Gravity's rainbow: a bridge between LQC and DSR

The doubly special relativity (DSR) theories are investigated in order to take into account an observer-independent length scale in special relativity framework. It is widely believed that any quantum theory of gravity would reduce to a DSR model at the flat limit when purely gravitational and quantum mechanical effects are negligible. Gravity's rainbow is a simple generalization of DSR theories to incorporate gravity. In this paper, we show that the effective Friedmann equations that are suggested by loop quantum cosmology (LQC) can be exactly reobtained in rainbow cosmology setup. The deformed geometry of LQC then completely fixes the modified dispersion relation and results in unique DSR model. In comparison with standard LQC scenario where only the geometry is modified, both of the geometry and matter parts get modifications in our setup. In this respect, we find that the total number of microstates for the universe is finite which suggests the statistical origin for the energy and entropy density bounds. These results explicitly show that the DSR theories are appropriate candidates for the flat limit of loop quantum gravity.Comment: 10 pages, 4 figures, Refs. adde

Depression and quality of life in patients with type 2 diabetes

Background: Frequency of mood disorders in patients with chronic diseases, especially diabetes and its effects on life quality are dramatically increasing. Objectives: This study aimed to investigate the relation between depression and quality of life in patients with diabetes. Patients and Methods: This is a cross sectional survey. Subjects were selected from 330 eligible people referred to the only diabetes clinic in Gorgan City during 6 months, using systematic random sampling. Beak Depression questionnaire and the brief questioner with 26 questions recommended by the World Health Organization (WHOQOL-BREF) were used to measure depression and quality of life, respectively. Data were analyzed through descriptive methods, Chi-square, Independent t test and linear regression model using SPSS16; moreover, P value < 0.05 was considered as significant. Results: In total, 330 patients with diabetes (35.5% male and 64.5% women) were studied. The mean and standard deviation of their age and years involved with diabetes were 50.6 ± 9.0 and 5.4 ± 4.5 years, respectively. Range of age was 25 - 75 years, as well. The prevalence of depression in all patients with diabetes was 58.2% (124 mild, 56 medium, and 12 with severe depression). Hypertension was 13.9% more in diabetic patients with depression (P value < 0.001) and physical activity in 24.7% of the cases was less with a meaningful difference (P value = 0.01). The mean and standard deviation of quality of life in diabetic patients with and without depression was 50.7 ± 14 and 60.5 ± 13.3, respectively that was significant in two groups (P < 0.0001). Conclusions: The prevalence of depression is high in patients with diabetes and has a considerable impact on the consequences of diabetes and quality of life too. © 2015, Iranian Red Crescent Medical Journal