1,720,970 research outputs found
Mosh: An Interactive Remote Shell for Mobile Clients
Get PDFMosh (mobile shell) is a remote terminal application that supports intermittent connectivity, allows roaming, and speculatively and safely echoes user keystrokes for better interactive response over high-latency paths. Mosh is built on the State Synchronization Protocol (SSP), a new UDP-based protocol that securely synchronizes client and server state, even across changes of the client’s IP address. Mosh uses SSP to synchronize a character-cell terminal emulator, maintaining terminal state at both client and server to predictively echo keystrokes. Our evaluation analyzed keystroke traces from six different users covering a period of 40 hours of real-world usage. Mosh was able to immediately display the effects of 70% of the user keystrokes. Over a commercial EV-DO (3G) network, median keystroke response latency with Mosh was less than 5 ms, compared with 503 ms for SSH. Mosh is free software, available from http://mosh.mit.edu. It was downloaded more than 15,000 times in the first week of its release.National Science Foundation (U.S.) (NSF grant 1040072)National Science Foundation (U.S.) (NSF grant 0721702
Tcp ex machina: Computer-generated congestion control
No full textThis paper describes a new approach to end-to-end congestion con-trol on a multi-user network. Rather than manually formulate each endpoint’s reaction to congestion signals, as in traditional protocols, we developed a program called Remy that generates congestion-control algorithms to run at the endpoints. In this approach, the protocol designer specifies their prior knowledge or assumptions about the network and an objective that the algorithm will try to achieve, e.g., high throughput and low queueing delay. Remy then produces a distributed algorithm—the control rules for the independent endpoints—that tries to achieve this objective. In simulations with ns-2, Remy-generated algorithms outper-formed human-designed end-to-end techniques, including TCP Cu-bic, Compound, and Vegas. In many cases, Remy’s algorithms also outperformed methods that require intrusive in-network changes, including XCP and Cubic-over-sfqCoDel (stochastic fair queueing with CoDel for active queue management). Remy can generate algorithms both for networks where some parameters are known tightly a priori, e.g. datacenters, and for net-works where prior knowledge is less precise, such as cellular net-works. We characterize the sensitivity of the resulting performance to the specificity of the prior knowledge, and the consequences when real-world conditions contradict the assumptions supplied at design-time
End-to-End Transmission Control by Modeling Uncertainty about the Network State
No full textThis paper argues that the bar for the incorporation of a
new subnetwork or link technology in the current Internet is
much more than the ability to send minimum-sized IP packets:
success requires that TCP perform well over any subnetwork.
This requirement imposes a number of additional constraints,
some hard to meet because TCP’s network model is
limited and its overall objective challenging to specify precisely.
As a result, network evolution has been hampered
and the potential of new subnetwork technologies has not
been realized in practice. The poor end-to-end performance
of many important subnetworks, such as wide-area cellular
networks that zealously hide non-congestive losses and introduce
enormous delays as a result, or home broadband networks
that suffer from the notorious “bufferbloat” problem,
are symptoms of this more general issue.
We propose an alternate architecture for end-to-end resource
management and transmission control, in which the
endpoints work directly to achieve a specified goal. Each
endpoint treats the network as an nondeterministic automaton
whose parameters and topology are uncertain. The endpoint
maintains a probability distribution on what it thinks
the network’s configuration may be. At each moment, the
endpoint acts to maximize the expected value of a utility
function that is given explicitly. We present preliminary
simulation results arguing that the approach is tractable and
holds promise.National Science Foundation (U.S.) (CNS-1040072
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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