Traveling waves in lattice differential equations with distributed maturation delay

In this paper we derive a lattice model with infinite distributed delay to describe the growth of a single-species population in a 2D patchy environment with infinite number of patches connected locally by diffusion and global interaction. We consider the existence of traveling wave solutions when the birth rate is large enough that each patch can sustain a positive equilibrium. When the birth function is monotone, we prove that there exists a traveling wave solution connecting two equilibria with wave speed $c>c^*(\theta)$ by using the monotone iterative method and super and subsolution technique, where $\theta\in [0,2\pi]$ is any fixed direction of propagation. When the birth function is non-monotone, we prove the existence of non-trivial traveling wave solutions by constructing two auxiliary systems satisfying quasi-monotonicity

Impact parameters in an entrepreneurial career determination model from cognition and social network perspectives

The background to this study relates to the policy of the Chinese government to encourage university graduates to become entrepreneurs as a means of addressing unemployment in China. Far less than the expected number of university graduates however engage in an entrepreneurial career which leads one to question the effectiveness of this policy initiative. A number of critical issues arise. First, although the government’s policy incentives may have a positive impact on the take-up of entrepreneurial careers, there is insufficient research to justify the kind of support currently being implemented by the Chinese government. Second, while some studies have shown that one’s social network is a significant attribute in the decision to become an entrepreneur, the empirical evidence is mixed. Other studies have shown that entrepreneurial cognition is a crucial antecedent to whether people choose to become entrepreneurs. Few studies however have examined the relationship between one’s social network and cognition, and their relationship to how entrepreneurial intentions are formed. In addressing these gaps, the thesis investigates how the characteristics of an individual’s social network affect the formation of his or her entrepreneurial intentions directly and via entrepreneurial cognition. The findings of this study contribute to the literature in three respects. The first contribution comes from the argument that one’s social network properties and in particular, one’s entrepreneurial social network, directly influence cognition during the formation of entrepreneurial intentions. The second contribution reveals alternative measures and hence explanations of entrepreneurship in relation to one’s social capital, one’s social network characteristics and other factors. The third contribution rests on the analytical approach, which uses the technics of structural equation modeling (SEM) to reveal the relationship between critical realism and conceptions. As the analysis show, SEM is an appropriate and effective approach to the confirmatory analysis. Essentially, it enables integrating knowledge and by drawing together parameter variables and latent variables, it offers concurrent understanding of the critical insight of the focal problem of why some people choose to be entrepreneurs

Potential of Constraining Propagation Parameters of Galactic Cosmic Rays with the High Energy cosmic-Radiation Detection facility onboard China's Space Station

Precise measurements of the spectra of secondary and primary cosmic rays are crucial for understanding the origin and propagation of those energetic particles. The High Energy cosmic-Radiation Detection (HERD) facility onboard China`s Space Station, which is expected to operate in 2027, will push the direct measurements of cosmic ray fluxes precisely up to PeV energies. In this work, we investigate the potential of HERD on studying the propagation of cosmic rays using the measurements of boron, carbon, and oxygen spectra. We find that, compared with the current results, the new HERD measurements can improve the accuracy of the propagation parameters by 8\% to 40\%. The constraints on the injection spectra at high energies will also be improved.Comment: 10 pages, 4 figure

Triple-product asymmetry in the radiative two-pion tau decay

In this work, we perform a detailed study of the $\tau^-\to\pi^-\pi^0\gamma\nu$ decay process within the resonance chiral theory. We pay special attention to the triple-product asymmetry in the $\tau^-\to\pi^-\pi^0\gamma\nu$ process. The minimal resonance chiral Lagrangian and the odd-intrinsic parity resonance operators are simultaneously included to calculate the decay amplitudes. Various invariant-mass distributions in the $\pi^-\pi^0$, $\pi^-\gamma$ and $\pi^0\gamma$ systems are studied and they reveal different resonance dynamics. We further predict the intriguing nonzero triple-product asymmetry distributions, which may provide useful guidelines for future experimental measurements conducted at the Belle-II and super tau-charm facilities.Comment: 32 pages, 9 figures. To match the published versio

High-responsivity vertical-illumination Si/Ge uni-traveling-carrier photodiodes based on silicon-on-insulator substrate

Si/Ge uni-traveling carrier photodiodes exhibit higher output current when space-charge effects are overcome and thermal effects are suppressed, which is highly beneficial for increasing the dynamic range of various microwave photonic systems and simplifying high-bit-rate digital receivers in different applications. From the point of view of packaging, detectors with vertical-illumination configuration can be easily handled by pick-and-place tools and are a popular choice for making photo-receiver modules. However, vertical-illumination Si/Ge uni-traveling carrier (UTC) devices suffer from inter-constraint between high speed and high responsivity. Here, we report a high responsivity vertical-illumination Si/Ge UTC photodiode based on a silicon-on-insulator substrate. The maximum absorption efficiency of the devices was 2.4 times greater than the silicon substrate owing to constructive interference. The Si/Ge UTC photodiode was successfully fabricated and had a dominant responsivity at 1550 nm of 0.18 A/W, a 50% improvement even with a 25% thinner Ge absorption layer.Comment: 5pages,2figure