1384762
The Early Word Catches the Weights
The strong correlation between the frequency of words and their naming latency has been well documented. However, as early as 1973, the Age of Acquisition (AoA) of a word was alleged to be the actual variable of interest, but these studies seem to have been ignored in most of the literature. Recently, there has been a resurgence of interest in AoA. While some studies have shown that frequency has no effect when AoA is controlled for, more recent studies have found independent contributions of frequency and AoA. Connectionist models have repeatedly shown strong effects of frequency, but little attention has been paid to whether they can also show AoA effects. Indeed, several researchers have explicitly claimed that they cannot show AoA effects. In this work, we explore these claims using a simple feed forward neural network. We find a significant contribution of AoA to naming latency, as well as conditions under which frequency provides an independent contribution.
7589048
Security considerations when designing a distributed file system using object storage devices
We present the design goals that led us to developing a distributed object-based secure file system, Brave. Brave uses mutually authenticated object storage devices, SCARED, to store file system data. Rather than require a new authentication infrastructure. we show how we use a simple authentication protocol that is bridged into existing security infrastructures, even if there is more than one authentication protocol or domain present. We position our work in the context of some of the current work going on in distributed secure file systems and present our implementation of our file system. We also present some security weaknesses that are shared with other distributed file systems that may not be apparent when designing these systems.
5238518
Evolving video skims into useful multimedia abstractions
This paper reports two studies that measured the effects of different “video skim” techniques on comprehension, navigation, and user satisfaction. Video skims are compact, content-rich abstractions of longer videos, condensations that preserve frame rate while greatly reducing viewing time. Their characteristics depend on the image- and audio-processing techniques used to create them. Results from the initial study helped refine video skims, which were then reassessed in the second experiment. Significant benefits were found for skims built from audio sequences meeting certain criteria.
28781124
From Sequential Processes to Grid Computation
We introduce an extended model for view-centric reasoning, EVCR, that provides more comprehensive and flexible abstractions for representing actual concurrency. The theory of Communicating Sequential Processes (CSP) provides an interleaved semantics for reasoning about concurrency through a sequentialized trace of events recorded by an idealized observer. The theory of View-Centric Reasoning (VCR) extended CSP with notions of parallel events and views, and lazy observation, to represent the true concurrency of simultaneous events and multiple, possibly imperfect observers. But VCR could be more general still, since its events, like those of CSP, are instantaneous. This restriction precludes the possibility of observing events that partially overlap in time. EVCR permits partially overlapping events to be observed and recorded by a lazy observer. The result is a more general model of concurrency; one that is more appropriate for reasoning about network functioning and, in particular, grid computation.
10633849
Assessing differential usage of usenet social accounting meta-data
We describe a usage study of NetscanTech, a system that generates and publishes daily a range of social metrics across three dimensions: newsgroup, author, and thread, for a set of approximately 15,000 technical newsgroups in Usenet. We bring together three interlinked datasets: survey data, usage log data and social accounting data from Usenet participation, to triangulate the relationship between various user roles and differential usage of social metrics in NetscanTech. We found our most frequent users focused on information related to individual authors far more than any other information provided. In contrast, users that visited less frequently focused more on information related to newsgroups and viewing newsgroup metrics. Our results suggest features that designers and developers of online communities may wish to include in their interfaces to support the cultivation of different community roles.
45488813
Parallel application performance on shared high performance reconfigurable computing resources
The use of a network of shared, heterogeneous workstations each harboring a reconfigurable computing (RC) system offers high performance users an inexpensive platform for a wide range of computationally demanding problems. However, effectively using the full potential of these systems can be challenging without the knowledge of the system's performance characteristics. While some performance models exist for shared, heterogeneous workstations, none thus far account for the addition of RC systems. Our analytic performance model includes the effects of the reconfigurable device, application load imbalance, background user load, basic message passing communication, and processor heterogeneity. The methodology proves to be accurate in characterizing these effects for applications running on shared, homogeneous, and heterogeneous HPRC resources. The model error in all cases was found to be less than 5% for application runtimes greater than 30s, and less than 15% for runtimes less than 30s.
52872904
Simulative analysis of dynamic scheduling heuristics for reconfigurable computing of parallel applications
The demand for processing power has been ever increasing with the growth of high-performance computing (HPC) applications and so have the constraints restricting the solutions to such requirements. High-performance distributed and parallel computing and custom-built, hardware-based computing have attempted to address this problem with some success but at a substantial cost. Recently, systems augmented with Field-Programmable Gate Arrays (FPGAs) offering a fusion of traditional parallel and distributed machines with customizable and dynamically reconfigurable hardware have emerged as a cost-effective alternative to traditional systems. However, providing a robust runtime environment for such systems to which HPC users have become accustomed has been fraught with numerous challenges. Dynamic scheduling of large-scale HPC applications in such parallel reconfigurable computing (RC) environments is one such challenge and has not been sufficiently studied to our knowledge. In this paper, we simulatively analyze the performance of several common HPC scheduling heuristics that can be used by an automated job management service to schedule application tasks on a parallel RC system. We also present a performance prediction model which the scheduling heuristics employ to schedule several common HPC applications on a collection of typical FPGA processing platforms.