6 research outputs found
Scattering Parameter Measurements of the Long Wavelength Array Antenna and Front End Electronics
We present recent 2-port vector network analyzer (VNA) measurements of the
complete set of scattering parameters for the antenna used within the Long
Wavelength Array (LWA) and the associated front end electronics (FEEs). Full
scattering parameter measurements of the antenna yield not only the reflection
coefficient for each polarization, S11 and S22, but also the coupling between
polarizations, S12 and S21. These had been previously modeled using
simulations, but direct measurements had not been obtained until now. The
measurements are used to derive a frequency dependent impedance mismatch factor
(IMF) which represents the fraction of power that is passed through the
antenna-FEE interface and not reflected due to a mismatch between the impedance
of the antenna and the impedance of the FEE. We also present results from a two
antenna experiment where each antenna is hooked up to a separate port on the
VNA. This allows for cross-antenna coupling to be measured for all four
possible polarization combinations. Finally, we apply the newly measured IMF
and FEE forward gain corrections to LWA data to investigate how well they
remove instrumental effects.Comment: 16 pages, 12 figures, Accepted for publication in Publications of the
Astronomical Society of the Pacifi
Multiple Recurrent De Novo CNVs, Including Duplications of the 7q11.23 Williams Syndrome Region, Are Strongly Associated with Autism
SummaryWe have undertaken a genome-wide analysis of rare copy-number variation (CNV) in 1124 autism spectrum disorder (ASD) families, each comprised of a single proband, unaffected parents, and, in most kindreds, an unaffected sibling. We find significant association of ASD with de novo duplications of 7q11.23, where the reciprocal deletion causes Williams-Beuren syndrome, characterized by a highly social personality. We identify rare recurrent de novo CNVs at five additional regions, including 16p13.2 (encompassing genes USP7 and C16orf72) and Cadherin 13, and implement a rigorous approach to evaluating the statistical significance of these observations. Overall, large de novo CNVs, particularly those encompassing multiple genes, confer substantial risks (OR = 5.6; CI = 2.6–12.0, p = 2.4 × 10-7). We estimate there are 130–234 ASD-related CNV regions in the human genome and present compelling evidence, based on cumulative data, for association of rare de novo events at 7q11.23, 15q11.2-13.1, 16p11.2, and Neurexin 1
Anatomy in a New Curriculum: Facilitating the Learning of Gross Anatomy Using Web Access Streaming Dissection Videos
As anatomy course hours have decreased, it has become increasingly important to provide tools that facilitate laboratory task efficiency. Digital video clips were created to present dissection guidance to medical students. The video clips communicate challenging aspects of the dissection process with succinct visual demonstrations easily accessed via an online course site. Students were asked to complete a survey designed to assess the quality and utility of the videos. Survey respondents indicated that the videos enhanced the quality of the anatomy course as well as their individual performances. This teaching tool enhances student competencies in human gross anatomy