The solution of Burgers' equation for sinusoidal excitation at the upstream boundary

This paper generates an exact solution to Burgers' nonlinear diffusion equation on a convective stream with sinusoidal excitation applied at the upstream boundary, x =0. The downstream boundary, effectively at x =∞, is assumed to always be far enough ahead of the convective front at x=V s t that no disturbance is felt there. The Hopf-Cole transformation is applied in achieving the analytical solution, but only after integrating the equation and its conditions in x to avoid a nonlinearity in the transformed upstream boundary condition.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42700/1/10665_2006_Article_BF02383570.pd

High-resolution aerosol concentration data from the Greenland NorthGRIP and NEEM deep ice cores

Records of chemical impurities from ice cores enable us to reconstruct the past deposition of aerosols onto polar ice sheets and alpine glaciers. Through this they allow us to gain insight into changes of the source, transport and deposition processes that ultimately determine the deposition flux at the coring location. However, the low concentrations of the aerosol species in the ice and the resulting high risk of contamination pose a formidable analytical challenge, especially if long, continuous and highly resolved records are needed. Continuous flow analysis, CFA, the continuous melting, decontamination and analysis of ice-core samples has mostly overcome this issue and has quickly become the de facto standard to obtain high-resolution aerosol records from ice cores after its inception at the University of Bern in the mid-1990s. Here, we present continuous records of calcium (Ca2+), sodium (Na+), ammonium (NH+4), nitrate (NO-3) and electrolytic conductivity at 1 mm depth resolution from the NGRIP (North Greenland Ice Core Project) and NEEM (North Greenland Eemian Ice Drilling) ice cores produced by the Bern Continuous Flow Analysis group in the years 2000 to 2011 (Erhardt et al., 2021). Both of the records were previously used in a number of studies but were never published in full 1 mm resolution. Alongside the 1 mm datasets we provide decadal averages, a detailed description of the methods, relevant references, an assessment of the quality of the data and its usable resolution. Along the way we will also give some historical context on the development of the Bern CFA system. The data is available in full 1 mm and 10-year-averaged resolution on PANGAEA (https://doi.org/10.1594/PANGAEA.935838, Erhardt et al., 2021

Characterization of the Radiation Shielding Properties of US and Russian EVA Suits

Reported herein are results from the Eril Research, Inc. (ERI) participationin the NASA Johnson Space Center sponsored study characterizing the radiation shielding properties of the two types of space suit that astronauts are wearing during the EVA on-orbit assembly of the International Space Station (ISS). Measurements using passive detectors were carried out to assess the shielding properties of the US EMU Suit and the Russian Orlan-M suit during irradiations of the suits and a tissue equivalent phantom to monoenergetic proton and electron beams at the Loma Linda University Medical Center (LLUMC). During irradiations of 6 MeV electrons and 60 MeV protons, absorbed dose as a function of depth was measured using TLDs exposed behind swatches of the two suit materials and inside the two EVA helmets. Considerable reduction in electron dosewas measured behind all suit materials in exposures to 6 MeV electrons. Slowing of the proton beam in the suit materials led to an increase in dose measured in exposures to 60 MeV protons. During 232 MeV proton irradiations, measurements were made with TLDs and CR-39 PNTDs at five organ locations inside a tissue equivalent phantom, exposed both with and without the two EVA suits. The EVA helmets produce a 13 to 27 percent reduction in total dose and a 0 to 25 percent reduction in dose equivalent when compared to measurements made in the phantom head alone. Differences in dose and dose equivalent between the suit and non-suit irradiations forthe lower portions of the two EVA suits tended to be smaller. Proton-induced target fragmentation was found to be a significant source of increased dose equivalent, especially within the two EVA helmets, and average quality factor inside the EMU and Orlan-M helmets was 2 to 14 percent greater than that measured in the bare phantom head