Performance evaluation of FBP reconstruction in SPECT Imaging

Abstract Introduction: The purpose of this study was to define an optimal parameter for the tomographic reconstruction procedure in routine single photon emission tomography (SPECT) studies. In this study Hoffman Brain Phantom is modified in such a way that only software capability is evaluated. The phantom is composed of several independent slice that can be imaged individually (planar) or in 3-D composition (SPECT). Method and Materials: Planar image of the slices were imaged separately. The tomographic image was ..

Evaluation of knowledge and attitude of Kerman residents about the usage of bottled water for drinking and cooking purposes

Use of bottled water for drinking and cooking purposes is common in many communities, particularly in places where there is no water of good quality. This type of water supply is an appropriate alternative in prevention of much investment in full-scaled water treatment and dual water distribution system. In Iran, where water is considered as a serious challenge, use of bottled water can be constructive. In this investigation a questionnaire considered of 17 questions was designed and distributed among different classes of Kerman community (N=500) selected by random cluster method in order to evaluate their level of knowledge and attitude about the usage of bottled water. According to the results 45% of the respondents had poor knowledge, 38.8% average, and only 16.2% had a high level of knowledge about the usage of bottled water. Attitudes of the respondents to the use of bottled water were positive, but the market price of the available bottles as well as authorities’ motive for promoting the use of bottled water were questioned by the respondents. It is necessary to take proper measure in order to improve peoples’ level knowledge in this respect, and to encourage people for using bottled water by lowering the price. Keywords: Bottled water, Knowledge, Attitude, Drinking water, Kerma

Application of a time probabilistic approach to seismic landslide hazard estimates in Iran

Iran is a country located in a tectonic active belt and is prone to earthquake and related phenomena. In the recent years, several earthquakes caused many fatalities and damages to facilities, e.g. the Manjil (1990), Avaj (2002), Bam (2003) and Firuzabad-e-Kojur (2004) earthquakes. These earthquakes generated many landslides. For instance, catastrophic landslides triggered by the Manjil Earthquake (Ms = 7.7) in 1990 buried the village of Fatalak, killed more than 130 peoples and cut many important road and other lifelines, resulting in major economic disruption. In general, earthquakes in Iran have been concentrated in two major zones with different seismicity characteristics: one is the region of Alborz and Central Iran and the other is the Zagros Orogenic Belt. Understanding where seismically induced landslides are most likely to occur is crucial in reducing property damage and loss of life in future earthquakes. For this purpose a time probabilistic approach for earthquake-induced landslide hazard at regional scale, proposed by Del Gaudio et al. (2003), has been applied to the whole Iranian territory to provide the basis of hazard estimates. This method consists in evaluating the recurrence of seismically induced slope failure conditions inferred from the Newmark's model. First, by adopting Arias Intensity to quantify seismic shaking and using different Arias attenuation relations for Alborz - Central Iran and Zagros regions, well-established methods of seismic hazard assessment, based on the Cornell (1968) method, were employed to obtain the occurrence probabilities for different levels of seismic shaking in a time interval of interest (50 year). Then, following Jibson (1998), empirical formulae specifically developed for Alborz - Central Iran and Zagros, were used to represent, according to the Newmark's model, the relation linking Newmark's displacement Dn to Arias intensity Ia and to slope critical acceleration ac. These formulae were employed to evaluate the slope critical acceleration (Ac)x for which a prefixed probability exists that seismic shaking would result in a Dn value equal to a threshold x whose exceedence would cause landslide triggering. The obtained ac values represent the minimum slope resistance required to keep the probability of seismic-landslide triggering within the prefixed value. In particular we calculated the spatial distribution of (Ac)x for x thresholds of 10 and 2 cm in order to represent triggering conditions for coherent slides (e.g., slumps, block slides, slow earth flows) and disrupted slides (e.g., rock falls, rock slides, rock avalanches), respectively. Then we produced a probabilistic national map that shows the spatial distribution of (Ac)10 and (Ac)2, for a 10% probability of exceedence in 50 year, which is a significant level of hazard equal to that commonly used for building codes. The spatial distribution of the calculated (Ac)xvalues can be compared with the in situ actual ac values of specific slopes to estimate whether these slopes have a significant probability of failing under seismic action in the future. As example of possible application of this kind of time probabilistic map to hazard estimates, we compared the values obtained for the Manjil region with a GIS map providing spatial distribution of estimated ac values in the same region. The spatial distribution of slopes characterized by ac < (Ac)10 was then compared with the spatial distribution of the major landslides of coherent type triggered by the Manjil earthquake. This comparison provides indications on potential, problems and limits of the experimented approach for the study area. References Cornell, C.A., 1968: Engineering seismic risk analysis, Bull. Seism. Soc. Am., 58, 1583-1606. Del Gaudio V., Wasowski J., & Pierri P., 2003: An approach to time probabilistic evaluation of seismically-induced landslide hazard. Bull Seism. Soc. Am., 93, 557-569. Jibson, R.W., E.L. Harp and J.A. Michael, 1998: A method for producing digital probabilistic seismic landslide hazard maps: an example from the Los Angeles, California, area, U.S. Geological Survey Open-File Report 98-113, Golden, Colorado, 17 pp

Re-examination of the spatial distribution of landslides triggered by the Manjil-Iran 1990 earthquake

The Iranian Plateau, one of the most seismically active regions of the world, has a long history of catastrophic earthquakes. One of the recent destructive events that affected good part of Iran, was the large magnitude (MS =7.7, MW=7.3, Mb =6.4) Manjil earthquake of June 20, 1990, 21:00:10.9 UT. It completely destroyed 700 villages in the Sefidrud river valley and also the cities of Rudbar, Manjil and Loshan, killing more than 40,000 people, injuring 60,000 and rendering 500,000 homeless. Many landslides were triggered by the earthquake and some of them were catastrophic causing numerous fatalities and damage to infrastructure. In this paper the spatial distribution of 51 major landslides triggered by the Manjil earthquake is examined to assess the susceptibility to seismically induced landsliding of an area located in the middle of Alborz mountain range in the northern part of Iran. The study area, which covers 310 km2 is characterized by high relief (including elevations ranging between 1960 and 160 meters a.s.l.) and generaly steep slopes. From the lithological point of view, the study area contains Eocene age volcanic tuffs and andesites, Alborz magmatic assemblage (Karaj Formation, Eocene) consisting of porphyritic and nonporphyritic, andesitic and andesite-basaltic compositions, rhyodacites, calcareous and non-calcareous pyroclastics such as tuffs and agglomerates, limestone, shale and sandstone (Shamshak Formation), unconsolidated, poorly sorted Quaternary deposits. In this study, topographic data with a 30 m resolution and a digital representation of, geology, relevant geotechnical parameters and seismic shaking (Arias intensity) were ingested into a GIS. Then, using regional attenuation relations, Newmark's permanent-deformation (sliding-block) analysis was applied to estimate coseismic landslide displacements and to predict spatial probability of slope-failures. The modelled displacements were compared with the inventory of landslides triggered by the Manjil earthquake to test the reliability of the identification of the zones susceptible to earthquake-induced landslides. The results show that only 40 percent of major landslides were located in areas where the estimated Newmark displacement is larger than the value (10 cm) generally considered as a critical threshold for slope failure: these landslides are found on steeper slopes made of tuffs, agglomerates and limestones. The remaining 60 percent of landslides (with estimated Newmark displacement below the critical value) were found on shallower slopes mostly including Quaternary deposits and interbedded shales and sandstones (Shamshak Formation), and closely associated with the drainage network. Different causes of the apparent discrepancies between the calculated Newmark displacements and landslide triggering are analysed by examining the influence of the uncertainties in geotechnical parameters, possibility of liquefaction failure, as well as the role of factors like topographic, and lithologic shaking amplification, delayed failure following alteration of hydrogeological conditions, and river erosion

Protective effects of resveratrol against X-ray irradiation by regulating antioxidant defense system

Ionizing radiation interacts with biomolecules to produce free radicals, which can damage all components of the cell. The aim of this study was to evaluate the protective effects of different doses of resveratrol against X-ray-induced damage in male rat. The animals were divided into five groups, each composed of six rats: two groups as control groups received saline or ethanol (ethanol in saline, 25%, V/V as a vehicle). Two groups received resveratrol (5 and 10 mg/kg.bwt) for 30 days before X-ray exposure. One group received X-ray. The rats were sacrificed 24 h after the last exposure, blood samples were collected and serum level of malondialdehyde (MDA), total antioxidant capacity (TAC), and the activities of superoxide dismutase (SOD) and catalase (CAT) were measured by spectrophotometric method. X-ray irradiation significantly increased the levels of MDA and decreased TAC as well as SOD activity as compared with control groups. Furthermore, resveratrol pretreatment led to remarkable decrease in MDA concentration and increase in the activities of SOD and CAT as well as TAC compared to those of controls. Our results revealed antioxidant properties of resveratrol and suggest it as a potent radioprotector to ameliorate X-irradiation induced damage in the body