Retrieval of upper atmosphere pressure-temperature profiles from high resolution solar occultation spectra

Pressure-temperature profiles over the 18 to 75 km altitude range were retrieved from 0.01 cm(-1) resolution infrared solar absorption spectra recorded with the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer operating in the solar occultation mode during the Spacelab 3 shuttle mission (April 30 to May 1, 1985). The analysis method is described and preliminary results deduced for five occultation events are compared to correlative pressure-temperature measurments

Uniaxial Stress Effects on the Low-Field Magnetoacoustic Interactions in Low and Medium Carbon Steels

In the past, we have shown that the low-field magnetoacoustic technique is capable of detecting uniaxial compression in steel components without necessiating a calibration standard [1,2]. This is because the initial slope of the AF(B)/F curve (fractional frequency change of phase-locked acoustic waves as a function of net magnetic induction) is negative only under compression and positive otherwise, when the specimens are magnetized along the static unaxial stress axis.</p

AC Magnetic Field Amplitude Dependence of Magnetoacoustic Emission Spectra and Effects of Temper Embrittlement of HY80 Steel

Certain impurity species trapped in the grain boundaries of HY80 steel during the post-fabrication heat treatment are known to cause temper embrittlement [1]. On the other hand, the local residual stress fields due to lattice mismatch at grain boundaries are the main pinning sites causing irreversible magnetic domain wall motion that creates magnetoacoustic emission (MAE). The peak amplitude of MAE depends on two major factors; the waveform of applied AC magnetic field and the strength of the 90° domain wall-defect interaction which creates an effective potential barrier against the domain wall motion. As the degree of embrittlement increases, therefore, the peak amplitude of MAE burst should increase since the higher concentration of impurities enhances the 90° wall-defect interaction at the grain boundaries

effect of butyric acid on the performance and carcass yield of broiler chickens

Short-chain fatty acids such as butyrate are considered potential alternatives to antibiotic growth promoters. The efficacy of butyric acid on performance and carcass characteristics of broiler chickens was tested in two studies. The effect of dietary butyrate on the ability to withstand coccidial oocyte challenge also was investigated. In experiment 1, male broiler chickens were fed diets supplemented with 0 or 11 ppm virginiamycin or 0.2 or 0.4% butyric acid (as mono-, di-, and triglyceride). In experiment 2, broilers were fed bacitracin methylene disalicylate or 0.1 or 0.2% butyric acid. In another trial, birds vaccinated against coccidiosis were challenged with oocytes at 21 d and examined 6 d later. In experiment 1, diet treatments had no effect on body weight gain. Feed intake of the birds fed 0.4% butyric acid was decreased (P < 0.01) compared with birds fed the nonmedicated diet during the starter period, whereas birds fed 0.2% butyric acid had similar feed intake to the control birds. In experiment 2, diet treatments did not affect the performance of broiler chicks while carcass weight and breast meat yield increased (P < 0.01) in birds fed 0.2% butyric acid. With oocyte challenge, birds that had received butyric acid before challenge showed higher growth rate following the challenge compared with birds that received nonmedicated feed. Bacitracin decreased (P < 0.05%) duodenal villi crypt depth, whereas villus length was similar in birds fed butyric acid or the nonmedicated control diet. These results show that 0.2% butyric acid can help to maintain the performance and carcass quality of broilers, especially in vaccinated birds challenged with coccidiosis

Impacts of the COVID-19 Pandemic on Elementary School Teachers’ Practices and Perceptions Across the Spring and Fall 2020 Semesters

Following the closure of schools in the spring 2020 semester due to the COVID-19 pandemic, we developed two surveys to understand how the pandemic affected elementary education in the U.S. First, we distributed a survey at the end of the spring 2020 semester to understand how school closures impacted delivery of instruction. Second, we conducted a follow up survey in November 2020 to determine the nature of instruction provided to students when schools did or did not re-open in Fall 2020 and understand teachers’ perceptions of student learning and achievement during the pandemic. Each survey was sent to a sample of over 9,000 teachers who were randomly selected to be representative of the population of the U.S. Results indicated that many students did not receive direct instruction in academic skills during the spring 2020 semester. Although by late fall 2020 teachers reported broad use of some form of in-person instructional model, teachers indicated that many of their students were not ready to transition to the next grade level and that achievement gaps were larger in fall 2020 than in typical years. These findings have important implications for practices during potential school closures in the future

Analysis of the mutual inductance between two parallel plates for the detection of surface flaws

There has recently been much effort behind the development of NDE methods applicable to the detection of surface/subsurface flaws in thin metallic structures with a rapid scan capability. One such method, an electromagnetic technique using a current-sheet parallel to the surface of a specimen in order to induce eddy current flow shows a high potential for satisfying the rapid scan requirement stated above. The technique is based on the detection of flaw-induced magnetic field components normal to the specimen surface by an appropriate detection mechanism positioned above the current-sheet as shown schematically in Fig. 1. As indicated in this figure, the current-sheet separates the source of the normal magnetic field components from the detector in such a way that the electric and magnetic properties of the current-sheet can be a major factor affecting the strength of the detected signals. The purpose of the present study is, therefore, to perform a detailed investigation on the effect of the material properties of the current-sheet on the detected signal strength and to establish a simple theoretical model for the detection mechanism

Imaging Flaws in Thin Metal Plates Using a Magneto-Optic Device

The ability to quickly detect flaws in thin aluminum alloy sheets is of critical importance to the commercial airline fleets. Current eddy-current methods, although very effective at exposing flawed regions, can be very time consuming when applied to airframe structures. The need for a fast, effective means of detecting critical flaws needs to be met. The purpose of this paper is to present preliminary results describing some capabilities of a new instrument, The Magneto-Optic/Eddy Current Imager, as an NDE tool for use in the Airframe Structural Integrity Program

A method to measure the electron temperature and density of a laser-produced plasma by Raman scattering

A method is proposed to investigate the electron temperature and density of a laser-produced plasma simultaneously, using the temperature dependence difference of the Raman forward scattering (RFS) and backward scattering (RBS). Density and temperature dependence of spectra from the RBS and the RFS in a laser produced plasma were investigated by one-dimensional particle-in-cell simulations in the nonrelativistic regime. This technique has a great advantage as a simple diagnostic of plasma characteristics in the sense that it can be performed only with the pump laser, without any additional probe laser.open3