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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 login-id 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. [ABSTRACT FROM AUTHOR]

For critical applications, real-time data access is essential from the nodes inside a wireless sensor network (WSN). Only the authorized users with unique access privilege should access the specific, but not all, sensing information gathered by the cluster heads in a hierarchical WSNs. Access rights for the correct information and resources for different services from the cluster heads to the genuine users can be provided with the help of efficient user access control mechanisms. In this paper, we propose a new user access control scheme with attribute-based encryption using elliptic curve cryptography in hierarchical WSNs. In attribute-based encryption, the ciphertexts are labeled with sets of attributes and secret keys of the users that are associated with their own access structures. The authorized users with the relevant set of attributes can able to decrypt the encrypted message coming from the cluster heads. Our scheme provides high security. Moreover, our scheme is efficient as compared with those for other existing user access control schemes. Through both the formal and informal security analysis, we show that our scheme has the ability to tolerate different known attacks required for a user access control designed for WSNs. Furthermore, 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 demonstrate that our scheme is secure. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Recently, Huang proposed a new access control scheme based on elliptic curve cryptosystem which prevents malicious nodes from joining the sensor network. This scheme uses the expiration time of nodes so that the nodes can only authenticate with its neighbor nodes within that time. In this paper, we first show that though this scheme is efficient, but it has a fatal weakness such as it is vulnerable to an active attack known as man-in-the-middle attack. In order to remedy that weakness we propose a more efficient and secure access control scheme as compared with Huang's scheme. Further, our scheme is significantly better in terms of performance and security compared with other related access control schemes. In fact, our scheme requires significantly less communication costs as compared to other related schemes. Moreover, we simulate our scheme for formal security analysis using the AVISPA (Automated Validation of Internet Security Protocols and Applications) tool and show that our scheme is secure. [ABSTRACT FROM AUTHOR]

In an access control scheme, a deployed sensor node proves its identity to its neighbor nodes through authentication and also proves that it has the proper right to access the sensor network. After successful authentication, the shared secret keys should be established between a deployed sensor node and its neighbor nodes to protect communications. In a wireless sensor network, we often require deployment of new nodes to extend the lifetime of the network because sensor network may be lost due to power exhaustion problem or malicious nodes. In order to protect malicious nodes from joining the sensor network, access control mechanism becomes a major challenge in the design of sensor network protocols due to resource limitations of sensor nodes. Until now, there have been ample of access control schemes published in the literature, and each published scheme has its own merits and demerits. In this paper, we have identified all the functionality features and security requirements which must be satisfied for an ideal access control scheme. We have presented and discussed the recently proposed access control schemes available so far in the literature and their cryptanalysis. We have critically analyzed the storage, communication, computational overheads requirement, functionality and security analysis of the existing schemes. Further, we have performed formal security analysis of existing schemes using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool. All the schemes are vulnerable to different attacks except the Zhou et al.'s scheme and the Chatterjee et al.'s scheme. However, the Zhou et al.'s scheme requires high storage, communication and computational costs. Hence, we feel that there is a strong need to design an ideal efficient access control scheme in future, which should meet all the security requirements and achieve all the functionality features. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) simulation involves solving Newton's equations of motion for a system of atoms, by calculating forces and updating atomic positions and velocities over a timestep Δt. Despite the large amount of computing power currently available, the timescale of MD simulations is limited by both the small timestep required for propagation, and the expensive algorithm for computing pairwise forces. These issues are currently addressed through the development of efficient simulation methods, some of which make acceptable approximations and as a result can afford larger timesteps. We present MDLab, a development environment for MD simulations built with Python which facilitates prototyping, testing, and debugging of these methods. MDLab provides constructs which allow the development of propagators, force calculators, and high level sampling protocols that run several instances of molecular dynamics. For computationally demanding sampling protocols which require testing on large biomolecules, MDL includes an interface to the OpenMM libraries of Friedrichs et al. which execute on graphical processing units (GPUs) and achieve considerable speedup over execution on the CPU. As an example of an interesting high level method developed in MDLab, we present a parallel implementation of the On-The-Fly string method of Maragliano and Vanden-Eijnden. MDLab is available at http://mdlab.sourceforge.net. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [ABSTRACT FROM AUTHOR]

Background: Recent epidemiologic data on travelers' diarrhea (TD) are essential for the evaluation of conventional and future prophylactic and therapeutic measures.Methods: To determine the epidemiology, including risk factors, impact and quality-of-life evaluation of TD, a cross-sectional survey was conducted over 12 months at the airports of Mombasa (Kenya), Goa (India), Montego Bay (Jamaica) and Fortaleza (Brazil) by distributing questionnaires to visitors just prior to their flying home. The study period was March 1996 to July 1998.Results: Overall, 73,630 short-term visitors completed a questionnaire. The total diarrhea attack rate varied between a high of 54.6% in Mombasa and a low of 13.6% in Fortaleza, but only between 31.5% and 5.4% of all travelers had classic TD. The 14-day incidence rates varied between 19.5% and 65.7%. Few travelers meticulously avoided potentially dangerous food items, although in India and Kenya most travelers avoided those considered most dangerous. Risk factors were stays exceeding 1 week, age between 15 and 30 years, and residence in the UK. The impact, measured as incapacity or quality-of-life scores, was very considerable.Conclusions: TD continues to affect vacationers and business travelers as frequently as it did some 20 years ago. Compliance with recommendations to reduce exposure to pathogens by avoiding dangerous food items is poor among travelers from all countries. Implementation of food safety education programs may be difficult to achieve. [ABSTRACT FROM AUTHOR]

Prescribing habits in South Asian countries have been subjected to some scrutiny.1-6 Most studies conclude that the quality of prescribing is poor, with overuse of antimicrobials and irrational use of fixed-dose combination therapy, particularly in the private sector.1 Prescriptions for multiple drugs are the rule rather than the exception, with up to seven items being prescribed for a single disease entity. Analgesics, anti-inflammatories and drugs of uncertain pharmacologic efficacy, such as vitamins, minerals and glucose water, are also frequently prescribed. [ABSTRACT FROM AUTHOR]