CiteULike: Author Bhargava

Cross-Layer Rate and Power Adaptation Strategies for IR-HARQ Systems over Fading Channels with Memory: A SMDP-Based Approach

AK Karmokar — 2008-08-19T00:14:58-00:00

Communications, IEEE Transactions on, Vol. 56, No. 8. (2008), pp. 1352-1365.

Incremental-redundancy hybrid automatic repeatrequest (IR-HARQ) schemes are proposed in several wireless standards for increased throughput-efficiency and greater reliability. We investigate transmit power and modulation order adaptation strategies for the IR-HARQ schemes over correlated Rayleigh fading channels using semi-Markov decision processbased model. In order to jointly analyze physical layer and link layer, transmitter model incorporates a finite-size buffer that receives randomly varying traffic from a higher layer application. It is assumed that channel variations can be modeled with a firstorder Markov chain. We show that the optimal transmission power and rate adaptation laws under buffering delay and packet overflow constraints can be obtained using the framework of semi-Markov decision process. We discuss three different adaptation models for the IR-HARQ schemes and compare their performances with the non-adaptive scheme. It is shown that unique optimal policy exists for each case and it can be computed using linear programming approach. This optimal policy is then applied for realistic channel fading and incoming traffic samples to evaluate its performance for both hard-decision and softdecision decoding. Simulation results in general point out that substantial power savings can be achieved using adaptation and also if the transmission-delay requirements are relaxed.

Comparative proteogenomics: Combining mass spectrometry and comparative genomics to analyze multiple genomes

Nitin Gupta — 2008-07-07T09:52:16-00:00

Genome Res., Vol. 18, No. 7. (1 July 2008), pp. 1133-1142.

Recent proliferation of low-cost DNA sequencing techniques will soon lead to an explosive growth in the number of sequenced genomes and will turn manual annotations into a luxury. Mass spectrometry recently emerged as a valuable technique for proteogenomic annotations that improves on the state-of-the-art in predicting genes and other features. However, previous proteogenomic approaches were limited to a single genome and did not take advantage of analyzing mass spectrometry data from multiple genomes at once. We show that such a comparative proteogenomics approach (like comparative genomics) allows one to address the problems that remained beyond the reach of the traditional "single proteome" approach in mass spectrometry. In particular, we show how comparative proteogenomics addresses the notoriously difficult problem of "one-hit-wonders" in proteomics, improves on the existing gene prediction tools in genomics, and allows identification of rare post-translational modifications. We therefore argue that complementing DNA sequencing projects by comparative proteogenomics projects can be a viable approach to improve both genomic and proteomic annotations. 10.1101/gr.074344.107

State of the art smart spaces: application models and software infrastructure

Ramesh Singh — 2008-07-21T15:14:06-00:00

Ubiquity, Vol. 7, No. 37. (2006), pp. 2-9.

Implementing Sponsored Search in Web Search Engines: Computational Evaluation of Alternative Mechanisms

Juan Feng — 2008-07-07T15:37:12-00:00

INFORMS J. on Computing, Vol. 19, No. 1. (January 2007), pp. 137-148.

The practice of sponsored search advertising---where advertisers pay a fee to appear alongside particular Web search results---is now one of the largest and fastest growing source of revenue for Web search engines. We model and compare several mechanisms for allocating sponsored slots, including stylized versions of those used by Overture and Google, the two biggest brokers of sponsored search. The performance of these mechanisms depends on the degree of correlation between providers' willingness to pay and their relevance to the search term. Ranking providers based on the product of relevance and bid price performs well and is robust across varying degrees of correlation. Ranking purely based on bid price fares nearly as well when bids and relevance are positively correlated (the expected regime), and is further enhanced by adding an editorial filter. Regardless of the allocation mechanism, sponsored search revenues are lower when users' attention decays quickly at lower ranks, emphasizing the need to develop better user interfaces and control features. The search engine can address initial inscience of relevance scores by modifying rank allocations over time as it observes clickthroughs at each rank. We propose a rank-revision strategy that weights clicks on lower ranked items more than clicks on higher ranked items. This method is shown to converge to the optimal (maximum revenue) ordering faster and more consistently than other methods.

On timing offset estimation for OFDM systems

H Minn — 2008-06-03T14:50:55-00:00

Communications Letters, IEEE, Vol. 4, No. 7. (2000), pp. 242-244.

Two timing offset estimation methods for orthogonal frequency division multiplexing (OFDM) systems as modifications to Schmidl and Cox's method (see IEEE Trans. Commun., vol.45, p.1613-21, 1997) are presented. The performances of the timing offset estimators in additive white Gaussian noise channel and intersymbol interference channel are compared in terms of estimator variance obtained by simulation. Both proposed methods have significantly smaller estimator variance in both channel conditions

ISI-free pulses for high-data-rate ultra-wideband wireless systems

Z Hasan — 2008-05-07T22:28:13-00:00

Electrical and Computer Engineering, Canadian Journal of, Vol. 32, No. 4. (2007), pp. 187-192.

Modified intersymbol interference (ISI)¿free pulses and ISI-free band-limited polynomial pulses for ultra-wideband (UWB) communication systems are proposed to provide the possibility of very high data rates not achievable by conventional pulses and the pulse design algorithms available in the literature. The power spectrum of the proposed pulses fits the Federal Communications Commission (FCC) spectral mask for very high data rates that have quantized values with various levels. Using this scheme and a particular choice of design variables, it is possible to design orthogonal pulses that could be used for multi-user data communication after they are truncated for the same time interval. Several possible improvements for these proposed pulses are considered for certain practical cases.

Adsorption of NO on Cu Exchanged Zeolites, an FTIR Study: Effects of Cu Levels, NO Pressure, and Catalyst Pretreatment

T Cheung — 2008-05-07T15:32:27-00:00

Journal of Catalysis, Vol. 158, No. 1. (January 1996), pp. 301-310.

Three different copper zeolite systems (Cu-ZSM5, Cu-UHSY, and Cu-mordenite) have been prepared with different copper loadings from low to over exchange levels. The surface chemistry of three systems has been studied using IR spectra of adsorbed NO. Most of the copper in Cu-ZSM5 was in the form of Cu(I). Cu(II) species were predominant in Cu-mordenite. For Cu-UHSY the number of Cu(I) species increased as the level of copper loading increased. The catalytic activity for NO decomposition appeared to depend on a Cu(I)-Cu(II) redox cycle which resulted in the formation of an ON-Cu2+-NO-2complex, previously postulated as the critical intermediate in the reaction. Both oxidation and regeneration of the Cu(I) sites in Cu-ZSM5 occurred readily. In Cu-UHSY oxidation was low, suggesting that Cu(I) species were more stable. Cu(II) was the prominent copper species in Cu-mordenite, and regeneration of the Cu(I) sites was difficult. Stability, oxidation, and regeneration of Cu(I) sites play a major role in NO decomposition. In over-exchanged Cu-ZSM5, the Cu(I) sites were more stable, and the rate of oxidation was high. Furthermore a large number of reduced sites were readily regenerated from the Cu(II), thus making it the most effective catalyst for the decomposition of NO.

Membrane Binding, Structure, and Localization of Cecropin-Mellitin Hybrid Peptides: A Site-Directed Spin-Labeling Study

Kalpana Bhargava — 2008-04-24T20:45:58-00:00

Biophys. J., Vol. 86, No. 1. (1 January 2004), pp. 329-336.

The interaction of antimicrobial peptides with membranes is a key factor in determining their biological activity. In this study we have synthesized a series of minimized cecropin-mellitin hybrid peptides each containing a single cysteine residue, modified the cysteine with the sulfhydryl-specific methanethiosulfonate spin-label, and used electron paramagnetic resonance spectroscopy to measure membrane-binding affinities and determine the orientation and localization of peptides bound to membranes that mimic the bacterial cytoplasmic membrane. All of the peptides were unstructured in aqueous solution but underwent a significant conformational change upon membrane binding that diminished the rotational mobility of the attached spin-label. Apparent partition coefficients were similar for five of the six constructs examined, indicating that location of the spin-label had little effect on peptide binding as long as the attachment site was in the relatively hydrophobic C-terminal domain. Depth measurements based on accessibility of the spin-labeled sites to oxygen and nickel ethylenediaminediacetate indicated that at high lipid/peptide ratios these peptides form a singlealpha -helix, with the helical axis aligned parallel to the bilayer surface and immersed [~]5 A below the membrane-aqueous interface. Such a localization would provide exposure of charged/polar residues on the hydrophilic face of the amphipathic helix to the aqueous phase, and allow the nonpolar residues along the opposite face of the helix to remain immersed in the hydrophobic phase of the bilayer. These results are discussed with respect to the mechanism of membrane disruption by antimicrobial peptides.

On generating an integrated DSS from a mathematical model specification

HK Bhargava — 2008-03-20T17:30:13-00:00

System Sciences, 1996., Proceedings of the Twenty-Ninth Hawaii International Conference on ,, Vol. 2 (1996), pp. 396-406 vol.2.

Executable mathematical modeling languages (EMLs), designed to facilitate model representation and execution, are traditionally weak in data modeling and management, which often constitutes a majority of the effort in a modeling project. We describe a systematic approach for developing an integrated decision support system given an EML model. This approach is first demonstrated using a model for flight scheduling, integrating a formal data model, represented in a database management system, and a mathematical model, represented in an EML (GAMS). Next, we present a generalized procedure that, for any mathematical model represented in GAMS, produces a data model and a primitive user interface for the mathematical model. Benefits of this approach include explicit data modeling, improved representation and manipulation of model inputs and outputs, greater integrity of input data, and easier interpretation and multiple views of model outputs

Identification of an intersubunit cross-link between substituted cysteine residues located in the putative ATP binding site of the P2X1 receptor.

B Marquez-Klaka — 2008-02-21T15:22:07-00:00

J Neurosci, Vol. 27, No. 6. (7 February 2007), pp. 1456-1466.

P2X receptors are ATP-gated nonselective cation channels. Functional receptors are assembled as homotrimers or heterotrimers of seven cloned subunits. Each subunit contains two transmembrane domains linked by a large extracellular loop that is required for agonist binding. So far, there is no direct evidence indicating whether the agonist binding site is formed within one subunit or at the interface of two neighboring subunits. Here we used a disulfide cross-linking approach to identify pairs of residues that are in close proximity within the ATP binding site of the P2X1 homotrimer. Eight amino acid residues that have previously been shown to be essential for high ATP potency (K68, K70, F185, K190, F291, R292, R305, and K309) were substituted by cysteine residues, and the respective mutant subunits were pairwise expressed in Xenopus laevis oocytes. Nonreducing SDS-PAGE analysis of the purified receptors revealed a spontaneous and specific dimer formation between the K68C and F291C mutants. An almost complete cross-link into trimers was achieved with the K68C/F291C double mutant, consistent with the formation of intersubunit disulfide bridges. In support of this interpretation, two-electrode voltage-clamp analysis of the K68C/F291C mutations introduced into a nondesensitizing P2X(2-1) chimera showed only small ATP-activated currents that, however, increased approximately 60-fold after extracellular application of the reducing agent dithiothreitol. In addition, we show that a K68C/K309C double mutant is nonfunctional and can be functionally rescued by coexpression with nonmutated subunits. Our data are consistent with loops from neighboring P2X subunits forming the ATP-binding site in P2X receptors.

On the Design of Perceptual MPEG-Video Encryption Algorithms

Shujun Li — 2008-02-20T05:16:05-00:00

IEEE Transactions on Circuits and Systems for Video Technology, Vol. 17, No. 2. (February 2007), pp. 214-223.

In this paper, some existing perceptual encryption algorithms of MPEG videos are reviewed and some problems, especially security defects of two recently proposed MPEG-video perceptual encryption schemes, are pointed out. Then, a simpler and more effective design is suggested, which selectively encrypts fixed-length codewords in MPEG-video bit streams under the control of three perceptibility factors. The proposed design is actually an encryption configuration that can work with any stream cipher or block cipher. Compared with the previously-proposed schemes, the new design provides more useful features, such as strict size-preservation, on-the-fly encryption and multiple perceptibility, which make it possible to support more applications with different requirements. In addition, four different measures are suggested to provide better security against known/chosen-plaintext attacks

Probabilistic anonymity

Mohit Bhargava — 2008-02-14T10:07:57-00:00

(2005), pp. 171-185.

Authorization based on evidence and trust

B Bhargava — 2007-07-02T11:32:17-00:00

(2002)

Developing authorization mechanisms for secure information access by a large community of users in an open environment is challenging. Current research efforts grant privilege to a user based on his/her properties that are demonstrated by digital credentials (evidences). Holding credentials does not necessarily certify that the user is trustworthy. We use trust to characterize the possibility that a user will not carry out harmful actions. Authorization based on trust as well as evidence makes...

On Demand Media Streaming Over the Internet

M Hefeeda — 2008-01-10T12:06:18-00:00

(2002)

We propose a new model for on-demand media streaming centered around the peer-to-peer (P2P) paradigm. The proposed P2P model can support a large number of clients with a low overall system cost. The P2P model allows for peers to share some of their resources with the system and in return, they get some incentives or rewards. We describe how to realize (or deploy) the proposed model. In addition, we present a new dispersion algorithm (for disseminating the media files into the system) and a...

Gnustream: A P2P Media Streaming System Prototype

Xuxian Jiang — 2007-03-23T13:20:43-00:00

(2003)

We present the design and prototype of GnuStream, a peerto -peer (P2P) and receiver-driven media streaming system.

A robust timing and frequency synchronization for OFDM systems

Hlaing Minn — 2007-11-11T15:35:58-00:00

Wireless Communications, IEEE Transactions on, Vol. 2, No. 4. (2003), pp. 822-839.

A robust symbol-timing and carrier-frequency synchronization scheme applicable to orthogonal frequency-division-multiplexing systems is presented. The proposed method is based on a training symbol specifically designed to have a steep rolloff timing metric. The proposed timing metric also provides a robust sync detection capability. Both time domain training and frequency domain (FD) training are investigated. For FD training, maintaining a low peak-to-average power ratio of the training symbol was taken into consideration. The channel estimation scheme based on the designed training symbol was also incorporated in the system in order to give both fine-timing and frequency-offset estimates. For fine frequency estimation, two approaches are presented. The first one is based on the suppression of the interference introduced in the frequency estimation process by the training symbol pattern in the context of multipath dispersive channels. The second one is based on the maximum likelihood principle and does not suffer from any interference. A new performance measure is introduced for timing estimation, which is based on the plot of signal to timing-error-induced average interference power ratio against the timing estimate shift. A simple approach for finding the optimal setting of the timing estimator is presented. Finally, the sync detection, timing estimation, frequency estimation, and bit-error-rate performance of the proposed method are presented in a multipath Rayleigh fading channel.

Visualization of wormholes in sensor networks

Weichao Wang — 2006-11-18T05:33:45-00:00

(2004), pp. 51-60.

On the Application of Importance Sampling to BER Estimation in the Simulation of Digital Communication Systems

Qiang Wang — 2007-11-13T23:43:51-00:00

Communications, IEEE Transactions on [legacy, pre - 1988], Vol. 35, No. 11. (1987), pp. 1231-1233.

Importance sampling (IS) is a useful technique for reducing the number of Monte Carlo trials in BER estimation. Two important aspects of recent research work in this area are to find more applications of IS BER estimation and to seek a good bias scheme in the implementation of the estimator. This correspondence presents a general and rigorous mathematical description of these aspects of this problem which, we hope, will be useful for further research. We also present a general result on how to choose a good bias scheme which may provide some insight into the problem.

Optical Properties of Substitutional H- and Li-Atom Impurities in Solid Argon and Neon

Raj Bhargava — 2006-10-15T12:27:52-00:00

Physical Review B, Vol. 1, No. 1. (1 January 1970), 1.

A tight-binding formalism is presented for the calculation of the excitation energies and oscillator strengths for low-lying excitations; and of the ground-state polarizabilities; of substitutional impurities in rare-gas solids. The formalism is applied to hydrogen- and lithium-atom impurities in solid neon and in solid argon at 0Â°K; and numerical results are presented.

Progress in Web-based decision support technologies

Hemant Bhargava — 2007-08-15T20:22:27-00:00

Decision Support Systems, Vol. 43, No. 4. (August 2007), pp. 1083-1095.

World Wide Web technologies have transformed the design, development, implementation and deployment of decision support systems. This article reviews and summarizes recent technology developments, current usage of Web-based DSS, and trends in the deployment of such systems. Many firms use the Web as a medium to convey information about DSS products or to distribute DSS software. The use of Web-based computation to provide product demonstrations or to deploy DSS applications for remote access remains less common. The academic literature on Web-based DSS is largely focused on applications and implementations, and only a few articles examine architectural issues or provide design guidelines based on empirical evidence.

Proteomics and electron microscopic characterization of the unusual mitochondrial ribosome-related 45S complex in Leishmania tarentolae

Dmitri Maslov — 2007-08-07T16:09:54-00:00

Molecular and Biochemical Parasitology, Vol. 152, No. 2. (April 2007), pp. 203-212.

A novel type of ribonucleoprotein (RNP) complex has been described from the kinetoplast-mitochondria of Leishmania tarentolae. The complex, termed the 45S SSU*, contains the 9S small subunit rRNA but does not contain the 12S large subunit rRNA. This complex is the most stable and abundant mitochondrial RNP complex present in Leishmania. As shown by tandem mass spectrometry, the complex contains at least 39 polypeptides with a combined molecular mass of almost 2.1 MDa. These components include several homologs of small subunit ribosomal proteins (S5, S6, S8, S9, S11, S15, S16, S17, S18, MRPS29); however, most of the polypeptides present are unique. Only a few of them show recognizable motifs, such as protein-protein (coiled-coil, Rhodanese) or protein-RNA (pentatricopeptide repeat) interaction domains. A cryo-electron microscopy examination of the 45S SSU* fraction reveals that 27% of particles represent SSU homodimers arranged in a head-to-tail orientation, while the majority of particles are clearly different and show an asymmetric bilobed morphology. Multiple classes of two-dimensional averages were derived for the asymmetrical particles, probably reflecting random orientations of the particles and difficulties in correlating these views with the known projections of ribosomal complexes. One class of the two-dimensional averages shows a SSU moiety attached to a protein mass or masses in a monosome-like appearance. The combined mass spectrometry and electron microscopy data thus indicate that the majority 45S SSU* particles represents a heterodimeric complex in which the SSU of the Leishmania mitochondrial ribosome is associated with an additional protein mass. The biological role of these particles is not known.

Defending against wormhole attacks in mobile ad hoc networks: Research Articles

Weichao Wang — 2007-07-20T10:18:50-00:00

Wirel. Commun. Mob. Comput., Vol. 6, No. 4. (June 2006), pp. 483-503.

Trust-based privacy preservation for peer-to-peer data sharing

Yi Lu — 2007-07-02T11:15:50-00:00

Systems, Man and Cybernetics, Part A, IEEE Transactions on, Vol. 36, No. 3. (2006), pp. 498-502.

Privacy preservation in a peer-to-peer (P2P) system tries to hide the association between the identity of a participant and the data that it is interested in. This paper proposes a trust-based privacy-preservation method for P2P data sharing. It adopts the trust relation between a peer and its collaborators (buddies). The buddy works as a proxy to send the request and acquire the data. This provides a shield under which the identity of the requester and the accessed data cannot be linked. A privacy measuring method is presented to evaluate the proposed mechanism. Dynamic trust assessment and the enhancement to supplier's privacy are discussed.

Peer-to-peer file-sharing over mobile ad hoc networks

G Ding — 2007-04-10T08:51:31-00:00

Pervasive Computing and Communications Workshops, 2004. Proceedings of the Second IEEE Annual Conference on (2004), pp. 104-108.

Current peer-to-peer file-sharing systems mostly work on wired networks. Mobile ad hoc network is characterized as multihop wireless communications between mobile devices. Five routing approaches with different complexity are proposed to enable peer-to-peer file-sharing over mobile ad hoc networks. The complexity of the proposed approaches is evaluated and compared. It is concluded that the cross-layer protocols perform better than simply overlaying peer-to-peer searching protocol on mobile ad hoc networks.

Effect of hospitalist consultation on treatment of osteoporosis in hip fracture patients.

CM Jachna — 2007-04-03T17:39:02-00:00

Osteoporos Int, Vol. 14, No. 8. (August 2003), pp. 665-671.

The objective of this study was to determine if hospitalist consultation during admission for hip fracture results in improved treatment for osteoporosis. This was a retrospective chart review, carried out in a university-based academic hospital. Administrative discharge data was used to identify patients discharged between 1 September 1999 and 1 September 2001, discharged with the diagnosis of hip fracture. Eighty-two patient charts were reviewed after exclusion for traumatic and pathologic fractures. Treatment for osteoporosis consisted of medications recommended by the National Osteoporosis Foundation (NOF), including calcium (+/-vitamin D), estrogen, raloxifene, calcitonin, alendronate and risedronate. Osteoporosis treatment improvement was defined as the addition of a medication for osteoporosis that strengthened treatment. Twenty-nine percent of patients in our study received treatment for osteoporosis at the time of discharge from the hospitalization for hip fracture. While 20% received calcium, only 7% received a bisphosphonate. Twelve percent received improvement in osteoporosis treatment from admission to discharge. Those that received hospitalist consultation did not have a significant improvement in osteoporosis treatment (P=0.314), but had significantly more co-morbid illnesses and were significantly older than those receiving no consultation (P<0.05). Identification of osteoporosis as a medical problem was significantly associated with osteoporosis treatment (P<0.05). Potential barriers to hospitalist consultation's effect on osteoporosis treatment included patient age and co-morbidities. Further research is needed to identify and overcome barriers to effective osteoporosis treatment in patients with fractures.

GnuStream: a P2P media streaming system prototype

Xuxian Jiang — 2006-08-03T02:30:54-00:00

Multimedia and Expo, 2003. ICME '03. Proceedings. 2003 International Conference on, Vol. 2 (2003), pp. II-325-8 vol.2.

We present the design and prototype of GnuStream, a peer- to-peer (P2P) and receiver-driven media streaming system. GnuStream is built on top of Gnutella, and it integrates dynamic peer location and streaming capacity aggregation. Each GnuStream streaming session is controlled by the receiver peer and involves a dynamic set of peer senders instead of one fixed sender. The receiver aggregates streaming bandwidth from the multiple senders, achieving load distribution and fast reaction to sender capacity and on/off-line status changes. The effectiveness of GnuStream is demonstrated by our experiments with its prototype, which serves as the basis for real-world development and evaluation of resilient P2P media streaming services.

On peer-to-peer media streaming

Dongyan Xu — 2006-08-04T14:56:51-00:00

Distributed Computing Systems, 2002. Proceedings. 22nd International Conference on (2002), pp. 363-371.

In this paper, we study a peer-to-peer media streaming system with the following characteristics: (1) its streaming capacity grows dynamically; (2) peers do not exhibit server-like behavior; (3) peers are heterogeneous in their bandwidth contribution; and (4) each streaming session may involve multiple supplying peers. Based on these characteristics, we investigate two problems: (1) how to assign media data to multiple supplying peers in one streaming session and (2) how to quickly amplify the system's total streaming capacity. Our solution to the first problem is an optimal media data assignment algorithm OTS/sub p2p/, which results in minimum buffering delay in the consequent streaming session. Our solution to the second problem is a distributed differentiated admission control protocol DAC/sub p2p/. By differentiating between requesting peers with different outbound bandwidth, DAC/sub p2p/ achieves fast system capacity amplification; benefits all requesting peers in admission rate, waiting time, and buffering delay; and creates an incentive for peers to offer their truly available out-bound bandwidth.

Transcription and translation in bovine spermatozoa.

E Premkumar — 2007-03-05T03:44:02-00:00

Nat New Biol, Vol. 240, No. 100. (29 November 1972), pp. 139-143.

Hybrid simulations of stochastic reaction-diffusion processes for modeling intracellular signaling pathways

KH Chiam — 2007-01-20T22:17:01-00:00

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 74, No. 5. (2006)

In the intracellular environment, signaling takes place in a nonideal environment that is spatially heterogeneous and that is noisy, with the noise arising from the low copy numbers of the signaling molecules involved. In this paper, we model intracellular signaling pathways as stochastic reaction-diffusion processes and adapt techniques commonly used by physicists to solve for the spatiotemporal evolution of the signaling pathways. We then apply it to study two problems of relevance to the modeling of intracellular signaling pathways. First, we show that, in the limit of small protein diffusion which is typically the case for proteins in the cytosol crowded by other macromolecules, the extent of diffusion control, in the transient regime, on reactions is greater than previous predictions. Second, we show that the presence of scaffold proteins can modify the phosphorylation activity of a mitogen-activated protein kinase cascade, and explain how this activity is modulated by the scaffold protein concentration.

Signal Transduction and Transcriptional Regulation of Plant Defence Responses

BL Jalali — 2006-01-28T09:59:14-00:00

Journal of Phytopathology, Vol. 154, No. 2. (February 2006), pp. 65-74.

Pagoda: a dynamic overlay network for routing, data management, and multicasting

Ankur Bhargava — 2007-01-10T10:26:15-00:00

(2004), pp. 170-179.

The tremendous growth of public interest in peer-to-peer systems in recent years has initiated a lot of research work on how to design efficient and robust overlay networks for these systems. While a large collection of scalable peer-to-peer overlay networks has been proposed in recent years, many fundamental questions have remained open. Some of these are: * Is it possible to design deterministic peer-to-peer overlay networks with properties comparable to randomized peer-to-peer systems? * How can peers of non-uniform bandwidth be organized in an overlay network? We propose a dynamic overlay network called Pagoda that provides solutions to both of these problems. The Pagoda network has a constant degree, a logarithmic diameter, and a 1/logarithmic expansion, and therefore matches the properties of the best randomized overlay networks known so far. However, in contrast to these networks, the Pagoda is deterministic and therefore guarantees these properties. The Pagoda can be used to organize both nodes with uniform bandwidth and nodes with non-uniform bandwidth. For nodes with uniform bandwidth, any node insertion or deletion can be executed with logarithmic work, and for nodes with non-uniform bandwidth, any node insertion and deletion can be executed with polylogarithmic work. Moreover, the Pagoda overlay network can route arbitrary multicast problems with a congestion that is within a logarithmic factor of what a best possible overlay network of logarithmic degree for that particular multicast problem can achieve, even though the Pagoda is a constant degree network. This holds even for nodes of arbitrary non-uniform bandwidths. We also show that the Pagoda network can be used for efficient data management.

PROMISE: peer-to-peer media streaming using CollectCast

Mohamed Hefeeda — 2006-06-22T10:37:08-00:00

(2003), pp. 45-54.

Ramanujan---for lowbrows

Bruce Berndt — 2006-07-16T23:01:58-00:00

Amer. Math. Monthly, Vol. 100, No. 7. (1993), pp. 644-656.

A new minimal average weight representation for left-to-right point multiplication methods

M Khabbazian — 2006-11-14T23:30:13-00:00

Computers, IEEE Transactions on, Vol. 54, No. 11. (2005), pp. 1454-1459.

This paper introduces a new radix-2 representation with the same average weight as the width-w nonadjacent form (w-NAF). In both w-NAF and the proposed representations, each nonzero digit is an odd integer with absolute value less than M. However, for w-NAF, M is of the form 2/sup w-1/, while, for the proposed representation, it can be any positive integer. Therefore, using the proposed integer representation, we can use the available memory efficiently, which is attractive for devices with limited memory. Another advantage of the proposed representation over-w-NAF is that it can be obtained by scanning the bits from left-to-right. This property is also useful for memory-constrained devices because it can reduce both the time and space complexity of fast point multiplication techniques.

Characterization of the "native" surface thin film on pure polycrystalline iron: A high resolution XPS and TEM study

G Bhargava — 2006-11-06T14:25:32-00:00

Applied Surface Science, Vol. In Press, Corrected Proof

The characterization of the "native" surface thin film on pure polycrystalline iron has been studied by high resolution X-ray photoelectron (XP) spectroscopy of Fe 2p and O 1s regions. The film was allowed to form by exposing the sample to atmosphere at ambient conditions for a period of 1 h. The systematic approach used here includes the determination of curve fitting parameters from external standards and their use in fitting the raw data for the surface thin film. The quantitative high resolution XPS analysis involved an angle resolved study of the surface to determine the chemical composition and thickness of this native film. The film was found to be a mixture of Fe3O4 and Fe(OH)2 with a thickness of 1.2 +/- 0.3 nm. This conclusion is consistent with thermodynamics as indicated by the Pourbaix diagram for the Fe-H2O system and the phase diagram for the Fe-oxygen system. A detailed TEM study of the native surface film also supports this conclusion.

KQML as an Agent Communication Language

T Finin — 2006-10-29T10:01:21-00:00

(1994), pp. 456-463.

This document and other information on the KRSS group is available as

A hybrid architecture for cost-effective on-demand media streaming

MM Hefeeda — 2004-12-28T18:02:28-00:00

Computer Networks, Vol. 44, No. 3. (20 February 2004), pp. 353-382.

Phased-array intracardiac echocardiography monitoring during pulmonary vein isolation in patients with atrial fibrillation: impact on outcome and complications.

NF Marrouche — 2006-10-02T21:10:20-00:00

Circulation, Vol. 107, No. 21. (3 June 2003), pp. 2710-2716.

BACKGROUND: The objective of this study was to assess the impact of intracardiac echocardiography (ICE) on the long-term success and complications in patients undergoing pulmonary vein isolation (PVI) for treatment of atrial fibrillation (AF). METHODS AND RESULTS: Three hundred fifteen patients underwent PVI for treatment of AF. Each patient underwent ostial isolation of all PVs using a cooled-tip ablation catheter. PVI was performed using circular mapping (CM) alone (group 1, 56 patients), CM and ICE (group 2, 107 patients), and CM and ICE with titration of radiofrequency energy based on visualization of microbubbles by ICE (group 3, 152 patients). After a mean follow-up time of 417+/-145 days, 19.6% (11 of 56), 16.8% (18 of 107), and 9.8% (15 of 152) of patients in groups 1, 2, and 3 experienced recurrence of AF, respectively. Moreover, whereas no group 3 patient experienced severe (>70%) PV stenosis, severe PV stenosis was documented in 3 (3.5%) of 56 patients in group 1 and in 2 (1.8%) of 107 patients in group 2 (P<0.05). No embolic events were detected in group 3 patients. CONCLUSIONS: Intracardiac echocardiography improves the outcome of cooled-tip PVI. Power adjustment guided by direct visualization of microbubble formation reduces the risk of PV stenosis and improves long-term cure.

On security study of two distance vector routing protocols for mobile ad hoc networks

Weichao Wang — 2006-08-25T15:36:59-00:00

Pervasive Computing and Communications, 2003. (PerCom 2003). Proceedings of the First IEEE International Conference on (2003), pp. 179-186.

This paper compares the security properties of ad hoc on-demand distance vector (AODV) and destination sequence distance vector (DSDV) protocols, especially the difference caused by on-demand and proactive route queries. The on-demand route query enables the malicious host to conduct real time attacks on AODV. The communication overhead of attacks on DSDV is independent of the attack methods and the width of attack targets. A single false route propagates slower in AODV than in DSDV. The detection of false destination sequence in AODV heavily depends on the mobility of hosts. False distance vector and false destination sequence attacks are studied by simulation. The delivery ratio, communication overhead, and the propagation of false routes are measured by varying the traffic load and the maximum speed of host movement. The anomalous patterns of sequence numbers detected by destination hosts can be applied to detect the false destination sequence attacks.

Reliable broadcast in ZigBee networks

Gang Ding — 2006-08-11T21:08:22-00:00

Sensor and Ad Hoc Communications and Networks, 2005. IEEE SECON 2005. 2005 Second Annual IEEE Communications Society Conference on (2005), pp. 510-520.

Histones in functional diversification. Core histone variants.

RH Pusarla — 2006-08-10T11:49:33-00:00

FEBS J, Vol. 272, No. 20. (October 2005), pp. 5149-5168.

Recent research suggests that minor changes in the primary sequence of the conserved histones may become major determinants for the chromatin structure regulating gene expression and other DNA-related processes. An analysis of the involvement of different core histone variants in different nuclear processes and the structure of different variant nucleosome cores shows that this may indeed be so. Histone variants may also be involved in demarcating functional regions of the chromatin. We discuss in this review why two of the four core histones show higher variation. A comparison of the status of variants in yeast with those from higher eukaryotes suggests that histone variants have evolved in synchrony with functional requirement of the cell.

Ramanujan---for lowbrows

Bruce Berndt — 2006-07-17T19:25:59-00:00

American Mathematical Monthly, Vol. 100, No. 7. (ash 1993), pp. 644-656.

this paper is written for lowbrows. Only elementary algebra is needed to prove the lion's share of theorems reported here. Most are found in the unorganized portion of Ramanujan's second notebook, his third notebook, and problems that he posed for readers of the Journal of the Indian Mathematical Society. The results we describe fall under the headings of elementary algebra, equal sums of powers, and elementary number theory.

PROMISE: peer-to-peer media streaming using CollectCast

Mohamed Hefeeda — 2006-07-15T18:26:16-00:00

(2003), pp. 45-54.

Monitoring and controlling QoS network domains

Ahsan Habib — 2005-07-18T01:43:16-00:00

Int. J. Netw. Manag., Vol. 15, No. 1. (January 2005), pp. 11-29.

Early observations on lung function studies in symptomatic "gas" exposed population of Bhopal.

DK Bhargava — 2006-04-12T14:44:09-00:00

Indian J Med Res, Vol. 86 Suppl (1987), pp. 1-10.

KQML as an Agent Communication Language

T Finin — 2005-11-24T19:37:05-00:00

(1994), pp. 456-463.

This paper describes the design of and experimentation with the Knowledge Query and Manipulation Language (KQML), a new language and protocol for exchanging information and knowledge. This work is part of a larger effort, the ARPA Knowledge Sharing Effort which is aimed at developing techniques and methodology for building large-scale knowledge bases which are sharable and reusable. KQML is both a message format and a message-handling protocol to support run-time knowledge sharing among agents. ...

Study of distance vector routing protocols for mobile ad hoc networks

Yi Lu — 2005-08-12T12:43:48-00:00

Pervasive Computing and Communications, 2003. (PerCom 2003). Proceedings of the First IEEE International Conference on (2003), pp. 187-194.

We investigate the performance issues of destination-sequenced distance vector (DSDV) and ad-hoc on-demand distance vector (AODV) routing protocols for mobile ad hoc networks. Four performance metrics are measured by varying the maximum speed of mobile hosts, the number of connections, and the network size. The correlation between network topology change and mobility is investigated by using linear regression analysis. The simulation results indicate that AODV outperforms DSDV in less stressful situations, while DSDV is more scalable with respect to the network size. It is observed that network congestion is the dominant reason for packet drop for both protocols. We propose a new routing protocol, congestion-aware distance vector (CADV), to address the congestion issues. CADV outperforms AODV in delivery ratio by about 5%, while introduces less protocol load. The result demonstrates that integrating congestion avoidance mechanisms with proactive routing protocols is a promising way to improve performance.