bluuebunny/crossref_metadata_2025 huggingface dataset:
A new high sensitivity far-infrared laser interferometer for the HL-2A tokamak
Authors: Li Y. G. , Zhou Y. , Li Y. , Deng Z. C. , Wang H. X. , Yi J.
Published: August 2017

A new four-chord Michelson-type formic acid (HCOOH, λ = 432.5 μm) laser interferometer has been successfully commissioned on the HL-2A tokamak to measure the electron density and density fluctuations. Due to the employment of the two-laser heterodyne technique, the time resolution of the interferometer reached 1.0 microseconds (μs). Four chords of line electron densities with a line-averaged density resolution 2 × 1016/m3 were obtained in a recent HL-2A experimental campaign, and detailed electron density fluctuations, caused by events such as edge localized mode, sawtooth precursor-oscillations, and energetic particle driven instabilities, were distinctly measured. In particular, the high-frequency electron density fluctuations (up to 500 kHz) caused by the reversed shear Alfvénic eigenmode were observed by the internal two interferometry channels, and their fluctuation location could be approximately identified from the spectra characteristics of multi-chord line electron densities.
Multi-rate cubature Kalman filter based data fusion method with residual compensation to adapt to sampling rate discrepancy in attitude measurement system
Authors: Guo Xiaoting , Sun Changku , Wang Peng
Published: August 2017

This paper investigates the multi-rate inertial and vision data fusion problem in nonlinear attitude measurement systems, where the sampling rate of the inertial sensor is much faster than that of the vision sensor. To fully exploit the high frequency inertial data and obtain favorable fusion results, a multi-rate CKF (Cubature Kalman Filter) algorithm with estimated residual compensation is proposed in order to adapt to the problem of sampling rate discrepancy. During inter-sampling of slow observation data, observation noise can be regarded as infinite. The Kalman gain is unknown and approaches zero. The residual is also unknown. Therefore, the filter estimated state cannot be compensated. To obtain compensation at these moments, state error and residual formulas are modified when compared with the observation data available moments. Self-propagation equation of the state error is established to propagate the quantity from the moments with observation to the moments without observation. Besides, a multiplicative adjustment factor is introduced as Kalman gain, which acts on the residual. Then the filter estimated state can be compensated even when there are no visual observation data. The proposed method is tested and verified in a practical setup. Compared with multi-rate CKF without residual compensation and single-rate CKF, a significant improvement is obtained on attitude measurement by using the proposed multi-rate CKF with inter-sampling residual compensation. The experiment results with superior precision and reliability show the effectiveness of the proposed method.
An immersed boundary-simplified sphere function-based gas kinetic scheme for simulation of 3D incompressible flows
Authors: Yang L. M. , Shu C. , Yang W. M. , Wang Y. , Wu J.
Published: August 2017

In this work, an immersed boundary-simplified sphere function-based gas kinetic scheme (SGKS) is presented for the simulation of 3D incompressible flows with curved and moving boundaries. At first, the SGKS [Yang et al., “A three-dimensional explicit sphere function-based gas-kinetic flux solver for simulation of inviscid compressible flows,” J. Comput. Phys. 295, 322 (2015) and Yang et al., “Development of discrete gas kinetic scheme for simulation of 3D viscous incompressible and compressible flows,” J. Comput. Phys. 319, 129 (2016)], which is often applied for the simulation of compressible flows, is simplified to improve the computational efficiency for the simulation of incompressible flows. In the original SGKS, the integral domain along the spherical surface for computing conservative variables and numerical fluxes is usually not symmetric at the cell interface. This leads the expression of numerical fluxes at the cell interface to be relatively complicated. For incompressible flows, the sphere at the cell interface can be approximately considered to be symmetric as shown in this work. Besides that, the energy equation is usually not needed for the simulation of incompressible isothermal flows. With all these simplifications, the simple and explicit formulations for the conservative variables and numerical fluxes at the cell interface can be obtained. Second, to effectively implement the no-slip boundary condition for fluid flow problems with complex geometry as well as moving boundary, the implicit boundary condition-enforced immersed boundary method [Wu and Shu, “Implicit velocity correction-based immersed boundary-lattice Boltzmann method and its applications,” J. Comput. Phys. 228, 1963 (2009)] is introduced into the simplified SGKS. That is, the flow field is solved by the simplified SGKS without considering the presence of an immersed body and the no-slip boundary condition is implemented by the immersed boundary method. The accuracy and efficiency of the present scheme are validated by simulating the decaying vortex flow, flow past a stationary and rotating sphere, flow past a stationary torus, and flows over dragonfly flight.
Multiplicative equations related to the affine Weyl group E8
Authors: Grammaticos B. , Ramani A. , Willox R. , Satsuma J.
Published: August 2017

We derive integrable equations starting from autonomous mappings with a general form inspired by the multiplicative systems associated with the affine Weyl group E8(1). Five such systems are obtained, three of which turn out to be linearisable and the remaining two are integrable in terms of elliptic functions. In the case of the linearisable mappings, we derive non-autonomous forms which contain a free function of the independent variable and we present the linearisation in each case. The two remaining systems are deautonomised to new discrete Painlevé equations. We show that these equations are in fact special forms of much richer systems associated with the affine Weyl groups E7(1) and E8(1), respectively.
What is the best planar cavity for maximizing coherent exciton-photon coupling
Authors: Wang Zhaorong , Gogna Rahul , Deng Hui
Published: August 2017

We compare alternative planar cavity structures for strong exciton-photon coupling with the conventional distributed Bragg reflector (DBR) and three unconventional types of cavity mirrors—air/GaAs DBR, Tamm-plasmon mirror, and sub-wavelength grating mirror. We design and optimize the planar cavities built with each type of mirror at one side or both sides for the maximum vacuum field strength. We discuss the trade-off between performance and fabrication difficulty for each cavity structure. We show that cavities with sub-wavelength grating mirrors allow simultaneously the strongest field and high cavity quality. The optimization principles and techniques developed in this work will guide the cavity design for research and applications of matter-light coupled semiconductors, especially new material systems that require greater flexibility in the choice of cavity materials and cavity fabrication procedures.
Gated ion spectrometer for spectroscopy of neutral particles
Authors: Sharif S. , Braenzel J. , Schnürer M. , Prasad R. , Borghesi M. , Tikhonchuk V. , Ter-Avetisyan S.
Published: August 2017

A new design of an ion mass spectrometer for the laser-plasma particle diagnostic, which is capable to detect simultaneously also neutral particles, is described. The particles are detected with micro-channel-plate detector operating in a gated mode. This allows us to separate x-rays and energetic electrons from other stray plasma emissions, e.g., neutral particles, which hit the detector in the same place. The ion energies are measured with the spectrometer in energy intervals corresponding to their time-of-flight within the gating window. The latter also defines the energy interval of neutrals recorded with the same time-of-flight. The spectrum of neutral particles can be reconstructed by subsequently collecting different parts of the spectrum while applying different delays on the gate pulse. That separation-in-time technique (time-of-flight mass spectrometry) in combination with the spatially separating mass analyzer (ion mass spectrometer) is used for the neutral particles spectroscopy.
Morphology of drop impact on a superhydrophobic surface with macro-structures
Authors: Regulagadda Kartik , Bakshi Shamit , Das Sarit Kumar
Published: August 2017

Drop-surface interaction is predominant in nature as well as in many industrial applications. Superhydrophobic surfaces show potential for various applications as they show complete drop rebound. In a recent work, it has been reported that the drop lift-off time on a superhydrophobic substrate could be further reduced by introducing a macro-ridge. The macro-ridge introduces asymmetry on the morphology of drop spreading and retraction on the surface. This changes the hydrodynamics of drop retraction and reduces the lift-off time. Keeping practical applications in view, we decorate the surface with multiple ridges. The morphology of the hydrodynamic asymmetry is completely different for the drops impacting onto the tip of the ridges from those impacting onto the middle of the valley between the ridges. We show that the morphology forms the key to the lift-off time. We also show that the outward flow from the ridge triggers a Laplace pressure driven de-wetting on the tip of the ridge, thus aiding the lift-off time. At the end of this work, we propose a ridge to ridge separation that effectively reduces the lift-off times for impacts both at the tip of the ridge and offset from it.
Chemical dynamics between wells across a time-dependent barrier: Self-similarity in the Lagrangian descriptor and reactive basins
Authors: Junginger Andrej , Duvenbeck Lennart , Feldmaier Matthias , Main Jörg , Wunner Günter , Hernandez Rigoberto
Published: August 2017

In chemical or physical reaction dynamics, it is essential to distinguish precisely between reactants and products for all times. This task is especially demanding in time-dependent or driven systems because therein the dividing surface (DS) between these states often exhibits a nontrivial time-dependence. The so-called transition state (TS) trajectory has been seen to define a DS which is free of recrossings in a large number of one-dimensional reactions across time-dependent barriers and thus, allows one to determine exact reaction rates. A fundamental challenge to applying this method is the construction of the TS trajectory itself. The minimization of Lagrangian descriptors (LDs) provides a general and powerful scheme to obtain that trajectory even when perturbation theory fails. Both approaches encounter possible breakdowns when the overall potential is bounded, admitting the possibility of returns to the barrier long after the trajectories have reached the product or reactant wells. Such global dynamics cannot be captured by perturbation theory. Meanwhile, in the LD-DS approach, it leads to the emergence of additional local minima which make it difficult to extract the optimal branch associated with the desired TS trajectory. In this work, we illustrate this behavior for a time-dependent double-well potential revealing a self-similar structure of the LD, and we demonstrate how the reflections and side-minima can be addressed by an appropriate modification of the LD associated with the direct rate across the barrier.
Electric field modulated conduction mechanism in Al/BaTiO3/La0.67Sr0.33MnO3 heterostructures
Authors: Zheng Dongxing , Li Dong , Gong Junlu , Jin Chao , Li Peng , Zhang Xixiang , Bai Haili
Published: August 2017

Mediating a metastable state is a promising way to achieve a giant modulation of physical properties in artificial heterostructures. A metastable state La0.67Sr0.33MnO3 (LSMO) layer suffering tensile strain was grown on MgO substrates. Incorporating with the ferroelectric BaTiO3 (BTO) layer, an accumulation or depletion state controlled by electric fields can be formed at the BTO/LSMO interface, which drives a switching of the conduction mechanism between space charge limited conduction and Poole-Frenkel emission, corresponding to the low and high resistance states. Our results lighten an effective way for electric-field modulated resistance states in multiferroic magnetoelectric devices.
Numerical investigation of nanosecond laser induced plasma and shock wave dynamics from air using 2D hydrodynamic code
Authors: Sai Shiva S. , Leela Ch. , Prem Kiran P. , Sijoy C. D. , Ikkurthi V. R. , Chaturvedi S.
Published: August 2017

A two-dimensional axis symmetric hydrodynamic model was developed to investigate nanosecond laser induced plasma and shock wave dynamics in ambient air over the input laser energies of 50–150 mJ and time scales from 25 ns to 8 μs. The formation of localized hot spots during laser energy deposition, asymmetric spatio-temporal evolution, rolling, and splitting of the plasma observed in the simulations were in good agreement with the experimental results. The formed plasma was observed to have two regions: the hot plasma core and the plasma outer region. The asymmetric expansion was due to the variation in the thermodynamic variables along the laser propagation and radial directions. The rolling of the plasma was observed to take place in the core region where very high temperatures exist. Similarly, the splitting of the plasma was observed to take place in the core region between the localized hot spots that causes the hydrodynamic instabilities. The rolling and splitting times were observed to vary with the input laser energy deposited. The plasma expansion was observed to be asymmetric for all the simulated time scales considered, whereas the shock wave evolution was observed to transfer from asymmetric to symmetric expansion. Finally, the simulated temporal evolution of the electron number density, temperature of the hot core plasma, and the temperature evolution across the shock front after the detachment from the plasma were presented over the time scales 25 ns–8 μs for different input laser pulse energies.
Plasmonic electron acceleration with the meta-surfaces
Authors: Kong Ling-Bao , Chen Zhaoyang
Published: August 2017

A mechanism for electron acceleration by spoof surface-plasmons (SSP) is proposed. By using a specially designed meta-surface with gradient structural size, the SSP and electrons can be accelerated simultaneously along the surface, which gives rise to a long-range and efficient electron-SSP interaction. Compared with the homogeneous meta-surfaces, the increment of electron kinetic energy, ∼19 keV, is enhanced by two orders of magnitude. The effect may be valuable for developing efficient plasmonic electron accelerators.
Study of BenW (n = 1–12) clusters: An electron collision perspective
Authors: Modak Paresh , Kaur Jaspreet , Antony Bobby
Published: August 2017

This article explores electron scattering cross sections by Beryllium-Tungsten clusters (BenW). Beryllium and tungsten are important elements for plasma facing wall components, especially for the deuterium/tritium phase of ITER and in the recently installed JET. The present study focuses on different electron impact interactions in terms of elastic cross section (Qel), inelastic cross section (Qinel), ionization cross section (Qion), and momentum transfer cross section (Qmtcs) for the first twelve clusters belonging to the BenW family. It also predicts the evolution of the cross section with the size of the cluster. These cross sections are used as an input to model processes in plasma. The ionization cross section presented here is compared with the available reported data. This is the first comprehensive report on cross section data for all the above-mentioned scattering channels, to the best of our knowledge. Such broad analysis of cross section data gives vital insight into the study of local chemistry of electron interactions with BenW (n = 1–12) clusters in plasma.
Tunable thermal conductivity in mesoporous silicon by slight porosity change
Authors: Seol Jae Hun , Barth David S. , Zhu Jia , Ćoso Dušan , Hippalgaonkar Kedar , Lim Jongwoo , Han Junkyu , Zhang Xiang , Majumdar Arun
Published: August 2017

We report the thermal conductivity of photoelectrochemically synthesized mesoporous silicon (MPS), with ∼20-nm diameter pores and 52%–58% porosity. The thermal conductivity of MPS samples with a thickness of a few microns was measured using the three omega (3ω) differential technique. We experimentally demonstrated that the thermal conductivity of MPS varies between 3 and 7 W/m K at room temperature and is dependent on the photoelectrochemical etching times used during the MPS synthesis, which induces a slight change in the MPS porosity. Calculations were conducted using the Boltzmann transport equation in the relaxation time approximation, with the results suggesting that the large thermal conductivity reduction in the MPSs was not entirely explained by the pore boundary scattering. Our findings indicate that elastic softening in the mesoporous structure may be responsible for the reduction in the thermal conductivity.
Jeans instability in a degenerate electron-positron-ion and classical dusty plasma
Authors: Rozina Ch. , Tsintsadze N. L. , Khadija A.
Published: August 2017

We follow the quantum hydrodynamic model to study the newly suggested problem of Jeans instability in collisionless self-gravitating multicomponent, dense, astrophysical quantum plasmas. Here, the quantum effects appear through the quantum diffraction and Fermi pressure, whereas the quantum statistical effects are important only for degenerate electron-positron- ion and dust being the heaviest is treated as classical. We have obtained dispersion relations for three particular plasmas; every time, Fermi pressure is found to be numerically larger than the quantum diffraction term which tends to stabilize Jeans instability even more than the Madelung term. The Jeans critical wave number and the corresponding critical mass are defined for particular plasmas. We have displayed our results numerically and have shown that the gravitational instability of quantum electron-ion-dust plasmas and electron-positron-dust plasmas is achieved by increasing both the number density and mass of the dust grains. Moreover, the degeneracy quantum corrections effectively stabilizing the Jeans instability was focused.
Communication: On the diffusion tensor in macroscopic theory of cavitation
Authors: Shneidman Vitaly A.
Published: August 2017

The classical description of nucleation of cavities in a stretched fluid relies on a one-dimensional Fokker-Planck equation (FPE) in the space of their sizes r, with the diffusion coefficient D(r) constructed for all r from macroscopic hydrodynamics and thermodynamics, as shown by Zeldovich. When additional variables (e.g., vapor pressure) are required to describe the state of a bubble, a similar approach to construct a diffusion tensor D^ generally works only in the direct vicinity of the thermodynamic saddle point corresponding to the critical nucleus. It is shown, nevertheless, that “proper” kinetic variables to describe a cavity can be selected, allowing to introduce D^ in the entire domain of parameters. In this way, for the first time, complete FPE’s are constructed for viscous volatile and inertial fluids. In the former case, the FPE with symmetric D^ is solved numerically. Alternatively, in the case of an inertial fluid, an equivalent Langevin equation is considered; results are compared with analytics. The suggested approach is quite general and can be applied beyond the cavitation problem.
A critical evaluation of kinetic surface freezing of water
Authors: Hendricks-Sturrup Rachele
Published: August 2017

Yale and Princeton University researchers expound the current state of research on the thermodynamic and kinetic tendencies of surface freezing.
An empirically based approach to defining wildland firefighter safety and survival zone separation distances
Authors: Page Wesley G. , Butler Bret W.
Published: August 2017

Wildland firefighters in the US are mandated to identify areas that provide adequate separation between themselves and the flames (i.e. safety zones) to reduce the risk of burn injury. This study presents empirical models that estimate the distance from flames that would result in a low probability (1 or 5%) of either fatal or non-fatal injuries. The significant variables for the fatal injury model were fire shelter use, slope steepness and flame height. The separation distances needed to ensure no more than a 1 or 5% probability of fatal injury, without the use of a fire shelter, for slopes less than 25% were 20 to 50 m for flame heights less than 10 m, and 1 to 4 times the flame height for flames taller than 10 m. The non-fatal injury model significant variables were fire shelter use, vehicle use and fuel type. At the 1 and 5% probability thresholds for a non-fatal injury, without the use of a fire shelter, the separation distances were 1 to 2, 6 to 7, and 12 to 16 times greater than the current safety zone guideline (i.e. 4 times the flame height) for timber, brush and grass fuel types respectively.
Minority households’ willingness to pay for public and private wildfire risk reduction in Florida
Authors: González-Cabán Armando , Sánchez José J.
Published: August 2017

The purpose of this work is to estimate willingness to pay (WTP) for minority (African-American and Hispanic) homeowners in Florida for private and public wildfire risk-reduction programs and also to test for differences in response between the two groups. A random parameter logit and latent class model allowed us to determine if there is a difference in wildfire mitigation program preferences, whether WTP is higher for public or private actions for wildfire risk reduction, and whether households with personal experience and who perceive that they live in higher-risk areas have significantly higher WTP. We also compare Florida minority homeowners’ WTP values with Florida original homeowners’ estimates. Results suggest that Florida minority homeowners are willing to invest in public programs, with African-Americans WTP values at a higher rate than Hispanics. In addition, the highest priority for cost-sharing funds would go to low-income homeowners, especially to cost-share private actions on their own land. These results may help fire managers optimise allocation of scarce cost-sharing funds for public v. private actions.
Rainforest metropolis casts 1,000-km defaunation shadow
Authors: Tregidgo Daniel J. , Barlow Jos , Pompeu Paulo S. , de Almeida Rocha Mayana , Parry Luke
Published: August 2017

Significance

Tropical wilderness areas of largely pristine habitats and low human population densities are witnessing rapid urbanization. However, the urban impact on harvested wildlife populations is largely unknown. An extensive dataset on the population status of a keystone fish species was generated by interviewing hundreds of rural Amazonians about their lifetime fishing activity along a heavily fished but otherwise relatively pristine river. Data reveal that the fish become much smaller and harder to catch when travelling toward a rainforest metropolis of over 2 million residents. This trend extends over 1,000 km from the city. We show how urban connectivity drives this depletion, and discuss how wider forest diversity and human livelihoods may suffer as a result.
Antibacterial photosensitization through activation of coproporphyrinogen oxidase
Authors: Surdel Matthew C. , Horvath Dennis J. , Lojek Lisa J. , Fullen Audra R. , Simpson Jocelyn , Dutter Brendan F. , Salleng Kenneth J. , Ford Jeremy B. , Jenkins J. Logan , Nagarajan Raju , Teixeira Pedro L. , Albertolle Matthew , Georgiev Ivelin S. , Jansen E. Duco , Sulikowski Gary A. , Lacy D. Borden , Dailey Harry A. , Skaar Eric P.
Published: August 2017

Significance

Skin and soft tissue infections (SSTIs) account for a majority of visits to hospitals and clinics in the United States and are typically caused by Gram-positive pathogens. Recently, it was discovered that Gram-positive bacteria use a unique pathway to synthesize the critical cellular cofactor heme. The divergence of the heme biosynthesis pathways between humans and Gram-positive bacteria provides a unique opportunity for the development of new antibiotics targeting this pathway. We report here the identification of a small-molecule activator of coproporphyrinogen oxidase (CgoX) from Gram-positive bacteria that induces accumulation of coproporphyrin III and leads to photosensitization of Gram-positive pathogens. In combination with light, CgoX activation reduces bacterial burden in murine models of SSTI.
HEMO, an ancestral endogenous retroviral envelope protein shed in the blood of pregnant women and expressed in pluripotent stem cells and tumors
Authors: Heidmann Odile , Béguin Anthony , Paternina Janio , Berthier Raphaël , Deloger Marc , Bawa Olivia , Heidmann Thierry
Published: August 2017

Significance

Endogenization of retroviruses has occurred multiple times in the course of vertebrate evolution, with the captured retroviral envelope syncytins playing a role in placentation in mammals, including marsupials. Here, we identify an endogenous retroviral envelope protein with unprecedented properties, including a specific cleavage process resulting in the shedding of its extracellular moiety in the human blood circulation. This protein is conserved in all simians—with a homologous protein found in marsupials—with a “stemness” expression in embryonic and reprogrammed stem cells, as well as in the placenta and some human tumors, especially ovarian tumors. This protein could constitute a versatile marker—and possibly an effector—of specific cellular states and being shed, be immunodetected in the blood.
Inkjet-printed point-of-care immunoassay on a nanoscale polymer brush enables subpicomolar detection of analytes in blood
Authors: Joh Daniel Y. , Hucknall Angus M. , Wei Qingshan , Mason Kelly A. , Lund Margaret L. , Fontes Cassio M. , Hill Ryan T. , Blair Rebecca , Zimmers Zackary , Achar Rohan K. , Tseng Derek , Gordan Raluca , Freemark Michael , Ozcan Aydogan , Chilkoti Ashutosh
Published: August 2017

Significance

Sensitive quantitation of protein biomarkers plays an important role in modern clinical decision making. This work introduces an inkjet-printed assay platform built on a nonfouling, nanoscale polymer brush, which eliminates nonspecific binding, the largest source of noise in surface-based assays. The assay goes to completion after adding a drop of blood (with no additional reagents or mixing), and the assay can be read with a smartphone-based detector. This technology is significant because it enables high-performance diagnostic testing in blood with minimal infrastructural requirements. Furthermore, its fully printed nature makes it highly customizable and thus broadly applicable to a wide range of diagnostic targets.
Bilingual infants control their languages as they listen
Authors: Byers-Heinlein Krista , Morin-Lessard Elizabeth , Lew-Williams Casey
Published: August 2017

Significance

Bilingual infants must manage two languages in a single developing mind. However, the mechanisms that enable young bilinguals to manage their languages over the course of learning remain unclear. Here, we demonstrate that bilingual infants monitor and control their languages during real-time language listening, and do so similarly to bilingual adults. This ability could help bilinguals’ language learning to keep pace with that of their monolingual peers, and may underpin the cognitive advantages enjoyed by bilinguals in both infancy and adulthood.
CDCP1 drives triple-negative breast cancer metastasis through reduction of lipid-droplet abundance and stimulation of fatty acid oxidation
Authors: Wright Heather J. , Hou Jue , Xu Binzhi , Cortez Marvin , Potma Eric O. , Tromberg Bruce J. , Razorenova Olga V.
Published: August 2017

Significance

Approximately 34% of triple-negative breast cancer (TNBC) patients relapse with local recurrence or metastasis within 5 y of radiation and chemotherapy treatment. There are currently no targeted therapies to treat TNBC. This study offers therapeutic targets for blocking TNBC metastasis: cell-surface antigen CUB-domain containing protein 1 (CDCP1) and proteins in the lipid metabolism pathway. CDCP1 regulates lipid metabolism by reducing cytoplasmic lipid droplet abundance, stimulating fatty acid oxidation and oxidative phosphorylation. This metabolic pathway likely contributes to the energy production required for cell migration and metastasis of TNBC, and represents a potential therapeutic target.
Near-atomic resolution cryoelectron microscopy structure of the 30-fold homooligomeric SpoIIIAG channel essential to spore formation in
Bacillus subtilis
Authors: Zeytuni Natalie , Hong Chuan , Flanagan Kelly A. , Worrall Liam J. , Theiltges Kate A. , Vuckovic Marija , Huang Rick K. , Massoni Shawn C. , Camp Amy H. , Yu Zhiheng , Strynadka Natalie C.
Published: August 2017

Significance

Bacteria use sophisticated nanomachines to transport proteins across membranes. Although these secretion systems are typically associated with bacterial pathogenicity, a specialized variant has been proposed to play a central role in bacterial sporulation. Sporulation is a primitive protective process that allows starving cells to form spores that can survive in extreme environments. Following an asymmetric cellular division, the mother cell engulfs the forespore, with a “feeding-tube” channel creating a direct conduit between them. Here, using near-atomic resolution cryoelectron microscopy, we show that a central component of the feeding tube channel self-assembles into an unprecedented 30-fold symmetrical complex with unique architectural features and dimensions. We discuss the similarities and diverse features of the feeding tube relative to other bacterial secretion nanomachines.
Aquaporins facilitate hydrogen peroxide entry into guard cells to mediate ABA- and pathogen-triggered stomatal closure
Authors: Rodrigues Olivier , Reshetnyak Ganna , Grondin Alexandre , Saijo Yusuke , Leonhardt Nathalie , Maurel Christophe , Verdoucq Lionel
Published: August 2017

Significance

Guard cells play a crucial role in controlling transpiration and the plant water status. Here, we show that the
Arabidopsis
plasma membrane aquaporin PIP2;1 is involved in stomatal closure triggered by abscisic acid (ABA) or the pathogen-associated molecular pattern flg22. The use of a genetic probe for hydrogen peroxide (H
2
O
2
) revealed that PIP2;1 is also required for intracellular accumulation of H
2
O
2
after flg22 or ABA treatments. Our data lead to a model whereby flg22 and ABA activate PIP2;1 through phosphorylation at a conserved site to facilitate transport of both water and H
2
O
2
and promote stomatal closure. This study fills a gap in our understanding of stomatal regulation and suggests a general signaling role of aquaporin in contexts involving H
2
O
2
.
Structural insights into the catalytic mechanism of a sacrificial sulfur insertase of the N-type ATP pyrophosphatase family, LarE
Authors: Fellner Matthias , Desguin Benoît , Hausinger Robert P. , Hu Jian
Published: August 2017

Significance

Thiolation reactions are essential steps in the synthesis of numerous biological metabolites. To make the novel sulfur-containing cofactor of LarA, an Ni-dependent lactic acid racemase, LarE catalyzes a critical sulfur transfer reaction to a nicotinic acid-derived substrate by converting the protein's cysteine residue to dehydroalanine. In this study, crystal structures of ligand-free and several ligand-bound forms of LarE provide a structural basis for a catalytic mechanism that is further supported by structure-guided mutagenesis and functional assays. This work establishes LarE as a sulfur insertase within the N-type ATP pyrophosphatase family and presents a paradigm for sulfur transfer through sacrificing a catalytic cysteine residue.
High-precision chronology for Central American maize diversification from El Gigante rockshelter, Honduras
Authors: Kennett Douglas J. , Thakar Heather B. , VanDerwarker Amber M. , Webster David L. , Culleton Brendan J. , Harper Thomas K. , Kistler Logan , Scheffler Timothy E. , Hirth Kenneth
Published: August 2017

Significance

Maize was initially domesticated in the Balsas region of Mexico ∼9,000 y ago, but it remains unclear when this globally important cultigen became a staple crop in the Americas. We demonstrate that highly productive maize varieties were present in Central America outside the natural distribution of ancestral teosinte populations [
Zea mays
subspecies (ssp.)
parviglumis
] by ∼4,340 calendar years B.P., and we hypothesize that reduced introgression with
Z. mays
ssp.
parviglumis
and
Z. mays
ssp.
mexicana
was instrumental in the development of more productive staple grain varieties.
Dehumanization increases instrumental violence, but not moral violence
Authors: Rai Tage S. , Valdesolo Piercarlo , Graham Jesse
Published: August 2017

Significance

To eliminate violence, we must understand the motives that drive it. Most theories assume that violence is motivated by instrumental gain or impulsiveness, and is restrained by moral inhibitions. In these frameworks, dehumanization breaks down moral inhibitions by reducing perceptions of victims as fellow human beings worthy of concern. However, we argue that much violence is actually motivated by moral sentiments, and that morally motivated perpetrators wish to harm fellow human beings. Across five experiments, we show that dehumanizing victims increases instrumental, but not moral, violence. This distinction, between instrumental violence enabled by dehumanization, and moral violence directed toward human victims, has important implications for understanding how morality and dehumanization interact with violence, and for informing violence reduction efforts worldwide.
Molecular basis for the substrate specificity of quorum signal synthases
Authors: Dong Shi-Hui , Frane Nicole D. , Christensen Quin H. , Greenberg E. Peter , Nagarajan Rajesh , Nair Satish K.
Published: August 2017

Significance

These first structures of a homoserine-lactone quorum-signal synthase bound to various substrates and analogs help to provide a molecular rationale for understanding acyl chain specificity. Based on the structural data, we show how different clades of signal synthases can accommodate their cognate acyl–CoA ligands. Lastly, the elucidation of the reaction mechanism for the signal synthase may provide a rationale for the design of therapeutic small-molecule antagonists.
Complete overview of protein-inactivating sequence variations in 36 sequenced mouse inbred strains
Authors: Timmermans Steven , Van Montagu Marc , Libert Claude
Published: August 2017

Significance

We have developed a bioinformatics tool that allows us to compare the sequences of all protein-coding genes of 36 sequenced mouse inbred strains with the reference mouse strain C57BL/6J. We also provide an estimate of the effect on protein function of each deviant protein sequence and have built a searchable database of all these sequences, giving researchers the opportunity to search for abnormal alleles of any protein coding gene across these strains. The database makes the enormous richness of variant alleles present in these 36 inbred strains visible, accessible, and useful to the whole mouse research community.
miR-146a
–
Traf6
regulatory axis controls autoimmunity and myelopoiesis, but is dispensable for hematopoietic stem cell homeostasis and tumor suppression
Authors: Magilnick Nathaniel , Reyes Estefany Y. , Wang Wei-Le , Vonderfecht Steven L. , Gohda Jin , Inoue Jun-ichiro , Boldin Mark P.
Published: August 2017

Significance

Aberrant inflammation is the root cause of numerous human diseases, from autoimmunity to cancer.
microRNA-146a
(
miR-146a
), a member of a large class of small regulatory RNAs, functions as a critical molecular brake on inflammation and malignant transformation. However, the molecular mechanism through which
miR-146a
exerts its regulatory activity in immune cells is unclear. Using mouse genetics, we have examined the role of the
miR-146a–Traf6
signaling axis and found that although this miRNA–target interaction is responsible for regulating normal myeloid cell development and autoimmunity, it is dispensable for hematopoietic stem cell homeostasis and tumor suppression.
Permeability transition in human mitochondria persists in the absence of peripheral stalk subunits of ATP synthase
Authors: He Jiuya , Carroll Joe , Ding Shujing , Fearnley Ian M. , Walker John E.
Published: August 2017

Significance

Mitochondria generate the cellular fuel ATP to sustain complex life. Production of ATP depends on the oxidation of energy-rich compounds to produce a chemical potential difference for hydrogen ions, the proton motive force (pmf), across the inner mitochondrial membrane (IMM). Disruption of the IMM, dissipation of the pmf, and cell death occur if the concentration of calcium ions inside mitochondria is sufficiently elevated to open a pore in the IMM. The identity of the pore is disputed. One proposal is that the pore is in the enzyme that makes ATP. Here, we show that proteins in the enzyme’s peripheral stalk are not involved in the formation or regulation of the pore.
Functional New World monkey oxytocin forms elicit an altered signaling profile and promotes parental care in rats
Authors: Parreiras-e-Silva Lucas T. , Vargas-Pinilla Pedro , Duarte Diego A. , Longo Dânae , Espinoza Pardo Grace Violeta , Dulor Finkler Andrea , Paixão-Côrtes Vanessa Rodrigues , Paré Pâmela , Rovaris Diego L. , Oliveira Eduardo B. , Caceres Rafael Andrade , Gonçalves Gislene L. , Bouvier Michel , Salzano Francisco M. , Lucion Aldo B. , Costa-Neto Claudio M. , Bortolini Maria Cátira
Published: August 2017

Significance

Several forms of the oxytocin neurohormone have been found in New World monkeys (NWMs). Previous research has suggested an association between these forms and behaviors typical of this primate branch, including paternal care and monogamy. Our study provides genetic, pharmacological, behavioral, and in silico evidence supporting this connection. Rats treated intranasally with two NWM oxytocin variants showed an increase in some parental care behaviors. The same two variants were found to elicit different cell-signaling profiles in cell-based assays compared with ancestral oxytocin. Our findings highlight how mutations in the
OXT
DNA sequence coding for a nonapeptide result in distinct signaling profiles that may be linked to the emergence of novel adaptive traits, in this case, paternal care and monogamy.
3.3 Å structure of Niemann–Pick C1 protein reveals insights into the function of the C-terminal luminal domain in cholesterol transport
Authors: Li Xiaochun , Lu Feiran , Trinh Michael N. , Schmiege Philip , Seemann Joachim , Wang Jiawei , Blobel Günter
Published: August 2017

Significance

The Niemann–Pick C1 (NPC1) protein is responsible for transporting LDL-derived cholesterol out of late endosomes. Mutations in NPC1 lead to the fatal Niemann–Pick Type C disease. We present here an improved structure of an NPC1 protein at 3.3 Å and decipher details of its C-terminal luminal domain (CTD), which could not be resolved in previous structures. In particular, a loop stabilized by a pair of disulfide bonds in the CTD binds to the N-terminal domain through a loop–loop interaction. We show that this interaction is important for cholesterol transport in cultured cells. Together, our data provide insights related to the molecular mechanism of NPC1 activity and Niemann–Pick Type C disease.
Isolation and Pathogenicity of Streptococcus iniae in Cultured Red Hybrid Tilapia in Malaysia
Authors: Rahmatullah M. , Ariff M. , Kahieshesfandiari M. , Daud H. M. , Zamri-Saad M. , Sabri M. Y. , Amal M. N. A. , Ina-Salwany M. Y.
Published: August 2017

This study describes the isolation and pathogenicity of Streptococcus iniae in cultured red hybrid tilapia (Nile Tilapia Oreochromis niloticus × Mozambique Tilapia O. mossambicus) in Malaysia. The isolated gram-positive S. iniae appeared punctiform, transparently white, catalase and oxidase negative and produced complete β-hemolysis on blood agar, while a PCR assay resulted in the amplification of the 16 S rRNA gene and lactate oxidase encoded genes. The isolate was sensitive to tetracycline, vancomycin, and bacitracin but was resistant to streptomycin, ampicillin, penicillin, and erythromycin. Pathogenicity trials conducted in local red hybrid tilapia (mean ± SE = 20.00 ± 0.45 g) showed 90.0, 96.7, and 100.0% mortality within 14 d postinfection following intraperitoneal exposure to 104, 106, and 108 CFU/mL of the pathogen, respectively. The clinical signs included erratic swimming, lethargy, and inappetance at 6 h postinfection, while mortality was recorded at less than 24 h postinfection in all infected groups. The LD50-336 h of S. iniae against the red hybrid tilapia was 102 CFU/mL. The post mortem examinations revealed congested livers, kidneys, and spleens of the infected fish. This is the first report of S. iniae experimental infection in cultured red hybrid tilapia in Malaysia.

Received January 20, 2017; accepted July 16, 2017 Published online October 11, 2017
Glioblastoma stem‐like cells secrete the pro‐angiogenic VEGF‐A factor in extracellular vesicles
Authors: Treps Lucas , Perret Raul , Edmond Sébastien , Ricard Damien , Gavard Julie
Published: August 2017

Glioblastoma multiforme (GBM) are mortifying brain tumours that contain a subpopulation of tumour cells with stem‐like properties, termed glioblastoma stem‐like cells (GSCs). GSCs largely contribute to tumour initiation, propagation and resistance to current anti‐cancer therapies. GSCs are situated in perivascular niches, closely associated with brain microvascular endothelial cells, thereby involved in bidirectional molecular and cellular interactions. Moreover, extracellular vesicles are suspected to carry essential information that can adapt the microenvironment to the tumour's needs, including tumour‐induced angiogenesis. In GBM, extracellular vesicles produced by differentiated tumour cells and GSCs were demonstrated to disseminate locally and at distance. Here, we report that the pro‐angiogenic pro‐permeability factor VEGF‐A is carried in extracellular vesicles secreted from ex vivo cultured patient‐derived GSCs. Of note, extracellular vesicle‐derived VEGF‐A contributes to the in vitro elevation of permeability and angiogenic potential in human brain endothelial cells. Indeed, VEGF‐A silencing in GSCs compromised in vitro extracellular vesicle‐mediated increase in permeability and angiogenesis. From a clinical standpoint, extracellular vesicles isolated from circulating blood of GBM patients present higher levels of VEGF‐A, as compared to healthy donors. Overall, our results suggest that extracellular vesicle‐harboured VEGF‐A targets brain endothelial cells and might impact their ability to form new vessels. Thus, tumour‐released EV cargo might emerge as an instrumental part of the tumour‐induced angiogenesis and vascular permeability modus operandi in GBM.
The Allure of Tenure
Authors: Gold Katherine J.
Published: August 2017

The tenure track is a common career path for clinician–scientists who focus on research, but it comes at a life stage in which there are multiple competing personal and academic demands. The stakes for tenure review are high, with pretenure faculty at many institutions facing job loss if they are denied tenure. In academic medicine, the exacting requirements and intense demands of the tenure track frequently merge with a physician population carrying high and even unreasonable personal self-expectations of achievement. This combination can result in substantial stress on junior faculty with significant impact on personal and job satisfaction. The author uses her own experience to illustrate these themes and reflect on the circumstances surrounding clinician–scientists’ pursuit of tenure.
Becoming a Physician–Scientist: A View Looking Up From Base Camp
Authors: Ganetzky Rebecca D.
Published: August 2017

The process of becoming a physician–scientist is a long and often harrowing one. The author reflects on her own experience deciding to commit to a career as a physician–scientist and setting out on that career path. She identifies the largest challenges as the lack of clear direction to becoming a physician–scientist; the long lag time between the end of graduate medical education and becoming faculty, resulting in lower wages, less job security, and conflicts with personal goals; and a tension between traditional definitions of success and her own areas of interest. The author also reviews the advantages that led to her first faculty position as a physician–scientist: innovative educational programs that integrate medical and research training, financial support for physician investigators, a supportive educational milieu, and appropriately tailored promotion tracks. Advances on these three fronts could support increasing numbers of trainees pursuing careers as physician–scientists.
Human Metapneumovirus Infection and Acute Respiratory Distress Syndrome During Pregnancy
Authors: Fuchs Alina , McLaren Rodney , Saunders Paul , Karakash Scarlett , Minkoff Howard
Published: August 2017

BACKGROUND:

Human metapneumovirus has recently been recognized as an important cause of severe respiratory viral infections and of viral infections in patients admitted to intensive care units. Little is known about the course of this infection in pregnancy.

CASE:

A late-preterm primigravid woman was admitted to the intensive care unit for acute respiratory distress syndrome and subsequently diagnosed with human metapneumovirus. Because of worsening maternal respiratory status, she was intubated and a primary cesarean delivery was performed. The patient's respiratory status continued to decline postpartum, and she ultimately required extracorporeal membrane oxygenation. She was treated supportively until her respiratory status improved, at which time she was extubated and weaned off extracorporeal membrane oxygenation and subsequently discharged home.

CONCLUSION:

Human metapneumovirus can lead to severe respiratory illness during pregnancy.