ALBERT

Notes: Planktivory by fingerling kokanee Oncorhynchus nerka feeding on Daphnia became more size-selective with increased illumination (0·1 v. 15 lux). The average difference in length of Daphnia (D. pulex and D. galeata) in trial arenas before and after kokanee feeding was 0·107 mm (P = 0·0007) at 0·1 lux and 0·371 mm (P 〈 0·0001) at 15 lux.

Notes: SUMMARYY 1. A total of 2.7 × 106 walleye fingerlings and 1.7 × 105 northern pike fingerlings were stocked during 1987–99 in eutrophic Lake Mendota. The objectives of the biomanipulation were to improve sport fishing and to increase piscivory to levels that would reduce planktivore biomass, increase Daphnia grazing and ultimately reduce algal densities in the lake. The combined biomass of the two piscivore species in the lake increased rapidly from 〈 1 kg ha−1 and stabilised at 4–6 kg ha−1 throughout the evaluation period.2. Restrictive harvest regulations (i.e. increase in minimum size limit and reduction in bag limit) were implemented in 1988 to protect the stocked piscivores. Further restrictions were added in 1991 and 1996 for walleye and northern pike, respectively. These restrictions were essential because fishing pressure on both species (especially walleye) increased dramatically during biomanipulation.3. Commencing in 1987 with a massive natural die-off of cisco and declining yellow perch populations, total planktivore biomass dropped from about 300–600 kg ha−1 prior to the die-off and the fish stocking, to about 20–40 kg ha−1 in subsequent years. These low planktivore biomasses lasted until a resurgence in the perch population in 1999.4. During the period prior to biomanipulation when cisco were very abundant, the dominant Daphnia species was the smaller-bodied D. galeata mendotae, which usually reached a biomass maximum in June and then crashed shortly thereafter. Beginning in 1988, the larger-bodied D. pulicaria dominated, with relatively high biomasses occurring earlier in the spring and lasting well past mid-summer of many years.5. In many years dominated by D. pulicaria, Secchi disc readings were greater during the spring and summer months when compared with years dominated by D. galeata mendotae. During the biomanipulation evaluation period, phosphorus (P) levels also changed dramatically thus complicating our analysis. Earlier research on Lake Mendota had shown that Daphnia grazing increased summer Secchi disc readings, but P concentrations linked to agricultural and urban runoff and to climate-controlled internal mixing processes were also important factors affecting summer readings.6. The Lake Mendota biomanipulation project has been a success given that high densities of the large-bodied D. pulicaria have continued to dominate for over a decade, and the diversity of fishing opportunities have improved for walleye, northern pike and, more recently, yellow perch.7. Massive stocking coupled with very restrictive fishing regulations produced moderate increases in piscivore densities. Larger increases could be realised by more drastic restrictions on sport fishing, but these regulations would be very controversial to anglers.8. If the lake's food web remains in a favourable biomanipulation state (i.e. high herbivory), further improvements in water clarity are possible with future reductions in P loadings from a recently initiated non-point pollution abatement programme in the lake's drainage basin.

Notes: We are exploring a new approach for heavy-ion beam injection (e.g., into the relativistic heavy-ion collider at BNL), as well as new sources of intense high charge state ions to be mounted on a relatively low voltage platform for high energy ion implantation. While conventional metal vapor vacuum arc (Mevva) ion sources can produce up to hundreds of milliamps or more of several-times-ionized metal ions (e.g., U3+), the recent results from Batalin et al. indicate that the addition of an energetic electron beam may lead to considerably higher charge states. An alternative way to produce the electron beam is where a Z-discharge plasma is used to enhance multiple ionization. As the vacuum arc plasma plume expands into a magnetized drift region, a Z-discharge is triggered in the drifting metal plasma. The ions are then extracted and analyzed using a time-of-flight system. We report initial results using these schemes with applied discharge and electron beam voltages from 1 to 2 kV. © 1998 American Institute of Physics.

Notes: Numerous approaches to the production of intense beams of highly charged heavy ions are compared and contrasted. The competing processes of ionization and electron capture are described and evaluated to explore ways to further improve upon the encouraging recent results from electron-beam (E-MEVVA) and low-impedance Z-discharge (LIZ-MeV) variations on the venerable metal vapor vacuum arc (MEVVA) ion source. © 2002 American Institute of Physics.

Notes: Abstract The CEPPAD Experiment consists of four sensors for investigating energetic particle phenomena on the POLAR mission. These sensors provide 3-D proton and electron angular distributions in the energy range of 20 keV to 1 MeV, energetic proton and electron measurements extending to energies greater than 10 MEV, high angular and time resolution measurements in the loss-cone, and data on energetic neutral particles. All sensors operate in conjunction with special on-board data processing units which control sensor data acquisition modes while performing in-flight data processing, data compression, and telemetry formatting. Presented here is a CEPPAD system overview together with descriptions of the individual sensors, the in-flight data processing, and examples of sensor calibration data.

Notes: Abstract The quasimolecular 1sσ-2pπ transition energy as function of the internuclear distance is obtained for the first time in a direct way from the interference structure observed in quasimolecularK x-ray spectra from low energy (2.5, 5, 10 and 20 MeV) Cl16+ on Ar collisions at fixed impact parameter. The experimental results are in fair agreement with quasimolecular transition energies calculated with a two-center potential.

Notes: Abstract The impact parameter (b) dependence of K-shell vacancy production probability for 1,5 MeV/u Nb on Mo collisions has been measured. Consistent with previous experiments on other high Z collision systems, the shape of the b-dependence shows significant deviations from the two-state 2p≪-2pσ rotational coupling model.

Notes: The thermal reaction of equimolar quantities of isophthalonitrile and o-carborane has been shown to produce an adduct oligomer of isophthalonitrile. The structure was determined to involve condensation of three to five isophthalonitrile molecules to form a triazine-type system. This type of bonding gave rise to a trimer and pentamer. Further, the reaction was a homogeneous liquid phase reaction in which o-carborane is involved in a catalytic manner in the oligomerization. The overall reaction has first-order kinetics with an activation energy of 32.2 kcal/mole.