Efficiency Quantification for Pulsed-source Digital Holographic Wavefront Sensing

The efficiencies of a digital holography (DH) system in the pulsed configuration and the off-axis image plane recording geometry are analyzed. First, the system efficiencies of an infrared-wavelength DH system in a homodyne-pulsed configuration are measured and compared to those of a visible-wavelength DH system in a homodyne-continuous-wave (CW) configuration. The total-system, excess-reference-noise, shot-noise-limit, and mixing efficiencies of the pulsed-source system were found to be consistent with those of the CW-source system. This indicated no new efficiencies were necessary to characterize pulsed-source systems when no temporal delay exists between the pulses. The consistency of efficiencies also showed infrared DH systems are viable but degraded due to infrared detector technology. A new efficiency, called the ambiguity efficiency, was introduced to account for the degradation in system performance as the temporal delay between the pulses increased. This novel efficiency was then experimentally verified. Second, a DH system in the heterodyne-pulsed configuration was characterized in terms of the total-system and ambiguity efficiencies. The efficiencies measured using a heterodyne-pulsed configuration were consistent with those measured using a homodyne-pulsed configuration. Therefore, there was no degradation in system performance by changing from a homodyne configuration to a heterodyne configuration. This will allow the effective range of pulsed-source DH systems to greatly increase. Third, the effect of spectrally broadening the source laser of a DH system in the heterodyne-pulsed configuration was analyzed. Experiments showed the ambiguity efficiency was not significantly affected by the degradation in temporal coherence. However, the total-system efficiency did change as a function of temporal coherence degradation

Population Density Measurements of the Excited States of an Optically Excited Argon Discharge Using Emission and Absorption Spectroscopy

The populations of the excited argon 3s23p54s (s5 only) and 3s23p54p configurations in a 10 W radio frequency discharge has been studied using optical emission and diode laser absorption spectroscopy. By optically bleaching the s5→p9 transition with a narrow band laser pump of about 10 W/cm2 at 811 nm, the p9 population was increased by about a factor of 2 at a pressure of 5 Torr. At higher pressure, collisional mixing to adjacent p-states limited the laser-increased p9 population to less than 10 percent. All other laser-induced p-state populations were minimally affected at low pressure and increased by about a factor of 4 at higher pressure. The low pressure absorption line shapes exhibited an inhomogeneous hole with band-integrated absorbance that scaled linearly with pump power. The s5 population was greater than 7×1011 cm-3 at a pressure of 5 Torr, and about 57 percent of this population was moved to the p9 state at 828 mW, or about 10 W/cm2. Implications for development of a higher power optically pumped rare gas laser are discussed

Spectral broadening Effects on Pulsed-source Digital Holography

Using a pulsed configuration, a digital-holographic system is setup in the off-axis image plane recording geometry, and spectral broadening via pseudo-random bit sequence is used to degrade the temporal coherence of the master-oscillator laser. The associated effects on the signal-to-noise ratio are then measured in terms of the ambiguity and coherence efficiencies. It is found that the ambiguity efficiency, which is a function of signal-reference pulse overlap, is not affected by the effects of spectral broadening. The coherence efficiency, on the other hand, is affected. As a result, the coherence efficiency, which is a function of effective fringe visibility, is shown to be a valid performance metric for pulsed-source digital holography

Seasonal Variation in Terrestrial Invertebrate Subsidies to Tropical Streams and Implications for the Feeding Ecology of Hart’s Rivulus (Anablepsoides hartii)

Terrestrial invertebrates are important subsidies to fish diets, though their seasonal dynamics and importance to tropical stream consumers are particularly understudied. In this year-round study of terrestrial invertebrate input to two Trinidadian headwater streams with different forest canopy densities, we sought to (a) measure the mass and composition of terrestrial inputs with fall-in traps to evaluate the influences of seasonality, canopy cover, and rainfall intensity, and; (b) compare terrestrial and benthic prey importance to Anablepsoides hartii(Hart’s Rivulus), the dominant invertivorous fish in these streams, by concurrently measuring benthic and drifting invertebrate standing stocks and the volume and composition of invertebrates in Rivulus guts throughout the year. The biomass of terrestrial invertebrate fall-in was 53% higher in the wet versus dry season; in particular, ant input was 320% higher. Ant biomass fall-in also increased with the density of canopy cover among sampling locations within both streams. Greater precipitation correlated with increased ant inputs to the more open-canopied stream and increased inputs of winged insects in the more closed canopy stream. Concurrently, the biomass of benthic invertebrates was reduced by more than half in the wet season in both streams. We detected no differences in the total volume of terrestrial prey in Rivulus diets between seasons, though ants were a greater proportion of their diet in the wet season. In contrast, benthic prey were nearly absent from Rivulus diets in the wet season in both streams. We conclude that terrestrial invertebrates are a substantial year-round prey subsidy for invertivores in tropical stream ecosystems like those we studied, which may contrast to most temperate streams where such terrestrial inputs are significantly reduced in the cold season. Interestingly, the strongest seasonal pattern in these tropical streams was observed in benthic invertebrate biomass which was greatly reduced and almost absent from Rivulus diets during the wet season. This pattern is essentially the inverse of the pattern observed in many temperate streams and highlights the need for additional studies in tropical ecosystems to better understand how spatial and temporal variation in terrestrial subsidies and benthic prey populations combine to influence consumer diets and the structure of tropical stream food webs

A Cannabinoid CB 1 Receptor-Positive Allosteric Modulator Reduces Neuropathic Pain in the Mouse with No Psychoactive Effects

Peer reviewedPostprin

Calibration and application of a sediment accumulation rate model – a case study

A mechanistic mass balance model for sediment accumulation rate (SAR) that accommodates the dry density and burial velocity of solids and the depth dependency of porosity was tested and applied to Onondaga Lake, New York, for a 130-year period. The modeling for this case study is supported by a rich history of multiple anthropogenic drivers and coupled date horizons from the paleolimnological record, characterization of physical attributes of the sediments, and long-term monitoring of the water column and lake inputs. The consistency of predictions of SAR and measurements of downward flux of suspended particulate material (DFSPM) from a long-term sediment trap program was also evaluated. The model was demonstrated to perform well in simulating the lake’s history of SAR, which was supported by 10 different depth–date horizons. This history for 100 years was regulated by the production of soda-ash at an adjoining industry, which enhanced autochthonous formation and deposition of calcium carbonate (CaCO3), proportional to the level of production of this chemical. The SAR was extraordinarily high (~5 kg m-2 yr-1) during the 40 years of peak soda-ash production. An abrupt, more than 2-fold decrease in SAR occurred when the industry closed. The contemporary SAR remains relatively high as a result of multiple drivers but is serving to enhance burial of contaminants, including mercury, as part of an ongoing rehabilitation program. A high level of consistency (within 30%) between the contemporary SAR and an annual estimate of DFSPM was documented. The utility of the model was demonstrated through applications that depict the amount of deposits contributed by the industry, the effect of compaction on burial velocity, the dilution effect of the high SAR values on the paleolimnological record, and the resolution of sediment diagenesis kinetics

Prospective screening for postoperative deep venous thrombosis in patients undergoing infrainguinal revascularization

AbstractPurpose: The incidence of deep venous thrombosis (DVT) in patients undergoing infrainguinal bypass graft procedures has not been well documented, and the need for routine prophylaxis remains controversial. The purpose of this study was to prospectively evaluate the risk of postoperative DVT complicating infrainguinal revascularization. Methods: Seventy-four patients undergoing infrainguinal bypass graft procedures during a 12-month period were prospectively screened for DVT. Bilateral lower extremity venous duplex scan imaging was performed preoperatively and within 1 week and 6 weeks, postoperatively. Routine DVT prophylaxis was not used, with anticoagulation reserved for specific indications. Results: Of the 74 patients screened, three patients (4.1%) had DVT identified on preoperative venous duplex scan imaging and were excluded from the study. Of the remaining 71 patients enrolled, only two patients (2.8%) had postoperative DVT. Postoperative DVT was ipsilateral to the bypass graft extremity in both patients, with involvement of the peroneal vein in one patient and the femoral vein in the other. Although routine prophylaxis was not used, 18 of these patients (25%) were anticoagulated for other indications, with DVT occurring in one patient (5.6%). Of the remaining 53 patients who did not receive postoperative anticoagulation, only one patient (1.8%) had DVT. Conclusions: According to this prospective study, the risk of postoperative DVT in patients undergoing infrainguinal revascularization is low. Routine prophylaxis is not recommended, with postoperative anticoagulation reserved for specific indications. (J Vasc Surg 2000;32:669-75.

Financing Direct Democracy: Revisiting the Research on Campaign Spending and Citizen Initiatives

The conventional view in the direct democracy literature is that spending against a measure is more effective than spending in favor of a measure, but the empirical results underlying this conclusion have been questioned by recent research. We argue that the conventional finding is driven by the endogenous nature of campaign spending: initiative proponents spend more when their ballot measure is likely to fail. We address this endogeneity by using an instrumental variables approach to analyze a comprehensive dataset of ballot propositions in California from 1976 to 2004. We find that both support and opposition spending on citizen initiatives have strong, statistically significant, and countervailing effects. We confirm this finding by looking at time series data from early polling on a subset of these measures. Both analyses show that spending in favor of citizen initiatives substantially increases their chances of passage, just as opposition spending decreases this likelihood

Influence of Diporeia Density on Diet Composition, Relative Abundance, and Energy Density of Planktivorous Fishes in Southeast Lake Michigan

The benthic amphipod Diporeia spp. is an important prey for many fish in offshore areas of the Great Lakes, but its abundance has been rapidly decreasing. To assess the influence of Diporeia availability on the food habits, relative abundance, and energetics of planktivorous fish, the diet composition, catch per unit effort (CPUE), and energy density of plantkivorous fish in southeast Lake Michigan during 2000–2001 were compared among locations with different Diporeia densities. Diporeia densities at St. Joseph, Michigan, were near 0/m2 over much of the bottom but averaged more than 3,800/m2 at Muskegon and Little Sable Point, Michigan. Consistent with these differences in Diporeia density, fish diet composition, CPUE, and energy density varied spatially. For example, alternative prey types comprised a larger fraction of the diets of bloater Coregonus hoyi, large (>100 mm total length) alewife Alosa pseudoharengus, and slimy sculpin Cottus cognatus at St. Joseph than at Muskegon and Little Sable Point. This pattern was seasonally dependent for alewives and bloaters because Diporeia were eaten mainly in June. Food biomass per stomach was not lower at St. Joseph than elsewhere, suggesting that the spatial variation in diet composition was due to greater consumption of alternative prey by fish at St. Joseph. Although slimy sculpin and bloaters were able to feed on alternative prey, the CPUE of these species at certain depths was considerably lower at St. Joseph than at Muskegon or Little Sable Point, indicating that Diporeia availability may also influence fish abundance and distribution. Finally, a link between Diporeia density and fish energetics was suggested by the comparatively low energy density of deepwater sculpin Myoxocephalus thompsonii and large alewives at St. Joseph, a result that may reflect the low energy content of other prey relative to Diporeia.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141042/1/tafs0588.pd

Long-term impacts of conservation pasture management in manuresheds on system-level microbiome and antibiotic resistance genes

Animal manure improves soil fertility and organic carbon, but long-term deposition may contribute to antibiotic resistance genes (ARGs) entering the soil-water environment. Additionally, long-term impacts of applying animal manure to soil on the soil-water microbiome, a crucial factor in soil health and fertility, are not well understood. The aim of this study is to assess: (1) impacts of long-term conservation practices on the distribution of ARGs and microbial dynamics in soil, and runoff; and (2) associations between bacterial taxa, heavy metals, soil health indicators, and ARGs in manures, soils, and surface runoff in a study following 15 years of continuous management. This management strategy consists of two conventional and three conservation systems, all receiving annual poultry litter. High throughput sequencing of the 16S ribosomal RNA was carried out on samples of cattle manure, poultry litter, soil, and runoff collected from each manureshed. In addition, four representative ARGs (intl1, sul1, ermB, and blactx-m-32) were quantified from manures, soil, and runoff using quantitative PCR. Results revealed that conventional practice increased soil ARGs, and microbial diversity compared to conservation systems. Further, ARGs were strongly correlated with each other in cattle manure and soil, but not in runoff. After 15-years of conservation practices, relationships existed between heavy metals and ARGs. In the soil, Cu, Fe and Mn were positively linked to intl1, sul1, and ermB, but trends varied in runoff. These findings were further supported by network analyses that indicated complex co-occurrence patterns between bacteria taxa, ARGs, and physicochemical parameters. Overall, this study provides system-level linkages of microbial communities, ARGs, and physicochemical conditions based on long-term conservation practices at the soil-water-animal nexus