Bayesian methods for analysing pesticide contamination with uncertain covariates

Two chemical properties of pesticides are thought to control their environmental fate. These are the adsorption coefficient k(_oc) and soil half-life t(^soil_1/2). This study aims to demonstrate the use of Bayesian methods in exploring whether or not it is possible to discriminate between pesticides that leach from those that do not leach on the basis of their chemical properties, when the monitored values of these properties are uncertain, in the sense that there are a range of values reported for both k(_oc) and t(^soil_1/2) - The study was limited to 43 pesticides extracted from the UK Environment Agency (EA) where complete information was available regarding these pesticides. In addition, analysis of data from a separate study, known as "Gustafson's data”, with a single value reported for k(_oc) and t(^soil_1/2) was used as prior information for the EA data. Bayesian methods to analyse the EA data are proposed in this thesis. These methods use logistic regression with random covariates and prior information derives from (i) available United States Department of Agriculture (USDA) data base values of k(_oc) and t(^soil_1/2) for the covariates and (ii) Gustafson's data for the regression parameters. They are analysed by means of Markov Chain Monte Carlo (MCMC) simulation techniques via the freely available WinBUGS software and R package. These methods have succeeded in providing a complete or a good separation between leaching and non-leaching pesticide

Influence of Laser Irradiation Times on Properties of Porous Silicon

Porous silicon (P-Si) has been produced in this work by photoelectrochemical (PEC) etching process. The irradiation has been achieved using diode laser of (2 W) power and 810 nm wavelength. The influence of various irradiation times on the properties of P-Si material such as P-Si layer thickness, surface aspect, pore diameter and the thickness of walls between pores as well as porosity and etching rate was investigated by depending on the scanning electron micrograph (SEM) technique and gravimetric measurements

A model for ranking and selecting integrity tests in a distributed database

Checking the consistency of a database state generally involves the execution of integrity tests on the database, which verify whether the database is satisfying its constraints or not. This paper presents the various types of integrity tests as reported in previous works and discusses how these tests can significantly improve the performance of the constraint checking mechanisms without limiting to a certain type of test. Having these test alternatives and selecting the most suitable test is an issue that needs to be tackled. In this regard, the authors propose a model to rank and select the suitable test to be evaluated given several alternative tests. The model uses the amount of data transferred across the network, the number of sites involved, and the amount of data accessed as the parameters in deciding the suitable test. Several analyses have been performed to evaluate the proposed model, and results show that the model achieves a higher percentage of local processing as compared to the previous selected strategies

Iraqi Women’s Leadership and State-Building

After 2003, Iraq witnessed radical changes in its political system. These changes occurred after many wars, multiple sanctions, and an external occupation during which its infrastructure and institutions were destroyed until it became one of the failed states from which the most serious problems that affect international security and stability emanate. It has also become an environment of conflict and multiple renewed crises, the most important of which is a crisis of leadership and state-building, which has become a necessity to discuss. This research focuses on the topic of the leadership crisis in Iraq and we look to women as a possible leaders in resolving crises and peacemaking in the stage of building the Iraqi state, and on the possibility of applying the relationship between women leadership and nation-building and what this relationship means in the context of continued insecurity and stability. Our research looks at a set of important points: 1- The possibility of exploring the role of women leaders in the process of building the Iraqi state; 2- The political behavior of Iraqi women and their role in the process of state-building; 3- The possibility of women’s participation in conflict resolution and reconstruction after a series of internal political conflicts; 4- The possibility of determining the status of Iraqi women as leaders in the context of political transitions and clarifying the roles they have already played in the transitional phase. Are Iraqi women considered essential actors in the processes of achieving peace and building the state

Skyline queries over incomplete multidimensional database

In recent years, there has been much focus on skyline queries that incorporate and provide more flexible query operators that return data items which are dominating other data items in all attributes (dimensions).Several techniques for skyline have been proposed in the literature.Most of the existing skyline techniques aimed to find the skyline query results by supposing that the values of dimensions are always present for every data item.In this paper we aim to evaluate the skyline preference queries in which some dimension values are missing.We proposed an approach for answering preference queries in a database by utilizing the concept of skyline technique.The skyline set selected for a given query operation is then optimized so that the missing values are replaced with some approximate values that provide a skyline answer with complete data.This will significantly reduce the number of comparisons between data items.Beside that, the number of retrieved skyline data items is reduced and this guides the users to select the most appropriate data items from the several alternative complete skyline data items

Preference evaluation techniques of preference queries in database

Preference queries are considered as a major necessity tool in today’s database management system (DBMS). Adopting preference queries in the database application systems enable users to determine more than one objective in the submitted query which result into more accurate results compared to the traditional queries. Preference queries prefer one data item (tuple) p over the other data item (tuple) q if and only if p is better than q in all dimensions (attributes) and not worse than q in at least one dimension (attribute). Several preference evaluation techniques for preference queries have been proposed which aimed at finding the “best” results that meet the user preferences. These include but not limited to top-k, skyline, ranked skylines, k-representative dominance, k-dominance,top-k dominating, and k-frequency. This paper attempts to survey and analyze the following preference evaluation techniques of query processing in database systems: top-k, skyline, top-k dominating, k-dominance, and k-frequency by highlighting the strengths and the weaknesses of each technique

Density functional theory study of molecular structure, Electronic properties, UV–Vis spectra on coumarin102.

The various properties of the ground and excited electronic states of coumarins 102 using density functional theory (DFT) and time-dependent density functional theory (TDDFT) was calculated by the B3LYP density functional model with 6-31G(d,p) basis set by Gaussian 09 W program. Spectral characteristics of coumarin102 have been probed into by methods of experimental UV-visible, and quantum chemistry. The UV spectrum was measured in methanol. The optimized structures, total energies, electronic states (HOMO- LUMO), energy gap, ionization potentials, electron affinities, chemical potential, global hardness, softness, global electrophilictity, and dipole moment were measured. We find good agreement between experimental data of UV spectrum and TDDFT excitationenergies

Performance evaluation of task scheduling using hybrid meta-heuristic in heterogeneous cloud environment

Cloud computing is a ubiquitous platform that offers a wide range of online services to clients including but not limited to information and software over the Internet. It is an essential role of cloud computing to enable sharing of resources on-demand over the network including servers, applications, storage, services, and database to the end-users who are remotely connected to the network. Task scheduling is one of the significant function in the cloud computing environment which plays a vital role to sustain the performance of the system and improve its efficiency. Task scheduling is considered as an NP-complete problem in many contexts, however, the heterogeneity of resources in the cloud environment negatively influence on the job scheduling process. Furthermore, on the other side, the heuristic algorithms have satisfying performance but unable to achieve the desired level of efficiency for optimizing the scheduling in a cloud environment. Thus, this paper aims at evaluating the effectiveness of the hybrid meta-heuristic that incorporate genetic algorithm along with DE algorithm (GA-DE) in terms of make-span. In addition, the paper also intends to enhance the performance of the task scheduling in the heterogeneous cloud environment exploiting the scientific workflows (Cybershake, Montage, and Epigenomics). The proposed algorithm (GA-DE) has been compared against three heuristic algorithms, namely: HEFT-Upward Rank, HEFT – Downward Rank, and HEFT – Level Rank. The simulation results prove that the proposed algorithm (GA-DE) outperforms the other existing algorithms in all cases in terms of make-span

Algorithm for enhancing the QoS of video traffic over wireless mesh networks

One of the major issues in a wireless mesh networks (WMNs) which needs to be solved is the lack of a viable protocol for medium access control (MAC). In fact, the main concern is to expand the application of limited wireless resources while simultaneously retaining the quality of service (QoS) of all types of traffic. In particular, the video service for real-time variable bit rate (rt-VBR). As such, this study attempts to enhance QoS with regard to packet loss, average delay, and throughput by controlling the transmitted video packets. The packet loss and average delay of QoS for video traffic can be controlled. Results of simulation show that Optimum Dynamic Reservation-Time Division Multiplexing Access (ODR-TDMA) has achieved excellent utilization of resource that improvised the QoS meant for video packets. This study has also proven the adequacy of the proposed algorithm to minimize packet delay and packet loss, in addition to enhancing throughput in comparison to those reported in previous studies