Toward an Energy Efficient Language and Compiler for (Partially) Reversible Algorithms

We introduce a new programming language for expressing reversibility, Energy-Efficient Language (Eel), geared toward algorithm design and implementation. Eel is the first language to take advantage of a partially reversible computation model, where programs can be composed of both reversible and irreversible operations. In this model, irreversible operations cost energy for every bit of information created or destroyed. To handle programs of varying degrees of reversibility, Eel supports a log stack to automatically trade energy costs for space costs, and introduces many powerful control logic operators including protected conditional, general conditional, protected loops, and general loops. In this paper, we present the design and compiler for the three language levels of Eel along with an interpreter to simulate and annotate incurred energy costs of a program.Comment: 17 pages, 0 additional figures, pre-print to be published in The 8th Conference on Reversible Computing (RC2016

Energy-Efficient Algorithms

We initiate the systematic study of the energy complexity of algorithms (in addition to time and space complexity) based on Landauer's Principle in physics, which gives a lower bound on the amount of energy a system must dissipate if it destroys information. We propose energy-aware variations of three standard models of computation: circuit RAM, word RAM, and transdichotomous RAM. On top of these models, we build familiar high-level primitives such as control logic, memory allocation, and garbage collection with zero energy complexity and only constant-factor overheads in space and time complexity, enabling simple expression of energy-efficient algorithms. We analyze several classic algorithms in our models and develop low-energy variations: comparison sort, insertion sort, counting sort, breadth-first search, Bellman-Ford, Floyd-Warshall, matrix all-pairs shortest paths, AVL trees, binary heaps, and dynamic arrays. We explore the time/space/energy trade-off and develop several general techniques for analyzing algorithms and reducing their energy complexity. These results lay a theoretical foundation for a new field of semi-reversible computing and provide a new framework for the investigation of algorithms.Comment: 40 pages, 8 pdf figures, full version of work published in ITCS 201

Trace Complexity of Chaotic Reversible Cellular Automata

Delvenne, K\r{u}rka and Blondel have defined new notions of computational complexity for arbitrary symbolic systems, and shown examples of effective systems that are computationally universal in this sense. The notion is defined in terms of the trace function of the system, and aims to capture its dynamics. We present a Devaney-chaotic reversible cellular automaton that is universal in their sense, answering a question that they explicitly left open. We also discuss some implications and limitations of the construction.Comment: 12 pages + 1 page appendix, 4 figures. Accepted to Reversible Computation 2014 (proceedings published by Springer

Effects of once-weekly semaglutide on appetite, energy intake, control of eating, food preference and body weight in subjects with obesity.

AIM: To investigate the mechanism of action for body weight loss with semaglutide. MATERIALS AND METHODS: This randomised, double-blind, placebo-controlled, two-period crossover trial investigated the effects of 12 weeks treatment with once-weekly subcutaneous semaglutide, dose-escalated to 1.0 mg, in 30 subjects with obesity. Ad libitum energy intake, ratings of appetite, thirst, nausea and well-being, control of eating, food preference, resting metabolic rate, body weight and body composition were assessed. RESULTS: After a standardised breakfast, semaglutide, compared with placebo, led to a lower ad libitum energy intake during lunch (-1255 kJ; P < 0.0001), and during the subsequent evening meal (P = 0.0401) and snacks (P = 0.0034), resulting in a 24% reduction in total energy intake across all ad libitum meals throughout the day (-3036 kJ; P < 0.0001). Fasting overall appetite suppression scores were improved with semaglutide versus placebo, while nausea ratings were similar. Semaglutide was associated with less hunger and food cravings, better control of eating and a lower preference for high-fat foods. Resting metabolic rate, adjusted for lean body mass, did not differ between treatments. Semaglutide led to a reduction from baseline in mean body weight of 5.0 kg, predominantly from body fat mass. CONCLUSION: After 12 weeks' treatment, ad libitum energy intake was substantially lower with semaglutide versus placebo with a corresponding loss of body weight observed with semaglutide. In addition to reduced energy intake, likely mechanisms for semaglutide-induced weight loss included less appetite and food cravings, better control of eating and lower relative preference for fatty, energy-dense foods

Cost and Capacity of Signaling in the Escherichia coli Protein Reaction Network

In systems biology new ways are required to analyze the large amount of existing data on regulation of cellular processes. Recent work can be roughly classified into either dynamical models of well-described subsystems, or coarse-grained descriptions of the topology of the molecular networks at the scale of the whole organism. In order to bridge these two disparate approaches one needs to develop simplified descriptions of dynamics and topological measures which address the propagation of signals in molecular networks. Here, we consider the directed network of protein regulation in E. coli, characterizing its modularity in terms of its potential to transmit signals. We demonstrate that the simplest measure based on identifying sub-networks of strong components, within which each node could send a signal to every other node, indeed partitions the network into functional modules. We then suggest measures to quantify the cost and spread associated with sending a signal between any particular pair of proteins. Thereby, we address the signalling specificity within and between modules, and show that in the regulation of E.coli there is a systematic reduction of the cost and spread for signals traveling over more than two intermediate reactions.Comment: 21 pages, 6 figure

Measured UV Exposures of Ironman, Sprint and Olympic-Distance Triathlon Competitors

Triathletes present an extreme case of modelled behaviour in outdoor sport that favours enhanced exposure to solar ultraviolet radiation. This research presents personal solar ultraviolet exposures, measured using all-weather polysulphone film dosimeters, to triathletes during the distinct swimming, cycling and running stages of competitive Sprint, Olympic and Ironman events conducted within Australia and New Zealand. Measurements of exposure are made for each triathlon stage using film dosimeters fixed at a single site to the headwear of competing triathletes. Exposures are expressed relative to the local ambient and as absolute calibrated erythemally effective values across a total of eight triathlon courses (two Ironman, one half Ironman, one Olympic-distance, and four Sprint events). Competitor exposure results during training are also presented. Exposures range from between 0.2 to 6.8 SED/h (SED: standard erythema dose) depending upon the time of year, the local time of each event and cloud conditions. Cycle stage exposures can exceed 20 SED and represent the highest exposure fraction of any triathlon (average = 32%). The next highest stage exposure occurred during the swim (average = 28%), followed by the run (average = 26%). During an Ironman, personal competitor exposures exceed 30 SED, making triathlon a sporting discipline with potentially the highest personal ultraviolet exposure risk

Motivating doctors into leadership and management: a cross-sectional survey

Purpose: Calls for doctors to enter management are louder as the benefits of medical leadership become clearer. But supply is not meeting demand. This study asks doctors: what might encourage you to go into leadership, and what do you see as the disincentives? The same was asked about leadership training. First, the paper attempts to understand doctors’ motivation to lead, specifically, to explore the job characteristics that might act as incentives and disincentives. Second, the study points to organisational obstacles that further shrink the medical leadership pipeline. Method: Doctors were surveyed through the Organization of Danish Medical Societies. Our key variables included: 1) willingness to take on a management or leadership position; 2) the incentives to go into leadership or management; 3) disincentives to do so; and 4) incentives for participating in leadership training. Our sample includes 3534 doctors (17% response rate). Findings: Nearly 70% of doctors said that they would consider leadership or management positions. Overwhelmingly, the main incentive reported was to have a positive impact. Doctors are put off by fears of extra administration, longer hours, burnout, lack of resources, and by organisational cultures resistant to change. But they are fully aware of their need for leadership training. Practical implications: Health systems should adapt to reflect the motivations of their potential medical leaders, especially the best talent, who may not be the first to apply for management positions. It is also essential they offer leadership training. These findings, that aid succession planning, are especially important as more is known about the influence of medical leaders on organisational outcomes, and at a time of high reported stress, burnout, and staff recruitment and retention challenges

CYP83B1 Is the Oxime-metabolizing Enzyme in the Glucosinolate Pathway in \u3ci\u3eArabidopsis\u3c/i\u3e

CYP83B1 from Arabidopsis thaliana has been identified as the oxime-metabolizing enzyme in the biosynthetic pathway of glucosinolates. Biosynthetically active microsomes isolated from Sinapis alba converted p-hydroxyphenylacetaldoxime and cysteine into S-alkylated p-hydroxyphenylacetothiohydroximate, S-(p-hydroxyphenylacetohydroximoyl)-L-cysteine, the next proposed intermediate in the glucosinolate pathway. The production was shown to be dependent on a cytochrome P450 monooxygenase. We searched the genome of A. thaliana for homologues of CYP71E1 (P450ox), the only known oxime-metabolizing enzyme in the biosynthetic pathway of the evolutionarily related cyanogenic glucosides. By a combined use of bioinformatics, published expression data, and knock-out phenotypes, we identified the cytochrome P450 CYP83B1 as the oxime-metabolizing enzyme in the glucosinolate pathway as evidenced by characterization of the recombinant protein expressed in Escherichia coli. The data are consistent with the hypothesis that the oxime-metabolizing enzyme in the cyanogenic pathway (P450ox) was mutated into a “P450mox” that converted oximes into toxic compounds that the plant detoxified into glucosinolates