Applications of the wave packet method to resonant transmission and reflection gratings

Scattering of femtosecond laser pulses on resonant transmission and reflection gratings made of dispersive (Drude metals) and dielectric materials is studied by a time-domain numerical algorithm for Maxwell's theory of linear passive (dispersive and absorbing) media. The algorithm is based on the Hamiltonian formalism in the framework of which Maxwell's equations for passive media are shown to be equivalent to the first-order equation, $\partial \Psi/\partial t = {\cal H}\Psi$, where ${\cal H}$ is a linear differential operator (Hamiltonian) acting on a multi-dimensional vector $\Psi$ built of the electromagnetic inductions and auxiliary matter fields describing the medium response. The initial value problem is then solved by means of a modified time leapfrog method in combination with the Fourier pseudospectral method applied on a non-uniform grid that is constructed by a change of variables and designed to enhance the sampling efficiency near medium interfaces. The algorithm is shown to be highly accurate at relatively low computational costs. An excellent agreement with previous theoretical and experimental studies of the gratings is demonstrated by numerical simulations using our algorithm. In addition, our algorithm allows one to see real time dynamics of long leaving resonant excitations of electromagnetic fields in the gratings in the entire frequency range of the initial wide band wave packet as well as formation of the reflected and transmitted wave fronts.Comment: 23 pages; 8 figures in the png forma

Information sharing and user behavior in Internet-enabled Peer-to-Peer Lending Systems: an empirical study

Internet-based information systems (IS) have enabled various forms of collective intelligence, action, and resources (e.g. open source software, innovation marketplaces, crowdsourcing, and crowdfunding). Within the domain of crowdfunding, Internet-enabled Peer-to-Peer Lending Systems (IP2PLS) have emerged as a disruptive technology, with implications for the financial services sector, business capitalization strategies, and personal and community development. IS research investigating user behavior in IP2PLS has revealed the saliency of social identity and personal transparency (as expressed through information sharing) in such systems. Prior research has largely focused on a small number of IP2PLS providers, thus this study examines a very large but under-researched platform. The study tests a theoretical model based on Social Identity Theory and prior IP2PLS studies, through an analysis of 116,667 loan records, and a subsequent analysis of 1000 manually coded records, to investigate the impact of information sharing on user (lenders and borrowers) behavior. The study reveals the importance of social (vs financial) data, and further reveals relationships that frequently contradict prior findings from other IP2PLS. The study thus implies the need for a more heterogeneous view of the IP2PLS domain, and the need to more fully understand as systems that support user behavior by enabling social information exchanges

An exploratory conceptual model for digital entrepreneurs within entrepreneurial ecosystems

The entrepreneurial ecosystem is a well-known concept in supporting the creation and growth of entrepreneurs, driving the economy in a region. However, entrepreneurship is evolving, as more and more novel digital technologies are introduced into our lives. Accordingly, this paper focuses on digital entrepreneurs, who are defined as the entrepreneurs, who utilize innovation based on digital technology to create economic or social value by starting new ventures or transform existing ones (European Commission, 2015), and the relevant ecosystem that supports them. The change in the relationship between digital entrepreneurs and an entrepreneurial ecosystem, as they evolve towards digital products and customer engagement is the focus of this research. We reviewed the literature on the topic of digital entrepreneurs and entrepreneurial ecosystem using a concept-centric matrix, capturing 14 elements of an entrepreneurial ecosystem. These elements include networks, policy and government, professional and support services, capital services, human capital, culture, markets, knowledge sources, intermediaries, informal networks, leadership, physical infrastructure, engagement, and cooperative companies. The identified elements were then used to develop a conceptual framework, which will form the basis for the research strategy. This study sets out to establish the existence of these elements in the ecosystems and the extent of their usefulness. Therefore, this paper seeks to address the research gap of how digital entrepreneurs utilize each ecosystem element to understand their importance in the conceptual framework. We intend to conduct an exploratory quantitative research approach, gathering data from start-up digital entrepreneurs that are engaged in an entrepreneurial ecosystem, by using a data instrument derived from the conceptual framework. Then, we will analyze the data using descriptive and bi-variate statistical tools to uncover causal relations between the elements. The next phase of the research will involve case studies, where we plan to use the updated conceptual framework to undertake in-depth interviews to establish the context of digital entrepreneurial ecosystems

Competitive market innovation contests and social capital: diametrically opposed, or inherently linked?

Competitive market innovation contest platforms are increasingly used by businesses to identify new products or services to offer their customer base; yet, the degree to which social capital has been explored within these online communities remains scarce. While there is ample support for the presence of social capital within other forms of virtual communities to facilitate knowledge sharing, competitive markets represent a unique setting given the inherent competitive nature of their contest solvers. This has led to a distinct lack of prior research exploring this area, especially as previous studies have chosen to focus instead on social capital vis-à-vis solver motivation rather than a standalone theory. We investigate six competitive markets from the perspective of their experts to explore how the three dimensions of social capital have a role within this setting: (1) the structural dimension (involving social ties), (2) the relational dimension (involving trust, reciprocity and self-identity), and (3) the cognitive dimension (involving shared language and shared vision). Through this study, we present a theoretical model of both the emergent themes and the net impacts of social capital within competitive markets, and discuss its implications for both IS research and practice

Ultra-fast Au(III)-mediated Arylation of Cysteine

Through mechanistic work and rational design, we have developed the fastest organometallic abiotic Cys bioconjugation. As a result, the developed organometallic Au(III) bioconjugation reagents enable selective labeling of Cys moieties down to pM concentrations and allow for the rapid construction of complex heterostructures from peptides, proteins, and oligonucleo-tides. This work showcases how organometallic chemistry can be interfaced with biomolecules and lead to the range of reac-tivities that are largely unmatched by classical organic chemistry tools