187 research outputs found

    Mutual Dimension

    Get PDF
    We define the lower and upper mutual dimensions mdim(x:y)mdim(x:y) and Mdim(x:y)Mdim(x:y) between any two points xx and yy in Euclidean space. Intuitively these are the lower and upper densities of the algorithmic information shared by xx and yy. We show that these quantities satisfy the main desiderata for a satisfactory measure of mutual algorithmic information. Our main theorem, the data processing inequality for mutual dimension, says that, if f:Rm→Rnf:\mathbb{R}^m \rightarrow \mathbb{R}^n is computable and Lipschitz, then the inequalities mdim(f(x):y)≤mdim(x:y)mdim(f(x):y) \leq mdim(x:y) and Mdim(f(x):y)≤Mdim(x:y)Mdim(f(x):y) \leq Mdim(x:y) hold for all x∈Rmx \in \mathbb{R}^m and y∈Rty \in \mathbb{R}^t. We use this inequality and related inequalities that we prove in like fashion to establish conditions under which various classes of computable functions on Euclidean space preserve or otherwise transform mutual dimensions between points.Comment: This article is 29 pages and has been submitted to ACM Transactions on Computation Theory. A preliminary version of part of this material was reported at the 2013 Symposium on Theoretical Aspects of Computer Science in Kiel, German

    Observations of HONO by laser-induced fluorescence at the South Pole during ANTCI 2003

    Get PDF
    Observations of nitrous acid (HONO) by laser-induced fluorescence (LIF) at the South Pole taken during the Antarctic Troposphere Chemistry Investigation (ANTCI), which took place over the time period of Nov. 15, 2003 to Jan. 4, 2004, are presented here. The median observed mixing ratio of HONO 10 m above the snow was 5.8 pptv (mean value 6.3 pptv) with a maximum of 18.2 pptv on Nov 30th, Dec 1st, 3rd, 15th, 17th, 21st, 22nd, 25th, 27th and 28th. The measurement uncertainty is ±35%. The LIF HONO observations are compared to concurrent HONO observations performed by mist chamber/ion chromatography (MC/IC). The HONO levels reported by MC/IC are about 7.2 ± 2.3 times higher than those reported by LIF. Citation: Liao, W., A. T. Case, J. Mastromarino, D. Tan, and J. E. Dibb (2006), Observations of HONO by laser-induced fluorescence at the South Pole during ANTCI 2003, Geophys. Res. Lett., 33, L09810, doi:10.1029/2005GL025470

    Ariel - Volume 2 Number 3

    Get PDF
    Editors Delvyn C. Case, Jr. Paul M. Fernhoff News Editors Richard Bonanno Daniel B. Gould Robin A. Edwards Lay-Out Editor Carol Dolinskas Sports Editor James J. Nocon Contributing Editors Michael J. Blecker Lin Sey Edwards Jack Guralnik W. Cherry Light Features Editor Steven A. Ager Donald A. Bergman Stephen P. Flynn Business Manager Nick Greg

    Measuring single cell divisions in human tissues from multi-region sequencing data

    Get PDF
    Both normal tissue development and cancer growth are driven by a branching process of cell division and mutation accumulation that leads to intra-tissue genetic heterogeneity. However, quantifying somatic evolution in humans remains challenging. Here, we show that multi-sample genomic data from a single time point of normal and cancer tissues contains information on single-cell divisions. We present a new theoretical framework that, applied to whole-genome sequencing data of healthy tissue and cancer, allows inferring the mutation rate and the cell survival/death rate per division. On average, we found that cells accumulate 1.14 mutations per cell division in healthy haematopoiesis and 1.37 mutations per division in brain development. In both tissues, cell survival was maximal during early development. Analysis of 131 biopsies from 16 tumours showed 4 to 100 times increased mutation rates compared to healthy development and substantial inter-patient variation of cell survival/death rates

    Hepatic steatosis risk is partly driven by increased de novo lipogenesis following carbohydrate consumption.

    Get PDF
    BACKGROUND: Diet is a major contributor to metabolic disease risk, but there is controversy as to whether increased incidences of diseases such as non-alcoholic fatty liver disease arise from consumption of saturated fats or free sugars. Here, we investigate whether a sub-set of triacylglycerols (TAGs) were associated with hepatic steatosis and whether they arise from de novo lipogenesis (DNL) from the consumption of carbohydrates. RESULTS: We conduct direct infusion mass spectrometry of lipids in plasma to study the association between specific TAGs and hepatic steatosis assessed by ultrasound and fatty liver index in volunteers from the UK-based Fenland Study and evaluate clustering of TAGs in the National Survey of Health and Development UK cohort. We find that TAGs containing saturated and monounsaturated fatty acids with 16-18 carbons are specifically associated with hepatic steatosis. These TAGs are additionally associated with higher consumption of carbohydrate and saturated fat, hepatic steatosis, and variations in the gene for protein phosphatase 1, regulatory subunit 3b (PPP1R3B), which in part regulates glycogen synthesis. DNL is measured in hyperphagic ob/ob mice, mice on a western diet (high in fat and free sugar) and in healthy humans using stable isotope techniques following high carbohydrate meals, demonstrating the rate of DNL correlates with increased synthesis of this cluster of TAGs. Furthermore, these TAGs are increased in plasma from patients with biopsy-confirmed steatosis. CONCLUSION: A subset of TAGs is associated with hepatic steatosis, even when correcting for common confounding factors. We suggest that hepatic steatosis risk in western populations is in part driven by increased DNL following carbohydrate rich meals in addition to the consumption of saturated fat

    Unravelling the Wider Benefits of Social Pensions: Secondary Beneficiaries of the Older Persons Cash Transfer Program in the Slums of Nairobi

    Get PDF
    A growing number of low and middle income countries have introduced social pension programs for older people. Research has highlighted that the impact of such programs can extend beyond the primary recipient when funds are shared. It less clear the extent to which such redistribution persists in the lowest resource settings. Using data from a survey conducted in 2016, this paper examines how recipients of the Kenyan Older Persons Cash Transfer Program (OPCTP) living in two slum communities in Nairobi reallocate their social pension by examining the characteristics of older people who are more likely to share their cash and identifying secondary beneficiaries. Findings suggest that 40% of beneficiaries re-allocate some or all of the cash received. The majority of secondary beneficiaries are either grandchildren or children of the primary beneficiary. Overall, a higher proportion of the total cash is shared with secondary beneficiaries living in rural Kenya, as compared to those living in the same household. This highlights the role played by older people, even the most vulnerable, in providing support to wider kin networks; reinforcing the argument that investing in social pensions has much broader potential societal impact than the intended aims of reducing recipient household poverty. By enhancing economic opportunities and investments in human capital more broadly, societies that invest in social pension programs may improve the overall living conditions and experiences of ageing in their countries at a critical moment of global population ageing
    • …
    corecore