Quadratic autocatalysis in an extended continuous-flow stirred tank reactor (ECSTR)

The continuous-flow stirred tank reactor (CSTR) is a standard tool used to investigate the behaviour of chemical processes subject to nonlinear kinetics. A recently proposed variation of the CSTR is the extended continuous-flow stirred tank reactor (ECSTR). This consists of a standard CSTR attached to an environmental tank reactor with mass transfer occurring between them through a membrane. The attraction of studying a reaction scheme in an ECSTR, rather than a CSTR, is that this offers the possibility of modifying the behaviour with a larger parameter dimension. We investigate how the behaviour of a standard non-linear chemical mechanism, quadratic autocatalysis subject to linear decay, changes when it is studied in an ECSTR rather than a CSTR

Computational Efficiency: A Common Organizing Principle for Parallel Computer Maps and Brain Maps?

It is well-known that neural responses in particular brain regions are spatially organized, but no general principles have been developed that relate the structure of a brain map to the nature of the associated computation. On parallel computers, maps of a sort quite similar to brain maps arise when a computation is distributed across multiple processors. In this paper we will discuss the relationship between maps and computations on these computers and suggest how similar considerations might also apply to maps in the brain

Omnidirectional Sensory and Motor Volumes in Electric Fish

Active sensing organisms, such as bats, dolphins, and weakly electric fish, generate a 3-D space for active sensation by emitting self-generated energy into the environment. For a weakly electric fish, we demonstrate that the electrosensory space for prey detection has an unusual, omnidirectional shape. We compare this sensory volume with the animal's motor volume—the volume swept out by the body over selected time intervals and over the time it takes to come to a stop from typical hunting velocities. We find that the motor volume has a similar omnidirectional shape, which can be attributed to the fish's backward-swimming capabilities and body dynamics. We assessed the electrosensory space for prey detection by analyzing simulated changes in spiking activity of primary electrosensory afferents during empirically measured and synthetic prey capture trials. The animal's motor volume was reconstructed from video recordings of body motion during prey capture behavior. Our results suggest that in weakly electric fish, there is a close connection between the shape of the sensory and motor volumes. We consider three general spatial relationships between 3-D sensory and motor volumes in active and passive-sensing animals, and we examine hypotheses about these relationships in the context of the volumes we quantify for weakly electric fish. We propose that the ratio of the sensory volume to the motor volume provides insight into behavioral control strategies across all animals

Age-Friendly Cities and Older Indigenous People: An Exploratory Study in Prince George, Canada

Cities around the world are responding to aging populations and equity concerns for older people by developing age-friendly communities plans, following the World Health Organization’s guidelines. Such plans, however, often fail to account for the wide diversity of older people in cities, with the result that some older people, including Indigenous older people, do not see their needs reflected in age-friendly planning and policies. This article reports on a study involving 10 older First Nations and Métis women in the city of Prince George, Canada, comparing the expressed needs of these women with two age-friendly action plans: that of the city of Prince George, and that of the Northern Health Authority. Four main categories were raised in a group discussion and interview with these women at the Prince George Native Friendship Centre: availability of health care services, accessibility and affordability of programs and services, special roles of Indigenous Elders, and experiences of racism and discrimination. There are many areas of synergy between the needs expressed by the women and the two action plans; however, certain key areas are missing from the action plans; in particular, specific strategies for attending to the needs of Indigenous and other older populations who often feel marginalized in health care and in age-friendly planning

HCI for peace: from idealism to concrete steps

This panel will contribute diverse perspectives on the use of computer technology to promote peace and prevent armed conflict. These perspectives include: the use of social media to promote democracy and citizen participation, the role of computers in helping people communicate across division lines in zones of conflict, how persuasive technology can promote peace, and how interaction design can play a role in post-conflict reconciliation

An analysis of calving season strategies

Call number: LD2668 .T4 1986 N44Master of ScienceAgricultural Economic

Electronic properties of disclinated flexible membrane beyond the inextensional limit: Application to graphene

Gauge-theory approach to describe Dirac fermions on a disclinated flexible membrane beyond the inextensional limit is formulated. The elastic membrane is considered as an embedding of 2D surface into R^3. The disclination is incorporated through an SO(2) gauge vortex located at the origin, which results in a metric with a conical singularity. A smoothing of the conical singularity is accounted for by replacing a disclinated rigid plane membrane with a hyperboloid of near-zero curvature pierced at the tip by the SO(2) vortex. The embedding parameters are chosen to match the solution to the von Karman equations. A homogeneous part of that solution is shown to stabilize the theory. The modification of the Landau states and density of electronic states of the graphene membrane due to elasticity is discussed.Comment: 15 pages, Journal of Physics:Condensed Matter in pres

Potential of Trichoderma sp. for inhibition of Botrytis cinerea and Sclerotinia sclerotiorum on snap beans

Isolates of Trichoderma spp. collected from snap bean foliage were tested for inhibition of grey mold of snap beans caused by Botrytis cinerea. In a detached blossom-pod assay an isolate of Trichoderma hamatum reduced pod rot by 94% compared to the nontreated check. Control was comparable to that obtained with the fungicide vinclozolin. As few as 42 colony forming units (CFU) of T. hamatum per blossom reduced pod rot by 77% compared to the nontreated check. Control was 97% when 233 CFU per blossom were applied. Grey mold was reduced only when spores of T. hamatum were applied to blossoms prior to, or at the same time as, conidia of B. cinerea. In field studies conditions were very warm and dry. Because B. cinerea is primarily a cool weather pathogen, grey mold incidence was too low to detect meaningful differences among treatments. Differences in the incidence of pod rot caused by Sclerotinia sclerotiorum, however, were observed among treatments in these field trials. Control of white mold by T. hamatum was comparable to that obtained with the fungicide vinclozolin. Populations of Trichoderma spp. on foliage rapidly decreased following application of a T. hamatum spore suspension but remained higher in treated plots than in nontreated plots up to two weeks following application. The isolate of T. hamatum used in these trials produces volatile compounds which in vitro inhibits the growth of B. cinerea and S. sclerotiorum. Mean radial growth of B. cinerea in a closed chamber with a T. hamatum colony was 0.6 mm compared to 23.6 mm when enclosed with noninoculated potato dextrose agar (PDA). Mean radial growth of S. sclerotiorum was 0.8 mm when enclosed with a T. hamatum colony compared to 32.3 mm when enclosed with noninoculated PDA

Influence of coral and algal exudates on microbially mediated reef metabolism.

Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant benthic primary producers (calcifying and non-calcifying macroalgae, turf-algae and corals) on reefs of Mo'orea French Polynesia. Subsequently, we examined planktonic and benthic microbial community response to these dissolved exudates by measuring bacterial growth rates and oxygen and DOC fluxes in dark and daylight incubation experiments. All benthic primary producers exuded significant quantities of DOC (roughly 10% of their daily fixed carbon) into the surrounding water over a diurnal cycle. The microbial community responses were dependent upon the source of the exudates and whether the inoculum of microbes included planktonic or planktonic plus benthic communities. The planktonic and benthic microbial communities in the unamended control treatments exhibited opposing influences on DO concentration where respiration dominated in treatments comprised solely of plankton and autotrophy dominated in treatments with benthic plus plankon microbial communities. Coral exudates (and associated inorganic nutrients) caused a shift towards a net autotrophic microbial metabolism by increasing the net production of oxygen by the benthic and decreasing the net consumption of oxygen by the planktonic microbial community. In contrast, the addition of algal exudates decreased the net primary production by the benthic communities and increased the net consumption of oxygen by the planktonic microbial community thereby resulting in a shift towards net heterotrophic community metabolism. When scaled up to the reef habitat, exudate-induced effects on microbial respiration did not outweigh the high oxygen production rates of benthic algae, such that reef areas dominated with benthic primary producers were always estimated to be net autotrophic. However, estimates of microbial consumption of DOC at the reef scale surpassed the DOC exudation rates suggesting net consumption of DOC at the reef-scale. In situ mesocosm experiments using custom-made benthic chambers placed over different types of benthic communities exhibited identical trends to those found in incubation experiments. Here we provide the first comprehensive dataset examining direct primary producer-induced, and indirect microbially mediated alterations of elemental cycling in both benthic and planktonic reef environments over diurnal cycles. Our results highlight the variability of the influence of different benthic primary producers on microbial metabolism in reef ecosystems and the potential implications for energy transfer to higher trophic levels during shifts from coral to algal dominance on reefs

Laboratory kinetic studies of OH and CO2 relevant to upper atmospheric radiation balance

During the first year of this program, we have made considerable progress toward the measurement of the dipole moments of vibrationally excited OH radicals. Our primary accomplishments have been 1) the modification of the original slit jet spectrometer for the study of radical species and 2) the observation of infrared chemiluminescence from the vibrationally excited OH radicals formed in the H + ozone reaction in the supersonic jet. We are optimistic that we will soon observe OH* laser induced fluorescence in the jet. Modulation of this fluorescence with microwave radiation in an applied electric field will be the final step required for the precise determination of the vibrational dependence of the OH dipole moment