Cognitive Development and Language Acquisition in Autistic Children

Autism spectrum disorder (ASD) is typically perceived as a social communication and behavioral disability. However, it is a neurodevelopmental or brain-based condition with widespread consequences on cognitive and social-emotional development caused by genetic events that begin before birth. Cognitive functions of a higher level or those requiring integrative processing are disproportionately hampered in ASD. Normal children can learn any existing language based on their environment; however autistic youngsters find it difficult. The exploration of autistic children’s cognitive and language features has been greatly influenced by theoretical models and research approaches

Calibration System Design and Determination of Filter Calibration Requirements for SNAP

Thesis (PhD) - Indiana University, Astronomy, 2007The SuperNova/Acceleration Probe (SNAP) is a proposed space-based, wide-field telescope designed to measure the properties of dark energy in our universe. SNAP will measure ~2000 type Ia supernovae, and the reduction of systematic errors in the relative spectrophotometric measurements will be critical to the mission science. A stringent systematic error requirement of 2% in color photometry is driving the SNAP calibration methodology and system design into new areas of space-based, radiometric calibration for astronomical missions. At the forefront of these new calibration techniques is the use of narrowband light and photodiodes to measure the precise irradiance incident on SNAP filters and detectors. Using these techniques, I have built the Monochromatic Illumination and Cryogenic Calibration System (MICCS) to address the SNAP calibration hardware requirements. With this system, I can transfer the NIST irradiance calibration of an InGaAs photodiode to transfer photodiodes operated at 140K as well as measure the transmission of interference filters at incident angles and temperature similar to that used on the SNAP focal plane. Due to size and light efficiency constraints, I also investigated the use of light emitting diodes (LEDs) as calibrating light sources onboard SNAP. When coupled with calibrated photodiodes, a selection of LEDs could fly onboard SNAP and be used to track changes in the SNAP interference filters during the lifetime of the experiment. The error from this LED calibration technique will be propagated to the dark energy parameters to determine what design constraints are required of the onboard illumination system

A description of the NSSL cases used for a simulated VAS retrieval study

A documentation of eight National Severe Storm Laboratory severe storm cases, which serve as a basis for a simulated VISSR Atmospheric Sounder retrieval study, is presented in this paper. Six of the selected cases provide a control data set to complete the statistical information needed for retrieval techniques based upon the use of regression matrices. The other two cases are to be used in the actual retrieval experiments. The selection was based upon the presence of moisture gradients in the analysis region, the availability of satellite images at the selected time periods, and the extent of cloud cover within the observing network

The impact of conventional surface data upon VAS regression retrievals in the lower troposphere

Surface temperature and dewpoint reports are added to the infrared radiances from the VISSR Atmospheric Sounder (VAS) in order to improve the retrieval of temperature and moisture profiles in the lower troposphere. The conventional (airways) surface data are combined with the twelve VAS channels as additional predictors in a ridge regression retrieval scheme, with the aim of using all available data to make high resolution space-time interpolations of the radiosonde network. For one day of VAS observations, retrievals using only VAS radiances are compared with retrievals using VAS radiances plus surface data. Temperature retrieval accuracy evaluated at coincident radiosonde sites shows a significant impact within the boundary layer. Dewpoint retrieval accuracy shows a broader improvement within the lowest tropospheric layers. The most dramatic impact of surface data is observed in the improved relative spatial and temporal continuity of low-level fields retrieved over the Midwestern United States

Assessment of VAS soundings in the analysis of a preconvective environment

Retrievals from the VISSR Atmospheric Sounder (VAS) are combined with conventional data to assess the impact of geosynchronous satellite soundings upon the analysis of a preconvective environment. VAS retrievals of temperature, dewpoint, equivalent potential temperature, precipitable water, and lifted index are derived with 60 km resolution at 3 hour intervals. When VAS fields are combined with analyses from conventional data sources, mesoscale regions with convective instability are more clearly delineated prior to the rapid development of the thunderstorms. The retrievals differentiate isolated areas in which air extends throughout the lower troposphere from those regions where moisture is confined to a thin layer near the Earth's surface. The analyses of the VAS retrievals identify significant spatial gradients and temporal changes in the thermal and moisture fields, especially in the regions between radiosonde observations

Measuring galaxy [OII] emission line doublet with future ground-based wide-field spectroscopic surveys

The next generation of wide-field spectroscopic redshift surveys will map the large-scale galaxy distribution in the redshift range 0.7< z<2 to measure baryonic acoustic oscillations (BAO). The primary optical signature used in this redshift range comes from the [OII] emission line doublet, which provides a unique redshift identification that can minimize confusion with other single emission lines. To derive the required spectrograph resolution for these redshift surveys, we simulate observations of the [OII] (3727,3729) doublet for various instrument resolutions, and line velocities. We foresee two strategies about the choice of the resolution for future spectrographs for BAO surveys. For bright [OII] emitter surveys ([OII] flux ~30.10^{-17} erg /cm2/s like SDSS-IV/eBOSS), a resolution of R~3300 allows the separation of 90 percent of the doublets. The impact of the sky lines on the completeness in redshift is less than 6 percent. For faint [OII] emitter surveys ([OII] flux ~10.10^{-17} erg /cm2/s like DESi), the detection improves continuously with resolution, so we recommend the highest possible resolution, the limit being given by the number of pixels (4k by 4k) on the detector and the number of spectroscopic channels (2 or 3).Comment: 5 pages, 1 figur