Strange Matter: a state before black hole

Normal baryonic matter inside an evolved massive star can be intensely compressed by gravity after a supernova. General relativity predicts formation of a black hole if the core material is compressed into a singularity, but the real state of such compressed baryonic matter (CBM) before an event horizon of black hole appears is not yet well understood because of the non-perturbative nature of the fundamental strong interaction. Certainly, the rump left behind after a supernova explosion could manifest as a pulsar if its mass is less than the unknown maximum mass, $M_{\rm max}$. It is conjectured that pulsar-like compact stars are made of strange matter (i.e., with 3-flavour symmetry), where quarks are still localized as in the case of nuclear matter. In principle, different manifestations of pulsar-like objects could be explained in the regime of this conjecture. Besides compact stars, strange matter could also be manifested in the form of cosmic rays and even dark matter.Comment: 20 pages, 3 figures, contribution to "Centennial of general relativity - A celebration

Project-Based Learning: an Effective Approach to Link Teacher Professional Development and Students Learning

Professional development for teachers is a key mechanism for improving classroom instruction and student achievement, yet there is little empirical evidence upon which to damonstrate the connection between teachers’ professional development and students’ achievement. This paper presents a pilot research which adopts project-based teaching and learning(PjBL) as an approch to link teahcer professional development and student learning. In our longitudinal study, a resource-rich school in urban areas and a less developed school in outlying areas join hands to carry out a research project. Study groups were composed of 2-3 teachers and 10-15 students in each school. The groups from different regions then collaboratively carried out a learning project with the support of an online learning community. The data is collected from focus groups and interviews with stakeholders, online surveys and paper-based questionnaires, computer proficiency tests, observations from site visits, and an analysis of the students\u27 artificial product. Research findings show that project-based collaborative inquiry activity provides the greatest support for teachers and students to develop their comprehensive capacity

Singular Trudinger--Moser inequality involving LpL^{p} norm in bounded domain

In this paper, we use the method of blow-up analysis and capacity estimate to derive the singular Trudinger--Moser inequality involving $N$-Finsler--Laplacian and $L^{p}$ norm, precisely, for any $p>1$, $0\leq\gamma<\gamma_{1}:= \inf\limits_{u\in W^{1, N}_{0}(\Omega)\backslash \{0\}}\frac{\int_{\Omega}F^{N}(\nabla u)dx}{\| u\|_p^N}$ and $0\leq\beta<N$, we have \begin{align} \sup_{u\in W_{0}^{1,N}(\Omega),\;\int_{\Omega}F^{N}(\nabla u)dx-\gamma\| u\|_p^N\leq1}\int_{\Omega}\frac{e^{\lambda_{N}(1-\frac{\beta}{N})\lvert u\rvert^{\frac{N}{N-1}}}}{F^{o}(x)^{\beta}}\;\mathrm{d}x<+\infty\notag, \end{align} where $\lambda_{N}=N^{\frac{N}{N-1}} \kappa_{N}^{\frac{1}{N-1}}$ and $\kappa_{N}$ is the volume of a unit Wulff ball in $\mathbb{R}^N$, moreover, extremal functions for the inequality are also obtained. When $F=\lvert\cdot\rvert$ and $p=N$, we can obtain the singular version of Tintarev type inequality by the obove inequality, namely, for any $0\leq\alpha<\alpha_{1}(\Omega):=\inf\limits_{u\in W^{1, N}_{0}(\Omega)\backslash \{0\}}\frac{\int_{\Omega}|\nabla u|^Ndx}{\| u\|_N^N}$ and $0\leq\beta<N$, it holds $$\sup_{u\in W_{0}^{1,N}(\Omega),\;\int_{\Omega}\lvert\nabla u\rvert^{N}\;\mathrm{d}x-\alpha\|u\|_{N}^{N}\leq1}\int_{\Omega}\frac{e^{\alpha_{N}(1-\frac{\beta}{N})\lvert u\rvert^{\frac{N}{N-1}}}}{\lvert x\rvert^{\beta}}\;\mathrm{d}x<+\infty,$$ where $\alpha_{N}:=N^{\frac{N}{N-1}}\omega_{N}^{\frac{1}{N-1}}$ and $\omega_{N}$ is the volume of unit ball in $\mathbb{R}^{N}$. Our results extend many well-known Trudinger--Moser type inequalities to more general setting

Identification of candidate genes involved in wax deposition in Poa pratensis by RNA-seq

A, Randomness test of cDNA fragments; B, Sequencing saturation analysis. T1 and T2 represent NEZm; T3 and T4 represent EBZ. (PDF 290 kb

Contagion processes on the static and activity driven coupling networks

The evolution of network structure and the spreading of epidemic are common coexistent dynamical processes. In most cases, network structure is treated either static or time-varying, supposing the whole network is observed in a same time window. In this paper, we consider the epidemic spreading on a network consisting of both static and time-varying structures. At meanwhile, the time-varying part and the epidemic spreading are supposed to be of the same time scale. We introduce a static and activity driven coupling (SADC) network model to characterize the coupling between static (strong) structure and dynamic (weak) structure. Epidemic thresholds of SIS and SIR model are studied on SADC both analytically and numerically with various coupling strategies, where the strong structure is of homogeneous or heterogeneous degree distribution. Theoretical thresholds obtained from SADC model can both recover and generalize the classical results in static and time-varying networks. It is demonstrated that weak structures can make the epidemics break out much more easily in homogeneous coupling but harder in heterogeneous coupling when keeping same average degree in SADC networks. Furthermore, we show there exists a threshold ratio of the weak structure to have substantive effects on the breakout of the epidemics. This promotes our understanding of why epidemics can still break out in some social networks even we restrict the flow of the population

An Ultra Low Mass and Small Radius Compact Object in 4U 1746-37?

Photospheric radius expansion (PRE) bursts have already been used to constrain the masses and radii of neutron stars. RXTE observed three PRE bursts in 4U 1746-37, all with low touchdown fluxes. We discuss here the possibility of low mass neutron star in 4U 1746-37 because the Eddington luminosity depends on stellar mass. With typical values of hydrogen mass fraction and color correction factor, a Monte-Carlo simulation was applied to constrain the mass and radius of neutron star in 4U 1746-37. 4U 1746-37 has a high inclination angle. Two geometric effects, the reflection of the far side accretion disc and the obscuration of the near side accretion disc have also been included in the mass and radius constraints of 4U 1746-37. If the reflection of the far side accretion disc is accounted, a low mass compact object (mass of $0.41\pm0.14~M_{\odot}$ and radius of $8.73\pm1.54~\rm km$ at 68% confidence) exists in 4U 1746-37. If another effect operated, 4U 1746-37 may contain an ultra low mass and small radius object ($M=0.21\pm0.06~M_{\odot},~R=6.26\pm0.99~\rm km$ at 68% confidence). Combined all possibilities, the mass of 4U 1746-37 is $0.41^{+0.70}_{-0.30}~M_\odot$ at 99.7% confidence. For such low mass NS, it could be reproduced by a self-bound compact star, i.e., quark star or quark-cluster star.Comment: accepted by Ap

Poinsettia and Easter Lily Growth and Development Responses to Root Substrate Containing Biochar

Greenhouse production of Poinsettia (Euphorbia pulcherrima) and Easter lily (Lilium longiflorum) mainly uses peat-based root substrates. The decrease of peatland has increased the need for alternative root substrate components in the horticulture industry. Biochar, a byproduct of bio-energy production, has the potential to be an alternative root substrate component to reduce the use of peatmoss in greenhouse production. The objectives of the present studies were to determine the effects of different percentages of biochar and fertigation regimes on the growth and development of ‘Prestige Red’ poinsettia and Easter lily ‘Nellie White’ in greenhouse production. Two experiments were conducted to evaluate different percentages of one type of biochar added to a commercial peat-based root substrate for poinsettia and Easter lily greenhouse production. In experiment one, rooted poinsettia cuttings were potted in one of the six root substrates mixes including Sunshine Mix #1 replaced by 0%, 20%, 40%, 60%, 80%, or 100% biochar (by volume) and irrigated under four fertigation regimes (100 to 200 mg•L-1 N, 200 to 300 mg•L^-1 N, 300 to 400 mg•L^-1 N, or 400 to 500 mg•L^-1 N). Root rot and red bract necrosis were only observed in the highest fertigation regime (400-500 mg•L^-1 N) combined with the highest biochar percentage (100%). At 100 to 400 mg•L^-1 N fertilization rate, up to 80% of the commercial peat-based root substrate could be replaced by biochar without a significant change in poinsettia growth and quality. In experiment two, Easter lily bulbs were potted in one of the five root substrates mixes (Sunshine Mix #1 amended with 0%, 20%, 40%, 60%, and 80% biochar) and irrigated under four fertigation regimes (constant liquid feed at 200 mg•L^-1 N or 300 mg•L^-1 N, and fertilization at every third watering with 200 mg•L^-1 N or 300 mg•L^-1 N). Neither fertigation regimes nor biochar percentages significantly affected the Easter lily growth and development. Under the four fertigation regimes used in this experiment, up to 80% peat-based root substrate could be replaced by biochar without a significant difference on the growth and development of Easter lily

Does a higher minimum wage accelerate labour division in agricultural production? Evidence from the main riceplanting area in China

Agricultural production outsourcing, a new means of agricultural production, can optimise the allocation of resources, reduce agricultural production costs, and improve agricultural productivity. However, farmers’ outsourcing behaviours are strongly interfered with by many factors such as economics, technology and institutions. Using a farmer-level data set from 2014 to 2018 in China, we examine the effects of the minimum wage increase on rice farmers’ production outsourcing behaviours. Our study relies on a Logit regression framework and uses the control function (C.F.) approach to address potential endogeneity concerns. Results show that the minimum wage increase significantly reduces the probability of farmers conducting production outsourcing. We also examine the heterogeneous effects of the minimum wage increase, and find that compared with other outsourcing services, the adverse effects on harvesting outsourcing are the strongest; the negative effects on production outsourcing are stronger for rice farmers with higher education. Our results provide new insights into understanding how labour regulation affects labour division in agricultural production