Thermal Stress on Intertidal Limpets: Long-Term Hindcasts and Lethal Limits

When coupled with long-term meteorological records, a heat-budget model for the limpet, Lottia gigantea, provides a wealth of information regarding environmental and topographic controls of body temperature in this ecologically important species. (1) The maximum body temperature predicted for any site (37.5°C) is insufficient to kill all limpets, suggesting that acute thermal stress does not set an absolute upper limit to the elevation of L. gigantea on the shore. Therefore, the upper limit must be set by behavioral responses, sublethal effects or ecological interactions. (2) Temperatures sufficient to kill limpets are reached at only a small fraction of substratum orientations and elevations and on only three occasions in 5 years. These rare predicted lethal temperatures could easily be missed in field measurements, thereby influencing the interpretation of thermal stress. (3) Body temperature is typically higher than air temperature, but maximum air temperature can nonetheless be used as an accurate predictor of maximum body temperature. Warmer air temperatures in the future may thus cause increased mortality in this intertidal species. Interpretation of the ecological effects of elevated body temperature depends strongly on laboratory measurements of thermal stress, highlighting the need for additional research on the temporal and spatial variability of thermal limits and sublethal stress. The lengthy time series of body temperatures calculated from the heat-budget model provides insight into how these physiological measurements should be conducted

The Affording Mars Workshop: Background and Recommendations

A human mission to Mars is the stated "ultimate" goal for NASA and is widely believed by the public to be the most compelling destination for America's space program. However, widely cited enormous costs - perhaps as much as a trillion dollars for a many-decade campaign - seem to be an impossible hurdle, although political and budget instability over many years may be equally challenging. More recently, a handful of increasingly detailed architectures for initial Mars missions have been developed by commercial companies that have estimated costs much less than widely believed and roughly comparable with previous major human space flight programs: the Apollo Program, the International Space Station, and the space shuttle. Several of these studies are listed in the bibliography to the workshop report. As a consequence of these new scenarios, beginning in spring, 2013 a multiinstitutional planning team began developing the content and invitee list for a winter workshop that would critically assess concepts, initiatives, technology priorities, and programmatic options to reduce significantly the costs of human exploration of Mars. The output of the workshop - findings and recommendations - would be presented in a number of forums and discussed with national leaders in human space flight. It would also be made available to potential international partners. This workshop was planned from the start to be the first in a series. Subsequent meetings, conferences, and symposia will concentrate on topics not able to be covered in December. In addition, to make progress in short meeting, a handful of ground rules were adopted by the planning team and agreed to by the participants. Perhaps the two most notable such ground rules were (1) the Space Launch System (SLS) and Orion would be available during the time frame considered by the participants and (2) the International Space Station (ISS) would remain the early linchpin in preparing for Mars exploration over the coming decade. The workshop was organized around three topical breakout sessions: 1. The ISS and the path to Mars: The critical coming decade 2. Affordability and sustainability: what does it mean and what are its implications within guidelines established at the start of the workshop? 3. Notional sequence(s) of cost-achievable missions for the 2020s to 2030s, including capability objectives at each stage and opportunities for coordinated robotic partnerships

Amino acid changes in the spike protein of feline coronavirus correlate with systemic spread of virus from the intestine and not with feline infectious peritonitis

Recent evidence suggests that a mutation in the spike protein gene of feline coronavirus (FCoV), which results in an amino acid change from methionine to leucine at position 1058, may be associated with feline infectious peritonitis (FIP). Tissue and faecal samples collected post mortem from cats diagnosed with or without FIP were subjected to RNA extraction and quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) to detect FCoV RNA. In cats with FIP, 95% of tissue, and 81% of faecal samples were PCR-positive, as opposed to 22% of tissue, and 60% of faecal samples in cats without FIP. Relative FCoV copy numbers were significantly higher in the cats with FIP, both in tissues (P < 0.001) and faeces (P = 0.02). PCR-positive samples underwent pyrosequencing encompassing position 1058 of the FCoV spike protein. This identified a methionine codon at position 1058, consistent with the shedding of an enteric form of FCoV, in 77% of the faecal samples from cats with FIP, and in 100% of the samples from cats without FIP. In contrast, 91% of the tissue samples from cats with FIP and 89% from cats without FIP had a leucine codon at position 1058, consistent with a systemic form of FCoV. These results suggest that the methionine to leucine substitution at position 1058 in the FCoV spike protein is indicative of systemic spread of FCoV from the intestine, rather than a virus with the potential to cause FIP

Multiscale modeling in granular flow

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 245-254).Granular materials are common in everyday experience, but have long-resisted a complete theoretical description. Here, we consider the regime of slow, dense granular flow, for which there is no general model, representing a considerable hurdle to industry, where grains and powders must frequently be manipulated. Much of the complexity of modeling granular materials stems from the discreteness of the constituent particles, and a key theme of this work has been the connection of the microscopic particle motion to a bulk continuum description. This led to development of the "spot model", which provides a microscopic mechanism for particle rearrangement in dense granular flow, by breaking down the motion into correlated group displacements on a mesoscopic length scale. The spot model can be used as the basis of a multiscale simulation technique which can accurately reproduce the flow in a large-scale discrete element simulation of granular drainage, at a fraction of the computational cost. In addition, the simulation can also successfully track microscopic packing signatures, making it one of the first models of a flowing random packing. To extend to situations other than drainage ultimately requires a treatment of material properties, such as stress and strain-rate, but these quantities are difficult to define in a granular packing, due to strong heterogeneities at the level of a single particle. However, they can be successfully interpreted at the mesoscopic spot scale, and this information can be used to directly test some commonly-used hypotheses in modeling granular materials, providing insight into formulating a general theory.by Christopher Harley Rycroft.Ph.D

“My Autism is Linked with Everything”: at the Crossroads of Autism and Diabetes

Autistic adults experience stark health disparities and difficulties accessing health care. Their realities of managing complex health conditions are unknown. Our research explored the experience of Autistic adults self-managing diabetes. Interviews with Autistic adults with diabetes and their support people were thematically analysed to identify three key themes. The Autistic experience influenced diabetes self-management, including autism-unique challenges and strengths. Participants prioritised avoiding Autistic burnout over diabetes self-management; mitigating the psychosocial pressures of neurotypical systems took precedence. Health professionals often separated autism and diabetes subsequently overlooking key factors impacting diabetes self-management. To better meet the needs of Autistic adults, diabetes care and health management more broadly should be considered within the context of autism, including supports for self-management during Autistic burnout

Aerodynamic performance of low form factor spoilers

The development of low form factor flight controls is driven by the benefits of reducing the installed volume of the control device and/or minimising the change in external geometry, with particular application to flight control of low observable aircraft. For this work, the term "low form factor" does not refer to the aspect ratio of the control device rather the overall installed volume. This thesis compares the use of low form factor geometric and fluid devices on a NACA 0015 aerofoil section through two-dimensional numerical analysis and low speed wind tunnel experiments. The geometric spoiler is implemented as a small (boundary layer scale) variable height tab oriented normal to the local surface, referred to as a Micro Geometric Spoiler (MiGS). The fluidic spoiler is implemented as an air jet tangential to the local surface acting in the forward direction, referred to as a Counter-Flow Fluidic Spoiler (CFFS). Two chordwise spoiler locations were considered: 0.35c and 0.65c. Numerical analysis was undertaken using a commercial CFD code using an unsteady solver and k-omega shear-stress-transport turbulence model. Experimental forces and moments were measured via an overhead force balance, integrated surface pressures and pressure wake survey. Device performance is assessed against the magnitude of control achievable compared to macro scale spoilers and trailing edge controls (effectiveness), the ratio of aerodynamic output to control input (efficiency or gain), the shape of control response curve (linearity), and the degree of control cross coupling. Results show that the MiG and CFF spoilers work by a similar mechanism based on inducing flow separation that increases the pressure ahead of the spoiler and reduces the pressure downstream. Increasing control input increases drag and reduces lift, however the change in pitching moment is dependent on chordwise location. Chordwise location has a significant effect on effectiveness, efficiency, linearity and separability. Forward MiGS location gives the largest drag gain however the control response is strongly nonlinear with angle of attack and there is a significant undesirable coupling of drag with pitching moment. Aft MiGS location significantly improves control linearity and reduces pitching moment coupling however the drag gain is much reduced. For the CFFS, the control linearity with respect to control input and angle of attack is good for both forward and aft locations, with the aft location giving the largest gain for lift and drag. The control response trends predicted from numerical analysis are good, however a calibration factor of around ½ has to be applied to the control input momentum to match the experimentally observed gains. Furthermore numerical control drag polars under predict the change in lift with change in drag at low blowing rates. Through the use of a CFFS device on both the upper and lower surfaces of a wing section it is possible to generate control drag inputs fully decoupled from both lift and pitching moment, thus potentially simplifying device control law implementation within an integrated yaw control system.EThOS - Electronic Theses Online ServiceBAE SystemsGBUnited Kingdo