Investigating affordances of virtual worlds for real world B2C e-commerce

Virtual worlds are three-dimensional (3D) online persistent multi-user environments where users interact through avatars. The literature suggests that virtual worlds can facilitate real world business-to-consumer (B2C) e-commerce. However, few real world businesses have adopted virtual worlds for B2C e-commerce. In this paper, we present results from interviews with consumers in a virtual world to investigate how virtual worlds can support B2C e-commerce. A thematic analysis of the data was conducted to uncover affordances and constraints of virtual worlds for B2C e-commerce. Two affordances (habitability and appearance of realness) and one constraint (demand for specialised skill) were uncovered. The implications of this research for designers are (1) to provide options to consumers that enable them to manage their online reputation, (2) to focus on managing consumers’ expectations and (3) to facilitate learning between consumers

Adaptive range filters for cold data: avoiding trips to siberia

ABSTRACT Bloom filters are a great technique to test whether a key is not in a set of keys. This paper presents a novel data structure called ARF. In a nutshell, ARFs are for range queries what Bloom filters are for point queries. That is, an ARF can determine whether a set of keys does not contain any keys that are part of a specific range. This paper describes the principles and methods for efficient implementation of ARFs and presents the results of comprehensive experiments that assess the precision, space, and latency of ARFs. Furthermore, this paper shows how ARFs can be applied to a commercial database system that partitions data into hot and cold regions to optimize queries that involve only hot data

Tians scheduling: Using partial processing in best-effort applications

Abstract-To service requests with high quality, interactive services such as web search, on-demand video and online gaming keep average server utilization low. As servers become busy, queuing delays increase, and requests miss their deadlines, resulting in degraded quality of service with poor user experience and potential revenue loss. In this paper, we propose Tians scheduling, a group of scheduling algorithms for interactive services that can produce partial answers during overload. A Tians scheduler allocates processing time to each request based on system load with the objective of maximizing overall quality of responses. We propose three Tians scheduling algorithms -offline, online clairvoyant and online nonclairvoyant. For interactive applications with concave quality profile, we prove that the offline algorithm is optimal. We show the effectiveness of the online algorithms by conducting a simulation study modeling important applications -a web search engine and video-ondemand (VOD) system. Simulation results show a significant improvement of Tians over traditional server models: average response quality improves and the variance of responses decreases. Keywords-interactive services, best-effort applications, offline, online clairvoyant, online nonclairvoyant, partial results, quality profile, scheduling, VOD bandwidth allocation, web search engine

Linqits: Big data on little clients

ABSTRACT We present LINQits, a flexible hardware template that can be mapped onto programmable logic or ASICs in a heterogeneous system-on-chip for a mobile device or server. Unlike fixed-function accelerators, LINQits accelerates a domainspecific query language called LINQ. LINQits does not provide coverage for all possible applications-however, existing applications (re-)written with LINQ in mind benefit extensively from hardware acceleration. Furthermore, the LINQits framework offers a graceful and transparent migration path from software to hardware. LINQits is prototyped on a 2W heterogeneous SoC called the ZYNQ processor, which combines dual ARM A9 processors with an FPGA on a single die in 28nm silicon technology. Our physical measurements show that LINQits improves energy efficiency by 8.9 to 30.6 times and performance by 10.7 to 38.1 times compared to optimized, multithreaded C programs running on conventional ARM A9 processors

On the Energy Overhead of Mobile Storage Systems

Abstract Secure digital cards and embedded multimedia cards are pervasively used as secondary storage devices in portable electronics, such as smartphones and tablets. These devices cost under 70 cents per gigabyte. They deliver more than 4000 random IOPS and 70 MBps of sequential access bandwidth. Additionally, they operate at a peak power lower than 250 milliwatts. However, software storage stack above the device level on most existing mobile platforms is not optimized to exploit the low-energy characteristics of such devices. This paper examines the energy consumption of the storage stack on mobile platforms. We conduct several experiments on mobile platforms to analyze the energy requirements of their respective storage stacks. Software storage stack consumes up to 200 times more energy when compared to storage hardware, and the security and privacy requirements of mobile apps are a major cause. A storage energy model for mobile platforms is proposed to help developers optimize the energy requirements of storage intensive applications. Finally, a few optimizations are proposed to reduce the energy consumption of storage systems on these platforms

Scaling Network Verification using Symmetry and Surgery

Abstract On the surface, large data centers with about 100,000 stations and nearly a million routing rules are complex and hard to verify. However, these networks are highly regular by design; for example they employ fat tree topologies with backup routers interconnected by redundant patterns. To exploit these regularities, we introduce network transformations: given a reachability formula and a network, we transform the network into a simpler to verify network and a corresponding transformed formula, such that the original formula is valid in the network if and only if the transformed formula is valid in the transformed network. Our network transformations exploit network surgery (in which irrelevant or redundant sets of nodes, headers, ports, or rules are "sliced" away) and network symmetry (say between backup routers). The validity of these transformations is established using a formal theory of networks. In particular, using Van BenthemHennessy-Milner style bisimulation, we show that one can generally associate bisimulations to transformations connecting networks and formulas with their transforms. Our work is a development in an area of current wide interest: applying programming language techniques (in our case bisimulation and modal logic) to problems in switching networks. We provide experimental evidence that our network transformations can speed up by 65x the task of verifying the communication between all pairs of Virtual Machines in a large datacenter network with about 100,000 VMs. An all-pair reachability calculation, which formerly took 5.5 days, can be done in 2 hours, and can be easily parallelized to complete in minutes

Investigation of a novel approach to scoring Giemsa-stained malaria-infected thin blood films

Daily assessment of the percentage of erythrocytes that are infected ('percent-parasitaemia') across a time-course is a necessary step in many experimental studies of malaria, but represents a time-consuming and unpopular task among researchers. The most common method is extensive microscopic examination of Giemsa-stained thin blood-films. This study explored a method for the assessment of percent-parasitaemia that does not require extended periods of microscopy and results in a descriptive and permanent record of parasitaemia data that is highly amenable to subsequent 'data-mining'. Digital photography was utilized in conjunction with a basic purpose-written computer programme to test the viability of the concept. Partial automation of the determination of percent parasitaemia was then explored, resulting in the successful customization of commercially available broad-spectrum image analysis software towards this aim. Lastly, automated discrimination between infected and uninfected RBCs based on analysis of digital parameters of individual cell images was explored in an effort to completely automate the calculation of an accurate percent-parasitaemia

Efficient scale-space spatiotemporal saliency tracking for distortion-free video retargeting

Abstract. Video retargeting aims at transforming an existing video in order to display it appropriately on a target device, often in a lower resolution, such as a mobile phone. To preserve a viewer's experience, it is desired to keep the important regions in their original aspect ratio, i.e., to maintain them distortionfree. Most previous methods are susceptible to geometric distortions due to the anisotropic manipulation of image pixels. In this paper, we propose a novel approach to distortion-free video retargeting by scale-space spatiotemporal saliency tracking. An optimal source cropping window with the target aspect ratio is smoothly tracked over time, and then isotropically resized to the retargeted display. The problem is cast as the task of finding the most spatiotemporally salient cropping window with minimal information loss due to resizing. We conduct the spatiotemporal saliency analysis in scale-space to better account for the effect of resizing. By leveraging integral images, we develop an efficient coarse-to-fine solution that combines exhaustive coarse and gradient-based fine search, which we term scale-space spatiotemporal saliency tracking. Experiments on real-world videos and our user study demonstrate the efficacy of the proposed approach

Decision aid system founded on nonlinear valuation, dispersion-based weighting and correlative aggregation for wire rope selection in slope stability cable nets

This paper presents a decision aid system to address hierarchically structured decision-making problems based on the determination of the satisfaction provided by a group of alternatives in relation to multiple conflicting subcriteria grouped into criteria. The system combines the action of three new methods related to the following concepts: nonlinear valuation, dispersion-based weighting and correlative aggregation. The first includes five value functions that allow the conversion of the ratings of the alternatives regarding the subcriteria into the satisfaction they produce in a versatile and simple manner through the Beta Cumulative Distribution Function. The use of measures of dispersion to weight the subcriteria by giving more importance to those factors that can make a difference due to their heterogeneity is revised to validate it when the values are not normally distributed. Dependencies between subcriteria are taken into account through the determination of their correlation coefficients, whose incorporation adjusts the results provided by the system to favour those alternatives having a balanced behaviour with respect to conflicting aspects. The overall satisfaction provided by each alternative is determined using a prioritisation operator to avoid compensation between criteria when aggregating the subcriteria. The system was tested through a novel field of application such as the selection of wire rope to form slope stability cable nets.The authors wish to express their gratitude to the IP department of INCHALAM S.A., whose collaboration and support made this paper possible

On the Communication of Scientific Results: The Full-Metadata Format

In this paper, we introduce a scientific format for text-based data files, which facilitates storing and communicating tabular data sets. The so-called Full-Metadata Format builds on the widely used INI-standard and is based on four principles: readable self-documentation, flexible structure, fail-safe compatibility, and searchability. As a consequence, all metadata required to interpret the tabular data are stored in the same file, allowing for the automated generation of publication-ready tables and graphs and the semantic searchability of data file collections. The Full-Metadata Format is introduced on the basis of three comprehensive examples. The complete format and syntax is given in the appendix