Human well-being and causality in social epidemiology

This paper discusses the work of Ballas and Dorling on life events and happiness. I believe epidemiologists have things they could learn from economists (and vice versa). Here I emphasize the issue of how to establish causality, and try to suggest some ways forward

High Density Mesoscopic Atom Clouds in a Holographic Atom Trap

We demonstrate the production of micron-sized high density atom clouds of interest for meso- scopic quantum information processing. We evaporate atoms from 60 microK, 3x10^14 atoms/cm^3 samples contained in a highly anisotropic optical lattice formed by interfering di racted beams from a holographic phase plate. After evaporating to 1 microK by lowering the con ning potential, in less than a second the atom density reduces to 8x10^13 cm^- 3 at a phase space density approaching unity. Adiabatic recompression of the atoms then increases the density to levels in excess of 1x10^15 cm^-3. The resulting clouds are typically 8 microns in the longest dimension. Such samples are small enough to enable mesoscopic quantum manipulation using Rydberg blockade and have the high densities required to investigate new collision phenomena.Comment: 4 pages, 4 figures, submitted to PR

Spinning Particles, Braid Groups and Solitons

We develop general techniques for computing the fundamental group of the configuration space of $n$ identical particles, possessing a generic internal structure, moving on a manifold $M$. This group generalizes the $n$-string braid group of $M$ which is the relevant object for structureless particles. In particular, we compute these generalized braid groups for particles with an internal spin degree of freedom on an arbitrary $M$. A study of their unitary representations allows us to determine the available spectrum of spin and statistics on $M$ in a certain class of quantum theories. One interesting result is that half-integral spin quantizations are obtained on certain manifolds having an obstruction to an ordinary spin structure. We also compare our results to corresponding ones for topological solitons in $O(d+1)$-invariant nonlinear sigma models in $(d+1)$-dimensions, generalizing recent studies in two spatial dimensions. Finally, we prove that there exists a general scalar quantum theory yielding half-integral spin for particles (or $O(d+1)$ solitons) on a closed, orientable manifold $M$ if and only if $M$ possesses a ${\rm spin}_c$ structure.Comment: harvmac, 34 pages, HUTP-93/A037; UICHEP-TH/93-18; BUHEP-93-2

Decentralisation: a multidisciplinary perspective

Contains fulltext : 236508.pdf (Publisher’s version ) (Open Access

Decentralisation in the blockchain space

Contains fulltext : 233930.pdf (Publisher’s version ) (Open Access)25 november 202

Examination of Sea Ice Cover in Norwegian Fjords

Presented are two steps being taken to examine sea ice coverage in Norwegian fjords as part of a larger study to improve our understanding of ice formation and breakup processes in these regions and implications for oil spill response. First, working with Google Earth Engine, MODIS images will be analyzed to determine where and when seasonal ice formation occurred along the Norwegian coastline since 2000. Here we summarize a simple method developed to quantify ice area in these regions to examine trends through the ice season and between years. While the larger study will cover a number of fjords, as an example focus is placed on Efjord, located in Nordland county, which has experienced large variations in ice coverage between years. We discuss the use of other datasets to determine the causes of such fluctuations focusing on the close relationship between run-off and ice cover in Efjord. Second, measurements of water temperature and salinity and ice thickness, stratigraphy, and salinity will be gathered over a three year period to better understand the ice observed in the MODIS images. The first set of measurements collected in November 2017 before freeze up are discussed below. In addition, initial images collected from time lapse cameras positioned to observe general weather and ocean conditions and the initial freeze up of ice are presented.submittedVersio

Comparison of two indexed gill-netting protocols for fish community surveys in Northern lakes

1) I compared the performance of two standard fish community assessment protocols, the NORDIC protocol and the Broad-scale Fish Community Monitoring (BsM) protocol (the latter consisting of two gear types). I utilized fish catch and attribute data collected from 21 Boreal Shield lakes (17 in Ontario, 4 in NWT) surveyed using both protocols, in a pairwise design. Fish community composition (species richness, diversity, and evenness), relative abundance (number and biomass per 100 m of net), and body size distributions were compared between NORDIC and BsM surveys, and among the three gill net gears - NORDIC (NRD), North American Standard (NA1), and Ontario Small Mesh Standard (ON2). The NORDIC protocol dedicates a higher proportion of total sampling effort to small-mesh gear compared to the BsM protocol, and the ranking of gears according to proportion of small mesh effort is ON2 > NRD > NA1. NORDIC surveys used 38% greater effort (total length of net deployed per area of lake) than BsM surveys over the 21 lakes examined. 2) Principal components analysis (PCA) of species relative abundances showed significant differences between surveys in community compositions, as well as a separation of communities between Ontario and NWT lakes. NORDIC surveys detected 19% more species per survey, with the additional species primarily belonging to smallbodied taxa (e.g., Cyprinidae, Gasterosteidae, Cottidae). Paired-comparisons of gears indicated that NA1 gangs (highest proportion of large mesh) yielded fewer species, lower diversity, and higher evenness at standardized levels of effort compared to NRD and ON2 gangs, but there were no significant differences between NRD and ON2 gangs. 3) NORDIC surveys tended to provide higher numeric catch per unit effort (NPUE) and lower biomass per unit effort (BPUE) estimates compared to BsM surveys for the whole community, but differences between surveys were stronger and more consistent for smallbodied species than large-bodied species. For most small-bodied species, both NPUE and BPUE were significantly higher in NORDIC than BsM surveys. In gear comparisons, differences generally followed mesh size compositions for both NPUE and BPUE; NA1 gear tended to provide higher estimates for large-bodied species, and lower estimates for small-bodied species compared to NRD and ON2 gears. NRD and ON2 gear provided comparable NPUE and BPUE estimates for small-bodied species, but NRD gear tended to provide higher estimates for large-bodied species. 4) Biomass size distributions of all captured fish differed significantly between surveys in most Ontario lakes, but not in most NWT lakes. Significant differences between the surveys were more consistent across lakes for large-bodied piscivores than for other taxa. Size distributions from NORDIC surveys generally had lower medians and higher CVs than distributions from BsM surveys. Both NRD and ON2 gears yielded size distributions that tended to be more multi-modal than distributions from NA1 gear. In gear comparisons, size distribution medians were NA1 > NRD > ON2, whereas size distribution CVs were NRD=ON2 > NA1. 5) Differences in fish community metrics between the surveys were not related to the physical characteristics of the survey lakes (area, depth, water clarity), with the exception that BPUE differences were weakly but significantly related to lake maximum depth. Differences between surveys appeared to be less distinct in NWT lakes than in Ontario lakes, presumably due to differences in fish community composition between regions. 6) Overall, BsM surveys tended to under-represent small-bodied fish and over-represent large-bodied fish relative to NORDIC surveys. Differences between survey results could likely be reduced by increasing the total sampling effort, and/or the relative amount of ON2 effort in BsM surveys.Master of Science (M.Sc.) in Biolog