6,200 research outputs found
Advanced information processing system: Authentication protocols for network communication
In safety critical I/O and intercomputer communication networks, reliable message transmission is an important concern. Difficulties of communication and fault identification in networks arise primarily because the sender of a transmission cannot be identified with certainty, an intermediate node can corrupt a message without certainty of detection, and a babbling node cannot be identified and silenced without lengthy diagnosis and reconfiguration . Authentication protocols use digital signature techniques to verify the authenticity of messages with high probability. Such protocols appear to provide an efficient solution to many of these problems. The objective of this program is to develop, demonstrate, and evaluate intercomputer communication architectures which employ authentication. As a context for the evaluation, the authentication protocol-based communication concept was demonstrated under this program by hosting a real-time flight critical guidance, navigation and control algorithm on a distributed, heterogeneous, mixed redundancy system of workstations and embedded fault-tolerant computers
Cross-correlating Carbon Monoxide Line-intensity Maps with Spectroscopic and Photometric Galaxy Surveys
Line-intensity mapping (LIM or IM) is an emerging field of observational
work, with strong potential to fit into a larger effort to probe large-scale
structure and small-scale astrophysical phenomena using multiple complementary
tracers. Taking full advantage of such complementarity means, in part,
undertaking line-intensity surveys with galaxy surveys in mind. We consider the
potential for detection of a cross-correlation signal between COMAP and blind
surveys based on photometric redshifts (as in COSMOS) or based on spectroscopic
data (as with the HETDEX survey of Lyman- emitters). We find that
obtaining accuracy in redshifts and
sources per Mpc with spectroscopic redshift determination
should enable a CO-galaxy cross spectrum detection significance at least twice
that of the CO auto spectrum. Either a future targeted spectroscopic survey or
a blind survey like HETDEX may be able to meet both of these requirements.Comment: 19 pages + appendix (31 pages total), 16 figures, 6 tables; accepted
for publication in Ap
The C-Band All-Sky Survey (C-BASS): New Constraints on the Integrated Radio Spectrum of M 31
The Andromeda galaxy (M31) is our closest neighbouring spiral galaxy, making
it an ideal target for studying the physics of the interstellar medium in a
galaxy very similar to our own. Using new observations of M31 at 4.76GHz by the
C-Band All-Sky Survey (C-BASS), and all available radio data at
resolution, we produce the integrated spectrum and put new constraints on the
synchrotron spectral index and anomalous microwave emission (AME) from M31. We
use aperture photometry and spectral modelling to fit for the integrated
spectrum of M31, and subtract a comprehensive model of nearby background radio
sources. The AME in M31 is detected at significance with a peak near
30GHz and flux density Jy. The synchrotron spectral index of M31
is flatter than our own Galaxy at with no strong
evidence of spectral curvature. The emissivity of AME, averaged over the total
emission from M31 is lower than typical AME sources in our Galaxy, implying
that AME is not uniformly distributed throughout M31 and instead is likely
confined to sub-regions -- this will need to be confirmed using future higher
resolution observations around 20--30GHz.Comment: 16 pages, 6 figures, submitted to MNRA
SKAO HI intensity mapping: blind foreground subtraction challenge
Neutral Hydrogen Intensity Mapping (H I IM) surveys will be a powerful new probe of cosmology. However, strong astrophysical
foregrounds contaminate the signal and their coupling with instrumental systematics further increases the data cleaning
complexity. In this work, we simulate a realistic single-dish HI IM survey of a 5000 deg2 patch in the 950–1400 MHz
range, with both the MID telescope of the SKA Observatory (SKAO) and MeerKAT, its precursor. We include a state-of-the-art
HI simulation and explore different foreground models and instrumental effects such as non-homogeneous thermal noise and
beam side lobes. We perform the first Blind Foreground Subtraction Challenge for HI IM on these synthetic data cubes, aiming
to characterize the performance of available foreground cleaning methods with no prior knowledge of the sky components and
noise level. Nine foreground cleaning pipelines joined the challenge, based on statistical source separation algorithms, blind
polynomial fitting, and an astrophysical-informed parametric fit to foregrounds. We devise metrics to compare the pipeline
performances quantitatively. In general, they can recover the input maps’ two-point statistics within 20 per cent in the range of
scales least affected by the telescope beam. However, spurious artefacts appear in the cleaned maps due to interactions between
the foreground structure and the beam side lobes. We conclude that it is fundamental to develop accurate beam deconvolution
algorithms and test data post-processing steps carefully before cleaning. This study was performed as part of SKAO preparatory
work by the HI IM Focus Group of the SKA Cosmology Science Working Group
The assessment of neuromuscular fatigue during 120 min of simulated soccer exercise
Purpose
This investigation examined the development of neuromuscular fatigue during a simulated soccer match incorporating a period of extra time (ET) and the reliability of these responses on repeated test occasions.
Methods
Ten male amateur football players completed a 120 min soccer match simulation (SMS). Before, at half time (HT), full time (FT), and following a period of ET, twitch responses to supramaximal femoral nerve and transcranial magnetic stimulation (TMS) were obtained from the knee-extensors to measure neuromuscular fatigue. Within 7 days of the first SMS, a second 120 min SMS was performed by eight of the original ten participants to assess the reliability of the fatigue response.
Results
At HT, FT, and ET, reductions in maximal voluntary force (MVC; −11, −20 and −27%, respectively, P ≤ 0.01), potentiated twitch force (−15, −23 and −23%, respectively, P < 0.05), voluntary activation (FT, −15 and ET, −18%, P ≤ 0.01), and voluntary activation measured with TMS (−11, −15 and −17%, respectively, P ≤ 0.01) were evident. The fatigue response was robust across both trials; the change in MVC at each time point demonstrated a good level of reliability (CV range 6–11%; ICC2,1 0.83–0.94), whilst the responses identified with motor nerve stimulation showed a moderate level of reliability (CV range 5–18%; ICC2,1 0.63–0.89) and the data obtained with motor cortex stimulation showed an excellent level of reliability (CV range 3–6%; ICC2,1 0.90–0.98).
Conclusion
Simulated soccer exercise induces a significant level of fatigue, which is consistent on repeat tests, and involves both central and peripheral mechanisms
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Metabolism and Excretion Rates of Parent and Hydroxy-PAHs in Urine Collected after Consumption of Traditionally Smoked Salmon for Native American Volunteers
Few studies have been published on the excretion rates of parent polycyclic aromatic hydrocarbons (PAHs) and hydroxy-polycyclic aromatic hydrocarbons (OH-PAHs) following oral exposure. This study investigated metabolism and excretion rates of 4 parent PAHs and 10 OH-PAHs after the consumption of smoked salmon. Nine members of the Confederated Tribes of the Umatilla Indian Reservation consumed 50 g of traditionally smoked salmon with breakfast and five urine samples were collected during the following 24 hours. The concentrations of OH-PAHs increased from 43.9 µg/g creatinine for 2-OH-Nap to 349 ng/g creatinine for 1-OH-Pyr, 3
to 6 hr post-consumption. Despite volunteers following a restricted diet, there appeared to be a secondary source of naphthalene and fluorene, which led to excretion efficiencies greater than 100%. For the parent PAHs that were detected in urine, the excretion efficiencies ranged from 13% for phenanthrene (and its metabolite) to 240% for naphthalene (and its metabolites). The half-lives for PAHs ranged from 1.4 hr for retene to 3.3 hr for pyrene. The half-lives for OH-PAHs were higher and ranged from 1.7 hr for 9-OH-fluorene to 7.0 hr for 3-OH-fluorene. The concentrations of most parent PAHs, and their metabolites, returned to the background levels 24 hr post-consumption
Tackling alcoholism and domestic violence in fisheries - a new opportunity to improve wellbeing for the most vulnerable people in global fisheries
The UN Sustainable Development Goals (SDGs) principle of ‘Leaving no one behind’ focusses global attention on the poorest and most vulnerable people. As different sectors grapple to engage meaningfully with this principle, we posit that greater consideration of social problems in fishing-dependent communities, such as alcoholism and domestic violence, presents an opportunity for fisheries governors to contribute to the SDGs mandate. We further argue that governing marine resources in ignorance of these problems can risk harming some of the most vulnerable people in fisheries. Using subjective wellbeing data from women living in two small-scale fishing communities in India and Sri Lanka, we demonstrate the prevalence and impact of alcoholism and domestic violence in fishing households. We further highlight how policies which restrict access to marine resources can undermine important coping strategies, in particular the ability of women to act as independent income-earners, exacerbating harm to already vulnerable women. A scoping review of the literature reveals that alcoholism and domestic violence are reported in certain fisheries around the world, and we theorise how this may relate to the nature of fishing life, and growing stresses regarding the future of fishing. Tackling the burdens of alcoholism and domestic violence in fisheries, where it is an issue, is an opportunity to improve wellbeing for men, women and their families. The paper concludes with tangible actions which marine resource governors could adopt to contribute to the ‘leave no one behind’ ethos
Effect of neoadjuvant treatment with anastrozole on tumour histology in postmenopausal women with large operable breast cancer
Anastrozole is an orally active, non-steroidal aromatase inhibitor which appears effective as neoadjuvant treatment of breast cancer. Histological changes have been evaluated in biopsies from large, oestrogen-receptor rich, operable breast tumours in postmenopausal women following 12 weeks of neoadjuvant anastrozole treatment (1 mg (n=12) or 10 mg (n=11)). Of the 23 patients, 18 had a clinical response following treatment. Compared with pre-treatment biopsies anastrozole-treated specimens displayed decreased cellularity and/or increased fibrosis in 15 tumours; changes in gland formation, nuclear pleomorphism, or mitoses, in 12 cases; and a reduction in Mib1 score in all tumours. Marked changes in apoptotic scores were seen following treatment but the direction of effect was inconsistent. In all 17 tumours which were positive for progesterone receptors before therapy, treatment was associated with reduced staining for progesterone receptors. There was no consistent effect of treatment on oestrogen-receptor expression. It is concluded that neoadjuvant anastrozole treatment in this patient group has marked effects on tumour histopathology but these do not always correlate with clinical response
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