Spectroscopic analysis of radiation-generated changes in tensile properties of a polyetherimide film

The effects of electron radiation on Ultem, a polyetherimide were studied for doses from 2 x 10 to the 9th power to 6 x 10 to the 9th power rad. Specimens were studied for tensile property testing and for electron paramagnetic resonance and infrared spectroscopic measurements of molecular structure. A Faraday cup design and a method for remote temperature measurement were developed. The spectroscopic data show that radiation caused dehydrogenation of methyl groups, rupture of main-chain ether linkage, and opening of imide rings, all to form radicals and indicate that the so-formed atomic hydrogen attached to phenyl radicals, but not to phenoxyl radicals, which would have formed hydroxyls. The observed decays of the radiation-generated phenoxyl, gem-dimethyl, and carbonyl radicals were interpreted as a combining of the radicals to form crosslinking. This crosslinking is the probable cause of the major reduction in the elongation of the tensile specimens after irradiation. Subsequent classical solubility tests indicate that the irradiation caused massive crosslinking

A common goodness-of-fit framework for neural population models using marked point process time-rescaling

A critical component of any statistical modeling procedure is the ability to assess the goodness-of-fit between a model and observed data. For spike train models of individual neurons, many goodness-of-fit measures rely on the time-rescaling theorem and assess model quality using rescaled spike times. Recently, there has been increasing interest in statistical models that describe the simultaneous spiking activity of neuron populations, either in a single brain region or across brain regions. Classically, such models have used spike sorted data to describe relationships between the identified neurons, but more recently clusterless modeling methods have been used to describe population activity using a single model. Here we develop a generalization of the time-rescaling theorem that enables comprehensive goodness-of-fit analysis for either of these classes of population models. We use the theory of marked point processes to model population spiking activity, and show that under the correct model, each spike can be rescaled individually to generate a uniformly distributed set of events in time and the space of spike marks. After rescaling, multiple well-established goodness-of-fit procedures and statistical tests are available. We demonstrate the application of these methods both to simulated data and real population spiking in rat hippocampus. We have made the MATLAB and Python code used for the analyses in this paper publicly available through our Github repository at https://github.com/Eden-Kramer-Lab/popTRT.This work was supported by grants from the NIH (MH105174, NS094288) and the Simons Foundation (542971). (MH105174 - NIH; NS094288 - NIH; 542971 - Simons Foundation)Published versio

Solo women - a new agenda for ageing?

A short review of research findings from an online survey of women living without partners and children as they enter later life

The visual acuity in viewing scaled objects on television compared with that in direct viewing

Visual acuity for scaled objects by direct viewing and on television monitor

Laboratory measurements and theoretical calculations of O_2 A band electric quadrupole transitions

Frequency-stabilized cavity ring-down spectroscopy was utilized to measure electric quadrupole transitions within the ^(16)O_2 A band, b^1Σ^+_g ← X^3Σ^-_g(0,0). We report quantitative measurements (relative uncertainties in intensity measurements from 4.4% to 11%) of nine ultraweak transitions in the ^NO, ^PO, ^RS, and ^TS branches with line intensities ranging from 3×10^(−30) to 2×10^(−29) cm molec.^(−1). A thorough discussion of relevant noise sources and uncertainties in this experiment and other cw-cavity ring-down spectrometers is given. For short-term averaging (t<100 s), we estimate a noise-equivalent absorption of 2.5×10^(−10) cm^(−1) Hz^(−1/2). The detection limit was reduced further by co-adding up to 100 spectra to yield a minimum detectable absorption coefficient equal to 1.8×10^(−11) cm^(−1), corresponding to a line intensity of ~2.5×10^(−31) cm molec.^(−1). We discuss calculations of electric quadrupole line positions based on a simultaneous fit of the ground and upper electronic state energies which have uncertainties <3 MHz, and we present calculations of electric quadrupole matrix elements and line intensities. The electric quadrupole line intensity calculations and measurements agreed on average to 5%, which is comparable to our average experimental uncertainty. The calculated electric quadrupole band intensity was 1.8(1)×10^(−27) cm molec.−1 which is equal to only ~8×10^(−6) of the magnetic dipole band intensity

Calcium and magnesium absorption and retention by growing goats offered diets with different calcium sources

Calcium addition is necessary in order to balance the high phosphorus concentrations that are characteristic of high-concentrate ruminant diets. However, calcium sources differ in their bioavailability. Our objective was to determine apparent calcium and magnesium absorption and retention in goats offered diets containing different sources of calcium. Spanish-Boer goats (n = 18; 19.6 ± 1.88 kg) were stratified by body weight (BW) and sex and randomized to dietary treatments consisting of Purina Antlermax 16 containing either calcium carbonate (CC), Calmin (CM) or Milk Cal (MC). Goats were adapted to a control, corn-based high-concentrate diet on pasture and then moved to individual 1.0 × 1.5-m pens with plastic coated expanded metal floors, and adjusted to their respective diets along with removal of hay from the diet over a 7-d period. Goats were then offered their respective diets at a total of 2% of BW in equal feedings at 8:30 AM and 5:00 PM for an additional 14-d adaption period to diet and facilities followed by a 7-d collection of total urine and feces. Data were analyzed using PROC MIXED of SAS. Calcium and magnesium intake were not different (P ≥ 0.12) among diets. Calcium and magnesium apparent absorption and retention (g/d and % of intake) were greatest (P \u3c 0.05) in goats offered CC and did not differ (P ≥ 0.20) between goats offered the CM and MC diets. Therefore, calcium and magnesium were more available for goats from the diet containing calcium carbonate compared with diets containing Calmin and Milk Cal