Impact of the urgent care telephone service NHS 111 pilot sites: a controlled before and after study

Objectives To measure the impact of the urgent care telephone service NHS 111 on the emergency and urgent care system. Design Controlled before and after study using routine data. Setting Four pilot sites and three control sites covering a total population of 3.6 million in England, UK. Participants and data Routine data on 36 months of use of emergency ambulance service calls and incidents, emergency department attendances, urgent care contacts (general practice (GP) out of hours, walk in and urgent care centres) and calls to the telephone triage service NHS direct. Intervention NHS 111, a new 24 h 7 day a week telephone service for non-emergency health problems, operated by trained non-clinical call handlers with clinical support from nurse advisors, using NHS Pathways software to triage calls to different services and home care. Main outcomes Changes in use of emergency and urgent care services. Results NHS 111 triaged 277 163 calls in the first year of operation for a population of 1.8 million. There was no change overall in emergency ambulance calls, emergency department attendances or urgent care use. There was a 19.3% reduction in calls to NHS Direct (95% CI −24.6% to −14.0%) and a 2.9% increase in emergency ambulance incidents (95% CI 1.0% to 4.8%). There was an increase in activity overall in the emergency and urgent care system in each site ranging 4.7–12%/month and this remained when assuming that NHS 111 will eventually take all NHS Direct and GP out of hours calls. Conclusions In its first year of operation in four pilot sites NHS 111 did not deliver the expected system benefits of reducing calls to the 999 ambulance service or shifting patients to urgent rather than emergency care. There is potential that this type of service increases overall demand for urgent care

A re-examination of the anatomy and systematics of the tomistomine crocodylians from the Miocene of Italy and Malta

Once a much more globally widespread crocodylian clade, Tomistominae is today represented by just one species, Tomistoma schlegelii (the false gharial), restricted to south-east Asia. Although tomistomine fossil occurrences are recognized from the early Eocene (∼55 Ma) onwards, their remains are often incomplete, making appropriate taxonomic classification within the group problematic. This is especially pertinent to several taxa from the Miocene of Europe, which were historically erected from fragmentary remains. Here we re-examine and describe four approximately contemporaneous taxa from Malta and Italy to determine their taxonomy and phylogenetic affinities: Melitosaurus champsoides, Tomistoma calaritanum, Tomistoma gaudense and Tomistoma lyceense. We place them into a phylogenetic analysis for the first time, comprising 70 taxa scored for 244 characters, several of which are revised or novel, and apply a number of character weighting strategies. Whereas ‘Tomistoma lyceense’ is deemed to be an indeterminate tomistomine, a unique combination of features confirms Melitosaurus champsoides, Tomistoma calaritanum and Tomistoma gaudense as three distinct species. These three taxa are recovered as derived tomistomines, with characters such as a posterior maxillary process between the lacrimal and nasal, large supratemporal fenestrae that are wider than long, and the posteromedial alignment of the last three premaxillary teeth, suggesting a close relationship with the approximately contemporaneous European taxa, Tomistoma lusitanica and Gavialosuchus eggenburgensis. It is unlikely that any of these species belong to Tomistoma, with the possibility that they can all be classified under Melitosaurus and Gavialosuchus. However, we retain them in open nomenclature pending reassessment of the remaining European Miocene tomistomines. Our taxonomic and phylogenetic revision helps to elucidate past tomistomine diversity in the Miocene of the Mediterranean region, prior to the group’s extirpation, and is an important first step in resolving the complicated history of European tomistomine systematics

PS16dtm: A Tidal Disruption Event in a Narrow-line Seyfert 1 Galaxy

[Abridged] We present observations of PS16dtm, a luminous transient that occurred at the nucleus of a known Narrow-line Seyfert 1 galaxy hosting a 10$^6$ M$_\odot$ black hole. The transient was previously claimed to be a Type IIn SLSN due to its luminosity and hydrogen emission lines. The light curve shows that PS16dtm brightened by about two magnitudes in ~50 days relative to the archival host brightness and then exhibited a plateau phase for about 100 days followed by the onset of fading in the UV. During the plateau PS16dtm showed no color evolution, maintained a blackbody temperature of 1.7 x 10$^4$ K, and radiated at approximately $L_{Edd}$ of the SMBH. The spectra exhibit multi-component hydrogen emission lines and strong FeII emission, show little evolution with time, and closely resemble the spectra of NLS1s while being distinct from those of Type IIn SNe. Moreover, PS16dtm is undetected in the X-rays to a limit an order of magnitude below an archival X-ray detection of its host galaxy. These observations strongly link PS16dtm to activity associated with the SMBH and are difficult to reconcile with a SN origin or any known form of AGN variability, and therefore we argue that it is a TDE in which the accretion of the stellar debris powers the rise in the continuum and excitation of the pre-existing broad line region, while providing material that obscures the X-ray emitting region of the pre-existing AGN accretion disk. A detailed TDE model fit to the light curve indicates that PS16dtm will remain bright for several years; we further predict that the X-ray emission will reappear on a similar timescale as the accretion rate declines. Finally, we place PS16dtm in the context of other TDEs and find that TDEs in AGN galaxies are an order of magnitude more efficient and reach Eddington luminosities, likely due to interaction of the stellar debris with the pre-existing accretion disk.Comment: 19 pages, 17 figures, Submitted to Ap

Spitzer Space Telescope Infrared Observations of the Binary Neutron Star Merger GW170817

We present Spitzer Space Telescope 3.6 and 4.5 micron observations of the binary neutron star merger GW170817 at 43, 74, and 264 days post-merger. Using the final observation as a template, we uncover a source at the position of GW170817 at 4.5 micron with a brightness of 22.9+/-0.3 AB mag at 43 days and 23.8+/-0.3 AB mag at 74 days (the uncertainty is dominated by systematics from the image subtraction); no obvious source is detected at 3.6 micron to a 3-sigma limit of >23.3 AB mag in both epochs. The measured brightness is dimmer by a factor of about 2-3 times compared to our previously published kilonova model, which is based on UV, optical, and near-IR data at <30 days. However, the observed fading rate and color (m_{3.6}-m_{4.5}> 0 AB mag) are consistent with our model. We suggest that the discrepancy is likely due to a transition to the nebular phase, or a reduced thermalization efficiency at such late time. Using the Spitzer data as a guide, we briefly discuss the prospects of observing future binary neutron star mergers with Spitzer (in LIGO/Virgo Observing Run 3) and the James Webb Space Telescope (in LIGO/Virgo Observing Run 4 and beyond).Comment: 6 pages, 2 figures, submitted to ApJ

A multi-messenger model for neutron star - black hole mergers

We present a semi-analytic model for predicting kilonova light curves from the mergers of neutron stars with black holes (NSBH). The model is integrated into the MOSFiT platform, and can generate light curves from input binary properties and nuclear equation-of-state considerations, or incorporate measurements from gravitational wave (GW) detectors to perform multi-messenger parameter estimation. The rapid framework enables the generation of NSBH kilonova distributions from binary populations, light curve predictions from GW data, and statistically meaningful comparisons with an equivalent BNS model in MOSFiT. We investigate a sample of kilonova candidates associated with cosmological short gamma-ray bursts, and demonstrate that they are broadly consistent with being driven by NSBH systems, though most have limited data. We also perform fits to the very well sampled GW170817, and show that the inability of an NSBH merger to produce lanthanide-poor ejecta results in a significant underestimate of the early (< 2 days) optical emission. Our model indicates that NSBH-driven kilonovae may peak up to a week after merger at optical wavelengths for some observer angles. This demonstrates the need for early coverage of emergent kilonovae in cases where the GW signal is either ambiguous or absent; they likely cannot be distinguished from BNS mergers by the light curves alone from ~2 days after the merger. We also discuss the detectability of our model kilonovae with the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST).Comment: 14 pages, 6 figures, 2 tables. Accepted for publication in MNRAS. This is the author's final submitted version. The model code is available through MOSFiT at https://github.com/guillochon/MOSFi

Tight multi-messenger constraints on the neutron star equation of state from GW170817 and a forward model for kilonova light curve synthesis

We present a rapid analytic framework for predicting kilonova light curves following neutron star (NS) mergers, where the main input parameters are binary-based properties measurable by gravitational wave detectors (chirp mass and mass ratio, orbital inclination) and properties dependent on the nuclear equation of state (tidal deformability, maximum NS mass). This enables synthesis of a kilonova sample for any NS source population, or determination of the observing depth needed to detect a live kilonova given gravitational wave source parameters in low latency. We validate this code, implemented in the public MOSFiT package, by fitting it to GW170817. A Bayes factor analysis overwhelmingly ($B>10^{10}$) favours the inclusion of an additional luminosity source in addition to lanthanide-poor dynamical ejecta during the first day. This is well fit by a shock-heated cocoon model, though differences in the ejecta structure, opacity or nuclear heating rate cannot be ruled out as alternatives. The emission thereafter is dominated by a lanthanide-rich viscous wind. We find the mass ratio of the binary is $q=0.92\pm0.07$ (90% credible interval). We place tight constraints on the maximum stable NS mass, $M_{\rm TOV}=2.17^{+0.08}_{-0.11}$ M$_\odot$. For a uniform prior in tidal deformability, the radius of a 1.4 M$_\odot$ NS is $R_{1.4}\sim 10.7$ km. Re-weighting with a prior based on equations of state that support our credible range in $M_{\rm TOV}$, we derive a final measurement $R_{1.4}=11.06^{+1.01}_{-0.98}$ km. Applying our code to the second gravitationally-detected neutron star merger, GW190425, we estimate that an associated kilonova would have been fainter (by $\sim0.7$ mag at one day post-merger) and declined faster than GW170817, underlining the importance of tuning follow-up strategies individually for each GW-detected NS merger.Comment: Updated to match accepted version in MNRA

Theory-assisted determination of nano-rippling and impurities in atomic resolution images of angle-mismatched bilayer graphene

Ripples and impurity atoms are universally present in 2D materials, limiting carrier mobility, creating pseudo–magnetic fields, or affecting the electronic and magnetic properties. Scanning transmission electron microscopy (STEM) generally provides picometer-level precision in the determination of the location of atoms or atomic 'columns' in the in-image plane (xy plane). However, precise atomic positions in the z-direction as well as the presence of certain impurities are difficult to detect. Furthermore, images containing moiré patterns such as those in angle-mismatched bilayer graphene compound the problem by limiting the determination of atomic positions in the xy plane. Here, we introduce a reconstructive approach for the analysis of STEM images of twisted bilayers that combines the accessible xy coordinates of atomic positions in a STEM image with density-functional-theory calculations. The approach allows us to determine all three coordinates of all atomic positions in the bilayer and establishes the presence and identity of impurities. The deduced strain-induced rippling in a twisted bilayer graphene sample is consistent with the continuum model of elasticity. We also find that the moiré pattern induces undulations in the z direction that are approximately an order of magnitude smaller than the strain-induced rippling. A single substitutional impurity, identified as nitrogen, is detected. The present reconstructive approach can, therefore, distinguish between moiré and strain-induced effects and allows for the full reconstruction of 3D positions and atomic identities

Improved constraints on H0 from a combined analysis of gravitational-wave and electromagnetic emission from GW170817

The luminosity distance measurement of GW170817 derived from GW analysis in Abbott et al. 2017 (here, A17:H0) is highly correlated with the measured inclination of the NS-NS system. To improve the precision of the distance measurement, we attempt to constrain the inclination by modeling the broad-band X-ray-to-radio emission from GW170817, which is dominated by the interaction of the jet with the environment. We update our previous analysis and we consider the radio and X-ray data obtained at $t<40$ days since merger. We find that the afterglow emission from GW170817 is consistent with an off-axis relativistic jet with energy $10^{48}\,\rm{erg}<E_{k}\le 3\times 10^{50} \,\rm{erg}$ propagating into an environment with density $n\sim10^{-2}-10^{-4} \,\rm{cm^{-3}}$, with preference for wider jets (opening angle $\theta_j=15$ deg). For these jets, our modeling indicates an off-axis angle $\theta_{\rm obs}\sim25-50$ deg. We combine our constraints on $\theta_{\rm obs}$ with the joint distance-inclination constraint from LIGO. Using the same $\sim 170$ km/sec peculiar velocity uncertainty assumed in A17:H0 but with an inclination constraint from the afterglow data, we get a value of $H_0=$$74.0 \pm \frac{11.5}{7.5}$ \mbox{km/s/Mpc}, which is higher than the value of $H_0=$$70.0 \pm \frac{12.0}{8.0}$ \mbox{km/s/Mpc} found in A17:H0. Further, using a more realistic peculiar velocity uncertainty of 250 km/sec derived from previous work, we find $H_0=$$75.5 \pm \frac{11.6}{9.6}$ km/s/Mpc for H0 from this system. We note that this is in modestly better agreement with the local distance ladder than the Planck CMB, though a significant such discrimination will require $\sim 50$ such events. Future measurements at $t>100$ days of the X-ray and radio emission will lead to tighter constraints.Comment: Submitted to ApJL. Comments Welcome. Revised uncertainties in v

The Binary Neutron Star event LIGO/VIRGO GW170817 a hundred and sixty days after merger: synchrotron emission across the electromagnetic spectrum

We report deep Chandra, HST and VLA observations of the binary neutron star event GW170817 at $t<160$ d after merger. These observations show that GW170817 has been steadily brightening with time and might have now reached its peak, and constrain the emission process as non-thermal synchrotron emission where the cooling frequency $\nu_c$ is above the X-ray band and the synchrotron frequency $\nu_m$ is below the radio band. The very simple power-law spectrum extending for eight orders of magnitude in frequency enables the most precise measurement of the index $p$ of the distribution of non-thermal relativistic electrons $N(\gamma)\propto \gamma^{-p}$ accelerated by a shock launched by a NS-NS merger to date. We find $p=2.17\pm0.01$, which indicates that radiation from ejecta with $\Gamma\sim3-10$ dominates the observed emission. While constraining the nature of the emission process, these observations do \emph{not} constrain the nature of the relativistic ejecta. We employ simulations of explosive outflows launched in NS ejecta clouds to show that the spectral and temporal evolution of the non-thermal emission from GW170817 is consistent with both emission from radially stratified quasi-spherical ejecta traveling at mildly relativistic speeds, \emph{and} emission from off-axis collimated ejecta characterized by a narrow cone of ultra-relativistic material with slower wings extending to larger angles. In the latter scenario, GW170817 harbored a normal SGRB directed away from our line of sight. Observations at $t\le 200$ days are unlikely to settle the debate as in both scenarios the observed emission is effectively dominated by radiation from mildly relativistic material.Comment: Updated with the latest VLA and Chandra dat

A Decline in the X-ray through Radio Emission from GW170817 Continues to Support an Off-Axis Structured Jet

We present new observations of the binary neutron star merger GW170817 at $\Delta t\approx 220-290$ days post-merger, at radio (Karl G. Jansky Very Large Array; VLA), X-ray (Chandra X-ray Observatory) and optical (Hubble Space Telescope; HST) wavelengths. These observations provide the first evidence for a turnover in the X-ray light curve, mirroring a decline in the radio emission at $\gtrsim5\sigma$ significance. The radio-to-X-ray spectral energy distribution exhibits no evolution into the declining phase. Our full multi-wavelength dataset is consistent with the predicted behavior of our previously published models of a successful structured jet expanding into a low-density circumbinary medium, but pure cocoon models with a choked jet cannot be ruled out. If future observations continue to track our predictions, we expect that the radio and X-ray emission will remain detectable until $\sim 1000$ days post-merger.Comment: Accepted to ApJL. Updated version includes new VLA observations extending through 2018 June