Papers by Jonathan Thompson
Journal of Physics Condensed Matter, Feb 16, 2011
The physical properties including magnetic susceptibility, specific heat, and electrical resistiv... more The physical properties including magnetic susceptibility, specific heat, and electrical resistivity of two new plutonium compounds Pu2M3Si5 (M = Co, Ni) are reported. Pu2Ni3Si5 crystallizes in the orthorhombic U2Co3Si5 structure type, which can be considered a variant of the BaAl4 tetragonal structure, while Pu2Co3Si5 adopts the closely related monoclinic Lu2Co3Si5 type. Magnetic order is observed in both compounds, with Pu2Ni3Si5 ordering ferromagnetically at TC = 65 K then undergoing a transition into an antiferromagnetic state below TN = 35 K. Two successive magnetic transitions are also observed at Tmag1 = 38 K and Tmag2 = 5 K in Pu2Co3Si5. Specific heat measurements reveal that these two materials have a moderately enhanced Sommerfeld coefficient γ ~ 100 mJ/mol Pu K2 in the magnetic state with comparable RKKY and Kondo energy scales.
We present an intra-annual study of short-period, mesospheric gravity wave events observed over A... more We present an intra-annual study of short-period, mesospheric gravity wave events observed over Antarctica in the near infrared OH emission. The measurements were made using an all-sky airglow imager operated at either Halley Station on the Brunt Ice Shelf, or Rothera Station, situated on the Antarctic Peninsula. A total of six austral winter seasons have been analyzed (2000-2006). This study comprises the first detailed winter seasonal investigation of short-period mesospheric gravity waves at high-Antarctic latitudes. Distributions of their observed wave parameters were found to be similar to previous findings using imaging instrumentation at other latitudes in the Northern and Southern Hemispheres. However, the observed wave headings exhibited strong, but dissimilar anisotropy at both sites that was also found to be repetitive from year to year, establishing a persistent recurrent pattern. In this poster we present example wave data and seasonal summaries of their properties at both observing sites focusing on wave anisotropy and the strong year to year consistency.
Proceedings of the 12th European Conference on Evolutionary Computation in Combinatorial Optimization, Apr 11, 2012
ABSTRACT The vehicle routing problem with pickups, deliveries and time windows (PDPTW) is an impo... more ABSTRACT The vehicle routing problem with pickups, deliveries and time windows (PDPTW) is an important member in the class of vehicle routing problems. In this paper a general heuristic to construct an initial feasible solution is proposed and compared with other construction methods. New route reconstruction heuristics are then shown to improve on this. These reconstruction heuristics look to reorder individual routes and recombine multiple routes to decrease the number of vehicles used in the solution. A tabu search scheme where the attribute to be recorded has been specifically adapted to the PDPTW is proposed. A new method based on branch and bound optimisation attempts to optimise the final ordering of requests in routes to further improve the solutions. Results are analysed for a standard set of benchmark instances and are shown to be competitive with the state of the art.
Http Dx Doi Org 10 1080 03067319 2012 746323, Oct 21, 2013
ABSTRACT The aqueous phase nitration of benzoic acid and phenol was investigated via on-line capi... more ABSTRACT The aqueous phase nitration of benzoic acid and phenol was investigated via on-line capillary electrophoresis (CE). The presence of nitrated benzoic acid and phenol was supported through appearance of corresponding molecular ion peaks in ESI-MS measurements, and speciation of the nitrated isomers is achieved via the on-line CE method. The nitrated isomers produced in both reactions were successfully separated in <4 min by addition of 15 mM β-cyclodextrin to the electrophoresis buffer. Sequential separations (on-line analysis) allowed the reaction kinetics to be described. For benzoic acid, reaction yields were low (2–3%) however, results suggest both 3- and 2-nitrobenzoic acid form in a 1–1.4 concentration ratio. In addition, 3-hydroxybenzoic acid also forms in significant quantity under our reaction conditions. For the nitration of phenol, the reaction occurred more rapidly with observed yields between ≈10–30% for individual isomers. The yield of 2-nitrophenol was higher than 4-nitrophenol by a ratio of ≈ 1.7–2, but 3-nitrophenol was not detected. For both reactions, nitrated and hydroxylated aromatics were the major products and formation of higher molecular weight oligomers was not observed.
Southern Medical Journal, May 1, 2011
Lithium is known for its efficacy and toxicity. Toxic effects have been characterized even with t... more Lithium is known for its efficacy and toxicity. Toxic effects have been characterized even with therapeutic levels. Most physicians will at some point be faced with a patient with altered mental status and no records of his or her history. The differential diagnosis of altered mental status is long, and further lengthens in a patient with a psychiatric history. Since several life-threatening complications of psychotropic medications exist, physicians must be astute with their diagnoses. Lithium toxicity, neuroleptic malignant syndrome, and the serotonin syndrome can present similarly and require rapid recognition. We present a case of lithium toxicity in a patient who presented with altered mental status and a paucity of history information.
Anal Chem, 1998
Optically gated capillary electrophoresis (CE) of amino acids derivatized with o-phthalaldehyde/β... more Optically gated capillary electrophoresis (CE) of amino acids derivatized with o-phthalaldehyde/β-mercaptoethanol (OPA/β-ME) was explored as a means to monitor amino acids with high temporal resolution. In agreement with a theoretical model described herein, 98% of a given concentration of OPA/β-ME derivatives can be photobleached by a few milliwatts of the 350-nm line of an argon ion laser with just 0.7-ms exposure times in 5-μm-i.d. capillaries. The low background from such high photobleaching efficiency allows detection limits in the low-nanomolar range for all amino acids tested. The short injection times possible with optical gating allow separation efficiencies of nearly 200 000 plates to be achieved in less than 1 s under ideal conditions. Under mock in vivo conditions, separations were slower and had lower efficiency due to reduced electroosmotic flow associated with the high salt content. To demonstrate chemical monitoring, the optically gated CE system was interfaced to two different sampling probes with on-line derivatization with OPA/β-ME. With microdialysis sampling, the optically gated CE system could assay the sample stream every 2 s but actual temporal resolution for monitoring was limited by band broadening in the dialysis probe to ∼12 s. Optically gated CE was also interfaced to a 10-μm-i.d. sampling capillary that continuously pulled samples into the separation capillary at 6.5 nL/min. This direct sampling probe allowed monitoring of multiple amino acids with 10-s temporal resolution with several advantages compared to microdialysis including improved detection limits and spatial resolution.
Lecture Notes in Computer Science, 1996
Abstract. The precise nature of the examination timetabling problem differs from institution to i... more Abstract. The precise nature of the examination timetabling problem differs from institution to institution. Thus any general solution method must be suitably flexible and this paper is concerned with finding robust cooling schedules for a simulated annealing based approach. The ...
Ammonia is present within earth's atmosphere at low ppb - ppm concentrations. Ammonia is know... more Ammonia is present within earth's atmosphere at low ppb - ppm concentrations. Ammonia is known to play an important role in atmospheric and biogeochemical processes. Monitoring the concentration of ammonia in the ambient air near agricultural operations is of particular interest due to the large source strength. Indeed, domestic animals, agricultural crops, and fertilizers are believed to account for over 40 Tg of ammonia nitrogen emissions each year. We have explored use of 216 μm o.d. and 200 μm i.d. regenerated cellulose (RC) microdialysis tubes as sampling probes for ammonia. The gas diffuses through the permeable probe into a stream of deionized water which continually perfused the tubing at 10 - 20 μL/ min. The ammonium collected was analyzed through a fluorimetric method (OPA-sulfite) with LED excitation at 365 nm and measurement of fluorescence emission at 425 nm. Since the sampling probe exhibits a very high surface area to volume ratio (approx. 200 cm2 / mL), the fiber...
Open Journal of Air Pollution, 2012
ABSTRACT This paper provides a mathematical treatment of the NP-hard post enrolment-based course ... more ABSTRACT This paper provides a mathematical treatment of the NP-hard post enrolment-based course timetabling problem and presents a powerful two-stage metaheuristic-based algorithm to approximately solve it. We focus particularly on the issue of solution space connectivity and demonstrate that when this is increased via specialised neighbourhood operators, the quality of solutions achieved is generally enhanced. Across a well-known suite of benchmark problem instances, our proposed algorithm is shown to produce results that are superior to all other methods appearing in the literature; however, we also make note of those instances where our algorithm struggles in comparison to others and offer evidence as to why.
Talanta, 2010
We have explored use of perfused regenerated cellulose (RC) microdialysis tubing (216microm o.d./... more We have explored use of perfused regenerated cellulose (RC) microdialysis tubing (216microm o.d./200microm i.d.) as sampling probes for gaseous ammonia. The probes functioned by allowing the gas to diffuse through the permeable membrane into a stream of de-ionized water which continually perfused the tubing at 10-20microLmin(-1). The resulting ammonium in the perfusate was determined through a fluorimetric method (OPA-sulfite) with LED excitation at lambda(ex)=365+/-10nm and measurement of fluorescence emission at lambda(em)=425+/-20nm. By shielding the sampling membrane with a Plexiglas tube purged under laminar flow conditions, the potential interference of particulate ammonium depositing on the probe was minimized. The RC microdialysis tube was found to act as an efficient sampling device since it exhibits a very high surface-area-to-volume ratio (approximately 200cm(2)mL(-1)). As a result, aqueous concentrations of >100microM NH(4)(+) per ppm NH(3) (g) have been observed. In addition, the fluorogenic OPA-sulfite reaction is demonstrated to be very selective for ammonia over amines that have been measured in the atmosphere. This feature of the derivatization chemistry allows analysis of ammonia by fluorimetry without need for a separation step. The method developed has been applied to field measurements of ammonia at a swine barn facility with quantitative results agreeing with a reference method.
ABSTRACT The vehicle routing problem with pickups, deliveries and time windows (PDPTW) is an impo... more ABSTRACT The vehicle routing problem with pickups, deliveries and time windows (PDPTW) is an important member in the class of vehicle routing problems. In this paper a general heuristic to construct an initial feasible solution is proposed and compared with other construction methods. New route reconstruction heuristics are then shown to improve on this. These reconstruction heuristics look to reorder individual routes and recombine multiple routes to decrease the number of vehicles used in the solution. A tabu search scheme where the attribute to be recorded has been specifically adapted to the PDPTW is proposed. A new method based on branch and bound optimisation attempts to optimise the final ordering of requests in routes to further improve the solutions. Results are analysed for a standard set of benchmark instances and are shown to be competitive with the state of the art.
The Wilson Journal of Ornithology, 2012
Uploads
Papers by Jonathan Thompson