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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. 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.

  4. 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.

  5. 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.

  6. Tolerance for error and computational estimation ability.

    PubMed

    Hogan, Thomas P; Wyckoff, Laurie A; Krebs, Paul; Jones, William; Fitzgerald, Mark P

    2004-06-01

    Previous investigators have suggested that the personality variable tolerance for error is related to success in computational estimation. However, this suggestion has not been tested directly. This study examined the relationship between performance on a computational estimation test and scores on the NEO-Five Factor Inventory, a measure of the Big Five personality traits, including Openness, an index of tolerance for ambiguity. Other variables included SAT-I Verbal and Mathematics scores and self-rated mathematics ability. Participants were 65 college students. There was no significant relationship between the tolerance variable and computational estimation performance. There was a modest negative relationship between Agreeableness and estimation performance. The skepticism associated with the negative pole of the Agreeableness dimension may be important to pursue in further understanding of estimation ability. PMID:15362423

  7. 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.

  8. 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).

  9. How to estimate your tolerance for risk

    SciTech Connect

    Mackay, J.A.

    1996-12-31

    Risk tolerance is used to calculate the Risk Adjusted Value (RAV) of a proposed investment. The RAV incorporates both the expected value and risk attitude for a particular investment, taking into consideration your concern for catastrophic financial loss, as well as chance of success, cost and value if successful. Uncertainty can be incorporated into all of the above variables. Often a project is more valuable to a corporation if a partial working interest is taken rather than the entire working interest. The RAV can be used to calculate the optimum working interest and the value of that diversification. To estimate the Apparent Risk Tolerance (ART) of an individual, division or corporation several methods can be employed: (1) ART can be calculated from the working interest selected in prior investment decisions. (2) ART can be estimated from a selection of working interests by the decision maker in a proposed portfolio of projects. (3) ART can be approximated from data released to the Security and Exchange Commission (SEC) in the annual 10K supplements (for both your company and possible partners). (4) ART can be assigned based on corporate size, budget, or activity. Examples are provided for the various methods to identify risk tolerance and apply it in making optimum working interest calculations for individual projects and portfolios.

  10. 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.

  11. 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. PMID:26227029

  12. INTERLABORATORY INTERCOMPARISON OF POLONIUM-210 MEASUREMENTS

    EPA Science Inventory

    In 1975 the U.S. Environmental Protection Agency distributed calibrated solutions of polonium-210 to laboratories interested in participating in an intercomparison study of polonium-210 analysis. Participants were asked to perform a quantitative radioactivity analysis of the solu...

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Neutralization kinetics for polonium-218

    SciTech Connect

    Chu, K.D.; Hopke, P.K.

    1988-06-01

    In a well-defined experimental system the neutralization of polonium-218 ions was investigated as a function of the physical and chemical properties of the controlled composition atmosphere. The diffusion coefficient of polonium-218 under various concentrations of trace gas NO/sub 2/ in nitrogen was measured. The mobilities of Po/sup +/ and PoO/sub 2//sup +/ are determined by combining experimental results with a computer model of the system. Three neutralization mechanisms were individually studied. The small-ion recombination rate has been found to be proportional to the square root of radon concentration. The electron-scavenging mechanism is responsible for the neutralization of Po/sup +/ in NO/sub 2/ or H/sub 2/O in nitrogen. When PoO/sub 2//sup +/ is formed, the electron-transfer mechanism dominates the neutralization process. The electron is transferred to PoO/sub 2//sup +/ from molecules with lower ionization potentials. The ionization molecules with lower ionization potentials. The ionization potential of PoO/sub 2//sup +/ is also determined to be 10.44 +/- 0.05 eV.

  18. Computer-aided reliability estimation. [for fault-tolerant systems

    NASA Technical Reports Server (NTRS)

    Stiffler, J. J.

    1977-01-01

    Computer-aided reliability estimation (CARE) programs are developed to improve the tools available for estimating the reliability of fault-tolerant systems. A description is presented of a program, called CARE II, which was developed after the first program reported by Mathur (1971). Attention is given to the CARE II reliability model, the CARE II coverage model, and CARE II limitations which are to be rectified in CARE III. It is pointed out that the present coverage model in CARE II is extremely versatile. The major limitation is related to the burden placed on the user to determine the basic parameters from which the coverage calculations are made.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. [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. PMID:26856053

  7. 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…

  8. 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.

  9. 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

  10. 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. PMID:26298337

  11. 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.

  12. The thermal tolerance of crayfish could be estimated from respiratory electron transport system activity.

    PubMed

    Simčič, Tatjana; Pajk, Franja; Jaklič, Martina; Brancelj, Anton; Vrezec, Al

    2014-04-01

    Whether electron transport system (ETS) activity could be used as an estimator of crayfish thermal tolerance has been investigated experimentally. Food consumption rate, respiration rates in the air and water, the difference between energy consumption and respiration costs at a given temperature ('potential growth scope', PGS), and ETS activity of Orconectes limosus and Pacifastacus leniusculus were determined over a temperature range of 5-30°C. All concerned parameters were found to be temperature dependent. The significant correlation between ETS activity and PGS indicates that they respond similarly to temperature change. The regression analysis of ETS activity as an estimator of thermal tolerance at the mitochondrial level and PGS as an indicator of thermal tolerance at the organismic level showed the shift of optimum temperature ranges of ETS activity to the right for 2° in O. limosus and for 3° in P. leniusculus. Thus, lower estimated temperature optima and temperatures of optimum ranges of PGS compared to ETS activity could indicate higher thermal sensitivity at the organismic level than at a lower level of complexity (i.e. at the mitochondrial level). The response of ETS activity to temperature change, especially at lower and higher temperatures, indicates differences in the characteristics of the ETSs in O. limosus and P. leniusculus. O. limosus is less sensitive to high temperature. The significant correlation between PGS and ETS activity supports our assumption that ETS activity could be used for the rapid estimation of thermal tolerance in crayfish species. PMID:24679968

  13. Systematics of even-a polonium isotopes

    SciTech Connect

    Younes, W.; Cizewski, J.A.; Bernstein, L.A.

    1995-04-01

    Polonium nuclei, with two valence protons, provide fertile ground for the study of the onset of collectivity: from the textbook two-particle levels of {sup 210}Po to the phonon-like multiplets of {sup 196}Po. In their earlier work the authors described the low-lying structure of even-A Po nuclei down to {sup 196}Po as two protons interacting via a surface-{delta} interaction and adiabatically coupled to a vibrating core. However, this particle-core model (PCM) fails to adequately describe the recently measured level scheme of {sup 194}Po. Also because it assumes a pre-existing vibrational core, this model does not help to understand the single particle contributions to the collective motion. Therefore, the authors have also studied the Po systematics using a more microscopic model: the quasi-particle random phase approximation (QRPA). They will present a phenomenological analysis of the rapidity of the onset of collectivity for the Po isotopes as well as results of both PCM and QRPA calculations. The microscopic nature of the collectivity for the even-A Po isotopes will be discussed.

  14. 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.

  15. 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.

  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. 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. PMID:25176601

  18. Estimated Risk Level of Unified Stereotactic Body Radiation Therapy Dose Tolerance Limits for Spinal Cord.

    PubMed

    Grimm, Jimm; Sahgal, Arjun; Soltys, Scott G; Luxton, Gary; Patel, Ashish; Herbert, Scott; Xue, Jinyu; Ma, Lijun; Yorke, Ellen; Adler, John R; Gibbs, Iris C

    2016-04-01

    A literature review of more than 200 stereotactic body radiation therapy spine articles from the past 20 years found only a single article that provided dose-volume data and outcomes for each spinal cord of a clinical dataset: the Gibbs 2007 article (Gibbs et al, 2007(1)), which essentially contains the first 100 stereotactic body radiation therapy (SBRT) spine treatments from Stanford University Medical Center. The dataset is modeled and compared in detail to the rest of the literature review, which found 59 dose tolerance limits for the spinal cord in 1-5 fractions. We partitioned these limits into a unified format of high-risk and low-risk dose tolerance limits. To estimate the corresponding risk level of each limit we used the Gibbs 2007 clinical spinal cord dose-volume data for 102 spinal metastases in 74 patients treated by spinal radiosurgery. In all, 50 of the patients were previously irradiated to a median dose of 40Gy in 2-3Gy fractions and 3 patients developed treatment-related myelopathy. These dose-volume data were digitized into the dose-volume histogram (DVH) Evaluator software tool where parameters of the probit dose-response model were fitted using the maximum likelihood approach (Jackson et al, 1995(3)). Based on this limited dataset, for de novo cases the unified low-risk dose tolerance limits yielded an estimated risk of spinal cord injury of ≤1% in 1-5 fractions, and the high-risk limits yielded an estimated risk of ≤3%. The QUANTEC Dmax limits of 13Gy in a single fraction and 20Gy in 3 fractions had less than 1% risk estimated from this dataset, so we consider these among the low-risk limits. In the previously irradiated cohort, the estimated risk levels for 10 and 14Gy maximum cord dose limits in 5 fractions are 0.4% and 0.6%, respectively. Longer follow-up and more patients are required to improve the risk estimates and provide more complete validation. PMID:27000514

  19. Structural equation models to estimate risk of infection and tolerance to bovine mastitis

    PubMed Central

    2013-01-01

    Background One method to improve durably animal welfare is to select, as reproducers, animals with the highest ability to resist or tolerate infection. To do so, it is necessary to distinguish direct and indirect mechanisms of resistance and tolerance because selection on these traits is believed to have different epidemiological and evolutionary consequences. Methods We propose structural equation models with latent variables (1) to quantify the latent risk of infection and to identify, among the many potential mediators of infection, the few ones that influence it significantly and (2) to estimate direct and indirect levels of tolerance of animals infected naturally with pathogens. We applied the method to two surveys of bovine mastitis in the Walloon region of Belgium, in which we recorded herd management practices, mastitis frequency, and results of bacteriological analyses of milk samples. Results and discussion Structural equation models suggested that, among more than 35 surveyed herd characteristics, only nine (age, addition of urea in the rations, treatment of subclinical mastitis, presence of dirty liner, cows with hyperkeratotic teats, machine stripping, pre- and post-milking teat disinfection, and housing of milking cows in cubicles) were directly and significantly related to a latent measure of bovine mastitis, and that treatment of subclinical mastitis was involved in the pathway between post-milking teat disinfection and latent mastitis. These models also allowed the separation of direct and indirect effects of bacterial infection on milk productivity. Results suggested that infected cows were tolerant but not resistant to mastitis pathogens. Conclusions We revealed the advantages of structural equation models, compared to classical models, for dissecting measurements of resistance and tolerance to infectious diseases, here bovine mastitis. Using our method, we identified nine major risk factors that were directly associated with an increased risk of

  20. 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

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

    DOE PAGESBeta

    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.; et al

    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

  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. 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.}

  4. 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).

  5. Evolution of collective motion in light polonium nuclei

    SciTech Connect

    Cizewski, J. A.; Ding, K. Y.; Fotiades, N.; McNabb, D. P.; Younes, W.; Julin, R.; Leino, M.; Cocks, J.; Greenlees, P.; Helariutta, K.; Jones, P.; Juutinen, S.; Kankaanpaeae, A.; Kettunen, H.; Kuusiniemi, P.; Muikku, M.; Rahkila, P.; Savelius, A.; Davids, C. N.; Janssens, R. V. F.

    1998-12-21

    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. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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. PMID:25557609

  11. 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. PMID:26456728

  12. 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).

  13. 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).

  14. 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).

  15. 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).

  16. 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).

  17. 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).

  18. 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).

  19. 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).

  20. 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).

  1. 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).

  2. 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).

  3. 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).

  4. 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).

  5. 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).

  6. 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).

  7. 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).

  8. 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).

  9. Atomic Mass and Nuclear Binding Energy for Po-267 (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-267 (Polonium, atomic number Z = 84, mass number A = 267).

  10. Atomic Mass and Nuclear Binding Energy for Po-266 (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-266 (Polonium, atomic number Z = 84, mass number A = 266).

  11. 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.

  12. 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.

  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. 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.

  15. 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

  16. 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. PMID:25607005

  17. 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.

  18. 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.

  19. 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}

  20. 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.

  1. 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.

  2. 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

  3. Assessment of flood magnitude estimator uncertainty: Tolerance limits for the gamma and generalized gamma distributions

    SciTech Connect

    Ashkar, F.; Ouarda, T.B.M.J.

    1995-12-31

    The quantification of the uncertainty associated with hydrologic {open_quotes}design-event{close_quotes} estimations (e.g., flood quantile estimation by statistical flood frequency analysis) is an important problem in the assessment of the design risk associated with hydraulic structures. In and semi-arid regions the 2-parameter gamma (G2) distribution is a possible candidate for estimating flood-flow probabilities from annual flood series. The distribution has also many other hydrological applications. An approximate method is proposed for constructing approximate confidence intervals (CI`s) for quantiles of the G2 distribution. Simulation was used to test this approximate method, Similar simulation experiments were carried out for the 3-parameter generalized gamma (GG3) distribution, which has more shape flexibility than the G2. The methods of moments (MM) and of maximum likelihood (ML) were used to fit both the G2 and GG3 distributions. Useful results concerning both the G2 and GG3 distributions, based on these two estimation methods, were obtained.

  4. 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. PMID:22320701

  5. 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.

  6. Uranium series radionuclides, polonium-210 and lead-210, in the lichen-caribou-wolf food chain of the Northwest Territories

    SciTech Connect

    Thomas, P.A.; Sheard, J.W.; Swanson, S.

    1994-12-31

    This report examines baseline concentrations and transfer of the uranium decay products polonium-210 and lead-210 in the lichen-caribou-wolf food chain at two locations in the Northwest Territories, Baker Lake and Snowdrift. At each location, concentrations of the two radionuclides were determined in the lichen species Cetraria nivalis and Cladina mitis, and several tissues from caribou and wolves. Baseline concentrations and transfer coefficients within the food chain were compared between the two locations. Lichen samples were also collected from Kasba Lake, a third hunting ground used by northern Saskatchewan hunters. The lichen species chosen were common forage for caribou. Both the predominant lichen species at each location and rumen contents were used to estimate the winter diet of caribou in the calculation of transfer coefficients. The results are relevant to environmental monitoring in areas of potential future uranium mining development and the transfer coefficients determined in the study may be used to estimate radionuclide concentrations and radiation doses in future environmental assessments.

  7. 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.

  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. 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.

  10. 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.

  11. Polonium-210 in the environment around a radioactive waste disposal area and phosphate ore processing plant.

    PubMed

    Arthur, W J; Markham, O D

    1984-04-01

    Polonium-210 concentrations were determined for soil, vegetation and small mammal tissues collected at a solid radioactive waste disposal area, near a phosphate ore processing plant and at two rural areas in southeastern Idaho. Polonium concentrations in media sampled near the radioactive waste disposal facility were equal to or less than values from rural area samples, indicating that disposal of solid radioactive waste at the Idaho National Engineering Laboratory Site has not resulted in increased environmental levels of polonium. Concentrations of 210Po in soils, deer mice hide and carcass samples collected near the phosphate processing plant were statistically (P less than or equal to 0.05) greater than the other sampling locations; however, the mean 210Po concentration in soils and small mammal tissues from sampling areas near the phosphate plant were only four and three times greater, respectively, than control values. No statistical (P greater than 0.05) difference was observed for 210Po concentrations in vegetation among any of the sampling locations. PMID:6706588

  12. 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.

  13. 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

  14. 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. PMID:24586436

  15. 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…

  16. 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…

  17. 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.

  18. Elevated tolerance to aneuploidy in cancer cells: estimating the fitness effects of chromosome number alterations by in silico modelling of somatic genome evolution.

    PubMed

    Valind, Anders; Jin, Yuesheng; Gisselsson, David

    2013-01-01

    An unbalanced chromosome number (aneuploidy) is present in most malignant tumours and has been attributed to mitotic mis-segregation of chromosomes. However, recent studies have shown a relatively high rate of chromosomal mis-segregation also in non-neoplastic human cells, while the frequency of aneuploid cells remains low throughout life in most normal tissues. This implies that newly formed aneuploid cells are subject to negative selection in healthy tissues and that attenuation of this selection could contribute to aneuploidy in cancer. To test this, we modelled cellular growth as discrete time branching processes, during which chromosome gains and losses were generated and their host cells subjected to selection pressures of various magnitudes. We then assessed experimentally the frequency of chromosomal mis-segregation as well as the prevalence of aneuploid cells in human non-neoplastic cells and in cancer cells. Integrating these data into our models allowed estimation of the fitness reduction resulting from a single chromosome copy number change to an average of ≈30% in normal cells. In comparison, cancer cells showed an average fitness reduction of only 6% (p = 0.0008), indicative of aneuploidy tolerance. Simulations based on the combined presence of chromosomal mis-segregation and aneuploidy tolerance reproduced distributions of chromosome aberrations in >400 cancer cases with higher fidelity than models based on chromosomal mis-segregation alone. Reverse engineering of aneuploid cancer cell development in silico predicted that aneuploidy intolerance is a stronger limiting factor for clonal expansion of aneuploid cells than chromosomal mis-segregation rate. In conclusion, our findings indicate that not only an elevated chromosomal mis-segregation rate, but also a generalised tolerance to novel chromosomal imbalances contribute to the genomic landscape of human tumours. PMID:23894657

  19. Elevated Tolerance to Aneuploidy in Cancer Cells: Estimating the Fitness Effects of Chromosome Number Alterations by In Silico Modelling of Somatic Genome Evolution

    PubMed Central

    Valind, Anders; Jin, Yuesheng; Gisselsson, David

    2013-01-01

    An unbalanced chromosome number (aneuploidy) is present in most malignant tumours and has been attributed to mitotic mis-segregation of chromosomes. However, recent studies have shown a relatively high rate of chromosomal mis-segregation also in non-neoplastic human cells, while the frequency of aneuploid cells remains low throughout life in most normal tissues. This implies that newly formed aneuploid cells are subject to negative selection in healthy tissues and that attenuation of this selection could contribute to aneuploidy in cancer. To test this, we modelled cellular growth as discrete time branching processes, during which chromosome gains and losses were generated and their host cells subjected to selection pressures of various magnitudes. We then assessed experimentally the frequency of chromosomal mis-segregation as well as the prevalence of aneuploid cells in human non-neoplastic cells and in cancer cells. Integrating these data into our models allowed estimation of the fitness reduction resulting from a single chromosome copy number change to an average of ≈30% in normal cells. In comparison, cancer cells showed an average fitness reduction of only 6% (p = 0.0008), indicative of aneuploidy tolerance. Simulations based on the combined presence of chromosomal mis-segregation and aneuploidy tolerance reproduced distributions of chromosome aberrations in >400 cancer cases with higher fidelity than models based on chromosomal mis-segregation alone. Reverse engineering of aneuploid cancer cell development in silico predicted that aneuploidy intolerance is a stronger limiting factor for clonal expansion of aneuploid cells than chromosomal mis-segregation rate. In conclusion, our findings indicate that not only an elevated chromosomal mis-segregation rate, but also a generalised tolerance to novel chromosomal imbalances contribute to the genomic landscape of human tumours. PMID:23894657

  20. 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.

  1. 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

    2016-03-01

    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. PMID:26885566

  2. Prehepatic secretion and disposal of insulin in obese adolescents as estimated by three-hour, eight-sample oral glucose tolerance tests.

    PubMed

    Vogt, Josef A; Domzig, Christian; Wabitsch, Martin; Denzer, Christian

    2016-07-01

    The body compensates for early-stage insulin resistance by increasing insulin secretion. A reliable and easy-to-use mathematical assessment of insulin secretion and disposal could be a valuable tool for identifying patients at risk for the development of type 2 diabetes. Because the pathophysiology of insulin resistance is incompletely understood, assessing insulin metabolism with minimal assumptions regarding its metabolic regulation is a major challenge. To assess insulin secretion and indexes of insulin disposal, our marginalized and regularized absorption approach (MRA) was applied to a sparse sampling oral glucose tolerance test (OGTT) protocol measuring the insulin and C-peptide concentrations. Identifiability and potential bias of metabolic parameters were estimated from published data with dense sampling. The MRA was applied to OGTT data from 135 obese adolescents to demonstrate its clinical applicability. Individual prehepatic basal and dynamic insulin secretion and clearance levels were determined with a precision and accuracy greater than 10% of the nominal value. The intersubject variability in these parameters was approximately four times higher than the intrasubject variability, and there was a strong negative correlation between prehepatic secretion and plasma clearance of insulin. MRA-based analysis provides reliable estimates of insulin secretion and clearance, thereby enabling detailed glucose homeostasis characterization based on restricted datasets that are obtainable during routine patient care. PMID:27143555

  3. Dietary intake of PCDDs/PCDFs and coplanar PCBs among the Japanese population estimated by duplicate portion analysis: a low proportion of adults exceed the tolerable daily intake.

    PubMed

    Arisawa, Kokichi; Uemura, Hirokazu; Hiyoshi, Mineyoshi; Satoh, Hiroshi; Sumiyoshi, Yoshio; Morinaga, Kenji; Kodama, Kazunori; Suzuki, Taka-ichiro; Nagai, Masaki; Suzuki, Tsuguyoshi

    2008-10-01

    Dietary intake of dioxins was estimated by duplicate portion analysis of consecutive 3-day food samples among 86 men and 288 women (aged 17-72 years), who were living in 75 different areas of 25 prefectures in Japan. The mean (median) intake of PCDDs+PCDFs, coplanar PCBs (co-PCBs), and total dioxins, expressed on the basis of toxicity equivalents (TEQ), was 0.46 (0.34), 0.59 (0.39), and 1.06 (0.79)pg/kg body weight/day, respectively. Dietary intake was highest in fishing areas, followed by farming and urban areas. In multiple regression analysis, TEQs of PCDDs+PCDFs, co-PCBs, and total dioxins were positively associated with age and intake amount of fish and shellfish, and milk and dairy products, and negatively associated with survey year. There were significant positive correlations between dietary intake and blood levels for TEQs of PCDDs+PCDFs, co-PCBs, and total dioxins (Pearson r=0.35-0.36). The proportion of those whose dietary intake exceeded the tolerable daily intake (TDI), set by the World Health Organization (4pg TEQ/kg/day) and European Union (2pg TEQ/kg/day), was estimated at 2.1% and 10.4%, respectively. However, these proportions were considered to be overestimated because of the effect of day-to-day within-person variation. Therefore, the ratio of within- and between-person variance was estimated by applying random effects one-way analysis of variance to repeated measurements for another group of 35 persons. When the effect of within-person variation of dietary intake was accounted for, the proportion of subjects whose long-term intake exceeded the TDI of WHO and EU decreased to 0.06% and 2.9%, respectively. PMID:18692182

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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)

  9. 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. PMID:19292030

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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).

  16. Transplantation tolerance.

    PubMed

    Salisbury, Emma M; Game, David S; Lechler, Robert I

    2014-12-01

    Although transplantation has been a standard medical practice for decades, marked morbidity from the use of immunosuppressive drugs and poor long-term graft survival remain important limitations in the field. Since the first solid organ transplant between the Herrick twins in 1954, transplantation immunology has sought to move away from harmful, broad-spectrum immunosuppressive regimens that carry with them the long-term risk of potentially life-threatening opportunistic infections, cardiovascular disease, and malignancy, as well as graft toxicity and loss, towards tolerogenic strategies that promote long-term graft survival. Reports of "transplant tolerance" in kidney and liver allograft recipients whose immunosuppressive drugs were discontinued for medical or non-compliant reasons, together with results from experimental models of transplantation, provide the proof-of-principle that achieving tolerance in organ transplantation is fundamentally possible. However, translating the reconstitution of immune tolerance into the clinical setting is a daunting challenge fraught with the complexities of multiple interacting mechanisms overlaid on a background of variation in disease. In this article, we explore the basic science underlying mechanisms of tolerance and review the latest clinical advances in the quest for transplantation tolerance. PMID:24213880

  17. 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. PMID:26272653

  18. 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…

  19. 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. PMID:8051515

  20. 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. PMID:25503327

  1. 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. PMID:25016556

  2. 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.

  3. 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).

  4. 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. PMID:26650826

  5. 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)

  6. 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. PMID:26645235

  7. An aircraft sensor fault tolerant system

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    The design of a sensor fault tolerant system which uses analytical redundancy for the Terminal Configured Vehicle (TCV) research aircraft in a Microwave Landing System (MLS) environment was studied. The fault tolerant system provides reliable estimates for aircraft position, velocity, and attitude in the presence of possible failures in navigation aid instruments and onboard sensors. The estimates, provided by the fault tolerant system, are used by the automated guidance and control system to land the aircraft along a prescribed path. Sensor failures are identified by utilizing the analytic relationship between the various sensor outputs arising from the aircraft equations of motion.

  8. Intelligent fault-tolerant controllers

    NASA Technical Reports Server (NTRS)

    Huang, Chien Y.

    1987-01-01

    A system with fault tolerant controls is one that can detect, isolate, and estimate failures and perform necessary control reconfiguration based on this new information. Artificial intelligence (AI) is concerned with semantic processing, and it has evolved to include the topics of expert systems and machine learning. This research represents an attempt to apply AI to fault tolerant controls, hence, the name intelligent fault tolerant control (IFTC). A generic solution to the problem is sought, providing a system based on logic in addition to analytical tools, and offering machine learning capabilities. The advantages are that redundant system specific algorithms are no longer needed, that reasonableness is used to quickly choose the correct control strategy, and that the system can adapt to new situations by learning about its effects on system dynamics.

  9. 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. PMID:24811891

  10. 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. PMID:25042075

  11. 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. PMID:15000607

  12. 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.

  13. 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.

  14. Normothermic central hypovolemia tolerance reflects hyperthermic tolerance

    PubMed Central

    Schlader, Zachary J.

    2016-01-01

    Purpose To test the hypothesis that those who are highly tolerant to lower body negative pressure (LBNP) while normothermic are also highly tolerant to this challenge while hyperthermic. Methods Sixty pairs of normothermic and hyperthermic LBNP tests to pre-syncope were evaluated. LBNP tolerance was quantified via the cumulative stress index (CSI), which is calculated as the sum of the product of the LBNP level and the duration of each level until test termination (i.e., 20 mmHg × 3 min + 30 mmHg × 3 min, etc.). CSI was compared between normothermic and hyperthermic trials. Internal and skin temperatures, heart rate, and arterial pressure were measured throughout. Results Hyperthermia reduced (P<0.001) CSI from 997 ± 437 to 303 ± 213 mmHg min. There was a positive correlation between normothermic and hyperthermic LBNP tolerance (R2 = 0.38; P<0.001). As a secondary analysis, the 20 trials with the highest LBNP tolerance while normothermic were identified (indicated as the HIGH group; CSI 1,467 ± 356 mmHg min), as were the 20 trials with the lowest normothermic tolerance (indicated as the LOW group; CSI 565 ± 166 mmHg min; P<0.001 between groups). While hyperthermia unanimously reduced CSI in both HIGH and LOW groups, in this hyperthermic condition CSI was ~threefold higher in the HIGH group (474 ± 226 mmHg min) relative to the LOW group (160 ± 115 mmHg min; P<0.001). Conclusions LBNP tolerance while hyperthermic is related to normothermic tolerance and, associated with this finding, those who have a high LBNP tolerance while normothermic remain relatively tolerant when hyperthermic. PMID:24700256

  15. 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. ...

  16. Temperature tolerance of bloater (Coregonus hoyi)

    USGS Publications Warehouse

    Edsall, Thomas A.; Rottiers, Donald V.; Brown, Edward H.

    1970-01-01

    Juvenile and young adult bloaters (Coregonus hoyi) were tested for tolerance to high temperatures. The ultimate upper lethal temperature of juvenile bloaters (26.75 C) appeared to be slightly higher than that of young adult bloaters, but was similar to that of juvenile ciscoes,Coregonus artedii (26.0 C), the only other North American coregonine for which a detailed description of temperature tolerance has been published.Regression equations are given that permit estimation of the thermal tolerance when the lethal temperatures are incompletely known. The estimated thermal tolerance of juvenile bloaters (617 units) was slightly less than that of the brook trout (Salvelinus fontinalis; 625 units), but was higher than that of other Salmonidae.

  17. 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)

  18. "Infectious" Transplantation Tolerance

    NASA Astrophysics Data System (ADS)

    Qin, Shixin; Cobbold, Stephen P.; Pope, Heather; Elliott, James; Kioussis, Dimitris; Davies, Joanna; Waldmann, Herman

    1993-02-01

    The maintenance of transplantation tolerance induced in adult mice after short-term treatment with nonlytic monoclonal antibodies to CD4 and CD8 was investigated. CD4^+ T cells from tolerant mice disabled naive lymphocytes so that they too could not reject the graft. The naive lymphocytes that had been so disabled also became tolerant and, in turn, developed the capacity to specifically disable other naive lymphocytes. This process of "infectious" tolerance explains why no further immunosuppression was needed to maintain long-term transplantation tolerance.

  19. 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

  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. 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.

  2. Isotopes of uranium and thorium, lead-210, and polonium-210 in the lungs of coal miners of Appalachia and the lungs and livers of residents of central Ohio

    SciTech Connect

    Gilbert, G.E.; Casella, V.R.; Bishop, C.T.; Aguirre, A.G.

    1985-10-21

    The lungs of twelve and the livers of three residents of central Ohio and the lungs of four coal miners of Appalachia were analyzed for uranium-238, uranium-234, thorium-230, lead-210, polonium-210, and thorium-232. Mean and median lung concentrations of uranium-238 and of uranium-234 in the lungs of central Ohioans were essentially the same and were equal to 4 fCi/g dry. Mean concentrations of these isotopes in the lungs of Appalachian coal miners were also essentially the same and were equal to 9 fCi/g. Little uranium was found in the liver. The median concentration of thorium-230 in the lungs of central Ohioans was also 4 fCi/g dry; however, the mean concentration was 8 fCi/g due to the relatively high concentration values in a few persons. The mean concentrations of this isotope in the lungs of central Ohioans and Appalachian coal miners were essentially the same; i.e. 8 fCi/g. The mean and median concentrations of thorium-232 in the lungs of central Ohioans were assentially the same and equal to 4 fCi/g. The mean concentration of this isotope in the lungs of Appalachian coal miners was 9 fCi/g. Little thorium was found in the liver. The mean concentrations of lead-210 in the lungs of the two populations were nearly equal and about 23 fCi/g dry. The mean liver/lung ratio of this isotope was essentially two, and the concentrations appeared to be positively correlated with smoking. Polonium-210 concentrations in the lungs were distributed into three sets of values which are described here as low (2-4 fCi/g), medium (20-30 fCi/g), and high (>100 fCi/g), and also appeared to be correlated with smoking. Mean liver concentrations of this irotope were nearly equal to the mean liver concentrations of lead-210 (50 as opposed to 47 fCi/g). 18 refs., 6 tabs.

  3. Tolerance bands for functional data.

    PubMed

    Rathnayake, Lasitha N; Choudhary, Pankaj K

    2016-06-01

    Often the object of inference in biomedical applications is a range that brackets a given fraction of individual observations in a population. A classical estimate of this range for univariate measurements is a "tolerance interval." This article develops its natural extension for functional measurements, a "tolerance band," and proposes a methodology for constructing its pointwise and simultaneous versions that incorporates both sparse and dense functional data. Assuming that the measurements are observed with noise, the methodology uses functional principal component analysis in a mixed model framework to represent the measurements and employs bootstrapping to approximate the tolerance factors needed for the bands. The proposed bands also account for uncertainty in the principal components decomposition. Simulations show that the methodology has, generally, acceptable performance unless the data are quite sparse and unbalanced, in which case the bands may be somewhat liberal. The methodology is illustrated using two real datasets, a sparse dataset involving CD4 cell counts and a dense dataset involving core body temperatures. PMID:26574904

  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. Frost tolerance in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When conducting studies to characterize and determine the underlying mechanisms for freezing tolerance, it is essential to take into account that the type and form of freezing injury varies with the species and its degree of freezing tolerance. There are at least seven different patterns of freezin...

  6. Moving Beyond Tolerance.

    ERIC Educational Resources Information Center

    Cirone, Bill

    2001-01-01

    Operating under the umbrella of the Santa Barbara County Education Office, the Beyond Tolerance Educational Center serves as a resource for educators. It provides county schools with information and programs that promote social awareness and tolerance while teaching kids the dangers of hatred and discrimination. (MLH)

  7. 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.

  8. Maize aluminum tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  9. Tolerance Induction in Liver.

    PubMed

    Karimi, M H; Geramizadeh, B; Malek-Hosseini, S A

    2015-01-01

    Liver is an exclusive anatomical and immunological organ that displays a considerable tolerance effect. Liver allograft acceptance is shown to occur spontaneously within different species. Although in human transplant patients tolerance is rarely seen, the severity level and cellular mechanisms of transplant rejection vary. Non-paranchymal liver cells, including Kupffer cells, liver sinusoidal endothelial cells, hepatic stellate cells, and resident dendritic cells may participate in liver tolerogenicity. The mentioned cells secret anti-inflammatory cytokines such as TGF-β and IL-10 and express negative co-stimulatory molecules like PD-L1 to mediate immunosuppression. Other mechanisms such as microchimerism, soluble major histocompatibility complex and regulatory T cells may take part in tolerance induction. Understanding the mechanisms involved in liver transplant rejection/tolerance helps us to improve therapeutic options to induce hepatic tolerance. PMID:26082828

  10. 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.

  11. 76 FR 27268 - Glyphosate; Pesticide Tolerance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-11

    ...) 305-5805. II. Summary of Petitioned-For Tolerance In the Federal Register of February 4, 2011 (76 FR... with glyphosate follows. In the Federal Register of April 8, 2011 (76 FR 19701) (FRL-8866- 8), EPA... estimated aggregate risks resulting from use of glyphosate, as discussed in the April 8, 2011 (76 FR...

  12. Tolerability and patient compliance.

    PubMed

    Roose, S P

    1999-01-01

    Currently available antidepressants interact with several types of receptors, which may explain both wanted and unwanted effects of these drugs. These effects are different and distinctive, and knowledge about them may help clinicians understand differences between compounds in terms of their tolerability profiles. Given roughly comparable efficacy, tolerability profile is the critical determinant in selecting an antidepressant medication for a particular patient. In addition, tolerability is inseparably linked to patient compliance, both in acute and long-term treatment, and ultimately to overall success of treatment. Refinement in pharmacologic profiles of all newly introduced antidepressants resulted in overall advantages in tolerability in comparison with older tricyclic compounds. However, differences in receptor interactions between antidepressants are directly reflected in tolerability (adverse event) profiles. Among new antidepressants, mirtazapine and the selective serotonin reuptake inhibitors share favorable overall tolerability and safety, especially with respect to low premature termination rates because of adverse events, cardiac safety, and safety in overdose. However, the different pharmacologic profile of mirtazapine is reflected in its different tolerability profile. Because of interactions with the histamine (H1) receptor, mirtazapine may be related to transient initial somnolence and weight gain in some patients. Its serotonin-2 (5-HT2)-blocking properties may account for lack of sexual dysfunction, insomnia, nervousness, and agitation. Mirtazapine's 5-HT3-blocking properties are unique among all currently available antidepressants and may account for lack of gastrointestinal adverse events. PMID:10446736

  13. Antimicrobial Tolerance in Biofilms.

    PubMed

    Stewart, Philip S

    2015-06-01

    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

  14. 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

  15. 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.

  16. [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. PMID:27337844

  17. 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.

  18. 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.

  19. DNA damage tolerance.

    PubMed

    Branzei, Dana; Psakhye, Ivan

    2016-06-01

    Accurate chromosomal DNA replication is fundamental for optimal cellular function and genome integrity. Replication perturbations activate DNA damage tolerance pathways, which are crucial to complete genome duplication as well as to prevent formation of deleterious double strand breaks. Cells use two general strategies to tolerate lesions: recombination to a homologous template, and trans-lesion synthesis with specialized polymerases. While key players of these processes have been outlined, much less is known on their choreography and regulation. Recent advances have uncovered principles by which DNA damage tolerance is regulated locally and temporally - in relation to replication timing and cell cycle stage -, and are beginning to elucidate the DNA dynamics that mediate lesion tolerance and influence chromosome structure during replication. PMID:27060551

  20. 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.

  1. 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

  2. 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.

  3. Pollution-induced community tolerance of freshwater biofilms: measuring heterotrophic tolerance to Pb using an enzymatic toxicity test.

    PubMed

    Fechner, Lise C; Dufour, Marine; Gourlay-Francé, Catherine

    2012-11-01

    This study aims at investigating the impacts of Pb on freshwater biofilms with a pollution-induced community tolerance (PICT) approach using a recently developed short-term toxicity test based on β-glucosidase activity to measure biofilms' tolerance to Pb. We first investigated more closely the influence of the total suspended solids (TSS) concentrations of biofilm suspensions used for short-term toxicity tests performed to assess Pb tolerance. The Pb EC(50) values of four dilutions of the same biofilm suspension increased with their TSS concentrations. TSS-normalization allowed to obtain a unique measure of Pb tolerance, thus confirming that TSS-normalization of EC(50) values is a good means to estimate biofilm tolerance to Pb. The experiment was repeated with three different biofilm samples collected at different sites and dates. Second, biofilms were exposed to Pb (0, 1, 10 and 100 μg/L) for 3 weeks in microcosms to assess the impacts of Pb exposure on the communities. An increase in Pb tolerance was observed for the biofilm exposed to 100 μg/L. Automated Ribosomal Intergenic Spacer Analysis revealed modifications of bacterial and eukaryotic community structure with Pb exposure. Moreover, exposure to 100 μg/L Pb also led to an increase in Zn tolerance but not Cu tolerance. This study shows that tolerance acquisition to Pb can be detected after exposure to environmental concentrations of Pb using a PICT methodology and normalized EC(50) values as measures of Pb tolerance. PMID:22729786

  4. Perceptual Tolerance Intersection

    NASA Astrophysics Data System (ADS)

    Wasilewski, Piotr; Peters, James F.; Ramanna, Sheela

    This paper elaborates on the introduction of perceptual tolerance intersection of sets as an example of a near set operation. Such operations are motivated by the need to consider similarities between digital images viewed as disjoint sets of points. The proposed approach is in keeping with work by E.C. Zeeman on tolerance spaces and visual perception and work by J.H. Poincaré on sets of similar sensations used to define representative spaces (aka tolerance spaces) such as visual, tactile and motile spaces. Perceptual tolerance intersection of sets is a direct consequence of recent work on near sets. The theory of perceptual set intersection has many practical applications such as a solution to the problem of how one goes about measuring the closeness of digital images. The main contribution of this article is a description-based approach to formulating perceptual set intersections between disjoint sets that resemble each other. A practical application of the proposed approach is the discovery of resemblances between sets of points in digital image regions that represent tolerance rough sets.

  5. 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.

  6. 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.

  7. Zero Tolerance Expulsions.

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    1999-01-01

    Most courts have flexibly interpreted the constitutional requirement of procedural and substantive due process in favor of zero-tolerance expulsion decisions. While being sensitive to community intolerance for threats to school safety (student possession of guns or drugs), school leaders should modulate development and enforcement of expulsion…

  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); "Out of the Shadows" (Elizabeth Hunt);…

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

    PubMed Central

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

    2013-01-01

    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. PMID:24187585

  10. Cuphea tolerates clopyralid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  11. 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. PMID:23340387

  12. 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.

  13. 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,…

  14. 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)

  15. 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)

  16. 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).

  17. 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

  18. 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.

  19. 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…

  20. 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.

  1. 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.

  2. Impurity tolerant electrocatalysts

    SciTech Connect

    Paffett, M.T.

    1990-01-01

    This project has two central goals. The primary research effort addresses fundamental aspects of Pt electrocatalyst poisoning by CO and an understanding of practical schemes for improving the CO tolerance of electrocatalytic materials. The second mission of this work is an attempt to address, on a fundamental level, the surface chemical properties that enhance the direct electrooxidation of methanol at binary Pt alloy electrode surfaces. 8 refs., 4 figs.

  3. 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

  4. Drought tolerance in wheat.

    PubMed

    Nezhadahmadi, Arash; 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

  5. 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.

  6. Damage tolerance for commuter aircraft

    NASA Technical Reports Server (NTRS)

    Lincoln, John W.

    1992-01-01

    The damage tolerance experience in the United States Air Force with military aircraft and in the commercial world with large transport category aircraft indicates that a similar success could be achieved in commuter aircraft. The damage tolerance process is described for the purpose of defining the approach that could be used for these aircraft to ensure structural integrity. Results of some of the damage tolerance assessments for this class of aircraft are examined to illustrate the benefits derived from this approach. Recommendations are given for future damage tolerance assessment of existing commuter aircraft and on the incorporation of damage tolerance capability in new designs.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. Tolerability of hypertonic injectables.

    PubMed

    Wang, Wei

    2015-07-25

    Injectable drug products are ideally developed as isotonic solutions. Often, hypertonic injectables may have to be marketed for a variety of reasons such as product solubilization and stabilization. A key concern during product formulation development is the local and systemic tolerability of hypertonic products upon injection. This report reviews and discusses the tolerability in terms of local discomfort, irritation, sensation of heat and pain, along with other observed side effects of hypertonicity in both in-vitro systems and in-vivo animal and human models. These side effects clearly depend on the degree of hypertonicity. The sensation of pain among different injection routes seems to follow this order: intramuscular>subcutaneous>intravenous or intravascular. It is recommended that the upper osmolality limit should be generally controlled under 600 mOsm/kg for drug products intended for intramuscular or subcutaneous injection. For drug products intended for intravenous or intravascular injection, the recommended upper limit should be generally controlled under 1,000 mOsm/kg for small-volume injections (≤ 100 mL) and 500 mOsm/kg for large-volume injections (>100mL). Several options are available for minimization of hypertonicity-induced pain upon product administration. PMID:26027488

  12. 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.

  13. Fault-tolerant processing system

    NASA Technical Reports Server (NTRS)

    Palumbo, Daniel L. (Inventor)

    1996-01-01

    A fault-tolerant, fiber optic interconnect, or backplane, which serves as a via for data transfer between modules. Fault tolerance algorithms are embedded in the backplane by dividing the backplane into a read bus and a write bus and placing a redundancy management unit (RMU) between the read bus and the write bus so that all data transmitted by the write bus is subjected to the fault tolerance algorithms before the data is passed for distribution to the read bus. The RMU provides both backplane control and fault tolerance.

  14. 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.

  15. 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.

  16. Comparative Expression Profiling of Desiccation Tolerant and Sensitive Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drought tolerance and desiccation tolerance have often been cited as manifestations of the same mechanism: desiccation tolerance being the extreme form of drought tolerance. However, there is a fundamental difference between drought and desiccation tolerance; drought tolerance mechanisms include way...

  17. 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.

  18. [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.

  19. Tolerances in panoramic lenses

    NASA Astrophysics Data System (ADS)

    Thibault, Simon; Dallaire, Xavier

    2014-09-01

    Almost every aspect concerning the optical design of panoramic lenses brings new challenges to optical designers. Examples of these include ray tracing programs having problems finding the entrance pupil which is moving through the field-of-view, optimization, production particularities due to the shape of the lenses, and ways of tolerancing these systems having strong distortion. This last topic will be discussed in this paper. We will start from a historical perspective on the understanding of panoramic imagery. This will lead us to the modern panoramic imager called the Panomorph lens. We will discuss the particular case of the tolerance of the front surface (most of the time a freeform surface) and the impact on the image quality, both image footprint and field curvature. We will explain the behavior using first and second order approaches.

  20. Plants tolerant of high boron levels.

    PubMed

    Miwa, Kyoko; Takano, Junpei; Omori, Hiroyuki; Seki, Motoaki; Shinozaki, Kazuo; Fujiwara, Toru

    2007-11-30

    Reduced crop productivity due to soils containing toxic levels of boron (B) is a worldwide problem in food production. It is estimated that up to 17% of the barley yield losses in southern Australia are caused by B toxicity. We found that the expression of AtBOR4, an Arabidopsis paralog of BOR1, the first identified boron transporter gene, generates plants that are tolerant of high B levels. BOR4 is a polarly localized borate exporter that enhances B efflux from roots. The present study is a foundation for the improvement of crop productivity in soils containing excess B, which are distributed in arid areas of the world. PMID:18048682

  1. Evolution of tolerance by magpies to brood parasitism by great spotted cuckoos.

    PubMed

    Soler, J J; Martín-Gálvez, D; Martínez, J G; Soler, M; Canestrari, D; Abad-Gómez, J M; Møller, A P

    2011-07-01

    Hosts may use two different strategies to ameliorate negative effects of a given parasite burden: resistance or tolerance. Although both resistance and tolerance of parasitism should evolve as a consequence of selection pressures owing to parasitism, the study of evolutionary patterns of tolerance has traditionally been neglected by animal biologists. Here, we explore geographical covariation between tolerance of magpies (Pica pica) and brood parasitism by the great spotted cuckoo (Clamator glandarius) in nine different sympatric populations. We estimated tolerance as the slope of the regression of number of magpie fledglings (i.e. host fitness) on number of cuckoo eggs laid in non-depredated nests (which broadly equals parasite burden). We also estimated prevalence of parasitism and level of host resistance (i.e. rejection rates of mimetic model eggs) in these nine populations. In accordance with the hypothetical role of tolerance in the coevolutionary process between magpies and cuckoos we found geographical variation in tolerance estimates that positively covaried with prevalence of parasitism. Levels of resistance and tolerance were not associated, possibly suggesting the lack of a trade-off between the two kinds of defences against great spotted cuckoo parasitism for magpies. We discuss the results in the framework of a mosaic of coevolutionary interactions along the geographical distribution of magpies and great spotted cuckoos for which we found evidence that tolerance plays a major role. PMID:21123258

  2. 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 School" (R. Rhodes, D.…

  3. Plant salt-tolerance mechanisms

    DOE PAGESBeta

    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 selectionmore » and gene stacking techniques. We also identify key open questions that remain to be addressed in the future.« less

  4. 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.

  5. A historical perspective on cold tolerance in the Canal Point Sugarcane Breeding Program

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Developing sugarcane cultivars with greater freeze tolerance is an important objective of the USDA-ARS Canal Point breeding program, as temperatures around -3oC (27oF) cause serious sugar yield losses during the harvest season. To estimate if progress was made in freeze tolerance by breeding for can...

  6. Pitted and Hybrid Morningglory Accessions Have Variable Tolerance to Glyphosate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Greenhouse studies were conducted to investigate the variability in tolerance to glyphosate among 38 accessions of pitted morningglory collected from several southern United States. Glyphosate at 420 g ae/ha was applied postemergence to plants at 4- to 5-leaf stage and control was visually estimated...

  7. 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.

  8. [Immune tolerance after renal transplantation].

    PubMed

    Krajewska, Magdalena; Weyde, Wacław; Klinger, Marian

    2006-01-01

    Progress in immunosuppressive therapy has improved short-term survival of renal allografts by decreasing the frequency of acute rejections. However, the long-term survival of renal grafts has not improved. Transplanted kidneys are lost in the late period after transplantation as a result of vasculopathy and chronic rejection. Immunological tolerance means the lack of immunological activity towards certain antigens while the response towards others remains correct. The induction of immunological tolerance of donor antigens (transplant tolerance) is examined intensively to work out treatment methods which will allow prevention of chronic allograft rejection. The paper includes an overview of current knowledge on allograft tolerance. Immune response to alloantigens is described and the mechanisms of immunological tolerance induction (including clonal deletion, anergy connected with the microchimerism phenomenon, and active suppression caused by regulatory lymphocytes) are characterized. The role of dendritic cells in the process of inducing and maintaining tolerance is highlighted. Tolerance-inducing strategies in renal transplant recipients and clinically applied evaluation methods are presented. At present, optimizing recipient matching is used to decrease the risk of graft rejection. Hopefully, gene therapy will be possible in the near future. However, before introducing such a procedure into clinical studies, optimal therapy conditions and risk evaluation must be defined in tests on animals. PMID:16552396

  9. Genetic analysis of tolerance to infections using random regressions: a simulation study.

    PubMed

    Kause, Antti

    2011-08-01

    Tolerance to infections is the ability of a host to limit the impact of a given pathogen burden on host performance. This simulation study demonstrated the merit of using random regressions to estimate unbiased genetic variances for tolerance slope and its genetic correlations with other traits, which could not be obtained using the previously implemented statistical methods. Genetic variance in tolerance was estimated as genetic variance in regression slopes of host performance along an increasing pathogen burden level. Random regressions combined with covariance functions allowed genetic variance for host performance to be estimated at any point along the pathogen burden trajectory, providing a novel means to analyse infection-induced changes in genetic variation of host performance. Yet, the results implied that decreasing family size as well as a non-zero environmental or genetic correlation between initial host performance before infection and pathogen burden led to biased estimates for tolerance genetic variance. In both cases, genetic correlation between tolerance slope and host performance in a pathogen-free environment became artificially negative, implying a genetic trade-off when it did not exist. Moreover, recording a normally distributed pathogen burden as a threshold trait is not a realistic way of obtaining unbiased estimates for tolerance genetic variance. The results show that random regressions are suitable for the genetic analysis of tolerance, given suitable data structure collected either under field or experimental conditions. PMID:21767462

  10. 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. PMID:27449401

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

    NASA Astrophysics Data System (ADS)

    Tesar, Delbert

    1993-02-01

    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.

  12. 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

  13. Freeze-Tolerant Condensers

    NASA Technical Reports Server (NTRS)

    Crowley, Christopher J.; Elkouhk, Nabil

    2004-01-01

    Two condensers designed for use in dissipating heat carried by working fluids feature two-phase, self-adjusting configurations such that their working lengths automatically vary to suit their input power levels and/or heat-sink temperatures. A key advantage of these condensers is that they can function even if the temperatures of their heat sinks fall below the freezing temperatures of their working fluids and the fluids freeze. The condensers can even be restarted from the frozen condition. The top part of the figure depicts the layout of the first condenser. A two-phase (liquid and vapor) condenser/vapor tube is thermally connected to a heat sink typically, a radiatively or convectively cooled metal panel. A single-phase (liquid) condensate-return tube (return artery) is also thermally connected to the heat sink. At intervals along their lengths, the condenser/vapor tube and the return artery are interconnected through porous plugs. This condenser configuration affords tolerance of freezing, variable effective thermal conductance (such that the return temperature remains nearly constant, independently of the ultimate sink temperature), and overall pressure drop smaller than it would be without the porous interconnections. An additional benefit of this configuration is that the condenser can be made to recover from the completely frozen condition either without using heaters, or else with the help of heaters much smaller than would otherwise be needed. The second condenser affords the same advantages and is based on a similar principle, but it has a different configuration that affords improved flow of working fluid, simplified construction, reduced weight, and faster recovery from a frozen condition.

  14. Accident tolerant fuel analysis

    SciTech Connect

    Smith, Curtis; Chichester, Heather; Johns, Jesse; Teague, Melissa; Tonks, Michael Idaho National Laboratory; Youngblood, Robert

    2014-09-01

    Safety is central to the design, licensing, operation, and economics of Nuclear Power Plants (NPPs). Consequently, the ability to better characterize and quantify safety margin holds the key to improved decision making about light water reactor design, operation, and plant life extension. A systematic approach to characterization of safety margins and the subsequent margins management options represents a vital input to the licensee and regulatory analysis and decision making that will be involved. The purpose of the Risk Informed Safety Margin Characterization (RISMC) Pathway research and development (R&D) is to support plant decisions for risk-informed margins management by improving economics and reliability, and sustaining safety, of current NPPs. Goals of the RISMC Pathway are twofold: (1) Develop and demonstrate a risk-assessment method coupled to safety margin quantification that can be used by NPP decision makers as part of their margin recovery strategies. (2) Create an advanced ''RISMC toolkit'' that enables more accurate representation of NPP safety margin. In order to carry out the R&D needed for the Pathway, the Idaho National Laboratory is performing a series of case studies that will explore methods- and tools-development issues, in addition to being of current interest in their own right. One such study is a comparative analysis of safety margins of plants using different fuel cladding types: specifically, a comparison between current-technology Zircaloy cladding and a notional ''accident-tolerant'' (e.g., SiC-based) cladding. The present report begins the process of applying capabilities that are still under development to the problem of assessing new fuel designs. The approach and lessons learned from this case study will be included in future Technical Basis Guides produced by the RISMC Pathway. These guides will be the mechanism for developing the specifications for RISMC tools and for defining how plant decision makers should propose and

  15. 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.

  16. 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.

  17. 76 FR 5704 - Sulfentrazone; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-02

    ...This regulation establishes tolerances for residues of sulfentrazone in or on multiple commodities. Additionally, this regulation deletes existing tolerances on commodities superseded by the establishment of crop subgroups. This regulation also deletes a time- limited tolerance on bean, succulent seed without pod (lima bean and cowpea), as the tolerance expired on December 31, 2007.......

  18. Glucose tolerance test - non-pregnant

    MedlinePlus

    Oral glucose tolerance test - non-pregnant; OGTT - non-pregnant; Diabetes - glucose tolerance test ... The most common glucose tolerance test is the oral glucose tolerance test (OGTT). Before the test begins, a sample of blood will be taken. You will then ...

  19. 78 FR 55635 - Prometryn; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-11

    ...This regulation establishes tolerances for residues of prometryn in or on succulent snap bean, dill oil, fresh dillweed leaves, and dried dillweed leaves. This regulation additionally removes the established tolerance with regional restrictions on dill, since it is superseded by the tolerance on fresh dillweed leaves. Interregional Research Project Number 4 (IR-4) requested these tolerances......

  20. Combining dynamical decoupling with fault-tolerant quantum computation

    SciTech Connect

    Ng, Hui Khoon; Preskill, John; Lidar, Daniel A.

    2011-07-15

    We study how dynamical decoupling (DD) pulse sequences can improve the reliability of quantum computers. We prove upper bounds on the accuracy of DD-protected quantum gates and derive sufficient conditions for DD-protected gates to outperform unprotected gates. Under suitable conditions, fault-tolerant quantum circuits constructed from DD-protected gates can tolerate stronger noise and have a lower overhead cost than fault-tolerant circuits constructed from unprotected gates. Our accuracy estimates depend on the dynamics of the bath that couples to the quantum computer and can be expressed either in terms of the operator norm of the bath's Hamiltonian or in terms of the power spectrum of bath correlations; we explain in particular how the performance of recursively generated concatenated pulse sequences can be analyzed from either viewpoint. Our results apply to Hamiltonian noise models with limited spatial correlations.

  1. 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

  2. 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.

  3. 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.

  4. 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. PMID:26292981

  5. Organ-specific Differences in Achieving Tolerance

    PubMed Central

    Madariaga, Maria Lucia L.; Kreisel, Daniel; Madsen, Joren C.

    2015-01-01

    Purpose of review When it comes to tolerance induction, kidney allografts behave differently from heart allografts which behave differently from lung allografts. Here, we examine how and why different organ allografts respond differently to the same tolerance induction protocol. Recent findings Allograft tolerance has been achieved in experimental and clinical kidney transplantation. However, inducing tolerance in experimental recipients of heart and lung allografts has proven to be more challenging. New protocols being developed in nonhuman primates based on mixed chimerism and co-transplantation of tolerogenic organs may provide mechanistic insights to help overcome these challenges. Summary Tolerance induction protocols that are successful in patients transplanted with “tolerance-prone” organs such as kidneys and livers will most likely not succeed in recipients of “tolerance-resistant” organs such as hearts and lungs. Separate clinical trials using more robust tolerance protocols will be required to achieve tolerance in heart and lung recipients. PMID:26147678

  6. Lessons on dehydration tolerance from desiccation tolerant plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extremophiles: organisms that thrive (a relative term) in environments where conditions are such that the majority of organisms cannot survive. This is not strictly true if one is describing desiccation-tolerant plants, as other plants do grow around them, but it is certainly true that they can surv...

  7. 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.

  8. 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.

  9. 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.

  10. 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…

  11. 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…

  12. B cells and immunological tolerance.

    PubMed

    Manjarrez-Orduño, Nataly; Quách, Tâm D; Sanz, Iñaki

    2009-02-01

    Work from multiple groups continues to provide additional evidence for the powerful and highly diverse roles, both protective and pathogenic, that B cells play in autoimmune diseases. Similarly, it has become abundantly clear that antibody-independent functions may account for the opposing influences that B cells exercise over other arms of the immune response and ultimately over autoimmunity itself. Finally, it is becoming apparent that the clinical impact of B-cell depletion therapy may be, to a large extent, determined by the functional balance between different B-cell subsets that may be generated by this therapeutic intervention. In this review, we postulate that our perspective of B-cell tolerance and our experimental approach to its understanding are fundamentally changed by this view of B cells. Accordingly, we first discuss current knowledge of B-cell tolerance conventionally defined as the censoring of autoantibody-producing B cells (with an emphasis on human B cells). Therefore, we discuss a different model that contemplates B cells not only as targets of tolerance but also as mediators of tolerance. This model is based on the notion that the onset of clinical autoimmune disease may require a B-cell gain-of-pathogenic function (or a B-cell loss-of-regulatory-function) and that accordingly, disease remission may depend on the restoration of the physiological balance between B-cell pathogenic and protective functions. PMID:19148217

  13. 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)

  14. Sugarcane Genotype Tolerance to Wireworms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugarcane (interspecific hybrids of Saccharum spp.) growers in Florida normally apply a soil insecticide at planting to limit wireworm (Melanotus communis Gyllenhall) damage to seed cane (vegetative plantings of stalks). The objective of this study was to measure the tolerance of eight commercial su...

  15. 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.

  16. "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)

  17. 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.…

  18. 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…

  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. 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…

  1. 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.

  2. 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.

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 78 FR 23497 - Propiconazole; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-19

    ...This regulation amends existing tolerances for residues of propiconazole in or on multiple commodities which are identified and discussed later in this document. Syngenta Crop Protection, LLC requested these tolerances under the Federal Food, Drug, and Cosmetic Act...

  9. 76 FR 69648 - Trifloxystrobin; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-09

    ...This regulation establishes tolerances for residues of trifloxystrobin in or on alfalfa, forage and alfalfa, hay. Bayer CropScience requested these tolerances under the Federal Food, Drug, and Cosmetic Act...

  10. 7 CFR 51.1861 - Tolerances.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Fresh Tomatoes 1 Tolerances § 51.1861 Tolerances. In... percent for tomatoes which are green in color, when any term other than “Green” is specified....