The Remarriage of Elite Widows in the Later Middle Ages

Although late medieval widows had considerable legal control over their own remarriages, in practice their freedom was limited by the constraints of family social strategies and, for the highly placed, by political manipulation by powerful men. Similar factors operated in many countries. The wealth and prestige which gave these women consequence also attracted men who wished to use those assets. This can be found at all levels of property and status, from widowed queens pressured by those seeking power, to widows on the margins of the aristocracy, who could be required to remarry to suit a patron. The freedom of widows to choose was almost always contingent on the greater social and political power of men. The article concludes with a case study of Maud Stanhope, Lady Willoughby

Numerical modeling of gravity-driven sediment transport and deposition on an energetic continental shelf: Eel River, northern California

A two-dimensional numerical model was applied to predict large-scale deposition by wave-supported sediment gravity flows on the Eel River continental shelf for four consecutive flood seasons using measured bathymetry, waves and river forcing. The model assumes that sediment-induced stratification maintains the near-bed Richardson number at its critical value, which determines the sediment carrying capacity of the wave boundary layer. Deposition is predicted when the gravity-driven flux of sediment exceeds the carrying capacity. The model predicted 26% of fine sediment discharged by the Eel River to be deposited on the midshelf with a magnitude and distribution largely consistent with field observations. Greatest deposition on the midshelf was predicted well north of the river mouth despite greater sediment input nearest the river mouth. Model results indicate that when the river delivers sufficient sediment to critically stratify the wave boundary layer, wave intensity and the bathymetry of the Eel shelf are the dominant factors controlling the observed pattern of deposition. Large wave energy caused the majority of fine sediment (65%) to escape the shelf as gravity-driven flows. The greatest amount of sediment was predicted to leave the shelf from the region off-shelf of the river mouth (including 11% into the Eel Canyon) where inshore sediment input was high and the concave downward bathymetry associated with the Eel River subaqueous delta prevents significant midshelf gravity-driven deposition

Controls on Sediment Bed Erodibility in a Muddy, Partially-Mixed Tidal Estuary

he objectives of this study are to better understand controls on bed erodibility in muddy estuaries, including the roles of both sediment properties and recent hydrodynamic history. An extensive data set of erodibility measurements, sediment properties, and hydrodynamic information was utilized to create statistical models to predict the erodibility of the sediment bed. This data set includes \u3e160 eroded mass versus applied stress profiles collected over 15 years along the York River estuary, a system characterized by “depth-limited erosion,” such that the critical stress for erosion increases rapidly with depth into the bed. For this study, erodibility was quantified in two ways: the mass of sediment eroded at 0.2 Pa (a stress commonly produced by tides in the York), and the normalized shape of the eroded mass profile for stresses between 0 and 0.56 Pa. In models with eroded mass as the response variable, the explanatory variables with the strongest influence were (in descending order) tidal range squared averaged over the previous 8 days (a proxy for recent bottom stress), salinity or past river discharge, sediment organic content, recent water level anomalies, percent sand, percent clay, and bed layering. Results support the roles of 1) recent deposition and bed disturbance increasing erodibility and 2) cohesion/consolidation and erosion/winnowing of fines decreasing erodibility. The most important variable influencing the shape of the eroded mass profile was eroded mass at 0.2 Pa, such that more (vs. less) erodible cases exhibited straighter (vs. more strongly curved) profiles. Overall, hydrodynamic variables were the best predictors of eroded mass at 0.2 Pa, which, in turn, was the best predictor of profile shape. This suggests that calculations of past bed stress and the position of the salt intrusion can serve as useful empirical proxies for muddy bed consolidation state and resulting erodibility of the uppermost seabed in estuarine numerical models. Observed water content averaged over the top 1 cm was a poor predictor of erodibility, likely because typical tidal stresses suspend less than 1 mm of bed sediment. Future field sampling would benefit from higher resolution observations of water content within the bed’s top few millimeters

Symmetric hyperbolic systems for Bianchi equations

We obtain a family of first-order symmetric hyperbolic systems for the Bianchi equations. They have only physical characteristics: the light cone and timelike hypersurfaces. In the proof of the hyperbolicity, new positivity properties of the Bel tensor are used.Comment: latex, 7 pages, accepted for publication in Class. Quantum Gra

Spring-neap variation in fecal pellet properties within surficial sediment of the York River stuary, Virginia

Fecal pellet abundance was measured within the upper seabed of the York River Estuary as part of a larger study investigating relationships between fine sediment aggregates and bed erodibility. Sedimentalogical surveys were conducted twice a month during the spring and summer of 2011 to coincide with spring or neap tidal cycles. Particle size distributions were determined by sieving the sediment using three methods: 1) typical grain size analysis, 2) gentle agitation with seawater, 3) gentle agitation with deionized water. Each method used four sieves (150, 90, 63 and 45 microns) to constrain the size abundance of the particles. The study found that resilient fecal pellets comprised up to ~30% of the total sediment within the top centimeter of the seabed, and abundance was not directly related to spring-neap tidal cycles. There was a tendency, however, for larger pellets to persist around neap tide, perhaps because stronger currents at spring tide were more likely to break apart the largest pellets. Also, a greater mass of pellets was preserved when seawater rather than deionized water was used during sieving

On the Theory of Superfluidity in Two Dimensions

The superfluid phase transition of the general vortex gas, in which the circulations may be any non-zero integer, is studied. When the net circulation of the system is not zero the absence of a superfluid phase is shown. When the net circulation of the vortices vanishes, the presence of off-diagonal long range order is demonstrated and the existence of an order parameter is proposed. The transition temperature for the general vortex gas is shown to be the Kosterlitz---Thouless temperature. An upper bound for the average vortex number density is established for the general vortex gas and an exact expression is derived for the Kosterlitz---Thouless ensemble.Comment: 22 pages, one figure, written in plain TeX, published in J. Phys. A24 (1991) 502