8,280 research outputs found
Participantsâ reflections on being interviewed about risk and sexual behaviour: implications for collection of qualitative data on sensitive topics
In this article, we explore how those taking part in an interview about sex and risk reflected on their participation and what, if any, impact it had on them. All 22 individuals who were interviewed in an initial study were invited to document their thoughts and feelings about the research process in a short follow-up exercise. The data relating to the 11 people who shared their reflections on the interview were subjected to a thematic analysis. The themes that emerged describe the value participants placed on honest and open interaction within neutral and non-judgmental environments. They also illustrate how being interviewed about prior behaviour can facilitate a sense-making process and might provide some degree of cathartic benefit. The findings help improve our understanding of how individuals reflect on their interview participation, which can in turn help to inform the development of ethically sensitive qualitative data collection
The resolution bias: low resolution feedback simulations are better at destroying galaxies
Feedback from super-massive black holes (SMBHs) is thought to play a key role
in regulating the growth of host galaxies. Cosmological and galaxy formation
simulations using smoothed particle hydrodynamics (SPH), which usually use a
fixed mass for SPH particles, often employ the same sub-grid Active galactic
nuclei (AGN) feedback prescription across a range of resolutions. It is thus
important to ask how the impact of the simulated AGN feedback on a galaxy
changes when only the numerical resolution (the SPH particle mass) changes. We
present a suite of simulations modelling the interaction of an AGN outflow with
the ambient turbulent and clumpy interstellar medium (ISM) in the inner part of
the host galaxy at a range of mass resolutions. We find that, with other things
being equal, degrading the resolution leads to feedback becoming more efficient
at clearing out all gas in its path. For the simulations presented here, the
difference in the mass of the gas ejected by AGN feedback varies by more than a
factor of ten between our highest and lowest resolution simulations. This
happens because feedback-resistant high density clumps are washed out at low
effective resolutions. We also find that changes in numerical resolution lead
to undesirable artifacts in how the AGN feedback affects the AGN immediate
environment.Comment: 15 pages, 12 figures, accepted for publication in MNRA
Black hole feedback in a multiphase interstellar medium
Ultrafast outflows (UFOs) from supermassive black holes (SMBHs) are thought
to regulate the growth of SMBHs and host galaxies, resulting in a number of
observational correlations. We present high-resolution numerical simulations of
the impact of a thermalized UFO on the ambient gas in the inner part of the
host galaxy. Our results depend strongly on whether the gas is homogeneous or
clumpy. In the former case all of the ambient gas is driven outward rapidly as
expected based on commonly used energy budget arguments, while in the latter
the flows of mass and energy decouple. Carrying most of the energy, the shocked
UFO escapes from the bulge via paths of least resistance, taking with it only
the low-density phase of the host. Most of the mass is however in the
high-density phase, and is affected by the UFO much less strongly, and may even
continue to flow inwards. We suggest that the UFO energy leakage through the
pores in the multiphase interstellar medium (ISM) may explain why observed
SMBHs are so massive despite their overwhelmingly large energy production
rates. The multiphase ISM effects reported here are probably under-resolved in
cosmological simulations but may be included in prescriptions for active
galactic nuclei feedback in future simulations and in semi-analytical models.Comment: 12 pages, 8 figures, accepted in MNRA
Run-Time Selection of Coordination Mechanisms in Multi-Agent Systems
This paper presents a framework that enables autonomous agents to dynamically select the mechanism they employ in order to coordinate their inter-related activities. Adopting this framework means coordination mechanisms move from the realm of being imposed upon the system at design time, to something that the agents select at run-time in order to fit their prevailing circumstances and their current coordination needs. Empirical analysis is used to evaluate the effect of various design alternatives for the agent's decision making mechanisms and for the coordination mechanisms themselves
âBrick & Mortarâ Education and âReal Worldâ Experience: Assessing HRM Alumni Perceptions of their Early Professional Development
In this research we examined the extent to which three distinct human resource management (HRM) undergraduate programs provide coverage of the 13 core content areas specified by the Society for Human Resource Management (SHRM) and explored the usefulness of various ways of learning including their undergraduate coursework, an internship, and previous work experience as related to early professional development. Based on perceptions of HRM alumni, the findings reveal that the three curricula provided significant differences in levels of proficiency in seven of the core areas and in perceived usefulness of the learning methods. Implications for HRM curriculum development and studentsâ professional development are discussed
Helicopter roll control effectiveness criteria program summary
A study of helicopter roll control effectiveness is summarized for the purpose of defining military helicopter handling qualities requirements. The study is based on an analysis of pilot-in-the-loop task performance of several basic maneuvers. This is extended by a series of piloted simulations using the NASA Ames Vertical Motion Simulator and selected flight data. The main results cover roll control power and short-term response characteristics. In general the handling qualities requirements recommended are set in conjunction with desired levels of flight task and maneuver response which can be directly observed in actual flight. An important aspect of this, however, is that vehicle handling qualities need to be set with regard to some quantitative aspect of mission performance. Specific examples of how this can be accomplished include a lateral unmask/remask maneuver in the presence of a threat and an air tracking maneuver which recognizes the kill probability enhancement connected with decreasing the range to the target. Conclusions and recommendations address not only the handling qualities recommendations, but also the general use of flight simulators and the dependence of mission performance on handling qualities
Thermal energy storage material thermophysical property measurement and heat transfer impact
The thermophysical properties of salts having potential for thermal energy storage to provide peaking energy in conventional electric utility power plants were investigated. The power plants studied were the pressurized water reactor, boiling water reactor, supercritical steam reactor, and high temperature gas reactor. The salts considered were LiNO3, 63LiOH/37 LiCl eutectic, LiOH, and Na2B4O7. The thermal conductivity, specific heat (including latent heat of fusion), and density of each salt were measured for a temperature range of at least + or - 100 K of the measured melting point. Measurements were made with both reagent and commercial grades of each salt
Default reasoning using maximum entropy and variable strength defaults
PhDThe thesis presents a computational model for reasoning with partial information
which uses default rules or information about what normally happens. The idea is
to provide a means of filling the gaps in an incomplete world view with the most
plausible assumptions while allowing for the retraction of conclusions should they
subsequently turn out to be incorrect. The model can be used both to reason from
a given knowledge base of default rules, and to aid in the construction of such
knowledge bases by allowing their designer to compare the consequences of his
design with his own default assumptions. The conclusions supported by the proposed
model are justified by the use of a probabilistic semantics for default rules
in conjunction with the application of a rational means of inference from incomplete
knowledge the principle of maximum entropy (ME). The thesis develops
both the theory and algorithms for the ME approach and argues that it should be
considered as a general theory of default reasoning.
The argument supporting the thesis has two main threads. Firstly, the ME approach
is tested on the benchmark examples required of nonmonotonic behaviour,
and it is found to handle them appropriately. Moreover, these patterns of commonsense
reasoning emerge as consequences of the chosen semantics rather than
being design features. It is argued that this makes the ME approach more objective,
and its conclusions more justifiable, than other default systems. Secondly, the
ME approach is compared with two existing systems: the lexicographic approach
(LEX) and system Z+. It is shown that the former can be equated with ME under
suitable conditions making it strictly less expressive, while the latter is too crude to
perform the subtle resolution of default conflict which the ME approach allows. Finally,
a program called DRS is described which implements all systems discussed
in the thesis and provides a tool for testing their behaviours.Engineering and Physical Science Research Council (EPSRC
Encountering One Another: Feminist Relationships in Organizational Research
As a graduate student attempting to integrate feminist principles into my academic endeavors, I eagerly entered the research field to examine how women business owners who feel a conflict between feminism and capitalism enact their everyday lives. I chose participant observation, a common methodology in feminist research, with the aim of getting âinsideâ these womenâs lives to better understand their experiences. However, as the fieldwork proceeded, my focus shifted to examining the space in which the realities of the feminist organizational researcher and of the feminist business owner encounter one another. This paper reflects upon how we made sense of our practices through complex interactions that blurred the binary between subject/object and researcher/researched. By acknowledging the co-constitution of the research process, scholars of organizational studies can begin to rethink the relationship between the âresearcherâ and the âresearchedâ and ask questions about the power dynamics inherent to fieldwork
- âŠ