Infection with Helicobacter pylori is a major risk factor for the development of gastric cancer, and infection with strains carrying the virulence factor CagA significantly increases this risk. To investigate the mechanisms by which CagA promotes carcinogenesis, we generated transgenic zebrafish expressing CagA ubiquitously or in the anterior intestine. Transgenic...
Na⁺/H⁺ antiporters are ubiquitous membrane proteins that play a central role in the ion homeostasis of cells. In this study, we examined the possible role of Na⁺/H⁺ antiport in Yersinia pestis virulence and found that Y. pestis strains lacking the major Na⁺/H⁺ antiporters, NhaA and NhaB, are completely attenuated in...
The amount and type of carbon (C) in a forest soil reflects the past balance between C accumulation and loss. In an old-growth forest soil, C is thought to be in dynamic equilibrium between accumulations and losses. Disturbance upsets this equilibrium by altering the microclimate, the amount and type of...
From measurements of the energy‐containing scales of turbulence in the ocean thermocline, two new formulations are examined: (1) an inviscid estimate for the viscous dissipation rate of turbulent kinetic energy and (2) a mixing length estimate for the turbulent heat flux. These formulations are tested using coincident measurements of the...
Estimates of heat flux from direct measurements of vertical velocity-temperature
fluctuation correlations have been obtained from vertical profiles
through turbulent patches in the main thermocline. These have been compared
to more indirect flux estimates derived from dissipation rates of turbulent kinetic
energy and temperature variance. Because record lengths are limited...
A low-power (<10 mW), physically small (15.6 cm long × 3.2 cm diameter), lightweight (600 g Cu; alternatively, 200 g Al), robust, and simply calibrated pitot-static tube to measure mean speed and turbulence dissipation (ε ) is described and evaluated. The measurement of speed is derived from differential pressure via...
Internal gravity waves measured under the Arctic pack ice were strikingly different from measurements
at lower latitudes. The total wave energy, integrated over the internal wave frequency band, was lower by
a factor of 0.03-0.07, and the spectral slope at high frequency was nearly -1 in contrast to the -2...
The dissipation of internal wave energy in the turbulent boundary layer under pack ice is determined using a time‐varying boundary layer model with an eddy coefficient closure scheme. The magnitude of the eddy coefficient is determined by the ice drift velocity, which is assumed greater than the rms water velocity...
Certain institutions traditionally have had broad socializing influence over their members, providing templates for identity that comprehend all aspects of life from the existential and moral to the mundanely material. Marketization and detraditionalization undermine that socializing role. This study examines the consequences when, for some members, such an institution loses...
The upper ocean current and temperature fields in the western Weddell Sea were measured from the drifting pack ice at Ice Station Weddell 1 (ISW) and nearby sites using a vertical profiler and an array of moored sensors in January–June 1992. These data document the structure and variability of the...