Tentacular nature of the ‘column’ of the Cambrian diploblastic Xianguangia sinica

Unveiling the body architectures of Cambrian problematic fossils would provide novel insights into the radiation of metazoan body plans during the ‘Cambrian Explosion’ and the ancestral traits of major living animal clades. Xianguangia sinica, from the celebrated Chengjiang biota (518Ma), is a typical Cambrian problematicum with disputable body architecture, particularly about its ‘column’ part. The contradictory interpretations of the ‘column’ of X. sinica have led to at least three hypotheses regarding its affinity in the diploblastic clade. Here we depict the detailed anatomy of the ‘column’ based on new, exquisitely preserved material. The ‘column’ of X. sinica is formed by 18 longsword-shaped tentacle-sheath complexes that can either close or be in a flowering state. There is no partitioned cavity internally when the ‘column’ is closed, invalidating the homology with the true column of living sea anemones. Each tentacle tapers distally and includes a distal flexible portion at about one-fourth the length of the tentacle. The proximal portion is stiff, bearing a set of paired dark stains, and is enveloped by a single outer sheath. Pinnules carrying a row of large cilia are fringed on both sides along the whole length of the tentacles. The body plan of X. sinica is accordingly revised as consisting of a calyx and 18 unique tentacle-sheath complexes that radially surround the mouth. Our result corroborates previous observations that suggest a close relationship between Xianguangia, Daihua and Dinomischus, all of which are here formally assigned to the family Dinomischidae, a monophyletic clade recovered in our phylogenetic analyses. Xianguangia sinica likely employs cilia-bearing pinnate tentacles for sieving particle matter down to 21 mm, indicating that its nutrition source is suspended micro-planktonic organisms or other organic matter in the bottom water

CO observations of major merger pairs at z=0: Molecular gas mass and star formation

We present CO observations of 78 spiral galaxies in local merger pairs. These galaxies representa subsample of a Ks-band selected sample consisting of 88 close major-merger pairs (HKPAIRs), 44 spiral-spiral (S+S) pairs and 44 spiral-elliptical (S+E) pairs, with separation $<20 h^{-1}$ kpc and mass ratio <2.5. For all objects, the star formation rate (SFR) and dust mass were derived from HERSCHEL PACS and SPIRE data, and the atomic gas mass, MHI, from the Green Bank Telescope HI observations. The complete data set allows us to study the relation between the gas (atomic and molecular) mass, dust mass and SFR in merger galaxies. We derive the molecular gas fraction (MH2/M*), molecular-to-atomic gas mass ratio (MH2/MHI), gas-to-dust mass ratio and SFE (=SFR/MH2) and study their dependences on pair type (S+S compared to S+E), stellar mass and the presence of morphological interaction signs. We find an overall moderate enhancements (~2x) in both molecular gas fraction (MH2/M*), and molecular-to-atomic gas ratio (MH2/MHI) for star-forming galaxies in major-merger pairs compared to non-interacting comparison samples, whereas no enhancement was found for the SFE nor for the total gas mass fraction (MHI+MH2)/M*. When divided into S+S and S+E, low mass and high mass, and with and without interaction signs, there is a small difference in SFE, moderate difference in MH2/M*, and strong differences in MH2/MHI between subsamples. For MH2/MHI, the difference between S+S and S+E subsamples is 0.69+-0.16 dex and between pairs with and without interaction signs is 0.53+-0.18 dex. Together, our results suggest (1) star formation enhancement in close major-merger pairs occurs mainly in S+S pairs after the first close encounter (indicated by interaction signs) because the HI gas is compressed into star-forming molecular gas by the tidal torque; (2) this effect is much weakened in the S+E pairs.Comment: Accepted in A&A, 19 page

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

Detection of the Diffuse Supernova Neutrino Background with JUNO

As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

Renovation Construction Process Scheduling for Long-Term Performance of Buildings: An Application Case of University Campus

Renovation construction is employed for maintaining the long-term performance of buildings. For the occupants, the building users, renovation contributes to the acceptable levels of convenience and quality of the buildings. However, if the operation continues during the renovation for an area containing several buildings, such as a university campus, the impacts on the occupants are unavoidable. The complicated schedule plan is needed due to the various types of buildings and types of renovation under limited resources. The goal of this study is to build a model that can help the planners to make the renovation schedule plan. Taking a university campus as an example, the occupants&rsquo; convenience rate and the long-term quality of the building are analyzed in this paper. Based on the key attributes of building renovation, this study proposes a model integrating the genetic algorithm and simulation to provide the optimal schedule plan to the planners. The model is demonstrated by an application case of a university campus of 11 buildings remaining in operation. It helps the university maintain a good level of long-term performance of buildings