Engaging new dimensions in nonlinear optical spectroscopy using auxiliary beams of light

By applying a sufficiently intense beam of off-resonant light, simultaneously with a conventional excitation source beam, the efficiencies of one- and two-photon absorption processes may be significantly modified. The nonlinear mechanism that is responsible, known as laser modified absorption, is fully described by a quantum electrodynamical analysis. The origin of the process, which involves stimulated forward Rayleigh-scattering of the auxiliary beam, relates to higher order terms which are secured by a time-dependent perturbation treatment. These terms, usually inconsequential when a single beam of light is present, become prominent under the secondary optical stimulus – even with levels of intensity that are moderate by today’s standards. Distinctive kinds of behaviour may be observed for chromophores fixed in a static arrangement, or for solution- or gas-phase molecules whose response is tempered by a rotational average of orientations. In each case the results exhibit an interplay of factors involving the beam polarisations and the molecular electronic response. Special attention is given to interesting metastable states that are symmetry forbidden by one- or two-photon absorption. Such states may be accessible, and thus become populated, on input of the auxiliary beam. For example, in the one-photon absorption case, terms arise that are more usually associated with three-photon processes, corresponding to very different selection rules. Other kinds of metastable state also arise in the two-photon process, and measuring the effect of applying the stimulus beam to absorbances of such character adds a new dimension to the information content of the associated spectroscopy. Finally, based on these novel forms of optical nonlinearity, there may be new possibilities for quantum non-demolition measurements

Reactions to Skill Assessment: The Forgotten Factor in Explaining Motivation to Learn

This study examined the effects of trainees’ reactions to skill assessment on their motivation to learn. A model was developed that suggests that two dimensions of trainees’ assessment reactions – distributive justice and utility – influence training motivation and overall training effectiveness. The model was tested using a sample of individuals (N = 113) enrolled in a truck driving training program. Results revealed that trainees’ who perceived higher levels of distributive justice and utility had higher motivation to learn. Training motivation was found to significantly predict several measures of training effectiveness. Trainees’ performance on the pre-training assessment and trait goal orientation exhibited direct and interactive effects on their reactions to the skill assessment. Implications of these findings for future research on reactions to skill assessments are identified along with the practical implications for the design and conduct of training needs assessment

Archaeological Investigation of a Spring Lake Lot for Joe\u27s Crab Shack Parking

On August 19 and 25, 1997, the Center for Archaeological Research (CAR) of The University of Texas at San Antonio conducted an intensive survey for cultural resources at the proposed location of a parking lot for Joe\u27s Crab Shack Restaurants along Spring Lake, Hays County, Texas. The work was contracted by Southwest Texas State University (SWTSU) and conducted under Texas Antiquities Permit number 1877. Upon completion of the survey and subsurface testing, CAR determined that no cultural resources would be impacted by the planned parking lot construction. CAR therefore recommended that the project sponsor be allowed to proceed as planned with the proposed project and the Texas Historical Commission (THC) has concurred

On the detection of characteristic optical emission from electronically coupled nanoemitters

Optical emission from an electronically coupled pair of nanoemitters is investigated, in a new theoretical development prompted by experimental work on oriented semiconductor polymer nanostructures. Three physically distinct mechanisms for photon emission by such a pair, positioned in the near-field, are identified: emission from a pairdelocalized exciton state, emission that engages electrodynamic coupling through quantum interference, and correlated photon emission from the two components of the pair. Each possibility is investigated, in detail, by examination of the emission signal via explicit coupling of the nanoemitter pair with a photodetector, enabling calculations to give predictive results in a form directly tailored for experiment. The analysis incorporates both near- and far-field properties (determined from the detector-pair displacement), so that the framework is applicable not only to a conventional remote detector, but also a near-field microscope setup. The results prove strongly dependent on geometry and selection rules. This work paves the way for a broader investigation of pairwise coupling effects in the optical emission from structured nanoemitter arrays

Changing the way the world thinks about computer security.

Small changes in an established system can result in larger changes in the overall system (e.g. network effects, émergence, criticality, broken Windows theory). However, in an immature discipline, such as computer security, such changes can be difficult to envision and even more difficult to amplement, as the immature discipline is likely to lack the scientific framework that would allow for the introduction of even minute changes. (Cairns, P. and Thimbleby, H, 2003) describe three of the signs of an immature discipline as postulated by (Kuhn, 1970): a. squabbles over what are legitimate tools for research b. disagreement over which phenomenon are legitimate to study, and c. inability to scope the domain of study. The research presented in this document demonstrates how the computer security field, at the time this research began, was the embodiment of thèse characteristics. It presents a cohesive analysis of the intentional introduction of a séries of small changes chosen to aid in maturation of the discipline. Summarily, it builds upon existing theory, exploring the combined effect of coordinated and strategie changes in an immature system and establishing a scientific framework by which the impact of the changes can be quantified. By critically examining the nature of the computer security system overall, this work establishes the need for both increased scientific rigor, and a multidisciplinary approach to the global computer security problem. In order for these changes to take place, many common assumptions related to computer security had to be questioned. However, as the discipline was immature, and controlled by relatively few entities, questioning the status quo was not without difficulties. However, in order for the discipline to mature, more feedback into the overall computer security (and in particular, the computer malware/virus) system was needed, requiring a shift from a mostly closed system to one that was forced to undergo greater scrutiny from various other communities. The input from these communities resulted in long-term changes and increased maturation of the system. Figure 1 illustrates the specific areas in which the research presented herein addressed these needs, provides an overview of the research context, and outlines the specific impact of the research, specifically the development of new and significant scientific paradigms within the discipline