Genetic Differentiation of the Semi-terrestrial Amphipod Orchestia traskiana in an Expanded Habitat on Santa Cruz Island

Busath, Ann L. "Genetic Differentiation of the Semi-terrestrial Amphipod Orchestia traskiana in an Expanded Habitat on Santa Cruz Island." In: 2nd California Islands Multidisciplinary Symposium. 1978. 395-401

Factors in Word-Final /t/ Reduction and Deletion in German

Sound reduction and deletion have been studied across many languages for some time. Usage-based approaches suggest that the more often a word is used, the more likely it is that some of the sounds are reduced. Phonetic environment, stress, and speech rate have all been studied as reasons for sound reduction or deletion. Most recently, frequency in reducing context (FRC) has been included when studying sound reduction and deletion. FRC in this thesis measures the portion of word tokens of a given word type that are followed by a reducing context. This thesis focuses on word-final /t/ reduction and deletion in German. Audio and transcriptions of six native German speakers were time aligned with the Montreal Forced Aligner for the analysis. Word frequency, phonetic environment, stress, and FRC were analyzed as factors that condition reduction and deletion. A linear mixed-effects regression model with the dependent variable of word-final /t/ duration found significance between a shorter /t/ duration and (1) a shorter duration of the preceding sound and (2) a consonant preceding the reduced /t/. A logistic mixed-effects regression model with the dependent variable of word-final /t/ deletion found significance between deletion and (1) a consonant preceding the deleted /t/ and (2) word frequency. Though FRC was not found to be significant in this study, perhaps measuring FRC with a different reducing context would be significant in a future study

Simple catalytic cell for restoring He leak detector sensitivity on vacuum systems with high D{sub 2} backgrounds

The DIII-D National Fusion Facility at General Atomics focuses on plasma physics and fusion energy science. The DIII-D tokamak is a 35 m{sup 3} toroidal vacuum vessel with over 200 ports for diagnostic instrumentation, cryogenics, microwave heating, and four large neutral beam injectors. Maintaining vacuum in the 10{sup {minus}8} Torr range is crucial for producing high performance plasma discharges. He leak checking the DIII-D tokamak and the neutral beamlines has historically been difficult. D{sub 2} is used as the fuel gas in most plasma discharges and neutral beams. After plasma operations, D{sub 2} out-gassing from the torus walls and internal beamline components can exceed 10{sup {minus}4} std cc/s. The mass of the D{sub 2} molecule (4.028 u) is indistinguishable from that of the He atom (4.003 u) to a standard mass spectrometer leak detector. High levels of D{sub 2} reduce leak detector sensitivity and effectively mask the He trace gas signal rendering normal leak checking techniques ineffective. A simple apparatus was developed at GA to address these problems. It consists of a palladium based catalyst cell and associated valves and piping placed in series with the leak detector. This reduces the D{sub 2} throughput by a factor greater than 10,000, restoring leak detector sensitivity. This paper will briefly discuss the development of the cell, the physical processes involved, the tests performed to quantify and optimize the processes, and the operational results at DIII-D

Computerized Drug Screening of the S31N Mutant of the Influenza A Virus

Influenza is responsible for millions of hospitalizations and deaths every year. Treating the influenza virus has become increasingly difficult since mutant viruses have rendered previously viable drugs ineffective. New drug-screening procedures are now necessary in order to speed up the process of viable drug discovery. Molecular simulations have proven valuable for studying drug effectiveness in wild-type flu viruses, but little has been done on prevailing influenza mutants. Influenza mutants often feature a change in the M2 proton channel, a critical component in the viral replication and infection cycle. To counter this, drugs must be discovered that can block the influenza M2 channel of mutant viruses. The purpose of this research report is to discuss the methods and results of using molecular dynamics simulations to predict drug efficacy against the M2 proton channel of the Influenza A virus

Sodium Flux Ratio in Voltage-Clamped Squid Giant Axons

The sodium flux ratio across the axolemma of internally perfused, voltage-clamped giant axons of Loligo pealei has been measured at various membrane potentials. The flux ratio exponent obtained from these measurements was about unity and independent of membrane voltage over the 50 mV range from about -20 to +30 mV. These results, combined with previous measurements of ion permeation through sodium channels, show that the sodium channel behaves like a multi-ion pore with two ion binding sites that are rarely simultaneously occupied by sodium

Two-, Three-, and Four-Particle Spatial Correlations Among Tertiary Cosmic Ray Muons

Showers of muons which result from interactions of primary cosmic rays high in the atmosphere appear deep underground as bundles of nearly parallel muons. For threshold energies of 1 TeV and arrival zenith angles of 45 degrees, those events having a small mean number of muons are described by a power law distribution in shower size having an exponent of ≅ -3.7 and a radial density distribution that decreases with distance R from the shower axis a little less rapidly than exp(-R/5.4 m). Comparison of new data on four muon spatial correlations in terms of the same phenomenology with data on two and three muon spatial correlations from previous experiments suggests that the shower size distribution steepens and the shower radial density distribution broadens with increasing shower size (i.e., with increasing mean energy of the primary cosmic ray at a given threshold energy of the muons observed). These results might be explained by a basically geometrical effect due either to a total inelastic cross section which rises with energy or by an enhanced contribution from the interactions of secondaries. If the effect does not have a geometrical origin, then it may be necessary to reformulate the input to shower development calculations which have assumed that interaction products axe described by factored, uncorrelated single particle statistical distributions. The relationships between the inclusive distributions predicted by theory and those of the empirical phenomenology are explored in.some detail

Fluorescence anisotropy of diphenylhexatriene and its cationic Trimethylamino derivative in liquid dipalmitoylphosphatidylcholine liposomes: opposing responses to isoflurane

<p>Abstract</p> <p>Background</p> <p>The mechanism of action of volatile general anesthetics has not yet been resolved. In order to identify the effects of isoflurane on the membrane, we measured the steady-state anisotropy of two fluorescent probes that reside at different depths. Incorporation of anesthetic was confirmed by shifting of the main phase transition temperature.</p> <p>Results</p> <p>In liquid crystalline dipalmitoylphosphatidylcholine liposomes, isoflurane (7-25 mM in the bath) increases trimethylammonium-diphenylhexatriene fluorescence anisotropy by ~0.02 units and decreases diphenylhexatriene anisotropy by the same amount.</p> <p>Conclusions</p> <p>The anisotropy data suggest that isoflurane decreases non-axial dye mobility in the headgroup region, while increasing it in the tail region. We propose that these results reflect changes in the lateral pressure profile of the membrane.</p

Dissolved Oxygen Reduction in the DIII-D Neutral Beam Ion Source Cooling System

OAK-B135 Neutral beam ion sources (NBIS) are critical components for the neutral beam injection system supporting the DIII-D tokamak. The NBIS must be cooled with 3028 {ell}/m (800 gpm) of de-ionized and de-oxygenated water to protect the sources from overheating and failure. These ions sources are currently irreplaceable. Since the water cooled molybdenum components will oxidize in water almost instantaneously in the presence of dissolved oxygen (DO), de-oxygenation is extremely important in the NBIS water system. Under normal beam operation the DO level is kept below 5 ppb. However, during weeknights and weekends when neutral beam is not in operation, the average DO level is maintained below 10 ppb by periodic circulation with a 74.6 kW (100 hp) pump, which consumes significant power. Experimental data indicated evidence of continuous oxygen diffusion through non-metallic hoses in the proximity of the NBIS. Because of the intermittent flow of the cooling water, the DO concentration at the ion source(s) could be even higher than measured downstream, and hence the concern of significant localized oxidation/corrosion. A new 3.73 kW (5 hp) auxiliary system, installed in the summer of 2003, is designed to significantly reduce the peak and the time-average DO levels in the water system and to consume only a fraction of the power

Copper Complexes as Influenza Antivirals: Reduced Zebrafish Toxicity

Copper complexes have previously been developed to target His37 in influenza M2 and are effective blockers of both the wild type (WT) and the amantadine-resistant M2S31N. Here, we report that the complexes were much less toxic to zebrafish than CuCl2. In addition, we characterized albumin binding, mutagenicity, and virus resistance formation of these metal complexes, and employed steered molecular dynamics simulations to explore whether the complexes would fit in M2. We also examined their anti-viral efficacy in a multi-generation cell culture assay to extend the previous work with an initial-infection assay, discovering that this is complicated by cell culture medium components. The number of copper ions binding to bovine serum albumin (BSA) correlates well with the number of surface histidines and BSA binding affinity is low compared to M2. No mutagenicity of the complexes was observed when compared to sodium azide. After 10 passages of virus in MDCK culture, the EC50 was unchanged for each of the complexes, i.e. resistance did not develop. The simulations revealed that the compounds fit well in the M2 channel, much like amantadine