A study has been made of the transmural fluxes of benzoic, phenylacetic, and pentanoic acids, benzylamine, hexylamine, and D-amphetamine across rat jejunum incubated in vitro. The M to S fluxes of the weak acids were greater than their corresponding S to M fluxes, and the S to M fluxes of the weak bases were larger than their M to S fluxes. These patterns of asymmetric movements were observed w...

The Central American volcanic arc supplies a significant proportion of the persistent annual global sulphur dioxide emissions from volcanoes. In November/December 2003, we completed a survey of the arc section from Mombacho to San Cristóbal in Nicaragua recording individual mean fluxes of 800, 530 and 220 Mg day 1 in the plumes from San Cristóbal, Telica and Masaya, respectively. An assessment ...

The aim of this study is to explain topography induced spatial variations in the diurnal cycles of assimilation and latent heat of Mediterranean forest. Spatial variations of the fluxes are caused by variations in weather conditions and in vegetation characteristics. Weather conditions reflect short-term effects of climate, whereas vegetation characteristics, through adaptation and acclimation,...

Differences in soil nitrous oxide (N2 O) fluxes among ecosystems are often difficult to evaluate and predict due to high spatial and temporal variabilities and few direct experimental comparisons. For 20 years, we measured N2 O fluxes in 11 ecosystems in southwest Michigan USA: four annual grain crops (corn-soybean-wheat rotations) managed with conventional, no-till, reduced input, or biologica...

Investigations of the atmospheric fallout of 7Be and 210pb in many places around the globe indicate that there are seasonal variations on the alepositional fluxes of these nuclides: high in winter in a few places, while in most places the high occurs in spring. However, these earlier studies did not address quantitatively the corresponding seasonal variations of the amount of precipitation duri...

Micrometeorological measurements of sizesegregated particle number fluxes above Dutch heathlands and forests have repeatedly shown simultaneous apparent emission of particles with a diameter (Dp)<0.18μm and deposition of larger particles when measured with optical particle counters. In order to assess whether this observation may be explained by the equilibrium reaction of ammonia (NH3), nitric...

[1] We measured soil nitrogen (N) cycling and fluxes of N2O and NO in three land-use types across the metropolitan area of Phoenix, Arizona. Urbanization increased N2O emissions compared to native landscapes, primarily due to the expansion of fertilized and irrigated lawns. Fluxes of N2O from lawns ranged from 18 to 80 mg N m!2 h!1 and were significantly larger than managed xeric landscapes (2....

One of the major problem appearing in compactifications of string theory, is the emergence of a continuous moduli space of string vacua. In order to get contact, not only to the standard model of particle physics, but also to (inflationary) cosmology, these moduli have to be fixed and if supersymmetry is broken only at fairly low energies, we have to understand the mechanism while preserving at...

The theoretical concept and initial test results of a Passive Surface Water Fluxmeter (PSFM) to directly and simultaneously measure cumulative water and solute mass fluxes in surface water flow systems are presented. The PSFM consists of a symmetric hydrofoil that is vertically installed in a stream and one or more sorbent columns that are connected to the nonuniform flow field around the hydro...

Previous studies suggest that ice shelves experience asymmetric melting and freezing. Topography may constrain oceanic circulation (and thus basal melt–freeze patterns) through its influence on the potential vorticity (PV) field. However, melting and freezing induce a local circulation that may modify locations of heat transport to the ice shelf. This paper investigates the influence of buoyanc...