Numerically determined transport laws for fingering ("thermohaline") convection in astrophysics

We present the first three-dimensional simulations of fingering convection performed in a parameter regime close to the one relevant for astrophysics, and reveal the existence of simple asymptotic scaling laws for turbulent heat and compositional transport. These laws can straightforwardly be extrapolated to the true astrophysical regime. Our investigation also indicates that thermocompositional "staircases," a key consequence of fingering convection in the ocean, cannot form spontaneously in the fingering regime in stellar interiors. Our proposed empirically-determined transport laws thus provide simple prescriptions for mixing by fingering convection in a variety of astrophysical situations, and should, from here on, be used preferentially over older and less accurate parameterizations. They also establish that fingering convection does not provide sufficient extra mixing to explain observed chemical abundances in RGB stars.Comment: Submitted to ApJ Letters on October 29th. 15 pages, 4 figures. See Garaud 2010 for companion pape

Can children resist making interpretations when uncertain?

In two experiments we examined young children’s ability to delay a response to ambiguous input. In Experiment 1 5- and 6- year olds performed as poorly when they had to choose between basing an interpretation on ambiguous input and delaying an interpretation as when making explicit evaluations of knowledge. Seven- and 8- year olds’ found the former task easy. In Experiment 2 5- and 6- year olds performed well on a task that required delaying a response but removed the need to decide between strategies. We discuss children’s difficulty with ambiguity in terms of the decision making demands made by different procedures. These demands appear to cause particular problems for young children

Surface energetics and structure of the Ge wetting layer on Si(100)

Ge deposited on Si(100) initially forms heteroepitaxial layers, which grow to a critical thickness of ~3 MLs before the appearance of three-dimensional strain relieving structures. Experimental observations reveal that the surface structure of this Ge wetting layer is a dimer vacancy line (DVL) superstructure of the unstrained Ge(100) dimer reconstruction. In the following, the results of first-principles calculations of the thickness dependence of the wetting layer surface excess energy for the c(4×2) and 4×6 DVL surface reconstructions are reported. These results predict a wetting layer critical thickness of ~3 MLs, which is largely unaffected by the presence of dimer vacancy lines. The 4×6 DVL reconstruction is found to be thermodynamically stable with respect to the c(4×2) structure for wetting layers at least 2 ML thick. A strong correlation between the fraction of total surface induced deformation present in the substrate and the thickness dependence of wetting layer surface energy is also shown

Secukinumab in the treatment of psoriasis: patient selection and perspectives.

Secukinumab is a human monoclonal antibody targeting IL-17A that has been approved for three indications: moderate-to-severe plaque psoriasis, psoriatic arthritis, and ankylosing spondylitis. In Phase III clinical trials for each of these three indications, secukinumab has proven to be both highly efficacious and well-tolerated. However, several biologic medications are currently approved for the treatment of moderate-to-severe plaque psoriasis, and many demonstrate excellent efficacy and safety. Due to this wide selection, it is often unclear how to choose biologics for specific patients. Important considerations in biologic selection include clinical efficacy, safety, cost, convenience, onset of action, and management of comorbid disease. This article aims to outline the key considerations in patient selection for the treatment of plaque psoriasis with secukinumab

Stress corrosion cracking of titanium alloys: SCC velocity: concentration of TiCl3

Stress corrosion cracking of titanium alloys, velocity of cracking in aqueous and methanol solutions and halogenated organic solvents, concentration of TiCl3 in crack

The Time Capsule and the Cut Up: Negotiating Temporality, Anticipating Catastrophe

The first feature film made about the design and deployment of the atomic bomb, The Beginning or the End (1947), begins with fake newsreel footage depicting the burial in a time capsule of a copy of the film and a projector to show it on. The scene, with its funereal overtones yet grim optimism that, even in the face of catastrophic destruction, the germ of civilisation will endure, recalls the ceremonies surrounding the interment of the Westinghouse time capsule at the New York World's Fair in 1939. Time capsules, this article argues, stand in a complex relation to war and temporality, seeking to at once anticipate and work through the challenge posed to futurity by the threat of global conflict. As a container, the capsule attempts to deliver and control the reception of a legible inventory of the present, yet the principle of selection and the impossibility of predicting how information might be received in the deep future – if it is received at all – threatens this aim. The dilemma faced by time capsule curators is, we argue with reference to William Burroughs' and Brion Gysin's so-called cut -up method of writing, one of control. By reading the time capsule through the cut-up, anticipated catastrophe can be seen to be functioning proleptically in the present and already active as a challenge to the capsule as proof against disaster

Simulations of the Galaxy Cluster CIZA J2242.8+5301 I: Thermal Model and Shock Properties

The giant radio relic in CIZA J2242.8+5301 is likely evidence of a Mpc sized shock in a massive merging galaxy cluster. However, the exact shock properties are still not clearly determined. In particular, the Mach number derived from the integrated radio spectrum exceeds the Mach number derived from the X-ray temperature jump by a factor of two. We present here a numerical study, aiming for a model that is consistent with the majority of observations of this galaxy cluster. We first show that in the northern shock upstream X-ray temperature and radio data are consistent with each other. We then derive progenitor masses for the system using standard density profiles, X-ray properties and the assumption of hydrostatic equilibrium. We find a class of models that is roughly consistent with weak lensing data, radio data and some of the X-ray data. Assuming a cool-core versus non-cool-core merger, we find a fiducial model with a total mass of $1.6 \times 10^{15}\,M_\odot$, a mass ratio of 1.76 and a Mach number that is consistent with estimates from the radio spectrum. We are not able to match X-ray derived Mach numbers, because even low mass models over-predict the X-ray derived shock speeds. We argue that deep X-ray observations of CIZA J2242.8+5301 will be able to test our model and potentially reconcile X-ray and radio derived Mach numbers in relics.Comment: 19 pages, 19 figure