43,694 research outputs found
Link stability estimation based on link connectivity changes in mobile ad-hoc networks
No full textDear Wang,
Re: Link Stability Estimation Based on Link Connectivity Changes in Mobile Ad-hoc Networks
I have not been able to assess if this is an author version peer-reviewed or is it an author version non peer reviewed. Could you please clarify this so I can proceed to add your paper to Spiral. Spiral digital repository only accept peer-reviewed papers.
30/11/12 author has confirmed peer reviewe
Bridging distributed hash tables in wireless ad-hoc networks
No full textThe adaptation of structured P2P networks, i.e.
Distributed Hash Tables (DHTs), to wireless ad-hoc networks has
been investigated in recent years. Existing work assume all peers
would come to an agreement on establishing one uniform DHT
across the entire network. However, in reality, there isn’t a defacto
standard of DHT implementation, different DHTs co-exist.
We present a novel protocol, known as the DHT-gatewaying
model, which enables cross-DHT searching between multiple
DHTs of different implementations
Practical Short Signature Batch Verification
No full textIn many applications, it is desirable to work with digital signatures that are short, and yet where many messages from different signers be verified very quickly. RSA signatures satisfy the latter condition, but are generally thousands of bits in length. Recent developments in pairing-based cryptography produced a number of “short” signatures which provide equivalent security in a fraction of the space. Unfortunately, verifying these signatures is computationally intensive due to the expensive pairing operation. Toward achieving “short and fast” signatures, Camenisch, Hohenberger and Pedersen (Eurocrypt 2007) showed how to batch verify two pairing-based schemes so that the total number of pairings was independent of the number of signatures to verify. In this work, we present both theoretical and practical contributions. On the theoretical side, we introduce new batch verifiers for a wide variety of regular, identity-based, group, ring and aggregate signature schemes. These are the first constructions for batching group signatures, which answers an open problem of Camenisch et al. On the practical side, we implement each of these algorithms and compare each batching algorithm to doing individual verifications. Our goal is to test whether batching is practical; that is, whether the benefits of removing pairings significantly outweigh the cost of the additional operations required for batching, such as group membership testing, randomness generation, and additional modular exponentiations and multiplications. We experimentally verify that the theoretical results of Camenisch et al. and this work, indeed, provide an efficient, effective approach to verifying multiple signatures from (possibly) different signers
Calibration of the Radiocarbon Time Scale for the Southern Hemisphere: AD 1850-950
No full textWe have conducted a series of radiocarbon measurements on decadal samples of dendrochronologically dated wood from both hemispheres, spanning 1000 years (McCormac et al. 1998; Hogg et al. this issue). Using the data presented in Hogg et al., we show that during the period AD 950-1850 the 14C offset between the hemispheres is not constant, but varies periodically (~130 yr periodicity) with amplitudes varying between 1 and 10‰ (i.e. 8-80 yr), with a consequent effect on the 14C calibration of material from the Southern Hemisphere. A large increase in the offset occurs between AD 1245 and 1355. In this paper, we present a Southern Hemisphere high-precision calibration data set (SHCal02) that comprises measurements from New Zealand, Chile, and South Africa. This data, and a new value of 41 ± 14 yr for correction of the IntCal98 data for the period outside the range given here, is proposed for use in calibrating Southern Hemisphere 14C dates
THE EFFECTS OF AD-BLOCK WALL LEVEL, AD-BLOCK WALL MESSAGE FRAME, EXPLICIT GOAL EXISTENCE AND AD TYPE ON PSYCHOLOGICAL REACTANCE, UNCONSCIOUS AD PROCESSING AND ONLINE NEWS BRAND EVALUATION
No full textMyopic loss aversion can take place when news media management and advertisers focus too much on preventing short-term losses. Although ad-bock walls may successfully block the ad-block users’ access, two studies here have shown that the ad-block wall can backfire when ad-block users perceive their freedom as being threatened. In study 1, depending on the goal type and ad-block wall level, ad-block users evaluated the ad-block walls and news media brand differently. The results showed that high-level ad-block walls and explicit goal conditions together tend to generate greater reactance than other conditions. In addition, the finding showed that loss-frame wall messages in high-reactant condition (i.e., high-level ad-block wall) can result in more negative responses than gain-frame wall messages. Study 2 found that perceived reactance from the ad-block wall processing can influence the unconscious advertised brand ratings if the ad format was perceived as a distractor. The results showed that distractor devaluation was generated in the banner ad condition but not in the native ad condition which implies that the native ad format needs to be considered as a possible future of advertising.
Keywords: Ad-block, Ad-block Wall, Psychological Reactance, Distractor Devaluation, Native Advertising, Affect Transfer, Advertising Avoidance, Unconscious Ad Processin
When Peer-to-Peer comes Face-to-Face: Collaborative Peer-to-Peer Computing in Mobile Ad hoc Networks
No full textThis paper motivates and describes the notion of mobile ad hoc information systems. Such a system consists of a decentralized and self-organizing network of autonomous, mobile devices that interact as peers. Connectivity is determined by distance between devices; as hosts change their physical location they establish pair-wise communication links based on mutual proximity. We describe application scenarios for mobile ad hoc information systems and identify technical challenges of a generic software infrastructure. Moreover, we present the goals and architecture of Proem, a peer-to-peer system and development platform for mobile ad hoc applications. Proem has successfully been used as instructional tool in an advanced software engineering course on peer-to-peer computing
Cerebral atrophy in mild cognitive impairment and Alzheimer disease: rates and acceleration.
No full textOBJECTIVE: To quantify the regional and global cerebral atrophy rates and assess acceleration rates in healthy controls, subjects with mild cognitive impairment (MCI), and subjects with mild Alzheimer disease (AD). METHODS: Using 0-, 6-, 12-, 18-, 24-, and 36-month MRI scans of controls and subjects with MCI and AD from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, we calculated volume change of whole brain, hippocampus, and ventricles between all pairs of scans using the boundary shift integral. RESULTS: We found no evidence of acceleration in whole-brain atrophy rates in any group. There was evidence that hippocampal atrophy rates in MCI subjects accelerate by 0.22%/year2 on average (p = 0.037). There was evidence of acceleration in rates of ventricular enlargement in subjects with MCI (p = 0.001) and AD (p < 0.001), with rates estimated to increase by 0.27 mL/year2 (95% confidence interval 0.12, 0.43) and 0.88 mL/year2 (95% confidence interval 0.47, 1.29), respectively. A post hoc analysis suggested that the acceleration of hippocampal loss in MCI subjects was mainly driven by the MCI subjects that were observed to progress to clinical AD within 3 years of baseline, with this group showing hippocampal atrophy rate acceleration of 0.50%/year2 (p = 0.003). CONCLUSIONS: The small acceleration rates suggest a long period of transition to the pathologic losses seen in clinical AD. The acceleration in hippocampal atrophy rates in MCI subjects in the ADNI seems to be driven by those MCI subjects who concurrently progressed to a clinical diagnosis of AD
The Impact of Ad Characteristics on Adolescents’ Attitudes Towards Antismoking Ads
No full textSmoking exerts a considerable burden not only on those who smoke but just as well on society at large. In response, governments and institutions often resort to advertising which aims to discourage smoking. Unfortunately, our knowledge of the workings of antismoking advertising is detrimentally limited. In particular, the literature delving into the impact of antismoking ad characteristics (e. g., ad content, valence, intensity) on the overall effectiveness of antismoking advertising is scarce and contradictory. This empirical study aims to enhance the knowledge of antismoking advertising by presenting results of the survey involving Slovene adolescents. The adolescents were first exposed to advertisements of different antismoking ad contents (for the purpose of this study the term ‘ad content’ refers to types of appeals used in antismoking advertising), ad valence and intensity, and later invited to respond to a number of questions measuring their attitudes toward the ads, their attitudes toward smoking, their intentions to smoke, etc. The results indicate that while the different intensity and valence of ads produce varying attitudes toward the ads, we could not confirm these differences based on ad content. Also, we found that adolescent smokers respond to antismoking ads differently than do their nonsmoking peers. Our findings offer several important implications for antismoking advertisers and the research community interested in the workings of antismoking advertising.smoking and adolescents, antismoking advertising, attitudes toward antismoking ads
A Fair and Secure Cluster Formation Process for Ad Hoc Networks
No full textAn efficient approach for organizing large ad hoc networks is to divide the nodes
into multiple clusters and designate, for each cluster, a clusterhead which is responsible for
holding intercluster control information. The role of a clusterhead entails rights and duties.
On the one hand, it has a dominant position in front of the others because it manages the
connectivity and has access to other node¿s sensitive information. But on the other hand, the
clusterhead role also has some associated costs. Hence, in order to prevent malicious nodes
from taking control of the group in a fraudulent way and avoid selfish attacks from suitable
nodes, the clusterhead needs to be elected in a secure way. In this paper we present a novel
solution that guarantees the clusterhead is elected in a cheat-proof manner
Transmission of short messages using dynamic ad-hoc WiFi networks
No full textBezvadu un mobilie datu pārraides tīkli nav pieejami visur. Šādos apvidos ir vairāki svarīgi scenāriji, kuros vērtīga būtu iespēja pārraidīt īsus ziņojumus starp vairākiem dalībniekiem. Darba mērķis ir izveidot šādu ziņojumu pārraides risinājumu.
Darbā autors apraksta prototipa risinājuma izstrādi īsu ziņojumu apraidei starp mobilajām ierīcēm, izmantojot dinamiskus 802.11b/g bezvadu tīklus Ad-Hoc režīmā, kā arī autora izstrādātu UDP bāzētu ziņojumu apraides protokolu ALAN. Darbā demonstrēta prototipa risinājuma veiksmīga darbība gan uz klēpjdatoriem, gan Nokia N900 viedtelefona. Katrs dinamiskā Ad-Hoc bezvadu tīkla dalībnieks spēj saņemt pārējo dalībnieku teksta ziņojumus un atrašanās pozīcijas koordinātes no dalībniekiem ar GPS uztvērējiem. Izstrādātais protokols ir paplašināms, lai nākotnē spētu atbalstīt jaunus ziņojumu tipus.Wireless and mobile data networks are not omnipresent. In such uncovered areas there are several key use cases, where ability to exchange short messages between multiple participants would be valuable. The purpose of this work is to present such a solution for message exchange.
The author designs and presents a solution for short message exchange between mobile devices using dynamic 802.11b/g wireless networks in Ad-Hoc mode as well as UDP based message dissemination protocol ALAN. Successful operation of prototype solution is further demonstrated both on laptops as well as Nokia N900 smartphone. Each participant in dynamic Ad-Hoc network is able to receive text messages and GPS location data from other participants, assuming they have GPS receivers. The protocol is further expandable to support new message types in the future
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