Observations on the action of botulin toxin: with a note on grass disease in horses

That Bacillus Botulinus is the cause of a type of food poisoning giving rise to a definite set of symptoms was first demonstrated by van Ermengem in 1895. In that year an outbreak of food poisoning occurred affecting twenty people who had partaken_ of a ham. The ham which was available for investigation was found not to be in a decomposed condition, though it had a somewhat rancid smell. Inoculations from this meat into animals produced typical symptoms in rabbits, guinea pigs, apes and pigeons. The symptoms included paralysis and eye symptoms such as ptasis and unequal pupils. Van Ermengem then proceeded on bacteriological lines and as a result of his work he isolated from the ham and from the spleen of one of his patients who died an organism which on culture produced a very virulent poison. The symptoms produced corresponded to those of the original disease. This organism van Ermengem named Bacillus botulinus. From that time the disease as been known as Botulism. Though the cause of this type of food poisoning was thus established,the disease must have been known for a considerable time previous to 1895. The earliest published accounts seem to be those of Justinus Kerner , a Schwabian physician. In 1820 he issued an account of the disease occurring in Wiírtemberg. According to this author the earliest described cases occurred in the year 1793. From this date and until the discovery of Bacillus botulinus the disease was known as Sausage poisoning. Other records of a similar disease occurring prior to 1895 exist, but the literature is only of historical interest. The more modern literature on botulism during the last fifteen or twenty years has come mainly from work carried out in the United States where a very large number of cases of botulism have occurred. During the last three or four years especially a number of very important contributions have been made to the literature of the subject

Neutral density map of Hall thruster plume expansion in a vacuum chamber

A neutral background pressure map of the large vacuum test facility (LVTF) is presented. The LVTF is mapped at cold anode flow rates of 5.25, 10.46, and 14.09 mg/s14.09mg∕s. In addition, neutral background pressure maps are created at hot anode (i.e., discharge on) flow rates of 5.25 and 10.46 mg/s10.46mg∕s for discharge voltages of 300 and 500 V500V, corresponding to P5 Hall thruster operating conditions ranging from 1.5 to 5.0 kW1.5to5.0kW. The chamber pressure is mapped at nominal xenon pumping speeds of 140 000 and 240 000 l/s240000l∕s. The pressure map is performed with a rake consisting of five calibrated Bayard–Alpert hot-cathode ionization gauges. The plume expansion appears to be independent of anode flow rate and facility background pressure. Analysis of axial pressure profiles on the LVTF’s centerline shows that the plume pressure decreases from a maximum at the thruster exit plane down to the facility background pressure at approximately 2 m2m downstream of the exit plane. Comparison of axial pressure profiles on the LVTF’s centerline shows that the neutral density is nearly the same for cold flow and hot flow. The study shows that a cold flow neutral density background map accurately characterizes the neutral density in an operating Hall thruster plume.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87890/2/053509_1.pd

Hall Thruster Cluster Operation with a Shared Cathode

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76373/1/AIAA-23688-572.pd

The Effects of Nude Faraday Probe Design and Vacuum Facility Backpressure on the Measured Ion Current Density Profile of Hall Thruster Plumes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76894/1/AIAA-2002-4253-511.pd

Computation of Neutral Gas Flow From a Hall Thruster Into a Vacuum Chamber

The finite pressure present in vacuum chamber testing of space propulsion systems such as Hall thrusters can have a number of undesirable effects. For example, the thrust generated by the thruster is higher and the plume divergence angle larger in ground tests in comparison to space operation. To try to quantify these effects, the direct simulation Monte Carlo method is applied to model a cold flow of xenon gas expanding from a Hall thruster into a vacuum chamber. The simulations are performed for the P5 Hall thruster operating in a large vacuum tank at the University of Michigan. Comparison of the simulation results is made with experimental measurements of pressure obtained with a series of ion gauges. The mass flow rate through the thruster and the total pumping speed of the vacuum chamber are varied. A key physical parameter in the simulations concerns the probability that a xenon atom incident on a cryogenic pumping panel actually sticks to the panel. For a reasonable range of values for the sticking coefficient, excellent agreement between simulation and experiment is obtained for several different conditions. © 2003 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87929/2/541_1.pd

Pressure Map of a Facility as a Function of Flow Rate to Study Facility Effects

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76369/1/AIAA-2002-3815-510.pd

Effect of Backpressure on Ion Current Density Measurements in Hall Thruster Plumes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76301/1/AIAA-7713-781.pd

Magnetically filtered Faraday probe for measuring the ion current density profile of a Hall thruster

The ability of a magnetically filtered Faraday probe (MFFP) to obtain the ion current density profile of a Hall thruster is investigated. The MFFP is designed to eliminate the collection of low-energy, charge-exchange (CEX) ions by using a variable magnetic field as an ion filter. In this study, a MFFP, Faraday probe with a reduced acceptance angle (BFP), and nude Faraday probe are used to measure the ion current density profile of a 5 kW5kW Hall thruster operating over the range of 300–500 V300–500V and 5–10 mg/s5–10mg∕s. The probes are evaluated on a xenon propellant Hall thruster in the University of Michigan Large Vacuum Test Facility at operating pressures within the range of 4.4×10−4 Pa4.4×10−4Pa Xe (3.3×10−6 Torr3.3×10−6Torr Xe) to 1.1×10−3 Pa1.1×10−3Pa Xe (8.4×10−6 Torr8.4×10−6Torr Xe) in order to study the ability of the Faraday probe designs to filter out CEX ions. Detailed examination of the results shows that the nude probe measures a greater ion current density profile than both the MFFP and BFP over the range of angular positions investigated for each operating condition. The differences between the current density profiles obtained by each probe are attributed to the ion filtering systems employed. Analysis of the results shows that the MFFP, operating at a +5 A+5A solenoid current, provides the best agreement with flight-test data and across operating pressures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87898/2/013503_1.pd

LANDMAP: Serving Satellite imagery to the UK academic Community

The LANDMAP Project has created the first IfSAR DEM covering the entire British Isles. That DEM and associated orthorectified ERS images were used to produce a set of orthorectified images of the British Isles from LANDSAT and SPOT. Additional merged and mosaiced images were also created with the three different satellite products. The dataset includes images stored as files in Geo-TIFF format. This paper discusses the data creation process and presents the methods of serving these data to the user community

Ion Collection in Hall Thruster Plumes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77342/1/AIAA-11953-462.pd