PI SA: A PERSONALIZED INFORMATION SEARCH ASSISTANT

A common characteristic of most of the traditional search and retrieval systems is that they are oriented towards a generic user, often failing in connecting people with what they are really looking for. In this paper we present PI SA, a Personalized Information Search Assistant, which, rather than relying on the unrealistic assumption that the user will precisely specify what she is really looking for when searching, leverages implicit information about the user\u27s interests. PI SA is a desktop application which provides the user with a highly personalized information space where she can create, manage and organize folders (similarly to email programs), and manage documents retrieved by the system into her folders to best fit her needs. Furthermore, PI SA offers different mechanisms to search the Web, and the possibility of personalizing result delivery and visualization. PI SA learns user and folder profiles from user\u27s choices, and uses these profiles to improve retrieval effectiveness in searching by selecting the relevant resources to query and filtering the results accordingly. A working prototype has been also developed, tested and evaluated. Preliminary user evaluation and experimental results are very promising, showing that the personalized search environment PI SA provides considerably increases effectiveness and user satisfaction in the searching process

Evaluating Load Balancing in Peer-to-Peer Resource Sharing Algorithms for Wireless Mesh Networks

Wireless mesh networks are a promising area for the deployment of new wireless communication and networking technologies. In this paper, we address the problem of enabling effective peer-to-peer resource sharing in this type of networks. In particular, we consider the well-known Chord protocol for resource sharing in wired networks and the recently proposed MeshChord specialization for wireless mesh networks, and compare their performance under various network settings for what concerns total generated traffic and load balancing. Both iterative and recursive key lookup implementation in Chord/MeshChord are considered in our extensive performance evaluation. The results confirm superiority of MeshChord with respect to Chord, and show that recursive key lookup is to be preferred when considering communication overhead, while similar degree of load unbalancing is observed. However, recursive lookup implementation reduces the efficacy of MeshChord cross-layer design with respect to the original Chord algorithm. MeshChord has also the advantage of reducing load unbalancing with respect to Chord, although a moderate degree of load unbalancing is still observed, leaving room for further improvement of the MeshChord design

Tandem repeats discovery service (TReaDS) applied to finding novel cis-acting factors in repeat expansion diseases

<p>Abstract</p> <p>Background</p> <p>Tandem repeats are multiple duplications of substrings in the DNA that occur contiguously, or at a short distance, and may involve some mutations (such as substitutions, insertions, and deletions). Tandem repeats have been extensively studied also for their association with the class of repeat expansion diseases (mostly affecting the nervous system). Comparative studies on the output of different tools for finding tandem repeats highlighted significant differences among the sets of detected tandem repeats, while many authors pointed up how critical it is the right choice of parameters.</p> <p>Results</p> <p>In this paper we present <it>TReaDS - Tandem Repeats Discovery Service</it>, a <it>tandem repeat meta search engine</it>. <it>TReaDS </it>forwards user requests to several state of the art tools for finding tandem repeats and merges their outcome into a single report, providing a global, synthetic, and comparative view of the results. In particular, <it>TReaDS </it>allows the user to (<it>i</it>) simultaneously run different algorithms on the same data set, (<it>ii</it>) choose for each algorithm a different setting of parameters, and (<it>iii</it>) obtain a report that can be downloaded for further, off-line, investigations. We used <it>TReaDS </it>to investigate sequences associated with repeat expansion diseases.</p> <p>Conclusions</p> <p>By using the tool <it>TReaDS </it>we discover that, for 27 repeat expansion diseases out of a currently known set of 29, <it>long fuzzy tandem repeats </it>are covering the expansion loci. Tests with control sets confirm the specificity of this association. This finding suggests that long fuzzy tandem repeats can be a new class of cis-acting elements involved in the mechanisms leading to the expansion instability.</p> <p>We strongly believe that biologists can be interested in a tool that, not only gives them the possibility of using multiple search algorithm at the same time, with the same effort exerted in using just one of the systems, but also simplifies the burden of comparing and merging the results, thus expanding our capabilities in detecting important phenomena related to tandem repeats.</p

TRStalker: an Efficient Heuristic for Finding NP-Complete Tandem Repeats

Genomic sequences in higher eucaryotic organisms contain a substantial amount of (almost) repeated sequences. Tandem Repeats (TRs) constitute a large class of repetitive sequences that are originated via phenomena such as replication slippage, are characterized by close spatial contiguity, and play an important role in several molecular regulatory mechanisms. Certain types of tandem repeats are highly polymorphic and constitute a fingerprint feature of individuals. Abnormal TRs are known to be linked to several diseases. Researchers in bio-informatics in the last 20 years have proposed many formal definitions for the rather loose notion of a Tandem Repeat and have proposed exact or heuristic algorithms to detect TRs in genomic sequences. The general trend has been to use formal (implicit or explicit) definitions of TR for which verification of the solution was easy (with complexity linear, or polynomial in the TR\u27s length and substitution+indel rates) while the effort was directed towards identifying efficiently the sub-strings of the input to submit to the verification phase (either implicitly or explicitly). In this paper we take a step forward: we use a definition of TR for which also the verification step is difficult (in effect, NP-complete) and we develop new filtering techniques for coping with high error levels. The resulting heuristic algorithm, christened TRStalker, is approximate since it cannot guarantee that all NP-Complete Tandem Repeats satisfying the target definition in the input string will be found. However, in synthetic experiments with 30% of errors allowed, TRStalker has demonstrated a very high recall (ranging from 100% to 60%, depending on motif length and repetition number) for the NP-complete TRs. TRStalker has consistently better performance than some stateof- the-art methods for a large range of parameters on the class of NP-complete Tandem Repeats. TRStalker aims at improving the capability of TR detection for classes of TRs for which existing methods do not perform well

Beaconing Performance in IEEE 802.11p Vehicular Networks: the Effect of Radio Channel Congestion

In this paper, we study the performance of the beaconing mechanism underlying active safety vehicular applications in presence of different levels of channel congestion. The importance of this study lies in the fact that channel congestion is considered a major factor influencing communication performance in vehicular networks, and that ours is the first investigation of the effects of congestion based on extensive, real-world measurements. The results of our study reveal that congestion has a profound impact on the most important beaconing performance metric, namely, packet (beacon) inter reception time, influencing not only the average value, but also the shape of the distribution. Congestion also considerably increases the frequency of potentially dangerous situation-awareness blackouts, with a likely negative impact on the effectiveness of active safety applications. Our study also reveals that multihop propagation of beaconing information can be used as an effective means of lessening the negative impact of congestion on beaconing performance

Multihop Beaconing Forwarding Strategies in Congested IEEE 802.11p Vehicular Networks

Abstract?Multi-hop propagation of situational information is a promising technique for improving beaconing performance and increasing the degree of situational awareness onboard vehicles. A possible way of achieving this is by piggyback information on the beacon packets that are sent periodically by each vehicle in the network, as prescribed by the DSRC and ETSI standards. However, prescribed limitations on beacon size imply that only information about a very small number of surrounding vehicles can be piggybacked in a beacon packet. In most traffic situations, this number is well below the typical number of vehicles within transmission range, implying that multi-hop forwarding strategies must be devised to select which neighboring vehicle?s information to include in a transmitted beacon. In this paper, we designed different multi-hop forwarding strategies, and assessed their effectiveness in delivering fresh situational information to surrounding vehicles. Effectiveness is estimated in terms of both information age and probability of experiencing a potentially dangerous situational-awareness blackout. Both metrics are estimated as a function of the hop distance from the transmitting vehicle, and in presence of different level of radio channel congestion. The investigation is based on extensive simulations whose multi-hop communication performance is corroborated by real-world measurements. The results show that network-coding based strategies substantially improve forwarding performance as compared to a randomized strategy, reducing the average information age of up to 60%, and the blackout probability of up to two orders of magnitude.We also consider the effect of multi-hop propagation of situational information on the reliability of a forward collision warning application, and show that network-coding based propagation yields a factor three improvement of reliability with respect to arandomized forwarding strategy, and even higher improvements with respect to the case of no propagation

Multihop Beaconing Forwarding Strategies in Congested IEEE 802.11p Vehicular Networks

Multi-hop propagation of situational information is a promising technique for improving beaconing performance and increasing the degree of situational awareness onboard vehicles. However, limitation on beacon size prescribed by standardization bodies implies that only<br> information about 3-4 surrounding vehicles can be piggybacked in a beacon packet. In most traffic situations, the number of vehicles within transmission range is much larger than 3-4, implying that multi-hop forwarding strategies must be devised to select which neighboring<br> vehicle\u27s information to include in a transmitted beacon. In this paper, we investigate the effectiveness of different multi-hop forwarding strategies in delivering fresh situational information to surrounding vehicles. Effectiveness is estimated in terms of both average information age<br> and probability of experiencing a situational-awareness blackout of at least 1 sec. Both metrics are estimated as a function of the hop distance from the transmitting vehicle, and in presence of different level of radio channel congestion. The investigation is based on extensive simulations<br> whose multi-hop communication performance is corroborated by real-world measurements. <br> The results show that network-coding based strategies substantially improve forwarding performance as compared to a randomized strategy, reducing the average information age of up to 60%, the blackout probability of up to two orders of magnitude.<br> We also consider the effect of multi-hop propagation of situational information on the reliability of a forward collision warning application, and show that network-coding based propagation yields a factor three improvement of reliability with respect to a randomized forwarding strategy, and even higher improvements with respect to the case of no propagatio

Measuring IEEE 802.11p Performance for Active Safety Applications in Cooperative Vehicular Systems

Abstract-In this paper, we present a measurement study of application layer performance in IEEE 802.11p vehicular networks. More specifically, our focus is on active safety applications, which are based on the exchange of beacon messages containing status information between close-by vehicles. We consider two performance metrics relevant to active safety applications: the first is application-layer goodput, which can be used to optimize congestion control techniques aimed at limiting the beaconing load on the wireless channel; the second is the beacon reception rate, which is useful to estimate the level of situation awareness achievable onboard vehicles. Our measurements were conducted using a prototypal, 802.11p compliant communication device developed by NEC, in both stationary and mobile V2V scenarios, and disclosed several useful insights on 802.11p application-level performance. To the best of our knowledge, the ones presented in this paper are the first application-level measurements of IEEE 802.11p based vehicular networks reported in the literature

Load Balancing Hashing for Geographic Hash Tables

In this paper, we address the problem of balancing the network traffic load generated when querying a geographic hash table. State-of-the-art approaches can be used to improve load balancing by changing the underlying geo-routing protocol used to forward queries in the geographic hash table. However, this comes at the expense of considerably complicating the routing process, which no longer occurs along (near) straightline trajectories, but requires computing complex geometric transformations. Thus, current load balancing approaches are impractical in application scenarios where the nodes composing the geographic hash table have limited computational power, such as in most wireless sensor networks. In this paper, we propose a novel approach to solve the traffic load balancing problem in geographic hash tables: instead of changing the (near) straight-line geo-routing protocol used to send a query from the node issuing the query (the source) to the node managing the queried key (the destination), we propose to "reverse engineer" the hash function so that the resulting destination density, when combined with a given source density, yields a perfectly balanced load distribution. We first formally characterize the desired destination density as a solution of a complex integral equation. We then present explicit destination density functions (taken from the family of Beta distributions) yielding quasi-perfect load balancing under the assumption of uniformly distributed sources. Our theoretical results are derived under an infinite node density model. In order to prove practicality of our approach, we have performed extensive simulations resembling realistic wireless sensor network deployments showing the effectiveness of our approach in considerably improving load balancing. Differently from previous work, the load balancing technique proposed in this paper can be readily applied in geographic hash tables composed of computationally constrained nodes, as it is typically the case in wireless sensor networks

TReaDS: Tandem Repeats Discovery Service

Tandem repeats (TRs) are multiple duplications of substrings in the DNA that occur contiguously, or at a short distance, and may involve some mutations (such as substitutions, insertions, and deletions). The analysis of TRs is an important genetic profiling technique. In fact, TRs can be used, for instance, to detect evolutionary phenomena in populations, to identify the cause of several diseases, and to help in determining parentage. There are several web-based resources or downloadable packages for finding TRs, but such tools rarely give exactly the same result for a given input. Thus, biologists could be interested in a tool that, not only gives them the possibility of querying multiple systems at the same time, but also simplifies the burden of comparing and merging the results. TReaDS (Tandem Repeats Discovery Service) is a tandem repeat meta search engine that finds exact, approximate, short and long TRs. TReaDS queries several web-based tools and merges their outcome into a single report, providing a global, synthetic, and comparative view of the different results. Availability: TReaDS, the Tandem Repeats Discovery Service, is a web application free and open to all users without login requirement at the following URL: http://bioalgo.iit.cnr.it/treads