1,208 research outputs found

    Governing Yield Modes for Common Bolted and Nailed Wood Connections

    Full text link
    Connections in wood structures are important when designing for ductility. The 1997 Uniform Building Code has taken this into consideration when designating wind and earthquake load duration factors for connections. Factors of 1.6 or 1.33 may be applied to the connection strength, depending on the type of yield mode exhibited by the connection, which may be determined from the yield limit equations supplied in the National Design Specification for Wood Construction (NDS). The NDS provides the designer with multiple tables containing capacities for various common connections. Unfortunately, yield modes are not published along with tabulated capacities. Therefore, the designer must carry out potentially cumbersome calculations using the NDS yield limit equations simply to determine the governing yield mode before an appropriate Uniform Building Code load duration factor can be applied. In this paper, several NDS tables are extended to include capacity and yield mode, smaller side member thickness configurations are added to the existing nail/spike tables, and a useful toe-nail table is provided. The overall purpose of these tables is to accelerate the design process by eliminating time-consuming calculations

    Photoinduced Ullmann C–N Coupling: Demonstrating the Viability of a Radical Pathway

    Get PDF
    Carbon–nitrogen (C–N) bond-forming reactions of amines with aryl halides to generate arylamines (anilines), mediated by a stoichiometric copper reagent at elevated temperature (>180°C), were first described by Ullmann in 1903. In the intervening century, this and related C–N bond-forming processes have emerged as powerful tools for organic synthesis. Here, we report that Ullmann C–N coupling can be photoinduced by using a stoichiometric or a catalytic amount of copper, which enables the reaction to proceed under unusually mild conditions (room temperature or even –40°C). An array of data are consistent with a single-electron transfer mechanism, representing the most substantial experimental support to date for the viability of this pathway for Ullmann C–N couplings

    Remotely Accessible Testbed for Software Defined Radio Development

    Get PDF
    Previous development testbeds have assumed that the developer was physically present in front of the hardware being used. No provision for remote operation of basic functions (power on/off or reset) was made, because the developer/operator was sitting in front of the hardware, and could just push the button manually. In this innovation, a completely remotely accessible testbed has been created, with all diagnostic equipment and tools set up for remote access, and using standardized interfaces so that failed equipment can be quickly replaced. In this testbed, over 95% of the operating hours were used for testing without the developer being physically present. The testbed includes a pair of personal computers, one running Linux and one running Windows. A variety of peripherals is connected via Ethernet and USB (universal serial bus) interfaces. A private internal Ethernet is used to connect to test instruments and other devices, so that the sole connection to the outside world is via the two PCs. An important design consideration was that all of the instruments and interfaces used stable, long-lived industry standards, such as Ethernet, USB, and GPIB (general purpose interface bus). There are no plug-in cards for the two PCs, so there are no problems with finding replacement computers with matching interfaces, device drivers, and installation. The only thing unique to the two PCs is the locally developed software, which is not specific to computer or operating system version. If a device (including one of the computers) were to fail or become unavailable (e.g., a test instrument needed to be recalibrated), replacing it is a straightforward process with a standard, off-the-shelf device

    S-Band POSIX Device Drivers for RTEMS

    Get PDF
    This is a set of POSIX device driver level abstractions in the RTEMS RTOS (Real-Time Executive for Multiprocessor Systems real-time operating system) to SBand radio hardware devices that have been instantiated in an FPGA (field-programmable gate array). These include A/D (analog-to-digital) sample capture, D/A (digital-to-analog) sample playback, PLL (phase-locked-loop) tuning, and PWM (pulse-width-modulation)-controlled gain. This software interfaces to Sband radio hardware in an attached Xilinx Virtex-2 FPGA. It uses plug-and-play device discovery to map memory to device IDs. Instead of interacting with hardware devices directly, using direct-memory mapped access at the application level, this driver provides an application programming interface (API) offering that easily uses standard POSIX function calls. This simplifies application programming, enables portability, and offers an additional level of protection to the hardware. There are three separate device drivers included in this package: sband_device (ADC capture and DAC playback), pll_device (RF front end PLL tuning), and pwm_device (RF front end AGC control)

    Architectural Implementation of NASA Space Telecommunications Radio System Specification

    Get PDF
    This software demonstrates a working implementation of the NASA STRS (Space Telecommunications Radio System) architecture specification. This is a developing specification of software architecture and required interfaces to provide commonality among future NASA and commercial software-defined radios for space, and allow for easier mixing of software and hardware from different vendors. It provides required functions, and supports interaction with STRS-compliant simple test plug-ins ("waveforms"). All of it is programmed in "plain C," except where necessary to interact with C++ plug-ins. It offers a small footprint, suitable for use in JPL radio hardware. Future NASA work is expected to develop into fully capable software-defined radios for use on the space station, other space vehicles, and interplanetary probes

    Efficient luminescence from easily prepared three-coordinate copper(I) arylamidophosphines

    Get PDF
    A series of brightly luminescent, three-coordinate copper(I) arylamidophosphine complexes have been prepared from readily available precursors in high yield. Emission maxima span 102 nm in the visible spectrum from 461 (blue) to 563 nm (yellow) while photoluminescence quantum yields range from 0.11 to 0.24 in fluid solution at room temperature

    Visuomotor learning promotes visually evoked activity in the medial prefrontal cortex

    Get PDF
    The medial prefrontal cortex (mPFC) is necessary for executing many learned associations between stimuli and movement. It is unclear, however, how activity in the mPFC evolves across learning, and how this activity correlates with sensory stimuli and the learned movements they evoke. To address these questions, we record cortical activity with widefield calcium imaging while mice learned to associate a visual stimulus with a forelimb movement. After learning, the mPFC shows stimulus-evoked activity both during task performance and during passive viewing, when the stimulus evokes no action. This stimulus-evoked activity closely tracks behavioral performance across training, with both exhibiting a marked increase between days when mice first learn the task, followed by a steady increase with further training. Electrophysiological recordings localized this activity to the secondary motor and anterior cingulate cortex. We conclude that learning a visuomotor task promotes a route for visual information to reach the prefrontal cortex

    Levels of frailty and frailty progression in older urban- and regional-living First Nations Australians

    Get PDF
    OBJECTIVES: To explore the prevalence of frailty, association between frailty and mortality, and transitions between frailty states in urban- and regional-living First Nations Australians.STUDY DESIGN: Secondary analysis of longitudinal data from the Koori Growing Old Well Study. First Nations Australians aged 60 years or more from five non-remote communities were recruited in 2010-2012 and followed up six years later (2016-2018). Data collected at both visits were used to derive a 38-item Frailty Index (FI). The FI (range 0-1.0) was classified as robust (&lt;0.1), pre-frail (0.1- &lt; 0.2), mildly (0.2- &lt; 0.3), moderately (0.3- &lt; 0.4) or severely frail (≥0.4).MAIN OUTCOME MEASURES: Association between frailty and mortality, examined using logistic regression and transitions in frailty (the percentage of participants who changed frailty category) during follow-up.RESULTS: At baseline, 313 of 336 participants (93 %) had sufficient data to calculate a FI. Median FI score was 0.26 (interquartile range 0.21-0.39); 4.79 % were robust, 20.1 % pre-frail, 31.6 % mildly frail, 23.0 % moderately frail and 20.5 % severely frail. Higher baseline frailty was associated with mortality among severely frail participants (adjusted odds ratio 7.11, 95 % confidence interval 2.51-20.09) but not moderately or mildly frail participants. Of the 153 participants with a FI at both baseline and follow-up, their median FI score increased from 0.26 to 0.28.CONCLUSIONS: Levels of frailty in this First Nations cohort are substantially higher than in similar-aged non-Indigenous populations. Screening for frailty before the age of 70 years may be warranted in First Nations Australians. Further research is urgently needed to determine the factors that are driving such high levels of frailty and propose solutions to prevent or manage frailty in this population.</p

    Insight into Genotype-Phenotype Associations through eQTL Mapping in Multiple Cell Types in Health and Immune-Mediated Disease

    Get PDF
    Genome-wide association studies (GWAS) have transformed our understanding of the genetics of complex traits such as autoimmune diseases, but how risk variants contribute to pathogenesis remains largely unknown. Identifying genetic variants that affect gene expression (expression quantitative trait loci, or eQTLs) is crucial to addressing this. eQTLs vary between tissues and following in vitro cellular activation, but have not been examined in the context of human inflammatory diseases. We performed eQTL mapping in five primary immune cell types from patients with active inflammatory bowel disease (n = 91), anti-neutrophil cytoplasmic antibody-associated vasculitis (n = 46) and healthy controls (n = 43), revealing eQTLs present only in the context of active inflammatory disease. Moreover, we show that following treatment a proportion of these eQTLs disappear. Through joint analysis of expression data from multiple cell types, we reveal that previous estimates of eQTL immune cell-type specificity are likely to have been exaggerated. Finally, by analysing gene expression data from multiple cell types, we find eQTLs not previously identified by database mining at 34 inflammatory bowel disease-associated loci. In summary, this parallel eQTL analysis in multiple leucocyte subsets from patients with active disease provides new insights into the genetic basis of immune-mediated diseases.This research was funded by a Wellcome Trust Clinical PhD Programme Fellowship (JEP), the NIH-Oxford-Cambridge Scholars Program (ACR), Wellcome Trust Grant 083650/Z/07/Z and MRC Grant MR/L19027/1 (KGCS), and the National Institute for Health Research Cambridge Biomedical Research Centre. KGCS is a National Institute for Health Research Senior Investigator. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    JPL Space Telecommunications Radio System Operating Environment

    Get PDF
    A flight-qualified implementation of a Software Defined Radio (SDR) Operating Environment for the JPL-SDR built for the CoNNeCT Project has been developed. It is compliant with the NASA Space Telecommunications Radio System (STRS) Architecture Standard, and provides the software infrastructure for STRS compliant waveform applications. This software provides a standards-compliant abstracted view of the JPL-SDR hardware platform. It uses industry standard POSIX interfaces for most functions, as well as exposing the STRS API (Application Programming In terface) required by the standard. This software includes a standardized interface for IP components instantiated within a Xilinx FPGA (Field Programmable Gate Array). The software provides a standardized abstracted interface to platform resources such as data converters, file system, etc., which can be used by STRS standards conformant waveform applications. It provides a generic SDR operating environment with a much smaller resource footprint than similar products such as SCA (Software Communications Architecture) compliant implementations, or the DoD Joint Tactical Radio Systems (JTRS)
    • …
    corecore