Gravitational Wave Radiation from Newborn Accreting Magnetars

The observed electromagnetic radiation from some long and short gamma-ray bursts,and neutron stars(NSs),and the theoretical models proposed to interpret these observations together point to a very interesting but confusing problem,namely,whether fall-back accretion could lead to dipole field decay of newborn NSs.In this paper,we investigate the gravitational wave(GW) radiation of newborn magnetars with a fall-back disk formed in both the core-collapse of massive stars and the merger of binary NSs.We make a comparison of the results obtained with and without fall-back accretion-induced dipole-field decay(FADD) involved.Depending on the fall-back parameters,initial parameters of newborn magnetars,and models used to describe FADD,FADD may indeed occur in newborn magnetars.Because of the low dipole fields caused by FADD,the newborn magnetars will be spun up to higher frequencies and have larger masses in comparison with the non-decay cases.Thus the GW radiation of newborn accreting magnetars would be remarkably enhanced.We propose that observation of GW signals from newborn magnetars using future GW detectors may help to reveal whether FADD could occur in newborn accreting magnetars.Our model is also applied to the discussion of the remnant of GW170817.From the post-merger GW searching results of Advanced LIGO and Advanced Virgo we cannot confirm the remnant is a low-dipole-field long-lived NS.Future detection of GWs from GW170817-like events using more sensitive detectors may help to clarify the FADD puzzle.

Probing the Internal Physics of Neutron Stars through the Observed Braking Indices and Magnetic Tilt Angles of Several Young Pulsars

The braking indices of pulsars may contain important information about the internal physics of neutron stars(NSs),such as neutron superfluidity and internal magnetic fields.As a subsequent paper of Cheng et al.,we perform the same analysis as that done in the previous paper to other young pulsars with a steady braking index,n.Combining the timing data of these pulsars with the theory of magnetic field decay,and using their measured magnetic tilt angles,we can set constraints on the number of precession cycles,ξ,which represents the interactions between superfluid neutrons and other particles in the NS interior.For the pulsars considered in this paper,the results show thatξis within the range of a few×10~3 to a few×10~6.Interestingly,for the Crab and Vela pulsars,the constraints onξobtained with our method are generally consistent with that derived from modeling of the glitch rise behaviors of the two pulsars.Furthermore,we find that the internal magnetic fields of pulsar with n<3 may be dominated by the toroidal components.Our results may not only help to understand the interactions between the superfluid neutrons and other particles in the interior of NSs but also be important for the study of continuous gravitational waves from pulsars.

The design and implementation of a ROACH2+GPU based correlator on the Tianlai dish array

A digital correlator is a crucial element in a modern radio telescope.In this paper,we describe a scalable design for the correlator system of the Tianlai pathfinder array,which is an experiment dedicated to testing key technologies for conducting a 21cm intensity mapping survey.The correlator implements the FX design,which firstly performs a fast Fourier transform(FFT) including polyphase filter bank(PFB) computation using a Collaboration for Astronomy Signal Processing and Electronics Research(CASPER) Reconfigurable Open Architecture Computing Hardware-2(ROACH2) board,then computes cross-correlations by employing Graphics Processing Units(GPUs).The design has been tested both in laboratory and in actual observation.

Contrast-enhanced ultrasound predicts microvascular invasion in patients with hepatocellular carcinoma

To the Editor:The presence of microvascular invasion(MVI)in hepatocellular carcinoma(HCC)is an important indicator for HCC recurrence and poor prognosis[1].Determining the preoperative MVI status is helpful for guiding clinical treatment and improving prognosis.Currently,MVI diagnosis is achieved primarily by postoperative histopathology,which makes it difficult to provide a definite diagnosis before surgery.However,significant advancements in imaging technology have begun to allow clinicians to make a diagnosis of HCC MVI prior to surgery.In this study,we used contrast-enhanced ultrasound(CEUS)to observe the characteristics of HCC enhancement patterns and quantitatively analyze the changes in HCC blood perfusion parameters to explore the value of CEUS in evaluating HCC MVI.

R-mode instability of strange stars and observations of neutron stars in LMXBs

Using a realistic equation of state （EOS） of strange quark matter, namely, the modified bag model, and considering the constraints on the parameters of EOS by the observational mass limit of neutron stars, we investigate the r-mode instability window of strange stars, and find the same result as in the brief study of Haskell, Degenaar and Ho in 2012 that these instability windows are not consistent with the spin frequency and temperature observations of neutron stars in low mass X-ray binaries.

A possible origin of the Galactic Center magnetar SGR 1745–2900

Since there is a large population of massive O/B stars and putative neutron stars （NSs） located in the vicinity of the Galactic Center （GC）, intermediate-mass X-ray binaries （IMXBs） constituted by an NS and a B-type star probably exist there. We investigate the evolutions of accreting NSs in IMXBs （similar to M82 X-2） with a - 5.2 M companion and orbital period 2.53 d. By adopting a mildly super-Eddington rate M = 6 × 10-8 M yr-1 for the early Case B Roche-lobe overflow （RLOF） accretion, we find that only in accreting NSs with quite elastic crusts （slippage factor s = 0.05） can the toroidal magnetic fields be amplified within 1 Myr, which is assumed to be the longest duration of the RLOF. These IMXBs will evolve into NS＋white dwarf （WD） binaries if they are dynamically stable. However, before the formation of NS＋WD binaries, the high stellar density in the GC will probably lead to frequent encounters between the NS＋evolved star binaries （in post-early Case B mass transfer phase） and NSs or exchange encounters with other stars, which may produce single NSs. These NSs will evolve into magnetars when the amplified poloidal magnetic fields diffuse out to the NS surfaces. Consequently, our results provide a possible expianation for the origin of the GC magnetar SGR 1745-2900. Moreover, the accreting NSs with s 〉 0.05 will evolve into millisecond pulsars （MSPs）. Therefore, our model reveals that the GC magnetars and MSPs could both originate from a special kind of IMXB.

Quark stars with strong magnetic fields: considering different magnetic field geometries

We calculate the mass-radius relationship of quark stars with the magnetized density- dependent quark mass model in this work, considering two magnetic field geometries： a statistically isotropic, tangled field and a force-free configuration. In both cases, magnetic field production decreases in the case of maximum quark star mass. Furthermore, a tangled, isotropic magnetic field has a relatively smaller impact on the mass and radius, compared to the force-free configuration, which implies that the geometry of the interior magnetic field is at least as important as the field strength itself when the influ- ence of the strong magnetic field on the mass and radius is assessed.

Thermal evolution of neutron stars with decaying magnetic fields

Rotochemical heating originates in the deviation from beta equilibrium due to spin-down compression, which is closely related to the dipole magnetic field. We numerically calculate the deviation from chemical equilibrium and thermal evolution of neutron stars with decaying magnetic fields. We find that the power-law long term decay of the magnetic field slightly affects the deviation from chemical equilibrium and surface temperature. However, the magnetic decay leads to older neutron stars that could have a different surface temperature with the same magnetic field strength. That is, older neutron stars with a low magnetic field （10^8 G） could have a lower temper- ature even with rotochemical heating in operation, which probably explains the lack of other observations on older millisecond pulsars with higher surface temperature, except millisecond pulsar J0437-4715.

First-order phase transitions in rotating hybrid stars and pulsar glitches

The first order deconfinement phase transitions in rotating hybrid stars are studied and it is found that if the surface tension is sufficiently large, the transition from metastable hadron matter to stable mixed hadron-quark matter during the spindown history of a hybrid star can cause a glitch.

Recovering the pulse profiles and polarization position angles of some pulsars from interstellar scattering

Interstellar scattering causes broadening and distortion in the mean pulse profiles and polarization position angle （PPA） curves of pulsars, especially pulse profiles observed at lower frequencies. This paper implements a method to recover the pulse profiles and PPA curves of five pulsars which have obvious scattered pulse pro- files at lower frequency. It reports a simulation to show the scattering and descatter- ing of pulse profiles and PPA curves, and as a practical application the lower frequency profiles and PPA curves of PSR 1356-60, PSR 1831-03, PSR 1838＋04, PSR 1859＋03 and PSR 1946＋35 are obtained. It is found that the original pulse profiles and PPA curves can be recovered.

All-optical signal processing for linearity enhancement of Mach–Zehnder modulators

This paper presents the fundamental principles and recent advances in the field of linearity enhancement of Mach–Zehnder modulators in microwave photonic systems using all-optical signal processing.A review of the fundamentals and applications that implement the linearity improvement is also provided.

Effect of intercritical deformation on tensile performance of a low-carbon Si-Mn steel processed by quenching and bainitic partitioning

The effect of intercritical deformation on retained austenite and tensile performance of a low-carbon Si-Mn steel in modified quenching and bainitic partitioning processes was evaluated.The results showed that the intercritical deformation can play a positive role in stabilizing and refining the retained austenite,and possessed promising potential in balancing tensile strength and ductility of multiphase high-strength steels.The experimental low-carbon Si-Mn steel exhibited multiphase configuration comprising polygonal ferrite,granular bainite and granular structure after two different modified quenching and bainitic partitioning processes,and the bainitic ferrite laths got refined by intercritical deformation.The volume fraction of retained austenite in film-like and blocky morphology was increased from 11.5%to 13.9%due to applied intercritical deformation,and the larger amount of retained austenite provided the sufficient transformation-induced plasticity effect and resulted in enhanced work hardening degree;in response,enhanced ultimate tensile strength 1260 MPa and fracture elongation 22.1%were obtained,leading to increased product of strength and elongation in value of 27.7 GPa% compared to 20.8 GPa% of undeformed structure.

Chemical Characteristics Combined with Bioactivity for Comprehensive Evaluation of Tumuxiang Based on HPLC-DAD and Multivariate Statistical Methods

Background: The dried roots of Inula helenium L.(IH) and Inula racemosa Hook f.(IR) are used commonly as folk medicine under the name of "tumuxiang(TMX)". Phenolic acid compounds and their derivatives, as main active constituents in IH and IR, exhibit prominent anti-inflammation effect.Objective: To develop a holistic method based on chemical characteristic and anti-inflammation effect for systematically evaluating the quality of twenty-seven TMX samples(including 18 IH samples and 9 IR samples) from different origins.Methods: HPLC fingerprints data of AL(Aucklandia lappa Decne.) whose dried root was similar with HR was added for classification analysis. The HPLC fingerprints of twenty-seven TMX samples and four AL samples were evaluated using hierarchical clustering analysis(HCA) and principle component analysis(PCA). The spectrum-efficacy model between HPLC fingerprints and anti-inflammatory activities was investigated by principal component regression(PCR) and partial least squares(PLS).Results: All samples were successfully divided into three main clusters and peaks 7, 9, 11, 22, 24 and 26 had a primary contribution to classify these medicinal herbs. The results were in accord with the appraisal results of herbs. The spectrum-efficacy relationship results indicated that citric acid, quinic acid, caffeic acid-β-D-glucopyranoside, chlorogenic acid, caffeic acid, 1,3-O-dicaffeoyl quinic acid, tianshic acid and 3β-Hydroxypterondontic acid had main contribution to anti-inflammatory activities.Conclusion: This comprehensive strategy was successfully used for identification of IH, IR and AL, which provided a reliable and adequate theoretical basis for the bioactivity relevant quality standards and studying the material basis of anti-inflammatory effect of TMX.

Effect of time interval on microstructure evolution of medium carbon steel during warm deformation

The thermal mechanical simulator system (Gleeble-3500) was used to carry out the double passes compression tests. The microstructure evolution of medium carbon steel with different time intervals during warm deformation was investigated by scanning electron microscopy, transmission electron microscopy and electron back-scattered diffraction. The results show that the effects of time interval on microstructure evolution are very important. The low-angle boundaries transform into high-angle boundaries (HABs) during interval. The fraction of HABs and homogeneity of particle carbides increase with increasing time interval. In addition, the homogeneity of carbides also increases with the strain. However, the effects of time interval on the microstructure evolution are negligible when it exceeds 100 s.

Investigation on Prescription Screening of a Polyherbal Preparation Based on Splenocyte Proliferation Activity and its Preparation Method

Objective: The present study aims to optimize the extraction conditions of polysaccharides and flavonoids from a polyherbal preparation consisting of three kinds of Chinese medicinal herbs, Codonopsis pilosula, Crataegus pinnatifida, and Lycium barbarum, and evaluation of its immunomodulatory activity in immunosuppressed mice. Materials and Methods: An orthogonal design(L_9 [3]~4) was constructed to achieve the optimal extraction conditions. The immunomodulatory action of the polyherbal preparation was studied at three doses of 10, 20, and 40 mL/kg/day orally by measuring splenocyte proliferation in mice model of cyclophosphamide-induced immunosuppression. Results: The chosen parameters, including the ratio of solvent-to-raw material, duration of extraction, and extraction times, were the fundamental variables that influenced the extract yields. The highest yield of total polysaccharides content was 54.3 mg/mL when the ratio of solvent-to-raw material,duration of extraction, and number of extractions were 12:1, 1.5 h, and 3, respectively. The maximum extraction yield of the flavonoids was 3.5 mg/mL when the ratio of solvent-to-raw material was 12:1, the extraction time was 2 h, and the number of extractions was 3. The prescription screening showed that the impact of the polyherbal preparation on the splenocyte proliferation capacity was more pronounced than its disassembled components. Oral administration of the polyherbal preparation could significantly increase the concanavalin A-stimulated mouse spleen cells proliferation in a dose-dependent manner. Conclusion: These findings suggested that the polyherbal preparation possesses potential for augmenting the immune activity due to the polysaccharide and flavonoid content in these herbal medicines.

The Effects of Different Compatibilities of Qing'e Formula on Scopolamine-induced Learning and Memory Impairment in the Mouse

Background: The Qing'e formula(QEF) is a well-known traditional Chinese prescription that has been clinically employed for treatment of bone disease for hundreds of years. Objective: The present study aims to observe the effects of different compatibilities of QEF on the scopolamine-induced learning and memory impairment in the mouse, and further to explore its action mechanisms and compatibility rationality.Materials and Methods: The learning and memory alterations in the mouse were evaluated using the step-down test and Morris water maze(MWM) test; the acetylcholinesterase(AChE) activity and brain-derived neurotrophic factor(BDNF) expression in the hippocampus were measured using colorimetric method or immunohistochemistry. Results: The results showed that different compatibilities of QEF significantly prolonged latency in the step-down test, shortened escape latency in the navigation test, increased the percentage of residence time, and the percentage of swimming distance in the target quadrant in the probe trial session. In addition, our results also found that different compatibilities of QEF remarkably inhibited AChE activity and increased BDNF expression in the hippocampus of mice. What's more, the group after being treated with whole recipe(QF) showed the highest level of improvement. Conclusions: These findings not only suggest that QEF may effectively ameliorate cognitive deficits through inhibiting AChE activity and increasing BDNF expression in the hippocampus but also elucidate the rationality of QEF.