Patterns and drivers of avian taxonomic and phylogenetic beta diversity in China vary across geographical backgrounds and dispersal abilities

Geographical background and dispersal ability may strongly influence assemblage dissimilarity;however,these aspects have generally been overlooked in previous large-scale beta diversity studies.Here,we examined whether the patterns and drivers of taxonomic beta diversity(TBD)and phylogenetic beta diversity(PBD)of breeding birds in China vary across(1)regions on both sides of the Hu Line,which demarcates China’s topographical,climatic,economic,and social patterns,and(2)species with different dispersal ability.TBD and PBD were calculated and partitioned into turnover and nestedness components using a moving window approach.Variables representing climate,habitat heterogeneity,and habitat quality were employed to evaluate the effects of environmental filtering.Spatial distance was considered to assess the impact of dispersal limitation.Variance partitioning analysis was applied to assess the relative roles of these variables.In general,the values of TBD and PBD were high in mountainous areas and were largely determined by environmental filtering.However,different dominant environmental filters on either side of the Hu Line led to divergent beta diversity patterns.Specifically,climate-driven species turnover and habitat heterogeneity-related species nestedness dominated the regions east and west of the line,respectively.Additionally,bird species with stronger dispersal ability were more susceptible to environmental filtering,resulting in more homogeneous assemblages.Our results indicated that regions with distinctive geographical backgrounds may present different ecological factors that lead to divergent assemblage dissimilarity patterns,and dispersal ability determines the response of assemblages to these ecological factors.Identifying a single universal explanation for the observed pattern without considering these aspects may lead to simplistic or incomplete conclusions.Consequently,a comprehensive understanding of large-scale beta diversity patterns and effective planning of conservation strategies necessitate the consideration of both geographical background and species dispersal ability.

Design of a high-dynamic-range prototype readout system for VLAST calorimeter

In the future, the Very Large Area gamma-ray Space Telescope is expected to observe high-energy electrons and gamma rays in the MeV to TeV range with unprecedented acceptance. As part of the detector suite, a high-energy imaging calorimeter(HEIC) is currently being developed as a homogeneous calorimeter that utilizes long bismuth germanate(BGO) scintillation crystals as both absorbers and detectors. To accurately measure the energy deposition in the BGO bar of HEIC, a highdynamic-range readout method using a silicon photomultiplier(SiPM) and multiphotodiode(PD) with different active areas has been proposed. A prototype readout system that adopts multichannel charge measurement ASICs was also developed to read out the combined system of SiPMs and PDs. Preliminary tests confirmed the feasibility of the readout scheme, which is expected to have a dynamic range close to 10~6.

Construction and Validation of a Geometry-based Mathematical Model for the Hard X-Ray Imager

Quantitative and analytical analysis of the modulation process of the collimator is a great challenge,and is also of great value to the design and development of Fourier transform imaging telescopes.The Hard X-ray Imager(HXI),as one of the three payloads onboard the Advanced Space-based Solar Observatory(ASO-S) mission,adopts modulating Fourier-Transformation imaging technique and will be used to explore the mechanism of energy release and transmission in solar flare activities.As an important step to reconstruct the images of solar flares,accurate modulation functions of HXI are needed.In this paper,a mathematical model is developed to analyze the modulation function under a simplified condition first.Then its behavior under six degrees of freedom is calculated after adding the rotation matrix and translation change to the model.In addition,unparalleled light and extended sources are also considered so that our model can be used to analyze the X-ray beam experiment.Next,applied to the practical HXI conditions,the model has been confirmed not only by Geant4 simulations but also by some verification experiments.Furthermore,how this model helps to improve the image reconstruction process after the launch of ASO-S is also presented.

Assessment of first-order-moment-based sample reconstruction method for design flood estimation in changing environment

Estimating the design flood under nonstationary conditions is challenging. In this study, a sample reconstruction approach was developed to transform a nonstationary series into a stationary one in a future time window (FTW). In this approach, the first-order moment (EFTW) of an extreme flood series in the FTW was used, and two possible methods of estimating EFTW values in terms of point values and confidence intervals were developed. Three schemes were proposed to analyze the uncertainty of design flood estimation in terms of sample representativeness, uncertainty from EFTW estimation, and both factors, respectively. To investigate the performance of the sample reconstruction approach, synthesis experiments were designed based on the annual peak series of the Little Sugar Creek in the United States. The results showed that the sample reconstruction approach performed well when the high-order moment of the series did not change significantly in the specified FTW. Otherwise, its performance deteriorated. In addition, the uncertainty of design flood estimation caused by sample representativeness was greater than that caused by EFTW estimation.

An Implementation of Galactic White Dwarf Binary Data Analysis for MLDC-3.1

The space-borne gravitational wave detectors will observe a large population of double white dwarf binaries in the Milky Way.However,the search for double white dwarfs in the gravitational wave data will be time-consuming due to the large number of templates involved and antenna response calculation.In this paper,we implement an iterative combinatorial algorithm to search for double white dwarfs in MLDC-3.1 data.To quickly determine the rough parameters of the target sources,the following algorithms are adopted in a coarse search process:(1)using the downsampling method to reduce the number of original data points;(2)using the undersampling method to speed up the generation of a single waveform template;(3)using the stochastic template bank method to quickly construct the waveform template bank while achieving high coverage of the parameter space;(4)combining the FFT acceleration algorithm with the stochastic template bank to reduce the calculation time of a single template.A fine search process is applied to further determine the parameters of the signals based on the coarse search,for which we adopt the particle swarm optimization.Finally,we detect O(10^(4))double white dwarf signals,validating the feasibility of our method.

Hard X-ray Imager (HXI) onboard the ASO-S mission

Hard X-ray Imager(HXI)is one of the three scientific instruments onboard the Advanced Spacebased Solar Observatory(ASO-S)mission,which is proposed for the 25th solar maximum by the Chinese solar community.HXI is designed to investigate the non-thermal high-energy electrons accelerated in solar flares by providing images of solar flaring regions in the energy range from 30 keV to 200 keV.The imaging principle of HXI is based on spatially modulated Fourier synthesis and utilizes about 91 sets of bi-grid sub-collimators and corresponding LaBr3 detectors to obtain Fourier components with a spatial resolution of about 3 arcsec and a time resolution better than 0.5 s.An engineering prototype has been developed and tested to verify the feasibility of design.In this paper,we present background,instrument design and the development and test status of the prototype.

A new record of the capped langur (Trachypithecus pileatus) in China

DEAR EDITOR, The distribution of the capped langur （Trachypithecus pileatus） in China has become controversial since Shortridge＇s langur （Trachypithecus shortridgei） was upgraded to a full species. The capped langur is considered to be distributed in northeast India, Bangladesh, Bhutan, and northwest Myanmar only （Brandon-Jones et al., 2004; Choudhury, 2008, 2014; Das et al., 2008; Groves, 2001）. In our field survey, however, we obtained photos of the capped langur, demonstrating its existence in China. Following the species promotion of Shortridge＇s langur （Brandon-Jones et al., 2004; Groves, 2001） and the delimiting of its distribution range to northwestern Yunnan in China and northeastern Myanmar （Brandon-Jones et al., 2004; Cui et al.,

Spectrometer of hard X-ray imager payload onboard the ASO-S mission

A spaceborne hard X-ray spectrometer, composed of an array of 99 scintillation detectors and associated readout electronics, has been developed for the hard X-ray imager(HXI). The HXI is one of the three payloads onboard the advanced space-based solar observatory(ASO-S), which is scheduled to be launched in early 2022 as the first Chinese solar satellite. LaBr3 scintillators and photomultiplier tubes with a super bialkali cathode are used to achieve an energy resolution better than 20% at 30 keV.Further, a new multi-channel charge-sensitive readout application-specific integrated circuit guarantees high-frequency data acquisition with low power consumption. This paper presents a detailed design of the spectrometer for the engineering model of the HXI and discusses its noise and linearity performance.

Research on the On-orbit Background of the Hard X-Ray Imager Onboard ASO-S

The space environment background of various particle fluxes of the Hard X-ray Imager(HXI), one of the payloads of the Advanced Space-based Solar Observatory(ASO-S) spacecraft, is investigated and presented. Different approaches are used to obtain the input information on various space environment particles(protons, alpha particles, electrons, positrons, neutrons, and photons). Some special regions(SAA and radiation belt) are also taken into account. The findings indicate that electrons are the primary background source in the radiation belt. Due to the large background flux generated by electrons, HXI cannot effectively observe solar flares in the radiation belt.Outside the radiation belt, primary protons and albedo photons are the main sources of background at low and high magnetic latitudes respectively. The statistical analysis of the flare and background spectra shows that the errors of the flare energy spectrum observation are mainly concentrated in the high energy band, and the detector still has a certain spectrum observation capability for flares of C-class and below in the low energy band of the non-radiation belt. The imaging observation of flares of C-class and below is significantly affected by the accuracy of background subtraction. The energy band with the best signal-to-noise ratio is from 10 to 50 ke V, which can be used to monitor the formation and class of flares.

Design and verification of the HXI collimator on the ASO-S mission

A space-borne hard X-ray collimator,comprising 91 pairs of grids,has been developed for the Hard X-ray Imager(HXI).The HXI is one of the three scientific instruments onboard the first Chinese solar mission:the Advanced Space-based Solar Observatory(ASO-S).The HXI collimator(HXI-C)is a spatial modulation X-ray telescope designed to observe hard X-rays emitted by energetic electrons in solar flares.This paper presents the detailed design of the HXI-C for the qualification model that will be inherited by the flight model.Series tests on the HXI-C qualification model are reported to verify the ability of the HXI-C to survive the launch and to operate normally in on-orbit environments.Furthermore,results of the X-ray beam test for the HXI-C are presented to indirectly identify the working performance of the HXI-C.

Characterization of silicon microstrip sensors for space astronomy

Silicon microstrip detectors are widely used in experiments for space astronomy.Before the detector is assembled,extensive characterization of the silicon microstrip sensors is indispensable and challenging.This work electrically evaluates a series of sensor parameters,including the depletion voltage,bias resistance,metal strip resistance,total leakage current,strip leakage current,coupling capacitance,and interstrip capacitance.Two methods are used to accurately measure the strip leakage current,and the test results match each other well.In measuring the coupling capacitance,we extract the correct value based on a SPICE model and two-port network analysis.In addition,the expression of the measured bias resistance is deduced based on the SPICE model.

Following up the afterglow:strategy for X-ray observation triggered by gravitational wave events

The multi-messenger observation of coalescing compact binary systems promises great scientific treasure.However,synthesising observations from both gravitational wave and electromagnetic channels remains challenging.In the context of the day-to-week long emission from a macronova,the binary neutron star merger GW170817 remains the only event with successful electromagnetic followup.In this manuscript,we explore the possibility of using the early stage X-ray afterglow to search for the electromagnetic counterpart of a gravitational wave event.Two algorithms,the simple and straightforward sequential observation(SO)and the step-wise optimizing local optimization are considered and applied to some simulated events.We consider the WXT from the proposed Einstein Probe as a candidate X-ray telescope,which has a very wide field of view of 3600 deg^(2).Benefiting from the large field of view and high sensitivity,we find that the SO algorithm not only is easy to implement,but also promises a good chance of actual detection.

Near real-time gravitational wave data analysis of the massive black hole binary with TianQin

Space-borne gravitational wave(GW)detectors can detect the merger of massive black holes.The early warning and localization of GW events before merging can be used to inform electromagnetic telescopes and conduct multimessenger observations.However,this requires real-time data transmission and analysis capabilities.The geocentric orbit of the space-borne GW detector Tian Qin makes it possible to conduct real-time data transmission.In this study,we develop a search and localization pipeline for massive black hole binaries(MBHBs)with Tian Qin under both regular and real-time data transmission modes.We demonstrate that,with real-time data transmission,MBHBs can be accurately localized on the fly.With the approaching merger,each analysis can be finished in only 40 min.For an MBHB system at a distance of 1 Gpc,if we receive data every hour,then we can pinpoint its location to within less than 1 deg^(2)on the final day before the merger.

Detection of astrophysical gravitational wave sources by TianQin and LISA

TianQin and LISA are space-based laser interferometer gravitational wave(GW)detectors planned to be launched in the mid-2030s.Both detectors will detect low-frequency GWs around 10^(-2)Hz;however,Tian Qin is more sensitive to frequencies above this common sweet-spot while LISA is more sensitive to frequencies below 10^(-2)Hz.Therefore,Tian Qin and LISA will be able to detect the same sources but with different accuracy depending on the source and its parameters.We consider some of the most important astrophysical sources—massive black hole binaries,stellar-mass black hole binaries,double white dwarfs,extreme mass ratio inspirals,light and heavy intermediate mass ratio inspirals,as well as the stochastic gravitational background of astrophysical origin—that Tian Qin and LISA will be able to detect.For each of these sources,we analyze how far they can be detected(detection distance)and how well their parameters can be measured(detection accuracy)using a Fisher Matrix analysis.We compare the results obtained by the three detection scenarios(Tian Qin alone,LISA alone,and joint detection by LISA and Tian Qin)highlighting the gains from joint detection as well as the contribution of Tian Qin and LISA to a combined study of astrophysical sources.In particular,we consider the different orientations,lifetimes,and duty cycles of the two detectors to explore how they can give a more complete picture when working together.

Constraining the Hubble constant to a precision of about 1% using multi-band dark standard siren detections

Gravitational wave signal from the inspiral of stellar-mass binary black hole can be used as standard sirens to perform cosmological inference.This inspiral covers a wide range of frequency bands,from the millihertz band to the audio-band,allowing for detections by both space-borne and ground-based gravitational wave detectors.In this work,we conduct a comprehensive study on the ability to constrain the Hubble constant using the dark standard sirens,or gravitational wave events that lack electromagnetic counterparts.To acquire the redshift information,we weight the galaxies within the localization error box with photometric information from several bands and use them as a proxy for the binary black hole redshift.We discover that Tian Qin is expected to constrain the Hubble constant to a precision of roughly 30%through detections of 10 gravitational wave events;in the most optimistic case,the Hubble constant can be constrained to a precision of<10%,assuming Tian Qin I+II.In the optimistic case,the multi-detector network of Tian Qin and LISA is capable of constraining the Hubble constant to within 5%precision.It is worth highlighting that the multi-band network of Tian Qin and Einstein Telescope is capable of constraining the Hubble constant to a precision of about 1%.We conclude that inferring the Hubble constant without bias from photo-z galaxy catalog is achievable,and we also demonstrate self-consistency using the P-P plot.On the other hand,high-quality spectroscopic redshift information is crucial for improving the estimation precision of Hubble constant.