We used mass load budgets, transient storage modeling, and nutrient spiraling metrics to characterize nitrate (NO), ammonium (NH), and inorganic phosphorus (SRP) demand in seven agricultural streams across the United States and to identify in-stream services that may control these conditions. Retention of one or all nutrients was observed in all but one stream, but demand for all nutrients was ...

Technetium-99m hexakis 2-methoxy-2-isobutyl isonitrile (Tc-MIBI) and thallium-201 extraction, washout, and retention were investigated and compared in 20 isolated, isovolumic, retrograde blood-perfused rabbit hearts at flow rates ranging from 0.5 to 3.5 ml/g wet wt min-1 in the absence of tracer recirculation. Mean Tc-MIBI peak instantaneous extraction was lower (0.55 +/- 0.10, p less than 0.00...

A three-step procedure has been developed for the separation of complex mixtures of sterol intermediates in cholesterol biosynthesis. The method has been applied to the separation of sterol intermediates formed from [14C]mevalonate by normal rat hepatocyte culture cells. In Step 1, a short gravity-flow silicic acid column (1.2 x 6.5 cm) separates the incubation products into four classes consis...

Many experiments provide evidence that practicing retrieval benefits retention relative to conditions of no retrieval practice. Nearly all prior research has employed retrieval practice requiring overt responses, but a few experiments have shown that covert retrieval also produces retention advantages relative to control conditions. However, direct comparisons between overt and covert retrieval...

Inverse gas chromatography (IGC) is used for the analysis of the influence of air relative humidity on the retention of hexane, benzene, toluene and p-xylene in a sandy soil under experimental conditions similar to those typical of soil vapor extraction (SVE). The advantages of IGC over other techniques, are (a) an efficient use of lab resources, (b) a high sensitivity to low partitioning coeff...

This report examines the use of high-performance affinity chromatography as a screening tool for studying the change in binding by sulfonylurea drugs to the protein human serum albumin (HSA) during diabetes. The effects of both the non-enzymatic glycation of HSA and the presence of fatty acids on these interactions were considered using a zonal elution format. It was found that there was a sign...

Primate retrosplenial cortex (RSC) is important for memory but patient neuropathologies are diffuse so its key contributions to memory remain elusive. This study provides the first causal evidence that RSC in macaque monkeys is crucial for postoperative retention of preoperatively and postoperatively acquired memories. Preoperatively, monkeys learned 300 object-in-place scene discriminations ac...

Downward carbon flux in the ocean is largely governed by particle settling. Most marine particles settle at low Reynolds numbers and are highly porous, yet the fluid dynamics of this regime have remained unexplored. We present results of an experimental investigation of porous particles settling through a density interface at Reynolds numbers between 0.1 and 1. We tracked 100 to 500 μm hydrogel...

In the present study, we examined how the function relating continued retrieval practice (e.g., one, three, or five tests) and long-term memory retention is modulated by desirable difficulty (R. A. Bjork, 1994). Of particular interest was how retrieval difficulty differed across young and older adults and across manipulations of lag (Exp. 1) and spacing (Exp. 2). To extend on previous studies, ...

Soil and aquifer materials have a finite capacity for colloid retention. Blocking of the limited number of available retention sites further decreases the rate of retention with time and enhances risks (e.g., pathogens or colloid-associated contaminants) or benefits (e.g., remediation by microorganisms or nanoparticles) of colloid migration. Our objective was to use a straightforward procedure,...