R-process nucleosynthesis during explosion of low-mass neutron stars in close binaries

We investigate the explosion of low-mass neutron stars through Newtonian hydrodynamic simulations. We couple the hydrodynamics to a nuclear reaction network consisting of $\sim 4500$ isotopes to study the impact of nuclear reactions, mainly neutron capture, $\beta$-decays, and spontaneous fission of nuclei, on the development of hydrodynamic instability of a neutron star. We show that after mass removal from the surfaces, low-mass neutron stars undergo delayed explosion, and an electron anti-neutrino burst with a peak luminosity of $\sim3\times10^{50}$ erg s$^{-1}$ is emitted, while the ejecta is heated to $\sim10^{9}$ K. A robust r-process nucleosynthesis is realized in the ejecta. Lanthanides and heavy elements near the second and third r-process peaks are synthesized as end products of nucleosynthesis, suggesting that the explosions of low-mass neutron stars could be a potentially important source of solar chemical elements.Comment: 12 pages, 13 figure

Accretion-induced Collapse of Dark Matter-admixed Rotating White Dwarfs: Dynamics and Gravitational-wave Signals

We present two-dimensional hydrodynamic simulations of the accretion-induced collapse (AIC) of rotating white dwarfs admixed with an extended component of dark matter (DM) comprising of sub-GeV degenerate fermionic DM particles. We find that the DM component would follow the collapse of the normal matter (NM) component to become a bound DM core. Thus, we demonstrate how a DM-admixed neutron star could form through DM-admixed AIC (DMAIC) for the first time, with the dynamics of DM taken into account. The gravitational-wave (GW) signature from the DMAIC shows distinctive features. In the diffusive DM limit, the DM admixture indirectly suppresses the post-bounce spectral peak of the NM GWs. In the compact DM limit, the collapse dynamics of the DM in a Milky Way event generate GWs that are strong enough to be detectable by Advanced LIGO as continuous low-frequency ($< 1000$ Hz) signals after the NM core bounce. Our study not only is the first-ever computation of GW from a collapsing DM object but also provides the key features to identify DM in AIC events through future GW detections.Comment: 14 pages, 13 figure

Comparing the effects of visibility of different neighborhood greenery settings on the preference ratings and noise annoyance responses to road traffic noises

The impact of visual environment on human noise perceptions has always been under scrutiny. Two consecutive sets of laboratory experiments were performed for studying the effect of visual perceptions of different percentages of sea, greenery, and/or road views on noise-induced annoyance responses as well as preference ratings. Both experiments were carried out in a room purposely constructed inside an anechoic chamber to mimic the living room setting of a dwelling in Hong Kong. Video clips were projected consecutively onto the exterior window panel of the living room to simulate neighborhood views containing different percentages of sea, greenery and road. 82 and 58 participants were successfully administered in two experiments. Each participant was presented with 11 video clips and requested to respond to a series of questions regarding perceived noise annoyance and view preferences after presentation of individual clips. The responses collected from each experiment were employed to formulate ordered logit models to predict the probability of evoking a high annoyance response. Findings indicated that participants tended to prefer the presence of sea rather than that of either mountain or trees in views containing a trafficking road. Views containing sea would produce an attenuating effect on noise annoyance while views containing road would produce an aggravating effect. However, the size of the effects did not vary between 0% and 30% sea, or between 30% and 60% road contained in a view. Views containing dense greenery at a close distance would aggravate noise annoyance irrespective of form. However, when the percentage of greenery increased from 30% to 60%, the noise annoyance attenuating effect increased in the case of wooded mountain but decreased in the case of the more transparent tree clumps

A low frequency mechanical transmitter based on magnetoelectric heterostructures operated at their resonance frequency

Magneto-elasto-electric (ME) coupling heterostructures, consisting of piezoelectric layers bonded to magnetostrictive ones, provide for a new class of electromagnetic emitter materials on which a portable (area ~ 16 cm 2 ) very low frequency (VLF) transmitter technology could be developed. The proposed ME transmitter functions as follows: (a) a piezoelectric layer is first driven by alternating current AC electric voltage at its electromechanical resonance (EMR) frequency, (b) subsequently, this EMR excites the magnetostrictive layers, giving rise to magnetization change, (c) in turn, the magnetization oscillations result in oscillating magnetic fields. By Maxwell’s equations, a corresponding electric field, is also generated, leading to electromagnetic field propagation. Our hybrid piezoelectric-magnetostrictive transformer can take an input electric voltage that may include modulation-signal over a carrier frequency and transmit via oscillating magnetic field or flux change. The prototype measurements reveal a magnetic dipole like near field, demonstrating its transmission capabilities. Furthermore, the developed prototype showed a 10 4 times higher efficiency over a small-circular loop of the same area, exhibiting its superiority over the class of traditional small antennas

The Ethanol Extract of Fructus trichosanthis Promotes Fetal Hemoglobin Production via p38 MAPK Activation and ERK Inactivation in K562 Cells

Pharmacological stimulation of fetal hemoglobin (HbF) expression may be a promising approach for the treatment of beta-thalassemia. In this study, the effects of Fructus trichosanthis (FT) were investigated in human erythroleukemic K562 cells for their gamma-globin mRNA and HbF-induction activities. The role of signaling pathways, including extracellular regulated protein kinase (ERK) and p38 mitogen-activated protein kinase (MAPK), was also investigated. It was found that the ethanol extract of FT significantly increased gamma-globin mRNA and HbF levels, determined by real-time reverse transcription polymerase chain reaction and enzyme linked immunosorbent assay, respectively, in dose- and time-dependent manner. Total Hb (THb) levels were also elevated in the concentrations without cytotoxicity (<80 μg mL−1). Pre-treatment with p38 MAPK inhibitor SB203580 blocked the stimulatory effects of FT extract in total and HbF induction. In contrast, no change in HbF was observed when treated with ERK inhibitor PD98059. Furthermore, FT ethanol extract activated p38 MAPK and inhibited ERK signaling pathways in K562 cells, as revealed in western blotting analysis. In addition, SB203580 significantly abolished p38 MAPK activation when the cells were treated with FT. In summary, the ethanol extract of FT was found to be a potent inducer of HbF synthesis in K562 cells. The present data delineated the role of ERK and p38 MAPK signaling as molecular targets for pharmacologic stimulation of HbF production upon FT treatment

此時彼刻文化研究 = Cultural studies still in the making

時光荏苒，MCS15年了！ 今年MCS年度研討會與過去有點不同，主題是「展演CROSSOVER：香港文化研究的變奏與另類新選擇」。在舉步維艱的社會政治泥沼中，我們如何理解和面對這境地？透過這次研討會，MCS表達對這個時代的關切，並在這關口中提出新概念，加入「表演研究」元素──不但帶來學術上的協同效應，而且使未來教育的路更闊、與大家走得更遠，發揮更大的潛質。 研討會分為兩部分。第一部分以MCSian的論文為引旨，透過對話去思考在當前處境如何尋找出路，由梁旭明主持，分別由吳紹奇主講〈作為歷史哲學家的班雅明：論歷史哲學兼評〈歷史哲學論綱〉〉，Kong Yee主講〈The Identity of Cheung Chau Kai-fong : The Cultural Disparity of The Northern and Southern Cheung Chau〉，古卓嵐主講〈Modern Educayshun 的啟示──從恐懼女性主義心理 到課室政治的省思〉，並由羅冠聰評論及與講者進行討論

Genome maps across 26 human populations reveal population-specific patterns of structural variation.

Large structural variants (SVs) in the human genome are difficult to detect and study by conventional sequencing technologies. With long-range genome analysis platforms, such as optical mapping, one can identify large SVs (&gt;2 kb) across the genome in one experiment. Analyzing optical genome maps of 154 individuals from the 26 populations sequenced in the 1000 Genomes Project, we find that phylogenetic population patterns of large SVs are similar to those of single nucleotide variations in 86% of the human genome, while ~2% of the genome has high structural complexity. We are able to characterize SVs in many intractable regions of the genome, including segmental duplications and subtelomeric, pericentromeric, and acrocentric areas. In addition, we discover ~60 Mb of non-redundant genome content missing in the reference genome sequence assembly. Our results highlight the need for a comprehensive set of alternate haplotypes from different populations to represent SV patterns in the genome