The Physical Oceanography of the Cape Hatt Region, Eclipse Sound, N.W.T.

In the spring and summer of 1980 and 1981, detailed measurements of water temperature, salinity and depth, currents, tidal height and waves were made in the vicinity of Cape Hatt, at the northern end of Baffin Island, N.W.T., in support of the Baffin Island Oil Spill (BIOS) Project. Currents in the region were generally weak, averaging less than 10 cm/s near the surface and about 2 cm/s in the deeper waters. Deep circulation in Ragged Channel, on the western side of Cape Hatt, was usually counterclockwise. On the western side of Cape Hatt, a strong (up to 30 cm/s) northward flowing coastal current existed. It was occasionally reversed by a flood tide or prolonged south winds. Eddies were observed in bays on the western side of Cape Hatt driven by this coastal current. These eddies were clockwise when the flow offshore was northward and counterclockwise when the flow was southward. Evidence was found for an internal M2 tide in Ragged Channel. Some of the variations in the observed currents and density fields were explained with a simple model of this tide. Under-ice density profiles showed a typical well-mixed layer just above freezing temperature that reached to the bottom in the nearshore regions and to about 35 m depth in mid-channel. In the ice-free season, there was a pronounced shallow mixed layer that ranged from 4 to 10 m in depth. Water properties at the bottom of Ragged Channel were essentially unchanged from winter to summer. In the winter, water properties in Z-Lagoon were similar to those in Ragged Channel. In the summer, they showed the result of being cut off from the main body of Eclipse Sound. In Ragged Channel, wave conditions were very mild, not exceeding 20 cm in significant height, while on the eastern side of Cape Hatt, they were worse, up to 1.4 m, but still not severe.Key words: Eclipse Sound, oceanography, currents, tides, internal tides, water temperature, salinity, wavesMots clés: Eclipse Sound, océanographie, courants, marées, marées internes, température de l’eau, salinité, vague

On the Hybrid Extension of CTL and CTL+

The paper studies the expressivity, relative succinctness and complexity of satisfiability for hybrid extensions of the branching-time logics CTL and CTL+ by variables. Previous complexity results show that only fragments with one variable do have elementary complexity. It is shown that H1CTL+ and H1CTL, the hybrid extensions with one variable of CTL+ and CTL, respectively, are expressively equivalent but H1CTL+ is exponentially more succinct than H1CTL. On the other hand, HCTL+, the hybrid extension of CTL with arbitrarily many variables does not capture CTL*, as it even cannot express the simple CTL* property EGFp. The satisfiability problem for H1CTL+ is complete for triply exponential time, this remains true for quite weak fragments and quite strong extensions of the logic

SN1A data and the CMB of Modified Curvature at short and long distances

The SN1a data, although inconclusive, when combined with other observations makes a strong case that our universe is presently dominated by dark energy. We investigate the possibility that large distance modifications of the curvature of the universe would perhaps offer an alternative explanation of the observation. Our calculations indicate that a universe made up of no dark energy but instead, with a modified curvature at large scales, is not scale-invariant, therefore quite likely it is ruled out by the CMB observations. The sensitivity of the CMB spectrum is checked for the whole range of mode modifications of large or short distance physics. The spectrum is robust against modifications of short-distance physics and the UV cutoff when: the initial state is the adiabatic vacuum, and the inflationary background space is de Sitter.Comment: 13 pages, 2 eps figures, typos corrected, references added; to appear in Phys. Rev.

Modeling oscillatory Microtubule--Polymerization

Polymerization of microtubules is ubiquitous in biological cells and under certain conditions it becomes oscillatory in time. Here simple reaction models are analyzed that capture such oscillations as well as the length distribution of microtubules. We assume reaction conditions that are stationary over many oscillation periods, and it is a Hopf bifurcation that leads to a persistent oscillatory microtubule polymerization in these models. Analytical expressions are derived for the threshold of the bifurcation and the oscillation frequency in terms of reaction rates as well as typical trends of their parameter dependence are presented. Both, a catastrophe rate that depends on the density of {\it guanosine triphosphate} (GTP) liganded tubulin dimers and a delay reaction, such as the depolymerization of shrinking microtubules or the decay of oligomers, support oscillations. For a tubulin dimer concentration below the threshold oscillatory microtubule polymerization occurs transiently on the route to a stationary state, as shown by numerical solutions of the model equations. Close to threshold a so--called amplitude equation is derived and it is shown that the bifurcation to microtubule oscillations is supercritical.Comment: 21 pages and 12 figure

Genome-wide Association Study of Periodontal Pathogen Colonization

Pathological shifts of the human microbiome are characteristic of many diseases, including chronic periodontitis. To date, there is limited evidence on host genetic risk loci associated with periodontal pathogen colonization. We conducted a genome-wide association (GWA) study among 1,020 white participants of the Atherosclerosis Risk in Communities Study, whose periodontal diagnosis ranged from healthy to severe chronic periodontitis, and for whom “checkerboard” DNA-DNA hybridization quantification of 8 periodontal pathogens was performed. We examined 3 traits: “high red” and “high orange” bacterial complexes, and “high” Aggregatibacter actinomycetemcomitans (Aa) colonization. Genotyping was performed on the Affymetrix 6.0 platform. Imputation to 2.5 million markers was based on HapMap II-CEU, and a multiple-test correction was applied (genome-wide threshold of p < 5 × 10−8). We detected no genome-wide significant signals. However, 13 loci, including KCNK1, FBXO38, UHRF2, IL33, RUNX2, TRPS1, CAMTA1, and VAMP3, provided suggestive evidence (p < 5 × 10−6) of association. All associations reported for “red” and “orange” complex microbiota, but not for Aa, had the same effect direction in a second sample of 123 African-American participants. None of these polymorphisms was associated with periodontitis diagnosis. Investigations replicating these findings may lead to an improved understanding of the complex nature of host-microbiome interactions that characterizes states of health and disease