887 research outputs found

    Operations analysis of Fleet battle experiments using the Battlespace Information War methodology: preliminary report

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    This report outlines an approach for quantitative operations analysis of aspects of Fleet Battle Experiments (FBEs) using the methodology underlying the Battlespace Information War (BAT/IW) analytical tool. The general approach of this analysis methodology is to focus on a specific experimental initiative from one or more FBEs, such as Time Critical Targeting (TCT). BAT/IW models are then tailored to the experimental situation using actual data obtained from one or more experiments and the experiment systems architecture. After the models and actual data are reconciled, further analysis tasks are undertaken, such as predictions of the effects of attack intensity, and/or of C4ISR response time reduction. BAT/IW modeling helps analyze and understand the system-level impact of sensor data quality, including timeliness, as one contributor to total operation/campaign success. BAT/IW modeling also accounts for the latency involved in processing information, including communications delays, decision time, waiting, etc. An example is developed to show how operational data obtained during FBE Foxtrot can be quantitatively analyzed to indicate important sensitivities.--Report documentation page.Approved for public release; distribution is unlimited

    Magnitude effects for experienced rewards at short delays in the escalating interest task

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    A first-person shooter video game was adapted for the study of choice between smaller sooner and larger later rewards. Participants chose when to fire a weapon that increased in damage potential over a short interval. When the delay to maximum damage was shorter (5 – 8 s), people showed greater sensitivity to the consequences of their choices than when the delay was longer (17 – 20 s). Participants also evidenced a magnitude effect by waiting proportionally longer when the damage magnitudes were doubled for all rewards. The experiment replicated the standard magnitude effect with this new video game preparation over time scales similar to those typically used in nonhuman animal studies and without complications due to satiation or cost

    PAPER-64 Constraints On Reionization II: The Temperature Of The z=8.4 Intergalactic Medium

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    We present constraints on both the kinetic temperature of the intergalactic medium (IGM) at z=8.4, and on models for heating the IGM at high-redshift with X-ray emission from the first collapsed objects. These constraints are derived using a semi-analytic method to explore the new measurements of the 21 cm power spectrum from the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER), which were presented in a companion paper, Ali et al. (2015). Twenty-one cm power spectra with amplitudes of hundreds of mK^2 can be generically produced if the kinetic temperature of the IGM is significantly below the temperature of the Cosmic Microwave Background (CMB); as such, the new results from PAPER place lower limits on the IGM temperature at z=8.4. Allowing for the unknown ionization state of the IGM, our measurements find the IGM temperature to be above ~5 K for neutral fractions between 10% and 85%, above ~7 K for neutral fractions between 15% and 80%, or above ~10 K for neutral fractions between 30% and 70%. We also calculate the heating of the IGM that would be provided by the observed high redshift galaxy population, and find that for most models, these galaxies are sufficient to bring the IGM temperature above our lower limits. However, there are significant ranges of parameter space that could produce a signal ruled out by the PAPER measurements; models with a steep drop-off in the star formation rate density at high redshifts or with relatively low values for the X-ray to star formation rate efficiency of high redshift galaxies are generally disfavored. The PAPER measurements are consistent with (but do not constrain) a hydrogen spin temperature above the CMB temperature, a situation which we find to be generally predicted if galaxies fainter than the current detection limits of optical/NIR surveys are included in calculations of X-ray heating.Comment: companion paper to Ali et al. (2015), ApJ 809, 61; matches version accepted to ApJ; 11 pages, 7 figure

    Mycobacterium tuberculosis pks12 Produces a Novel Polyketide Presented by CD1c to T Cells

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    CD1c-mediated T cells are activated by a mycobacterial phospholipid antigen whose carbohydrate structure precisely corresponds to mammalian mannosyl β-1-phosphodolichol (MPD), but contains an unusual lipid moiety. Here, we show that this T cell antigen is a member of a family of branched, alkane lipids that vary in length (C30-34) and are produced by medically important mycobacteria such as M. tuberculosis and M. bovis Bacille-Calmette-Guerin. The alkane moiety distinguished these mycobacterial lipid antigens from mammalian MPDs and was necessary for activation of CD1c-restricted T cells, but could not be accounted for by any known lipid biosynthetic pathway. Metabolic labeling and mass spectrometric analyses suggested a mechanism for elongating lipids using alternating C2 and C3 units, rather than C5 isopentenyl pyrophosphate. Inspection of the M. tuberculosis genome identified one candidate gene, pks12, which was predicted to encode the largest protein in M. tuberculosis, consisting of 12 catalytic domains that correspond to key steps in the proposed pathway. Genetic deletion and complementation showed that Pks12 was necessary for antigen production, but did not affect synthesis of true isoprenols. These studies establish the genetic and enzymatic basis for a previously unknown type of polyketide, designated mycoketide, which contains a lipidic pathogen-associated molecular pattern

    Quantum teleportation on a photonic chip

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    Quantum teleportation is a fundamental concept in quantum physics which now finds important applications at the heart of quantum technology including quantum relays, quantum repeaters and linear optics quantum computing (LOQC). Photonic implementations have largely focussed on achieving long distance teleportation due to its suitability for decoherence-free communication. Teleportation also plays a vital role in the scalability of photonic quantum computing, for which large linear optical networks will likely require an integrated architecture. Here we report the first demonstration of quantum teleportation in which all key parts - entanglement preparation, Bell-state analysis and quantum state tomography - are performed on a reconfigurable integrated photonic chip. We also show that a novel element-wise characterisation method is critical to mitigate component errors, a key technique which will become increasingly important as integrated circuits reach higher complexities necessary for quantum enhanced operation.Comment: Originally submitted version - refer to online journal for accepted manuscript; Nature Photonics (2014

    Comment on Rojas-Bracho and Colleagues (2019): Unsubstantiated Claims Can Lead to Tragic Conservation Outcomes

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    The vaquita’s decline is a tragic story indeed. However, the lack of action to prevent the extinction of this species is not due to unsubstantiated claims and scientific uncertainty
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