On the concept of pressure in quantum mechanics

Heat and work are fundamental concepts for thermodynamical systems. When these are scaled down to the quantum level they require appropriate embeddings. Here we show that the dependence of the particle spectrum on system size giving rise to a formal definition of pressure can, indeed, be correlated with an external mechanical degree of freedom, modelled as a spatial coordinate of a quantum oscillator. Under specific conditions this correlation is reminiscent of that occurring in the classical manometer.Comment: 7 pages, 3 figure

The dynamical balance, transport and circulation of the Antarctic Circumpolar Current

The physical ingredients of the ACC circulation are reviewed. A picture of thecirculation is sketched by means of recent observations of the WOCE decade. Wepresent and discuss the role of forcing functions (wind stress, surfacebuoyancy flux) in the balance of the (quasi)-zonal flow, the meridionalcirculation and their relation to the ACC transport. Emphasis will be on theinterrelation of the zonal momentum balance and the meridional circulation, theimportance of diapycnal mixing and eddy processes. Finally, new model conceptsare described: a model of the ACC transport dependence on wind stress andbuoyancy flux, based on linear wave theory; and a model of the meridionaloverturning of the Southern Ocean, based on zonally averaged dynamics with eddyparameterization

Patterns and sources of anthropogenic contaminants in the Otter Creek Watershed, Madison County, Kentucky

Stream systems are often affected by anthropogenic activities that affect water quality and stream ecosystems. Land use typically determines the type and quantity of anthropogenic contaminants entering natural waters. The Otter Creek watershed (170 km2; Madison County, Kentucky) consists predominantly of pasture and rural housing, with some cropland. The basin also receives runoff from the town of Richmond and a sewage treatment plant operates within the watershed. We measured concentrations of nutrients (phosphate, ammonium, nitrate) and fecal microbes to discover levels of anthropogenic contaminants affecting water quality and to identify contaminant sources. We sampled 4 times in the summer field season of 2015 over a variety of conditions. Nutrients were measured colorimetrically using established colorimetric methods. The abundance of Escherichia coli was quantified using IDEXX rapid-assay techniques. Phosphate (0 – 0.5 mg/L) and ammonium (\u3c0.1 mg/L) concentrations were low for all sampling days, whereas nitrate was the dominant anthropogenic nutrient contaminant showing concentrations of 1 to 3 mg/L. Consistently higher levels of phosphate and nitrate were found in the waters of Dreaming Creek, which drains urban Richmond. High ammonium levels were sporadic and associated with pasture. High E. coli counts occurred in Dreaming Creek, the upper reaches of Otter Creek, and proximal to pastures. Both point- and non-point sources exist for contaminants. The sewage treatment plant is a definite point source for nitrate and less so for phosphate and ammonium. Non-point sources include high concentrations of nitrate, phosphate, and fecal microbes occur along Dreaming Creek, likely due to leaky sewage distribution pipes. Spikes in ammonium concentration are associated with cattle pasture, another non-point source. We also tested contaminant levels immediately before and after a rainfall event associated with tropical storm Bill (June 22). Phosphate and ammonium levels decreased, whereas nitrate increased significantly. E. coli counts also increased dramatically, after the rain event

Seasonal changes in a eutrophic lake, Wilgreen Lake, Madison County, Kentucky

WilgreenLake (Madison County, Kentucky) covers ~169 acres, formed in 1966 by damming Taylor Fork. The Wilgreen watershed drains residential developments, modified woodlands, cattle pasture, and some industrial/urban areas in the city ofRichmond. The lake is deemed “nutrient impaired” by the EPA. Our main objective is to document the seasonal changes in key lake parameters from summer stratification through fall overturn over 4 months of sampling, August through November, 2008. We collect temperature, oxygen, pH, and conductivity data from 19 stations at depth intervals of 1 meter using an YSI multi-probe. Concurrent with collecting these framework data, we take water samples, also at 1-meter intervals, and measure phosphate (PO4-), ammonium (NH4+), and nitrate (NO3-) concentration. Summer stratification exerts a large control on processes occurring within the lake, as does stream inflow. August and September surface temperatures range from 25 to 26.5 degrees Celsius, considerably cooler than in 2006 and 2007. The summer thermocline was located between 6 and 7 meters. Oxygen concentrations are highest in surface layer of the lake, become disoxic below 3 to 4 meters, and are anoxic only for the bottom several meters at our deepest stations. In 2008, a much smaller volume of the lake was anoxic. We attribute these annual differences to a much cooler and wetter early summer in 2008. Much higher nutrient concentrations occur near the largest stream inputs into the lake, either from watershed runoff or from anthropogenic sources near the lakeshore such as septic systems

A preliminary comparison of the sulfur geochemistry between two gas hydrate terranes

We compare the authigenic sulfide mineral geochemistry of two, different gas hydrate terranes: the accretionary wedge of the Cascadia continental margin (offshore Oregon) and the passive margin of the BlakeRidgeregion (offshore southeastern US). We expect diagenetic processes effecting sulfide mineral formation (elemental sulfur, iron monosulfides, and pyrite) within these sediments to respond to differing geologic conditions at each setting. In both settings, methane diffuses upward from gas hydrates to the methane-sulfate interface (SMI), where it is consumed by reaction with sulfate during anaerobic methane oxidation (AMO). This microbially-mediated, diagenetic process produces an interstitial environment conducive to authigenic sulfide mineral formation, so that sulfide minerals tend to be concentrated near the SMI and contain more heavy sulfur (34S). Sulfate reduction occurs simultaneously as sulfate is consumed by microbes utilizing sedimentary organic matter as a foodstuff. In this case, more sulfide mineralization occurs above the SMI, and so that sulfide minerals there should contain more 32S. These competing sulfate-depleting processes potentially produce different vertical distributions of the concentration and sulfur isotopic composition (d34S) of sulfide minerals preserved within the sedimentary record. Preliminary geochemical results from ODP Site 1244 (Cascadia) show a shallower SMI, large concentrations of dissolved sulfide, significant levels of dissolved iron only where dissolved sulfide is low to absent, larger amounts of sulfide sulfur in the sediments, and a similar d34S profile as compared to Blake Ridge sediments. Because methane is consumed by AMO in both settings, we hypothesize that sulfate reduction is responsible for most sulfide mineralization within Cascadia sediments

Predictions from a stochastic polymer model for the MinDE dynamics in E.coli

The spatiotemporal oscillations of the Min proteins in the bacterium Escherichia coli play an important role in cell division. A number of different models have been proposed to explain the dynamics from the underlying biochemistry. Here, we extend a previously described discrete polymer model from a deterministic to a stochastic formulation. We express the stochastic evolution of the oscillatory system as a map from the probability distribution of maximum polymer length in one period of the oscillation to the probability distribution of maximum polymer length half a period later and solve for the fixed point of the map with a combined analytical and numerical technique. This solution gives a theoretical prediction of the distributions of both lengths of the polar MinD zones and periods of oscillations -- both of which are experimentally measurable. The model provides an interesting example of a stochastic hybrid system that is, in some limits, analytically tractable.Comment: 16 page

Patterns and sources of anthropogenic contaminants in the Otter Creek watershed, Madison County, Kentucky

Stream systems are often affected by anthropogenic contaminants that affect water quality and stream ecosystems. Land use determines the type and quantity of contaminants present in natural waters. The Otter Creek watershed (170 km2; Madison County, Kentucky) consists predominantly of pasture and rural housing, with some cropland. The basin also receives runoff from the town of Richmond and a sewage treatment plant operates within the watershed. We measured concentrations of nutrients (phosphate, ammonium, nitrate) and fecal microbes to discover levels of anthropogenic contaminants affecting water quality and to identify contaminant sources. We sampled 4 times in the summer field season of 2015 over a variety of conditions. Water samples for nutrient analysis were pressed through a 0.45 µm filter, placed in pre-acidified vials, and measured one or two days after collection. Nutrients were measured colorimetrically using established methods. Microbial samples were collected in sterile containers, placed on ice in the field, and then transported to the lab where they were spiked with Colilert-18 media. Samples incubated overnight at 35oC, and Escherichia coli were quantified using IDEXX rapid-assay techniques. Phosphate (0 – 0.5 mg/L) and ammonium (\u3c0.1 mg/L) concentrations were low for all sampling days, whereas nitrate was the dominant anthropogenic nutrient contaminant showing concentrations of 1 – 3 mg/L. Consistently higher levels of phosphate and nitrate were found in the waters of Dreaming Creek, which drains urban Richmond. High ammonium levels were sporadic and associated with pasture. High E. coli counts occurred in Dreaming Creek, the upper reaches of Otter Creek, and proximal to pastures. Both point- and non-point sources exist for contaminants. The sewage treatment plant is a definite point source for nitrate and less so for phosphate and ammonium. High concentrations of nitrate, phosphate, and fecal microbes occur along Dreaming Creek, likely due to leaky sewage distribution pipes. Spikes in ammonium concentration are sourced from cattle pasture. We also tested contaminant levels immediately before and after a rainfall event associated with tropical storm Bill. Phosphate and ammonium levels decreased, whereas nitrate increased significantly. E. coli counts also increased dramatically

Patterns of anthropogenic nutrient contaminants in the Otter Creek watershed, Madison County, Kentucky

We measured nutrient concentrations within the Otter Creek watershed (Madison County, Kentucky) to: (1) discover levels of anthropogenic contaminants affecting the water quality; (2) compare these measurements to a national data set; and (3) identify nutrient sources. The watershed mainly drains rural land characterized by cattle grazing, but also drains the town of Richmond. We sampled throughout the watershed to gain a representative perspective of nutrient levels and specifically targeted localities of suspected anthropogenic nutrient sources. Water samples were passed through a 0.45 mm filter, placed in pre-acidified vials, and measured one to two days after collection. Nutrients – ammonium, nitrate, and phosphate – were measured colorimetrically using the sodium hypochlorite, cadmium reduction, and ascorbic acid methods, respectively. Nutrients within the watershed show distinctively different concentration patterns. Ammonium and phosphate levels remain low for all sampling days. Higher ammonium concentrations are sporadic, but higher phosphate levels persist along Dreaming Creek, which drains Richmond. Nitrate consistently shows higher concentration levels of 4 to 7 mg/L and generally falls with the 25 to 50 percentile range as compared to impacted streams nationally. We sampled the watershed before and after a significant rain event. Ammonium and phosphate values changed little, but much larger amounts of nitrate entered Otter Creek afterward. We attribute higher nutrient values to several sources. A sewage treatment plant is a definite point source for nitrate and to lesser extent for phosphate. High nutrient values in Dreaming Creek are likely due leaky sewage pipes. The major non-point source is from cattle pasture