Science.gov

Sample records for polonium tolerance estimations

  1. A simplified analytical method to estimate the bismuth build-up and the polonium activity in LiPb-bearing blankets of a fusion reactor

    SciTech Connect

    Zimin, S.

    1994-09-01

    Although neutron-induced activation in a fusion reactor is a nonlinear problem whose solution requires the use of both neutron transport and activation codes, a simplified analytical approach to bismuth and polonium build-up in lead is proposed to estimate the polonium inventory and the related biological hazards of LiPb-bearing blankets. All neutronic reactions of polonium build-up in lead and in its bismuth impurities are surveyed and discussed. The contribution of the different possible chains to the build-up of polonium is evaluated. A set of differential equations for the densities of {sup 209}Bi and {sup 210}Po isotopes in the lead is worked into simplified, easy-to-use expressions. These analytical formulas obtained for the densities can be used for the estimation of both the bismuth and the polonium densities after any reactor operation time and allow identification of the build-up mechanisms of those isotopes. A simplified formula for polonium inventory estimations at any blanket zone is proposed as well. The polonium inventory evaluation takes into account the initial conditions (primarily bismuth impurity in the lead) and the reactor operation conditions, such as the average availability of a fusion reactor and the blanket operation scenario. 44 refs., 11 figs., 5 tabs.

  2. Primate polonium metabolic models and their use in estimation of systemic radiation doses from bioassay data

    SciTech Connect

    Fellman, A.

    1989-01-01

    A Polonium metabolic model was derived and incorporated into a Fortran algorithm which estimates the systemic radiation dose from {sup 210}Po when applied to occupational urine bioassay data. The significance of the doses estimated are examined by defining the degree of uncertainty attached to them through comprehensive statistical testing procedures. Many parameters necessary for dosimetry calculations, were evaluated from metabolic studies of {sup 210}Po in non-human primates. Two tamarins and six baboons were injected intravenously with {sup 210}Po citrate. Excreta and blood samples were collected. Five of the baboons were sacrifice at times ranging from 1 day to 3 months post exposure. Complete necropsies were performed and all excreta and the majority of all skeletal and tissue samples were analyzed radiochemically for their {sup 210}Po content. The {sup 210}Po excretion rate in the baboon was more rapid than in the tamarin. The biological half-time of {sup 210}Po excretion in the baboon was approximately 15 days while in the tamarin, the {sup 210}Po excretion rate was in close agreement with the 50 day biological half-time predicted by ICRP 30. Excretion fractions of {sup 210}Po in the non-human primates were found to be markedly different from data reported elsewhere in other species, including man.

  3. Polonium pollution

    SciTech Connect

    Not Available

    1982-06-01

    In January of 1982, polonium-210 was discovered in drinking water supplies in two southwest Florida counties. Since then, the radioisotope has been found in two more counties. Samples were taken from 20-25 ft. wells, and Po-210 concentrations ranged from 50-7000 pCi/liter. Federal standards of the Nuclear Regulatory Commission limit concentrations in water supplies to 700 pCi/liter. Although Florida's phosphate rocks are rich sources of uranium, no geographical pattern has been found which would suggest an association of the contamination with phosphate mining operations. However, the ''gyp-stacks'', huge piles of waste calcium sulfate are considered by some to be a potential health hazard because they contain high levels of radium sulfate which, through decay, could eventually form polonium. (JMT)

  4. Thermal Reactions of Polonium

    NASA Astrophysics Data System (ADS)

    Abakumov, A. S.

    1982-07-01

    Published information on the interaction of polonium with the chemical elements has been surveyed and systematised. Attention is paid to specific features of experimental methods for investigating the properties of polonium compounds. Conditions for the direct synthesis of binary polonium compounds and their thermal properties are given. The applicability of the Samsonov classification of chalcogenides to polonium compounds is shown. Bibliography of 43 references.

  5. Primate polonium metabolic models and their use in estimation of systemic radiation doses from bioassay data. Final report

    SciTech Connect

    Cohen, N.

    1989-03-15

    A Polonium metabolic model was derived and incorporated into a Fortran algorithm which estimates the systemic radiation dose from {sup 210}Po when applied to occupational urine bioassay data. The significance of the doses estimated are examined by defining the degree of uncertainty attached to them through comprehensive statistical testing procedures. Many parameters necessary for dosimetry calculations (such as organ partition coefficients and excretion fractions), were evaluated from metabolic studies of {sup 210}Po in non-human primates. Two tamarins and six baboons were injected intravenously with {sup 210}Po citrate. Excreta and blood samples were collected. Five of the baboons were sacrificed at times ranging from 1 day to 3 months post exposure. Complete necropsies were performed and all excreta and the majority of all skeletal and tissue samples were analyzed radiochemically for their {sup 210}Po content. The {sup 210}Po excretion rate in the baboon was more rapid than in the tamarin. The biological half-time of {sup 210}Po excretion in the baboon was approximately 15 days while in the tamarin, the {sup 210}Po excretion rate was in close agreement with the 50 day biological half-time predicted by ICRP 30. Excretion fractions of {sup 210}Po in the non-human primates were found to be markedly different from data reported elsewhere in other species, including man. A thorough review of the Po urinalysis procedure showed that significant recovery losses resulted when metabolized {sup 210}Po was deposited out of raw urine. Polonium-210 was found throughout the soft tissues of the baboon but not with the partition coefficients for liver, kidneys, and spleen that are predicted by the ICRP 30 metabolic model. A fractional distribution of 0.29 for liver, 0.07 for kidneys, and 0.006 for spleen was determined. Retention times for {sup 210}Po in tissues are described by single exponential functions with biological half-times ranging from 15 to 50 days.

  6. POLONIUM SEPARATION PROCESS

    DOEpatents

    Karraker, D.G.

    1959-07-14

    A liquid-liquid extraction process is presented for the recovery of polonium from lead and bismuth. According to the invention an acidic aqueous chloride phase containing the polonium, lead, and bismuth values is contacted with a tributyl phosphate ether phase. The polonium preferentially enters the organic phase which is then separated and washed with an aqueous hydrochloric solution to remove any lead or bismuth which may also have been extracted. The now highly purified polonium in the organic phase may be transferred to an aqueous solution by extraction with aqueous nitric acid.

  7. METHOD FOR ELECTRODEPOSITING POLONIUM

    DOEpatents

    Wehrmann, R.F.

    1960-08-30

    The deposition of a thick uniform layer of polonium metal from aqueous solutions can be carried out by electrolyzing an aqueous solution of 1 N hydrofluoric acid containing about 0.13 curie of polonium per cubic centimeter of solution with platinum electrodes and a current density of about 1.2 ma/cm/sup 2/ of cathode surface.

  8. Helium-3 and CO 2 fluxes from subaerial volcanoes estimated from polonium-210 emissions

    NASA Astrophysics Data System (ADS)

    Marty, Bernard; Le Cloarec, Marie-Françoise

    1992-11-01

    The volcanic flux of 210Po, a radiogenic and radioactive isotope belonging to the decay chain of 238U, has been quantified from its concentration in volcanic plumes and its mean residence time in the troposphere (Lambert et al., 1982). Measurements of 3He, CO 2 and 210Po in the high-temperature gases of a few volcanoes allow estimates of 3He and CO 2 subaerial fluxes to be made. Several factors affecting the 210Po/ 3He ratio in volcanic gases are discussed. The 3He flux from subaerial volcanoes, (1.0±0.5) × 10 2 mol/yr , is one order of magnitude lower than the MOR flux. The volcanic flux of CO 2 into the atmosphere, (2±0.5) × 10 2 mol/yr , is comparable to the carbon flux from the mantle at mid-ocean ridges. We propose that most of carbon involved in subaerial volcanism is derived from the mobilisation of carbon present at the surface of the Earth.

  9. The polonium-210 problem in thermonuclear reactor

    SciTech Connect

    Shchipakhin, O.L.; Borisov, N.B.; Churkin, S.L.

    1993-12-31

    Polonium 210 forms in the lithium-lead eutectic blanket of a thermonuclear reactor. On the basis of obtained experimental data some estimates have been calculated on the ITER blanket accident consequences. The LOCA type accident represents the failure of eutectic circuit in the process of transfusion of liquid eutectic from blanket to the tritium reprocessing plant.

  10. Polonium problem in lead-bismuth flow target

    SciTech Connect

    Pankratov, D.V.; Yefimov, E.I.; Bugreev, M.I.

    1996-06-01

    Alpha-active polonium nuclides Po198 - Po210 are formed in a lead-bismuth target as results of reactions Bi{sup 209}(n,{gamma})Bi{sup 210} {yields} Po{sup 210}, Bi{sup 209}(p,xn)Po{sup 210} {yields} Po{sup 210 {minus} x} (x = 1-12), Pb{sup 208}({alpha},xn) {yields} Po{sup 210 {minus} x + 2} (x = 2-14). The most important nuclides are Po-210 (T{sub {1/2}}=138.4 day), Po-209 (T{sub {1/2}}=102 years) and Po-208 (T{sub {1/2}}=2.9 years). Polonium activity of the circuit for SINQ - conditions is about 15,000 Ci after 1-year operation. Polonium radiation hazard is connected with its output from the coolant and formation of aerosol and surface alpha-activity after the circuit break-down for repair works or in accidents. One of the important issues of polonium removal system creation is containing and storing polonium removed. Its storage in solidified alkaline is not expedient because of secondary neutron formation as a result of ({alpha},n) - reaction on oxygen and sodium nucleus. The estimations carried out demonstrated that by polonium concentration {approx} 100 Ci/l neutron current on the container surface can reach {approx} 10{sup 4}n/(cm{sup 2}s). Concentration and storage of polonium in solidified lead-bisumth seems the most convenient. The calculations demonstrated that in a 100 l container 50,000 Ci of polonium can be stored (as much as 3 times more than 1-year polonium product in SINQ-conditions) under temperature in the container less than melting point of lead bismuth (the wall temperature is about 100{degrees}C).

  11. Why is Polonium simple cubic?

    NASA Astrophysics Data System (ADS)

    Roundy, David; Kraig, Robert E.; Cohen, Marvin L.

    2002-03-01

    Scientists have long pondered why the simple cubic structure is so rarely seen in nature. Only one element forms the simple cubic structure: polonium. There are `proofs' dating back to 1954 that the simple cubic lattice should be unstable. We will attempt to address the question of why polonium takes the simple cubic structure by means of ab initio calculations using the pseudopotential density functional method. We will discuss the electronic structure of polonium in relation to its crystal structure.

  12. Environmental neutralization of polonium-218

    SciTech Connect

    Goldstein, S.D.; Hopke, P.K.

    1985-01-01

    Previous work has indicated that two mechanisms of neutralization of the singly charged polonium ion exist. Charged Polonium-218 can be neutralized by reacting with oxygen to form a polonium oxide ion with a higher ionization potential than that of the polonium metal and then accepting an electron transferred from a lower ionization potential gas. In this present work, this mechanism has been verified by determining that the polonium oxide has an ionization potential in the range 10.35-10.53 eV. It was also previously reported that /sup 218/Po can be neutralized, in the absence of oxygen, by the scavenging of electrons by a trace gas such as water or nitrogen dioxide and their diffusion to the polonium ion. To verify this second neutralization mechanism, concentrations of nitrogen dioxide in nitrogen in the range of 50 ppb-1 ppm were examined for their ability to neutralize the polonium ion. Complete neutralization of /sup 218/Po was observed at nitrogen dioxide concentrations greater than 700 ppb. For concentrations below 700 ppb, the degree of neutralization was found to increase smoothly with the nitrogen dioxide concentration.

  13. Polonium 210Po in the phytobenthos from Puck Bay.

    PubMed

    Skwarzec, B; Ulatowski, J; Strumińska, D I; Falandysz, J

    2003-04-01

    The aim of the work was to determine the 210Po content in phytobenthos species (seaweeds and angiosperms) from Puck Bay (southern Baltic). Alpha spectrometry was used to measure and calculate the activities and concentrations of polonium 210Po in the phytobenthos. The activity of 210Po in Puck Bay waters was determined to estimate the bioconcentration factors (BCF) of these plants. The 210Po concentration in water was estimated at 0.25 mBq dm(-3). The lowest polonium concentration in the phytobenthos was found in Cladophora rupestris (0.12 Bq kg(-1) wet wt.), the highest in Chara crinita (1.12 Bq kg(-1) wet wt.). Polonium is accumulated in these phytobenthos species; the bioconcentration factors (BCF) ranged from 450 to 4400.

  14. Murder with Radioactive Polonium Metal.

    PubMed

    Kato, T A; Wozniak, D E

    2014-07-01

    The physical and biological aspects of polonium-210, one of the most hazardous radioisotopes, are summarized. Although this radioisotope is naturally occurring and rare, it received quite a bit of attention after it was used in the 2006 assassination of former Russian Intelligence member Alexander Litvinenko in London. Recent reports on the suspected murder of Yasser Arafat with polonium-210 are also discussed. Copyright © 2014 Central Police University.

  15. Polonium-210 budget in cigarettes.

    PubMed

    Khater, Ashraf E M

    2004-01-01

    Due to the relatively high activity concentrations of (210)Po and (210)Pb that are found in tobacco and its products, cigarette smoking highly increases the internal intake of both radionuclides and their concentrations in the lung tissues. That might contribute significantly to an increase in the internal radiation dose and in the number of instances of lung cancer observed among smokers. Samples of most frequently smoked fine and popular brands of cigarettes were collected from those available on the Egyptian market. (210)Po activity concentrations were measured by alpha spectrometry, using surface barrier detectors, following the radiochemical separation of polonium. Samples of fresh tobacco, wrapping paper, fresh filters, ash and post-smoking filters were spiked with (208)Po for chemical recovery calculation. The samples were dissolved using mineral acids (HNO(3), HCl and HF). Polonium was spontaneously plated-out on stainless steel disks from diluted HCl solution. The (210)Po activity concentration in smoke was estimated on the basis of its activity in fresh tobacco and wrapping paper, fresh filter, ash and post-smoking filters. The percentages of (210)Po activity concentrations that were recovered from the cigarette tobacco to ash, post-smoking filters, and smokes were assessed. The results of this work indicate that the average (range) activity concentration of (210)Po in cigarette tobacco was 16.6 (9.7-22.5) mBq/cigarette. The average percentages of (210)Po content in fresh tobacco plus wrapping paper that were recovered by post-smoking filters, ash and smoke were 4.6, 20.7 and 74.7, respectively. Cigarette smokers, who are smoking one pack (20 cigarettes) per day, are inhaling on average 123 mBq/d of (210)Po and (210)Pb each. The annual effective doses were calculated on the basis of (210)Po and (210)Pb intake with the cigarette smoke. The mean values of the annual effective dose for smokers (one pack per day) were estimated to be 193 and 251 microSv from

  16. Environmental properties of polonium-218

    SciTech Connect

    Goldstein, S.D.

    1983-01-01

    An investigation was undertaken of the atmospheric chemistry of the radon decay product polonium-218. Previous work has indicated that two mechanisms of neutralization of the singly charged ion exist. Charged RaA can be neutralized by reacting with oxygen to form a polonium oxide ion that has a higher ionization potential than that of the polonium metal, and then accepting an electron transferred from a lower ionization potential gas. It was been determined that the polonium dioxide has an ionization potential in the range of 10.35 to 10.53 eV. It has also been determined that RaA can be neutralized, in the absence of oxygen, from the scavenging of electrons by a trace gas such as water or nitrogen dioxide and the diffusion to the polonium ion. To verify the presence of the second neutralization mechanism, nitrogen dioxide in nitrogen concentrations in the range of 1 ppM to 50 ppB were examined. Complete neutralization of RaA was observed at nitrogen dioxide concentrations greater than 700 ppB. For concentrations less than 700 ppB, the degree of neutralization was found to decrease. 12 references, 3 figures, 8 tables.

  17. Polonium-210 as a poison.

    PubMed

    Harrison, John; Leggett, Rich; Lloyd, David; Phipps, Alan; Scott, Bobby

    2007-03-01

    The death of Alexander Litvinenko on 23 November 2006 has brought into focus scientific judgements concerning the radiotoxicity of polonium-210 ((210)Po). This paper does not consider the specific radiological circumstances surrounding the tragic death of Mr Litvinenko; rather, it provides an evaluation of published human and animal data and models developed for the estimation of alpha radiation doses from (210)Po and the induction of potentially fatal damage to different organs and tissues. Although uncertainties have not been addressed comprehensively, the reliability of key assumptions is considered. Concentrating on the possibility of intake by ingestion, the use of biokinetic and dosimetric models to estimate organ and tissue doses from (210)Po is examined and model predictions of the time-course of dose delivery are illustrated. Estimates are made of doses required to cause fatal damage, taking account of the possible effects of dose protraction and the relative biological effectiveness (RBE) of alpha particles compared to gamma and x-rays. Comparison of LD(50) values (dose to cause death for 50% of people) for different tissues with the possible accumulation of dose to these tissues suggests that bone marrow failure is likely to be an important component of multiple contributory causes of death occurring within a few weeks of an intake by ingestion. Animal data on the effects of (210)Po provide good confirmatory evidence of intakes and doses required to cause death within about 3 weeks. The conclusion is reached that 0.1-0.3 GBq or more absorbed to blood of an adult male is likely to be fatal within 1 month. This corresponds to ingestion of 1-3 GBq or more, assuming 10% absorption to blood. Well-characterised reductions in white cell counts would be observed. Bone marrow failure is likely to be compounded by damage caused by higher doses to other organs, including kidneys and liver. Even if the bone marrow could be rescued, damage to other organs can be

  18. Bacterial mobilization of polonium

    NASA Astrophysics Data System (ADS)

    Larock, P.; Hyun, J.-H.; Boutelle, S.; Burnett, W. C.; Hull, C. D.

    1996-11-01

    Polonium has been observed as the sole a-emitting nuclide in groundwaters of central Florida, in the absence of its radiogenic parents, at levels of 1,000 dpm/l or more. Because of the chemical similarity of Po to S (both occupy the same column in the periodic table), studies were begun to determine whether bacteria, particularly those species active in sulfur cycling, could account for the selective solubilization and mobilization of Po. Possible sources of Po are the U-rich phosphate rock and phosphogypsum (gypsum), a byproduct in the manufacture of phosphoric acid. This paper reports on a series of experiments involving the interaction of bacteria with this waste gypsum that resulted in the solubilization of Po. Bacteria were isolated from gypsum that were capable of mediating Po release in column experiments when fed a growth medium. Sulfate-reducing bacteria were particularly effective at mediating Po release provided the sulfide levels did not rise above 10 μM, in which case Po was apparently coprecipitated as a metal sulfide. Conversely, the ability of sulfate-reducing bacteria to effctively remove dissolved Po when sulfide levels are high suggests that these bacteria may be used as an effective bioremediation tool at reducing groundwater Po levels.

  19. Polonium and Lung Cancer

    PubMed Central

    Zagà, Vincenzo; Lygidakis, Charilaos; Chaouachi, Kamal; Gattavecchia, Enrico

    2011-01-01

    The alpha-radioactive polonium 210 (Po-210) is one of the most powerful carcinogenic agents of tobacco smoke and is responsible for the histotype shift of lung cancer from squamous cell type to adenocarcinoma. According to several studies, the principal source of Po-210 is the fertilizers used in tobacco plants, which are rich in polyphosphates containing radio (Ra-226) and its decay products, lead 210 (Pb-210) and Po-210. Tobacco leaves accumulate Pb-210 and Po-210 through their trichomes, and Pb-210 decays into Po-210 over time. With the combustion of the cigarette smoke becomes radioactive and Pb-210 and Po-210 reach the bronchopulmonary apparatus, especially in bifurcations of segmental bronchi. In this place, combined with other agents, it will manifest its carcinogenic activity, especially in patients with compromised mucous-ciliary clearance. Various studies have confirmed that the radiological risk from Po-210 in a smoker of 20 cigarettes per day for a year is equivalent to the one deriving from 300 chest X-rays, with an autonomous oncogenic capability of 4 lung cancers per 10000 smokers. Po-210 can also be found in passive smoke, since part of Po-210 spreads in the surrounding environment during tobacco combustion. Tobacco manufacturers have been aware of the alpha-radioactivity presence in tobacco smoke since the sixties. PMID:21772848

  20. Polonium metabolism in adult female baboons

    SciTech Connect

    Fellman, A. ); Ralston, L. ); Hickman, D. ); Ayres, L.; Cohen, N. )

    1994-02-01

    The biokinetics of polonium in nonhuman primates (Papio anubis) has been studied after intravenous injection of [sup 210]Po citrate. The urinary excretion of polonium in the baboon could be described by a single exponential function with a half-time of 15.6 days. Excretion fractions of polonium were found to be markedly different from those reported for other species, including humans. Polonium-210 was found to be distributed throughout the soft tissues of the baboon with 29% of the injected polonium being deposited in liver, 7% in kidneys and 0.6 in spleen. Retention of polonium in all tissues exhibited single exponential functions; however, the biological half-times were variable, ranging from 15 to 50 days. 23 refs., 9 figs., 10 tabs.

  1. Ab Initio Study of Polonium

    NASA Astrophysics Data System (ADS)

    Zabidi, Noriza Ahmad; Kassim, Hasan Abu; Shrivastava, Keshav N.

    2008-05-01

    Polonium is the only element with a simple cubic (sc) crystal structure. Atoms in solid polonium sit at the corners of a simple cubic unit cell and no where else. Polonium has a valence electron configuration 6s26p4 (Z = 84). The low temperature α-phase transforms into the rhombohedral (trigonal) β structure at ˜348 K. The sc α-Po unit cell constant is a = 3.345 Å. The beta form of polonium (β-Po) has the lattice parameters, aR = 3.359 Å and a rhombohedral angle 98°13'. We have performed an ab initio electronic structure calculation by using the density functional theory. We have performed the calculation with and without spin-orbit (SO) coupling by using both the LDA and the GGA for the exchange-correlations. The k-points in a simple cubic BZ are determined by R (0.5, 0.5, 0.5), Γ (0, 0, 0), X (0.5, 0, 0), M (0.5, 0.5, 0) and Γ (0, 0, 0). Other directions of k-points are Γ (0, 0, 0), X (0.5, 0, 0), R (0.5, 0.5, 0.5) and Γ (0, 0, 0). The SO splittings of p states at the Γ point in the GGA+SO scheme for α-Po are 0.04 eV and 0.02 eV while for the β-Po these are 0.03 eV and 0.97 eV. We have also calculated the vibrational spectra for the unit cells in both the structures. We find that exchanging of a Po atom by Pb atom produces several more bands and destabilizes the β phase.

  2. Ab Initio Study of Polonium

    SciTech Connect

    Zabidi, Noriza Ahmad; Kassim, Hasan Abu; Shrivastava, Keshav N.

    2008-05-20

    Polonium is the only element with a simple cubic (sc) crystal structure. Atoms in solid polonium sit at the corners of a simple cubic unit cell and no where else. Polonium has a valence electron configuration 6s{sup 2}6p{sup 4} (Z = 84). The low temperature {alpha}-phase transforms into the rhombohedral (trigonal) {beta} structure at {approx}348 K. The sc {alpha}-Po unit cell constant is a = 3.345 A. The beta form of polonium ({beta}-Po) has the lattice parameters, a{sub R} = 3.359 A and a rhombohedral angle 98 deg. 13'. We have performed an ab initio electronic structure calculation by using the density functional theory. We have performed the calculation with and without spin-orbit (SO) coupling by using both the LDA and the GGA for the exchange-correlations. The k-points in a simple cubic BZ are determined by R (0.5, 0.5, 0.5), {gamma} (0, 0, 0), X (0.5, 0, 0), M (0.5, 0.5, 0) and {gamma} (0, 0, 0). Other directions of k-points are {gamma} (0, 0, 0), X (0.5, 0, 0), R (0.5, 0.5, 0.5) and {gamma} (0, 0, 0). The SO splittings of p states at the {gamma} point in the GGA+SO scheme for {alpha}-Po are 0.04 eV and 0.02 eV while for the {beta}-Po these are 0.03 eV and 0.97 eV. We have also calculated the vibrational spectra for the unit cells in both the structures. We find that exchanging of a Po atom by Pb atom produces several more bands and destabilizes the {beta} phase.

  3. A systemic biokinetic model for polonium.

    PubMed

    Leggett, R W; Eckerman, K F

    2001-07-25

    Although the biokinetics of polonium has been studied extensively, interpretation of the data is complicated by potential differences with species and route of exposure and the questionable reliability of much of the reported excretion data for man. A study was undertaken to identify the data that are most likely to represent the typical behavior of polonium and apply those data to construct an improved, physiologically realistic systemic biokinetic model for polonium in man. Such a model is needed for interpretation of urinary excretion data for workers exposed to 210Po and reconstruction of the radiation doses received by those workers. This paper reviews the database on the biokinetics of polonium and describes a new systemic biokinetic model for polonium in man.

  4. The experimental study of the polonium-210 release from Li17-Pb83 eutectic

    SciTech Connect

    Schipakin, O.; Borisov, N.; Churkin, S.

    1994-12-31

    The polonium contamination hazard arise as a result of accidental Po-210 release from breeding blanket material - melted Li17Pb83 eutectic - in the environment. The experimental study of Po-210 release rates from eutectic were carry out in atmosphere of noble gases and air with different humidity in 1992-1993. In these experiments used method of carrier-gas flowing above melted eutectic surface. The main findings presented by RDIPE and Karpov Institute are: (1) The polonium-210 release rate strongly increase with eutectic temperature from 150 to 450{degrees}C. (2) The Po-210 release rate in the noble carrier-gas is in proportion with polonium concentration in eutectic in studied range from 10{sup {minus}7} to 10{sup {minus}4} Ci/g. (3) The Po-210 release rate in air remarkably effected by the surface oxide film also. (4) In these experiments for the first time were studied differently gaseous and aerosol polonium-210 fractions release rates. The experimental results and corresponding estimates showed needs the technological and accidental cleaning systems equipped by complex filters of gaseous and aerosols polonium-210 forms.

  5. The polonium-210 poisoning of Mr Alexander Litvinenko.

    PubMed

    Harrison, John; Fell, Tim; Leggett, Rich; Lloyd, David; Puncher, Matthew; Youngman, Mike

    2017-03-20

    Mr Litvinenko died on 23 November 2006 after having been poisoned with polonium-210 on 1 November. Measurements of the polonium-210 content of post-mortem tissue samples and samples of urine and blood showed the presence of large amounts of (210)Po. Autoradiography of hair samples showed two regions of (210)Po activity, providing evidence of an earlier poisoning attempt during October 2006, resulting in absorption to blood of about one-hundredth of that estimated for 1 November. Intake by ingestion on 1 November was estimated to be around 4 GBq, assuming 10% absorption to blood, and the resulting organ doses reached estimated values that were generally in a range from about 20 Gy to over 100 Gy. Comparison with estimates of protracted alpha particle doses required to cause irreversible organ damage supported the conclusion that death was the inevitable consequence of multiple organ failure, with destruction of the haemopoietic bone marrow, as well as damage to kidneys and liver, being important contributors. If the earlier poisoning during October 2006 had not been followed by a second major intake on 1 November, it is possible that the earlier intake of around 40 MBq, with absorption of 4 MBq to blood, might have caused irreversible kidney damage over a prolonged period of months or years, with doses of approaching 3 Gy.

  6. Polonium-210 and lead-210 in food and tobacco products: a review of parameters and an estimate of potential exposure and dose

    SciTech Connect

    Watson, A.P.

    1983-07-01

    Food-chain transport of Pb-210 and Po-210 from soil to edible plant parts and from animal feed to meat and milk were evaluated from a review of literature. The degree of transfer was characterized by estimating concentration factors (unweighted arithmetic means) as well as the transfer coefficients B/sub v/, B/sub r/ (unweighted geometric means, f/sub m/ and f/sub f/ (unweighted arithmetic means). Global dietary intake of Pb-210 and Po-210 was also summarized, and 50-year dose estimates to target organs calculated. The greatest estimated ingestion doses were those to populations with large dietary complements of animal protein in the form of seafood (Japan) or caribou/reindeer muscle and organ meats (Arctic Eskimos and Lapps). The magnitude of this latter source illustrates the importance of simple food chains in generating significant exposures to populations dependent upon them. The origin and magnitude of inhalation exposure and dose from tobacco products was also assessed. For the majority of internal organs evaluated, the dose resulting from smoking commercially available tobacco products is comparable to or greater than the dose estimates for ingestion of naturally occurring dietary Pb-210 and Po-210.

  7. The polonium-210 poisoning of Mr Alexander Litvinenko

    DOE PAGES

    Harrison, John; Fell, Tim; Leggett, Rich; ...

    2017-02-28

    Mr Litvinenko died on 23rd November 2006 after having been poisoned with polonium-210 on 1st November. Measurements of the polonium-210 content of post-mortem tissue samples and samples of urine and blood showed the presence of large amounts of 210Po. Furthermore, autoradiography of hair samples showed two regions of 210Po activity, providing evidence of an earlier poisoning attempt during October 2006, resulting in absorption to blood of about one-hundredth of that estimated for 1st November. Intake by ingestion on 1st November was estimated to be around 4 GBq, assuming 10% absorption to blood, and the resulting organ doses reached estimatedmore » values that were generally in a range from about 20 Gy to over 100 Gy. In comparison with estimates of protracted alpha particle the doses required to cause irreversible organ damage support the conclusion that death was the inevitable consequence of multiple organ failure, with destruction of the haemopoietic bone marrow, as well as damage to kidneys and liver, being important contributors. If the earlier poisoning during October 2006 had not been followed by a second major intake on 1st November, it is possible that the earlier intake of around 40 MBq, with absorption of 4 MBq to blood, might have proved fatal over a prolonged period of months or years, primarily as a result of kidney damage following a dose of approaching 3 Gy.« less

  8. Proton-induced Polonium Production in Lead

    NASA Astrophysics Data System (ADS)

    Lorenz, T.; Dai, Y.; Schumann, D.; Türler, A.

    2014-05-01

    An appropriate experimental approach is described from which information can be obtained on the amounts of radiotoxic polonium isotopes 208-210Po produced in a lead spallation target during an irradiation period of 16 months from 2000 to 2001. Lead samples from a central position near the beam entry were dissolved and spontaneous deposition of polonium on silver discs was used to prepare thin layer samples for α-counting. The evaluated results show a good correlation to the gradient of the proton beam profile.

  9. Delayed neutrons in fission of polonium isotopes

    SciTech Connect

    Ramazanov, R.; Urikbaev, Z.S.; Maksyutenko, B.P.; Ignat'ev, S.V.

    1988-06-01

    A strong difference is found in the relative yields of delayed neutrons in the production of compound nuclei of polonium isotopes in reactions in which bismuth and lead are bombarded by various charged particles. The effect can be partially explained by the different lengths of the ..beta..-decay chains of the light and heavy fission products.

  10. Human absorption and retention of polonium-210 from caribou meat.

    PubMed

    Thomas, P A; Fisenne, I; Chorney, D; Baweja, A S; Tracy, B L

    2001-01-01

    The gastrointestinal (GI) absorption factors and the biological retention times for polonium were determined for a group of 14 volunteers--seven men and seven women--from Saskatoon, Saskatchewan, Canada. Each volunteer consumed 2.0 kg of caribou meat containing known amounts of naturally occurring 210Po. Urine and faecal samples were collected for up to 65 days after meat consumption and analysed for 210Po. The average GI absorption factor for the 14 volunteers was 56 +/- 4% (range = 31-71%), not significantly different from the ICRP value of 50%. About 3% of absorbed polonium underwent prompt excretion by the urinary pathway. The remainder was retained by the body with a half-time >100 days, compared to the ICRP value of 50 days. The effect of these findings increases the dose estimate for ingestion of 210Po in food by a factor of 1.5 to 3.5. Thus, background doses to people consuming caribou and reindeer may be higher than previously thought.

  11. Lead 210 and polonium 210 in Mount St. Helens ash

    NASA Astrophysics Data System (ADS)

    Nevissi, A. E.

    1984-07-01

    During the Mount St. Helens eruptions, lead 210 and polonium 210 were measured in volcanic ash samples. Polonium 210 was consistently higher than lead 210 in all samples, with the 210Po/210Pb ratios ranging from 2 to 12. The overequilibrium of the ratios is due to the enrichment of polonium compounds in the volcanic gases from hot magma relative to less volatile lead compounds.

  12. The first step toward genetic selection for host tolerance to infectious pathogens: obtaining the tolerance phenotype through group estimates

    PubMed Central

    Doeschl-Wilson, Andrea B.; Villanueva, Beatriz; Kyriazakis, Ilias

    2012-01-01

    Reliable phenotypes are paramount for meaningful quantification of genetic variation and for estimating individual breeding values on which genetic selection is based. In this paper, we assert that genetic improvement of host tolerance to disease, although desirable, may be first of all handicapped by the ability to obtain unbiased tolerance estimates at a phenotypic level. In contrast to resistance, which can be inferred by appropriate measures of within host pathogen burden, tolerance is more difficult to quantify as it refers to change in performance with respect to changes in pathogen burden. For this reason, tolerance phenotypes have only been specified at the level of a group of individuals, where such phenotypes can be estimated using regression analysis. However, few stsudies have raised the potential bias in these estimates resulting from confounding effects between resistance and tolerance. Using a simulation approach, we demonstrate (i) how these group tolerance estimates depend on within group variation and co-variation in resistance, tolerance, and vigor (performance in a pathogen free environment); and (ii) how tolerance estimates are affected by changes in pathogen virulence over the time course of infection and by the timing of measurements. We found that in order to obtain reliable group tolerance estimates, it is important to account for individual variation in vigor, if present, and that all individuals are at the same stage of infection when measurements are taken. The latter requirement makes estimation of tolerance based on cross-sectional field data challenging, as individuals become infected at different time points and the individual onset of infection is unknown. Repeated individual measurements of within host pathogen burden and performance would not only be valuable for inferring the infection status of individuals in field conditions, but would also provide tolerance estimates that capture the entire time course of infection. PMID

  13. Parameter Estimation Analysis for Hybrid Adaptive Fault Tolerant Control

    NASA Astrophysics Data System (ADS)

    Eshak, Peter B.

    Research efforts have increased in recent years toward the development of intelligent fault tolerant control laws, which are capable of helping the pilot to safely maintain aircraft control at post failure conditions. Researchers at West Virginia University (WVU) have been actively involved in the development of fault tolerant adaptive control laws in all three major categories: direct, indirect, and hybrid. The first implemented design to provide adaptation was a direct adaptive controller, which used artificial neural networks to generate augmentation commands in order to reduce the modeling error. Indirect adaptive laws were implemented in another controller, which utilized online PID to estimate and update the controller parameter. Finally, a new controller design was introduced, which integrated both direct and indirect control laws. This controller is known as hybrid adaptive controller. This last control design outperformed the two earlier designs in terms of less NNs effort and better tracking quality. The performance of online PID has an important role in the quality of the hybrid controller; therefore, the quality of the estimation will be of a great importance. Unfortunately, PID is not perfect and the online estimation process has some inherited issues; the online PID estimates are primarily affected by delays and biases. In order to ensure updating reliable estimates to the controller, the estimator consumes some time to converge. Moreover, the estimator will often converge to a biased value. This thesis conducts a sensitivity analysis for the estimation issues, delay and bias, and their effect on the tracking quality. In addition, the performance of the hybrid controller as compared to direct adaptive controller is explored. In order to serve this purpose, a simulation environment in MATLAB/SIMULINK has been created. The simulation environment is customized to provide the user with the flexibility to add different combinations of biases and delays to

  14. Potential energy surfaces of Polonium isotopes

    NASA Astrophysics Data System (ADS)

    Nerlo-Pomorska, B.; Pomorski, K.; Schmitt, C.; Bartel, J.

    2015-11-01

    The evolution of the potential energy landscape is analysed in detail for ten even-even polonium isotopes in the mass range 188\\lt A\\lt 220 as obtained within the macroscopic-microscopic approach, relying on the Lublin-Strasbourg drop model and the Yukawa-folded single-particle energies for calculating the microscopic shell and pairing corrections. A variant of the modified Funny-Hills nuclear shape parametrization is used to efficiently map possible fission paths. The approach explains the main features of the fragment partition as measured in low-energy fission along the polonium chain. The latter lies in a transitional region of the nuclear chart, and will be essential to consistently understand the evolution of fission properties from neutron-deficient mercury to heavy actinides. The ability of our method to predict fission observables over such an extended region looks promising.

  15. Evaluation of static eliminators containing polonium-210

    SciTech Connect

    Czajkowski, C.J.

    1999-01-01

    Six static eliminators containing radioactive polonium-210 microspheres were examined subsequent to a contamination incident at a commercial facility. It was found that cracked and broken microspheres were being produced and incorporated into new devices and even as received devices were potential sources of contamination. It is shown that rough handling of the devices may initiate polonium-210 leakage during or prior to service. The epoxy binder used in the devices appears to suffer significant environmental and material damage even under ambient conditions. The effects of solvents, heat, moisture, or vibration during service may accelerate this damage. The breakdown of the epoxy binder appears to be a significant contributor to the contamination by loose microspheres or microsphere fragments.

  16. [Polonium-210 acute and chronic pathomorphology and pathogenesis].

    PubMed

    Kvacheva, Yu E

    2015-01-01

    In the present review, the data on the pathology of acute and chronic polonium injuries available from the an open-access domestic and foreign literature are primarily systemized and analyzed. The historical background of the research is presented in brief. On the basis of clinical and experimental generalizations, the current concept regarding the pathogenesis of polonium intoxication has been developed.

  17. METHOD OF PREPARING POLONIUM-BORON SOURCES

    DOEpatents

    Birden, J.H.

    1959-08-01

    An improved technique is described for preparation of a polonium-boron neutron source. A selected amount of Po-210 is vaporized into a thin walled nickel container, then the desired amcunt of boron powder is added. After sealing the container, it is heated quickly by induction heating to vaporize the Po-210 and deposit it in the still cool boron powder. The unit is then quickly cooled to prevent revaporization of the Po-210 from the boron. The build-up of neutron emission may be followed by means of a neutron counter in order to terminate the heating at the optimum level of neutron yield.

  18. Plant Distribution Data Show Broader Climatic Limits than Expert-Based Climatic Tolerance Estimates

    PubMed Central

    Curtis, Caroline A.; Bradley, Bethany A.

    2016-01-01

    Background Although increasingly sophisticated environmental measures are being applied to species distributions models, the focus remains on using climatic data to provide estimates of habitat suitability. Climatic tolerance estimates based on expert knowledge are available for a wide range of plants via the USDA PLANTS database. We aim to test how climatic tolerance inferred from plant distribution records relates to tolerance estimated by experts. Further, we use this information to identify circumstances when species distributions are more likely to approximate climatic tolerance. Methods We compiled expert knowledge estimates of minimum and maximum precipitation and minimum temperature tolerance for over 1800 conservation plant species from the ‘plant characteristics’ information in the USDA PLANTS database. We derived climatic tolerance from distribution data downloaded from the Global Biodiversity and Information Facility (GBIF) and corresponding climate from WorldClim. We compared expert-derived climatic tolerance to empirical estimates to find the difference between their inferred climate niches (ΔCN), and tested whether ΔCN was influenced by growth form or range size. Results Climate niches calculated from distribution data were significantly broader than expert-based tolerance estimates (Mann-Whitney p values << 0.001). The average plant could tolerate 24 mm lower minimum precipitation, 14 mm higher maximum precipitation, and 7° C lower minimum temperatures based on distribution data relative to expert-based tolerance estimates. Species with larger ranges had greater ΔCN for minimum precipitation and minimum temperature. For maximum precipitation and minimum temperature, forbs and grasses tended to have larger ΔCN while grasses and trees had larger ΔCN for minimum precipitation. Conclusion Our results show that distribution data are consistently broader than USDA PLANTS experts’ knowledge and likely provide more robust estimates of climatic

  19. Mortality among mound workers exposed to polonium-210 and other sources of radiation, 1944-1979.

    PubMed

    Boice, John D; Cohen, Sarah S; Mumma, Michael T; Ellis, Elizabeth Dupree; Cragle, Donna L; Eckerman, Keith F; Wallace, Phillip W; Chadda, Bandana; Sonderman, Jennifer S; Wiggs, Laurie D; Richter, Bonnie S; Leggett, Richard W

    2014-02-01

    Polonium-210 is a naturally occurring radioactive element that decays by emitting an alpha particle. It is in the air we breathe and also a component of tobacco smoke. Polonium-210 is used as an anti-static device in printing presses and gained widespread notoriety in 2006 after the poisoning and subsequent death of a Russian citizen in London. More is known about the lethal effects of polonium-210 at high doses than about late effects from low doses. Cancer mortality was examined among 7,270 workers at the Mound nuclear facility near Dayton, OH where polonium-210 was used (1944-1972) in combination with beryllium as a source of neutrons for triggering nuclear weapons. Other exposures included external gamma radiation and to a lesser extent plutonium-238, tritium and neutrons. Vital status and cause of death was determined through 2009. Standardized mortality ratios (SMRs) were computed for comparisons with the general population. Lifetime occupational doses from all places of employment were sought and incorporated into the analysis. Over 200,000 urine samples were analyzed to estimate radiation doses to body organs from polonium and other internally deposited radionuclides. Cox proportional hazards models were used to evaluate dose-response relationships for specific organs and tissues. Vital status was determined for 98.7% of the workers of which 3,681 had died compared with 4,073.9 expected (SMR 0.90; 95% CI 0.88-0.93). The mean dose from external radiation was 26.1 mSv (maximum 939.1 mSv) and the mean lung dose from external and internal radiation combined was 100.1 mSv (maximum 17.5 Sv). Among the 4,977 radiation workers, all cancers taken together (SMR 0.86; 95% CI 0.79-0.93), lung cancer (SMR 0.85; 95% CI 0.74-0.98), and other types of cancer were not significantly elevated. Cox regression analysis revealed a significant positive dose-response trend for esophageal cancer [relative risk (RR) and 95% confidence interval at 100 mSv of 1.54 (1.15-2.07)] and a

  20. Diagnosis and treatment of polonium poisoning.

    PubMed

    Jefferson, Robert D; Goans, Ronald E; Blain, Peter G; Thomas, Simon H L

    2009-05-01

    Interest in the clinical toxicology of (210)polonium ((210)Po) has been stimulated by the poisoning of Alexander Litvinenko in 2006. This article reviews the clinical features, diagnosis, and treatment of acute radiation syndrome (ARS) resulting from the ingestion of (210)Po. PHYSICAL CHARACTERISTICS: (210)Po is a high-energy alpha-emitter (radioactive half-life 138 days) that presents a radiation hazard only if taken into the body, for example, by ingestion, because of the low range of alpha particles in biological tissues. As a result, external contamination does not cause radiation sickness. Ingested (210)Po is concentrated initially in red blood cells and then the liver, kidneys, spleen, bone marrow, gastrointestinal (GI) tract, and gonads. (210)Po is excreted in urine, bile, sweat, and (possibly) breath and is also deposited in hair. After ingestion, unabsorbed (210)Po is present in the faeces. The elimination half-life in man is approximately 30-50 days. In the absence of medical treatment, the fatal oral amount is probably in the order of 10-30 microg. If the absorbed dose is sufficiently large (e.g., >0.7 Gy), (210)Po can cause ARS. This is characterized by a prodromal phase, in which nausea, vomiting, anorexia, lymphopenia, and sometimes diarrhea develop after exposure. Higher radiation doses cause a more rapid onset of symptoms and a more rapid reduction in lymphocyte count. The prodromal phase may be followed by a latent phase during which there is some clinical improvement. Subsequently, the characteristic bone marrow (0.7-10 Gy), GI (8-10 Gy), or cardiovascular/central nervous system syndromes (>20 Gy) develop, with the timing and pattern of features dependent on the systemic dose. The triad of early emesis followed by hair loss and bone marrow failure is typical of ARS. Those patients who do not recover die within weeks to months, whereas in those who survive, full recovery can take many months. Serial blood counts are important for assessing the rate

  1. Polonium, uranium and plutonium in the southern Baltic ecosystem

    NASA Astrophysics Data System (ADS)

    Skwarzec, B.

    1999-01-01

    This paper presents the results of the measurement of polonium, uranium and plutonium alpha radio-nuclides in seawater and biota of the southern Baltic ecosystem as well as the recognition of their accumulation processes in the trophic chain. Investigation of the polonium210Po and plutonium239+240Pu concentrations in Baltic biota revealed that these radionuclides are strongly accumulated by some species. Mean values of the bioconcentration factor (BCF) fell within the range 9·102 to 3.7·104. The Baltic Sea algae, benthic animals and fish concentrated uranium radioisotopes only to a small extent and mean BCF values for this element range from 1 to 55, which is several orders of magnitude lower than that for polonium and plutonium. Moreover, it was found that Baltic fish constitute an important source of polonium210Po for humans.

  2. Maps of Lunar Radon-222 and Polonium-210

    NASA Astrophysics Data System (ADS)

    Lawson, S. L.; Feldman, W. C.; Lawrence, D. J.; Moore, K. R.; Maurice, S.; Belian, R. D.; Binder, A. B.

    2002-03-01

    The LP Alpha Particle Spectrometer radon-222 map indicates that radon gas is presently emanating from the vicinity of craters Aristarchus and Kepler. The polonium-210 map indicates a variability in time and space of lunar gas release events.

  3. Polonium, uranium and plutonium in the southern Baltic ecosystem

    NASA Astrophysics Data System (ADS)

    Skwarzec, B.

    1999-01-01

    This paper presents the results of the measurement of polonium, uranium and plutonium alpha radio-nuclides in seawater and biota of the southern Baltic ecosystem as well as the recognition of their accumulation processes in the trophic chain. Investigation of the polonium210Po and plutonium239+240Pu concentrations in Baltic biota revealed that these radionuclides are strongly accumulated by some species. Mean values of the bioconcentration factor (BCF) fell within the range 9·102 to 3.7·104. The Baltic Sea algae, benthic animals and fish concentrated uranium radioisotopes only to a small extent and mean BCF values for this element range from 1 to 55, which is several orders of magnitude lower than that for polonium and plutonium. Moreover, it was found that Baltic fish constitute an important source of polonium210Po for humans.

  4. Calculation of weighted averages approach for the estimation of ping tolerance values

    USGS Publications Warehouse

    Silalom, S.; Carter, J.L.; Chantaramongkol, P.

    2010-01-01

    A biotic index was created and proposed as a tool to assess water quality in the Upper Mae Ping sub-watersheds. The Ping biotic index was calculated by utilizing Ping tolerance values. This paper presents the calculation of Ping tolerance values of the collected macroinvertebrates. Ping tolerance values were estimated by a weighted averages approach based on the abundance of macroinvertebrates and six chemical constituents that include conductivity, dissolved oxygen, biochemical oxygen demand, ammonia nitrogen, nitrate nitrogen and orthophosphate. Ping tolerance values range from 0 to 10. Macroinvertebrates assigned a 0 are very sensitive to organic pollution while macroinvertebrates assigned 10 are highly tolerant to pollution.

  5. Polonium 210Po in cigarettes produced in Poland.

    PubMed

    Skwarzec, B; Strumińska, D I; Borylo, A; Ulatowski, J

    2001-01-01

    This paper discusses the results of 210Po determinations in the fourteen most frequently smoked brands of cigarettes, which constitute over 80% of total cigarette consumption in Poland. The 210Po activity in the cigarette samples analysed (tobacco, ash, filter before and after smoking) were measured using alpha spectrometry (Canberra-Packard). The data indicates that there is considerable variation in the polonium content of these brands. The highest 210Po content per sample was found in the cheap "Popularne" brand (24.12 mBq), the lowest in "Caro" (4.23 mBq). There was also a large difference between the polonium remaining in the ash in comparison with its total content in the tobacco in all the brands (from 4.3% for "Golden American" to 71.0% for "Sobieski King-Size"). The analysis has demonstrated that filters absorbed only a small amount of the polonium contained in the tobacco. "Caro" cigarettes have the most efficient filter, retaining 25.1% of the polonium contained in the tobacco, but most filters absorbed only 0.1-7.2% of polonium. The daily inhalation of 210Po by Polish smokers who get through one pack per day ranges from 20 to 215 mBq, but people smoking two or more packs of "Popularne" brand will inhale over 430 mBq of polonium per day.

  6. Purification of polonium-210 using pyrochemical extraction

    SciTech Connect

    Wheelwright, E.J.; Swanson, J.L.; Myers, T.R.

    1980-05-01

    An efficient extraction process that does not utilize halides or organic solvents has been developed for the recovery and purification of /sup 210/Po. Polonium-210, produced in bismuth metal by neutron irradiation, is extracted from molten bismuth metal into molten NaOH in an unique 3-compartment contactor under an inert atmosphere. At a temperature of 450+-25/sup 0/C, and at a NaOH/Bi weight ratio of 0.044, five successive 60-minute extractions remove > 96% of the /sup 210/Po. Following phase separation and freezing, additional purification steps include dissolution of the solidified NaOH in HNO/sub 3/, recovery of /sup 210/Po from this solution by MnO/sub 2/ carrier precipitation, dissolution of the precipitate by H/sub 2/O/sub 2/ in HNO/sub 3/, and , finally, electrodeposition of /sup 210/Po onto platinum gauze.

  7. Phases of Polonium via Density Functional Theory

    NASA Astrophysics Data System (ADS)

    Verstraete, Matthieu J.

    2010-01-01

    The thermodynamical properties of the main phases of metallic polonium are examined using density functional theory. The exceptional nature of the solid-solid phase transition of α to β Po is underlined: it induces a lowering in symmetry, from cubic to rhombohedral, with increasing temperature. This is explained as the result of a delicate balance between bonding and entropic effects. Overall agreement with existing experimental data is good by state-of-the-art standards. The phonons of Po present Kohn anomalies, and it is shown that the effect of spin-orbit interactions is the inverse of that in normal metals: due to the nonspherical nature of the Fermi Surface, spin-orbit effects reduce nesting and harden most phonon frequencies.

  8. Polonium-210 levels in different environmental samples.

    PubMed

    Fonollosa, E; Peñalver, A; Aguilar, C; Borrull, F

    2015-12-01

    Polonium-210 is analysed in different samples which can be affected by the presence of a dicalcium phosphate plant (DCP). Particularly, it was determined in sludge samples from a drinking water treatment plant located downstream of the phosphate plant. From the obtained results, it was not possible to establish a correlation with the industrial activities carried out in the DCP plant since the measured activities were comparable to the reported in the literature for normal soils. This isotope was also monitored in different biota species (as mussels) taken also downstream of the DCP, and the potential risk of their ingestion by calculating the total effective doses was evaluated. As a result, it is important to highlight that the ingestion of these mussels does not constitute a risk for the population since the found doses were lower than the values published by UNSCEAR.

  9. Zero Benefit: Estimating the Effect of Zero Tolerance Discipline Polices on Racial Disparities in School Discipline

    ERIC Educational Resources Information Center

    Hoffman, Stephen

    2014-01-01

    This study estimates the effect of zero tolerance disciplinary policies on racial disparities in school discipline in an urban district. Capitalizing on a natural experiment, the abrupt expansion of zero tolerance discipline policies in a mid-sized urban school district, the study demonstrates that Black students in the district were…

  10. Zero Benefit: Estimating the Effect of Zero Tolerance Discipline Polices on Racial Disparities in School Discipline

    ERIC Educational Resources Information Center

    Hoffman, Stephen

    2014-01-01

    This study estimates the effect of zero tolerance disciplinary policies on racial disparities in school discipline in an urban district. Capitalizing on a natural experiment, the abrupt expansion of zero tolerance discipline policies in a mid-sized urban school district, the study demonstrates that Black students in the district were…

  11. Biomarkers in Fasting Serum to Estimate Glucose Tolerance, Insulin Sensitivity, and Insulin Secretion

    PubMed Central

    Goldfine, Allison B.; Gerwien, Robert W.; Kolberg, Janice A.; O’Shea, Sheila; Hamren, Sarah; Hein, Glenn P.; Xu, Xiaomei M.; Patti, Mary Elizabeth

    2014-01-01

    BACKGROUND Biomarkers for estimating reduced glucose tolerance, insulin sensitivity, or impaired insulin secretion would be clinically useful, since these physiologic measures are important in the pathogenesis of type 2 diabetes mellitus. METHODS We conducted a cross-sectional study in which 94 individuals, of whom 84 had 1 or more risk factors and 10 had no known risk factors for diabetes, underwent oral glucose tolerance testing. We measured 34 protein biomarkers associated with diabetes risk in 250-μL fasting serum samples. We applied multiple regression selection techniques to identify the most informative biomarkers and develop multivariate models to estimate glucose tolerance, insulin sensitivity, and insulin secretion. The ability of the glucose tolerance model to discriminate between diabetic individuals and those with impaired or normal glucose tolerance was evaluated by area under the ROC curve (AUC) analysis. RESULTS Of the at-risk participants, 25 (30%) were found to have impaired glucose tolerance, and 11 (13%) diabetes. Using molecular counting technology, we assessed multiple biomarkers with high accuracy in small volume samples. Multivariate biomarker models derived from fasting samples correlated strongly with 2-h postload glucose tolerance (R2 = 0.45, P < 0.0001), composite insulin sensitivity index (R2 = 0.91, P < 0.0001), and insulin secretion (R2 = 0.45, P < 0.0001). Additionally, the glucose tolerance model provided strong discrimination between diabetes vs impaired or normal glucose tolerance (AUC 0.89) and between diabetes and impaired glucose tolerance vs normal tolerance (AUC 0.78). CONCLUSIONS Biomarkers in fasting blood samples may be useful in estimating glucose tolerance, insulin sensitivity, and insulin secretion. PMID:21149503

  12. Occurrence and Geochemistry of Polonium-210 in Ground Water, Lahontan Valley, Nevada

    NASA Astrophysics Data System (ADS)

    Seiler, R. L.

    2008-12-01

    Substantially more gross alpha radioactivity than could be explained by the presence of uranium led to the discovery of polonium-210 in numerous domestic wells in Lahontan Valley, Nevada. Polonium-210 activities in water from 30 domestic wells ranged from <1 mBq/L to 2,800±95 mBq/L, with a median activity of 350 mBq/L. The source of the polonium is radioactive decay of uranium in sediments eroded from granitic rocks in the Sierra Nevada that has been transported into the valley. In the United States, polonium-210 activities greater than these have been reported for only a few wells in Florida and one well in Louisiana. Polonium-210 activities in ground water rarely exceed about 40 mBq/L because it strongly binds to sediments. On-going research in Lahontan Valley is aimed at identifying the biological and geological factors responsible for mobilization of the polonium. Preliminary results indicate that elevated polonium-210 activities (>400 mBq/L) are associated with anoxic (DO <0.1 mg/L), high pH (>8.5) water. Iron, but not manganese, increases monotonically with polonium. δ34SSO4 values indicate that sulfate reduction has occurred in all of the wells with elevated polonium-210 activities. However, sulfide concentrations were low (≤0.02 mg/L) in all but one well containing >130 mBq/L of polonium-210. This is consistent with previous investigations which have shown that polonium-210 is mobilized by sulfate- reducing bacteria and can remain in solution as long as sulfides do not accumulate. The polonium-210 in the water is not supported by lead-210. In Lahontan Valley ground water, uranium, radon, and polonium are the only significant alpha emitters. Radon and polonium activities are not statistically correlated and wells with elevated polonium-210 activities almost always have uranium concentrations <3 μg/L.

  13. Alkaline extraction of polonium from liquid lead bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Heinitz, S.; Neuhausen, J.; Schumann, D.

    2011-07-01

    The production of highly radiotoxic polonium isotopes poses serious safety concerns for the development of future nuclear systems cooled by lead bismuth eutectic (LBE). In this paper it is shown that polonium can be extracted efficiently from LBE using a mixture of alkaline metal hydroxides (NaOH + KOH) in a temperature range between 180 and 350 °C. The extraction ratio was analyzed for different temperatures, gas blankets and phase ratios. A strong dependence of the extraction performance on the redox properties of the cover gas was found. While hydrogen facilitates the removal of polonium, oxygen has a negative influence on the extraction. These findings open new possibilities to back up the safety of future LBE based nuclear facilities.

  14. [Polonium: the radioactive killer from tobacco smoke].

    PubMed

    Zagà, Vincenzo; Gattavecchia, Enrico

    2008-01-01

    Among all carcinogenic substances contained in tobacco smoke, Polonium 210 (Po-210), with a half-life of 138 days, is one of the most dangerous, by exerting a devastating, chronic, slow and progressive carcinogenesis activity. The main source of Po-210 in tobacco is represented by fertilizers (polyphosphates) containing radium-226 (Ra-222) which decades to plumb 210 (Pb-210). Through the thricomes Pb-210 is concentrated in the tobacco leaves, where it turns to Po-210, which at the cigarette combustion temperature (800-900 degrees C) reaches the gaseous state and it is absorbed by the micro particles released into tobacco smoke. Thus, smoke becomes radioactive in both its gaseous and corpuscular components and reaches the airways, where, particularly at the branches level and together with other substances, it exerts its carcinogenic activity, especially in those subjects with impaired respiratory mucosal clearance. The carcinogenic risk/one year lifetime of a smoker of 20 cigarettes per day is equivalent to that of undertaking 300 chest x-rays. It is calculated that Po-210 may be independently responsible of 4 lung cancers every 10,000 smokers. During cigarette's combustion, tobacco smoke is also released in the air, contributing to serious health risks for those exposed to passive smoke.

  15. A study of the mechanical and structural properties of polonium

    NASA Astrophysics Data System (ADS)

    Kraig, Robert E.; Roundy, David; Cohen, Marvin L.

    2004-02-01

    We have performed an ab initio study of the structure of polonium. By calculating total energies in a number of tetragonal lattice configurations, we have shown that the simple cubic structure is preferred by the system. The other two zero-stress structures, bcc and fcc, correspond to inflection points along this path. These calculations agree with experimental evidence that polonium is the only known element to assume the simple cubic structure at room temperature. We have found an LDA lattice constant of 3.28 Å, and we have obtained two of the elastic constants: C 11=113 GPa and C 12=28 GPa.

  16. Discovery of the thallium, lead, bismuth, and polonium isotopes

    NASA Astrophysics Data System (ADS)

    Fry, C.; Thoennessen, M.

    2013-05-01

    Forty-two thallium, forty-two lead, forty-one bismuth, and forty-two polonium isotopes have so far been observed; the discovery of these isotopes is described. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  17. Polonium in cigarette smoke and radiation exposure of lungs

    NASA Astrophysics Data System (ADS)

    Carvalho, Fernando P.; Oliveira, João M.

    2006-01-01

    Polonium (210Po), the most volatile of naturally-occurring radionuclides in plants, was analysed in three common brands of cigarettes produced in Portugal. The analyses were carried out on the unburned tobacco contained in cigarettes, on the ashes and butts of smoked cigarettes and on the mainstream smoke. 210Po in tobacco displays concentrations ranging from 3 to 37 mBq g-1, depending upon the cigarette brand. The 210Po activity remaining in the solid residue of a smoked cigarette varied from 0.3 to 4.9 mBq per cigarette, and the 210Po in the inhaled smoke varied from 2.6 to 28.9 mBq. In all brands of cigarettes tested, a large fraction of the 210Po content is not inhaled by the smoker and it is released into the atmosphere. Part of it may be inhaled by passive smokers. Depending upon the commercial brand and upon the presence or absence of a filter in the cigarette, 5 to 37 % of the 210Po in the cigarette can be inhaled by the smoker. Taking into account the average 210Po in surface air, the smoker of one pack of twenty cigarettes per day may inhale 50 times 210Po than a non smoker. Cigarette smoke contributes with 1.5 % to the daily rate of 210Po absorption into the blood, 0.39 Bq d-1, and, after systemic circulation it gives rise to a whole body radiation dose in the same proportion. However, in the smoker the deposition of 210Po in the lungs is much more elevated than normal and may originate an enhanced radiation exposure. Estimated dose to the lungs is presented and radiobiological effects of cigarette smoke are discussed.

  18. Evaluation of sample pretreatment methods for analysis of polonium isotopes in herbal medicines.

    PubMed

    Sreejith, Sathyapriya R; Nair, Madhu G; Rao, D D

    2014-12-01

    Herbal infusions like ayurvedic aristas are widely consumed by Indian population for good health. With increasing awareness about radiological assessment, an effort was made to assess the radioactivity concentration of naturally occurring radionuclides in herbal medicines. (210)Po is an important alpha particle emitter contributing to internal dose to man from ingestion. Though (210)Po can be spontaneously deposited on silver disk for alpha spectrometric measurements with less radiochemical step, great care has to be taken during the sample pretreatment step owing to the high volatility of polonium even at low temperatures. Aim of the study was to evaluate an appropriate sample pretreatment method for estimation of polonium in herbal medicines. (209)Po was used for radiochemical yield calculation. Conventional open vessel wet ashing, physical evaporation, freeze-drying and microwave digestion in a Teflon vessel were examined. The recovery ranged between 9 and 79%. The lowest recovery was obtained for the samples that were processed by open vessel digestion without any volume reduction. The recoveries were comparable for those samples that were freeze dried and subjected to HNO3 + HClO4 + H2O2 + HF acid digestion and microwave digested samples. (210)Po concentration in the samples ranged from 11.3 to 39.6 mBq/L. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Estimating the tolerance of species to the effects of global environmental change.

    PubMed

    Saavedra, Serguei; Rohr, Rudolf P; Dakos, Vasilis; Bascompte, Jordi

    2013-01-01

    Global environmental change is affecting species distribution and their interactions with other species. In particular, the main drivers of environmental change strongly affect the strength of interspecific interactions with considerable consequences for biodiversity. However, extrapolating the effects observed on pair-wise interactions to entire ecological networks is challenging. Here we propose a framework to estimate the tolerance to changes in the strength of mutualistic interaction that species in mutualistic networks can sustain before becoming extinct. We identify the scenarios where generalist species can be the least tolerant. We show that the least tolerant species across different scenarios do not appear to have uniquely common characteristics. Species' tolerance is extremely sensitive to the direction of change in the strength of mutualistic interaction, as well as to the observed mutualistic trade-offs between the number of partners and the strength of the interactions.

  20. Mortality Among Mound Workers Exposed to Polonium-210 and Other Sources of Radiation, 1944–1979

    DOE PAGES

    Boice, John D.; Cohen, Sarah S.; Mumma, Michael T.; ...

    2014-02-14

    Polonium-210 is a naturally occurring radioactive element that decays by emitting an alpha particle. It is in the air we breathe and also a component of tobacco smoke. Polonium-210 is used as an anti-static device in printing presses and gained widespread notoriety in 2006 after the poisoning and subsequent death of a Russian citizen in London. More is known about the lethal effects of polonium-210 at high doses than about late effects from low doses. In this paper, cancer mortality was examined among 7,270 workers at the Mound nuclear facility near Dayton, OH where polonium-210 was used (1944–1972) in combinationmore » with beryllium as a source of neutrons for triggering nuclear weapons. Other exposures included external gamma radiation and to a lesser extent plutonium-238, tritium and neutrons. Vital status and cause of death was determined through 2009. Standardized mortality ratios (SMRs) were computed for comparisons with the general population. Lifetime occupational doses from all places of employment were sought and incorporated into the analysis. Over 200,000 urine samples were analyzed to estimate radiation doses to body organs from polonium and other internally deposited radionuclides. Cox proportional hazards models were used to evaluate dose-response relationships for specific organs and tissues. Vital status was determined for 98.7% of the workers of which 3,681 had died compared with 4,073.9 expected (SMR 0.90; 95% CI 0.88–0.93). The mean dose from external radiation was 26.1 mSv (maximum 939.1 mSv) and the mean lung dose from external and internal radiation combined was 100.1 mSv (maximum 17.5 Sv). Among the 4,977 radiation workers, all cancers taken together (SMR 0.86; 95% CI 0.79–0.93), lung cancer (SMR 0.85; 95% CI 0.74–0.98), and other types of cancer were not significantly elevated. Cox regression analysis revealed a significant positive dose-response trend for esophageal cancer [relative risk (RR) and 95% confidence interval at 100 m

  1. Mortality Among Mound Workers Exposed to Polonium-210 and Other Sources of Radiation, 1944–1979

    SciTech Connect

    Boice, John D.; Cohen, Sarah S.; Mumma, Michael T.; Ellis, Elizabeth Dupree; Cragle, Donna L.; Eckerman, Keith F.; Wallace, Phillip W.; Chadda, Bandana; Sonderman, Jennifer S.; Wiggs, Laurie D.; Richter, Bonnie S.; Leggett, Richard W.

    2014-02-14

    Polonium-210 is a naturally occurring radioactive element that decays by emitting an alpha particle. It is in the air we breathe and also a component of tobacco smoke. Polonium-210 is used as an anti-static device in printing presses and gained widespread notoriety in 2006 after the poisoning and subsequent death of a Russian citizen in London. More is known about the lethal effects of polonium-210 at high doses than about late effects from low doses. In this paper, cancer mortality was examined among 7,270 workers at the Mound nuclear facility near Dayton, OH where polonium-210 was used (1944–1972) in combination with beryllium as a source of neutrons for triggering nuclear weapons. Other exposures included external gamma radiation and to a lesser extent plutonium-238, tritium and neutrons. Vital status and cause of death was determined through 2009. Standardized mortality ratios (SMRs) were computed for comparisons with the general population. Lifetime occupational doses from all places of employment were sought and incorporated into the analysis. Over 200,000 urine samples were analyzed to estimate radiation doses to body organs from polonium and other internally deposited radionuclides. Cox proportional hazards models were used to evaluate dose-response relationships for specific organs and tissues. Vital status was determined for 98.7% of the workers of which 3,681 had died compared with 4,073.9 expected (SMR 0.90; 95% CI 0.88–0.93). The mean dose from external radiation was 26.1 mSv (maximum 939.1 mSv) and the mean lung dose from external and internal radiation combined was 100.1 mSv (maximum 17.5 Sv). Among the 4,977 radiation workers, all cancers taken together (SMR 0.86; 95% CI 0.79–0.93), lung cancer (SMR 0.85; 95% CI 0.74–0.98), and other types of cancer were not significantly elevated. Cox regression analysis revealed a significant positive dose-response trend for esophageal cancer [relative risk (RR) and 95% confidence interval at 100 mSv of 1

  2. Determination of Polonium-210 in Mussels from the Adria Sea

    NASA Astrophysics Data System (ADS)

    Bylyku, Elida; Bode, Kozeta; Fisnka, Kujtim; Cfarku, Florinda

    2010-01-01

    The important role played by alpha radioactive nuclides in the marine radiation environment is already evident. The dominant contribution made by natural fall-out nuclide Polonium-210 to the alpha radioactivity of most marine organisms is very important. The common mussel Mytilus galloprovincialis is selected as unique bio monitor species to be analyzed. Samples are collected at the Adria Sea along the Albanian coast. A radiochemical procedure followed by alpha spectrometry measurement of 210Po is performed. The standard solution of 209Po is used as a yield tracer. Thin sources for alpha spectrometry measurements are prepared by spontaneous deposition of polonium on to silver disks from weakly acid solutions. The value of specific activity of 210Po vary between 200 to 400 Bq/kg dry and are in good agreement with the results found for 210Po in mussels from other countries in the Adria Sea.

  3. Graphs for Isotopes of 84-Po(Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides a graphic representation of nucleon separation energies and residual interaction parameters for isotopes of the chemical element 84-Po (Polonium, atomic number Z = 84).

  4. Evolution of collective motion in light polonium nuclei

    SciTech Connect

    Cizewski, J.A.; Ding, K.Y.; Fotiades, N.; McNabb, D.P.; Younes, W.; Davids, C.N.; Janssens, R.V.F.; Seweryniak, D.; Carpenter, M.P.; Amro, H.; Decrock, P.; Reiter, P.; Nisius, D.; Brown, L.T.; Fischer, S.; Lauritsen, T. Younes, W.; Leino, M.; Cocks, J.; Greenlees, P.; Helariutta, K.; Jones, P.; Juutinen, S.; Kankaanpauml, A.; Kettunen, H.; Kuusiniemi, P.; Muikku, M.; Rahkila, P.; Savelius, A.; Bingham, C.R.; Andreyev, A.

    1998-12-01

    The {gamma}-ray spectroscopy of even- and odd-mass isotopes of polonium have been studied using arrays of Ge detectors coupled to recoil-mass analyzers, including recoil-decay tagging techniques. The level energies and B(E2) branching ratios can be reproduced by theoretical frameworks which do not explicitly include proton particle-hole excitations across the Z=82 shell, conclusions in contrast to those deduced from alpha-decay measurements. {copyright} {ital 1998 American Institute of Physics.}

  5. Evolution of collective motion in light polonium nuclei.

    SciTech Connect

    Cizewski, J. A.

    1998-07-13

    The {gamma}-ray spectroscopy of even- and odd-mass isotopes of polonium have been studied using arrays of Ge detectors coupled to recoil-mass analyzers, including recoil-decay tagging techniques. The level energies and B(E2) branching ratios can be reproduced by theoretical frameworks which do not explicitly include proton particle-hole excitations across the Z = 82 shell, conclusions in contrast to those deduced from alpha-decay measurements.

  6. Collateral contamination concomitant to the polonium-210 poisoning of Mr Alexander Litvinenko.

    PubMed

    Harrison, John; Smith, Tracy; Fell, Tim; Smith, Jenny; Ham, George; Haylock, Richard; Hodgson, Alan; Etherington, George

    2017-07-20

    Mr Litvinenko died on 23 November 2006, having been poisoned with polonium-210 on 1 November, with evidence of a previous poisoning attempt during October 2006. Measurements of (210)Po in urine samples were made for a large number of people to determine whether they may have been contaminated. In the majority of cases, measured levels were attributable to the presence of (210)Po from normal dietary sources. For a small number of cases, elevated levels provided evidence of direct contamination associated with the poisonings. For one individual, while estimated doses were below thresholds for irreversible organ damage, a notably increased risk of cancer can be inferred. The use of the chelating agent, unithiol, to increase (210)Po excretion in this case was only moderately effective in reducing doses received.

  7. Hair as an indicator of the body content of polonium in humans: preliminary results from study of five male volunteers.

    PubMed

    Rääf, C L; Holstein, H; Holm, E; Roos, P

    2015-03-01

    The radionuclide (210)Po is of importance from a radiation protection view and has properties that cause special problems when attempting to determine the body content in humans. Estimates have traditionally been made from either urine and/or fecal samples, which require a time-consuming radiochemical preparation before alpha spectrometric determination. In order to find a more simple and less labor intensive method hair has been used as a bioindicator and investigated in this study. The relationship between intake and excretion in hair has been estimated in five volunteers who ingested radioactive polonium ((209)Po as a bio-tracer for (210)Po) in well determined quantities. Four of the volunteers were given 5-10 Bq (209)Po in a single intake (acute intake) and one volunteer has ingested a daily intake of 58.7 mBq (209)Po for a period of 180 d. Human hair was found to reflect the daily clearance of ingested polonium peaking at 0.001-0.01% d(-1) of the ingested amount, thereafter decreasing mono-exponentially, corresponding to a biological half-time of 10-20 days. For the case of protracted intake a mono-exponential build-up was observed with a half-time of 40 ± 5 d. In addition, after cessation of intake, a short-term component (74%) with a biological half-time of 16 ± 4 d, and a long-term component (26%) with a half-time of 93 ± 53 d were observed. It is concluded that hair can be used to detect not only the amount of ingested polonium but also whether the intake was protracted or acute. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Polonium aspects associated with the use of lead-lithium blankets in fusion applications

    SciTech Connect

    Hoffman, N.J.; Blink, J.A.; Meier, W.R.; Murray, K.A.; Vogelsang, W.F.

    1985-07-01

    Polonium, an alpha-emitting sulfur-like element, is formed by neutron irradiation of lead or bismuth impurity in lead. Design studies of both the Pulse*Star inertial confinement fusion (ICF) reactor and the MARS mirror fusion reactor postulated use of 83Pb-17Li melt as the tritium breeding blanket and coolant. Comparison of the amounts of polonium in the melt at plant shutdown indicated that Pulse*Star would have a far higher level of polonium in the melt. Neutronic considerations and the polonium distribution between the vacuum cleanup system and 83Pb-17Li melt for the two reactors are explored in this paper. Sample neutronics runs showed that the codes used by each design team were not the source of the difference in polonium content.

  9. A robust adaptive nonlinear fault-tolerant controller via norm estimation for reusable launch vehicles

    NASA Astrophysics Data System (ADS)

    Hu, Chaofang; Gao, Zhifei; Ren, Yanli; Liu, Yunbing

    2016-11-01

    In this paper, a reusable launch vehicle (RLV) attitude control problem with actuator faults is addressed via the robust adaptive nonlinear fault-tolerant control (FTC) with norm estimation. Firstly, the accurate tracking task of attitude angles in the presence of parameter uncertainties and external disturbances is considered. A fault-free controller is proposed using dynamic surface control (DSC) combined with fuzzy adaptive approach. Furthermore, the minimal learning parameter strategy via norm estimation technique is introduced to reduce the multi-parameter adaptive computation burden of fuzzy approximation of the lump uncertainties. Secondly, a compensation controller is designed to handle the partial loss fault of actuator effectiveness. The unknown maximum eigenvalue of actuator efficiency loss factors is estimated online. Moreover, stability analysis guarantees that all signals of the closed-loop control system are semi-global uniformly ultimately bounded. Finally, illustrative simulations show the effectiveness of the proposed method.

  10. A vapor-pressure study of the systems formed by polonium with palladium and iridium

    SciTech Connect

    Abakumou, A.S.; Khokhlou, A.D.; Malysheu, M.L.; Reznikova, N.F.

    1985-11-01

    Direct thermal vacuum synthesis shows that polonium vapor does not react with iridium when they are heated together to 1000/sup 0/C. Polonium vapor begins to be absorbed appreciably by palladium at 340-350/sup 0/C. The radiotensimetric method has been used in examining the thermal stabilities of polonium-palladium comounds, which has shown that there are three intermetallides PdPo, Pd/sub 2/Po, and Pd/sub 3/Po, which dissociate to release elemental polonium. The dissociation temperature increases as the polonium content of the compound decreases and is in the range 390-700/sup 0/C. The temperature dependence of the polonium vapor pressure in the dissociation is described by the following: PdPo log P /SUB Pa/ = (7.31 + or - 0.08) -- (4520 + or -40)/T, and at 460580/sup 0/C, ..delta..H = 86.3 + or - 0.7 kJ/mol; Pd/sub 2/Po log P /SUB Pa/ = (7.42 + or - 0.01) -- (6080 + or 10)/T at 725900/sup 0/C, ..delta..H = 116 + or - 0.2 kJ/mol; Pd/sub 3/Po log P /SUB Pa/ = (9.18 + or - 0.01) -- (8620 + or 1000/sup 0/C, ..delta..H = 164 + or - 1 kJ/mol. The properties of these compounds are compared with those of the corresponding tellurides and of the polonium-nickel and poloniumplatinum systems.

  11. Atomic Mass and Nuclear Binding Energy for Po-280 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-280 (Polonium, atomic number Z = 84, mass number A = 280).

  12. Atomic Mass and Nuclear Binding Energy for Po-282 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-282 (Polonium, atomic number Z = 84, mass number A = 282).

  13. Atomic Mass and Nuclear Binding Energy for Po-274 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-274 (Polonium, atomic number Z = 84, mass number A = 274).

  14. Atomic Mass and Nuclear Binding Energy for Po-275 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-275 (Polonium, atomic number Z = 84, mass number A = 275).

  15. Atomic Mass and Nuclear Binding Energy for Po-276 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-276 (Polonium, atomic number Z = 84, mass number A = 276).

  16. Atomic Mass and Nuclear Binding Energy for Po-278 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-278 (Polonium, atomic number Z = 84, mass number A = 278).

  17. Atomic Mass and Nuclear Binding Energy for Po-270 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-270 (Polonium, atomic number Z = 84, mass number A = 270).

  18. Atomic Mass and Nuclear Binding Energy for Po-269 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-269 (Polonium, atomic number Z = 84, mass number A = 269).

  19. Atomic Mass and Nuclear Binding Energy for Po-284 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-284 (Polonium, atomic number Z = 84, mass number A = 284).

  20. Atomic Mass and Nuclear Binding Energy for Po-273 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-273 (Polonium, atomic number Z = 84, mass number A = 273).

  1. Atomic Mass and Nuclear Binding Energy for Po-283 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-283 (Polonium, atomic number Z = 84, mass number A = 283).

  2. Atomic Mass and Nuclear Binding Energy for Po-271 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-271 (Polonium, atomic number Z = 84, mass number A = 271).

  3. Atomic Mass and Nuclear Binding Energy for Po-272 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-272 (Polonium, atomic number Z = 84, mass number A = 272).

  4. Atomic Mass and Nuclear Binding Energy for Po-277 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-277 (Polonium, atomic number Z = 84, mass number A = 277).

  5. Atomic Mass and Nuclear Binding Energy for Po-279 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-279 (Polonium, atomic number Z = 84, mass number A = 279).

  6. Atomic Mass and Nuclear Binding Energy for Po-281 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-281 (Polonium, atomic number Z = 84, mass number A = 281).

  7. The sorption of polonium, actinium and protactinium onto geological materials

    SciTech Connect

    Baston, G.M.N.; Berry, J.A.; Brownsword, M.; Heath, T.G.; Ilett, D.J.; McCrohon, R.; Tweed, C.J.; Yui, M.

    1999-07-01

    This paper describes a combined experimental and modeling program of generic sorption studies to increase confidence in the performance assessment for a potential high-level radioactive waste repository in Japan. The sorption of polonium, actinium and protactinium onto geological materials has been investigated. Sorption of these radioelements onto bentonite, tuff and granodiorite from equilibrated de-ionized water was studied under reducing conditions at room temperature. In addition, the sorption of actinium and protactinium was investigated at 60 C. Thermodynamic chemical modeling was carried out to aid interpretation of the results.

  8. Atomic Mass and Nuclear Binding Energy for Po-210 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-210 (Polonium, atomic number Z = 84, mass number A = 210).

  9. Atomic Mass and Nuclear Binding Energy for Po-211 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-211 (Polonium, atomic number Z = 84, mass number A = 211).

  10. Atomic Mass and Nuclear Binding Energy for Po-268 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-268 (Polonium, atomic number Z = 84, mass number A = 268).

  11. Global error estimation based on the tolerance proportionality for some adaptive Runge-Kutta codes

    NASA Astrophysics Data System (ADS)

    Calvo, M.; González-Pinto, S.; Montijano, J. I.

    2008-09-01

    Modern codes for the numerical solution of Initial Value Problems (IVPs) in ODEs are based in adaptive methods that, for a user supplied tolerance [delta], attempt to advance the integration selecting the size of each step so that some measure of the local error is [similar, equals][delta]. Although this policy does not ensure that the global errors are under the prescribed tolerance, after the early studies of Stetter [Considerations concerning a theory for ODE-solvers, in: R. Burlisch, R.D. Grigorieff, J. Schröder (Eds.), Numerical Treatment of Differential Equations, Proceedings of Oberwolfach, 1976, Lecture Notes in Mathematics, vol. 631, Springer, Berlin, 1978, pp. 188-200; Tolerance proportionality in ODE codes, in: R. März (Ed.), Proceedings of the Second Conference on Numerical Treatment of Ordinary Differential Equations, Humbold University, Berlin, 1980, pp. 109-123] and the extensions of Higham [Global error versus tolerance for explicit Runge-Kutta methods, IMA J. Numer. Anal. 11 (1991) 457-480; The tolerance proportionality of adaptive ODE solvers, J. Comput. Appl. Math. 45 (1993) 227-236; The reliability of standard local error control algorithms for initial value ordinary differential equations, in: Proceedings: The Quality of Numerical Software: Assessment and Enhancement, IFIP Series, Springer, Berlin, 1997], it has been proved that in many existing explicit Runge-Kutta codes the global errors behave asymptotically as some rational power of [delta]. This step-size policy, for a given IVP, determines at each grid point tn a new step-size hn+1=h(tn;[delta]) so that h(t;[delta]) is a continuous function of t. In this paper a study of the tolerance proportionality property under a discontinuous step-size policy that does not allow to change the size of the step if the step-size ratio between two consecutive steps is close to unity is carried out. This theory is applied to obtain global error estimations in a few problems that have been solved with

  12. Polonium-210 poisoning: a first-hand account.

    PubMed

    Nathwani, Amit C; Down, James F; Goldstone, John; Yassin, James; Dargan, Paul I; Virchis, Andres; Gent, Nick; Lloyd, David; Harrison, John D

    2016-09-10

    Polonium-210 ((210)Po) gained widespread notoriety after the poisoning and subsequent death of Mr Alexander Litvinenko in London, UK, in 2006. Exposure to (210)Po resulted initially in a clinical course that was indistinguishable from infection or exposure to chemical toxins, such as thallium. A 43-year-old man presented to his local hospital with acute abdominal pain, diarrhoea, and vomiting, and was admitted to the hospital because of dehydration and persistent gastrointestinal symptoms. He was initially diagnosed with gastroenteritis and treated with antibiotics. Clostridium difficile toxin was subsequently detected in his stools, which is when he first raised the possibility of being poisoned and revealed his background and former identity, having been admitted under a new identity with which he had been provided on being granted asylum in the UK. Within 6 days, the patient had developed thrombocytopenia and neutropenia, which was initially thought to be drug induced. By 2 weeks, in addition to bone marrow failure, he had evidence of alopecia and mucositis. Thallium poisoning was suspected and investigated but ultimately dismissed because blood levels of thallium, although raised, were lower than toxic concentrations. The patient continued to deteriorate and within 3 weeks had developed multiple organ failure requiring ventilation, haemofiltration, and cardiac support, associated with a drop in consciousness. On the 23rd day after he first became ill, he suffered a pulseless electrical activity cardiorespiratory arrest from which he could not be resuscitated and was pronounced dead. Urine analysis using gamma-ray spectroscopy on day 22 showed a characteristic 803 keV photon emission, raising the possibility of (210)Po poisoning. Results of confirmatory analysis that became available after the patient's death established the presence of (210)Po at concentrations about 10(9)-times higher than normal background levels. Post-mortem tissue analyses showed autolysis

  13. Superconductivity in α-polonium at the reduced volume

    NASA Astrophysics Data System (ADS)

    Szczęśniak, R.; Durajski, A. P.; Pach, P. W.

    2014-02-01

    The paper discusses the thermodynamic properties of the superconducting state that gets induced in the α phase of polonium at the reduced volume (V /Vexp = 0.93). It has been shown that the critical temperature (TC) is equal to 7.11 K, if the assumed value of the Coulomb pseudopotential equals 0.1. Then, the thermodynamic critical field (HC) has been calculated, as well as the specific heat in the superconducting state (CS) and in the normal state (CN). It has been proven that the values of the dimensionless ratios RH ≡TCCN(TC) / HC2(0) and RC ≡ ΔC(TC) /CN(TC) differ significantly from the expectations of the BCS theory. In particular, RH = 0.147 and RC = 2.34. In the next step, the order parameter (Δ) and the electron effective mass have been calculated. It has been found that the ratio of the energy gap to the critical temperature significantly exceeds the value predicted by the BCS model: RΔ ≡ 2 Δ(0) /kBTC = 4.12. The electron effective mass is high and reaches its maximum equal to 2.191me at the critical temperature, where the parameter me denotes the electron band mass. Nevertheless, some recent papers show that α-polonium becomes unstable for V /Vexp lower or equal to 0.97. In this case, our study relates to the unstable hypothetical phase.

  14. Bioaccumulation of polonium 210Po in marine birds.

    PubMed

    Skwarzec, B; Fabisiak, J

    2007-01-01

    The aim of this work was to determine the 210Po content in marine birds which permanently or temporally live in the Polish part of the Baltic Sea. We chose 11 species of sea birds: three species permanently residing at southern Baltic Sea, four species of wintering birds and three species of migrating birds. The results show that the polonium is non-uniformly distributed in the marine birds. The highest activities of 210Po were observed in feathers, muscles and liver and the lowest in skin and skeleton. Species of birds that eat crustaceans, molluscs, fish and plants (long-tailed duck Clangula hyemalis, white-winged scoter Melanitta fusca) accumulated more polonium than species that eat mainly fish (great cormorant Phalacrocorax carbo, common guillemot Uria aalge) or plants (tufted duck Aythya fuligula). Moreover, about 63% of the 210Po that was located in feathers of razorbil (Alca torda) and long-tailed duck (C. hyemalis) was apparently adsorbed, suggesting an external source such as the air. It means that the adsorption of 210Po on the feather surface may be an important transfer from air to water.

  15. Tissue decorporation of polonium-210 in rats by DMPA

    SciTech Connect

    Aposhian, H.V.; Dart, R.C.; Aposhian, M.M.; Dawson, B.V.

    1987-11-01

    Polonium-210 exposures, although rare, have occurred due to accidents in nuclear working environments. This alpha emitting radioactive element can bind thiols and thiol-containing proteins in vivo. Since thiol-containing chelating agents compete with many thiols for heavy metals, a number of these chelating agents have been investigated as protective agents against the lethal effects of /sup 210/Po and as tissue decorporating agents for it. Rats given /sup 210/Po (40 microCi/kg) ip had a median survival time (mst) of 39 days. The mst was increased to 106 days when N-(2,3-dimercaptopropyl)phthalamidic acid (DMPA), meso-dimercaptosuccinic acid (DMSA) or the Na salt of 2,3-dimercapto-1-propanesulfonic acid (DMPS) was administered sc (p less than .002). Decorporation studies were performed by giving rats /sup 210/Po (0.4 microCi) sc, followed by a series of thiol injections beginning one hour later. After 21 days, kidney levels of /sup 210/Po in rats given DMPA were only 28% of those of the untreated controls and significantly lower than those receiving DMSA, DMPS, N-acetyl-L-cysteine, or WR2721. After DMPA treatment, the /sup 210/Po levels of the spleen were 25% of the saline-treated control. DMPA appears to be a new and consistent decorporating agent for polonium-210.

  16. The experience in handling of lead-bismuth coolant contaminated by Polonium-210

    SciTech Connect

    Pankratov, D.V.; Gromov, B.F.; Solodjankin, M.A.

    1993-12-31

    During exploitation of lead-bismuth cooled reactors a wide experience in handling of radioactive coolant containing polonium has been gained. By 1990 total time of this reactor operation has reached approximately 60 reactor years.

  17. Waking a sleeping giant: the tobacco industry's response to the polonium-210 issue.

    PubMed

    Muggli, Monique E; Ebbert, Jon O; Robertson, Channing; Hurt, Richard D

    2008-09-01

    The major tobacco manufacturers discovered that polonium was part of tobacco and tobacco smoke more than 40 years ago and attempted, but failed, to remove this radioactive substance from their products. Internal tobacco industry documents reveal that the companies suppressed publication of their own internal research to avoid heightening the public's awareness of radioactivity in cigarettes. Tobacco companies continue to minimize their knowledge about polonium-210 in cigarettes in smoking and health litigation. Cigarette packs should carry a radiation-exposure warning label.

  18. Estimation of probability of failure for damage-tolerant aerospace structures

    NASA Astrophysics Data System (ADS)

    Halbert, Keith

    The majority of aircraft structures are designed to be damage-tolerant such that safe operation can continue in the presence of minor damage. It is necessary to schedule inspections so that minor damage can be found and repaired. It is generally not possible to perform structural inspections prior to every flight. The scheduling is traditionally accomplished through a deterministic set of methods referred to as Damage Tolerance Analysis (DTA). DTA has proven to produce safe aircraft but does not provide estimates of the probability of failure of future flights or the probability of repair of future inspections. Without these estimates maintenance costs cannot be accurately predicted. Also, estimation of failure probabilities is now a regulatory requirement for some aircraft. The set of methods concerned with the probabilistic formulation of this problem are collectively referred to as Probabilistic Damage Tolerance Analysis (PDTA). The goal of PDTA is to control the failure probability while holding maintenance costs to a reasonable level. This work focuses specifically on PDTA for fatigue cracking of metallic aircraft structures. The growth of a crack (or cracks) must be modeled using all available data and engineering knowledge. The length of a crack can be assessed only indirectly through evidence such as non-destructive inspection results, failures or lack of failures, and the observed severity of usage of the structure. The current set of industry PDTA tools are lacking in several ways: they may in some cases yield poor estimates of failure probabilities, they cannot realistically represent the variety of possible failure and maintenance scenarios, and they do not allow for model updates which incorporate observed evidence. A PDTA modeling methodology must be flexible enough to estimate accurately the failure and repair probabilities under a variety of maintenance scenarios, and be capable of incorporating observed evidence as it becomes available. This

  19. The Polonium brief: a hidden history of cancer, radiation, and the tobacco industry.

    PubMed

    Rego, Brianna

    2009-09-01

    The first scientific paper on polonium-210 in tobacco was published in 1964, and in the following decades there would be more research linking radioisotopes in cigarettes with lung cancer in smokers. While external scientists worked to determine whether polonium could be a cause of lung cancer, industry scientists silently pursued similar work with the goal of protecting business interests should the polonium problem ever become public. Despite forty years of research suggesting that polonium is a leading carcinogen in tobacco, the manufacturers have not made a definitive move to reduce the concentration of radioactive isotopes in cigarettes. The polonium story therefore presents yet another chapter in the long tradition of industry use of science and scientific authority in an effort to thwart disease prevention. The impressive extent to which tobacco manufacturers understood the hazards of polonium and the high executive level at which the problem and potential solutions were discussed within the industry are exposed here by means of internal documents made available through litigation.

  20. Noise-tolerant model selection and parameter estimation for complex networks

    NASA Astrophysics Data System (ADS)

    Aliakbary, Sadegh; Motallebi, Sadegh; Rashidian, Sina; Habibi, Jafar; Movaghar, Ali

    2015-06-01

    Real networks often exhibit nontrivial topological features that do not occur in random graphs. The need for synthesizing realistic networks has resulted in development of various network models. In this paper, we address the problem of selecting and calibrating the model that best fits a given target network. The existing model fitting approaches mostly suffer from sensitivity to network perturbations, lack of the parameter estimation component, dependency on the size of the networks, and low accuracy. To overcome these limitations, we considered a broad range of network features and employed machine learning techniques such as genetic algorithms, distance metric learning, nearest neighbor classification, and artificial neural networks. Our proposed method, which is named ModelFit, outperforms the state-of-the-art baselines with respect to accuracy and noise tolerance in different network datasets.

  1. The Total Deviation Index estimated by Tolerance Intervals to evaluate the concordance of measurement devices

    PubMed Central

    2010-01-01

    Background In an agreement assay, it is of interest to evaluate the degree of agreement between the different methods (devices, instruments or observers) used to measure the same characteristic. We propose in this study a technical simplification for inference about the total deviation index (TDI) estimate to assess agreement between two devices of normally-distributed measurements and describe its utility to evaluate inter- and intra-rater agreement if more than one reading per subject is available for each device. Methods We propose to estimate the TDI by constructing a probability interval of the difference in paired measurements between devices, and thereafter, we derive a tolerance interval (TI) procedure as a natural way to make inferences about probability limit estimates. We also describe how the proposed method can be used to compute bounds of the coverage probability. Results The approach is illustrated in a real case example where the agreement between two instruments, a handle mercury sphygmomanometer device and an OMRON 711 automatic device, is assessed in a sample of 384 subjects where measures of systolic blood pressure were taken twice by each device. A simulation study procedure is implemented to evaluate and compare the accuracy of the approach to two already established methods, showing that the TI approximation produces accurate empirical confidence levels which are reasonably close to the nominal confidence level. Conclusions The method proposed is straightforward since the TDI estimate is derived directly from a probability interval of a normally-distributed variable in its original scale, without further transformations. Thereafter, a natural way of making inferences about this estimate is to derive the appropriate TI. Constructions of TI based on normal populations are implemented in most standard statistical packages, thus making it simpler for any practitioner to implement our proposal to assess agreement. PMID:20377875

  2. Polonium-210 poisoning in London: hypochondriasis and public health.

    PubMed

    Morgan, Oliver W; Page, Lisa; Forrester, Sarah; Maguire, Helen

    2008-01-01

    In November 2006, a Russian dissident died from radioactive Polonium-210 (210Po) poisoning in London. Providing reassuring messages during a public health incident may be ineffective for individuals with high health anxiety (hypochondriasis). Members of the public who called a 24-hour telephone helpline were offered a follow-up call by a health protection specialist for reassurance. A psychiatrist attempted to contact those callers who were unable to be reassured by the health protection specialist. Of 872 individuals contacted for reassurance, seven (0.6%) could not be reassured. The psychiatrist contacted four of these individuals. Three had a history of health-related anxiety and two attributed somatic symptoms to 210Po exposure. For individuals with hypochondriasis, reassurance during major public health incidents may be ineffective. Having a psychiatrist available was helpful in managing individuals with excessive health anxiety.

  3. Fatigue life estimation procedures for the endurance of a cardiac valve prosthesis: stress/life and damage-tolerant analyses.

    PubMed

    Ritchie, R O; Lubock, P

    1986-05-01

    Projected fatigue life analyses are performed to estimate the endurance of a cardiac valve prosthesis under physiological environmental and mechanical conditions. The analyses are conducted using both the classical stress-strain/life and the fracture mechanics-based damage-tolerant approaches, and provide estimates of expected life in terms of initial flaw sizes which may pre-exist in the metal prior to the valve entering service. The damage-tolerant analysis further is supplemented by consideration of the question of "short cracks," which represents a developing area in metal fatigue research, not commonly applied to data in standard engineering design practice.

  4. Disturbance observer based fault estimation and dynamic output feedback fault tolerant control for fuzzy systems with local nonlinear models.

    PubMed

    Han, Jian; Zhang, Huaguang; Wang, Yingchun; Liu, Yang

    2015-11-01

    This paper addresses the problems of fault estimation (FE) and fault tolerant control (FTC) for fuzzy systems with local nonlinear models, external disturbances, sensor and actuator faults, simultaneously. Disturbance observer (DO) and FE observer are designed, simultaneously. Compared with the existing results, the proposed observer is with a wider application range. Using the estimation information, a novel fuzzy dynamic output feedback fault tolerant controller (DOFFTC) is designed. The controller can be used for the fuzzy systems with unmeasurable local nonlinear models, mismatched input disturbances, and measurement output affecting by sensor faults and disturbances. At last, the simulation shows the effectiveness of the proposed methods.

  5. Detection of Polonium-210 on Spirit Dust Magnets and Implications for the Global Martian Dust Cycle

    NASA Astrophysics Data System (ADS)

    Wong, R.; Meslin, P.; Sabroux, J.; Madsen, M. B.; Pineau, J.; Richon, P.

    2013-12-01

    The radioactivity of airborne aerosols, which originates from the attachment of radionuclides produced by radon disintegration, Galactic Cosmic Rays (GCR) or anthropogenic activities, especially fallouts from nuclear weapons testing, can be used to measure the residence time of these aerosols in the atmosphere and their deposition rate. It is also used to characterize soils erosion rates (Matissof et al., 2002) or to investigate the origin of desert rock varnish (Hodge et al., 2005), to name only a few terrestrial applications. A translation of these nuclear methods to the Martian atmosphere, which is characterized by a very active dust cycle, is tempting, and has the potential to offer a unique insight into the present-day recycling of the Martian surface. This approach is made possible by two facts: 1) the presence of radon in the Martian atmosphere, which produces long-lived radioactive decay products, in particular polonium-210, and whose abundance can be indirectly inferred by gamma ray spectrometry from orbit using Mars Odyssey Gamma Ray Spectrometer (GRS) (Meslin et al., 2012); 2) the presence at the surface of Mars of two Alpha Particle X-Ray Spectrometers (APXS), onboard Opportunity and Spirit Mars Exploration Rovers, whose energy range (in the alpha mode) very fortuitously happens to include the energy of alpha particles emitted by the decay of polonium-210. The long half-life of this radionuclide is such that it is almost entirely attached to the particles that have been in suspension in the atmosphere, especially those characterized by a large specific surface area or by a long atmospheric residence time. It can therefore be used as a tracer of the dust cycle. An analysis of the alpha spectra acquired on the dust Capture and Filter magnets of the Spirit rover confirms results obtained by Meslin et al. (2006) that the Martian dust is radioactive w/r to polonium-210, thereby extending Opportunity's result to a global scale. This result enables us to

  6. Noise tolerance of algorithms for estimating chlorophyll a concentration in turbid waters.

    PubMed

    Chen, Jun

    2014-04-01

    The accuracy and noise tolerance of 13 global models and 5 Case II chlorophyll a (chl a) retrieval models were evaluated using three dataset. It was found that if 5% input noise related to atmospheric correction is considered, then the uncertainty associated with noise tolerance varied from 5.5% to 55.6%, and these uncertainties generally accounts for 15.63% to 24.75% of the total uncertainty. This observation suggests that an optimal algorithm not only should have a strong chl a concentration prediction ability but also should possess high insensitivity to the noise of remote-sensing imagery. The accuracy evaluations of chl a models were based on comparisons of chl a predicted models with chl a concentration measured analytically for field measurements. The results indicate that none of the selected chl a estimation algorithms provide accurate retrievals of chl a in turbid waters. This may be attributed to the strong optical influence of organic and inorganic matter at the blue green range, and the non-negligible of non-organic matter absorption at the red and near-infrared ranges. In order to solve this problem, the chl a concentration retrieval models must be further optimized. After being optimized using the empirical optimized method constructed in this paper, a single parameterized NDCI (normalized difference chl a index) model produces accurate retrievals in the Yellow River Estuary, Taihu Lake and Chesapeake Bay. If 5% input noise associated with residual uncertainty 0of atmospheric correction is taken into account, the model produces only 29.96% uncertainty for the remote sensing of chl a concentration in these three turbid waters.

  7. Review of chemical and radiotoxicological properties of polonium for internal contamination purposes

    SciTech Connect

    Ansoborlo, Eric; Berard, Philippe; Den Auwer, Christophe; Leggett, Richard Wayne; Menetrier, Florence; Younes, Ali; Montavon, Gilles; Moisy, Phillipe

    2012-01-01

    The discovery of polonium (Po) was first published in July 1898 by P. and M. Curie. It was the first element to be discovered by the radiochemical method. Polonium can be considered as a famous but neglected element: only a few studies of polonium chemistry have been published, mostly between 1950 and 1990. The recent (2006) event in which 2106 Po evidently was used as a poison to kill A. Litvinenko has raised new interest in polonium. 2011 being the 100th 8 anniversary of Marie Curie Nobel Prize in Chemistry, the aim of this paper is to review several aspect of polonium linked to its chemical properties and its radiotoxicity, including : i) its radiochemistry and interaction with matter; ii) its main sources and uses; iii) its physico-chemical properties; iv) its main analytical methods; v) its background exposure risk in water, food, and other environmental media; vi) its biokinetics and distribution following inhalation, ingestion and wound contamination; vii) its dosimetry and viii) treatments available (decorporation) in case of internal contamination.

  8. Ab initio study of the trapping of polonium on noble metals

    NASA Astrophysics Data System (ADS)

    Rijpstra, Kim; Van Yperen-De Deyne, Andy; Maugeri, Emilio Andrea; Neuhausen, Jörg; Waroquier, Michel; Van Speybroeck, Veronique; Cottenier, Stefaan

    2016-04-01

    In the future MYRRHA reactor, lead bismuth eutectic (LBE) will be used both as coolant and as spallation target. Due to the high neutron flux a small fraction of the bismuth will transmute to radiotoxic 210Po. Part of this radiotoxic element will evaporate into the gas above the coolant. Extracting it from the gas phase is necessary to ensure a safe handling of the reactor. An issue in the development of suitable filters is the lack of accurate knowledge on the chemical interaction between a candidate filter material and either elemental polonium or polonium containing molecules. Experimental work on this topic is complicated by the high radiotoxicity of polonium. Therefore, we present in this paper a first-principles study on the adsorption of polonium on noble metals as filter materials. The adsorption of monoatomic Po is considered on the candidate filter materials palladium, platinum, silver and gold. The case of the gold filter is looked upon in more detail by examining how bismuth pollution affects its capability to capture polonium and by studying the adsorption of the heavy diatomic molecules Po2, PoBi and PoPb on this gold filter.

  9. Review of chemical and radiotoxicological properties of polonium for internal contamination purposes.

    PubMed

    Ansoborlo, Eric; Berard, Philippe; Den Auwer, Christophe; Leggett, Rich; Menetrier, Florence; Younes, Ali; Montavon, Gilles; Moisy, Philippe

    2012-08-20

    The discovery of polonium (Po) was first published in July, 1898 by P. Curie and M. Curie. It was the first element to be discovered by the radiochemical method. Polonium can be considered as a famous but neglected element: only a few studies of polonium chemistry have been published, mostly between 1950 and 1990. The recent (2006) event in which (210)Po evidently was used as a poison to kill A. Litvinenko has raised new interest in polonium. 2011 being the 100th anniversary of the Marie Curie Nobel Prize in Chemistry, the aim of this review is to look at the several aspects of polonium linked to its chemical properties and its radiotoxicity, including (i) its radiochemistry and interaction with matter; (ii) its main sources and uses; (iii) its physicochemical properties; (iv) its main analytical methods; (v) its background exposure risk in water, food, and other environmental media; (vi) its biokinetics and distribution following inhalation, ingestion, and wound contamination; (vii) its dosimetry; and (viii) treatments available (decorporation) in case of internal contamination.

  10. Lung cancer: is the increasing incidence due to radioactive polonium in cigarettes

    SciTech Connect

    Marmorstein, J.

    1986-02-01

    This paper presents clinical, experimental, and epidemiologic evidence to help explain the rapidly increasing incidence of primary lung cancer, with recently observed reversal in leading cell type from squamous cell to adenocarcinoma. It postulates that this may be due to changes in modern cigarettes, with or without filters, which allow inhalation of increased amounts of radioactive lead and polonium and decreased amounts of benzopyrene. This hypothesis is based upon measurements of increased concentrations of radioactive polonium in the lungs of cigarette smokers, in modern tobaccos grown since 1950, and in high-phosphate fertilizers used for tobacco farming in industrialized countries. Critical support for this thesis is based upon experimental animal studies in which lung cancers that resemble adenocarcinomas are induced with as little as 15 rads of radioactive polonium, equal to one fifth the dosage inhaled by cigarette smokers who average two packs a day during a 25-year period.

  11. Volatile dimethyl polonium produced by aerobic marine microorganisms.

    PubMed

    Bahrou, Andrew S; Ollivier, Patrick R L; Hanson, Thomas E; Tessier, Emmanuel; Amouroux, David; Church, Thomas M

    2012-10-16

    The production of volatile polonium (Po(v)), a naturally occurring radioactive element, by pure cultures of aerobic marine tellurite-resistant microorganisms was investigated. Rhodotorula mucilaginosa, a carotogenic yeast, and a Bacillus sp. strain, a Gram-positive bacterium, generated approximately one and 2 orders of magnitude, respectively, greater amounts of Po(v) compared to the other organisms tested. Gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS) analysis identified dimethyl polonide (DMPo) as the predominant volatile Po compound in culture headspace of the yeast. This species assignment is based on the exact relation between GC retention times and boiling points of this and other Group VI B analogues (S, Se, and Te). The extent of the biotic Po(v) production correlates exponentially with elevated particulate Po (Po(p)): dissolved Po (Po(aq)) ratios in the cultures, consistent with efficient Po bioaccumulation. Further experimentation demonstrated that some abiotic Po(v) generation is possible. However, high-level Po(v) generation in these cultures is predominantly biotic.

  12. Large deficiency of polonium in the oligotrophic ocean's interior

    NASA Astrophysics Data System (ADS)

    Kim, Guebuem

    2001-09-01

    The naturally occurring radionuclide 210Po is typically deficient relative to its parent 210Pb in the surface ocean due to preferential removal by biota, while in near equilibrium or excess below the surface mixed layer due to rapid regeneration from sinking organic matter. However, a strikingly large deficit of 210Po is observed in the oligotrophic Sargasso Sea's interior. This argues against the general concept that the removal of reactive elements depends on the population of settling particles. A 210Po mass balance model suggests that rather than downward transport, polonium (proxy for S, Se, and Te) is taken up efficiently by bacteria (i.e., cyanobacteria) and transferred to higher trophic levels (i.e., nekton) in this environment. In contrast, in productive areas of the ocean, sulfur group elements seem to reside in the subsurface ocean for much longer periods as taken up by abundant free-living bacteria (non-sinking fine particles). This study sheds new light on global biogeochemical cycling of sulfur group elements in association with microbial roles, and suggests that 210Po may be useful as a tracer of nitrogen fixation in the ocean.

  13. Systematical behavior of even-A polonium isotopes

    SciTech Connect

    Younes, W.; Cizewski, J.A.

    1997-03-01

    The energy systematics of even-A, neutron-deficient polonium isotopes have been previously observed down to A=194. The low-lying states display a gradual approach to the equal spacings of a harmonic vibrator, exceeding this limit for the first time in {sup 194}Po. We have successfully modeled these energy systematics using the particle-core model and have applied the quasiparticle random phase approximation to extract microscopic wave functions for the collective 2{sub 1}{sup +} states and predict B(E2;2{sub 1}{sup +}{r_arrow}0{sub 1}{sup +}) values. We are able to explain the Po trends in terms of the overlaps of the wave functions of valence particles, overlaps which are enhanced when particles occupy the high-j proton 1h{sub 9/2} and neutron 1i{sub 13/2} orbitals. We find little evidence for particle-hole excitations across the Z=82 shell gap. {copyright} {ital 1997} {ital The American Physical Society}

  14. Waking a Sleeping Giant: The Tobacco Industry’s Response to the Polonium-210 Issue

    PubMed Central

    Muggli, Monique E.; Ebbert, Jon O.; Robertson, Channing; Hurt, Richard D.

    2008-01-01

    The major tobacco manufacturers discovered that polonium was part of tobacco and tobacco smoke more than 40 years ago and attempted, but failed, to remove this radioactive substance from their products. Internal tobacco industry documents reveal that the companies suppressed publication of their own internal research to avoid heightening the public’s awareness of radioactivity in cigarettes. Tobacco companies continue to minimize their knowledge about polonium-210 in cigarettes in smoking and health litigation. Cigarette packs should carry a radiation-exposure warning label. PMID:18633078

  15. Relativistically parametrized extended Hueckel calculations. 11. Energy bands for elemental tellurium and polonium

    SciTech Connect

    Lohr, L.L.

    1987-06-17

    An extension of the REX relativistically parametrized extended Hueckel LCAO molecular orbital method to periodic solids is outlined. The method provides a simple and systematic approach to the description of the spin-orbit splitting of energy bands. The method is illustrated with results for the main-group elements tellurium and polonium, with trigonal-helical and simple-cubic structures, respectively. The helical structure of tellurium is described as a distortion of a simple-cubic structure, with the distortion being quenched in the case of polonium by its very large spin-orbit coupling. 36 references, 10 figures, 1 table.

  16. Estimating risk factors and perinatal outcomes for gestational diabetes and impaired glucose tolerance in teen mothers.

    PubMed

    Baker, Arthur M; Haeri, Sina

    2012-11-01

    Our objective was to identify potentially modifiable risk factors and outcomes for gestational diabetes and impaired glucose tolerance in a contemporary American teen population. We conducted a retrospective cohort analysis of all teenage deliveries (≤18 years old) at one institution over a 4-year period with documented oral glucose tolerance testing. All cases of gestational diabetes and impaired glucose tolerance were identified using the Carpenter and Coustan diagnostic criteria and compared with teenage mothers with normal glucose tolerance testing. Of the 670 included teen deliveries, 668 were either African American or Hispanic/Latino; 31 (5%) were diagnosed with gestational diabetes (n = 5) or impaired glucose tolerance (n = 26). Higher maternal prepregnancy body mass index (34.3 ± 7.8 vs 30.3 ± 6.4, p = 0.001) and morbid obesity (body mass index ≥ 35 kg/m(2) , RR 2.0, 95% CI 1.1-3.6) were associated with gestational diabetes and impaired glucose tolerance. There was no association with weight gain above the Institute of Medicine recommended levels (RR 1.6, 95% CI 0.77-3.4). On postpregnancy follow up, three of the five (60%) teens with gestational diabetes and none of the 26 (0%) teens with impaired glucose tolerance were diagnosed with diabetes mellitus. Higher prepregnancy body mass index, especially morbid obesity, places the gravid teen at higher risk for development of gestational diabetes and impaired glucose tolerance in pregnancy. The potentially modifiable nature of these risk factors coupled with the emerging teen obesity epidemic underscores the need for increased public health focus on this problem. Copyright © 2012 John Wiley & Sons, Ltd.

  17. Low-complexity and phase noise tolerant carrier phase estimation for dual-polarization 16-QAM systems.

    PubMed

    Gao, Yuliang; Lau, Alan Pak Tao; Yan, Shuangyi; Lu, Chao

    2011-10-24

    A low-complexity feed-forward carrier phase estimation (CPE) technique is presented for dual-polarization (DP)-16-QAM transmission systems. By combining QPSK partitioning, maximum likelihood (ML) detection and phase offset estimation between signals in different polarizations, simulation and experimental results for a 200 Gb/s DP-16-QAM system demonstrate similar linewidth tolerance to the best feed-forward CPE reported to date while the computational complexity is at least three times lower compared with other simplified feed-forward CPE techniques.

  18. Transfer factors of polonium from soil to parsley and mint.

    PubMed

    Al-Masri, M S; Al-Hamwi, A; Eadan, Z; Amin, Y

    2010-12-01

    Transfer factors of (210)Po from soil to parsley and mint have been determined. Artificial polonium isotope ((208)Po) was used as a tracer to determine transfer factor of Po from soil to plant in pot experiments. Two plant growing systems were used for this study namely, an outdoor system and a sheltered system by a polyethylene tent. (208)Po and (210)Po were determined in soil and different parts of the studied plants (stem and leaf), using alpha spectroscopy. The results have shown that there was a clear uptake of (208)Po by roots to leaves and stems of both plants. Higher values of transfer factors using the (210)Po activity concentrations than the (208)Po activity concentration were observed. Transfer factors of (210)Po from soil to parsley varied between 20 × 10⁻² and 50 × 10⁻² and 22 × 10⁻³ and 67 × 10⁻³ in mint, while (208)Po transfer factors varied between 4 × 10⁻² and 12 × 10⁻² for parsley and 10 × 10⁻² and 22 × 10⁻² in mint. Transfer factors of Po were higher in those plants grown in the sheltered system than in the open system; about 75% of Po was transferred from atmosphere to parsley parts using the two systems. Ratios of transferred Po from soil to mint stem and leaf in the sheltered system were higher by 2 times from those in the open system. Copyright © 2010 Elsevier Ltd. All rights reserved.

  19. Rapid preparation of polonium counting sources for alpha spectrometry using copper sulfide microprecipitation.

    PubMed

    Guérin, Nicolas; Dai, Xiongxin

    2013-07-02

    Thin-layer polonium (Po) sources for alpha spectrometry counting can be rapidly prepared using copper sulfide (CuS) microprecipitation. Polonium was coprecipitated with CuS, filtered onto Eichrom Resolve filters, and counted. This simple procedure is faster, cheaper, and more convenient than traditional spontaneous plating on metallic discs, and similar yields were obtained (80-90%). The experimental conditions for the microprecipitation technique were optimized (0.05 mg of Cu(2+) in 10 mL of 1 M HCl); these compare advantageously with conventional preparation and purification procedures for polonium samples (0.1 to 1 M HCl). The results showed that the most likely potential radionuclide interferences (Ra, Th, U, Np, Pu, and Am) for long-lived polonium isotopes ((208)Po, (209)Po, (210)Po) are effectively removed during processing. The effects of several transition metals (Cu(2+), Ag(+), Fe(3+), Fe(2+), Pb(2+), and Ni(2+)) on the yield and the resolution of the alpha peaks obtained were also assessed. Little interference was found, demonstrating the versatility of the present microprecipitation technique for environmental and biological matrices. The procedure has been successfully applied to different amounts of (210)Po using (209)Po as a yield tracer.

  20. Laboratory and field studies of polonium and plutonium in marine plankton.

    PubMed

    Wilson, R C; Watts, S J; Vives i Batlle, J; McDonald, P

    2009-08-01

    Uptake experiments were successfully undertaken for polonium and plutonium in the marine diatom Skeletonema costatum. Experiments were complemented with a field study which yielded concentration factors for these radionuclides for plankton samples collected in the eastern Irish Sea. The uptake experiment produced uptake half times of 0.8 and 0.6 days for plutonium and polonium, respectively. Concentration factors of 3.1 x 10(5) l kg(-1) for plutonium and 2.4 x 10(5) l kg(-1) for polonium were consistent with those suggested by the IAEA for phytoplankton. Concentration factors derived from the field study were 2 x 10(3) l kg(-1) for plutonium and 1.4 x 10(4) l kg(-1) for polonium and were more consistent with IAEA values for zooplankton rather than phytoplankton. The maximum calculated dose rate due to Po and Pu in plankton sampled in the field was 0.12 microGyh(-1). In applying the laboratory-derived phytoplankton CF values for Po and Pu, higher dose rates, in the range 6-11 microGyh(-1), were calculated. The latter values are well below the UNSCEAR and IAEA review value of 400 microGyh(-1), and are also below the Environment Agency marine action level of 40 microGyh(-1).

  1. Epidemiology of internal contamination with polonium-210 in the London incident, 2006.

    PubMed

    Fraser, G; Giraudon, I; Cohuet, S; Bishop, L; Maguire, H; Thomas, H L; Mandal, S; Anders, K; Sanchez-Padilla, E; Charlett, A; Evans, B; Gross, R

    2012-02-01

    More than 700 UK residents were tested for possible contamination with polonium-210 ((210)Po) following the alleged poisoning of Mr Alexander Litvinenko in London in November 2006. This paper describes the epidemiology of internal contamination with the radionuclide in this group. 11 locations in London had been identified as sufficiently environmentally contaminated with (210)Po to present a health risk to people associated with them. Public health consultant teams identified individuals at risk and offered 24-h urine testing for (210)Po excretion. Prevalence of internal contamination was estimated, and a retrospective cohort analysis was completed for each location. Overall 139 individuals (prevalence 0.19 (95% CI 0.13 to 0.27)) showed evidence of internal contamination with (210)Po, although none with uptakes likely to cause adverse health effects. Substantial prevalence was seen among specific hotel service staff, customers, staff and other users of a hotel bar, office and hospital staff, staff of one restaurant and residents of and visitors to the family home. Increased risks of contamination were seen for a hotel bar in association with occupational, behavioural and temporal factors. Occupational and guest exposure to contaminated areas of hotels were also associated with increased contamination risk. Nurses were more likely to become contaminated than other staff involved in direct patient care. Uptake of trace amounts of radionuclide in this incident was frequent. Occupational, behavioural and temporal gradients in contamination risk were mostly consistent with a priori site risk assessments. Utility of the investigation methods and findings for future accidental or deliberate environmental contamination incidents are discussed.

  2. Phase noise tolerance study in coherent optical circular QAM transmissions with Viterbi-Viterbi carrier phase estimation.

    PubMed

    Zafra, Sebastian Ortega; Pang, Xiaodan; Jacobsen, Gunnar; Popov, Sergei; Sergeyev, Sergey

    2014-12-15

    We present a performance evaluation of a non-conventional approach to implement phase noise tolerant optical systems with multilevel modulation formats. The performance of normalized Viterbi-Viterbi carrier phase estimation (V-V CPE) is investigated in detail for circular m-level quadrature amplitude modulation (C-mQAM) signals. The intrinsic property of C-mQAM constellation points with a uniform phase separation allows a straightforward employment of V-V CPE without the need to adapt constellation. Compared with conventional feed-forward CPE for square QAM signals, the simulated results show an enhanced tolerance of linewidth symbol duration product (ΔνTs) at a low sensitivity penalty by using feed-forward CPE structure with C-mQAM. This scheme can be easily upgraded to higher order modulations without inducing considerable complexity.

  3. Polonium, uranium and plutonium radionuclides in aquatic and land ecosystem of Poland.

    PubMed

    Skwarzec, Bogdan; Strumińska-Parulska, Dagmara I; Boryło, Alicja; Kabat, Krzysztof

    2012-01-01

    This article presents the results of study about distribution, inflow and accumulation of polonium, uranium and plutonium in aquatic and land environment of Poland and the southern Baltic Sea. Radionuclides of (210)Po, (234)U and (238)U as well as (239+240)Pu and (241)Pu are strongly accumulated in Baltic organisms and plants and transferred through the trophic chain. The values of bioconcentration factor (BCF) in Baltic plants and animals are higher for polonium and plutonium in comparison with uranium. The principal source of radionuclides in the southern Baltic Sea is their inflow with rivers. Total annual runoff of polonium, uranium and plutonium from the Vistula and the Odra as well as the Pomeranian rivers were calculated at 95 GBq of (210)Po, 750 GBq of (234+238)U and 160 MBq of (238+239+240)Pu. Seasonal and spatial variability of (210)Po, (238)U and (239+240)Pu levels in the Vistula and the Odra drainage basins were assessed by application of neural-network based classification, especially cluster analysis (CA), principal component analysis (PCA) and self-organizing maps (SOM). The result for the Vistula river indicated correlation between polonium and plutonium as well as polonium and uranium. In the Odra drainage basin, the biggest differences were observed in the case of (238)U. To assess if there are statistically significant differences in mean concentration values of (210)Po, (238)U and (239+240)Pu for the Vistula and the Odra rivers drainage basins were obtained by used of the non-parametric tests. Comparing to the Vistula catchment area, statistically differences concentration of (210)Po and (239+240)Pu in all year was observed for river samples collected on the Odra drainage basin.

  4. SEPARATION OF POLONIUM, PROTACTINIUM OR MIXTURES THEREOF IN AQUEOUS SOLUTION FROM BISMUTH, LEAD, ZIRCONIUM AND/OR COLUMBIUM VALUES

    DOEpatents

    Van Winkle, Q.; Kraus, K.A.

    1959-10-27

    A process is presented for separating polonium, protactinium, or mixtures thereof in aqueous solution from bismuth, zirconium, lead, and niobium values contained in the solution. The method comprises providing hydrochloric acid in the solution in a concentration of at least 5N. contacting the aqueous solution with a substantially waterimmiscible organic solvent such as diisopropyl ketone, and separating the aqueous phase containing the bismuth, zirconium, lead, and niobium from the organic extract phase containing the polonium, protactinium, or mixture thereof.

  5. Ingestion of polonium ((210)Po) via dietary sources in high background radiation areas of south India.

    PubMed

    Arunachalam, Kantha Deivi; Baskaran, Kamesh Viswanathan; Rao, D D; Sathyapriya, R; Annamalai, Sathesh Kumar; Kuruva, Jaya Krishna; Hari, Shanmugamsundaram

    2014-10-01

    To study the distribution of Polonium ((210)Po) activity in dietary sources in the high background radiation zone of Puttetti in southern Tamil Nadu. (210)Po was analyzed in the food materials consumed by the male and female individual representatives living in the high background areas by 24-h Duplicate Diet Study (DDS) and Market Basket Study (MBS). The MBS was performed by collecting the food samples such as, cereals, fruits, leafy vegetables, roots and tubers, other vegetables, fish, meat and milk grown in the high background radiation zone of southern Tamil Nadu as a part of baseline study in this region. The DDS was done by collecting the food materials consumed including the beverages in 24 h from different age groups of male and female individuals living in the village of Puttetti. The intake and ingestion dose of the radionuclide (210)Po was estimated. The average concentration of (210)Po in DDS (n = 33) was found to be 74 mBq.kg(- 1) of fresh weight. The MBS was collected based on food consumption representing more than 85-95% of annual supply, and were divided into eight food groups. The average concentration of (210)Po in the eight food groups namely leafy vegetables was 2176 mBq.kg(- 1) (n = 3), vegetables 55 mBq.kg(- 1) (n = 10), roots and tubers 251 mBq.kg(- 1) (n = 4), fruits 65 mBq.kg(- 1) (n = 5), fish 345 mBq.kg(- 1) (n = 2), meat food 117 mBq.kg(- 1) (n = 3), milk 20 mBq.kg(- 1) (n = 1) and cereal 290 (n = 1) mBq.kg(- 1) of fresh weight, respectively. The annual intake and ingestion dose due to (210)Po was estimated by DDS and MBS in adults, adolescents and children. The overall results showed that the MBS was moderately higher than the DDS in all age groups. Moreover, a DDS approach may even be more realistic, as cooked foodstuffs are used for dietary exposure assessment. The study confirms that the current levels of (210)Po do not pose a significant radiological risk to the local inhabitants.

  6. Early Onset of Ground State Deformation in Neutron Deficient Polonium Isotopes

    NASA Astrophysics Data System (ADS)

    Cocolios, T. E.; Dexters, W.; Seliverstov, M. D.; Andreyev, A. N.; Antalic, S.; Barzakh, A. E.; Bastin, B.; Büscher, J.; Darby, I. G.; Fedorov, D. V.; Fedosseyev, V. N.; Flanagan, K. T.; Franchoo, S.; Fritzsche, S.; Huber, G.; Huyse, M.; Keupers, M.; Köster, U.; Kudryavtsev, Yu.; Mané, E.; Marsh, B. A.; Molkanov, P. L.; Page, R. D.; Sjoedin, A. M.; Stefan, I.; van de Walle, J.; van Duppen, P.; Venhart, M.; Zemlyanoy, S. G.; Bender, M.; Heenen, P.-H.

    2011-02-01

    In-source resonant ionization laser spectroscopy of the even-A polonium isotopes Po192-210,216,218 has been performed using the 6p37s S25 to 6p37p P25 (λ=843.38nm) transition in the polonium atom (Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope shifts in Po200-210 with a previous data set allows us to test for the first time recent large-scale atomic calculations that are essential to extract the changes in the mean-square charge radius of the atomic nucleus. When going to lighter masses, a surprisingly large and early departure from sphericity is observed, which is only partly reproduced by beyond mean field calculations.

  7. Accumulation of polonium 210Po in tissues and organs of deer carvidae from Northern Poland.

    PubMed

    Skwarzec, Bogdan; Prucnal, Malgorzata

    2007-01-01

    This study was undertaken to provide information on accumulation of polonium in tissues and organs of deer carvidae in order to assess the potential transport of this element via food-chain to game meat consumers. Livers, kidneys and muscles of large herbivorous animals belonging to three species: roe deer (Capreolus capreolus), red deer (Cervus elaphus) and fallow deer (Dama dama), collected in Northern Poland, were the subject of the present investigation. Activities of (210)Po were determined by means of alpha spectrometry along with relevant radiochemical procedures. The concentration of (210)Po in analyzed animals decreased in the order kidney > liver > muscle tissue. The average activity concentrations of (210)Po ranged between 0.02 +/- 0.01 Bq. kg(- 1) w.w. in muscles and 7.15 +/- 0.12 Bq. kg(- 1) w.w. in kidneys. Levels of polonium were not influenced by sampling location, sex, age and species of animals.

  8. Early Onset of Ground State Deformation in Neutron Deficient Polonium Isotopes

    SciTech Connect

    Cocolios, T. E.; Van de Walle, J.; Dexters, W.; Bastin, B.; Buescher, J.; Darby, I. G.; Huyse, M.; Keupers, M.; Kudryavtsev, Yu.; Van Duppen, P.; Seliverstov, M. D.; Andreyev, A. N.; Antalic, S.; Barzakh, A. E.; Fedorov, D. V.; Molkanov, P. L.; Fedosseyev, V. N.; Marsh, B. A.; Flanagan, K. T.; Franchoo, S.

    2011-02-04

    In-source resonant ionization laser spectroscopy of the even-A polonium isotopes {sup 192-210,216,218}Po has been performed using the 6p{sup 3}7s {sup 5}S{sub 2} to 6p{sup 3}7p {sup 5}P{sub 2} ({lambda}=843.38 nm) transition in the polonium atom (Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope shifts in {sup 200-210}Po with a previous data set allows us to test for the first time recent large-scale atomic calculations that are essential to extract the changes in the mean-square charge radius of the atomic nucleus. When going to lighter masses, a surprisingly large and early departure from sphericity is observed, which is only partly reproduced by beyond mean field calculations.

  9. Finite Time Fault Tolerant Control for Robot Manipulators Using Time Delay Estimation and Continuous Nonsingular Fast Terminal Sliding Mode Control.

    PubMed

    Van, Mien; Ge, Shuzhi Sam; Ren, Hongliang

    2016-04-28

    In this paper, a novel finite time fault tolerant control (FTC) is proposed for uncertain robot manipulators with actuator faults. First, a finite time passive FTC (PFTC) based on a robust nonsingular fast terminal sliding mode control (NFTSMC) is investigated. Be analyzed for addressing the disadvantages of the PFTC, an AFTC are then investigated by combining NFTSMC with a simple fault diagnosis scheme. In this scheme, an online fault estimation algorithm based on time delay estimation (TDE) is proposed to approximate actuator faults. The estimated fault information is used to detect, isolate, and accommodate the effect of the faults in the system. Then, a robust AFTC law is established by combining the obtained fault information and a robust NFTSMC. Finally, a high-order sliding mode (HOSM) control based on super-twisting algorithm is employed to eliminate the chattering. In comparison to the PFTC and other state-of-the-art approaches, the proposed AFTC scheme possess several advantages such as high precision, strong robustness, no singularity, less chattering, and fast finite-time convergence due to the combined NFTSMC and HOSM control, and requires no prior knowledge of the fault due to TDE-based fault estimation. Finally, simulation results are obtained to verify the effectiveness of the proposed strategy.

  10. Four-Quasiparticle High-K States in Neutron-Deficient Lead and Polonium Nuclei

    NASA Astrophysics Data System (ADS)

    Shi, Yue; Xu, Furong

    2012-06-01

    Configuration-constrained potential energy surface calculations have been performed to investigate four-quasiparticle high-K configurations in neutron-deficient lead and polonium isotopes. A good agreement between the calculations and the experimental data has been found for the excitation energy of the observed Kπ = 19- state in 188Pb. Several lowly excited high-K states are predicted, and the large oblate deformation and low energy indicate high-K isomerism in these nuclei.

  11. Strong phonon anomalies and Fermi surface nesting of simple cubic Polonium

    NASA Astrophysics Data System (ADS)

    Belabbes, A.; Zaoui, A.; Ferhat, M.

    2010-12-01

    The unknown lattice dynamics of simple cubic Polonium is calculated using first-principles density-functional perturbation theory with pseudopotentials and a plane-wave basis set. We notice several phonon anomalies, in particular along major symmetry directions namely M-R, R-Γ, Γ-M, M-X, and X-Γ. The analysis of the Fermi surface strongly suggests that the observed phonon anomalies are Kohn anomalies arising from strong Fermi surface nesting.

  12. Isotope shifts and hyperfine structure in polonium isotopes by atomic-beam laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Kowalewska, D.; Bekk, K.; Göring, S.; Hanser, A.; Kälber, W.; Meisel, G.; Rebel, H.

    1991-08-01

    Laser-induced fluorescence spectroscopy in a collimated atomic beam has been applied to determine isotope shifts and the hyperfine structure of an isotopic chain of the radioactive element polonium (200Po, 202Po, 204-210Po). The relative isotope shifts show a striking similarity with results for other elements in the vicinity of Pb, even reproducing details of the odd-even staggering.

  13. Influence of heavy metals upon the retention and mobilization of polonium-210 in rats.

    PubMed

    Rencová, J; Vlková, A; Curík, R; Holusa, R; Veselá, G

    2004-10-01

    To provide information about the tissue retention and mobilization of the alpha-emitting radionuclide, polonium-210 (210Po), in rats under combined exposure to heavy metal ions and the chelating agent, 2, 3-dimercaptopropane-1-sulfonate (DMPS). Rats were pre-exposed intraperitoneally to either CdCl2 or Pb(CH3COO)2. 9 or 15 h later they received 210Po nitrate intravenously. The retention and excretion of 210Po via the urine and faeces of pre-exposed rats, as well as in pre-exposed rats treated with DMPS, were followed. The radioactivity due to 210Po in a broad spectrum of body tissues and excreta was measured by the liquid scintillation counting after sample digestion in a mixture of perchloric acid and hydrogen peroxide. The immunohistochemical localization of metallothioneins (MT) was studied using a mixture of murine monoclonal antibodies directed against MT I+II. The present study revealed different tissue distributions of polonium-210 in the rats pre-exposed to lead or cadmium ions when compared with that in 210Po only controls. Under combined exposure to Pb or Cd, the spontaneous excretion of 210Po was enhanced and could be further enhanced by treatment with DMPS. Treatment with this chelator was efficient even when its start was postponed until 24h after internal contamination of the body with 210Po. Polonium-210 is bound in vivo to binding sites on various biomolecules, among them erythrocytic enzymes and MT. This phenomenon explains the different affinity and overall distribution of 210Po in control body tissues. When the appropriate binding sites are occupied by lead or cadmium, enhanced natural excretion of polonium-210 occurs.

  14. Comparison of AC electronic monitoring and field data for estimating tolerance to Empoasca kraemeri (Homoptera: Cicadellidae) in common bean genotypes.

    PubMed

    Serrano, M S; Backus, E A; Cardona, C

    2000-12-01

    Two methods for estimating the tolerance of common bean genotypes to Empoasca kraemeri Ross & Moore were compared, using a yield trial carried out at Centro Internacional de Agricultura Tropical (CIAT), Cali, Colombia, versus stylet penetration tactics measured by AC electronic feeding monitors. A stylet penetration index was devised based on principal component scores of three penetration tactics identified (pulsing laceration, cell rupturing, and lancing sap ingestion), combined with knowledge of the hopperburn symptoms caused by each tactic. Tolerant genotypes, as classified by the CIAT yield index, showed significantly more unprotected yield and lower hopperburn scores than the susceptible control. They also induced performance of less pulsing laceration (the tactic considered most damaging to the plant), and more of the other two, mitigating tactics, especially cell rupturing. When index values were calculated for each genotype, stylet penetration index values matched those of the yield index for three out of five genotypes: two EMP-coded tolerant lines ('EMP 385' and 'EMP 392') and the susceptible control 'BAT 41'. Thus, for these three genotypes, all subsequent hoppereburn symptoms are predictable by the type of feeding behavior performed on them. 'Porrillo Sintético' and 'EMP 84', considered borderline genotypes by the yield index, were overestimated and underestimated respectively, by the stylet penetration index. We postulate that, for these two genotypes, plant physiological responses to feeding (either compensatory or heightened sensitivity, respectively) synergize with type of feeding performed to generate the overall hopperburn condition. This multivariate analysis of electronic monitoring data was successfully used to devise an index of resistance. The implications of using the stylet penetration index and the advantages of using electronic monitoring in a bean-breeding program are discussed.

  15. Proton-induced polonium production in massive lead bismuth target irradiated by 660 MeV protons

    NASA Astrophysics Data System (ADS)

    Polanski, Aleksander; Petrochenkov, Sergey; Pohorecki, Wladyslaw

    2006-06-01

    The paper presents study of polonium production in bismuth foils placed in lead target. Proton-induced production of residual nuclei 206Po, 207Po, 208Po, 209Po, 210Po in 209Bi foils placed in lead target irradiated by 660 MeV protons was calculated. A comparison with calculated spatial distribution of polonium production using an MCNPX code and experimental results has been performed. The results of calculation will be useful for design of target of Subcritical Assembly in Dubna (SAD).

  16. Lichens and mosses as polonium and uranium biomonitors on Sobieszewo Island.

    PubMed

    Boryło, Alicja; Romańczyk, Grzegorz; Skwarzec, Bogdan

    2017-01-01

    In the study the activities of polonium (210)Po and uranium (234)U, (238)U radionuclides in moss and lichen samples were determined using the alpha spectrometry. Different lichens and mosses were collected around the Sobieszewo Island (northern Poland) and investigated for potential use as biomonitors for (210)Po and (238)U deposition. Mosses and lichens have a high efficiency in capturing (210)Po and (238)U from atmospheric fallout. The obtained results showed that (210)Po, (238)U concentrations are changing in analyzed thallophytes samples depending on the type of thallus.

  17. Evaluation of the contribution of smoking to total blood polonium-210 in Saudi population.

    PubMed

    Shabana, E I; Abd Elaziz, M A; Al-Arifi, M N; Al-Dhawailie, A A; Al-Bokari, M M

    2000-01-01

    A preliminary study of 210Po concentrations in the blood of some smokers and nonsmokers is presented in order to evaluate the contribution of smoking to total blood 210Po in Saudi population. Blood samples were collected from 30 volunteers and analyzed by high resolution alpha-spectrometry using a radiochemical technique. The technique is based on the separation of polonium from other components of the sample by wet ashing with an HNO3/H2O2 oxidizing mixture and spontaneous deposition on a silver disc under the relevant conditions for alpha-particle counting. The results indicated that a significant fraction (about 30%) of blood 210Po is related to smoking.

  18. Polonium release from an ATW burner system with liquid lead-bismuth coolant

    SciTech Connect

    Li, N.; Yefimov, E.; Pankratov, D.

    1998-04-01

    The authors analyzed polonium release hazards in a conceptual pool-type ATW burner with liquid lead-bismuth eutectic (LBE) coolant. Simplified quantitative models are used based on experiments and real NPP experience. They found little Po contamination outside the burner under normal operating conditions with nominal leakage from the gas system. In sudden gas leak and/or coolant spill accidents, the P contamination level can reach above the regulation limit but short exposure would not lead to severe health consequences. They are evaluating and developing mitigation methods.

  19. Health Risk Evaluations for Ingestion Exposure of Humans to Polonium-210

    PubMed Central

    Scott, Bobby R.

    2007-01-01

    The incident in London during November 2006 involving a lethal intake by Mr. Alexander Litvinenko of the highly-radioactive, alpha-particles-emitting polonium-210 (Po-210) isotope, presumably via ingestion, sparked renewed interest in the area of Po-210 toxicity to humans. This paper is the result of assembling and interpreting existing Po-210 data within the context of what is considered a reliable risk model (hazard-function [HF] model) for characterizing the risk of death from deterministic effects of high alpha radiation doses and dose rates to body organs. The HF model was developed to address radiation exposure scenarios involving combined exposures to alpha, beta, and gamma radiations and can be used in circumstances where only one type of radiation is involved. Under a plausible but not yet validated set of assumptions and using available megabecquerel (Po-210) to gray dose-conversion factors, acute lethality risk vs. dose curves were developed for circumstances of ingestion exposure to Po-210 by humans. Initial risk calculations were carried out for a reference adult male human (a hypothetical 70-kg person). Results were then modified for application to all ages (except the in utero child) via the use of systemic Po-210 burden. Because of the unavailability of acute lethality data derived from human ingestions of high levels of Po-210, plausibility of risk calculations were evaluated based on data from studies of Po-210 injections in animals. The animal data, although limited, were found to be consistent with the theoretical risk calculations. Key findings are as follows: (1) ingestion (or inhalation) of a few tents of a milligram of Po-210 will likely be fatal to all exposed persons. (2) Lethal intakes are expected to involve fatal damage to the bone marrow which is likely to be compounded by damage caused by higher doses to other organs including the kidneys and liver. (3) Lethal intakes are expected to cause severe damage to the kidney, spleen, stomach

  20. Health risk evaluations for ingestion exposure of humans to polonium-210.

    PubMed

    Scott, Bobby R

    2007-04-20

    The incident in London during November 2006 involving a lethal intake by Mr. Alexander Litvinenko of the highly-radioactive, alpha-particles-emitting polonium-210 (Po-210) isotope, presumably via ingestion, sparked renewed interest in the area of Po-210 toxicity to humans. This paper is the result of assembling and interpreting existing Po-210 data within the context of what is considered a reliable risk model (hazard-function [HF] model) for characterizing the risk of death from deterministic effects of high alpha radiation doses and dose rates to body organs. The HF model was developed to address radiation exposure scenarios involving combined exposures to alpha, beta, and gamma radiations and can be used in circumstances where only one type of radiation is involved. Under a plausible but not yet validated set of assumptions and using available megabecquerel (Po-210) to gray dose-conversion factors, acute lethality risk vs. dose curves were developed for circumstances of ingestion exposure to Po-210 by humans. Initial risk calculations were carried out for a reference adult male human (a hypothetical 70-kg person). Results were then modified for application to all ages (except the in utero child) via the use of systemic Po-210 burden. Because of the unavailability of acute lethality data derived from human ingestions of high levels of Po-210, plausibility of risk calculations were evaluated based on data from studies of Po-210 injections in animals. The animal data, although limited, were found to be consistent with the theoretical risk calculations. Key findings are as follows: (1) ingestion (or inhalation) of a few tents of a milligram of Po-210 will likely be fatal to all exposed persons. (2) Lethal intakes are expected to involve fatal damage to the bone marrow which is likely to be compounded by damage caused by higher doses to other organs including the kidneys and liver. (3) Lethal intakes are expected to cause severe damage to the kidney, spleen, stomach

  1. An improved sensitive assay for polonium-210 by use of a background-rejecting extractive liquid-scintillation method.

    PubMed

    Case, G N; McDowell, W J

    1982-10-01

    A procedure is described for the determination of polonium-210 in various types of materials, including ores, mill tailings, and environmental samples, by a combined solvent-extraction liquid-scintillation spectrometry method. Concentration of polonium-210 and separation from interfering elements (such as iron) are accomplished by extraction from a 7M phosphoric acid-0.01M hydrochloric acid solution with 0.20M trioctylphosphine oxide solution (together with a scintillator) in toluene. The polonium-210 is determined by counting the 5.3-MeV alpha-radiation with a photon/ electron-rejecting alpha liquid-scintillation spectrometer. Extraction coefficients of over 1000 for polonium ensure quantitative recovery, and no other alpha-emitters in the decay chains of uranium-238, uranium-235 and thorium-232 are extracted. The results for several samples show the relative standard deviation to be approximately 1.2%. A lower limit of detection of 0.0038 pCi is proposed, based on a counting time of 1000 min and an easily obtainable background of 0.01 cpm for the alpha peak.

  2. Using estimates of metal bioavailability in the soil and genetic variation of allozymes to investigate heavy metal tolerance in the earthworm Eisenia fetida (Oligochaeta).

    PubMed

    Voua Otomo, P; Owojori, O J; Reinecke, S A; Daniels, S; Reinecke, A J

    2011-10-01

    In a recent study, we showed that the earthworm species Eisenia fetida, inhabiting an extremely high metal polluted compost heap on a wine farm, did not have elevated body loads of the metals but exhibited genotoxic tolerance when exposed to Cd in the laboratory (Voua Otomo and Reinecke, 2010). To unravel the mechanism behind the surprisingly low metal body burdens on one hand and genotoxic tolerance on the other hand, we investigated the estimated bioavailability of these metals (Cu, Zn, Pb and Cd) using sequential extraction methods with CaCl(2) and di-ethylene-triamine-pentaacetic acid (DTPA) and allozyme polymorphism in this field population, a laboratory control as well as a long-term Cd exposed population. The amounts of mobile (extracted with CaCl(2)) and mobilizable (extracted with DTPA) metals in relation to the total (extracted with nitric acid) metals were all below 0.05% for all four metals, suggesting low availability for uptake. The low availability of these metals could not be explained by physico-chemical properties of soil but by the phenomenon of aging of the metals. There was no difference in allozyme frequency between metal tolerant and non-metal tolerant populations of E. fetida. This suggested that the tolerance found in earlier studies could be a mere physiological adaptation.

  3. Familial hypercholesterolemia and estimation of US patients eligible for low-density lipoprotein apheresis after maximally tolerated lipid-lowering therapy.

    PubMed

    Vishwanath, Raghu; Hemphill, Linda C

    2014-01-01

    Familial hypercholesterolemia (FH), an autosomal-dominant inherited disorder, can occur in either the heterozygous (HeFH) or homozygous (HoFH) state, and is characterized by high levels of serum low-density lipoprotein cholesterol (LDL-C). Although potent statins and maximally tolerated lipid-lowering therapy (LLT) have greatly reduced the risk of premature coronary heart disease (CHD) and death, all patients with HoFH and many with severe HeFH remain far from treatment goals and are thus at risk of cardiovascular disease. LDL apheresis is the treatment of choice for these patients but remains underutilized. No formal studies or epidemiologic data have estimated the prevalence of HoFH. An HeFH prevalence of 1:500 and a simplified Hardy-Weinberg equilibrium model was used to determine the probability of finding HoFH as 1:1 million in the general population. A US population of approximately 314.8 million was used to determine the number of cases of HoFH and HeFH. The following key parameters were used to estimate the prevalence of severe HeFH: baseline pretreatment LDL-C level and distribution of patients with FH, posttreatment LDL-C level and distribution after maximally tolerated LLT, and baseline percentage of patients with HeFH who have CHD. We assumed an HeFH prevalence of 1:500 and used statistics for a Gaussian distribution after the posttreatment means and standard deviations of LDL-C levels in patients with HeFH receiving maximally tolerated LLT, as has been documented by data from clinical trials and cross-sectional studies. These estimates do not include the statin-intolerant population. The objective of this analysis was to determine the prevalence of the US population with severe HeFH with or without CHD who still will be eligible for LDL apheresis despite maximally tolerated LLT. We estimated that there are 315 US patients with HoFH and 650,000 with HeFH. The estimated prevalence of the severe HeFH population eligible for apheresis is approximately 1

  4. (210)Polonium bioaccessibility assessment in algae for human consumption: An in vitro gastrointestinal digestion method.

    PubMed

    Desideri, Donatella; Meli, Maria Assunta; Roselli, Carla; Feduzi, Laura; Ugolini, Lucia

    2017-01-01

    The occurrence and mobility of natural radioactive element as (210)Polonium ((210)Po) in 13 commercial algae consumed in Italy by humans were determined because the effects on human health need to take into account the bioavailability of these elements. The simulation of gastrointestinal (GIT) digestion was divided into three stages and was accomplished using three different artificial solutions: saliva, gastric, and synthetic bile-pancreas solution. The same sample was treated in two different ways: a) only gastric digestion and b) complete GIT digestion (gastric digestion followed by bile-pancreas solution). The difference between Po gastric mobility with respect to that found for GIT digestion was not significant; in fact, Po mobility exhibited a mean value 17.2 ± 15.1% and 19.5 ± 11.5% for gastric and GIT digestion, respectively.

  5. Interplay between lattice dynamics and the low-pressure phase of simple cubic polonium

    NASA Astrophysics Data System (ADS)

    Zaoui, A.; Belabbes, A.; Ahuja, R.; Ferhat, M.

    2011-04-01

    Low-pressure structural properties of simple cubic polonium are explored through first-principles density-functional theory based relativistic total energy calculations using pseudopotentials and plane-wave basis set, as well as linear-response theory. We have found that Po undergoes structural phase transition at low pressure near 2 GPa, where the element transforms from simple cubic to a mixture of two trigonal phases namely, hR1 (α=86°) and hR2 (α=97.9°) structures. The lattice dynamics calculations provide strong support for the observed phase transition, and show the dynamical stability (instability) of the hR2 (hR1) phase.

  6. Polonium (210)Po activities in human blood of patients with ischaemic heart disease from Gdańsk in Poland.

    PubMed

    Boryło, Alicja; Skwarzec, Bogdan; Romańczyk, Grzegorz; Siebert, Janusz

    The determination of polonium (210)Po in human blood samples is presented and discussed in this paper. The human blood samples were collected from patients of Medical University of Gdańsk with ischaemic heart disease (morbus ischaemicus cordis, MIC). The polonium concentrations in analyzed human blood samples are very differentiated. (210)Po is of particular interest in public health and although is present in the environment in extremely low amounts, it is easily bioaccumulated to the human body. The study shows that the amount of (210)Po that is incorporated into the human body depends on the food habits and some difference in its levels could be observed between smokers and non-smokers.

  7. Tolerable Variation in Item Parameter Estimates for Linear and Adaptive Computer-Based Testing. Research Report No. 04-28

    ERIC Educational Resources Information Center

    Rizavi, Saba; Way, Walter D.; Davey, Tim; Herbert, Erin

    2004-01-01

    Item parameter estimates vary for a variety of reasons, including estimation error, characteristics of the examinee samples, and context effects (e.g., item location effects, section location effects, etc.). Although we expect variation based on theory, there is reason to believe that observed variation in item parameter estimates exceeds what…

  8. Releases of phosphate fertilizer industry in the surrounding environment: investigation on heavy metals and polonium-210 in soil.

    PubMed

    Aoun, M; El Samrani, A G; Lartiges, B S; Kazpard, V; Saad, Z

    2010-01-01

    Distribution of Cu, Zn, Pb, Cr, Ni, Mn concentrations and the activity of polonium-210 in the surrounding area of a phosphate fertilizer industry located on the eastern coast of the Mediterranean Sea has been determined. Nineteen sampling sites were distributed around the industrial zone on a surface area of about 100,000 m2. Atomic absorption spectroscopy and Alpha spectroscopy were used to quantify the heavy elements and polonium-210, respectively. Investigation on a particle scale was conducted by TEM and SEM coupled to EDX and X-ray cartography to determine the nature of heavy elements carriers and their distribution. Heavy elements were mainly concentrated inside the particle size fraction < 50 microm. Their levels decreased with distance increasing from the industry. According to the reference soil, enrichment factors were about 10, 15, 32 and 100 times for Zn, Pb, Cu, and Cr, respectively inside the particle size fraction < 50 microm on the closest sites to the industry. The main contaminant sources were transport and storage of row materials and the free release of phosphogypsum waste. Heavy elements were entrapped inside agglomerates of sulfates, phosphates and iron oxihydroxides in a diffused shape. Polonium-210 with an enrichment factor of about 56, showed the same behavior of the spatial distribution of the trace elements.

  9. Evidence towards Improved Estimation of Respiratory Muscle Effort from Diaphragm Mechanomyographic Signals with Cardiac Vibration Interference Using Sample Entropy with Fixed Tolerance Values

    PubMed Central

    Sarlabous, Leonardo; Torres, Abel; Fiz, José A.; Jané, Raimon

    2014-01-01

    The analysis of amplitude parameters of the diaphragm mechanomyographic (MMGdi) signal is a non-invasive technique to assess respiratory muscle effort and to detect and quantify the severity of respiratory muscle weakness. The amplitude of the MMGdi signal is usually evaluated using the average rectified value or the root mean square of the signal. However, these estimations are greatly affected by the presence of cardiac vibration or mechanocardiographic (MCG) noise. In this study, we present a method for improving the estimation of the respiratory muscle effort from MMGdi signals that is robust to the presence of MCG. This method is based on the calculation of the sample entropy using fixed tolerance values (fSampEn), that is, with tolerance values that are not normalized by the local standard deviation of the window analyzed. The behavior of the fSampEn parameter was tested in synthesized mechanomyographic signals, with different ratios between the amplitude of the MCG and clean mechanomyographic components. As an example of application of this technique, the use of fSampEn was explored also in recorded MMGdi signals, with different inspiratory loads. The results with both synthetic and recorded signals indicate that the entropy parameter is less affected by the MCG noise, especially at low signal-to-noise ratios. Therefore, we believe that the proposed fSampEn parameter could improve estimates of respiratory muscle effort from MMGdi signals with the presence of MCG interference. PMID:24586436

  10. Evidence towards improved estimation of respiratory muscle effort from diaphragm mechanomyographic signals with cardiac vibration interference using sample entropy with fixed tolerance values.

    PubMed

    Sarlabous, Leonardo; Torres, Abel; Fiz, José A; Jané, Raimon

    2014-01-01

    The analysis of amplitude parameters of the diaphragm mechanomyographic (MMGdi) signal is a non-invasive technique to assess respiratory muscle effort and to detect and quantify the severity of respiratory muscle weakness. The amplitude of the MMGdi signal is usually evaluated using the average rectified value or the root mean square of the signal. However, these estimations are greatly affected by the presence of cardiac vibration or mechanocardiographic (MCG) noise. In this study, we present a method for improving the estimation of the respiratory muscle effort from MMGdi signals that is robust to the presence of MCG. This method is based on the calculation of the sample entropy using fixed tolerance values (fSampEn), that is, with tolerance values that are not normalized by the local standard deviation of the window analyzed. The behavior of the fSampEn parameter was tested in synthesized mechanomyographic signals, with different ratios between the amplitude of the MCG and clean mechanomyographic components. As an example of application of this technique, the use of fSampEn was explored also in recorded MMGdi signals, with different inspiratory loads. The results with both synthetic and recorded signals indicate that the entropy parameter is less affected by the MCG noise, especially at low signal-to-noise ratios. Therefore, we believe that the proposed fSampEn parameter could improve estimates of respiratory muscle effort from MMGdi signals with the presence of MCG interference.

  11. Adaptive Estimation of Personalized Maximum Tolerated Dose in Cancer Phase I Clinical Trials Based on All Toxicities and Individual Genomic Profile

    PubMed Central

    Chen, Zhengjia; Li, Zheng; Zhuang, Run; Yuan, Ying; Kutner, Michael; Owonikoko, Taofeek; Curran, Walter J.; Kowalski, Jeanne

    2017-01-01

    Background Many biomarkers have been shown to be associated with the efficacy of cancer therapy. Estimation of personalized maximum tolerated doses (pMTDs) is a critical step toward personalized medicine, which aims to maximize the therapeutic effect of a treatment for individual patients. In this study, we have established a Bayesian adaptive Phase I design which can estimate pMTDs by utilizing patient biomarkers that can predict susceptibility to specific adverse events and response as covariates. Methods Based on a cutting-edge cancer Phase I clinical trial design called escalation with overdose control using normalized equivalent toxicity score (EWOC-NETS), which fully utilizes all toxicities, we propose new models to incorporate patient biomarker information in the estimation of pMTDs for novel cancer therapeutic agents. The methodology is fully elaborated and the design operating characteristics are evaluated with extensive simulations. Results Simulation studies demonstrate that the utilization of biomarkers in EWOC-NETS can estimate pMTDs while maintaining the original merits of this Phase I trial design, such as ethical constraint of overdose control and full utilization of all toxicity information, to improve the accuracy and efficiency of the pMTD estimation. Conclusions Our novel cancer Phase I designs with inclusion of covariate(s) in the EWOC-NETS model are useful to estimate a personalized MTD and have substantial potential to improve the therapeutic effect of drug treatment. PMID:28125617

  12. Polonium purification

    SciTech Connect

    Baker, J.D.

    1996-09-01

    Three processes for the purification of {sup 210}Po from irradiated bismuth targets are described. Safety equipment includes shielded hotcells for the initial separation from other activation products, gloveboxes for handling the volatile and highly toxic materials, and provisions for ventilation. All chemical separations must be performed under vacuum or in inerted systems. Two of the processes require large amounts of electricity; the third requires vessels made from exotic materials.

  13. Tolerating Zero Tolerance?

    ERIC Educational Resources Information Center

    Moore, Brian N.

    2010-01-01

    The concept of zero tolerance dates back to the mid-1990s when New Jersey was creating laws to address nuisance crimes in communities. The main goal of these neighborhood crime policies was to have zero tolerance for petty crime such as graffiti or littering so as to keep more serious crimes from occurring. Next came the war on drugs. In federal…

  14. Assessing public health risk in the London polonium-210 incident, 2006.

    PubMed

    Maguire, H; Fraser, G; Croft, J; Bailey, M; Tattersall, P; Morrey, M; Turbitt, D; Ruggles, R; Bishop, L; Giraudon, I; Walsh, B; Evans, B; Morgan, O; Clark, M; Lightfoot, N; Gilmour, R; Gross, R; Cox, R; Troop, P

    2010-06-01

    Mr Alexander Litvinenko died in a London hospital on 23 November 2006, allegedly from poisoning with the radionuclide polonium-210 ((210)Po). Associated circumstances required an integrated response to investigate the potential risk of internal contamination for individuals exposed to contaminated environments. Descriptive study. Contaminated locations presenting a potential risk to health were identified through environmental assessment by radiation protection specialists. Individuals connected with these locations were identified and assessed for internal contamination with (210)Po. In total, 1029 UK residents were identified, associated with the 11 most contaminated locations. Of these, 974 were personally interviewed and 787 were offered urine tests for (210)Po excretion. Overall, 139 individuals (18%) showed evidence of probable internal contamination with (210)Po arising from the incident, but only 53 (7%) had assessed radiation doses of 1mSv or more. The highest assessed radiation dose was approximately 100mSv. Although internal contamination with (210)Po was relatively frequent and was most extensive among individuals associated with locations judged a priori to pose the greatest risk, a high degree of assurance could be given to UK and international communities that the level of health risk from exposure to the radionuclide in this incident was low. Copyright 2010 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

  15. Wet precipitation of major ions, polonium-210, and organic carbon in a metropolitan city, Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Yan, G.; Kim, G.

    2011-12-01

    An extensive survey of chemical constituents in precipitation including dissolved organic carbon, dissolved nitrogen, major ions, trace elements, and radionuclides was conducted in a representative urban environment of Seoul over one-year period from 2009 to 2010. The sources for these chemical species were apportioned by applying principal component analysis (PCA) in association with commonly acknowledged key tracers, such as Na, K, Ca, and V. The fossil fuel combustion (especially coal) was shown to be the dominant source for most constituents being investigated, with biomass burning being recognized as another significant source. With the aid of air mass backward trajectory analyses, we concluded that the primary fraction of the chemical species in our precipitation samples originated locally in Korea, albeit the frequent long-range transport from the eastern and northeastern China might contribute substantially. Overall, our study suggests the significant role of human activities in altering the atmospheric environment of Seoul and presumably most urban areas around the world, highlighting its profound environmental implications, such as health risks posed by excessive polonium-210, enhanced rainwater acidity from organic acids, and radiative forcing by organic aerosols.

  16. Suspected radioactive contamination: evaluation of 45 Israeli citizens potentially exposed to polonium-210 in London.

    PubMed

    Brosh-Nissimov, Tal; Havkin, Ofra; Davidovitch, Nadav; Poles, Lion; Shapira, Chen

    2008-02-01

    The lethal poisoning of Alexander Litvinenco with the radioactive element polonium-210, and the risk that many civilians (including Israeli citizens) who were in the same location in London at the same time were exposed to radiation, was an unprecedented event in the western world. This was only the second known death due to 210Po, a natural alpha radiation-emitting element. A task team was created to handle the event. The team comprised representatives from the Ministry of Health's advisory committee for radiological events (which includes the Israel Defense Force, the Israeli Atomic Energy Commission and the Ministry of Environmental Protection), the Public Health Services Central District, and a public relations expert. Forty-seven people were located and underwent an epidemiological inquiry, and urine samples for detection of 210Po were sent abroad to a specialized laboratory. The radiotoxicological results were analyzed and evaluated by the expert team and follow-up recommendations were made. This unfamiliar and potentially stressful scenario was handled successfully by a multi-organizational multidisciplinary task team. The joint work of the task team was a real-life "exercise" simulating a radiological event in Israel. This team has recommended further evaluation of various vital missions in the event of any possible future radiological event, with special emphasis on a proactive communication approach to the media and the public.

  17. Deformation and mixing of coexisting shapes in neutron-deficient polonium isotopes

    NASA Astrophysics Data System (ADS)

    Kesteloot, N.; Bastin, B.; Gaffney, L. P.; Wrzosek-Lipska, K.; Auranen, K.; Bauer, C.; Bender, M.; Bildstein, V.; Blazhev, A.; Bönig, S.; Bree, N.; Clément, E.; Cocolios, T. E.; Damyanova, A.; Darby, I.; De Witte, H.; Di Julio, D.; Diriken, J.; Fransen, C.; García-Ramos, J. E.; Gernhäuser, R.; Grahn, T.; Heenen, P.-H.; Hess, H.; Heyde, K.; Huyse, M.; Iwanicki, J.; Jakobsson, U.; Konki, J.; Kröll, T.; Laurent, B.; Lecesne, N.; Lutter, R.; Pakarinen, J.; Peura, P.; Piselli, E.; Próchniak, L.; Rahkila, P.; Rapisarda, E.; Reiter, P.; Scheck, M.; Seidlitz, M.; Sferrazza, M.; Siebeck, B.; Sjodin, M.; Tornqvist, H.; Traykov, E.; Van De Walle, J.; Van Duppen, P.; Vermeulen, M.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.; Zielińska, M.

    2015-11-01

    Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient Po 196 ,198 ,200 ,202 isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, Po,202200, the transitional and diagonal matrix elements of the 21+ state are determined. In Po,198196 multistep Coulomb excitation is observed, populating the 41+,02+ , and 22+ states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from 196Po onwards. Three model descriptions are used to compare to the data. Calculations with the beyond-mean-field model, the interacting boson model, and the general Bohr Hamiltonian model show partial agreement with the experimental data. Finally, calculations with a phenomenological two-level mixing model hint at the mixing of a spherical structure with a weakly deformed rotational structure.

  18. Studies of Polonium Removal from Molten Lead-Bismuth for Lead-Alloy-Cooled Reactor Applications

    SciTech Connect

    Jacopo Buongiorno; Ken Czerwinski; Eric Loewen; Chris Larson

    2004-09-01

    The isotope 210Po is the main product of neutron activation in fast reactors cooled by molten lead-bismuth eutectic (LBE). The isotope 210Po is a pure alpha emitter with a half-life of 138.38 days. For typical values of the neutron flux the 210Po concentration in the coolant can reach 1-10 Ci/kg. While exposure of plant personnel to Po is prevented under normal operating conditions because the primary system is sealed, Po does pose a radiological hazard during maintenance activities for which access to submerged structures is required as well as during accidents resulting in breach of the primary-system barrier. Obviously, continuous removal of Po from the LBE reduces this hazard. Therefore, it is important to understand the mechanisms by which Po is formed in and released from the LBE. We summarize research performed at the Idaho National Engineering and Environmental Laboratory and the Massachusetts Institute of Technology to investigate the basic chemistry of four mechanisms of Po release, which could serve as the basis for a coolant cleanup system in LBE-cooled reactors. The mechanisms explored are lead polonide evaporation, formation of polonium hydride, rare-earth filtering, and alkaline extraction. For the key chemical species involved expressions are given for useful quantities such as formation energy, release, and deposition rates. It is concluded that the most promising removal mechanism is alkaline extraction, although a more systematic investigation of this mechanism is needed.

  19. Studies of Polonium Removal from Molten Lead-Bismuth for Lead-Alloy-Cooled Reactor Applications

    SciTech Connect

    Buongiorno, Jacopo; Loewen, Eric P.; Czerwinski, Kenneth; Larson, Christopher

    2004-09-15

    The isotope {sup 210}Po is the main product of neutron activation in fast reactors cooled by molten lead-bismuth eutectic (LBE). The isotope {sup 210}Po is a pure alpha emitter with a half-life of 138.38 days. For typical values of the neutron flux the {sup 210}Po concentration in the coolant can reach 1-10 Ci/kg. While exposure of plant personnel to Po is prevented under normal operating conditions because the primary system is sealed, Po does pose a radiological hazard during maintenance activities for which access to submerged structures is required as well as during accidents resulting in breach of the primary-system barrier. Obviously, continuous removal of Po from the LBE reduces this hazard. Therefore, it is important to understand the mechanisms by which Po is formed in and released from the LBE. We summarize research performed at the Idaho National Engineering and Environmental Laboratory and the Massachusetts Institute of Technology to investigate the basic chemistry of four mechanisms of Po release, which could serve as the basis for a coolant cleanup system in LBE-cooled reactors. The mechanisms explored are lead polonide evaporation, formation of polonium hydride, rare-earth filtering, and alkaline extraction. For the key chemical species involved expressions are given for useful quantities such as formation energy, release, and deposition rates. It is concluded that the most promising removal mechanism is alkaline extraction, although a more systematic investigation of this mechanism is needed.

  20. MATLAB-implemented estimation procedure for model-based assessment of hepatic insulin degradation from standard intravenous glucose tolerance test data.

    PubMed

    Di Nardo, Francesco; Mengoni, Michele; Morettini, Micaela

    2013-05-01

    Present study provides a novel MATLAB-based parameter estimation procedure for individual assessment of hepatic insulin degradation (HID) process from standard frequently-sampled intravenous glucose tolerance test (FSIGTT) data. Direct access to the source code, offered by MATLAB, enabled us to design an optimization procedure based on the alternating use of Gauss-Newton's and Levenberg-Marquardt's algorithms, which assures the full convergence of the process and the containment of computational time. Reliability was tested by direct comparison with the application, in eighteen non-diabetic subjects, of well-known kinetic analysis software package SAAM II, and by application on different data. Agreement between MATLAB and SAAM II was warranted by intraclass correlation coefficients ≥0.73; no significant differences between corresponding mean parameter estimates and prediction of HID rate; and consistent residual analysis. Moreover, MATLAB optimization procedure resulted in a significant 51% reduction of CV% for the worst-estimated parameter by SAAM II and in maintaining all model-parameter CV% <20%. In conclusion, our MATLAB-based procedure was suggested as a suitable tool for the individual assessment of HID process. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  1. Death by polonium-210: lessons learned from the murder of former Soviet spy Alexander Litvinenko.

    PubMed

    McFee, Robin B; Leikin, Jerrold B

    2009-02-01

    The medical response to radiation--whether the result of radiological warfare, terrorist deployment of improvised radiation dispersal weapons, political assassination, occupational or industrial accidents or the medically radiated patient remains one of the least taught among all disciplines within medical education. In the aftermath of 9/11 among medical vulnerabilities to toxicant threats, of all the categories of weapons of mass destruction (WMD)--whether using the CBRNE (chemical, biological, radiological, nuclear, explosive) or NBC (nuclear, biological, chemical) acronym--radiation is the least taught in professional schools, responder cultures or civil preparedness organizations. To date, few health care professionals (HCP) possess the fundamental knowledge or skills to identify and diagnose, let alone treat a radiation victim; this vulnerability made even more obvious in the aftermath of the high profile assassination of former Russian agent Alexander Litvinenko. He was poisoned with Polonium210. Radioactive substances are ubiquitous with radiation sources being in or transported through virtually every region nationwide. It is essential to increase preparedness among community and rural health care facilities as well as urban and university hospitals. Managing radiation injuries effectively requires access to specialized equipment and expertise. Radiation sickness is progressive and may require acute, critical and long-term care throughout the course of illness. Regardless of the source, preparedness rests upon acknowledging a threat exists and dedicating the resources to address the risks including the enhancement of training and equipment. Mass or individual exposures to radiation present unique challenges to the entire response continuum from law enforcement, first responders and emergency medical care. Increased education about and practice in responding to radiological threats is essential to enhance preparedness.

  2. Evaluating the trophic transfer of cadmium, polonium, and methylmercury in an estuarine food chain.

    PubMed

    Mathews, Teresa; Fisher, Nicholas S

    2008-05-01

    We examined the transfer of Cd, methylmercury (MeHg), and Po in an estuarine food chain (from phytoplankton to zooplankton [Daphnia pulex] to killifish [Fundulus heteroclitus] and, finally, to juvenile striped bass [Morone saxatilis]) to better understand both the extent to which these elements may biomagnify and the underlying mechanisms governing this biomagnification. Among the phytoplankton examined (Cyclotella meneghiniana and Chlamdomonas reinhardtii), metal uptake was rapid, and volume concentration factors for all metals reached values between 10(4) and 10(5). The resulting assimilation efficiencies (AEs) of ingested metals in all animals were highest for MeHg, with values greater than 76%. The AEs of Cd were 21 to 33% in D. pulex, 1 to 16% in F. heteroclitus, and 38 to 56% in M. saxatilis. Polonium AEs were 69 to 87% in D. pulex, 25 to 41% in F. heteroclitus, and 9 to 21% in M. saxatilis. Loss rate constants (ke) of metals in D. pulex ranged from 0.04/d for MeHg to 0.39/d for Po; metal ke values for F. heteroclitus ranged from 0.01 to 0.02/d. Using a kinetic model, we showed that the trophic transfer factor, defined as the ratio of metal concentration in predatory animals to metal concentration in prey organisms, was greater than unity for all three metals in D. pulex feeding on phytoplankton, suggesting that these metals may be biomagnified at this trophic step. In killifish feeding on D. pulex, the trophic transfer factor was consistently greater than one for MeHg, consistently less than one for Cd, and from 0.1 to 1.4 for Po, suggesting that both MeHg and Po have the potential to biomagnify at this trophic step.

  3. The international follow-up of individuals potentially exposed to polonium-210 in London 2006.

    PubMed

    Shaw, K; Anders, K; Olowokure, B; Fraser, G; Maguire, H; Bailey, M; Smith, J; Frossell, S; Yap, K; Evans, B

    2010-06-01

    Following a death from polonium-210 ((210)Po), contamination was found at several sites in London. This paper describes the UK Health Protection Agency's follow-up and assessment of individuals resident overseas who were potentially exposed to (210)Po. Descriptive follow-up study. Individuals were classified into three exposure groups (higher, lower and unknown). Presence and degree of internal contamination were measured by 24-h urinary (210)Po activity (mBq/day). Results over 30mBq/day were taken to indicate probable contact with (210)Po in this incident. Dose assessments were conducted to determine degree of exposure and to identify individuals requiring further follow-up. Overall, 664 potentially exposed persons from 52 countries and territories were identified. Of these, 157 (24%) were in the higher exposure category, and urinary measurements were reported for 31% (48/157). Results for 19% (9/48) of those at higher exposure were more than 30mBq/day. For those at lower exposure, the percentage was 4% (3/68). Results above 30mBq/day were significantly more likely to be reported for the higher exposure category than the lower exposure category (Fisher's exact test P=0.010). Reported dose assessments suggested that identified individuals were not at increased health risk in the long term. Challenges and practical lessons were identified during the investigation. The results suggest that it is unlikely that any overseas resident had significant internal contamination with (210)Po. However, this incident clearly demonstrated the scale of international involvement likely to be necessary in other public health emergencies in large cities. The lessons identified have implications for the international health community, particularly with regard to the follow-up of individuals exposed to radiation in one country who then travel to another. Copyright 2010 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

  4. Polonium-210 accumulates in a lake receiving coal mine discharges-anthropogenic or natural?

    PubMed

    Nelson, A W; Eitrheim, E S; Knight, A W; May, D; Wichman, M D; Forbes, T Z; Schultz, M K

    2017-02-01

    Coal is an integral part of global energy production; however, coal mining is associated with numerous environmental health impacts. It is well documented that coal-mine waste can contaminate the environment with naturally-occurring radionuclides from the uranium-238 ((238)U) decay series. However, the behavior of the final radionuclide in the (238)U-series, i.e., polonium-210 ((210)Po) arising from coal-mine waste-water discharge is largely unexplored. Here, results of a year-long (2014-2015) field study, in which the concentrations of (210)Po in sediments and surface water of a lake that receives coal-mine waste-water discharge in West Virginia are presented. Initial measurements identified levels of (210)Po in the lake sediments that were in excess of that which could be attributed to ambient U-series parent radionuclides; and were indicative of discharge site contamination of the lake ecosystem. However, control sediment obtained from a similar lake system in Iowa (an area with no coal mining or unconventional drilling) suggests that the levels of (210)Po in the lake are a natural phenomenon; and are likely unrelated to waste-water treatment discharges. Elevated levels of (210)Po have been reported in lake bottom sediments previously, yet very little information is available on the radioecological implications of (210)Po accumulation in lake bottom sediments. The findings of this study suggest that (Monthly Energy Review, 2016) the natural accumulation and retention of (210)Po in lake sediments may be a greater than previously considered (Chadwick et al., 2013) careful selection of control sites is important to prevent the inappropriate attribution of elevated levels of NORM in lake bottom ecosystems to industrial sources; and (Van Hook, 1979) further investigation of the source-terms and potential impacts on elevated (210)Po in lake-sediment ecosystems is warranted. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Polonium Issue in Fast Reactor Lead Coolants and One of the Ways of Its Solution

    SciTech Connect

    Khorasanov, G.L.; Ivanov, A.P.; Blokhin, A.I.

    2002-07-01

    One of the main issues in using materials for nuclear facilities is to minimize the production of the most hazardous radionuclides. In the ideal case, all nuclear reactor materials, except a fuel, should be low-activation. The term 'low-activation material' means that this one loses its induced activity in a short time after removal from irradiation. Proposals for building a fusion reactor using low-activation materials are given in Ref.1, 2. For this purpose, low-activation structural materials based on V-Ti-Cr alloys are in the stage of R and D in several countries [3,4]. Another technique to avoid the hazardous activity is in using isotopically enriched materials [5-7]. Although isotopic tailoring option requires tremendous technical efforts and it is too expensive, its application can be first of all assumed for those structural and functional materials which generate very hazardous radionuclides under irradiation. In modern projects of next generation NPPs the preference is given to fast reactors (FRs) with a lead coolant [8]. As it known, the coolant circulating through a FR core is activated, and in the future we should have problems with handling a completed coolant after FR decommissioning or at realization of repair or emergency activities. There, it is desirable to have a low-activation coolant with the low contents of hazardous radionuclides. In papers [9,10] presented at the previous ICONE conferences it was proposed to use lead isotope, Pb-206, as a coolant instead of lead natural, Pb-nat. This paper is devoted to more detailed calculations of accumulating stable bismuth, Bi-209, and polonium radioisotopes, Po-209 (T{sub 1/2}=102 y) and Po-210 (T{sub 1/2}=138 d), in 1 kg of Pb-nat or Pb-206 placed in the core of the BOR-60 type FR. (authors)

  6. Radon-222 and Polonium-210 in the Martian Atmosphere: A New Insight into the Exchange of Volatiles and the Dust Cycle

    NASA Astrophysics Data System (ADS)

    Meslin, P.-Y.; Sabroux, J.-C.; Chassefière, E.; Pineau, J.-F.

    2007-03-01

    We expose how 222radon and 210polonium can be used as geochemical probes to characterize the subsurface (water and 238U content, gas exchange) and the dust cycle. We present the first evidence of 210Po on Mars and make comparisons with the Moon.

  7. Estimating Broad Sense Heritability and Investigating the Mechanism of Genetic Transmission of Cold Tolerance Using Mannitol as a Measure of Post-freeze Juice Degradation in Sugarcane and Energycane (Saccharum spp.).

    PubMed

    Hale, Anna L; Viator, Ryan P; Eggleston, Gillian; Hodnett, George; Stelly, David M; Boykin, Debbie; Miller, Donnie K

    2016-03-02

    In approximately 25% of the sugarcane-producing countries worldwide, conventional sugarcane (Saccharum spp. hybrids) is exposed to damaging freezes. A study was conducted during the 2009 and 2010 harvest seasons to compare late-season freeze tolerance among three groups: commercial Louisiana sugarcane genotypes, early generation genotypes selected for cold tolerance in the U.S. Department of Agriculture sugarcane breeding programs at Houma, LA, and Canal Point, FL, and potential energycane genotypes selected for high total biomass per acre. Mannitol concentrations in cane juice following freezing temperatures were determined to evaluate levels of cold tolerance. Genotypes selected for cold tolerance in Houma, LA, had significantly more late-season freeze tolerance than commercial sugarcane genotypes and genotypes selected in Canal Point, FL. Genotypes showing the most cold tolerance were Ho02-146 and Ho02-152, and those that were most highly susceptible were US87-1006 and US87-1003 (early-generation breeding genotypes) and L99-233 (commercial genotype). Broad-sense heritability for late-season cold tolerance in the two-year study was estimated at g(2) = 0.78. The enzymatic mannitol analysis successfully differentiated high-fiber energycane genotypes from those from other sources.

  8. The Onset of Collectivity in Neutron-Deficient POLONIUM-200,198,196

    NASA Astrophysics Data System (ADS)

    Bernstein, Lee Allen

    This dissertation concerns the study of discrete, low spin and high spin states in the three even-mass polonium (Z = 84) isotopes; ^{200}Po, ^{198}Po and ^{196}Po. The reactions used to study the nuclei were: ^{172} Yb(^{28}Si,4n) ^{196}Po at beam energies of 141 and 145 MeV; ^{174}Yb( ^{29}Si,5n)^ {198}Po at beam energies of 141 and 146 MeV; ^{176}Yb( ^{29}Si,5n)^{200 }Po at a beam energy of 146 MeV. The experiment studying ^{196}Po was performed at Argonne National Laboratory using the Argonne -Notre Dame array, which consists of 12 Compton-suppressed Ge detectors and a 50 element BGO inner ball of detectors. The other two nuclei were studied at Lawrence Berkeley Laboratory using the High Energy Resolution Array, which consisted of 20 Compton suppressed Ge detectors and a 40 element BGO inner ball. Decay schemes of yrast and near-yrast states, including probable spin and parity assignments, were built in spite of sizable backgrounds from fission, Coulomb excitation, and transfer reactions. The purpose of the present work was to study the transition from single-particle to collective behavior in the low-lying states. The systematic behavior of the low-lying states, including ratios of the yrast state energies and branching ratios of transitions depopulating the 2 _sp{2}{+} and 4_sp{2}{+} states, were studied. The transition was described using a composite of the shell model and the vibrational limit of the liquid drop model. It was determined that the yrast 2 ^+ and 4^+ states are collective for ^{208-196} Po. However, the yrast 6^+ state remains predominantly a non-collective excitation until ^{196}Po, where it becomes an excellent example of vibrational behavior. This can be attributed to the opening of the neutron i _{13/2} orbital near ^ {198}Po (N = 114), which causes larger overlap between the valence protons and neutrons. In addition to the transitional behavior of the low-lying states, high spin level schemes were established for all three nuclei

  9. The inflow of polonium (210)Po from Vistula river catchments area.

    PubMed

    Skwarzec, Bogdan; Jahnz, Anna

    2007-12-01

    The activities of polonium (210)Po in Vistula unfiltered water samples, collected from November 2002 to November 2003, were measured using the alpha spectrometry. In winter, the highest concentration of (210)Po was in Vistula river water from Torun (2.72 +/- 0.04 Bq x m(-3)) and from the Wieprz river (5.46 +/- 0.07 Bq x m(-3) [Bequerel per cubic metre]), and the lowest was in water from Nida river (0.59 +/- 0.02 Bq x m(-3)). During spring, the highest concentration of (210)Po was observed in Vistula water collected in Deblin (5.98 +/- 0.03 Bq x m(-3)) and the lowest in water from the Narew river (1.20 +/- 0.12 Bq x m(-3)). In summer, the highest concentration of (210)Po was in Nogat river water collected in Malbork (3.18 +/- 0.04 Bq x m(-3)) and the Bzura river (5.30 +/- 0.02 Bq x m(-3)), the lowest in Wieprz river (0.49 +/- 0.09 Bq x m(-3)) and Vistula river water from Kraków (1.44 +/- 0.05 Bq x m(-3)). In autumn, the highest (210)Po concentration was in Bzura river (8.93 +/- 0.03 Bq x m(-3)), the lowest in Vistula water from Grudziadz (1.51 +/- 0.04 Bq x m(-3)), and Toruń (1.89 +/- 0.05 Bq x m(-3)). The highest quantity of (210)Po was transported from Vistula catchments area to the Baltic Sea in spring and the lowest in summer. Annually, the southern Baltic Sea is enriched by about 73.7 GBq (210)Po (with Leniwka and Nogat rivers), with 71.6 GBq going to Gdańsk Bay and 2.1 GBq to Vistula Lagoon. The highest surface (210)Po runoff was observed in spring (to 1370 kBq x km(-2) x quarter(-1) for Dunajec catchment's area), the lowest in summer (for Nida catchment's area to 100 kBq x km(-2) x quarter(-1)).

  10. Mobilization Of Polonium-210 In Naturally-Contaminated Groundwater, Churchill County, Nevada

    NASA Astrophysics Data System (ADS)

    Seiler, R. L.; Stillings, L. L.; Cutler, N.

    2009-12-01

    Polonium-210 activities in groundwater rarely exceed about 40 mBq/L because it strongly binds to sediments. The recent discovery of natural 210Po at levels ranging from below 1 to 6,300±280 mBq/L in 62 drinking-water wells in Lahontan Valley, Churchill County, Nevada, led to a geochemical investigation of the processes responsible for its mobilization from the aquifer sediments. The source of the 210Po is radioactive decay of uranium in sediments transported into the valley by erosion of granitic rocks in the Sierra Nevada during the Pleistocene. There is little spatial or depth variability in 210Pb activity in study-area sediments (average 35 Bq/kg) and detailed analysis at a contaminated well indicates mobilization of <0.5 percent of the 210Po in the sediments would account for all of the 210Po in the well water. Elevated 210Po activities (>200 mBq/L) are associated with anoxic water (DO <0.1 mg/L) with high pH (commonly >9.0). Investigations in the 1980s by William Burnett and colleagues of naturally-contaminated wells in Florida showed that 210Po was mobilized by sulfate-reducing bacteria and remained in solution as long as sulfides did not accumulate above certain levels. Similarly, δ34SSO4 values in Lahontan Valley indicate that significant sulfate reduction has occurred in wells containing >200 mBq/L of 210Po, but sulfide is not accumulating and its concentrations are low (<0.03 mg/L) in 25 of 28 of those wells. In our working hypothesis, mobilization of 210Po in Lahontan Valley is linked to reduction of Mn oxides by sulfide in an anaerobic sulfur cycle (Figure 1). Such a sulfur cycle is consistent with the high pH, less than predicted δ18OSO4 values, low sulfide concentrations, and presence of elemental sulfur in the water. Results from the Nevada and Florida investigations suggest that 210Po contamination may be more widespread than previously recognized, occurring in groundwater near uranium-mine operations and other uranium containing sediments when

  11. Phonon softening and superconductivity triggered by spin-orbit coupling in simple-cubic α-polonium crystals

    NASA Astrophysics Data System (ADS)

    Kang, Chang-Jong; Kim, Kyoo; Min, B. I.

    2012-08-01

    We have investigated the mechanism of stabilizing the simple-cubic (sc) structure in polonium (α-Po), based on the phonon dispersion calculations using the first-principles all-electron band method. We have demonstrated that the stable sc structure results from the suppression of the Peierls instability due to the strong spin-orbit coupling (SOC) in α-Po. We have also discussed the structural chirality realized in β-Po, as a consequence of the phonon instability. Further, we have explored the possible superconductivity in α-Po, and predicted that it becomes a superconductor with Tc˜4 K. The transverse soft phonon mode at q≈(2)/(3)R, which is greatly influenced by the SOC, plays an important role both in the structural stability and the superconductivity in α-Po.

  12. Investigation of intravalence, core-valence and core-core electron correlation effects in polonium atomic structure calculations

    NASA Astrophysics Data System (ADS)

    Quinet, Pascal

    2014-09-01

    A detailed investigation of the atomic structure and radiative parameters involving the lowest states within the 6p4, 6p36d, 6p37s, 6p37p and 6p37d configurations of neutral polonium is reported in the present paper. Using different physical models based on the pseudo-relativistic Hartree-Fock approach, the influence of intravalence, core-valence and core-core electron correlation on the atomic parameters is discussed in detail. This work allowed us to fix the spectroscopic designation of some experimental level energy values and to provide for the first time a set of reliable oscillator strengths corresponding to 31 Po I spectral lines in the wavelength region from 175 to 987 nm.

  13. Sequential extraction procedure for determination of uranium, thorium, radium, lead and polonium radionuclides by alpha spectrometry in environmental samples

    NASA Astrophysics Data System (ADS)

    Oliveira, J. M.; Carvalho, F. P.

    2006-01-01

    A sequential extraction technique was developed and tested for common naturally-occurring radionuclides. This technique allows the extraction and purification of uranium, thorium, radium, lead, and polonium radionuclides from the same sample. Environmental materials such as water, soil, and biological samples can be analyzed for those radionuclides without matrix interferences in the quality of radioelement purification and in the radiochemical yield. The use of isotopic tracers (232U, 229Th, 224Ra, 209Po, and stable lead carrier) added to the sample in the beginning of the chemical procedure, enables an accurate control of the radiochemical yield for each radioelement. The ion extraction procedure, applied after either complete dissolution of the solid sample with mineral acids or co-precipitation of dissolved radionuclide with MnO2 for aqueous samples, includes the use of commercially available pre-packed columns from Eichrom® and ion exchange columns packed with Bio-Rad resins, in altogether three chromatography columns. All radioactive elements but one are purified and electroplated on stainless steel discs. Polonium is spontaneously plated on a silver disc. The discs are measured using high resolution silicon surface barrier detectors. 210Pb, a beta emitter, can be measured either through the beta emission of 210Bi, or stored for a few months and determined by alpha spectrometry through the in-growth of 210Po. This sequential extraction chromatography technique was tested and validated with the analysis of certified reference materials from the IAEA. Reproducibility was tested through repeated analysis of the same homogeneous material (water sample).

  14. Use of lung toxicity and lung particle clearance to estimate the maximum tolerated dose (MTD) for a fiber glass chronic inhalation study in the rat.

    PubMed

    Hesterberg, T W; McConnel, E E; Miiller, W C; Chevalier, J; Everitt, J; Thevenaz, P; Fleissner, H; Oberdörster, G

    1996-07-01

    Short-term toxicity and lung clearance were assessed in rats exposed by inhalation to size-selected fibrous glass (FG) for 13 weeks. Results from this study and from a recent FG chronic inhalation study are presented here as guidelines for the selection of a maximum tolerated dose (MTD) for chronic inhalation studies of fibers. Fischer 344 rats were exposed using nose-only inhalation chambers, 6 hr/day, 5 days/week, for 13 weeks to one of five concentrations of FG (36, 206, 316, 552, or 714 fibers/cc; expressed gravimetrically, 3, 16, 30, 45, or 60 mg/m3) or to filtered air. Rats were then held for an additional 10 weeks of postexposure recovery. Test fiber was size-selected from glass wool having a chemical composition representative of building insulation. Rats were terminated at 7, 13, 19, and 23 weeks after the onset of exposure to evaluate pulmonary pathology, lung epithelium cell proliferation, lung fiber burden, and lung lavage cells and chemistry. The effect of fiber inhalation on lung clearance of innocuous microspheres was also evaluated: following fiber exposure, six rats/group were exposed to 85Sr-labeled 3.0-microns polystyrene microspheres by intratracheal inhalation and then monitored for whole-body radioactivity during the 10-week recovery period. Data from the short-term study support the choice of 30 mg/m3 as the MTD for the previous chronic FG study and also provide indicators of long-term lung toxicity and functional impairment that can be used to estimate the MTD for future chronic fiber inhalation studies.

  15. Activity concentrations of (137)Caesium and (210)Polonium in seafood from fishing regions of New Zealand and the dose assessment for seafood consumers.

    PubMed

    Pearson, Andrew J; Gaw, Sally; Hermanspahn, Nikolaus; Glover, Chris N

    2016-01-01

    A study was undertaken to determine activity concentrations for (134)Caesium, (137)Caesium and (210)Polonium in New Zealand seafood, and establish if activity concentrations varied with respect to species/ecological niche and coastal region. Thirty seafood samples were obtained from six fishing regions of New Zealand along with a further six samples of two commercially important species (hoki and arrow squid) with well-defined fisheries. (134)Caesium was not detected in any sample. (137)Caesium was detected in 47% of samples, predominantly in pelagic fish species, with most activities at a trace level. Detections of (137)Caesium were evenly distributed across all regions. Activity concentrations were consistent with those expected from the oceanic inventory representing residual fallout from global nuclear testing. (210)Polonium was detected above the minimum detectable concentration in 33 (92%) of the analysed samples. Molluscs displayed significantly elevated activity concentrations relative to all other species groups. No significant regional variation in activity concentrations were determined. Two dose assessment models for high seafood consumers were undertaken. Dose contribution from (137)Caesium was minimal and far below the dose exemption limit of 1 mSv/year. Exposure to (210)Polonium was significant in high seafood consumers at 0.44-0.77 mSv/year (5th-95th percentile). (137)Caesium is concluded to be a valuable sentinel radionuclide for monitoring anthropogenic releases, such as global fallout and reactor releases, in the marine environment. (210)Polonium is of importance as a natural radionuclide sentinel due to its high contribution to dietary committed dose in seafood consumers. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Polonium (²¹⁰Po), uranium (²³⁴U, ²³⁸U) isotopes and trace metals in mosses from Sobieszewo Island, northern Poland.

    PubMed

    Boryło, Alicja; Nowicki, Waldemar; Olszewski, Grzegorz; Skwarzec, Bogdan

    2012-01-01

    The activity of polonium (210)Po and uranium (234)U, (238)U radionuclides, as well as trace metals in mosses, collected from Sobieszewo Island area (northern Poland), were determined using the alpha spectrometry, AAS (atomic absorption spectrometry) and OES-ICP (atomic emission spectrometry with inductively coupled plasma). The concentrations of mercury (directly from the solid sample) were determined by the cold vapor technique of CV AAS. The obtained results revealed that the concentrations of (210)Po, (234)U, and (238)U in the two analyzed kinds of mosses: schrebers big red stem moss (Pleurozium schreberi) and broom moss (Dicranum scoparium) were similar. The higher polonium concentrations were found in broom moss (Dicranum scoparium), but uranium concentrations were relatively low for both species of analyzed mosses. Among the analyzed trace metals the highest concentration in mosses was recorded for iron, while the lowest for nickel, cadmium and mercury. The obtained studies showed that the sources of polonium and uranium isotopes, as well as trace metals in analyzed mosses are air city contaminations transported from Gdańsk and from existing in the vicinity the phosphogypsum waste heap in Wiślinka (near Gdańsk).

  17. Improving crop salt tolerance.

    PubMed

    Flowers, T J

    2004-02-01

    Salinity is an ever-present threat to crop yields, especially in countries where irrigation is an essential aid to agriculture. Although the tolerance of saline conditions by plants is variable, crop species are generally intolerant of one-third of the concentration of salts found in seawater. Attempts to improve the salt tolerance of crops through conventional breeding programmes have met with very limited success, due to the complexity of the trait: salt tolerance is complex genetically and physiologically. Tolerance often shows the characteristics of a multigenic trait, with quantitative trait loci (QTLs) associated with tolerance identified in barley, citrus, rice, and tomato and with ion transport under saline conditions in barley, citrus and rice. Physiologically salt tolerance is also complex, with halophytes and less tolerant plants showing a wide range of adaptations. Attempts to enhance tolerance have involved conventional breeding programmes, the use of in vitro selection, pooling physiological traits, interspecific hybridization, using halophytes as alternative crops, the use of marker-aided selection, and the use of transgenic plants. It is surprising that, in spite of the complexity of salt tolerance, there are commonly claims in the literature that the transfer of a single or a few genes can increase the tolerance of plants to saline conditions. Evaluation of such claims reveals that, of the 68 papers produced between 1993 and early 2003, only 19 report quantitative estimates of plant growth. Of these, four papers contain quantitative data on the response of transformants and wild-type of six species without and with salinity applied in an appropriate manner. About half of all the papers report data on experiments conducted under conditions where there is little or no transpiration: such experiments may provide insights into components of tolerance, but are not grounds for claims of enhanced tolerance at the whole plant level. Whether enhanced

  18. Normal Tissue Complication Probability Estimation by the Lyman-Kutcher-Burman Method Does Not Accurately Predict Spinal Cord Tolerance to Stereotactic Radiosurgery

    SciTech Connect

    Daly, Megan E.; Luxton, Gary; Choi, Clara Y.H.; Gibbs, Iris C.; Chang, Steven D.; Adler, John R.; Soltys, Scott G.

    2012-04-01

    Purpose: To determine whether normal tissue complication probability (NTCP) analyses of the human spinal cord by use of the Lyman-Kutcher-Burman (LKB) model, supplemented by linear-quadratic modeling to account for the effect of fractionation, predict the risk of myelopathy from stereotactic radiosurgery (SRS). Methods and Materials: From November 2001 to July 2008, 24 spinal hemangioblastomas in 17 patients were treated with SRS. Of the tumors, 17 received 1 fraction with a median dose of 20 Gy (range, 18-30 Gy) and 7 received 20 to 25 Gy in 2 or 3 sessions, with cord maximum doses of 22.7 Gy (range, 17.8-30.9 Gy) and 22.0 Gy (range, 20.2-26.6 Gy), respectively. By use of conventional values for {alpha}/{beta}, volume parameter n, 50% complication probability dose TD{sub 50}, and inverse slope parameter m, a computationally simplified implementation of the LKB model was used to calculate the biologically equivalent uniform dose and NTCP for each treatment. Exploratory calculations were performed with alternate values of {alpha}/{beta} and n. Results: In this study 1 case (4%) of myelopathy occurred. The LKB model using radiobiological parameters from Emami and the logistic model with parameters from Schultheiss overestimated complication rates, predicting 13 complications (54%) and 18 complications (75%), respectively. An increase in the volume parameter (n), to assume greater parallel organization, improved the predictive value of the models. Maximum-likelihood LKB fitting of {alpha}/{beta} and n yielded better predictions (0.7 complications), with n = 0.023 and {alpha}/{beta} = 17.8 Gy. Conclusions: The spinal cord tolerance to the dosimetry of SRS is higher than predicted by the LKB model using any set of accepted parameters. Only a high {alpha}/{beta} value in the LKB model and only a large volume effect in the logistic model with Schultheiss data could explain the low number of complications observed. This finding emphasizes that radiobiological models

  19. Radiation Tolerant Embedded Memory

    DTIC Science & Technology

    2007-11-02

    REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 ...currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YYYY) 27-06-2003 2. REPORT TYPE SBIR...Tolerant Embedded Memory 1 Table of Contents: Table of Contents

  20. Polonium-210 and selenium in tissues and tissue extracts of the mussel Mytilus galloprovincialis (Gulf of Trieste).

    PubMed

    Kristan, Urška; Planinšek, Petra; Benedik, Ljudmila; Falnoga, Ingrid; Stibilj, Vekoslava

    2015-01-01

    Marine organisms such as mussels and fish take up polonium (Po) and selenium (Se), and distribute them into different cellular components and compartments. Due to its high radiotoxicity and possible biomagnification across the marine food chain Po-210 is potentially hazardous, while selenium is an essential trace element for humans and animals. The aim of this study was to investigate and compare the presence and extractability of the elements in the mussels Mytilus galloprovincialis collected in the Gulf of Trieste. The levels of Po-210 in the samples ranged from 220 to 400 Bq kg(-1) and of Se from 2.6 to 8.2 mg kg(-1), both on a dry matter basis. Using various extraction types and conditions in water, buffer or enzymatic media, the best extractability was obtained with enzymatic extraction (Protease XIV, 1h shaking at 40 °C) and the worst by water extraction (24 h shaking at 37 °C). 90% of Po-210 and 70% of Se was extractable in the first case versus less than 10% of Po-210 and less than 40% of Se in the second. Such evident differences in extractability between the investigated elements point to different metabolic pathways of the two elements. In enzymatic extracts Se speciation revealed three Se compounds (SeCys2, SeMet, one undefined), while Po-210 levels were too low to allow any conclusions about speciation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Structural Stability Driven by the Spin-Orbit Coupling and the Superconductivity in simple-cubic Polonium

    NASA Astrophysics Data System (ADS)

    Kang, Chang-Jong; Kim, Kyoo; Min, B. I.

    2013-03-01

    Polonium is the only element which has the simple-cubic (SC) structure in the periodic table. We have studied its structural stability based on the phonon dispersion calculations using the first-principles all-electron full-potential band method. We have demonstrated that the strong spin-orbit coupling (SOC) in SC-Po suppresses the Peierls instability and makes the SC structure stable. We have also discussed the structural chirality realized in beta-Po, as a consequence of the phonon instability. Further, we have investigated the possible superconductivity in SC-Po, and predicted that it becomes a superconductor with Tc ~ 4 K at ambient pressure. The transverse soft phonon mode at q ~ 2/3 R, which is greatly affected by the SOC, plays an important role both in the structural stability and the superconductivity in SC-Po. We have explored effects of the SOC and the volume variation on the phonon dispersions and superconducting properties of SC-Po.

  2. Composition of tobaccos from countries with high and low incidences of lung cancer. I. Selenium, polonium-210, Alternaria, tar, and nicotine

    SciTech Connect

    Bogden, J.D.; Kemp, F.W.; Buse, M.; Thind, I.S.; Louria, D.B.; Forgacs, J.; Llanos, G.; Terrones, I.M.

    1981-01-01

    Tobaccos from countries with high and low incidences of lung cancer were analyzed. Tobacco concentrations of polonium-210 were similar in cigarettes from high- and low-incidence countries, as were levels of cigarette smoke tar and nicotine. Tobaccos from low-incidence countries had significantly lower Alternaria spore counts. Mean selenium concentrations of tobaccos from the high-incidence countries (0.16 +- 0.05 ..mu..g/g) were significantly lower than those of tobaccos from the low-incidence countries (0.49 +- 0.22 ..mu..g/g).

  3. Tolerability and toxicity of prophylactic cranial irradiation in patients with non-small cell lung cancer – Results of a phase II study (with estimation of hematological toxicity, pituitary function and magnetic resonance spectra changes)

    PubMed Central

    Marzena, Gawkowska-Suwińska; Sławomir, Blamek; Alicja, Heyda; Łukasz, Boguszewicz; Anna, Cichoń; Łukasz, Zarudzki; Elżbieta, Nowicka; Katarzyna, Behrendt; Beata, Smolska-Ciszewska; Grzegorz, Plewicki; Aleksander, Zajusz; Rafał, Tarnawski

    2014-01-01

    Aim To evaluate the tolerability and toxicity of PCI in patients with NSCLC. Background Prophylactic cranial irradiation (PCI) is a standard treatment for patients with small cell lung cancer. There are data showing a decreasing ratio of brain metastases after PCI for non-small cell lung cancer (NSCLC-non small cell lung cancer) patients but, so far, there is no evidence for increasing overall survival. The main concern in this setting is the tolerance and toxicity of the treatment. Materials and methods From 1999 to 2007, 50 patients with NSCLC treated with radical intent underwent PCI (30 Gy in 15 fractions). Mean follow-up was 2.8 years. The tolerability and hematological toxicity were evaluated in all patients, a part of participants had done neuropsychological tests, magnetic resonance imaging with 1H nuclear magnetic resonance spectra, and estimation of pituitary function. Results During follow-up, 20 patients developed distant metastases, 4-brain metastases. Fourteen (30%) patients had acute side effects: (headache, nausea, erythema of the skin). The symptoms did not require treatment breaks. Six patients complained of late side effects (vertigo, nausea, anxiety, lower extremity weakness, deterioration of hearing and olfactory hyperesthesia). Hematological complications were not observed. Testosterone levels tended to decrease (p = 0.062). Visual-motor function deteriorated after treatment (p < 0.059). Performance IQ decreased (p < 0.025) and the difference between performance IQ and verbal IQ increased (p < 0.011). Degenerative periventricular vascular changes were observed in two patients. Analysis of the spectroscopic data showed metabolic but reversible alterations after PCI. Conclusion PCI in the current series was well tolerated and associated with a relatively low toxicity. PMID:25337408

  4. Estimation of Anticipated Performance Index and Air Pollution Tolerance Index and of vegetation around the marble industrial areas of Potwar region: bioindicators of plant pollution response.

    PubMed

    Noor, Mehwish Jamil; Sultana, Shazia; Fatima, Sonia; Ahmad, Mushtaq; Zafar, Muhammad; Sarfraz, Maliha; Balkhyour, Masour A; Safi, Sher Zaman; Ashraf, Muhammad Aqeel

    2015-06-01

    Mitigating industrial air pollution is a big challenge, in such scenario screening of plants as a bio monitor is extremely significant. It requires proper selection and screening of sensitive and tolerant plant species which are bio indicator and sink for air pollution. The present study was designed to evaluate the Air Pollution Tolerance Index (APTI) and Anticipated Performance Index (API) of the common flora. Fifteen common plant species from among trees, herb and shrubs i.e. Chenopodium album (Chenopodiaceae), Parthenium hysterophorus (Asteraceae), Amaranthus viridis (Amaranthaceae), Lantana camara (Verbenaceaea), Ziziphus nummulari (Rhamnaceae), Silibum merianum (Asteraceae), Cannabis sativa (Cannabinaceae), Calatropis procera (Asclepediaceae), Ricinus communis (Euphorbiaceae), Melia azadirachta (Meliaceae), Psidium guajava (Myrtaceae), Eucalyptus globules (Myrtaceae), Broussonetia papyrifera (Moraceae), Withania somnifera (Solanaceae) and Sapium sabiferum (Euphorbiaceae) were selected growing frequently in vicinity of Marble industries in Potwar region. APTI and API of selected plant species were analyzed by determining important biochemical parameter i.e. total chlorophyll, ascorbic acid, relative water content and pH etc. Furthermore the selected vegetation was studied for physiological, economic, morphological and biological characteristics. The soil of studied sites was analyzed. It was found that most the selected plant species are sensitive to air pollution. However B. papyrifera, E. globulus and R. communis shows the highest API and therefore recommended for plantation in marble dust pollution stress area.

  5. Polonium behaviour in reservoirs potentially affected by acid mine drainage (AMD) in the Iberian Pyrite Belt (SW of Spain).

    PubMed

    Blasco, M; Gázquez, M J; Pérez-Moreno, S M; Grande, J A; Valente, T; Santisteban, M; de la Torre, M L; Bolívar, J P

    2016-02-01

    The province of Huelva is one of the areas most affected by acid mine drainage (AMD) in the world, which can produce big enhancements and fractionations in the waters affected by AMD. There are very few studies on this issue, and none on polonium-210. Twenty-two water reservoirs were sampled, and the (210)Po was measured in both dissolution and particulate phases. The (210)Po concentrations in the waters were in the same order of magnitude to those ones for unperturbed systems, although the data published to particulate matter are very scarce. A mean value and standard uncertainty for (210)Po of 0.25 ± 0.03 mBq L(-1) in the dissolved matter, and 62 ± 9 mBq g(-1) in the particulate matter can be established as base line for the reservoirs of the Huelva area. The distribution coefficients (kd) range from 10(4) to 10(6) L kg(-1), in agreement to the found ones by other authors for the case of neutral waters, but being the lowest values for the more acidic reservoirs. It has been also found that (210)Po has a high tendency to be associated to the particulate matter for neutral-alkaline waters, however, under extreme acid conditions (pH < 3), increases the Po tendency to be associated to the dissolved phase. Therefore, the main conclusion obtained in this work is that AMD has no a significant influence on the total activity concentration of (210)Po in the waters of reservoirs, but the acidity has a clear influence on its distribution between both dissolved and the particulate phases. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Experimental Investigation of Evaporation Behavior of Polonium and Rare-Earth Elements in Lead-Bismuth Eutectic Pool

    SciTech Connect

    Shuji Ohno; Shinya Miyahara; Yuji Kurata; Ryoei Katsura; Shigeru Yoshida

    2006-07-01

    Equilibrium evaporation behavior was experimentally investigated for polonium ({sup 210}Po) in liquid lead-bismuth eutectic (LBE) and for rare-earth elements gadolinium (Gd) and europium (Eu) in LBE to understand and clarify the transfer behavior of toxic impurities from LBE coolant to a gas phase. The experiments utilized the 'transpiration method' in which saturated vapor in an isothermal evaporation pot was transported by inert carrier gas and collected outside of the pot. While the previous paper ICONE12-49111 has already reported the evaporation behavior of LBE and of tellurium in LBE, this paper summarizes the outlines and the results of experiments for important impurity materials {sup 210}Po and rare-earth elements which are accumulated in liquid LBE as activation products and spallation products. In the experiments for rare-earth elements, non-radioactive isotope was used. The LBE pool is about 330-670 g in weight and has a surface area of 4 cm x 14 cm. {sup 210}Po experiments were carried out with a smaller test apparatus and radioactive {sup 210}Po produced through neutron irradiation of LBE in the Japan Materials Testing Reactor (JMTR). We obtained fundamental and instructive evaporation data such as vapor concentration, partial vapor pressure of {sup 210}Po in the gas phase, and gas-liquid equilibrium partition coefficients of the impurities in LBE under the temperature condition between 450 and 750 deg. C. The {sup 210}Po test revealed that Po had characteristics to be retained in LBE but was still more volatile than LBE solvent. A part of Eu tests implied high volatility of rare-earth elements comparable to that of Po. This tendency is possibly related to the local enrichment of the solute near the pool surface and needs to be investigated more. These results are useful and indispensable for the evaluation of radioactive materials transfer to the gas phase in LBE-cooled nuclear systems. (authors)

  7. Intolerant tolerance.

    PubMed

    Khushf, G

    1994-04-01

    The Hyde Amendment and Roman Catholic attempts to put restrictions on Title X funding have been criticized for being intolerant. However, such criticism fails to appreciate that there are two competing notions of tolerance, one focusing on the limits of state force and accepting pluralism as unavoidable, and the other focusing on the limits of knowledge and advancing pluralism as a good. These two types of tolerance, illustrated in the writings of John Locke and J.S. Mill, each involve an intolerance. In a pluralistic context where the free exercise of religion is respected, John Locke's account of tolerance is preferable. However, it (in a reconstructed form) leads to a minimal state. Positive entitlements to benefits like artificial contraception or nontherapeutic abortions can legitimately be resisted, because an intolerance has already been shown with respect to those that consider the benefit immoral, since their resources have been coopted by taxation to advance an end that is contrary to their own. There is a sliding scale from tolerance (viewed as forbearance) to the affirmation of communal integrity, and this scale maps on to the continuum from negative to positive rights.

  8. Pesticide Tolerances

    EPA Pesticide Factsheets

    EPA regulates pesticides used to protect crops and sets limits on the amount of pesticide remaining in or on foods in the U.S. The limits on pesticides on foods are called tolerances in the U.S. (maximum residue limits (MRLs) in many other countries).

  9. Religious Tolerance.

    ERIC Educational Resources Information Center

    Martz, Carlton

    2000-01-01

    This theme issue looks at three issues of religious tolerance. The first article examines a case recently decided by the United States Supreme Court on student-led prayers at school events. The second article explores the persecution suffered by members of the Mormon religion during the 19th century. The final article looks at Martin Luther and…

  10. A study on possible use of Urtica dioica (common nettle) plant as polonium (210)Po and lead (210)Pb contamination biomonitor in the area of phosphogypsum stockpile.

    PubMed

    Olszewski, Grzegorz; Boryło, Alicja; Skwarzec, Bogdan

    2016-04-01

    The aim of this study was to test a possible use of Urtica dioica (common nettle) plant as a biomonitor of polonium (210)Po and lead (210)Pb contamination near phosphogypsum stacks by determining concentrations of these radionuclides in samples collected from the area of phosphogypsum stockpile in Wiślinka (northern Poland). The (210)Po and (210)Pb contents in roots depended on their concentrations in soils. Bioconcentration factor values from soil to root of the plant did not depend on (210)Po and (210)Pb contents in soils that leads to the conclusion that different polonium and lead species have different affinities to U. dioica plants. The main sources of both analyzed radionuclides in green parts of plants are wet and dry air deposition and transportation from soil. The values of (210)Po/(210)Pb activity ratio indicate natural origin of these radioisotopes in analyzed plants. (210)Po and (210)Pb concentration in U. dioica roots is negatively weakly correlated with distance from phosphogypsum stockpile.

  11. Nitrate tolerance.

    PubMed

    Parker, J O

    1987-11-16

    The organic nitrates are the most widely used agents in the management of patients with angina pectoris. When initially administered by the oral route, the nitrates produce profound changes in systemic hemodynamics and significant and prolonged improvement in exercise duration. It has been shown that during short periods of regular oral nitrate administration, the hemodynamic, antiischemic and antianginal effects of the nitrates are greatly reduced. Thus, when initially administered, oral isosorbide dinitrate prolongs exercise duration for a period of several hours, but during sustained 4-times-daily therapy, exercise tolerance is improved for only 2 hours after administration. Studies with transdermal preparations of isosorbide dinitrate and nitroglycerin also show improvement during short-term administration for up to 8 hours, but after several days of once-daily therapy, the effects of these agents are similar to placebo. It is apparent that nitrate tolerance is a clinically relevant problem. Although tolerance develops rapidly during nitrate therapy, it is reversed promptly during nitrate-free periods. Oral nitrates maintain their antianginal effects when given 2 or 3 times daily with provision of a nitrate-free period. Studies are currently underway to investigate the effects of intermittent administration schedules with transdermal nitrate preparations.

  12. A double-blind, placebo-controlled pilot study to estimate the efficacy and tolerability of a nonsteroidal cream for the treatment of cradle cap (seborrheic dermatitis).

    PubMed

    David, Elmer; Tanuos, Hanan; Sullivan, Timothy; Yan, Albert; Kircik, Leon H

    2013-04-01

    This study was a multicenter, double-blind, placebo-controlled, parallel-group pilot study of efficacy and tolerability of a nonsteroidal cream (Promiseb® Topical Cream; Promius Pharma, LLC, Bridgewater, NJ) for treatment of cradle cap when applied topically twice daily for up to 14 days in 42 pediatric subjects. Both treatments were similarly effective in reducing disease severity, as measured by success with Investigator's Global Assessment scores at day 7 or end of treatment, with 96% of subjects achieving success in the nonsteroidal cream group and 92% of subjects achieving success in the placebo cream group. Both treatments resulted in significant reductions from baseline in terms of erythema, crusting, scaling, and oiliness (P<.05), with no significant difference between treatments. There was a significant difference (P=.03) between treatment groups for percent reduction in scaling at the end of treatment, with a 90% reduction in the nonsteroidal cream group compared with a 58% reduction in the placebo cream group. All subjects in both groups had an overall safety score of excellent, and there were no adverse events related to treatment for either group.

  13. Polonium in size fractionated mainstream cigarette smoke, predicted deposition and associated internal radiation dose.

    PubMed

    Tiwari, M; Sahu, S K; Bhangare, R C; Pandit, G G

    2016-10-01

    In this study, size fractionated mass and (210)Po activity concentrations in mainstream cigarette smoke (MCS) were monitored for three popular cigarette brands. Size segregated collection of MCS was carried out using a cascade type impactor, while mass and (210)Po activity concentration were analyzed gravimetrically and alpha spectrometry (following the radiochemical separation) respectively. Multiple-Path Particle Dosimetry (MPPD V2.11) model is used for prediction of deposition fraction calculations for the MCS deposition in different compartment of human respiratory tract. The activity concentration of (210)Po is founds 10.56 ± 2.46 mBq per cigarette for the tested cigarette brands. (210)Po size distribution indicates most of this associates with fine fraction (Dp < 2.23 μm) of cigarette smoke. The committed annual effective dose to smokers (smoking on an average 20 cigarette a day), considering the (210)Po and (210)Pb concentrations (assuming it is in secular equilibrium with (210)Po) in MCS, was estimated between 0.22 and 0.40 mSv, with mean value of 0.30 mSv for tested cigarette brands. Considering the risk factor of fatal cancer due to radiation exposure of lung (exposure time of 30 years); the average collective estimated fatal cancer risk is estimated as 1.5 × 10(-4) due to (210)Po and (210)Pb exposure to smokers. Copyright © 2016. Published by Elsevier Ltd.

  14. Cold tolerance in Arabidopsis kamchatica.

    PubMed

    Armstrong, Jessica J; Takebayashi, Naoki; Sformo, Todd; Wolf, Diana E

    2015-03-01

    • Cold tolerance is a critically important factor determining how plants will be influenced by climate change, including changes in snowcover and extreme weather events. Although a great deal is known about cold tolerance in Arabidopsis thaliana, it is not highly cold tolerant. This study examined cold tolerance and its genetic diversity in an herbaceous subarctic relative, Arabidopsis kamchatica, which generally occurs in much colder climates.• Thermal analysis and electrolyte leakage were used to estimate supercooling points and lethal temperatures (LT50) in cold-acclimated and nonacclimated families from three populations of A. kamchatica.• Arabidopsis kamchatica was highly cold tolerant, with a mean LT50 of -10.8°C when actively growing, and -21.8°C when cold acclimated. It also was able to supercool to very low temperatures. Surprisingly, actively growing plants supercooled more than acclimated plants (-14.7 vs. -12.7°C). There was significant genetic variation for cold tolerance both within and among populations. However, both cold tolerance and genetic diversity were highest in the midlatitude population rather than in the far north, indicating that adaptations to climate change are most likely to arise in the center of the species range rather than at the edges.• Arabidopsis kamchatica is highly cold tolerant throughout its range. It is far more freeze tolerant than A. thaliana, and supercooled to lower temperatures, suggesting that A. kamchatica provides a valuable complement to A. thaliana for cold tolerance research. © 2015 Botanical Society of America, Inc.

  15. Polonium-210 and lead-210 in the terrestrial environment: a historical review.

    PubMed

    Persson, Bertil R R; Holm, Elis

    2011-05-01

    The radionuclides (210)Po and (210)Pb widely present in the terrestrial environment are the final long-lived radionuclides in the decay of (238)U in the earth's crust. Their presence in the atmosphere is due to the decay of (222)Rn diffusing from the ground. The range of activity concentrations in ground level air for (210)Po is 0.03-0.3 Bq m(-3) and for (210)Pb 0.2-1.5 Bq m(-3). In drinking water from private wells the activity concentration of (210)Po is in the order of 7-48 mBq l(-1) and for (210)Pb around 11-40 mBq l(-1). From water works, however, the activity concentration for both (210)Po and (210)Pb is only in the order of 3 mBq l(-1). Mosses, lichens and peat have a high efficiency in capturing (210)Po and (210)Pb from atmospheric fallout and exhibit an inventory of both (210)Po and (210)Pb in the order of 0.5-5 kBq m(-2) in mosses and in lichens around 0.6 kBq m(-2). The activity concentrations in lichens lies around 250 Bq kg(-1), dry mass. Reindeer and caribou graze lichen which results in an activity concentration of (210)Po and (210)Pb of about 1-15 Bq kg(-1) in meat from these animals. The food chain lichen-reindeer or caribou, and Man constitutes a unique model for studying the uptake and retention of (210)Po and (210)Pb in humans. The effective annual dose due to (210)Po and (210)Pb in people with high consumption of reindeer/caribou meat is estimated to be around 260 and 132 μSv a(-1) respectively. In soils, (210)Po is adsorbed to clay and organic colloids and the activity concentration varies with soil type and also correlates with the amount of atmospheric precipitation. The average activity concentration levels of (210)Po in various soils are in the range of 20-240 Bq kg(-1). Plants become contaminated with radioactive nuclides both by absorption from the soil (supported Po) and by deposition of radioactive fallout on the plants directly (unsupported Po). In fresh leafy plants the level of (210)Po is particularly high as the result of the

  16. Microdosimetry of astatine-211 single-cell irradiation: role of daughter polonium-211 diffusion.

    PubMed

    Palm, Stig; Humm, John L; Rundqvist, Robert; Jacobsson, Lars

    2004-02-01

    A microdosimetric analysis of previously published data on 211At-albumin, free 211At, and 211At-C215 irradiation of Colo-205 cells in a slowly rotating single-cell suspension is presented. A custom-built computer program based on the Monte Carlo method was used to simulate the irradiation and the energy deposition in individual cell nuclei. Separate simulations were made for the assumption that the 211Po atom stays in the position where it is created, and that it diffuses away. The mean event number at which 37% of all cells survived, n37, and the frequency mean specific energy per event, zF, were estimated. The Poisson distribution of events and simulated single and multievent distributions of specific energy were used to find the single-cell specific energy at which the probability of survival is reduced to 37%, z37. The calculated single-cell radiosensitivity values show that 211Po atoms, created on a cell surface by the decay of 211At atoms, will diffuse from the cell during its life-span. The increasing distance to the cell nucleus will drastically decrease the probability of the emitted alpha particle to hit the nucleus. This will result in fewer alpha-particle events in the cell nucleus. For dispersed cells, the diffusion of 211Po atoms will reduce the total dose from cell-bound 211At by a factor of 2.

  17. Polonium-210 in marine mussels (bivalve molluscs) inhabiting the southern coast of India.

    PubMed

    Khan, M Feroz; Wesley, S Godwin; Rajan, M P

    2014-12-01

    The present study focused on the determination of the alpha-emitter, (210)Po, in two species of marine mussels (bivalve molluscs) commonly available in the southern coastal region of India. The brown mussel, Perna indica was collected from the west coast and the green mussel, Perna viridis from the east coast. The concentration of (210)Po was related to the allometry (length of shell, wet/dry weight of shell/soft tissue) of the mussels and significant results were found. The study period focused on three seasons namely, pre-monsoon, monsoon and post-monsoon for a 1-year period (2010-2011). The results revealed higher activity levels in smaller-sized mussels compared to larger ones. Marked variation in (210)Po activity concentration was noted in the whole-body soft tissues between seasons and sampling site (p < 0.05). The dose rate assessment for mussels was performed using the ERICA Assessment tool. The chronic exposure to mussels due to (210)Po was found to be lesser than the global benchmark dose rate of 10 μGy h(-1). The effective ingestion dose to adults who intake mussels was estimated to be in the range 5.1-34.9 μSv y(-1). The measurement contributes to the furthering of knowledge of (210)Po, since no data exist in this region. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Reproducibility of +Gz tolerance testing.

    PubMed

    Whinnery, J E; Jackson, W G

    1979-08-01

    The +Gz tolerance of USAF aircrewmen undergoing medical evaluation has been tested at the USAF School of Aerospace Medicine since 1973. For various reasons, the test protocol can usually be carried out only once on these patients. Accurate determination of the +Gz tolerance of aircrewmen who fly high performance fighter aircraft is very important in assuring aero-medical safety, since loss of consciousness as a result of exceeding a pilot's G tolerance may result in loss of life and loss of aircraft. It is, therefore, necessary to estimate the variability associated with each profile of the test so that a more accurate assessment of +Gz tolerance can be made. Multiple repeat medical evaluation test protocols were performed on 17 centrifuge acceleration panel members. The standard deviations in the +Gz measurements for the four centrifuge profiles were GOR(1) = 0.38 Gz, ROR=0.22 Gz, GOR(2)=0.34 Gz, and GOR(S)=0.39 Gz. A statistically significant learning effect, which increases +Gz tolerance, was observed in both experienced and inexperienced subjects. Knowledge of the variability associated with each test profile will allow a more accurate definition of an individual +Gz tolerance when only a single centrifuge test protocol can be performed. In addition, possible future use of this centrifuge protocol in the selection of individuals with above- or below-average +Gz tolerance is facilitated with an accurate assessment of the variability associated with the test.

  19. Biogeochemistry of lead-210 and polonium-210 in fresh waters and sediments. Final report, 1 September 1985-31 August 1987

    SciTech Connect

    Benoit, G.; Hemond, H.F.

    1988-05-01

    The objective was to investigate the behavior of toxic metals in lakes and streams using the naturally occurring radioactive metals lead-210 and polonium-210 as tracers. The radionuclides were measured as a function of position and time in a Massachusetts lake, its sediments and pore waters, and associated streams. A mass balance for the epilimnion showed that lead-210 direct uptake by bottom sediments was inconsequential. Below the epilimnion, a steep temperature/density gradient limited vertical transport. Anoxic conditions caused remobilization of iron and lead-210, which reprecipitated at the oxycline and returned to the bottom via settling. Below the oxycline, lead-210 and iron distributions resulted from constant release from anoxic sediments and dilution in the water column. Sediment lead-210 distributions were caused by sedimentation and Fickian transport.

  20. Polonium-210 and Caesium-137 in lynx (Lynx lynx), wolverine (Gulo gulo) and wolves (Canis lupus).

    PubMed

    Gjelsvik, Runhild; Holm, Elis; Kålås, John Atle; Persson, Bertil; Asbrink, Jessica

    2014-12-01

    Wolves, lynx and wolverines are on the top of the food-chain in northern Scandinavia and Finland. (210)Po and (137)Cs have been analysed in samples of liver, kidney and muscle from 28 wolves from Sweden. In addition blood samples were taken from 27 wolves. In 9 of the wolves, samples of muscle, liver and blood were analysed for (210)Po. Samples of liver and muscle were collected from 16 lynx and 16 wolverines from Norway. The liver samples were analysed for (210)Po and (137)Cs. Only (137)Cs analyses were carried out for the muscle samples. The wolves were collected during the winter 2010 and 2011, while the samples for lynx and wolverines were all from 2011. The activity concentrations of (210)Po in wolves were higher for liver (range 20-523 Bq kg(-1) d.w.) and kidney (range 24-942 Bq kg(-1) d.w.) than muscle (range 1-43 Bq kg(-1) d.w.) and blood (range 2-54 Bq kg(-1) d.w.). Activity ratios, (210)Po/(210)Pb, in wolf samples of muscle, liver and blood were in the ranges 2-77, 9-56 and 2-54. Using a wet weight ratio of 3.8 the maximal absorbed dose from (210)Po to wolf liver was estimated to 3500 μGy per year. Compared to wolf, the ranges of (210)Po in liver samples were lower in lynx (range 22-211 Bq kg(-1) d.w.) and wolverine (range16-160 Bq kg(-1) d.w.). Concentration of (137)Cs in wolf samples of muscle, liver, kidney and blood were in the ranges 70-8410 Bq kg(-1) d.w., 36-4050 Bq kg(-1) d.w., 31-3453 Bq kg(-1) d.w. and 4-959 Bq kg(-1) d.w., respectively. (137)Cs in lynx muscle and liver samples were in the ranges 44-13393 Bq kg(-1) d.w. and 125-10260 Bq kg(-1) d.w. The corresponding values for (137)Cs in wolverine were 22-3405 Bq kg(-1) d.w. for liver and 53-4780 Bq kg(-1) d.w. for muscle. The maximal absorbed dose from (137)Cs to lynx was estimated to 3000 μGy per year. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Using tolerance bounds in scientific investigations

    SciTech Connect

    Wendelberger, J.R.

    1996-07-01

    Assessment of the variability in population values plays an important role in the analysis of scientific data. Analysis of scientific data often involves developing a bound on a proportion of a population. Sometimes simple probability bounds are obtained using formulas involving known mean and variance parameters and replacing the parameters by sample estimates. The resulting bounds are only approximate and fail to account for the variability in the estimated parameters. Tolerance bounds provide bounds on population proportions which account for the variation resulting from the estimated mean and variance parameters. A beta content, gamma confidence tolerance interval is constructed so that a proportion beta of the population lies within the region bounded by the interval with confidence gamma. An application involving corrosion measurements is used to illustrate the use of tolerance bounds for different situations. Extensions of standard tolerance intervals are applied to generate regression tolerance bounds, tolerance bounds for more general models of measurements collected over time, and tolerance intervals for varying precision data. Tolerance bounds also provide useful information for designing the collection of future data.

  2. Imputing Risk Tolerance From Survey Responses

    PubMed Central

    Kimball, Miles S.; Sahm, Claudia R.; Shapiro, Matthew D.

    2010-01-01

    Economic theory assigns a central role to risk preferences. This article develops a measure of relative risk tolerance using responses to hypothetical income gambles in the Health and Retirement Study. In contrast to most survey measures that produce an ordinal metric, this article shows how to construct a cardinal proxy for the risk tolerance of each survey respondent. The article also shows how to account for measurement error in estimating this proxy and how to obtain consistent regression estimates despite the measurement error. The risk tolerance proxy is shown to explain differences in asset allocation across households. PMID:20407599

  3. Imputing Risk Tolerance From Survey Responses.

    PubMed

    Kimball, Miles S; Sahm, Claudia R; Shapiro, Matthew D

    2008-09-01

    Economic theory assigns a central role to risk preferences. This article develops a measure of relative risk tolerance using responses to hypothetical income gambles in the Health and Retirement Study. In contrast to most survey measures that produce an ordinal metric, this article shows how to construct a cardinal proxy for the risk tolerance of each survey respondent. The article also shows how to account for measurement error in estimating this proxy and how to obtain consistent regression estimates despite the measurement error. The risk tolerance proxy is shown to explain differences in asset allocation across households.

  4. Computer-Aided Reliability Estimation

    NASA Technical Reports Server (NTRS)

    Bavuso, S. J.; Stiffler, J. J.; Bryant, L. A.; Petersen, P. L.

    1986-01-01

    CARE III (Computer-Aided Reliability Estimation, Third Generation) helps estimate reliability of complex, redundant, fault-tolerant systems. Program specifically designed for evaluation of fault-tolerant avionics systems. However, CARE III general enough for use in evaluation of other systems as well.

  5. Methods and Data Used to Investigate Polonium-210 as a Source of Excess Gross-Alpha Radioactivity in Ground Water, Churchill County, Nevada

    USGS Publications Warehouse

    Seiler, Ralph L.

    2007-01-01

    Ground water is the major source of drinking water in the Carson River Basin, California and Nevada. Previous studies have shown that uranium and gross-alpha radioactivities in ground water can be greater than U.S. Environmental Protection Agency Maximum Contaminant Levels, particularly in the Carson Desert, Churchill County, Nevada. Studies also have shown that the primary source of the gross-alpha radioactivity and alpha-emitting radionuclides in ground water is the dissolution of uranium-rich granitic rocks and basin-fill sediments that have their origins in the Sierra Nevada. However, ground water sampled from some wells in the Carson Desert had gross-alpha radioactivities greater than could be accounted for by the decay of dissolved uranium. The occurrence of polonium-210 (Po-210) was hypothesized to explain the higher than expected gross-alpha radioactivities. This report documents and describes the study design, field and analytical methods, and data used to determine whether Po-210 is the source of excess gross-alpha radioactivity in ground water underlying the Carson Desert in and around Fallon, Nevada. Specifically, this report presents: 1) gross alpha and uranium radioactivities for 100 wells sampled from June to September 2001; and 2) pH, dissolved oxygen, specific conductance, and Po-210 radioactivity for 25 wells sampled in April and June 2007. Results of quality-control samples for the 2007 dataset are also presented.

  6. Performance characteristics of sequential separation and quantification of lead-210 and polonium-210 by ion exchange chromatography and nuclear spectrometric measurements.

    PubMed

    El Afifi, E M; Borai, E H

    2006-01-01

    A selective separation and quantitative determination procedure for 210Pb and 210Po in various environmental matrices from different sources such as IAEA-326 soil, phosphate rocks (PR), and phosphogypsum (PG) was developed. The tested samples were digested sequentially using concentrated mineral acids (HF, HNO3) by a programmable high-pressure microwave digestion system. The sample solution was loaded onto a preconditioned ion exchange column (Sr-resin) for chromatographic separation. Polonium-210 was eluted by 6 M HNO3 then spontaneously deposited onto polished silver discs to be measured using low-background alpha spectrometry. Lead-210 was sequentially eluted using 6 M HCl solution, precipitated as lead oxalate, dissolved in HNO3 solution, and mixed with scintillation cocktail to be measured by liquid scintillation counting (LSC). Performance of the developed procedure was tested using a reference soil (IAEA-326), with recommended isotope values, that was used as a quality control to assess separation and quantification efficiency (recovery %). The minimum detectable activities of 210Pb and 210Po were found to be 24 and 0.28 Bq kg(-1) for the measurements using LSC and alpha spectrometry, respectively. The recoveries (%) of 210Pb and 210Po were found to be 80 and 60%, respectively. To test the validity of the proposed LSC method, a comparative study was performed by measuring 210Pb activity concentration in test samples by nondestructive gamma-ray spectrometry.

  7. A study on lead (210Pb) and polonium (210Po) contamination from phosphogypsum in the environment of Wiślinka (northern Poland).

    PubMed

    Boryło, Alicja; Olszewski, Grzegorz; Skwarzec, Bogdan

    2013-08-01

    The results of polonium ((210)Po) and lead ((210)Pb) determination in different environmental soil samples collected in the vicinity of the phosphogypsum stack in Wiślinka (northern Poland) are presented and discussed in this paper. The (210)Po and (210)Pb concentrations in soil samples from the phosphogypsum stack recorded in this study are significantly higher only in areas that are close to the heap. The relationship between atmospheric deposition and elevated analyzed radionuclides concentrations in top soil layers, especially in the vicinity of the phosphogypsum stack, was showed in this study. (210)Po and (210)Pb radionuclides were detected in concentrations which could have harmful effects on human health or the environment. The considerably high concentrations of (210)Po and (210)Pb in soil samples collected from the vicinity of the phosphogypsum stack obtained in this study can lead to the conclusion that the presently undertaken recultivation process is successful and the 300 m(2) protection zone around the phosphogypsum stack seems to be able to offset the negative influence of the phosphogypsum stack on the surrounding environment.

  8. TASTRAK spectroscopy of polonium-210 alpha-particle activity at bone surfaces: Evidence for a concentrated surface deposit less than 3 {mu}m deep

    SciTech Connect

    Salmon, P.L.; Henshaw, D.L.; Keitch, P.A.; Allen, J.E.; Fews, A.P.

    1994-10-01

    The technique of {alpha}-particle spectroscopy by CR-39 type TASTRAK plastic has been used to study the depth distribution of natural {alpha}-particle emitters at the surface of human bone. The predominant component of this {alpha}-particle activity was {sup 210}Po supported by {sup 210}Pb, although a smaller activity of {sup 226}Ra was also detected. Autopsy samples of human femur and cranium were obtained from subjects age 63 to 86. Both cortical and trabecular surfaces were analyzed. The results indicate that {sup 210}Pb-supported {sup 210}Po is concentrated at the surfaces of human bone from elderly subjects, in a narrow band 3 {mu}m deep or less, by a factor of about four. As a result, the {alpha}-particle dose to the nuclei of cells lining bone surfaces is around 1.8 times greater than that calculated for a uniform volume distribution. Polonium-210 activity indicates the distribution of {sup 210}Pb, and of stable lead, received by continuous intake throughout life at a very low level. A persistent bone surface concentration of lead and other osteotropic metals may be associated with the hypermineralized layer about 1 {mu}m thick which occurs at the surface of resting bone mineral. 31 refs., 9 figs., 3 tabs.

  9. Macroevolutionary constraints to tolerance: trade-offs with drought tolerance and phenology, but not resistance.

    PubMed

    Pearse, Ian S; Aguilar, Jessica; Schroder, John; Strauss, Sharon Y

    2017-08-24

    Plant tolerance of herbivory, i.e., the ability to recover after damage, is an important component of how plants cope with herbivores. Tolerance has long been hypothesized to be constrained evolutionarily by plant resistance to herbivores, traits that allow plants to cope with stressful growing conditions, and traits that influence the timing of damage in relation to reproduction. Variation in tolerance and resistance can be caused by differences in the identity of the plant (e.g. genotype, species, clade) and by the context of the herbivore threat (e.g. identity of the herbivore, type of damage it causes, abiotic conditions in which the plant is growing). To date, the vast majority of studies have explored trade-offs with tolerance within species. Here, we test hypotheses of constraints on tolerance using comparative approaches in a clade of mustards, emphasizing the variety of contexts in which damage is realistically tolerated. We estimated tolerance to leaf damage, tolerance to apical clipping at the bolting stage- simulating browsing-, and resistance to a specialist and generalist lepidopteran herbivore for a group of native mustards, grown in field soils unique to each population and in a common potting soil. Resistance to herbivores was soil dependent, while surprisingly, tolerance was not. Phylogenetic signal in resistance to specialist and generalist lepidopteran herbivores was present, but only when plants were grown in field soils. Tolerance had low phylogenetic signal. Tolerance to leaf damage was unrelated to tolerance to simulated browse. We found no evidence for a resistance-tolerance trade-off, and some evidence for a soil-dependent positive correlation between tolerance and resistance to both herbivores. Drought-tolerant species had poorer ability to tolerate browse damage, and earlier flowering species tended to be less tolerant to leaf damage. Our results suggest that tolerance trades off with traits that allow mostly annual, monocarpic

  10. Parametric Modeling and Fault Tolerant Control

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva; Ju, Jianhong

    2000-01-01

    Fault tolerant control is considered for a nonlinear aircraft model expressed as a linear parameter-varying system. By proper parameterization of foreseeable faults, the linear parameter-varying system can include fault effects as additional varying parameters. A recently developed technique in fault effect parameter estimation allows us to assume that estimates of the fault effect parameters are available on-line. Reconfigurability is calculated for this model with respect to the loss of control effectiveness to assess the potentiality of the model to tolerate such losses prior to control design. The control design is carried out by applying a polytopic method to the aircraft model. An error bound on fault effect parameter estimation is provided, within which the Lyapunov stability of the closed-loop system is robust. Our simulation results show that as long as the fault parameter estimates are sufficiently accurate, the polytopic controller can provide satisfactory fault-tolerance.

  11. Urban birds have broader environmental tolerance.

    PubMed

    Bonier, Frances; Martin, Paul R; Wingfield, John C

    2007-12-22

    Urbanization dramatically changes the composition and diversity of biotic communities. The characteristics distinguishing species that persist in urban environments, however, are poorly understood. Here we test the hypothesis that broadly adapted organisms are better able to tolerate urbanization, using a phylogenetically controlled, global comparison of birds. We compared elevational and latitudinal distributions of 217 urban birds found in 73 of the world's largest cities with distributions of 247 rural congeners to test the hypothesis that urban birds possess broader environmental tolerance. Urban birds had markedly broader environmental tolerance than rural congeners, as estimated by elevational and latitudinal distributions. Our results suggest that broad environmental tolerance may predispose some birds to thrive in urban habitats. The mechanisms mediating such environmental tolerance warrant further investigation, but probably include greater behavioural, physiological and ecological flexibility.

  12. Revoking Pesticide Tolerances

    EPA Pesticide Factsheets

    EPA revokes pesticide tolerances when all registrations of a pesticide have been canceled in the U.S. and the tolerances are not needed for imported foods or when there are no registered uses for certain crops.

  13. Lactose tolerance tests

    MedlinePlus

    Hydrogen breath test for lactose tolerance ... Two common methods include: Lactose tolerance blood test Hydrogen breath test The hydrogen breath test is the preferred method. It measures the amount of hydrogen in the air you breathe out. ...

  14. Zero Tolerance in Schools.

    ERIC Educational Resources Information Center

    Henault, Cherry

    2001-01-01

    Questions the effectiveness of the widespread use of zero-tolerance policies enacted by school boards to punish students who violate weapon and drug rules. Suggests that enforcement of zero-tolerance policies has not been equitable. Reviews proposal for alternative to zero tolerance. (PKP)

  15. Need for Tolerances and Tolerance Exemptions for Minimum Risk Pesticides

    EPA Pesticide Factsheets

    The ingredients used in minimum risk products used on food, food crops, food contact surfaces, or animal feed commodities generally have a tolerance or tolerance exemption. Learn about tolerances and tolerance exemptions for minimum risk ingredients.

  16. [Selenium tolerance of yeasts].

    PubMed

    Golubev, V I; Golubev, N V

    2002-01-01

    Selenium tolerance of yeasts widely varies: the growth of some yeasts can be inhibited by a selenium concentration as low as 10(-4) M, whereas others can grow in the presence of 10(-1) M selenium. Homogeneous yeast taxa are characterized by a certain level of selenium tolerance, and heterogeneous taxa show a variable level of tolerance to selenium. In general, ascomycetous yeasts are more tolerant to selenium than basidiomycetous yeasts. Among the ascomycetous yeasts, the genera Dekkera and Schizosaccharomyces exhibited the lowest and the species Candida maltosa, Hanseniaspora valbyensis, Kluyveromyces marxianus, and Yarrowia lipolytica the highest tolerance to selenium. Among the basidiomycetous yeasts, the genera Bullera, Cryptococcus, and Holtermannia showed the lowest and the species Cryptococcus curvatus, Cr. humicola, and Trichosporon spp. the highest tolerance to selenium. The selenium tolerance of yeasts depends on the composition of the growth medium, in particular, on the presence of sulfate, sulfur-containing amino acids, and glutamine in the medium.

  17. Public information needs after the poisoning of Alexander Litvinenko with polonium-210 in London: cross sectional telephone survey and qualitative analysis

    PubMed Central

    Page, Lisa; Morgan, Oliver; Pinder, Richard J; Riley, Paul; Hatch, Stephani; Maguire, Helen; Catchpole, Mike; Simpson, John; Wessely, Simon

    2007-01-01

    Objectives To identify public perceptions of the risk to health after the poisoning of Alexander Litvinenko with polonium-210 (210Po) in London and to assess the impact of public health communications. Design Cross sectional telephone survey and qualitative interviews. Setting London, United Kingdom. Participants 1000 people completed the cross sectional survey and 86 potentially exposed people completed the qualitative interviews. Main outcome measures Perception of risk to personal health after the 210Po incident. Qualitative interviews were analysed with an emphasis on information needs. Results 11.7% of the survey sample (n=117) perceived their health to be at risk. Aside from personal variables the main predictors of perceived risk to health were believing that the incident was related to terrorism (odds ratio 2.7, 95% confidence interval 1.5 to 4.6) rather than to espionage, that it was targeted at the wider public rather than one person (5.9, 3.2 to 10.9), and that it could affect people who had not been in the contaminated area (3.2, 2.1 to 5.1). Participants in the qualitative interviews were generally satisfied with the information they had received, although they would have preferred more information about their individual risk of exposure, the results of their urine tests, and the health implications of the incident. Conclusions Perceptions of the public that the 210Po incident in London in 2006 was related to espionage helped to reassure them that the risks to personal health were low. In the event of future incidents it is important to ensure that detailed, comprehensible information about the risks of any exposure is available. PMID:17975252

  18. Prevalence of and risks for internal contamination among hospital staff caring for a patient contaminated with a fatal dose of polonium-210.

    PubMed

    le Polain de Waroux, Olivier; Cohuet, Sandra; Bishop, Louise; Johnson, Sandra; Shaw, Karen; Maguire, Helen; Charlett, André; Fraser, Graham

    2011-10-01

    Alexander Litvinenko died on November 23, 2006, from acute radiation sickness syndrome caused by ingestion of polonium-210 (²¹⁰Po). The objective was to assess the prevalence of and risk factors for internal contamination with ²¹⁰Po in healthcare workers (HCWs) caring for the contaminated patient. Hospital. HCWs who had direct contact with the patient. We interviewed 43 HCWs and enquired about their activities and use of personal protective equipment (PPE). Internal contamination was defined as urinary ²¹⁰Po excretion above 20 mBq within 24 hours. We obtained risk ratios (RRs) for internal contamination using Poisson regression. Thirty-seven HCWs (86%) responded, and 8 (22%) showed evidence of internal contamination, all at very low levels that were unlikely to cause adverse health outcomes. Daily care of the patient (washing and toileting the patient) was the main risk factor (RR, 3.6 [95% confidence interval (CI), 1.1-11.6]). In contrast, planned invasive procedures were not associated with a higher risk. There was some evidence of a higher risk associated with handling blood samples (RR, 3.5 [95% CI, 0.8-15.6]) and changing urine bags and/or collecting urine samples (RR, 2.7 [95% CI, 0.8-9.5]). There was also some evidence that those who reported not always using standard PPE were at higher risk than were others (RR, 2.5 [95% CI, 0.8-8.1]). The sensitive quantitative measurement enabled us to identify factors associated with contamination, which by analogy to other conditions with similar transmission mechanisms may help improve protection and preparedness in staff dealing with an ill patient who experiences an unknown illness.

  19. Public information needs after the poisoning of Alexander Litvinenko with polonium-210 in London: cross sectional telephone survey and qualitative analysis.

    PubMed

    Rubin, G James; Page, Lisa; Morgan, Oliver; Pinder, Richard J; Riley, Paul; Hatch, Stephani; Maguire, Helen; Catchpole, Mike; Simpson, John; Wessely, Simon

    2007-12-01

    To identify public perceptions of the risk to health after the poisoning of Alexander Litvinenko with polonium-210 (210Po) in London and to assess the impact of public health communications. Cross sectional telephone survey and qualitative interviews. London, United Kingdom. 1000 people completed the cross sectional survey and 86 potentially exposed people completed the qualitative interviews. Perception of risk to personal health after the 210Po incident. Qualitative interviews were analysed with an emphasis on information needs. 11.7% of the survey sample (n=117) perceived their health to be at risk. Aside from personal variables the main predictors of perceived risk to health were believing that the incident was related to terrorism (odds ratio 2.7, 95% confidence interval 1.5 to 4.6) rather than to espionage, that it was targeted at the wider public rather than one person (5.9, 3.2 to 10.9), and that it could affect people who had not been in the contaminated area (3.2, 2.1 to 5.1). Participants in the qualitative interviews were generally satisfied with the information they had received, although they would have preferred more information about their individual risk of exposure, the results of their urine tests, and the health implications of the incident. Perceptions of the public that the 210Po incident in London in 2006 was related to espionage helped to reassure them that the risks to personal health were low. In the event of future incidents it is important to ensure that detailed, comprehensible information about the risks of any exposure is available.

  20. Acid tolerance in amphibians

    SciTech Connect

    Pierce, B.A.

    1985-04-01

    Studies of amphibian acid tolerance provide information about the potential effects of acid deposition on amphibian communities. Amphibians as a group appear to be relatively acid tolerant, with many species suffering increased mortality only below pH 4. However, amphibians exhibit much intraspecific variation in acid tolerance, and some species are sensitive to even low levels of acidity. Furthermore, nonlethal effects, including depression of growth rates and increases in developmental abnormalities, can occur at higher pH.

  1. Polyamines and abiotic stress tolerance in plants

    PubMed Central

    Gill, Sarvajeet Singh

    2010-01-01

    Environmental stresses including climate change, especially global warming, are severely affecting plant growth and productivity worldwide. It has been estimated that two-thirds of the yield potential of major crops are routinely lost due to the unfavorable environmental factors. On the other hand, the world population is estimated to reach about 10 billion by 2050, which will witness serious food shortages. Therefore, crops with enhanced vigour and high tolerance to various environmental factors should be developed to feed the increasing world population. Maintaining crop yields under adverse environmental stresses is probably the major challenge facing modern agriculture where polyamines can play important role. Polyamines (PAs)(putrescine, spermidine and spermine) are group of phytohormone-like aliphatic amine natural compounds with aliphatic nitrogen structure and present in almost all living organisms including plants. Evidences showed that polyamines are involved in many physiological processes, such as cell growth and development and respond to stress tolerance to various environmental factors. In many cases the relationship of plant stress tolerance was noted with the production of conjugated and bound polyamines as well as stimulation of polyamine oxidation. Therefore, genetic manipulation of crop plants with genes encoding enzymes of polyamine biosynthetic pathways may provide better stress tolerance to crop plants. Furthermore, the exogenous application of PAs is also another option for increasing the stress tolerance potential in plants. Here, we have described the synthesis and role of various polyamines in abiotic stress tolerance in plants. PMID:20592804

  2. Sulfur tolerant anode materials

    SciTech Connect

    Not Available

    1987-02-01

    The goal of this program is the development of a molten carbonate fuel cell (MCFC) anode which is more tolerant of sulfur contaminants in the fuel than the current state-of-the-art nickel-based anode structures. This program addresses two different but related aspects of the sulfur contamination problem. The primary aspect is concerned with the development of a sulfur tolerant electrocatalyst for the fuel oxidation reaction. A secondary issue is the development of a sulfur tolerant water-gas-shift reaction catalyst and an investigation of potential steam reforming catalysts which also have some sulfur tolerant capabilities. These two aspects are being addressed as two separate tasks.

  3. Sulfur tolerant anode materials

    SciTech Connect

    Not Available

    1988-02-01

    The goal of this program is the development of a molten carbonate fuel cell (MCFC) anode which is more tolerant of sulfur contaminants in the fuel than the current state-of-the-art nickel-based anode structures. This program addresses two different but related aspects of the sulfur contamination problem. The primary aspect is concerned with the development of a sulfur tolerant electrocatalyst for the fuel oxidation reaction. A secondary issue is the development of a sulfur tolerant water-gas-shift reaction catalyst and an investigation of potential steam reforming catalysts which also have some sulfur tolerant capabilities. These two aspects are being addressed as two separate tasks.

  4. Software Fault Tolerance: A Tutorial

    NASA Technical Reports Server (NTRS)

    Torres-Pomales, Wilfredo

    2000-01-01

    Because of our present inability to produce error-free software, software fault tolerance is and will continue to be an important consideration in software systems. The root cause of software design errors is the complexity of the systems. Compounding the problems in building correct software is the difficulty in assessing the correctness of software for highly complex systems. After a brief overview of the software development processes, we note how hard-to-detect design faults are likely to be introduced during development and how software faults tend to be state-dependent and activated by particular input sequences. Although component reliability is an important quality measure for system level analysis, software reliability is hard to characterize and the use of post-verification reliability estimates remains a controversial issue. For some applications software safety is more important than reliability, and fault tolerance techniques used in those applications are aimed at preventing catastrophes. Single version software fault tolerance techniques discussed include system structuring and closure, atomic actions, inline fault detection, exception handling, and others. Multiversion techniques are based on the assumption that software built differently should fail differently and thus, if one of the redundant versions fails, it is expected that at least one of the other versions will provide an acceptable output. Recovery blocks, N-version programming, and other multiversion techniques are reviewed.

  5. Maize aluminum tolerance

    USDA-ARS?s Scientific Manuscript database

    Maize is one of the most economically important food crops grown on acid soils, where aluminum (Al) toxicity greatly limits crop yields. Considerable variation for Al tolerance exists in maize, and this variation has been exploited for many years by plant breeders to enhance maize Al tolerance. Curr...

  6. A Lesson in Tolerance

    ERIC Educational Resources Information Center

    Johnt, Marlene

    2004-01-01

    This article describes one classroom's experience integrating a three-part lesson that focused on tolerance. In the lesson, students examined works by American folk-art painter Edward Hicks, researched quotes about tolerance in society, and applied calligraphy skills to an original composition.

  7. The Paradoxes of Tolerance

    ERIC Educational Resources Information Center

    Pasamonik, Barbara

    2004-01-01

    Teachers who endeavor to build tolerant attitudes in their students often fall into the trap of political correctness. Political correctness can suspend free reflection on the differences inherent in otherness, which is the subject of tolerance, and creates an ideology of the generalized, abstract Other. As a result, teachers prefer to talk about…

  8. 78 FR 33731 - Propamocarb; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ... Modeling System (PRZM/EXAMS) and Screening Concentration in Ground Water (SCI- GROW) models, the estimated.... The following list of North American Industrial Classification System (NAICS) codes is not intended to... of filing. Based upon review of the data supporting the petition, EPA has revised the tolerance...

  9. A statistical approach to investigating enhancement of polonium-210 in the Eastern Irish Sea arising from discharges from a former phosphate processing plant.

    PubMed

    Dewar, Alastair; Camplin, William; Barry, Jon; Kennedy, Paul

    2014-12-01

    Since the cessation of phosphoric acid production (in 1992) and subsequent closure and decommissioning (2004) of the Rhodia Consumer Specialties Limited plant in Whitehaven, the concentration levels of polonium-210 ((210)Po) in local marine materials have declined towards a level more typical of natural background. However, enhanced concentrations of (210)Po and lead-210 ((210)Pb), due to this historic industrial activity (plant discharges and ingrowth of (210)Po from (210)Pb), have been observed in fish and shellfish samples collected from this area over the last 20 years. The results of this monitoring, and assessments of the dose from these radionuclides, to high-rate aquatic food consumers are published annually in the Radioactivity in Food and the Environment (RIFE) report series. The RIFE assessment uses a simple approach to determine whether and by how much activity is enhanced above the normal background. As a potential tool to improve the assessment of enhanced concentrations of (210)Po in routine dose assessments, a formal statistical test, where the null hypothesis is that the Whitehaven area is contaminated with (210)Po, was applied to sample data. This statistical, modified "green", test has been used in assessments of chemicals by the OSPAR commission. It involves comparison of the reported environmental concentrations of (210)Po in a given aquatic species against its corresponding Background Assessment Concentration (BAC), which is based upon environmental samples collected from regions assumed to be not enhanced by industrial sources of (210)Po, over the period for which regular monitoring data are available (1990-2010). Unlike RIFE, these BAC values take account of the variability of the natural background level. As an example, for 2010 data, crab, lobster, mussels and winkles passed the modified "green" test (i.e. the null hypothesis is rejected) and as such are deemed not to be enhanced. Since the cessation of phosphoric acid production in 1992

  10. Antimicrobial Tolerance in Biofilms

    PubMed Central

    Stewart, Philip S.

    2015-01-01

    The tolerance of microorganisms in biofilms to antimicrobial agents is examined through a meta-analysis of literature data. A numerical tolerance factor comparing the rates of killing in the planktonic and biofilm states is defined to provide a quantitative basis for the analysis. Tolerance factors for biocides and antibiotics range over three orders of magnitude. This variation is not explained by taking into account the molecular weight of the agent, the chemistry of the agent, the substratum material, or the speciation of the microorganisms. Tolerance factors do depend on the areal cell density of the biofilm at the time of treatment and on the age of the biofilm as grown in a particular experimental system. This suggests that there is something that happens during biofilm maturation, either physical or physiological, that is essential for full biofilm tolerance. Experimental measurements of antimicrobial penetration times in biofilms range over orders of magnitude, with slower penetration (>12 min) observed for reactive oxidants and cationic molecules. These agents are retarded through the interaction of reaction, sorption, and diffusion. The specific physiological status of microbial cells in a biofilm contributes to antimicrobial tolerance. A conceptual framework for categorizing physiological cell states is discussed in the context of antimicrobial susceptibility. It is likely that biofilms harbor cells in multiple states simultaneously (e.g., growing, stress-adapted, dormant, inactive) and that this physiological heterogeneity is an important factor in the tolerance of the biofilm state. PMID:26185072

  11. Tolerance doses for treatment planning

    SciTech Connect

    Lyman, J.T.

    1985-10-01

    Data for the tolerance of normal tissues or organs to (low-LET) radiation has been compiled from a number of sources which are referenced at the end of this document. This tolerance dose data are ostensibly for uniform irradiation of all or part of an organ, and are for either 5% (TD/sub 5/) or 50% (TD/sub 50/) complication probability. The ''size'' of the irradiated organ is variously stated in terms of the absolute volume or the fraction of the organ volume irradiated, or the area or the length of the treatment field. The accuracy of these data is questionable. Much of the data represents doses that one or several experienced therapists have estimated could be safely given rather than quantitative analyses of clinical observations. Because these data have been obtained from multiple sources with possible different criteria for the definition of a complication, there are sometimes different values for what is apparently the same endpoint. The data from some sources shows a tendancy to be quantized in 5 Gy increments. This reflects the size of possible round off errors. It is believed that all these data have been accumulated without the benefit of 3-D dose distributions and therefore the estimates of the size of the volume and/or the uniformity of the irradiation may be less accurate than is now possible. 19 refs., 4 figs.

  12. Tolerance analysis program

    NASA Technical Reports Server (NTRS)

    Watson, H. K.

    1971-01-01

    Digital computer program determines tolerance values of end to end signal chain or flow path, given preselected probability value. Technique is useful in the synthesis and analysis phases of subsystem design processes.

  13. Radiation Tolerant Antifuse FPGA

    NASA Technical Reports Server (NTRS)

    Wang, Jih-Jong; Cronquist, Brian; McCollum, John; Parker, Wanida; Katz, Rich; Kleyner, Igor; Day, John H. (Technical Monitor)

    2002-01-01

    The total dose performance of the antifuse FPGA for space applications is summarized. Optimization of the radiation tolerance in the fabless model is the main theme. Mechanisms to explain the variation in different products are discussed.

  14. [INABILITY TO TOLERATE COSMETICS].

    PubMed

    Piérard, G E; Piérard-Franchimont, C

    2016-05-01

    Inability to tolerate cosmetics can result from distinct mechanisms which appear as the so-called sensitive skin corresponding to one aspect of invisible dermatosis, or which corresponds to manifestations of a contact allergic or irritation dermatitis.

  15. Composites Damage Tolerance Workshop

    NASA Technical Reports Server (NTRS)

    Gregg, Wayne

    2006-01-01

    The Composite Damage Tolerance Workshop included participants from NASA, academia, and private industry. The objectives of the workshop were to begin dialogue in order to establish a working group within the Agency, create awareness of damage tolerance requirements for Constellation, and discuss potential composite hardware for the Crew Launch Vehicle (CLV) Upper Stage (US) and Crew Module. It was proposed that a composites damage tolerance working group be created that acts within the framework of the existing NASA Fracture Control Methodology Panel. The working group charter would be to identify damage tolerance gaps and obstacles for implementation of composite structures into manned space flight systems and to develop strategies and recommendations to overcome these obstacles.

  16. How Much Does Risk Tolerance Change?

    PubMed Central

    Sahm, Claudia R.

    2014-01-01

    Stability of preferences is central to how economists study behavior. This paper uses panel data on hypothetical gambles over lifetime income in the Health and Retirement Study to quantify changes in risk tolerance over time and differences across individuals. Maximum-likelihood estimation of a correlated random effects model utilizes information from 12,000 respondents in the 1992–2002 HRS. The results are consistent with constant relative risk aversion and career selection based on preferences. While risk tolerance changes with age and macroeconomic conditions, persistent differences across individuals account for over 70% of the systematic variation. PMID:25544881

  17. Experiments in fault tolerant software reliability

    NASA Technical Reports Server (NTRS)

    Mcallister, David F.; Tai, K. C.; Vouk, Mladen A.

    1987-01-01

    The reliability of voting was evaluated in a fault-tolerant software system for small output spaces. The effectiveness of the back-to-back testing process was investigated. Version 3.0 of the RSDIMU-ATS, a semi-automated test bed for certification testing of RSDIMU software, was prepared and distributed. Software reliability estimation methods based on non-random sampling are being studied. The investigation of existing fault-tolerance models was continued and formulation of new models was initiated.

  18. How Much Does Risk Tolerance Change?

    PubMed

    Sahm, Claudia R

    2012-01-01

    Stability of preferences is central to how economists study behavior. This paper uses panel data on hypothetical gambles over lifetime income in the Health and Retirement Study to quantify changes in risk tolerance over time and differences across individuals. Maximum-likelihood estimation of a correlated random effects model utilizes information from 12,000 respondents in the 1992-2002 HRS. The results are consistent with constant relative risk aversion and career selection based on preferences. While risk tolerance changes with age and macroeconomic conditions, persistent differences across individuals account for over 70% of the systematic variation.

  19. Certification of damage tolerant composite structure

    NASA Technical Reports Server (NTRS)

    Rapoff, Andrew J.; Dill, Harold D.; Sanger, Kenneth B.; Kautz, Edward F.

    1990-01-01

    A reliability based certification testing methodology for impact damage tolerant composite structure was developed. Cocured, adhesively bonded, and impact damaged composite static strength and fatigue life data were statistically analyzed to determine the influence of test parameters on the data scatter. The impact damage resistance and damage tolerance of various structural configurations were characterized through the analysis of an industry wide database of impact test results. Realistic impact damage certification requirements were proposed based on actual fleet aircraft data. The capabilities of available impact damage analysis methods were determined through correlation with experimental data. Probabilistic methods were developed to estimate the reliability of impact damaged composite structures.

  20. 210-Polonium studies in some environmental and biological matrices of Domiasiat uranium deposit area, West Khasi Hills, Meghalaya, India.

    PubMed

    Marbaniang, Deswyn G; Poddar, Raj K; Nongkynrih, Phlis; Khathing, Darlando T

    2010-03-01

    The study was performed using a silicon surface barrier alpha spectrometer at Bhabha Atomic Research Centre, Mumbai, India. Through the study, the observed (210)Po activity in water sample from different locations in the Domiasiat area ranges from 0.04 to 0.69 Bq/l. The daily and annual intake of (210)Po through water was also estimated and the mean value of 0.72 and 263.61 Bq, respectively, were observed. It is observed that the effective doses through water were higher than the World Health Organization recommended dose of 0.05 mSv/year. The total annual effective doses through terrestrial ingestion for all the locations was studied and the mean annual effective dose was observed to be 0.315 mSv, which, when compared to the worldwide and the Indian values, was observed to be slightly higher. The mean activity in soil is found to be 124.8 +/-5.7 Bq/kg and in meat the activity is 0.43 +/-0.05 Bq/kg. In fishes, an activity of 0.48 +/-0.07 Bq/kg in Garra lamta, 0.29 +/-0.02 Bq/kg in Neolissocheilus hexaganolepis, and 3.3 +/-0.1 Bq/kg in Macrobrachium sp. is observed. Activity concentration in plant samples was analyzed and the activity ranges from 0.020 +/-0.002 to 9.69 +/-0.35 Bq/kg. Committed effective dose by the adult population of the Domiasiat area through intake of (210)Po through these food items was also determined and compared with the Indian average value and the worldwide average value.

  1. Fault tolerant linear actuator

    DOEpatents

    Tesar, Delbert

    2004-09-14

    In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.

  2. Damage Tolerance of Composites

    NASA Technical Reports Server (NTRS)

    Hodge, Andy

    2007-01-01

    Fracture control requirements have been developed to address damage tolerance of composites for manned space flight hardware. The requirements provide the framework for critical and noncritical hardware assessment and testing. The need for damage threat assessments, impact damage protection plans, and nondestructive evaluation are also addressed. Hardware intended to be damage tolerant have extensive coupon, sub-element, and full-scale testing requirements in-line with the Building Block Approach concept from the MIL-HDBK-17, Department of Defense Composite Materials Handbook.

  3. Glucose Tolerance and Hyperkinesis.

    ERIC Educational Resources Information Center

    Langseth, Lillian; Dowd, Judith

    Examined were medical records of 265 hyperkinetic children (7-9 years old). Clinical blood chemistries, hematology, and 5-hour glucose tolerance test (GTT) results indicated that hematocrit levels were low in 27% of the Ss, eosinophil levels were abnormally high in 86% of the Ss, and GTT results were abnormal in a maority of Ss. (CL)

  4. Glucose Tolerance and Hyperkinesis.

    ERIC Educational Resources Information Center

    Langseth, Lillian; Dowd, Judith

    Examined were medical records of 265 hyperkinetic children (7-9 years old). Clinical blood chemistries, hematology, and 5-hour glucose tolerance test (GTT) results indicated that hematocrit levels were low in 27% of the Ss, eosinophil levels were abnormally high in 86% of the Ss, and GTT results were abnormal in a maority of Ss. (CL)

  5. Zero Tolerance versus Privacy.

    ERIC Educational Resources Information Center

    Dowling-Sendor, Benjamin

    2000-01-01

    In a case involving questionable canine search-and-seizure practices, a circuit court upheld a school board's decision to terminate a teacher's contract. While touting zero tolerance, the board fired an honored teacher 3 years from retirement who may not have known about the marijuana cigarette in her car. (MLH)

  6. Cuphea tolerates clopyralid

    USDA-ARS?s Scientific Manuscript database

    Cuphea is a new crop of temperate regions that produces seed oil with medium-chain length fatty acids, which can substitute for imported coconut and palm kernels oils. Only four herbicides are known to be tolerated by cuphea to date. More herbicides, especially POST products, are needed for continue...

  7. A little toleration, please

    PubMed Central

    McKnight, C.

    2000-01-01

    Value pluralism does not imply relativism or subjectivism about values. What it does is allow respect for an at least limited toleration of values with which one may profoundly disagree. Thus a doctor can respect the autonomy of a patient whose values he does not share. Key Words: Pluralism • multiculturalism • relativism • subjectivism • patient autonomy PMID:11129842

  8. Teaching Tolerance Magazine, 2003.

    ERIC Educational Resources Information Center

    Carnes, Jim, Ed.

    2003-01-01

    This magazine provides teachers with classroom learning materials to help children learn to be tolerant with others. Articles in the magazine are: "A Standard to Sustain" (Mary M. Harrison); "Let's Just Play" (Janet Schmidt); "Who's Helen Keller?" (Ruth Shagoury Hubbard); "Margins of Error" (Joe Parsons);…

  9. Tolerant (parallel) Programming

    NASA Technical Reports Server (NTRS)

    DiNucci, David C.; Bailey, David H. (Technical Monitor)

    1997-01-01

    In order to be truly portable, a program must be tolerant of a wide range of development and execution environments, and a parallel program is just one which must be tolerant of a very wide range. This paper first defines the term "tolerant programming", then describes many layers of tools to accomplish it. The primary focus is on F-Nets, a formal model for expressing computation as a folded partial-ordering of operations, thereby providing an architecture-independent expression of tolerant parallel algorithms. For implementing F-Nets, Cooperative Data Sharing (CDS) is a subroutine package for implementing communication efficiently in a large number of environments (e.g. shared memory and message passing). Software Cabling (SC), a very-high-level graphical programming language for building large F-Nets, possesses many of the features normally expected from today's computer languages (e.g. data abstraction, array operations). Finally, L2(sup 3) is a CASE tool which facilitates the construction, compilation, execution, and debugging of SC programs.

  10. Oilseed cuphea tolerates bromoxynil

    USDA-ARS?s Scientific Manuscript database

    Weed management is a critical feature of all crop production, but especially for new and alternative crops with which most growers have little experience. Oilseed cuphea is a new annual crop for temperate regions and, at present, it is known to tolerate only a narrow spectrum of herbicides. Addition...

  11. Pesticide tolerance in amphibians: induced tolerance in susceptible populations, constitutive tolerance in tolerant populations.

    PubMed

    Hua, Jessica; Morehouse, Nathan I; Relyea, Rick

    2013-11-01

    The role of plasticity in shaping adaptations is important to understanding the expression of traits within individuals and the evolution of populations. With increasing human impacts on the environment, one challenge is to consider how plasticity shapes responses to anthropogenic stressors such as contaminants. To our knowledge, only one study (using mosquitoes) has considered the possibility of induced insecticide tolerance. Using populations of wood frogs (Lithobates sylvaticus) located close to and far from agricultural fields, we discovered that exposing some populations of embryos and hatchlings to sublethal concentrations of the insecticide carbaryl induced higher tolerance to a subsequent lethal concentration later in life. Interestingly, the inducible populations were located >800 m from agricultural areas and were the most susceptible to the insecticide. In contrast, the noninducible populations were located close to agricultural areas and were the least susceptible. We also found that sublethal concentrations of carbaryl induced higher tadpole AChE concentrations in several cases. This is the first study to demonstrate inducible tolerance in a vertebrate species and the pattern of inducible and constitutive tolerance among populations suggests the process of genetic assimilation.

  12. Zero Tolerance versus Privacy.

    ERIC Educational Resources Information Center

    Dowling-Sendor, Benjamin

    2000-01-01

    In a case involving questionable canine search-and-seizure practices, a circuit court upheld a school board's decision to terminate a teacher's contract. While touting zero tolerance, the board fired an honored teacher 3 years from retirement who may not have known about the marijuana cigarette in her car. (MLH)

  13. Why Tolerate Conscience?

    PubMed

    Boucher, François; Laborde, Cécile

    In Why Tolerate Religion?, Brian Leiter argues against the special legal status of religion, claiming that religion should not be the only ground for exemptions to the law and that this form of protection should be, in principle, available for the claims of secular conscience as well. However, in the last chapter of his book, he objects to a universal regime of exemptions for both religious and secular claims of conscience, highlighting the practical and moral flaws associated with it. We believe that Leiter identifies a genuine and important contemporary legal and philosophical problem. We find much to admire in his reasoning. However, we raise questions about two claims that are crucial for his argument. The first claim is that it is not religion as such, but conscience that deserves toleration and respect. The second claim is that respect for religion and conscience demands 'principled toleration' but does not entail stronger policies of legal exemptions. Against the first claim, we argue that Leiter does not successfully distinguish religious belief from secular conscience and morality; and he does not explain why secular conscience (which shares many of religious conscience's epistemic features) deserves respect. Against the second claim, we argue that the most promising theories of legal exemptions are not classical theories of liberal toleration.

  14. Biocide tolerance in bacteria.

    PubMed

    Ortega Morente, Elena; Fernández-Fuentes, Miguel Angel; Grande Burgos, Maria José; Abriouel, Hikmate; Pérez Pulido, Rubén; Gálvez, Antonio

    2013-03-01

    Biocides have been employed for centuries, so today a wide range of compounds showing different levels of antimicrobial activity have become available. At the present time, understanding the mechanisms of action of biocides has also become an important issue with the emergence of bacterial tolerance to biocides and the suggestion that biocide and antibiotic resistance in bacteria might be linked. While most of the mechanisms providing antibiotic resistance are agent specific, providing resistance to a single antimicrobial or class of antimicrobial, there are currently numerous examples of efflux systems that accommodate and, thus, provide tolerance to a broad range of structurally unrelated antimicrobials, both antibiotics and biocides. If biocide tolerance becomes increasingly common and it is linked to antibiotic resistance, not only resistant (even multi-resistant) bacteria could be passed along the food chain, but also there are resistance determinants that can spread and lead to the emergence of new resistant microorganisms, which can only be detected and monitored when the building blocks of resistance traits are understood on the molecular level. This review summarizes the main advances reached in understanding the mechanism of action of biocides, the mechanisms of bacterial resistance to both biocides and antibiotics, and the incidence of biocide tolerance in bacteria of concern to human health and the food industry.

  15. Fault tolerant magnetic bearings

    SciTech Connect

    Maslen, E.H.; Sortore, C.K.; Gillies, G.T.; Williams, R.D.; Fedigan, S.J.; Aimone, R.J.

    1999-07-01

    A fault tolerant magnetic bearing system was developed and demonstrated on a large flexible-rotor test rig. The bearing system comprises a high speed, fault tolerant digital controller, three high capacity radial magnetic bearings, one thrust bearing, conventional variable reluctance position sensors, and an array of commercial switching amplifiers. Controller fault tolerance is achieved through a very high speed voting mechanism which implements triple modular redundancy with a powered spare CPU, thereby permitting failure of up to three CPU modules without system failure. Amplifier/cabling/coil fault tolerance is achieved by using a separate power amplifier for each bearing coil and permitting amplifier reconfiguration by the controller upon detection of faults. This allows hot replacement of failed amplifiers without any system degradation and without providing any excess amplifier kVA capacity over the nominal system requirement. Implemented on a large (2440 mm in length) flexible rotor, the system shows excellent rejection of faults including the failure of three CPUs as well as failure of two adjacent amplifiers (or cabling) controlling an entire stator quadrant.

  16. Tolerance through Exposure.

    ERIC Educational Resources Information Center

    Russo, Carolyn

    In this project, eighth grade students are exposed to black history, literature, music, and art to enhance the understanding of diversity and to establish an atmosphere of tolerance for diversity. Students are asked to choose a personality or significant historical event to research and present to the class. They focus on issues such as prejudice,…

  17. Ethanol tolerance in yeasts.

    PubMed

    Casey, G P; Ingledew, W M

    1986-01-01

    It is now certain that the inherent ethanol tolerance of the Saccharomyces strain used is not the prime factor regulating the level of ethanol that can be produced in a high sugar brewing, wine, sake, or distillery fermentation. In fact, in terms of the maximum concentration that these yeasts can produce under batch (16 to 17% [v/v]) or fed-batch conditions, there is clearly no difference in ethanol tolerance. This is not to say, however, that under defined conditions there is no difference in ethanol tolerance among different Saccharomyces yeasts. This property, although a genetic determinant, is clearly influenced by many factors (carbohydrate level, wort nutrition, temperature, osmotic pressure/water activity, and substrate concentration), and each yeast strain reacts to each factor differently. This will indeed lead to differences in measured tolerance. Thus, it is extremely important that each of these be taken into consideration when determining "tolerance" for a particular set of fermentation conditions. The manner in which each alcohol-related industry has evolved is now known to have played a major role in determining traditional thinking on ethanol tolerance in Saccharomyces yeasts. It is interesting to speculate on how different our thinking on ethanol tolerance would be today if sake fermentations had not evolved with successive mashing and simultaneous saccharification and fermentation of rice carbohydrate, if distillers' worts were clarified prior to fermentation but brewers' wort were not, and if grape skins with their associated unsaturated lipids had not been an integral part of red wine musts. The time is now ripe for ethanol-related industries to take advantage of these findings to improve the economies of production. In the authors' opinion, breweries could produce higher alcohol beers if oxygenation (leading to unsaturated lipids) and "usable" nitrogen source levels were increased in high gravity worts. White wine fermentations could also, if

  18. Deconstructing tolerance with clobazam

    PubMed Central

    Wechsler, Robert T.; Sankar, Raman; Montouris, Georgia D.; White, H. Steve; Cloyd, James C.; Kane, Mary Clare; Peng, Guangbin; Tworek, David M.; Shen, Vivienne; Isojarvi, Jouko

    2016-01-01

    Objective: To evaluate potential development of tolerance to adjunctive clobazam in patients with Lennox-Gastaut syndrome. Methods: Eligible patients enrolled in open-label extension study OV-1004, which continued until clobazam was commercially available in the United States or for a maximum of 2 years outside the United States. Enrolled patients started at 0.5 mg·kg−1·d−1 clobazam, not to exceed 40 mg/d. After 48 hours, dosages could be adjusted up to 2.0 mg·kg−1·d−1 (maximum 80 mg/d) on the basis of efficacy and tolerability. Post hoc analyses evaluated mean dosages and drop-seizure rates for the first 2 years of the open-label extension based on responder categories and baseline seizure quartiles in OV-1012. Individual patient listings were reviewed for dosage increases ≥40% and increasing seizure rates. Results: Data from 200 patients were included. For patients free of drop seizures, there was no notable change in dosage over 24 months. For responder groups still exhibiting drop seizures, dosages were increased. Weekly drop-seizure rates for 100% and ≥75% responders demonstrated a consistent response over time. Few patients had a dosage increase ≥40% associated with an increase in seizure rates. Conclusions: Two-year findings suggest that the majority of patients do not develop tolerance to the antiseizure actions of clobazam. Observed dosage increases may reflect best efforts to achieve seizure freedom. It is possible that the clinical development of tolerance to clobazam has been overstated. ClinicalTrials.gov identifier: NCT00518713 and NCT01160770. Classification of evidence: This study provides Class III evidence that the majority of patients do not develop tolerance to clobazam over 2 years of treatment. PMID:27683846

  19. Comparative Investigation of Copper Tolerance and Identification of Putative Tolerance Related Genes in Tardigrades.

    PubMed

    Hygum, Thomas L; Fobian, Dannie; Kamilari, Maria; Jørgensen, Aslak; Schiøtt, Morten; Grosell, Martin; Møbjerg, Nadja

    2017-01-01

    Tardigrades are microscopic aquatic animals renowned for their tolerance toward extreme environmental conditions. The current study is the first to investigate their tolerance toward heavy metals and we present a novel tardigrade toxicant tolerance assay based on activity assessments as a measure of survival. Specifically, we compare tolerance toward copper in four species representing different evolutionary lineages, habitats and adaptation strategies, i.e., a marine heterotardigrade, Echiniscoides sigismundi, a limno-terrestrial heterotardigrade, Echiniscus testudo, a limno-terrestrial eutardigrade, Ramazzottius oberhaeuseri, and a marine eutardigrade, Halobiotus crispae. The latter was sampled at a time of year, when the population is predominantly represented by aberrant P1 cysts, while the other species were in normal active states prior to exposure. Based on volume measurements and a general relation between body mass and copper tolerance, expected tardigrade EC50 values were estimated at 0.5-2 μg l(-1). Following 24 h of exposure, tolerance was high with no apparent link to lineage or habitat. EC50s (95% CI), 24 h after exposure, were estimated at 178 (168-186) and 310 (295-328) μg l(-1), respectively, for E. sigismundi and R. oberhaeuseri, whereas E. testudo and H. crispae were less affected. Highest tolerance was observed in H. crispae with a mean ± s.e.m. activity of 77 ± 2% (n = 3) 24 h after removal from ~3 mg l(-1) copper, suggesting that tardigrade cysts have increased tolerance toward toxicants. In order to identify putative tolerance related genes, an E. sigismundi transcriptome was searched for key enzymes involved in osmoregulation, antioxidant defense and copper metabolism. We found high expression of Na/K ATPase and carbonic anhydrase, known targets for copper. Our transcriptome, furthermore, revealed high expression of antioxidant enzymes, copper transporters, ATOX1, and a Cu-ATPase. In summary, our results indicate that tardigrades express

  20. Comparative Investigation of Copper Tolerance and Identification of Putative Tolerance Related Genes in Tardigrades

    PubMed Central

    Hygum, Thomas L.; Fobian, Dannie; Kamilari, Maria; Jørgensen, Aslak; Schiøtt, Morten; Grosell, Martin; Møbjerg, Nadja

    2017-01-01

    Tardigrades are microscopic aquatic animals renowned for their tolerance toward extreme environmental conditions. The current study is the first to investigate their tolerance toward heavy metals and we present a novel tardigrade toxicant tolerance assay based on activity assessments as a measure of survival. Specifically, we compare tolerance toward copper in four species representing different evolutionary lineages, habitats and adaptation strategies, i.e., a marine heterotardigrade, Echiniscoides sigismundi, a limno-terrestrial heterotardigrade, Echiniscus testudo, a limno-terrestrial eutardigrade, Ramazzottius oberhaeuseri, and a marine eutardigrade, Halobiotus crispae. The latter was sampled at a time of year, when the population is predominantly represented by aberrant P1 cysts, while the other species were in normal active states prior to exposure. Based on volume measurements and a general relation between body mass and copper tolerance, expected tardigrade EC50 values were estimated at 0.5–2 μg l−1. Following 24 h of exposure, tolerance was high with no apparent link to lineage or habitat. EC50s (95% CI), 24 h after exposure, were estimated at 178 (168–186) and 310 (295–328) μg l−1, respectively, for E. sigismundi and R. oberhaeuseri, whereas E. testudo and H. crispae were less affected. Highest tolerance was observed in H. crispae with a mean ± s.e.m. activity of 77 ± 2% (n = 3) 24 h after removal from ~3 mg l−1 copper, suggesting that tardigrade cysts have increased tolerance toward toxicants. In order to identify putative tolerance related genes, an E. sigismundi transcriptome was searched for key enzymes involved in osmoregulation, antioxidant defense and copper metabolism. We found high expression of Na/K ATPase and carbonic anhydrase, known targets for copper. Our transcriptome, furthermore, revealed high expression of antioxidant enzymes, copper transporters, ATOX1, and a Cu-ATPase. In summary, our results indicate that tardigrades

  1. Validated Fault Tolerant Architectures for Space Station

    NASA Technical Reports Server (NTRS)

    Lala, Jaynarayan H.

    1990-01-01

    Viewgraphs on validated fault tolerant architectures for space station are presented. Topics covered include: fault tolerance approach; advanced information processing system (AIPS); and fault tolerant parallel processor (FTPP).

  2. Zero Tolerance Policies. Research Brief

    ERIC Educational Resources Information Center

    Muir, Mike

    2004-01-01

    Much of this brief comes from the ERIC Digest on Zero Tolerance Policies (ERIC #: ED451579). State legislatures and school boards are adopting a growing number of zero-tolerance polices toward weapons, guns, and violence. Zero-tolerance polices are rules intended to address specific school-safety issues. Despite the controversies that it has…

  3. Implementing fault-tolerant sensors

    NASA Technical Reports Server (NTRS)

    Marzullo, Keith

    1989-01-01

    One aspect of fault tolerance in process control programs is the ability to tolerate sensor failure. A methodology is presented for transforming a process control program that cannot tolerate sensor failures to one that can. Additionally, a hierarchy of failure models is identified.

  4. Full Tolerant Archiving System

    NASA Astrophysics Data System (ADS)

    Knapic, C.; Molinaro, M.; Smareglia, R.

    2013-10-01

    The archiving system at the Italian center for Astronomical Archives (IA2) manages data from external sources like telescopes, observatories, or surveys and handles them in order to guarantee preservation, dissemination, and reliability, in most cases in a Virtual Observatory (VO) compliant manner. A metadata model dynamic constructor and a data archive manager are new concepts aimed at automatizing the management of different astronomical data sources in a fault tolerant environment. The goal is a full tolerant archiving system, nevertheless complicated by the presence of various and time changing data models, file formats (FITS, HDF5, ROOT, PDS, etc.) and metadata content, even inside the same project. To avoid this unpleasant scenario a novel approach is proposed in order to guarantee data ingestion, backward compatibility, and information preservation.

  5. Damage Tolerance Assessment Branch

    NASA Technical Reports Server (NTRS)

    Walker, James L.

    2013-01-01

    The Damage Tolerance Assessment Branch evaluates the ability of a structure to perform reliably throughout its service life in the presence of a defect, crack, or other form of damage. Such assessment is fundamental to the use of structural materials and requires an integral blend of materials engineering, fracture testing and analysis, and nondestructive evaluation. The vision of the Branch is to increase the safety of manned space flight by improving the fracture control and the associated nondestructive evaluation processes through development and application of standards, guidelines, advanced test and analytical methods. The Branch also strives to assist and solve non-aerospace related NDE and damage tolerance problems, providing consultation, prototyping and inspection services.

  6. Abuse Tolerance Improvements

    SciTech Connect

    Orendorff, Christopher J.; Nagasubramanian, Ganesan; Fenton, Kyle R.; Allcorn, Eric

    2015-10-01

    As lithium-ion battery technologies mature, the size and energy of these systems continues to increase (> 50 kWh for EVs); making safety and reliability of these high energy systems increasingly important. While most material advances for lithium-ion chemistries are directed toward improving cell performance (capacity, energy, cycle life, etc.), there are a variety of materials advancements that can be made to improve lithium-ion battery safety. Issues including energetic thermal runaway, electrolyte decomposition and flammability, anode SEI stability, and cell-level abuse tolerance continue to be critical safety concerns. This report highlights work with our collaborators to develop advanced materials to improve lithium-ion battery safety and abuse tolerance and to perform cell-level characterization of new materials.

  7. Fault Tolerant Paradigms

    DTIC Science & Technology

    2016-02-26

    AFRL-AFOSR-VA-TR-2016-0105 BRI) Fault Tolerant Paradigms BENJAMIN ONG MICHIGAN STATE UNIV EAST LANSING Final Report 02/26/2016 DISTRIBUTION A...property allows the algorithm to outperform FFTW over a wide range of sparsity and noise values, and is to the best of our knowledge novel in the...best of our knowledge novel. The new algorithm gives excellent performance in the noisy setting without significantly increasing the computational

  8. Ethanol tolerance in bacteria.

    PubMed

    Ingram, L O

    1990-01-01

    The adverse effects of ethanol on bacterial growth, viability, and metabolism are caused primarily by ethanol-induced leakage of the plasma membrane. This increase in membrane leakage is consistent with known biophysical properties of membranes and ethanolic solutions. The primary actions of ethanol result from colligative effects of the high molar concentrations rather than from specific interactions with receptors. The ethanol tolerance of growth in different microorganisms appears to result in large part from adaptive and evolutionary changes in cell membrane composition. Different cellular activities vary in their tolerance to ethanol. Therefore, it is essential that the aspect of cellular function under study be specifically defined and that comparisons of ethanol tolerance among systems share this common definition. Growth is typically one of the most sensitive cellular activities to inhibition by ethanol, followed by survival, or loss of reproductive ability. Glycolysis is the most resistant of these three activities. Since glycolysis is an exergonic process, a cell need not be able to grow or remain viable for glycolysis to occur.

  9. Drought Tolerance in Wheat

    PubMed Central

    Prodhan, Zakaria Hossain; Faruq, Golam

    2013-01-01

    Drought is one of the most important phenomena which limit crops' production and yield. Crops demonstrate various morphological, physiological, biochemical, and molecular responses to tackle drought stress. Plants' vegetative and reproductive stages are intensively influenced by drought stress. Drought tolerance is a complicated trait which is controlled by polygenes and their expressions are influenced by various environmental elements. This means that breeding for this trait is so difficult and new molecular methods such as molecular markers, quantitative trait loci (QTL) mapping strategies, and expression patterns of genes should be applied to produce drought tolerant genotypes. In wheat, there are several genes which are responsible for drought stress tolerance and produce different types of enzymes and proteins for instance, late embryogenesis abundant (lea), responsive to abscisic acid (Rab), rubisco, helicase, proline, glutathione-S-transferase (GST), and carbohydrates during drought stress. This review paper has concentrated on the study of water limitation and its effects on morphological, physiological, biochemical, and molecular responses of wheat with the possible losses caused by drought stress. PMID:24319376

  10. Biocular image misalignment tolerance

    NASA Astrophysics Data System (ADS)

    Kalich, Melvyn E.; Rash, Clarence E.; van de Pol, Corina; Rowe, Terri L.; Lont, Lisa M.; Peterson, R. David

    2003-09-01

    Biocular helmet-mounted display (HMD) design flexibility and cost are directly related to image misalignment tolerance standards. Currently recommended tolerance levels are based on highly variable data from a number of studies. This paper presents progress of an ongoing study to evaluate optometric measures sensitive to misalignment in partial-overlap biocular optical systems like that proposed for the Comanche RAH-66 helicopter helmet integrated display sighting system (HIDSS). Horizontal divergent and relative vertical misalignments (offsets) of see-through biocular symbology viewed against a simulated daytime background were chosen for this study. Misalignments within and just beyond current tolerance recommendations were evaluated using pre, pre and post, and during measures of visual performance. Data were obtained from seven experimental and four control subjects. The diplopia responses from experimental and control subjects were essentially the same. However, accommodative facility showed a rate decrement following exposure to both types of misalignment. Horizontal heterophorias showed definite post-misalignment increases. Subject responses to questionnaires universally indicated increased adaptation to (ease with) visual tasks over the testing period.

  11. Fault tolerant control laws

    NASA Technical Reports Server (NTRS)

    Ly, U. L.; Ho, J. K.

    1986-01-01

    A systematic procedure for the synthesis of fault tolerant control laws to actuator failure has been presented. Two design methods were used to synthesize fault tolerant controllers: the conventional LQ design method and a direct feedback controller design method SANDY. The latter method is used primarily to streamline the full-state Q feedback design into a practical implementable output feedback controller structure. To achieve robustness to control actuator failure, the redundant surfaces are properly balanced according to their control effectiveness. A simple gain schedule based on the landing gear up/down logic involving only three gains was developed to handle three design flight conditions: Mach .25 and Mach .60 at 5000 ft and Mach .90 at 20,000 ft. The fault tolerant control law developed in this study provides good stability augmentation and performance for the relaxed static stability aircraft. The augmented aircraft responses are found to be invariant to the presence of a failure. Furthermore, single-loop stability margins of +6 dB in gain and +30 deg in phase were achieved along with -40 dB/decade rolloff at high frequency.

  12. A consideration of resistance and tolerance for ruminant nematode infections

    PubMed Central

    Bishop, Stephen C.

    2012-01-01

    Debates on the relative merits of resistance (the ability of the host to control the parasite lifecycle) and tolerance (the net impact of infection on host performance) are often lively and unhindered by data or evidence. Resistance generally shows continuous, heritable variation but data are sparser for tolerance, the utility of which will depend upon the disease prevalence. Prevalence is a function of group mean resistance and infection pressure, which itself is influenced by mean resistance. Tolerance will have most value for endemic diseases with a high prevalence but will be of little value for low prevalence diseases. The conditionality of tolerance on infection status, and hence resistance, makes it difficult to estimate independently of resistance. Tolerance is potentially tractable for nematode infections, as the prevalence of infection is ca. 100% in animals grazing infected pasture, and infection level can be quantified by faecal egg count (FEC). Whilst individual animal phenotypes for tolerance are difficult to estimate, breeding values are estimable if related animals graze pastures of different contamination levels. Selection for resistance, i.e., FEC, provides both direct and indirect benefits from ever decreased pasture contamination and hence decreased infectious challenge. Modeling and experimental studies have shown that such reductions in pasture contamination may lead to substantially increased performance. It is proposed that selection goals addressing nematode infections should include both resistance and performance under challenging conditions. However, there may be benefits from exploiting large datasets in which sires are used across cohorts differing in infection level, to further explore tolerance. This may help to customise breeding objectives, with tolerance given greater weight in heavily parasitized environments. PMID:23248638

  13. Desiccation tolerance of prokaryotes.

    PubMed Central

    Potts, M

    1994-01-01

    The removal of cell-bound water through air drying and the addition of water to air-dried cells are forces that have played a pivotal role in the evolution of the prokaryotes. In bacterial cells that have been subjected to air drying, the evaporation of free cytoplasmic water (Vf) can be instantaneous, and an equilibrium between cell-bound water (Vb) and the environmental water (vapor) potential (psi wv) may be achieved rapidly. In the air-dried state some bacteria survive only for seconds whereas others can tolerate desiccation for thousands, perhaps millions, of years. The desiccated (anhydrobiotic) cell is characterized by its singular lack of water--with contents as low as 0.02 g of H2O g (dry weight)-1. At these levels the monolayer coverage by water of macromolecules, including DNA and proteins, is disturbed. As a consequence the mechanisms that confer desiccation tolerance upon air-dried bacteria are markedly different from those, such as the mechanism of preferential exclusion of compatible solutes, that preserve the integrity of salt-, osmotically, and freeze-thaw-stressed cells. Desiccation tolerance reflects a complex array of interactions at the structural, physiological, and molecular levels. Many of the mechanisms remain cryptic, but it is clear that they involve interactions, such as those between proteins and co-solvents, that derive from the unique properties of the water molecule. A water replacement hypothesis accounts for how the nonreducing disaccharides trehalose and sucrose preserve the integrity of membranes and proteins. Nevertheless, we have virtually no insight into the state of the cytoplasm of an air-dried cell. There is no evidence for any obvious adaptations of proteins that can counter the effects of air drying or for the occurrence of any proteins that provide a direct and a tangible contribution to cell stability. Among the prokaryotes that can exist as anhydrobiotic cells, the cyanobacteria have a marked capacity to do so. One

  14. Desiccation tolerance of prokaryotes.

    PubMed

    Potts, M

    1994-12-01

    The removal of cell-bound water through air drying and the addition of water to air-dried cells are forces that have played a pivotal role in the evolution of the prokaryotes. In bacterial cells that have been subjected to air drying, the evaporation of free cytoplasmic water (Vf) can be instantaneous, and an equilibrium between cell-bound water (Vb) and the environmental water (vapor) potential (psi wv) may be achieved rapidly. In the air-dried state some bacteria survive only for seconds whereas others can tolerate desiccation for thousands, perhaps millions, of years. The desiccated (anhydrobiotic) cell is characterized by its singular lack of water--with contents as low as 0.02 g of H2O g (dry weight)-1. At these levels the monolayer coverage by water of macromolecules, including DNA and proteins, is disturbed. As a consequence the mechanisms that confer desiccation tolerance upon air-dried bacteria are markedly different from those, such as the mechanism of preferential exclusion of compatible solutes, that preserve the integrity of salt-, osmotically, and freeze-thaw-stressed cells. Desiccation tolerance reflects a complex array of interactions at the structural, physiological, and molecular levels. Many of the mechanisms remain cryptic, but it is clear that they involve interactions, such as those between proteins and co-solvents, that derive from the unique properties of the water molecule. A water replacement hypothesis accounts for how the nonreducing disaccharides trehalose and sucrose preserve the integrity of membranes and proteins. Nevertheless, we have virtually no insight into the state of the cytoplasm of an air-dried cell. There is no evidence for any obvious adaptations of proteins that can counter the effects of air drying or for the occurrence of any proteins that provide a direct and a tangible contribution to cell stability. Among the prokaryotes that can exist as anhydrobiotic cells, the cyanobacteria have a marked capacity to do so. One

  15. Gluten tolerance; potential challenges in treatment strategies.

    PubMed

    Bold, Justine; Rostami, Kamran

    2011-01-01

    Tolerable gluten thresholds in gluten free products have long been debated together with issues of cross contamination of gluten free cereals during the milling process. It is well established that a totally gluten free diet is virtually impossible owing to the presence of traces of gluten. It is estimated that daily consumption of gluten from contaminated gluten free foods is in the range of 5 to 50 mg. We believe evidence is mounting that it may be possible for some coeliac patients to tolerate gluten above the limits considered permissible at threshold levels. Conversely, it seems there is evidence that some patients might have a much lower threshold for gluten. Whatever would be the individual threshold, GFD may be of benefit to any symptomatic patients even those with milder enteropathy like microscopic enteritis.

  16. Performance Analysis on Fault Tolerant Control System

    NASA Technical Reports Server (NTRS)

    Shin, Jong-Yeob; Belcastro, Christine

    2005-01-01

    In a fault tolerant control (FTC) system, a parameter varying FTC law is reconfigured based on fault parameters estimated by fault detection and isolation (FDI) modules. FDI modules require some time to detect fault occurrences in aero-vehicle dynamics. In this paper, an FTC analysis framework is provided to calculate the upper bound of an induced-L(sub 2) norm of an FTC system with existence of false identification and detection time delay. The upper bound is written as a function of a fault detection time and exponential decay rates and has been used to determine which FTC law produces less performance degradation (tracking error) due to false identification. The analysis framework is applied for an FTC system of a HiMAT (Highly Maneuverable Aircraft Technology) vehicle. Index Terms fault tolerant control system, linear parameter varying system, HiMAT vehicle.

  17. Do copper tolerant fathead minnows produce copper tolerant adult offspring?

    PubMed Central

    Kolok, Alan S.; L’Etoile-Lopes, Darcy

    2009-01-01

    The objective of this study was to determine if the relative Cu tolerance of fathead minnow parents determines the, relative Cu tolerance of their adult offspring. It was hypothesized that the adult offspring of Cu-tolerant minnows would inherit Cu tolerance from their parents. The relative Cu tolerance of 96 adult fish was determined based upon their reduction in swim performance following a sublethal exposure to 150 μg Cu/l. Control, Cu-tolerant and Cu-susceptible lines of fish were produced and fish within each line were allowed to breed. The offspring were raised to adults, then exposed to one of two sublethal Cu concentrations (150 or 225 (μg Cu/l) for 8 days. There were no significant differences in relative Cu tolerance, as measured by reduction in swim performance, among the three lines of fish at either dose. However, significant differences in whole body Na+ occurred among the fish lines after exposure to 150 μg Cu/l, but not after exposure to 225 μg Cu/l. Significant differences in whole body Cu occurred between Cu-tolerant and Cu-susceptible fish lines after exposure to either Cu dose. The offspring did not inherit the relative Cu tolerance of their parents, however, the selection lines had diverged from each other, particularly with respect to their whole body Cu concentrations after exposure. PMID:15820103

  18. Fault tolerant navigation in a Microwave Landing System environment

    NASA Technical Reports Server (NTRS)

    Caglayan, A. K.; Lancraft, R. E.

    1982-01-01

    This paper describes the failure detection and isolation performance of a sensor fault tolerant system for the NASA Terminal Configured Vehicle (TCV) research aircraft in a Microwave Landing System (MLS) environment. The objective of the fault tolerant system is to detect failures in navigation-aid instruments and on-board sensors and to provide reliable estimates for the aircraft states in the possible presence of these sensor malfunctions. Analytic redundancy, which exists between the various sensor outputs due to the aircraft point mass equations of motion, is used to identify sensor failures. State estimates are used by an automatic guidance and control system to land the aircraft along a prescribed path.

  19. Efficacy and tolerance

    PubMed Central

    Goetzke, Edda; Findeisen, P.; Welbers, Inés B.

    1983-01-01

    1 Efficacy of and tolerance to 0.25 mg brotizolam and 2.0 mg flunitrazepam were compared over a period of 6 days in ambulatory patients complaining of sleep disturbance. The study was double-blind and randomised with a parallel group design. 2 Both drugs improved sleep. More patients assessed sleep latency as shorter during the first night of ingestion with flunitrazepam than with brotizolam, but assessments were comparable over the next 5 days. The number of patients who considered that the frequency of nocturnal awakenings was less did not differ significantly between drugs. 3 Tolerance to brotizolam (0.25 mg) was assessed more favourably than with flunitrazepam (2.0 mg). 4 The study suggests that brotizolam (0.25 mg) is indicated for patients who have difficulty in falling asleep and staying asleep, and who must preserve their alertness during the early part of the next day. Flunitrazepam (2.0 mg) is equally effective, but at this dose there is a higher incidence of adverse effects. PMID:6362698

  20. SFT: Scalable Fault Tolerance

    SciTech Connect

    Petrini, Fabrizio; Nieplocha, Jarek; Tipparaju, Vinod

    2006-04-15

    In this paper we will present a new technology that we are currently developing within the SFT: Scalable Fault Tolerance FastOS project which seeks to implement fault tolerance at the operating system level. Major design goals include dynamic reallocation of resources to allow continuing execution in the presence of hardware failures, very high scalability, high efficiency (low overhead), and transparency—requiring no changes to user applications. Our technology is based on a global coordination mechanism, that enforces transparent recovery lines in the system, and TICK, a lightweight, incremental checkpointing software architecture implemented as a Linux kernel module. TICK is completely user-transparent and does not require any changes to user code or system libraries; it is highly responsive: an interrupt, such as a timer interrupt, can trigger a checkpoint in as little as 2.5μs; and it supports incremental and full checkpoints with minimal overhead—less than 6% with full checkpointing to disk performed as frequently as once per minute.

  1. Intelligent failure-tolerant control

    NASA Technical Reports Server (NTRS)

    Stengel, Robert F.

    1991-01-01

    An overview of failure-tolerant control is presented, beginning with robust control, progressing through parallel and analytical redundancy, and ending with rule-based systems and artificial neural networks. By design or implementation, failure-tolerant control systems are 'intelligent' systems. All failure-tolerant systems require some degrees of robustness to protect against catastrophic failure; failure tolerance often can be improved by adaptivity in decision-making and control, as well as by redundancy in measurement and actuation. Reliability, maintainability, and survivability can be enhanced by failure tolerance, although each objective poses different goals for control system design. Artificial intelligence concepts are helpful for integrating and codifying failure-tolerant control systems, not as alternatives but as adjuncts to conventional design methods.

  2. Physical fault tolerance of nanoelectronics.

    PubMed

    Szkopek, Thomas; Roychowdhury, Vwani P; Antoniadis, Dimitri A; Damoulakis, John N

    2011-04-29

    The error rate in complementary transistor circuits is suppressed exponentially in electron number, arising from an intrinsic physical implementation of fault-tolerant error correction. Contrariwise, explicit assembly of gates into the most efficient known fault-tolerant architecture is characterized by a subexponential suppression of error rate with electron number, and incurs significant overhead in wiring and complexity. We conclude that it is more efficient to prevent logical errors with physical fault tolerance than to correct logical errors with fault-tolerant architecture.

  3. The Dilemma of Zero Tolerance.

    ERIC Educational Resources Information Center

    Holloway, John H.

    2002-01-01

    Reviews research on the impact of zero-tolerance policies on student behavior and achievement. Concludes that policies are generally ineffective and often counterproductive. (Contains 14 references.) (PKP)

  4. Selection indices to identify drought-tolerant grain sorghum cultivars.

    PubMed

    Menezes, C B; Ticona-Benavente, C A; Tardin, F D; Cardoso, M J; Bastos, E A; Nogueira, D W; Portugal, A F; Santos, C V; Schaffert, R E

    2014-11-27

    Twenty-five cultivars of grain sorghum [Sorghum bicolor (L.) Moench] were examined under both drought stress and normal conditions in 4 experiments. In each condition, genotypes were evaluated in a factorial experiment using a randomized complete block design with 3 replications. Eight drought tolerance indices including stability tolerance index, mean productivity (MP), geometric MP, harmonic mean, stress susceptibility index, tolerance index, yield index, and yield stability index were estimated for each genotype based on grain yield under drought (Ys) and irrigated conditions (Yp). The results indicated that there were positive and significant correlations among Yp and Ys with geometric MP, MP, harmonic mean, and stability tolerance index, indicating that these factors are better predictors of Yp and Ys than tolerance index, stress susceptibility index, yield stability index, and yield index. Based on adjusted means at Yp and Ys, indices geometric MP, MP, harmonic mean, and stability tolerance index, unweighted pair group method with arithmetic mean cluster and biplot analysis, the most tolerant cultivars were '9929020', '9929034', and 'N 95B'.

  5. Fault tolerant architectures for integrated aircraft electronics systems, task 2

    NASA Technical Reports Server (NTRS)

    Levitt, K. N.; Melliar-Smith, P. M.; Schwartz, R. L.

    1984-01-01

    The architectural basis for an advanced fault tolerant on-board computer to succeed the current generation of fault tolerant computers is examined. The network error tolerant system architecture is studied with particular attention to intercluster configurations and communication protocols, and to refined reliability estimates. The diagnosis of faults, so that appropriate choices for reconfiguration can be made is discussed. The analysis relates particularly to the recognition of transient faults in a system with tasks at many levels of priority. The demand driven data-flow architecture, which appears to have possible application in fault tolerant systems is described and work investigating the feasibility of automatic generation of aircraft flight control programs from abstract specifications is reported.

  6. Method of Discriminant Gravity Tolerance using Heart Rate Variability

    NASA Astrophysics Data System (ADS)

    Yoshida, Yutaka; Yokoyama, Kiyoko; Takada, Hiroki; Iwase, Satoshi

    When returning on the earth by the space flight, the space deconditioning may be developed. As this countermeasure, the artificial gravity load device using the centrifuge is proposed in the space station. But the gravity load might cause the faint, and safe gravity load is uncertainty. We proposed that discriminate strength of gravity tolerance using heart rate variability time series. Step function was inputted to AR model estimated from heart rate variability time series during rest or under light gravity load, and strength of the gravity tolerance was discriminated by the step response function. On the result, discriminant accuracy was 87.5% by using heart rate variability time series when gravity load of 1.0 G was added to the human lying on the supine. Therefore, possibility of discriminant of gravity tolerance was obtained by using heart rate variability time series when sympathetic hyperactivity. Discriminant of the gravity tolerance is expected before countermeasure of space deconditioning is executed.

  7. Cost-effectiveness of lowering the aflatoxin tolerance level.

    PubMed

    Dichter, C R; Weinstein, M C

    1984-06-01

    The cost-effectiveness of adopting aflatoxin tolerance levels of 15, 10 and 5 ppb for peanuts and peanut products was assessed. Estimates of the annual cost to manufacturers of monitoring and controlling peanut aflatoxin levels at the current 20-ppb action level, and estimates of the projected increase in costs of establishing lower tolerances were elicited from producers by questionnaire. Exposures to peanut products were derived from the HANES I survey and from peanut production statistics. The risk of liver cancer at each tolerance level was estimated using both epidemiological and extrapolated experimental data assuming that exposure would be reduced in direct proportion to the decrease in the tolerance. It was found that the 15-ppb tolerance would cost $60,000 per cancer death averted (range $20,000-$1,700,000) and is therefore relatively cost-effective. The marginal costs per life saved for both the 10-ppb and 5-ppb levels were found to be $1.7 million (range $0.6 million-$11.4 million) and $1.6 million (range +0.6 million-$31.1 million), respectively. Conclusions on the optimal regulatory approach should be guided by comparisons of these figures with corresponding cost-effectiveness ratios for alternative regulatory uses of national resources in the interests of public health.

  8. [Radiation Tolerant Electronics

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Research work in the providing radiation tolerant electronics to NASA and the commercial sector is reported herein. There are four major sections to this report: (1) Special purpose VLSI technology section discusses the status of the VLSI projects as well as the new background technologies that have been developed; (2) Lossless data compression results provide the background and direction of new data compression pursued under this grant; (3) Commercial technology transfer presents an itemization of the commercial technology transfer; and (4) Delivery of VLSI to the Government is a solution and progress report that shows how the Government and Government contractors are gaining access to the technology that has been developed by the MRC.

  9. Fault Tolerant Cache Schemes

    NASA Astrophysics Data System (ADS)

    Tu, H.-Yu.; Tasneem, Sarah

    Most of modern microprocessors employ on—chip cache memories to meet the memory bandwidth demand. These caches are now occupying a greater real es tate of chip area. Also, continuous down scaling of transistors increases the possi bility of defects in the cache area which already starts to occupies more than 50% of chip area. For this reason, various techniques have been proposed to tolerate defects in cache blocks. These techniques can be classified into three different cat egories, namely, cache line disabling, replacement with spare block, and decoder reconfiguration without spare blocks. This chapter examines each of those fault tol erant techniques with a fixed typical size and organization of L1 cache, through extended simulation using SPEC2000 benchmark on individual techniques. The de sign and characteristics of each technique are summarized with a view to evaluate the scheme. We then present our simulation results and comparative study of the three different methods.

  10. Fault Tolerant State Machines

    NASA Technical Reports Server (NTRS)

    Burke, Gary R.; Taft, Stephanie

    2004-01-01

    State machines are commonly used to control sequential logic in FPGAs and ASKS. An errant state machine can cause considerable damage to the device it is controlling. For example in space applications, the FPGA might be controlling Pyros, which when fired at the wrong time will cause a mission failure. Even a well designed state machine can be subject to random errors us a result of SEUs from the radiation environment in space. There are various ways to encode the states of a state machine, and the type of encoding makes a large difference in the susceptibility of the state machine to radiation. In this paper we compare 4 methods of state machine encoding and find which method gives the best fault tolerance, as well as determining the resources needed for each method.

  11. The DESCARTES-Nantes survey of kidney transplant recipients displaying clinical operational tolerance identifies 35 new tolerant patients and 34 almost tolerant patients.

    PubMed

    Massart, Annick; Pallier, Annaïck; Pascual, Julio; Viklicky, Ondrej; Budde, Klemens; Spasovski, Goce; Klinger, Marian; Sever, Mehmet Sukru; Sørensen, Søren Schwartz; Hadaya, Karine; Oberbauer, Rainer; Dudley, Christopher; De Fijter, Johan W; Yussim, Alexander; Hazzan, Marc; Wekerle, Thomas; Berglund, David; De Biase, Consuelo; Pérez-Sáez, María José; Mühlfeld, Anja; Orlando, Giuseppe; Clemente, Katia; Lai, Quirino; Pisani, Francesco; Kandus, Aljosa; Baas, Marije; Bemelman, Frederike; Ponikvar, Jadranka Buturovic; Mazouz, Hakim; Stratta, Piero; Subra, Jean-François; Villemain, Florence; Hoitsma, Andries; Braun, Laura; Cantarell, Maria Carmen; Colak, Hulya; Courtney, Aisling; Frasca, Giovanni Maria; Howse, Matthew; Naesens, Maarten; Reischig, Tomas; Serón, Daniel; Seyahi, Nurhan; Tugmen, Cem; Alonso Hernandez, Angel; Beňa, Luboslav; Biancone, Luigi; Cuna, Vania; Díaz-Corte, Carmen; Dufay, Alexandre; Gaasbeek, André; Garnier, Arnaud; Gatault, Philippe; Gentil Govantes, Miguel Angel; Glowacki, François; Gross, Oliver; Hurault de Ligny, Bruno; Huynh-Do, Uyen; Janbon, Bénédicte; Jiménez Del Cerro, Luis Antonio; Keller, Frieder; La Manna, Gaetano; Lauzurica, Ricardo; Le Monies De Sagazan, Hervé; Thaiss, Friedrich; Legendre, Christophe; Martin, Séverine; Moal, Marie-Christine; Noël, Christian; Pillebout, Evangeline; Piredda, Gian Benedetto; Puga, Ana Ramírez; Sulowicz, Wladyslaw; Tuglular, Serhan; Prokopova, Michaela; Chesneau, Mélanie; Le Moine, Alain; Guérif, Pierrick; Soulillou, Jean-Paul; Abramowicz, Marc; Giral, Magali; Racapé, Judith; Maggiore, Umberto; Brouard, Sophie; Abramowicz, Daniel

    2016-06-01

    Kidney recipients maintaining a prolonged allograft survival in the absence of immunosuppressive drugs and without evidence of rejection are supposed to be exceptional. The ERA-EDTA-DESCARTES working group together with Nantes University launched a European-wide survey to identify new patients, describe them and estimate their frequency for the first time. Seventeen coordinators distributed a questionnaire in 256 transplant centres and 28 countries in order to report as many 'operationally tolerant' patients (TOL; defined as having a serum creatinine <1.7 mg/dL and proteinuria <1 g/day or g/g creatinine despite at least 1 year without any immunosuppressive drug) and 'almost tolerant' patients (minimally immunosuppressed patients (MIS) receiving low-dose steroids) as possible. We reported their number and the total number of kidney transplants performed at each centre to calculate their frequency. One hundred and forty-seven questionnaires were returned and we identified 66 TOL (61 with complete data) and 34 MIS patients. Of the 61 TOL patients, 26 were previously described by the Nantes group and 35 new patients are presented here. Most of them were noncompliant patients. At data collection, 31/35 patients were alive and 22/31 still operationally tolerant. For the remaining 9/31, 2 were restarted on immunosuppressive drugs and 7 had rising creatinine of whom 3 resumed dialysis. Considering all patients, 10-year death-censored graft survival post-immunosuppression weaning reached 85% in TOL patients and 100% in MIS patients. With 218 913 kidney recipients surveyed, cumulative incidences of operational tolerance and almost tolerance were estimated at 3 and 1.5 per 10 000 kidney recipients, respectively. In kidney transplantation, operational tolerance and almost tolerance are infrequent findings associated with excellent long-term death-censored graft survival. © The Author 2016. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

  12. [Autoantibodies, tolerance and autoimmunity].

    PubMed

    Oppezzo, Pablo; Dighiero, Guillaume

    2003-07-01

    In 1900, the group from Metchnikoff suggested the concept of autoimmunization by demonstrating the presence of autoantibodies in normal conditions; which was opposed to the concept of horror autotoxicus raised by Ehrlich. Landsteiner's description of the transfusion compatibility rules and 50 year-later work from Burnett's and Medawar's groups lead to the clonal deletion theory as a general explanation of tolerance and autoimmunity. However, more recent work succeeded demonstrating that autoreactive B cells constitute a substantial part of the B-cell repertoire and that this autoreactive repertoire secretes the so-called natural autoantibodies (NAA) characterized by their broad reactivity mainly directed against very well conserved public epitopes. They fulfill the definition of an autoantibody since they are self-reactive, but they are not self-specific. As yet, NAA directed against determinants of polymorphism have not been reported. The presence of this repertoire in normal conditions challenges the clonal deletion theory as a unique explanation for self-tolerance. However, if we take into account that this autoreactive B-cell repertoire is not self-specific, this contradiction may not be a real one opposition. Indeed, the Lansteiner's rule that a subject belonging to group A will never produce anti-A antibodies and will always produce natural antibodies against the B-cell group, could never be challenged. Clonal deletion is probably accounting for this phenomenum. However, the serum of healthy adult individuals frequently exhibits low titers of anti-I antibodies, which is a precursor molecule of AB0 antigen system. The mechanism accounting for deletion of B cells directed against critical determinants like antigens A and B in the red blood cell system and allowing the production of autoantibodies against I remain elusive.

  13. Behavioral Tolerance to Anticholinergic Agents

    DTIC Science & Technology

    1986-11-20

    tolerance to marihuana in rats. Pharmacology Biochemistry and Behavior, 1, 73-76. 43 40. Olson, J. and Carder, B. (1974) Behavioral tolerance to... marihuana as a function of amount of prior training. Pharmacology Biochemistry and Behavior, 2, 243-247. 41. Sidman, M. (1960) Tactics of Scientific

  14. Pathways to Tolerance: Student Diversity.

    ERIC Educational Resources Information Center

    Daugherty, Dorothy, Ed.; Stanhope, Victoria, Ed.

    Ideas for schools to support tolerance and celebrate student diversity are presented in this volume of reprinted articles. Titles include: (1) "One of Us, One of Them: Lessons in Diversity for a School Psychologist" (M. M. Chittooran); (2) "The Tolerance-in-Action Campaign" (H. M. Knoff); (3) "Immigrant Parents and the…

  15. Pathways to Tolerance: Student Diversity.

    ERIC Educational Resources Information Center

    Daugherty, Dorothy, Ed.; Stanhope, Victoria, Ed.

    Ideas for schools to support tolerance and celebrate student diversity are presented in this volume of reprinted articles. Titles include: (1) "One of Us, One of Them: Lessons in Diversity for a School Psychologist" (M. M. Chittooran); (2) "The Tolerance-in-Action Campaign" (H. M. Knoff); (3) "Immigrant Parents and the…

  16. Tolerance Issue in Kazakh Culture

    ERIC Educational Resources Information Center

    Aubakirova, Saltanat S.; Ismagambetova, Zukhra N.; Karabayeva, Aliya G.; Rysbekova, Shamshiya S.; Mirzabekova, Alma Sh.

    2016-01-01

    In this article the authors reveal the basic cultural mechanisms that influence the formation of the tolerance strategy in Kazakh and Kazakhstan society, show its basic directions, as well as its importance for the modern Kazakhstan society and the formation of intercultural communication with foreign countries. Tolerance is a necessary element of…

  17. [Postgenomic analysis of desiccation tolerance].

    PubMed

    Buitink, Julia; Leprince, Olivier

    2008-01-01

    Desiccation tolerance is the capacity to survive complete drying. It is an ancient trait that can be found in prokaryotes, fungi, primitive animals (often at the larval stages), whole plants, pollens and seeds. In the dry state, metabolism is suspended and the duration that anhydrobiotes can survive ranges from years to centuries. Whereas genes induced by drought stress have been successfully enumerated in tissues that are sensitive to cellular desiccation, we have little knowledge as to the adaptive role of these genes in establishing desiccation tolerance at the cellular level. This paper reviews postgenomic approaches in a variety of desiccation tolerant organisms in which the genetic responses have been investigated when they acquire the capacity of tolerating extremes of dehydration or when they are dry. Accumulation of non-reducing sugars, LEA proteins and a coordinated repression of metabolism appear to be the essential and universal attributes that can confer desiccation tolerance. The protective mechanisms of these attributes are described. Furthermore, it is most likely that other mechanisms have evolved since the function of about 30% of the genes involved in desiccation tolerance remains to be elucidated. The question of the overlap between desiccation tolerance and drought tolerance is briefly addressed.

  18. 7 CFR 51.1306 - Tolerances.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Tolerances. 51.1306 Section 51.1306 Agriculture... Standards for Winter Pears 1 Tolerances § 51.1306 Tolerances. (a) In order to allow for variations incident... applying the foregoing tolerances to the combination grade no part of any tolerance shall be used to...

  19. 7 CFR 51.1265 - Tolerances.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Tolerances. 51.1265 Section 51.1265 Agriculture... Standards for Summer and Fall Pears 1 Tolerances § 51.1265 Tolerances. (a) In order to allow for variations... applying the foregoing tolerances to the combination grade no part of any tolerance shall be used to...

  20. Plant salt-tolerance mechanisms

    PubMed Central

    Deinlein, Ulrich; Stephan, Aaron B.; Horie, Tomoaki; Luo, Wei; Xu, Guohua; Schroeder, Julian I.

    2014-01-01

    Crop performance is severely affected by high salt concentrations in soils. To engineer more salt-tolerant plants it is crucial to unravel the key components of the plant salt tolerance network. Here we review our understanding of the core salt-tolerance mechanisms in plants. Recent studies have shown that stress sensing and signaling components may play important roles in regulating the plant salinity stress response. We also review key Na+ transport and detoxification pathways and the impact of epigenetic chromatin modifications on salinity tolerance. In addition, we discuss the progress that has been made toward engineering salt tolerance in crops, including marker assisted selection and gene stacking techniques. We also identify key open questions that remain to be addressed in the future. PMID:24630845

  1. Plant salt-tolerance mechanisms

    SciTech Connect

    Deinlein, Ulrich; Stephan, Aaron B.; Horie, Tomoaki; Luo, Wei; Xu, Guohua; Schroeder, Julian I.

    2014-06-01

    Crop performance is severely affected by high salt concentrations in soils. To engineer more salt-tolerant plants it is crucial to unravel the key components of the plant salt-tolerance network. Here we review our understanding of the core salt-tolerance mechanisms in plants. Recent studies have shown that stress sensing and signaling components can play important roles in regulating the plant salinity stress response. We also review key Na+ transport and detoxification pathways and the impact of epigenetic chromatin modifications on salinity tolerance. In addition, we discuss the progress that has been made towards engineering salt tolerance in crops, including marker-assisted selection and gene stacking techniques. We also identify key open questions that remain to be addressed in the future.

  2. Plant salt-tolerance mechanisms.

    PubMed

    Deinlein, Ulrich; Stephan, Aaron B; Horie, Tomoaki; Luo, Wei; Xu, Guohua; Schroeder, Julian I

    2014-06-01

    Crop performance is severely affected by high salt concentrations in soils. To engineer more salt-tolerant plants it is crucial to unravel the key components of the plant salt-tolerance network. Here we review our understanding of the core salt-tolerance mechanisms in plants. Recent studies have shown that stress sensing and signaling components can play important roles in regulating the plant salinity stress response. We also review key Na+ transport and detoxification pathways and the impact of epigenetic chromatin modifications on salinity tolerance. In addition, we discuss the progress that has been made towards engineering salt tolerance in crops, including marker-assisted selection and gene stacking techniques. We also identify key open questions that remain to be addressed in the future.

  3. Plant salt-tolerance mechanisms

    DOE PAGES

    Deinlein, Ulrich; Stephan, Aaron B.; Horie, Tomoaki; ...

    2014-06-01

    Crop performance is severely affected by high salt concentrations in soils. To engineer more salt-tolerant plants it is crucial to unravel the key components of the plant salt-tolerance network. Here we review our understanding of the core salt-tolerance mechanisms in plants. Recent studies have shown that stress sensing and signaling components can play important roles in regulating the plant salinity stress response. We also review key Na+ transport and detoxification pathways and the impact of epigenetic chromatin modifications on salinity tolerance. In addition, we discuss the progress that has been made towards engineering salt tolerance in crops, including marker-assisted selectionmore » and gene stacking techniques. We also identify key open questions that remain to be addressed in the future.« less

  4. Tolerable Beam Loss at High-Intensity Machines

    SciTech Connect

    Oleg E. Krivosheev, Nikolai V. Mokhov

    2000-08-28

    Tolerable beam losses are estimated for high-intensity ring accelerators with proton energy of 3 to 16 GeV. Dependence on beam energy, lattice and magnet geometry is studied via full Monte Carlo MARS14 simulations in lattice elements, shielding, tunnel and surrounding dirt with realistic geometry, materials and magnetic fields.

  5. From immunosuppression to tolerance.

    PubMed

    Adams, David H; Sanchez-Fueyo, Alberto; Samuel, Didier

    2015-04-01

    The past three decades have seen liver transplantation becoming a major therapeutic approach in the management of end-stage liver diseases. This is due to the dramatic improvement in survival after liver transplantation as a consequence of the improvement of surgical and anaesthetic techniques, of post-transplant medico-surgical management and of prevention of disease recurrence and other post-transplant complications. Improved use of post-transplant immunosuppression to prevent acute and chronic rejection is a major factor in these improved results. The liver has been shown to be more tolerogenic than other organs, and matching of donor and recipients is mainly limited to ABO blood group compatibility. However, long-term immunosuppression is required to avoid severe acute and chronic rejection and graft loss. With the current immunosuppression protocols, the risk of acute rejection requiring additional therapy is 10-40% and the risk of chronic rejection is below 5%. However, the development of histological lesions in the graft in long-term survivors suggest atypical forms of graft rejection may develop as a consequence of under-immunosuppression. The backbone of immunosuppression remains calcineurin inhibitors (CNI) mostly in association with steroids in the short-term and mycophenolate mofetil or mTOR inhibitors (everolimus). The occurrence of post-transplant complications related to the immunosuppressive therapy has led to the development of new protocols aimed at protecting renal function and preventing the development of de novo cancer and of dysmetabolic syndrome. However, there is no new class of immunosuppressive drugs in the pipeline able to replace current protocols in the near future. The aim of a full immune tolerance of the graft is rarely achieved since only 20% of selected patients can be weaned successfully off immunosuppression. In the future, immunosuppression will probably be more case oriented aiming to protect the graft from rejection and at

  6. Validation of a fault-tolerant clock synchronization system

    NASA Technical Reports Server (NTRS)

    Butler, R. W.; Johnson, S. C.

    1984-01-01

    A validation method for the synchronization subsystem of a fault tolerant computer system is investigated. The method combines formal design verification with experimental testing. The design proof reduces the correctness of the clock synchronization system to the correctness of a set of axioms which are experimentally validated. Since the reliability requirements are often extreme, requiring the estimation of extremely large quantiles, an asymptotic approach to estimation in the tail of a distribution is employed.

  7. Glucose tolerance test - non-pregnant

    MedlinePlus

    ... gov/ency/article/003466.htm Glucose tolerance test - non-pregnant To use the sharing features on this ... is broken) Alternative Names Oral glucose tolerance test - non-pregnant; OGTT - non-pregnant; Diabetes - glucose tolerance test; ...

  8. 40 CFR 180.319 - Interim tolerances.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.319 Interim... pesticide chemicals in or on the following raw agricultural commodities: Substances Uses Tolerance in...

  9. Contingencies promote delay tolerance.

    PubMed

    Ghaemmaghami, Mahshid; Hanley, Gregory P; Jessel, Joshua

    2016-09-01

    The effectiveness of functional communication training as treatment for problem behavior depends on the extent to which treatment can be extended to typical environments that include unavoidable and unpredictable reinforcement delays. Time-based progressive delay (TBPD) often results in the loss of acquired communication responses and the resurgence of problem behavior, whereas contingency-based progressive delay (CBPD) appears to be effective for increasing tolerance for delayed reinforcement. No direct comparison of TBPD and CBPD has, however, been conducted. We used single-subject designs to compare the relative efficacy of TBPD and CBPD. Four individuals who engaged in problem behavior (e.g., aggression, vocal and motor disruptions, self-injury) participated. Results were consistent across all participants, and showed lower rates of problem behavior and collateral responses during CBPD than during TBPD. The generality of CBPD treatment effects, including optimal rates of communication and compliance with demands, was demonstrated across a small but heterogeneous group of participants, reinforcement contingencies, and contexts.

  10. Blur tolerance for luminance and chromatic stimuli.

    PubMed

    Wuerger, S M; Owens, H; Westland, S

    2001-06-01

    We investigated the blur tolerance of human observers for stimuli modulated along the isoluminant red-green, the isoluminant yellow-blue, and the luminance (black-white) direction in color space. We report the following results: (i) Blur difference thresholds for red-green and luminance stimuli (of equal cone contrast) are very similar and as low as 0.5 min of visual angle; for yellow-blue the lowest blur thresholds are much higher (1.5 min of visual angle). (ii) The smallest blur thresholds are found for slightly blurred square waves (reference blur of 1 arc min) and not for sharp edges. (iii) Blur thresholds for red-green and black-white follow a Weber law for reference (pedestal) blurs greater than the optimum blur. (iv) Using the model proposed by Watt and Morgan [Vision Res. 24, 1387 (1984)] we estimated the internal blur of the visual system for the black-white and the red-green color directions and arrived at the following estimates: 1.2 arc min for black-white stimuli at 10% contrast and 0.9 arc min for red-green stimuli at 10% cone contrast. Blur tolerance for yellow-blue is independent of external blur and cannot be predicted by the model. (v) The contrast dependence of blur sensitivity is similar for red-green and luminance modulations (slopes of -0.15 and -0.16 in log-log coordinates, respectively) and slightly stronger for yellow-blue (slope = -0.75). Blur discrimination thresholds are not predicted by the contrast sensitivity function of the visual system. Our findings are useful for predicting blur tolerance for complex images and provide a spatial frequency cutoff point when Gaussian low-pass filters are used for noise removal in colored images. They are also useful as a baseline for the study of visual disorders such as amblyopia.

  11. MECHANISMS OF ENDOTOXIN TOLERANCE

    PubMed Central

    Greisman, Sheldon E.; Woodwards, William E.

    1965-01-01

    Bacterial endotoxins were administered by continuous intravenous infusions at constant rates to normal man and rabbits. An initial progressive febrile reaction was followed by progressive defervescence to baseline. The resulting pyrogenic refractory state was characterized as follows: (a) reticuloendothelial blockade with thorotrast neither prevented nor reversed its course; (b) passive transfer was unsuccessful with refractory phase plasma; (c) infusions of normal plasma or fresh whole blood failed to restore responsiveness; (d) a minimum of 4 hours of continuous endotoxin infusion was required for full development of unresponsiveness; (e) circulating antibody titers to endotoxin remained unaltered; (f) peripheral leukocytosis appeared; (g) infusion of febrile phase plasma reevoked an immediate, monophasic fever; (h) endotoxinemia could be demonstrated by pyrogen bioassay; (i) 10-fold increases in endotoxin infusion rates reevoked fever; (j) impaired responsiveness extended to heterologous endotoxins; (k) dermal inflammatory responses to endotoxin were suppressed in man while tuberculin reactivity remained unimpaired; dermal inflammatory responses to endotoxin were enhanced in rabbits; and (l) pyrogenic reactivity to endotoxin reappeared within 24 hours in man; refractoriness persisted in rabbits. It is concluded that the pyrogenic refractory state reflects an inability of the host to continue to mobilize endogenous pyrogen during sustained endotoxinemia. Such observations, together with previous studies, are consistent with two distinct immunologic mechanisms of resistance to endotoxin pyrogenicity: (a) desensitization at the cellular level; and (b) elaboration of circulating antibodies which assist reticuloendothelial clearance and destruction of endotoxin. Whereas both such mechanisms may contribute to pyrogenic tolerance, the characteristics of the pyrogenic refractory state suggest the participation only of the former. PMID:14319407

  12. On the design of fault-tolerant robotic manipulator systems

    NASA Technical Reports Server (NTRS)

    Tesar, Delbert

    1993-01-01

    Robotic systems are finding increasing use in space applications. Many of these devices are going to be operational on board the Space Station Freedom. Fault tolerance has been deemed necessary because of the criticality of the tasks and the inaccessibility of the systems to maintenance and repair. Design for fault tolerance in manipulator systems is an area within robotics that is without precedence in the literature. In this paper, we will attempt to lay down the foundations for such a technology. Design for fault tolerance demands new and special approaches to design, often at considerable variance from established design practices. These design aspects, together with reliability evaluation and modeling tools, are presented. Mechanical architectures that employ protective redundancies at many levels and have a modular architecture are then studied in detail. Once a mechanical architecture for fault tolerance has been derived, the chronological stages of operational fault tolerance are investigated. Failure detection, isolation, and estimation methods are surveyed, and such methods for robot sensors and actuators are derived. Failure recovery methods are also presented for each of the protective layers of redundancy. Failure recovery tactics often span all of the layers of a control hierarchy. Thus, a unified framework for decision-making and control, which orchestrates both the nominal redundancy management tasks and the failure management tasks, has been derived. The well-developed field of fault-tolerant computers is studied next, and some design principles relevant to the design of fault-tolerant robot controllers are abstracted. Conclusions are drawn, and a road map for the design of fault-tolerant manipulator systems is laid out with recommendations for a 10 DOF arm with dual actuators at each joint.

  13. The genetic analysis of tolerance to infections: a review

    PubMed Central

    Kause, Antti; Ødegård, Jørgen

    2012-01-01

    Tolerance to infections is defined as the ability of a host to limit the impact of a given pathogen burden on host performance. Uncoupling resistance and tolerance is a challenge, and there is a need to be able to separate them using specific trait recording or statistical methods. We present three statistical methods that can be used to investigate genetics of tolerance-related traits. Firstly, using random regressions, tolerance can be analyzed as a reaction norm slope in which host performance (y-axis) is regressed against an increasing pathogen burden (x-axis). Genetic variance in tolerance slopes is the genetic variance for tolerance. Variation in tolerance can induce genotype re-ranking and changes in genetic and phenotypic variation in host performance along the pathogen burden trajectory, contributing to environment-dependent genetic responses to selection. Such genotype-by-environment interactions can be quantified by combining random regressions and covariance functions. To apply random regressions, pathogen burden of individuals needs to be recorded. Secondly, when pathogen burden is not recorded, the cure model for time-until-death data allows separating two traits, susceptibility and endurance. Susceptibility is whether or not an individual was susceptible to an infection, whereas endurance denotes how long time it took until the infection killed a susceptible animal (influenced by tolerance). Thirdly, the normal mixture model can be used to classify continuously distributed host performance, such as growth rate, into different sub-classes (e.g., non-infected and infected), which allows estimation of host performance reduction specific to infected individuals. Moreover, genetics of host performance can be analyzed separately in healthy and affected animals, even in the absence of pathogen burden and survival data. These methods provide novel tools to increase our understanding on the impact of parasites, pathogens, and production diseases on host

  14. Patenting drought tolerance in organisms.

    PubMed

    Somvanshi, Vishal S

    2009-01-01

    Dehydration is a major form of osmotic stress in cells. Physiological and molecular basis of dehydration stress responses in cells and organisms has been intensively researched over past years. Almost all of the patented dehydration stress tolerance genes from different organisms were used in engineering drought tolerance in crop plants. In spite of the moral, religious and ethical controversies surrounding use of foreign DNA sequences in crop plants, the numbers of such patents has grown tremendously in recent years. In future, we might witness another rise in patents on use of dehydration stress related gene sequences in creating environmental stress tolerant biological control agents for plant disease and insect pest management in agriculture. This review summarizes some of the recent published patents related to drought tolerance genes and their use.

  15. Exploiting Tolerance Processes in Transplantation

    NASA Astrophysics Data System (ADS)

    Waldmann, Herman; Cobbold, Stephen

    2004-07-01

    The full potential of organ transplantation has not yet been realized because of the hazards associated with the long-term use of immunosuppressive drugs. Modern research into mechanisms of immune tolerance offers the promise of reprogramming the immune system, so as to harness the body's natural tolerance mechanisms in the service of graft acceptance. This would allow the minimization of immunosuppressive treatment and offers the prospect of eventually weaning transplant recipients off their drugs.

  16. Fault-tolerant rotary actuator

    DOEpatents

    Tesar, Delbert

    2006-10-17

    A fault-tolerant actuator module, in a single containment shell, containing two actuator subsystems that are either asymmetrically or symmetrically laid out is provided. Fault tolerance in the actuators of the present invention is achieved by the employment of dual sets of equal resources. Dual resources are integrated into single modules, with each having the external appearance and functionality of a single set of resources.

  17. Combined methods of tolerance increasing for embedded SRAM

    NASA Astrophysics Data System (ADS)

    Shchigorev, L. A.; Shagurin, I. I.

    2016-10-01

    The abilities of combined use of different methods of fault tolerance increasing for SRAM such as error detection and correction codes, parity bits, and redundant elements are considered. Area penalties due to using combinations of these methods are investigated. Estimation is made for different configurations of 4K x 128 RAM memory block for 28 nm manufacturing process. Evaluation of the effectiveness of the proposed combinations is also reported. The results of these investigations can be useful for designing fault-tolerant “system on chips”.

  18. Tolerance analyses of a quadrupole magnet for advanced photon source upgrade

    SciTech Connect

    Liu, J. Jaski, M. Borland, M.; Jain, A.

    2016-07-27

    Given physics requirements, the mechanical fabrication and assembly tolerances for storage ring magnets can be calculated using analytical methods [1, 2]. However, this method is not easy for complicated magnet designs [1]. In this paper, a novel method is proposed to determine fabrication and assembly tolerances consistent with physics requirements, through a combination of magnetic and mechanical tolerance analyses. In this study, finite element analysis using OPERA is conducted to estimate the effect of fabrication and assembly errors on the magnetic field of a quadrupole magnet and to determine the allowable tolerances to achieve the specified magnetic performances. Based on the study, allowable fabrication and assembly tolerances for the quadrupole assembly are specified for the mechanical design of the quadrupole magnet. Next, to achieve the required assembly level tolerances, mechanical tolerance stackup analyses using a 3D tolerance analysis package are carried out to determine the part and subassembly level fabrication tolerances. This method can be used to determine the tolerances for design of other individual magnets and of magnet strings.

  19. Multiple Heavy Metal Tolerance of Soil Bacterial Communities and Its Measurement by a Thymidine Incorporation Technique

    PubMed Central

    Díaz-Raviña, Montserrat; Bååth, Erland; Frostegård, Åsa

    1994-01-01

    A thymidine incorporation technique was used to determine the tolerance of a soil bacterial community to Cu, Cd, Zn, Ni, and Pb. An agricultural soil was artificially contaminated in our laboratory with individual metals at three different concentrations, and the results were compared with the results obtained by using the plate count technique. Thymidine incorporation was found to be a simple and rapid method for measuring tolerance. Data obtained by this technique were very reproducible. A linear relationship was found between changes in community tolerance levels obtained by the thymidine incorporation and plate count techniques (r = 0.732, P < 0.001). An increase in tolerance to the metal added to soil was observed for the bacterial community obtained from each polluted soil compared with the community obtained from unpolluted soil. The only exception was when Pb was added; no indication of Pb tolerance was found. An increase in the tolerance to metals other than the metal originally added to soil was also observed, indicating that there was multiple heavy metal tolerance at the community level. Thus, Cu pollution, in addition to increasing tolerance to Cu, also induced tolerance to Zn, Cd, and Ni. Zn and Cd pollution increased community tolerance to all five metals. Ni amendment increased tolerance to Ni the most but also increased community tolerance to Zn and, to lesser degrees, increased community tolerance to Pb and Cd. In soils polluted with Pb increased tolerance to other metals was found in the following order: Ni > Cd > Zn > Cu. We found significant positive relationships between changes in Cd, Zn, and Pb tolerance and, to a lesser degree, between changes in Pb and Ni tolerance when all metals and amendment levels were compared. The magnitude of the increase in heavy metal tolerance was found to be linearly related to the logarithm of the metal concentration added to the soil. Threshold tolerance concentrations were estimated from these linear

  20. Flooding tolerance of forage legumes.

    PubMed

    Striker, Gustavo G; Colmer, Timothy D

    2016-06-20

    We review waterlogging and submergence tolerances of forage (pasture) legumes. Growth reductions from waterlogging in perennial species ranged from >50% for Medicago sativa and Trifolium pratense to <25% for Lotus corniculatus, L. tenuis, and T. fragiferum For annual species, waterlogging reduced Medicago truncatula by ~50%, whereas Melilotus siculus and T. michelianum were not reduced. Tolerant species have higher root porosity (gas-filled volume in tissues) owing to aerenchyma formation. Plant dry mass (waterlogged relative to control) had a positive (hyperbolic) relationship to root porosity across eight species. Metabolism in hypoxic roots was influenced by internal aeration. Sugars accumulate in M. sativa due to growth inhibition from limited respiration and low energy in roots of low porosity (i.e. 4.5%). In contrast, L. corniculatus, with higher root porosity (i.e. 17.2%) and O2 supply allowing respiration, maintained growth better and sugars did not accumulate. Tolerant legumes form nodules, and internal O2 diffusion along roots can sustain metabolism, including N2 fixation, in submerged nodules. Shoot physiology depends on species tolerance. In M. sativa, photosynthesis soon declines and in the longer term (>10 d) leaves suffer chlorophyll degradation, damage, and N, P, and K deficiencies. In tolerant L corniculatus and L. tenuis, photosynthesis is maintained longer, shoot N is less affected, and shoot P can even increase during waterlogging. Species also differ in tolerance of partial and complete shoot submergence. Gaps in knowledge include anoxia tolerance of roots, N2 fixation during field waterlogging, and identification of traits conferring the ability to recover after water subsides.

  1. On requirements for software fault tolerance for flight controls

    NASA Technical Reports Server (NTRS)

    Migneault, G. E.

    1983-01-01

    The need for the application of software fault tolerance techniques in digital flight control systems is argued to follow from the requirements derivable from the safety constraints of such systems, requirements which can be stated in terms of minimum acceptable system reliability levels and, moreover, stated quantitatively. It is argued further that, while fault tolerance appears to be a viable mechanism in general, individual fault tolerance schemes need to be analyzed to ensure that they are adequate to the task and being properly utilized, that such analysis is essentially an exercise in software 'reliability' estimation involving software characteristics not currently included in software 'reliability' modeling (most especially, the degree of correlation of malfunctions among redundant, dissimilar software modules), and that, consequently, further research and studies in the characterization of software behavior and malfunctions is required.

  2. Desiccation tolerance in Staphylococcus aureus.

    PubMed

    Chaibenjawong, Plykaeow; Foster, Simon J

    2011-02-01

    Staphylococcus aureus is a multidrug-resistant pathogen that not only causes a diverse array of human diseases, but also is able to survive in potentially dry and stressful environments, such as the human nose, on skin and on inanimate surfaces such as clothing and surfaces. This study investigated parameters governing desiccation tolerance of S. aureus and identified several components involved in the process. Initially, the role of environmental parameters such as temperature, growth phase, cell density, desiccation time and protectants in desiccation tolerance were determined. This established a robust model of desiccation tolerance in which S. aureus has the ability to survive on dry plastic surfaces for more than 1,097 days. Using a combination of a random screen and defined mutants, clpX, sigB and yjbH were identified as being required for desiccation tolerance. ClpX is a part of the ATP-dependent ClpXP protease, important for protein turnover, and YjbH has a proposed linked function. SigB is an accessory sigma factor with a role in generalized stress resistance. Understanding the molecular mechanisms that govern desiccation tolerance may determine the break points to be exploited to prevent the spread of this dangerous pathogen in hospitals and communities.

  3. The Relationship between Population Structure and Aluminum Tolerance in Cultivated Sorghum

    PubMed Central

    Caniato, Fernanda F.; Guimarães, Claudia T.; Hamblin, Martha; Billot, Claire; Rami, Jean-François; Hufnagel, Barbara; Kochian, Leon V.; Liu, Jiping; Garcia, Antonio Augusto F.; Hash, C. Tom; Ramu, Punna; Mitchell, Sharon; Kresovich, Stephen; Oliveira, Antônio Carlos; de Avellar, Gisela; Borém, Aluízio; Glaszmann, Jean-Christophe; Schaffert, Robert E.; Magalhaes, Jurandir V.

    2011-01-01

    Background Acid soils comprise up to 50% of the world's arable lands and in these areas aluminum (Al) toxicity impairs root growth, strongly limiting crop yield. Food security is thereby compromised in many developing countries located in tropical and subtropical regions worldwide. In sorghum, SbMATE, an Al-activated citrate transporter, underlies the AltSB locus on chromosome 3 and confers Al tolerance via Al-activated root citrate release. Methodology Population structure was studied in 254 sorghum accessions representative of the diversity present in cultivated sorghums. Al tolerance was assessed as the degree of root growth inhibition in nutrient solution containing Al. A genetic analysis based on markers flanking AltSB and SbMATE expression was undertaken to assess a possible role for AltSB in Al tolerant accessions. In addition, the mode of gene action was estimated concerning the Al tolerance trait. Comparisons between models that include population structure were applied to assess the importance of each subpopulation to Al tolerance. Conclusion/Significance Six subpopulations were revealed featuring specific racial and geographic origins. Al tolerance was found to be rather rare and present primarily in guinea and to lesser extent in caudatum subpopulations. AltSB was found to play a role in Al tolerance in most of the Al tolerant accessions. A striking variation was observed in the mode of gene action for the Al tolerance trait, which ranged from almost complete recessivity to near complete dominance, with a higher frequency of partially recessive sources of Al tolerance. A possible interpretation of our results concerning the origin and evolution of Al tolerance in cultivated sorghum is discussed. This study demonstrates the importance of deeply exploring the crop diversity reservoir both for a comprehensive view of the dynamics underlying the distribution and function of Al tolerance genes and to design efficient molecular breeding strategies aimed at

  4. Drug Tolerance: A Known Unknown in Translational Neuroscience.

    PubMed

    Bespalov, Anton; Müller, Reinhold; Relo, Ana-Lucia; Hudzik, Thomas

    2016-05-01

    In neuropsychiatric drug development, the rate of successful translation of preclinical to clinical efficacy has been disappointingly low. Tolerance, defined as a loss of efficacy with repeated drug exposure, is rarely addressed as a potential source of clinical failures. In this review, we argue that preclinical methods of tolerance development may have predictive validity and, therefore, inclusion of studies using repeated drug exposure early during the drug discovery and development process should serve to mitigate a proportion of clinical failures. Our analysis indicates that many published preclinical efficacy studies in the neuropsychiatry arena are conducted with acute drug administration only. Furthermore, specifically in the field of schizophrenia, there are several examples where tolerance development may be suspected as a factor contributing to translational failures. These and other examples highlight the need for built-for-purpose tolerance studies to be conducted, regardless of the target interaction mode of the drugs (i.e., agonist or antagonist, allosteric or orthosteric). We suggest that, for compounds that have failed in clinical studies, preclinical efficacy data sets need to be revisited to estimate the potential impact of tolerance development, one of the most significant known unknowns in the preclinical-to-clinical translation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Tolerance - One Transplant for Life

    PubMed Central

    Kawai, Tatsuo; Leventhal, Joseph; Madsen, Joren C.; Strober, Samuel; Turka, Laurence A.; Wood, Kathryn J.

    2014-01-01

    A recent TTS workshop was convened to address the question: “What do we need to have in place to make tolerance induction protocols a “standard of care” for organ transplant recipients over the next decade?” In a productive two day meeting there was wide-ranging discussion on a broad series of topics resulting in five consensus recommendations: (1) Establish a registry of results for patients enrolled in tolerance trials; (2) Establish standardized protocols for sample collection and storage; (3) Establish standardized biomarkers and assays; (4) Include children aged 12 and older in protocols that have been validated in adults; (5) a task force to engage third party payers in discussions of how to fund tolerance trials. Future planned workshops will focus on progress in implementing these recommendations and identifying other steps that the community needs to take. PMID:24926829

  6. Neuropilin-1 in Transplantation Tolerance

    PubMed Central

    Campos-Mora, Mauricio; Morales, Rodrigo A.; Gajardo, Tania; Catalán, Diego; Pino-Lagos, Karina

    2013-01-01

    In the immune system, Neuropilin-1 (Nrp1) is a molecule that plays an important role in establishing the immunological synapse between dendritic cells (DCs) and T cells. Recently, Nrp1 has been identified as a marker that seems to distinguish natural T regulatory (nTreg) cells, generated in the thymus, from inducible T regulatory (iTreg) cells raised in the periphery. Given the crucial role of both nTreg and iTreg cells in the generation and maintenance of immune tolerance, the ability to phenotypically identify each of these cell populations in vivo is needed to elucidate their biological properties. In turn, these properties have the potential to be developed for therapeutic use to promote immune tolerance. Here we describe the nature and functions of Nrp1, including its potential use as a therapeutic target in transplantation tolerance. PMID:24324469

  7. Fault-Tolerant Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Izenson, Michael G.; Crowley, Christopher J.

    2005-01-01

    A compact, lightweight heat exchanger has been designed to be fault-tolerant in the sense that a single-point leak would not cause mixing of heat-transfer fluids. This particular heat exchanger is intended to be part of the temperature-regulation system for habitable modules of the International Space Station and to function with water and ammonia as the heat-transfer fluids. The basic fault-tolerant design is adaptable to other heat-transfer fluids and heat exchangers for applications in which mixing of heat-transfer fluids would pose toxic, explosive, or other hazards: Examples could include fuel/air heat exchangers for thermal management on aircraft, process heat exchangers in the cryogenic industry, and heat exchangers used in chemical processing. The reason this heat exchanger can tolerate a single-point leak is that the heat-transfer fluids are everywhere separated by a vented volume and at least two seals. The combination of fault tolerance, compactness, and light weight is implemented in a unique heat-exchanger core configuration: Each fluid passage is entirely surrounded by a vented region bridged by solid structures through which heat is conducted between the fluids. Precise, proprietary fabrication techniques make it possible to manufacture the vented regions and heat-conducting structures with very small dimensions to obtain a very large coefficient of heat transfer between the two fluids. A large heat-transfer coefficient favors compact design by making it possible to use a relatively small core for a given heat-transfer rate. Calculations and experiments have shown that in most respects, the fault-tolerant heat exchanger can be expected to equal or exceed the performance of the non-fault-tolerant heat exchanger that it is intended to supplant (see table). The only significant disadvantages are a slight weight penalty and a small decrease in the mass-specific heat transfer.

  8. Evaluation of reliability modeling tools for advanced fault tolerant systems

    NASA Technical Reports Server (NTRS)

    Baker, Robert; Scheper, Charlotte

    1986-01-01

    The Computer Aided Reliability Estimation (CARE III) and Automated Reliability Interactice Estimation System (ARIES 82) reliability tools for application to advanced fault tolerance aerospace systems were evaluated. To determine reliability modeling requirements, the evaluation focused on the Draper Laboratories' Advanced Information Processing System (AIPS) architecture as an example architecture for fault tolerance aerospace systems. Advantages and limitations were identified for each reliability evaluation tool. The CARE III program was designed primarily for analyzing ultrareliable flight control systems. The ARIES 82 program's primary use was to support university research and teaching. Both CARE III and ARIES 82 were not suited for determining the reliability of complex nodal networks of the type used to interconnect processing sites in the AIPS architecture. It was concluded that ARIES was not suitable for modeling advanced fault tolerant systems. It was further concluded that subject to some limitations (the difficulty in modeling systems with unpowered spare modules, systems where equipment maintenance must be considered, systems where failure depends on the sequence in which faults occurred, and systems where multiple faults greater than a double near coincident faults must be considered), CARE III is best suited for evaluating the reliability of advanced tolerant systems for air transport.

  9. Heat tolerance in Drosophila subobscura along a latitudinal gradient: Contrasting patterns between plastic and genetic responses.

    PubMed

    Castañeda, Luis E; Rezende, Enrico L; Santos, Mauro

    2015-10-01

    Susceptibility to global warming relies on how thermal tolerances respond to increasing temperatures through plasticity or evolution. Climatic adaptation can be assessed by examining the geographic variation in thermal-related traits. We studied latitudinal patterns in heat tolerance in Drosophila subobscura reared at two temperatures. We used four static stressful temperatures to estimate the thermal death time (TDT) curves, and two ramping assays with fast and slow heating rates. Thermal death time curves allow estimation of the critical thermal maximum (CT(max)), by extrapolating to the temperature that would knock down the flies almost "instantaneously," and the thermal sensitivity to increasing stressful temperatures. We found a positive latitudinal cline for CT(max), but no clinal pattern for knockdown temperatures estimated from the ramping assays. Although high-latitude populations were more tolerant to an acute heat stress, they were also more sensitive to prolonged exposure to less stressful temperatures, supporting a trade-off between acute and chronic heat tolerances. Conversely, developmental plasticity did not affect CT(max) but increased the tolerance to chronic heat exposition. The patterns observed from the TDT curves help to understand why the relationship between heat tolerance and latitude depends on the methodology used and, therefore, these curves provide a more complete and reliable measurement of heat tolerance. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  10. Estimating Eggs

    ERIC Educational Resources Information Center

    Lindsay, Margaret; Scott, Amanda

    2005-01-01

    The authors discuss mass as one of the three fundamental measurements (the others being length and time), noting that estimation of mass is little taught and assessed in primary schools. This article briefly explores the reasons for this in terms of culture, practice, and the difficulty of assessing estimation of mass. An activity using the…

  11. A Fault Tolerant System for an Integrated Avionics Sensor Configuration

    NASA Technical Reports Server (NTRS)

    Caglayan, A. K.; Lancraft, R. E.

    1984-01-01

    An aircraft sensor fault tolerant system methodology for the Transport Systems Research Vehicle in a Microwave Landing System (MLS) environment is described. The fault tolerant system provides reliable estimates in the presence of possible failures both in ground-based navigation aids, and in on-board flight control and inertial sensors. Sensor failures are identified by utilizing the analytic relationships between the various sensors arising from the aircraft point mass equations of motion. The estimation and failure detection performance of the software implementation (called FINDS) of the developed system was analyzed on a nonlinear digital simulation of the research aircraft. Simulation results showing the detection performance of FINDS, using a dual redundant sensor compliment, are presented for bias, hardover, null, ramp, increased noise and scale factor failures. In general, the results show that FINDS can distinguish between normal operating sensor errors and failures while providing an excellent detection speed for bias failures in the MLS, indicated airspeed, attitude and radar altimeter sensors.

  12. Fault-tolerant software for aircraft control systems

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Concepts for software to implement real time aircraft control systems on a centralized digital computer were discussed. A fault tolerant software structure employing functionally redundant routines with concurrent error detection was proposed for critical control functions involving safety of flight and landing. A degraded recovery block concept was devised to allow collocation of critical and noncritical software modules within the same control structure. The additional computer resources required to implement the proposed software structure for a representative set of aircraft control functions were discussed. It was estimated that approximately 30 percent more memory space is required to implement the total set of control functions. A reliability model for the fault tolerant software was described and parametric estimates of failure rate were made.

  13. Estimation of past radon exposure to indoor radon from embedded (210)Po in household glass.

    PubMed

    Gusain, G S; Rautela, B S; Ramola, R C

    2012-11-01

    In the present investigation, the surface-deposited polonium activities were measured in houses in the Ukhimath region of Garhwal Himalaya, India. The surface-deposited (210)Po activity concentrations were found to vary from 0.7 to 15.40 Bq m(-2) with an average of 5.95 Bq m(-2). The radon concentration estimated on the basis of (210)Po activity was found to vary from 0.29 to 700 Bq m(-3) with an average value 242 Bq m(-3). The contemporary radon concentration in the area was found to vary from 13 to 181 Bq m(-3) with an average of 46 Bq m(-3). The annual effective dose due to (210)Po activity in houses in the Garhwal Himalaya region was found to vary from 0.61 to 13.33 mSv with an average of 5.15 mSv. Some worldwide studies have shown the relation between the increased risk of lung cancer and smoking habits. Data on smoking have also been collected from the same dwellings. The significance of this work is also discussed in detail from a radiation protection point of view.

  14. Statistical Tolerance and Clearance Analysis for Assembly

    NASA Technical Reports Server (NTRS)

    Lee, S.; Yi, C.

    1996-01-01

    Tolerance is inevitable because manufacturing exactly equal parts is known to be impossible. Furthermore, the specification of tolerances is an integral part of product design since tolerances directly affect the assemblability, functionality, manufacturability, and cost effectiveness of a product. In this paper, we present statistical tolerance and clearance analysis for the assembly. Our proposed work is expected to make the following contributions: (i) to help the designers to evaluate products for assemblability, (ii) to provide a new perspective to tolerance problems, and (iii) to provide a tolerance analysis tool which can be incorporated into a CAD or solid modeling system.

  15. Statistical Tolerance and Clearance Analysis for Assembly

    NASA Technical Reports Server (NTRS)

    Lee, S.; Yi, C.

    1996-01-01

    Tolerance is inevitable because manufacturing exactly equal parts is known to be impossible. Furthermore, the specification of tolerances is an integral part of product design since tolerances directly affect the assemblability, functionality, manufacturability, and cost effectiveness of a product. In this paper, we present statistical tolerance and clearance analysis for the assembly. Our proposed work is expected to make the following contributions: (i) to help the designers to evaluate products for assemblability, (ii) to provide a new perspective to tolerance problems, and (iii) to provide a tolerance analysis tool which can be incorporated into a CAD or solid modeling system.

  16. Civic Tolerance among Honors Students

    ERIC Educational Resources Information Center

    Shepherd, Gordon; Shepherd, Gary

    2014-01-01

    As important as cognitive outcomes are in assessing the educational merits of honors programs, the authors ask whether honors programs affect the values and social attitudes of their students differently than other students: in particular, whether honors students are more or less tolerant than other students and, if so, in what ways and why. There…

  17. Stepping Back from Zero Tolerance

    ERIC Educational Resources Information Center

    Browne-Dianis, Judith

    2011-01-01

    Schools' use of zero tolerance policies has been increasing since the 1980s as part of a societal movement to crack down on drug abuse and violence among youth. But far from making schools safer, this harsh, inflexible approach to discipline has been eroding the culture of schools and creating devastating consequences for children, writes…

  18. Toleration, Multiculturalism and Mistaken Belief

    ERIC Educational Resources Information Center

    Standish, Paul

    2006-01-01

    Doubts have been expressed about the virtue of toleration, especially in view of what some have seen as its complicity with a morality of anything goes. More rigorous arguments have been provided by Peter Gardner and Harvey Siegel against the relativism evident in certain versions of multiculturalism and in the new religious studies. This article…

  19. Tolerance of snakes to hypergravity

    NASA Technical Reports Server (NTRS)

    Lillywhite, H. B.; Ballard, R. E.; Hargens, A. R.

    1996-01-01

    Sensitivity of carotid blood flow to increased gravitational force acting in the head-to-tail direction(+Gz) was studied in diverse species of snakes hypothesized to show adaptive variation of response. Tolerance to increased gravity was measured red as the maximum graded acceleration force at which carotid blood flow ceased and was shown to vary according to gravitational adaptation of species defined by their ecology and behavior. Multiple regression analysis showed that gravitational habitat, but not body length, had a significant effect on Gz tolerance. At the extremes, carotid blood flow decreased in response to increasing G force and approached zero near +1 Gz in aquatic and ground-dwelling species, whereas in climbing species carotid flow was maintained at forces in excess of +2 Gz. Tolerant (arboreal) species were able to withstand hypergravic forces of +2 to +3 Gz for periods up to 1 h without cessation of carotid blood flow or loss of body movement and tongue flicking. Data suggest that the relatively tight skin characteristic of tolerant species provides a natural antigravity suit and is of prime importance in counteracting Gz stress on blood circulation.

  20. Assessing Your Board's Risk Tolerance

    ERIC Educational Resources Information Center

    Griswold, John S.; Jarvis, William F.

    2014-01-01

    In the wake of the financial crisis, trustees of many endowed nonprofit institutions realized that their portfolio was riskier than they thought and their own ability to tolerate loss wasn't as strong as they imagined. What can board and investment committee members do to improve their ability to assess their--and their institution's--capacity for…

  1. Stepping Back from Zero Tolerance

    ERIC Educational Resources Information Center

    Browne-Dianis, Judith

    2011-01-01

    Schools' use of zero tolerance policies has been increasing since the 1980s as part of a societal movement to crack down on drug abuse and violence among youth. But far from making schools safer, this harsh, inflexible approach to discipline has been eroding the culture of schools and creating devastating consequences for children, writes…

  2. Developing Political Tolerance. ERIC Digest.

    ERIC Educational Resources Information Center

    Avery, Patricia G.

    Political tolerance is the willingness to extend basic rights and civil liberties to persons and groups whose viewpoints differ from one's own. It is a central tenet of a liberal democracy. The individual rights and freedoms that U.S. citizens value encourage a wide array of ideas and beliefs, some of which may offend segments of the population.…

  3. Vegetable soybean tolerance to pyroxasulfone

    USDA-ARS?s Scientific Manuscript database

    If registered for use on vegetable soybean, pyroxasulfone would fill an important gap in weed management systems in the crop. In order to determine the potential crop injury risk of pyroxasulfone on vegetable soybean, the objective of this work was to quantify vegetable soybean tolerance to pyroxasu...

  4. Biocatalysts with enhanced inhibitor tolerance

    DOEpatents

    Yang, Shihui; Linger, Jeffrey; Franden, Mary Ann; Pienkos, Philip T.; Zhang, Min

    2015-12-08

    Disclosed herein are biocatalysts for the production of biofuels, including microorganisms that contain genetic modifications conferring tolerance to growth and fermentation inhibitors found in many cellulosic feedstocks. Methods of converting cellulose-containing materials to fuels and chemicals, as well as methods of fermenting sugars to fuels and chemicals, using these biocatalysts are also disclosed.

  5. Promoting Tolerance in Preservice Teachers.

    ERIC Educational Resources Information Center

    Swearingen, Judith A.

    1996-01-01

    Describes a social science methods course where preservice teachers taught a unit on controversial topics involving tolerance and intolerance. Students were forbidden to lecture. Permitted methods included cooperative learning, inquiry, simulations, jackdaws, documents, and sociodrama. Student response was generally positive. (MJP)

  6. "Zero Tolerance" for Free Speech.

    ERIC Educational Resources Information Center

    Hils, Lynda

    2001-01-01

    Argues that school policies of "zero tolerance" of threatening speech may violate a student's First Amendment right to freedom of expression if speech is less than a "true threat." Suggests a two-step analysis to determine if student speech is a "true threat." (PKP)

  7. Excess of ²¹⁰polonium activity in the surface urban atmosphere. Part (1) fluctuation of the ²¹⁰Po excess in the air.

    PubMed

    Długosz-Lisiecka, Magdalena

    2015-02-01

    The concentrations of (210)Pb, (210)Bi, and (210)Po in the urban atmosphere of Lodz city were measured from February 2010 to May 2010 and from May 2011 to April 2012. The seasonal changes in the activity ratios for (210)Po/(210)Pb and (210)Bi/(210)Pb indicated that the observed fluctuations were independent of the concentration of tropospheric (210)Pb and its decay products, particularly (210)Po. A simple calculation method was proposed for the estimation of the excess of (210)Po in urban aerosols in relation to the fraction of its activity formed from (210)Pb. On the basis of the results obtained, it was concluded that a substantial part of the (210)Po in urban air did not come from the decay of atmospheric (222)Rn, but rather it was from artificial sources. The highest levels of measured total (210)Po activity were observed during the winter period. This observation suggests that the main source of (210)Po in the investigated region could be related to anthropogenic emissions from domestic heating systems and local coal power plants, rather than from other sources, such as soil resuspension or stratospheric air intrusion as usually suggested in the literature.

  8. Decomposition in reliability analysis of fault-tolerant systems

    NASA Technical Reports Server (NTRS)

    Trivedi, K. S.; Geist, R. M.

    1983-01-01

    The existing approaches to reliability modeling are briefly reviewed. An examination of the limitations of the existing approaches in modeling ultrareliable fault-tolerant systems illustrates the need to use decomposition techniques. The notion of behavioral decomposition is introduced for dealing with reliability models with a large number of states, and a series of examples is presented. The CARE (computer-aided reliability estimation) and HARP (hybrid automated reliability predictor) approaches to reliability are discussed.

  9. Decomposition in reliability analysis of fault-tolerant systems

    NASA Technical Reports Server (NTRS)

    Trivedi, K. S.; Geist, R. M.

    1983-01-01

    The existing approaches to reliability modeling are briefly reviewed. An examination of the limitations of the existing approaches in modeling ultrareliable fault-tolerant systems illustrates the need to use decomposition techniques. The notion of behavioral decomposition is introduced for dealing with reliability models with a large number of states, and a series of examples is presented. The CARE (computer-aided reliability estimation) and HARP (hybrid automated reliability predictor) approaches to reliability are discussed.

  10. Design methods for fault-tolerant finite state machines

    NASA Technical Reports Server (NTRS)

    Niranjan, Shailesh; Frenzel, James F.

    1993-01-01

    VLSI electronic circuits are increasingly being used in space-borne applications where high levels of radiation may induce faults, known as single event upsets. In this paper we review the classical methods of designing fault tolerant digital systems, with an emphasis on those methods which are particularly suitable for VLSI-implementation of finite state machines. Four methods are presented and will be compared in terms of design complexity, circuit size, and estimated circuit delay.

  11. Urbanism, Migration, and Tolerance: A Reassessment.

    ERIC Educational Resources Information Center

    Wilson, Thomas C.

    1991-01-01

    Urbanism's impact on the personality may be stronger than previously thought. Finds that urban residence has a strong positive effect on tolerance. Migration also promotes tolerance, regardless of the size of the destination community. (DM)

  12. Increased tolerance to humans among disturbed wildlife

    PubMed Central

    Samia, Diogo S. M.; Nakagawa, Shinichi; Nomura, Fausto; Rangel, Thiago F.; Blumstein, Daniel T.

    2015-01-01

    Human disturbance drives the decline of many species, both directly and indirectly. Nonetheless, some species do particularly well around humans. One mechanism that may explain coexistence is the degree to which a species tolerates human disturbance. Here we provide a comprehensive meta-analysis of birds, mammals and lizards to investigate species tolerance of human disturbance and explore the drivers of this tolerance in birds. We find that, overall, disturbed populations of the three major taxa are more tolerant of human disturbance than less disturbed populations. The best predictors of the direction and magnitude of bird tolerance of human disturbance are the type of disturbed area (urbanized birds are more tolerant than rural or suburban populations) and body mass (large birds are more tolerant than small birds). By identifying specific features associated with tolerance, these results guide evidence-based conservation strategies to predict and manage the impacts of increasing human disturbance on birds. PMID:26568451

  13. 7 CFR 51.2928 - Tolerances.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Standards for Grades of Apricots Tolerances § 51.2928 Tolerances. In order to allow for variations incident..., by count, of the apricots in any sample may be below the minimum size specified. Application of...

  14. 7 CFR 51.2928 - Tolerances.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apricots Tolerances § 51.2928 Tolerances. In... minimum size: Not more than 10 percent, by count, of the apricots in any sample may be below the minimum...

  15. 7 CFR 51.2928 - Tolerances.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Standards for Grades of Apricots Tolerances § 51.2928 Tolerances. In order to allow for variations incident..., by count, of the apricots in any sample may be below the minimum size specified. Application of...

  16. 7 CFR 51.2928 - Tolerances.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Standards for Grades of Apricots Tolerances § 51.2928 Tolerances. In order to allow for variations incident..., by count, of the apricots in any sample may be below the minimum size specified. Application of...

  17. 7 CFR 51.2928 - Tolerances.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apricots Tolerances § 51.2928 Tolerances. In... minimum size: Not more than 10 percent, by count, of the apricots in any sample may be below the minimum...

  18. 78 FR 78738 - Pendimethalin; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-27

    ... pendimethalin on almond hulls to be higher under this revised tolerance, EPA recalculated the ruminant... increase in the ruminant dietary burden. Furthermore, the increase in tolerance on almond hulls will...

  19. Increased tolerance to humans among disturbed wildlife.

    PubMed

    Samia, Diogo S M; Nakagawa, Shinichi; Nomura, Fausto; Rangel, Thiago F; Blumstein, Daniel T

    2015-11-16

    Human disturbance drives the decline of many species, both directly and indirectly. Nonetheless, some species do particularly well around humans. One mechanism that may explain coexistence is the degree to which a species tolerates human disturbance. Here we provide a comprehensive meta-analysis of birds, mammals and lizards to investigate species tolerance of human disturbance and explore the drivers of this tolerance in birds. We find that, overall, disturbed populations of the three major taxa are more tolerant of human disturbance than less disturbed populations. The best predictors of the direction and magnitude of bird tolerance of human disturbance are the type of disturbed area (urbanized birds are more tolerant than rural or suburban populations) and body mass (large birds are more tolerant than small birds). By identifying specific features associated with tolerance, these results guide evidence-based conservation strategies to predict and manage the impacts of increasing human disturbance on birds.

  20. A Developmental View of Children's Behavioral Tolerance.

    ERIC Educational Resources Information Center

    Safran, Joan S.; Safran, Stephen P.

    1985-01-01

    Analysis of scores of 469 third to sixth graders on the Children's Tolerance Scale yielded significant grade level differences with older children generally the most tolerant. The more outer-directed behaviors were rated as most disturbing. (CL)

  1. 40 CFR 180.460 - Benoxacor; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances...-metolachlor in or on raw agricultural commodities for which tolerances have been established for...

  2. Relationship between fish size and upper thermal tolerance

    USGS Publications Warehouse

    Recsetar, Matthew S.; Zeigler, Matthew P.; Ward, David L.; Bonar, Scott A.; Caldwell, Colleen A.

    2012-01-01

    Using critical thermal maximum (CTMax) tests, we examined the relationship between upper temperature tolerances and fish size (fry-adult or subadult lengths) of rainbow trout Oncorhynchus mykiss (41-200-mm TL), Apache trout O. gilae apache (40-220-mm TL), largemouth bass Micropterus salmoides (72-266-mm TL), Nile tilapia Oreochromis niloticus (35-206-mm TL), channel catfish Ictalurus punctatus (62-264 mm-TL), and Rio Grande cutthroat trout O. clarkii virginalis (36-181-mm TL). Rainbow trout and Apache trout were acclimated at 18°C, Rio Grande cutthroat trout were acclimated at 14°C, and Nile tilapia, largemouth bass, and channel catfish were acclimated at 25°C, all for 14 d. Critical thermal maximum temperatures were estimated and data were analyzed using simple linear regression. There was no significant relationship (P > 0.05) between thermal tolerance and length for Nile tilapia (P = 0.33), channel catfish (P = 0.55), rainbow trout (P = 0.76), or largemouth bass (P = 0.93) for the length ranges we tested. There was a significant negative relationship between thermal tolerance and length for Rio Grande cutthroat trout (R2 = 0.412, P 2 = 0.1374, P = 0.028); however, the difference was less than 1°C across all lengths of Apache trout tested and about 1.3°C across all lengths of Rio Grande cutthroat trout tested. Because there was either no or at most a slight relationship between upper thermal tolerance and size, management and research decisions based on upper thermal tolerance should be similar for the range of sizes within each species we tested. However, the different sizes we tested only encompassed life stages ranging from fry to adult/subadult, so thermal tolerance of eggs, alevins, and larger adults should also be considered before making management decisions affecting an entire species.

  3. Parameter Transient Behavior Analysis on Fault Tolerant Control System

    NASA Technical Reports Server (NTRS)

    Belcastro, Christine (Technical Monitor); Shin, Jong-Yeob

    2003-01-01

    In a fault tolerant control (FTC) system, a parameter varying FTC law is reconfigured based on fault parameters estimated by fault detection and isolation (FDI) modules. FDI modules require some time to detect fault occurrences in aero-vehicle dynamics. This paper illustrates analysis of a FTC system based on estimated fault parameter transient behavior which may include false fault detections during a short time interval. Using Lyapunov function analysis, the upper bound of an induced-L2 norm of the FTC system performance is calculated as a function of a fault detection time and the exponential decay rate of the Lyapunov function.

  4. Attitude Estimation or Quaternion Estimation?

    NASA Technical Reports Server (NTRS)

    Markley, F. Landis

    2003-01-01

    The attitude of spacecraft is represented by a 3x3 orthogonal matrix with unity determinant, which belongs to the three-dimensional special orthogonal group SO(3). The fact that all three-parameter representations of SO(3) are singular or discontinuous for certain attitudes has led to the use of higher-dimensional nonsingular parameterizations, especially the four-component quaternion. In attitude estimation, we are faced with the alternatives of using an attitude representation that is either singular or redundant. Estimation procedures fall into three broad classes. The first estimates a three-dimensional representation of attitude deviations from a reference attitude parameterized by a higher-dimensional nonsingular parameterization. The deviations from the reference are assumed to be small enough to avoid any singularity or discontinuity of the three-dimensional parameterization. The second class, which estimates a higher-dimensional representation subject to enough constraints to leave only three degrees of freedom, is difficult to formulate and apply consistently. The third class estimates a representation of SO(3) with more than three dimensions, treating the parameters as independent. We refer to the most common member of this class as quaternion estimation, to contrast it with attitude estimation. We analyze the first and third of these approaches in the context of an extended Kalman filter with simplified kinematics and measurement models.

  5. "Bringing Up Baby" to Tolerate Germs.

    PubMed

    Nagao, Keisuke; Segre, Julia A

    2015-11-17

    How immune tolerance is maintained in the skin remains unclear. In this issue of Immunity, Rosenblum and colleagues demonstrate that tolerance to commensal bacteria is established during the neonatal period via regulatory T cells. Defining the crucial window during which commensal-specific tolerance is achieved has strategic implications for the induction of tolerance in allergic diseases. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Quantitative genetic analysis of Cry1Ab tolerance in Ostrinia nubilalis Spanish populations.

    PubMed

    Crava, Cristina M; Farinós, Gema P; Bel, Yolanda; Castañera, Pedro; Escriche, Baltasar

    2013-07-01

    Tolerance to Bacillus thuringiensis Cry1Ab toxin in Spanish Ostrinia nubilalis populations was analyzed by quantitative genetic techniques, using isolines established from field-derived insects. F1 offspring was tested for susceptibility to trypsin activated Cry1Ab using a concentration that caused a mean larval mortality of 87% (±17% SD). The progeny of the most tolerant isolines (that had shown mortalities lower than 60%) was crossed to obtain the F2 generation that was exposed to the same Cry1Ab concentration. A clear reduction in mortality (62±17% SD) was observed. The upper limit for heritability was estimated to range between 0.82 and 0.90, suggesting that a high part of phenotypic variation in tolerance to Cry1Ab was attributable to genetic differences. An estimate of the minimum number of segregating factors indicated that the loci involved in tolerance to Cry1Ab were at least two. The role of the cadherin gene, which is a B. thuringiensis resistance gene in Lepidoptera, was assessed in the most tolerant isolines by using an EPIC-PCR marker specifically developed for this study. Association between cadherin and tolerance was obtained in one tolerant isoline; however it could be not confirmed by segregation analysis in the F2 progeny because F2 offspring was not viable. Our results indicate that the tolerance trait is common in Spanish field populations. Quantitative genetic techniques may be helpful for estimating the influence of genetic factors to Cry1Ab tolerance in O. nubilalis.

  7. 76 FR 38036 - Propylene Oxide; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-29

    ...). ACTION: Final rule. SUMMARY: This regulation amends the propylene oxide tolerance on ``nut, tree, group...), announcing the Agency's proposal to amend the propylene oxide tolerance (40 CFR 180.491) on ``nut, tree... the propylene oxide tolerance (40 CFR 180.491) on ``nut, tree, group 14'' to read ``nutmeat,...

  8. Unique preservative tolerance in Tyromyces palustris

    Treesearch

    Frederick Green; Rachel A. Arango; Carol A. Clausen

    2005-01-01

    Fungal tolerance to wood preservatives has been critically important for many years. The tolerance of type cultures to common wood preservatives is, in fact, noted in the AWPA Standards [1]. Gloeophyllum trabeum Mad-617, for example, is particularly tolerant to phenolic and arsenic compounds. One important group of decay fungi that has been studied extensively are...

  9. Tolerance to insect defoliation: biocenotic aspects

    Treesearch

    Andrey A. Pleshanov; Victor I. Voronin; Elena S. Khlimankova; Valentina I. Epova

    1991-01-01

    Woody plant resistance to insect damage is of great importance in forest protection, and tree tolerance is an important element of this resistance. The compensating mechanisms responsible for tolerance are nonspecific as a rule and develop after damage has been caused by phytophagous animals or other unfavorable effects. Beyond that, plant tolerance depends on duration...

  10. 47 CFR 74.464 - Frequency tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Frequency tolerance. 74.464 Section 74.464....464 Frequency tolerance. For operations on frequencies above 25 MHz using authorized bandwidths up to... frequency of each station in compliance with the frequency tolerance requirements of § 90.213 of this...

  11. 47 CFR 74.561 - Frequency tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Frequency tolerance. 74.561 Section 74.561... § 74.561 Frequency tolerance. In the bands above 944 MHz, the operating frequency of the transmitter shall be maintained in accordance with the following table: Frequency band (MHz) Tolerance as percentage...

  12. 47 CFR 74.161 - Frequency tolerances.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Frequency tolerances. 74.161 Section 74.161... Technical Operation and Operators § 74.161 Frequency tolerances. The departure of the carrier frequency or frequencies of an experimental broadcast station must not exceed the tolerance specified in the instrument of...

  13. 47 CFR 74.464 - Frequency tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Frequency tolerance. 74.464 Section 74.464....464 Frequency tolerance. For operations on frequencies above 25 MHz using authorized bandwidths up to... frequency of each station in compliance with the frequency tolerance requirements of § 90.213 of this...

  14. 47 CFR 74.464 - Frequency tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Frequency tolerance. 74.464 Section 74.464....464 Frequency tolerance. For operations on frequencies above 25 MHz using authorized bandwidths up to... frequency of each station in compliance with the frequency tolerance requirements of § 90.213 of this...

  15. 47 CFR 74.161 - Frequency tolerances.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Frequency tolerances. 74.161 Section 74.161... Technical Operation and Operators § 74.161 Frequency tolerances. The departure of the carrier frequency or frequencies of an experimental broadcast station must not exceed the tolerance specified in the instrument of...

  16. 47 CFR 74.464 - Frequency tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Frequency tolerance. 74.464 Section 74.464....464 Frequency tolerance. For operations on frequencies above 25 MHz using authorized bandwidths up to... frequency of each station in compliance with the frequency tolerance requirements of § 90.213 of this...

  17. 47 CFR 74.561 - Frequency tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Frequency tolerance. 74.561 Section 74.561... § 74.561 Frequency tolerance. In the bands above 944 MHz, the operating frequency of the transmitter shall be maintained in accordance with the following table: Frequency band (MHz) Tolerance as percentage...

  18. 47 CFR 74.561 - Frequency tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Frequency tolerance. 74.561 Section 74.561... § 74.561 Frequency tolerance. In the bands above 944 MHz, the operating frequency of the transmitter shall be maintained in accordance with the following table: Frequency band (MHz) Tolerance as percentage...

  19. 47 CFR 74.561 - Frequency tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Frequency tolerance. 74.561 Section 74.561... § 74.561 Frequency tolerance. In the bands above 944 MHz, the operating frequency of the transmitter shall be maintained in accordance with the following table: Frequency band (MHz) Tolerance as percentage...

  20. 47 CFR 74.561 - Frequency tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Frequency tolerance. 74.561 Section 74.561... § 74.561 Frequency tolerance. In the bands above 944 MHz, the operating frequency of the transmitter shall be maintained in accordance with the following table: Frequency band (MHz) Tolerance as percentage...

  1. 47 CFR 74.464 - Frequency tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Frequency tolerance. 74.464 Section 74.464....464 Frequency tolerance. For operations on frequencies above 25 MHz using authorized bandwidths up to... frequency of each station in compliance with the frequency tolerance requirements of § 90.213 of this...

  2. 47 CFR 74.161 - Frequency tolerances.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Frequency tolerances. 74.161 Section 74.161... Technical Operation and Operators § 74.161 Frequency tolerances. The departure of the carrier frequency or frequencies of an experimental broadcast station must not exceed the tolerance specified in the instrument of...

  3. 40 CFR 180.5 - Zero tolerances.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Definitions and Interpretative Regulations § 180.5 Zero tolerances. A zero tolerance means that no amount of the pesticide chemical may remain on the raw...

  4. 40 CFR 180.5 - Zero tolerances.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Definitions and Interpretative Regulations § 180.5 Zero tolerances. A zero tolerance means that no amount of the pesticide chemical may remain on the raw...

  5. 40 CFR 180.5 - Zero tolerances.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Definitions and Interpretative Regulations § 180.5 Zero tolerances. A zero tolerance means that no amount of the pesticide chemical may remain on the raw...

  6. 75 FR 26668 - Flutriafol; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-12

    ...: Tolerance- level residues, 100% crop treated (CT), and DEEM\\TM\\ version 7.81 default processing factors were... chronic exposure assessment: Tolerance-level residues, 100% CT, and DEEM\\TM\\ version 7.81 default... information in the dietary assessment for flutriafol. Tolerance level residues and 100% CT were assumed for...

  7. Increasing ideological tolerance in social psychology.

    PubMed

    Inbar, Yoel; Lammers, Joris

    2015-01-01

    We argue that recognizing current ideological diversity in social psychology and promoting tolerance of minority views is just as important as increasing the number of non-liberal researchers. Increasing tolerance will allow individuals in the minority to express dissenting views, which will improve psychological science by reducing bias. We present four recommendations for increasing tolerance.

  8. 78 FR 42693 - Hexythiazox; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-17

    ... established tolerances for ruminant meat byproducts from 0.05 ppm to 0.5 ppm (PP 2F8054); and by amending the... the ruminant meat byproduct tolerances to 0.5 ppm and an increase in the current egg tolerance to...

  9. Zero Tolerance in Tennessee Schools: An Update.

    ERIC Educational Resources Information Center

    Potts, Kim; Njie, Bintou; Detch, Ethel R.; Walton, Jason

    As required by Tennessee law, this report examines the state's zero-tolerance disciplinary data collected by the Tennessee Department of Education for school years 1999-00, 2000-01, and 2001-02. The first section displays statewide zero-tolerance statistics. The second section focuses on the zero-tolerance statistics of Tennessee's five major…

  10. 7 CFR 51.3744 - Tolerances.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Standards for Grades of Honey Dew and Honey Ball Type Melons Tolerances § 51.3744 Tolerances. In order to... following tolerances, by count, are provided as specified: (a) U.S. No. 1. 10 percent for melons in any lot... not more than 1 percent for melons affected by decay. (b) U.S. Commercial. 20 percent for melons in...

  11. 7 CFR 51.3744 - Tolerances.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Standards for Grades of Honey Dew and Honey Ball Type Melons Tolerances § 51.3744 Tolerances. In order to... following tolerances, by count, are provided as specified: (a) U.S. No. 1. 10 percent for melons in any lot... not more than 1 percent for melons affected by decay. (b) U.S. Commercial. 20 percent for melons in...

  12. 7 CFR 51.3744 - Tolerances.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Standards for Grades of Honey Dew and Honey Ball Type Melons Tolerances § 51.3744 Tolerances. In order to... following tolerances, by count, are provided as specified: (a) U.S. No. 1. 10 percent for melons in any lot... not more than 1 percent for melons affected by decay. (b) U.S. Commercial. 20 percent for melons in...

  13. Enhancement of chronic acceleration tolerance by selection

    NASA Technical Reports Server (NTRS)

    Smith, A. H.

    1982-01-01

    A review is presented of experiments concerning the physiological consequences of chronic acceleration and of studies of selection for acceleration tolerance over many generations. It is shown that acceleration selection is effective in improving chronic acceleration tolerance. However, it is determined that the variable selection procedure employed in developing this acceleration-tolerant line limits the confidence in the quantitative evaluation of the procedure.

  14. 7 CFR 51.3150 - Tolerances.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... grade. 10 percent for nectarines in any lot which fail to meet the requirements of the grade. (ii) U.S... Standards for Grades of Nectarines Tolerances § 51.3150 Tolerances. In order to allow for variations incident to proper grading and handling in each of the following grades, the following tolerances, by count...

  15. Toleration and Recognition: What Should We Teach?

    ERIC Educational Resources Information Center

    Jones, Peter Nigel

    2010-01-01

    Generally we think it good to tolerate and to accord recognition. Yet both are complex phenomena and our teaching must acknowledge and cope with that complexity. We tolerate only what we object to, so our message to students cannot be simply, "promote the good and prevent the bad". Much advocacy of toleration is not what it pretends to be. Nor is…

  16. Perceptions of Tolerance within a Canadian University.

    ERIC Educational Resources Information Center

    Luppicini, Rocci; Sajnani, Nisha

    2003-01-01

    Sought to determine the definition of the word "tolerance" as used within a Canadian university's mission statement. Gauged the climate of tolerance within this university and connected it to sociocultural challenges faced by similar universities. The qualitative case study explored tolerance through the experiences of administrators,…

  17. 7 CFR 993.602 - Maximum tolerances.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Maximum tolerances. 993.602 Section 993.602... CALIFORNIA Grade Regulations § 993.602 Maximum tolerances. In lieu of the provision prescribed in I C of § 993.97 that the tolerance allowances prescribed therein shall be on a weight basis, the...

  18. Enhancement of chronic acceleration tolerance by selection

    NASA Technical Reports Server (NTRS)

    Smith, A. H.

    1982-01-01

    A review is presented of experiments concerning the physiological consequences of chronic acceleration and of studies of selection for acceleration tolerance over many generations. It is shown that acceleration selection is effective in improving chronic acceleration tolerance. However, it is determined that the variable selection procedure employed in developing this acceleration-tolerant line limits the confidence in the quantitative evaluation of the procedure.

  19. Zero Tolerance: Advantages and Disadvantages. Research Brief

    ERIC Educational Resources Information Center

    Walker, Karen

    2009-01-01

    What are the positives and negatives of zero tolerance? What should be considered when examining a school's program? Although there are no definitive definitions of zero tolerance, two commonly used ones are as follows: "Zero tolerance means that a school will automatically and severely punish a student for a variety of infractions" (American Bar…

  20. Statistical computation of tolerance limits

    NASA Technical Reports Server (NTRS)

    Wheeler, J. T.

    1993-01-01

    Based on a new theory, two computer codes were developed specifically to calculate the exact statistical tolerance limits for normal distributions within unknown means and variances for the one-sided and two-sided cases for the tolerance factor, k. The quantity k is defined equivalently in terms of the noncentral t-distribution by the probability equation. Two of the four mathematical methods employ the theory developed for the numerical simulation. Several algorithms for numerically integrating and iteratively root-solving the working equations are written to augment the program simulation. The program codes generate some tables of k's associated with the varying values of the proportion and sample size for each given probability to show accuracy obtained for small sample sizes.

  1. Radiation and temperature tolerant hybrids

    NASA Astrophysics Data System (ADS)

    Palmer, D. W.; Draper, B. L.

    1981-12-01

    The nuclear and space industries require electronics with higher tolerance to radiation than that commercially available. The recently developed 300 C electronics technology based on junction field-effect transistors and thick film hybridization was tested beyond 10 to the 9th power rad (Si) in a cobalt 60 gamma source and 10 to the 16th power neutrons/sq cm in an annular core rector. Circuits and individual components from this technology all survived these total doses although often required annealing at 200 C or 300 C to regain functionality. Radiation tolerance comparisons were made with military radhard CMOS, simplified linear I2L, and JFET technologies. Real time 200 to 300 C annealing should allow circuit functionality to even higher radiation levels.

  2. Radiation and temperature tolerant hybrids

    SciTech Connect

    Palmer, D.W.; Draper, B.L.

    1981-12-01

    The nuclear and space industries require electronics with higher tolerance to radiation than that commercially available. The recently developed 300/sup 0/C electronics technology based on junction field-effect transistors and thick film hybridization was tested beyond 10/sup 9/ rad (Si) in a cobalt 60 gamma source and 10/sup 16/ neutrons/cm/sup 2/ in an annular core reactor. Circuits and individual components from this technology all survived these total doses although often required annealing at 200/sup 0/C or 300/sup 0/C to regain functionality. Radiation tolerance comparisons were made with military radhard CMOS, simplified linear I/sup 2/L, and JFET technologies. Real time 200 to 300/sup 0/C annealing should allow circuit functionality to even higher radiation levels.

  3. Some species tolerate ocean acidification

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2011-12-01

    Increasing carbon dioxide levels lead to rising ocean acidity, which can harm corals and many other species of ocean life. Acidification causes calcium carbonate, which corals usually need to build skeletons, to dissolve. “Every day, ocean acidification is taking up the weight of 6 million midsize cars' worth of carbon, said Nina Keul, a graduate student at the Alfred Wegener Institute for Polar and Marine Research in Germany during a 7 December press conference at the AGU Fall Meeting. Somewhat surprising, though, is that some species are more tolerant of acidic conditions than scientists had expected. For instance, Keul exposed a species of foraminifera, Ammonia tepida, to seawater with varying acidity and varying carbonate ion concentrations. Previous studies had found that foraminifera growth declined with decreasing carbonate levels, but Keul's foraminifera continued to grow in the acidic conditions. She said that the mechanism that allows this species to tolerate the low carbonate conditions is as yet unknown.

  4. Fault-tolerant quantum computation with asymmetric Bacon-Shor codes

    NASA Astrophysics Data System (ADS)

    Brooks, Peter; Preskill, John

    2013-03-01

    We develop a scheme for fault-tolerant quantum computation based on asymmetric Bacon-Shor codes, which works effectively against highly biased noise dominated by dephasing. We find the optimal Bacon-Shor block size as a function of the noise strength and the noise bias, and estimate the logical error rate and overhead cost achieved by this optimal code. Our fault-tolerant gadgets, based on gate teleportation, are well suited for hardware platforms with geometrically local gates in two dimensions.

  5. Behavioral Tolerance to Anticholinergic Agents.

    DTIC Science & Technology

    negative reinforcement (avoidance of brief electric shocks). Each procedure was designed to allow within-subject determination of drug effects. In the...maintained by negative reinforcement ; c) eating of the food pellets used as positive reinforcers was suppressed by atropine, sometimes for more than a...also resulted in decreased responding. Evidence of antagonism between atropine and physostigmine was observed for behavior maintained alternatly by positive and negative reinforcement . Keywords: Tolerances(physiology);

  6. Historical overview of immunological tolerance.

    PubMed

    Schwartz, Ronald H

    2012-04-01

    A fundamental property of the immune system is its ability to mediate self-defense with a minimal amount of collateral damage to the host. The system uses several different mechanisms to achieve this goal, which is collectively referred to as the "process of immunological tolerance." This article provides an introductory historical overview to these various mechanisms, which are discussed in greater detail throughout this collection, and then briefly describes what happens when this process fails, a state referred to as "autoimmunity."

  7. Fault tolerant control of spacecraft

    NASA Astrophysics Data System (ADS)

    Godard

    Autonomous multiple spacecraft formation flying space missions demand the development of reliable control systems to ensure rapid, accurate, and effective response to various attitude and formation reconfiguration commands. Keeping in mind the complexities involved in the technology development to enable spacecraft formation flying, this thesis presents the development and validation of a fault tolerant control algorithm that augments the AOCS on-board a spacecraft to ensure that these challenging formation flying missions will fly successfully. Taking inspiration from the existing theory of nonlinear control, a fault-tolerant control system for the RyePicoSat missions is designed to cope with actuator faults whilst maintaining the desirable degree of overall stability and performance. Autonomous fault tolerant adaptive control scheme for spacecraft equipped with redundant actuators and robust control of spacecraft in underactuated configuration, represent the two central themes of this thesis. The developed algorithms are validated using a hardware-in-the-loop simulation. A reaction wheel testbed is used to validate the proposed fault tolerant attitude control scheme. A spacecraft formation flying experimental testbed is used to verify the performance of the proposed robust control scheme for underactuated spacecraft configurations. The proposed underactuated formation flying concept leads to more than 60% savings in fuel consumption when compared to a fully actuated spacecraft formation configuration. We also developed a novel attitude control methodology that requires only a single thruster to stabilize three axis attitude and angular velocity components of a spacecraft. Numerical simulations and hardware-in-the-loop experimental results along with rigorous analytical stability analysis shows that the proposed methodology will greatly enhance the reliability of the spacecraft, while allowing for potentially significant overall mission cost reduction.

  8. Carisoprodol Tolerance and Precipitated Withdrawal

    PubMed Central

    Gatch, Michael B.; Nguyen, Jacques D.; Carbonaro, Theresa; Forster, Michael J.

    2011-01-01

    Aims Carisoprodol is a muscle relaxant that acts at the GABAA receptor. Concerns about the abuse liability of carisoprodol are increasing, but evidence that carisoprodol produces tolerance and a significant withdrawal syndrome has yet to be established. The purpose of the current study was to determine if repeated administration of carisoprodol produces tolerance and withdrawal signs in a mouse model. Methods Carisoprodol (0, 100, 200, 300, or 500 mg/kg bid, i.p.) was administered to Swiss-Webster mice for 4 days and loss-of-righting reflex was measured 20 to 30 minutes following each administration. On the fourth day, bemegride (20 mg/kg), flumazenil (20 mg/kg), or vehicle was administered following carisoprodol and withdrawal signs were measured. Separate groups of mice receiving the same treatment regimen and dose range were tested for spontaneous withdrawal at 6, 12 and 24 hr after the last dose of carisoprodol. Results The righting reflex was dose-dependently impaired following the first administration of carisoprodol. A 75 to 100% decrease in the magnitude of the impairment occurred over the four days of exposure, indicating the development of tolerance to the carisoprodol-elicited loss-of-righting reflex. Withdrawal signs were not observed within 24 hours following spontaneous withdrawal; however, bemegride and flumazenil each precipitated withdrawal within 15 to 30 min of administration. Conclusions Carisoprodol treatment resulted in tolerance and antagonist-precipitated withdrawal, suggesting it may have an addiction potential similar to that of other long-acting benzodiazepine or barbiturate compounds. PMID:22055010

  9. Fault Tolerance of Neural Networks

    DTIC Science & Technology

    1994-07-01

    Systematic Ap - proach, Proc. Government Microcircuit Application Conf. (GOMAC), San Diego, Nov. 1986. [10] D.E.Goldberg, Genetic Algorithms in Search...s l m n ttempt to develop fault tolerant neural networks. The lows. Given a well-trained network, we first eliminate temp todevlopfaut tlernt eurl ...both ap - proaches, and this resulted in very slight improve- ments over the addition/deletion procedure. 103 Fisher’s Iris data in average case Fisher’s

  10. Modelling Accident Tolerant Fuel Concepts

    SciTech Connect

    Hales, Jason Dean; Gamble, Kyle Allan Lawrence

    2016-05-01

    The catastrophic events that occurred at the Fukushima-Daiichi nuclear power plant in 2011 have led to widespread interest in research of alternative fuels and claddings that are proposed to be accident tolerant. The United States Department of Energy (DOE) through its Nuclear Energy Advanced Modeling and Simulation (NEAMS) program has funded an Accident Tolerant Fuel (ATF) High Impact Problem (HIP). The ATF HIP is a three-year project to perform research on two accident tolerant concepts. The final outcome of the ATF HIP will be an in-depth report to the DOE Advanced Fuels Campaign (AFC) giving a recommendation on whether either of the two concepts should be included in their lead test assembly scheduled for placement into a commercial reactor in 2022. The two ATF concepts under investigation in the HIP are uranium silicide fuel and iron-chromium-aluminum (FeCrAl) alloy cladding. Utilizing the expertise of three national laboratory participants (Idaho National Laboratory, Los Alamos National Laboratory, and Argonne National Laboratory), a comprehensive multiscale approach to modeling is being used that includes atomistic modeling, molecular dynamics, rate theory, phase-field, and fuel performance simulations. Model development and fuel performance analysis are critical since a full suite of experimental studies will not be complete before AFC must prioritize concepts for focused development. In this paper, we present simulations of the two proposed accident tolerance fuel systems: U3Si2 fuel with Zircaloy-4 cladding, and UO2 fuel with FeCrAl cladding. Sensitivity analyses are completed using Sandia National Laboratories’ Dakota software to determine which input parameters (e.g., fuel specific heat) have the greatest influence on the output metrics of interest (e.g., fuel centerline temperature). We also outline the multiscale modelling approach being employed. Considerable additional work is required prior to preparing the recommendation report for the Advanced

  11. Fault Tolerant Frequent Pattern Mining

    SciTech Connect

    Shohdy, Sameh; Vishnu, Abhinav; Agrawal, Gagan

    2016-12-19

    FP-Growth algorithm is a Frequent Pattern Mining (FPM) algorithm that has been extensively used to study correlations and patterns in large scale datasets. While several researchers have designed distributed memory FP-Growth algorithms, it is pivotal to consider fault tolerant FP-Growth, which can address the increasing fault rates in large scale systems. In this work, we propose a novel parallel, algorithm-level fault-tolerant FP-Growth algorithm. We leverage algorithmic properties and MPI advanced features to guarantee an O(1) space complexity, achieved by using the dataset memory space itself for checkpointing. We also propose a recovery algorithm that can use in-memory and disk-based checkpointing, though in many cases the recovery can be completed without any disk access, and incurring no memory overhead for checkpointing. We evaluate our FT algorithm on a large scale InfiniBand cluster with several large datasets using up to 2K cores. Our evaluation demonstrates excellent efficiency for checkpointing and recovery in comparison to the disk-based approach. We have also observed 20x average speed-up in comparison to Spark, establishing that a well designed algorithm can easily outperform a solution based on a general fault-tolerant programming model.

  12. Tolerance of Snakes to Hypergravity

    NASA Technical Reports Server (NTRS)

    Lillywhite, H. B.; Ballard, R. E.; Hargens, A. R.

    1994-01-01

    Sensitivity of carotid blood flow to +Gz (head-to-tail) acceleration was studied in six species of snakes hypothesized to show varied adaptive cardiovascular responses to gravity. Blood flow in the proximal carotid artery was measured in 15 snakes before, during and following stepwise increments of +0.25Gz force produced on a 2.4 m diameter centrifuge. During centrifugation each snake was confined to a straight position within an individually- fitted acrylic tube with the head facing the center of rotation. We measured the centrifugal force at the tail of the snake in order to quantify the maximum intensity of force gradient promoting antero-posterior pooling of blood. Tolerance to increased gravity was quantified as the acceleration force at which carotid blood flow ceased. This parameter varied according to the gravitational adaptation of species defined by their ecology and behavior. At the extremes, carotid blood flow decreased in response to increasing gravity and approached zero near +1Gz in aquatic and ground-dwelling species, whereas in climbing species carotid flow was maintained at forces in excess of +2Gz. Surprisingly, tolerant (arboreal) species withstood hypergravic forces of +2 to +3 G. for periods up to 1 h without cessation of carotid blood flow or apparent loss of consciousness. Data suggest that relatively tight skin of the tolerant species provides a natural antigravity suit which is of prime importance in counteracting Gz stress on blood circulation.

  13. Extreme flooding tolerance in Rorippa.

    PubMed

    Akman, Melis; Bhikharie, Amit; Mustroph, Angelika; Sasidharan, Rashmi

    2014-01-01

    Low oxygen stress imposed by floods creates a strong selection force shaping plant ecosystems in flood-prone areas. Plants inhabiting these environments adopt various adaptations and survival strategies to cope with increasing water depths. Two Rorippa species, R. sylvestris and R. amphibia that grow in naturally flooded areas, have high submergence tolerance achieved by the so-called quiescence and escape strategies, respectively. In order to dissect the molecular mechanisms involved in these strategies, we investigated submergence-induced changes in gene expression in flooded roots of Rorippa species. There was a higher induction of glycolysis and fermentation genes and faster carbohydrate reduction in R. amphibia, indicating a higher demand for energy potentially leading to faster mortality by starvation. Moreover, R. sylvestris showed induction of genes improving submergence tolerance, potentially enhancing survival in prolonged floods. Additionally, we compared transcript profiles of these 2 tolerant species to relatively intolerant Arabidopsis and found that only Rorippa species induced various inorganic pyrophosphate dependent genes, alternatives to ATP demanding pathways, thereby conserving energy, and potentially explaining the difference in flooding survival between Rorippa and Arabidopsis.

  14. Radiation tolerance in water bears.

    NASA Astrophysics Data System (ADS)

    Horikawa, D. D.; Sakashita, T.; Katagiri, C.; Watanabe, M.; Nakahara, Y.; Okuda, T.; Hamada, N.; Wada, S.; Funayama, T.; Kobayashi, Y.

    Tardigrades water bears are tiny invertebrates forming a phylum and inhabit various environments on the earth Terrestrial tardigrades enter a form called as anhydrobiosis when the surrounding water disappears Anhyydrobiosis is defined as an ametabolic dry state and followed by recovering their activity when rehydrated Anhydrobiotic tardigrades show incredible tolerance to a variety of extreme environmental conditions such as temperatures -273 r C to 151 r C vacuum high pressure 600 MPa and chemicals that include alcohols and methyl bromide In these views there have been some discussions about their potential for surviving outer space In the present study we demonstrated the survival limit not merely against gamma-rays but against heavy ions in the tardigrade Milnesium tardigradum in order to evaluate the effects of radiations on them The animals were exposure to 500 to 7000 Gy of gamma-rays or 500 to 8000 Gy of heavy ions 4 He in their hydrated or anhydrobiotic state The results showed that both of hydrated and anhydrobiotic animals have high radio-tolerance median lethal dose LD50 48 h of gamma-rays or heavy ions in M tardigradum was more than 4000 Gy indicating that this species is categorized into the most radio-tolerant animals We suggest that tardigrades will be suitable model animals for extremophilic multicellular organisms and may provide a survival strategy in extraterrestrial environments

  15. Liver transplant center risk tolerance.

    PubMed

    Johnson, Scott R; Karp, Seth J; Curry, Michael P; Barugel, Martin; Rodrigue, James R; Mandelbrot, Didier A; Rogers, Christin P; Hanto, Douglas W

    2012-01-01

    Recent changes in Center for Medicare & Medicaid Services (CMS) condition for participation, using benchmark volume/outcomes requirements for certification, have been implemented. Consequently, the ability of a transplant center to assess its risk tolerance is important in successful management. An analysis of SRTR data was performed to determine donor/recipient risk factors for graft loss or patient death in the first year. Each transplant performed was then assigned a prospective relative risk (RR) of failure. Using a Monte-Carlo simulation, transplants were selected at random that met the centers' acceptable risk tolerance. Transplant center volume was fixed and its risk tolerance was adjusted to determine the impact on outcomes. The model was run 1000 times on centers with varying volume. The modeling demonstrates that centers with smaller annual volumes must use a more risk taking strategy than larger volume centers to avoid being flagged for CMS volume requirements. The modeling also demonstrates optimal risk taking strategies for centers based upon volume to minimize the probability of being flagged for not meeting volume or outcomes benchmarks. Small volume centers must perform higher risk transplants to meet current CMS requirements and are at risk for adverse action secondary to chance alone.

  16. Extreme flooding tolerance in Rorippa

    PubMed Central

    Akman, Melis; Bhikharie, Amit V; Mustroph, Angelika; Sasidharan, Rashmi

    2014-01-01

    Low oxygen stress imposed by floods creates a strong selection force shaping plant ecosystems in flood-prone areas. Plants inhabiting these environments adopt various adaptations and survival strategies to cope with increasing water depths. Two Rorippa species, R. sylvestris and R. amphibia that grow in naturally flooded areas, have high submergence tolerance achieved by the so-called quiescence and escape strategies, respectively. In order to dissect the molecular mechanisms involved in these strategies, we investigated submergence-induced changes in gene expression in flooded roots of Rorippa species. There was a higher induction of glycolysis and fermentation genes and faster carbohydrate reduction in R. amphibia, indicating a higher demand for energy potentially leading to faster mortality by starvation. Moreover, R. sylvestris showed induction of genes improving submergence tolerance, potentially enhancing survival in prolonged floods. Additionally, we compared transcript profiles of these 2 tolerant species to relatively intolerant Arabidopsis and found that only Rorippa species induced various inorganic pyrophosphate dependent genes, alternatives to ATP demanding pathways, thereby conserving energy, and potentially explaining the difference in flooding survival between Rorippa and Arabidopsis. PMID:24525961

  17. Natural selection on individual variation in tolerance of gastrointestinal nematode infection.

    PubMed

    Hayward, Adam D; Nussey, Daniel H; Wilson, Alastair J; Berenos, Camillo; Pilkington, Jill G; Watt, Kathryn A; Pemberton, Josephine M; Graham, Andrea L

    2014-07-01

    Hosts may mitigate the impact of parasites by two broad strategies: resistance, which limits parasite burden, and tolerance, which limits the fitness or health cost of increasing parasite burden. The degree and causes of variation in both resistance and tolerance are expected to influence host-parasite evolutionary and epidemiological dynamics and inform disease management, yet very little empirical work has addressed tolerance in wild vertebrates. Here, we applied random regression models to longitudinal data from an unmanaged population of Soay sheep to estimate individual tolerance, defined as the rate of decline in body weight with increasing burden of highly prevalent gastrointestinal nematode parasites. On average, individuals lost weight as parasite burden increased, but whereas some lost weight slowly as burden increased (exhibiting high tolerance), other individuals lost weight significantly more rapidly (exhibiting low tolerance). We then investigated associations between tolerance and fitness using selection gradients that accounted for selection on correlated traits, including body weight. We found evidence for positive phenotypic selection on tolerance: on average, individuals who lost weight more slowly with increasing parasite burden had higher lifetime breeding success. This variation did not have an additive genetic basis. These results reveal that selection on tolerance operates under natural conditions. They also support theoretical predictions for the erosion of additive genetic variance of traits under strong directional selection and fixation of genes conferring tolerance. Our findings provide the first evidence of selection on individual tolerance of infection in animals and suggest practical applications in animal and human disease management in the face of highly prevalent parasites.

  18. Natural Selection on Individual Variation in Tolerance of Gastrointestinal Nematode Infection

    PubMed Central

    Hayward, Adam D.; Nussey, Daniel H.; Wilson, Alastair J.; Berenos, Camillo; Pilkington, Jill G.; Watt, Kathryn A.; Pemberton, Josephine M.; Graham, Andrea L.

    2014-01-01

    Hosts may mitigate the impact of parasites by two broad strategies: resistance, which limits parasite burden, and tolerance, which limits the fitness or health cost of increasing parasite burden. The degree and causes of variation in both resistance and tolerance are expected to influence host–parasite evolutionary and epidemiological dynamics and inform disease management, yet very little empirical work has addressed tolerance in wild vertebrates. Here, we applied random regression models to longitudinal data from an unmanaged population of Soay sheep to estimate individual tolerance, defined as the rate of decline in body weight with increasing burden of highly prevalent gastrointestinal nematode parasites. On average, individuals lost weight as parasite burden increased, but whereas some lost weight slowly as burden increased (exhibiting high tolerance), other individuals lost weight significantly more rapidly (exhibiting low tolerance). We then investigated associations between tolerance and fitness using selection gradients that accounted for selection on correlated traits, including body weight. We found evidence for positive phenotypic selection on tolerance: on average, individuals who lost weight more slowly with increasing parasite burden had higher lifetime breeding success. This variation did not have an additive genetic basis. These results reveal that selection on tolerance operates under natural conditions. They also support theoretical predictions for the erosion of additive genetic variance of traits under strong directional selection and fixation of genes conferring tolerance. Our findings provide the first evidence of selection on individual tolerance of infection in animals and suggest practical applications in animal and human disease management in the face of highly prevalent parasites. PMID:25072883

  19. Tetracycline tolerance mediated by gene amplification in Bacillus subtilis.

    PubMed

    Wannarat, Wannasiri; Motoyama, Shiori; Masuda, Kenta; Kawamura, Fujio; Inaoka, Takashi

    2014-11-01

    Bacillus subtilis can acquire a higher tolerance to tetracycline by increasing the gene dosage of its resistance gene tetB. In this study, we estimated the multiplication effect of tetB on tetracycline tolerance. Cells harbouring multiple copies of tetB were found to comprise approximately 30 % of the total tetracycline-resistant cell population when selected on medium containing 10 µg tetracycline ml(-1). Disruption of recA resulted in a significant decrease in the frequency of tetB amplification. Although four direct repeats exist around tetB, the majority of tetB amplicons were found to be flanked by non-homologous sequences, indicating that the initial duplication of tetB can occur largely through RecA-independent recombination. The correlation between the tetB copy number and the MIC values for tetracycline indicated that more than three copies of tetB were required for tolerance to 10 µg tetracycline ml(-1). Thus, the RecA-dependent expansion step appears to be necessary for developing significant tetracycline tolerance mediated by tetB amplification. © 2014 The Authors.

  20. Vertebrate defense against parasites: Interactions between avoidance, resistance, and tolerance.

    PubMed

    Klemme, Ines; Karvonen, Anssi

    2017-01-01

    Hosts can utilize different types of defense against the effects of parasitism, including avoidance, resistance, and tolerance. Typically, there is tremendous heterogeneity among hosts in these defense mechanisms that may be rooted in the costs associated with defense and lead to trade-offs with other life-history traits. Trade-offs may also exist between the defense mechanisms, but the relationships between avoidance, resistance, and tolerance have rarely been studied. Here, we assessed these three defense traits under common garden conditions in a natural host-parasite system, the trematode eye-fluke Diplostomum pseudospathaceum and its second intermediate fish host. We looked at host individuals originating from four genetically distinct populations of two closely related salmonid species (Atlantic salmon, Salmo salar and sea trout, Salmo trutta trutta) to estimate the magnitude of variation in these defense traits and the relationships among them. We show species-specific variation in resistance and tolerance and population-specific variation in resistance. Further, we demonstrate evidence for a trade-off between resistance and tolerance. Our results suggest that the variation in host defense can at least partly result from a compromise between different interacting defense traits, the relative importance of which is likely to be shaped by environmental components. Overall, this study emphasizes the importance of considering different components of the host defense system when making predictions on the outcome of host-parasite interactions.

  1. Evolutionary potential of upper thermal tolerance: biogeographic patterns and expectations under climate change.

    PubMed

    Diamond, Sarah E

    2017-02-01

    How will organisms respond to climate change? The rapid changes in global climate are expected to impose strong directional selection on fitness-related traits. A major open question then is the potential for adaptive evolutionary change under these shifting climates. At the most basic level, evolutionary change requires the presence of heritable variation and natural selection. Because organismal tolerances of high temperature place an upper bound on responding to temperature change, there has been a surge of research effort on the evolutionary potential of upper thermal tolerance traits. Here, I review the available evidence on heritable variation in upper thermal tolerance traits, adopting a biogeographic perspective to understand how heritability of tolerance varies across space. Specifically, I use meta-analytical models to explore the relationship between upper thermal tolerance heritability and environmental variability in temperature. I also explore how variation in the methods used to obtain these thermal tolerance heritabilities influences the estimation of heritable variation in tolerance. I conclude by discussing the implications of a positive relationship between thermal tolerance heritability and environmental variability in temperature and how this might influence responses to future changes in climate. © 2016 New York Academy of Sciences.

  2. Issues on human acceleration tolerance after long-duration space flights

    NASA Technical Reports Server (NTRS)

    Kumar, K. Vasantha; Norfleet, William T.

    1992-01-01

    This report reviewed the literature on human tolerance to acceleration at 1 G and changes in tolerance after exposure to hypogravic fields. It was found that human tolerance decreased after exposure to hypokinetic and hypogravic fields, but the magnitude of such reduction ranged from 0 to 30 percent for plateau G forces and 30 to 70 percent for time tolerance on sustained G forces. A logistic regression model of the probability of individuals with 25 percent reduction in +Gz tolerance after 1 to 41 days of hypogravic exposures was constructed. The estimated values from the model showed a good correlation with the observed data. A brief review of the need for in-flight centrifuge during long-duration missions was also presented. Review of the available data showed that the use of countermeasures (such as anti-G suits, periodic acceleration, and exercise) reduced the decrement in acceleration tolerance after long-duration space flights. Areas of further research include quantification of the effect of countermeasures on tolerance, and methods to augment tolerance during and after exposures to hypogravic fields. Such data are essential for planning long-duration human missions.

  3. Pillar III--optimisation of anaemia tolerance.

    PubMed

    Meier, Jens; Gombotz, Hans

    2013-03-01

    In the case of acute bleeding, the use of the anaemia tolerance of a patient enables the physician to either avoid blood transfusions or delay them after bleeding has ceased. This concept is the cornerstone of the third pillar of modern patient blood management programmes. Its efficacy depends on the degree of utilisation of anaemia tolerance, which is not constant but depends on the compensatory capacity of the individual patient in a given situation. Fortunately, the specifications of anaemia tolerance can be influenced by the anaesthesiologist. This article presents the concept of anaemia tolerance and highlights the options for how anaemia tolerance can be optimised in the pre-, intra-, and postoperative periods.

  4. Prospects and strategies for clinical tolerance.

    PubMed

    Monaco, A P

    2004-01-01

    The morbidity and mortality associated with chronic immunosuppression provide a strong motivation for development of clinical tolerance. This paper discusses the definition(s) of clinical (operational) tolerance, the role of chimerism in experimental and clinical tolerance, and the special role of bone marrow in tolerance induction. The states of microchimerism and macrochimerism are defined and related to certain clinical observations in solid organ transplantation. Current clinical strategies already being tested in the clinic are briefly reviewed. Certain principles for induction of clinical (operational) tolerance are elaborated.

  5. IRON-TOLERANT CYANOBACTERIA: IMPLICATIONS FOR ASTROBIOLOGY

    NASA Technical Reports Server (NTRS)

    Brown, Igor I.; Allen, Carlton C.; Mummey, Daniel L.; Sarkisova, Svetlana A.; McKay, David S.

    2006-01-01

    The review is dedicated to the new group of extremophiles - iron tolerant cyanobacteria. The authors have analyzed earlier published articles about the ecology of iron tolerant cyanobacteria and their diversity. It was concluded that contemporary iron depositing hot springs might be considered as relative analogs of Precambrian environment. The authors have concluded that the diversity of iron-tolerant cyanobacteria is understudied. The authors also analyzed published data about the physiological peculiarities of iron tolerant cyanobacteria. They made the conclusion that iron tolerant cyanobacteria may oxidize reduced iron through the photosystem of cyanobacteria. The involvement of both Reaction Centers 1 and 2 is also discussed. The conclusion that iron tolerant protocyanobacteria could be involved in banded iron formations generation is also proposed. The possible mechanism of the transition from an oxygenic photosynthesis to an oxygenic one is also discussed. In the final part of the review the authors consider the possible implications of iron tolerant cyanobacteria for astrobiology.

  6. Estimation Destinations.

    ERIC Educational Resources Information Center

    Threewit, Fran

    This book leads students through a journey of hands-on investigations of skill-based estimation. The 30 lessons in the book are grouped into four units: Holding Hands, The Real Scoop, Container Calculations, and Estimeasurements. In each unit children work with unique, real materials intended to build an awareness of number, quantity, and…

  7. Computational Estimation

    ERIC Educational Resources Information Center

    Fung, Maria G.; Latulippe, Christine L.

    2010-01-01

    Elementary school teachers are responsible for constructing the foundation of number sense in youngsters, and so it is recommended that teacher-training programs include an emphasis on number sense to ensure the development of dynamic, productive computation and estimation skills in students. To better prepare preservice elementary school teachers…

  8. Bayesian reconstruction of ancestral expression of the LEA gene families reveals propagule-derived desiccation tolerance in resurrection plants.

    PubMed

    Fisher, Kirsten M

    2008-04-01

    Desiccation tolerance is a complex trait that is broadly but infrequently present throughout the evolutionary tree of life. Desiccation tolerance has played a significant role in land plant evolution, in both the vegetative and reproductive life history stages. In the land plants, the late embryogenesis abundant (LEA) gene families are involved in both abiotic stress tolerance and the development of reproductive propagules. They are also a major component of vegetative desiccation tolerance. Phylogenies were estimated for four families of LEA genes from Arabidopsis, Physcomitrella, and the desiccation tolerant plants Tortula ruralis, Craterostigma plantagineum, and Xerophyta humilis. Microarray expression data from Arabidopsis and a subset of the Physcomitrella LEAs were used to estimate ancestral expression patterns in the LEA families and to evaluate alternative hypotheses for the origins of vegetative desiccation tolerance in the flowering plants. The results contradict the idea that vegetative desiccation tolerance in the resurrection angiosperms Craterostigma and Xerophyta arose through the co-option of genes exclusively related to stress tolerance, and support the propagule-derived origin of vegetative desiccation tolerance in the resurrection plants.

  9. Damage Tolerance: Assessment Handbook. Volume 2: Airframe Damage Tolerance Evaluation

    DTIC Science & Technology

    1993-10-01

    Airframe Damage Tolerance Evaluation NJ 084u5 DTIC FLE 15 1994 Research and Special Programs Administration John A. Volpe National Transportation Systems...permission of John Wiley and Sons, New York, N.Y.] (4-5] CORRODED END Magnes;um Magnesium alloys Zinc Galvanized steel or galvanized wrought iron Aluminum...Reprinted from M M. Ratwani and D.P. Wilhem , iDeelopment andEvaluation of Methods of Plane Strain Fractuire Analysis, Northrop Corporation, AFFDL-TR-73-42

  10. Temperature-stress resistance and tolerance along a latitudinal cline in North American Arabidopsis lyrata.

    PubMed

    Wos, Guillaume; Willi, Yvonne

    2015-01-01

    The study of latitudinal gradients can yield important insights into adaptation to temperature stress. Two strategies are available: resistance by limiting damage, or tolerance by reducing the fitness consequences of damage. Here we studied latitudinal variation in resistance and tolerance to frost and heat and tested the prediction of a trade-off between the two strategies and their costliness. We raised plants of replicate maternal seed families from eight populations of North American Arabidopsis lyrata collected along a latitudinal gradient in climate chambers and exposed them repeatedly to either frost or heat stress, while a set of control plants grew under standard conditions. When control plants reached maximum rosette size, leaf samples were exposed to frost and heat stress, and electrolyte leakage (PEL) was measured and treated as an estimate of resistance. Difference in maximum rosette size between stressed and control plants was used as an estimate of tolerance. Northern populations were more frost resistant, and less heat resistant and less heat tolerant, but-unexpectedly-they were also less frost tolerant. Negative genetic correlations between resistance and tolerance to the same and different thermal stress were generally not significant, indicating only weak trade-offs. However, tolerance to frost was consistently accompanied by small size under control conditions, which may explain the non-adaptive latitudinal pattern for frost tolerance. Our results suggest that adaptation to frost and heat is not constrained by trade-offs between them. But the cost of frost tolerance in terms of plant size reduction may be important for the limits of species distributions and climate niches.

  11. Temperature-Stress Resistance and Tolerance along a Latitudinal Cline in North American Arabidopsis lyrata

    PubMed Central

    Wos, Guillaume; Willi, Yvonne

    2015-01-01

    The study of latitudinal gradients can yield important insights into adaptation to temperature stress. Two strategies are available: resistance by limiting damage, or tolerance by reducing the fitness consequences of damage. Here we studied latitudinal variation in resistance and tolerance to frost and heat and tested the prediction of a trade-off between the two strategies and their costliness. We raised plants of replicate maternal seed families from eight populations of North American Arabidopsis lyrata collected along a latitudinal gradient in climate chambers and exposed them repeatedly to either frost or heat stress, while a set of control plants grew under standard conditions. When control plants reached maximum rosette size, leaf samples were exposed to frost and heat stress, and electrolyte leakage (PEL) was measured and treated as an estimate of resistance. Difference in maximum rosette size between stressed and control plants was used as an estimate of tolerance. Northern populations were more frost resistant, and less heat resistant and less heat tolerant, but—unexpectedly—they were also less frost tolerant. Negative genetic correlations between resistance and tolerance to the same and different thermal stress were generally not significant, indicating only weak trade-offs. However, tolerance to frost was consistently accompanied by small size under control conditions, which may explain the non-adaptive latitudinal pattern for frost tolerance. Our results suggest that adaptation to frost and heat is not constrained by trade-offs between them. But the cost of frost tolerance in terms of plant size reduction may be important for the limits of species distributions and climate niches. PMID:26110428

  12. [High arsenic-tolerant fungi: their isolation and tolerant ability].

    PubMed

    Su, Shi-ming; Zeng, Xi-bai; Jiang, Xi-liang; Bai, Ling-yu; Li, Lian-fang; Zhang, Yan-rong

    2010-12-01

    A total of thirteen fungal strains with higher arsenic (As)-tolerance ability were isolated from six As-contaminated soil samples collected from the mining areas of Shimen County and Chenz-hou City in Hunan Province. Among the strains isolated, Penicillin janthinellum, Fusarium oxysporum, and Trichoderma asperellum had the highest As-tolerance ability, based on the morphological identification and phylogenetic analysis. Culture experiment showed that on the solid plates with 30,000, 30,000, and 20,000 mg x L(-1) of As, P. janthinellum, F. oxysporum, and T. asperellum had a better colony growth, and after cultured in the liquid medium with 0-50, 0-50, and 0-80 mg x L(-1) of As for 2 days, respectively, the dry mycelia masses of the three strains all increased with increasing As concentration. When the As concentration reached 50, 50, and 80 mg x L(-1), respectively, the fungal biomass of F. oxysporum, T. asperellum, and P. janthinellum increased significantly, compared with CK. High concentration As had no significant effects on the sporalation of the three fungal strains.

  13. The failure-tolerant leader.

    PubMed

    Farson, Richard; Keyes, Ralph

    2002-08-01

    "The fastest way to succeed," IBM's Thomas Watson, Sr., once said, "is to double your failure rate." In recent years, more and more executives have embraced Watson's point of view, coming to understand what innovators have always known: Failure is a prerequisite to invention. But while companies may grasp the value of making mistakes at the level of corporate practices, they have a harder time accepting the idea at the personal level. People are afraid to fail, and corporate culture reinforces that fear. In this article, psychologist and former Harvard Business School professor Richard Farson and coauthor Ralph Keyes discuss how companies can reduce the fear of miscues. What's crucial is the presence of failure-tolerant leaders--executives who, through their words and actions, help employees overcome their anxieties about making mistakes and, in the process, create a culture of intelligent risk-taking that leads to sustained innovation. Such leaders don't just accept productive failure, they promote it. Drawing from their research in business, politics, sports, and science, the authors identify common practices among failure-tolerant leaders. These leaders break down the social and bureaucratic barriers that separate them from their followers. They engage at a personal level with the people they lead. They avoid giving either praise or criticism, preferring to take a nonjudgmental, analytical posture as they interact with staff. They openly admit their own mistakes rather than trying to cover them up or shifting the blame. And they try to root out the destructive competitiveness built into most organizations. Above all else, failure-tolerant leaders push people to see beyond traditional definitions of success and failure. They know that as long as a person views failure as the opposite of success, rather than its complement, he or she will never be able to take the risks necessary for innovation.

  14. Split Immunological Tolerance to Trophoblast

    PubMed Central

    de Mestre, Amanda; Noronha, Leela; Wagner, Bettina; Antczak, Douglas F.

    2010-01-01

    Split immunological tolerance refers to states in which an individual is capable of mounting certain types of immune responses to a particular antigenic challenge, but is tolerant of the same antigen in other compartments of the immune system. This concept is applicable to the immunological relationship between mother and fetus, and particularly relevant in equine pregnancy. In pregnant mares, antibody responses to paternal foreign Major Histocompatibility Complex class I antigens are robust, while anti-paternal cytotoxic T cell responses are diminished compared to those mounted by non-pregnant mares. Here we compared the distribution of the major lymphocyte subsets, the percentage of lymphocytes expressing Interferon Gamma (IFNG) and Interleukin 4 (IL4) and the level of expression of the immunoregulatory transcription factor FOXP3 between pregnant and non-pregnant mares, and between peripheral blood and the endometrium during pregnancy. In a cohort of mares in which peripheral blood lymphocytes were tested during early pregnancy and in the non-pregnant state, there were only slight changes observed during pregnancy. In contrast, comparison of peripheral blood lymphocytes with lymphocytes isolated from the endometrial cups of pregnant mares revealed striking differences in lymphocyte sub-populations. The endometrial cups contained higher numbers of IFNG+ lymphocytes, and lower numbers of lymphocytes expressing IL4. The endometrial cup lymphocytes also had higher numbers of FOXP3+ cells compared to peripheral blood lymphocytes. Taken together, these results strengthen the evidence for a state of split tolerance to trophoblast, and furthermore define sharp differences in immune reactivity during equine pregnancy between peripheral blood lymphocytes and lymphocytes at the maternal-fetal interface. PMID:19876828

  15. Noise tolerant spatiotemporal chaos computing.

    PubMed

    Kia, Behnam; Kia, Sarvenaz; Lindner, John F; Sinha, Sudeshna; Ditto, William L

    2014-12-01

    We introduce and design a noise tolerant chaos computing system based on a coupled map lattice (CML) and the noise reduction capabilities inherent in coupled dynamical systems. The resulting spatiotemporal chaos computing system is more robust to noise than a single map chaos computing system. In this CML based approach to computing, under the coupled dynamics, the local noise from different nodes of the lattice diffuses across the lattice, and it attenuates each other's effects, resulting in a system with less noise content and a more robust chaos computing architecture.

  16. SUMC fault tolerant computer system

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The results of the trade studies are presented. These trades cover: establishing the basic configuration, establishing the CPU/memory configuration, establishing an approach to crosstrapping interfaces, defining the requirements of the redundancy management unit (RMU), establishing a spare plane switching strategy for the fault-tolerant memory (FTM), and identifying the most cost effective way of extending the memory addressing capability beyond the 64 K-bytes (K=1024) of SUMC-II B. The results of the design are compiled in Contract End Item (CEI) Specification for the NASA Standard Spacecraft Computer II (NSSC-II), IBM 7934507. The implementation of the FTM and memory address expansion.

  17. Noise tolerant spatiotemporal chaos computing

    SciTech Connect

    Kia, Behnam; Kia, Sarvenaz; Ditto, William L.; Lindner, John F.; Sinha, Sudeshna

    2014-12-01

    We introduce and design a noise tolerant chaos computing system based on a coupled map lattice (CML) and the noise reduction capabilities inherent in coupled dynamical systems. The resulting spatiotemporal chaos computing system is more robust to noise than a single map chaos computing system. In this CML based approach to computing, under the coupled dynamics, the local noise from different nodes of the lattice diffuses across the lattice, and it attenuates each other's effects, resulting in a system with less noise content and a more robust chaos computing architecture.

  18. Can crops tolerate acid rain

    SciTech Connect

    Kaplan, J.K.

    1989-11-01

    This brief article describes work by scientists at the ARS Air Quality-Plant Growth and Development Laboratory in Raleigh, North Carolina, that indicates little damage to crops as a result of acid rain. In studies with simulated acid rain and 216 exposed varieties of 18 crops, there were no significant injuries nor was there reduced growth in most species. Results of chronic and acute exposures were correlated in sensitive tomato and soybean plants and in tolerant winter wheat and lettuce plants. These results suggest that 1-hour exposures could be used in the future to screen varieties for sensitivity to acid rain.

  19. Tolerance of LSS Plant Component to Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Ushakova, S. A.; Tikhomirov, A. A.

    2002-06-01

    Stability of LSS based on biological regeneration of water, air and food subject to damaging factors is largely dependent on the behavior of the photosynthesizing component represented, mainly, by higher plants. The purpose of this study is to evaluate the tolerance of uneven-aged wheat and radish cenoses to temperature effects different in time and value. Estimation of thermal tolerance of plants demonstrated that exposure for 20 h to the temperature increasing to 45°C brought about irreversible damage both in photosynthetic processes (up to 80% of initial value) and the processes of growth and development. Kinetics of visible photosynthesis during exposure to elevated temperatures can be used to evaluate critical exposure time within the range of which the damage of metabolic processes is reversible. With varying light intensity and air temperature it is possible to find a time period admissible for the plants to stay under adverse conditions without considerable damage of metabolic processes.

  20. Trajectory Stability Modeling And Tolerances in the LCLS

    SciTech Connect

    Wu, J.; Emma, P.; /SLAC

    2007-04-27

    To maintain stable performance of the Linac Coherent Light Source (LCLS) x-ray free-electron laser, one must control the electron trajectory stability through the undulator to a small fraction of the beam size. BPM-based feedback loops running at 120 Hz will be effective in controlling jitter at low frequencies less than a few Hz. On the other hand, linac and injector stability tolerances must be chosen to limit jitter at higher frequencies. In this paper we study possible sources of high frequency jitter, including: (1) steering coil current regulation; (2) quadrupole magnet transverse vibrations; (3) quadrupole current regulation with transverse misalignments; (4) charge variations coupled to jitter through transverse wakefields of misaligned RF structures; and (5) bunch length variations coupled through coherent synchrotron radiation in the bunch compressor chicanes. Based on this study, we set component tolerances and estimate expected trajectory stability in the LCLS.

  1. An integrated study of fault tolerance in computing systems

    SciTech Connect

    Lin, Tein-Hsiang.

    1988-01-01

    A general framework for the design and analysis of distributed fault-tolerant systems is proposed including fault/error occurrence and detection, error propagation, fault location, retry, system reconfiguration, damage assessment, and error recovery. Detection mechanisms are usually assumed to be so perfect that problems within a particular phase of fault tolerance can be studied without considering its interplay with other phases. This dissertation shows that the assumption of imperfect detection mechanisms will greatly influence fault diagnosis, rollback recovery, and checkpointing. Two additional related problems are studied. One is concerned with the use of retry following a fault detection and the other with the optimal placement of checkpoints in a real-time task with or without the perfect detection assumption. A fault-classification scheme is developed for on-line estimation of fault parameters.

  2. Straining GOR tolerance determinations are a measure of G-duration not G-level tolerance.

    PubMed

    Burton, R R

    1999-03-01

    Straining gradual G onset rate (GOR) tolerances are considered by physiologists as a measure of G-level tolerance. Using recently developed G-level and G-duration mathematical models, it was found that straining GOR tolerances may well be a measure of tolerance to G-duration. G-duration tolerance was determined to be limited with the onset of fatigue and not cardiovascular insufficiency. G-level tolerances that were predicted using a mathematical model were higher than determined using straining GOR tolerance measurements of subjects on a centrifuge. Also the G-duration tolerance mathematical model showed that those centrifuge subjects had not expended all of their "energy reserve" during their sustained G exposure most probably because of the onset of fatigue. Even if they were able to use all of their potential energy reserve, their G-duration tolerance would not have allowed them to reach the maximum G-level predicted with the G-level tolerance model. It is therefore concluded that the straining GOR tolerance profile, with G onset rates of 0.1G/s, is not a measure of G-level tolerance, as has been assumed, but is a measure of G-duration tolerance. These findings have significant safety implications world-wide since this straining GOR profile is commonly used as a G-level tolerance fighter-pilot-selection determination; i.e. pilot selection standards for G-level tolerance are not a measure of G-level tolerance. In testing equipment design changes, the proper G tolerance profiles must be used to correctly measure its impact on G tolerance.

  3. Onset of deformation in polonium nuclei

    SciTech Connect

    Younes, W.; Cizewski, J.A.

    1996-12-31

    The authors have been able to reproduce the systematics of the positive-parity states in {sup 192-208}Po within the framework of the Particle-Core Model. The wave-functions of the 2{sup +}{sub 1} states have been extracted using the Quasiparticle Random Phase Approximation. The increase in the collective motion of the lighter isotopes comes from the increased proton-neutron interaction when the neutrons and protons both occupy high-j orbitals.

  4. Sea squirts and immune tolerance.

    PubMed

    De Tomaso, Anthony W

    2009-01-01

    Transplantation specificity and protective immunity occur in both adaptive and innate branches of the vertebrate immune system. Understanding the mechanisms that underlie specificity and self-tolerance of immune function has major significance, from preventing a rejection reaction after transplantation to dissecting the causes of autoimmune disease. The core of vertebrate immunity is the ability to discriminate between highly polymorphic ligands, and this process is also found in allorecognition systems throughout the metazoa. Botryllus schlosseri is a tunicate, the modern-day descendents of the phylum that made the transition between invertebrates and vertebrates. In addition, B. schlosseri undergoes a natural transplantation reaction, which is controlled by a single, highly polymorphic locus called fuhc, reminiscent of major histocompatibility complex (MHC)-based allorecognition. The life-history characteristics of Botryllus make it an excellent model to dissect the functional and developmental mechanisms underlying allorecognition, and have the potential to reveal novel insights into issues from innate recognition strategies to the evolution of genetic polymorphism. In addition, we hypothesize that allorecognition in Botryllus must be based on conserved processes that are fundamental to all immune function: education and tolerance, or the ontogeny and maintenance of specificity.

  5. 210Po and 210Pb Activity Concentrations in Cigarettes Produced in Vietnam and Their Estimated Dose Contribution Due to Smoking

    NASA Astrophysics Data System (ADS)

    Tran, Thuy-Ngan N.; Le, Cong-Hao; Chau, Van-Tao

    Smoking cigarettes contributes significantly to the increase of radiation in human body because 210Po and 210Pb exist relatively high in tobacco leaves. Therefore, these two radioisotopes in eighteen of the most frequently sold cigarette brands produced in Vietnam were examined in this study. 210Po was determined by alpha spectroscopy using a passivated implanted planar silicon (PIPS) detector after a procedure including radiochemical separation and spontaneous deposition of polonium on a copper disc (the deposition efficiency of 210Po on a copper disc was approximately 94%). Sequentially, 210Pb was determined through the ingrowth of 210Po after storing the sample solutions for approximately six months. The activity concentrations of 210Po in cigarettes ranged from 13.8 to 82.6 mBq/cigarette (the mean value was 26.4 mBq/cigarette) and the activity concentrations of 210Pb in cigarettes ranged from 13.9 to 78.8 mBq/cigarette (the mean value was 25.8 mBq/cigarette). The annual committed effective dose for smokers who smoke one pack per day was also estimated to be 295.4 µSv/year (223.0 µSv/year and 72.4 µSv/year from 210Po and 210Pb, respectively). These indicated that smoking increased the risk of developing lung cancer was approximately 60 times greater for smokers than for non-smokers.

  6. Antibiotic tolerance facilitates the evolution of resistance.

    PubMed

    Levin-Reisman, Irit; Ronin, Irine; Gefen, Orit; Braniss, Ilan; Shoresh, Noam; Balaban, Nathalie Q

    2017-02-24

    Controlled experimental evolution during antibiotic treatment can help to explain the processes leading to antibiotic resistance in bacteria. Recently, intermittent antibiotic exposures have been shown to lead rapidly to the evolution of tolerance-that is, the ability to survive under treatment without developing resistance. However, whether tolerance delays or promotes the eventual emergence of resistance is unclear. Here we used in vitro evolution experiments to explore this question. We found that in all cases, tolerance preceded resistance. A mathematical population-genetics model showed how tolerance boosts the chances for resistance mutations to spread in the population. Thus, tolerance mutations pave the way for the rapid subsequent evolution of resistance. Preventing the evolution of tolerance may offer a new strategy for delaying the emergence of resistance.

  7. The Social Psychology of Intergroup Toleration.

    PubMed

    Verkuyten, Maykel; Yogeeswaran, Kumar

    2017-02-01

    The global increase in cultural and religious diversity has led to calls for toleration of group differences to achieve intergroup harmony. Although much social-psychological research has examined the nature of stereotyping, prejudice, and discrimination, and its impact on targets of these biases, little research has examined the nature and impact of toleration for intergroup relations. Toleration does not require that people give up their objections to out-group norms and practices but rather mutual accommodation. Integrating research from various social sciences, we explore the nature of intergroup tolerance including its three components-objection, acceptance, and rejection-while drawing out its implications for future social-psychological research. We then explore some psychological consequences to social groups that are the object of toleration. By doing so, we consider the complex ways in which intergroup tolerance impacts both majority and minority groups and the dynamic interplay of both in pluralistic societies.

  8. The fault-tolerant multiprocessor computer

    NASA Technical Reports Server (NTRS)

    Smith, T. B., III (Editor); Lala, J. H. (Editor); Goldberg, J. (Editor); Kautz, W. H. (Editor); Melliar-Smith, P. M. (Editor); Green, M. W. (Editor); Levitt, K. N. (Editor); Schwartz, R. L. (Editor); Weinstock, C. B. (Editor); Palumbo, D. L. (Editor)

    1986-01-01

    The development and evaluation of fault-tolerant computer architectures and software-implemented fault tolerance (SIFT) for use in advanced NASA vehicles and potentially in flight-control systems are described in a collection of previously published reports prepared for NASA. Topics addressed include the principles of fault-tolerant multiprocessor (FTMP) operation; processor and slave regional designs; FTMP executive, facilities, acceptance-test/diagnostic, applications, and support software; FTM reliability and availability models; SIFT hardware design; and SIFT validation and verification.

  9. Model-Based Fault Tolerant Control

    NASA Technical Reports Server (NTRS)

    Kumar, Aditya; Viassolo, Daniel

    2008-01-01

    The Model Based Fault Tolerant Control (MBFTC) task was conducted under the NASA Aviation Safety and Security Program. The goal of MBFTC is to develop and demonstrate real-time strategies to diagnose and accommodate anomalous aircraft engine events such as sensor faults, actuator faults, or turbine gas-path component damage that can lead to in-flight shutdowns, aborted take offs, asymmetric thrust/loss of thrust control, or engine surge/stall events. A suite of model-based fault detection algorithms were developed and evaluated. Based on the performance and maturity of the developed algorithms two approaches were selected for further analysis: (i) multiple-hypothesis testing, and (ii) neural networks; both used residuals from an Extended Kalman Filter to detect the occurrence of the selected faults. A simple fusion algorithm was implemented to combine the results from each algorithm to obtain an overall estimate of the identified fault type and magnitude. The identification of the fault type and magnitude enabled the use of an online fault accommodation strategy to correct for the adverse impact of these faults on engine operability thereby enabling continued engine operation in the presence of these faults. The performance of the fault detection and accommodation algorithm was extensively tested in a simulation environment.

  10. Using phylogenetic information and chemical properties to predict species tolerances to pesticides

    PubMed Central

    Guénard, Guillaume; Carsten von der Ohe, Peter; Carlisle Walker, Steven; Lek, Sovan; Legendre, Pierre

    2014-01-01

    Direct estimation of species' tolerance to pesticides and other toxic organic substances is a combinatorial problem, because of the large number of species–substance pairs. We propose a statistical modelling approach to predict tolerances associated with untested species–substance pairs, by using models fitted to tested pairs. This approach is based on the phylogeny of species and physico-chemical descriptors of pesticides, with both kinds of information combined in a bilinear model. This bilinear modelling approach predicts tolerance in untested species–compound pairs based on the facts that closely related species often respond similarly to toxic compounds and that chemically similar compounds often have similar toxic effects. The three tolerance models (median lethal concentration after 96 h) used up to 25 aquatic animal species and up to nine pesticides (organochlorines, organophosphates and carbamates). Phylogeny was estimated using DNA sequences, while the pesticides were described by their mode of toxic action and their octanol–water partition coefficients. The models explained 77–84% of the among-species variation in tolerance (log10 LC50). In cross-validation, 84–87% of the predicted tolerances for individual species were within a factor of 10 of the observed values. The approach can also be used to model other species response to multivariate stress factors. PMID:25009056

  11. Using phylogenetic information and chemical properties to predict species tolerances to pesticides.

    PubMed

    Guénard, Guillaume; Carsten von der Ohe, Peter; Carlisle Walker, Steven; Lek, Sovan; Legendre, Pierre

    2014-08-22

    Direct estimation of species' tolerance to pesticides and other toxic organic substances is a combinatorial problem, because of the large number of species-substance pairs. We propose a statistical modelling approach to predict tolerances associated with untested species-substance pairs, by using models fitted to tested pairs. This approach is based on the phylogeny of species and physico-chemical descriptors of pesticides, with both kinds of information combined in a bilinear model. This bilinear modelling approach predicts tolerance in untested species-compound pairs based on the facts that closely related species often respond similarly to toxic compounds and that chemically similar compounds often have similar toxic effects. The three tolerance models (median lethal concentration after 96 h) used up to 25 aquatic animal species and up to nine pesticides (organochlorines, organophosphates and carbamates). Phylogeny was estimated using DNA sequences, while the pesticides were described by their mode of toxic action and their octanol-water partition coefficients. The models explained 77-84% of the among-species variation in tolerance (log10 LC50). In cross-validation, 84-87% of the predicted tolerances for individual species were within a factor of 10 of the observed values. The approach can also be used to model other species response to multivariate stress factors.

  12. Heritable variation in host tolerance and resistance inferred from a wild host–parasite system

    PubMed Central

    Mazé-Guilmo, Elise; Loot, Géraldine; Páez, David J.; Lefèvre, Thierry; Blanchet, Simon

    2014-01-01

    Hosts have evolved two distinct defence strategies against parasites: resistance (which prevents infection or limit parasite growth) and tolerance (which alleviates the fitness consequences of infection). However, heritable variation in resistance and tolerance and the genetic correlation between these two traits have rarely been characterized in wild host populations. Here, we estimate these parameters for both traits in Leuciscus burdigalensis, a freshwater fish parasitized by Tracheliastes polycolpus. We used a genetic database to construct a full-sib pedigree in a wild L. burdigalensis population. We then used univariate animal models to estimate inclusive heritability (i.e. all forms of genetic and non-genetic inheritance) in resistance and tolerance. Finally, we assessed the genetic correlation between these two traits using a bivariate animal model. We found significant heritability for resistance (H = 17.6%; 95% CI: 7.2–32.2%) and tolerance (H = 18.8%; 95% CI: 4.4–36.1%), whereas we found no evidence for the existence of a genetic correlation between these traits. Furthermore, we confirm that resistance and tolerance are strongly affected by environmental effects. Our results demonstrate that (i) heritable variation exists for parasite resistance and tolerance in wild host populations, and (ii) these traits can evolve independently in populations. PMID:24478295

  13. Heritable variation in host tolerance and resistance inferred from a wild host-parasite system.

    PubMed

    Mazé-Guilmo, Elise; Loot, Géraldine; Páez, David J; Lefèvre, Thierry; Blanchet, Simon

    2014-03-22

    Hosts have evolved two distinct defence strategies against parasites: resistance (which prevents infection or limit parasite growth) and tolerance (which alleviates the fitness consequences of infection). However, heritable variation in resistance and tolerance and the genetic correlation between these two traits have rarely been characterized in wild host populations. Here, we estimate these parameters for both traits in Leuciscus burdigalensis, a freshwater fish parasitized by Tracheliastes polycolpus. We used a genetic database to construct a full-sib pedigree in a wild L. burdigalensis population. We then used univariate animal models to estimate inclusive heritability (i.e. all forms of genetic and non-genetic inheritance) in resistance and tolerance. Finally, we assessed the genetic correlation between these two traits using a bivariate animal model. We found significant heritability for resistance (H = 17.6%; 95% CI: 7.2-32.2%) and tolerance (H = 18.8%; 95% CI: 4.4-36.1%), whereas we found no evidence for the existence of a genetic correlation between these traits. Furthermore, we confirm that resistance and tolerance are strongly affected by environmental effects. Our results demonstrate that (i) heritable variation exists for parasite resistance and tolerance in wild host populations, and (ii) these traits can evolve independently in populations.

  14. Enhancing drought tolerance in C(4) crops.

    PubMed

    Lopes, Marta S; Araus, Jose Luis; van Heerden, Philippus D R; Foyer, Christine H

    2011-05-01

    Adaptation to abiotic stresses is a quantitative trait controlled by many different genes. Enhancing the tolerance of crop plants to abiotic stresses such as drought has therefore proved to be somewhat elusive in terms of plant breeding. While many C(4) species have significant agronomic importance, most of the research effort on improving drought tolerance has focused on maize. Ideally, drought tolerance has to be achieved without penalties in yield potential. Possibilities for success in this regard are highlighted by studies on maize hybrids performed over the last 70 years that have demonstrated that yield potential and enhanced stress tolerance are associated traits. However, while our understanding of the molecular mechanisms that enable plants to tolerate drought has increased considerably in recent years, there have been relatively few applications of DNA marker technologies in practical C(4) breeding programmes for improved stress tolerance. Moreover, until recently, targeted approaches to drought tolerance have concentrated largely on shoot parameters, particularly those associated with photosynthesis and stay green phenotypes, rather than on root traits such as soil moisture capture for transpiration, root architecture, and improvement of effective use of water. These root traits are now increasingly considered as important targets for yield improvement in C(4) plants under drought stress. Similarly, the molecular mechanisms underpinning heterosis have considerable potential for exploitation in enhancing drought stress tolerance. While current evidence points to the crucial importance of root traits in drought tolerance in C(4) plants, shoot traits may also be important in maintaining high yields during drought.

  15. Tolerating failures of continuous-valued sensors

    NASA Technical Reports Server (NTRS)

    Marzullo, Keith

    1990-01-01

    One aspect of fault tolerance in process control programs is the ability to tolerate sensor failure. A methodology for transforming a process control program that cannot tolerate sensor failures onto one that can is presented. Issues addressed include modifying specifications in order to accommodate uncertainty in sensor values and averaging sensor values in a fault tolerant manner. In addition, a hierarchy of sensor failure models is identified, and both the attainable accuracy and the run-time complexity of sensor averaging with respect to this hierarchy is discussed.

  16. Tolerating failures of continuous-valued sensors

    NASA Astrophysics Data System (ADS)

    Marzullo, Keith

    1990-09-01

    One aspect of fault tolerance in process control programs is the ability to tolerate sensor failure. A methodology for transforming a process control program that cannot tolerate sensor failures onto one that can is presented. Issues addressed include modifying specifications in order to accommodate uncertainty in sensor values and averaging sensor values in a fault tolerant manner. In addition, a hierarchy of sensor failure models is identified, and both the attainable accuracy and the run-time complexity of sensor averaging with respect to this hierarchy is discussed.

  17. Genomic and Genetic Approaches to Solvent Tolerance

    SciTech Connect

    Eleftherios T. Papoutsakis

    2005-06-10

    The proposed research is to understand and exploit the molecular basis that determines tolerance of the industrially important anaerobic clostridia to solvents. Furthermore, we aim to develop general genomic and metabolic engineering strategies for understanding the molecular basis of tolerance to chemicals and for developing tolerant strains. Our hypothesis is that the molecular basis of what makes bacterial cells able to withstand high solvent concentrations can be used to metabolically engineer cells so that they can tolerate higher concentrations of solvents and related chemicals.

  18. Breach of tolerance: primary biliary cirrhosis.

    PubMed

    Wang, Lifeng; Wang, Fu-Sheng; Chang, Christopher; Gershwin, M Eric

    2014-08-01

    In primary biliary cirrhosis (PBC), the breach of tolerance that leads to active disease involves a disruption in several layers of control, including central tolerance, peripheral anergy, a "liver tolerance effect," and the action of T regulatory cells and their related cytokines. Each of these control mechanisms plays a role in preventing an immune response against self, but all of them act in concert to generate effective protection against autoimmunity without compromising the ability of the host immune system to mount an effective response to pathogens. At the same time, genetic susceptibility, environmental factors, including infection agents and xenobiotics, play important roles in breach of tolerance in the development of PBC.

  19. Mechanisms of ethanol tolerance in Saccharomyces cerevisiae.

    PubMed

    Ma, Menggen; Liu, Z Lewis

    2010-07-01

    Saccharomyces cerevisiae is a superb ethanol producer, yet is also sensitive to higher ethanol concentrations especially under high gravity or very high gravity fermentation conditions. Ethanol tolerance is associated with interplay of complex networks at the genome level. Although significant efforts have been made to study ethanol stress response in past decades, mechanisms of ethanol tolerance are not well known. With developments of genome sequencing and genomic technologies, our understanding of yeast biology has been revolutionarily advanced. More evidence of mechanisms of ethanol tolerance have been discovered involving multiple loci, multi-stress, and complex interactions as well as signal transduction pathways and regulatory networks. Transcription dynamics and profiling studies of key gene sets including heat shock proteins provided insight into tolerance mechanisms. A transient gene expression response or a stress response to ethanol does not necessarily lead to ethanol tolerance in yeast. Reprogrammed pathways and interactions of cofactor regeneration and redox balance observed from studies of tolerant yeast demonstrated the significant importance of a time-course study for ethanol tolerance. In this review, we focus on current advances of our understanding for ethanol-tolerance mechanisms of S. cerevisiae including gene expression responses, pathway-based analysis, signal transduction and regulatory networks. A prototype of global system model for mechanisms of ethanol tolerance is presented.

  20. Abscisic Acid-Induced Chilling Tolerance in Maize Suspension-Cultured Cells 1

    PubMed Central

    Xin, Zhanguo; Li, Paul H.

    1992-01-01

    The induction of chilling tolerance by abscisic acid (ABA) in maize (Zea mays L. cv Black Mexican Sweet) suspension cultured cells was examined. Cell viability during exposure to chilling was estimated by triphenyl tetrazolium chloride reduction immediately after chilling and a filter paper growth assay. Both methods yielded comparable results. Chilling tolerance was induced by transferring 5-day-old cultures (late log phase) to a fresh medium containing ABA (10 to 100 micromolar). The greatest chilling tolerance was achieved with ABA at 100 micromolar. Growth of cells was inhibited at this concentration. After a 7-day exposure to 4°C in the dark, the survival of ABA-treated cells (100 micromolar ABA, 28°C for 24 h in the dark) was sevenfold greater than untreated cells. Effective induction of chilling tolerance was first observed when cells were held at 28°C for 6 hours after adding ABA. No tolerance was induced if the culture was chilled at the inception of ABA treatment. Induction of chilling tolerance was inhibited by cycloheximide. These results indicate that ABA is capable of inducing chilling tolerance when ABA-treated cells are incubated at a warm temperature before exposure to chilling, and this induction requires de novo synthesis of proteins. ImagesFigure 2 PMID:16668943

  1. Extensive Acclimation in Ectotherms Conceals Interspecific Variation in Thermal Tolerance Limits

    PubMed Central

    Pintor, Anna F. V.; Schwarzkopf, Lin; Krockenberger, Andrew K.

    2016-01-01

    Species’ tolerance limits determine their capacity to tolerate climatic extremes and limit their potential distributions. Interspecific variation in thermal tolerances is often proposed to indicate climatic vulnerability and is, therefore, the subject of many recent meta-studies on differential capacities of species from climatically different habitats to deal with climate change. Most studies on thermal tolerances do not acclimate animals or use inconsistent, and insufficient, acclimation times, limiting our knowledge of the shape, duration and extent of acclimation responses. Consequently patterns in thermal tolerances observed in meta-analyses, based on data from the literature are based on inconsistent, partial acclimation and true trends may be obscured. In this study we describe time-course of complete acclimation of critical thermal minima in the tropical ectotherm Carlia longipes and compare it to the average acclimation response of other reptiles, estimated from published data, to assess how much acclimation time may contribute to observed differences in thermal limits. Carlia longipes decreased their lower critical thermal limits by 2.4°C and completed 95% of acclimation in 17 weeks. Wild populations did not mirror this acclimation process over the winter. Other reptiles appear to decrease cold tolerance more quickly (95% in 7 weeks) and to a greater extent, with an estimated average acclimation response of 6.1°C. However, without data on tolerances after longer acclimation times available, our capacity to estimate final acclimation state is very limited. Based on the subset of data available for meta-analysis, much of the variation in cold tolerance observed in the literature can be attributed to acclimation time. Our results indicate that (i) acclimation responses can be slow and substantial, even in tropical species, and (ii) interspecific differences in acclimation speed and extent may obscure trends assessed in some meta-studies. Cold tolerances

  2. Extensive Acclimation in Ectotherms Conceals Interspecific Variation in Thermal Tolerance Limits.

    PubMed

    Pintor, Anna F V; Schwarzkopf, Lin; Krockenberger, Andrew K

    2016-01-01

    Species' tolerance limits determine their capacity to tolerate climatic extremes and limit their potential distributions. Interspecific variation in thermal tolerances is often proposed to indicate climatic vulnerability and is, therefore, the subject of many recent meta-studies on differential capacities of species from climatically different habitats to deal with climate change. Most studies on thermal tolerances do not acclimate animals or use inconsistent, and insufficient, acclimation times, limiting our knowledge of the shape, duration and extent of acclimation responses. Consequently patterns in thermal tolerances observed in meta-analyses, based on data from the literature are based on inconsistent, partial acclimation and true trends may be obscured. In this study we describe time-course of complete acclimation of critical thermal minima in the tropical ectotherm Carlia longipes and compare it to the average acclimation response of other reptiles, estimated from published data, to assess how much acclimation time may contribute to observed differences in thermal limits. Carlia longipes decreased their lower critical thermal limits by 2.4°C and completed 95% of acclimation in 17 weeks. Wild populations did not mirror this acclimation process over the winter. Other reptiles appear to decrease cold tolerance more quickly (95% in 7 weeks) and to a greater extent, with an estimated average acclimation response of 6.1°C. However, without data on tolerances after longer acclimation times available, our capacity to estimate final acclimation state is very limited. Based on the subset of data available for meta-analysis, much of the variation in cold tolerance observed in the literature can be attributed to acclimation time. Our results indicate that (i) acclimation responses can be slow and substantial, even in tropical species, and (ii) interspecific differences in acclimation speed and extent may obscure trends assessed in some meta-studies. Cold tolerances of

  3. Selection of machining datum and allocation of tolerance through tolerance charting technique

    NASA Astrophysics Data System (ADS)

    Thilak, Manoharan; Sivakumar, Karuppan; Jayaprakash, Govindharajalu

    2012-07-01

    Tolerance charting is an effective tool to determine the optimal allocation of working dimensions and working tolerances such that the blueprint dimensions and tolerances can be achieved to accomplish the cost objectives. The selection of machining datum and allocation of tolerances are critical in any machining process planning as they directly affect any setup methods/machine tools selection and machining time. This paper mainly focuses on the selection of optimum machining datums and machining tolerances simultaneously in process planning. A dynamic tolerance charting constraint scheme is developed and implemented in the optimization procedure. An optimization model is formulated for selecting machining datum and tolerances and implemented with an algorithm namely Elitist Non-Dominated Sorting Genetic Algorithm (NSGA-II).The computational results indicate that the proposed methodology is capable and robust in finding the optimal machining datum set and tolerances.

  4. Probabilistic evaluation of on-line checks in fault-tolerant multiprocessor systems

    NASA Technical Reports Server (NTRS)

    Nair, V. S. S.; Hoskote, Yatin V.; Abraham, Jacob A.

    1992-01-01

    The analysis of fault-tolerant multiprocessor systems that use concurrent error detection (CED) schemes is much more difficult than the analysis of conventional fault-tolerant architectures. Various analytical techniques have been proposed to evaluate CED schemes deterministically. However, these approaches are based on worst-case assumptions related to the failure of system components. Often, the evaluation results do not reflect the actual fault tolerance capabilities of the system. A probabilistic approach to evaluate the fault detecting and locating capabilities of on-line checks in a system is developed. The various probabilities associated with the checking schemes are identified and used in the framework of the matrix-based model. Based on these probabilistic matrices, estimates for the fault tolerance capabilities of various systems are derived analytically.

  5. Tolerance of the liver to the effects of Yttrium-90 radiation

    SciTech Connect

    Gray, B.N.; Burton, M.A.; Kelleher, D.; Klemp, P.; Matz, L. )

    1990-03-01

    There are no reliable data documenting the tolerance of the human liver to ionizing radiation from a continuous Yttrium-90 source. As Yttrium-90 incorporated into microspheres is being used to treat patients with liver cancer, it is imperative that the tolerance of the human liver to this form of radiation damage be determined. Four patients with metastatic liver cancer were treated with Yttrium-90 to deliver radiation doses above that considered tolerable when given by conventional external sources. Patients were monitored with serial estimations of liver function tests and between 7 and 9 months after treatment liver biopsies were performed. Histological examination of the liver biopsies confirmed only minimal changes in the normal liver parenchyma. These data indicate that the human liver may tolerate relatively large radiation doses when delivered by Yttrium-90 microspheres embedded in the liver parenchyma as a number of discrete point sources.

  6. A new statistical method for design and analyses of component tolerance

    NASA Astrophysics Data System (ADS)

    Movahedi, Mohammad Mehdi; Khounsiavash, Mohsen; Otadi, Mahmood; Mosleh, Maryam

    2016-09-01

    Tolerancing conducted by design engineers to meet customers' needs is a prerequisite for producing high-quality products. Engineers use handbooks to conduct tolerancing. While use of statistical methods for tolerancing is not something new, engineers often use known distributions, including the normal distribution. Yet, if the statistical distribution of the given variable is unknown, a new statistical method will be employed to design tolerance. In this paper, we use generalized lambda distribution for design and analyses component tolerance. We use percentile method (PM) to estimate the distribution parameters. The findings indicated that, when the distribution of the component data is unknown, the proposed method can be used to expedite the design of component tolerance. Moreover, in the case of assembled sets, more extensive tolerance for each component with the same target performance can be utilized.

  7. A new statistical method for design and analyses of component tolerance

    NASA Astrophysics Data System (ADS)

    Movahedi, Mohammad Mehdi; Khounsiavash, Mohsen; Otadi, Mahmood; Mosleh, Maryam

    2017-09-01

    Tolerancing conducted by design engineers to meet customers' needs is a prerequisite for producing high-quality products. Engineers use handbooks to conduct tolerancing. While use of statistical methods for tolerancing is not something new, engineers often use known distributions, including the normal distribution. Yet, if the statistical distribution of the given variable is unknown, a new statistical method will be employed to design tolerance. In this paper, we use generalized lambda distribution for design and analyses component tolerance. We use percentile method (PM) to estimate the distribution parameters. The findings indicated that, when the distribution of the component data is unknown, the proposed method can be used to expedite the design of component tolerance. Moreover, in the case of assembled sets, more extensive tolerance for each component with the same target performance can be utilized.

  8. Strain tolerant microfilamentary superconducting wire

    DOEpatents

    Finnemore, Douglas K.; Miller, Theodore A.; Ostenson, Jerome E.; Schwartzkopf, Louis A.; Sanders, Steven C.

    1993-02-23

    A strain tolerant microfilamentary wire capable of carrying superconducting currents is provided comprising a plurality of discontinuous filaments formed from a high temperature superconducting material. The discontinuous filaments have a length at least several orders of magnitude greater than the filament diameter and are sufficiently strong while in an amorphous state to withstand compaction. A normal metal is interposed between and binds the discontinuous filaments to form a normal metal matrix capable of withstanding heat treatment for converting the filaments to a superconducting state. The geometry of the filaments within the normal metal matrix provides substantial filament-to-filament overlap, and the normal metal is sufficiently thin to allow supercurrent transfer between the overlapped discontinuous filaments but is also sufficiently thick to provide strain relief to the filaments.

  9. Water-tolerant legume nodulation.

    PubMed

    Capoen, Ward; Goormachtig, Sofie; Holsters, Marcelle

    2010-03-01

    Water-tolerant nodulation is an adaptation of legumes that grow in wet or temporarily flooded habitats. This nodulation mode takes place at lateral root bases via intercellular bacterial invasion in cortical infection pockets. The tropical legume Sesbania rostrata has become a model for the study of the molecular basis of crack entry nodulation compared with root hair curl nodulation. For intercellular invasion, Nodulation Factor (NF) signalling recruits an ethylene-dependent, common Sym gene-independent pathway, leading to local cell death. The NF structure requirements are less stringent than for intracellular invasion in root hairs, which is correlated with a very specific NF-induced calcium spiking signature, presumably necessary for correct gene expression to assemble a functional entry complex in the epidermis.

  10. Fault tolerant data management system

    NASA Technical Reports Server (NTRS)

    Gustin, W. M.; Smither, M. A.

    1972-01-01

    Described in detail are: (1) results obtained in modifying the onboard data management system software to a multiprocessor fault tolerant system; (2) a functional description of the prototype buffer I/O units; (3) description of modification to the ACADC and stimuli generating unit of the DTS; and (4) summaries and conclusions on techniques implemented in the rack and prototype buffers. Also documented is the work done in investigating techniques of high speed (5 Mbps) digital data transmission in the data bus environment. The application considered is a multiport data bus operating with the following constraints: no preferred stations; random bus access by all stations; all stations equally likely to source or sink data; no limit to the number of stations along the bus; no branching of the bus; and no restriction on station placement along the bus.

  11. Targeting phenotypically tolerant Mycobacterium tuberculosis

    PubMed Central

    Gold, Ben; Nathan, Carl

    2016-01-01

    While the immune system is credited with averting tuberculosis in billions of individuals exposed to Mycobacterium tuberculosis, the immune system is also culpable for tempering the ability of antibiotics to deliver swift and durable cure of disease. In individuals afflicted with tuberculosis, host immunity produces diverse microenvironmental niches that support suboptimal growth, or complete growth arrest, of M. tuberculosis. The physiological state of nonreplication in bacteria is associated with phenotypic drug tolerance. Many of these host microenvironments, when modeled in vitro by carbon starvation, complete nutrient starvation, stationary phase, acidic pH, reactive nitrogen intermediates, hypoxia, biofilms, and withholding streptomycin from the streptomycin-addicted strain SS18b, render M. tuberculosis profoundly tolerant to many of the antibiotics that are given to tuberculosis patients in a clinical setting. Targeting nonreplicating persisters is anticipated to reduce the duration of antibiotic treatment and rate of post-treatment relapse. Some promising drugs to treat tuberculosis, such as rifampicin and bedaquiline, only kill nonreplicating M. tuberculosis in vitro at concentrations far greater than their minimal inhibitory concentrations against replicating bacilli. There is an urgent demand to identify which of the currently used antibiotics, and which of the molecules in academic and corporate screening collections, have potent bactericidal action on nonreplicating M. tuberculosis. With this goal, we review methods of high throughput screening to target nonreplicating M. tuberculosis and methods to progress candidate molecules. A classification based on structures and putative targets of molecules that have been reported to kill nonreplicating M. tuberculosis revealed a rich diversity in pharmacophores. However, few of these compounds were tested under conditions that would exclude the impact of adsorbed compound acting during the recovery phase of

  12. Robot Position Sensor Fault Tolerance

    NASA Technical Reports Server (NTRS)

    Aldridge, Hal A.

    1997-01-01

    Robot systems in critical applications, such as those in space and nuclear environments, must be able to operate during component failure to complete important tasks. One failure mode that has received little attention is the failure of joint position sensors. Current fault tolerant designs require the addition of directly redundant position sensors which can affect joint design. A new method is proposed that utilizes analytical redundancy to allow for continued operation during joint position sensor failure. Joint torque sensors are used with a virtual passive torque controller to make the robot joint stable without position feedback and improve position tracking performance in the presence of unknown link dynamics and end-effector loading. Two Cartesian accelerometer based methods are proposed to determine the position of the joint. The joint specific position determination method utilizes two triaxial accelerometers attached to the link driven by the joint with the failed position sensor. The joint specific method is not computationally complex and the position error is bounded. The system wide position determination method utilizes accelerometers distributed on different robot links and the end-effector to determine the position of sets of multiple joints. The system wide method requires fewer accelerometers than the joint specific method to make all joint position sensors fault tolerant but is more computationally complex and has lower convergence properties. Experiments were conducted on a laboratory manipulator. Both position determination methods were shown to track the actual position satisfactorily. A controller using the position determination methods and the virtual passive torque controller was able to servo the joints to a desired position during position sensor failure.

  13. 40 CFR 180.32 - Procedure for modifying and revoking tolerances or exemptions from tolerances.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Procedural Regulations § 180.32 Procedure for modifying and revoking tolerances or exemptions from... modifying or revoking a tolerance for a pesticide chemical residue on raw agricultural commodities or...

  14. 40 CFR 180.32 - Procedure for modifying and revoking tolerances or exemptions from tolerances.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Procedural Regulations § 180.32 Procedure for modifying and revoking tolerances or exemptions from... modifying or revoking a tolerance for a pesticide chemical residue on raw agricultural commodities or...

  15. 40 CFR 180.32 - Procedure for modifying and revoking tolerances or exemptions from tolerances.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Procedural Regulations § 180.32 Procedure for modifying and revoking tolerances or exemptions from... modifying or revoking a tolerance for a pesticide chemical residue on raw agricultural commodities or...

  16. 40 CFR 180.32 - Procedure for modifying and revoking tolerances or exemptions from tolerances.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Procedural Regulations § 180.32 Procedure for modifying and revoking tolerances or exemptions from... modifying or revoking a tolerance for a pesticide chemical residue on raw agricultural commodities or...

  17. 40 CFR 180.32 - Procedure for modifying and revoking tolerances or exemptions from tolerances.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Procedural Regulations § 180.32 Procedure for modifying and revoking tolerances or exemptions from... modifying or revoking a tolerance for a pesticide chemical residue on raw agricultural commodities or...

  18. Chronic Manganism: Preliminary Observations on Glucose Tolerance and Serum Proteins

    PubMed Central

    Hassanein, M.; Ghaleb, H. A.; Haroun, E. A.; Hegazy, M. R.; Khayyal, M. A. H.

    1966-01-01

    An intravenous glucose tolerance test was carried out in 11 patients with chronic manganese poisoning. Prolonged reactionary hypoglycaemia was observed. The underlying mechanism is discussed. It may be due to a disturbance of the hypothalamo-pituitary-adrenal axis. In seven of these patients total serum proteins were estimated and were separated electrophoretically. The albumin: globulin ratios were lower in patients than in controls. There were significant reductions in serum albumin concentrations and increases in concentrations of α1 and β globulins. PMID:5904101

  19. Reliability estimation procedures and CARE: The Computer-Aided Reliability Estimation Program

    NASA Technical Reports Server (NTRS)

    Mathur, F. P.

    1971-01-01

    Ultrareliable fault-tolerant onboard digital systems for spacecraft intended for long mission life exploration of the outer planets are under development. The design of systems involving self-repair and fault-tolerance leads to the companion problem of quantifying and evaluating the survival probability of the system for the mission under consideration and the constraints imposed upon the system. Methods have been developed to (1) model self-repair and fault-tolerant organizations; (2) compute survival probability, mean life, and many other reliability predictive functions with respect to various systems and mission parameters; (3) perform sensitivity analysis of the system with respect to mission parameters; and (4) quantitatively compare competitive fault-tolerant systems. Various measures of comparison are offered. To automate the procedures of reliability mathematical modeling and evaluation, the CARE (computer-aided reliability estimation) program was developed. CARE is an interactive program residing on the UNIVAC 1108 system, which makes the above calculations and facilitates report preparation by providing output in tabular form, graphical 2-dimensional plots, and 3-dimensional projections. The reliability estimation of fault-tolerant organization by means of the CARE program is described.

  20. Reliability of Fault Tolerant Control Systems. Part 2

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva

    2000-01-01

    This paper reports Part II of a two part effort that is intended to delineate the relationship between reliability and fault tolerant control in a quantitative manner. Reliability properties peculiar to fault-tolerant control systems are emphasized, such as the presence of analytic redundancy in high proportion, the dependence of failures on control performance, and high risks associated with decisions in redundancy management due to multiple sources of uncertainties and sometimes large processing requirements. As a consequence, coverage of failures through redundancy management can be severely limited. The paper proposes to formulate the fault tolerant control problem as an optimization problem that maximizes coverage of failures through redundancy management. Coverage modeling is attempted in a way that captures its dependence on the control performance and on the diagnostic resolution. Under the proposed redundancy management policy, it is shown that an enhanced overall system reliability can be achieved with a control law of a superior robustness, with an estimator of a higher resolution, and with a control performance requirement of a lesser stringency.

  1. Heated Allergens and Induction of Tolerance in Food Allergic Children

    PubMed Central

    Netting, Merryn; Makrides, Maria; Gold, Michael; Quinn, Patrick; Penttila, Irmeli

    2013-01-01

    Food allergies are one of the first manifestations of allergic disease and have been shown to significantly impact on general health perception, parental emotional distress and family activities. It is estimated that in the Western world, almost one in ten children have an IgE-mediated allergy. Cow’s milk and egg allergy are common childhood allergies. Until recently, children with food allergy were advised to avoid all dietary exposure to the allergen to which they were sensitive, in the thought that consumption would exacerbate their allergy. However, recent publications indicate that up to 70% of children with egg allergy can tolerate egg baked in a cake or muffin without apparent reaction. Likewise, up to 75% of children can tolerate baked goods containing cow’s milk, and these children demonstrate IgE and IgG4 profiles indicative of tolerance development. This article will review the current literature regarding the use of heated food allergens as immunotherapy for children with cow’s milk and egg allergy. PMID:23739144

  2. 78 FR 28507 - Spirotetramat; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-15

    ...; pineapple, process residue at 0.36 ppm; coffee, green beans at 0.2 ppm; and coffee, roast beans at 0.32 ppm... coffee, roast beans, are not necessary and a tolerance on coffee, instant, should be established. The... Agency determined that the proposed tolerances in or on pineapple, process residue, and coffee,...

  3. Method of identifying plant pathogen tolerance

    DOEpatents

    Ecker, Joseph R.; Staskawicz, Brian J.; Bent, Andrew F.; Innes, Roger W.

    1997-10-07

    A process for identifying a plant having disease tolerance comprising administering to a plant an inhibitory amount of ethylene and screening for ethylene insensitivity, thereby identifying a disease tolerant plant, is described. Plants identified by the foregoing process are also described.

  4. Drought tolerance of sugar maple ecotypes

    Treesearch

    Richard J. Hauer; Jeffery O. Dawson

    1995-01-01

    Sugar maple declines periodically occur in rural and urban areas. These declines usually follow periods of below-average precipitation leading to the speculation that moisture deficiency is a primary cause of the decline. Sugar maple ecotypes with greater tolerance to drought should have greater longevity and vitality as a result of this tolerance. Sugar maple and...

  5. 75 FR 69353 - Isoxaben; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-12

    ... almond, hulls; grape; nut, tree, group 14; and pistachio. Dow AgroSciences requested these tolerances... 0.01 ppm; and nut, tree, group 14 and pistachio at 0.03 ppm. That notice referenced a summary of the... the data supporting the petition, EPA has reduced the tolerances for nut, tree, group 14 and...

  6. 75 FR 22256 - Difenoconazole Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-28

    ...; citrus, dried pulp; citrus, oil; fruit, citrus, group 10; grape; grape, raisin; nut, tree, group 14... at 14 ppm; nut, tree, group 14 at 0.03 ppm; onion, bulb, subgroup 3-07A at 6 ppm; onion, green, bulb... tree nut group tolerance is being established, a separate pistachio tolerance is needed...

  7. 77 FR 28493 - Propylene Oxide; Tolerance Actions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-15

    ... Agency (EPA). ACTION: Final rule. SUMMARY: EPA is establishing the tree nut crop group tolerance and... CFR 180.491(a)(1) tolerances for propylene oxide at 300 ppm on nut, pine; nut, tree, group 14; and..., tree, group 14; and pistachio. Also, in accordance with current Agency practice, EPA is making...

  8. 77 FR 35295 - Methyl Bromide; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-13

    ... AGENCY 40 CFR Part 180 RIN 2070-ZA16 Methyl Bromide; Pesticide Tolerances AGENCY: Environmental... methyl bromide in or on cotton, undelinted seed under the Federal Food, Drug, and Cosmetic Act (FFDCA... to establish a tolerance for residues of methyl bromide, including metabolites and degradates in or...

  9. 75 FR 29435 - Diquat Dibromide; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-26

    ..., 1995.'' This statement was originally included as a footnote to import tolerances for banana and coffee... banana and coffee tolerances. The updated footnote to the table in paragraph (a)(3) reads ``There are no... cation in or on the following food commodites: Commodity Parts per million Banana\\1\\ 0.05 Coffee, bean...

  10. 7 CFR 51.1525 - Tolerances.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Standards for Grades of Fresh Plums and Prunes Tolerances § 51.1525 Tolerances. In order to allow for....S. No. 1—(1) For defects of plums or prunes other than Italian type prunes at shipping point. 1 8... continental United States, the port of entry into the United States. (2) For defects of plums or prunes other...

  11. 7 CFR 51.1525 - Tolerances.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Standards for Grades of Fresh Plums and Prunes Tolerances § 51.1525 Tolerances. In order to allow for....S. No. 1—(1) For defects of plums or prunes other than Italian type prunes at shipping point. 1 8... continental United States, the port of entry into the United States. (2) For defects of plums or prunes other...

  12. 47 CFR 74.1261 - Frequency tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Frequency tolerance. 74.1261 Section 74.1261... FM Broadcast Booster Stations § 74.1261 Frequency tolerance. (a) The licensee of an FM translator or... frequency at the output of the translator within 0.01 percent of its assigned frequency. (b) The licensee of...

  13. 47 CFR 101.107 - Frequency tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequency tolerance. 101.107 Section 101.107... SERVICES Technical Standards § 101.107 Frequency tolerance. (a) The carrier frequency of each transmitter authorized in these services must be maintained within the following percentage of the reference frequency...

  14. 47 CFR 74.1261 - Frequency tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Frequency tolerance. 74.1261 Section 74.1261... FM Broadcast Booster Stations § 74.1261 Frequency tolerance. (a) The licensee of an FM translator or... frequency at the output of the translator within 0.01 percent of its assigned frequency. (b) The licensee of...

  15. 47 CFR 74.661 - Frequency tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Frequency tolerance. 74.661 Section 74.661... Stations § 74.661 Frequency tolerance. Stations in this service shall maintain the carrier frequency of each authorized transmitter to within the following percentage of the assigned frequency. Frequency...

  16. 47 CFR 74.1261 - Frequency tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Frequency tolerance. 74.1261 Section 74.1261... FM Broadcast Booster Stations § 74.1261 Frequency tolerance. (a) The licensee of an FM translator or... frequency at the output of the translator within 0.01 percent of its assigned frequency. (b) The licensee of...

  17. 47 CFR 22.355 - Frequency tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Frequency tolerance. 22.355 Section 22.355... Operational and Technical Requirements Technical Requirements § 22.355 Frequency tolerance. Except as otherwise provided in this part, the carrier frequency of each transmitter in the Public Mobile Services...

  18. 47 CFR 74.1261 - Frequency tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Frequency tolerance. 74.1261 Section 74.1261... FM Broadcast Booster Stations § 74.1261 Frequency tolerance. (a) The licensee of an FM translator or... frequency at the output of the translator within 0.01 percent of its assigned frequency. (b) The licensee of...

  19. 47 CFR 22.355 - Frequency tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Frequency tolerance. 22.355 Section 22.355... Operational and Technical Requirements Technical Requirements § 22.355 Frequency tolerance. Except as otherwise provided in this part, the carrier frequency of each transmitter in the Public Mobile Services...

  20. 47 CFR 22.355 - Frequency tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Frequency tolerance. 22.355 Section 22.355... Operational and Technical Requirements Technical Requirements § 22.355 Frequency tolerance. Except as otherwise provided in this part, the carrier frequency of each transmitter in the Public Mobile Services...