1,092 research outputs found
RMD-QOSM: The NSIS Quality-of-Service Model for Resource Management in Diffserv
This document describes a Next Steps in Signaling (NSIS) Quality-of- Service (QoS) Model for networks that use the Resource Management in Diffserv (RMD) concept. RMD is a technique for adding admission control and preemption function to Differentiated Services (Diffserv) networks. The RMD QoS Model allows devices external to the RMD network to signal reservation requests to Edge nodes in the RMD network. The RMD Ingress Edge nodes classify the incoming flows into traffic classes and signals resource requests for the corresponding traffic class along the data path to the Egress Edge nodes for each flow. Egress nodes reconstitute the original requests and continue forwarding them along the data path towards the final destination. In addition, RMD defines notification functions to indicate overload situations within the domain to the Edge nodes
Jointly they edit: examining the impact of community identification on political interaction in Wikipedia
In their 2005 study, Adamic and Glance coined the memorable phrase "divided
they blog", referring to a trend of cyberbalkanization in the political
blogosphere, with liberal and conservative blogs tending to link to other blogs
with a similar political slant, and not to one another. As political discussion
and activity increasingly moves online, the power of framing political
discourses is shifting from mass media to social media. Continued examination
of political interactions online is critical, and we extend this line of
research by examining the activities of political users within the Wikipedia
community. First, we examined how users in Wikipedia choose to display (or not
to display) their political affiliation. Next, we more closely examined the
patterns of cross-party interaction and community participation among those
users proclaiming a political affiliation. In contrast to previous analyses of
other social media, we did not find strong trends indicating a preference to
interact with members of the same political party within the Wikipedia
community. Our results indicate that users who proclaim their political
affiliation within the community tend to proclaim their identity as a
"Wikipedian" even more loudly. It seems that the shared identity of "being
Wikipedian" may be strong enough to triumph over other potentially divisive
facets of personal identity, such as political affiliation.Comment: 33 pages, 5 figure
Sulfite: Cytochrome \u3cem\u3ec\u3c/em\u3e Oxidoreductase from \u3cem\u3eThiobacillus novellus\u3c/em\u3e
Direct oxidation of sulfite to sulfate occurs in various photo- and chemotrophic sulfur oxidizing microorganisms as the final step in the oxidation of reduced sulfur compounds and is catalyzed by sulfite:cytochrome c oxidoreductase (EC1.8.2.1). Here we show that the enzyme from Thiobacillus novellus is a periplasmically located αβ heterodimer, consisting of a 40.6-kDa subunit containing a molybdenum cofactor and an 8.8-kDa mono-heme cytochrome c 552 subunit (midpoint redox potential, E m8.0 = +280 mV). The organic component of the molybdenum cofactor was identified as molybdopterin contained in a 1:1 ratio to the Mo content of the enzyme. Electron paramagnetic resonance spectroscopy revealed the presence of a sulfite-inducible Mo(V) signal characteristic of sulfite:acceptor oxidoreductases. However, pH-dependent changes in the electron paramagnetic resonance signal were not detected. Kinetic studies showed that the enzyme exhibits a ping-pong mechanism involving two reactive sites. K m values for sulfite and cytochrome c 550 were determined to be 27 and 4 μm, respectively; the enzyme was found to be reversibly inhibited by sulfate and various buffer ions. The sorABgenes, which encode the enzyme, appear to form an operon, which is preceded by a putative extracytoplasmic function-type promoter and contains a hairpin loop termination structure downstream ofsorB. While SorA exhibits significant similarities to known sequences of eukaryotic and bacterial sulfite:acceptor oxidoreductases, SorB does not appear to be closely related to any knownc-type cytochromes
Concepts, Developments and Advanced Applications of the PAX Toolkit
The Physics Analysis eXpert (PAX) is an open source toolkit for high energy
physics analysis. The C++ class collection provided by PAX is deployed in a
number of analyses with complex event topologies at Tevatron and LHC. In this
article, we summarize basic concepts and class structure of the PAX kernel. We
report about the most recent developments of the kernel and introduce two new
PAX accessories. The PaxFactory, that provides a class collection to facilitate
event hypothesis evolution, and VisualPax, a Graphical User Interface for PAX
objects
The Ecology of Acidophilic Microorganisms in the Corroding Concrete Sewer Environment.
Concrete corrosion is one of the most significant problems affecting valuable sewer infrastructure on a global scale. This problem occurs in the aerobic zone of the sewer, where a layer of surface corrosion develops on the exposed concrete and the surface pH is typically lowered from around 11-10 (pristine concrete) to pH 2-4. Acidophilic microorganisms become established as biofilms within the concrete corrosion layer and enhance the loss of concrete mass. Until recently, the acidophilic community was considered to comprise relatively few species of microorganisms, however, the biodiversity of the corrosion community is now recognized as being extensive and varying from different sewer environmental conditions. The diversity of acidophiles in the corrosion communities includes chemolithoautotrophs, chemolithoheterotrophs, and chemoorganoheterotrophs. The activity of these microorganisms is strongly affected by H2S levels in the sewer gas phase, although CO2, organic matter, and iron in the corrosion layer influence this acidic ecosystem. This paper briefly presents the conditions within the sewer that lead to the development of concrete corrosion in that environment. The review focuses on the acidophilic microorganisms detected in sewer corrosion environments, and then summarizes their proposed functions and physiology, especially in relation to the corrosion process. To our knowledge, this is the first review of acidophilic corrosion microbial communities, in which, the ecology and the environmental conditions (when available) are considered. Ecological studies of sewer corrosion are limited, however, where possible, we summarize the important metabolic functions of the different acidophilic species detected in sewer concrete corrosion layers. It is evident that microbial functions in the acidic sewer corrosion environment can be linked to those occurring in the analogous acidic environments of acid mine drainage and bioleaching
Physics Analysis Expert PAX: First Applications
PAX (Physics Analysis Expert) is a novel, C++ based toolkit designed to
assist teams in particle physics data analysis issues. The core of PAX are
event interpretation containers, holding relevant information about and
possible interpretations of a physics event. Providing this new level of
abstraction beyond the results of the detector reconstruction programs, PAX
facilitates the buildup and use of modern analysis factories. Class structure
and user command syntax of PAX are set up to support expert teams as well as
newcomers in preparing for the challenges expected to arise in the data
analysis at future hadron colliders.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 7 pages, LaTeX, 10 eps figures. PSN
THLT00
An experimental investigation of the mechanical properties of a selected group of plastic materials
Dynamic and static testing of selected plastics for determination of mechanical propertie
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