Light Field and Water Clarity Simulation of Natural Environments in Laboratory Conditions

Simulation of natural oceanic conditions in a laboratory setting is a challenging task, especially when that environment can be miles away. We present an attempt to replicate the solar radiation expected at different latitudes with varying water clarity conditions up to 30 m in depth using a 2.5 m deep engineering tank at the University of New Hampshire. The goals of the study were: 1) to configure an underwater light source that produced an irradiance spectrum similar to natural daylight with the sun at zenith and at 60° under clear atmospheric conditions, and 2) to monitor water clarity as a function of depth. Irradiance was measured using a spectra-radiometer with a cosine receiver to analyze the output spectrum of submersed lamps as a function of distance. In addition, an underwater reflection method was developed to measure the diffuse attenuation coefficient in real time. Two water clarity types were characterized, clear waters representing deep, open-ocean conditions, and murky waters representing littoral environments. Results showed good correlation between the irradiance measured at 400 nm to 600 nm and the natural daylight spectrum at 3 m from the light source. This can be considered the water surface conditions reference. Using these methodologies in a controlled laboratory setting, we are able to replicate illumination and water conditions to study the physical, chemical and biological processes on natural and man-made objects and/or systems in simulated, varied geographic locations and environments

Radiometric and Photometeric Determinations of Simulated Shallow-Water Environment

Optical remote sensing is increasingly becoming a preferred economic alternative to the traditional in situ observations and physical sampling for mapping and monitoring habitats. Submersed habitats, such as eelgrass and corals, are especially challenging for field work. Even for remote-sensing work, a priori knowledge of environmental factors is required for highly accurate analysis. Background illumination and water clarity are two key factors that affect the optical remote-sensing imagery, which may vary widely with season, time of year, geographic location, or water depth. This article presents efforts to simulate natural oceanic conditions in a laboratory setting. Solar radiation predicted at different latitudes under varying water clarity conditions and depth were replicated using a 2.5 m deep wave tank at the University of New Hampshire. The goals of the study were: (1) to simulate illumination and water clarity conditions that approximate coastal and oceanic waters, and (2) to quantify the impact of the simulated illumination and water clarity conditions at different depths on the apparent colours that can be observed from an aerial platform. The empirical radiometric measurements included irradiance, radiance, and remote-sensing reflectance from an underwater array of light sources. The results of the study show good correlation (r 2 = 0.89–0.93) between the natural daylight spectrum at the water surface and the irradiance measurements between 350 nm and 590 nm, at 3.5 m from the light array. The colours of the clear and murky water types were photometrically calculated from the radiometric measurements and validated using underwater video imagery. Using this methodology, illumination and water clarity can be replicated under controlled laboratory conditions and used to assist in studying the physical, chemical, and biological processes in habitats, at varied geographic locations and differing environments

Comparative molecular properties of swine and human very low density lipoproteins—Apoproteins E and C

1. By means of 2-dimensional gradient-gel electrophoresis, the very low density lipoproteins (VLDL) apoproteins E and C profiles from human and swine plasma were studied.2. The molecular properties (isoelectric point and molecular weight) of the VLDL apoproteins and their isoforms were determined and showed many similarities between species.3. It also appears evident that a previously unrecognized apoprotein (C-III) and several associated isoforms may exist in swine; however, it\u27s mobility on 2-dimensional gradient gels is very similar to APO C-II

Low-Dose a-Tocopherol Improves and HighDose a-Tocopherol Worsens Endothelial Vasodilator Function in Cholesterol-Fed Rabbits

Abnormalities in endothelium-dependent arterial relaxation develop early in atherosclerosis and may, in part, result from the effects of modified low-density lipoprotein (LDL) on agonistmediated endothelium-derived relaxing factor (EDRF) release and EDRF degradation. a-Tocopherol (AT) is the main lipidsoluble antioxidant in human plasma and lipoproteins, therefore, we investigated the effects of AT on endothelium-dependent arterial relaxation in male New Zealand White rabbits fed diets containing (a) no additive (controls), (b) 1 % cholesterol (cholesterol group), or 1 % cholesterol with either (c) 1,000 IU/kg chow AT (low-dose AT group) or (d) 10,000 IU/kg chow AT (high-dose AT group). After 28 d, we assayed endothelial function and LDL susceptibility to ex vivo copper-mediated oxidation. Acetylcholine- and A23187-mediated endothelium-dependen