Measuring changes in areal extent of historic wetlands at Great Sand Dunes National Monument, Colorado 1936-1995

1998 Summer.Includes bibliographical references (pages 82-86).Great Sand Dunes National Monument (GRSA) is a unit of the National Park system in south central Colorado. With funding from the Colorado Historical Society, a series of studies were undertaken for an environmental history of the GRSA area and the San Luis Valley. Park managers were concerned over the disappearance of small wetlands in northwestern GRSA. The objective of this study is to document and analyze the changes to the wetlands through the study of digital, georeferenced images and to relate these changes to climatic and hydrologic factors. Ten sets of aerial photographs were obtained, from 1936 to 1995, with at least one set from each decade except for the 1940s. All photos were scanned into a digital format. A system was devised to mosaic the images prior to rectification due to the lack of ground control in the area. Land cover was digitized from the mosaics including the wetlands and sand type. Size and spatial distribution of the wetlands were analyzed. Analysis shows that the greatest total number of wetlands and acreage totals were present in the 1936 and 1937 photo sets. In 1937, 114 wetlands were found, 47% have water at the surface. By 1953 the total number of wetlands dropped to 38 and by 1975 only 22 remained, with only 1 having water at the surface. The total number of wetlands has increased in recent years primarily due to sub-irrigated meadows. A large increase in the vegetation cover has .occurred since 1936 to the present, increasing from 20% of the area in 1936 to 47% by 1995. Climatic data were collected to analyze possible causes of the changes to the wetlands but the study was limited by the lack of long-term data. Weather data is consistently available since 1948. Well data is of short term and sporadic nature. Two sources of long-term data were available. The discharge of the Rio Grande has been monitored in Del Norte, CO since 1906. A dendrochronology study was done in the area of GRSA in 1980. The precipitation data, discharge and dendrochronology data were summed, averaged or offset for monthly or annual intervals prior to the dates of the aerial photo sets. These values were correlated with the acreage of the wetlands for each of the photo years by means of linear regression. Very poor correlation resulted between the precipitation indices and wetland acreage. A surprising result came from correlation of the wetland acreage with the dendrochronology and discharge data. Over 58% of the wetlands variation can be explained by the 15 to 19 year offsets of dendrochronology data, 55% can be explained by the 20 year offset of Rio Grande discharge. These results are interpreted that the offset indices are related to the slow change in total area of the wetlands rather than fluctuations in the water table

Anaerobic carbohydrate metabolism by trypanosoma brucei brucei

The pathway of anaerobic glycolysis of Trypanosoma brucei has been studied by the following five approaches : 1. Ensyme activity required for the various different postulated schemes for anaerobic glycolysis (hexose monophosphate aldolase, glycerol dehydrogenase, glycerophosphate : glucose or glycerophosphate : fructosesphosphate or glycerophosphate : triose or* glycerophosphate : ALP transphosphorylases) have been examined in a variety of assay conditions. Only significant activities of glycerophosphate : ALP transphosphorylase were detectable. 2. Broken cell incubation studies established that there were no significant differences in the sequence of the increase and decrease in glycolytic intermediates between aerobic and anaerobic pathways.3. Whole cell adenylate charge and glycolytic intermediates were assayed in steady-state aerobic, anaerobic and in the transitions between aerobic to anaerobic, and anaerobic to aerobic showed glucose-6-phosj)hate production to be the rate limiting step in anaerobic glucose utilization. Salicylhyaroxamic acid (0.5 mM) inhibited only glycerophosphate oxidase -and so simulated anaerobiosis. 4. The inhibitory effect of glycerol on whole cells metabolising glucose anaerobically showed it to be dependent upon the intracellular concentration of glycerophosphate. Consequently its inhibitory effect is not caused through the inhibition of glucose transport. 5. The concentration of glycerophosphate in cells metabolising glucose under glycerophosphate oxidase inhibited conditions was found to increase rapidly to a concentration that was independent of time and extracellular glycerol concentration. Furthermore it was found to be an intermediate in anaerobic glucose utilization. The results of this work were consistent with the pathway of carbohydrate metabolism under glycerophosphate oxidase inhibition which involved the production of glycerol plus ATP from ADP plus glycerophosphate catalysed by glycerokinase

A High Stability Optical Shadow Sensor with Applications for Precision Accelerometers

Gravimeters are devices which measure changes in the value of the gravitational acceleration, \textit{g}. This information is used to infer changes in density under the ground allowing the detection of subsurface voids; mineral, oil and gas reserves; and even the detection of the precursors of volcanic eruptions. A micro-electro mechanical system (MEMS) gravimeter has been fabricated completely in silicon allowing the possibility of cost e-effective, lightweight and small gravimeters. To obtain a measurement of gravity, a highly stable displacement measurement of the MEMS is required. This requires the development of a portable electronics system that has a displacement sensitivity of $\leq 2.5$ nm over a period of a day or more. The portable electronics system presented here has a displacement sensitivity $\leq 10$ nm$/\sqrt{\textrm{Hz}}$ ($\leq 0.6$ nm at $1000$ s). The battery power system used a modulated LED for measurements and required temperature control of the system to $\pm$ 2 mK, monitoring of the tilt to $\pm$ 2 $\mu$radians, the storage of measured data and the transmission of the data to an external server.Comment: 8 Pages, 12 figures, 5 equations, currently submitted and under review at IEEE Sensors SIE

Platelet Response in Hypercholesterol Blood to Thrombin-Induced Aggression

A report submitted by David J. Saxon to the Research and Creative Productions Committee in 1989 on whether hypercholesterol platelets are more responsive than normocholesterolemic platelets to thrombin-induced aggregation in whole blood

Using genomic DNA-based probe-selection to improve the sensitivity of high-density oligonucleotide arrays when applied to heterologous species

High-density oligonucleotide (oligo) arrays are a powerful tool for transcript profiling. Arrays based on GeneChip® technology are amongst the most widely used, although GeneChip® arrays are currently available for only a small number of plant and animal species. Thus, we have developed a method to improve the sensitivity of high-density oligonucleotide arrays when applied to heterologous species and tested the method by analysing the transcriptome of Brassica oleracea L., a species for which no GeneChip® array is available, using a GeneChip® array designed for Arabidopsis thaliana (L.) Heynh. Genomic DNA from B. oleracea was labelled and hybridised to the ATH1-121501 GeneChip® array. Arabidopsis thaliana probe-pairs that hybridised to the B. oleracea genomic DNA on the basis of the perfect-match (PM) probe signal were then selected for subsequent B. oleracea transcriptome analysis using a .cel file parser script to generate probe mask files. The transcriptional response of B. oleracea to a mineral nutrient (phosphorus; P) stress was quantified using probe mask files generated for a wide range of gDNA hybridisation intensity thresholds. An example probe mask file generated with a gDNA hybridisation intensity threshold of 400 removed > 68 % of the available PM probes from the analysis but retained >96 % of available A. thaliana probe-sets. Ninety-nine of these genes were then identified as significantly regulated under P stress in B. oleracea, including the homologues of P stress responsive genes in A. thaliana. Increasing the gDNA hybridisation intensity thresholds up to 500 for probe-selection increased the sensitivity of the GeneChip® array to detect regulation of gene expression in B. oleracea under P stress by up to 13-fold. Our open-source software to create probe mask files is freely available http://affymetrix.arabidopsis.info/xspecies/ webcite and may be used to facilitate transcriptomic analyses of a wide range of plant and animal species in the absence of custom arrays

XUV Frequency Combs via Femtosecond Enhancement Cavities

We review the current state of tabletop extreme ultraviolet (XUV) sources based on high harmonic generation (HHG) in femtosecond enhancement cavities (fsEC). Recent developments have enabled generation of high photon flux (1014 photons/sec) in the XUV, at high repetition rates (>50 MHz) and spanning the spectral region from 40 nm - 120 nm. This level of performance has enabled precision spectroscopy with XUV frequency combs and promises further applications in XUV spectroscopic and photoemission studies. We discuss the theory of operation and experimental details of the fsEC and XUV generation based on HHG, including current technical challenges to increasing the photon flux and maximum photon energy produced by this type of system. Current and future applications for these sources are also discussed.Comment: invited review article, 38 page

Water content detection in aviation fuel by using PMMA based optical fiber grating

Water in aviation fuel is a destructive contaminant and can cause serious problems that compromise aircraft’s safe operation and reduce its efficiency and lifetime. Online monitoring of water content in aviation fuel would permit the control of water content before it builds up to dangerous level. Optical fibers made of PMMA have water affinity. In a PMMA based optical fiber Bragg grating (POFBG) its refractive index and volume vary with the water content. This feature is used to detect tiny water content in aviation fuel in this work. The sensing mechanism of POFBG is analyzed. POFBG wavelength is found to be the function of both temperature and equilibrium relative humidity (ERH). POFBG response to water content in fuel can be determined by the ERH. The sensor is experimented at different environmental conditions to identify its sensitivity. As a result, a general expression of POFBG response is achieved. Water content in Jet-A1 is measured by using POFBG sensor calibrated with both environmental chamber and coulometric titration. POFBG sensor is finally tested in a simulation fuel tank, demonstrating a better performance than coulometric titration. A sensitivity of POFBG wavelength change to water content of 33 pm/ppm is achieved at room temperature, indicating detectable water content of 0.03 ppm