SAFIUS - A secure and accountable filesystem over untrusted storage

We describe SAFIUS, a secure accountable file system that resides over an untrusted storage. SAFIUS provides strong security guarantees like confidentiality, integrity, prevention from rollback attacks, and accountability. SAFIUS also enables read/write sharing of data and provides the standard UNIX-like interface for applications. To achieve accountability with good performance, it uses asynchronous signatures; to reduce the space required for storing these signatures, a novel signature pruning mechanism is used. SAFIUS has been implemented on a GNU/Linux based system modifying OpenGFS. Preliminary performance studies show that SAFIUS has a tolerable overhead for providing secure storage: while it has an overhead of about 50% of OpenGFS in data intensive workloads (due to the overhead of performing encryption/decryption in software), it is comparable (or better in some cases) to OpenGFS in metadata intensive workloads.Comment: 11pt, 12 pages, 16 figure

Phase relations and gibbs energies in the system Mn-Rh-O

Phase relations in the system Mn-Rh-O are established at 1273 K by equilibrating different compositions either in evacuated quartz ampules or in pure oxygen at a pressure of 1.01 × 105 Pa. The quenched samples are examined by optical microscopy, X-ray diffraction, and energy-dispersive X-ray analysis (EDAX). The alloys and intermetaUics in the binary Mn-Rh system are found to be in equilibrium with MnO. There is only one ternary compound, MnRh204, with normal spinel structure in the system. The compound Mn304 has a tetragonal structure at 1273 K. A solid solution is formed between MnRh204 and Mn304. The solid solution has the cubic structure over a large range of composition and coexists with metallic rhodium. The partial pressure of oxygen corresponding to this two-phase equilibrium is measured as a function of the composition of the spinel solid solution and temperature. A new solid-state cell, with three separate electrode compartments, is designed to measure accurately the chemical potential of oxygen in the two-phase mixture, Rh + Mn3-2xRh2xO4, which has 1 degree of freedom at constant temperature. From the electromotive force (emf), thermodynamic mixing properties of the Mn304-MnRh204 solid solution and Gibbs energy of formation of MnRh204 are deduced. The activities exhibit negative deviations from Raoult's law for most of the composition range, except near Mn304, where a two-phase region exists. In the cubic phase, the entropy of mixing of the two Rh3+ and Mn3+ ions on the octahedral site of the spinel is ideal, and the enthalpy of mixing is positive and symmetric with respect to composition. For the formation of the spinel (sp) from component oxides with rock salt (rs) and orthorhombic (orth) structures according to the reaction, MnO (rs) + Rh203 (orth) → MnRh204 (sp), ΔG° = -49,680 + 1.56T (±500) J mol-1. The oxygen potentials corresponding to MnO + Mn304 and Rh + Rh203 equilibria are also obtained from potentiometric measurements on galvanic cells incorporating yttria-stabilized zirconia as the solid electrolyte. From these results, an oxygen potential diagram for the ternary system is developed

Energy-dependent time lags in the Seyfert 1 galaxy NGC 4593

We investigate the energy-time lag dependence of the source NGC 4593 using XMM-Newton/EPIC pn data. We found that the time lag dependency is linear in nature with respect to the logarithm of different energy bands. We also investigate the frequency-dependent time lags and identify that at some frequency range (5 x 10-5 Hz to 2 x 10-4 Hz) the X-ray emission is highly coherent, mildly frequency dependent, and very strongly energy dependent. These observations can be explained in the framework of the thermal Comptonization process, and they indicate a truncated accretion disk very close to the black hole. We discuss the plausible spectral state to explain the phenomenon and conclude that the observed properties bear a close resemblance to the intermediate state or the steep power-law state, found in galactic black hole sources

Anti-correlated hard X-ray time lags in Galactic black hole sources

We investigate the accretion disk geometry in Galactic black hole sources by measuring the time delay between soft and hard X-ray emissions. Similar to the recent discoveries of anti-correlated hard X-ray time lags in Cyg X-3 and GRS 1915+105, we find that the hard X-rays are anti-correlated with soft X-rays with a significant lag in another source: XTE J1550-564. We also find the existence of pivoting in the model independent X-ray spectrum during these observations. We investigate time-resolved X-ray spectral parameters and find that the variation in these parameters is consistent with the idea of a truncated accretion disk. The QPO frequency, which is a measure of the size of truncated accretion disk, too changes indicating that the geometric size of the hard X-ray emitting region changes along with the spectral pivoting and soft X-ray flux. Similar kind of delay is also noticed in 4U 1630-47.Comment: 14 pages, 7 figures, accepted for publication in Ap

Does E-Marketing Mix Influence Brand Loyalty and Popularity of E-Commerce Websites?

E-commerce portals are increasing exponentially in terms of both business and data. Many organizations rely on their online websites to attract new customers, while still retaining their existing ones. E-commerce websites provide consumers with flexibility in terms of time, price, and space, during their purchases. The traditional marketing mix comprising of product, price, place and promotion (4Ps) identifies important factors in a purchase journey. In the online environment the concept of the marketing mix remains the same, except that the characteristics and functions of each factor are dynamic, suiting the online marketplace. The e-marketing mix, namely e-product, price intelligence (price sensitivity), delivery risk (place) and promotional intelligence, influences consumer buying-decisions in online markets. This research is an attempt to find the effect of the e-marketing mix on the loyalty and popularity of e-commerce sites. Data was collected using a structured questionnaire and was analyzed using a structural equation modeling-partial least squares method. The results showed that brand popularity was significantly influenced by the characteristics of the product and intelligent promotional techniques. Brand popularity had an influence on brand loyalty in an electronic marketing space

Online Purchase Intention: A Study on Consumer Behaviour in Indian Digital Environment

With a potent market like India and the preference being given to a convenient lifestyle and the now happening digital revolution, Indian marketers and purchasers have started to understand the importance and the advantages of utilizing the online shopping platforms. Digital marketing is what affects the purchasing tendency and intentions of people. The motivation behind this research is to recognize the factors influencing Indian customers' frame of mind towards shopping on the internet along the lines of digital marketing to use it for the benefit of both, the marketer and the consumer. Based on Theory of Planned Behavior, constructs/variables like Perceived Behavioral Control, Subjective Norms, Attitude and India-specific factor (covers several socio-economic factors) were examined and analyzed. Two factors, online buying intention, and online purchase were created to extend the research.  The result shows that online purchase intention has the most significance in converting a buyer to actually make an online purchase. Out of the other factors, subjective norms positively affect the online buying intentions the most and perceived behavior negatively affects the same. The study highly reflects that digital marketing and targeting the right audience positively influence the purchase intention of an individual such that it converts into actual purchase