Continental Runoff and Effects on the North Atlantic Ocean Subtropical Mode Water

Interannual salinity variations in North Atlantic Subtropical Mode Water (STMW) are well known although the cause is less well understood. Attempts to model local salinity variation with local evaporation and precipitation have not been successful and some authors invoke advection of low salinity water as the cause. Examination of the STMW and North American river runoff data suggests that runoff may partly explain the salinity variations. It is known that low salinity water resulting from Mississippi River outflow is transported well past Cape Hatteras. Spearman Rank Correlation analysis and spectra and cross-spectra Fourier correlation analysis both show that river flow is significantly inversely correlated with STMW salinity. This result suggests that North American river flow may have an influence on the salinity of STMW

Large-wavelength instabilities in free-surface Hartmann flow at low magnetic Prandtl numbers

We study the linear stability of the flow of a viscous electrically conducting capillary fluid on a planar fixed plate in the presence of gravity and a uniform magnetic field. We first confirm that the Squire transformation for MHD is compatible with the stress and insulating boundary conditions at the free surface, but argue that unless the flow is driven at fixed Galilei and capillary numbers, the critical mode is not necessarily two-dimensional. We then investigate numerically how a flow-normal magnetic field, and the associated Hartmann steady state, affect the soft and hard instability modes of free surface flow, working in the low magnetic Prandtl number regime of laboratory fluids. Because it is a critical layer instability, the hard mode is found to exhibit similar behaviour to the even unstable mode in channel Hartmann flow, in terms of both the weak influence of Pm on its neutral stability curve, and the dependence of its critical Reynolds number Re_c on the Hartmann number Ha. In contrast, the structure of the soft mode's growth rate contours in the (Re, alpha) plane, where alpha is the wavenumber, differs markedly between problems with small, but nonzero, Pm, and their counterparts in the inductionless limit. As derived from large wavelength approximations, and confirmed numerically, the soft mode's critical Reynolds number grows exponentially with Ha in inductionless problems. However, when Pm is nonzero the Lorentz force originating from the steady state current leads to a modification of Re_c(Ha) to either a sublinearly increasing, or decreasing function of Ha, respectively for problems with insulating and conducting walls. In the former, we also observe pairs of Alfven waves, the upstream propagating wave undergoing an instability at large Alfven numbers.Comment: 58 pages, 16 figure

Net Energy of Finishing Diets Containing Light or Normal Test Weight Corn

Net energy (NE) of diets containing 77.7% whole corn of either normal (53.8 Ib/bushel, NC) or light (40.8 Ib/bushel, LC) test weight was determined by total collection and indirect respiration calorimetry using six crossbred steers (avg wt 327 kg). Diet treatments were applied in a switchback design. The steers were initially adapted to ad libitum intake of either NC or LC diets for 32 days followed by 7 days total feces and urine collection. Gaseous exchange was subsequently measured for at least 48 hours. Intake was then reduced to an estimated 1.1 times maintenance for 6 days and collections were repeated. The steers were then switched between NC and LC diets and the entire process was repeated. As a percentage of gross energy consumed, fecal energy losses were 32% greater for the NC diet compared to LC (P\u3c .01). Urinary energy losses were unaffected by diet (P \u3e .20). Although energy lost as methane did not differ between diets at high intake, it was 27% greater for LC than NC at low intake (interaction P.20). Partial efficiencies of ME used for maintenance (k,) and gain (k,), as well as ME required for maintenance, also were not different (P\u3e.20). Diet NE for maintenance and gain was 13% greater for LC than NC. NE estimates calculated by difference for light and normal whole corn were 2.48, 1.65, 2.15 and 1.43 mcal/kg dry matter, respectively. These data demonstrate that corn of low test weight is not inherently lower in NE content than normal corn

The Savvidy ``ferromagnetic vacuum'' in three-dimensional lattice gauge theory

The vacuum effective potential of three-dimensional SU(2) lattice gauge theory in an applied color-magnetic field is computed over a wide range of field strengths. The background field is induced by an external current, as in continuum field theory. Scaling and finite volume effects are analyzed systematically. The first evidence from lattice simulations is obtained of the existence of a nontrivial minimum in the effective potential. This supports a ``ferromagnetic'' picture of gluon condensation, proposed by Savvidy on the basis of a one-loop calculation in (3+1)-dimensional QCD.Comment: 9pp (REVTEX manuscript). Postscript figures appende

Rubber friction: role of the flash temperature

When a rubber block is sliding on a hard rough substrate, the substrate asperities will exert time-dependent deformations of the rubber surface resulting in viscoelastic energy dissipation in the rubber, which gives a contribution to the sliding friction. Most surfaces of solids have roughness on many different length scales, and when calculating the friction force it is necessary to include the viscoelastic deformations on all length scales. The energy dissipation will result in local heating of the rubber. Since the viscoelastic properties of rubber-like materials are extremely strongly temperature dependent, it is necessary to include the local temperature increase in the analysis. At very low sliding velocity the temperature increase is negligible because of heat diffusion, but already for velocities of order 0.01 m/s the local heating may be very important. Here I study the influence of the local heating on the rubber friction, and I show that in a typical case the temperature increase results in a decrease in rubber friction with increasing sliding velocity for v > 0.01 m/s. This may result in stick-slip instabilities, and is of crucial importance in many practical applications, e.g., for the tire-road friction, and in particular for ABS-breaking systems.Comment: 22 pages, 27 figure

Mapping musical mobilities: challenging musical nationalism through mobility and migration

Often, music—particularly classical music—has been viewed in some quarters as a product of particular national cultures, with little regard paid to the ways in which mobile phenomena can contribute to its production, whether in the form of mobile people, objects, or concepts. This paper turns to notions of mobility as a means of exploring how musical cultures can be animated. It explores, too, the possibilities of particular forms of “mapping” as a way to retain, but also rethink, the spatial specificity so emphatically signalled in some musical tradition-claiming, while simultaneously avoiding the excessive valorisation of mobility that can characterise many musical careers as endlessly nomadic or socially detached. We begin by discussing the question of music and nationalism in more detail, particularly as it has been conceived of within musicology, ethnomusicology, and nationalism studies. In so doing, we aim to establish a sense of the national framing and fixing through which (classical) music has hitherto been understood in some contexts. This leads naturally onto an attendant discussion of the mobility of music, in which we will outline some of the nascent material on this topic

Oscillatory oblique stagnation-point flow toward a plane wall

Two-dimensional oscillatory oblique stagnation-point flow toward a plane wall is investigated. The problem is a eneralisation of the steady oblique stagnation-point flow examined by previous workers. Far from the wall, the flow is composed of an irrotational orthogonal stagnation-point flow with a time-periodic strength, a simple shear flow of constant vorticity, and a time-periodic uniform stream. An exact solution of the Navier-Stokes equations is sought for which the flow streamfunction depends linearly on the coordinate parallel to the wall. The problem formulation reduces to a coupled pair of partial differential equations in time and one spatial variable. The first equation describes the oscillatory orthogonal stagnation-point flow discussed by previous workers. The second equation, which couples to the first, describes the oblique component of the flow. A description of the flow velocity field, the instantaneous streamlines, and the particle paths is sought through numerical solutions of the governing equations and via asymptotic analysis