Pulsar spin-down: the glitch-dominated rotation of PSR J0537-6910

The young, fast-spinning, X-ray pulsar J0537-6910 displays an extreme glitch activity, with large spin-ups interrupting its decelerating rotation every ~100 days. We present nearly 13 years of timing data from this pulsar, obtained with the {\it Rossi X-ray Timing Explorer}. We discovered 22 new glitches and performed a consistent analysis of all 45 glitches detected in the complete data span. Our results corroborate the previously reported strong correlation between glitch spin-up size and the time to the next glitch, a relation that has not been observed so far in any other pulsar. The spin evolution is dominated by the glitches, which occur at a rate ~3.5 per year, and the post-glitch recoveries, which prevail the entire inter-glitch intervals. This distinctive behaviour provides invaluable insights into the physics of glitches. The observations can be explained with a multi-component model which accounts for the dynamics of the neutron superfluid present in the crust and core of neutron stars. We place limits on the moment of inertia of the component responsible for the spin-up and, ignoring differential rotation, the velocity difference it can sustain with the crust. Contrary to its rapid decrease between glitches, the spin-down rate increased over the 13 years, and we find the long-term braking index $n_{\rm l}=-1.22(4)$, the only negative braking index seen in a young pulsar. We briefly discuss the plausible interpretations of this result, which is in stark contrast to the predictions of standard models of pulsar spin-down.Comment: Minor changes to match the MNRAS accepted versio

The enigmatic spin evolution of PSR J0537-6910: r-modes, gravitational waves and the case for continued timing

We discuss the unique spin evolution of the young X-ray pulsar PSR J0537-6910, a system in which the regular spin down is interrupted by glitches every few months. Drawing on the complete timing data from the Rossi X-ray Timing Explorer (RXTE, from 1999-2011), we argue that a trend in the inter-glitch behaviour points to an effective braking index close to $n=7$, much larger than expected. This value is interesting because it would accord with the neutron star spinning down due to gravitational waves from an unstable r-mode. We discuss to what extent this, admittedly speculative, scenario may be consistent and if the associated gravitational-wave signal would be within reach of ground based detectors. Our estimates suggest that one may, indeed, be able to use future observations to test the idea. Further precision timing would help enhance the achievable sensitivity and we advocate a joint observing campaign between the Neutron Star Interior Composition ExploreR (NICER) and the LIGO-Virgo network.Comment: 10 pages, 4 figures, emulate ApJ forma

Perfusion in ENT imaging

AbstractPerfusion MRI is an essential part of characterizing salivary gland tumors. The shape of the curves can provide a guide as to the type of lesion: benign (ascending plateau) or malignant (descending plateau), and can also occasionally strongly suggest a histological type such as a Warthin tumor (intense, rapid contrast enhancement with washout>30%). Perfusion imaging (CT or MRI) for other head and neck tumors is currently being developed and is being assessed. It should be a tool to assist in choosing the most appropriate initial treatment (chemotherapy, radiotherapy or surgery) and should also allow poor responders to conservative treatment to be identified and recurrences to be detected in post-treatment damaged tissues. Aims: (a) to determine when to perform perfusion MRI; (b) to determine the type of perfusion to carry out: CT, T1-weighted MRI; (c) to determine how to position the region of interest to plot the perfusion curve; (d) to know how to interpret MRI curves for salivary gland tumors; (e) to know how to interpret the information obtained from perfusion CT or MRI for the upper aerodigestive tract

Accelerating COBAYA3 on multi-core CPU and GPU systems using PARALUTION

COBAYA3 is a multi-physics system of codes which includes two 3D multi-group neutron diffusion codes, ANDES and COBAYA3-PBP, coupled with COBRA-TF, COBRA-IIIc and SUBCHANFLOW sub-channel thermal-hydraulic codes, for the simulation of LWR core transients. The 3D multi-group neutron diffusion equations are expressed in terms of a sparse linear system which can be solved using different iterative Krylov subspace solvers. The mathematical SPARSKIT library has been used for these purposes as it implements among others, external GMRES, PGMRES and BiCGStab solvers. Multi-core CPUs and graphical processing units (GPUs) provide high performance capabilities which are able to accelerate many scientific computations. To take advantage of these new hardware features in daily use computer codes, the integration of the PARALUTION library to solve sparse systems of linear equations is a good choice. It features several types of iterative solvers and preconditioners which can run on both multi-core CPUs and GPU devices without any modification from the interface point of view. This feature is due to the great portability obtained by the modular and flexible design of the library. By exploring this technology, namely the implementation of the PARALUTION library in COBAYA3, we are able to decrease the solution time of the sparse linear systems by a factor 5.15x on GPU and 2.56x on multi-core CPU using standard hardware. These obtained speedup factors in addition to the implementation details are discussed in this paper

The evolution of depletion zones beneath mud volcanoes

Depletion zones are the least well understood component of mud volcanic systems. They are generally difficult to image using reflection seismic data, and have only rarely been identified and described in the subsurface. This study documents 277 mapped depletion zones in the western Nile Cone, offshore Egypt, of which the dimensions and stratigraphic characteristics of a sub-set of 86 depletion zones associated with mud volcanoes of early Pliocene to Recent age are recorded. The primary database used is a large (4,300 km2) 3D seismic survey in which depletion zones can be confidently interpreted using a set of simple criteria. The sub-set of 86 depletion zones were selected for morphometric analysis by virtue of the quality of seismic imaging. The depletion zones are characterised by circular to elliptical planforms with a bowl or conical geometry. They exhibit truncational stratal relationships with their parent stratigraphic unit, which in this area is the Mid-Late Miocene aged OM2 unit, and which occurs directly beneath the Messinian Evaporites. This geometry implies a top-down formation mechanism. Their diameters and relief range from is 600 m–3300 m, and 100 m–740 m, respectively, with a modest scaling relationship between diameter and relief. Flank angles of bowls and cones range from 11⁰ to 41⁰, with a crudely normal distribution, with median and mean values of 26⁰. A model for the evolution of depletion zones in the study area is based on two previous models developed for single source layer plumbing systems and invokes mobilisation of the source layer by sediment collapse and shear-induced liquefaction following initial seal failure by hydraulic fracturing of the evaporite seal. This mechanism may be more widely applicable to mud volcano systems than currently appreciated

Some Properties of Entire Functions Associated with L-entire Functions on C(I)

In this paper, let C(I) denote the Banach algebra of all continuous complex-valued functions defined on a close interval I in the set of real numbers, R. The functions having derivatives in the Lorch sense on the whole Banach algebra C(I) are considered and they are called L-entire functions [1, 3]. For each L-entire function on C(I), entire complex functions are associated and the relationship between their orders is studied. Even more, the possibility of locating the solutions of the equation F(f) = 0 from the location of zeros of the associated family of entire functions with F is analyzed too

Early optical spectra of nova V1369 Cen show presence of Lithium

We present early high resolution spectroscopic observations of the nova V1369 Cen. We have detected an absorption feature at 6695.6 \AA\, that we have identified as blue--shifted $^7$Li I $\lambda$6708 \AA. The absorption line, moving at -550 km/s, was observed in five high-resolution spectra of the nova obtained at different epochs. On the basis of the intensity of this absorption line we infer that a single nova outburst can inject in the Galaxy $M_{Li} =$ 0.3 - 4.8 $\times 10^{-10}$ M$_{\odot}$. Given the current estimates of Galactic nova rate, this amount is sufficient to explain the puzzling origin of the overabundance of Lithium observed in young star populations.Comment: 6 pages, 5 figures, accepted for publication in ApJLetter

Safety and Pharmacokinetics of a Four Monoclonal Antibody Combination Against Botulinum C and D Neurotoxins.

Botulism is caused by botulinum neurotoxin (BoNT), the most poisonous substance known. BoNTs are also classified as Tier 1 biothreat agents due to their high potency and lethality. The existence of seven BoNT serotypes (A-G), which differ between 35% to 68% in amino acid sequence, necessitates the development of serotype specific countermeasures. We present results of a Phase 1 clinical study of an anti-toxin to BoNT serotypes C and D, NTM-1634, which consists of an equimolar mixture of four fully human IgG1 monoclonal antibodies (mAbs), each binding to non-overlapping epitopes on BoNT serotypes C and D resulting in potent toxin neutralization in rodents. This first-in-human study evaluated the safety and pharmacokinetics of escalating doses of NTM-1634 administered intravenously to healthy adults (NCT03046550). Three cohorts of eight healthy subjects received a single intravenous dose of NTM-1634 or placebo at 0.33 mg/kg, 0.66 mg/kg or 1 mg/kg. Follow-up examinations and pharmacokinetic evaluations were continued up to 121 days post-infusion. Subjects were monitored using physical examinations, hematology and chemistry blood tests, and electrocardiograms. Pharmacokinetic parameters were estimated using noncompartmental methods. The results demonstrated that the materials were safe and well-tolerated with the expected half-lives for human mAbs and with minimal anti-drug antibodies detected over the dose ranges and duration of the study

The Mass-Radius Relationship for Very Low Mass Stars: Four New Discoveries from the HATSouth Survey

We report the discovery of four transiting F-M binary systems with companions between 0.1-0.2 Msun in mass by the HATSouth survey. These systems have been characterised via a global analysis of the HATSouth discovery data, combined with high-resolution radial velocities and accurate transit photometry observations. We determined the masses and radii of the component stars using a combination of two methods: isochrone fitting of spectroscopic primary star parameters, and equating spectroscopic primary star rotation velocity with spin-orbit synchronisation. These new very low mass companions are HATS550-016B (0.110 -0.006/+0.005 Msun, 0.147 -0.004/+0.003 Rsun), HATS551-019B (0.17 -0.01/+0.01 Msun, 0.18 -0.01/+0.01 Rsun), HATS551-021B (0.132 -0.005/+0.014 Msun, 0.154 -0.008/+0.006 Rsun), HATS553-001B (0.20 -0.02/+0.01 Msun, 0.22 -0.01/+0.01 Rsun). We examine our sample in the context of the radius anomaly for fully-convective low mass stars. Combining our sample with the 13 other well-studied very low mass stars, we find a tentative 5% systematic deviation between the measured radii and theoretical isochrone models.Comment: 17 pages, 8 figures, accepted for publication in MNRA