bluuebunny/crossref_metadata_2025 huggingface dataset:
Cone degeneration is triggered by the absence of USH1 proteins but prevented by antioxidant treatments
Authors: Trouillet Alix , Dubus Elisabeth , Dégardin Julie , Estivalet Amrit , Ivkovic Ivana , Godefroy David , García-Ayuso Diego , Simonutti Manuel , Sahly Iman , Sahel José A. , El-Amraoui Aziz , Petit Christine , Picaud Serge
Published: January 2018

Usher syndrome type 1 (USH1) is a major cause of inherited deafness and blindness in humans. The eye disorder is often referred to as retinitis pigmentosa, which is characterized by a secondary cone degeneration following the rod loss. The development of treatments to prevent retinal degeneration has been hampered by the lack of clear evidence for retinal degeneration in mutant mice deficient for the Ush1 genes, which instead faithfully mimic the hearing deficit. We show that, under normal housing conditions, Ush1g−/− and Ush1c−/− albino mice have dysfunctional cone photoreceptors whereas pigmented knockout animals have normal photoreceptors. The key involvement of oxidative stress in photoreceptor apoptosis and the ensued retinal gliosis were further confirmed by their prevention when the mutant mice are reared under darkness and/or supplemented with antioxidants. The primary degeneration of cone photoreceptors contrasts with the typical forms of retinitis pigmentosa. Altogether, we propose that oxidative stress probably accounts for the high clinical heterogeneity among USH1 siblings, which also unveils potential targets for blindness prevention.
Blockade of ACK1/TNK2 To Squelch the Survival of Prostate Cancer Stem-like Cells
Authors: Mahajan Nupam P. , Coppola Domenico , Kim Jongphil , Lawrence Harshani R. , Lawrence Nicholas J. , Mahajan Kiran
Published: January 2018

Prostate cancer stem-like cells (PCSCs) are not only enriched in the CD44+PSA−/lo subpopulation but also employ androgen-independent signaling mechanisms for survival. CD44+ PCSCs defy androgen deprivation, resist chemo- and radiotherapy and are highly tumorigenic. Human prostate tissue microarray (TMA) staining revealed an increased membranous staining of CD44 in the luminal compartment in higher grade G7-G9 tumors versus staining of the basal layer in benign hyperplasia. To uncover tyrosine kinase/s critical for the survival of the CD44+PSA−/lo subpopulation, we performed an unbiased screen targeting 87 tyrosine kinases with gene specific siRNAs. Among a subset of tyrosine kinases crucial for PCSC survival, was a non-receptor tyrosine kinase, ACK1/TNK2, a critical regulator of castration resistant prostate cancer (CRPC) growth. Consistently, activated ACK1 as measured by phosphorylation at Tyr284 was significant in the CD44+PSA−/lo population. Conversely, pharmacological inhibition by ACK1 inhibitor, (R)-9bMS mitigated CD44+PSA−/lo sphere formation, overcame resistance to radiation-induced cell death, induced significant apoptosis in PCSCs and inhibited CD44+PSA−/lo xenograft tumor growth in castrated mice suggesting dependency of PCSCs on ACK1 for survival. Thus, blockade of ACK1/TNK2 could be a new therapeutic modality to target recalcitrant PCSCs.
Lithosphere strain rate and stress field orientations near the Alpine arc in Switzerland
Authors: Houlié N. , Woessner J. , Giardini D. , Rothacher M.
Published: January 2018

In this study we test whether principal components of the strain rate and stress tensors align within Switzerland. We find that 1) Helvetic Nappes line (HNL) is the relevant tectonic boundary to define different domains of crustal stress/surface strain rates orientations and 2) orientations of T- axes (of moment tensor solutions) and long-term asthenosphere cumulative finite strain (from SKS shear wave splitting) are consistent at the scale of the Alpine arc in Switzerland. At a more local scale, we find that seismic activity and surface deformation are in agreement but in three regions (Basel, Swiss Jura and Ticino); possibly because of the low levels of deformation and/or seismicity. In the Basel area, deep seismicity exists while surface deformation is absent. In the Ticino and the Swiss Jura, where seismic activity is close to absent, surface deformation is detected at a level of ~2 10−8/yr (~6.3 10−16/s).
Comparative analyses of co-evolving host-parasite associations reveal unique gene expression patterns underlying slavemaker raiding and host defensive phenotypes
Authors: Alleman Austin , Feldmeyer Barbara , Foitzik Susanne
Published: January 2018

The transition to parasitism is a drastic shift in lifestyle, involving rapid changes in gene structure, function, and expression. After the establishment of antagonistic relationships, parasites and hosts co-evolve through reciprocal adaptations, often resulting in evolutionary arms-races. Repeated evolution of social parasitism and slavery among Temnothorax ants allows us to examine those gene expression patterns that characterize slavemaker raiding and reciprocal host defensive phenotypes. Previous behavioural studies have established that raiding strategies between Temnothorax slavemakers diverge, while host defense portfolios shift similarly under parasite pressure. We are the first to confirm this at the molecular level, revealing that slavemaking species exhibit a wider variety of genes with species-specific patterns of expression within their raiding phenotypes, whereas expression similarity is commonly found during the non-raiding phenotype. Host species response to slavemaker aggression, however, is indicated by strong changes in the expression of a relatively few number genes. Additionally, the expression of individual genes such as Acyl-CoA-Delta(11) desaturase and Trypsin-7 is strongly associated with the raiding phenotype of all three slavemaking species. Here, we provide novel insight into the gene expression patterns associated with raiding and nest defense behavior in Temnothorax ants, suggesting lineage-specific evolutionary patterns among both slavemakers and hosts.
MET or NRAS amplification is an acquired resistance mechanism to the third-generation EGFR inhibitor naquotinib
Authors: Ninomiya Kiichiro , Ohashi Kadoaki , Makimoto Go , Tomida Shuta , Higo Hisao , Kayatani Hiroe , Ninomiya Takashi , Kubo Toshio , Ichihara Eiki , Hotta Katsuyuki , Tabata Masahiro , Maeda Yoshinobu , Kiura Katsuyuki
Published: January 2018

As a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), osimeritnib is the standard treatment for patients with non-small cell lung cancer harboring the EGFR T790M mutation; however, acquired resistance inevitably develops. Therefore, a next-generation treatment strategy is warranted in the osimertinib era. We investigated the mechanism of resistance to a novel EGFR-TKI, naquotinib, with the goal of developing a novel treatment strategy. We established multiple naquotinib-resistant cell lines or osimertinib-resistant cells, two of which were derived from EGFR-TKI-naïve cells; the others were derived from gefitinib- or afatinib-resistant cells harboring EGFR T790M. We comprehensively analyzed the RNA kinome sequence, but no universal gene alterations were detected in naquotinib-resistant cells. Neuroblastoma RAS viral oncogene homolog (NRAS) amplification was detected in naquotinib-resistant cells derived from gefitinib-resistant cells. The combination therapy of MEK inhibitors and naquotinib exhibited a highly beneficial effect in resistant cells with NRAS amplification, but the combination of MEK inhibitors and osimertinib had limited effects on naquotinib-resistant cells. Moreover, the combination of MEK inhibitors and naquotinib inhibited the growth of osimertinib-resistant cells, while the combination of MEK inhibitors and osimertinib had little effect on osimertinib-resistant cells. Clinical assessment of this novel combination (MEK inhibitors and naquotinib) is worth considering in osimertinib-resistant lung tumors.
Quartz-based flat-crystal resonant inelastic x-ray scattering spectrometer with sub-10 meV energy resolution
Authors: Kim Jungho , Casa D. , Said Ayman , Krakora Rich , Kim B. J. , Kasman Elina , Huang Xianrong , Gog T.
Published: January 2018

Continued improvement of the energy resolution of resonant inelastic x-ray scattering (RIXS) spectrometers is crucial for fulfilling the potential of this technique in the study of electron dynamics in materials of fundamental and technological importance. In particular, RIXS is the only alternative tool to inelastic neutron scattering capable of providing fully momentum resolved information on dynamic spin structures of magnetic materials, but is limited to systems whose magnetic excitation energy scales are comparable to the energy resolution. The state-of-the-art spherical diced crystal analyzer optics provides energy resolution as good as 25 meV but has already reached its theoretical limit. Here, we demonstrate a novel sub-10 meV RIXS spectrometer based on flat-crystal optics at the Ir-L3 absorption edge (11.215 keV) that achieves an analyzer energy resolution of 3.9 meV, very close to the theoretical value of 3.7 meV. In addition, the new spectrometer allows efficient polarization analysis without loss of energy resolution. The performance of the instrument is demonstrated using longitudinal acoustical and optical phonons in diamond, and magnon in Sr3Ir2O7. The novel sub-10 meV RIXS spectrometer thus provides a window into magnetic materials with small energy scales.
Protein corona of airborne nanoscale PM2.5 induces aberrant proliferation of human lung fibroblasts based on a 3D organotypic culture
Authors: Li Yan , Wang Pengcheng , Hu Chuanlin , Wang Kun , Chang Qing , Liu Lieju , Han Zhenggang , Shao Yang , Zhai Ying , Zuo Zhengyu , Mak Michael , Gong Zhiyong , Wu Yang
Published: January 2018

Exposure to PM2.5 has become one of the most important factors affecting public health in the world. Both clinical and research studies have suggested that PM2.5 inhalation is associated with impaired lung function. In this study, material characterization identified the existence of nanoscale particulate matter (NPM) in airborne PM2.5 samples. When coming into contact with protein-rich fluids, the NPM becomes covered by a protein layer that forms a “protein corona”. Based on a 3D organotypic cell culture, the protein corona was shown to mitigate NPM cytotoxicity and further stimulate the proliferation of human lung fibroblasts (HLFs). ROS-activated alpha-smooth muscle actin (α-SMA) is considered to be one of the proliferation pathways. In this research, 3D cell cultures exhibited more tissue-like properties compared with the growth in 2D models. Animal models have been widely used in toxicological research. However, species differences make it impossible to directly translate discoveries from animals to humans. In this research, the 3D HLF model could partly simulate the biological responses of NPM-protein corona-induced aberrant HLF proliferation in the human lung. Our 3D cellular results provide auxiliary support for an animal model in research on PM2.5-induced impaired lung function, particularly in lung fibrosis.
Covert lie detection using keyboard dynamics
Authors: Monaro Merylin , Galante Chiara , Spolaor Riccardo , Li Qian Qian , Gamberini Luciano , Conti Mauro , Sartori Giuseppe
Published: January 2018

Identifying the true identity of a subject in the absence of external verification criteria (documents, DNA, fingerprints, etc.) is an unresolved issue. Here, we report an experiment on the verification of fake identities, identified by means of their specific keystroke dynamics as analysed in their written response using a computer keyboard. Results indicate that keystroke analysis can distinguish liars from truth tellers with a high degree of accuracy - around 95% - thanks to the use of unexpected questions that efficiently facilitate the emergence of deception clues.
Solid state [2 + 2] photocycloaddition for constructing dimers of N,N′-diacyl-1,4-dihydropyrazines based on thiourea-induced assembly
Authors: Fan Qiangwen , Duan Xiaowei , Yan Hong
Published: January 2018

Unprecedented photoadducts were obtained through solid state [2 + 2] photocycloaddition of 1,4-dihydropyrazines, assembled using thiourea as a template.
Lanthanide-MOFs constructed from mixed dicarboxylate ligands as selective multi-responsive luminescent sensors
Authors: Zhang Xiaolei , Zhan Zhiying , Liang Xiaoyu , Chen Chen , Liu Xiaoli , Jia YueJiao , Hu Ming
Published: January 2018

Five novel Ln-MOFs with the isostructural 2D layered structures were synthesized and characterized. Compound 4 can detect the nitrobenzene derivatives-based explosives among the diverse organic solvents with high selectivity and sensitivity.
Surface ligand modification of cesium lead bromide nanocrystals for improved light-emitting performance
Authors: Wu Hua , Zhang Yu , Lu Min , Zhang Xiaoyu , Sun Chun , Zhang Tieqiang , Colvin Vicki L. , Yu William W.
Published: January 2018

Ammonium halide facilitated perovskite NC synthesis significantly improves the PLQY and the NC-based light-emitting performances.
Photomechanical motion of diarylethene molecular crystal nanowires
Authors: Tong Fei , Kitagawa Daichi , Dong Xinning , Kobatake Seiya , Bardeen Christopher J.
Published: January 2018

Crystalline nanowires composed of the photochromic diarylethene derivative 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene (1a) are prepared and characterized.
New insights into the nature of semi-soft elasticity and “mechanical-Fréedericksz transitions” in liquid crystal elastomers
Authors: Mistry Devesh , Morgan Philip B. , Clamp John H. , Gleeson Helen F.
Published: January 2018

Previously unseen coincidence of a semi-soft elastic-like load curve with a “mechanical-Fréedericksz transition” and negative liquid crystal order parameter (S).
Large deformation electrohydrodynamics of a Skalak elastic capsule in AC electric field
Authors: Das Sudip , Thaokar Rochish M.
Published: January 2018

The axisymmetric electrohydrodynamic deformation of an elastic capsule with a capacitive membrane obeying the Skalak law under a uniform AC electric field is investigated using analytical and boundary integral theory.
Natural Product Reports 35 years on
Authors: Moore Bradley S.
Published: January 2018

The Chair of the Natural Product Reports Editorial Board discusses how the journal has evolved since its inception.
Crystal structure of thermospermine synthase from Medicago truncatula and substrate discriminatory features of plant aminopropyltransferases
Authors: Sekula Bartosz , Dauter Zbigniew
Published: January 2018

Polyamines are linear polycationic compounds that play a crucial role in the growth and development of higher plants. One triamine (spermidine, SPD) and two tetraamine isomers (spermine, SPM, and thermospermine, TSPM) are obtained by the transfer of the aminopropyl group from decarboxylated S-adenosylmethionine to putrescine and SPD. These reactions are catalyzed by the specialized aminopropyltransferases. In that respect, plants are unique eukaryotes that have independently evolved two enzymes, thermospermine synthase (TSPS), encoded by the gene ACAULIS5, and spermine synthase, which produce TSPM and SPM, respectively. In this work, we structurally characterize the ACAULIS5 gene product, TSPS, from the model legume plant Medicago truncatula (Mt). Six crystal structures of MtTSPS — one without ligands and five in complexes with either reaction substrate (SPD), reaction product (TSPM), or one of three cofactor analogs (5′-methylthioadenosine, S-adenosylthiopropylamine, and adenosine) — give detailed insights into the biosynthesis of TSPM. Combined with small-angle X-ray scattering data, the crystal structures show that MtTSPS is a symmetric homotetramer with an interdomain eight-stranded β-barrel. Such an assembly and the presence of a hinge-like feature between N-terminal and C-terminal domains give the protein additional flexibility which potentially improves loading substrates and discarding products after the catalytic event. We also discuss the sequence and structural features around the active site of the plant aminopropyltransferases that distinguish them from each other and determine their characteristic substrate discrimination.
Improved synchronisation algorithm based on reconstructed correlation function for BOC modulation in satellite navigation and positioning system
Authors: Xiong Hailiang , Wang Songhua , Gong Shu , Peng Meixuan , Shi Junyu , Tang Juan
Published: January 2018

With the development of the new generation satellite navigation and positioning systems utilise binary offset carrier (BOC) modulation to improve inter‐operability. The main shortcoming of BOC modulation is its ambiguity of searching for a multi‐peaked auto‐correlation function (ACF). In this study, an improved unambiguous synchronisation algorithm based on compensated correlation reconstructed technique (CCRT) is proposed for the arbitrary‐order BOC, which is a new modulation technique for navigation modernisation. The key technique used in this study is to generate local reference signals with different shape vectors. By recombining the piecewise correlation functions of the step‐shape coded symbol, a reconstructed correlation function which has only one peak is obtained, and the energy loss is compensated by the ACF. In the proposed algorithm, different shape vectors are employed in different BOC modulation signals. The simulation results demonstrate that the ambiguity problem is completely eliminated. Compared with traditional synchronisation methods, the proposed algorithm shows outstanding detection and multipath mitigation performance. Moreover, the CCRT can be utilised for arbitrary stage BOC modulation signals.
Admission control algorithm based on the effective bandwidth in vehicle‐to‐infrastructure communication
Authors: Paul Mousumi , Sanyal Goutam , Samanta Debabrata , Nguyen Gia Nhu , Le Dac‐Nhuong
Published: January 2018

With pervasive of mobile computing and wireless communication, the vehicular ad‐hoc network has become a key technology in modern day's information exchange. Due to the fast growing number of vehicles and saturation of the transport infrastructure, it is inhabitable to come out with better solution considering the available resources. In this study, thorough traffic analysis has been carried out to suggest a better model. Further, an attempt has been made to propose an admission control algorithm based‐on the parameters evolve from the mathematical analysis. Moreover, the performance analysis has been shown to establish the efficacy of the algorithm.
Free space optical communications with distributed switch‐and‐stay combining
Authors: Gupta Juhi , Dwivedi Vivek K. , Karwal Vikram , Ansari Imran Shafique , Karagiannidis George K.
Published: January 2018

The authors study the performance of an amplify‐and‐forward dual‐hop, switch‐and‐stay combining receiver, used in free space optical communications over non‐identical fading channels. One path is characterised by the generalised Málaga (or M distribution), whereas the other is influenced by the combined effects of Gamma–Gamma distributed atmospheric turbulence, pointing error and path loss. Novel closed‐form expressions for the end‐to‐end moment generating function, probability density function, and cumulative distribution function are derived in terms of Meijer's G function. Furthermore, the performance of the system is analysed, and closed‐form expressions are presented for the end‐to‐end outage probability and channel capacity.
Relay performance optimisation based on signal space reconstruction
Authors: Wang Xiyuan , Wang Yong
Published: January 2018

In this study, the authors study the interference exploitation problem in multi‐input multi‐output (MIMO) multi‐way relay channel, which is MIMO Y channel. In this channel, multiple users complete the exchange of information among users through a common relay in the multiple access channel phase and broadcast phase. Each user sends signals to other users and receives the signals sent by other users. For a three‐user transmission model, each user and relay have three antennas, respectively. To achieve better decoding performance at the relay, they design precoding vectors on the basis of traditional signal space alignment (SSA) so that the intersection subspaces hold orthogonal. Corresponding optimisation rules are proposed for zero‐forcing and maximum‐likelihood decoders. It is seen from the simulation results that the proposed algorithm greatly improves the decoding accuracy compared with the traditional SSA relay decoding, and reduce the computational complexity. Because of the improvement of the performance of relay decoding, the reliability of the whole transmission system will be improved.
Millimetre‐wave dielectric resonator antenna array based on directive LTCC elements
Authors: Mrnka Michal , Cupal Miroslav , Raida Zbynek , Pietrikova Alena , Kocur Dusan
Published: January 2018

The study deals with the application of low‐temperature co‐fired ceramic (LTCC) technology for design of a higher‐order mode dielectric resonator antenna element operating at centre frequency 25.7 GHz. The LTCC material that the authors use provides very low dielectric losses and enables us to design an antenna element with very high radiation efficiency. The authors follow by examining the mutual coupling between two resonators and the authors propose a small (1 × 4) one‐dimensional antenna array composed of such elements. In order to minimise the dimensions of the ground plane and to place the connector at a convenient location, the authors design a parallel feed network in substrate integrated waveguide technology, thus reducing the radiation losses of the feeding structure. The experiments verify the four‐element antenna array concept with maximum measured gain of 16.3 dBi.
Stable marching‐on‐in‐time algorithm capable of handling multiple excitations – application to wire junction problems
Authors: Rao Sadasiva M.
Published: January 2018

In this work, a stable marching‐on‐in‐time method is presented to obtain a scattering response from arbitrary wire structures illuminated by a Gaussian plane wave directly in the time domain (TD). Contrary to all the available TD algorithms until now, the present procedure, besides being stable, is also capable of handling multiple excitations in a trivial manner. The new procedure is based on the conventional method of moments and utilises standard pulse functions for expansion of the space variable and time‐shifted Gaussian functions for the time variable. The testing procedure is accomplished by collocation. The numerical results obtained using the new procedure are validated by comparing with the data obtained from the frequency domain solution using the same modelling scheme and performing inverse discrete Fourier transform.
Design and measurement of a contactless interface between a dipole antenna and a CMOS fully integrated wireless power receiver
Authors: Menezes Thaironi , da Silva Fernanda R. , Cabrera Fabian L. , Rangel de Sousa Fernando
Published: January 2018

Here, the authors present a study on a contactless interface between a fully integrated wireless power receiver (WPR) and a dipole antenna. The authors analyse the impedance matching between the antenna and the inductive link formed by the contactless interface for providing an appropriate design methodology. Furthermore, the authors developed a measurement strategy to verify the entire system comprised by a pair of dipole antennas, the inductive link, and the CMOS WPR. The results show that the CMOS die is well coupled to the antenna, the complete system operates correctly with a source of 26.6 dBm at 987 MHz when the distance between the dipole antennas is 58 cm.
Assessment of overvoltage mitigation techniques in low‐voltage distribution networks with high penetration of photovoltaic microgeneration
Authors: Camilo Fernando M. , Castro Rui , Almeida Maria Eduarda , Fernão Pires Victor
Published: January 2018

Nowadays, a strong concern to decrease greenhouse gas emissions is encouraging the implementation of renewable energy sources closer to end‐users, in low‐voltage (LV) distribution networks. Due to the expected high microgeneration (µG) penetration level, several problems are likely to arise, such as overvoltages and reverse power flow. This study presents a review of the several techniques used to deal with these problems. These are compared in terms of their capacity to smooth the voltage profile and avoid reverse power flow. An unbalanced three‐phase power flow algorithm, based on current summation method for radial distribution networks, is proposed. A study based on a highly unbalanced test radial LV distribution network for a typical summer day, with a high µG penetration, is performed. The voltage profile, active power flow in the service transformer, and power losses on the network are the monitored electrical quantities. The obtained results indicate that self‐consumption with storage is the recommended solution to eliminate overvoltages, to avoid reverse power flow and allow for a decreasing in the power losses. Nevertheless, the economic viability of this solution must be carefully assessed, because the profitability of the project is not straightforward at the current time.
Sensitivity‐based approach for real‐time evaluation of transient stability of wind turbines interconnected to power grids
Authors: Tajdinian Mohsen , Seifi Ali Reza , Allahbakhshi Mehdi
Published: January 2018

The growth of utilisation of wind turbines in the contemporary power systems, the transient stability (TS) evaluation has turned to a challenging issue in the modern power grids. An innovative and high‐precision real‐time method based on the transient energy function (TEF) is proposed which aims to evaluate the TS of power system in the presence of wind turbines. The proposed method is designed so that the initial point of TEF is calculated precisely by performing offline calculations. Structure preserving is used to guarantee the accuracy of the proposed method in order to consider the details of power system modelling. Moreover, the proposed method takes into account the impacts of the wind turbines controllers utilising new formulation based on a sensitivity‐based approach. The new formulation is utilised to calculate the effects of the controllers reflected in the potential terms of TEF during the fault occurrence. As a result, in addition of considering fault‐on trajectory, the latter technique causes reducing the computational burden and also guarantees accurate real‐time assessment of TS. The simulation results demonstrate the efficiency and also comprehensiveness of the proposed method in calculation of critical clearing time and TS assessment.
X‐ray pulsar navigation using multiple detectors based on a new observation strategy
Authors: Guo Pengbin , Sun Jian , Xue Ju
Published: January 2018

Pulsar navigation has gradually attracted increased attention because of its unique advantages in the study of high‐attitude missions and deep space exploration. Low navigation accuracy, due to the long integration period, is one of the main problems with X‐ray pulsar navigation. In this study, a new observation strategy for pulsar navigation that could greatly increase observations compared with the traditional synchronous observation model has been proposed. Due to the uncertainty of the measured angles of the pulsar navigation model, a robust Kalman filter was designed based on the new observation model, and mathematical simulation results showed that the proposed method had improved navigation accuracy.
Generation and evolution of anisotropic turbulence and related energy transfer in drifting proton-alpha plasmas
Authors: Maneva Y. G. , Poedts S.
Published: January 2018

The power spectra of magnetic field fluctuations in the solar wind typically follow a power-law dependence with respect to the observed frequencies and wave-numbers. The background magnetic field often influences the plasma properties, setting a preferential direction for plasma heating and acceleration. At the same time the evolution of the solar-wind turbulence at the ion and electron scales is influenced by the plasma properties through local micro-instabilities and wave-particle interactions. The solar-wind-plasma temperature and the solar-wind turbulence at sub- and sup-ion scales simultaneously show anisotropic features, with different components and fluctuation power in parallel with and perpendicular to the orientation of the background magnetic field. The ratio between the power of the magnetic field fluctuations in parallel and perpendicular direction at the ion scales may vary with the heliospheric distance and depends on various parameters, including the local wave properties and nonthermal plasma features, such as temperature anisotropies and relative drift speeds. In this work we have performed two-and-a-half-dimensional hybrid simulations to study the generation and evolution of anisotropic turbulence in a drifting multi-ion species plasma. We investigate the evolution of the turbulent spectral slopes along and across the background magnetic field for the cases of initially isotropic and anisotropic turbulence. Finally, we show the effect of the various turbulent spectra for the local ion heating in the solar wind.
The atmospheric parameters of FGK stars using wavelet analysis of CORALIE spectra
Authors: Gill S. , Maxted P. F. L. , Smalley B.
Published: January 2018

Context. Atmospheric properties of F-, G- and K-type stars can be measured by spectral model fitting or with the analysis of equivalent width (EW) measurements. These methods require data with good signal-to-noise ratios (S/Ns) and reliable continuum normalisation. This is particularly challenging for the spectra we have obtained with the CORALIE échelle spectrograph for FGK stars with transiting M-dwarf companions. The spectra tend to have low S/Ns, which makes it difficult to analyse them using existing methods.

Aims. Our aim is to create a reliable automated spectral analysis routine to determine Teff, [Fe/H], V sini from the CORALIE spectra of FGK stars.

Methods. We use wavelet decomposition to distinguish between noise, continuum trends, and stellar spectral features in the CORALIE spectra. A subset of wavelet coefficients from the target spectrum are compared to those from a grid of models in a Bayesian framework to determine the posterior probability distributions of the atmospheric parameters.

Results. By testing our method using synthetic spectra we found that our method converges on the best fitting atmospheric parameters. We test the wavelet method on 20 FGK exoplanet host stars for which higher-quality data have been independently analysed using EW measurements. We find that we can determine Teff to a precision of 85 K, [Fe/H] to a precision of 0.06 dex and V sini to a precision of 1.35 km s−1 for stars with V sini ≥ 5 km s−1. We find an offset in metallicity ≈− 0.18 dex relative to the EW fitting method. We can determine log g to a precision of 0.13 dex but find systematic trends with Teff. Measurements of log g are only reliable enough to confirm dwarf-like surface gravity (log g ≈ 4.5).

Conclusions. The wavelet method can be used to determine Teff, [Fe/H], and V sini for FGK stars from CORALIE échelle spectra. Measurements of log g are unreliable but can confirm dwarf-like surface gravity. We find that our method is self consistent, and robust for spectra with S∕N  ⪆ 40.
Consistency with synchrotron emission in the bright GRB 160625B observed by Fermi
Authors: Ravasio M. E. , Oganesyan G. , Ghirlanda G. , Nava L. , Ghisellini G. , Pescalli A. , Celotti A.
Published: January 2018

We present time-resolved spectral analysis of prompt emission from GRB 160625B, one of the brightest bursts ever detected by Fermi in its nine years of operations. Standard empirical functions fail to provide an acceptable fit to the GBM spectral data, which instead require the addition of a low-energy break to the fitting function. We introduce a new fitting function, called 2SBPL, consisting of three smoothly connected power laws. Fitting this model to the data, the goodness of the fits significantly improves and the spectral parameters are well constrained. We also test a spectral model that combines non-thermal and thermal (black body) components, but find that the 2SBPL model is systematically favoured. The spectral evolution shows that the spectral break is located around Ebreak ~100 keV, while the usual νFν peak energy feature Epeak evolves in the 0.5–6 MeV energy range. The slopes below and above Ebreak are consistent with the values –0.67 and –1.5, respectively, expected from synchrotron emission produced by a relativistic electron population with a low-energy cut-off. If Ebreak is interpreted as the synchrotron cooling frequency, the implied magnetic field in the emitting region is ~10 Gauss, i.e. orders of magnitudes smaller than the value expected for a dissipation region located at ~1013−14 cm from the central engine. The low ratio between Epeak and Ebreak implies that the radiative cooling is incomplete, contrary to what is expected in strongly magnetized and compact emitting regions.
Anti-glioma Efficacy and Mechanism of Action of Tripolinolate A from Tripolium pannonicum
Authors: Chai Weiyun , Chen Lu , Lian Xiao-Yuan , Zhang Zhizhen
Published: January 2018

Tripolinolate A as a new bioactive phenolic ester was previously isolated from a halophyte of Tripolium pannonicum. However, the in vitro and in vivo anti-glioma effects and mechanism of tripolinolate A have not been investigated. This study has demonstrated that (1) tripolinolate A inhibited the proliferation of different glioma cells with IC50 values of 7.97 to 14.02 µM and had a significant inhibitory effect on the glioma growth in U87MG xenograft nude mice, (2) tripolinolate A induced apoptosis in glioma cells by downregulating the expressions of antiapoptotic proteins and arrested glioma cell cycle at the G2/M phase by reducing the expression levels of cell cycle regulators, and (3) tripolinolate A also remarkably reduced the expression levels of several glioma metabolic enzymes and transcription factors. All data together suggested that tripolinolate A had significant in vitro and in vivo anti-glioma effects and the regulation of multiple tumor-related regulators and transcription factors might be responsible for the activities of tripolinolate A against glioma.
Kinetic energy classification and smoothing for compact B-spline basis sets in quantum Monte Carlo
Authors: Krogel Jaron T. , Reboredo Fernando A.
Published: January 2018

Quantum Monte Carlo calculations of defect properties of transition metal oxides have become feasible in recent years due to increases in computing power. As the system size has grown, availability of on-node memory has become a limiting factor. Saving memory while minimizing computational cost is now a priority. The main growth in memory demand stems from the B-spline representation of the single particle orbitals, especially for heavier elements such as transition metals where semi-core states are present. Despite the associated memory costs, splines are computationally efficient. In this work, we explore alternatives to reduce the memory usage of splined orbitals without significantly affecting numerical fidelity or computational efficiency. We make use of the kinetic energy operator to both classify and smooth the occupied set of orbitals prior to splining. By using a partitioning scheme based on the per-orbital kinetic energy distributions, we show that memory savings of about 50% is possible for select transition metal oxide systems. For production supercells of practical interest, our scheme incurs a performance penalty of less than 5%.
On the transient flow inside and around a deforming millimetre class oil droplet falling under the action of gravity in stagnant air
Authors: Bergeles K. , Hardalupas Y. , Taylor A. M. K. P.
Published: January 2018

The liquid flow inside, and the induced air flow around, a falling droplet in stagnant air was numerically investigated using the volume of fluid method to describe the droplet interface. The droplet consisted of oil with the same surface tension and with viscosity as parameter. It was injected into stagnant air with an initial velocity of 1 m/s; therefore, the initial Weber (We = 0.14), Reynolds (Re = 141), and Bond (Bo = 2.4) numbers remained constant during the parametric study whilst the initial Capillary (Ca) and Ohnesorge (Oh) numbers varied by an order of magnitude from 0.46 to 4.6 and from 0.044 to 0.44, respectively. We examined the effect of viscosity on the flow inside, and around, the droplet as well as on the droplet deformation and its natural frequency. This investigation showed a strong dependence of the deformation with liquid viscosity. Specifically, the droplets achieved their final deformation in under-damped, for low viscosity, and in over-damped, for high viscosity, oscillation modes. After a critical time tcrit (or Recrit), the instantaneous air flow symmetry was disturbed, initially in the wake and soon after in the interior of the droplet and in the vortex shedding downstream of the droplet. The air flow in the wake region detached from the droplet surface and resulted in a wake which was approximately 1.5 times longer and wider than the wake behind a solid sphere at the same Re number at steady state conditions. A roller-vortex structure (called rollex) was established upon injection in the immediate wake of the droplet, forming the necessary kinematic link between the directions of the internal circulation in the droplet (Hill vortex) and of the external recirculating air flow in the droplet’s wake. The droplet drag coefficients were compared with corresponding values used in droplet breakup models: although, ultimately, the droplet drag coefficient converged to the values given by the models, the initial magnitudes after injection were incorrect.
Photodissociation of aligned CH3I and C6H3F2I molecules probed with time-resolved Coulomb explosion imaging by site-selective extreme ultraviolet ionization
Authors: Amini Kasra , Savelyev Evgeny , Brauße Felix , Berrah Nora , Bomme Cédric , Brouard Mark , Burt Michael , Christensen Lauge , Düsterer Stefan , Erk Benjamin , Höppner Hauke , Kierspel Thomas , Krecinic Faruk , Lauer Alexandra , Lee Jason W. L. , Müller Maria , Müller Erland , Mullins Terence , Redlin Harald , Schirmel Nora , Thøgersen Jan , Techert Simone , Toleikis Sven , Treusch Rolf , Trippel Sebastian , Ulmer Anatoli , Vallance Claire , Wiese Joss , Johnsson Per , Küpper Jochen , Rudenko Artem , Rouzée Arnaud , Stapelfeldt Henrik , Rolles Daniel , Boll Rebecca
Published: January 2018

We explore time-resolved Coulomb explosion induced by intense, extreme ultraviolet (XUV) femtosecond pulses from a free-electron laser as a method to image photo-induced molecular dynamics in two molecules, iodomethane and 2,6-difluoroiodobenzene. At an excitation wavelength of 267 nm, the dominant reaction pathway in both molecules is neutral dissociation via cleavage of the carbon–iodine bond. This allows investigating the influence of the molecular environment on the absorption of an intense, femtosecond XUV pulse and the subsequent Coulomb explosion process. We find that the XUV probe pulse induces local inner-shell ionization of atomic iodine in dissociating iodomethane, in contrast to non-selective ionization of all photofragments in difluoroiodobenzene. The results reveal evidence of electron transfer from methyl and phenyl moieties to a multiply charged iodine ion. In addition, indications for ultrafast charge rearrangement on the phenyl radical are found, suggesting that time-resolved Coulomb explosion imaging is sensitive to the localization of charge in extended molecules.
Development of a multistage compliant mechanism with new boundary constraint
Authors: Ling Mingxiang , Cao Junyi , Jiang Zhou , Li Qisheng
Published: January 2018

This paper presents a piezo-actuated compliant mechanism with a new boundary constraint to provide concurrent large workspace and high dynamic frequency for precision positioning or other flexible manipulation applications. A two-stage rhombus-type displacement amplifier with the “sliding-sliding” boundary constraint is presented to maximize the dynamic frequency while retaining a large output displacement. The vibration mode is also improved by the designed boundary constraint. A theoretical kinematic model of the compliant mechanism is established to optimize the geometric parameters, and a prototype is fabricated with a compact dimension of 60 mm × 60 mm × 12 mm. The experimental testing shows that the maximum stroke is approximately 0.6 mm and the output stiffness is 1.1 N/μm with the fundamental frequency of larger than 2.2 kHz. Lastly, the excellent performance of the presented compliant mechanism is compared with several mechanisms in the previous literature. As a conclusion, the presented boundary constraint strategy provides a new way to balance the trade-off between the frequency response and the stroke range widely existed in compliant mechanisms.
Pressure-induced topological phase transitions and structural transition in 1T-TiTe2 single crystal
Authors: Zhang Min , Wang Xiangqi , Rahman Azizur , Zeng Qunsong , Huang Da , Dai Rucheng , Wang Zhongping , Zhang Zengming
Published: January 2018

High pressure in situ Raman scattering and electrical resistivity measurements were performed to investigate the phase transitions in a semimetal 1T-TiTe2 single crystal up to 17 GPa. Combining anomalous experimental results with the electronic band structures and Z2 topological invariants in calculations, two topological phase transitions and one structural phase transition were confirmed at 1.7 GPa, 3 GPa, and 8 GPa, respectively. These two topological transformations are due to the enhanced orbital hybridization followed by a few of band inversions near the Fermi level, and the further parity analysis manifested that the phases II and III correspond to a strong topological state and a weak topological state, respectively. The rich topology variation of 1T-TiTe2 under high pressure provides a potential candidate for understanding the relevant topology physics and probable applications. The current results also demonstrate that Raman spectroscopy and electrical transport measurements are efficient tools to detect the topological phase transition under high pressure.
Wavelength-dependent visible light response in vertically aligned nanohelical TiO2-based Schottky diodes
Authors: Kwon Hyunah , Sung Ji Ho , Lee Yuna , Jo Moon-Ho , Kim Jong Kyu
Published: January 2018

Enhancements in photocatalytic performance under visible light have been reported by noble metal functionalization on nanostructured TiO2; however, the non-uniform and discrete distribution of metal nanoparticles on the TiO2 surface makes it difficult to directly clarify the optical and electrical mechanisms. Here, we investigate the light absorption and the charge separation at the metal/TiO2 Schottky junctions by using a unique device architecture with an array of TiO2 nanohelixes (NHs) forming Schottky junctions both with Au-top and Pt-bottom electrodes. Wavelength-dependent photocurrent measurements through the Pt/TiO2 NHs/Au structures revealed that the origin of the visible light absorption and the separation of photogenerated carriers is the internal photoemission at the metal/nanostructured TiO2 Schottky junctions. In addition, a huge persistent photoconductivity was observed by the time-dependent photocurrent measurement, implying a long lifetime of the photogenerated carriers before recombination. We believe that the results help one to understand the role of metal functionalization on TiO2 and hence to enhance the photocatalytic efficiency by utilizing appropriately designed Schottky junctions.
Communication: Modeling electrolyte mixtures with concentration dependent dielectric permittivity
Authors: Chen Hsieh , Panagiotopoulos Athanassios Z.
Published: January 2018

We report a new implicit-solvent simulation model for electrolyte mixtures based on the concept of concentration dependent dielectric permittivity. A combining rule is found to predict the dielectric permittivity of electrolyte mixtures based on the experimentally measured dielectric permittivity for pure electrolytes as well as the mole fractions of the electrolytes in mixtures. Using grand canonical Monte Carlo simulations, we demonstrate that this approach allows us to accurately reproduce the mean ionic activity coefficients of NaCl in NaCl–CaCl2 mixtures at ionic strengths up to I = 3M. These results are important for thermodynamic studies of geologically relevant brines and physiological fluids.
Nutritional status affects the microRNA profile of the hypothalamus of female sheep
Authors: Yang Heng , Lin Shan , Lei Xiaoping , Yuan Cong , Yu Yaosheng , Zhao Zongsheng , Chen Jingbo
Published: January 2018

Recent studies on the seasonal regulation of the oestrous cycle in sheep have focussed mainly on the responses to photoperiod. However, the brain systems that control reproductive activity also respond to nutritional inputs, although the molecular mechanisms involved are not completely understood. One possibility is that small, non-coding RNAs, such as micro-RNAs (miRNAs), have significant influence. In the present study, the amounts and characteristics of miRNAs in hypothalamus from oestrous and anestrous ewes, fed low- or high-nutrient diets, were compared using Illumina HiSeq sequencing technology. In total, 398 miRNAs, including 261 novel miRNAs, were identified in ewes with an enhanced nutritional status (HEN), whereas 384 miRNAs, including 247 novel miRNAs, were identified in the ewes with a lesser nutritional status (HAN). There were eight conserved and 140 novel miRNAs expressed differentially between the two libraries. Based on quantitative real-time polymerase chain reaction, six miRNAs were assessed to verify the accuracy of the library database. Moreover, the correlation between the miRNA target and several upstream and downstream genes in the oestrus-related pathways were also verified in hypothalamus nerve cells. According to the results, nutritional status plays an important role in oestrous regulation in sheep, and the hypothalamic processes and pathways induced by nutritional signals (folic acid and tyrosine) are different from those induced by photoperiodic regulation of oestrus. We have expanded the repertoire of sheep miRNAs that could contribute to the molecular mechanisms that regulate the initiation of oestrous cycles in anestrous ewes in response to the influence of nutritional status.
On the genesis of Robert P. Langlands’ conjectures and his letter to André Weil
Authors: Mueller Julia
Published: January 2018

This article is an introduction to the early life and work of Robert P. Langlands, creator and founder of the Langlands program. The story is, to a large extent, told by Langlands himself, in his own words. Our focus is on two of Langlands’ major discoveries: automorphic

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-functions and the principle of functoriality. It was Langlands’ desire to communicate his excitement about his newly discovered objects that resulted in his famous letter to André Weil. This article is aimed at a general mathematical audience and we have purposely not included the more technical aspects of Langlands’ work.
Néron-Tate heights of cycles on jacobians
Authors: de Jong Robin
Published: January 2018

We develop a method to calculate the Néron-Tate height of tautological integral cycles on jacobians of curves defined over number fields. As examples we obtain closed expressions for the Néron-Tate height of the difference surface, the Abel-Jacobi images of the square of the curve, and of any symmetric theta divisor. As applications we obtain a new effective positive lower bound for the essential minimum of any Abel-Jacobi image of the curve and a proof, in the case of jacobians, of a formula proposed by Autissier relating the Faltings height of a principally polarized abelian variety with the Néron-Tate height of a symmetric theta divisor.