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Based on the well-known results of classical potential theory, viz. the limit and jump relations for layer integrals, a numerically viable and efficient multiscale method of approximating the disturbing potential from gravity anomalies is established on regular surfaces, i.e., on telluroids of ellipsoidal or even more structured geometric shape. The essential idea is to use scale dependent regularizations of the layer potentials occurring in the integral formulation of the linearized Molodensky problem to introduce scaling functions and wavelets on the telluroid. As an application of our multiscale approach some numerical examples are presented on an ellipsoidal telluroid.

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Thermogravimetry/mass spectrometry is used to identify TG transitions corresponding to loss of residual moisture in freeze-dried biological products with complex TG curves. While TG weight losses were recorded, ion intensities of mass peaksm/e=18 (water) andm/e=44 (carbon dioxide) were monitored continuously for Typhoid Vaccine U.S.P., Meningococcal Polysaccharide Vaccine Groups A and C Combined and Honey Bee Venom Allergenic Extract. MS ion intensities indicated the difference between evolution of residual moisture and moisture associated with product thermal decomposition. Residual moisture values calculated from TG weight losses indicated by mass spectral data agreed with Karl Fischer moisture data.

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Abstract  

The crystallization of silica glass has been studied by positron lifetime spectroscopy and accompanying investigations using X-ray diffraction and nuclear magnetic resonance (NMR). To this end isothermal and isochronal heat treatments were performed in the range from 700 °C up to 1600 °C. The lifetime spectra are analyzed by two lifetime components. The decrease of the short lifetime (200 ps) is attributed to the increasing volume fraction of the crystalline phase. The long lifetime (1000 ps) is related with the pick-off annihilation of theo-Ps states in cavities.With starting formation of crystallization nuclei the long lifetime increases which is explained by expanding cavities at the interface between crystalline phase and amorphous matrix.

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Abstract

Background

Decision-making and risk-taking behavior undergo developmental changes during adolescence. Disadvantageous decision-making and increased risk-taking may lead to problematic behaviors such as substance use and abuse, pathological gambling and excessive internet use.

Methods

Based on MEDLINE searches, this article reviews the literature on decision-making and risk-taking and their relationships to addiction vulnerability in youth.

Results

Decision-making and risk-taking behaviors involve brain areas that undergo developmental changes during puberty and young adulthood. Individual differences and peer pressure also relate importantly to decision-making and risk-taking.

Conclusions

Brain-based changes in emotional, motivational and cognitive processing may underlie risk-taking and decision-making propensities in adolescence, making this period a time of heightened vulnerability for engagement in addictive behaviors.

Open access

Abstract  

Liquid scintillation counting of radionuclides emitting beta radiation with Emax>2 MeV has been investigated. Fluor volume effects were similar to those for low energy beta radiation, and pulse height spectra broadened in a predictable manner with no pulse clipping up to 4.913 MeV. Large changes in sample channels ratio due to color quenching resulted in progressively smaller losses of counting efficiency as beta energy increased. Counting efficiences were estimated to be near 100 percent for34Clm,36Cl,32P and38Cl. Cerenkov counting of38Cl by liquid scintillation counter was volume dependent for both counting efficiency and pulse height spectrum. Counting efficiencies for34Clm,36Cl,32P and38Cl were estimated to be 57.0, 7.5, 42.7 and 66.3%, respectively. Pulse height spectra were shifted to greater pulse heights as a function of beta Emax, supporting the possibility of energy discrimination for beta emitters by Cerenkov pulse height spectrum analysis. The advantage of singles Cerenkov counting over coincidence Cerenkov counting was greatest for36Cl and least for38Cl; this advantage was amplified more for samples of36Cl which had been color quenched than for similarly quenched samples of38Cl or32P.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: H. Chen-Mayer, V. Sharov, D. Mildner, R. Downing, R. Paul, R. Lindstrom, C. Zeissler, and Q. Xiao

Abstract  

A neutron lens has been constructed to focus cold neutrons from the exit of a58Ni neutron guide, which delivers a beam to the Prompt-Gamma Activation Analysis (PGAA) station at the NIST Cold Neutron Research Facility. The lens compresses a neutron beam of cross section 50 mm× 45 mm onto a focal spot of diameter 0.53 mm (fwhm) wich an average gain of 80 in neutron current density. PGAA measurements have been performed to demonstrate the enhanced sensitivity and detection limits for various elements and the spatial resolution in one transverse dimension. For the two test particles (a gadolinium glass bead and cadmium metal of sizes less than 0.5 mm), the gain in the -count rate with the lens is a factor of 60, and the detection limit is improved by a factor of 20. The system can be used for two-dimensional mapping of samples on a sub-millimeter scale to complement other analytical techniques such as neutron depth profiling (NDP).

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Journal of Behavioral Addictions
Authors: Christopher J. Hammond, Corey E. Pilver, Loreen Rugle, Marvin A. Steinberg, Linda C. Mayes, Robert T. Malison, Suchitra Krishnan-Sarin, Rani A. Hoff, and Marc N. Potenza MD, PhD

Abstract

Background and aims

Gambling is common in adolescents and at-risk and problem/pathological gambling (ARPG) is associated with adverse measures of health and functioning in this population. Although ARPG commonly co-occurs with marijuana use, little is known how marijuana use influences the relationship between problem-gambling severity and health- and gambling-related measures.

Methods

Survey data from 2,252 Connecticut high school students were analyzed using chi-square and logistic regression analyses.

Results

ARPG was found more frequently in adolescents with lifetime marijuana use than in adolescents denying marijuana use. Marijuana use was associated with more severe and a higher frequency of gambling-related behaviors and different motivations for gambling. Multiple health/functioning impairments were differentially associated with problem-gambling severity amongst adolescents with and without marijuana use. Significant marijuana-use-by-problem-gambling-severity-group interactions were observed for low-average grades (OR = 0.39, 95% CI = [0.20, 0.77]), cigarette smoking (OR = 0.38, 95% CI = [0.17, 0.83]), current alcohol use (OR = 0.36, 95% CI = [0.14, 0.91]), and gambling with friends (OR = 0.47, 95% CI = [0.28, 0.77]). In all cases, weaker associations between problem-gambling severity and health/functioning correlates were observed in the marijuana-use group as compared to the marijuana-non-use group.

Conclusions

Some academic, substance use, and social factors related to problem-gambling severity may be partially accounted for by a relationship with marijuana use. Identifying specific factors that underlie the relationships between specific attitudes and behaviors with gambling problems and marijuana use may help improve intervention strategies.

Open access