Reliability of a k-out-of-n: G System Subjected to Marshall-Olkin Type Shocks Concerning Magnitude

In this paper the reliability of a k-out-of-n: G system under the effect of shocks having the Marshall-Olkin type shock models, is studied. The magnitudes of the shocks are considered. The system contains n components and only functions when at least k of these components function. The system is subjected to (n + 1) shocks coming from (n + 1) different sources. The shock coming from the it h source may destroy the it h component, i = 1, . . . , n, while the shock coming from the (n + 1)t h source may destroy all components simultaneously. A shock is fatal, destroys a component (components), whenever its magnitude exceeds an upper threshold. The system reliability is obtained by considering the arrival time and the magnitude of a shock as a bivariate random variable. It is assumed that the bivariate random variables representing the arrival times and the magnitudes of the shocks are independent with non-identical bivariate distributions. Since the computation of the reliability formula obtained is not easy to handle, an algorithm is introduced for calculating the reliability formula. The reliability of a k-out-of-n: G system subjected to independent and identical shocks is obtained as a special case, as well as the reliabilities of the series and the parallel systems. As an application, the bivariate exponential Gumbel distribution is considered. Also, numerical illustrations are performed to highlight the results obtained

Incidence of orbital, conjunctival and lacrimal gland malignant tumors in USA from Surveillance, Epidemiology and End Results, 1973-2009

AIM: To determine the types and incidence of tumors affecting the orbit, conjunctiva and lacrimal glands and to study the trend line of these tumors in the United States from 1973 to 2009. METHODS: We used the publicly available Surveillance, Epidemiology and End Results (SEER) database registries to determine the incidence rates. Age was adjusted to the 2000 US Standard Population. Patients were stratified according to age group, gender, race and histological grouping of tumor lesions. Three age groups were defined: 0-19, 20-49 and ≥50y. Annual percentage changes were calculated to examine trends. RESULTS: The overall age adjusted incidence rate was 3.39 (95%CI: 3.27-3.52) per million person-years. The tumors were more prevalent in age group ≥50 counting 9.51 (95%CI: 9.11-9.92) per million person-years. Most of the soft tissue sarcomas occurred in the young age with incidence rate of 0.35 (95%CI: 0.28-0.42) per million person-years. Lymphomas were the dominant subtype in the adult population with incidence rate of 5.74 (95%CI: 5.43-6.06) per million person-years. Incidence rates were higher in males than females with an overall rate ratio of 1.31 (95%CI: 1.21-1.41) mainly caused by the increase in carcinoma subtypes. White race had a higher tumor incidence with a rate ratio of 1.47(95%CI: 1.25-1.73) driven by the higher incidence of most histological subtypes. Orbital tumors showed a higher incidence rate followed by conjunctival and lacrimal gland tumors with incidence rates of 1.59, 1.37 and 0.43 per million person-years respectively. The trend line of overall incidence of tumors showed a significant increase (APC=3.11, 95%CI: 2.61-3.61) mainly due to increase of lymphomas. This increase was higher than the increase of lymphomas at other sites. CONCLUSION: Orbital, conjunctival and lacrimal gland malignant tumors differ among children and adults. Over the years there has been a noticeable increase in incidence rates of orbital and lacrimal gland tumors mainly caused by an increase in lymphomas and an apparent increase due to advances in diagnostic techniques. ICD-O-3 topographical coding should be improved to consider the different orbital bones and ocular structures

Ocular Findings in Neurofibromatosis

Neurofibromatosis (NF) is an inherited disease affecting multiple systems in the body. The eye is frequently affected in neurofibromatosis, and therefore ocular manifestations play a major role in the diagnosis of NF. This chapter aims to explore the spectrum of ocular manifestations found in neurofibromatosis highlighting the importance of ophthalmic exam in these patients. It will describe various intraocular manifestations involving the iris, lens, and retina. It will be focusing on glaucoma and the pathogenesis behind it in this group of patients. Moreover, periorbital and orbital involvement such as skin neurofibromas and optic nerve gliomas will be discussed along with some of their histopathological findings

Global Campus: learning to walk with webbed feet

Universities wishing to expand their provision beyond their local catchment areas need to consider whether to bring the students to the tuition or take the tuition to the students. Current-day educational and information technologies make the latter option a much more achievable prospect than it has been in the past. Nevertheless, careful consideration needs to be given to the nature of the distance-learning students' learning experiences and the extent to which these may be comparable with those of the local students. These matters are considered in this paper against the background of the Global Campus project whereby Middlesex University's School of Computing Science sought to take its initial steps in distance-learning provision

Sharp estimates on the first eigenvalue of the p-Laplacian with negative Ricci lower bound

We complete the picture of sharp eigenvalue estimates for the p-Laplacian on a compact manifold by providing sharp estimates on the first nonzero eigenvalue of the nonlinear operator $\Delta_p$ when the Ricci curvature is bounded from below by a negative constant. We assume that the boundary of the manifold is convex, and put Neumann boundary conditions on it. The proof is based on a refined gradient comparison technique and a careful analysis of the underlying model spaces.Comment: Sign mistake fixed in the proof of the gradient comparison theorem (theorem 5.1 pag 10), and some minor improvements aroun

Dental Pain in Children with Intellectual Disabilities: Caregivers’ Perspective

Purpose. Description of pain is generally difficult in children, and more so in those with intellectual disabilities (ID). Aim. This study is aimed at evaluating dental pain from caregivers’ perspective in children with ID. Methods. The study sampled 86 children (33 with ID, 53 normally developing) ages ranges from birth to 16 years old among those visiting the School of Dentistry, King Abdulaziz University, Saudi Arabia. Caregivers were asked about their awareness of dental pain in their wards using the Dental Discomfort Questionnaire (DDQ+). The children were examined for dental caries and periodontal status. Results. The mean DDQ+ in children with ID (4.55±3.46) was not significantly different from that in healthy children (4.19±3.26, P=0.7). Children with ID had more salivation (P=0.01) and were putting their hands inside their mouths more often (P=0.003). Conclusions. Caregivers can recognize dental pain-related behaviors in children with ID such as excessive salivation and putting hands inside the mouth more often

Assessing the UK policies for broadband adoption

Broadband technology has been introduced to the business community and the public as a rapid way of exploiting the Internet. The benefits of its use (fast reliable connections, and always on) have been widely realised and broadband diffusion is one of the items at the top of the agenda for technology related polices of governments worldwide. In this paper an examination of the impact of the UK government’s polices upon broadband adoption is undertaken. Based on institutional theory a consideration of the manipulation of supply push and demand pull forces in the diffusion of broadband is offered. Using primary and secondary data sources, an analysis of the specific institutional actions related to IT diffusion as pursued by the UK government in the case of broadband is provided. Bringing the time dimension into consideration it is revealed that the UK government has shifted its attention from supply push-only strategies to more interventional ones where the demand pull forces are also mobilised. It is believed that this research will assist in the extraction of the “success factors” in government intervention that support the diffusion of technology with a view to render favourable results if applied to other national settings