Non-slice linear combinations of iterated torus knots

In 1976, Rudolph asked whether algebraic knots are linearly independent in the knot concordance group. This paper uses twisted Blanchfield pairings to answer this question in the affirmative for new large families of algebraic knots

Environmental Marine Geoscience 4. Georgia Basin: Seabed Features and Marine Geohazards

A multibeam bathymetric swath-mapping program of the Strait of Georgia has provided a 5-m resolution map of the seabed. Numerous geological features of the basin, some of which are considered geohazards, are clearly defined. During the Olympia interglacial period most of the basin was filled with sediment and then subsequently excavated during the Fraser Glaciation, except for a group of isolated banks; the southern basin was partially filled by the pro-grading Fraser River Delta during the Holocene. Marine geohazards that exist in this seismically active region include, slope stability features, active faults, gas pockmarks, and large migrating sedimentary bedforms. Other features, such as sponge reefs, have developed because of the glacial history and dynamic oceanography of the basin and provide unique and critical habitats to marine species. SUMMAIRE Un programme de levé par balayage bathymétrique a faisceaux multiples dans le détroit de Georgie a permis la production d'une carte du fond marin d'une résolution de 5 m. De nombreux éléments géologiques du bassin y sont clairement définis, dont certains constituent des géorisques clairement définis. Durant la période interglaciaire d'Olympia, la plus grande partie du bassin a été rempli de sédiments, lesquels ont par la suite été excavés durant la glaciation de Fraser, sauf un groupe de bancs isolés; la partie sud du bassin a été partiellement remplie par progradation du delta de la rivière Fraser à l'Holocène. Les géorisques marins de cette région d'activité sismique comprennent certains éléments de stabilité des talus, des failles actives, des cratères d'échappement de gaz, et de grands éléments topographiques sédimentaires migrants. D'autres éléments, comme des récifs de spongiaires se sont développés à cause de l'histoire glaciaire et de la dynamique océanographique du bassin, constituent un habitat essentiel pour des espèces marines

Relative Sea-Level Change in the Northern Strait of Georgia, British Columbia

Twenty-four new radiocarbon dates from isolation basin cores, excavations and natural exposures, and an archeological site, constrain relative sea-level change since the last glaciation in the northern Strait of Georgia, British Columbia. Relative sea level fell rapidly from about 150 m elevation to 45 m elevation from 11 750 to 11 000 BP (13 750 to 13 000 cal BP), then its rate of fall slowed. The initial rapid emergence began soon after the transition from proximal to distal glaciomarine sedimentation, when the glacial front retreated from the Strait of Georgia and the Earth’s surface was unloaded. A sea-level lowstand a few metres below present-day sea level may have occurred in the early Holocene, but sea level was near its present level by 2000 BP. Sea-level change in the northern Strait of Georgia lagged the mid Strait of Georgia, 80 km to the south, by a few hundred years during initial emergence. The lowstand in the northern strait was later and probably shallower than in the mid strait. Isostatic depression inferred from the sea-level observations can be fit with two decaying exponential terms with characteristic decay times of 500 and 2600 years. The faster decay time corresponds to a shallow mantle viscosity of about 1019 Pa s, consistent with previous glacio-isostatic modelling. The present-day crustal uplift rate from the residual isostatic effects of the Cordilleran Ice Sheet is about 0.25 mm/a. Crustal uplift is not expected to significantly ameliorate projected sea-level rise in the mid and northern Strait of Georgia because present-day vertical crustal movements are inferred to be small.Vingt-quatre nouvelles dates au 14C provenant de carottes sédimentaires de bassins isolés, d’excavations, de coupes naturellement exposées et archéologiques permettent de cerner les changements du niveau marin relatif depuis la dernière glaciation dans la partie nord du détroit de Géorgie, en Colombie-Britannique. Le niveau marin relatif a rapidement passé de 150 m à 45 m d’altitude entre 11 750 et 11 000 ans BP (13 750-13 000 cal. BP), le taux d’abaissement ayant ralenti par la suite. L’émersion initiale rapide correspond à la fin de la sédimentation glaciomarine distale qui accompagnait le retrait du front glaciaire. Un bas niveau de quelques mètres sous le niveau actuel a pu s’instaurer durant l’Holocène inférieur, jusqu’en 2000 ans BP. Au début, le soulèvement isostatique a accusé un retard de quelques siècle sur celui de la zone du détroit à 80 km plus au sud. Le bas niveau de la partie nord du détroit est survenu plus tard et fut moins prononcé. Les données indiquent un enfoncement isostatique de type exponentiel avec des constantes de désintégration de 500 et de 2600 ans 14C. Le taux le plus rapide correspond à une viscosité du manteau terrestre d’environ 1019 Pa s, ce qui concorde avec les résultats de la modélisation glacio-isostatique. Le taux de soulèvement glacio-isostatique actuel résultant de l’inlandsis de la Cordillère s’établit à environ 0,25 mm/a. Ce taux ne peut contrer les effets du rehaussement du niveau marin prévu pour cette région en raison des faibles mouvements de la croûte terrestre qui y sont envisagés

Periostin as a Multifunctional Modulator of the Wound Healing Response

During tissue healing, dynamic and temporal alterations occur in the structure and composition of the extracellular matrix (ECM) that are required for effective repair to occur. Matricellular proteins (MPs) are a group of diverse non-structural ECM components, which bind cell surface receptors mediating interactions between the cell and its microenviroment, effectively regulating adhesion, migration, proliferation, signaling and cell phenotype. Periostin (Postn), a pro-fibrogenic secreted glycoprotein, was defined as a MP based on its expression pattern and regulatory roles during development, healing and in disease processes. Postn consists of a typical signal sequence, an EMI domain responsible for binding to fibronectin, four tandem fasciclin-like domains that are responsible for integrin binding and a C-terminal region where multiple splice variants originate. This review will focus specifically on the role of Postn in wound healing and remodeling, an area of intense research in the last 10 years particularly related to skin healing as well as in myocardium post infarction. Postn interacts with cells through various integrin pairs and is an essential downstream effector of TGF-β superfamily signaling. As will be discussed, across different tissues, Postn is associated with pro-fibrogenic process, specifically, the transition of fibroblasts to myofibroblasts, collagen fibrillogenesis and ECM synthesis. Although the complexity of Postn as a modulator of cell behavior in tissue healing is only beginning to be elucidated, its expression is clearly a defining event in moving wound healing through the proliferative and remodeling phases

Diagnostics of active galaxies: I. Modeling the infrared properties of dusty cores of starburst galaxies

An evolutionary model of star formation in ULIRGs was created using existing star formation and radiative transfer codes (STARBURST99, RADMC and RADICAL) as building blocks. The results of the simulations are compared to data from two IRAS catalogs. From the simulations it is found that the dust surrounding the starburst region is made up from two components. There is a low optical depth (tau=0.1, which corresponds to 0.1% of the total dust mass), hot (T~400K) non-grey component close to the starburst (scale size 10pc) and a large scale, colder grey component (100pc, 75K) with a much larger column (tau=10). The simulations also show that starburst galaxies can be powered by massive star formation. The parameters for this star forming region are difficult to determine, since the IR continuum luminosity is only sensitive to the total UV input. Therefore, there is a degeneracy between the total starburst mass and the initial mass function (IMF) slope. A less massive star formation with a shallower IMF will produce the same amount of OB stars and therefore the same amount of irradiating UV flux. Assuming the stars are formed according to a Salpeter IMF (Psi(M) ~ M^-2.35), the star formation region should produce 10^9 Msun of stars (either in one instantaneous burst, or in a continuous process) in order to produce enough IR radiation.Comment: 37 pages, 32 figures, accepted by Astronomy and Astrophysics. Version with Appendices can be obtained from http://www.astro.rug.nl/~loenen/Loenen_et_al_2006.pd