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10,484 results on '"DAVIES, PETER"'

14. Optimal (degree+1)-Coloring in Congested Clique

Author

Coy, Sam, Czumaj, Artur, Davies, Peter, and Mishra, Gopinath

Subjects
Computer Science - Data Structures and Algorithms
Abstract

We consider the distributed complexity of the (degree+1)-list coloring problem, in which each node $u$ of degree $d(u)$ is assigned a palette of $d(u)+1$ colors, and the goal is to find a proper coloring using these color palettes. The (degree+1)-list coloring problem is a natural generalization of the classical $(\Delta+1)$-coloring and $(\Delta+1)$-list coloring problems, both being benchmark problems extensively studied in distributed and parallel computing. In this paper we settle the complexity of the (degree+1)-list coloring problem in the Congested Clique model by showing that it can be solved deterministically in a constant number of rounds., Comment: 27 pages. Appeared at ICALP 2023

Published
2023

17. Greater male variability in daily energy expenditure develops through puberty.

Author

Haisma, Hinke, Hambly, Catherine, Hoffman, Daniel, Hoos, Marije, Hu, Sumei, Joonas, Noorjehan, Joosen, Annemiek, Katzmarzyk, Peter, Kempen, Kitty, Kimura, Misaka, Kraus, William, Kriengsinyos, Wantanee, Kuriyan, Rebecca, Kushner, Robert, Lambert, Estelle, Lanerolle, Pulani, Larsson, Christel, Lessan, Nader, Löf, Marie, Martin, Corby, Matsiko, Eric, Meijer, Gerwin, Morehen, James, Morton, James, Must, Aviva, Neuheuser, Marian, Nicklas, Theresa, Ojiambo, Robert, Pietilainen, Kirsi, Pitsiladis, Yannis, Plange-Rhule, Jacob, Plasqui, Guy, Prentice, Ross, Rabinovich, Roberto, Racette, Susan, Raichen, David, Ravussin, Eric, Redman, Leanne, Reilly, John, Reynolds, Rebecca, Roberts, Susan, Rood, Jennifer, Samaranayake, Dulani, Sardinha, Luís, Scuitt, Albertine, Silva, Analiza, Sinha, Srishti, Sjödin, Anders, Stice, Eric, Stunkard, Albert, Urlacher, Samuel, Valencia, Mauro, Valenti, Giulio, van Etten, Ludo, Van Mil, Edgar, Verbunt, Jeanine, Wells, Jonathan, Wilson, George, Wood, Brian, Yoshida, Tsukasa, Zhang, Xueying, Murphy-Alford, Alexia, Loechl, Cornelia, Luke, Amy, Pontzer, Herman, Sagayama, Hiroyuki, Westerterp, Klaas, Wong, William, Yamada, Yosuke, Speakman, John, Halsey, Lewis, Careau, Vincent, Ainslie, Philip, Alemán-Mateo, Heliodoro, Andersen, Lene, Anderson, Liam, Arab, Leonore, Baddou, Issad, Bandini, Linda, Bedu-Addo, Kweku, Blaak, Ellen, Blanc, Stephane, Bonomi, Alberto, Bouten, Carlijn, Bovet, Pascal, Brage, Soren, Buchowski, Maciej, Butte, Nancy, Camps, Stephan, Casper, Regian, Close, Graeme, Colbert, Lisa, Cooper, Jamie, Cooper, Richard, Dabare, Prasangi, Das, Sai, Davies, Peter, Deb, Sanjoy, and Nyström, Christine

Subjects
age, height, inter-individual variation, morphometry, weight, Adolescent, Young Adult, Female, Humans, Male, Adult, Puberty, Sexual Behavior, Reproduction, Energy Metabolism, Phenotype
Abstract

There is considerably greater variation in metabolic rates between men than between women, in terms of basal, activity and total (daily) energy expenditure (EE). One possible explanation is that EE is associated with male sexual characteristics (which are known to vary more than other traits) such as musculature and athletic capacity. Such traits might be predicted to be most prominent during periods of adolescence and young adulthood, when sexual behaviour develops and peaks. We tested this hypothesis on a large dataset by comparing the amount of male variation and female variation in total EE, activity EE and basal EE, at different life stages, along with several morphological traits: height, fat free mass and fat mass. Total EE, and to some degree also activity EE, exhibit considerable greater male variation (GMV) in young adults, and then a decreasing GMV in progressively older individuals. Arguably, basal EE, and also morphometrics, do not exhibit this pattern. These findings suggest that single male sexual characteristics may not exhibit peak GMV in young adulthood, however total and perhaps also activity EE, associated with many morphological and physiological traits combined, do exhibit GMV most prominently during the reproductive life stages.

Published
2023

19. Uniting General-Graph and Geometric-Based Radio Networks via Independence Number Parametrization

Author

Davies, Peter

Subjects
Computer Science - Distributed, Parallel, and Cluster Computing
Abstract

In the study of radio networks, the tasks of broadcasting (propagating a message throughout the network) and leader election (having the network agree on a node to designate `leader') are two of the most fundamental global problems, and have a long history of work devoted to them. This work has two divergent strands: some works focus on exploiting the geometric properties of wireless networks based in physical space, while others consider general graphs. Algorithmic results in each of these avenues have often used quite different techniques, and produced bounds using incomparable parametrizations. In this work, we unite the study of general-graph and geometric-based radio networks, by adapting the broadcast and leader election algorithm of Czumaj and Davies (JACM '21) to achieve a running-time parametrized by the independence number of the network (i.e., the size of the maximum independent set). This parametrization preserves the running time on general graphs, matching the best known, but also improves running times to near-optimality across a wide range of geometric-based graph classes. As part of this algorithm, we also provide the first algorithm for computing a maximal independent set in general-graph radio networks. This algorithm runs in $O(\log^3 n)$ time-steps, only a $\log n$ factor away from the $\Omega(\log^2 n)$ lower bound., Comment: To appear at PODC 2023

Published
2023

20. Optimal Message-Passing with Noisy Beeps

Author

Davies, Peter

Subjects
Computer Science - Distributed, Parallel, and Cluster Computing
Abstract

Beeping models are models for networks of weak devices, such as sensor networks or biological networks. In these networks, nodes are allowed to communicate only via emitting beeps: unary pulses of energy. Listening nodes only the capability of {\it carrier sensing}: they can only distinguish between the presence or absence of a beep, but receive no other information. The noisy beeping model further assumes listening nodes may be disrupted by random noise. Despite this extremely restrictive communication model, it transpires that complex distributed tasks can still be performed by such networks. In this paper we provide an optimal procedure for simulating general message passing in the beeping and noisy beeping models. We show that a round of \textsf{Broadcast CONGEST} can be simulated in $O(\Delta\log n)$ round of the noisy (or noiseless) beeping model, and a round of \textsf{CONGEST} can be simulated in $O(\Delta^2\log n)$ rounds (where $\Delta$ is the maximum degree of the network). We also prove lower bounds demonstrating that no simulation can use asymptotically fewer rounds. This allows a host of graph algorithms to be efficiently implemented in beeping models. As an example, we present an $O(\log n)$-round \textsf{Broadcast CONGEST} algorithm for maximal matching, which, when simulated using our method, immediately implies a near-optimal $O(\Delta \log^2 n)$-round maximal matching algorithm in the noisy beeping model., Comment: To appear at PODC 2023

Published
2023

21. Parallel Derandomization for Coloring

Author

Coy, Sam, Czumaj, Artur, Davies, Peter, and Mishra, Gopinath

Subjects
Computer Science - Data Structures and Algorithms
Abstract

Graph coloring problems are among the most fundamental problems in parallel and distributed computing, and have been studied extensively in both settings. In this context, designing efficient deterministic algorithms for these problems has been found particularly challenging. In this work we consider this challenge, and design a novel framework for derandomizing algorithms for coloring-type problems in the Massively Parallel Computation (MPC) model with sublinear space. We give an application of this framework by showing that a recent $(degree+1)$-list coloring algorithm by Halldorsson et al. (STOC'22) in the LOCAL model of distributed computation can be translated to the MPC model and efficiently derandomized. Our algorithm runs in $O(\log \log \log n)$ rounds, which matches the complexity of the state of the art algorithm for the $(\Delta + 1)$-coloring problem., Comment: 26 Pages. The paper will appear in IPDPS 2024

Published
2023

43. Total daily energy expenditure has declined over the past three decades due to declining basal expenditure, not reduced activity expenditure.

Author

Speakman, John, de Jong, Jasper, Sinha, Srishti, Westerterp, Klaas, Yamada, Yosuke, Sagayama, Hiroyuki, Ainslie, Philip, Anderson, Liam, Arab, Lenore, Bedu-Addo, Kweku, Blanc, Stephane, Bonomi, Alberto, Bovet, Pascal, Brage, Soren, Buchowski, Maciej, Butte, Nancy, Camps, Stefan, Cooper, Jamie, Cooper, Richard, Das, Sai, Davies, Peter, Dugas, Lara, Ekelund, Ulf, Entringer, Sonja, Forrester, Terrence, Fudge, Barry, Gillingham, Melanie, Ghosh, Santu, Goris, Annelies, Halsey, Lewis, Hambly, Catherine, Haisma, Hinke, Hoffman, Daniel, Hu, Sumei, Joosen, Annemiek, Kaplan, Jennifer, Katzmarzyk, Peter, Kraus, William, Kushner, Robert, Leonard, William, Löf, Marie, Martin, Corby, Matsiko, Eric, Medin, Anine, Meijer, Erwin, Neuhouser, Marian, Nicklas, Theresa, Ojiambo, Robert, Pietiläinen, Kirsi, Plange-Rhule, Jacob, Plasqui, Guy, Prentice, Ross, Racette, Susan, Raichlen, David, Ravussin, Eric, Redman, Leanne, Roberts, Susan, Rudolph, Michael, Sardinha, Luis, Schuit, Albertine, Silva, Analiza, Stice, Eric, Urlacher, Samuel, Valenti, Giulio, Van Etten, Ludo, Van Mil, Edgar, Wood, Brian, Yanovski, Jack, Yoshida, Tsukasa, Zhang, Xueying, Murphy-Alford, Alexia, Loechl, Cornelia, Kurpad, Anura, Luke, Amy, Pontzer, Herman, Rodeheffer, Matthew, Rood, Jennifer, Schoeller, Dale, Wong, William, and Gurven, Michael

Subjects
Male, Female, United States, Humans, Health Expenditures, Exercise, Basal Metabolism, Energy Metabolism, Obesity
Abstract

Obesity is caused by a prolonged positive energy balance1,2. Whether reduced energy expenditure stemming from reduced activity levels contributes is debated3,4. Here we show that in both sexes, total energy expenditure (TEE) adjusted for body composition and age declined since the late 1980s, while adjusted activity energy expenditure increased over time. We use the International Atomic Energy Agency Doubly Labelled Water database on energy expenditure of adults in the United States and Europe (n = 4,799) to explore patterns in total (TEE: n = 4,799), basal (BEE: n = 1,432) and physical activity energy expenditure (n = 1,432) over time. In males, adjusted BEE decreased significantly, but in females this did not reach significance. A larger dataset of basal metabolic rate (equivalent to BEE) measurements of 9,912 adults across 163 studies spanning 100 years replicates the decline in BEE in both sexes. We conclude that increasing obesity in the United States/Europe has probably not been fuelled by reduced physical activity leading to lowered TEE. We identify here a decline in adjusted BEE as a previously unrecognized factor.

Published
2023

48. Index

Author

Davies, Peter J.

Published
2006

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