Investigation of different light delivery schemes in photodynamic therapy of human glioma spheroids

The response of human glioma spheroids to ALA-mediated photodynamic therapy subjected to various optical dose delivery schemes is investigated. In particular, the effects of fluence, fluence rate, light dose fractionation and long-term repeat PDT is considered. Improved PDT response was found for low fluence rate photodynamic treatments i.e. those at or below 25 mW cm-2 . Results are consistent with the self-sensitized singlet oxygen mediated photobleaching model of Georgakoudi et al (Georgakoudi, 1998., in which the response is attributed to the deposition of singlet oxygen to a larger volume, i.e., deeper into the spheroid. The efficacy of high-fluence rate PDT (150 mW cm-2) can be improved by the introduction of dark intervals---an approximately 35% enhanced spheroid response was observed with cyclic intervals of between 15 and 45 s. Shorter on/off cycles appear more effective than longer cycles; Repetitive PDT consisting of multiple weekly treatments at sub-optimal fluences (12.5 or 25 J cm-2) revealed marked improvements in efficacy. (Abstract shortened by UMI.)

General method for prediction of thermal conductivity for well-characterized hydrocarbon mixtures and fuels up to extreme conditions using entropy scaling

A general and efficient technique is developed to predict the thermal conductivity of well-characterized hydrocarbon mixtures, rocket propellant (RP) fuels, and jet fuels up to high temperatures and high pressures (HTHP). The technique is based upon entropy scaling using the group contribution method coupled with the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state. The mixture number averaged molecular weight and hydrogen to carbon ratio are used to define a single pseudo-component to represent the compounds in a well-characterized hydrocarbon mixture or fuel. With these two input parameters, thermal conductivity predictions are less accurate when the mixture contains significant amounts of iso-alkanes, but the predictions improve when a single thermal conductivity data point at a reference condition is used to fit one model parameter. For eleven binary mixtures and three ternary mixtures at conditions from 288 to 360 K and up to 4,500 bar, thermal conductivities are predicted with mean absolute percent deviations (MAPDs) of 16.0 and 3.0% using the two-parameter and three-parameter models, respectively. Thermal conductivities are predicted for three RP fuels and three jet fuels at conditions from 293 to 598 K and up to 700 bar with MAPDs of 14.3 and 2.0% using the two-parameter and three-parameter models, respectively

Maximum MLC opening effect in dynamic delivery of IMRT: leaf‐positional analysis

The analysis of dynamic multileaf collimator (MLC) positions for the delivered intensity‐modulated radiotherapy (IMRT) plans is crucial in that it may capture dose delivery problems otherwise difficult to observe and quantify in the conventional dosimetric measurements with film or with an ionization chamber. In some IMRT systems, delivery of IMRT fields starts with a maximum MLC opening (roughly the shape of the target in the beam's‐eye view) and then proceeds to the subsequent dynamic MLC subfields. No irradiation is required in going from the initial segment (maximum opening) to the next one, and theoretically, no dose should be delivered in that initial moment. However, due to a finite sampling time of the MLC controller, the finite speed of the MLC, and a finite leaf tolerance, there may be some dose delivered between the first and the second segment. The amount of the excess dose is higher for larger dose rates and for a smaller number of the total monitor units per IMRT field. The magnitude of the dose errors could be in the order of a few percent. Effects similar to the maximum MLC opening may occur in other situations as well, for instance, when leaves are forced to move over large distances in a short time. Confounding this are dose errors due to the uncertainty in the MLC transmission. The analysis of the actual leaf positions recorded in the dynamic MLC log file is helpful in differentiating between the two types of errors and in determining the optimal dynamic MLC delivery parameters. PACS numbers: 87.53.‐j, 87.90.+

Characterization of high-current, high-temperature superconductor current lead elements

The refrigeration loads of current leads for superconducting magnets can be significantly reduced by using high-temperature superconductor (HTS) leads. An HTS conductor type that is well suited for this application is a laminated sintered stack of HTS powder-in-tube (PIT) tapes. The superconducting elements are normally characterized by their manufacturer by measuring critical currents at 77 K in self field. Additional characterization, which correlates electrical performance at 77 K and at lower temperatures with applied magnetic fields, provides the current lead designer and conductor element manufacturer with critical information. For HTS conductor elements comprising a laminated and sintered stack of Bi-2223 PIT tapes having an alloyed Ag sheath, this characterization uses variable applied fields and operating temperatures

The Optimal Workplace: Organizational and Managerial Structures Supporting Individual Role Quality in the Workplace

A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Arts in Sociology, University of Regina. vi, p.144Rationale: The purpose of this thesis is to examine employee perceptions and experiences in order to understand which attributes support the creation and maintenance of an optimal work culture. Aim: The thesis is driven by three areas of inquiry: an individual‘s perception of workplace quality and optimality; organizational and managerial attributes contributing to quality workplaces; and techniques applied in a workplace to achieve an optimal workplace culture and employee experience. Methodology: This investigation is situated under the rubric of the Interpretivist paradigm, which emphasizes the importance of understanding the ‗lived experiences‘ from the point of view of those who live it day to day as reality is socially and experientially based, local and specific. In line with this approach, qualitative methodology is used to address the research questions. The qualitative data used within this thesis are collected from four focus groups (n=11). Focus group interviews are conducted to collect original data about workplace managerial structures. The purpose is to add in-depth perspective to a small but growing collection of work in this area. The intent is not to generalize individual experiences, but to understand how a group of Saskatchewan government workers perceive the workplace and define what constitutes an optimal workplace. The data were analyzed using a grounded theory method. Lines of the transcription are sorted by thematic experiences, which are confirmed by empirical data to link individual experiences to relevant workplace issues. Discussion: Results show that personal growth, flexibility and autonomy, social networking, and managerial support, are the factors most sought after in a workplace. The focus group data indicates that individuals who have elevated levels of quality and satisfaction within their work role report more positive experiences in the workplace. Conclusion: Focus group participants discussed their workplace experiences and described how the organizational structure and management style of supervisors affected their perceived work culture. From the findings, interpersonal relationships with managers and peers were the most common source of support for individuals, followed by policies that promoted flexible environments and autonomy. Thus, it was determined that a workplace supporting individual efforts to balance work roles and obligations provides individuals with an advantage in maintaining work and personal role quality,and creating a sense of optimality at work. Keywords: Work and life roles; optimal workplace; role quality; support; managerial and organizational structures; balance; well-being; networking; and satisfaction.Studentye

Design a Tiny House on Wheels for Wildfire and Indoor Air Quality Research and Teaching

As the effects of climate change become more prevalent, along with rising temperatures and droughts, the risk of wildfires has also increased. While there is ongoing research in labs that replicate the wildfire atmosphere, it is impossible to account for every variation that could affect research. Additionally, conducting a field study in occupied residential homes would pose significant challenges in terms of timely organization and setup of experimental equipment. Therefore, our goal was to design a portable research space that could be transported to locations around the US that are impacted by wildfires, perform live research, and produce accurate results. In the future, this research could help come up with solutions to completely eliminate harmful exposure to wildfire smoke

Understanding Perceptions of Residents and Officials to Reduce Wildfire Risk in Estes Park

Wildfires have increased in both intensity and frequency across Estes Park, Colorado across decades. Collaborating with the Boulder Watershed Collective, we aimed to understand the perceptions surrounding wildfires from the perspectives of residents, town officials, and external organizations. We conducted 38 semi-structured interviews to understand wildfire plans and document experiences of residents regarding recent wildfires. The interviews were recorded, transcribed, and coded to extract common themes and ideas. The need for evacuation protocols, the importance of communication, and the exclusion of vulnerable populations of Estes Park were among our key findings. The group primarily recommends that communication and education strategies be expanded to reach a greater audience in an emergency

A Group Contribution Method for the Prediction of Thermal Conductivity of Liquids and Its Application to the Prandtl Number for Vegetable Oils

Data on thermal conductivity of liquids, as a function of temperature, are essential in the design of heat- and mass-transfer equipment. A number of correlations have been developed to predict thermal conductivity of liquids with limited success. Among the correlations proposed so far, only the correlation due to Nagvekar and Daubert (Ind. Eng. Chem. Res. 1987, 26, 1362) is based on group contributions. In this paper, a new group contribution method is developed based on the Klaas and Viswanath (Ind. Eng. Chem. Res. 1998, 37, 2064) method for prediction of thermal conductivity of liquids and the results are compared to the method of Nagvekar and Daubert and other existing correlations. The present method predicts thermal conductivity of some 228 liquids that encompass 1487 experimental data points with an average absolute deviation of 2.5%. The group contribution method is used to examine the temperature dependence of Prandtl number for vegetable oils