Growth of Incumbent Firms and Entrepreneurship in Vietnam

This paper analyzes the relationship between the performance of incumbent firms and the net entry of new firms by combining different theoretical views of entrepreneurship. It shows that new knowledge and ideas created but not commercialized by incumbents are an important source of entrepreneurial opportunities for nascent firms. Different regression models to treat dynamics and endogeneity issues are applied to test the research hypothesis that growth of incumbent firms in a region will stimulate start-up activities by creating new profit opportunities for potential entrepreneurs. Vietnam’s regional micro-data from 2000 to 2008 are used for this test. Four controlling indicators – entrepreneurial demand, market structure, regional economic environment, and market innovativeness – are found to exert a statistically significant effect on new entries.

The Interplay of Human and Social Capital in Shaping Entrepreneurial Performance: The Case of Vietnam

This study investigates the effects of human capital, social capital and their interaction on the performance of 1,398 Vietnamese new-born firms. Operating profit is used as the measure of success. Human capital is captured by individual-level professional education, start-up experience, and learning. Whereas the first two dimensions of human capital are measured with traditional indicators, we define learning as ability to accumulate knowledge to conduct innovation activities (new product introduction, product innovation and process innovation). Social capital is measured as benefits obtained from personal strong-tie and weak-tie networks. Key findings are three-fold: (i) human capital strongly predicts firm success, with learning exerting a statistically significant positive impact on operating profit; (ii) benefits from weak ties outweigh those from strong ties; (iii) interaction of human capital and social capital displays a statistically significant positive effect on new-firm performance.

Closed-form Absorption Probability of Certain D=5 and D=4 Black Holes and Leading-Order Cross-Section of Generic Extremal p-branes

We obtain the closed-form absorption probabilities for minimally-coupled massless scalars propagating in the background of D=5 single-charge and D=4 two-charge black holes. These are the only two examples of extremal black holes with non-vanishing absorption probabilities that can be solved in closed form for arbitrary incident frequencies. In both cases, the absorption probability vanishes when the frequency is below a certain threshold, and we discuss the connection between this phenomenon and the behaviour of geodesics in these black hole backgrounds. We also obtain leading-order absorption cross-sections for generic extremal p-branes, and show that the expression for the cross-section as a function of frequency coincides with the leading-order dependence of the entropy on the temperature in the corresponding near-extremal p-branes.Comment: Latex (3 times), 20 page

Involutivity of integrals for sine-Gordon, modified KdV and potential KdV maps

Closed form expressions in terms of multi-sums of products have been given in \cite{Tranclosedform, KRQ} of integrals of sine-Gordon, modified Korteweg-de Vries and potential Korteweg-de Vries maps obtained as so-called $(p,-1)$-traveling wave reductions of the corresponding partial difference equations. We prove the involutivity of these integrals with respect to recently found symplectic structures for those maps. The proof is based on explicit formulae for the Poisson brackets between multi-sums of products.Comment: 24 page

Co-doping red-emitting Sr2Si5N8:Eu2+ into yellow-emitting phosphor-packaging for enhancing the optical properties of the 8500 K remote-phosphor packaging wleds

In the last decades, WLEDs attract more and more consideration in both academic and industrial purposes because of its advantages such as fast response time, environment friendliness, small size, long lifetime, and high efficiency. In this research, by doping the red-emitting Sr2Si5N8:Eu2+ phosphor particles into yellow-emitting YAG:Ce phosphor-packaging, a new recommendation for enhancing the optical properties (color uniformity, color rendering index, and lumen output) of the 8500 K remote-phosphor packaging WLEDs is presented, investigated, and demonstrated. By using Mat Lab and Light Tools software based on Mie Theory, the obtained results show that the optical properties of the 8500 K remote-phosphor packaging WLEDs significantly depended on Sr2Si5N8:Eu2+ concentration. The results have provided a potential practical recommendation for manufacturing remote-phosphor W-LEDs.Web of Science1341034102

Well-Rounded ideal lattices of cyclic cubic and quartic fields

In this paper, we find criteria for when cyclic cubic and cyclic quartic fields have well-rounded ideal lattices. We show that every cyclic cubic field has at least one well-rounded ideal. We also prove that there exist families of cyclic quartic fields which have well-rounded ideals and explicitly construct their minimal bases. In addition, for a given prime number $p$, if a cyclic quartic field has a unique prime ideal above $p$, then we provide the necessary and sufficient conditions for that ideal to be well-rounded. Moreover, in cyclic quartic fields, we provide the prime decomposition of all odd prime numbers and construct an explicit integral basis for every prime ideal.Comment: 26 page