282 research outputs found
The interaction between transpolar arcs and cusp spots
Transpolar arcs and cusp spots are both auroral phenomena which occur when
the interplanetary magnetic field is northward. Transpolar arcs are associated
with magnetic reconnection in the magnetotail, which closes magnetic flux and
results in a "wedge" of closed flux which remains trapped, embedded in the
magnetotail lobe. The cusp spot is an indicator of lobe reconnection at the
high-latitude magnetopause; in its simplest case, lobe reconnection
redistributes open flux without resulting in any net change in the open flux
content of the magnetosphere. We present observations of the two phenomena
interacting--i.e., a transpolar arc intersecting a cusp spot during part of its
lifetime. The significance of this observation is that lobe reconnection can
have the effect of opening closed magnetotail flux. We argue that such events
should not be rare
First Constraints on Compact Dark Matter from Fast Radio Burst Microstructure
Despite existing constraints, it remains possible that up to of all
dark matter is comprised of compact objects, such as the black holes in the
10-100\,M range whose existence has been confirmed by LIGO. The strong
gravitational lensing of transients such as FRBs and GRBs has been suggested as
a more sensitive probe for compact dark matter than intensity fluctuations
observed in microlensing experiments. Recently ASKAP has reported burst
substructure down to s timescales in FRBs in the redshift range
. We investigate here the implications of this for the detectability
of compact dark matter by FRBs. We find that a sample size of FRBs
would be required to constrain compact dark matter to less than the existing
35 limit with 95 confidence, if it were distributed along Gpc-long FRB sightlines through the cosmic web. Conversely, existing
constraints on the fraction of compact dark matter permit as many as 1 in
of all FRBs to exhibit micro-lensed burst
structure. Approximately FRBs intercepting halos within kpc
would be required to exclude the fraction of compact dark matter in each
intercepted halo to a similar level. Furthermore, we consider the cumulative
effects of lensing of the FRB signal by a macroscopic dark matter distribution.
We conclude that lensing from a uniform distribution of compact objects is
likely not observable, but suggest that FRBs may set meaningful limits on
power-law distributions of dark matter.Comment: 3 Figures, 1 tabl
Probing the distant universe with a very luminous fast radio burst at redshift 1
Fast radio bursts are millisecond-duration pulses of radio emission that have
been found to originate at extragalactic distances. The bursts show dispersion
imparted by intervening plasma, with the bulk attributed to the intergalactic
medium. Here we report the discovery of a burst, FRB20220610A, in a complex
host galaxy system at a redshift of . The relationship
between its redshift and dispersion confirm that the bulk of the baryonic
matter was ionized and in the intergalactic medium when the universe was almost
half its present age. The burst shows evidence for passage through a
significant additional column of turbulent and magnetized high-redshift plasma.
It extends the maximum observed burst energy by a factor of four, confirming
the presence of an energetic burst population at high redshift.Comment: 40 page
The unseen host galaxy and high dispersion measure of a precisely-localised Fast Radio Burst suggests a high-redshift origin
FRB 20210912A is a fast radio burst (FRB), detected and localised to
sub-arcsecond precision by the Australian Square Kilometre Array Pathfinder. No
host galaxy has been identified for this burst despite the high precision of
its localisation and deep optical and infrared follow-up, to 5- limits
of mag and mag with the Very Large Telescope. The
combination of precise radio localisation and deep optical imaging has almost
always resulted in the secure identification of a host galaxy, and this is the
first case in which the line-of-sight is not obscured by the Galactic disk. The
dispersion measure of this burst,
, allows for
a large source redshift of according to the Macquart relation. It could
thus be that the host galaxy is consistent with the known population of FRB
hosts, but is too distant to detect in our observations ( for a host
like that of the first repeating FRB source, FRB 20121102A); that it is more
nearby with a significant excess in , and thus dimmer than
any known FRB host; or, least likely, that the FRB is truly hostless. We
consider each possibility, making use of the population of known FRB hosts to
frame each scenario. The fact of the missing host has ramifications for the FRB
field: even with high-precision localisation and deep follow-up, some FRB hosts
may be difficult to detect, with more distant hosts being the less likely to be
found. This has implications for FRB cosmology, in which high-redshift
detections are valuable.Comment: 14 pages, 6 figures. Revised based on referee's comments and accepted
to MNRA
Social identity, social networks and recovery capital in emerging adulthood: a pilot study
Background
It has been argued that recovery from substance dependence relies on a change in identity, with past research focused on ‘personal identity’. This study assessed support for a social identity model of recovery in emerging adults through examining associations between social identity, social networks, recovery capital, and quality of life.
Methods
Twenty participants aged 18–21 in residential treatment for substance misuse were recruited from four specialist youth drug treatment services - three detoxification facilities and one psychosocial rehabilitation facility in Victoria, Australia. Participants completed a detailed social network interview exploring the substance use of groups in their social networks and measures of quality of life, recovery capital, and social identity.
Results
Lower group substance use was associated with higher recovery capital, stronger identification with non-using groups, and greater importance of non-using groups in the social network. Additionally, greater identification with and importance of non-using groups were associated with better environmental quality of life, whereas greater importance conferred on using groups was associated with reduced environmental quality of life.
Conclusions
Support was found for the role of social identity processes in reported recovery capital and quality of life. Future research in larger, longitudinal samples is required to improve understanding of social identity processes during treatment and early recovery and its relationship to recovery stability.
Keywords
Social network Social identity Emerging adult Substance use Treatment Recovery Quality of lif
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Creative and productive workplaces: a review
The built environment affects our well-being and this in turn influences our effectiveness in the workplace. Poor environments contribute to absenteeism and to people not working as well as they might. This is an enormous cost to the nation. High-quality environmental design is an investment, as occupants are healthier, staff-retention rates are higher, productivity is higher and sustainability ideals are more likely to be met. Workplaces reflect the culture of companies and are places that are not just functional and convenient but give the occupant a wholesome experience in terms of body and spirit
The fusion approach – applications for understanding local government and European integration
The article explores the theoretical capabilities of the fusion approach as a conceptual ‘kit’ to explain the ‘bigger picture’ of European integration from a local government perspective. Fusion addresses the rationales and methods facilitating the transfer of policy-making competences to the European level. It understands European integration as a merging of public resources and policy instruments from multiple levels of government, whereby accountability and responsibilities for policy outcomes become blurred. The article argues that the fusion approach is useful to explain the systemic linkages between macro-trajectories and the corresponding change at the local level; the fusion dynamics of the local and European levels in a common policy-cycle; and the attitudes of local actors towards the EU. Although the article concludes that local government is rather modestly ‘fused’ into the EU, fusion approaches allow examining the extent to which the local level has become integrated into the European governance system
Controlled creation of a singular spinor vortex by circumventing the Dirac belt trick
Persistent topological defects and textures are particularly dramatic consequences of superfluidity. Among the most fascinating examples are the singular vortices arising from the rotational symmetry group SO(3), with surprising topological properties illustrated by Dirac’s famous belt trick. Despite considerable interest, controlled preparation and detailed study of vortex lines with complex internal structure in fully three-dimensional spinor systems remains an outstanding experimental challenge. Here, we propose and implement a reproducible and controllable method for creating and detecting a singular SO(3) line vortex from the decay of a non-singular spin texture in a ferromagnetic spin-1 Bose–Einstein condensate. Our experiment explicitly demonstrates the SO(3) character and the unique spinor properties of the defect. Although the vortex is singular, its core fills with atoms in the topologically distinct polar magnetic phase. The resulting stable, coherent topological interface has analogues in systems ranging from condensed matter to cosmology and string theory
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Glucosinolates, myrosinase hydrolysis products, and flavonols found in rocket (Eruca sativa and Diplotaxis tenuifolia)
Rocket species have been shown to have very high concentrations of glucosinolates and flavonols, which have numerous positive health benefits with regular consumption. In this review we highlight how breeders and processors of rocket species can utilize genomic and phytochemical research to improve varieties and enhance the nutritive benefits to consumers. Plant breeders are increasingly looking to new technologies such as HPLC, UPLC, LC-MS and GC-MS to screen populations for their phytochemical content to inform plant selections. Here we collate the research that has been conducted to-date in rocket, and summarise all glucosinolate and flavonol compounds identified in the species. We emphasize the importance of the broad screening of populations for phytochemicals and myrosinase degradation products, as well as unique traits that may be found in underutilized gene bank resources. We also stress that collaboration with industrial partners is becoming essential for long-term plant breeding goals through research
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