2,061 research outputs found
Evidence from Patents and Patent Citations on the Impact of NASA and Other Federal Labs on Commercial Innovation
We explore the commercialization of government-generated technology by analyzing patents awarded to the U.S. government and the citations to those patents from subsequent patents. We use information on citations to federal patents in two ways: (1) to compare the average technological impact of NASA patents, other Federal' patents, and a random sample of all patents using measures of importance' and generality;' and (2) to trace the geographic location of commercial development by focusing on the location of inventors who cite NASA and other federal patents. We find, first, that the evidence is consistent with increased effort to commercialize federal lab technology generally and NASA specifically. The data reveal a striking NASA golden age' during the second half of the 1970s which remains a puzzle. Second, spillovers are concentrated within a federal lab complex of states representing agglomerations of labs and companies. The technology complex links five NASA states through patent citations: California, Texas, Ohio, DC/Virginia-Maryland, and Alabama. Third, qualitative evidence provides some support for the use of patent citations as proxies for both technological impact and knowledge spillovers.
Impact of g-factors and valleys on spin qubits in a silicon double quantum dot
We define single electron spin qubits in a silicon MOS double quantum dot
system. By mapping the qubit resonance frequency as a function of gate-induced
electric field, the spectrum reveals an anticrossing that is consistent with an
inter-valley spin-orbit coupling. We fit the data from which we extract an
inter-valley coupling strength of 43 MHz. In addition, we observe a narrow
resonance near the primary qubit resonance when we operate the device in the
(1,1) charge configuration. The experimental data is consistent with a
simulation involving two weakly exchanged-coupled spins with a g-factor
difference of 1 MHz, of the same order as the Rabi frequency. We conclude that
the narrow resonance is the result of driven transitions between the T- and T+
triplet states, using an ESR signal of frequency located halfway between the
resonance frequencies of the two individual spins. The findings presented here
offer an alternative method of implementing two-qubit gates, of relevance to
the operation of larger scale spin qubit systems
From LTL and Limit-Deterministic B\"uchi Automata to Deterministic Parity Automata
Controller synthesis for general linear temporal logic (LTL) objectives is a
challenging task. The standard approach involves translating the LTL objective
into a deterministic parity automaton (DPA) by means of the Safra-Piterman
construction. One of the challenges is the size of the DPA, which often grows
very fast in practice, and can reach double exponential size in the length of
the LTL formula. In this paper we describe a single exponential translation
from limit-deterministic B\"uchi automata (LDBA) to DPA, and show that it can
be concatenated with a recent efficient translation from LTL to LDBA to yield a
double exponential, \enquote{Safraless} LTL-to-DPA construction. We also report
on an implementation, a comparison with the SPOT library, and performance on
several sets of formulas, including instances from the 2016 SyntComp
competition
Complex diffuse radio emission in the merging PLANCK ESZ cluster Abell 3411
We present VLA radio and Chandra X-ray observations of the merging galaxy
cluster Abell 3411. For the cluster, we find an overall temperature of 6.4 keV
and an X-ray luminosity of 2.8 x 10^{44} erg s^{-1} between 0.5 and 2.0 keV.
The Chandra observation reveals the cluster to be undergoing a merger event.
The VLA observations show the presence of large-scale diffuse emission in the
central region of the cluster, which we classify as a 0.9 Mpc size radio halo.
In addition, a complex region of diffuse, polarized emission is found in the
southeastern outskirts of the cluster, along the projected merger axis of the
system. We classify this region of diffuse emission as a radio relic. The total
extent of this radio relic is 1.9 Mpc. For the combined emission in the cluster
region, we find a radio spectral index of -1.0 \pm 0.1 between 74 MHz and 1.4
GHz. The morphology of the radio relic is peculiar, as the relic is broken up
into five fragments. This suggests that the shock responsible for the relic has
been broken up due to interaction with a large-scale galaxy filament connected
to the cluster or other substructures in the ICM. Alternatively, the complex
morphology reflects the presence of electrons in fossil radio bubbles that are
re-accelerated by a shock.Comment: Accepted for publication in ApJ, 8 pages, 5 figure
The SAMI Galaxy Survey: Unveiling the nature of kinematically offset active galactic nuclei
We have observed two kinematically offset active galactic nuclei (AGN), whose
ionised gas is at a different line-of-sight velocity to their host galaxies,
with the SAMI integral field spectrograph (IFS). One of the galaxies shows gas
kinematics very different to the stellar kinematics, indicating a recent merger
or accretion event. We demonstrate that the star formation associated with this
event was triggered within the last 100 Myr. The other galaxy shows simple disc
rotation in both gas and stellar kinematics, aligned with each other, but in
the central region has signatures of an outflow driven by the AGN. Other than
the outflow, neither galaxy shows any discontinuity in the ionised gas
kinematics at the galaxy's centre. We conclude that in these two cases there is
no direct evidence of the AGN being in a supermassive black hole binary system.
Our study demonstrates that selecting kinematically offset AGN from
single-fibre spectroscopy provides, by definition, samples of kinematically
peculiar objects, but IFS or other data are required to determine their true
nature.Comment: MNRAS accepted. 14 pages, 11 figure
Integrated silicon qubit platform with single-spin addressability, exchange control and robust single-shot singlet-triplet readout
Silicon quantum dot spin qubits provide a promising platform for large-scale
quantum computation because of their compatibility with conventional CMOS
manufacturing and the long coherence times accessible using Si enriched
material. A scalable error-corrected quantum processor, however, will require
control of many qubits in parallel, while performing error detection across the
constituent qubits. Spin resonance techniques are a convenient path to parallel
two-axis control, while Pauli spin blockade can be used to realize local parity
measurements for error detection. Despite this, silicon qubit implementations
have so far focused on either single-spin resonance control, or control and
measurement via voltage-pulse detuning in the two-spin singlet-triplet basis,
but not both simultaneously. Here, we demonstrate an integrated device platform
incorporating a silicon metal-oxide-semiconductor double quantum dot that is
capable of single-spin addressing and control via electron spin resonance,
combined with high-fidelity spin readout in the singlet-triplet basis.Comment: 10 pages, 4 figure
Modeling and experimental verification of single event upsets
The research performed and the results obtained at the Laboratory for Radiation Studies, Prairie View A&M University and Texas A&I University, on the problem of Single Events Upsets, the various schemes employed to limit them and the effects they have on the reliability and fault tolerance at the systems level, such as robotic systems are reviewed
The SAMI Galaxy Survey: Asymmetry in Gas Kinematics and its links to Stellar Mass and Star Formation
We study the properties of kinematically disturbed galaxies in the SAMI
Galaxy Survey using a quantitative criterion, based on kinemetry (Krajnovic et
al.). The approach, similar to the application of kinemetry by Shapiro et al.
uses ionised gas kinematics, probed by H{\alpha} emission. By this method
23+/-7% of our 360-galaxy sub-sample of the SAMI Galaxy Survey are
kinematically asymmetric. Visual classifications agree with our kinemetric
results for 90% of asymmetric and 95% of normal galaxies. We find stellar mass
and kinematic asymmetry are inversely correlated and that kinematic asymmetry
is both more frequent and stronger in low-mass galaxies. This builds on
previous studies that found high fractions of kinematic asymmetry in low mass
galaxies using a variety of different methods. Concentration of star forma-
tion and kinematic disturbance are found to be correlated, confirming results
found in previous work. This effect is stronger for high mass galaxies (log(M*)
> 10) and indicates that kinematic disturbance is linked to centrally
concentrated star formation. Comparison of the inner (within 0.5Re) and outer
H{\alpha} equivalent widths of asymmetric and normal galaxies shows a small but
significant increase in inner equivalent width for asymmetric galaxies.Comment: 29 pages, 21 figure
The SAMI Galaxy Survey: Gas Streaming and Dynamical M/L in Rotationally Supported Systems
Line-of-sight velocities of gas and stars can constrain dark matter (DM)
within rotationally supported galaxies if they trace circular orbits
extensively. Photometric asymmetries may signify non-circular motions,
requiring spectra with dense spatial coverage. Our integral-field spectroscopy
of 178 galaxies spanned the mass range of the SAMI Galaxy Survey. We derived
circular speed curves (CSCs) of gas and stars from non-parametric Diskfit fits
out to . For 12/14 with measured H I profiles, ionized gas and H I
maximum velocities agreed. We fitted mass-follows-light models to 163 galaxies
by approximating the radial starlight profile as nested, very flattened mass
homeoids viewed as a S\'ersic form. Fitting broad-band SEDs to SDSS images gave
median stellar mass/light 1.7 assuming a Kroupa IMF vs. 2.6 dynamically.
Two-thirds of the dynamical mass/light measures were consistent with
star+remnant IMFs. One-fifth required upscaled starlight to fit, hence
comparable mass of unobserved baryons and/or DM distributed similarly across
the SAMI aperture that came to dominate motions as the starlight CSC declined
rapidly. The rest had mass distributed differently from starlight. Subtracting
fits of S\'ersic profiles to 13 VIKING Z-band images revealed residual weak
bars. Near the bar PA, we assessed m = 2 streaming velocities, and found
deviations usually <30 km/s from the CSC; three showed no deviation. Thus,
asymmetries rarely influenced our CSCs despite co-located shock-indicating,
emission-line flux ratios in more than 2/3.Comment: 21 pages, 15 figures. Accepted to MNRA
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