Quark-cluster Stars: the structure

The nature of pulsar-like compact stars is still in controversy although the first pulsar was found more than 40 years ago. Generally speaking, conventional neutron stars and non-mainstream quark stars are two types of models to describe the inner structure of pulsars, with the former composed mainly of hadrons and the latter of a peculiar kind of matter whose state equation should be understood in the level of quarks rather than hadrons. To construct a more realistic model from both theoretical and observational points of view, we conjecture that pulsars could be "quark-cluster stars" which are composed of quark-clusters with almost equal numbers of up, down and strange quarks. Clustering quark matter could be the result of strong coupling between quarks inside realistic compact stars. The lightest quark clusters could be of H-dibaryons, while quark clusters could also be heavier with more quarks. Being essentially related to the non-perturbative quantum-chromo dynamics (QCD), the state of supra-nuclear condensed matter is really difficult to obtain strictly by only theoretical QCD-calculations, and we expect, nevertheless, that astrophysical observations could help us to have a final solution.Comment: 10 pages, 2 figures, talk at the 3rd Galileo-XuGuangqi Meeting (11-15 October 2011, Beijing

An Internal Observability Estimate for Stochastic Hyperbolic Equations

This paper is addressed to establishing an internal observability estimate for some linear stochastic hyperbolic equations. The key is to establish a new global Carleman estimate for forward stochastic hyperbolic equations in the $L^2$-space. Different from the deterministic case, a delicate analysis of the adaptedness for some stochastic processes is required in the stochastic setting

Strangeons constitute bulk strong matter-- To test using GW170817

The fundamental strong interaction determines the nature of pulsar-like compact stars which are essentially in the form of bulk strong matter. From an observational point of view, it is proposed that bulk strong matter could be composed of strangeons, i.e. quark-clusters with there-light-flavor symmetry of quarks, and therefore pulsar-like compact objects could actually be strangeon stars. The equation of state (EOS) of strangeon stars is described in a Lennard-Jones model for the purpose of constraining the EOS by both the tidal deformability $\Lambda$ of GW170817 and $M_{\rm TOV}$. It is found that the allowed parameter space is quite large as most of the Lennard-Jones EOS models satisfy the tidal deformability constraint by GW170817. The future GW detections for smaller values of $\Lambda$ and mass measurement for larger values of $M_{\rm TOV}$ will help a better constraint on the strangeon star model.Comment: Accepted by the EPJA Topical Issue "The first Neutron Star Merger Observation - Implications for Nuclear Physics

Convergence of martingale solution to slow-fast systems with jumps modulated by Markovian switching

This paper investigates the convergence of martingale solutions to slow-fast systems with jumps modulated by Markovian switching on weakly irreducible class. The key point here is to deals with slow-fast systems and two-time-scale Markovian switching simultaneously, while averaging on the slow component requires two invariant measures respectively due to the coexistence of the fast component and Markovian switching. We first investigate the slow-fast systems modulated by Markovian chains with single weakly irreducible class, and the existence and uniqueness of the solution will be proved. Then weak convergence is presented based on tightness and the exponential ergodicity of the fast component with the martingale method, where the appropriate perturbed test functions plays a decisive role in processing. Finally we extend results to the case of the multiple irreducible class

Ecologically-framed Mercury Database, Exposure Modeling and Risk/Benefit Communication to Lower Chesapeake Bay Fish Consumers

Mercury concentrations and determinants of mercury accumulation were examined for ten finfish species from the lower Chesapeake Bay and its tributaries. None of the sampled fish had total mercury concentrations approaching the U.S. EPA human health screening value. Mercury concentrations in different fish species generally increased with increasing delta 15N, but not delta 13C, suggesting that trophic position, but not dietary carbon source was a dominant determinant. A methylmercury biomagnification model was built to estimate a food web magnification factor of approximately 10-fold increase per trophic level in Chesapeake Bay. Based on otolith strontium-calcium ratios, Atlantic croaker inhabiting less saline waters might accumulate more mercury than those inhabiting more saline waters. Positive intraspecies relationships between methylmercury concentration and delta 13C were identified for summer flounder, weakfish, American eel, Atlantic croaker, and spot. Fish consumption and associated mercury exposure were explored for two ethnic (Chinese and Vietnamese) church communities along coastal Virginia, as well as two general population (non-Asian) churches in this region. Individual seafood consumption rates for the ethnic communities were higher than the general U.S. fish consumption rate of 12.8 g/person/day. People from the general population churches and Chinese church took in most of their mercury from market fish (distributed and sold nationally) whereas people from the Vietnamese church took in mercury from both the market and local fish as they tended to eat a large amount of diverse local species. Hair mercury concentrations in the Chinese and the Vietnamese church were higher than the overall level for U.S. women (0.20 mug/g), but lower than the published WHO exposure threshold of 14 mug/g. Regression between seafood consumption rates and hair mercury concentrations suggested that dietary mercury ingestion through seafood was positively related to mercury exposure. Mercury exposure of the Vietnamese community was higher compared to the Chinese community, which itself was higher than the general church communities. Regardless, the daily methylmercury intake rates for all studied communities were lower than the U.S. EPA Reference Dose of 0.1 mug/kg BW-day. Keywords: Mercury, methylmercury, trophic ecology, biomagnification, fish, Chesapeake Bay, exposure assessment, seafood consumption, Chinese, Vietnamese

An analysis of stance and voice in research articles across Chinese and British cultures, using the Appraisal Framework

Scholars from Mainland China are increasingly publishing in the medium of English, in order to gain visibility and credibility worldwide. However, the visibility of Chinese scholars in the Social Sciences is strikingly low. Due to the holistic, interpretative, reiterative nature of knowledge in the Social Sciences, writers have to work harder to establish personal credibility through claim-making negotiations, sharing sympathetic understanding and promoting tolerance in their readers (Becher, 1994; Becher & Trowler, 2001; Hyland, 2000). This thesis investigates differences in stance and voice style between scholars from Mainland China and Britain so as to derive new information which might be useful to novice researchers in the Social Sciences (particularly applied linguistics) who intend to publish internationally. A corpus of 30 research articles in applied linguistics was analysed in terms of Appraisal Theory (Martin & White 2005), theory of context (Xu & Nesi, 2017) and genre analysis (Swales 1990, 2004), using the UAM Corpus Tool (O’Donnell 2011). Findings from this analysis suggest that both the Chinese and the British authors are aware of the need to argue for their own opinions and maintain good relationships with their readers, but choose contrasting ways to realize these same purposes. Generally the Chinese authors try to maintain writer-reader relationships by avoiding explicit attitudinal evaluation of the work of others, while the British authors try to maintain writer-reader relationships by toning down or only evoking stance. The Chinese authors argue for their own positions by reinforcing their explicit attitudes, adding multiple references, sharpening the completion of tasks and construing claims as unquestioned, whereas the British authors argue for their own positions by explicitly evaluating people and phenomena. Because the statistically significant differences in stance and voice strategies revealed in this thesis indicate differences between Chinese and British scholars’ argumentative styles, they suggest the need for a new way of perceiving Chinese ethnolinguistic impact on research writing, and might also inform the teaching of academic writing in the social sciences