Spatially and temporally resolved temperature measurements of plasma generated in percussion drilling with a diode-pumped Nd:YAG laser

Results of spectroscopic temperature measurements of the laser-induced plasma generated during percussion drilling with a high power diode-pumped, pulsed Nd:YAG laser are presented. SAE 52100 steel was drilled with varying average powers. Helium and oxygen were each used as the shield gas. Emission spectra were collected with a monochrometer and an intensified charge coupled detector connected to the optical multichannel analyzer. The plasma electron temperatures were calculated from the relative intensities of the spectral lines. The spatial and temporal temperature distributions are presented. Both drilling times and spatial distributions indicate energy absorption by the plasma. © 1998 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71333/2/JAPIAU-84-8-4122-1.pd

High-contrast Doppler-free transmission spectroscopy

By applying Doppler-free saturated absorption spectroscopy in the regime of high integrated sample absorption, high-contrast Doppler-free laser transmission signals can be obtained as demonstrated in experiments on the sodium D lines. Natural linewidth background-free signals are observed

Laser spectroscopy using beam-overlap modulation

A new Doppler-free laser spectroscopy method is demonstrated that employs modulation of the position of a laser beam rather than the commonly used intensity or polarization modulation. The technique is applicable in saturated absorption as well as fluorescence measurements, as is illustrated in experiments on sodium and iodine lines. A particular feature of the method is that Doppler- and background-free fluorescence spectra can be recorded without using intermodulation techniques

Dynamic buckling of containments: The influence of damping

The seismic buckling capacities of representative thin, unstiffened elastic containment shells are investigated to evaluate the sensitivity of buckling to the damping level. The finite element method with transient time integration is utilized with both actual earthquake acceleration-time signals and artificial time histories generated from regulatory spectra. The dynamic response and subsequent buckling of the selected containment shells are found to be highly dependent on both damping level and the degree to which the input signal excites the fundamental shear-bending mode of the shell. Transient stresses and buckling levels for the two containment shells induced by the seismic inputs were reduced in the range of 12% to 111% by increasing the damping level from 1% to 4% of critical

A De Novo Mutation in the Sodium-Activated Potassium Channel KCNT2 Alters Ion Selectivity and Causes Epileptic Encephalopathy.

Early infantile epileptic encephalopathies (EOEE) are a debilitating spectrum of disorders associated with cognitive impairments. We present a clinical report of a KCNT2 mutation in an EOEE patient. The de novo heterozygous variant Phe240Leu SLICK was identified by exome sequencing and confirmed by Sanger sequencing. Phe240Leu rSlick and hSLICK channels were electrophysiologically, heterologously characterized to reveal three significant alterations to channel function. First, [Cl-]i sensitivity was reversed in Phe240Leu channels. Second, predominantly K+-selective WT channels were made to favor Na+ over K+ by Phe240Leu. Third, and consequent to altered ion selectivity, Phe240Leu channels had larger inward conductance. Further, rSlick channels induced membrane hyperexcitability when expressed in primary neurons, resembling the cellular seizure phenotype. Taken together, our results confirm that Phe240Leu is a "change-of-function" KCNT2 mutation, demonstrating unusual altered selectivity in KNa channels. These findings establish pathogenicity of the Phe240Leu KCNT2 mutation in the reported EOEE patient

Bostonia: The Boston University Alumni Magazine. Volume 12

Founded in 1900, Bostonia magazine is Boston University’s main alumni publication

Organic nitrate aerosol formation via NO_3 + biogenic volatile organic compounds in the southeastern United States

Gas- and aerosol-phase measurements of oxidants, biogenic volatile organic compounds (BVOCs) and organic nitrates made during the Southern Oxidant and Aerosol Study (SOAS campaign, Summer 2013) in central Alabama show that a nitrate radical (NO_3) reaction with monoterpenes leads to significant secondary aerosol formation. Cumulative losses of NO_3 to terpenes are correlated with increase in gas- and aerosol-organic nitrate concentrations made during the campaign. Correlation of NO_3 radical consumption to organic nitrate aerosol formation as measured by aerosol mass spectrometry and thermal dissociation laser-induced fluorescence suggests a molar yield of aerosol-phase monoterpene nitrates of 23–44 %. Compounds observed via chemical ionization mass spectrometry (CIMS) are correlated to predicted nitrate loss to BVOCs and show C_(10)H_(17)NO_5, likely a hydroperoxy nitrate, is a major nitrate-oxidized terpene product being incorporated into aerosols. The comparable isoprene product C_5H_9NO_5 was observed to contribute less than 1 % of the total organic nitrate in the aerosol phase and correlations show that it is principally a gas-phase product from nitrate oxidation of isoprene. Organic nitrates comprise between 30 and 45 % of the NOy budget during SOAS. Inorganic nitrates were also monitored and showed that during incidents of increased coarse-mode mineral dust, HNO_3 uptake produced nitrate aerosol mass loading at a rate comparable to that of organic nitrate produced via NO_3 + BVOCs

Herbivore-Mediated Effects of Glucosinolates on Different Natural Enemies of a Specialist Aphid

The cabbage aphid Brevicoryne brassicae is a specialist herbivore that sequesters glucosinolates from its host plant as a defense against its predators. It is unknown to what extent parasitoids are affected by this sequestration. We investigated herbivore-mediated effects of glucosinolates on the parasitoid wasp Diaeretiella rapae and the predator Episyrphus balteatus. We reared B. brassicae on three ecotypes of Arabidopsis thaliana that differ in glucosinolate content and on one genetically transformed line with modified concentrations of aliphatic glucosinolates. We tested aphid performance and the performance and behavior of both natural enemies. We correlated this with phloem and aphid glucosinolate concentrations and emission of volatiles. Brevicoryne brassicae performance correlated positively with concentrations of both aliphatic and indole glucosinolates in the phloem. Aphids selectively sequestered glucosinolates. Glucosinolate concentration in B. brassicae correlated negatively with performance of the predator, but positively with performance of the parasitoid, possibly because the aphids with the highest glucosinolate concentrations had a higher body weight. Both natural enemies showed a positive performance-preference correlation. The predator preferred the ecotype with the lowest emission of volatile glucosinolate breakdown products in each test combination, whereas the parasitoid wasp preferred the A. thaliana ecotype with the highest emission of these volatiles. The study shows that there are differential herbivore-mediated effects of glucosinolates on a predator and a parasitoid of a specialist aphid that selectively sequesters glucosinolates from its host plant

Menu labelling and food choice in obese adults: a feasibility study.

BACKGROUND: To date research examining the benefits of menu labelling in the UK is sparse. The aim of the present study was to examine the impact of menu labelling in a UK obese population. METHODS: Using a repeated measures design, 61 patients at a tier 3 weight management service completed four questionnaires to assess their food choice (control) and behaviour change when presented with 3 menu labelling formats (calorie content; nutrient content; and energy expenditure). RESULTS: All three forms of labelling increased participants weight control concerns compared to the control condition. There was a significant difference in content of food ordered in the three menu labelling formats compared to the control condition. The calorie condition had the largest percentage decrease in calories selected followed by energy expenditure and nutrient content. However, no difference was observed between the three conditions in the desire for menu labelling in restaurants to be introduced in the UK. CONCLUSIONS: The findings suggest that menu labelling should be enforced in the UK as it is both beneficial to promoting healthy eating and in demand. This study is the first to examine menu labelling in a UK obese population using energy expenditure equivalents to provide nutritional information