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Search Results: 1 - 10 of 326563 matches for " Santosh S. Venkatesh "
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Visibility-Aware Optimal Contagion of Malware Epidemics
Soheil Eshghi,Saswati Sarkar,Santosh S. Venkatesh
Mathematics , 2015,
Abstract: Recent innovations in the design of computer viruses have led to new trade-offs for the attacker. Multiple variants of a malware may spread at different rates and have different levels of visibility to the network. In this work we examine the optimal strategies for the attacker so as to trade off the extent of spread of the malware against the need for stealth. We show that in the mean-field deterministic regime, this spread-stealth trade-off is optimized by computationally simple single-threshold policies. Specifically, we show that only one variant of the malware is spread by the attacker at each time, as there exists a time up to which the attacker prioritizes maximizing the spread of the malware, and after which she prioritizes stealth.
Observer Variability in BI-RADS Ultrasound Features and Its Influence on Computer-Aided Diagnosis of Breast Masses  [PDF]
Laith R. Sultan, Ghizlane Bouzghar, Benjamin J. Levenback, Nauroze A. Faizi, Santosh S. Venkatesh, Emily F. Conant, Chandra M. Sehgal
Advances in Breast Cancer Research (ABCR) , 2015, DOI: 10.4236/abcr.2015.41001
Abstract: Objective: Computer classification of sonographic BI-RADS features can aid differentiation of the malignant and benign masses. However, the variability in the diagnosis due to the differences in the observed features between the observations is not known. The goal of this study is to measure the variation in sonographic features between multiple observations and determine the effect of features variation on computer-aided diagnosis of the breast masses. Materials and Methods: Ultrasound images of biopsy proven solid breast masses were analyzed in three independent observations for BI-RADS sonographic features. The BI-RADS features from each observation were used with Bayes classifier to determine probability of malignancy. The observer agreement in the sonographic features was measured by kappa coefficient and the difference in the diagnostic performances between observations was determined by the area under the ROC curve, Az, and interclass correlation coefficient. Results: While some features were repeatedly observed, κ = 0.95, other showed a significant variation, κ = 0.16. For all features, combined intra-observer agreement was substantial, κ = 0.77. The agreement, however, decreased steadily to 0.66 and 0.56 as time between the observations increased from 1 to 2 and 3 months, respectively. Despite the variation in features between observations the probabilities of malignancy estimates from Bayes classifier were robust and consistently yielded same level of diagnostic performance, Az was 0.772-0.817 for sonographic features alone and 0.828-0.849 for sonographic features and age combined. The difference in the performance, ΔAz, between the observations for the two groups was small (0.003-0.044) and was not statistically significant (p < 0.05). Interclass correlation coefficient for the observations was 0.822 (CI: 0.787-0.853) for BI-RADS sonographic features alone and for those combined with age was 0.833 (CI: 0.800-0.862). Conclusion: Despite the differences in the BI-RADS sonographic features between different observations, the diagnostic performance of computer-aided analysis for differentiating breast masses did not change. Through continual retraining, the computer-aided analysis provides consistent diagnostic performance independent of the variations in the observed sonographic features.
Sequence space coverage, entropy of genomes and the potential to detect non-human DNA in human samples
Zhandong Liu, Santosh S Venkatesh, Carlo C Maley
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-509
Abstract: We have analyzed aspects of the information content of Homo sapiens, Mus musculus, Drosophila melanogaster, Caenorhabditis elegans, Arabidopsis thaliana, Saccharomyces cerevisiae, and Escherichia coli (K-12) genomes. Virtually all possible (> 98%) 12 bp oligomers appear in vertebrate genomes while < 2% of 19 bp oligomers are present. Other species showed different ranges of > 98% to < 2% of possible oligomers in D. melanogaster (12–17 bp), C. elegans (11–17 bp), A. thaliana (11–17 bp), S. cerevisiae (10–16 bp) and E. coli (9–15 bp). Frequencies of unique oligomers in the genomes follow similar patterns. We identified a set of 2.6 M 15-mers that are more than 1 nucleotide different from all 15-mers in the human genome and so could be used as probes to detect microbes in human samples. In a human sample, these probes would detect 100% of the 433 currently fully sequenced prokaryotes and 75% of the 3065 fully sequenced viruses. The human genome is significantly more compact in sequence space than a random genome. We identified the most frequent 5- to 20-mers in the human genome, which may prove useful as PCR primers. We also identified a bacterium, Anaeromyxobacter dehalogenans, which has an exceptionally low diversity of oligomers given the size of its genome and its GC content. The entropy of coding regions in the human genome is significantly higher than non-coding regions and chromosomes. However chromosomes 1, 2, 9, 12 and 14 have a relatively high proportion of coding DNA without high entropy, and chromosome 20 is the opposite with a low frequency of coding regions but relatively high entropy.Measures of the frequency of oligomers are useful for designing PCR assays and for identifying chromosomes and organisms with hidden structure that had not been previously recognized. This information may be used to detect novel microbes in human tissues.The discovery of the structure of DNA [1] was a fundamental event in biology because it illuminated the mechanism by which
Optimal Patching in Clustered Malware Epidemics
Soheil Eshghi,MHR. Khouzani,Saswati Sarkar,Santosh S. Venkatesh
Mathematics , 2014,
Abstract: Studies on the propagation of malware in mobile networks have revealed that the spread of malware can be highly inhomogeneous. Platform diversity, contact list utilization by the malware, clustering in the network structure, etc. can also lead to differing spreading rates. In this paper, a general formal framework is proposed for leveraging such heterogeneity to derive optimal patching policies that attain the minimum aggregate cost due to the spread of malware and the surcharge of patching. Using Pontryagin's Maximum Principle for a stratified epidemic model, it is analytically proven that in the mean-field deterministic regime, optimal patch disseminations are simple single-threshold policies. Through numerical simulations, the behavior of optimal patching policies is investigated in sample topologies and their advantages are demonstrated.
Optimal Energy-Aware Epidemic Routing in DTNs
Soheil Eshghi,MHR. Khouzani,Saswati Sarkar,Ness B. Shroff,Santosh S. Venkatesh
Mathematics , 2014,
Abstract: In this work, we investigate the use of epidemic routing in energy constrained Delay Tolerant Networks (DTNs). In epidemic routing, messages are relayed by intermediate nodes at contact opportunities, i.e., when pairs of nodes come within the transmission range of each other. Each node needs to decide whether to forward its message upon contact with a new node based on its own residual energy level and the age of that message. We mathematically characterize the fundamental trade-off between energy conservation and a measure of Quality of Service as a dynamic energy-dependent optimal control problem. We prove that in the mean-field regime, the optimal dynamic forwarding decisions follow simple threshold-based structures in which the forwarding threshold for each node depends on its current remaining energy. We then characterize the nature of this dependence. Our simulations reveal that the optimal dynamic policy significantly outperforms heuristics.
Development and Installation of High Pressure Boilers for Co-Generation Plant in Sugar Industries  [PDF]
Kolar Seenappa Venkatesh, Aashis S. Roy
Smart Grid and Renewable Energy (SGRE) , 2010, DOI: 10.4236/sgre.2010.11008
Abstract: The sugar cane containing minimum 30% fiber was referred as bagasse and used the generation of power required for the operation of sugar mill. The bagasse is fired in the boiler for producing steam at high pressure, which is extracted through various single high capacity turbines and used in the process. The installation of high pressure boilers and high pressure turbo-generators has provision for the operation of co-generation plant during the off-season also that enhances the power generation from 9MW to 23MW. The annual monetary benefits achieved are Rs. 204.13 million and this was based on cost of power sold to the grid @ Rs 2.548 per unit, sugar season of 219 days and off season of 52 days. This required an investment of Rs 820.6 million. The investment had an attractive simple payback period of 48 months.
Supracutaneous Locking Compression Plate for Grade I & II Compound Fracture Distal Tibia—A Case Series  [PDF]
S. K. Venkatesh Gupta, Shyam Prasad Parimala
Open Journal of Orthopedics (OJO) , 2013, DOI: 10.4236/ojo.2013.32021

Background: Supracutaneous plating using a locking compression plate (LCP) as an external fixator in compound periarticular areas is facilitated by the development of anatomical plates. The soft tissue around the distal tibia is easily compromised by trauma and subsequent operative fracture treatment posing a definitive challenge in the distal tibia compound fractures. The purpose of this report is to describe our successful results using the metaphyseal locking compression plate (LCP) as an external fixator in the treatment of Grade I & II compound fractures of distal tibia. Methodology: A total of five (05) patients underwent “supracutaneous plating” of the tibia using a metaphyseal locking compression plate. Average age was 36 years. Regular screw tract dressings were done. Average period of follow-up was 15 months. Results: The plate was in situ for an average of 24 weeks. There were no clinically significant screw site infections. In all five patients the plate was kept in place until there was complete consolidation both clinically and radiologically. At the latest follow-up (average 15 months), all patients were fully weight bearing with a fully healed tibia. All patients were infection-free with well-healed wounds. Conclusion: Routinely, after initial debridement and temporary bony stabilization is provided by external fixation in compound fractures of the distal tibia with significant soft tissue injury. Most external frames for the lower leg are bulky and cumbersome, causing significant problems for the patient. To circumvent these issues, we have successfully used an anatomically-contoured supracutaneous metaphyseal locking compression plate as external fixator in a series of five patients for grade I & II compound fracture of the distal tibia.

Management of Tibial Metaphyseal Fractures by Hybrid External Fixator  [PDF]
S. K. Venkatesh Gupta, Gottipati Sunil
Open Journal of Orthopedics (OJO) , 2014, DOI: 10.4236/ojo.2014.43014
Abstract: Introduction: The Hybrid External Fixator combines the advantages of the monolateral pin fixators and the circular Ilizarov wire fixators. Principle of early motion has been touted as the functional savior of major intra articular injuries in application of hybrid external fixation. Materials & Methodology: 48 patients were considered for the study with tibial fractures admitted in Mamata General Hospital from May 2011 to May 2013. Results: The union and functional outcome of hybrid external fixator in simple and complex proximal and distal metaphyseal fractures of tibia in adults was evaluated at our centre. The fractures of the proximal tibia united with an average of 13.3 weeks (12 - 16 weeks). The fractures of the distal tibia united with an average of 14.42 weeks (13 - 22 weeks) with minimal complications. Conclusion: Our study shows high satisfaction rate after fixation, provides adequate stability and allows early motion of the joint. It is also effective in extra articular fractures occurring within 5 cm of the joint as the IM nails often do not provide enough stability and plating requires extensive soft tissue dissection.
Is Ultrasound Effective in Diagnosing Internal Derangements of the Knee?  [PDF]
S. K. Venkatesh Gupta, Sugnanam Sirish Aditya
Open Journal of Orthopedics (OJO) , 2013, DOI: 10.4236/ojo.2013.38059

Internal derangement of knee significantly affects daily activities of patients and management of such cases with accurate diagnosis and early treatment is of utmost importance. This study determines the benefits of arthroscopy directly and also compares the sensitivity and specificity of ultrasound, MRI and arthroscopic findings in diagnosing internal derangements of the knee. This is a prospective study of 50 cases that includes patients having knee pain and instability of joint for more than 6 weeks, symptoms of locking of knee joint or effusion and having no bony injury as confirmed by X ray. Results were analysed and sensitivity and specificity were calculated. The present study supports that the clinical diagnosis is of primary necessity, while ultrasound and MRI are additional diagnostic tools in diagnosing IDK. Arthroscopy combines more accurate diagnosing tool and therapeutic modality, which is a more convenient, economical and convincing technique to both surgeon and patient alike. Although ultrasound is less accurate than MRI, it is cost effective and available at most of the peripheral centres. So it is better to do ultrasound rather than MRI for diagnosing IDK in peripheral centres and refer to specialty clinics or tertiary centres for further diagnosis and treatment.


A Case Series of Various Swelling of Fingers in Adults  [PDF]
S. K. Venkatesh Gupta, Srujith Kommera
Open Journal of Orthopedics (OJO) , 2014, DOI: 10.4236/ojo.2014.412052
Abstract: Patients commonly present to their general practitioner with swellings of the hand. These include a variety of diagnoses with certain lesions (for example, ganglion) being more common than others. Some may even be familiar as they are often site-specific. This article aims to provide general practitioners with clear and concise information regarding swellings to be ruled out before suspecting giant cell tumor of tendon sheath. Swellings of the hand are commonly encountered in a general practice with different diagnosis. They may arise from any tissue in the hand including skin, subcutaneous fat, muscle, nerves, vessels, tendon, bone and cartilage. Fortunately, most are benign, asymptomatic and may not require surgical intervention. Ganglions, epidermoid inclusion cysts, giant cell tumours of the tendon sheath, and swellings associated with arthropathy comprise the majority of lesion. This study includes 16 cases which are presented with similar history and presentation of finger swellings as that of giant cell tumor tendon sheath but the final diagnosis has varied.
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