742 research outputs found
Transatlantic Relations: Past, Present, and Future. College of Europe Policy Brief #7.November 2019
> The United States and Europe have a rich history of
cooperation which played a fundamental role in the
establishment of the post-World War II international
order with its tissue of multilateral structures
that helped to generate an unprecedented period of
peace and stability in the world.
> The new millennium posed a number of difficult
challenges to the partners with 9/11 and the wars
in Afghanistan and Iraq, financial crisis and a global
recession that exploded confidence in financial institutions,
economic policy and, ultimately, political
institutions, the effects of which are still felt today.
> However, it was the election of President Trump in
2016 that led to the most sustained divergence
across the entire spectrum of relations: from defence
and security to climate change and trade. It
has also exposed the structural features of a divide
which pose a more fundamental threat to the longterm
future of the transatlantic alliance.
> The present drift towards disconnection can only be
overcome by ensuring that common ground is
found and that all parties are comfortable with the
balance of rights and responsibilities. The European
Union could play a leading role in reinventing the
transatlantic relationship for the next generation by
seeking to achieve a reinvigorated transatlantic
partnership with the United States covering, in particular,
security, trade, and common approaches to
the emergence of a new global order
A deep Chandra observation of the poor cluster AWM4 - II. The role of the radio jets in enriching the intra-cluster medium
We use a Chandra observation of the poor cluster AWM4 to map the temperature
and abundance of the intra-cluster medium, so as to examine the influence of
the central radio galaxy on its environment. While the cluster core is
generally enriched to near-solar abundances, we find evidence of super-solar
abundances correlated with the radio jets, extending ~35 kpc from the core of
the central dominant galaxy NGC 6051 along its minor axis. We conclude that the
enriched gas has been transported out of the central galaxy through the action
of the radio source. We estimate the excess mass of iron in the entrained gas
to be ~1.4x10^6 Msol, and find that this can be produced in the core of NGC
6051 within the timescale of the AGN outburst. The energy required to transport
this gas to its current location is ~4.5x10^57 erg, a significant fraction of
the estimated total mechanical energy output of the AGN, though this estimate
is dependent on the degree of enrichment of the uplifted gas. The larger
near-solar abundance region is also compatible with enrichment by metals mixed
outward from NGC 6051 over a much longer timescale.Comment: Accepted for publication in MNRAS, 11 pages, 6 figure
Evaluation of Skin-mounted Sensor for Head Impact Measurement
Background: The requirement to measure the number and severity of head impacts in sports has led to the development of wearable sensors.
Aim: The objective of this study was to determine the reliability and accuracy of a wearable head impact sensor: xPatch, X2Biosystems Inc.
Methods: The skin mounted sensor, xPatch, was fixed onto a Hybrid III headform, and dropped using an impact test rig. Four hundred impacts were performed, ranging from 20 to 200g linear acceleration, and impact velocities of 1.2m/s to 3.9m/s. During each impact, the peak linear acceleration, angular velocity and angular acceleration, were recorded and compared to reference calibrated data. Impacts were also recorded using a high-speed video camera.
Results: The linear acceleration recorded by the xPatch during frontal and side impacts had errors of up to 24% when compared to the referenced data. The angular velocity and angular acceleration had substantially larger errors of up to 47.5% and 57% respectively. The location of the impact had a significant effect on the results: if the impact was to the side of the head, the device on that side may have an error of up to 71%, thus highlighting the importance of device location. All impacts were recorded using two separate xPatches and, in certain cases, the difference in angular velocity between the devices was 43%.
Conclusion: The xPatch can be useful for identifying impacts and recording linear accelerations during front and side impacts, but the rotational velocity and acceleration data needs to be interpreted with caution
Clues on black hole feedback from simulated and observed X-ray properties of elliptical galaxies
The centers of elliptical galaxies host supermassive black holes that
significantly affect the surrounding interstellar medium through feedback
resulting from the accretion process. The evolution of this gas and of the
nuclear emission during the galaxies' lifetime has been studied recently with
high-resolution hydrodynamical simulations. These included gas cooling and
heating specific for an average AGN spectral energy distribution, a radiative
efficiency declining at low mass accretion rates, and mechanical coupling
between the hot gas and AGN winds. Here we present a short summary of the
observational properties resulting from the simulations, focussing on 1) the
nuclear luminosity; 2) the global luminosity and temperature of the hot gas; 3)
its temperature profile and X-ray brightness profile. These properties are
compared with those of galaxies of the local universe, pointing out the
successes of the adopted feedback and the needs for new input in the
simulations.Comment: 15 pages, 6 figures, accepted for publication in Advances in Space
Researc
Cavities and shocks in the galaxy group HCG 62 as revealed by Chandra, XMM and GMRT data
We report on the results of an analysis of Chandra, XMM-Newton and new GMRT
data of the X-ray bright compact group of galaxies HCG 62, which is one of the
few groups known to possess clear, small X-ray cavities in the inner regions.
This is part of an ongoing X-ray/low-frequency radio study of 18 groups,
initially chosen for the availability of good-quality X-ray data and evidence
for AGN/hot gas interaction. At higher frequency (1.4 GHz), the HCG 62 cavity
system shows minimal if any radio emission, but the new GMRT observations at
235 MHz and 610 MHz clearly detect extended low-frequency emission from radio
lobes corresponding to the cavities. By means of the synergy of X-ray and
low-frequency radio observations, we compare and discuss the morphology,
luminosity and pressure of the gas and of the radio source. We find that the
radio source is radiatively inefficient, with a ratio of radio luminosity to
mechanical cavity power of , and that the radio pressure of the
lobes is about one order of magnitude lower than the X-ray pressure of the
surrounding thermal gas. Thanks to the high spatial resolution of the Chandra
surface brightness and temperature profiles, we also identify a shock front
located at 36 kpc to the south-west of the group center, close to the southern
radio lobe, with a Mach number and a total power which is about one
order of magnitude higher than the cavity power. Such a shock may have heated
the gas in the southern region, as indicated by the temperature map. The shock
may also explain the arc-like region of enriched gas seen in the iron abundance
map, as this may be produced by a non-Maxwellian electron distribution near its
front.Comment: 14 pages, 8 figures, accepted for publication in ApJ. Revised version
including minor comments and expanded discussion (version with full
resolution figures available at
http://hea-www.harvard.edu/~mgitti/hcg62-gitti.pdf
Methodological “Learning-by-Doing” for Action Design Research
This study shares the direct experiences of designing and implementing methodological “learning-by-doing” for Action Design Research (ADR) within a 5-credit module that condenses the realities of completing a full ADR project without compromising the rigour of the approach. The module is described in detail, along with the specifics of its implementation over two years and the key learnings from doing so. Adopting a confessional writing approach, documented experiences from those involved (both designers and students) provide a rich data source, analysed using autonomous and communicative reflexivity. The underlying contribution of this paper is that it provides insights into the learning of ADR, the doing of ADR, and the outcomes of a technique that simultaneously combines both. As a result, ADR educators and researchers can draw on these insights to further their teaching, learning, and research endeavours. Finally, key insights such as forced pragmatism and the challenge of problematisation add to our understanding of conducting ADR while avoiding issues such as methodological slurring
Biomechanical Performance Factors for Development of Minimum Disability Requirements in Para-taekwondo – Part 1
Objective: To assess taekwondo sparring performance variables, such as joint ranges of motion, reaction times, and kicking foot speeds, to serve as a framework for developing sport-specific classification in Para-taekwondo competition. Methods: After a standard taekwondo warm up, athletes executed five popular scoring techniques, back kick, cut kick, fast kick, turning kick, and tornado kick five times each (25 total). Kinematic and kinetic variables were recorded by a motion capture system of seven infrared cameras and two force plates. Maximum joint range of motion, foot velocities, and reaction time were calculated. Results: Collapsed over kick, maximum hip abduction motion, maximum hip flexion, maximum knee flexion, peak foot velocity, reaction time for male athletes were 47.8 ±10.4°, 46.3 ±7.6°, 105.3 ±14.0°, 11.5 ±2.4 m/s, and 0.46 ±0.06 s respectively. maximum hip abduction motion, maximum hip flexion, maximum knee flexion, peak foot velocity, reaction time for female athletes were 49.1 ±6.8°, 43.9 ±11.0°, 94.2 ±13.7°, 10.9 ±2.2 m/s, and 0.48 ±0.11 s respectively. Conclusions: The results of this study provide a foundational framework for future studies designed to compare and assess Para-taekwondo athletes with various physical and neurological impairments. From this, future studies may move towards developing practical on-site sport specific testing methods which may ultimately assist in making taekwondo-specific classification for Para-taekwondo competitions
Monkeypox: another test for PCR
Monkeypox was declared a public health emergency of international concern by the World Health Organization (WHO) on 23 July 2022. Between 1 January and 23 July 2022, 16,016 laboratory confirmed cases of monkeypox and five deaths were reported to WHO from 75 countries on all continents. Public health authorities are proactively identifying cases and tracing their contacts to contain its spread. As with COVID-19, PCR is the only method capable of being deployed at sufficient speed to provide timely feedback on any public health interventions. However, at this point, there is little information on how those PCR assays are being standardised between laboratories. A likely reason is that testing is still limited on a global scale and that detection, not quantification, of monkeypox virus DNA is the main clinical requirement. Yet we should not be complacent about PCR performance. As testing requirements increase rapidly and specimens become more diverse, it would be prudent to ensure PCR accuracy from the outset to support harmonisation and ease regulatory conformance. Lessons from COVID-19 should aid implementation with appropriate material, documentary and methodological standards offering dynamic mechanisms to ensure testing that most accurately guides public health decisions
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