Impedance of a sphere oscillating in an elastic medium with and without slip

The dynamic impedance of a sphere oscillating in an elastic medium is considered. Oestreicher's formula for the impedance of a sphere bonded to the surrounding medium can be expressed simply in terms of three lumped impedances associated with the displaced mass and the longitudinal and transverse waves. If the surface of the sphere slips while the normal velocity remains continuous, the impedance formula is modified by adjusting the definition of the transverse impedance to include the interfacial impedance.Comment: 10 pages, 2 figure

The cervical cancer epidemic that screening has prevented in the UK.

BACKGROUND: Recent reports suggest that the reduction in mortality achieved by the UK national cervical screening programme is too small to justify its financial and psychosocial costs, except perhaps in a few high-risk women. METHODS: We analysed trends in mortality before 1988, when the British national screening programme was launched, to estimate what future trends in cervical cancer mortality would have been without any screening. FINDINGS: Cervical cancer mortality in England and Wales in women younger than 35 years rose three-fold from 1967 to 1987. By 1988, incidence in this age-range was among the highest in the world despite substantial opportunistic screening. Since national screening was started in 1988, this rising trend has been reversed. INTERPRETATION: Cervical screening has prevented an epidemic that would have killed about one in 65 of all British women born since 1950 and culminated in about 6000 deaths per year in this country. However, these estimates are subject to substantial uncertainty, particularly in relation to the effects of oral contraceptives and changes in sexual behaviour. 80% or more of these deaths (up to 5000 deaths per year) are likely to be prevented by screening, which means that about 100000 (one in 80) of the 8 million British women born between 1951 and 1970 will be saved from premature death by the cervical screening programme at a cost per life saved of about pound 36000. The birth cohort trends also provide strong evidence that the death rate throughout life is substantially lower in women who were first screened when they were younger

That the effects of smoking should be measured in pack-years: misconceptions 4.

Lung cancer incidence in smokers is roughly proportional to dose rate (cigarettes per day) but increases much more rapidly with duration of smoking. The assumption that the incidence rate is proportional to total lifetime dose (the product of dose rate and duration) has been known to be wrong for many years, but total dose in pack-years is still often included, either alone or together, with more fundamental parameters such as dose rate, in regression analysis of epidemiological data. This is mathematically unnecessary and scientifically unhelpful

A Population-Based Ultra-Widefield Digital Image Grading Study for Age-Related Macular Degeneration-Like Lesions at the Peripheral Retina.

Our understanding of the relevance of peripheral retinal abnormalities to disease in general and in age-related macular degeneration (AMD) in particular is limited by the lack of detailed peripheral imaging studies. The purpose of this study was to develop image grading protocols suited to ultra-widefield imaging (UWFI) in an aged population

Schemes of social insurance system

In this article we will analyzed the social security schemes as important elements of this system but also to the individuals. Social security schemes have been established and developed for a very important purpose, to protect individuals and their families against the attack of social risks. For the effect of organizing better social security, the Social Insurance System provides benefits to individuals divided into three groups, or otherwise termed, into three schemes: The scheme of special benefits. The scheme of general benefits. The scheme of unemployment. Analysis of elements of these schemes is treated in detail by virtue of the basic principles of this system the directives of the Council of Europe, as well as international conventions

Prevalence of age-related macular degeneration in Nakuru, Kenya: a cross-sectional population-based study.

BACKGROUND: Diseases of the posterior segment of the eye, including age-related macular degeneration (AMD), have recently been recognised as the leading or second leading cause of blindness in several African countries. However, prevalence of AMD alone has not been assessed. We hypothesized that AMD is an important cause of visual impairment among elderly people in Nakuru, Kenya, and therefore sought to assess the prevalence and predictors of AMD in a diverse adult Kenyan population. METHODS AND FINDINGS: In a population-based cross-sectional survey in the Nakuru District of Kenya, 100 clusters of 50 people 50 y of age or older were selected by probability-proportional-to-size sampling between 26 January 2007 and 11 November 2008. Households within clusters were selected through compact segment sampling. All participants underwent a standardised interview and comprehensive eye examination, including dilated slit lamp examination by an ophthalmologist and digital retinal photography. Images were graded for the presence and severity of AMD lesions following a modified version of the International Classification and Grading System for Age-Related Maculopathy. Comparison was made between slit lamp biomicroscopy (SLB) and photographic grading. Of 4,381 participants, fundus photographs were gradable for 3,304 persons (75.4%), and SLB was completed for 4,312 (98%). Early and late AMD prevalence were 11.2% and 1.2%, respectively, among participants graded on images. Prevalence of AMD by SLB was 6.7% and 0.7% for early and late AMD, respectively. SLB underdiagnosed AMD relative to photographic grading by a factor of 1.7. After controlling for age, women had a higher prevalence of early AMD than men (odds ratio 1.5; 95% CI, 1.2-1.9). Overall prevalence rose significantly with each decade of age. We estimate that, in Kenya, 283,900 to 362,800 people 50 y and older have early AMD and 25,200 to 50,500 have late AMD, based on population estimates in 2007. CONCLUSIONS: AMD is an important cause of visual impairment and blindness in Kenya. Greater availability of low vision services and ophthalmologist training in diagnosis and treatment of AMD would be appropriate next steps. Please see later in the article for the Editors' Summary

The anti-competitive agreements in the prospective of the law on competition protection - An inside in the Albanian practices and legal framework

In Albania legislation on competition was developed only after the 90s and this is natural depending on the economic development and market model, which before the 90s had spaces of a free and competitive development. Competition is an economic phenomenon that refers to such a state of a free market economy, where companies compete independently in order to benefit as many buyers so as to meet the objectives to increase profits and expansion of markets. In this way free competition is both beneficial for business development and profitable for consumers themselves, who should benefit from the prices set based on the demand–offer ratio. Competition should be perceived as a necessary mechanism that promotes increase of welfare in general, by providing enterprises with greater opportunities for profit and therefore better quality for consumers, a major benefit in the range of choices lower prices. Encouraged by the existence of competition, enterprises as market players should be motivated to be always on the alert and perhaps in uncertainty in order to be as much active in the way they compete with their competitors by providing investments and aggressive strategies as a reply to their, but also potential rivals. In competitive markets, the companies are motivated to gain market power in order to strengthen their positions in the markets where they operate and thereby they have an impact in the fulfillment of the growing needs of the consumer, which brings increase of welfare. Nevertheless, quite often companies have such an attitude that they may cause limitation of competition, such as the agreements, whose object or consequence is price fixing, market shares or the establishment of a market structure where competitors join (in case of concentrations). Price fixing is a classic element to all cases of cartels. By means of such behavior competitors try to avoid price competition between them to the detriment of the consumer, by applying higher prices. This may happen at horizontal level, but also at vertical level. What do we perceive with prohibited agreements under Albanian law of competition? What are the forms of agreements that are prohibited and which are excluded? These are some of the questions that this article adresses