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 $d \geq 4$ 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 O(α′2)O(\alpha'^2)

Recently, it has been found that there are couplings of the RR field strength $F^{(p)}$ and the B-field strength $H$ on the world volume of D$_p$-branes at order ${\cal O}(\alpha'^2)$. 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 $F^{(p)}$ in these couplings should be replaced by ${\cal F}^{(p)}=d{\cal C}^{(p-1)}$ where ${\cal C}=e^{B}C$. 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 ${\cal F}^{(p)}$. 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 ${\cal F}^{(p)}$ one should keep only the B-field gauge invariant terms, e.g. $B\wedge dC^{(p-3)}$ where both indices of B-field lie along the brane. Moreover, in this case one should replace $B$ with $B+2\pi\alpha'f$ to have the $B$-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 cost‐of‐illness 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 low‐ and middle‐income countries. This study aimed to estimate the economic burden of T2DM in Iran, in 2018. Methods This was a cost‐of‐illness study. Three hundred and seventy‐five 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 researcher‐constructed 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 $) (approximately 7.69$). The mean total direct and indirect costs were 11,278.68 (PPP) (62.35% of mean total cost) and 6808.88 (PPP, Current International $) (37.64$) (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 self‐care measures and focusing on modifying lifestyle (dietary modification and physical activity) in patients with T2DM can significantly reduce the costs of the disease