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Radio telescopes with dual linearly polarized feeds regularly participate in Very Long Baseline Interferometry. One example is the VLBI Global Observing System (VGOS), which is employed for high‐precision geodesy and astrometry. In order to achieve the maximum signal‐to‐noise ratio, the visibilities of all four polarization products are combined to Stokes I before fringe‐fitting. Our aim is to improve cross‐polarization bandpass calibration, which is an essential processing step in this context. Here we investigate the shapes of these station‐specific quantities as a function of frequency and time. We observed the extra‐galactic source 4C 39.25 for 6 hours with a VGOS network. We correlated the data with the DiFX software and analyzed the visibilities with PolConvert to determine the complex cross‐bandpasses with high accuracy. Their frequency‐dependent shape is to first order characterized by a group delay between the two orthogonal polarizations, in the order of several hundred picoseconds. We find that this group delay shows systematic variability in the range of a few picoseconds, but can remain stable within this range for several years, as evident from earlier sessions. On top of the linear phase‐frequency relationship there are systematic deviations of several tens of degrees, which in addition are subject to smooth temporal evolution. The antenna cross‐bandpasses are variable on time scales of ∼1 hr, which defines the frequency of necessary calibrator scans. The source 4C 39.25 is confirmed as an excellent cross‐bandpass calibrator. Dedicated surveys are highly encouraged to search for more calibrators of similar quality. Key Points: The new‐generation geodetic radio telescopes observe two orthogonal linear polarization directionsCalibration of the gain differences between the two polarizers is necessary to maximize the signal‐to‐noise ratio of observationsWe investigate these cross‐polarization gain differences and their temporal evolution for selected antennas [ABSTRACT FROM AUTHOR]

In this paper, a hybrid nanogenerator with concurrently harvested piezoelectric and triboelectric mechanisms, called a fully encapsulated piezoelectric--triboelectric hybrid nanogenerator (PTHG), is demonstrated. In the construction of piezoelectric nanogenerator (PENG), an in-situ poling near-field electrospinning (NFES) was utilized to direct-write piezoelectric polymeric nano/micro fibers (NMFs) polyvinylidene fluoride (PVDF) as the functional layer of piezoelectric nanogenerators. On the other hand, the nano-textured functional layer of triboelectric nanogenerators (TENGs) is also concurrently combined with PENG. This hybridized nanogenerator was demonstrated to simultaneously harvest piezoelectric and triboelectric output such that the superimposed peak output voltage /current signals of ~130 V/4 µA at 2 Hz, which can be translated to the area power density of 8.34 mW/m2. Individually measured TENG under a hand-induced strain 0.2 and 2 Hz actuation, the output voltage/current peak is measured about 110 V/2.8 µA, while the PENG counterpart shows the the output voltage/current peak is about 18 V/0.6 µA. In addition, the proposed PTHG can harvest sustainable energy sources such as rain water with the output maximum voltage reaches ~20 V and area power density ~0.981 mW/m² for dropping rate of 10 ml/s. This research shows the substantial improvement in the synergy of nano-textured triboelectric and piezoelectric functional layers. The practical application of the self-powered system can be ubiquitously implemented in the sustainable energy sources and future industry 4.0 scenarios to provide the stand alone energy sources of IoT sensors. [ABSTRACT FROM AUTHOR]

Summary: Activated acid-sensing ion channel 1a (ASIC1a) is involved in acid-induced osteoclastogenesis by regulating activation of the transcription factor NFATc1. These results indicated that ASIC1a activation by extracellular acid may cause osteoclast migration and adhesion through Ca-dependent integrin/Pyk2/Src signaling pathway. Introduction: Osteoclast adhesion and migration are responsible for osteoporotic bone loss. Acidic conditions promote osteoclastogenesis. ASIC1a in osteoclasts is associated with acid-induced osteoclastogenesis through modulating transcription factor NFATc1 activation. However, the influence and the detailed mechanism of ASIC1a in regulating osteoclast adhesion and migration, in response to extracellular acid, are not well characterized. Methods: In this study, knockdown of ASIC1a was achieved in bone marrow macrophage cells using small interfering RNA (siRNA). The adhesion and migration abilities of osteoclast precursors and osteoclasts were determined by adhesion and migration assays, in vitro. Bone resorption was performed to measure osteoclast function. Cytoskeletal changes were assessed by F-actin ring formation. αvβ3 integrin expression in osteoclasts was measured by flow cytometry. Western blotting and co-immunoprecipitation were performed to measure alterations in integrin/Pyk2/Src signaling pathway. Results: Our results showed that blockade of ASIC1a using ASIC1a-siRNA inhibited acid-induced osteoclast precursor migration and adhesion, as well as osteoclast adhesion and bone resorption; we also demonstrated that inhibition of ASIC1a decreased the cell surface αvβ3 integrin and β3 protein expression. Moreover, blocking of ASIC1a inhibited acidosis-induced actin ring formation and reduced Pyk2 and Src phosphorylation in osteoclasts and also inhibited the acid-induced association of the αvβ3 integrin/Src/Pyk2. Conclusion: Together, these results highlight a key functional role of ASIC1a/αvβ3 integrin/Pyk2/Src signaling pathway in migration and adhesion of osteoclasts. [ABSTRACT FROM AUTHOR]

The effects of the waveguide layer on the band structure of Rayleigh waves are studied in this work based on a one-dimensional acoustic superlattice lithium niobate substrate coated with a waveguide layer. The present phononic structure is formed by the periodic domain-inverted single crystal that is the Z-cut lithium niobate substrate with a waveguide layer on the upper surface. The plane wave expansion method (PWE) is adopted to determine the band gap behavior of the phononic structure and validated by the finite element method (FEM). The FEM is also used to investigate the transmission of Rayleigh waves in the phononic structure with the interdigital transducers by means of the commercial package COMSOL. The results show that, although there is a homogeneous waveguide layer on the surface, the band gap of Rayleigh waves still exist. It is also found that increasing the thickness of the waveguide layer, the band width narrows and the band structure shifts to lower frequency. The present approach can be taken as an efficient tool in designing of phononic structures with waveguide layer. [ABSTRACT FROM AUTHOR]

We presented a new logarithmic-quadratic proximal alternating direction scheme for the separable constrained convex programming problem. The predictor is obtained by solving series of related systems of non-linear equations in a parallel wise. The new iterate is obtained by searching the optimal step size along a new descent direction. The new direction is obtained by the linear combination of two descent directions. Global convergence of the proposed method is proved under certain assumptions. We show theO(1 / t) convergence rate for the parallel LQP alternating direction method. [ABSTRACT FROM PUBLISHER]

Composites LiNi0.5Mn1.5O4-NiO nanosticks were prepared by a simple molten salt route of adding MnSO4 to molten LiNO3, NaNO3 and slightly excess NiSO4·6H2O. Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) investigations revealed that one-dimensional composites LiNi0.5Mn1.5O4-NiO nanosticks were generated in a large quantity. The result of dc and ac magnetisation, as well as magnetic hysteresis measurements, shows that three different magnetic phases, i.e. ferrimagnetic, antiferromagnetic (AFM) and spin-glass-like (SGL) phases may coexist in LiNi0.5Mn1.5O4-NiO nanocomposites. Furthermore, magnetic measurements suggest that the exchange bias (EB) effect was obtained at low temperature. [ABSTRACT FROM AUTHOR]

The response of soil respiration (Rs) and its components (autotrophic [Ra] and heterotrophic respiration [Rh]) to climate warming is one of the uncertainties in ecosystem carbon (C) models. Here we conducted a warming experiment in an alpine meadow dominated by Koresbia in the permafrost region of the Qinghai-Tibet Plateau (QTP) to examine effects of warming on Rs and its components. Infrared heaters were used to simulate a 2°C warming of the surface soil temperature. Deep collars (50 cm to exclude root growth) were inserted into soil to measure Rh: Ra, which was calculated by subtracting Rhfrom Rs. Average Rs and its components (Ra and Rh) were significantly stimulated by 21.5, 27 and 15.6%, respectively, in warmed plots from January 2011 to October 2013. The contribution of Rh to Rs decreased in the warmed plots because of the smaller relative increase in Rh than in Ra. Annual soil C release increased by 263 and 247 gCm-2 in 2011 and 2012, respectively. Stimulation in Ra and Rh was related to the significant increase in root biomass (0-50 cm) and in labile soil C in the deeper layer (40-50 cm). The temperature sensitivities (Q10) of Rs and its components all increased with larger values in Ra, followed by Rs and Rh. Our results suggest a positive feedback between soil C release and climatic warming in the permafrost region of the QTP. [ABSTRACT FROM AUTHOR]

Proton acceleration from 4 im thick aluminum foils irradiated by 30-TW Ti:sapphire laser pulses is investigated using an angle-resolved proton energy spectrometer. We find that a modulated spectral peak at ~0.82 MeV is presented at 2.5° off the target normal direction. The divergence angle of the modulated zone is 3.8°. Two-dimensional particle-in-cell simulations reveal that self-generated toroidal magnetic field at the rear surface of the target foil is responsible for the modulated spectral feature. The field deflects the low energy protons, resulting in the modulated energy spectrum with certain peaks. [ABSTRACT FROM AUTHOR]

The epoch International Celestial Reference Frame (epoch ICRF) is proposed as a new concept in order to consider the effect of apparent proper motion of the position of a radio source due to acceleration of the spatial origin of the ICRF, the centre of mass of the Solar system. This apparent proper motion has a magnitude of approximately 5.8 microarcsec (μas) per year, and for the 30-year very long baseline interferometry (VLBI) observational history these position variations will exceed 100 µas. We show that the dipole structure of the apparent proper motions leads to global rotation in the ICRF2 and the main term, the shift of direction of the origin of right ascension, reaches 25 µas per century. The 'epoch ICRF' is constructed using epoch positions at J2000.0 and apparent proper motions of radio sources, which are reported here for 295 ICRF2-defining sources. [ABSTRACT FROM AUTHOR]

This paper presents a sensorless bifilar wound permanent magnet brushless DC (BW-PMBLDC) motor fan for automotive engine cooling applications. The key is to incorporate the bifilar winding design into the conventional half-wave PMBLDC motor. Due to the perfect flux-coupling effect between bifilar winding, a regenerative capability is developed so that the trapped energy in the conducting winding during the turn-off period can be re-dumped to DC source through the other winding in the bifilar pair, hence effectively promoting the energy efficiency and repressing the voltage spikes. Moreover, the complementary scheme developed between the bifilar wound phases enables bipolar excitation on the unipolar converter topology. Therefore, the BWPMBLDC motor cannot only offer the advantages of full-wave motor in efficiency, voltage spike reduction, and low torque ripple, but also retain the advantages of simplicity and robustness of unipolar converter topology. Both simulation and experimental results are presented to validate the feasibility. [ABSTRACT FROM AUTHOR]

Aims. The three-dimensional acceleration vector of the solar system barycenter was estimated from VLBI delay observations. We also provide a first physical explanation for this acceleration vector. Methods. Two methods for the acceleration estimation were developed in the analysis of the global astrometric/geodetic VLBI observations. One is to take the solar acceleration vector as a global parameter that is to be directly estimated. The second method is to obtain the acceleration by fitting the solar velocity variation time series produced from the VLBI data analysis. Results. The results of these two methods are consistent with each other within their uncertainties. The acceleration vector derived from the first method is (7.47 ± 0.46, 0.17 ± 0.57, 3.95 ± 0.47) mm s-1 yr-1 in the Galactic Cartesian coordinate system. Conclusions. The Galactocentric component of the solar acceleration we obtained agrees well with the predicted value from the rotation movement of the Sun and has a high accuracy. The detected strong vertical component perpendicular to the Galactic plane may be important for the research of the Milky Way. [ABSTRACT FROM AUTHOR]

A simple method to enhance ion generation with femtosecond ultraintense lasers is demonstrated experimentally by defocusing laser beams on target surface. When the laser is optimally defocused, we find that the population of medium and low energy protons from ultra-thin foils is increased significantly while the proton cutoff energy is almost unchanged. In this way, the total proton yield can be enhanced by more than 1 order, even though the peak laser intensity drops. The depression of the amplified spontaneous emission (ASE) effect and the population increase of moderate-energy electrons are believed to be the main reasons for the effective enhancement. [ABSTRACT FROM AUTHOR]

Let S be a closed convex set of matrices and C be a given matrix. The matrix nearness problem considered in this paper is to find a matrix X in the set S at which max {∣xij - cij ∣} reaches its minimum value. In order to solve the matrix nearness problem, the problem is reformulated to a min-max problem firstly, then the relationship between the min-max problem and a monotone linear variational inequality (LVI) is built. Since the matrix in the LVI problem has a special structure, a projection and contraction method is suggested to solve this LVI problem. Moreover, some implementing details of the method are presented in this paper. Finally, preliminary numerical results are reported, which show that this simple algorithm is promising for this matrix nearness problem. [ABSTRACT FROM AUTHOR]

In this paper, a class of bi-level variational inequalities for describing some practical equilibrium problems, which especially arise from engineering, management and economics, is presented, and a neural network approach for solving the bi-level variational inequalities is proposed. The energy function and neural dynamics of the proposed neural network are defined in this paper, and then the existence of the solution and the asymptotic stability of the neural network are shown. The simulation algorithm is presented and the performance of the proposed neural network approach is demonstrated by some numerical examples. [ABSTRACT FROM AUTHOR]

Target normal measurements of proton energy spectra from ultrathin (50-200 nm) planar foil targets irradiated by 1019Wcm-2 40 fs laser pulses exhibit broad maxima that are not present in the energy spectra from micron thickness targets (6μm). The proton flux in the peak is considerably greater than the proton flux observed in the same energy range in thicker targets. Numerical modelling of the experiment indicates that this spectral modification in thin targets is caused by magnetic fields that grow at the rear of the target during the laser-target interaction. [ABSTRACT FROM AUTHOR]

The spatial and energy distributions of fast electrons emitted from foil targets irradiated by ultrashort intense laser pulses are measured. Four groups of collimated emissions of fast electrons along the front and rear target surfaces are observed for an incidence angle of <60°. This multipeak characterization is found to be independent of laser polarization states. Numerical simulations reveal that the electron beams are formed due to the deformation of the target surface and then guided by the induced quasistatic electromagnetic fields. [ABSTRACT FROM AUTHOR]

In the alternating directions method, the relaxation factor γ ϵ (0, √5+1―2 ) by Glowinski is useful in practical computations for structured variational inequalities. This paper points out that the same restriction region of the relaxation factor is also valid in the proximal alternating directions method. [ABSTRACT FROM AUTHOR]

The characteristics of proton beam generated in the interaction of an ultrashort laser pulse with a large prepulse with solid foils are experimentally investigated. It is found that the proton beam emitted from the rear surface is not well collimated, and a “ring-like” structure with some “burst-like” angular modulation is presented in the spatial distribution. The divergence of the proton beam reduces significantly when the laser intensity is decreased. The “burst-like” modulation gradually fades out for the thicker target. It is believed that the large divergence angle and the modulated ring structure are caused by the shock wave induced by the large laser prepulse. A one-dimensional hydrodynamic code, MED103, is used to simulate the behavior of the shock wave produced by the prepulse. The simulation indicates that the rear surface of the foil target is significantly modified by the shock wave, consequently resulting in the experimental observations. [ABSTRACT FROM AUTHOR]

The PhotoAcoustic (PA) method has been used to study the optical resonance absorptions on corrugated surfaces. The resonance absorptions due to the excitations of surface plasmons and guide-waves of corrugated surfaces have been measured experimentally, and the effects of the groove depth and period of the corrugated surface on the absorption curve have been observed. Moreover, the differential method based on the rigorous use of electromagnetic theory is used to calculate the parameters of the grooves and the optical absorptivities of the samples. The theoretical results on the resonance absorption peaks are in good agreement with those of the PA experiments. Then, the parameters of the grooves can be estimated by the PA investigations. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to an article by D. Luo and colleagues on the impact of rapamycin on bone mineral density, in which they discussed substantial sex differences in pathophysiology of osteoporosis, and the need for a better investigation of rapamycin-modulated autophagy in female rats.

We studied the transport of an intense electron beam produced by high intensity laser pulses through metals and insulators. Targets were irradiated at two different intensities, 1017 W/cm2 and 1019 W/cm2, at the laser facility Xtreme Light XL-III in Beijing, a Ti:Sa laser source emitting 40 fs pulses at 800 nm. The main diagnostic was Cu-Kα fluorescence imaging. Images of Kα spots have been collected for those two laser intensities, for different target thickness, and for different materials. Experimental results are analyzed taking into account both collisional and collective effects as well as refluxing at the edge of the target. The target temperature is evaluated to be Tc ∼ 6 eV for intensity I = 1017 W/cm2 (for all the tested materials: plastic, aluminium, and copper), and Tc ∼ 60 eV in aluminium and 120 eV in titanium for intensity I = 1019 W/cm2. [ABSTRACT FROM AUTHOR]