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[en] MAXINE is an EXCEL© spreadsheet, which is used to estimate dose to individuals for routine and accidental atmospheric releases of radioactive materials. MAXINE does not contain an atmospheric dispersion model, but rather doses are estimated using air and ground concentrations as input. Minimal input is required to run the program and site specific parameters are used when possible. Complete code description, verification of models, and user’s manual have been included.
[en] The present study discusses a prime cause of fluctuating protein concentrations, which play a significant role in generating phenotypic diversity in bacteria. A genetic circuit integrated in a bacterial genome was used to evaluate the cell-to-cell variation in protein concentration. A simple dynamic model, comprising terms for synthesis and dilution, was used to elucidate the contributions of distinct noises to the fluctuation in cell protein concentration. Experimental and theoretical results demonstrated that noise in the rate of increase in cell volume (cell growth rate) serves as a source of extrinsic noise that accounts for dozens of percent of the total noise, whereas intrinsic noise in protein synthesis makes only a moderate contribution to the fluctuation in protein concentration. This suggests that such external noise in the cell growth rate has a global effect on cellular components, resulting in a large fluctuation in protein concentration in bacterial cells
[en] The spatial variation of soil gas radon values were correlated with the seismogenic faults and earthquakes in the Tangshan area (north China). Radon concentrations were measured at 756 sites in an area about 2500 km2 from April to May 2010. The background and anomaly threshold values calculated were 4730.4 Bq/m3 and 8294.1 Bq/m3, respectively. Radon concentrations highlight a decreasing gradient from NE to SW in the area. Higher values mostly distributed in the NE sector of the Tangshan fault and the Luanxian fault where the Tangshan (Ms 7.8), and Luanxian (MS 7.1) earthquakes occurred in 1976 and 17 earthquakes with MS = 3.0 occurred in this area since 2005. Radon values illustrated a close relation with the shallow fault trace and earthquake activity in the area. The active fault zones and the associated fractures formed by the larger earthquakes, act as paths for radon migration. - Highlights: • Radon concentrations at 756 sites were attained in the Tangshan area. • The background value and anomaly threshold of Rn were calculated out. • Radon concentration decreasing from NE to SW in the study area. • Rn value has a close relation with the fault and earthquake activity
[en] Spatial gradients of surrounding chemoattractants are the key factors in determining the directionality of eukaryotic cell movement. Thus, it is important for cells to accurately measure the spatial gradients of surrounding chemoattractants. Here, we study the precision of sensing the spatial gradients of multiple chemoattractants using cooperative receptor clusters. Cooperative receptors on cells are modeled as an Ising chain of Monod–Wyman–Changeux clusters subject to multiple chemical-gradient fields to study the physical limits of multiple chemoattractants spatial gradients sensing. We found that eukaryotic cells cannot sense each chemoattractant gradient individually. Instead, cells can only sense a weighted sum of surrounding chemical gradients. Moreover, the precision of sensing one chemical gradient is signicantly affected by coexisting chemoattractant concentrations. These findings can provide a further insight into the role of chemoattractants in immune response and help develop novel treatments for inflammatory diseases. (paper)
[en] 137Cs accumulation into surface layers of forest soil is well known. Many studies have shown vertical migration of radiocaesium in forest soils, and also some results are available from the effects of fertilisation on the migration. However, not too many efforts have been done with the soil genetic horizons in this context. This study aims at finding out differences in fertilisation effect on 137Cs sorption in different genetic horizons of Cambic podzol. Soil samples were collected from a mature Norway spruce stand, which included five different fertilisation treatments. The spruce stand was fertilised in May 1986, just after the Chernobyl fallout in Finland. All soil samples were collected by genetic horizons, and classified (FAO classification) and analysed separately enabling also examination of spatial variation of radiocaesium in different treatment plots. (author)
[en] Highlights: • The pre-dose effect on TL and OSL from α-Al2O3:C,Mg and α-Al2O3:C is reported. • TL/OSL dose responses of α-Al2O3:C,Mg is unaffected by pre-dose up to 1000 Gy. • TL/OSL dose responses of α-Al2O3:C is affected by pre-dose. • The concentration of deep traps in α-Al2O3:C,Mg is less than that in α-Al2O3:C. - Abstract: We report the effect of pre-dose on the thermoluminescence (TL) and optically stimulated luminescence (OSL) dose response of α-Al2O3:C,Mg and α-Al2O3:C. Before any luminescence measurement, the samples were irradiated with different doses, namely 100, 500 and 1000 Gy to populate the deep electron traps. This is the pre-dose. The results from TL and OSL studies are compared with results from samples used without any pre-measurement dose. The TL glow curves and OSL decay curves of α-Al2O3:C,Mg recorded after pre-doses of 100, 500 and 1000 Gy are identical to those from a sample used without any pre-dose. Further, the TL and OSL dose response of all α-Al2O3:C,Mg samples are similar regardless of pre-dose. In comparison, the TL glow curves and OSL decay curves of α-Al2O3:C are influenced by pre-dose. We conclude that the differences in the TL and OSL dose response of various pre-dosed samples of α-Al2O3:C are due to the concentration of charge in the deep traps. On the other hand, owing to the lower concentration of such deep traps in α-Al2O3:C,Mg, the TL or OSL dose responses are not affected by pre-dose in this material.
[en] The quest for new sensing phenomena continues because detecting, discriminating, identifying, measuring and monitoring nuclear materials and their radiation from greater range, at lower concentrations, and in a more timely fashion brings greater safety, security and efficiency. The potential phenomena are diverse, and those that have been realised can be found in disparate fields of science, engineering and medicine, which makes the full range difficult to realise and record. The framework presented here offers a means to systematically and comprehensively explore nuclear sensing phenomena. The approach is based on the fundamental concepts of matter and energy, where the sequence starts with the original nuclear material and its emissions, and progressively considers signatures arising from secondary effects and the emissions from associated materials and the environment. Concepts of operations such as active and passive interrogation, and networked sensing are considered. In this operational light, unpacking nuclear signatures forces a fresh look at the sensing concept. It also exposes how some phenomena that exist in established technology may be considered novel based on how they could be exploited rather than what they fundamentally are. This article selects phenomena purely to illustrate the framework and how it can be best used to foster creativity in the quest for novel phenomena rather than exhaustively listing, categorising or comparing any practical aspects of candidate phenomena. (paper)
[en] Arsenic (As) is extremely toxic to living organisms at high concentration. In aquatic systems, As exists in different chemical forms. The two major inorganic As (iAs) species are AsV, which is thermodynamically stable in oxic waters, and AsIII, which is predominant in anoxic conditions. Photosynthetic microorganisms (e.g., phytoplankton and cyanobacteria) take up AsV, biotransform it to AsIII, then biomethylate it to methylarsenic (MetAs) forms. Although AsIII is more toxic than AsV, AsIII is much more easily excreted from the cells than AsV. Therefore, majority of researchers consider the reduction of AsV to AsIII as a detoxification process. The biomethylation process results in the conversion of toxic iAs to the less toxic pentavalent MetAs forms (monomethylarsonate; MMAV, dimethylarsonate; DMAV, and trimethylarsenic oxide; TMAOV) and trimethylarsine (TMAOIII). However, biomethylation by microorganisms also produces monomethylarsenite (MMAIII) and dimethylarsenite (DMAIII), which are more toxic than iAs, as a result of biomethylation by the microorganisms, demonstrates the need to reconsider to what extent As biomethylation contributes to a detoxification process. In this review, we focused on the discussion of whether the biotransformation of As species in microorganisms is really a detoxification process with recent data
[en] Many paddy fields have been contaminated by mercury (Hg) in mining areas of China. In this study, twenty-six rice cultivars and three Hg contaminated paddy fields in different geographic regions were selected for field trials and aimed to investigate the variations and similarities in total Hg (THg) and methylmercury (MeHg) accumulations in brown rice (seeds) across sites. Our results revealed widescale cultivar variation in THg (13–52 ng g−1 at Wanshan) and MeHg (3.5–23 ng g−1) accumulation and %MeHg (17.7–89%) in seeds. The ability to translocate is an important factor in the levels of THg and MeHg in seed. Cultivar tended to stability in THg accumulation across sites. Some cultivars accumulated lower concentrations of both THg and MeHg in seeds at fields seriously contaminated by Hg. Present results suggest that appropriate cultivar selection is a possible way to reduce THg and MeHg accumulation in seeds of rice grown in Hg-contaminated regions. -- Highlights: •Widescale cultivar variations in THg and MeHg accumulation in rice grain. •Some cultivars accumulated lower concentrations of both THg and MeHg in grains at fields seriously contaminated by Hg. •Rice cultivar possesses constancy in grain THg accumulation under different field conditions. -- Rice possesses widescale variations between cultivars and stability within a cultivar in grain THg and MeHg under different filed conditions
[en] Full text: Introduction: Radon exposure has the largest contribution to the internal exposure of the Earth’s population. In order to obtain systematic data a pilot study of the radon concentration in houses in 2011 and 2012 in the frame of the regional project of the International Atomic Energy Agency (IAEA) was carried out. Materials and Methods: Measurements were made in four areas: Sofia- city, Sofia, Plovdiv and Varna. Regions are chosen so as to cover a part of the varied topography of Bulgaria with a large population. The total number of detectors, provided by IAEA, was 400, 100 radon detectors for each area. According to the procedure detectors are placed on the ground habitable floor for a period of 6 months from October 2011 to May 2012 in one room in each apartment of about 1,5 m above the floor and away from windows and doors. Assessment of the concentration of radon was held in Swedish accredited laboratory. Results: The measured values show a wide range of concentration of radon in the rooms (with a maximum in the region of Plovdiv) as a result of various factors: geographical location, type of construction, and factors related to lifestyle. They are generally higher in houses without a basement than in apartments. The measured values were within the range of 20 to 3560 Bq m- 3. Arithmetic mean (AM) and The geometric mean (GM) values obtained for the regions under study are higher than the global average radon concentrations in rooms : AM = 46 Bq m- 3 , GM = 37 Bq m- 3 (UNSCEAR, 2000). Conclusion: The results of the pilot study suggest that there may be radon problem in Bulgaria and should be made a national survey of the whole country. Furthermore, it should be envisaged to reduce public exposure