Trophozoite killing assays for Tritrichomonas foetus parasites

Tritrichomonas foetus is a sexually-transmitted protozoan parasite infecting cattle throughout the world. In cows, infection results in early embryonic death and abortion. Current control methods rely on culling infected animals and there is no curative treatment. We obtained a field strain of the parasite from an Iowa bull and isolated it in axenic culture. We then developed a trophozoite killing assay suitable for identifying compounds with anti-parasite activity. Current and future studies involve screening of antimicrobial agents and identification of lead compounds for future in vivo studies

Modeling the Biogeochemical Cycle of Selenium in the San Francisco Bay

Due to recent concerns about selenium toxicity in the San Francisco Bay and the roles of refinery and San Joaquin River inputs on the selenium cycle, the model ECoS 3 (distributed from Plymouth Marine Laboratory, United Kingdom) was modified to simulate the biogeochemical cycle of selenium in the Northern Reach. The model is designed to simulate salinity, total suspended material, phytoplankton concentrations, dissolved selenium and its speciation (selenite, selenate, and organic selenide), and particulate selenium and its speciation (selenite + selenate, elemental selenium, and organic selenide). Actual data from 1999 were used to calibrate the model, while data from other sampling periods (1986–1988 and 1997–1998) were then compared to model simulations to verify its accuracy. The sensitivity of the model to specific inputs of selenium was also determined. These results indicate that dissolved selenium is largely controlled by riverine and refinery inputs, while particulate selenium is a function of phytoplankton productivity and riverine inputs of sediment. Forecasting simulations included increasing the San Joaquin River discharge to the Delta and varying refinery discharges to the Bay. These simulation results indicate that total particulate selenium concentrations may increase in the entire Bay to 1 μg g−1 if the San Joaquin Flow is increased. This concentration is twice as high as the current estuarine average particulate selenium and at the level where the concentration of selenium in Potomocorbula amurensis becomes problematic for estuarine predators. Furthermore, simulations suggest that doubling the current refinery loads as selenate have little effect on the particle-associated selenium in the estuary. Simulated data from the model can be used in other models to predict selenium concentrations in higher trophic levels. Furthermore the model can be used as a template to study the biogeochemical cycle of other elements in well-mixed estuaries, and in restoration projects, pollution control and other trophic transfer scenarios

Evaluating the Biogeochemical Cycle of Selenium in San Francisco Bay Through Modeling

A biogeochemical model was developed to simulate salinity, total suspended material, phytoplankton biomass, dissolved selenium concentrations (selenite, selenate, and organic selenide), and particulate selenium concentrations (selenite + selenate, elemental selenium, and organic selenide) in the San Francisco Bay estuary. Model-generated estuarine profiles of total dissolved selenium reproduced observed estuarine profiles at a confidence interval of 91- 99% for 8 different years under various environmental conditions. The model accurately reproduced the observed dissolved speciation at confidence intervals of 81-98% for selenite, 72-91% for selenate, and 60-96% for organic selenide. For particulate selenium, model-simulated estuarine profiles duplicated the observed behavior of total particulate selenium (76-93%), elemental selenium (80-97%), selenite + selenate (77-82%), and organic selenide (70-83%). Discrepancies between model simulations and the observed data provided insights into the estuarine biogeochemical cycle of selenium that were largely unknown (e.g., adsorption/desorption). Forecasting simulations investigated how an increase in the discharge from the San Joaquin River and varying refinery inputs affect total dissolved and particulate selenium within the estuary. These model runs indicate that during high river flows the refinery signal is undetectable, but when river flow is low (70- day residence time) total particle-associated selenium concentrations can increase to \u3e2 µg g-1 . Increasing the San Joaquin River discharge could also increase the total particle-associated selenium concentrations to \u3e1 µg g-1 . For both forecasting simulations, particle-associated selenium was predicted to be higher than current conditions and reached levels where selenium could accumulate in the estuarine food web

Numerical Studies on the Impact of Ionized Residual Gas on an Electron Beam in an ERL

Energy Recovery Linacs ERLs are the most promising candidates for next generation light sources now under active development. An optimal performance of these machines requires the preservation of the high beam brightness generated in the injector. For this, the impact of the ionized residual gas on the beam has to be avoided as it causes instabilities and emittance growth. Typical measures to reduce the effect of ion clouds are clearing electrodes and clearing gaps in the bunch train. In this paper, we present numerical studies of the impact of ion clouds on the electron bunch train. The simulations are performed with the software package MOEVE PIC Tracking developed at Rostock University. The model for the bunch and the ion cloud takes into account a distribution of macro particles. The interaction of the bunch with the ion cloud is computed with a 3D space charge model. Hence, particle tracking allows for detailed studies of bunch characteristics such as the emittance. The presented numerical investigations take into account the parameters of the ERL BERLinPro with the objective to deduce appropriate measures for the design and operation of BERLinPr

Investigation of Microbunching instability in BERLinPro

BERLinPro is using the new energy recovery linac technology. As, maintaining the low emittance and energy spread is of major importance in an ERL, the deep understanding and control of effects which can degrade the emittance and energy spread such as space charge effects are of interest. The microbunching caused by the longitudinal space charge forces can lead to an increase in emittance and energy spread in the arcs of the loop. In this contribution, the impacts of the microbunching instability on the beam quality and its implication for BERLinPro are discusse

Simulation of the Behavior of Ionized Residual Gas in the Field of Electrodes

Light sources of the next generation such as ERLs require minimal beam losses as well as a stable beam position and emittance over the time. Instabilities caused by ionized residual gas have to be avoided. In this paper we present simulations of the behavior of ionized residual gas in the field of clearing electrodes and investigate e.g. clearing times. For these simulations we apply MOEVE PIC Tracking developed at Rostock University. We demonstrate numerical results with parameters planed for the ERL BERLinPr

Numerical Studies on the Influence of Fill Patterns on Ion Clouds

Energy Recovery Linacs ERLs are the most promising candidates for next generation light sources now under active development. An optimal performance of these machines requires the preservation of the high beam brightness generated in the injector. For this, the impact of the ionized residual gas on the beam has to be avoided as it causes instabilities and emittance growth. Obviously, the vacuum chamber has to be cleared out of ions but as the potential of the electron beam attracts the ions, it is not enough to install vacuum pumps. One measure for ion clearing are gaps in the bunch train long enough that the ions have time to escape the force of the bunch potential. In this paper, we present numerical studies of the behavior of an ion cloud that interacts with a bunch train. Especially, we consider different distributions for the particles in the bunch, different fill patterns and several mixtures of ions in the residual gas. The simulations are performed with the package MOEVE PIC Tracking. The presented numerical investigations take into account the parameters of the ERL BERLinPro with the objective to deduce appropriate measures for the design and operation of BERLinPr

HGHG Scheme for FLASH II

FLASH II is a major extension of the existing FLASH facility at DESY. It has been proposed in collaboration with the Helmholtz Zentrum Berlin HZB . FLASH II is a seeded FEL in the parameter range of FLASH. The final layout of the undulator section of FLASH II allows for different seeding schemes. So that seeding with an HHG source as well as seeding in cascaded HGHG scheme and several combination of these schemes are possible. However, for the shortest wavelengths down to 4 nm the cascaded HGHG scheme is considered. It consists of two frequency up conversion stages utilizing a Ti Sa laser based seeding source in deep UV range. We present and discuss start to end simulation studies for the shortest wavelength generated in the HGHG cascade of FLASH I