Three essays on entrepreneurship : theory, measurement, and environment

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on October 15, 2007)Vita.Thesis (Ph. D.) University of Missouri-Columbia 2007.This dissertation consists of three essays. In Essay One, I question the conventional wisdom that economic transactions are governed either by the price mechanism or by the authority of the firm. I argue that the exchange of information and knowledge for innovative production does not totally conform to such alternatives of governance. I term such exchanges hidden transactions. Since innovative production takes place inside the mind, individual entrepreneurship is the fundamental force that initializes hidden transactions. Institutional factors that enhance hidden transactions are important. In Essay Two I consider two types of entrepreneurship, conceiving entrepreneurship and performing entrepreneurship, and argue that while conceiving entrepreneurship is largely unobservable performing entrepreneurship can be measured. A confirmatory factor analysis under latent variable modeling is proposed and multiple indicators are used to manifest performing technology entrepreneurship. Results show that the proposed model is plausible. In Essay Three, I argue that the performing entrepreneurship of a region depends on the entrepreneur's regional opportunity set. Four components of the opportunity set include the availability of strategic resources, the ease of combining resources, the ease of founding a firm, and the security of doing business. The OLS model results indicate that R&D investment, anchor firms, appropriate government size, and intellectual property law are important elements of these components.Includes bibliographical reference

Gate defined quantum dot realized in a single crystalline InSb nanosheet

Single crystalline InSb nanosheet is an emerging planar semiconductor material with potential applications in electronics, infrared optoelectronics, spintronics and topological quantum computing. Here we report on realization of a quantum dot device from a single crystalline InSb nanosheet grown by molecular-beam epitaxy. The device is fabricated from the nanosheet on a Si/SiO2 substrate and the quantum dot confinement is achieved by top gate technique. Transport measurements show a series of Coulomb diamonds, demonstrating that the quantum dot is well defined and highly tunable. Tunable, gate-defined, planar InSb quantum dots offer a renewed platform for developing semiconductor-based quantum computation technology.Comment: 12 pages, 4 figure

Secure Storage and Retrieval of Data without Original Files in Cloud Architectures Subtitle as needed

Abstract. When a client uses the service which is offered by cloud storage providers, he might worry about how to retrieve their original files securely. Relieving client's storage burden and successfully retrieving data on demand are the ultimate purposes of cloud storage service. To achieve the above two aims, in this paper we propose a specific way to store and retrieve the out stored data in cloud storage. We utilize an efficient publicly verifiable secret sharing (PVSS) scheme to divide the file into multiple parts and store them among a group of servers, then using the recovery algorithm in PVSS, the users can retrieve their stored files successfully from any k qualified servers without the need of holding original file. Thus, the storage burden of the user is relieved much. And we show that the security of the protocol is closely related to the computational Diffie-Hellman problem

Anisotropic Pauli spin-blockade effect and spin-orbit interaction field in an InAs nanowire double quantum dot

We report on experimental detection of the spin-orbit interaction field in an InAs nanowire double quantum dot device. In the spin blockade regime, leakage current through the double quantum dot is measured and is used to extract the effects of spin-orbit interaction and hyperfine interaction on spin state mixing. At finite magnetic fields, the leakage current arising from the hyperfine interaction is suppressed and the spin-orbit interaction dominates spin state mixing. We observe dependence of the leakage current on the applied magnetic field direction and determine the direction of the spin-orbit interaction field. We show that the spin-orbit field lies in a direction perpendicular to the nanowire axis but with a pronounced off-substrate-plane angle. It is for the first time that such an off-substrate-plane spin-orbit field in an InAs nanowire has been detected. The results are expected to have an important implication in employing InAs nanowires to construct spin-orbit qubits and topological quantum devices.Comment: 20 pages, 5 figures, Supporting Informatio

Two-dimensional Mott variable-range hopping transport in a disordered MoS2_2 nanoflake

The transport characteristics of a disordered MoS$_2$ nanoflake in the insulator regime are studied by electrical and magnetotransport measurements. The layered MoS$_2$ nanoflake is exfoliated from a bulk MoS$_2$ crystal and the conductance $G$ and magnetoresistance are measured in a four-probe setup over a wide range of temperatures. At high temperatures, we observe that $\log_{10}G$ exhibits a $-T^{-1}$ temperature dependence and the transport in the nanoflake dominantly arises from thermal activation. At low temperatures, where the transport in the nanoflake dominantly takes place via variable-range hopping (VRH) processes, we observe that $\log_{10}G$ exhibits a $-T^{-1/3}$ temperature dependence, an evidence for the two-dimensional (2D) Mott VRH transport. The measured low-field magnetoresistance of the nanoflake in the insulator regime exhibits a quadratic magnetic field dependence $\sim \alpha B^2$ with $\alpha\sim T^{-1}$, fully consistent with the 2D Mott VRH transport in the nanoflake.Comment: 14 pages, 4 figures, and Supplemental Material

Perception of Air Pollution in the Jinchuan Mining Area, China:A Structural Equation Modeling Approach

Studies on the perception of air pollution in China are very limited. The aim of this paper is to help to fill this gap by analyzing a cross-sectional dataset of 759 residents of the Jinchuan mining area, Gansu Province, China. The estimations suggest that perception of air pollution is two-dimensional. The first dimension is the perceived intensity of air pollution and the second is the perceived hazardousness of the pollutants. Both dimensions are influenced by environmental knowledge. Perceived intensity is furthermore influenced by socio-economic status and proximity to the pollution source; perceived hazardousness is influenced by socio-economic status, family health experience, family size and proximity to the pollution source. There are no reverse effects from perception on environmental knowledge. The main conclusion is that virtually all Jinchuan residents perceive high intensity and hazardousness of air pollution despite the fact that public information on air pollution and its health impacts is classified to a great extent. It is suggested that, to assist the residents to take appropriate preventive action, the local government should develop counseling and educational campaigns and institutionalize disclosure of air quality conditions. These programs should pay special attention to young residents who have limited knowledge of air pollution in the Jinchuan mining area

Necessary conditions for reaction-diffusion system with delay preserving positivity

We consider the reaction--diffusion system with delay \begin{equation*} \left\{\begin{aligned} &\frac{\partial u}{\partial t}=A(t,x)\Delta u-\sum_{i=1}^{k}\gamma_{i}(t,x)\partial_{x_{i}}u +f(t,u_{t}) , &x\in \Omega; \\ &B(u)|_{\partial \Omega}=0.\\ \end{aligned} \right. \end{equation*} We show that this system with delay preserves positivity if and only if its diffusion matrix $A$ and convection matrix $\gamma_{i}$ are diagonal with non-negative elements and nonlinear delay term $f$ satisfies the normal tangential condition