Process for preparing polyimide adhesives

High bonding strengths are obtained for metals and fiber-reinforced organic resin composites with no significant loss in thermo-oxidative stability of the adhesive resin

DIRBE External Calibrator (DEC)

Under NASA Contract No. NAS5-28185, the Center for Space Engineering at Utah State University has produced a calibration instrument for the Diffuse Infrared Background Experiment (DIRBE). DIRBE is one of the instruments aboard the Cosmic Background Experiment Observatory (COBE). The calibration instrument is referred to as the DEC (Dirbe External Calibrator). DEC produces a steerable, infrared beam of controlled spectral content and intensity and with selectable point source or diffuse source characteristics, that can be directed into the DIRBE to map fields and determine response characteristics. This report discusses the design of the DEC instrument, its operation and characteristics, and provides an analysis of the systems capabilities and performance

Reduced dimension modeling of leading edge turbulent interaction noise

A computational aeroacoustics approach is used to model the effects of real airfoil geometry on leading edge turbulent interaction noise for symmetric airfoils at zero angle of attack. For the first time, one-component (transverse), two-component (transverse and streamwise), and three-component (transverse, streamwise, and spanwise) synthesized turbulent disturbances are modeled instead of single frequency transverse gusts, which previous computational studies of leading edge noise have been confined to. The effects of the inclusion of streamwise and spanwise disturbances on the noise are assessed, and it is shown that accurate noise predictions for symmetric airfoils can be made by modeling only the transverse disturbances, which reduces the computational expense of simulations. Additionally, the two-component turbulent synthesis method is used to model the effects of airfoil thickness on the noise for thicknesses ranging from 2% to 12%. By using sufficient airfoil thicknesses to show trends, it is found that airfoil thickness will reduce the noise at high frequency, and that the sound power P will reduce linearly with increasing airfoil thickness

CAA study of airfoil broadband interaction noise using stochastic turbulent vorticity sources

The interaction of the turbulent wakes of the rotor with the outer guide vanes is one of the main broadband noise source in turbofan engines at approach conditions. Hence its prediction and reduction is a priority for engine manufacturers. The development of numerical methods is required as analytical approaches are limited to simple geometries and simplified flow configurations. The linearized Euler equations are solved in the time-domain to model the response of an isolated airfoil interacting with turbulence that is stochastically synthesized and injected in the computational domain through vorticity sources. This new method of injection has the advantages of being easy to implement and parallelize in an existing solver, whilst the generated turbulence is frozen. The method is firstly validated on a 2D free-field configuration. It is then applied, in the framework of the Fan Stage Broadband Noise Benchmarking Programme, to a two-dimensional NACA 65(12)-10 airfoil with no angle of attack and the results are validated through comparisons with experimental data. Afterwards, the effect of the angle of attack is studied and the results suggest that a one-component turbulent model is not satisfactory to perform accurate acoustic predictions with an angle of attack, as it overestimates the rate of decay of the acoustic spectra at high frequencies. The study of the influence of the integral length scale of the turbulence confirms that the airfoil leading edge response is only modulated by the incoming turbulence characteristics. Finally, the acoustic spectra predicted for different velocities show a better agreement with a flat plate analytical model when the velocity is increased

Fauna of the Middle Little Sioux River and Comparison with Upper and Lower Regions

A species list of macroscopic animals is compiled for the middle portion of the Little Sioux River, Iowa. These are tabulated along with published data from regions of the river above and below. The Little Sioux meanders throughout a valley of largely agricultural landscape; it has a relatively high silt load. Chemical differences are not great; some effects of municipal effluent are noted. The number of species is relatively constant (in the 40-60 range); numbers in the uppermost, intermittent stretches and the lowermost, channelized segment are lower (30- 40). Only about 20% of the species are ubiquitous; trends of diversity and distribution are noted in the invertebrates and fishes

What is the nature of peer interactions in children with language disorders? A qualitative study of parent and practitioner views

Background and aims: Children with Language Disorders (LDs) can exhibit increased levels of social withdrawal, aggression and problems managing social conflicts. The reasons underlying this pattern of social interaction profiles remain unclear. This qualitative study aimed to document the nature of social interactions between children with LDs and their peers, and to evaluate explanations for their social behaviour, as understood by parents and practitioners. Methods: This study focused on children with LDs who spend school hours with other children with LDs. Three parent focus groups (n ¼ 8) and three practitioner focus groups (n ¼ 10) were conducted with parents of children aged 4–12 attending specialist language schools and practitioners working at these schools. This was a mixed clinical sample. All children of participating parents had LD as their primary area of need, which was the reason they required specialist schooling. Focus groups were conducted across two specialist schools in the UK between March and June 2018. Results: An inductive reflective thematic analysis of the data identified three themes; social knowledge, coping strategies, and emotional competence. Parents and school staff reported that children with LDs experience difficulties managing peer interactions due to a combination of challenges including difficulties with understanding and regulating emotions, and difficulties understanding social situations. Some of the children with LDs were described as having developed strategies to cope with their challenges, for example imposing structure on their social interactions to manage uncertainty, which has implications for their social interactions with peers. Conclusions: Children with LDs have difficulties understanding emotions, difficulties understanding their peer’s intentions and difficulties resolving conflict situations independently according to their parents and practitioners working with these children. Participants proposed a novel explanation that social withdrawal may be used adaptively by children with LDs to process information. This study demonstrates the complexity of the relationship between Language Disorders and peer interaction profiles. Implications: Suggestions are offered regarding future research directions, such as investigating the specific contribution language skills make to children’s emotion understanding, to better understand the reasons for peer interaction difficulties in children with Language Disorders

Use of Saline Water in Energy Development

Maps were made of the Upper Colorado River Basin showing locations of coal deposits, oil and gas, oil shale, uranium, and tar sand, in relationship to cities and towns in the area. Superimposed on these are locations of wells showing four ranges of water quality; 1,000-3,000 mg/l, 3,000-10,000 mg/l, 10,000-35,000 mg/l, and over 35,000 mg/l. Information was assembled relative to future energy-related projects in the upper basin, and estimates were made of their anticipated water needs. Using computer models, various options were tested for using saline water for coal-fired power plant cooling. Both cooling towers and brine evaporation ponds were included. information is presented of several proven water treatment technologies, and comparisons are made of their cost effectiveness when placed in various combinations in the power plant makeup and blowdown water systems. A relative value scale was developed which compares graphically the relative values of water of different salinities based on three different water treatment options and predetermined upper limits of cooling tower circulating salinities. Coal from several different mines was slurried in waters of different salinities. Samples were analyzed in the laboratory to determine which constituents had been leached from or absorbed by the coal, and what possible deleterious effects this might have on the burning properties of the coal, or on the water for culinary use or irrigation

Characterization of chromoshadow domain-mediated binding of heterochromatin protein 1α (HP1α) to histone H3.

The chromoshadow domain (CSD) of heterochromatin protein 1 (HP1) was recently shown to contribute to chromatin binding and transcriptional regulation through interaction with histone H3. Here, we demonstrate the structural basis of this interaction for the CSD of HP1α. This mode of H3 binding is dependent on dimerization of the CSD and recognition of a PxVxL-like motif, as for other CSD partners. NMR chemical shift mapping showed that the H3 residues that mediate the CSD interaction occur in and adjacent to the αN helix just within the nucleosome core. Access to the binding region would require some degree of unwrapping of the DNA near the nucleosomal DNA entry/exit site

Urban agriculture : evaluating informal and formal practices

Urban agriculture (UA) is a fast-increasing element in many settlements in the Global North. This paper reviews the diversity of UA activity, ranging from legal to illegal, formal to informal. Focusing particularly on current research on UA projects in England, including small-scale guerrilla gardening and large community projects supported by community and government funding, we look at the realities of UA. We suggest that it is under-theorised as previous research has focused on practicalities and activism. In particular, we highlight the problematic contribution of UA to food production, the wider value in terms of community development, health and wellbeing, and warn of the danger of the ‘local trap’

Validation of the Harvard Lyman-α in situ water vapor instrument: Implications for the mechanisms that control stratospheric water vapor

Building on previously published details of the laboratory calibrations of the Harvard Lyman-α photofragment fluorescence hygrometer (HWV) on the NASA ER-2 and WB-57 aircraft, we describe here the validation process for HWV, which includes laboratory calibrations and intercomparisons with other Harvard water vapor instruments at water vapor mixing ratios from 0 to 10 ppmv, followed by in-flight intercomparisons with the same Harvard hygrometers. The observed agreement exhibited in the laboratory and during intercomparisons helps corroborate the accuracy of HWV. In light of the validated accuracy of HWV, we present and evaluate a series of intercomparisons with satellite and balloon borne water vapor instruments made from the upper troposphere to the lower stratosphere in the tropics and midlatitudes. Whether on the NASA ER-2 or WB-57 aircraft, HWV has consistently measured about 1–1.5 ppmv higher than the balloon-borne NOAA/ESRL/GMD frost point hygrometer (CMDL), the NOAA Cryogenic Frost point Hygrometer (CFH), and the Microwave Limb Sounder (MLS) on the Aura satellite in regions of the atmosphere where water vapor is <10 ppmv. Comparisons in the tropics with the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite show large variable differences near the tropopause that converge to ~10% above 460 K, with HWV higher. Results we show from the Aqua Validation and Intercomparison Experiment (AquaVIT) at the AIDA chamber in Karlsruhe do not reflect the observed in-flight differences. We illustrate that the interpretation of the results of comparisons between modeled and measured representations of the seasonal cycle of water entering the lower tropical stratosphere is dictated by which data set is used