Online querying of d-dimensional hierarchies

In this paper we describe a distributed system designed to efficiently store, query and update multidimensional data organized into concept hierarchies and dispersed over a network. Our system employs an adaptive scheme that automatically adjusts the level of indexing according to the granularity of the incoming queries, without assuming any prior knowledge of the workload. Efficient roll-up and drill-down operations take place in order to maximize the performance by minimizing query flooding. Updates are performed on-line, with minimal communication overhead, depending on the level of consistency needed. Extensive experimental evaluation shows that, on top of the advantages that a distributed storage offers, our method answers the vast majority of incoming queries, both point and aggregate ones, without flooding the network and without causing significant storage or load imbalance. Our scheme proves to be especially efficient in cases of skewed workloads, even when these change dynamically with time. At the same time, it manages to preserve the hierarchical nature of data. To the best of our knowledge, this is the first attempt towards the support of concept hierarchies in DHTs.     

Consumer acceptance of RFID-enabled services: a model of multiple attitudes,perceived system characteristics and individual traits

The introduction of emerging technologies in retailing and their infusion in the service encounter necessitates research to better understand consumer attitudes towards the usage of technology in service delivery systems. The capability of Radio Frequency Identification (RFID) technology to automatically and uniquely identify products makes this technology promising as an enabler of innovative consumer services. However there is limited research on how consumers perceive the RFID-enabled service systems. The authors develop and empirically test a model that focuses on consumer attitudes towards technology-based services. Based on the pre-prototype user acceptance framework and using RFID as a focal technology, the proposed model includes a hierarchy of three distinct consumer attitudes: towards the general service concept, towards the general technology-based service application and towards the RFID-enabled service. Perceived system characteristics as well as personality traits are included in the model. The partial least squares method of structural equation modelling is used to analyse 575 questionnaires collected in two consumer surveys in Greece (n=173) and Ireland (N=402). The results of the study show that consumer attitude towards RFID-enabled services in retailing can be modelled as a confluence of multiple attitudes. The results also indicate that perceived system-related factors – such as performance and effort expectancy – as well as individual traits – such as technology anxiety and information privacy concern – affect consumer attitude towards technology-based and RFID-enabled services, respectively.     

An analysis of Android adware

Journal of Computer Virology and Hacking Techniques - Most Android smartphone applications, or apps, are free—to generate revenue, advertisements are displayed when an app is used. Billions...     

Common Trends in Software Fault and Failure Data

The benefits of the analysis of software faults and failures have been widely recognized. However, detailed studies based on empirical data are rare. In this paper, we analyze the fault and failure data from two large, real-world case studies. Specifically, we explore: 1) the localization of faults that lead to individual software failures and 2) the distribution of different types of software faults. Our results show that individual failures are often caused by multiple faults spread throughout the system. This observation is important since it does not support several heuristics and assumptions used in the past. In addition, it clearly indicates that finding and fixing faults that lead to such software failures in large, complex systems are often difficult and challenging tasks despite the advances in software development. Our results also show that requirement faults, coding faults, and data problems are the three most common types of software faults. Furthermore, these results show that contrary to the popular belief, a significant percentage of failures are linked to late life cycle activities. Another important aspect of our work is that we conduct intra- and interproject comparisons, as well as comparisons with the findings from related studies. The consistency of several main trends across software systems in this paper and several related research efforts suggests that these trends are likely to be intrinsic characteristics of software faults and failures rather than project specific.     

Learning secondary mathematics with technology: Exploring the complex interrelationship between students’ attitudes,engagement, gender and achievement

The aim of this study was to investigate the complex relationship between students’ mathematics confidence, confidence with technology, attitude to learning mathematics with technology, affective engagement and behavioural engagement, achievement, gender and year level. The participants were secondary students from state co-educational schools in Metropolitan Athens, Greece. Gender differences as well as differences between year levels and the resulting clusters of students were investigated by using a MANOVA. It was found that boys expressed more positive views towards mathematics and more positive views towards the use of technology in mathematics, compared to girls. It was also found that high achievement in mathematics was associated with high levels of mathematics confidence, strongly positive levels of affective engagement and behavioural engagement, high confidence in using technology and a strongly positive attitude to learning mathematics with technology. Low levels of mathematics achievement was associated with low levels of mathematics confidence, strongly negative levels of affective engagement and behavioural engagement, low confidence in using technology, and a negative attitude to learning mathematics with technology.     

Use of DNA repair enzymes in electrochemical detection of damage to DNA bases in vitro and in cells

Electrochemical measurements at mercury or solid amalgam electrodes offer a highly sensitive detection of DNA strand breaks. On the other hand, electrochemical detection of damage to DNA bases at any electrode is usually much less sensitive. In this paper, we propose a new voltammetric method for the detection of the DNA base damage based on enzymatic conversion of the damaged DNA bases to single-strand breaks (ssb), single-stranded (ss) DNA regions, or both. Supercoiled DNA exposed to UV light was specifically cleaved by T4 endonuclease V, an enzyme recognizing pyrimidine dimers, the major products of photochemical DNA damage. Apurinic sites (formed in dimethyl sulfate-modified DNA) were determined after treating the DNA with E. coli exonuclease III, an enzyme introducing ssb at the abasic sites and degrading one of the DNA strands. The ssb or ssDNA regions, or both, were detected by adsorptive transfer stripping alternating current voltammetry at the mercury electrode. This technique offers much better sensitivity and selectivity of DNA base damage detection than any other electrochemical method. It is not limited to DNA damage in vitro, but it can detect also DNA base damage induced in living bacterial cells.     

Portable device for characterizing the angular response of UV spectroradiometers

This paper introduces a device that was developed to measure the angular response of UV spectroradiometers in the field. This device is designed to be used at the operating position of spectroradiometers; thus the derived angular response also includes any effects from imperfect leveling of the diffuser and corresponds to the actual operational angular response. The design and characterization of the device and the results from its application on 11 different spectroradiometers that operate at different European UV stations are presented. Various sources of uncertainties that were identified result in a combined uncertainty in determining the angular response, which ranges between approximately 1.5% and 10%, depending on the incidence angle and the characteristics of the diffuser. For the 11 instruments, the error in reporting the diffuse irradiance ranges between 2% and - 13%, assuming isotropic distribution of the downwelling radiances.     

Preparation and dissolution characteristics of controlled release diltiazem pellets

Different series of Diltiazem pellets with slow release of the active substance were prepared, by pan coating technique, using different mixtures of acrylic polymers (Eudragit E, Eudragit L, Eudragit RL and Eudragit RS) as film coating agents. The thickness of the coatings were varied by different amounts of Eudragit. Release profiles of Diltiazem hydrochloride were investigated using USP XX rotating basket method (Erweka DT-D6) with 1000 ml buffer solution (pH values 1.5; 2.2; 5.5; 6.8; 7.0) at 37°C as solvent. In vitro dissolution findings showed that Eudragit coatings gave prolonged release of Diltiazem hydrochloride. The permeability of coatings in gastric and intenstinal juices was found to be influenced by the amount of Eudragit L in the formulation. Also, the drug release rate was found to be dependent on the amount of coating applied. In order to understand the drug release mechanism better, the release data were tested assuming common kinetic models. In the present study square - root of the time plots and Weibull plots were not sufficiently linear, although several correlation coefficients were high. When the goodness of fit of release data to first - order kinetics and Hixson - Crowell 's equation was evaluated, the difference between these two models was often noted to be minimal.     

Review of New Directions in Sex Therapy: Innovations and Alternatives.

The impetus for this book grew out of the editor's dissatisfaction with approaches to sex therapy that overemphasize the technical aspects of sexual functioning and thus fail to appreciate the interpersonal relationships in which sexual problems arise. A central thesis of this book is that clinicians need to be aware of how sexuality is always a "product" of a complex set of power relations. The book provides up-to-date coverage of the theoretical and research literature in the field of sex therapy, while the contributors provide challenges to reductive, biomedical explanations of clients' sexual intimacy-related concerns, and they offer many practical, insightful, and helpful suggestions. The book is relevant to sex therapists, but it would also be a valuable resource for counselors and faculty teaching graduate-level courses in sexuality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ferromagnetic coupling of Fe3+-VO-Fe3+polarons in Fe-doped ZnO

Room temperature ferromagnetic Fe-doped ZnO with hexagonal wurtzite structure was synthesized by a hydrothermal method under 4 T high pulsed magnetic field. Detailed studies were carried out to survey the effect of magnetic field on morphological, structural and magnetic properties of samples. The results showed that the concentration of oxygen vacancies (VOs) and amount of Fe³⁺ doping in ZnO were improved due to the high magnetic field processing. It proposed that the inherent exchange interaction is mediated by magnetic ions (Fe³⁺) through VOs assist to produce bound magnetic polorans (BMPs), which is responsible for RTFM in Fe-doped ZnO matrix.