Integration of Digital Signal Processing Block in SymbiFlow FPGA Toolchain for Artix-7 Devices

The open-source community is a valuable resource for many hobbyists and researchers interested in collaborating and contributing towards publicly available tools. In the area of field programmable gate arrays (FPGAs) this is no exception. Contributors seek to reverse-engineer the functions of large proprietary FPGA devices. An interesting challenge for open-source FPGA engineers has been reverse-engineering the operation and bitstreams of digital signal processing (DSP) blocks located in FPGAs. SymbiFlow is an open-source FPGA toolchain designed as a free alternative to proprietary computer-aided design tools like Xilinx’s Vivado. For SymbiFlow, mapping logical multipliers to DSP blocks and generating DSP block bitstreams has been left unimplemented for the Artix-7 family of FPGAs. This research seeks to rectify this shortcoming by introducing DSP information for the place and route functions into SymbiFlow. By delving into the SymbiFlow architecture definitions and creating functioning FPGA assembly code (FASM) files for Project X-Ray, a bitstream generator for Artix-7, we have been able to determine the desired output of the open-source Versatile Place & Route tool that will generate a working DSP bitstream. We diagnose and implement changes needed throughout the SymbiFlow toolchain, allowing for DSP design bitstreams to be successfully generated with open-source tools

Intensive Archaeological Survey of the East Crystal Falls Parkway (CR 272) Improvements Project, From US 183 to US 183A, Williamson County, Texas

PROJECT TITLE: Intensive Archaeological Survey of the East Crystal Falls Parkway (CR 272) Improvements Project, From US 183 to US 183A, Williamson County, Texas LOCATION: The project is located in southwestern Williamson County roughly 1.5 miles east of the City of Leander, Texas. The project begins at US 183 and runs northeastward terminating at US 183A. The project area is located on the Leander, Texas USGS 7.5-minute topographic quadrangle map. PURPOSE OF WORK: The project sponsor is fulfilling regulatory requirements in compliance with the Texas Antiquities Code and Section 106 of the National Historic Preservation Act. PROJECT SPONSOR: Texas Department of Transportation PROJECT LANDOWNER: City of Leander, Texas INSTITUTION CONDUCTING INVESTIGATION: SWCA Environmental Consultants PRINCIPAL INVESTIGATOR: Mary Jo Galindo SWCAPROJECT NUMBER: 15525-AUS. TXDOT CSJ: 0914-05-138 TEXAS ANTIQUITIES PERMIT: 5373 PERSONNEL INVOLVED IN FIELDWORK: Christian Hartnett (8 hours-archaeological field supervisor) and Abigail Peyton (8 hours-archaeological technician) PERSONNEL INVOLVED IN REPORT PREPARATION: Christian Hartnett (32 hours-report preparation), Abigail Peyton (5 hours-report preparation) and Carol Carpenter (2 hours-cartographic work). PROJECT SCOPE AND SUMMARY: The County Road (CR) CR 272 Improvements Project is approximately 1.1 miles long, 110 feet wide, and maximally 3 to 4 feet deep. The project will include a railroad crossing upgrade and other intersection, signal, and safety improvements. SWCA conducted an archaeological background review and intensive pedestrian survey of the project area to determine if any significant archaeological resources would be impacted by the proposed project. DATE OF WORK: August 20, 2009. NUMBER OF ACRES SURVEYED: Approximately 13.5 acres NUMBER OF SITES: None. CURATION: No artifacts were collected, thus nothing was curated. SUMMARY OF RESULTS AND RECOMMENDATIONS: No archaeological resources were identified during the course of fieldwork. Based on these investigations, no further archaeological work is ecommended for the proposed CR 272 Improvements Project

Characterization of edge damage induced on REBCO superconducting tape by mechanical slitting

Rare-earth barium-copper-oxide (REBCO) superconductors are high-field superconductors fabricated in a tape geometry that can be utilized in magnet applications well in excess of 20 T. Due to the multilayer architecture of the tape, delamination is one cause of mechanical failure in REBCO tapes. During a mechanical slitting step in the manufacturing process, edge cracks can be introduced into the tape. These cracks are thought to be potential initiation sites for crack propagation in the tapes when subjected to stresses in the fabrication and operation of magnet systems. We sought to understand which layers were the mechanically weakest by locating the crack initiation layer and identifying the geometrical conditions of the slitter that promoted or suppressed crack formation. The described cracking was investigated by selectively etching and characterizing each layer with scanning electron microscopy, laser confocal microscopy, and digital image analysis. Our analysis showed that the average crack lengths in the REBCO, LaMnO3 (LMO) and Al2O3 layers were 34 μm, 28 μm, and 15 μm, respectively. The total number of cracks measured in 30mmof wire length was between 3000 and 5700 depending on the layer and their crack densities were 102 cracks mm-1 for REBCO, 108 cracks mm-1 for LMO, and 183 cracks mm-1 for Al2O3. These results indicated that there are separate crack initiation mechanisms for the REBCO and the LMO layers, as detailed in the paper. With a better understanding of the crack growth behavior exhibited by REBCO tapes, the fabrication process can be improved to provide a more mechanically stable and cost-effective superconductor

Characterization of Retinal Structure in ATF6-Associated Achromatopsia.

PurposeMutations in six genes have been associated with achromatopsia (ACHM): CNGA3, CNGB3, PDE6H, PDE6C, GNAT2, and ATF6. ATF6 is the most recent gene to be identified, though thorough phenotyping of this genetic subtype is lacking. Here, we sought to test the hypothesis that ATF6-associated ACHM is a structurally distinct form of congenital ACHM.MethodsSeven genetically confirmed subjects from five nonconsanguineous families were recruited. Foveal hypoplasia and the integrity of the ellipsoid zone (EZ) band (a.k.a., IS/OS) were graded from optical coherence tomography (OCT) images. Images of the photoreceptor mosaic were acquired using confocal and nonconfocal split-detection adaptive optics scanning light ophthalmoscopy (AOSLO). Parafoveal cone and rod density values were calculated and compared to published normative data as well as data from two subjects harboring CNGA3 or CNGB3 mutations who were recruited for comparative purposes. Additionally, nonconfocal dark-field AOSLO images of the retinal pigment epithelium were obtained, with quantitative analysis performed in one subject with ATF6-ACHM.ResultsFoveal hypoplasia was observed in all subjects with ATF6 mutations. Absence of the EZ band within the foveal region (grade 3) or appearance of a hyporeflective zone (grade 4) was seen in all subjects with ATF6 using OCT. There was no evidence of remnant foveal cone structure using confocal AOSLO, although sporadic cone-like structures were seen in nonconfocal split-detection AOSLO. There was a lack of cone structure in the parafovea, in direct contrast to previous reports.ConclusionsOur data demonstrate a near absence of cone structure in subjects harboring ATF6 mutations. This implicates ATF6 as having a major role in cone development and suggests that at least a subset of subjects with ATF6-ACHM have markedly fewer cellular targets for cone-directed gene therapies than do subjects with CNGA3- or CNGB3-ACHM

Adapting a Cryogenic Sapphire Oscillator for Very Long Baseline Interferometry

Extension of very long baseline interferometry (VLBI) to observing wavelengths shorter than 1.3mm provides exceptional angular resolution (~20 micro arcsec) and access to new spectral regimes for the study of astrophysical phenomena. To maintain phase coherence across a global VLBI array at these wavelengths requires that ultrastable frequency references be used for the heterodyne receivers at all participating telescopes. Hydrogen masers have traditionally been used as VLBI references, but atmospheric turbulence typically limits (sub) millimeter VLBI coherence times to ~1-30 s. Cryogenic Sapphire Oscillators (CSO) have better stability than Hydrogen masers on these time scale and are potential alternatives to masers as VLBI references. Here, We describe the design, implementation and tests of a system to produce a 10 MHz VLBI frequency standard from the microwave (11.2 GHz) output of a CSO. To improve long-term stability of the new reference, the CSO was locked to the timing signal from the Global Positioning System satellites and corrected for the oscillator aging. The long-term performance of the CSO was measured by comparison against a hydrogen maser in the same laboratory. The superb short-term performance, along with the improved long-term performance achieved by conditioning, makes the CSO a suitable reference for VLBI at wavelengths less than 1.3mm.Comment: 24 pages, 15 figure