The Lazarus Project. II. Spacelike extraction with the quasi-Kinnersley tetrad

The Lazarus project was designed to make the most of limited 3D binary black-hole simulations, through the identification of perturbations at late times, and subsequent evolution of the Weyl scalar $\Psi_4$ via the Teukolsky formulation. Here we report on new developments, employing the concept of the ``quasi-Kinnersley'' (transverse) frame, valid in the full nonlinear regime, to analyze late-time numerical spacetimes that should differ only slightly from Kerr. This allows us to extract the essential information about the background Kerr solution, and through this, to identify the radiation present. We explicitly test this procedure with full numerical evolutions of Bowen-York data for single spinning black holes, head-on and orbiting black holes near the ISCO regime. These techniques can be compared with previous Lazarus results, providing a measure of the numerical-tetrad errors intrinsic to the method, and give as a by-product a more robust wave extraction method for numerical relativity.Comment: 17 pages, 10 figures. Journal version with text changes, revised figures. [Note updated version of original Lazarus paper (gr-qc/0104063)

Changes in energy content of lunchtime purchases from fast food restaurants after introduction of calorie labelling: cross sectional customer surveys

Objective To assess the impact of fast food restaurants adding calorie labelling to menu items on the energy content of individual purchases

Optical signature of symmetry variations and spin-valley coupling in atomically thin tungsten dichalcogenides

Motivated by the triumph and limitation of graphene for electronic applications, atomically thin layers of group VI transition metal dichalcogenides are attracting extensive interest as a class of graphene-like semiconductors with a desired band-gap in the visible frequency range. The monolayers feature a valence band spin splitting with opposite sign in the two valleys located at corners of 1st Brillouin zone. This spin-valley coupling, particularly pronounced in tungsten dichalcogenides, can benefit potential spintronics and valleytronics with the important consequences of spin-valley interplay and the suppression of spin and valley relaxations. Here we report the first optical studies of WS2 and WSe2 monolayers and multilayers. The efficiency of second harmonic generation shows a dramatic even-odd oscillation with the number of layers, consistent with the presence (absence) of inversion symmetry in even-layer (odd-layer). Photoluminescence (PL) measurements show the crossover from an indirect band gap semiconductor at mutilayers to a direct-gap one at monolayers. The PL spectra and first-principle calculations consistently reveal a spin-valley coupling of 0.4 eV which suppresses interlayer hopping and manifests as a thickness independent splitting pattern at valence band edge near K points. This giant spin-valley coupling, together with the valley dependent physical properties, may lead to rich possibilities for manipulating spin and valley degrees of freedom in these atomically thin 2D materials

Differential Requirements for Myeloid Leukemia IFN-γ Conditioning Determine Graft-versus-Leukemio Resistance and Sensitivity

The graft-versus-leukemia (GVL) effect in allogeneic hematopoietic stem cell transplantation (alloSCT) is potent against chronic phase chronic myelogenous leukemia (CP-CML), but blast crisis CML (BC-CML) and acute myeloid leukemias (AML) are GVL resistant. To understand GVL resistance, we studied GVL against mouse models of CP-CML, BC-CML, and AML generated by the transduction of mouse BM with fusion cDNAs derived from human leukemias. Prior work has shown that CD4+ T cell-mediated GVL against CP-CML and BC-CML required intact leukemia MHCII; however, stem cells from both leukemias were MHCII negative. Here, we show that CP-CML, BC-CML, and AML stem cells upregulate MHCII in alloSCT recipients. Using gene-deficient leukemias, we determined that BC-CML and AML MHC upregulation required IFN-γ stimulation, whereas CP-CML MHC upregulation was independent of both the IFN-γ receptor (IFN-γR) and the IFN-α/β receptor IFNAR1. Importantly, IFN-γR-deficient BC-CML and AML were completely resistant to CD4- and CD8-mediated GVL, whereas IFN-γR/IFNAR1 double-deficient CP-CML was fully GVL sensitive. Mouse AML and BC-CML stem cells were MHCI+ without IFN-γ stimulation, suggesting that IFN-γ sensitizes these leukemias to T cell killing by mechanisms other than MHC upregulation. Our studies identify the requirement of IFN-γ stimulation as a mechanism for BC-CML and AML GVL resistance, whereas independence from IFN-γ renders CP-CML more GVL sensitive, even with a lower-level alloimmune response

The mass shell in the semi-relativistic Pauli-Fierz model

We consider the semi-relativistic Pauli-Fierz model for a single free electron interacting with the quantized radiation field. Employing a variant of Pizzo's iterative analytic perturbation theory we construct a sequence of ground state eigenprojections of infra-red cutoff, dressing transformed fiber Hamiltonians and prove its convergence, as the cutoff goes to zero. Its limit is the ground state eigenprojection of a certain Hamiltonian unitarily equivalent to a renormalized fiber Hamiltonian acting in a coherent state representation space. The ground state energy is an exactly two-fold degenerate eigenvalue of the renormalized Hamiltonian, while it is not an eigenvalue of the original fiber Hamiltonian unless the total momentum is zero. These results hold true, for total momenta inside a ball about zero of arbitrary radius p>0, provided that the coupling constant is sufficiently small depending on p and the ultra-violet cutoff. Along the way we prove twice continuous differentiability and strict convexity of the ground state energy as a function of the total momentum inside that ball.Comment: 44 page

Effectiveness of a large-scale distribution programme of free nicotine patches: a prospective evaluation

Abstract BACKGROUND: After an increase in cigarette taxes and implementation of smoke-free workplace legislation, the New York City Department of Health and Mental Hygiene, the New York State Department of Health, and the Roswell Park Cancer Institute undertook large-scale distribution of free nicotine replacement therapy (NRT). We did a 6 month follow-up survey to assess the success of this programme in improving smoking cessation on a population basis. METHODS: 34,090 eligible smokers who phoned a toll-free quitline were sent a 6-week course of nicotine patches (2 weeks each of 21 mg, 14 mg, and 7 mg per day). Brief follow-up counselling calls were attempted. At 6 months after treatment, we assessed smoking status of 1305 randomly sampled NRT recipients and a non-randomly selected comparison group of eligible smokers who, because of mailing errors, did not receive the treatment. NRT recipients were compared with local survey-derived data for heavy smokers in New York City. FINDINGS: An estimated 5% of all adults in New York City who smoked ten cigarettes or more daily received NRT; most (64%) recipients were non-white, foreign-born, or resided in a low-income neighbourhood. Of individuals contacted at 6 months, more NRT recipients than comparison group members successfully quit smoking (33%vs 6%, p\u3c0.0001), and this difference remained significant after adjustment for demographic factors and amount smoked (odds ratio 8.8, 95% CI 4.4-17.8). Highest quit rates were associated with those who were foreign born (87 [39%]), older than 65 years (40 [47%]), and smoked less than 20 cigarettes per day (116 [35%]). Those who received a counselling call were more likely to stop smoking than those who did not (246 [38%] vs 189 [27%], p=0.001). With the conservative assumption that every 6-month follow-up survey non-respondent continued to smoke, the stop rate among NRT recipients was 20%. At least 6038 successful quits were attributable to NRT receipt, and cost was 464 US dollars per quit. INTERPRETATION: Easy access to cessation medication for diverse populations could help many more smokers to stop

Gravito-electromagnetism

We develop and apply a fully covariant 1+3 electromagnetic analogy for gravity. The free gravitational field is covariantly characterized by the Weyl gravito-electric and gravito-magnetic spatial tensor fields, whose dynamical equations are the Bianchi identities. Using a covariant generalization of spatial vector algebra and calculus to spatial tensor fields, we exhibit the covariant analogy between the tensor Bianchi equations and the vector Maxwell equations. We identify gravitational source terms, couplings and potentials with and without electromagnetic analogues. The nonlinear vacuum Bianchi equations are shown to be invariant under covariant spatial duality rotation of the gravito-electric and gravito-magnetic tensor fields. We construct the super-energy density and super-Poynting vector of the gravitational field as natural U(1) group invariants, and derive their super-energy conservation equation. A covariant approach to gravito-electric/magnetic monopoles is also presented.Comment: 14 pages. Version to appear in Class. Quant. Gra

Gravitational ultrarelativistic spin-orbit interaction and the weak equivalence principle

It is shown that the gravitational ultrarelativistic spin-orbit interaction violates the weak equivalence principle in the traditional sense. This fact is a direct consequence of the Mathisson-Papapetrou equations in the frame of reference comoving with a spinning test particle. The widely held assumption that the deviation of a spinning test body from a geodesic trajectory is caused by tidal forces is not correctComment: 12 page

Gravito-electromagnetic analogies

We reexamine and further develop different gravito-electromagnetic (GEM) analogies found in the literature, and clarify the connection between them. Special emphasis is placed in two exact physical analogies: the analogy based on inertial fields from the so-called "1+3 formalism", and the analogy based on tidal tensors. Both are reformulated, extended and generalized. We write in both formalisms the Maxwell and the full exact Einstein field equations with sources, plus the algebraic Bianchi identities, which are cast as the source-free equations for the gravitational field. New results within each approach are unveiled. The well known analogy between linearized gravity and electromagnetism in Lorentz frames is obtained as a limiting case of the exact ones. The formal analogies between the Maxwell and Weyl tensors are also discussed, and, together with insight from the other approaches, used to physically interpret gravitational radiation. The precise conditions under which a similarity between gravity and electromagnetism occurs are discussed, and we conclude by summarizing the main outcome of each approach.Comment: 60 pages, 2 figures. Improved version (compared to v2) with some re-write, notation improvements and a new figure that match the published version; expanded compared to the published version to include Secs. 2.3 and