Effect of Improving the Lattice Gauge Action on QCD Topology

We use lattice topology as a laboratory to compare the Wilson action (WA) with the Symanzik-Weisz (SW) action constructed from a combination of (1x1) and (1x2) Wilson loops, and the estimate of the renormalization trajectory (RT) from a renormalization group transformation (RGT) which also includes higher representations of the (1x1) loop. Topological charges are computed using the geometric (L\"uscher's) and plaquette methods on the uncooled lattice, and also by using cooling to remove ultraviolet artifacts. We show that as the action improves by approaching the RT, the topological charges for individual configurations computed using these three methods become more highly correlated, suggesting that artificial lattice renormalizations to the topological susceptibility can be suppressed by improving the action.Comment: 4 pages, 4 figures, poster presented at LATTICE96(improvement

Geometric Measurement of Topological Susceptibility on Large Lattices

The topological susceptibility of the quenched QCD vacuum is measured on large lattices for three $\beta$ values from $6.0$ to $6.4$. Charges possibly induced by $O(a)$ dislocations are identified and shown to have little effect on the measured susceptibility. As $\beta$ increases, fewer such questionable charges are found. Scaling is checked by examining the ratios of the susceptibility to previously existing values of the rho mass, string tension, F-pi, and lambda-lattice.Comment: LaTeX article, 3 pages, uuencoded compressed tar file, 2 figures included as tex files using axismacros, DVIPS driver required to show figures. Talk presented by Jeffrey Grandy at Lattice 93, Dallas, Texas. Los Alamos Preprint number pendin

Failure of Intravenous Morphine to Serve as an Effective Instrumental Reinforcer in Dopamine D2 Receptor Knock-Out Mice

The rewarding effects of opiates are thought to be mediated through dopaminergic mechanisms in the ventral tegmental area, dopamine-independent mechanisms in the nucleus accumbens, or both. The purpose of the present study was to explore the contribution of dopamine to opiate-reinforced behavior using D2 receptor knock-out mice. Wild-type, heterozygous, and D2 knock-out mice were first trained to lever press for water reinforcement and then implanted with intravenous catheters. The ability of intravenously delivered morphine to maintain lever pressing in these mice was studied under two schedules of reinforcement: a fixed ratio 4 (FR4) schedule (saline, 0.1, 0.3, or 1.0 mg/kg, per injection) and a progressive ratio (PR) schedule (1.0 mg/kg, per injection). In the wild-type and heterozygous mice, FR4 behavior maintained by morphine injections was significantly greater than behavior maintained by vehicle injections. Response rate was inversely related to injection dose and increased significantly in the wild-type and heterozygous mice when the animals were placed on the PR schedule. In contrast, the knock-out mice did not respond more for morphine than for saline and did not respond more when increased ratios were required by the PR schedule. Thus, morphine served as a positive reinforcer in the wild-type and heterozygous mice but failed to do so in the knock-out mice. Under this range of doses and response requirements, the rewarding effects of morphine appear to depend critically on an intact D2 receptor systemFil: Elmer, Greg I.. University of Maryland; Estados UnidosFil: Pieper, Jeanne O.. National Institutes of Health; Estados UnidosFil: Rubinstein, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Low, Malcolm J.. Oregon Health and Sciences University; Estados UnidosFil: Grandy, David K.. Oregon Health and Sciences University; Estados UnidosFil: Wise, Roy A.. National Institutes of Health; Estados Unido

Conditioned place preference and locomotor activity in response to methylphenidate, amphetamine and cocaine in mice lacking dopamine D4 receptors

Methylphenidate (MP) and amphetamine (AMPH) are the most frequently prescribed medications for the treatment of attention-deficit/hyperactivity disorder (ADHD). Both drugs are believed to derive their therapeutic benefit by virtue of their dopamine (DA)-enhancing effects, yet an explanation for the observation that some patients with ADHD respond well to one medication but not to the other remains elusive. The dopaminergic effects of MP and AMPH are also thought to underlie their reinforcing properties and ultimately their abuse. Polymorphisms in the human gene that codes for the DA D4 receptor (D4R) have been repeatedly associated with ADHD and may correlate with the therapeutic as well as the reinforcing effects of responses to these psychostimulant medications. Conditioned place preference (CPP) for MP, AMPH and cocaine were evaluated in wild-type (WT) mice and their genetically engineered littermates, congenic on the C57Bl/6J background, that completely lack D4Rs (knockout or KO). In addition, the locomotor activity in these mice during the conditioning phase of CPP was tested in the CPP chambers. D4 receptor KO and WT mice showed CPP and increased locomotor activity in response to each of the three psychostimulants tested. D4R differentially modulates the CPP responses to MP, AMPH and cocaine. While the D4R genotype affected CPP responses to MP (high dose only) and AMPH (low dose only) it had no effects on cocaine. Inasmuch as CPP is considered an indicator of sensitivity to reinforcing responses to drugs these data suggest a significant but limited role of D4Rs in modulating conditioning responses to MP and AMPH. In the locomotor test, D4 receptor KO mice displayed attenuated increases in AMPH-induced locomotor activity whereas responses to cocaine and MP did not differ. These results suggest distinct mechanisms for D4 receptor modulation of the reinforcing (perhaps via attenuating dopaminergic signalling) and locomotor properties of these stimulant drugs. Thus, individuals with D4 receptor polymorphisms might show enhanced reinforcing responses to MP and AMPH and attenuated locomotor response to AMPH.Fil: Thanos, P. K.. NIAAA Intramural Program; Estados Unidos. Brookhaven National Laboratory; Estados Unidos. Universidad de Buenos Aires; ArgentinaFil: Bermeo, C.. Brookhaven National Laboratory; Estados UnidosFil: Rubinstein, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Suchland, K. L.. Oregon Health & Science University; Estados UnidosFil: Wang, G. J.. Brookhaven National Laboratory; Estados UnidosFil: Grandy, David K.. Oregon Health & Science University; Estados UnidosFil: Volkow, N. D.. NIAAA Intramural Program; Estados Unido

The Staggered Eta-prime with Smeared Operators

We present a refined calculation of the eta-prime mass using staggered fermions and Wuppertal smeared operators. We use quenched and dynamical configurations of size 16^3x32 with Nf=0, Nf=2 and Nf=4, and compare our results with the expected forms from quenched, partially quenched and unquenched chiral perturbation thoery.Comment: Talk presented at LATTICE96(chirality in qcd

Development of a Carbon Mesh Supported Thin Film Microextraction Membrane As a Means to Lower the Detection Limits of Benchtop and Portable GC/MS Instrumentation

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.analchem.5b04008.In this work, a durable and easy to handle thin film microextraction (TFME) device is reported. The membrane is comprised of poly(divinylbenzene) (DVB) resin particles suspended in a high-density polydimethylsiloxane (PDMS) glue, which is spread onto a carbon fiber mesh. The currently presented membrane was shown to exhibit a substantially lesser amount of siloxane bleed during thermal desorption, while providing a statistically similar extraction efficiency toward a broad spectrum of analytes varying in polarity when compared to an unsupported DVB/PDMS membrane of similar shape and size which was prepared with previously published methods. With the use of hand-portable GC-TMS instrumentation, membranes cut with dimensions 40 mm long by 4.85 mm wide and 40 ± 5 μm thick (per side) were shown to extract 21.2, 19.8, 18.5, 18,4, 26.8, and 23.7 times the amount of 2,4 dichlorophenol, 2,4,6 trichlorophenol, phorate D10, fonofos, chloropyrifos, and parathion, respectively, within 15 min from a 10 ppb aqueous solution as compared to a 65 μm DVB/PDMS solid phase microextraction (SPME) fiber. A portable high volume desorption module prototype was also evaluated and shown to be appropriate for the desorption of analytes with a volatility equal to or lesser than benzene when employed in conjunction with TFME membranes. Indeed, the coupling of these TFME devices to hand-portable gas chromatography toroidial ion trap mass spectrometry (GC-TMS) instrumentation was shown to push detection limits for these pesticides down to the hundreds of ppt levels, nearing that which can be achieved with benchtop instrumentation. Where these membranes can also be coupled to benchtop instrumentation it is reasonable to assume that detection limits could be pushed down even further. As a final proof of the concept, the first ever, entirely on-site TFME-GC-TMS analysis was performed at a construction impacted lake. Results had indicated the presence of contaminants such as toluene, ethylbenzene, xylene, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and tris(1-chloro-2-propyl)phosphate, which stood out from other naturally occurring compounds detected.the Natural Sciences and Engineering Research Council of Canada (NSERC

Development of Field Portable Solid Phase Microextraction Samplers for Performing On-site Environmental Analysis

Since being introduced in 1989 solid phase microextraction (SPME) techniques have continually evolved from within the analytical chemistry community due in large part to their clean, portable and easy to handle design. It is no surprise then that these devices lend themselves well to on-site sampling approaches making their use in conjunction with field portable instrumentation a growing trend. However, as with any emerging analytical methodology, it is important that these entirely on-site approaches are developed such that they deliver comparably reliable and sensitive results to accepted techniques. As such, presented herein, various novel morphologies and analytical methodologies based on the principles of solid phase microextraction were developed and validated as a means to improve the reliability and sensitivity of on-site environmental analysis. As an opening project, a portable in-vial standard analyte generator capable of delivering a highly reproducible gaseous headspace is proposed. The vial is comprised of a silicone diffusion pump fluid spiked with appropriate calibration or derivatization compounds, such as modified McReynolds probes (benzene, 2-pentanone, pyridine, 1-nitropropane, 1-pentanol, and n-octane) or pentafluorophenyl hydrazine (PFPH), respectively. The spiked silicone oil is then mixed with polystyrene/divinylbenzene (PS/DVB) particles and enclosed in a 20 mL headspace vial. Using the McReynolds calibration mixture, headspace concentrations were found to be substantially decreased in comparison to prior hydrocarbon pump oil based vials hence, the amount of standard loaded onto SPME fibers was at most, half that of the previous vial design. Appropriately, depletion for all compounds after 208 successive extractions was shown to be less than 3.5%. Smaller proportions of standards being used at each extraction resulted in a vial that depleted slower while remaining statistically repeatable over a wider number of runs. Indeed, it was found that this depletion could be predicted using a theoretical, mass-balance model. At a 95 % level of confidence, the ANOVA test demonstrated that prepared vials were statistically identical, with no significant intra- or inter-batch variations. Storage stability in varying conditions such as light exposure and temperature was also validated over 10 weeks for vials prepared with the reactive and unstable, pentafluorophenyl hydrazine in addition to the McReynolds probes. To demonstrate amenability for on-site environmental applications, a battery operated vial oven was constructed and employed in tandem with portable GC/MS instrumentation for the on-site PFPH derivatization and quantitation of formaldehyde from car exhaust. By using a combination of SPME fibers and needle trap devices (NTD’s) the concentration of this formaldehyde in aerosol particles could be determined and differentiated from the free gaseous concentration. Following these validatory experiments, varying standard headspace generating mixtures were continuously used to evaluate the portable GC/MS instrument while providing a means for on-site quality control. As the main accomplishment of this thesis a durable, high surface area, and easy to handle thin film microextraction (TFME) device is proposed. The membrane is comprised of poly-divinylbenzene resin particles suspended in a high-density polydimethylsiloxane glue spread onto a carbon mesh support. This novel design was shown to exhibit a substantially lesser amount of siloxane bleed during thermal desorption while providing a statistically similar extraction efficiency towards a broad spectrum of compounds when compared to an unsupported DVB/PDMS membrane of similar size that had been prepared with former methods. At a 95 % level of confidence, the ANOVA test demonstrated that these membranes were also statistically similar, with no significant intra- or inter-batch variations. In an initial validation, membranes cut to 4 cm long, 4.85 mm wide and coated 30-40 μm thick (per side), were shown to extract 21.2, 19.8, 18.5, 18,4, 26.8, and 23.7 times the amount of 2,4-dichlorophenol 2,4,6-trichlorophenol, phorate-D10, fonofos, chlorpyrifos, and parathion respectively, from a 10 ppb aqueous solution than a comparable 65 μm DVB/PDMS SPME fiber. Following these initial developments, these carbon mesh supported DVB/PDMS membranes were established as highly sensitive, accurate and green alternative to classical liquid-liquid extraction (LLE) for the determination of 23 multi-class pesticides from surface water samples. This signal improvement was made evident by method limits of detections (MLOD’s) in the low ng L -1 range for most of the pesticides studied while only requiring 30 mL of sample. Furthermore, these MLOD’s were shown to be at least 10 times lower than those achieved using an EPA certified, LLE method performed at an accredited analytical laboratory participating in the study. Moreover, the method accuracy was validated through double-blind split analyses of 18 surface water samples. Good agreement between the two methods was achieved with accuracy values between 70-130% for the majority of analytes tested. This methodology was further explored on-site with the design and deployment of a portable TFME sampling case to be used in conjunction with the portable GC/MS instrumentation. Although the chosen pesticides were found to be more-or-less absent from the 4 riparian sampling locations, a wide variety of untargeted compounds could still be detected and identified using the portable TFME-GC-TMS method. As such, the on-site method repeatability was still deemed acceptable with %RSD’s for the untargeted compounds around 20% (n=5). Moreover, by use of a BTEX standard headspace generating vial, the portable GC/MS was shown to remain stable over the entire 1-month sampling period. Furthering the development of carbon mesh supported TFME, a highly sensitive HLB-PDMS thin film microextraction device for the balanced determination of VOC compounds of varying polarity was prepared. In addition to exhibiting a 50+ fold increase in sensitivity when compared to a 65 µm DVB/PDMS SPME fiber, these membranes extracted approximately double the amount of McReynolds probes versus a more comparable DVB/PDMS TF-SPME device of identical size. Inter-membrane extraction efficiencies for these compounds were determined to be reproducible at 95% confidence for all 4 of the coating chemistries tested including the DVB/PDMS membranes, and those prepared with 3 different HLB compositions. Further method reliability was established by confirming that, once extracted, the McReynolds standards were stable on the HLB/PDMS membranes stored in the thermal desorption tubes on the autosampler rack for at least 120 hours for 5 of the 6 standards and only 24 hours for pyridine at 95% confidence. Finally, a real-world proof of concept application determining chlorination by-products from a private hot tub was performed, successfully identifying, 2-chloroethylamine 3-chloro-1-propanamine, and dichloroacetonitrile with %RSD’s less than 10%. Finally, as a side project, the goal of pushing on-site sampler design to its fullest was explored by means of the construction of a self-sealing coated bolt sampler for the analysis of deep ocean environments via divers and ROV submersibles. These samplers employ HLB particles which have been coated onto recessed stainless steel bolts by use of polyacrylonitrile (PAN) glue. 6 coated bolts are then inserted into a self-sealing, polytetrafluoroethylene (PFTE) bodied sampler designed to preserve extracted compounds for extended periods. To verify this stability, 3 samplers were deployed on-site at a waste-water treatment facility outflow pipe via kayak. Post-sampling, the samplers were stored using 3 storage conditions including A: immediate desorption, B: 3 days at 23 oC), C: 12 days at 23 oC and D: 12 days in a -80 oC freezer. All bolts tested were statistically indistinguishable when analyzed using principal component analysis (PCA). Furthermore, 10 randomly selected, volatile, features were also demonstrated to give a statistically identical response at a 95% level of confidence using the ANOVA test. Finally, in a cutting-edge application, these samplers were tailored for use on an ROV submersible and employed for the on-site sampling of hydrothermal vents at 2 locations along the Pacific Rim with 2 corresponding control extractions also performed from ambient waters away from these vents such that significant features could be differentiated. Separation and analysis of all samples were performed using an HPLC equipped orbit-trap mass spectrometer and 100’s of statistically unique features could be determined from the vents by use of multivariate statistical analysis