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A mathematical model and laboratory experiments are described that deal with twolayer flow over smallscale bottom topography in relatively shallow, partially stratified estuaries. The mathematical model is based on Boussinesqtype equations, which in an approximate way account for vertical accelerations, and assumes quasisteady flow. The analysis includes the effect of turbulent friction at bottom and sidewalls. In the experiments the positions of the interface, horizontal velocities, and turbulence intensities are measured. An increase in turbulence level downstream of the obstacle is observed, and a fair agreement with predicted leewave amplitudes, wavelengths, and wave damping is obtained.

Mesoscale anticyclonic eddies dominate the sea‐surface height variability in the Caribbean Sea. Although it is well established that these anticyclones are formed near the eastern boundary of the Caribbean Sea, which is demarcated by the Lesser Antilles, the source of their anticyclonic vorticity remains unclear. To gain insight into this source, we analyze the fluxes of vorticity into the Caribbean at its eastern boundary using a high‐resolution numerical model. We find that the anticyclonic vorticity in the eastern Caribbean Sea predominantly originates from regions where intense ocean currents flow close to the Lesser Antilles. More specifically, St. Lucia and Grenada are hotspots for vorticity generation. The local generation rate scales with the amplitude of the volume transport through the passages between these islands. This finding is in contrast with the view that anticyclonic North Brazil Current (NBC) rings in the Atlantic Ocean are the main source of anticyclonic vorticity in the eastern Caribbean Sea. Our analyses reveal that the direct contribution of the vorticity of the NBC rings is of lesser importance than the local generation. However, the collision of upstream NBC rings with the Lesser Antilles increases the volume transport through the passages into the Caribbean Sea, so that their presence indirectly leads to enhanced local production of anticyclonic vorticity. This process is an example of the importance of vorticity generation near topography, which is ubiquitous in the oceans, and expected to be important whenever currents and steep topography meet. The surface variability in the Caribbean Sea is dominated by bodies of water that rotate in clockwise direction, referred to as anticyclonic eddies. These eddies form in the eastern part of the basin westward of the steep topography of the Lesser Antilles island arc. Because it is unclear what the source for their vorticity (i.e., what determines the tendency of the water to rotate) is, we analyze the fluxes of vorticity into the eastern Caribbean Sea. We use a numerical model with a high spatial resolution to show that two thirds of the vorticity flux is generated locally near the topography of the islands. Furthermore, the magnitude of the locally generated vorticity scales with the magnitude of the transport between the islands. In turn, this transport is regulated by the presence of anticyclonic North Brazil Current rings that collide with the Lesser Antilles. This implies that, while the direct contribution of the vorticity influx of the North Brazil Current rings is at most one third of the anticyclonic vorticity flux into the Caribbean Sea, these rings predominantly impact the vorticity influx into the Caribbean indirectly. These results highlight the importance of vorticity generation near topography for the total vorticity budget, which is expected to be important whenever currents and steep topography meet. The vorticity flux into the Caribbean Sea is dominated by the local generation of vorticity near the topography of the Lesser AntillesNorth Brazil Current rings trigger local vorticity generation through increased transport, while their direct vorticity influx is limitedThis high‐resolution model example suggests that vorticity generation near topography can be a significant factor in the global budget The vorticity flux into the Caribbean Sea is dominated by the local generation of vorticity near the topography of the Lesser Antilles North Brazil Current rings trigger local vorticity generation through increased transport, while their direct vorticity influx is limited This high‐resolution model example suggests that vorticity generation near topography can be a significant factor in the global budget

Measurement of NQR line frequency at 77 K have been performed for the following compounds: 1-chloro-2,2-bis-(p-chlorophenyl) ethylene (DDMU), 1,1-dichloro-2,2-bis-(p-chlorophenyl) ethylene (DDE), 1,1-dichloro-2,2-bis-(p-chlorophenyl) ethane (ODD), 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane (DDT). An attempt to assign spectrum lines to particular Cl nuclei in a molecule has been made. Molecular and crystallographic inequivalences occurring in these compounds have been considered. Comparison of the NQR and crystallographic data revealed the influence of phenyl rings conformation on electric charge distribution in the studied molecules.

Sodium, barium and silver chlorates have been subjected to NQR investigations, Measurements of the 35Cl pure quadrupole resonance frequency and relaxation times were carried out in the temperature range from 290 K to temperatures where the NQR signal vanishes.

A mathematical model and laboratory experiments are described that deal with two‐layer flow over small‐scale bottom topography in relatively shallow, (partially) stratified estuaries. The mathematical model is based on Boussinesq‐type equations, which in an approximate way account for vertical accelerations, and assumes quasi‐steady flow. The analysis includes the effect of turbulent friction at bottom and sidewalls. In the experiments the positions of the interface, horizontal velocities, and turbulence intensities are measured. An increase in turbulence level downstream of the obstacle is observed, and a fair agreement with predicted lee‐wave amplitudes, wavelengths, and wave damping is obtained.

The molecular structure of free radicals formed in γ-irradiated monoclinic and orthorhombic single crystals of hydrated testosterone were investigated by EPR spectroscopy. Two different types of radical were observed. In the monoclinic form, the radical arises by the loss of a hydrogen atom from the carbon atom C(2), whereas, in the orthorhombic form, it arises by addition of a hydrogen atom to the oxygen atom O(3). The hyperfine spectrum of the radical formed in the monoclinic single crystal originates from the interaction of the unpaired electron with one α-proton in position 2 and two non equivalent β-protons in position 1. In the orthorhombic single crystal, we observed interaction of the unpaired electron, which is delocalized on the carbons C(3), C(4) and C(5) with one α-proton in position 4 and with four nonequivalent β-protons connected with the carbon atoms C(2) and C(6). The hyperfine tensors of the coupling and the g-tensor of the radicals are given.

The 63Cu and 65Cu NQR transitions in powder samples of cuprous oxide have been investigated from 77 to 500 K and at room temperature after annealing up to 1100 K Significant differences in T1, NQR linewidth Δv, and their temperature dependences were found among the samples prepared in different ways. For C u20 samples obtained in low temperatures (below 380 K), the temperature dependence of T1below 380 K is o f activation character with Ea= 0.07 eV. These results are interpreted in terms of an electron hopping mechanism. Thermal processing of these samples permits to obtain irreversible electronic state and then the spectroscopic parameters are the same as for the samples obtained in high temperatures (above 1320 K).