Contextuality and Information Systems: how the interplay between paradigms can help

Through this paper, we theorize on the meanings and roles of context in the study of information systems. The literatures of information systems and information science both explicitly conceptualize information systems (and there are multiple overlapping definitions). These literatures also grapple with the situated and generalizable natures of an information system. Given these shared interests and common concerns, this paper is used as a vehicle to explore the roles of context and suggests how multi-paradigmatic research ??? another shared feature of both information science and information systems scholarship ??? provides a means to carry forward more fruitful studies of information systems. We discuss the processes of reconstructed logic and logic-in-use in terms of studying information systems. We argue that what goes on in the practice of researchers, or the logic-in-practice, is typified by what we are calling the contextuality problem. In response, we envision a reconstructed logic, which is an idealization of academic practices regarding context. The logic-in-use of the field is then further explained based on two different views on context. The paper concludes by proposing a model for improving the logic-in-use for the study of information systems

Terahertz generation using plasmonic photoconductive gratings

A photoconductive terahertz emitter based on plasmonic contact electrode gratings is presented and experimentally demonstrated. The nanoscale grating enables ultrafast and high quantum efficiency operation simultaneously, by reducing the photo-generated carrier transport path to the photoconductor contact electrodes. The presented photoconductor eliminates the need for a short-carrier lifetime semiconductor, which limits the efficiency of conventional photoconductive terahertz emitters. Additionally, the photo-absorbing active area of the plasmonic photoconductive terahertz emitter can be increased without a significant increase in the capacitive loading to the terahertz radiating antenna, enabling high quantum-efficiency operation at high pump power levels by preventing the carrier screening effect and thermal breakdown. A plasmonic photoconductive terahertz emitter prototype based on the presented scheme is implemented and integrated with dipole antenna arrays on a semi-insulating In 0.53 Ga 0.47 As substrate. Emitted terahertz radiation is characterized in a terahertz time-domain spectroscopy setup, measuring a terahertz pulse width of 590 fs full-width at half maximum in response to 150 fs pump pulses at 925 nm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98624/1/1367-2630_14_10_105029.pd

An Analytical Approach to Cycle Time Evaluation in an Unreliable Multi-Product Production Line with Finite Buffers

This thesis develops an analytical approximation method to measure the performance of a multi-product unreliable production line with finite buffers between workstations. The performance measure used in this thesis is Total Cycle Time. The proposed approximation method generalizes the processing times to relax the variation of product types in a multi-product system. A decomposition method is then employed to approximate the production rate of a multi-product production line. The decomposition method considers generally distributed processing times as well as random failure and repair. A GI/G/1/N queuing model is also applied to obtain parameters such as blocking and starving probabilities that are needed for the approximation procedure. Several numerical experiments under different scenarios are performed, and results are validated by simulation models in order to assess the accuracy and strength of the approximation method. Consequent analysis and discussion of the results is also presented

Social Technologies and Informal Knowledge Sharing within and across Organizations

This doctoral dissertation is focused on both empirical and conceptual contributions relative to the roles social technologies play in informal knowledge sharing practices, both within and across organizations. Social technologies include (a) traditional social technologies (e.g., email, phone and instant messengers), (b) emerging social networking technologies commonly known as social media, such as blogs, wikis, major public social networking sites (e.g., Facebook, Twitter and LinkedIn), and (c) enterprise social networking technologies controlled by a host organization ( e.g., SocialText). The rapid uptake of social technologies, combined with growing interest in their broader social implications, raises pertinent questions about uses for knowledge sharing in organizations. The work reported in this thesis is motivated by two broad phenomena: (1) the importance of informal knowledge-sharing in organizations and (2) the rapid rise in the variety and prevalence of social technologies. The empirical basis of this research is a field study focused on the uses of social technologies by knowledge workers, specifically those in consulting firms. Building from the theoretical lenses of sociomateriality, structuration, and technological frames, the findings from this work advances our understanding of: (1) the ways social technologies are used in combination as a suite of tools, (2) the ways in which organizational norms, policies, and arrangements shape the uses of social technologies for knowledge practices, and (3) the variations in uses of social technologies by different groups of knowledge workers. The theoretical contribution of this work is to conceptualize the suite of social technologies used to support and enable knowledge workers is a more useful approach than the single-technological-tool-in-isolation approach, which is the norm in studies of computing. A second contribution of this work is to situate social technologies-in-use through incorporating complementary theoretical concepts: technology-mediated knowledge practices, social structures of organizations, and workers\u27 distinct interpretations of social technologies (technological frames). Practical implications arising from this study both inform the ways social technologies can be collectively integrated in work practices and inform the design and implementation of social technologies for accommodating different needs and preferences of knowledge workers. This research also generates insight into how organizations can craft policies that realistically regulate the use of social technologies, while empowering individual workers to optimize their knowledge sharing capacity by supporting informal engagement via social technologies

Continuous-wave Cascaded-Harmonic Generation and Multi-Photon Raman Lasing in Lithium Niobate Whispering-Gallery Resonators

We report experimental demonstration of continuous-wave cascaded-harmonic generation and Raman lasing in a millimeter-scale lithium niobate whispering-gallery resonator pumped at a telecommunication-compatible infrared wavelength. Intensity enhancement through multiple recirculations in the whispering-gallery resonator and quasi phase-matching through a nonuniform crystal poling enable simultaneous cascaded-harmonic generation up to the fourth-harmonic accompanied by stimulated Raman, two-photon, three-photon, and four-photon Raman scattering corresponding the molecular vibrational wavenumbers 632 cm-1 and 255 cm-1 in z-cut lithium niobate at pump power levels as low as 200mW. We demonstrate simultaneous cascaded-harmonic generation and Raman lasing by observing the spectrum of the scattered light from the resonator and by capturing the image of the decoupled light from the resonator on a color CCD camera