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Inspired by the recent realization of a two-dimensional (2-D) chiral fluid as an active monolayer droplet moving atop a 3-D Stokesian fluid, we formulate mathematically its free-boundary dynamics. The surface droplet is described as a general 2-D linear, incompressible and isotropic fluid, having a viscous shear stress, an active chiral driving stress and a Hall stress allowed by the lack of time-reversal symmetry. The droplet interacts with itself through its driven internal mechanics and by driving flows in the underlying 3-D Stokes phase. We pose the dynamics as the solution to a singular integral–differential equation, over the droplet surface, using the mapping from surface stress to surface velocity for the 3-D Stokes equations. Specializing to the case of axisymmetric droplets, exact representations for the chiral surface flow are given in terms of solutions to a singular integral equation, solved using both analytical and numerical techniques. For a disc-shaped monolayer, we additionally employ a semi-analytical solution that hinges on an orthogonal basis of Bessel functions and allows for efficient computation of the monolayer velocity field, which ranges from a nearly solid-body rotation to a unidirectional edge current, depending on the subphase depth and the Saffman–Delbrück length. Except in the near-wall limit, these solutions have divergent surface shear stresses at droplet boundaries, a signature of systems with codimension-one domains embedded in a 3-D medium. We further investigate the effect of a Hall viscosity, which couples radial and transverse surface velocity components, on the dynamics of a closing cavity. Hall stresses are seen to drive inward radial motion, even in the absence of edge tension.
Salmonella is a leading cause of bacterial foodborne illness. We report the collaborative investigative efforts of US and Canadian public health officials during the 2013–2014 international outbreak of multiple Salmonella serotype infections linked to sprouted chia seed powder. The investigation included open-ended interviews of ill persons, traceback, product testing, facility inspections, and trace forward. Ninety-four persons infected with outbreak strains from 16 states and four provinces were identified; 21% were hospitalized and none died. Fifty-four (96%) of 56 persons who consumed chia seed powder, reported 13 different brands that traced back to a single Canadian firm, distributed by four US and eight Canadian companies. Laboratory testing yielded outbreak strains from leftover and intact product. Contaminated product was recalled. Although chia seed powder is a novel outbreak vehicle, sprouted seeds are recognized as an important cause of foodborne illness; firms should follow available guidance to reduce the risk of bacterial contamination during sprouting.
The International Astronomical Union's Commission 51 was established in 1982 as\break “Bioastronomy: Search for Extraterrestrial Life”. As the interests of Commission members expanded to include all aspects of the study of the origin, evolution, and distribution of life in the universe, C51 was renamed simply “Bioastronomy” in 2006. Thus, the term “bioastronomy” became for the Commission essentially synonymous with the NASA-coined term “astrobiology“. Since the latter term has been adopted by many scientific societies around the world with similar interests, under the new Division and Commission structure of the IAU the Commission has been again renamed and is now Commission F-3 “Astrobiology”.
The 2013 multistate outbreaks contributed to the largest annual number of reported US cases of cyclosporiasis since 1997. In this paper we focus on investigations in Texas. We defined an outbreak-associated case as laboratory-confirmed cyclosporiasis in a person with illness onset between 1 June and 31 August 2013, with no history of international travel in the previous 14 days. Epidemiological, environmental, and traceback investigations were conducted. Of the 631 cases reported in the multistate outbreaks, Texas reported the greatest number of cases, 270 (43%). More than 70 clusters were identified in Texas, four of which were further investigated. One restaurant-associated cluster of 25 case-patients was selected for a case-control study. Consumption of cilantro was most strongly associated with illness on meal date-matched analysis (matched odds ratio 19·8, 95% confidence interval 4·0–∞). All case-patients in the other three clusters investigated also ate cilantro. Traceback investigations converged on three suppliers in Puebla, Mexico. Cilantro was the vehicle of infection in the four clusters investigated; the temporal association of these clusters with the large overall increase in cyclosporiasis cases in Texas suggests cilantro was the vehicle of infection for many other cases. However, the paucity of epidemiological and traceback information does not allow for a conclusive determination; moreover, molecular epidemiological tools for cyclosporiasis that could provide more definitive linkage between case clusters are needed.
Division III, with 1126 members, is the third largest of the 12 IAU Divisions, focusing on subject matter related to the physical study of interplanetary dust, comets, minor planets, satellites, planets, planetary systems and astrobiology. Within the Division are very active working groups that are responsible for planetary system and small body nomenclature, as well as a newly created working group on Near Earth Objects which was established order to investigate the requirements for international ground-and/or space-based NEO surveys to characterize 90% of all NEOs with diameters >40m in order to establish a permanent international NEO Early Warning System.
Astrobiology, also known as bioastronomy or exobiology, is the study of the origin, evolution and distribution of life in the Universe. These are subjects which have been of interest to mankind throughout recorded history. Although questions of origins have most frequently invoked divine beings, non-supernatural speculation on these fundamental issues dates back at least to the Ionian school of pre-Socratic Greek philosophers. Anaximander, the successor to Thales, is reported as saying that all living creatures arose from the moist element (water) through the action of the Sun (Freeman, 1966), a prescient insight given current ideas that life as we know it requires water, that radiation acting on inorganic matter can produce the molecular components of life (amino acids, nucleic acids, etc.) and that the Sun is the ultimate energy source for almost all life on Earth. In fact, Anaximander seems to have gone further and suggested that human beings arose from fish-like creatures (presumably a natural result of life having originated in water).
Speculation about life beyond the Earth has also had a long tradition. Although Pythagoras himself is not known to have recorded his teachings, his school (in particular, Philolaus, ca. 400 BCE) is said to have written that the Moon appears Earth-like because it is inhabited with animals and plants (Dreyer, 1953). At roughly the same time the atomist school of Leucippus and Democritus taught that the Universe is infinite and contains innumerable worlds.
Commission 51 met on August 12, 2009. Outgoing President Alan Boss chaired the meeting, and there were several dozen members present, including incoming President William Irvine, incoming Vice President Pascale Ehrenfreund, and outgoing Past President Karen Meech. Commission 51 (C51) was re-authorized for a term of six more years at the 2006 Prague General Assembly of the IAU, and hence comes up for renewal at the 2012 IAU General Assembly in Beijing, China.
Kirtland's Warbler Dendroica kirtlandii breeds in young jack pine Pinus banksiana forests on sandy soils in Michigan's lower peninsula, where there were 502 censused singing males in 1951 and 167 in 1974 and 1987. An ongoing control programme for the Brown-headed Cowbird Molothrus ater, a nest parasite, resulted in immediate and continued improvement in warbler reproductive success which was not, however, matched by an increase in warbler numbers until the 1990s. From three 1,000 ha reserves in the 1960s, currently over 54,000 ha are managed for the warbler. Despite the establishment of managed plantations, over 70% of warblers censused in the past 15 years have occupied habitat created by wildfires. Optimal habitat consists of more than 5,000 trees per hectare in a mosaic of dense patches interspersed with small openings. Nearly 70% of adult and 30% of juvenile warblers departing for the Bahamian wintering grounds return each spring, and the Michigan singing male population increased from 212 (1989) to 397 (1992) as abundant habitat, resulting from a 1980 wildfire, became available at Mack Lake. This suggests that lack of optimal habitat in Michigan has been the species's major problem.
Richard Johnston's article is addressed to an article of mine and to another, co-authored with Haim Gold.2 It is much more relevant to the former than to the latter, despite the fact that Johnston uses the data from the 1974 National Election Survey on which the Irvine and Gold article was based. The purpose of that article was to discover whether, if at all, a cleavage between two groups is sustained by social processes involving members of those groups.
When a panel is composed of residents from three or four of the conventionally defined Canadian regions, the issue of whether or not regionalism still persists in Canada is already to a large extent prejudged. For this reason, and also because I am doubtful of my credentials as either an interpreter or bearer of any particular set of regional values, I propose to address myself to the problem of how one can measure regional effects.
The various subtables of Table i, or some variant of them, must be familiar to every teacher and to every student of Canadian voting behaviour. While most of our history books, and certainly all of our current concerns, focus on cultural differences in Canada, all our voting and party identification data suggest that the primary line of political division is between Roman Catholics and non-Catholics. The leftmost tables in the two rows of Table i indicate that religious differences are approximately three times as strong as ethnic ones, regardless of the index chosen. The percentage difference in Liberal identifiers is 20 across religious categories, but only 6 across the ethnic ones; the phi coefficient is.21 as compared to.06, while Yule's Q is.42 as opposed to.13. Nor is this simply an artifact. The same finding shows up for vote as for party identification, for a linguistic dichotomy as for an ethnicity dichotomy, and for undichotomized as for dichotomized variables. Similarly, the religious dichotomy need not be imposed, but emerges quite freely when similar data are analysed with the aid program. Indeed, one need not depend on using dichotomies at all, though the analysis becomes more complex. In each case, however, the basic generalization holds.