background: absolute dosimetry of external beam radiotherapy is carried out by the use of ionization chambers. these chambers must be calibrated at a standard dosimetry laboratory before any use in clinical dosimetry. the secondary standard dosimetry laboratory of iran (ssdl) has the duty of calibrating the ionization chambers used in radiotherapy centers in iran. materials and methods: the pre...

Alaskan salmon stocks have exhibited enormous fluctuations in production during the 20th century. In this paper, we investigate our hypothesis that large-scale salmon-production variability is driven by climatic processes in the Northeast Pacific Ocean. Using a time-series analytical technique known as intervention analysis, we demonstrate that Alaskan salmonids alternate between high and low p...

The rate of climatic-niche evolution is important to many research areas in ecology, evolution, and conservation biology, including responses of species to global climate change, spread of invasive species, speciation, biogeography, and patterns of species richness. Previous studies have implied that clades with higher rates of climatic-niche evolution among species should have species with nar...

In integrated assessments of climate change, greenhouse-gas emissions and climate change impacts provide the linkages between the world economy and the climate system. Key climatic processes operate at the scales of centuries. This requires highly aggregated models for portraying the dynamics of the economic system. An extended Ramsey-type optimal growth model is presented as the appropriate to...

statement of problem: perforations are significant complications that can occur during root canal therapy and may result in the destruction of adjacent periodontal tissues. an ideal material for repairing a perforation should be biocompatible and have a high sealing ability. purpose: the aim of this study was to compare histologic tissue responses of experimentally induced pulp chamber perforat...

Abstract In the last decades, Fiber Reinforced Cementitious Matrix (FRCM) composites were successfully introduced to repair and strengthen existing masonry structures. The good mechanical performances of these materials determined their efficiency as a strengthening technique; however, durability is still an open issue. As matter fact, FRCM may be exposed combination different environmental con...

Introduction: The present study aimed to present a numerical analysis of the penetration depth,  specific absorption rate (SAR), and temperature rise in various eye tissues with varying distance between radiation source and exposed human eye tissues (i.e., cornea, posterior chamber, anterior chamber, lens, sclera, vitreous humor, and iris) at frequencies of 900 and1800 MHz. Materials and Method...

Introduction: Dental turbine chamber is a suitable reservoir for living microorganisms, so chamber sterilization is necessary for reducing cross contamination risk. On the other hand, in non-vacuum autoclaves, steam penetration into turbine chamber is doubtful, while they are still in use in dental clinics. In this study, performance of small non-vacuum autoclave in turbine chamber sterilizatio...

Abstract Levaillant’s Woodpecker Picus vaillantii is a primary cavity nester, endemic to the forests of northern Africa, including cedar forest in Aurès Mountains. This species, similar all woodpeckers, important for integrity ecosystems, especially as it provides nesting cavities and contributes availability habitats several secondary nesters that cannot excavate their hollows. work aim charac...