726 research outputs found
Richard Dawkins in conversation with Robyn Williams
No full textDawkins and Williams discuss the intricacies, the fascinating patterns and the anomalies produced by the process of evolution on earth.
At the Melbourne Town Hall, presented by the Melbourne Writers Festival, outspoken and influential author and scientist Richard Dawkins speaks to Robyn Williams (ABC RN) about the ideas underpinning his new book, The Greatest Show on Earth. They discuss the intricacies, the fascinating patterns and the anomalies produced by the process of evolution on earth. Dawkins then takes further questions from the audience about the theory of evolution, genetic determinism, the climate change denial movement and the place of religion in the world of science. Melbourne, March 2010.
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REVISITING THE ROLE OF M31 IN THE DYNAMICAL HISTORY OF THE MAGELLANIC CLOUDS
No full textWe study the dynamics of the Magellanic Clouds in a model for the Local Group whose mass is constrained using the timing argument/two-body limit of the action principle. The goal is to evaluate the role of M31 in generating the high angular momentum orbit of the Clouds, a puzzle that has only been exacerbated by the latest Hubble Space Telescope proper motion measurements. We study the effects of varying the total Local Group mass, the relative mass of the Milky Way (MW) and M31, the proper motion of M31, and the proper motion of the Large Magellanic Cloud (LMC) on this problem. Over a large part of this parameter space, we find that tides from M31 are insignificant. For a range of LMC proper motions approximately 3σ higher than the mean and total Local Group mass >3.5 × 10[superscript 12] M ☉, M31 can provide a significant torque to the LMC orbit. However, if the LMC is bound to the MW, then M31 is found to have negligible effect on its motion, and the origin of the high angular momentum of the system remains a puzzle. Finally, we use the timing argument to calculate the total mass of the MW-LMC system based on the assumption that they are encountering each other for the first time, their previous perigalacticon being a Hubble time ago, obtaining M [subscript MW] + M[subscript LMC] = (8.7 ± 0.8) × 10[superscript 11] M ☉
Seen and unseen tidal caustics in the Andromeda galaxy
No full textIndirect detection of high-energy particles from dark matter interactions is a promising
avenue for learning more about dark matter, but is hampered by the frequent coincidence
of high-energy astrophysical sources of such particles with putative high-density
regions of dark matter. We calculate the boost factor and gamma-ray flux from dark
matter associated with two shell-like caustics of luminous tidal debris recently discovered
around the Andromeda galaxy, under the assumption that dark matter is its own
supersymmetric antiparticle. These shell features could be a good candidate for indirect
detection of dark matter via gamma rays because they are located far from the primary
confusion sources at the galaxy’s center, and because the shapes of the shells indicate
that most of the mass has piled up near apocenter. Using a numerical estimator specifically
calibrated to estimate densities in N-body representations with sharp features and
a previously determined N-body model of the shells, we find that the largest boost factors
do occur in the shells but are only a few percent. We also find that the gamma-ray
flux is an order of magnitude too low to be detected with Fermi for likely dark matter
parameters, and about 2 orders of magnitude less than the signal that would have come
from the dwarf galaxy that produces the shells in the N-body model. We further show
that the radial density profiles and relative radial spacing of the shells, in either dark
or luminous matter, is relatively insensitive to the details of the potential of the host
galaxy but depends in a predictable way on the velocity dispersion of the progenitor
galaxy.United States. National Aeronautics and Space Administration (grant NNG06GG99G
Introducing in-house integrity testing into routine practise in a cochlear implant clinic
No full textFarm to Fork Quantitative Microbial Risk Assessment for Norovirus on Frozen Strawberries
No full textFoodborne illness outbreaks have been increasingly linked to the consumption of fresh and frozen berries that were contaminated with pathogenic viruses, such as human norovirus (NoV). Contamination of berries is assumed to take place at harvest by the use of contaminated water for pesticide dilution, irrigation water source or by shedding berry pickers in the field. A quantitative microbial risk assessment simulation model was built to replicate the largest known NoV outbreak which sickened about 11,000 people over a 3-week period. The outbreak occurred in Germany in 2012 when contaminated frozen strawberries were served at nearly 400 schools and daycare centers. The risk model explicitly assumed that all contamination would arise from NoV contamination of surface water used for pesticide dilution. Input data was collected from the published literature, observational studies and assumptions. The model starts with contamination of the berries in the field, and proceeds through transportation to processing facility, washing, sanitizing, freezing, frozen transport to cargo ship, transport view of cargo ship, transport to distribution center, frozen storage at the distribution center, transport to the catering facility, food service preparation and consumption, dose response, and predicted illnesses. A total of 21 scenarios were chosen to evaluate the impact of model parameters on the number of illness associated with NoV contamination of berries. Scenarios evaluated include the initial level of NoV in surface water, the effect of seasonality on the prevalence of NoV in surface water, the strength of the pesticide used, the volume of water used to dilute the pesticide, temperature during transportation to processing facility, washing and sanitizing conditions at processing facility and preparation (heat-treatment) of berries prior to consumption. Scenarios were compared via the Factor Sensitivity technique where the logarithm of the ratio of mean illnesses was used to compare different assumptions. The input that had the greatest effect on increasing in the number of illnesses was a high NoV concentration in the water (8 log Genome Copies/L) when compared to the baseline scenario with resulting mean illnesses of 7,964 illnesses and ~2 illnesses, respectively. This assumption about the concentration of virus in the pesticide makeup water was the only variable capable of producing an outbreak similar to that observed in Germany in 2012. Heat-treatment of the berries, use of a pesticide with strong antiviral effect, and assumption about the virus concentration in the pesticide make-up water had the largest impact on decreasing illnesses.Peer reviewe
Understanding dark matter halos with tidal caustics
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 181-188).The products of interactions between galaxies with a high mass ratio and low orbital angular momentum are studied. The interactions scatter the material from the smaller galaxy into structures with distinctive dynamics and morphology, including high local densities and a simple density profile related to properties of the participating galaxies. The role of the larger galaxy's tides in creating these structures and their relation to a well-studied class of mathematical objects motivates us to name them "tidal caustics". We study the densities achievable in tidal caustics for a typical merger of this type using an example from the Andromeda galaxy to determine whether they are sufficient to produce a detectable gamma-ray signal from self-interactions in the dark matter component, for likely particle models of dark matter. We find that the expected signal is an order of magnitude too low to be detected with current instruments. We also study the constraints that can be placed on the properties of the participating galaxies by observing the surface brightness profiles of the tidal caustics. We find that the local gravity and gravity gradient of the larger galaxy, and the energy spread and initial phase space density of the smaller galaxy, can be jointly constrained by fitting this profile. The constraints are degenerate but model-independent. We find that measurements of multiple caustics and the velocity of the material in each caustic along the line of sight give information about the orbital angular momentum and the deviations from spherical symmetry in the larger galaxy, though this information is somewhat model-dependent. We discuss the main technical difficulty in fitting the surface brightness profile: determining the inclination angle of the caustic. We demonstrate that a simple model can successfully recover the necessary parameters for some cases, and that a simple modification to this model will improve its success rate.by Robyn Ellyn Sanderson.Ph.D
"Exploring Our Sexualities" - Noted Author and Activist Robyn Ochs to Present Workshop and Interactive Presentation at U of M Crookston on Wednesday, April 22, 2009
No full textTollefson, Elizabeth. (2009). "Exploring Our Sexualities" - Noted Author and Activist Robyn Ochs to Present Workshop and Interactive Presentation at U of M Crookston on Wednesday, April 22, 2009. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/222053
Piloting the Recording of Electrode Voltages (REVS) using surface electrodes as a test to identify cochlear implant electrode migration, extra-cochlear electrodes and basal electrodes causing discomfort
No full textObjectives: To determine if Electrode Voltage (EV) measurements are potentially suitable as a test for detecting extra-cochlear electrodes in cochlear implants (CIs). Methods: EV measurements were made using surface electrodes in live mode in 17 adult cochlear implant (CI) users. Repeatability, the effects of stimulation level, CI active electrode position, (active) recording electrode position and stimulation mode (for Nucleus devices) were investigated. Results/discussion: Recordings made in monopolar mode showed good repeatability when the active recording electrode was placed on the ipsilateral earlobe; voltages increased linearly with stimulation level as expected. EVs for basal electrodes differed greatly between partially inserted/migrated devices, fully inserted devices with all electrodes activated, and those with deactivated basal electrodes [χ
2(2) = 10.2, p < 0.05 for the most basal electrode]. EVs for Nucleus devices were small for electrodes on the array when compared to those for monopolar return electrodes, except for the participant with extra-cochlear electrodes. We argue that fibrosis around the electrode array facilitated current flow across the round window in this case. Conclusion: The test appears to be a viable approach to detect electrode migration and extra-cochlear electrodes in adult CI users and may also be sensitive to discomfort caused by current leakage from the basal end of the cochlea.
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A case study of the design, implementation, and formative evaluation of a team development program for a women's swimming and diving team in a NCAA division I university setting
No full textThis dissertation reflects a case study of the process of the design, implementation and formative evaluation of a team development program conducted with a swimming and diving team consisting of twenty-three women at a NCAA Division I university during the 2008-2009 academic year. The dissertation was undertaken to contribute to the knowledge base about how team development programs can be designed and implemented in athletic settings. As a foundation for the dissertation, the participant observer role was used in conjunction with Maher's (2000) Program Planning and Evaluation (PP&E) Framework and Maher's (2004) Student-Athlete Pyramid of Development. Relying on these approaches as procedural and technical guidance, a framework of knowledge, skills and abilities was formulated and then put into an evaluable programmatic form to assist the student-athletes on the team with interpersonal communication, within the team context. This dissertation explores how the PP&E Framework can be coupled with some of the levels of the Student-Athlete Pyramid of Development along with knowledge about team development from business, military, and sport to assist an athletic team in learning to communicate constructively. Formative evaluation data is provided from participating team members and the coaching staff about the actual and potential value of this kind of program. Finally, conclusions and recommendations are offered for the possible design and implementation of similar team development programs in athletic, business, and other contexts.Psy.DIncludes bibliographical references (p. 119-126)by Robyn L. OdegaardIncludes abstrac
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