258 research outputs found
A methodology for full-system power modeling in heterogeneous data centers
The need for energy-awareness in current data centers has encouraged the use of power modeling to estimate their power consumption. However, existing models present noticeable limitations, which make them application-dependent, platform-dependent, inaccurate, or computationally complex. In this paper, we propose a platform-and application-agnostic methodology for full-system power modeling in heterogeneous data centers that overcomes those limitations. It derives a single model per platform, which works with high accuracy for heterogeneous applications with different patterns of resource usage and energy consumption, by systematically selecting a minimum set of resource usage indicators and extracting complex relations among them that capture the impact on energy consumption of all the resources in the system. We demonstrate our methodology by generating power models for heterogeneous platforms with very different power consumption profiles. Our validation experiments with real Cloud applications show that such models provide high accuracy (around 5% of average estimation error).This work is supported by the Spanish Ministry of Economy and Competitiveness under contract TIN2015-65316-P, by the Gener-
alitat de Catalunya under contract 2014-SGR-1051, and by the European Commission under FP7-SMARTCITIES-2013 contract 608679 (RenewIT) and FP7-ICT-2013-10 contracts 610874 (AS- CETiC) and 610456 (EuroServer).Peer ReviewedPostprint (author's final draft
A reply to “Historical construction costs of global nuclear power reactors”
Lovering et al. (2016) present data on the overnight costs of more than half of nuclear reactors built worldwide since the beginning of the nuclear age. The authors claim that this consolidated data set offers more accurate insights than previous country-level assessments. Unfortunately, the authors make analytical choices that mask nuclear power's real construction costs, cherry pick data, and include misleading data on early experimental and demonstration reactors. For those reasons, serious students of such issues should look elsewhere for guidance about understanding the true costs of nuclear power
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Comparative analysis of monetary estimates of external environmental costs associated with combustion of fossil fuels
Public utility commissions in a number of states have begun to explicitly treat costs of environmental externalities in the resource planning and acquisition process (Cohen et al. 1990). This paper compares ten different estimates and regulatory determinations of external environmental costs associated with fossil fuel combustion, using consistent assumptions about combustion efficiency, emissions factors, and resource costs. This consistent comparison is useful because it makes explicit the effects of various assumptions. This paper uses the results of the comparison to illustrate pitfalls in calculation of external environmental costs, and to derive lessons for design of policies to incorporate these externalities into resource planning. 38 refs., 2 figs., 10 tabs
Pilin expression and processing in pilus mutants of Neisseria gonorrhoeae : critical role of Gly -1 in assembly
Spontaneous mutants of Neisseria gonorrheae failing to express pili or having diminished levels of piliation were studied with regard to pilin expression. All mutants displayed altered pilin processing detectable as the release of soluble, truncated pilin molecules (S-pilin). Of particular interest was the finding, in one mutant, that substitution of serine for glycine at position -1 of propilin, a highly conserved residue among N -metPhe and related pilins, abolished pilus expression but not S-pilin release. The degree of S-pilin processing and the levels of membrane-associated pilin varied among the different classes of mutants, suggesting that each was blocked at a distinct step of pilus biogenesis. The data support a model in which increased S-pilin processing is a result of a decreased rate of pilus polymerization.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74951/1/j.1365-2958.1991.tb02108.x.pd
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
Single amino acid substitutions in the N-terminus of Vibrio cholerae TcpA affect colonization, autoagglutination, and serum resistance
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74620/1/j.1365-2958.1995.mmi_17061133.x.pd
Infection of human mucosal tissue by Pseudomonas aeruginosa requires sequential and mutually dependent virulence factors and a novel pilus-associated adhesin
Tissue damage predisposes humans to life-threatening disseminating infection by the opportunistic pathogen Pseudomonas aeruginosa. Bacterial adherence to host tissue is a critical first step in this infection process. It is well established that P. aeruginosa attachment to host cells involves type IV pili (TFP), which are retractile surface fibers. The molecular details of attachment and the identity of the bacterial adhesin and host receptor remain controversial. Using a mucosal epithelium model system derived from primary human tissue, we show that the pilus-associated protein PilY1 is required for bacterial adherence. We establish that P. aeruginosa preferentially binds to exposed basolateral host cell surfaces, providing a mechanistic explanation for opportunistic infection of damaged tissue. Further, we demonstrate that invasion and fulminant infection of intact host tissue requires the coordinated and mutually dependent action of multiple bacterial factors, including pilus fiber retraction and the host cell intoxication system, termed type III secretion. Our findings offer new and important insights into the complex interactions between a pathogen and its human host and provide compelling evidence that PilY1 serves as the principal P. aeruginosa adhesin for human tissue and that it specifically recognizes a host receptor localized or enriched on basolateral epithelial cell surfaces
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Conservation screening curves to compare efficiency investments topower plants: Applications to commercial sector conservationprograms
This paper describes a simplified methodology to compare supply and demand-side resources. The screening curve approach supplements with load shape information the data contained in a supply curve of conserved energy. In addition, a screening curve contains information on competing supply technologies, such as annualized capital costs, variable costs, and cost per delivered kWh. The information in the screening curve allows policymakers to promptly and conveniently compare the relevant parameters affecting supply and demand-side investment decisions. While many sophisticated computer models have evolved to account for the load shape impacts of energy efficiency investments, this sophistication has, by and large, not trickled down to spreadsheet-level or 'back-of-the-envelope' analyses. Our methodology allows a simple summary of load shape characteristics based on the output of the more complicated models. It offers many advantages, principal of which is clarity in analyzing supply and demand-side investment choices. This paper first describes how supply-side screening curves have been used in the past, and develops the conceptual tools needed to apply integrated supply/demand screening curves in the least-cost utility planning process. It then presents examples of supply-side technologies and commercial sector demand-side management programs, and plots them on representative screening curves
Informal Action—Adjudication—Rule Making: Some Recent Developments in Federal Administrative Law
Direct energy consumption of ICT hardware is only “half the story.” In order to get the “whole story,” energy consumption during the entire life cycle has to be taken into account. This chapter is a first step toward a more comprehensive picture, showing the “grey energy” (i.e., the overall energy requirements) as well as the releases (into air, water, and soil) during the entire life cycle of exemplary ICT hardware devices by applying the life cycle assessment method. The examples calculated show that a focus on direct energy consumption alone fails to take account of relevant parts of the total energy consumption of ICT hardware as well as the relevance of the production phase. As a general tendency, the production phase is more and more important the smaller (and the more energy-efficient) the devices are. When in use, a tablet computer is much more energy-efficient than a desktop computer system with its various components, so its production phase has a much greater relative importance. Accordingly, the impacts due to data transfer when using Internet services are also increasingly relevant the smaller the end-user device is, reaching up to more than 90 % of the overall impact when using a tablet computer.QC 20140825</p
Structural alterations in a type IV pilus subunit protein result in concurrent defects in multicellular behaviour and adherence to host tissue
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72384/1/j.1365-2958.2001.02629.x.pd
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