Can Gravitation Have a Finite Range?

No acceptable tensor gravitational theory with arbitrarily long but finite range exists. In linear approximation, the infinite-range limit is a scalar-tensor mixture implying an effective matter-matter coupling different from the strictly infinite-range prediction and contradicted by experiment. Compensation of the scalar requires the admixture of a ghost scalar coupling. In the massive version of the full Einstein theory, (a) there are necessarily six rather than the five tensor degrees of freedom, (b) the energy has no lower bound, (c) the infinite-range limit seems not to exist at all, and (d) lowest-order forces are the same as in the massive linearized theory

Electromagnetic Mass Shifts, Equal-Time Commutators, and Jost-Lehmann Representation

Electromagnetic mass shifts, equal-time commutators (ETC), and their relation are analyzed, using the Jost-Lehmann representation for the forward Compton amplitude. The divergences in δ m are determined by Lorentz scalars associated with the ETC (when these exist). These results are illustrated by models with currents bilinear and linear in canonical fields. Existence of the ETC implies that the Jost-Lehmann representation is unsubtracted

Canonical analysis of the fermion sector in higher-derivative supergravity

The degree of freedom and helicity count of the fermionic sector in generic superconformal plus supergravity models is exhibited by explicit elimination of all constraints in the 3+1 decomposition of the action, which is given entirely in terms of gauge-invariant variables. In the purely superconformal, massless, case, the third-derivative action describes three helicity-3/2 excitations and one of helicity ½. When mass is introduced by adding a Rarita-Schwinger term, a new helicity-½ excitation appears, and the total spectrum now consists of two massive spin-3/2 modes plus a massless one. In both cases, the excitations unavoidably emerge in sets with both signs of the Hilbert-space metric; some implications of this ghost behavior are discussed

Stress‐Tensor Commutators and Schwinger Terms

We investigate, in local field theory, general properties of commutators involving Poincaré generators or stress‐tensor components, particularly those of local commutators among the latter. The spectral representation of the vacuum stress commutator is given, and shown to require the existence of singular "Schwinger terms'' at equal times, similar to those present in current commutators. These terms are analyzed and related to the metric dependence of the stress tensor in the presence of a prescribed of a prescribed gravitational field and some general results concerning this dependence presented. The resolution of the Schwinger paradox for the T^(μν) commutators is discussed together with some of its implications, such as "nonclassical'' metric dependence of T^(μν). A further paradox concerning the vacuum self‐stress—whether the stress tensor or its vacuum‐subtracted value should enter in the commutators—is related to the covariance of the theory, and partially resolved within this framework

The implications of autoantibodies to a single islet antigen in relatives with normal glucose tolerance:development of other autoantibodies and progression to type 1 diabetes

AIMS/HYPOTHESIS: Autoantibodies directed at single islet autoantigens are associated with lower overall risk of type 1 diabetes than multiple autoantibodies, but individuals with one autoantibody may progress to higher risk categories. We examined the characteristics of this progression in relatives followed prospectively in the TrialNet Pathway to Prevention. METHODS: The study population comprised 983 relatives who were single autoantibody positive with normal baseline glucose tolerance (median age 16.2 years). Samples were screened for antibodies to GAD, insulinoma-associated antigen 2 (IA-2) and insulin, and all positive samples tested for antibodies to zinc transporter 8 and islet cell antibodies. RESULTS: Antibodies to at least one additional islet autoantigen appeared in 118 of 983 relatives (overall 5 year risk 22%, 95% CI [17.9, 26.1]). At baseline, antibodies to GAD alone (68%) were more frequent than antibodies to insulin (26%) or IA-2 (6%), but all were associated with a similar risk of developing additional autoantibodies. Risk was associated with younger age (p = 0.002) and HLA class II genotype, but was similar in high and intermediate genetic risk groups (p = 0.65). Relatives who became multiple autoantibody positive during the follow-up had increased risk of developing diabetes comparable with the risk in relatives with multiple autoantibodies at study entry. CONCLUSIONS/INTERPRETATION: Progression of islet autoimmunity in single autoantibody positive relatives in late childhood/adult life is associated with a predominance of autoantibodies to GAD and a distinct HLA risk profile. This heterogeneity in type 1 diabetes autoimmunity has potentially important implications for disease prevention. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00125-015-3830-2) contains peer-reviewed but unedited supplementary material, which is available to authorised users

The Heavy Quark Self-Energy in Nonrelativistic Lattice QCD

The heavy quark self-energy in nonrelativistic lattice QCD is calculated to $O(\alpha_s)$ in perturbation theory. An action which includes all spin-independent relativistic corrections to order $v^2$, where $v$ is the typical heavy quark velocity, and all spin-dependent corrections to order $v^4$ is used. The standard Wilson action and an improved multi-plaquette action are used for the gluons. Results for the mass renormalization, wavefunction renormalization, and energy shift are given; tadpole contributions are found to be large. A tadpole improvement scheme in which all link variables are rescaled by a mean-field factor is also studied. The effectiveness of this scheme in offsetting the large tadpole contributions to the heavy quark renormalization parameters is demonstrated.Comment: 28 pages, SLAC-PUB-598

Ophthalmic signs in Ugandan adults with HIV-associated cryptococcal meningitis: A nested analysis of the ASTRO-CM cohort.

Cryptococcal meningitis is a leading cause of morbidity and mortality among HIV-infected persons, accounting for 15% of AIDS-related deaths. Visual disturbance is commonly reported, and a wide range of ophthalmic signs may be present on examination. There is limited published literature to date describing the range and incidence of ophthalmic signs in HIV-associated cryptococcal meningitis. Nested within the Adjunctive Sertraline for the Treatment of HIV-Associated Cryptococcal Meningitis (ASTRO-CM) trial (ClinicalTrials.gov number: NCT01802385), we conducted an observational study of 696 Ugandan adults with HIV-associated cryptococcal meningitis. Patients were screened for visual disturbance and external ophthalmic signs at initial presentation and at follow-up appointments over 18 weeks. Assessment comprised simple clinical history and basic examination and required no specialist equipment. More than a quarter of our cohort demonstrated ocular signs or symptoms, which were observed throughout the study period.  A broad range of ocular signs were demonstrated: these included neurological signs (10.9%), localized ocular pathology (4.5%), and evidence of concurrent systemic disease (12.9%). The range of signs observed demonstrates the complexities of case management in patients with advanced HIV and cryptococcosis and also the importance of basic ocular examination in low resource settings. There remains an urgent need for studies conducting comprehensive ocular examination in patients with HIV-associated cryptococcal meningitis; these studies should include formal assessment of visual acuity, slit lamp examination and dilated indirect ophthalmoscopy. Prospective studies should investigate whether there is a correlation between reported visual disturbance and objective signs, in order to further clarify the underlying mechanisms and to guide effective diagnosis, follow-up and management

Cryptococcal Meningitis and Tuberculous Meningitis Co-infection in HIV-Infected Ugandan Adults.

We report 5 HIV-infected Ugandan adults with cryptococcal and tuberculous (TB) meningitis co-infection. All unmasked meningitis occurred within 5 weeks of starting HIV therapy. Xpert MTB/RIF Ultra facilitated prompt diagnosis; however, 60% in-hospital mortality occurred. TB meningitis coinfection prevalence was 0.8% (5/586) among cryptococcal meningitis, 2 during second cryptococcal episodes

Path Integrals, Density Matrices, and Information Flow with Closed Timelike Curves

Two formulations of quantum mechanics, inequivalent in the presence of closed timelike curves, are studied in the context of a soluable system. It illustrates how quantum field nonlinearities lead to a breakdown of unitarity, causality, and superposition using a path integral. Deutsch's density matrix approach is causal but typically destroys coherence. For each of these formulations I demonstrate that there are yet further alternatives in prescribing the handling of information flow (inequivalent to previous analyses) that have implications for any system in which unitarity or coherence are not preserved.Comment: 25 pages, phyzzx, CALT-68-188