11 research outputs found
Quintessential Quartic Quasi-topological Quartet
We construct the quartic version of generalized quasi-topological gravity,
which was recently constructed to cubic order in arXiv: 1703.01631. This class
of theories includes Lovelock gravity and a known form of quartic
quasi-topological gravity as special cases and possess a number of remarkable
properties: (i) In vacuum, or in the presence of suitable matter, there is a
single independent field equation which is a total derivative. (ii) At the
linearized level, the equations of motion on a maximally symmetric background
are second order, coinciding with the linearized Einstein equations up to a
redefinition of Newton's constant. Therefore, these theories propagate only the
massless, transverse graviton on a maximally symmetric background. (iii) While
the Lovelock and quasi-topological terms are trivial in four dimensions, there
exist four new generalized quasi-topological terms (the quartet) that are
nontrivial, leading to interesting higher curvature theories in
dimensions that appear well suited for holographic study. We construct four
dimensional black hole solutions to the theory and study their properties. A
study of black brane solutions in arbitrary dimensions reveals that these
solutions are modified from the `universal' properties these solutions have.
This result may lead to interesting consequences for the dual CFTs.Comment: 46 pages, 1 figure. Discussion of black branes added to section
On RR couplings on D-branes at order
Recently, it has been found that there are couplings of the RR field strength
and the B-field strength on the world volume of D-branes at
order . These couplings which have both world-volume and
transverse indices, are invariant under the linear T-duality transformations.
Consistency with the nonlinear T-duality indicates that the RR field strength
in these couplings should be replaced by where . This replacement, however, reproduces some
non-gauge invariant terms. On the other hand, the nonlinear terms are invariant
under the linear T-duality transformations at the level of two B-fields. This
allows one to remove some of the nonlinear terms in . We fix
this by comparing the nonlinear couplings with the S-matrix element of one RR
and two NSNS vertex operators. Our results indicate that in the expansion of
one should keep only the B-field gauge invariant terms, e.g.
where both indices of B-field lie along the brane.
Moreover, in this case one should replace with to have the
-field gauge invariance.Comment: 23 pages, Latex file, 1 figure; v2:typos corrected, to appear in JHE
Economic burden of type 2 diabetes in Iran: A costâofâillness study
Abstract Background and Aims Type 2 diabetes mellitus (T2DM) is a prevalent public health problem worldwide, and the economic burden of the disease poses one of the main challenges for health systems in lowâ and middleâincome countries. This study aimed to estimate the economic burden of T2DM in Iran, in 2018. Methods This was a costâofâillness study. Three hundred and seventyâfive patients with T2DM who were referred to Imam Reza and Sina's educational and therapeutic centers and Asad Abadi clinic in Tabriz, Iran, in 2018 were included. A researcherâconstructed checklist was used for data collection. Data were analyzed using EXCEL and SPSS software version 22. Results Total economic burden of diabetes was estimated at 152,443,862,480.3 (purchasing power parity [PPP], Current International ). The mean total direct and indirect costs were 11,278.68 (PPP) (62.35% of mean total cost) and 6808.88 (PPP, Current International ) (59.81% of mean total cost) and 459.24 (PPP, Current International $) (2.53% of mean total cost) per patient, respectively. Besides, the mean direct medical cost was 6.18 times the total per capita expenditure on health, and the total direct medical cost was 8.9% times the total expenditure on health. Conclusion Diabetes imposes a substantial economic burden on patients, health systems, and the whole economy. Besides, since the cost of the disease in patients treated with insulin and those with diabetes complications is significantly higher, the reinforcement of selfâcare measures and focusing on modifying lifestyle (dietary modification and physical activity) in patients with T2DM can significantly reduce the costs of the disease