Wide binaries as a critical test for Gravity theories

Assuming Newton's gravity and GR to be valid at all scales leads to the dark matter hypothesis as a requirement demanded by the observed dynamics and measured baryonic content at galactic and extragalactic scales. Alternatively, modified gravity scenarios where a change of regime appears at acceleration scales $a<a_{0}$ have been proposed. This modified regime at $a<a_{0}$ will generically be characterised by equilibrium velocities which become independent of distance. Here we identify a critical test in this debate and we propose its application to samples of wide binary stars. Since for $1 M_{\odot}$ systems the acceleration drops below $a_{0}$ at scales of around 7000 AU, a statistical survey of wide binaries with relative velocities and separations reaching $10^{4}$ AU and beyond should prove useful to the above debate. We apply the proposed test to the best currently available data. Results show a constant upper limit to the relative velocities in wide binaries which is independent of separation for over three orders of magnitude, in analogy with galactic flat rotation curves in the same $a<a_{0}$ acceleration regime. Our results are suggestive of a breakdown of Kepler's third law beyond $a \approx a_{0}$ scales, in accordance with generic predictions of modified gravity theories designed not to require any dark matter at galactic scales and beyond.Comment: 4 pages 1 figure, Proceedings of the COSGRAV12 meeting, Kolkata, India, 7th - 11th February, 201

Neutron scattering study of magnetic phase separation in nanocrystalline La5/8_{5/8}Ca3/8_{3/8}MnO3_3

We demonstrate that magnetic phase separation and competing spin order in the colossal magnetoresistive (CMR) manganites can be directly explored via tuning strain in bulk samples of nanocrystalline La$_{1-x}$Ca$_x$MnO$_3$. Our results show that strain can be reversibly frozen into the lattice in order to stabilize coexisting antiferromagnetic domains within the nominally ferromagnetic metallic state of La$_{5/8}$Ca$_{3/8}$MnO$_3$. The measurement of tunable phase separation via magnetic neutron powder diffraction presents a direct route of exploring the correlated spin properties of phase separated charge/magnetic order in highly strained CMR materials and opens a potential avenue for realizing intergrain spin tunnel junction networks with enhanced CMR behavior in a chemically homogeneous material.Comment: 6 pages, 4 figures. New figure and text added to manuscrip

Systematic review on the effects of the physical and social aspects of community pharmacy spaces on service users and staff

AIM: This systematic review aimed to provide new insights into how pharmacy spaces, or the architecture of pharmacies, are experienced by pharmacy service users and staff. The review sought to identify environmental factors which may influence service users' and staff participation in community-based pharmacy health services. METHOD: Ten databases were searched for English language publications, using a combination of search terms relating to pharmacy service users and staff; pharmacy spaces; and health and social care outcomes. Data from the final selected studies were extracted, thematically analysed using a narrative approach and the quality of each study assessed using the Integrated quality Criteria for the Review of Multiple Study designs (ICROMS). RESULTS: 80 articles reporting 80 studies published between 1994 and 2020 were identified; they were from 28 countries, involving around 3234 community pharmacies, 13,615 pharmacy service users, 5056 pharmacists and 78 pharmacy health staff. Most studies (94%) met the ICROMS minimum score, and half did not meet the mandatory quality criteria. Four themes likely to influence service users' and staff experiences of pharmacy health services were identified: (1) privacy; (2) experience of the physical environment; (3) professional image; and (4) risk of error. CONCLUSION: To optimise the delivery and experience of pharmacy health services, these spaces should be made more engaging. Future applied research could focus on optimising inclusive pharmacy design features

Spin ordering and electronic texture in the bilayer iridate Sr3_3Ir2_2O7_7

Through a neutron scattering, charge transport, and magnetization study, the correlated ground state in the bilayer iridium oxide Sr$_3$Ir$_2$O$_7$ is explored. Our combined results resolve scattering consistent with a high temperature magnetic phase that persists above 600 K, reorients at the previously defined $T_{AF}=280$ K, and coexists with an electronic ground state whose phase behavior suggests the formation of a fluctuating charge or orbital phase that freezes below $T^{*}\approx70$ K. Our study provides a window into the emergence of multiple electronic order parameters near the boundary of the metal to insulator phase transition of the 5d $J_{eff}=1/2$ Mott phase.Comment: Revised text and figures. 4 pages, 4 figure

Magnetic order and the electronic ground state in the pyrochlore iridate Nd2Ir2O7

We report a combined muon spin relaxation/rotation, bulk magnetization, neutron scattering, and transport study of the electronic properties of the pyrochlore iridate Nd2Ir2O7. We observe the onset of strongly hysteretic behavior in the temperature dependent magnetization below 120 K, and an abrupt increase in the temperature dependent resistivity below 8 K. Zero field muon spin relaxation measurements show that the hysteretic magnetization is driven by a transition to a magnetically disordered state, and that below 8 K a complex magnetically ordered ground state sets in, as evidenced by the onset of heavily damped spontaneous muon precession. Our measurements point toward the absence of a true metal-to-insulator phase transition in this material and suggest that Nd2Ir2O7 lies either within or on the metallic side of the boundary of the Dirac semimetal regime within its topological phase diagram.Comment: 21 pages, 7 figure

Lucky Imaging of transiting planet host stars with LuckyCam

We obtained high-resolution, high-contrast optical imaging in the Sloan Digital Sky Survey i′ band with the LuckyCam camera mounted on the 2.56 m Nordic Optical Telescope, to search for faint stellar companions to 16 stars harbouring transiting exoplanets. The Lucky imaging technique uses very short exposures to obtain near diffraction-limited images yielding sub-arcsecond sensitivity, allowing us to search for faint stellar companions within the seeing disc of the primary planet host. Here, we report the detection of two candidate stellar companions to the planet host TrES-1 at separations &lt;6.5 arcsec and we confirm stellar companions to CoRoT-2, CoRoT-3, TrES-2, TrES-4 and HAT-P-7 already known in the literature. We do not confirm the candidate companions to HAT-P-8 found via Lucky imaging by Bergfors et al., however, most probably because HAT-P-8 was observed in poor seeing conditions. Our detection sensitivity limits allow us to place constraints on the spectral types and masses of the putative bound companions to the planet host stars in our sample. If bound, the stellar companions identified in this work would provide stringent observational constraints to models of planet formation and evolution. In addition, these companions could affect the derived physical properties of the exoplanets in these systems