No Heavy Element Dispersion in the Globular Cluster M92

Although there have been recent claims that there is a large dispersion in the abundances of the heavy neutron capture elements in the old Galactic globular cluster M92, we show that the measured dispersion for the absolute abundances of four of the rare earth elements within a sample of 12 luminous red giants in M92 (less than or equal to 0.07 dex) does not exceed the relevant sources of uncertainty. As expected from previous studies, the heavy elements show the signature of the r-process. Their abundance ratios are essentially identical to those of M30, another nearby globular cluster of similar metallicity.Comment: Accepted for publication in ApJ Letter

Algebraic Properties of Valued Constraint Satisfaction Problem

The paper presents an algebraic framework for optimization problems expressible as Valued Constraint Satisfaction Problems. Our results generalize the algebraic framework for the decision version (CSPs) provided by Bulatov et al. [SICOMP 2005]. We introduce the notions of weighted algebras and varieties and use the Galois connection due to Cohen et al. [SICOMP 2013] to link VCSP languages to weighted algebras. We show that the difficulty of VCSP depends only on the weighted variety generated by the associated weighted algebra. Paralleling the results for CSPs we exhibit a reduction to cores and rigid cores which allows us to focus on idempotent weighted varieties. Further, we propose an analogue of the Algebraic CSP Dichotomy Conjecture; prove the hardness direction and verify that it agrees with known results for VCSPs on two-element sets [Cohen et al. 2006], finite-valued VCSPs [Thapper and Zivny 2013] and conservative VCSPs [Kolmogorov and Zivny 2013].Comment: arXiv admin note: text overlap with arXiv:1207.6692 by other author

Model Independent Tests of Skyrmions and Their Holographic Cousins

We describe a new exact relation for large $N_c$ QCD for the long-distance behavior of baryon form factors in the chiral limit. This model-independent relation is used to test the consistency of the structure of several baryon models. All 4D semiclassical chiral soliton models satisfy the relation, as does the Pomarol-Wulzer holographic model of baryons as 5D Skyrmions. However, remarkably, we find that the holographic model treating baryons as instantons in the Sakai-Sugimoto model does not satisfy the relation.Comment: v2. Added references, corrected typo

Dynamical dispersion relation for ELKO dark spinor fields

An intrinsic mass generation mechanism for exotic ELKO dark matter fields is scrutinized, in the context of the very special relativity (VSR). Our results are reported on unraveling inequivalent spin structures that educe an additional term on the associated Dirac operator. Contrary to the spinor fields of mass dimension 3/2, this term is precluded to be absorbed as a shift of some gauge vector potential, regarding the equations for the dark spinor fields. It leads to some dynamical constraints that can be intrinsically converted into a dark spinor mass generation mechanism, with the encoded symmetries maintained by the VSR. The dynamical mass is embedded in the VSR framework through a natural coupling to the kink solution of a \lambda \phi^{4} theory for a scalar field \phi. Our results evince the possibility of novel effective scenarios, derived from exotic couplings among dark spinor fields and scalar field topological solutions.Comment: 6 pages, to appear in Phys.Lett.

Anomalous diffusion in polymers: long-time behaviour

We study the Dirichlet boundary value problem for viscoelastic diffusion in polymers. We show that its weak solutions generate a dissipative semiflow. We construct the minimal trajectory attractor and the global attractor for this problem.Comment: 13 page

NGC 2419 -- Another Remnant of Accretion by the Milky Way

We isolate a sample of 43 upper RGB stars in the extreme outer halo Galactic globular cluster NGC 2419 from two Keck/DEIMOS slitmasks. The probability that there is more than one contaminating halo field star in this sample is extremely low. Analysis of moderate resolution spectra of these cluster members, as well as of our Keck/HIRES high resolution spectra of a subsample of them, demonstrates that there is a small but real spread in Ca abundance of ~ 0.2 dex within this massive metal-poor globular cluster. This provides additional support to earlier suggestions that NGC 2419 is the remnant of a dwarf galaxy accreted long ago by the Milky Way.Comment: Accepted to the Astrophysical Journa

How I treat anticoagulant-refractory thrombotic antiphospholipid syndrome

The standard treatment of thrombotic antiphospholipid syndrome (APS) is lifelong oral anticoagulation with a vitamin K antagonist (VKA), generally warfarin. A minority of APS patients re-thrombose despite seemingly adequate anticoagulation. These patients are deemed anticoagulant-refractory. The management of anticoagulant-refractory APS is largely empirical and extrapolated from other clinically similar situations. Further options include increased VKA anticoagulation intensity or alternative antithrombotic strategies, including low-molecular-weight heparin, fondaparinux, the addition of antiplatelet therapy and consideration of vascular options. Anticoagulant-refractory thrombotic APS patients may have APS-associated thrombocytopenia, which necessitates balancing the risk of recurrent thrombosis versus bleeding, to achieve adequate anticoagulation. The multiple mechanisms involved in the generation of the thrombotic phenotype in APS suggest that anticoagulation alone may not control thrombosis. Thus, other modalities, including adjunctive treatment (hydroxychloroquine, statins and vitamin D) for APS-related thrombosis merit consideration, as well as immunomodulatory therapy and complement inhibition. APS patients may have coexistent systemic lupus erythematosus, which adds to the complexity of managing their thromboembolic disease. However, with attention to detail and judicious application of the limited data, it is possible to minimise the morbidity resulting from anticoagulant-refractory thrombotic APS. Multicentre studies are required to guide the sequence of interventions and their comparative efficacy in patients with anticoagulant-refractory thrombotic APS