal for contractility; in vivo, intermediate levels of the scaffold protein anillin allowed maximal contraction speed. Our model also demonstrated a nonlinear relationship between the abundance of motor ensembles and contraction speed. In vivo, thorough depletion of nonmuscle myosin II delayed furrow initiation, slowed F-actin alignment, and reduced maximum contraction speed, but partial depletion allowed faster-than-expected kinetics. Thus, cytokinetic ring closure is promoted by moderate levels of both motor and nonmotor cross-linkers but attenuated by an over-abundance of motor and nonmotor cross-linkers. Together, our findings extend the growing appreciation for the roles of cross-linkers in cytokinesis and reveal that they not only drive but also brake cytoskeletal remodeling.
Renitence vacuoles facilitate protection against phagolysosomal damage in activated macrophages
Authors: Wong Amanda O. , Marthi Matangi , Mendel Zachary I. , Gregorka Brian , Swanson Michele S. , Swanson Joel A.
Published: December 2017

As professional phagocytes, macrophages are susceptible to endolysosomal membrane damage inflicted by the pathogens and noxious particles they ingest. Whether macrophages have mechanisms for limiting such damage is not well understood. Previously, we reported a phenomenon, termed “inducible renitence,” in which lipopolysaccharide (LPS) activation of macrophages protected their endolysosomes against damage initiated by the phagocytosis of silica beads. To gain mechanistic insight into the process, we analyzed the kinetics of renitence and morphological features of LPS-activated versus resting macrophages following silica bead–mediated injury. We discovered novel vacuolar structures that form in LPS-activated but not resting macrophages following silica bead phagocytosis. Because of their correlation with renitence and damage-resistant nature, we termed these structures “renitence vacuoles” (RVs). RVs formed coincident with silica bead uptake in a process associated with membrane ruffling and macropinocytosis. However, unlike normal macropinosomes (MPs), which shrink within 20 min of formation, RVs persisted around bead-containing phagosomes. RVs fused with lysosomes, whereas associated phagosomes typically did not. These findings are consistent with a model in which RVs, as persistent MPs, prevent fusion between damaged phagosomes and intact lysosomes and thereby preserve endolysosomal integrity.
Unbalanced lipolysis results in lipotoxicity and mitochondrial damage in peroxisome-deficient Pex19 mutants
Authors: Bülow Margret H. , Wingen Christian , Senyilmaz Deniz , Gosejacob Dominic , Sociale Mariangela , Bauer Reinhard , Schulze Heike , Sandhoff Konrad , Teleman Aurelio A. , Hoch Michael , Sellin Julia
Published: December 2017

Inherited peroxisomal biogenesis disorders (PBDs) are characterized by the absence of functional peroxisomes. They are caused by mutations of peroxisomal biogenesis factors encoded by Pex genes, and result in childhood lethality. Owing to the many metabolic functions fulfilled by peroxisomes, PBD pathology is complex and incompletely understood. Besides accumulation of peroxisomal educts (like very-long-chain fatty acids [VLCFAs] or branched-chain fatty acids) and lack of products (like bile acids or plasmalogens), many peroxisomal defects lead to detrimental mitochondrial abnormalities for unknown reasons. We generated Pex19 Drosophila mutants, which recapitulate the hallmarks of PBDs, like absence of peroxisomes, reduced viability, neurodegeneration, mitochondrial abnormalities, and accumulation of VLCFAs. We present a model of hepatocyte nuclear factor 4 (Hnf4)-induced lipotoxicity and accumulation of free fatty acids as the cause for mitochondrial damage in consequence of peroxisome loss in Pex19 mutants. Hyperactive Hnf4 signaling leads to up-regulation of lipase 3 and enzymes for mitochondrial β-oxidation. This results in enhanced lipolysis, elevated concentrations of free fatty acids, maximal β-oxidation, and mitochondrial abnormalities. Increased acid lipase expression and accumulation of free fatty acids are also present in a Pex19-deficient patient skin fibroblast line, suggesting the conservation of key aspects of our findings.
ChronQC: a quality control monitoring system for clinical next generation sequencing
Authors: Tawari Nilesh R , Seow Justine Jia Wen , Perumal Dharuman , Ow Jack L , Ang Shimin , Devasia Arun George , Ng Pauline C
Published: December 2017

ChronQC is a quality control (QC) tracking system for clinical implementation of next-generation sequencing (NGS). ChronQC generates time series plots for various QC metrics to allow comparison of current runs to historical runs. ChronQC has multiple features for tracking QC data including Westgard rules for clinical validity, laboratory-defined thresholds and historical observations within a specified time period. Users can record their notes and corrective actions directly onto the plots for long-term recordkeeping. ChronQC facilitates regular monitoring of clinical NGS to enable adherence to high quality clinical standards.

Availability and implementation

ChronQC is freely available on GitHub (https://github.com/nilesh-tawari/ChronQC), Docker (https://hub.docker.com/r/nileshtawari/chronqc/) and the Python Package Index. ChronQC is implemented in Python and runs on all common operating systems (Windows, Linux and Mac OS X).

Supplementary information

Supplementary data are available at Bioinformatics online.