Ashok Kumar Das

The National Information Security Research and Defense Institute, Washington, Washington, D.C., United States

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Publications (138)173.37 Total impact

  • Ashok Kumar Das · Sandip Das · Malay Sen
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    ABSTRACT: An interval matrix is the adjacency matrix of an interval digraph or equivalently the biadjacency matrix of an interval bigraph. In this paper we investigate the forbidden substructures of an interval bigraph. Our method finds hitherto existing forbidden substructures for interval matrices, and via a more concise statement, as well as a new example showing that these substructures are not exhaustive.
    No preview · Article · Feb 2016 · Discrete Mathematics
  • Jayakrushna Sahoo · Ashok Kumar Das · A. Goswami
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    ABSTRACT: In recent years, high utility itemsets (HUIs) mining from the transactional databases becomes one of the most emerging research topic in the field of data mining due to its wide range of applications in online e-commerce data analysis, identifying interesting patterns in biomedical data and for cross marketing solutions in retail business. It aims to discover the itemsets with high utilities efficiently by considering item quantities in a transaction and profit values of each item. However, it produces a tremendous number of HUIs, which imposes further burden in analysis of the extracted patterns and also degrades the performance of mining methods. Mining the set of closed + high utility itemsets (CHUIs) solves this issue as it is a loss-less and condensed representation of all HUIs. In this paper, we aim to present a new algorithm for finding CHUIs from a transactional database, called the CHUM (Closed + High Utility itemset Miner), which is scalable and efficient. The proposed mining algorithm adopts a tricky aimed vertical representation of the database in order to speed up the execution time in generating itemset closures and compute their utility information without accessing the database. The proposed method makes use of the item co-occurrences strategy in order to further reduce the number of intersections needed to be performed. Several experiments are conducted on various sparse and dense datasets and the simulation results clearly show the scalability and superior performance of our algorithm as compared to those for the existing state-of-the-art CHUD (Closed + High Utility itemset Discovery) algorithm.
    No preview · Article · Jan 2016 · Applied Intelligence
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    ABSTRACT: In recent years, Voice over Internet Protocol (VoIP) has gained more and more popularity as an application of the Internet technology. For various IP applications including VoIP, the topic of Session Initiation Protocol (SIP) has attracted major concern from researchers. SIP is an advanced signaling protocol operating on Internet Telephony. SIP uses digest authentication protocols such as Simple Mail Transport Protocol (SMTP) and Hyper Text Transport Protocol (HTTP). When a user seeks SIP services, authentication plays an important role in providing secure access to the server only to the authorized access seekers. Being an insecure-channel-based protocol, a SIP authentication protocol is susceptible to adversarial threats. Therefore, security is a big concern in SIP authentication mechanisms. This paper reveals the security vulnerabilities of two recently proposed SIP authentication schemes for VoIP, Irshad et al.’s scheme [Multimed. Tools. Appl. doi:10. 1007/ s11042-013-1807-z] and Arshad and Nikooghadam’s scheme [Multimed. Tools. Appl. DOI 10. 1007/ s11042-014-2282-x], the later scheme is based on the former scheme. Irshad et al.’s scheme suffers from password guessing, user impersonation and server spoofing attacks. Arshad and Nikooghadam’s scheme can be threatened with server spoofing and stolen verifier attack. None of these two schemes achieve mutual authentication. It also fails to follow the single round-trip authentication design of Irshad et al.’s scheme. To overcome these weaknesses, we propose a provable secure single round-trip SIP authentication scheme for VoIP using smart card. We formally prove the security of the scheme in random oracle and demonstrate through discussion its resistance to various attacks. The comparative analysis shows that the proposed SIP authentication scheme offers superior performance with a little extra computational cost.
    Full-text · Article · Nov 2015 · Multimedia Tools and Applications
  • Vanga Odelu · Ashok Kumar Das · Adrijit Goswami
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    ABSTRACT: With the rapid growth of the Internet, a lot of electronic patient records (EPRs) have been developed for e-medicine systems. The security and privacy issues of EPRs are important for the patients in order to understand how the hospitals control the use of their personal information, such as name, address, e-mail, medical records, etc. of a particular patient. Recently, Lee et al. proposed a simple group password-based authenticated key agreement protocol for the integrated EPR information system (SGPAKE). However, in this paper, we show that Lee et al.’s protocol is vulnerable to the off-line weak password guessing attack and as a result, their scheme does not provide users’ privacy. To withstand this security weakness found in Lee et al.’s scheme, we aim to propose an effective dynamic group password-based authenticated key exchange scheme for the integrated EPR information system, which retains the original merits of Lee et al.’s scheme. Through the informal and formal security analysis, we show that our scheme provides users’ privacy, perfect forward security and known-key security, and also protects online and offline password guessing attacks. Furthermore, our scheme efficiently supports the dynamic group password-based authenticated key agreement for the integrated EPR information system. In addition, we simulate our scheme for the formal security verification using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool and show that our scheme is secure against passive and active attacks.
    No preview · Article · Nov 2015
  • Ashok Kumar Das · Santanu Chatterjee · Jamuna Kanta Sing
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    ABSTRACT: User authentication is a primary concern in a resource constrained wireless sensor network (WSN) before accessing real-time data from the nodes inside WSN. In this paper, we propose a novel biometric-based user authentication scheme suitable for hierarchical wireless body area networks (WBANs). The proposed scheme makes use of biometric verification along with password verification, which enables any authorized user to access real-time data from any cluster head in the sensor network. The proposed scheme is light-weight because it only requires the efficient cryptographic hash function, and symmetric key encryption and decryption algorithms. The strengths of the proposed protocol are that it provides strong authentication as compared to traditional related password-based authentication schemes in WSNs and achieves some good properties such as it works without synchronized clock, it supports freely password change by the legitimate users at any time, and it provides low computation costs and mutual authentication. In addition, the proposed scheme provides unconditional security against node capture attack and also prevents other attacks such as denial-of-service attack, stolen-verifier attack, many logged-in users with the same loginid attack, masquerade attack, replay attack, privileged-insider attack, smart card breach attack, and man-in-the-middle attack. Through the formal security verification using AVISPA (Automated Validation of Internet Security Protocols and Applications) tool we show that our scheme is secure against passive and active attacks. Furthermore, the formal security analysis under the random oracle models proves that our scheme is provably secure against different known attacks.
    No preview · Article · Sep 2015 · Ad Hoc & Sensor Wireless Networks
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    ABSTRACT: Background & objectives: Overweight and obesity are rapidly increasing in countries like India. This study was aimed at determining the prevalence of generalized, abdominal and combined obesity in urban and rural India. Methods: Phase I of the ICMR-INDIAB study was conducted in a representative population of three s0 tates [Tamil Nadu (TN), Maharashtra (MH) and Jharkhand (JH)] and one Union Territory (UT)[Chandigarh (CH)] of India. A stratified multi-stage sampling design was adopted and individuals ≥20 yr of age were included. WHO Asia Pacific guidelines were used to define overweight [body mass index (BMI) ≥23 kg/m [2] but <25 kg/m [2]], generalized obesity (GO, BMI≥25kg/m [2] , abdominal obesity (AO, waist circumference ≥90 cm for men and ≥80cm for women) and combined obesity (CO, GO plus AO). Of the 14,277 participants, 13,800 subjects (response rate, 96.7%) were included for the analysis (urban: n=4,063; rural: n=9737). Results: The prevalence of GO was 24.6, 16.6, 11.8 and 31.3 per cent among residents of TN, MH, JH and CH, while the prevalence of AO was 26.6, 18.7, 16.9 and 36.1 per cent, respectively. CO was present in 19.3, 13.0, 9.8 and 26.6 per cent of the TN, MH, JH and CH population. The prevalence of GO, AO and CO were significantly higher among urban residents compared to rural residents in all the four regions studied. The prevalence of overweight was 15.2, 11.3, 7.8 and 15.9 per cent among residents of TN, MH, JH and CH, respectively. Multiple logistic regression analysis showed that female gender, hypertension, diabetes, higher socio-economic status, physical inactivity and urban residence were significantly associated with GO, AO and CO in all the four regions studied. Age was significantly associated with AO and CO, but not with GO. Interpretation & conclusions: Prevalence of AO as well as of GO were high in India. Extrapolated to the whole country, 135, 153 and 107 million individuals will have GO, AO and CO, respectively. However, these figures have been estimated from three States and one UT of India and the results may be viewed in this light.
    No preview · Article · Sep 2015 · The Indian Journal of Medical Research
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    ABSTRACT: Background: With prevalence of diabetes in India reaching epidemic proportions and increase in the population of geriatric age group and risks of falls, it is important to understand the effect that diabetes has on bone health. Aim: The objective was to assess bone mineral density (BMD) of patients with type 2 diabetes mellitus (T2DM) and to study factors contributing to BMD in patients with T2DM. Materials and Methods: This was a prospective cross-sectional study on 150 patients with T2DM (diagnosed at age > 30 years) and an equal number (n=150) of age and sex matched healthy controls from September 2012 to July 2014 at a tertiary care center located in Southern India.BMD was measured at the femoral neck and lumbar spine (L2–L4) by dual energy absorptiometry (DXA) in cases and controls. Serum total calcium, phosphorus and alkaline phosphatase (ALP) and 25-OH- vitamin D3 was measured in patient group. Results: Mean age (SD) was 51.29 (±8.05) and 51 (±8.3) years in cases and controls, respectively. The femoral neck and lumbar spine BMD was significantly lower in T2DM cases compared to controls. Also the femoral neck and lumbar spine T-score was significantly lower in T2DM cases compared to controls. Femoral neck BMD among male patients with T2DM was significantly lower compared to controls (men). Among women, BMD at femoral neck as well as lumbar spine was significantly lower in cases when compared to controls. Ninety six out of 150 (64%) T2DM cases had Vitamin D values <20 ng/mL. There was weak negative correlation between age of patient, duration of diabetes and HbA1C with femoral neck BMD. There was weak negative correlation between HbA1C and lumbar spine BMD. Conclusion: Indian subjects with type 2 diabetes have significantly lower BMD at both femoral neck and lumbar spine compared to age and sex matched healthy controls. We conclude that osteopenia and osteoporosis are overlooked complications of diabetes. Longitudinal studies are needed to see for actual incidence of fractures among this high risk group. © 2015,Journal of Clinical and Diagnostic Research. All rights reserved.
    No preview · Article · Sep 2015 · Journal of Clinical and Diagnostic Research
  • Ashok Kumar Das · Vanga Odelu · Adrijit Goswami
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    ABSTRACT: The telecare medicine information system (TMIS) helps the patients to gain the health monitoring facility at home and access medical services over the Internet of mobile networks. Recently, Amin and Biswas presented a smart card based user authentication and key agreement security protocol usable for TMIS system using the cryptographic one-way hash function and biohashing function, and claimed that their scheme is secure against all possible attacks. Though their scheme is efficient due to usage of one-way hash function, we show that their scheme has several security pitfalls and design flaws, such as (1) it fails to protect privileged-insider attack, (2) it fails to protect strong replay attack, (3) it fails to protect strong man-in-the-middle attack, (4) it has design flaw in user registration phase, (5) it has design flaw in login phase, (6) it has design flaw in password change phase, (7) it lacks of supporting biometric update phase, and (8) it has flaws in formal security analysis. In order to withstand these security pitfalls and design flaws, we aim to propose a secure and robust user authenticated key agreement scheme for the hierarchical multi-server environment suitable in TMIS using the cryptographic one-way hash function and fuzzy extractor. Through the rigorous security analysis including the formal security analysis using the widely-accepted Burrows-Abadi-Needham (BAN) logic, the formal security analysis under the random oracle model and the informal security analysis, we show that our scheme is secure against possible known attacks. Furthermore, we simulate our scheme using the most-widely accepted and used Automated Validation of Internet Security Protocols and Applications (AVISPA) tool. The simulation results show that our scheme is also secure. Our scheme is more efficient in computation and communication as compared to Amin-Biswas's scheme and other related schemes. In addition, our scheme supports extra functionality features as compared to other related schemes. As a result, our scheme is very appropriate for practical applications in TMIS.
    No preview · Article · Sep 2015 · Journal of Medical Systems
  • Vanga Odelu · Ashok Kumar Das · Adrijit Goswami
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    ABSTRACT: Recently, in 2014, He and Wang proposed a robust and efficient multi-server authentication scheme using biometrics-based smart card and elliptic curve cryptography (ECC). In this paper, we first analyze He-Wang’s scheme and show that their scheme is vulnerable to a known session-specific temporary information attack and impersonation attack. In addition, we show that their scheme does not provide strong user’s anonymity. Furthermore, He-Wang’s scheme cannot provide the user revocation facility when the smart card is lost/stolen or user’s authentication parameter is revealed. Apart from these, He- Wang’s scheme has some design flaws, such as wrong password login and its consequences, and wrong password update during password change phase. We then propose a new secure multiserver authentication protocol using biometric-based smart card and ECC with more security functionalities. Using the Burrows- Abadi-Needham (BAN) logic, we show that our scheme provides secure authentication. In addition, we simulate our scheme for the formal security verification using the widely-accepted and used AVISPA (Automated Validation of Internet Security Protocols and Applications) tool, and show that our scheme is secure against passive and active attacks. Our scheme provides high security along with low communication cost, computational cost, and variety of security features. As a result, our scheme is very suitable for battery-limited mobile devices as compared to He- Wang’s scheme.
    No preview · Article · Sep 2015 · IEEE Transactions on Information Forensics and Security
  • Vanga Odelu · Ashok Kumar Das · Adrijit Goswami
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    ABSTRACT: In communication systems, authentication protocols play an important role in protecting sensitive information against a malicious adversary by means of providing a variety of services such as mutual authentication, user credentials' privacy, and user revocation facility when the smart card of the user is lost/stolen or user's authentication parameters are revealed. Recently, several three-party authentication with key agreement (3PAKA) schemes are proposed in the literature, but most of them do not provide the basic security requirements such as user anonymity as well as user revocation and re-registration with the same identity. Thus, we feel that there is a great need to design a secure 3PAKA scheme with these security properties. In this paper, we propose a new secure biometric-based privacy-preserving 3PAKA scheme using the elliptic curve cryptography with efficient mechanism for the user revocation and re-registration with the same identity. The formal security analysis using the widely accepted Burrows–Abadi–Needham logic shows that our scheme provides secure authentication. In addition, we simulate our scheme for the formal security verification using the widely accepted Automated Validation of Internet Security Protocols and Applications tool. The simulation results show that our scheme is secure against passive and active attacks. Furthermore, our scheme is efficient as compared with other related schemes. Our scheme provides high security along with low computation and communication costs, and extra features as compared with other related existing schemes in the literature, and as a result, our scheme is suitable for battery-limited mobile devices. Copyright © 2015 John Wiley & Sons, Ltd.
    No preview · Article · Aug 2015 · Security and Communication Networks
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    ABSTRACT: Objectives: To find the prevalence of metabolic syndrome in systemic lupus erythematosus (SLE) compared to controls and to identify association of metabolic syndrome with SLE disease activity and damage. Methods: A total of 82 SLE and 82 healthy controls were studied. Metabolic syndrome was defined by National Cholesterol Education Program-Adult Treatment Panel III (NCEP ATP III), consensus definition for Asian Indian Adults and World Health Organisation (WHO) 1999 definition, and associations with lupus characteristics, disease activity, and damage were examined. Insulin resistance (IR) was estimated using the homeostasis model assessment for IR (HOMA-IR). Results: Metabolic syndrome was present in 24.39% SLE and 12.19% controls (p <. 0.04) by NCEP ATP III criteria; 29.26% SLE and 19.51% controls (p = 0.14) by consensus definition for Asian Indians; 18.2% SLE and 7.31% controls (p <. 0.035) by WHO 1999 criteria.Hypertension and hypertriglyceridemia were more frequent in SLE than in controls. Mean body mass index, diastolic and systolic blood pressure, triglycerides, and total cholesterol were higher in SLE than in controls. HOMA-IR (median, range) was 1.31 (0.06-9.32) and 1.55 (0.01-7.92), p = 0.09 in SLE and controls, respectively. There was no association of metabolic syndrome with disease activity/damage and prednisolone use. SLE patients with metabolic syndrome had a significantly longer duration of disease compared to patients without metabolic syndrome. Conclusion: South Indian SLE patients have higher prevalence of NCEP ATP III and WHO defined metabolic syndrome compared to healthy controls. SLE patients have an altered lipid profile, but there was no IR and no association of metabolic syndrome with disease activity or damage.
    No preview · Article · Aug 2015 · Indian Journal of Rheumatology
  • Jayakrushna Sahoo · Ashok Kumar Das · A. Goswami
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    ABSTRACT: Traditional association rule mining based on the support–confidence framework provides the objective measure of the rules that are of interest to users. However, it does not reflect the semantic measure among the items. The semantic measure of an itemset is characterized with utility values that are typically associated with transaction items, where a user will be interested to an itemset only if it satisfies a given utility constraint. In this paper, we first define the problem of finding association rules using utility-confidence framework, which is a generalization of the amount-confidence measure. Using this semantic concept of rules, we then propose a compressed representation for association rules having minimal antecedent and maximal consequent. This representation is generated with the help of high utility closed itemsets (HUCI) and their generators. We propose the algorithms to generate the utility based non-redundant association rules and methods for reconstructing all association rules. Furthermore, we describe the algorithms which generate high utility itemsets (HUI) and high utility closed itemsets with their generators. These proposed algorithms are implemented using both synthetic and real datasets. The results demonstrate better efficiency and effectiveness of the proposed HUCI-Miner algorithm compared to other well-known existing algorithms. In addition, the experimental results show better quality in the compressed representation of the entire rule set under the considered framework.
    No preview · Article · Aug 2015 · Expert Systems with Applications
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    Ashok Kumar Das · C. Retna Raj
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    ABSTRACT: An electrochemical route for the decoration of multiwalled carbon nanotubes (MWCNTs) with anisotropic Au nanostructures and the electroanalytical application of decorated MWCNTs are described. MWCNTs were electrochemically decorated with flowers and buds-like Au nanostructures in aqueous solution in the presence of KI. The flowers and buds-like nanostructures had an average size of 80 nm with a predominant Au(111) plane. The analytical application of the decorated MWCNTs in the electroanalysis of biologically important analytes, such as uric acid (UA), epinephrine (EN) and ascorbic acid (AA), was studied. The nanoparticles of flower-like morphology efficiently catalyze the oxidation of the bioanalytes at a less-positive potential. Simultaneous electroanalysis of AA, UA and EN have been achieved. Well separated individual voltammetric peaks were obtained in their coexistence. The decorated MWCNT modified electrode is very stable and highly sensitive towards UA and EN. It could detect micromolar levels of bioanalytes without any interference. The catalytic property of the nanostructures is superior to that of the conventional spherical nanoparticle. The morphology of the nanoparticle controls the electrocatalytic activity.
    Full-text · Article · Jul 2015 · Analytical Sciences
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    ABSTRACT: Authentication schemes present a user-friendly and scalable mechanism to establish the secure and authorized communication between the remote entities over the insecure public network. Later, several authentication schemes have proposed in the literature. However, most of the existing schemes do not satisfy the desirable attributes, such as resistance against known attacks and user anonymity. In 2012, Chen et al. designed a robust authentication scheme to erase the weaknesses of Sood et al.'s scheme. In 2013, Jiang et al. showed that Chen et al.'s scheme is vulnerable to password guessing attack. Furthermore, Jiang et al. presented an efficient solution to overcome the shortcoming of Chen et al.'s scheme. We demonstrate that Jiang et al.'s scheme does not withstand insider attack, on-line and off-line password guessing attacks, and user impersonation attack. Their scheme also fails to provide user's anonymity. To overcome these drawbacks, we aim to propose an enhanced scheme, which reduces the computation overhead and satisfies all desirable security attributes, while retaining the original merits of Jiang et al.'s scheme. The proposed scheme is also comparable in terms of the communication and computational overheads with Jiang et al.'s scheme and other existing schemes. Furthermore, we simulate the enhanced scheme for the formal security analysis utilizing the widely-accepted AVISPA tool and show that the proposed scheme is resistant against active and passive attacks.
    No preview · Article · Jul 2015
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    Ashok Kumar Das · Ritapa Chakraborty
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    ABSTRACT: A proper interval bigraph is a bigraph where to each vertex we can assign a closed interval such that the intervals can be chosen to be inclusion free and vertices in the opposite partite sets are adjacent when the corresponding intervals intersect. In this paper, we introduce the notion of astral triple of edges and along the lines of characterization of interval graphs via the absence of asteroidal triple of vertices we characterize proper interval bigraphs via the absence of astral triple of edges. We also characterize proper interval bigraphs in terms of dominating pair of vertices as defined by Corneil et al. Tucker characterized proper circular arc graphs in terms of circularly compatible 1’s of adjacency matrices. Sen and Sanyal characterized adjacency matrices of proper interval bigraphs in terms of monotone consecutive arrangement. We have shown an interrelation between these two concepts.
    Preview · Article · Jul 2015 · AKCE International Journal of Graphs and Combinatorics
  • Vanga Odelu · Ashok Kumar Das · Adrijit Goswami
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    ABSTRACT: Recently, in 2013, Wu et al. proposed an efficient adaptable and scalable group access control scheme (GAC) for managing wireless sensor networks and they claimed that their proposed GAC approach provides the forward secrecy and backward secrecy, and it also prevents the man-in-the-middle attack. However, in this paper, we revisit Wu et al.’s scheme and show that Wu et al.’s scheme fails to provide the forward and backward secrecy to the group access key (GAK), and also their scheme does not prevent the man-in-the-middle attack and it does not provide the mutual authentication between a node and the task manager. Moreover, in Wu et al.’s scheme, all the past GAKs used by a node can be revealed to an adversary when that node is compromised. We then aim to propose a novel group access control mechanism to withstand the security weaknesses found in Wu et al.’s scheme while retaining the original merits of their scheme. Through the rigorous informal security analysis and the formal security analysis using the widely-accepted Burrows–Abadi–Needham logic, we show that our scheme is secure against various known attacks including the attacks found in Wu et al.’s scheme. Moreover, in our scheme, the vulnerability of the GAKs used by a node is limited and bounded to the last GAK update protocol interval when that node is compromised by an adversary. Our scheme provides efficient dynamic properties such as joining and leaving of a node from a group along with high security and the required desirable features as compared to Wu et al.’s scheme, and as a result, our scheme is very suitable for the practical applications.
    No preview · Article · Jun 2015 · Wireless Personal Communications
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    ABSTRACT: The survival of patients with hypopharyngeal cancer is low amongst head and neck cancer cases. The incidence rates of hypopharyngeal cancers in our population are amongst the highest in the world and there are limited data available on the literature on varied responses to first course of treatment with radiotherapy (RT) and concurrent chemo-radiotherapy (CRT) in our population. Clinical characteristics and initial responses to treatment in patients who had received radiotherapy and chemo-radiotherapy in a regional cancer center from January 2010 to December 2013 were evaluated. The data were obtained from the hospital cancer registry, and analysis was carried using descriptive statistics. Pearson's chi-square was used to test for differences in the variables and p<0.05 was considered statistically significant. A total of 554 patients were included in the analysis, 411 (74.2%) receiving RT and 143 (25.8%) being given CRT. There was significantly lower number of patients above 70 years with a higher proportion of patients below 50 years who had received CRT (p<0.05). Some 79.3% and 84.6% of patients in the RT and CRT groups respectively presented with a favorable performance status, and in the RT group 240 (58.4%) showed complete response (CR), and in the CRT group 103 (72.0%) showed CR at the first follow-up (p<0.05). Concurrent chemo-radiotherapy gives better short term response to treatment in locally advanced hypopharyngeal cancers.
    Full-text · Article · Jun 2015 · Asian Pacific journal of cancer prevention: APJCP
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    ABSTRACT: Patient delay can contribute to a poor outcome in the management of head and neck cancers (HNC). The main objective of the present study was to investigate the factors associated with patient delay in our population. Patients with cancers of the head and neck attending a regional cancer center of North East India were consecutively interviewed during the period from June 2014 to November 2014. The participation of patients was voluntary. The questionnaire included information on age, gender, residential status, educational qualification, monthly family income, any family history of cancer, and history of prior awareness on cancer from television (TV) program and awareness program. Of 311 (n) patients, with an age range of 14-88 years (mean 55.4 years), 81.7% were males and 18.3% females (M:F=4.4). The overall median delay was 90 days (range=7 days-365 days), in illiterate patients the median delay was 90 days and 60 days in literate patients (P=0.002), the median delay in patients who had watched cancer awareness program on TV was 60 days and in patients who were unaware about cancer information from TV program had a median delay of 90 days (p=0.00021) and delay of <10 weeks was seen in 139 (44.6%) patients, a delay of 10-20 weeks in 98 (31.5%) patients, and a delay of 20-30 weeks in 63 (20.2%) patients. Education and awareness had a significant impact in reduction of median patient delay in our HNC cases.
    Full-text · Article · Jun 2015 · Asian Pacific journal of cancer prevention: APJCP
  • Ashok Kumar Das
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    ABSTRACT: Critical applications in wireless sensor network (WSN) are real-time based applications. Therefore, users are generally interested in accessing real-time information. This is possible, if the users (called the external parties) are allowed to access the real-time data directly from the sensor nodes inside WSN and not from the base station. The sensory information from nodes are gathered periodically by the base station and so, the gathered information may not be real-time. In order to get the real-time information from the sensor nodes, the user needs to be first authorized to the sensor nodes as well as the base station so that the illegal access to nodes do not happen. In this paper, we propose a novel three-factor user authentication scheme suited for distributed WSNs. Our scheme is light-weight, because it only requires the efficient cryptographic hash function, and symmetric key encryption and decryption operations. Further, our scheme is secure against different known attacks which are proved through the rigorous informal and formal security analysis. In addition, we simulate our scheme for the formal security verification using Automated Validation of Internet Security Protocols and Applications tool. The simulation results clearly demonstrate that our scheme is secure against passive and active adversaries.
    No preview · Article · Jun 2015 · Wireless Personal Communications
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    D. R. Pattanaik · Ashok Kumar Das
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    ABSTRACT: The present study is focused to see the performance of real-time extended range forecast (2–3 week forecast) of monsoon during the 2011 flood event over the eastern state of Odisha in India. The usefulness of such forecast in the management of reservoir flow in a way to reduce the risk of flood conditions is also discussed. This case study is carried out over the Mahanadi River basin situated in eastern region of India, which witnessed severe flood conditions during the late August and early part of September 2011 due to abnormally high rainfall over the Mahanadi River basins leading to simultaneous release of huge volume of water from the Hirakud reservoir. The forecasts are prepared based on the Bi-model average (BMA) of two coupled model outputs viz., the European Centre for Medium-Range Weather Forecasting (ECMWF) monthly forecast model and the National Centre for Environmental Prediction (NCEP) Climate Forecast System (CFS) coupled model. The synoptic analysis of the observed rainfall patterns demonstrated that the heavy rainfall is associated with active monsoon circulation during late August and early September, 2011 with the presence of low-pressure systems and anomalous cyclonic circulations at lower level. The extended range BMA forecast based on the initial condition of 25 August, 2011 valid for week 1 (days 5–11) and week 2 (days 12–18) indicate strong monsoon conditions associated with heavy rainfall over the Mahanadi River basins during the period from 29 August to 11 September 2011. With respect to individual model, the ECMWF model is better compared to NCEP CFS in capturing this rainfall episode, although it is much less compared to observed rainfall departure during the period. A mechanism to use such climate forecast along with the use of latest climatological information in the decision making process will be very useful for effective management of reservoir operation particularly during this difficult period.
    Full-text · Article · Jun 2015 · Natural Hazards

Publication Stats

830 Citations
173.37 Total Impact Points

Institutions

  • 2016
    • The National Information Security Research and Defense Institute
      Washington, Washington, D.C., United States
  • 2015-2016
    • University of Calcutta
      • Department of Pure Mathematics
      Kolkata, West Bengal, India
    • Pondicherry Institute of Medical Sciences
      Pondichéry, Pondicherry, India
    • India Meteorological Department
      New Dilli, NCT, India
  • 2014-2015
    • Chonbuk National University
      • Department of Polymer Nano Science & Technology
      Tsiuentcheou, Jeollabuk-do, South Korea
    • Kalinga Institute of Medical Sciences
      Bhubaneswar, Odisha, India
  • 2011-2015
    • International Institute of Information Technology
      Poona, Maharashtra, India
    • International Institute of Information Technology, Bhubaneswar
      • Department of Computer Science and Engineering
      Bhubaneswar, Orissa, India
    • Barasat Government College
      Bārāsat, Bengal, India
    • Dr. B. Borooah Cancer Institute
      Gauhāti, Assam, India
  • 2010-2015
    • International Institute of Information Technology, Hyderabad
      Bhaganagar, Telangana, India
    • Jothydev's Diabetes and Research Center
      Thrissur, Kerala, India
  • 1986-2015
    • Jawaharlal Institute of Postgraduate Medical Education & Research
      • • Department of Endocrinolgy
      • • Department of Medicine
      • • Department of Pharmacology
      Pondichéry, Pondicherry, India
  • 2013-2014
    • Utkal University
      Bhubaneswar, Odisha, India
  • 2011-2014
    • Biomedical Informatics Centre
      Chandigarh, Chandīgarh, India
  • 2005-2014
    • IIT Kharagpur
      • • Department of Chemistry
      • • Department of Computer Science & Engineering
      Khargpur, West Bengal, India
  • 2009
    • Bhubaneswar Institute of Technology
      Bhubaneswar, Orissa, India
  • 2001
    • Indian Association for the Cultivation of Science
      Kolkata, West Bengal, India