Magnetic configuration studies in a Compact Torsatron

An overview is presented of an experimental program of magnetic field line mapping on the research-grade Compact Auburn Torsatron (CAT). The vacuum magnetic flux surfaces of the CAT device have been experimentally mapped in a variety of magnetic configurations. The results are compared with an extensive computer model in order to validate the coil design. In initial field mapping experiments, an up-down asymmetry was identified in the vacuum magnetic surfaces, and was corrected with the use of a radial trim field. Magnetic islands are observed and their size has been reduced, also through the use of auxiliary trim coils. The Compact Auburn Torsatron is equipped with two pairs of large Helmholtz coils producing mutually orthogonal magnetic fields in the horizontal plane, and two pairs of helical saddle coils wound directly on the toroidal vacuum vessel. These trim coils are used to control the size and phase of the t=1/2 magnetic island. Through a systematic variation of trim field components, we demonstrate a reduction of the inherent t=1/2 magnetic island size by a factor of three. The technique is applicable to correcting small error fields in larger helical confinement devices. The measurements of island size are compared with measurements of magnetic field line rotation within the island, and are found to be in good agreement with first-order perturbation theory.     

Hippocampal seizures disrupt working memory performance but not reference memory acquisition.

The effect of hippocampal seizures in rats was assessed in two spatial memory tasks: The reference memory task was a simultaneous two-choice discrimination in a T-maze. The working memory task was a delayed conditional discrimination in a radial arm maze. In each task the hippocampus of each rat was stimulated to seizure after the presentation of the information to be remembered. In the reference memory task, hippocampal seizures did not impair acquisition, whether the stimulation was given immediately after or 4 hr after the presentation of the stimuli to be remembered. In the working memory task, hippocampal seizures did impair performance in a group of the same rats. These results support the distinction between a trial-dependent working memory system that requires hippocampal function and a trial-independent memory system that does not depend on hippocampal function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The evolution of interspecific mutualisms

Interspecific mutualisms are widespread, but how they evolve is not clear. The Iterated Prisoner's Dilemma is the main theoretical tool to study cooperation, but this model ignores ecological differences between partners and assumes that amounts exchanged cannot themselves evolve. A more realistic model incorporating these features shows that strategies that succeed with fixed exchanges (e. g., Tit-for-Tat) cannot explain mutualism when exchanges vary because the amount exchanged evolves to 0. For mutualism to evolve, increased investments in a partner must yield increased returns, and spatial structure in competitive interactions is required. Under these biologically plausible assumptions, mutualism evolves with surprising ease. This suggests that, contrary to the basic premise of past theoretical analyses, overcoming a potential host's initial defenses may be a bigger obstacle for mutualism than the subsequent recurrence and spread of noncooperative mutants.     

Naturally occurring dual infection with human and bovine rotaviruses as suggested by the recovery of G1P8 and G1P5 rotaviruses from a single patient

Culture adaptation of rotaviruses from an infant with severe diarrhea in Cincinnati, Ohio, yielded not only a virus with the original RNA electropherotype (CJN) but also rotaviruses with other electropherotypes, the most dominant of which was called CJN-M [Ward RL, Knowlton DR, Schiff GM, Hoshino Y, Greenberg HB (1988) in J Virol 62: 1543-1549]. RNA-RNA hybridization and sequencing studies indicated that CJN was a typical G1P8 human rotavirus while CJN-M was a G1P5 strain and contained four gene segments (including segment 4) of a bovine rotavirus. Thus, the infant was apparently dually infected with human and bovine rotaviruses.     

Remembering and knowing: Two different expressions of declarative memory.

Amnesic patients and a control group were given a recognition test 10 min after studying words. For each recognized word, participants indicated whether they remembered it (R) or whether simply they knew that the word was presented but had no recollections about it (K). The patients were impaired for both R and K responses, performing like a control group tested after 1 week. Another control group was tested both 10 min and 1 week after study. The proportion of words initially eliciting an R response and later eliciting a K response exceeded the proportion of K responses that shifted to R responses. These data are accounted for if items initially eliciting R responses can also elicit K responses. We conclude that the R–K distinction does not reflect the operation of explicit and implicit memory but reflects instead a distinction within declarative memory. Thus, K responses depend on brain structures damaged in amnesia; R responses depend on these same structures and also on the frontal lobes for contextual information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of relocation on locomotion and cleanliness in dairy cows

This study was conducted to determine the effect that relocation to a new free stall barn had on locomotion and cleanliness of two breeds of dairy cows. The original facility before relocation had cows housed in an 8-row free stall barn. Cows were allocated in a new 4-row free stall facility: cows of two breeds (n=22 Holsteins and 22 Jerseys) were intermixed in the northwest section. Locomotion (scale 1-5) and cleanliness were scored (scale 1-4). Holsteins and Jerseys had no difference in locomotion score throughout 12 weeks following relocation. A lactation number by date interaction showed cows in third and greater lactations had significantly higher locomotion scores (more lameness) by day 86. Locomotion scores increased across breeds during the 86-d observation period, suggesting cows became lamer. Jerseys had cleaner lower legs than Holsteins (2.9+/-0.1 v. 3.5+/-0.1, respectively). Lactation number affected lower leg cleanliness, with scores decreasing as lactation number increased (3.4 v. 3.3 v. 2.9+/-0.10 for first, second and third and greater lactations, respectively; P<0.01). All cows were cleaner (lower scores) after relocation, suggesting that the new facility improved hygiene.     

Intrusive probes in riser applications

Many of the probes used to understand hydrodynamics in circulating fluidized bed risers intrude into the environment they are measuring, although assumptions are typically asserted that the intrusive probes do not affect the data collected. This could be a poor assumption in some cases and conditions. We found that intrusive fiber‐optic probe measurements consistently mis‐predicted the solids concentration compared to the nonintrusive pressure drop measurements outside the fully developed flow region of a riser containing fluid catalytic cracking catalyst or glass bead particles. The discrepancy was sensitive to superficial gas velocity, solid circulation rate, probe position, and flow direction. Barracuda VR? computational fluid dynamics simulations confirmed this, and indicated that particle momentum was lost at the leading edge of the probe and particles were spilling over to the probe tip. Accordingly, new probe designs were proposed to mitigate the intrusiveness of a fiber‐optic probe for more accurate characterization. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5361–5374, 2017     

Use of Potassium for Treatment and Control of Zebra Mussel Infestation in Industrial Fire Protection Water Systems

Zebra mussels, first discovered in the Great Lakes in 1988, have frequently been detected in fire protection systems. However, the potential for large-scale infestations has not been established. It is clear that even small numbers of mussels can cause problems in areas that have small-diameter piping or in sprinkler system nozzles, if shells are flushed down-stream during emergency use.This paper will discuss the development of a method of zebra mussel control that limited interference with normal system operations when used at Niagara Mohawk's Dunkirk Steam Station. Because oxygen is often depressed in these systems and limits mussels survival and growth, it was established that by monitoring oxygen alone, or in combination with veliger or mussel larval monitoring, high-risk areas for mussel infestation could be determined. In previous laboratory research, it had already been determined that concentrations of potassium in excess of 100 mg/L would lead to quick mortality in adult zebra mussels. These results, along with a biofouling risk assessment completed at Dunkirk Steam Station, were used to develop and implement a successful treatment of the high-risk areas in the plant's fire protection water systems using potassium in the form of potash as the controlling agent.