Reaching A Point Of Mutual Understanding: A Practitioners Approach To Systems Development

This practitioner paper explores the background of the development of two separate information systems. The first a case study where a SME was able to commission the design and implementation of an information system that offered a solution to restraints on the growth of the business, and a second case study of an SME, whilst unable to articulate the requirements for an Information system, with the support of a patient programmer, was able to commission a system that was developed, grew, and was sustained, over a ten year period. The paper explores the ideas of how both commissioners and developers can negotiate to a point of mutual understanding benefiting all stakeholders of the system and, as a result of learning from practice, The discussion point of this paper is a reflection on theory from the perspective of the practitioner

Extremely Non-Degenerate Two Photon Absorption Sensing Method, Apparatus, and Applications

An extremely non-degenerate two photon absorption (END-2PA) method and apparatus provide for irradiating a semiconductor material substrate simultaneously with two photons each of different energy less than a bandgap energy of the semiconductor material substrate but in an aggregate greater than the bandgap energy of the semiconductor material substrate. A ratio of a higher energy photon energy to a lower energy is at least about 3.0. Alternatively, or as an adjunct, the higher energy and the lower energy photon has an energy no greater than about 25% of the bandgap energy

Continuously Variable, Wavelength-Independent Polarization Rotator

A useful optical device to provide continuously variable rotation of polarization of linearly polarized light in a wavelength-independent manner. This device features a cell of twisted nematic liquid crystal sandwiched between an input window and a rotatable output window, both with surfaces prepared so as to orient the nematic liquid crystal molecules. This optical device has different applications such as: variable-angle polarization rotator; using broad band polarizers as an energy attenuator; working in both cases as a wavelength independent and temporal pulse width independent device. The low cost, the very wide field of view, the wavelength and pulse width independence, the high efficiency, and its mechanical simplicity make of this new optical device a very useful and novel invention

Low frequency Raman gain measurements using chirped pulses

Two-beam coupling, attributed to Raman gain, is observed in dielectrics using chirped femtosecond pulses. A time resolved pump-probe geometry is used to vary the frequency difference between pulses in the terahertz frequency band. Stimulated Raman scattering couples the pulses transferring energy from the higher to the lower frequency beam, resulting in a dispersion shaped curve as a function of the temporal delay, dependent on the product of the pump and probe irradiances. The observed signal gives the Raman gain in SiO2 and PbF2 for detunings up to 10 THz (approximately 300 cm(-1)) using mm-thick samples. This method may also be sensitive to the electronic motion responsible for bound-electronic nonlinear refractive index, which could yield the optical response time of bound electrons

Alternative causal inference methods in population health research: Evaluating tradeoffs and triangulating evidence.

Population health researchers from different fields often address similar substantive questions but rely on different study designs, reflecting their home disciplines. This is especially true in studies involving causal inference, for which semantic and substantive differences inhibit interdisciplinary dialogue and collaboration. In this paper, we group nonrandomized study designs into two categories: those that use confounder-control (such as regression adjustment or propensity score matching) and those that rely on an instrument (such as instrumental variables, regression discontinuity, or differences-in-differences approaches). Using the Shadish, Cook, and Campbell framework for evaluating threats to validity, we contrast the assumptions, strengths, and limitations of these two approaches and illustrate differences with examples from the literature on education and health. Across disciplines, all methods to test a hypothesized causal relationship involve unverifiable assumptions, and rarely is there clear justification for exclusive reliance on one method. Each method entails trade-offs between statistical power, internal validity, measurement quality, and generalizability. The choice between confounder-control and instrument-based methods should be guided by these tradeoffs and consideration of the most important limitations of previous work in the area. Our goals are to foster common understanding of the methods available for causal inference in population health research and the tradeoffs between them; to encourage researchers to objectively evaluate what can be learned from methods outside one's home discipline; and to facilitate the selection of methods that best answer the investigator's scientific questions