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Sample records for chromatid exchange induction

  1. Induction of sister chromatid exchanges by coal dust and tobacco snuff extracts in human peripheral lymphocytes

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    Tucker, J.D.; Ong, T.

    1985-01-01

    The organic solvent extracts of sub-bituminous coal dust and tobacco snuff, both together and separately, were tested for the induction of sister chromatid exchanges (SCEs) in human peripheral lymphocytes. The results indicate that these extracts induced SCEs, and that when tested together synergistically induced SCEs in two of three donors. Studies with the organic solvent extracts of all five ranks of coal indicate that the extracts of bituminous, lignite, and peat, but not anthracite, induced SCEs. Similar experiments conducted with water extracts, induced SCEs, and that anthracite was equivocal. To determine whether individuals differed in their SCE responses to coal dust extracts, lymphocytes from five donors were tested with organic solvent extracts of bituminous and sub-bituminous coal. An analysis of variance indicates that the SCE response was significantly influenced by the donor and each of the two coal extracts. The findings presented here suggest that coal dust, with or without tobacco snuff, may play a role in the elevated incidence of gastric cancer in coal miners. Because water extracts of some ranks of coal induced SCEs, there exists the possibility of adverse environmental effects due to coal leachates.

  2. Iron-mediated induction of sister-chromatid exchanges by hydrogen peroxide and superoxide anion.

    Science.gov (United States)

    Larramendy, M; Mello-Filho, A C; Martins, E A; Meneghini, R

    1987-05-01

    When Chinese hamster fibroblasts were exposed to hydrogen peroxide or to a system consisting of xanthine oxidase and hypoxanthine, which generates superoxide anion plus hydrogen peroxide, sister-chromatid exchanges (SCEs) were formed in a dose-dependent manner. When the iron-complexing agent o-phenanthroline was present in the medium, however, the production of these SCEs was completely inhibited. This fact indicates that the Fenton reaction: Fe2+ + H2O2----OH0 + OH- + Fe3+ is responsible for the production of SCEs. When O2- and H2O2 were generated inside the cell by incubation with menadione, the production of SCE was prevented by co-incubation with copper diisopropylsalicylate, a superoxide dismutase mimetic agent. The most likely role of O2- is as a reducing agent of Fe3+: O2- + Fe3+----Fe2+ + O2, so that the sum of this and the Fenton reaction, i.e., the iron-catalyzed Haber-Weiss reaction, provides an explanation for the active oxygen species-induced SCE: H2O2 + O2(-)----OH- + OH0 + O2. According to this view, the OH radical thus produced is the agent which ultimately causes SCE. These results are discussed in comparison with other mechanisms previously proposed for induction of SCE by active oxygen species.

  3. Susceptibility to induction of chromosomal damage by metabolites of 1,3-butadiene and its relationship to 'spontaneous' sister chromatid exchange frequencies in human lymphocytes.

    Science.gov (United States)

    Wiencke, J K; Kelsey, K T

    1993-01-01

    Occupational exposure to butadiene is associated with the occurrence of lymphohaematopoietic cancers. The mutagenicity of butadiene is thought to be mediated by its mono- and diepoxide metabolites, which are capable of binding to DNA. Diepoxybutane is the most potent genotoxic metabolite and is known to produce interstrand DNA cross-links. In order to study individual differences in response to the genotoxicity of diepoxybutane, we devised a human lymphocyte culture system that involves short-term culture of T lymphocytes and measurement of sister chromatid exchange (SCE) and chromosomal aberration frequency as genotoxic end-points. We observed that when lymphocytes from healthy individuals are exposed in vitro to 6 microM of diepoxybutane, the number of SCEs induced is distributed bimodally: about 20% of 173 healthy workers studied were twice as sensitive to the induction of SCEs as the remaining 80%. Cells from sensitive individuals also contain four times more diepoxybutane-induced chromosomal deletions and exchanges. Of particular interest is the observation that diepoxybutane-sensitive individuals have higher frequencies of baseline (i.e., uninduced) SCEs. We have now examined the sensitivity of individual lymphocytes to SCE induction by another DNA cross-linking agent (nitrogen mustard) and to monoepoxybutene. The results indicate that lymphocytes sensitive to diepoxybutane-induced SCEs have normal sensitivity to nitrogen mustard and a moderately increased response to the monofunctional agent monoepoxybutene. Measurement of diepoxybutane-induced SCEs is a potential biomarker of sensitivity to the genotoxic effects of butadiene and may be useful in occupational epidemiological studies. Such studies, in combination with measures of butadiene metabolism, could be useful in ascertaining whether the sensitivity is mediated by enzyme polymorphisms.

  4. Evaluation of the persistence in the induction of Sister Chromatid Exchanges (SCE) by alkylating agents; Evaluacion de la persistencia en la induccion de Intercambio en las Cromatidas Hermanas (ICH) por agentes alquilantes

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    Rodriguez R, R.; Huerta V, C.; MOrales R, P.R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2006-07-01

    The persistence in the induction of sister chromatid exchanges (SCE) by the alkylating agents methyl and ethyl-methanesulfonates (MMS and EMS) was evaluated. For it, to groups of mice its were administered a dose of these agents and later its were analyzed the induced SCE's in two periods: early and late. Both agents caused high increments of SCE in the early period and small in the late one; however, the caused lately by EMS was significantly bigger. This late induction of SCE by EMS possibly is associated with an epigenetic change or with the presence of etiladucts in the phosphodiester bonds of the DNA. (Author)

  5. In vitro Antigenotoxicity of Ulva rigida C.Agardh (Chlorophyceae) Extract against Induction of Chromosome Aberration,Sister Chromatid Exchange and Micronuclei by Mutagenic Agent MMC

    Institute of Scientific and Technical Information of China (English)

    SERAP CELIKLER; GAMZE YILDIZ; OZGUR VATAN; RAHMI BILALOGLU

    2008-01-01

    To determine the in vitro possible clastogenic and cytotoxic activities of Uh,a rigida crude extracts (UP,E),and identify their antigenotoxic and protective effects on chemotherapeutic agent mitomycine-C (MMC).Methods Anti-clastogenic and anti-genotoxic activities of Ulva rigida crude extracts (URE) were studied using chromosome aberration (CA),sister chromatid exchange (SCE),and micronuclei (MN) tests in human lymphocytes cultured in vitro.Results The chromosome aberration,sister chromatid exchange or micronuclei tests showed that URE at concentrations of 10,20,and 40 μg/mL had no clastogenic activity in human lymphocyte cell culture.Three doses of URE significantly decreased the number of chromosomal aberrations and the frequencies of SCE and MN when compared with the culture treated with MMC (P<0.0001).Conclusion Although URE itself is not a clastogenic or cytotoxic substance,it possesses strong antigenotoxic,anti-clastogenic,and protective effects on MMC in vitro.

  6. Induction of micronuclei and sister chromatid exchange in bone-marrow cells and abnormalities in sperm of Algerian mice (Mus spretus) exposed to cadmium, lead and zinc.

    Science.gov (United States)

    Tapisso, Joaquim Torres; Marques, Carla Cristina; Mathias, Maria da Luz; Ramalhinho, Maria da Graça

    2009-08-01

    As a consequence of human activities, large amounts of cadmium, lead and zinc are released in the environment, often simultaneously. The aim of this study was to investigate under experimental conditions the DNA damage induced in Algerian mice (Mus spretus) exposed to cadmium (Cd), lead (Pb) and zinc (Zn) separately, or in selected combinations. Three cytogenetic end points were considered: the frequencies of micronucleated cells (MN) and sister chromatid exchange (SCE) in the bone marrow and the frequency of sperm abnormalities. Mice were treated by intraperitoneal (i.p.) injections with 5 or 10 doses of aqueous solutions of cadmium acetate, lead acetate and zinc acetate in concentrations corresponding to 1/10 of the LD50, respectively, 21.5, 0.46 and 1.5 mg/kg bw. The control groups were injected in the same way with distilled water. With only one exception (Cd + Zn group treated with 5 doses), the results show a significant increase of MN in all groups for both treatments (5 and 10 doses). Similarly, the results concerning the SCE revealed a statistically significant increase in all treated animals, with the exception of the Zn group treated with 5 doses. The number of sperm abnormalities was significantly higher in animals treated with 5 doses, except in the group Pb + Zn. In animals treated with 10 doses the number of sperm abnormalities was always statistically higher compared with controls. This study indicates that cadmium, lead and zinc can induce MN, SCEs and sperm abnormalities in Algerian mice and that the clastogenic potential is dependent on the time of exposure and the interaction between the three elements, confirming the environmental damage that may result from the simultaneous action of several metals. Most relevant is the toxic potential for Zn, related with the dose, which may compromise its protective effect against other metal contaminations, such as cadmium.

  7. Targeting of chemical mutagens to differentiating B-lymphocytes in vivo: detection by direct DNA labeling and sister chromatid exchange induction

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    Bloom, S.E.; Nanna, U.C.; Dietert, R.R.

    1987-01-01

    In vivo systems for analyzing mutagen interactions with a specific differentiating cell population are rare. Taking advantage of the unique anatomical features of the bursa of Fabricius in the chicken, the authors explored the possibility of targeting chemical mutagens to a defined differentiating cell population in the animal, namely, the B-lymphocytes series. Such cells are known to be the targets for the oncogene-activating avian leukosis virus. Targeting of chemicals to cells of the bursa was demonstrated by application of the DNA-specific fluorochrome 4'-6-diamidino-2-phenylindole (DAPI) to the anal lips of neonatal chicks. Bright nuclear fluorescence of cells in the bursa demonstrated to occur within minutes after the application of 500..mu..l of DAPI. DAPI labeling of nuclei was detected up to several days after a single application. No nuclear labeling was exhibited in cells of neighboring tissues. Methyl methanesulfonate (MMS)(10..mu..l) was applied to the anal lips of day-old chicks to study dose-response kinetics for mutagen targeting to DNA of dividing B-lymphocytes in the bursa. Since the mitotic index was found to be quite high (25-30%) in the bursa, chromosome analysis was used to assay for genome damage. Sister chromatid exchange frequencies of 3.9, 7.3, and 9.0 (baseline 2.5) per cell were obtained at MMS dosages per animal of 50 ..mu..g, 100..mu..g, and 200..mu..g, respectively. These results indicate the rapid and quantitative localization of DNA-binding chemicals to cells of the bursa, particularly the resident B-lymphocytes. The bursa should be a useful system for studying mutagen-DNA interactions in the differentiating B-lymphocyte and subsequent influences on the development of immunity and lymphoproliferative disease.

  8. Solution Radioactivated by Hadron Radiation Can Increase Sister Chromatid Exchanges.

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    Maeda, Junko; Yurkon, Charles R; Fujii, Yoshihiro; Fujisawa, Hiroshi; Kato, Sayaka; Brents, Colleen A; Uesaka, Mitsuru; Fujimori, Akira; Kitamura, Hisashi; Kato, Takamitsu A

    2015-01-01

    When energetic particles irradiate matter, it becomes activated by nuclear reactions. Radioactivation induced cellular effects are not clearly understood, but it could be a part of bystander effects. This investigation is aimed at understanding the biological effects from radioactivation in solution induced by hadron radiation. Water or phosphate buffered saline was activated by being exposed to hadron radiation including protons, carbon- and iron-ions. 1 mL of radioactivated solution was transferred to flasks with Chinese hamster ovary (CHO) cells cultured in 5 mL of complete media. The induction of sister chromatid exchanges (SCE) was used to observe any increase in DNA damage responses. The energy spectrum and the half-lives of the radioactivation were analyzed by NaI scintillation detector in order to identify generated radionuclides. In the radioactivated solution, 511 keV gamma-rays were observed, and their half-lives were approximately 2 min, 10 min, and 20 min. They respectively correspond to the beta+ decay of 15O, 13N, and 11C. The SCE frequencies in CHO cells increased depending on the amount of radioactivation in the solution. These were suppressed with a 2-hour delayed solution transfer or pretreatment with dimethyl sulfoxide (DMSO). Our results suggest that the SCE induction by radioactivated solution was mediated by free radicals produced by the annihilated gamma-rays. Since the SCE induction and DMSO modulation are also reported in radiation-induced bystander effects, our results imply that radioactivation of the solution may have some contribution to the bystander effects from hadron radiation. Further investigations are required to assess if radioactivation effects would attribute an additional level of cancer risk of the hadron radiation therapy itself.

  9. Solution Radioactivated by Hadron Radiation Can Increase Sister Chromatid Exchanges.

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    Junko Maeda

    Full Text Available When energetic particles irradiate matter, it becomes activated by nuclear reactions. Radioactivation induced cellular effects are not clearly understood, but it could be a part of bystander effects. This investigation is aimed at understanding the biological effects from radioactivation in solution induced by hadron radiation. Water or phosphate buffered saline was activated by being exposed to hadron radiation including protons, carbon- and iron-ions. 1 mL of radioactivated solution was transferred to flasks with Chinese hamster ovary (CHO cells cultured in 5 mL of complete media. The induction of sister chromatid exchanges (SCE was used to observe any increase in DNA damage responses. The energy spectrum and the half-lives of the radioactivation were analyzed by NaI scintillation detector in order to identify generated radionuclides. In the radioactivated solution, 511 keV gamma-rays were observed, and their half-lives were approximately 2 min, 10 min, and 20 min. They respectively correspond to the beta+ decay of 15O, 13N, and 11C. The SCE frequencies in CHO cells increased depending on the amount of radioactivation in the solution. These were suppressed with a 2-hour delayed solution transfer or pretreatment with dimethyl sulfoxide (DMSO. Our results suggest that the SCE induction by radioactivated solution was mediated by free radicals produced by the annihilated gamma-rays. Since the SCE induction and DMSO modulation are also reported in radiation-induced bystander effects, our results imply that radioactivation of the solution may have some contribution to the bystander effects from hadron radiation. Further investigations are required to assess if radioactivation effects would attribute an additional level of cancer risk of the hadron radiation therapy itself.

  10. Relationship of the demethylation of the DNA with the induction of the sister chromatid exchanges (SCE) In vivo; Relacion de la desmetilacion del ADN con la induccion de intercambios en las cromatidas hermanas (ICH) In vivo

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    Toribio E, E

    2005-07-01

    The methylation of the DNA is an epigenetic modification that has an important paper in the regulation of the functionality of the genome of the organisms. It can be altered by demethylation processes, either natural or experimentally induced. The 5-azacytidine (Aza) is a compound that causes the demethylation of the DNA (dm-DNA), inducing with it, expression genic and increase in the frequency of the Sister Chromatid Exchange (SCE). The SCE is a genotoxicity indicator, caused by diverse mutagens and carcinogen. Since the biological meaning and the formation mechanism of this phenomenon has not been totally illustrious, the exploration of the relation between the dm-DNA and the induction of SCE, it could offer new knowledge to explain those queries. The purpose of this work was to study in cells of the mouse bone marrow In vivo, the effect of the Aza on the induction of SCE, based on two aspects: 1) dose answer and 2) the effectiveness of multiple exhibition. To six groups of three to five animals, they are administered Aza to dose of 5, 10, 15 or 20 mg/Kg of weight; in sharp or multiple form, previously to the bromodeoxyuridine supply and 24 h was sacrificed after this; 2 h after an injection with colchicine. Preparations of those metaphases were made, those which were dyed by means of a technique of fluorescence more Giemsa. It was observed that to sharp low dose, the Aza produced an increment in the frequency of SCE that although small it was proportional and statistically significant. To sharp and multiple high doses, the Aza doesn't cause additional increments of SCE, but if toxicity at cellular level and of individuals. It is concluded that a relationship exists between the dm-DNA and the induction of SCE. It is suggested that the total demethylation of the DNA causes 2 SCE/Cell in cells of the mouse bone marrow, or that the cytotoxicity prevents to evidence a bigger induction. (Author)

  11. Sister chromatid exchange in Polish White improved goats (Capra hircus).

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    Wójcik, Ewa; Smalec, Elzbieta

    2012-01-01

    The study was aimed at evaluating the frequency of spontaneous sister chromatid exchange in Polish White Improved goats (Capra hircus). The mean number of SCEs/cell was 2.73 +/- 1.84. The effect of sex and age on SCE incidence was also investigated. No statistically significant differences in the number of SCEs/cell were observed between the males and females. On the other hand, age was found to significantly influence SCE frequency. A lower SCE frequency was observed in younger goats. A positive correlation between chromosome length and SCE number was identified. The longer the chromosome, the more exchanges occurred. The highest number of SCEs was observed in the interstitial region, the lowest in the distal area.

  12. Diethylstilbestrol-diphosphate induces chromosomal aberrations but not sister chromatid exchanges in murine bone marrow cells in vivo

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    Ivett, J.L. (North Carolina State Univ., Raleigh); Tice, R.R.

    1981-01-01

    Diethylstilbestrol diphosphate (DES-dp) clastogenesis was examined in the bone marrow of C57B1/6 male and female mice. Significant and sex-related dose effects were observed for the induction of chromatid-type chromosomal aberrations and for the inhibition of cellular proliferation. Females were more sensitive to the effects of DES-dp than males when assessed for either induced chromosomal aberrations or proliferative inhibition. Contrary to other published results, we did not observe either an increase in sister chromatid exchanges or an increased incidence of aneuploidy. Ovariectomy reduced the ability of DES-dp to inhibit cellular proliferation and decreased the high degree of variability between animals at high doses of DES-dp. The results of our studies show that DES is a clastogenic agent in vivo which may relate to its carcinogenicity.

  13. Further characterization of the genotoxicity of formaldehyde in vitro by the sister chromatid exchange test and co-cultivation experiments.

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    Neuss, Simone; Speit, Günter

    2008-09-01

    The induction of sister chromatid exchanges (SCE) was used to further characterize the genotoxic action of formaldehyde (FA) on cultured mammalian cells. FA induced SCE in V79 Chinese hamster cells and A549 human lung cells in a concentration-related manner. Addition of 5-bromodeoxyuridine (BrdUrd) for the differentiation of sister chromatids to visualize SCE 4 h after the FA treatment led to a clearly reduced induction of SCE in agreement with the repair kinetics of FA-induced DNA-protein cross-links. When A549 cells were treated with FA for 1 h and then co-cultivated with V79 cells in the presence of BrdUrd, a clear induction of SCE was measured in V79 cells. When the same experiment was performed including washing and change of medium after the FA treatment, no induction of SCE was measured in V79 cells. These results indicate that reactive FA remains in the cell culture medium for a longer time period despite the high reactivity of FA with macromolecules. However, FA that has entered a cell is not released and does not damage other cells. Possible implications for the mutagenicity of FA in vivo will be discussed.

  14. Bromodeoxyuridine does not contribute to sister chromatid exchange events in normal or Bloom syndrome cells

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    van Wietmarschen, Niek; Lansdorp, Peter M.

    2016-01-01

    Sister chromatid exchanges (SCEs) are considered sensitive indicators of genome instability. Detection of SCEs typically requires cells to incorporate bromodeoxyuridine (BrdU) during two rounds of DNA synthesis. Previous studies have suggested that SCEs are induced by DNA replication over BrdU-subst

  15. Effect of borax on immune cell proliferation and sister chromatid exchange in human chromosomes

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    Pongsavee Malinee

    2009-10-01

    Full Text Available Abstract Background Borax is used as a food additive. It becomes toxic when accumulated in the body. It causes vomiting, fatigue and renal failure. Methods The heparinized blood samples from 40 healthy men were studied for the impact of borax toxicity on immune cell proliferation (lymphocyte proliferation and sister chromatid exchange in human chromosomes. The MTT assay and Sister Chromatid Exchange (SCE technic were used in this experiment with the borax concentrations of 0.1, 0.15, 0.2, 0.3 and 0.6 mg/ml. Results It showed that the immune cell proliferation (lymphocyte proliferation was decreased when the concentrations of borax increased. The borax concentration of 0.6 mg/ml had the most effectiveness to the lymphocyte proliferation and had the highest cytotoxicity index (CI. The borax concentrations of 0.15, 0.2, 0.3 and 0.6 mg/ml significantly induced sister chromatid exchange in human chromosomes (P Conclusion Borax had effects on immune cell proliferation (lymphocyte proliferation and induced sister chromatid exchange in human chromosomes. Toxicity of borax may lead to cellular toxicity and genetic defect in human.

  16. SISTER-CHROMATID EXCHANGES IN CULTURED IMMATURE EMBRYOS OF WHEAT SPECIES AND REGENERANTS

    NARCIS (Netherlands)

    PIJNACKER, LP; FERWERDA, MA

    1994-01-01

    Immature embryos of Triticum aestivum (ten cultivars and lines), T. durum, T. dicoccum and T. monococcum were cultured in vitro on MS medium supplemented with 1 or 2 mg/l of 2,4-D and 20 or 30g/l of sucrose for 3 days and processed to score sister chromatid exchanges (SCEs) per chromosome. Media com

  17. Comparison of genome stability in two pig breeds by using the sister chromatid exchange (SCE test

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    V. Barbieri

    2010-01-01

    Full Text Available The sister chromatid exchange (SCE test has been used to detect genome stability in humans (Chaganti, 1974 and the main livestock species (Ciotola et al., 2004; Di Meo et al., 2000; Di Berardino et al., 1979, and to discover DNA damage caused by a variety of natural and artificial chemical compounds (Iannuzzi et al., 1990.

  18. Bromodeoxyuridine does not contribute to sister chromatid exchange events in normal or Bloom syndrome cells

    NARCIS (Netherlands)

    van Wietmarschen, Niek; Lansdorp, Peter M.

    2016-01-01

    Sister chromatid exchanges (SCEs) are considered sensitive indicators of genome instability. Detection of SCEs typically requires cells to incorporate bromodeoxyuridine (BrdU) during two rounds of DNA synthesis. Previous studies have suggested that SCEs are induced by DNA replication over BrdU-subst

  19. Mouse RAD54 Affects DNA Double-Strand Break Repair and Sister Chromatid Exchange

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    Dronkert, Mies L. G.; Beverloo, H. Berna; Johnson, Roger D.; Hoeijmakers, Jan H. J.; Jasin, Maria; Kanaar, Roland

    2000-01-01

    Cells can achieve error-free repair of DNA double-strand breaks (DSBs) by homologous recombination through gene conversion with or without crossover. In contrast, an alternative homology-dependent DSB repair pathway, single-strand annealing (SSA), results in deletions. In this study, we analyzed the effect of mRAD54, a gene involved in homologous recombination, on the repair of a site-specific I-SceI-induced DSB located in a repeated DNA sequence in the genome of mouse embryonic stem cells. We used six isogenic cell lines differing solely in the orientation of the repeats. The combination of the three recombination-test substrates used discriminated among SSA, intrachromatid gene conversion, and sister chromatid gene conversion. DSB repair was most efficient for the substrate that allowed recovery of SSA events. Gene conversion with crossover, indistinguishable from long tract gene conversion, preferentially involved the sister chromatid rather than the repeat on the same chromatid. Comparing DSB repair in mRAD54 wild-type and knockout cells revealed direct evidence for a role of mRAD54 in DSB repair. The substrate measuring SSA showed an increased efficiency of DSB repair in the absence of mRAD54. The substrate measuring sister chromatid gene conversion showed a decrease in gene conversion with and without crossover. Consistent with this observation, DNA damage-induced sister chromatid exchange was reduced in mRAD54-deficient cells. Our results suggest that mRAD54 promotes gene conversion with predominant use of the sister chromatid as the repair template at the expense of error-prone SSA. PMID:10757799

  20. Diagnostic insonation of extra uteri human placentas: no effect of lymphocytic sister chromatid exchange

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    Brulfert, A.; Ciaravino, V.; Miller, M.W.; Maulik, D.; Carstensen, E.L.

    1984-01-01

    Freshly delivered human placentas were exposed to ultrasound for 30 min using a diagnostic linear array unit. Blood was then drawn and cultured in the presence of bromodeoxyuridine, and the frequencies of sister chromatid exchanges (SCE) in the lymphocytes determined. There was no statistically significant difference in SCE frequencies between control and exposed cells; the frequencies of SCEs per cell ranged from 4.50 to 6.02 for control and from 4.66 to 6.10 for exposed cells in five separate experiments. Positive control mitomycin C treated cells were significantly affected, with more than 50 SCEs per cell. 20 references, 1 table.

  1. A proposal of a standardised nomenclature for terminal minute sister chromatid exchanges

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    Máximo E. Drets

    2006-01-01

    Full Text Available We described spontaneous minute sister chromatid exchanges (SCE in telomeric regions of human and Chinese hamster ovary (CHO chromosomes more than 10 years ago. These structures, which we called t-SCE, were detected by means of highly precise quantitative microphotometrical scanning and computer graphic image analysis. Recently, several authors using the CO-FISH method also found small SCEs in telomeric regions and called them T-SCE. The use of different terms for designating the same phenomenon should be avoided. We propose ter SCE as a uniform nomenclature for minute telomeric SCEs.

  2. Investigating the in vitro effect of taurine on the infant lymphocytes by sister chromatid exchange.

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    Ergun, Mehmet Ali; Soysal, Yasemin; Kismet, Erol; Akay, Cemal; Dundaroz, Rusen; Ilhan, Mustafan; Imirzalioglu, Necat

    2006-06-01

    Taurine (2-aminoethane sulphonic acid) is normally present in most mammalian tissues and the most abundant free amino acid in lymphocytes. It participates in various important physiological activities including modulation of the functioning of the central nervous system, cell proliferation, viability and prevention of oxidant-induced injury in many tissues. Its levels in human milk are very high which may be the most important difference from cow's milk. In contrast, an inverse association between breast-feeding and carcinogenesis in childhood or later in life has been suggested by several studies. The study group consisted of eight healthy infants. Peripheral blood was collected and lymphocytes were cultured with either Taurine or Mitomycin C (MMC). Sister chromatid exchange in lymphocytes of the infants were calculated. Statistical differences were found between untreated and MMC-treated lymphocytes, untreated and MMC plus taurine-treated lymphocytes, and between MMC and MMC plus taurine-treated lymphocytes (P = 0.012). The results indicated that taurine plays a protective role in MMC-induced sister chromatid exchange in human lymphocytes. The authors suggest that the high levels of taurine found in human milk may induce protecting effects from breast-feeding against DNA damage and malignancy.

  3. UV-induced chromosome aberrations, sister-chromatid exchanges and cell survival in cultured lymphocytes from malnourished children

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    Murthy, P.B.; Rahiman, M.A.; Tulpule, P.G.

    1982-08-01

    Cultured lymphocytes from children with kwashiorkor and from normal children were examined for their susceptibility to ultraviolet (UV)-induced chromosome aberrations, sister-chromatid exchanges and cell survival. Cells from kwashiorkor exhibited increased chromosome aberrations, but not sister-chromatid exchanges, when exposed to higher doses of UV. Furthermore, when cells from these patients were exposed to higher doses of UV, there was a significant reduction in viability. These results indicate that, as compared to normals, cells from kwashiorkor were more sensitive to the lethal effects of UV.

  4. Frequencies of chromosomal aberrations and sister chromatid exchanges in the benthic worm Neanthes arenaceodentata exposed to ionizing radiation

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    Harrison, F.L.; Rice, D.W. Jr., Moore, D.H.

    1984-07-01

    Traditional bioassays are unsuitable for assessing sublethal effects from ocean disposal of low-level radioactive waste because mortality and phenotypic responses are not anticipated. We compared the usefulness of chromosomal aberration and sister chromatid exchange (SCE) induction as measures of low-level radiation effects in a sediment-dwelling marine worm, Neanthes arenaceodentata. The SCEs, in contrast to chromosomal aberrations, do not alter the overall chromosome morphology and in mammalian cells appear to be a more sensitive indicator of DNA alterations caused by environmental mutagens. Newly hatched larvae were exposed to two radiation-exposure regimes of either x rays at a high dose rate of 0.7 Gy (70 rad)/min for as long as 5.5 min or to /sup 60/Co gamma rays at a low dose rate of from 4.8 x 10/sup -5/ to 1.2 x 10/sup -1/ Gy (0.0048 to 12 rad)/h for 24 h. After irradiation, the larvae were exposed to 3 x 10/sup -5/M bromodeoxyuridine (BrdUrd) for 28 h (x-ray-irradiated larvae) or for 54 h (/sup 60/Co-irradiated larvae). Larval cells were examined for the proportion of cells in first, second, and third or greater division. Frequencies of chromosomal aberrations and SCEs were determined in first and second division cells, respectively. Results from x-ray irradiation indicated that dose-related increases occur in chromosome and chromatid deletions, but a dose of equal or greater 2 Gy (equal to or greater than 200 rad) was required to observe a significant increase. Worm larvae receiving /sup 60/Co irradiation showed elevated SCE frequencies with a significant increase of 0.6 Gy (60 rad). We suggest that both SCEs and chromosomal aberrations may be useful for measuring effects on genetic material induced by radiation. 56 references, 7 figures, 9 tables.

  5. Bromodeoxyuridine does not contribute to sister chromatid exchange events in normal or Bloom syndrome cells.

    Science.gov (United States)

    van Wietmarschen, Niek; Lansdorp, Peter M

    2016-08-19

    Sister chromatid exchanges (SCEs) are considered sensitive indicators of genome instability. Detection of SCEs typically requires cells to incorporate bromodeoxyuridine (BrdU) during two rounds of DNA synthesis. Previous studies have suggested that SCEs are induced by DNA replication over BrdU-substituted DNA and that BrdU incorporation alone could be responsible for the high number of SCE events observed in cells from patients with Bloom syndrome (BS), a rare genetic disorder characterized by marked genome instability and high SCE frequency. Here we show using Strand-seq, a single cell DNA template strand sequencing technique, that the presence of variable BrdU concentrations in the cell culture medium and in DNA template strands has no effect on SCE frequency in either normal or BS cells. We conclude that BrdU does not induce SCEs and that SCEs detected in either normal or BS cells reflect DNA repair events that occur spontaneously.

  6. Sister-chromatid exchange analysis in a rural population of Mexico exposed to pesticides.

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    Gómez-Arroyo, S; Noriega-Aldana, N; Osorio, A; Galicia, F; Ling, S; Villalobos-Pietrini, R

    1992-03-01

    Cytogenetic damage was evaluated by means of the analysis of sister-chromatid exchange (SCE) in a rural population of Tlaxcala, Mexico, in occupational contact with pesticides. We studied 170 men, 94 exposed and 76 not exposed. It was shown that SCE followed a normal distribution and Student's t test did not present differences between the two groups (P = 0.4). The frequency of SCE was not correlated with the duration of exposure of the rural workers (r = -0.06), the multiple covariance analysis applied to the data of duration of exposure, tobacco intake and alcohol ingestion demonstrated a lack of statistical significance. In the exposed people we observed no symptoms provoked by these compounds.

  7. Antimutagenic effect of crown ethers on heavy metal-induced sister chromatid exchanges.

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    Cai, M Y; Arenaz, P

    1998-01-01

    Macrocyclic polyethers (crown ethers) are a family of compounds that possess the ability to complex with and transport metal ions across membranes. Because of their unique ionophoric characteristic, they have wide application in industry and research, chemistry and biology. In the current investigation the relationship between heavy metal mutagenesis and crown ether co-mutagenicity and/or antimutagenicity in mammalian cells has been examined using sister chromatid exchange (SCE) as the cytogenetic end point. Chinese hamster ovary cells were treated with lead or cadmium, with and without selected crown ethers. Several genotoxic end points, including SCEs were scored and statistically compared. We report here that most of the crown ethers studied had little or no influence on lead- or cadmium-induced SCEs or chromosome aberrations. On the other hand, the substituted crown ether dicyclohexyl 21-crown-7 significantly decreased both spontaneous and metal-induced SCE frequencies, suggesting that this crown ether may possess antimutagenic activity.

  8. Sister chromatid exchange in human populations: the effect of smoking, drug treatment, and occupational exposure

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, B.; Bredberg, A.; McKenzie, W.; Sten, M.

    1982-01-01

    Increased rate of sister chromatid exchange (SCE) in peripheral lymphocytes has been observed in smokers as compared to nonsmokers and in patients receiving certain cytostatic drugs. The increased SCE frequency in smokers was shown to depend on the number of cigarettes smoked per day, as well as on the duration of smoking. DNA cross-links caused by photochemotherapy against psoriasis, 8-methoxypsoralen plus UVA irradiation (PUVA), as well as by the anti-cancer chemotherapeutic agent CCNU, were shown to be more effective at inducing SCE's than other types of DNA damage caused by these treatments. These observations suggest that SCE analysis may be used as an indicator of genotoxic exposure in vivo, provided that the various types of DNA damage caused by genotoxic agents and the dose, as well as the time of exposure in relation to the time of sampling, are considered.

  9. An increase in telomere sister chromatid exchange in murine embryonic stem cells possessing critically shortened telomeres

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yisong [ORNL; Giannone, Richard J [ORNL; Wu, Jun [ORNL; Gomez, Marla V [ORNL; Liu, Yie [ORNL

    2005-01-01

    Telomerase deficiency leads to a progressive loss of telomeric DNA that eventually triggers cell apoptosis in human primary cells during prolonged growth in culture. Rare survivors can maintain telomere length through either activation of telomerase or recombination-based telomere lengthening, and thus proliferate indefinitely. We have explored the possibility that telomeres may be maintained through telomere sister chromatid exchange (T-SCE) in murine telomere reverse transcriptase-deficient (mTert -/-) splenocytes and ES cells. Because telomerase deficiency leads to gradual loss of telomeric DNA in mTert -/- splenocytes and ES cells and eventually to chromosomes with telomere signal-free ends (SFEs), we examined these cell types for evidence of sister chromatid exchange at telomeres, and observed an increase in T-SCEs only in a subset of mTert -/- splenocytes or ES cells that possessed multiple SFEs. Furthermore, T-SCEs were more often detected in ES cells than in splenocytes that harbored a similar frequency of SFEs. In mTert heterozygous (mTert +/-) ES cells or splenocytes, which are known to exhibit a decrease in average telomere length but no SFEs, no increase in T-SCE was observed. In addition to T-SCE, other genomic rearrangements (i.e., SCE) were also significantly increased in mTert -/- ES cells possessing critically short telomeres, but not in splenocytes. Our results suggest that animals and cell culture differ in their ability to carry out genomic rearrangements as a means of maintaining telomere integrity when telomeres become critically shortened.

  10. In vitro genotoxicity of fipronil sister chromatid exchange, cytokinesis block micronucleus test, and comet assay.

    Science.gov (United States)

    Çelik, Ayla; Ekinci, Seda Yaprak; Güler, Gizem; Yildirim, Seda

    2014-03-01

    Fipronil (FP) is a phenylpyrazole pesticide developed by the transnational company Rhône-Poulenc Agro in 1987. Data on the genotoxicity and toxicity of FP are rather inadequate. In this study, we aimed to evaluate the potential genotoxic activity of FP using the single-cell microgel electrophoresis or comet assay, sister chromatid exchanges (SCEs), and micronuclei (MN) in human peripheral blood lymphocytes. In addition, the cytokinesis block proliferation index (CBPI) and proliferation index (PRI) were measured for cytotoxicity. In this study, three different doses of FP were used (0.7, 0.3, 0.1 μg/mL). Mitomycin C (2 μg/mL) and hydrogen peroxide were used as positive controls for SCE MN test systems, and comet assay, respectively. FP induced a statistically significant increase in the MN and SCE frequency and DNA damage in a dose-dependent manner in human peripheral blood lymphocytes (pcomet assay, we showed that all the doses of the FP induced DNA damage in human peripheral blood lymphocytes in vitro (p<0.05).

  11. A high rate of telomeric sister chromatid exchange occurs in chronic lymphocytic leukaemia B-cells.

    Science.gov (United States)

    Medves, Sandrine; Auchter, Morgan; Chambeau, Laetitia; Gazzo, Sophie; Poncet, Delphine; Grangier, Blandine; Verney, Aurélie; Moussay, Etienne; Ammerlaan, Wim; Brisou, Gabriel; Morjani, Hamid; Géli, Vincent; Palissot, Valérie; Berchem, Guy; Salles, Gilles; Wenner, Thomas

    2016-07-01

    Cancer cells protect their telomere ends from erosion through reactivation of telomerase or by using the Alternative Lengthening of Telomere (ALT) mechanism that depends on homologous recombination. Chronic lymphocytic leukaemia (CLL) B cells are characterized by almost no telomerase activity, shelterin deregulation and telomere fusions. To characterize telomeric maintenance mechanisms in B-CLL patients, we measured their telomere length, telomerase expression and the main hallmarks of the ALT activity i.e. C-circle concentration, an extra-chromosomal telomere repeat (ECTR), and the level of telomeric sister chromatid exchange (T-SCE) rate. Patients showed relative homogenous telomere length although almost no TERT transcript and nearly no C-circle were evidenced. Nevertheless, compared with normal B cells, B-CLL cells showed an increase in T-SCE rate that was correlated with a strong down-regulation of the topoisomerase III alpha (TOP3A) expression, involved in the dissolution of Holliday Junctions (HJ), together with an increased expression of SLX1A, SLX4, MUS81 and GEN1, involved in the resolution of HJ. Altogether, our results suggest that the telomere maintenance mechanism of B-CLL cells do not preferentially use telomerase or ALT. Rather, the rupture of the dissolvasome/resolvasome balance may increase telomere shuffling that could homogenize telomere length, slowing telomere erosion in this disease.

  12. Sister chromatid exchange in human lymphocytes induced by propoxur following plant activation by Vicia faba.

    Science.gov (United States)

    Gómez-Arroyo, S; Calderón-Segura, M E; Villalobos-Pietrini, R

    1995-01-01

    Because the carbamate insecticide propoxur induced sister chromatid exchanges (SCE) in Vicia faba but was ineffective in producing SCE in lymphocytes in culture, it was hardly suspected that plant metabolism was involved. Experiments were conducted in which metabolic activation was afforded by Vicia faba roots, and SCE in human lymphocytes in vitro was used to assess cytogenetic damage. Several concentrations of propoxur (250, 500, 1,000, 1,500, and 2,000 ppm) were applied for 4 hr to the roots of Vicia faba. Extracts prepared from these treatments were added to the lymphocyte cultures and a significant increase of SCE frequencies with a concentration-response relationship could be detected. The lymphocyte proliferation kinetics and the proliferation rate index (PRI) were not affected (except in the highest concentration, of 2,000 ppm). This general behavior was in agreement with the presence of an enzymatic system (S10 fraction) in Vicia roots capable of metabolizing or activating the propoxur. With 2,000 ppm, cell necrosis was produced in Vicia; therefore, this extract did not induce SCE in lymphocytes. However, lymphocyte proliferation kinetics were delayed and PRI was significantly decreased. Ethanol, a promutagen activated by this plant, was applied directly to the lymphocyte cultures as a positive control, and the response was negative. On the other hand, the extracts of roots treated with ethanol increased the SCE to more than twice that of the negative control, but the lymphocyte proliferation kinetics and PRI were not affected.

  13. Health assessment of gasoline and fuel oxygenate vapors: micronucleus and sister chromatid exchange evaluations.

    Science.gov (United States)

    Schreiner, Ceinwen A; Hoffman, Gary M; Gudi, Ramadevi; Clark, Charles R

    2014-11-01

    Micronucleus and sister chromatid exchange (SCE) tests were performed for vapor condensate of baseline gasoline (BGVC), or gasoline with oxygenates, methyl tert-butyl ether (G/MTBE), ethyl tert butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), t-butyl alcohol (TBA), or ethanol (G/EtOH). Sprague Dawley rats (the same 5/sex/group for both endpoints) were exposed to 0, 2000, 10,000, or 20,000mg/m(3) of each condensate, 6h/day, 5days/week over 4weeks. Positive controls (5/sex/test) were given cyclophosphamide IP, 24h prior to sacrifice at 5mg/kg (SCE test) and 40mg/kg (micronucleus test). Blood was collected from the abdominal aorta for the SCE test and femurs removed for the micronucleus test. Blood cell cultures were treated with 5μg/ml bromodeoxyuridine (BrdU) for SCE evaluation. No significant increases in micronucleated immature erythrocytes were observed for any test material. Statistically significant increases in SCE were observed in rats given BGVC alone or in female rats given G/MTBE. G/TAME induced increased SCE in both sexes at the highest dose only. Although DNA perturbation was observed for several samples, DNA damage was not expressed as increased micronuclei in bone marrow cells. Inclusion of oxygenates in gasoline did not increase the effects of gasoline alone or produce a cytogenetic hazard.

  14. Effects of orally administered antioxidants on micronuclei and sister chromatid exchange frequency in workers professionally exposed to antineoplastic agents.

    Science.gov (United States)

    Mrđanović, Jasminka; Jungić, Saša; Šolajić, Slavica; Bogdanović, Višnja; Jurišić, Vladimir

    2012-08-01

    The widespread use of antineoplastic drugs in cancer treatment increased concern about possible hazard to workers involved in the preparation and administration of these drugs. In the present study, the effects of commercial antioxidative drug Oligogal Se on genome protection were analyzed in 15 nurses handling the antineoplastic drugs at the Oncology Department in comparison to twenty healthy volunteers. The nurses took antioxidant mixture Oligogal Se, consisting of vitamins C, E, A and selenium, one capsule per day, over a period of 6 months. Genome damage was measured in peripheral blood lymphocytes by usage of sister chromatid exchange test and the cytokinesis-block micronuclei test. The frequency of sister chromatid exchange (SCE) and micronuclei (MN) in the exposed group was significantly higher when compared to the control group (SCE, p<0.05; MN, p<0.01 respectively). After antioxidant supplementation, the frequency of sister chromatid exchange and micronuclei decreased (p<0.05) when compared with the values from the beginning of the study, but were still above the values of the control group. The effects of confounding factors such as cigarette smoking and cytostatics exposure time were also evaluated. The data indicated that Oligogal Se contributed to the decreasing of genome damages in workers handling the cytostatics. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Low doses of alpha particles do not induce sister chromatid exchanges in bystander Chinese hamster cells defective in homologous recombination

    Energy Technology Data Exchange (ETDEWEB)

    Nagasawa, H; Wilson, P F; Chen, D J; Thompson, L H; Bedford, J S; Little, J B

    2007-10-26

    We reported previously that the homologous recombinational repair (HRR)-deficient Chinese hamster mutant cell line irs3 (deficient in the Rad51 paralog Rad51C) showed only a 50% spontaneous frequency of sister chromatid exchange (SCE) as compared to parental wild-type V79 cells. Furthermore, when irradiated with very low doses of alpha particles, SCEs were not induced in irs3 cells, as compared to a prominent bystander effect observed in V79 cells (Nagasawa et al., Radiat. Res. 164, 141-147, 2005). In the present study, we examined additional Chinese hamster cell lines deficient in the Rad51 paralogs Rad51C, Rad51D, Xrcc2, and Xrcc3 as well as another essential HRR protein, Brca2. Spontaneous SCE frequencies in non-irradiated wild-type cell lines CHO, AA8 and V79 were 0.33 SCE/chromosome, whereas two Rad51C-deficient cell lines showed only 0.16 SCE/chromosome. Spontaneous SCE frequencies in cell lines defective in Rad51D, Xrcc2, Xrcc3, and Brca2 ranged from 0.23-0.33 SCE/chromosome, 0-30% lower than wild-type cells. SCEs were induced significantly 20-50% above spontaneous levels in wild-type cells exposed to a mean dose of 1.3 mGy of alpha particles (<1% of nuclei traversed by an alpha particle). However, induction of SCEs above spontaneous levels was minimal or absent after {alpha}-particle irradiation in all of the HRR-deficient cell lines. These data suggest that Brca2 and the Rad51 paralogs contribute to DNA damage repair processes induced in bystander cells (presumably oxidative damage repair in S-phase cells) following irradiation with very low doses of alpha particles.

  16. Rate of sister chromatid exchanges in Bloom syndrome fibroblasts reduced by co-cultivation with normal fibroblasts.

    OpenAIRE

    1980-01-01

    Six strains of Bloom syndrome (BlS) fibroblasts responded to co-cultivation with normal fibroblasts at a 1:2 ratio by a reduced rate of sister chromatid exchanges (SCE's) from a mean of 67.5 (range = 59--78) to 28.4 (range = 21--35). The response was dose-dependent in one strain tested at 1:2, 1:1, and 2:1 ratios. In addition, quadriradial exchange figures and other signs of increased chromosomal instability were not found in BlS cells following co-cultivation with control cells. Control cell...

  17. The Relationship between Dioxin Congeners in the Breast Milk of Vietnamese Women and Sister Chromatid Exchange

    Directory of Open Access Journals (Sweden)

    Hiroyuki Suzuki

    2014-04-01

    Full Text Available The aim of this study was to clarify the relationship between dioxin concentrations in breast milk and the sister chromatid exchange (SCE frequency in women from herbicide-sprayed and non sprayed areas. Blood samples were taken from 21 women with high TCDD (tetrachlorodibenzo-p-dioxin levels from sprayed areas, 23 women with moderate TCDD levels from sprayed areas, and 19 women from non sprayed areas to determine their SCE frequency. The SCE frequencies for the high and moderate TCDD groups from the sprayed area and for the non sprayed area group were 2.40, 2.19, and 1.48 per cell, respectively. Multiple regression analysis showed that the standardized β values for 1,2,3,6,7,8-hexaCDD (β = 0.60, 1,2,3,4,6,7,8-heptaCDD (β = 0.64, and octaCDD (β = 0.65 were higher than those for TCDD (β = 0.34 and 1,2,3,7,8-pentaCDD (β = 0.42. The adjusted R2 value for polyCDDs (R2 = 0.38 was higher than that for polyCDD toxic equivalents (TEQ (toxic equivalents; R2 = 0.23. This study therefore shows that levels of hexa-, hepta-, and octaCDD, which were previously regarded as being less toxic than TCDD, are closely related to SCE frequency and that the level of dioxin (pg/g lipid is potentially more useful as an indicator than TEQ value for explaining SCE frequency.

  18. Incorporation of deoxyuridine monophosphate into DNA increases the sister-chromatid exchange yield

    Energy Technology Data Exchange (ETDEWEB)

    Pardo, E.G.; Hernandez, P.; Gutierrez, C.

    1987-02-01

    The effect of a treatment with 5-fluoro-2'-deoxyuridine (FdUrd) in combination with 2'-deoxyuridine (dUrd) on cell proliferation, incorporation of DNA precursors into DNA and sister-chromatid exchanges (SCEs) has been analyzed in Allium cepa meristem cells. FdUrd in the range 10/sup -9/-5 x 10/sup -7/ M produced a dose- and time-dependent decrease in the amount of cells in mitosis. This inhibitory effect could be reversed by 70-80% in short-term (6 h) experiments, by exogenously supplied dUrd at a concentration of 10/sup -1/ M. However, at the highest FdUrd dose tested (10/sup -7/ M), 10/sup -4/ M dUrd could not reverse the FdUrd effect in long-term experiments as shown by analyzing the kinetics of synchronous cell populations. DNA extracted from cells pulsed with (6-/sup 3/H)dUrd in the presence of FdUrd and 6-amino-uracil (6-AU), an inhibitor of uracil-DNA glycosylase, contained a small amount of label in the form of (6-/sup 3/H)dUMP. Thus the authors conclude that under the experimental conditions, exogenously supplied dUrd may be metabolized intracellularly to 2'-deoxyuridine triphosphate (dUTP) and that this deoxynucleotide may eventually be mis-incorporated into DNA. By analyzing SCE levels in third division chromosomes of cells treated with FdUrd and dUrd during their second cycle, they has scored a 6-fold increase in the reciprocal SCE level which demonstrates that the replication of a dUMP-containing DNA template leads to a higher SCE yield.

  19. Chromosome aberrations and sister chromatid exchanges in cultured human lymphocytes treated with sodium metabisulfite, a food preservative.

    Science.gov (United States)

    Rencüzogullari, E; Ila, H B; Kayraldiz, A; Topaktaş, M

    2001-02-20

    The aim of this study was to investigate the ability of sodium metabisulfite (SMB) which is used as an antimicrobial substance in food, to induce chromosome aberrations (CA) and sister chromatid exchanges (SCE) in human lymphocytes. SMB-induced CAs and SCEs at all concentrations (75, 150 and 300 microg/ml) and treatment periods (24 and 48h) dose-dependently. However, SMB decreased the replication index (RI) and the mitotic index (MI) at the concentrations of 150 and 300 microg/ml for 24 and 48h treatment periods. This decrease was dose-dependent as well.

  20. Absence of an effect of lead acetate on sperm morphology, sister chromatid exchanges or on micronuclei formation in rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Willems, M.I.; Immel, H.R.; de Schepper, G.G.; Dietrich, A.J.J.; Wibowo, A.A.E.; Zielhuis, R.L.

    1982-07-01

    The influence of lead on sperm morphology, sister chromatid exchanges or on micronuclei formation was studied on male rabbits after exposure to doses of 0, 0.25, and 0.50 mg lead acetate/kg body weight subcutaneously injected three times a week during 14 weeks, each on a group of five rabbits. At the end of exposure phase the lead in blood concentrations of the three groups of rabbits were 0.32, 2.57, and 2.97 ..mu..mol/l respectively. The results did not show any evidence of treatment related effects on sperm count or on morphologic abnormalities of the sperms, neither on the histopathology of the testis. Statistical analysis of the number of sister chromatid exchanges per metaphase in lymphocytes indicated no differences between the groups. Also no dose dependent effect was observed on the relative number of micronuclei in bone marrow erythrocytes. The different susceptibility to lead in different organ systems of the rabbits was discussed.

  1. Chromosomal aberrations, sister-chromatid exchanges, cells with high frequency of SCE, micronuclei and comet assay parameters in 1, 3-butadiene-exposed workers.

    Science.gov (United States)

    Srám, R J; Rössner, P; Peltonen, K; Podrazilová, K; Mracková, G; Demopoulos, N A; Stephanou, G; Vlachodimitropoulos, D; Darroudi, F; Tates, A D

    1998-11-09

    The association of occupational exposure to 1,3-butadiene (BD) and induction of cytogenetic damage in peripheral lymphocytes was studied in 19 male workers from a monomer production unit and 19 control subjects from a heat production unit. The exposure to BD was measured by passive personal monitors. The following biomarkers were used: chromosomal aberrations (CA), sister chromatid exchanges (SCE), cells with a high frequency of SCE (HFC), micronuclei, comet assay parameters like tail length (TL) and percentage of DNA in tail [T (%)] and polymorphisms of GSTM1 and GSTT1 genotypes. BD exposure with a median value of 0.53 mg/m3 (range: 0.024-23.0) significantly increased (a) the percentage of cells with chromosomal aberrations in exposed vs. control groups (3.11% vs. 2.03%, P<0.01), (b) the frequency of SCE per cell (6.96 vs. 4.87, P<0.001), and (c) the percentage of HFC (19.9% vs. 4.1%, P<0.001). BD exposure had no significant effects on formation of micronuclei and on comet assay parameters. Effect of smoking was observed only for HFC in BD-exposed group. GSTM1 genotype affected chromosomal aberrations in exposed group, while GSTT1 genotype affected chromosomal aberrations in controls. No effect of GSTM1 or GSTT1 genotypes was observed on any other biomarkers used.

  2. Promutagen activation of triazine herbicides metribuzin and ametryn through Vicia faba metabolism inducing sister chromatid exchanges in human lymphocytes in vitro and in V. faba root tip meristems.

    Science.gov (United States)

    Flores-Maya, Saúl; Gómez-Arroyo, Sandra; Calderón-Segura, María Elena; Villalobos-Pietrini, Rafael; Waliszewski, Stefan M; de la Cruz, Leticia Gómez

    2005-03-01

    The aim of our study was the induction of sister chromatid exchanges (SCE) in human lymphocytes in vitro and in root tip meristems of Vicia faba to evaluate the genotoxic effects of metribuzin and ametryn. Direct treatments of these herbicides on human lymphocytes in vitro applied 24 h after the beginning of culture did not induce SCE; however, they showed a cytotoxic effect in the cultures expressed as cellular death. On the contrary, when extracts of V. faba roots, treated for 4 h with metribuzin and ametryn (in vivo activation), were added to the lymphocyte cultures, SCEs were significantly induced with an asymptotic response. Negative responses appeared with the in vitro assays, in which metribuzin and ametryn were added directly to the 48 h lymphocyte cultures for 4 h. Nevertheless, in treatments in which the S10 metabolic mix was added, the SCE frequencies were significantly different to the control, although a concentration-response relationship was only observed with metribuzin. The results showed that both herbicides needed the V. faba metabolism to produce SCE in human lymphocyte cultures. Metribuzin and ametryn applied to V. faba root tip meristems for 4 h increased SCE frequency significantly, and a concentration-response relationship was observed with both herbicides.

  3. Effects of chronic exposure to 2, 3, 7, 8,-tetrachlorodibenzo-p-dioxin on sister chromatid exchange levels in peripheral lymphocytes of the rhesus monkey

    Energy Technology Data Exchange (ETDEWEB)

    Lim, M.; Jacobson-Kram, D.; Bowman, R.E.; Williams, J.R.

    1987-01-01

    Frequencies of sister chromatid exchanges and chromosomal aberrations were examined in peripheral lymphocytes of Rhesus monkeys that had been fed a diet containing 25 parts per trillion 2,3,7,8-tetrachlorodibenzo-p-dioxin for a period of 4 years. When compared to non-exposed control animals, no significant differences were noted for either of these cytogenetic end points. In addition, there was not a significant difference in sister chromatid exchange response to a challenge dose of mitomycin C in cells from 2,3,7,8-tetrachlorodibenzo-p-dioxin exposed animals compared to controls. The results confirm the lack of genotoxic effects associated with 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure.

  4. Protection of halogenated DNA from strand breakage and sister-chromatid exchange induced by the topoisomerase I inhibitor camptothecin

    Energy Technology Data Exchange (ETDEWEB)

    Orta, Manuel Luis; Mateos, Santiago; Cantero, Gloria [Department of Cell Biology, Faculty of Biology, University of Seville (Spain); Wolff, Lisa J. [Sweet Briar College, VA (United States); Cortes, Felipe [Department of Cell Biology, Faculty of Biology, University of Seville (Spain)], E-mail: cortes@us.es

    2008-01-01

    The fundamental nuclear enzyme DNA topoisomerase I (topo I), cleaves the double-stranded DNA molecule at preferred sequences within its recognition/binding sites. We have recently reported that when cells incorporate halogenated nucleosides analogues of thymidine into DNA, it interferes with normal chromosome segregation, as shown by an extraordinarily high yield of endoreduplication, and results in a protection against DNA breakage induced by the topo II poison m-AMSA [F. Cortes, N. Pastor, S. Mateos, I. Dominguez, The nature of DNA plays a role in chromosome segregation: endoreduplication in halogen-substituted chromosomes, DNA Repair 2 (2003) 719-726; G. Cantero, S. Mateos, N. Pastor; F. Cortes, Halogen substitution of DNA protects from poisoning of topoisomerase II that results in DNA double-strand breaks (DSBs), DNA Repair 5 (2006) 667-674]. In the present investigation, we have assessed whether the presence of halogenated nucleosides in DNA diminishes the frequency of interaction of topo I with DNA and thus the frequency with which the stabilisation of cleavage complexes by the topo I poison camptothecin (CPT) takes place, in such a way that it protects from chromosome breakage and sister-chromatid exchange. This protective effect is shown to parallel a loss in halogen-substituted cells of the otherwise CPT-increased catalytic activity bound to DNA.

  5. Analysis of spontaneous and streptonigrin-induced sister chromatid exchanges in peripheral lymphocytes of aircrew members of international flights.

    Science.gov (United States)

    Sánchez, Julieta; Bianchi, Martha Susana; Ciancio, Vicente Rubén; Bolzán, Alejandro Daniel

    2008-01-01

    In this work, we extend our previous studies concerning mutagen sensitivity in flight personnel from commercial airlines by analyzing the frequency of spontaneous and streptonigrin (SN)-induced sister chromatid exchanges (SCEs) in peripheral blood lymphocytes of 18 long-haul aircrew members from Argentina and of 18 control individuals. Statistical analysis revealed no significant differences between aircrew and controls in the background level of SCEs (p > 0.05), which suggests that chronic exposure to cosmic radiation and other occupational hazards does not affect SCEs frequency in peripheral lymphocytes of aircrews. The fact that almost no correlation was found between cumulative flight hours and the yield of spontaneous SCEs in aircrews adds further support to this assumption. Therefore, the background SCEs frequency cannot be use as a valid biomarker to determine the genotoxic effects of cosmic radiation or other occupational hazards exposure in aircrews. Following SN treatment, a significant increase in the mean frequency of SCEs was observed in the control group (p aircrew group (p > 0.05), suggesting that at the population level, aircrew are more resistant to the mutagenic effects of SN than controls. The reasons of this resistance remain to be determined. Since cosmic radiation had no effect on the background SCEs frequency and no relationship was found between cumulative flight hours and SCEs inducer effect by SN in aircrews, a direct effect of cosmic radiation on SN resistance should be discarded.

  6. Influence of retinol on carcinogen-induced sister chromatid exchangers and chromosome aberrations in V79 cells

    Energy Technology Data Exchange (ETDEWEB)

    Qin, S.; Batt, T.; Huang, C.C.

    1985-01-01

    The influence of retinol (Rol) on sister chromatid exchangers (SCE) in V79 cells induced by six indirect and two direct carcinogens, and on chromosome aberration (CA) in V79 cells induced by four indirect carcinogens were studied. The indirect carcinogens used were aflatoxin B/sub 1/ (AFB), cyclophosphamide (CPP), benzo(a)anthracene (BA), benzo(a)pyrene (BP), 9,10-dimethyl-1,2-benz(a)anthracene (DMBA), and 3-methylcholanthrene (MCA). The two direct carcinogens were ethyl methane sulfonate (EMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Rol effectively inhibited SCE and CA induced by AFB and CPP in a dose-dependent manner, but it had no effect on SCE induced by BA, BP, DMBA, MCA, EMS, and MNNG. To the contrary, Rol had an enhancing effect on CA induced by BP and DMBA. The possibility that Rol exerts its anticarcinogenic effects by inhibiting certain forms of the cytochrome P-450 isoenzymes required for activation of precarcinogens, such as AFB and CPP but not those enzymes required by BA, BP, DMBA, and MCA, is discussed.

  7. Human RECQ1 is a DNA damage responsive protein required for genotoxic stress resistance and suppression of sister chromatid exchanges.

    Directory of Open Access Journals (Sweden)

    Sudha Sharma

    Full Text Available BACKGROUND: DNA helicases are ubiquitous enzymes that unwind DNA in an ATP-dependent and directionally specific manner. Unwinding of double-stranded DNA is essential for the processes of DNA repair, recombination, transcription, and DNA replication. Five human DNA helicases sharing sequence similarity with the E. coli RecQ helicase have been identified. Three of the human RecQ helicases are implicated in hereditary diseases (Bloom syndrome, Werner syndrome, and Rothmund-Thomson syndrome which display clinical symptoms of premature aging and cancer. RECQ1 helicase is the most highly expressed of the human RecQ helicases; however, a genetic disease has yet not been linked to mutations in the RECQ1 gene, and the biological functions of human RECQ1 in cellular DNA metabolism are not known. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we report that RECQ1 becomes phosphorylated upon DNA damage and forms irradiation-induced nuclear foci that associate with chromatin in human cells. Depletion of RECQ1 renders human cells sensitive to DNA damage induced by ionizing radiation or the topoisomerase inhibitor camptothecin, and results in spontaneous gamma-H2AX foci and elevated sister chromatid exchanges, indicating aberrant repair of DNA breaks. Consistent with a role in homologous recombinational repair, endogenous RECQ1 is associated with the strand exchange protein Rad51 and the two proteins directly interact with high affinity. CONCLUSION/SIGNIFICANCE: Collectively, these results provide the first evidence for a role of human RECQ1 in the response to DNA damage and chromosomal stability maintenance and point to the vital importance of RECQ1 in genome homeostasis.

  8. Sister chromatid exchange assessment by chromosome orientation-fluorescence in situ hybridization on the bovine sex chromosomes and autosomes 16 and 26.

    Science.gov (United States)

    Revay, T; King, W A

    2012-01-01

    Mammalian genome replication and maintenance are intimately coupled with the mechanisms that ensure cohesion between the resultant sister chromatids and the repair of DNA breaks. Although a sister chromatid exchange (SCE) is an error-free swapping of precisely matched and identical DNA strands, repetitive elements adjacent to the break site can act as alternative template sites and an unequal sister chromatid exchange can result, leading to structural variations and copy number change. Here we test the vulnerability for SCEs of the repeat-rich bovine Y chromosome in comparison with X, 16 and 26 chromosomes, using chromosome orientation-fluorescence in situ hybridization. The mean SCE rate of the Y chromosome (0.065 ± 0.029) was similar to that of BTA16 and BTA26 (0.065, 0.055), but was only approximately half of that of the X chromosome (0.142). As the chromosomal length affects the number of SCE events, we adjusted the SCE rates of the Y, 16, and 26 chromosomes to the length of the largest chromosome X resulting in very similar adjusted SCE (SCE(adj)) rates in all categories. Our results - based on 3 independent bulls - show that, although the cattle Y chromosome is a chest full of repeated elements, their presence and the documented activity of repeats in SCE formation does not manifest in significantly higher SCE(adj) rates and suggest the importance of the structural organization of the Y chromosome and the role of alternative mitotic DNA repair mechanisms.

  9. A novel frameshift mutation in BLM gene associated with high sister chromatid exchanges (SCE) in heterozygous family members.

    Science.gov (United States)

    Ben Salah, Ghada; Hadj Salem, Ikhlas; Masmoudi, Abderrahmen; Kallabi, Fakhri; Turki, Hamida; Fakhfakh, Faiza; Ayadi, Hamadi; Kamoun, Hassen

    2014-11-01

    The Bloom syndrome (BS) is an autosomic recessive disorder comprising a wide range of abnormalities, including stunted growth, immunodeficiency, sun sensitivity and increased frequency of various types of cancer. Bloom syndrome cells display a high level of genetic instability, including a 10-fold increase in the sister chromatid exchanges (SCE) level. Bloom syndrome arises through mutations in both alleles of the BLM gene, which was identified as a member of the RecQ helicase family. In this study, we screened a Tunisian family with three BS patients. Cytogenetic analysis showed several chromosomal aberrations, and an approximately 14-fold elevated SCE frequency in BS cells. A significant increase in SCE frequency was observed in some family members but not reaching the BS patients values, leading to suggest that this could be due to the heterozygous profile. Microsatellite genotyping using four fluorescent dye-labeled microsatellite markers revealed evidence of linkage to BLM locus and the healthy members, sharing higher SCE frequency, showed heterozygous haplotypes as expected. Additionally, the direct BLM gene sequencing identified a novel homozygous frameshift mutation c.3617-3619delAA (p.K1207fsX9) in BS patients and a heterozygous BLM mutation in the family members with higher SCE frequency. Our findings suggest that this latter mutation likely leads to a reduced BLM activity explaining the homologous recombination repair defect and, therefore, the increase in SCE. Based on the present data, the screening of this mutation could contribute to the rapid diagnosis of BS. The genetic confirmation of the mutation in BLM gene provides crucial information for genetic counseling and prenatal diagnosis.

  10. Review of the international symposium, sister chromatid exchanges: twenty-five years of experimental research

    Energy Technology Data Exchange (ETDEWEB)

    Tice, R.R.; Lambert, B.; Morimoto, Kanehisa; Hollaender, A.

    1983-01-01

    The purpose of this symposium was to honor initial research at Brookhaven by bringing internationally recognized leaders in the fields of genetics, cytogenetics, carcinogenesis, mutagenesis, radiation biology, toxicology, and environmental health together into an open forum to present and discuss: (1) current knowledge of the induction and formation of SCEs and their relationship to other biological endpoints, including carcinogenesis, mutagenesis, transformation, clastogenesis, DNA damage and repair, and cellular toxicity; (2) the optimal strategies for the utilization of SCEs in genetic toxicology testing schemes involving in vitro and in vivo exposure situations; (3) the most valid statistical methods for analyzing SCE data obtained from cells in culture, from cells in intact organisms, and from cells in humans; (4) the relevance of SCEs as an indicator of human disease states, both inherited and acquired, and of progress in disease treatment; and (5) the use of SCEs as an indicator of human exposure to genotoxic agents and their relevance as a prognosticator of future adverse health outcomes. This report summarizes the presentations. 7 references. (ACR)

  11. Mutagenicity in Salmonella and sister chromatid exchange in mice for 1,4-, 1,3-, 2,4-, and 3,4-dimethylphenanthrenes.

    Science.gov (United States)

    Sinsheimer, J E; Giri, A K; Hooberman, B H; Jung, K Y; Gopalaswamy, R; Koreeda, M

    1991-01-01

    The mutagenicity in Salmonella and in vivo sister chromatid exchange in the bone-marrow cells of mice was determined for 1,4-, 1,3-, 2,4-, and 3,4-dimethylphenanthrene (DMPh) with the objective to study the relative importance of substitution at the 1 and 4 positions of this series of methylated phenanthrenes. For both tests, 1,4- DMPh was decidedly more genotoxic than the remaining regioisomers. While the well recognized role of steric crowding in the bay region is a factor in this enhanced genotoxicity, equally important is substitution at the 1 position with its potential to inhibit detoxication through 9,10-diol formation.

  12. Mutagenicity in Salmonella and sister chromatid exchange in mice for 1,4-, and 1,3-, 2,4-, and 3,4-dimethylphenanthrenes

    Energy Technology Data Exchange (ETDEWEB)

    Sinsheimer, J.E.; Giri, A.K.; Hooberman, B.H.; Jung, K.Y.; Gopalaswamy, R.; Koreeda, M. (Univ. of Michigan, Ann Arbor (United States))

    1991-01-01

    The mutagenicity in Salmonella and in vivo sister chromatid exchange in the bone-marrow cells of mice was determined for 1,4-, 1,3-, 2,4-, and 3,4-dimethylphenanthrene (DMPh) with the objective to study the relative importance of substitution at the 1 and 4 positions of this series of methylated phenanthrenes. For both tests, 1,4-DMPh was decidedly more genotoxic than the remaining regioisomers. While the well recognized role of steric crowding in the bay region is a factor in this enhanced genotoxicity, equally important is substitution at the 1 position with its potential to inhibit detoxication through 9,10-diol formation.

  13. Genotoxic biomonitoring study of population residing in pesticide contaminated regions in Göksu Delta: micronucleus, chromosomal aberrations and sister chromatid exchanges.

    Science.gov (United States)

    Ergene, Serap; Celik, Ayla; Cavaş, Tolga; Kaya, Filiz

    2007-10-01

    Pesticides are widely used throughout the world in agriculture to protect crops and in public health to control diseases. Nevertheless, exposure to pesticides represents a potential risk to humans. This paper describes a study of possible genetic damage in the people living in regions contaminated with complex mixture of pesticides in Göksu Delta. In this study, used methods were chromosomal aberration (CA), sister chromatid exchange analysis (SCE) in the peripheral blood lymphocytes, and micronucleus (MN) assay in the buccal epithelial cells. In the present investigation, 32 affected subjects consist of 16 smoking and 16 non-smokings and an equal number of control subjects were assessed for genome damage. Micronucleus (MN), Broken egg (BE), Karyorrhexis (KR), Karyolysis (KL) and Binucleus (BN) frequencies were higher in affected subjects than in controls. Smoking had a statistically significant effect on the Micronucleus, Karyorrhexis and Binucleus frequencies for both the control and the exposed group. Also smoking and exposure affected the frequency of sister chromatid exchange and chromosomal aberrations compared with control groups.

  14. Reduction of diepoxybutane-induced sister chromatid exchanges by glutathione peroxidase and erythrocytes in transgenic Big Blue mouse and rat fibroblasts.

    Science.gov (United States)

    Erexson, G L; Tindall, K R

    2000-02-14

    We have investigated the effect of glutathione peroxidase (GSH-Px) and mammalian erythrocytes (RBCs) on spontaneous and diepoxybutane (DEB)-induced sister chromatid exchange (SCE) in primary Big Blue(R) mouse (BBM1) and Big Blue(R) rat (BBR1) fibroblasts. DEB is the putative carcinogenic metabolite of 1,3-butadiene (BD) for which inhalation exposure yields a high rate of malignancies in mice but not in rats. BD is metabolized differently in mice and rats, producing much higher levels of DEB in mice than in rats, which may partly explain the different carcinogenic responses. However, other factors may contribute to the observed differences in the rodent carcinogenic response to BD. DEB is a highly reactive compound. Upon epoxide hydrolysis, DEB can covalently bind to DNA bases. Likewise, DEB generates reactive oxygen species that, in turn, can either damage DNA or produce H(2)O(2). Reduced glutathione (GSH) is known to play a role in the metabolism and detoxification of DEB; and GSH is reduced by GSH-Px in the presence of H(2)O(2). GSH-Px is a constitutive enzyme that is found at high concentrations in mammalian RBCs. Therefore, we were interested in examining the role of RBCs and GSH-Px on DEB-induced SCE in rat and mouse cells for detection of possible differences in the species response. Transgenic BBM1 and BBR1 fibroblasts were treated with either 0, 2 or 4 microM DEB plus 0, 2 or 20 units of GSH-Px with and without 2x10(8) species-specific RBCs. DEB effectively induced SCEs in both rat and mouse cells. The relative induction of SCEs in both cell types was comparable. Both GSH-Px and RBCs alone and in combination were effective in significantly reducing DEB-induced SCEs in both mouse and rat fibroblasts, although there was more variability in the SCE response in rat cells. The present study suggests that GSH-Px may be important in the detoxification of DEB-induced DNA damage that results in the formation of SCEs.

  15. Psoralen/UVA treatment and chromosomes. I. Aberrations and sister chromatid exchange in human lymphocytes in vitro and synergism with caffeine

    Energy Technology Data Exchange (ETDEWEB)

    Waksvik, H.; Brogger, A.; Stene, J.

    1977-09-22

    Treatment of human lymphocytes in vitro with trimethylpsoralen or 8-methoxypsoralen and UVA irradiation (PUVA) induced chromosome damage, mainly constrictions and gaps, but also breaks and exchanges, and increased the frequency of sister chromatid exchange (SCE). The localization of the chromosome aberrations was nonrandom. The coincidence of many PUVA hits with mercaptoenthanol hits suggests that PUVA may have other targets in the cell than the DNA, perhaps the folding proteins of the chromosomes and the nuclear membrane/chromatin attachment organelles. Caffeine increased in a synergistic way the chromosome aberration yield if added after PUVA treatment, but there was no effect when caffeine was present before and during PUVA treatment. The SCE frequency was increased in the presence of caffeine.

  16. In Vitro genotoxic and antigenotoxic studies of Thai Noni fruit juice by chromosomal aberration and sister chromatid exchange assays in human lymphocytes

    Directory of Open Access Journals (Sweden)

    Treetip Ratanavalachai

    2008-09-01

    Full Text Available The genotoxic and antigenotoxic effects of Noni fruit juice produced in Thailand have been studied in human lymphocytes for chromosome aberration assay and sister chromatid exchange (SCE assay in vitro. Treatment of Noni fruit juice(3.1-50 mg/ml alone for 3 h did not significantly induce chromosomal aberration or SCE (p<0.05. Noni fruit juice at 6.2 mg/ml is the optimum dose for cell survival and cell replication as demonstrated by the highest value of mitotic index and proliferation index (P.I.. Interestingly, pretreatment of Noni fruit juice at the same concentration of 6.2 mg/ml for 2 hfollowed by mitomycin C treatment at 3 μg/ml for 2 h significantly reduced SCE level induced by mitomycin C (p<0.05. However, these treatments did not show significant decrease in chromatid-type aberrations. Our data indicate that Thai Noni fruit juice is not genotoxic against human lymphocytes in vitro. In addition, pretreatment of Noni fruit juice at 6.2 mg/ml demonstrated no anticlastogenic effect while had some antigenotoxic effects as demonstrated by significant decrease in the SCE level induced by mitomycin C (p<0.05. Therefore, the optimum dose of Noni fruit juice used as a traditional medicine is required and needs to be studied further for the benefit of human health.

  17. INVESTIGATION OF DNA REPAIR BY SISTER CHROMATID EXCHANGE (SCE) ANALYSIS AND THE ALKALINE SINGLE CELL GEL ASSAY (SCG) IN MAMMALIAN GO-LYMPHOCYTES AFTER IN VITRO EXPOSURE TO ETHYLENE OXIDE (EO)

    Science.gov (United States)

    Investigation ofDNA Repair by Sister Chromatid Exchange (SCE) Analysis and the Alkaline Single Cell Gel Assay (SCG) in Mammalian Go-Lymphocytes after In Vitro Exposure to Ethylene Oxide (EO). EO is a large volume chemical used primarily as an intermediate in manufacturing...

  18. Enhanced stimulation of chromosomal translocations and sister chromatid exchanges by either HO-induced double-strand breaks or ionizing radiation in Saccharomyces cerevisiae yku70 mutants

    Energy Technology Data Exchange (ETDEWEB)

    Fasullo, Michael [Ordway Research Institute, 150 New Scotland Avenue, Albany, NY 12209 (United States)]. E-mail: mfasullo@ordwayresearch.org; St Amour, Courtney [Ordway Research Institute, 150 New Scotland Avenue, Albany, NY 12209 (United States); Zeng Li [Ordway Research Institute, 150 New Scotland Avenue, Albany, NY 12209 (United States)

    2005-10-15

    DNA double-strand break (DSB) repair occurs by homologous recombination (HR) or non-homologous endjoining (NHEJ). In Saccharomyces cerevisiae, expression of both MAT a and MAT{alpha} inhibits NHEJ and facilitates DSB-initiated HR. We previously observed that DSB-initiated recombination between two his3 fragments, his3-{delta}5' and his3-{delta}3'::HOcs is enhanced in haploids and diploids expressing both MAT a and MAT{alpha} genes, regardless of the position or orientation of the his3 fragments. Herein, we measured frequencies of DNA damage-associated translocations and sister chromatid exchanges (SCEs) in yku70 haploid mutants, defective in NHEJ. Translocation and SCE frequencies were measured in strains containing the same his3 fragments after DSBs were made directly at trp1::his3-{delta}3'::HOcs. Wild type and yku70 cells were also exposed to ionizing radiation and radiomimetic agents methyl methanesulfonate (MMS), phleomycin, and 4-nitroquinolone-1-oxide (4-NQO). Frequencies of X-ray-associated and DSB-initiated translocations were five-fold higher in yku70 mutants compared to wild type; however, frequencies of phleomycin-associated translocations were lower in the yku70 haploid mutant. Frequencies of DSB-initiated SCEs were 1.8-fold higher in the yku70 mutant, compared to wild type. Thus, DSB-initiated HR between repeated sequences on non-homologous chromosomes and sister chromatids occurs at higher frequencies in yku70 haploid mutants; however, higher frequencies of DNA damage-associated HR in yku70 mutants depend on the DNA damaging agent.

  19. Field Verification Program (Aquatic Disposal). Sister Chromatid Exchange in Marine Polychaetes Exposed to Black Rock Harbor Sediment.

    Science.gov (United States)

    1985-07-01

    improbable that relationships would be detected given the variability inherent in the data. With a sample size of seven, the correlation coefficient would have...strain TA2637) with metabolic activation (Tikkanen, Matsushima, and Natori 1983), possibly via the generation of active oxygen (Brown 1980; Chesis ...Exchange as an Indicator of Mutagenesis," Nature (London), Vol 2- , p 551-553. Chesi , P. I., Levin, D. E., Smith, M. T., Ernster, L., and Ames, B. N. 1984

  20. Genotoxic effects of a particular mixture of acetamiprid and alpha-cypermethrin on chromosome aberration, sister chromatid exchange, and micronucleus formation in human peripheral blood lymphocytes.

    Science.gov (United States)

    Kocaman, Ayşe Yavuz; Topaktaş, Mehmet

    2010-04-01

    The genotoxic effects of a particular mixture of acetamiprid (Acm, neonicotinoid insecticide) and alpha-cypermethrin (alpha-cyp, pyrethroid insecticide) on human peripheral lymphocytes were examined in vitro by chromosomal aberrations (CAs), sister chromatid exchange (SCE), and micronucleus (MN) tests. The human peripheral lymphocytes were treated with 12.5 + 2.5, 15 + 5, 17.5 + 7.5, and 20 + 10 microg/mL of Acm+alpha-cyp, respectively, for 24 and 48 h. The mixture of Acm+alpha-cyp induced the CAs and SCEs at all concentrations and treatment times when compared with both the control and solvent control and these increases were concentration-dependent in both treatment times. MN formation was significantly induced at 12.5 + 2.5, 15 + 5, 17.5 + 7.5, microg/mL of Acm+alpha-cyp when compared with both controls although these increases were not concentration-dependent. Binuclear cells could not be detected sufficiently in the highest concentration of the mixture (20 + 10 microg/mL) for both the 24- and 48-h treatment times. Mitotic index (MI), proliferation index (PI) and nuclear division index (NDI) significantly decreased because of the cytotoxic and cytostatic effects of the mixture, at all concentrations for two treatment periods. Significant decreases in MI and PI were concentration dependent at both treatment times. The decrease in NDI was also concentration-dependent at 48-h treatment period. In general, Acm+alpha-cyp inhibited nuclear division more than positive control, mitomycin C (MMC) and showed a higher cytostatic effect than MMC. Furthermore, in this article, the results of combined effects of Acm+alpha-cyp were compared with the results of single effects of Acm or alpha-cyp (Kocaman and Topaktas,2007,2009, respectively). In conclusion, the particular mixture of Acm+alpha-cyp synergistically induced the genotoxicity/cytotoxicity in human peripheral blood lymphocytes.

  1. Sister chromatid exchange and micronucleus frequency in human lymphocytes of 1,650 subjects in an Italian population: II. Contribution of sex, age, and lifestyle.

    Science.gov (United States)

    Barale, R; Chelotti, L; Davini, T; Del Ry, S; Andreassi, M G; Ballardin, M; Bulleri, M; He, J; Baldacci, S; Di Pede, F; Gemignani, F; Landi, S

    1998-01-01

    Sister chromatid exchange (SCE) and micronuclei (MN) analysis was carried out on 1,650 healthy individuals living in Pisa and in two nearby small cities, Cascina and Navacchio (Ca-Na). The effect of smoking on SCEs was linearly correlated with the number of cigarettes per day, and an increase of 7.3% SCEs was detectable for as few cigarettes as 1-10/day. Ex-smokers showed intermediate mean values of SCEs (8.09 +/- 1.88) in comparison with never smokers (7.54 +/- 1.61) and current smokers (8.45 +/- 1.94). Mean values of SCEs of ex-smokers decreased linearly with time of smoking cessation, reaching the mean values of never smokers within 8 years. The extent of SCE decrease was inversely proportional to the number of cigarettes previously smoked. No interaction between smoking habits and coffee or alcohol drinking on SCEs was observed. A borderline (P = 0.053) increase in mean SCE values in coffee drinkers (more than 3 cups/day) was found. The age effect on SCEs was remarkable in Ca-Na, but not in Pisa donors. Job type was not associated with significant modification of mean values of SCEs. Multiple logistic regression analysis revealed a statistically significant association between the proportion of high frequency cells (HCF) outliers and coffee consumption. Age and sex appeared to be by far the most important variables associated with modifications in MN frequency, which increased by 0.04 per thousand and 0.02 per thousand per year in males and females, respectively. Children and young donors (age students (+0.71 and +0.55 per thousand, respectively). Smoking did not determine any increase of MN frequency. A total lack of correlation (P = 0.913) between MN and SCEs was observed.

  2. Investigation of Homologous Crossing over and Sister Chromatid Exchange in the Wheat Nor-B2 Locus Coding for Rrna and Gli-B2 Locus Coding for Gliadins

    Science.gov (United States)

    Dvořák, J.; Appels, R.

    1986-01-01

    Recombination was investigated within the Nor-B2 locus of wheat chromosome 6B that contains several thousand of the 18S-5.8S-26S rRNA (rDNA) repeated units. Additionally, recombination was assessed for several chromosome regions, in arm 6Bq between the centromere and the B2 locus (awn suppressor) and in arm 6Bp between the centromere and Nor-B2, between Nor-B2 and a distal C-band and between Nor-B2 and Gli-B2 coding for gliadins. The experimental design permitted the distinction between crossing over between homologous chromosomes and exchange between sister chromatids. No homologous crossing over within the Nor-B2 locus was found in a sample of 446 chromosomes, but one exchange with the attributes of unequal sister chromatid exchange was identified. The molecular characteristics of this presumed sister chromatid exchange indicate that the spacer variants present in the Nor-B2 locus are clustered. No homologous recombination was detected within the distal Gli-B2 locus containing repeated genes coding for gliadin seed-storage proteins. Both arms of chromosome 6B showed low crossing-over frequency in the proximal regions. The distance from the centromere to Nor-B2 was only from 0.3 to 2.2 cM although it accounts for about two-thirds of the metaphase chromosome arm, which shows a great distortion of the metaphase map of the arm. The level of homologous recombination within the Nor-B2 locus is lower than in the chromosome region immediately distal to it. Whether it is comparable to that in the chromosome region proximal to it could not be determined. Recombination frequencies of different pairs of chromosome 6B in all but one interval paralleled the frequencies of their metaphase I pairing: Lower pairing at metaphase I was paralleled by lower crossing-over frequency. This relationship indicated that reduced metaphase I pairing between 6B chromosomes from different populations is due to impaired crossing-over and not due to precocious chiasma terminalization. PMID

  3. The chromosome damage induced by x-ray radiation doses. Comparison between dicentric chromosomes, micronuclei and Sister Chromatid Exchanges analyses. Valoracion de dao cromosomico originado por una dosis de rayos X. Comparacion de los analisis de cromosomas dicentricos, micronucleos e intercambios entre cromatidas hermanas

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, J.L.; Losada, C.; Losada, G.; Veiras, C. (Centro Oncologico de Galicia. La Corua (Spain)); Goyanes, V.J. (Hospital ' ' Teresa Herrera' ' . La Corua (Spain))

    1993-01-01

    Exposure to ionizing radiations is a well-known source of chromosome damage. Here we present a comparison among three different methodologies employed to recognize cytogenetic damage, after an acute exposure of human lymphocytes to 3 Gy of X-rays (100kVp). Scoring of dicentric chromosomes, present in first mitosis ''in vitro'', was the method of preference as dicentrics increased 937.5 times with respect to background. Micronucleus scoring in binucleated-cytokinesis blocked cells showed an increase of 32.5 times, while it was only of 1.46 times when Sister Chromatid Exchanges (SCEs) were analyzed. The estimated probability of an acentric fragment becoming a micronucleus was around 0.25. Intercellular distribution of dicentrics agree with Poisson, while micronucleus were overdispersed. When analyzed at second cycle after damage induction, the dicentrics yield as well as the level of cells with unstable cromosome aberrations, decreased around a half. Finally, SCEs level was similar in cells with or without unstable structural chromosome aberrations. (Author)

  4. Similar Sister Chromatid Arrangement in Mono- and Holocentric Plant Chromosomes.

    Science.gov (United States)

    Schubert, Veit; Zelkowski, Mateusz; Klemme, Sonja; Houben, Andreas

    2016-01-01

    Due to the X-shape formation at somatic metaphase, the arrangement of the sister chromatids is obvious in monocentric chromosomes. In contrast, the sister chromatids of holocentric chromosomes cannot be distinguished even at mitotic metaphase. To clarify their organization, we differentially labelled the sister chromatids of holocentric Luzula and monocentric rye chromosomes by incorporating the base analogue EdU during replication. Using super-resolution structured illumination microscopy (SIM) and 3D rendering, we found that holocentric sister chromatids attach to each other at their contact surfaces similar to those of monocentrics in prometaphase. We found that sister chromatid exchanges (SCEs) are distributed homogeneously along the whole holocentric chromosomes of Luzula, and that their occurrence is increased compared to monocentric rye chromosomes. The SCE frequency of supernumerary B chromosomes, present additionally to the essential A chromosome complement of rye, does not differ from that of A chromosomes. Based on these results, models of the sister chromatid arrangement in mono- and holocentric plant chromosomes are presented.

  5. Effects of caffeine on sister chromatid exchange (SCE) after exposure to uv light or triaziquone studied with a fluorescence plus giemsa (FPG) technique

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, W.; Bauknecht, T.

    1978-01-19

    Studies are reported that are designed to analyze the mechanism by which caffeine reduces the induction of SCE by uv light or alkylating agents. The substantial points are (1) caffeine does not inhibit SCE formatin, and (2) the caffeine-mediated apparent decrease of SCE induction after uv or triaziquone, exposure is due to a selective destruction of those metaphases otherwise exhibiting a high number of SCE. These findings and their relevance to the ascertainment of the SCE-forming process are discussed.

  6. Evidence that cyclophosphamide can to induce exchanges in the sister chromatids (ICH) through secondary injuries; Evidencia de que la ciclofosfamida puede inducir intercambios en las cromatidas hermanas (ICH) a traves de lesiones secundarias

    Energy Technology Data Exchange (ETDEWEB)

    Morales R, P.; Rodriguez R, R. [Instituto Nacional de Investigaciones nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    By means of the use of destination protocol of ICH inductive injuries (DLI-ICH), it was studied if interchanges in the sister chromatids (ICH) induced by cyclophosphamide (CP), in the second post-treatment division (ICH-2) are produced by secondary injuries or by fresh injuries. For discard between these possibilities it was administered CP at different periods before of the first post-treatment division, taking as reference the administered time for high dose of bromodeoxyuridine (BrdU ) which was approximately at the beginning of this division. The ICH frequencies that occur in the first, the second and the third synthesis stages (S) were determined. It was observed that when the administered CP was four hours before BrdU , the ICH frequencies of the second and the third S were reduced. The frequency of the first ICH increased lightly in relation to those of the normal protocol (0.5 h before BrdU ) and that the supplying of CP six hours before caused almost a total reduction of ICH of second and third S and an important increment of ICH of first S.This was interpreted as evidence that the ICH-2 are product of secondary injuries. (Author)

  7. Sister chromatid cohesion and recombination in meiosis

    NARCIS (Netherlands)

    Heemst, van D.; Heyting, C.

    2000-01-01

    Sister chromatids are associated from their formation until their disjunction. Cohesion between sister chromatids is provided by protein complexes, of which some components are conserved across the kingdoms and between the mitotic and meiotic cell cycles. Sister chromatid cohesion is intimately link

  8. Cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with accelerated 56Fe ions

    Science.gov (United States)

    Suzuki, M.; Piao, C.; Hall, E. J.; Hei, T. K.

    2001-01-01

    We examined cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with high-energy 56Fe ions. Cells were irradiated with graded doses of 56Fe ions (1 GeV/nucleon) accelerated with the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The survival curves for cells plated 1 h after irradiation (immediate plating) showed little or no shoulder. However, the survival curves for cells plated 24 h after irradiation (delayed plating) had a small initial shoulder. The RBE for 56Fe ions compared to 137Cs gamma rays was 1.99 for immediate plating and 2.73 for delayed plating at the D10. The repair ratio (delayed plating/immediate plating) was 1.67 for 137Cs gamma rays and 1.22 for 56Fe ions. The dose-response curves for initially measured and residual chromatid fragments detected by the Calyculin A-mediated premature chromosome condensation technique showed a linear response. The results indicated that the induction frequency for initially measured fragments was the same for 137Cs gamma rays and 56Fe ions. On the other hand, approximately 85% of the fragments induced by 137Cs gamma rays had rejoined after 24 h of postirradiation incubation; the corresponding amount for 56Fe ions was 37%. Furthermore, the frequency of chromatid exchanges induced by gamma rays measured 24 h after irradiation was higher than that induced by 56Fe ions. No difference in the amount of chromatid damage induced by the two types of radiations was detected when assayed 1 h after irradiation. The results suggest that high-energy 56Fe ions induce a higher frequency of complex, unrepairable damage at both the cellular and chromosomal levels than 137Cs gamma rays in the target cells for radiation-induced lung cancers.

  9. Sister chromatid gene conversion is a prominent double-strand break repair pathway in mammalian cells

    OpenAIRE

    Johnson, Roger D.; Jasin, Maria

    2000-01-01

    In mammalian cells, repair of DNA double-strand breaks (DSBs) occurs by both homologous and non-homologous mechanisms. By definition, homologous recombination requires a template with sufficient sequence identity to the damaged molecule in order to direct repair. We now show that the sister chromatid acts as a repair template in a substantial proportion of DSB repair events. The outcome of sister chromatid repair is primarily gene conversion unassociated with reciprocal exchange. This contras...

  10. Role of oxidative stress and intracellular calcium in nickel carbonate hydroxide-induced sister-chromatid exchange, and alterations in replication index and mitotic index in cultured human peripheral blood lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    M' Bemba-Meka, Prosper [Universite de Montreal, Human Toxicology Research Group (TOXHUM), Department of Environmental and Occupational Health, Main Station, P.O. Box 6128, Montreal, QC (Canada); University of Louisville, Department of Pharmacology and Toxicology, Center for Genetics and Molecular Medicine, Louisville, KY (United States); Lemieux, Nicole [Universite de Montreal, Department of Pathology and Cellular Biology, Faculty of Medicine, Main Station, P.O. Box 6128, Montreal, QC (Canada); Chakrabarti, Saroj K. [Universite de Montreal, Human Toxicology Research Group (TOXHUM), Department of Environmental and Occupational Health, Main Station, P.O. Box 6128, Montreal, QC (Canada)

    2007-02-15

    Human peripheral lymphocytes from whole blood cultures were exposed to either soluble form of nickel carbonate hydroxide (NiCH) (0-60 {mu}M), or of nickel subsulfide (Ni{sub 3}S{sub 2}) (0-120 {mu}M), or of nickel oxide (NiO) (0-120 {mu}M), or nickel sulfate (NiSO{sub 4}) (0-120 {mu}M) for a short duration of 2 h. The treatments occurred 46 h after the beginning of the cultures. The cultures were harvested after a total incubation of 72 h, and sister-chromatid exchange (SCE), replication index (RI), and mitotic index (MI) were measured for each nickel compound. The soluble form of NiCH at 30 {mu}M but those of Ni{sub 3}S{sub 2} and NiO at 120 {mu}M produced significant increase in the SCE per cell compared to the control value, whereas NiSO{sub 4} failed to produce any such significant increase. Except NiSO{sub 4}, the soluble forms of NiCH, Ni{sub 3}S{sub 2}, and NiO produced significant cell-cycle delay (as measured by the inhibition of RI) as well as significant inhibition of the MI at respective similar concentrations as mentioned above. Pretreatment of human blood lymphocytes with catalase (H{sub 2}O{sub 2} scavenger), or superoxide dismutase (superoxide anion scavenger), or dimethylthiourea (hydroxyl radical scavenger), or deferoxamine (iron chelator), or N-acetylcysteine (general antioxidant) inhibited NiCH-induced SCE, and changes in RI and MI. This suggests the participation of oxidative stress involving H{sub 2}O{sub 2}, the superoxide anion radical, the hydroxyl radical, and iron in the NiCH-induced genotoxic responses. Cotreatment of NiCH with either verapamil (inhibitor of intracellular calcium ion ([Ca{sup 2+}]{sub i}) movement through plasma membranes), or dantrolene (inhibitor of [Ca{sup 2+}]{sub i} release from sarcoplasmic reticulum), or BAPTA (Ca{sup 2+} chelator) also inhibited the NiCH-induced responses. These results suggest that [Ca{sup 2+}]{sub i} is also implicated in the genotoxicity of NiCH. Overall these data indicate that various types

  11. Inductive phenomena at low frequencies in impedance spectra of proton exchange membrane fuel cells - A review

    Science.gov (United States)

    Pivac, Ivan; Barbir, Frano

    2016-09-01

    The results of electrochemical impedance spectroscopy of proton exchange membrane (PEM) fuel cells may exhibit inductive phenomena at low frequencies. The occurrence of inductive features at high frequencies is explained by the cables and wires of the test system. However, explanation of inductive loop at low frequencies requires a more detailed study. This review paper discusses several possible causes of such inductive behavior in PEM fuel cells, such as side reactions with intermediate species, carbon monoxide poisoning, and water transport, also as their equivalent circuit representations. It may be concluded that interpretation of impedance spectra at low frequencies is still ambiguous, and that better equivalent circuit models are needed with clearly defined physical meaning of each of the circuit elements.

  12. Sister chromatid segregation in meiosis II

    Science.gov (United States)

    Wassmann, Katja

    2013-01-01

    Meiotic divisions (meiosis I and II) are specialized cell divisions to generate haploid gametes. The first meiotic division with the separation of chromosomes is named reductional division. The second division, which takes place immediately after meiosis I without intervening S-phase, is equational, with the separation of sister chromatids, similar to mitosis. This meiotic segregation pattern requires the two-step removal of the cohesin complex holding sister chromatids together: cohesin is removed from chromosome arms that have been subjected to homologous recombination in meiosis I and from the centromere region in meiosis II. Cohesin in the centromere region is protected from removal in meiosis I, but this protection has to be removed—deprotected”—for sister chromatid segregation in meiosis II. Whereas the mechanisms of cohesin protection are quite well understood, the mechanisms of deprotection have been largely unknown until recently. In this review I summarize our current knowledge on cohesin deprotection. PMID:23574717

  13. Test for Chemical Induction of Chromosome Aberrations in Cultured Chinese Hamster (CHO) Cells With and Without Metabolic Activation, Test Acticle: Ethylenediamine Dinitrate (EDDN)

    Science.gov (United States)

    2010-02-25

    chromosomes leading to four-armed configurations. This could be asymmetrical with formation of a dicentric and an acentric chromatid, ifunion is complete, or...a shortened monocentric chromosome , and where there is no sister chromatid union. Dicentric - an asymmetrical exchange between two chromosomes ...a shortened monocentric chromosome , and where there is no sister chromatid union. Dicentric - an asymmetrical exchange between two chromosomes

  14. Plasma exchange for induction and cyclosporine A for maintenance of remission in Wegener's granulomatosis--a clinical randomized controlled trial

    DEFF Research Database (Denmark)

    Szpirt, Wladimir M; Heaf, James G; Petersen, Jørgen

    2011-01-01

    The use of plasma exchange (PE) for induction treatment of anti-neutrophil cytoplasm autoantibody (ANCA)-associated vasculitis (AAV), including Wegener's granulomatosis (WG), is still controversial. The use of PE in AAV is not commonly accepted in patients with a plasma creatinine......The use of plasma exchange (PE) for induction treatment of anti-neutrophil cytoplasm autoantibody (ANCA)-associated vasculitis (AAV), including Wegener's granulomatosis (WG), is still controversial. The use of PE in AAV is not commonly accepted in patients with a plasma creatinine...

  15. Mechanics of Sister Chromatids studied with a Polymer Model English

    Science.gov (United States)

    Zhang, Yang; Isbaner, Sebastian; Heermann, Dieter

    2013-10-01

    Sister chromatid cohesion denotes the phenomenon that sister chromatids are initially attached to each other in mitosis to guarantee the error-free distribution into the daughter cells. Cohesion is mediated by binding proteins and only resolved after mitotic chromosome condensation is completed. However, the amount of attachement points required to maintain sister chromatid cohesion while still allowing proper chromosome condensation is not known yet. Additionally the impact of cohesion on the mechanical properties of chromosomes also poses an interesting problem. In this work we study the conformational and mechanical properties of sister chromatids by means of computer simulations. We model both protein-mediated cohesion between sister chromatids and chromosome condensation with a dynamic binding mechanisms. We show in a phase diagram that only specific link concentrations lead to connected and fully condensed chromatids that do not intermingle with each other nor separate due to entropic forces. Furthermore we show that dynamic bonding between chromatids decrease the Young's modulus compared to non-bonded chromatids.

  16. Mechanics of Sister Chromatids studied with a Polymer Model

    Directory of Open Access Journals (Sweden)

    Yang eZhang

    2013-10-01

    Full Text Available Sister chromatid cohesion denotes the phenomenon that sister chromatids are initially attached to each other in mitosis to guarantee the error-free distribution into the daughter cells. Cohesion is mediated by binding proteins and only resolved after mitotic chromosome condensation is completed. However, the amount of attachement points required to maintain sister chromatid cohesion while still allowing proper chromosome condensation is not known yet. Additionally the impact of cohesion on the mechanical properties of chromosomes also poses an interesting problem. In this work we study the conformational and mechanical properties of sister chromatids by means of computer simulations. We model both protein-mediated cohesion between sister chromatids and chromosome condensation with a dynamic binding mechanisms. We show in a phase diagram that only specific link concentrations lead to connected and fully condensed chromatids that do not intermingle with each other nor separate due to entropic forces. Furthermore we show that dynamic bonding between chromatids decrease the Young's modulus compared to non-bonded chromatids.

  17. Induction

    DEFF Research Database (Denmark)

    Sprogøe, Jonas; Elkjaer, Bente

    2010-01-01

    The purpose of this paper is to explore how induction of newcomers can be understood as both organizational renewal and the maintenance of status quo, and to develop ways of describing this in terms of learning.......The purpose of this paper is to explore how induction of newcomers can be understood as both organizational renewal and the maintenance of status quo, and to develop ways of describing this in terms of learning....

  18. 石油作业女性染色单体交换与习惯性流产关系研究%Study on the relationship between sister chromatid exchange and habitual abortion among the women in the petroleum operations

    Institute of Scientific and Technical Information of China (English)

    慕明涛; 霍满鹏; 蒲力群; 张静; 刘俊俊

    2012-01-01

    目的:分析石油作业女性外周血淋巴细胞姐妹染色单体互换( SCE)对习惯性流产的影响.方法:随机选择习惯性流产的石油作业女性26人为观察组和正常的育龄女性18人为对照组,检测其外周血淋巴细胞姐妹染色单体互换,记势SCE发生率.结果:观察组的外周血淋巴细胞SCE发生率为8.66 ±0.61明显高于对照组,差异有统计学意义(P<0.05).结论:SCE的发生可作为石油作业习惯性流产女性染色体结构稳定性的检测指标.石油作业环境中的某些有害物质对女性DNA损伤有一定的影响.%Objective; To analyze the effect of sister chromatid exchange (SCE) in lymphocytes in peripheral blood of the women in the petroleum operations on habitual abortion. Methods: Twenty - six women in the petroleum operations with habitual abortion and 18 normal women at childbearing age were selected randomly as observation group and control group respectively. SCE in lymphocytes in peripheral blood was detected, and the incidence was recorded. Results; The incidence of SCE in lymphocytes in peripheral blood of observation group was (8. 66 ±0. 61), which was significantly higher than that in control group (P <0. 05) . Conclusion; The occurrence of SCE can be used as a index to detect the structural stability of chromosomes in women with habitual abortion; some harmful substances in the environment in petroleum operations have a certain impact on injury of female DNA.

  19. Enhanced G2 chromatid radiosensitivity in dyskeratosis congenita fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    DeBauche, D.M.; Pai, G.S.; Stanley, W.S. (Medical Univ. of South Carolina, Charleston (USA))

    1990-02-01

    Dyskeratosis congenita (DC) is an inherited disorder characterized by reticular pigmentation of the skin, dystrophic nails, mucosal leukoplakia, and a predisposition to cancer in early adult life. In the majority of cases, DC is an X-linked recessive trait. However, one or more autosomal form(s) of DC may exist. Although excessive spontaneous chromatid breakage has been reported in DC, it is not a consistent cytological marker for this disorder. We examined the frequency and specificity of X-irradiation-induced G2 chromatid breakage in fibroblasts from three unrelated DC patients (two males and one female). Metaphase cells from DC patients had significantly more chromatid breaks (16-18-fold and 17-26-fold at 50 and 100 rad X-irradiation, respectively) and chromatid gaps (10-12-fold and 6-7-fold at 50 and 100 rad, respectively) than those from two different controls. Analysis of banded chromosomes revealed a nonrandom distribution of chromatid aberrations in DC but not in controls, a distribution corresponding to some of the known breakpoints for cancer-specific rearrangements, constitutive fragile sites, and/or loci for cellular proto-oncogenes. The significance of this finding for cancer predisposition in DC patients is uncertain, but the increased susceptibility of X-irradiation-induced chromatid breakage may serve as a cellular marker of diagnostic value.

  20. Sister chromatid segregation in meiosis II: deprotection through phosphorylation.

    Science.gov (United States)

    Wassmann, Katja

    2013-05-01

    Meiotic divisions (meiosis I and II) are specialized cell divisions to generate haploid gametes. The first meiotic division with the separation of chromosomes is named reductional division. The second division, which takes place immediately after meiosis I without intervening S-phase, is equational, with the separation of sister chromatids, similar to mitosis. This meiotic segregation pattern requires the two-step removal of the cohesin complex holding sister chromatids together: cohesin is removed from chromosome arms that have been subjected to homologous recombination in meiosis I and from the centromere region in meiosis II. Cohesin in the centromere region is protected from removal in meiosis I, but this protection has to be removed--deprotected--for sister chromatid segregation in meiosis II. Whereas the mechanisms of cohesin protection are quite well understood, the mechanisms of deprotection have been largely unknown until recently. In this review I summarize our current knowledge on cohesin deprotection.

  1. Test for Chemical Induction of Chromosome Aberrations in Cultured Chinese Hamster Ovary (CHO) Cells With and Without Metabolic Activation. Test Article: Dimethylamine-2-2ethyl azide (DMAZ)

    Science.gov (United States)

    2008-07-26

    chromosomes leading to four-armed configurations. This could be asymmetrical with formation of a dicentric and an acentric chromatid, ifunion is complete...chromatid union. Dicentric - an asymmetrical exchange between two chromosomes resulting in a chromosome with two centromeres with or without an...no sister chromatid union. ’ d - Dicentric - an asymmetrical exchange between two chromosomes resulting, r dm in a chromosome with two centromeres

  2. EXCHANGE

    Energy Technology Data Exchange (ETDEWEB)

    Boltz, J.C. (ed.)

    1992-09-01

    EXCHANGE is published monthly by the Idaho National Engineering Laboratory (INEL), a multidisciplinary facility operated for the US Department of Energy (DOE). The purpose of EXCHANGE is to inform computer users about about recent changes and innovations in both the mainframe and personal computer environments and how these changes can affect work being performed at DOE facilities.

  3. Precocious Sister Chromatid Separation (PSCS) in Cornelia de Lange Syndrome

    Science.gov (United States)

    Kaur, Maninder; DeScipio, Cheryl; McCallum, Jennifer; Yaeger, Dinah; Devoto, Marcella; Jackson, Laird G.; Spinner, Nancy B.; Krantz, Ian D.

    2009-01-01

    The Cornelia de Lange syndrome (CdLS) (OMIM# 122470) is a dominantly inherited multisystem developmental disorder. The phenotype consists of characteristic facial features, hirsutism, abnormalities of the upper extremities ranging from subtle changes in the phalanges and metacarpal bones to oligodactyly and phocomelia, gastroesophageal dysfunction, growth retardation, and neurodevelopmental delay. Prevalence is estimated to be as high as 1 in 10,000. Recently, mutations in NIPBL were identified in sporadic and familial CdLS cases. To date, mutations in this gene have been identified in over 45% of individuals with CdLS. NIPBL is the human homolog of the Drosophila Nipped-B gene. Although its function in mammalian systems has not yet been elucidated, sequence homologs of Nipped-B in yeast (Scc2 and Mis4) are required for sister chromatid cohesion during mitosis, and a similar role was recently demonstrated for Nipped-B in Drosophila. In order to evaluate NIPBL role in sister chromatid cohesion in humans, metaphase spreads on 90 probands (40 NIPBL mutation positive and 50 NIPBL mutation negative) with CdLS were evaluated for evidence of precocious sister chromatid separation (PSCS). We screened 50 metaphases from each proband and found evidence of PSCS in 41% (compared to 9% in control samples). These studies indicate that NIPBL may play a role in sister chromatid cohesion in humans as has been reported for its homologs in Drosophila and yeast. PMID:16100726

  4. Meiotic sister chromatid cohesion and recombination in two filamentous fungi

    NARCIS (Netherlands)

    Heemst, van D.

    2000-01-01

    Homologous recombination and sister chromatid cohesion play important roles in the maintenance of genome integrity and the fidelity of chromosome segregation in mitosis and meiosis. Within the living cell, the integrity of the DNA is threatened by various factors that cause DNA-lesions, of which DNA

  5. Is chromatin remodeling required to build sister-chromatid cohesion?

    NARCIS (Netherlands)

    Riedel, Christian G; Gregan, Juraj; Gruber, Stephan; Nasmyth, Kim

    2004-01-01

    Chromosome segregation during mitosis and meiosis depends on the linkage of sister DNA molecules after replication. These links, known as sister-chromatid cohesion, are provided by a multi-subunit complex called cohesin. Recent papers suggest that chromatin-remodeling complexes also have a role in t

  6. Repairability during G1 of the inductor leisure of exchanges in the sister chromatid induced by alkylating agents in DNA substituted and no substituted with BUDR, in cells of the salivary gland of mouse In vivo; Reparabilidad durante G1 de las lesiones inductoras de intercambios en las cromatidas hermanas inducidos por agentes alquilantes en ADN sustituido y no sustituido con BrdU, en celulas de la glandula salival de raton In vivo

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez B, F

    2004-07-01

    In this work you determines the repair of the lesions inductoras of Sister chromatid exchange (ICHs) generated in the cells of the salivary gland of mouse, for the treatment with the N-Methyl-N-Nitrosourea (MNU), the N-Ethyl-N-Nitrosourea (ENU), the Methyl methanesulfonate (MMS) and the Ethyl methanesulfonate (EMS) in early and slow G1 of the first one and the second cellular division, that is to say before and after the cells incorporate 5-bromine-2 -Desoxyuridine (BrdU) in the DNA. Groups witness non treaties were included with mutagen. The cells of the salivary gland repaired the generated lesions partially by the MNU, the MMS and the EMS in the 1st division, and only the lesions induced by the ENU and MMS were repaired partially in the 2nd division. The ENU generates injure that they were not repaired in the 1st division and those taken place by the EMS were little repaired in the 2nd division. The methylating agents generated but ICHs that the ethylating. One observes that the BrdU makes to the molecule of the DNA but susceptible to the damage generated by the alkylating agents that induce the formation of the ICHs. This susceptibility was incremented around 150% for the treatment with the MNU, the ENU and the MMS, on the other hand for the EMS it was 3 times minor. It is proposed that the one electronegative atom of this analog of the timine would to work as a nucleophyllic center with which the electrophyllic compounds react. (Author)

  7. Separation of gold, palladium and platinum in chromite by anion exchange chromatography for inductively coupled plasma atomic emission spectrometric analysis

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kwang Soon; Lee, Chang Heon; Park, Yeong Jae; Joe, Kih Soo; Kim, Won Ho [KAERI, Taejon (Korea, Republic of)

    2001-08-01

    A study has been carried out on the separation of gold, iridium, palladium, rhodium, ruthenium and platinum in chromite samples and their quantitative determination using inductively coupled plasma atomic emission spectrometry (ICP-AES). The dissolution condition of the minerals by fusion with sodium peroxide was optimized and chromatographic elution behavior of the rare metals was investigated by anion exchange chromatography. Spectral interference of chromium, a matrix of the minerals, was investigated on determination of gold. Chromium interfered on determination of gold at the concentration of 500 mg/L and higher. Gold plus trace amounts of iridium, palladium, rhodium and ruthenium, which must be preconcentrated before ICP-AES was separated by anion exchange chromatography after reducing Cr(VI) to Cr(III) by H{sub 2}O{sub 2}. AuCl{sup -}{sub 4} retained on the resin column was selectively eluted with acetone- HNO{sub 3}-H{sub 2}O as an eluent. In addition, iridium, palladium, rhodium and ruthenium remaining on the resin column were eluted as a group with concentrated HCl. However, platinum was eluted with concentrated HNO{sub 3}. The recovery yield of gold with acetone-HNO{sub 3}-H{sub 2}O was 100.7 {+-} 2.0 % , and the yields of palladium and platinum with concentrated HCl and HNO{sub 3} were 96.1 {+-} 1.8% and 96.6 {+-} 1.3%, respectively. The contents of gold and platinum in a Mongolian chromite sample were 32.6 {+-} 2.2 {mu}g/g and 1.6 {+-} 0.14 {mu}g/g, respectively. Palladium was not detected.

  8. Abnormal centromere-chromatid apposition (ACCA) and Peters' anomaly.

    Science.gov (United States)

    Wertelecki, W; Dev, V G; Superneau, D W

    1985-08-01

    Abnormal centromere-chromatid apposition (ACCA) was noted in a patient with Peters' anomaly. Previous reports of ACCA emphasized its association with tetraphocomelia and other congenital malformations (Roberts, SC Phocomelia, Pseudothalidomide Syndromes). This report expands the array of congenital malformations associated with ACCA and emphasizes the diagnostic importance of ocular defects for the ascertainment of additional cases of ACCA and its possible relationship with abnormal cell division.

  9. Cohesin SMC1 beta is required for meiotic chromosome dynamics, sister chromatid cohesion and DNA recombination

    NARCIS (Netherlands)

    Revenkova, E.; Eijpe, M.; Heyting, C.; Hodges, C.A.; Hunt, P.A.; Liebe, B.; Scherthan, H.; Jessberger, R.

    2004-01-01

    Sister chromatid cohesion ensures the faithful segregation of chromosomes in mitosis and in both meiotic divisions1, 2, 3, 4. Meiosis-specific components of the cohesin complex, including the recently described SMC1 isoform SMC15, were suggested to be required for meiotic sister chromatid cohesion a

  10. Sister chromatid tension and the spindle assembly checkpoint.

    Science.gov (United States)

    Nezi, Luigi; Musacchio, Andrea

    2009-12-01

    The spindle assembly checkpoint (SAC) is a feedback control system that monitors the state of kinetochore/microtubule attachment during mitosis and halts cell cycle progression until all chromosomes are properly aligned at the metaphase plate. The state of chromosome-microtubule attachment is implicated as a crucial factor in the checkpoint response. On the contrary, lack of tension in the centromere-kinetochore region of sister chromatids has been shown to regulate a pathway of correction of undesired chromosome-microtubule connections, while the presence of tension is believed to promote the stabilization of attachments. We discuss how tension-sensitive phenomena, such as attachment correction and stabilization, relate to the SAC and we speculate on the existence of a single pathway linking error correction and SAC activation.

  11. Sororin actively maintains sister chromatid cohesion.

    Science.gov (United States)

    Ladurner, Rene; Kreidl, Emanuel; Ivanov, Miroslav P; Ekker, Heinz; Idarraga-Amado, Maria Helena; Busslinger, Georg A; Wutz, Gordana; Cisneros, David A; Peters, Jan-Michael

    2016-03-15

    Cohesion between sister chromatids is established during DNA replication but needs to be maintained to enable proper chromosome-spindle attachments in mitosis or meiosis. Cohesion is mediated by cohesin, but also depends on cohesin acetylation and sororin. Sororin contributes to cohesion by stabilizing cohesin on DNA. Sororin achieves this by inhibiting WAPL, which otherwise releases cohesin from DNA and destroys cohesion. Here we describe mouse models which enable the controlled depletion of sororin by gene deletion or auxin-induced degradation. We show that sororin is essential for embryonic development, cohesion maintenance, and proper chromosome segregation. We further show that the acetyltransferases ESCO1 and ESCO2 are essential for stabilizing cohesin on chromatin, that their only function in this process is to acetylate cohesin's SMC3 subunit, and that DNA replication is also required for stable cohesin-chromatin interactions. Unexpectedly, we find that sororin interacts dynamically with the cohesin complexes it stabilizes. This implies that sororin recruitment to cohesin does not depend on the DNA replication machinery or process itself, but on a property that cohesin acquires during cohesion establishment.

  12. Survey of inorganic arsenic in marine animals and marine certified reference materials by anion exchange high-performance liquid chromatography-inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Sloth, Jens Jørgen; Larsen, Erik Huusfeldt; Julshamn, Kåre

    2005-01-01

    A method for the determination of inorganic arsenic in seafood samples using high-performance liquid chromatography-inductively coupled plasma mass spectrometry is described. The principle of the method relied on microwave-assisted alkaline dissolution of the sample, which at the same time oxidized...... arsenite [As(Ill)] to arsenate [As(V)], whereby inorganic arsenic could be determined as the single species As(V). Anion exchange chromatography using isocratic elution with aqueous ammonium carbonate as the mobile phase was used for the separation of As(V) from other coextracted organoarsenic compounds......, including arsenobetaine. The stability of organoarsenic compounds during the sample pretreatment was investigated, and no degradation/conversion to inorganic arsenic was detected. The method was employed for the determination of inorganic arsenic in a variety of seafood samples including fish, crustaceans...

  13. Direct analysis of ultra-trace semiconductor gas by inductively coupled plasma mass spectrometry coupled with gas to particle conversion-gas exchange technique.

    Science.gov (United States)

    Ohata, Masaki; Sakurai, Hiromu; Nishiguchi, Kohei; Utani, Keisuke; Günther, Detlef

    2015-09-01

    An inductively coupled plasma mass spectrometry (ICPMS) coupled with gas to particle conversion-gas exchange technique was applied to the direct analysis of ultra-trace semiconductor gas in ambient air. The ultra-trace semiconductor gases such as arsine (AsH3) and phosphine (PH3) were converted to particles by reaction with ozone (O3) and ammonia (NH3) gases within a gas to particle conversion device (GPD). The converted particles were directly introduced and measured by ICPMS through a gas exchange device (GED), which could penetrate the particles as well as exchange to Ar from either non-reacted gases such as an air or remaining gases of O3 and NH3. The particle size distribution of converted particles was measured by scanning mobility particle sizer (SMPS) and the results supported the elucidation of particle agglomeration between the particle converted from semiconductor gas and the particle of ammonium nitrate (NH4NO3) which was produced as major particle in GPD. Stable time-resolved signals from AsH3 and PH3 in air were obtained by GPD-GED-ICPMS with continuous gas introduction; however, the slightly larger fluctuation, which could be due to the ionization fluctuation of particles in ICP, was observed compared to that of metal carbonyl gas in Ar introduced directly into ICPMS. The linear regression lines were obtained and the limits of detection (LODs) of 1.5 pL L(-1) and 2.4 nL L(-1) for AsH3 and PH3, respectively, were estimated. Since these LODs revealed sufficiently lower values than the measurement concentrations required from semiconductor industry such as 0.5 nL L(-1) and 30 nL L(-1) for AsH3 and PH3, respectively, the GPD-GED-ICPMS could be useful for direct and high sensitive analysis of ultra-trace semiconductor gas in air.

  14. Test for Chemical Induction of Chromosome Aberrations in Cultured Chinese Hamster (CHO) Cells With and Without Metabolic Activation. Test Article. Diethylene triamine trinitrate (DETN)

    Science.gov (United States)

    2010-02-25

    chromatid interchanges between chromosomes leading to four-armed configurations. This could be asymmetrical with formation of a dicentric and an acentric...fragment which may be misaligned and a shortened monocentric chromosome , and where there is no sister chromatid union. Dicentric - an asymmetrical...Test for Chemical Induction of Chromosome Aberrations in Cultured Chinese Hamster Ovary (CHO) Cells With and Without Metabolic Activation Test

  15. Increased sister chromatid cohesion and DNA damage response factor localization at an enzyme-induced DNA double-strand break in vertebrate cells.

    LENUS (Irish Health Repository)

    Dodson, Helen

    2009-10-01

    The response to DNA damage in vertebrate cells involves successive recruitment of DNA signalling and repair factors. We used light microscopy to monitor the genetic dependencies of such localization to a single, induced DNA double strand break (DSB) in vertebrate cells. We used an inducible version of the rare-cutting I-SceI endonuclease to cut a chromosomally integrated I-SceI site beside a Tet operator array that was visualized by binding a Tet repressor-GFP fusion. Formation of gamma-H2AX foci at a single DSB was independent of ATM or Ku70. ATM-deficient cells showed normal kinetics of 53Bp1 recruitment to DSBs, but Rad51 localization was retarded. 53Bp1 and Rad51 foci formation at a single DSB was greatly reduced in H2AX-null DT40 cells. We also observed decreased inter-sister chromatid distances after DSB induction, suggesting that cohesin loading at DSBs causes elevated sister chromatid cohesion. Loss of ATM reduced DSB-induced cohesion, consistent with cohesin being an ATM target in the DSB response. These data show that the same genetic pathways control how cells respond to single DSBs and to multiple lesions induced by whole-cell DNA damage.

  16. Functional induction of the cystine-glutamate exchanger system Xc(- activity in SH-SY5Y cells by unconjugated bilirubin.

    Directory of Open Access Journals (Sweden)

    Pablo J Giraudi

    Full Text Available We have previously reported that exposure of SH-SY5Y neuroblastoma cells to unconjugated bilirubin (UCB resulted in a marked up-regulation of the mRNA encoding for the Na(+-independent cystine∶glutamate exchanger System X(c(- (SLC7A11 and SLC3A2 genes. In this study we demonstrate that SH-SY5Y cells treated with UCB showed a higher cystine uptake due to a significant and specific increase in the activity of System X(c(-, without the contribution of the others two cystine transporters (X(AG(- and GGT reported in neurons. The total intracellular glutathione content was 2 folds higher in the cells exposed to bilirubin as compared to controls, suggesting that the internalized cystine is used for gluthathione synthesis. Interestingly, these cells were significantly less sensitive to an oxidative insult induced by hydrogen peroxide. If System X(c(- is silenced the protection is lost. In conclusion, these results suggest that bilirubin can modulate the gluthathione levels in neuroblastoma cells through the induction of the System X(c(-, and this renders the cell less prone to oxidative damage.

  17. Mouse RAD54 affects DNA double-strand break repair and sister chromatid exchange

    NARCIS (Netherlands)

    H.B. Beverloo (Berna); R.D. Johnson (Roger); M. Jasin (Maria); R. Kanaar (Roland); J.H.J. Hoeijmakers (Jan); M.L.G. Dronkert (Mies)

    2000-01-01

    textabstractCells can achieve error-free repair of DNA double-strand breaks (DSBs) by homologous recombination through gene conversion with or without crossover. In contrast, an alternative homology-dependent DSB repair pathway, single-strand annealing (SSA), results in deletions. In this study, we

  18. DNA-PK-dependent RPA2 hyperphosphorylation facilitates DNA repair and suppresses sister chromatid exchange.

    Directory of Open Access Journals (Sweden)

    Hungjiun Liaw

    Full Text Available Hyperphosphorylation of RPA2 at serine 4 and serine 8 (S4, S8 has been used as a marker for activation of the DNA damage response. What types of DNA lesions cause RPA2 hyperphosphorylation, which kinase(s are responsible for them, and what is the biological outcome of these phosphorylations, however, have not been fully investigated. In this study we demonstrate that RPA2 hyperphosphorylation occurs primarily in response to genotoxic stresses that cause high levels of DNA double-strand breaks (DSBs and that the DNA-dependent protein kinase complex (DNA-PK is responsible for the modifications in vivo. Alteration of S4, S8 of RPA2 to alanines, which prevent phosphorylations at these sites, caused increased mitotic entry with concomitant increases in RAD51 foci and homologous recombination. Taken together, our results demonstrate that RPA2 hyperphosphorylation by DNA-PK in response to DSBs blocks unscheduled homologous recombination and delays mitotic entry. This pathway thus permits cells to repair DNA damage properly and increase cell viability.

  19. 40 CFR 79.65 - In vivo sister chromatid exchange assay.

    Science.gov (United States)

    2010-07-01

    ... least five female and five male animals per experimental and control group shall be used. The use of a... PROGRAMS (CONTINUED) REGISTRATION OF FUELS AND FUEL ADDITIVES Testing Requirements for Registration § 79.65... days to three or more concentrations of a test substance in air. Groups of animals are sacrificed at...

  20. Metazoan Scc4 homologs link sister chromatid cohesion to cell and axon migration guidance

    NARCIS (Netherlands)

    V.C. Seitan (Vlad); P.A. Banks (Peter); S. Laval (Steve); N.A. Majid (Nazia); D. Dorsett (Dale); A. Rana (Amer); J. Smith (Jeremy); A. Bateman (Alex); S. Krpic (Sanja); A. Hostert (Arnd); S.M. Rollins; H. Erdjument-Bromage (Hediye); P. Tempst (Paul); C.Y. Benard (Claire); S. Hekimi (Siegfried); S.F. Newbury (Sarah); T. Strachan (Tom)

    2006-01-01

    textabstractSaccharomyces cerevisiae Scc2 binds Scc4 to form an essential complex that loads cohesin onto chromosomes. The prevalence of Scc2 orthologs in eukaryotes emphasizes a conserved role in regulating sister chromatid cohesion, but homologs of Scc4 have not hitherto been identified outside ce

  1. Cell biology of cancer: BRCA1 and sister chromatid pairing reactions?

    Science.gov (United States)

    Skibbens, Robert V

    2008-02-15

    A significant portion of familial breast/ovarian cancer patients harbors a mutation in Breast Cancer Associated gene 1 (BRCA1). Cells deficient for BRCA1 exhibit chromosome aberrations such as whole chromosome duplications, translocations, inter-sister gaps and gene mis-regulation. Here, new evidence is reviewed that defects in sister chromatid cohesion may contribute directly to cancer cell phenotypes-especially those of BRCA1 mutant cells. Linking cohesion to BRCA1-dependent tumorigenesis are reports that BRCA1-associated components (DNA helicase, RFC, PCNA and genome surveillance factors) are required for efficient sister chromatid cohesion. Other cohesion factors (WAPL, EFO2/ESCO2 and hSecurin) are tightly correlated with various cell-type specific carcinogenesis, in support of a generalized model for cohesion in cancer. Recent findings further reveal that a reciprocal relationship exists in that DNA damage induces new Ctf7/Eco1-dependent sister chromatid pairing reactions that, in turn, are required for efficient DNA repair. Future research into sister chromatid pairing mechanisms are likely to provide critical new insights into the underlying causes of cancer.

  2. DNA strand exchange and RecA homologs in meiosis.

    Science.gov (United States)

    Brown, M Scott; Bishop, Douglas K

    2014-12-04

    Homology search and DNA strand-exchange reactions are central to homologous recombination in meiosis. During meiosis, these processes are regulated such that the probability of choosing a homolog chromatid as recombination partner is enhanced relative to that of choosing a sister chromatid. This regulatory process occurs as homologous chromosomes pair in preparation for assembly of the synaptonemal complex. Two strand-exchange proteins, Rad51 and Dmc1, cooperate in regulated homology search and strand exchange in most organisms. Here, we summarize studies on the properties of these two proteins and their accessory factors. In addition, we review current models for the assembly of meiotic strand-exchange complexes and the possible mechanisms through which the interhomolog bias of recombination partner choice is achieved.

  3. {beta} -carotene effect the induction of the sister chromatid exchanges (ICH) by gamma radiation in mouse radiosensibilized osseous marrow cells In vivo; Efecto del {beta}- caroteno la induccion de intercambios en las cromatidas hermanas (ICH) por radiacion gamma en celulas radiosensibilizadas de la medula osea de raton In vivo

    Energy Technology Data Exchange (ETDEWEB)

    Morales R, P.; Cruz V, V.L. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico). Dept. de Biologia

    1997-07-01

    The effect of {beta}- carotene over the ICH radioinduction in radiosensibilized with BrdU osseous marrow cells of mouse was determined In vivo. The treatment with 50 {mu}g {beta} carotene per se induces a significant increment in the ICH frequency and the pre or post-treatment with the same dose causes an additive effect in the ICH frequency produced by 0.62 Gy of gamma radiation. This implies that {beta}- carotene does not have radioprotective activity, under conditions which was developed this experiment. (Author)

  4. Premature Sister Chromatid Separation Is Poorly Detected by the Spindle Assembly Checkpoint as a Result of System-Level Feedback

    OpenAIRE

    Mihailo Mirkovic; Lukas H. Hutter; Béla Novák; Raquel A. Oliveira

    2015-01-01

    Sister chromatid cohesion, mediated by the cohesin complex, is essential for faithful mitosis. Nevertheless, evidence suggests that the surveillance mechanism that governs mitotic fidelity, the spindle assembly checkpoint (SAC), is not robust enough to halt cell division when cohesion loss occurs prematurely. The mechanism behind this poor response is not properly understood. Using developing Drosophila brains, we show that full sister chromatid separation elicits a weak checkpoint response r...

  5. Premature Sister Chromatid Separation Is Poorly Detected by the Spindle Assembly Checkpoint as a Result of System-Level Feedback

    OpenAIRE

    Mirkovic, Mihailo; Hutter, Lukas H.; Novák, Béla; Oliveira, Raquel A.

    2015-01-01

    Sister chromatid cohesion, mediated by the cohesin complex, is essential for faithful mitosis. Nevertheless, evidence suggests that the surveillance mechanism that governs mitotic fidelity, the spindle assembly checkpoint (SAC), is not robust enough to halt cell division when cohesion loss occurs prematurely. The mechanism behind this poor response is not properly understood. Using developing Drosophila brains, we show that full sister chromatid separation elicits a weak checkpoint response r...

  6. Bloom Helicase and DNA Topoisomerase IIIα Are Involved in the Dissolution of Sister Chromatids

    Science.gov (United States)

    Seki, Masayuki; Nakagawa, Takayuki; Seki, Takahiko; Kato, Genta; Tada, Shusuke; Takahashi, Yuriko; Yoshimura, Akari; Kobayashi, Takayuki; Aoki, Ayako; Otsuki, Makoto; Habermann, Felix A.; Tanabe, Hideyuki; Ishii, Yutaka; Enomoto, Takemi

    2006-01-01

    Bloom's syndrome (BS) is an autosomal disorder characterized by predisposition to a wide variety of cancers. The gene product whose mutation leads to BS is the RecQ family helicase BLM, which forms a complex with DNA topoisomerase IIIα (Top3α). However, the physiological relevance of the interaction between BLM and Top3α within the cell remains unclear. We show here that Top3α depletion causes accumulation of cells in G2 phase, enlargement of nuclei, and chromosome gaps and breaks that occur at the same position in sister chromatids. The transition from metaphase to anaphase is also inhibited. All of these phenomena except cell lethality are suppressed by BLM gene disruption. Taken together with the biochemical properties of BLM and Top3α, these data indicate that BLM and Top3α execute the dissolution of sister chromatids. PMID:16880537

  7. Hypersensitivity to G/sub 2/ chromatid radiation damage in familial dysplastic naevus syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Sanford, K.K.; Tarone, R.E.; Parshad, Ram; Tucker, M.A.; Greene, M.H.; Jones, G.M.

    1987-11-14

    Skin fibroblasts from 25 members of nine kindreds with familial dysplastic naevus syndrome (DNS), 12 apparently normal spouses, and 11 additional unrelated normal individuals were tested for G/sub 2/ cell-cycle phase sensitivity to ionising radiation. The cells from individuals with DNS or hereditary cutaneous malignant melanoma with DNS (HCMM/DNS) had significantly more chromatid breaks and gaps when entering metaphase 0.5-1.5 h after G/sub 2/ phase X-irradiation (1 Gy) than those from unaffected controls. In two cases, the test results positively identified individuals before the clinical diagnosis of DNS. A clinically normal obligate carrier of the HCMM/DNS gene showed the enhanced G/sub 2/ radiosensitivity. Moreover, in a test on 1 proband, the sensitivity was apparent in peripheral blood lymphoblasts. Enhanced G/sub 2/ chromatid radiosensitivity may be a marker of genetic susceptibility to HCMM/DNS.

  8. Opposing Functions of the N-terminal Acetyltransferases Naa50 and NatA in Sister-chromatid Cohesion.

    Science.gov (United States)

    Rong, Ziye; Ouyang, Zhuqing; Magin, Robert S; Marmorstein, Ronen; Yu, Hongtao

    2016-09-02

    During the cell cycle, sister-chromatid cohesion tethers sister chromatids together from S phase to the metaphase-anaphase transition and ensures accurate segregation of chromatids into daughter cells. N-terminal acetylation is one of the most prevalent protein covalent modifications in eukaryotes and is mediated by a family of N-terminal acetyltransferases (NAT). Naa50 (also called San) has previously been shown to play a role in sister-chromatid cohesion in metazoans. The mechanism by which Naa50 contributes to cohesion is not understood however. Here, we show that depletion of Naa50 in HeLa cells weakens the interaction between cohesin and its positive regulator sororin and causes cohesion defects in S phase, consistent with a role of Naa50 in cohesion establishment. Strikingly, co-depletion of NatA, a heterodimeric NAT complex that physically interacts with Naa50, rescues the sister-chromatid cohesion defects and the resulting mitotic arrest caused by Naa50 depletion, indicating that NatA and Naa50 play antagonistic roles in cohesion. Purified recombinant NatA and Naa50 do not affect each other's NAT activity in vitro Because NatA and Naa50 exhibit distinct substrate specificity, we propose that they modify different effectors and regulate sister-chromatid cohesion in opposing ways.

  9. Functional genomics identifies a requirement of pre-mRNA splicing factors for sister chromatid cohesion.

    Science.gov (United States)

    Sundaramoorthy, Sriramkumar; Vázquez-Novelle, María Dolores; Lekomtsev, Sergey; Howell, Michael; Petronczki, Mark

    2014-11-18

    Sister chromatid cohesion mediated by the cohesin complex is essential for chromosome segregation during cell division. Using functional genomic screening, we identify a set of 26 pre-mRNA splicing factors that are required for sister chromatid cohesion in human cells. Loss of spliceosome subunits increases the dissociation rate of cohesin from chromatin and abrogates cohesion after DNA replication, ultimately causing mitotic catastrophe. Depletion of splicing factors causes defective processing of the pre-mRNA encoding sororin, a factor required for the stable association of cohesin with chromatin, and an associated reduction of sororin protein level. Expression of an intronless version of sororin and depletion of the cohesin release protein WAPL suppress the cohesion defect in cells lacking splicing factors. We propose that spliceosome components contribute to sister chromatid cohesion and mitotic chromosome segregation through splicing of sororin pre-mRNA. Our results highlight the loss of cohesion as an early cellular consequence of compromised splicing. This may have clinical implications because SF3B1, a splicing factor that we identify to be essential for cohesion, is recurrently mutated in chronic lymphocytic leukaemia.

  10. The PP2A inhibitor I2PP2A is essential for sister chromatid segregation in oocyte meiosis II.

    Science.gov (United States)

    Chambon, Jean-Philippe; Touati, Sandra A; Berneau, Stéphane; Cladière, Damien; Hebras, Céline; Groeme, Rachel; McDougall, Alex; Wassmann, Katja

    2013-03-18

    Haploid gametes are generated through two consecutive meiotic divisions, with the segregation of chromosome pairs in meiosis I and sister chromatids in meiosis II. Separase-mediated stepwise removal of cohesion, first from chromosome arms and later from the centromere region, is a prerequisite for maintaining sister chromatids together until their separation in meiosis II [1]. In all model organisms, centromeric cohesin is protected from separase-dependent removal in meiosis I through the activity of PP2A-B56 phosphatase, which is recruited to centromeres by shugoshin/MEI-S332 (Sgo) [2-5]. How this protection of centromeric cohesin is removed in meiosis II is not entirely clear; we find that all the PP2A subunits remain colocalized with the cohesin subunit Rec8 at the centromere of metaphase II chromosomes. Here, we show that sister chromatid separation in oocytes depends on a PP2A inhibitor, namely I2PP2A. I2PP2A colocalizes with the PP2A enzyme at centromeres at metaphase II, independently of bipolar attachment. When I2PP2A is depleted, sister chromatids fail to segregate during meiosis II. Our findings demonstrate that in oocytes I2PP2A is essential for faithful sister chromatid segregation by mediating deprotection of centromeric cohesin in meiosis II. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Metazoan Scc4 homologs link sister chromatid cohesion to cell and axon migration guidance.

    Directory of Open Access Journals (Sweden)

    Vlad C Seitan

    2006-07-01

    Full Text Available Saccharomyces cerevisiae Scc2 binds Scc4 to form an essential complex that loads cohesin onto chromosomes. The prevalence of Scc2 orthologs in eukaryotes emphasizes a conserved role in regulating sister chromatid cohesion, but homologs of Scc4 have not hitherto been identified outside certain fungi. Some metazoan orthologs of Scc2 were initially identified as developmental gene regulators, such as Drosophila Nipped-B, a regulator of cut and Ultrabithorax, and delangin, a protein mutant in Cornelia de Lange syndrome. We show that delangin and Nipped-B bind previously unstudied human and fly orthologs of Caenorhabditis elegans MAU-2, a non-axis-specific guidance factor for migrating cells and axons. PSI-BLAST shows that Scc4 is evolutionarily related to metazoan MAU-2 sequences, with the greatest homology evident in a short N-terminal domain, and protein-protein interaction studies map the site of interaction between delangin and human MAU-2 to the N-terminal regions of both proteins. Short interfering RNA knockdown of human MAU-2 in HeLa cells resulted in precocious sister chromatid separation and in impaired loading of cohesin onto chromatin, indicating that it is functionally related to Scc4, and RNAi analyses show that MAU-2 regulates chromosome segregation in C. elegans embryos. Using antisense morpholino oligonucleotides to knock down Xenopus tropicalis delangin or MAU-2 in early embryos produced similar patterns of retarded growth and developmental defects. Our data show that sister chromatid cohesion in metazoans involves the formation of a complex similar to the Scc2-Scc4 interaction in the budding yeast. The very high degree of sequence conservation between Scc4 homologs in complex metazoans is consistent with increased selection pressure to conserve additional essential functions, such as regulation of cell and axon migration during development.

  12. Rfc5p regulates alternate RFC complex functions in sister chromatid pairing reactions in budding yeast

    OpenAIRE

    Maradeo, Marie E.; Garg, Anisha; Skibbens, Robert V.

    2010-01-01

    Sister chromatid pairing reactions, termed cohesion establishment, occur during S phase and appear to be regulated by replication factor C (RFC) complexes. For instance, RFCs that contain Ctf18p exhibit pro-establishment activities while those that contain Elg1p exhibit anti-establishment activities. It remains unknown whether Ctf18p-RFC and Elg1p-RFC functions are simply opposing or instead reveal complicated and non-parallel regulatory mechanisms. To better understand the nature of these no...

  13. Cyclin A2 Is Required for Sister Chromatid Segregation, But Not Separase Control, in Mouse Oocyte Meiosis

    Directory of Open Access Journals (Sweden)

    Sandra A. Touati

    2012-11-01

    Full Text Available In meiosis, two specialized cell divisions allow the separation of paired chromosomes first, then of sister chromatids. Separase removes the cohesin complex holding sister chromatids together in a stepwise manner from chromosome arms in meiosis I, then from the centromere region in meiosis II. Using mouse oocytes, our study reveals that cyclin A2 promotes entry into meiosis, as well as an additional unexpected role; namely, its requirement for separase-dependent sister chromatid separation in meiosis II. Untimely cyclin A2-associated kinase activity in meiosis I leads to precocious sister separation, whereas inhibition of cyclin A2 in meiosis II prevents it. Accordingly, endogenous cyclin A is localized to kinetochores throughout meiosis II, but not in anaphase I. Additionally, we found that cyclin B1, but not cyclin A2, inhibits separase in meiosis I. These findings indicate that separase-dependent cohesin removal is differentially regulated by cyclin B1 and A2 in mammalian meiosis.

  14. Cyclin A2 is required for sister chromatid segregation, but not separase control, in mouse oocyte meiosis.

    Science.gov (United States)

    Touati, Sandra A; Cladière, Damien; Lister, Lisa M; Leontiou, Ioanna; Chambon, Jean-Philippe; Rattani, Ahmed; Böttger, Franziska; Stemmann, Olaf; Nasmyth, Kim; Herbert, Mary; Wassmann, Katja

    2012-11-29

    In meiosis, two specialized cell divisions allow the separation of paired chromosomes first, then of sister chromatids. Separase removes the cohesin complex holding sister chromatids together in a stepwise manner from chromosome arms in meiosis I, then from the centromere region in meiosis II. Using mouse oocytes, our study reveals that cyclin A2 promotes entry into meiosis, as well as an additional unexpected role; namely, its requirement for separase-dependent sister chromatid separation in meiosis II. Untimely cyclin A2-associated kinase activity in meiosis I leads to precocious sister separation, whereas inhibition of cyclin A2 in meiosis II prevents it. Accordingly, endogenous cyclin A is localized to kinetochores throughout meiosis II, but not in anaphase I. Additionally, we found that cyclin B1, but not cyclin A2, inhibits separase in meiosis I. These findings indicate that separase-dependent cohesin removal is differentially regulated by cyclin B1 and A2 in mammalian meiosis.

  15. Test for Chemical Induction of Chromosome Aberrations in Cultured Chinese Hamster Ovary (CHO) Cells with and without Metabolic Activation, Test Article: 3-Nitro-1,2,4-Triazol-5-one (NTO)

    Science.gov (United States)

    2008-10-30

    3110 Dicentric - an asymmetrical exchange between two chromosomes resulting in a chromosome with two centromeres with or without an accompanying...chromatid union. Dicentric - an asymmetrical exchange between two chromosomes resulting in a chromosome with two centromeres with or without an...Test for Chemical fuduction of Chromosome Aberrations in Cultured Chinese Hamster Ovary (CHO) Cells With and Without Metabolic Activation Test

  16. UBL5 is essential for pre-mRNA splicing and sister chromatid cohesion in human cells

    DEFF Research Database (Denmark)

    Oka, Yasuyoshi; Varmark, Hanne; Vitting-Seerup, Kristoffer;

    2014-01-01

    UBL5 is an atypical ubiquitin-like protein, whose function in metazoans remains largely unexplored. We show that UBL5 is required for sister chromatid cohesion maintenance in human cells. UBL5 primarily associates with spliceosomal proteins, and UBL5 depletion decreases pre-mRNA splicing efficiency......, leading to globally enhanced intron retention. Defective sister chromatid cohesion is a general consequence of dysfunctional pre-mRNA splicing, resulting from the selective downregulation of the cohesion protection factor Sororin. As the UBL5 yeast orthologue, Hub1, also promotes spliceosome functions...

  17. Rapid isolation of plutonium in environmental solid samples using sequential injection anion exchange chromatography followed by detection with inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Qiao Jixin, E-mail: jixin.qiao@risoe.d [Radiation Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Hou Xiaolin; Roos, Per [Radiation Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Miro, Manuel [Department of Chemistry, Faculty of Sciences, University of the Balearic Islands, Carretera de Valldemossa km. 7.5, E-07122 Palma de Mallorca, Illes Balears (Spain)

    2011-01-31

    This paper reports an automated analytical method for rapid determination of plutonium isotopes ({sup 239}Pu and {sup 240}Pu) in environmental solid extracts. Anion exchange chromatographic columns were incorporated in a sequential injection (SI) system to undertake the automated separation of plutonium from matrix and interfering elements. The analytical results most distinctly demonstrated that the crosslinkage of the anion exchanger is a key parameter controlling the separation efficiency. AG 1-x4 type resin was selected as the most suitable sorbent material for analyte separation. Investigation of column size effect upon the separation efficiency revealed that small-sized (2 mL) columns sufficed to handle up to 50 g of environmental soil samples. Under the optimum conditions, chemical yields of plutonium exceeded 90% and the decontamination factors for uranium, thorium and lead ranged from 10{sup 3} to 10{sup 4}. The determination of plutonium isotopes in three standard/certified reference materials (IAEA-375 soil, IAEA-135 sediment and NIST-4359 seaweed) and two reference samples (Irish Sea sediment and Danish soil) revealed a good agreement with reference/certified values. The SI column-separation method is straightforward and less labor intensive as compared with batch-wise anion exchange chromatographic procedures. Besides, the automated method features low consumption of ion-exchanger and reagents for column washing and elution, with the consequent decrease in the generation of acidic waste, thus bearing green chemical credentials.

  18. Rapid isolation of plutonium in environmental solid samples using sequential injection anion exchange chromatography followed by detection with inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Qiao, Jixin; Hou, Xiaolin; Roos, Per; Miró, Manuel

    2011-01-31

    This paper reports an automated analytical method for rapid determination of plutonium isotopes ((239)Pu and (240)Pu) in environmental solid extracts. Anion exchange chromatographic columns were incorporated in a sequential injection (SI) system to undertake the automated separation of plutonium from matrix and interfering elements. The analytical results most distinctly demonstrated that the crosslinkage of the anion exchanger is a key parameter controlling the separation efficiency. AG 1-×4 type resin was selected as the most suitable sorbent material for analyte separation. Investigation of column size effect upon the separation efficiency revealed that small-sized (2 mL) columns sufficed to handle up to 50 g of environmental soil samples. Under the optimum conditions, chemical yields of plutonium exceeded 90% and the decontamination factors for uranium, thorium and lead ranged from 10(3) to 10(4). The determination of plutonium isotopes in three standard/certified reference materials (IAEA-375 soil, IAEA-135 sediment and NIST-4359 seaweed) and two reference samples (Irish Sea sediment and Danish soil) revealed a good agreement with reference/certified values. The SI column-separation method is straightforward and less labor intensive as compared with batch-wise anion exchange chromatographic procedures. Besides, the automated method features low consumption of ion-exchanger and reagents for column washing and elution, with the consequent decrease in the generation of acidic waste, thus bearing green chemical credentials.

  19. The ELG1 clamp loader plays a role in sister chromatid cohesion.

    Directory of Open Access Journals (Sweden)

    Oren Parnas

    Full Text Available Mutations in the ELG1 gene of yeast lead to genomic instability, manifested in high levels of genetic recombination, chromosome loss, and gross chromosomal rearrangements. Elg1 shows similarity to the large subunit of the Replication Factor C clamp loader, and forms a RFC-like (RLC complex in conjunction with the 4 small RFC subunits. Two additional RLCs exist in yeast: in one of them the large subunit is Ctf18, and in the other, Rad24. Ctf18 has been characterized as the RLC that functions in sister chromatid cohesion. Here we present evidence that the Elg1 RLC (but not Rad24 also plays an important role in this process. A genetic screen identified the cohesin subunit Mcd1/Scc1 and its loader Scc2 as suppressors of the synthetic lethality between elg1 and ctf4. We describe genetic interactions between ELG1 and genes encoding cohesin subunits and their accessory proteins. We also show that defects in Elg1 lead to higher precocious sister chromatid separation, and that Ctf18 and Elg1 affect cohesion via a joint pathway. Finally, we localize both Ctf18 and Elg1 to chromatin and show that Elg1 plays a role in the recruitment of Ctf18. Our results suggest that Elg1, Ctf4, and Ctf18 may coordinate the relative movement of the replication fork with respect to the cohesin ring.

  20. Chromatids segregate without centrosomes during Caenorhabditis elegans mitosis in a Ran- and CLASP-dependent manner.

    Science.gov (United States)

    Nahaboo, Wallis; Zouak, Melissa; Askjaer, Peter; Delattre, Marie

    2015-06-01

    During mitosis, chromosomes are connected to a microtubule-based spindle. Current models propose that displacement of the spindle poles and/or the activity of kinetochore microtubules generate mechanical forces that segregate sister chromatids. Using laser destruction of the centrosomes during Caenorhabditis elegans mitosis, we show that neither of these mechanisms is necessary to achieve proper chromatid segregation. Our results strongly suggest that an outward force generated by the spindle midzone, independently of centrosomes, is sufficient to segregate chromosomes in mitotic cells. Using mutant and RNAi analysis, we show that the microtubule-bundling protein SPD-1/MAP-65 and BMK-1/kinesin-5 act as a brake opposing the force generated by the spindle midzone. Conversely, we identify a novel role for two microtubule-growth and nucleation agents, Ran and CLASP, in the establishment of the centrosome-independent force during anaphase. Their involvement raises the interesting possibility that microtubule polymerization of midzone microtubules is continuously required to sustain chromosome segregation during mitosis.

  1. High-throughput sequential injection method for simultaneous determination of plutonium and neptunium in environmental solids using macroporous anion-exchange chromatography, followed by inductively coupled plasma mass spectrometric detection.

    Science.gov (United States)

    Qiao, Jixin; Hou, Xiaolin; Roos, Per; Miró, Manuel

    2011-01-01

    This paper reports an automated analytical method for rapid and simultaneous determination of plutonium and neptunium in soil, sediment, and seaweed, with detection via inductively coupled plasma mass spectrometry (ICP-MS). A chromatographic column packed with a macroporous anion exchanger (AG MP-1 M) was incorporated in a sequential injection (SI) system for the efficient retrieval of plutonium, along with neptunium, from matrix elements and potential interfering nuclides. The sorption and elution behavior of plutonium and neptunium onto AG MP-1 M resin was compared with a commonly utilized AG 1-gel-type anion exchanger. Experimental results reveal that the pore structure of the anion exchanger plays a pivotal role in ensuring similar separation behavior of plutonium and neptunium along the separation protocol. It is proven that plutonium-242 ((242)Pu) performs well as a tracer for monitoring the chemical yield of neptunium when using AG MP-1 M resin, whereby the difficulties in obtaining a reliable and practicable isotopic neptunium tracer are overcome. An important asset of the SI setup is the feasibility of processing up to 100 g of solid substrates using a small-sized (ca. 2 mL) column with chemical yields of neptunium and plutonium being ≥79%. Analytical results of three certified/standard reference materials and two solid samples from intercomparison exercises are in good agreement with the reference values at the 0.05 significance level. The overall on-column separation can be completed within 3.5 h for 10 g of soil samples. Most importantly, the anion-exchange mini-column suffices to be reused up to 10-fold with satisfactory chemical yields (>70%), as demanded in environmental monitoring and emergency scenarios, making the proposed automated assembly well-suited for unattended and high-throughput analysis.

  2. Regulation of the Drosophila Enhancer of split and invected-engrailed Gene Complexes by Sister Chromatid Cohesion Proteins

    NARCIS (Netherlands)

    Schaaf, Cheri A.; Misulovin, Ziva; Sahota, Gurmukh; Siddiqui, Akbar M.; Schwartz, Yuri B.; Kahn, Tatyana G.; Pirrotta, Vincenzo; Gause, Maria; Dorsett, Dale

    2009-01-01

    The cohesin protein complex was first recognized for holding sister chromatids together and ensuring proper chromosome segregation. Cohesin also regulates gene expression, but the mechanisms are unknown. Cohesin associates preferentially with active genes, and is generally absent from regions in whi

  3. Phospho-H1 Decorates the Inter-chromatid Axis and Is Evicted along with Shugoshin by SET during Mitosis.

    Science.gov (United States)

    Krishnan, Swathi; Smits, Arne H; Vermeulen, Michiel; Reinberg, Danny

    2017-08-17

    Precise control of sister chromatid separation during mitosis is pivotal to maintaining genomic integrity. Yet, the regulatory mechanisms involved are not well understood. Remarkably, we discovered that linker histone H1 phosphorylated at S/T18 decorated the inter-chromatid axial DNA on mitotic chromosomes. Sister chromatid resolution during mitosis required the eviction of such H1S/T18ph by the chaperone SET, with this process being independent of and most likely downstream of arm-cohesin dissociation. SET also directed the disassembly of Shugoshins in a polo-like kinase 1-augmented manner, aiding centromere resolution. SET ablation compromised mitotic fidelity as evidenced by unresolved sister chromatids with marked accumulation of H1S/T18ph and centromeric Shugoshin. Thus, chaperone-assisted eviction of linker histones and Shugoshins is a fundamental step in mammalian mitotic progression. Our findings also elucidate the functional implications of the decades-old observation of mitotic linker histone phosphorylation, serving as a paradigm to explore the role of linker histones in bio-signaling processes. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. PICH promotes sister chromatid disjunction and co-operates with topoisomerase II in mitosis.

    Science.gov (United States)

    Nielsen, Christian F; Huttner, Diana; Bizard, Anna H; Hirano, Seiki; Li, Tian-Neng; Palmai-Pallag, Timea; Bjerregaard, Victoria A; Liu, Ying; Nigg, Erich A; Wang, Lily Hui-Ching; Hickson, Ian D

    2015-01-01

    PICH is a SNF2 family DNA translocase that binds to ultra-fine DNA bridges (UFBs) in mitosis. Numerous roles for PICH have been proposed from protein depletion experiments, but a consensus has failed to emerge. Here, we report that deletion of PICH in avian cells causes chromosome structural abnormalities, and hypersensitivity to an inhibitor of Topoisomerase II (Topo II), ICRF-193. ICRF-193-treated PICH(-/-) cells undergo sister chromatid non-disjunction in anaphase, and frequently abort cytokinesis. PICH co-localizes with Topo IIα on UFBs and at the ribosomal DNA locus, and the timely resolution of both structures depends on the ATPase activity of PICH. Purified PICH protein strongly stimulates the catalytic activity of Topo II in vitro. Consistent with this, a human PICH(-/-) cell line exhibits chromosome instability and chromosome condensation and decatenation defects similar to those of ICRF-193-treated cells. We propose that PICH and Topo II cooperate to prevent chromosome missegregation events in mitosis.

  5. Sororin pre-mRNA splicing is required for proper sister chromatid cohesion in human cells.

    Science.gov (United States)

    Watrin, Erwan; Demidova, Maria; Watrin, Tanguy; Hu, Zheng; Prigent, Claude

    2014-09-01

    Sister chromatid cohesion, which depends on cohesin, is essential for the faithful segregation of replicated chromosomes. Here, we report that splicing complex Prp19 is essential for cohesion in both G2 and mitosis, and consequently for the proper progression of the cell through mitosis. Inactivation of splicing factors SF3a120 and U2AF65 induces similar cohesion defects to Prp19 complex inactivation. Our data indicate that these splicing factors are all required for the accumulation of cohesion factor Sororin, by facilitating the proper splicing of its pre-mRNA. Finally, we show that ectopic expression of Sororin corrects defective cohesion caused by Prp19 complex inactivation. We propose that the Prp19 complex and the splicing machinery contribute to the establishment of cohesion by promoting Sororin accumulation during S phase, and are, therefore, essential to the maintenance of genome stability.

  6. The Elg1-RFC clamp-loading complex performs a role in sister chromatid cohesion.

    Science.gov (United States)

    Maradeo, Marie E; Skibbens, Robert V

    2009-01-01

    It is widely accepted that of the four Replication Factor C (RFC) complexes (defined by the associations of either Rfc1p, Ctf18p, Elg1p or Rad24p with Rfc2p-Rfc5p), only Ctf18-RFC functions in sister chromatid cohesion. This model is based on findings that CTF18 deletion is lethal in combination with mutations in either CTF7(ECO1) or MCD1 sister chromatid cohesion genes and that ctf18 mutant cells exhibit cohesion defects. Here, we report that Elg1-RFC not only participates in cohesion but performs a function that is distinct from that of Ctf18-RFC. The results show that deletion of ELG1 rescues both ctf7(eco1) mutant cell temperature sensitivity and cohesion defects. Moreover, over-expression of ELG1 enhances ctf7(eco1) mutant cell phenotypes. These findings suggest that the balance of Ctf7p(Eco1p) activity depends on both Ctf18-RFC and Elg1-RFC. We also report that ELG1 deletion produces cohesion defects and intensifies the conditional phenotype of mcd1 mutant cells, further supporting a role for Elg1-RFC in cohesion. Attesting to the specificity of these interactions, deletion of RAD24 neither suppressed nor exacerbated cohesion defects in either ctf7(eco1) or mcd1 mutant cells. While parallel analyses failed to uncover a similar role in cohesion for Rad24-RFC, it is well known that Rad24-RFC, Elg1-RFC and Ctf18-RFC play key roles in DNA damage responses. We tested and found that Ctf7p(Eco1p) plays a significant role in Rad24-RFC-based DNA response pathways. In combination, these findings challenge current views and document new and distinct roles for RFC complexes in cohesion and for Ctf7p(Eco1p) in DNA repair.

  7. The Elg1-RFC clamp-loading complex performs a role in sister chromatid cohesion.

    Directory of Open Access Journals (Sweden)

    Marie E Maradeo

    Full Text Available It is widely accepted that of the four Replication Factor C (RFC complexes (defined by the associations of either Rfc1p, Ctf18p, Elg1p or Rad24p with Rfc2p-Rfc5p, only Ctf18-RFC functions in sister chromatid cohesion. This model is based on findings that CTF18 deletion is lethal in combination with mutations in either CTF7(ECO1 or MCD1 sister chromatid cohesion genes and that ctf18 mutant cells exhibit cohesion defects. Here, we report that Elg1-RFC not only participates in cohesion but performs a function that is distinct from that of Ctf18-RFC. The results show that deletion of ELG1 rescues both ctf7(eco1 mutant cell temperature sensitivity and cohesion defects. Moreover, over-expression of ELG1 enhances ctf7(eco1 mutant cell phenotypes. These findings suggest that the balance of Ctf7p(Eco1p activity depends on both Ctf18-RFC and Elg1-RFC. We also report that ELG1 deletion produces cohesion defects and intensifies the conditional phenotype of mcd1 mutant cells, further supporting a role for Elg1-RFC in cohesion. Attesting to the specificity of these interactions, deletion of RAD24 neither suppressed nor exacerbated cohesion defects in either ctf7(eco1 or mcd1 mutant cells. While parallel analyses failed to uncover a similar role in cohesion for Rad24-RFC, it is well known that Rad24-RFC, Elg1-RFC and Ctf18-RFC play key roles in DNA damage responses. We tested and found that Ctf7p(Eco1p plays a significant role in Rad24-RFC-based DNA response pathways. In combination, these findings challenge current views and document new and distinct roles for RFC complexes in cohesion and for Ctf7p(Eco1p in DNA repair.

  8. A study of sister chromatid exchange and somatic cell mutation in hospital workers exposed to ethylene oxide.

    OpenAIRE

    Tomkins, D J; T. Haines; Lawrence, M.; Rosa, N

    1993-01-01

    To investigate the risks of exposure to ethylene oxide (EO) at current permissible levels and at past higher levels, an inception cohort of sterilizer operators and supervisors from the Central Processing Department (CPD), respiratory therapists, and engineers exposed to EO were identified at the McMaster University Medical Centre. A comparison group from Nutrition Services (NUTR) were matched with the CPD workers on the basis of sex, age, and smoking habit. The present report is based on gen...

  9. A study of sister chromatid exchange and somatic cell mutation in hospital workers exposed to ethylene oxide.

    Science.gov (United States)

    Tomkins, D J; Haines, T; Lawrence, M; Rosa, N

    1993-10-01

    To investigate the risks of exposure to ethylene oxide (EO) at current permissible levels and at past higher levels, an inception cohort of sterilizer operators and supervisors from the Central Processing Department (CPD), respiratory therapists, and engineers exposed to EO were identified at the McMaster University Medical Centre. A comparison group from Nutrition Services (NUTR) were matched with the CPD workers on the basis of sex, age, and smoking habit. The present report is based on genetic test results for the 94 CPD and matched NUTR workers only. Statistical analysis based on the mean SCE frequency in the top 5, top 10, and all cells (50 cells scored per individual) and high frequency cells (HFC) based on the 95th percentile for nonsmoking control subjects showed a direct association with current smoking but not with EO exposure. Similarly, statistical analysis of the somatic cell mutation (SCMT) variant frequencies did not demonstrate an association with EO exposure, nor with smoking. Regression analysis indicated that sex was the only other covariate that significantly affected SCE. Age was weakly associated with SCMT. A statistically significant interaction between occupational exposure and smoking habits was observed only for the mean SCE frequency of the top 5 and top 10 cells when the 11 current CPD/NUTR pairs were not included. Thus, this interaction should be interpreted with caution.

  10. Parallel increases in sister chromatid exchanges at base level and with UV treatment in human opiate users

    Energy Technology Data Exchange (ETDEWEB)

    Shafer, D.A.; Falek, A.; Madden, J.J.; Tadayon, F.; Pline, M. (Georgia Mental Health Inst., Atlanta (USA). Human Genetics Research Lab.; Emory Univ., Atlanta, GA (USA). Dept. of Psychiatry); Bokos, P.J. (Interventions, Chicago, IL (USA)); Kuehnle, J.C.; Mendelson, J. (McLean Hospital, Belmont, MA (USA). Alcohol and Drug Abuse Research Center)

    1983-04-01

    The SCE base level frequency and SCE levels induced by far-UV (254 nm) treatment of cells in early G/sub 1/ and early S phases of the cell cycle were significantly higher in leukocytes from heroin addicts as compared to controls. The increased SCE levels in addicts was greatest at base level and smallest after UV irradiation of cells in S phase. These results corrobate and extend our previous findings of increased chromosome damage and reduced DNA-repair synthesis in heroin users. Since opiates do not directly damage DNA, the elevated cytogenetic effects associated with opiate use probably arise from secondary promotional effects related to opiate-mediated alterations in leukocyte metabolism.

  11. Onderzoek naar de inductie van chromosoomafwijkingen en "sister- chromatid exchanges" door acrylamide met Chinese hamster cellen in vitro

    NARCIS (Netherlands)

    Knaap; A.G.A.C.; Bergkamp; W.G.M.; Groot; M.G.

    1986-01-01

    Acrylamide bleek een clastogene werking te hebben in een test op chromosoomafwijkingen met Chinese hamster cellen in vitro vanaf 0,1 mg/ml (1,4 mmol/l), zowel in aan- als afwezigheid van een systeem voor metaboliosche activering (S9). Tevens induceerde acrylamide in deze cellen een significante

  12. Identification of RFC(Ctf18p, Ctf8p, Dcc1p): an alternative RFC complex required for sister chromatid cohesion in S. cerevisiae.

    Science.gov (United States)

    Mayer, M L; Gygi, S P; Aebersold, R; Hieter, P

    2001-05-01

    We have identified and characterized an alternative RFC complex RFC(Ctf18p, Ctf8p, Dcc1p) that is required for sister chromatid cohesion and faithful chromosome transmission. Ctf18p, Ctf8p, and Dcc1p interact physically in a complex with Rfc2p, Rfc3p, Rfc4p, and Rfc5p but not with Rfc1p or Rad24p. Deletion of CTF18, CTF8, or DCC1 singly or in combination (ctf18Deltactf8Deltadcc1Delta) leads to sensitivity to microtubule depolymerizing drugs and a severe sister chromatid cohesion defect. Furthermore, temperature-sensitive mutations in RFC4 result in precocious sister chromatid separation. Our results highlight a novel function of the RFC proteins and support a model in which sister chromatid cohesion is established at the replication fork via a polymerase switching mechanism and a replication-coupled remodeling of chromatin.

  13. Smc5–Smc6 mediate DNA double-strand-break repair by promoting sister-chromatid recombination

    Science.gov (United States)

    De Piccoli, Giacomo; Cortes-Ledesma, Felipe; Ira, Gregory; Torres-Rosell, Jordi; Uhle, Stefan; Farmer, Sarah; Hwang, Ji-Young; Machin, Felix; Ceschia, Audrey; McAleenan, Alexandra; Cordon-Preciado, Violeta; Clemente-Blanco, Andrés; Vilella-Mitjana, Felip; Ullal, Pranav; Jarmuz, Adam; Leitao, Beatriz; Bressan, Debra; Dotiwala, Farokh; Papusha, Alma; Zhao, Xiaolan; Myung, Kyungjae; Haber, James E.; Aguilera, Andrés; Aragón, Luis

    2015-01-01

    DNA double-strand breaks (DSB) can arise during DNA replication, or after exposure to DNA-damaging agents, and their correct repair is fundamental for cell survival and genomic stability. Here, we show that the Smc5–Smc6 complex is recruited to DSBs de novo to support their repair by homologous recombination between sister chromatids. In addition, we demonstrate that Smc5–Smc6 is necessary to suppress gross chromosomal rearrangements. Our findings show that the Smc5–Smc6 complex is essential for genome stability as it promotes repair of DSBs by error-free sister-chromatid recombination (SCR), thereby suppressing inappropriate non-sister recombination events. PMID:16892052

  14. Premature Sister Chromatid Separation Is Poorly Detected by the Spindle Assembly Checkpoint as a Result of System-Level Feedback

    Directory of Open Access Journals (Sweden)

    Mihailo Mirkovic

    2015-10-01

    Full Text Available Sister chromatid cohesion, mediated by the cohesin complex, is essential for faithful mitosis. Nevertheless, evidence suggests that the surveillance mechanism that governs mitotic fidelity, the spindle assembly checkpoint (SAC, is not robust enough to halt cell division when cohesion loss occurs prematurely. The mechanism behind this poor response is not properly understood. Using developing Drosophila brains, we show that full sister chromatid separation elicits a weak checkpoint response resulting in abnormal mitotic exit after a short delay. Quantitative live-cell imaging approaches combined with mathematical modeling indicate that weak SAC activation upon cohesion loss is caused by weak signal generation. This is further attenuated by several feedback loops in the mitotic signaling network. We propose that multiple feedback loops involving cyclin-dependent kinase 1 (Cdk1 gradually impair error-correction efficiency and accelerate mitotic exit upon premature loss of cohesion. Our findings explain how cohesion defects may escape SAC surveillance.

  15. Cis-acting determinants affecting centromere function, sister-chromatid cohesion and reciprocal recombination during meiosis in Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Sears, D.D.; Hieter, P. [Johns Hopkins Univ. School of Medicine, Baltimore, MD (United States); Shero, J.H. [Johns Hopkins Univ. School of Medicine, Baltimore, MD (United States)]|[Baylor College of Medicine, Houston, TX (United States); Hegemann, J.H. [Justus Liebig Universitaet, Giessen (Germany)

    1995-03-01

    We have employed a system that utilizes homologous pairs of human DNA-derived yeast artificial chromosomes (YACs) as marker chromosomes to assess the specific role(s) of conserved centromere DNA elements (CDEI, CDEII, and CDEIII) in meiotic chromosome disjunction fidelity. Thirteen different centromere (CEN) mutations were tested for their effects on meiotic centromere function. YACs containing a wild-type CEN DNA sequence segregate with high fidelity in meiosis I (99% normal segregation) and in meiosis II (96% normal segregation). YACs containing a 31-bp deletion mutation in centromere DNA element II (CDEII{Delta}31) in either a heterocentric (mutant/wild type), homocentric (mutant/mutant) or monosomic (mutant/-) YAC pair configuration exhibited high levels (16-28%) of precocious sister-chromatid segregation (PSS) and increased levels (1-6%) of nondisjunction meiosis I (NDI). YACs containing this mutation also exhibit high levels (21%) of meiosis II nondisjunction. Interestingly, significant alterations in homolog recombination frequency were observed in the exceptional PSS class of tetrads, suggesting unusual interactions between prematurely separated sister chromatids and their homologous nonsister chromatids. We also have assessed the meiotic segregation effects of rare gene conversion events occurring at sites located immediately adjacent to or distantly from the centromere region. Proximal gene conversion events were associated with extremely high levels (60%) of meiosis I segregation errors (including both PSS and NDI), whereas distal events had no apparent effect. Taken together, our results indicate a critical role for CDEII in meiosis and underscore the importance of maintaining sister-chromatid cohesion for proper recombination in meiotic prophase and for proper disjunction in meiosis I. 49 refs., 4 figs., 5 tabs.

  16. Variations in dysfunction of sister chromatid cohesion in esco2 mutant zebrafish reflect the phenotypic diversity of Roberts syndrome

    Directory of Open Access Journals (Sweden)

    Stefanie M. Percival

    2015-08-01

    Full Text Available Mutations in ESCO2, one of two establishment of cohesion factors necessary for proper sister chromatid cohesion (SCC, cause a spectrum of developmental defects in the autosomal-recessive disorder Roberts syndrome (RBS, warranting in vivo analysis of the consequence of cohesion dysfunction. Through a genetic screen in zebrafish targeting embryonic-lethal mutants that have increased genomic instability, we have identified an esco2 mutant zebrafish. Utilizing the natural transparency of zebrafish embryos, we have developed a novel technique to observe chromosome dynamics within a single cell during mitosis in a live vertebrate embryo. Within esco2 mutant embryos, we observed premature chromatid separation, a unique chromosome scattering, prolonged mitotic delay, and genomic instability in the form of anaphase bridges and micronuclei formation. Cytogenetic studies indicated complete chromatid separation and high levels of aneuploidy within mutant embryos. Amongst aneuploid spreads, we predominantly observed decreases in chromosome number, suggesting that either cells with micronuclei or micronuclei themselves are eliminated. We also demonstrated that the genomic instability leads to p53-dependent neural tube apoptosis. Surprisingly, although many cells required Esco2 to establish cohesion, 10-20% of cells had only weakened cohesion in the absence of Esco2, suggesting that compensatory cohesion mechanisms exist in these cells that undergo a normal mitotic division. These studies provide a unique in vivo vertebrate view of the mitotic defects and consequences of cohesion establishment loss, and they provide a compensation-based model to explain the RBS phenotypes.

  17. RSC facilitates Rad59-dependent homologous recombination between sister chromatids by promoting cohesin loading at DNA double-strand breaks.

    Science.gov (United States)

    Oum, Ji-Hyun; Seong, Changhyun; Kwon, Youngho; Ji, Jae-Hoon; Sid, Amy; Ramakrishnan, Sreejith; Ira, Grzegorz; Malkova, Anna; Sung, Patrick; Lee, Sang Eun; Shim, Eun Yong

    2011-10-01

    Homologous recombination repairs DNA double-strand breaks by searching for, invading, and copying information from a homologous template, typically the homologous chromosome or sister chromatid. Tight wrapping of DNA around histone octamers, however, impedes access of repair proteins to DNA damage. To facilitate DNA repair, modifications of histones and energy-dependent remodeling of chromatin are required, but the precise mechanisms by which chromatin modification and remodeling enzymes contribute to homologous DNA repair are unknown. Here we have systematically assessed the role of budding yeast RSC (remodel structure of chromatin), an abundant, ATP-dependent chromatin-remodeling complex, in the cellular response to spontaneous and induced DNA damage. RSC physically interacts with the recombination protein Rad59 and functions in homologous recombination. Multiple recombination assays revealed that RSC is uniquely required for recombination between sister chromatids by virtue of its ability to recruit cohesin at DNA breaks and thereby promoting sister chromatid cohesion. This study provides molecular insights into how chromatin remodeling contributes to DNA repair and maintenance of chromatin fidelity in the face of DNA damage.

  18. Variations in dysfunction of sister chromatid cohesion in esco2 mutant zebrafish reflect the phenotypic diversity of Roberts syndrome.

    Science.gov (United States)

    Percival, Stefanie M; Thomas, Holly R; Amsterdam, Adam; Carroll, Andrew J; Lees, Jacqueline A; Yost, H Joseph; Parant, John M

    2015-08-01

    Mutations in ESCO2, one of two establishment of cohesion factors necessary for proper sister chromatid cohesion (SCC), cause a spectrum of developmental defects in the autosomal-recessive disorder Roberts syndrome (RBS), warranting in vivo analysis of the consequence of cohesion dysfunction. Through a genetic screen in zebrafish targeting embryonic-lethal mutants that have increased genomic instability, we have identified an esco2 mutant zebrafish. Utilizing the natural transparency of zebrafish embryos, we have developed a novel technique to observe chromosome dynamics within a single cell during mitosis in a live vertebrate embryo. Within esco2 mutant embryos, we observed premature chromatid separation, a unique chromosome scattering, prolonged mitotic delay, and genomic instability in the form of anaphase bridges and micronuclei formation. Cytogenetic studies indicated complete chromatid separation and high levels of aneuploidy within mutant embryos. Amongst aneuploid spreads, we predominantly observed decreases in chromosome number, suggesting that either cells with micronuclei or micronuclei themselves are eliminated. We also demonstrated that the genomic instability leads to p53-dependent neural tube apoptosis. Surprisingly, although many cells required Esco2 to establish cohesion, 10-20% of cells had only weakened cohesion in the absence of Esco2, suggesting that compensatory cohesion mechanisms exist in these cells that undergo a normal mitotic division. These studies provide a unique in vivo vertebrate view of the mitotic defects and consequences of cohesion establishment loss, and they provide a compensation-based model to explain the RBS phenotypes.

  19. Effect of nebulizer/spray chamber interfaces on simultaneous, axial view inductively coupled plasma optical emission spectrometry for the direct determination of As and Se species separated by ion exchange high-performance liquid chromatography

    Science.gov (United States)

    Gettar, Raquel T.; Smichowski, Patricia; Garavaglia, Ricardo N.; Farías, Silvia; Batistoni, Daniel A.

    2005-06-01

    Different nebulizer/expansion chamber combinations were evaluated to assess their performance for sample introduction in the direct coupling with an axial view inductively coupled plasma multielement spectrometer for on-line determination of As and Se species previously separated by ion exchange-high performance liquid chromatography. The column effluents were injected into the plasma without prior derivatization. The instrument operation software was adapted for data acquisition and processing to allow multi-wavelength recording of the transient chromatographic peaks. After optimization of the chromatographic operating conditions, separation of mixtures of inorganic As and Se species, and of inorganic and two organic As species (monomethylarsonic and dimethylarsinic acids), was achieved with excellent resolution. Species discrimination from mixtures of As and Se oxyanions was further improved by the simultaneous element detection at specific analytical wavelengths. Three nebulizers and three spray chambers, employed in seven combinations, were tested as interfaces. Concentric nebulizers associated to a glass cyclonic chamber appear most suitable regarding sensitivity and signal to noise ratio. Measured element detection limits (3 σ) were around 10 ng ml - 1 for all the species considered, making the method a viable alternative to similar procedures that employ volatile hydride generation previous to sample injection into the plasma. Analytical recoveries both for inorganic and organic species ranged between 92 and 107%. The method was demonstrated to be apt for the analysis of surface waters potentially subjected to natural contamination with arsenic.

  20. Mutagen sensitivity as measured by induced chromatid breakage as a marker of cancer risk.

    Science.gov (United States)

    Wu, Xifeng; Zheng, Yun-Ling; Hsu, T C

    2014-01-01

    Risk assessment is now recognized as a multidisciplinary process, extending beyond the scope of traditional epidemiologic methodology to include biological evaluation of interindividual differences in carcinogenic susceptibility. Modulation of environmental exposures by host genetic factors may explain much of the observed interindividual variation in susceptibility to carcinogenesis. These genetic factors include, but are not limited to, carcinogen metabolism and DNA repair capacity. This chapter describes a standardized method for the functional assessment of mutagen sensitivity. This in vitro assay measures the frequency of mutagen-induced breaks in the chromosomes of peripheral blood lymphocytes. Mutagen sensitivity assessed by this method has been shown to be a significant risk factor for tobacco-related maladies, especially those of the upper aerodigestive tract. Mutagen sensitivity may therefore be a useful member of a panel of susceptibility markers for defining high-risk subgroups for chemoprevention trials. This chapter describes methods for and discusses results from studies of mutagen sensitivity as measured by quantifying chromatid breaks induced by clastogenic agents, such as the γ-radiation mimetic DNA cross-linking agent bleomycin and chemicals that form so-called bulky DNA adducts, such as 4-nitroquinoline and the tobacco smoke constituent benzo[a]pyrene, in short-term cultured peripheral blood lymphocytes.

  1. Role of the Saccharomyces cerevisiae Rad51 paralogs in sister chromatid recombination.

    Science.gov (United States)

    Mozlin, Amy M; Fung, Cindy W; Symington, Lorraine S

    2008-01-01

    Rad51 requires a number of other proteins, including the Rad51 paralogs, for efficient recombination in vivo. Current evidence suggests that the yeast Rad51 paralogs, Rad55 and Rad57, are important in formation or stabilization of the Rad51 nucleoprotein filament. To gain further insights into the function of the Rad51 paralogs, reporters were designed to measure spontaneous or double-strand break (DSB)-induced sister or nonsister recombination. Spontaneous sister chromatid recombination (SCR) was reduced 6000-fold in the rad57 mutant, significantly more than in the rad51 mutant. Although the DSB-induced recombination defect of rad57 was suppressed by overexpression of Rad51, elevated temperature, or expression of both mating-type alleles, the rad57 defect in spontaneous SCR was not strongly suppressed by these same factors. In addition, the UV sensitivity of the rad57 mutant was not strongly suppressed by MAT heterozygosity, even though Rad51 foci were restored under these conditions. This lack of suppression suggests that Rad55 and Rad57 have different roles in the recombinational repair of stalled replication forks compared with DSB repair. Furthermore, these data suggest that most spontaneous SCR initiates from single-stranded gaps formed at stalled replication forks rather than DSBs.

  2. Rfc5p regulates alternate RFC complex functions in sister chromatid pairing reactions in budding yeast.

    Science.gov (United States)

    Maradeo, Marie E; Garg, Anisha; Skibbens, Robert V

    2010-11-01

    Sister chromatid pairing reactions, termed cohesion establishment, occur during S-phase and appear to be regulated by Replication Factor C (RFC) complexes. For instance, RFCs that contain Ctf18p exhibit pro-establishment activities while those that contain Elg1p exhibit anti-establishment activities. It remains unknown whether Ctf18p-RFC and Elg1p-RFC functions are simply opposing or instead reveal complicated and non-parallel regulatory mechanisms. To better understand the nature of these novel pathways, we analyzed the small RFC subunit Rfc5p that is common to both Ctf18p-RFC and Elg1p-RFC. Despite this commonality, the data show that diminished Rfc5p function rescues ctf7/eco1 mutant cell phenotypes, revealing that Rfc5p promotes anti-establishment activities. This rescue is specific to establishment pathways in that rfc5-1 greatly accentuates growth defects when expressed in scc2 (deposition), mcd1/scc1 or smc3 (cohesion maintenance) mutated cells. Our results reveal for the first time a role for small RFC subunits in directing RFC complex functions-in this case towards anti-establishment pathways. We further report that Pds5p exhibits both establishment and anti-establishment functions in cohesion. This duality suggests that categorizations of establishment and anti-establishment activities require further examination.

  3. Defective sister chromatid cohesion is synthetically lethal with impaired APC/C function.

    Science.gov (United States)

    de Lange, Job; Faramarz, Atiq; Oostra, Anneke B; de Menezes, Renee X; van der Meulen, Ida H; Rooimans, Martin A; Rockx, Davy A; Brakenhoff, Ruud H; van Beusechem, Victor W; King, Randall W; de Winter, Johan P; Wolthuis, Rob M F

    2015-10-01

    Warsaw breakage syndrome (WABS) is caused by defective DDX11, a DNA helicase that is essential for chromatid cohesion. Here, a paired genome-wide siRNA screen in patient-derived cell lines reveals that WABS cells do not tolerate partial depletion of individual APC/C subunits or the spindle checkpoint inhibitor p31(comet). A combination of reduced cohesion and impaired APC/C function also leads to fatal mitotic arrest in diploid RPE1 cells. Moreover, WABS cell lines, and several cancer cell lines with cohesion defects, display a highly increased response to a new cell-permeable APC/C inhibitor, apcin, but not to the spindle poison paclitaxel. Synthetic lethality of APC/C inhibition and cohesion defects strictly depends on a functional mitotic spindle checkpoint as well as on intact microtubule pulling forces. This indicates that the underlying mechanism involves cohesion fatigue in response to mitotic delay, leading to spindle checkpoint re-activation and lethal mitotic arrest. Our results point to APC/C inhibitors as promising therapeutic agents targeting cohesion-defective cancers.

  4. Gravitational induction

    CERN Document Server

    Bini, Donato; Chicone, Carmen; Mashhoon, Bahram

    2008-01-01

    We study the linear post-Newtonian approximation to general relativity known as gravitoelectromagnetism (GEM); in particular, we examine the similarities and differences between GEM and electrodynamics. Notwithstanding some significant differences between them, we find that a special nonstationary metric in GEM can be employed to show {\\it explicitly} that it is possible to introduce gravitational induction within GEM in close analogy with Faraday's law of induction and Lenz's law in electrodynamics. Some of the physical implications of gravitational induction are briefly discussed.

  5. Inductive reasoning.

    Science.gov (United States)

    Hayes, Brett K; Heit, Evan; Swendsen, Haruka

    2010-03-01

    Inductive reasoning entails using existing knowledge or observations to make predictions about novel cases. We review recent findings in research on category-based induction as well as theoretical models of these results, including similarity-based models, connectionist networks, an account based on relevance theory, Bayesian models, and other mathematical models. A number of touchstone empirical phenomena that involve taxonomic similarity are described. We also examine phenomena involving more complex background knowledge about premises and conclusions of inductive arguments and the properties referenced. Earlier models are shown to give a good account of similarity-based phenomena but not knowledge-based phenomena. Recent models that aim to account for both similarity-based and knowledge-based phenomena are reviewed and evaluated. Among the most important new directions in induction research are a focus on induction with uncertain premise categories, the modeling of the relationship between inductive and deductive reasoning, and examination of the neural substrates of induction. A common theme in both the well-established and emerging lines of induction research is the need to develop well-articulated and empirically testable formal models of induction. Copyright © 2010 John Wiley & Sons, Ltd. For further resources related to this article, please visit the WIREs website.

  6. Radiation sensitivity of the gastrula-stage embryo: Chromosome aberrations and mutation induction in lacZ transgenic mice: The roles of DNA double-strand break repair systems.

    Science.gov (United States)

    Jacquet, Paul; van Buul, Paul; van Duijn-Goedhart, Annemarie; Reynaud, Karine; Buset, Jasmine; Neefs, Mieke; Michaux, Arlette; Monsieurs, Pieter; de Boer, Peter; Baatout, Sarah

    2015-10-01

    At the gastrula phase of development, just after the onset of implantation, the embryo proper is characterized by extremely rapid cell proliferation. The importance of DNA repair is illustrated by embryonic lethality at this stage after ablation of the genes involved. Insight into mutation induction is called for by the fact that women often do not realize they are pregnant, shortly after implantation, a circumstance which may have important consequences when women are subjected to medical imaging using ionizing radiation. We screened gastrula embryos for DNA synthesis, nuclear morphology, growth, and chromosome aberrations (CA) shortly after irradiation with doses up to 2.5Gy. In order to obtain an insight into the importance of DNA repair for CA induction, we included mutants for the non-homologous end joining (NHEJ) and homologous recombination repair (HRR) pathways, as well as Parp1-/- and p53+/- embryos. With the pUR288 shuttle vector assay, we determined the radiation sensitivity for point mutations and small deletions detected in young adults. We found increased numbers of abnormal nuclei 5h after irradiation; an indication of disturbed development was also observed around this time. Chromosome aberrations 7h after irradiation arose in all genotypes and were mainly of the chromatid type, in agreement with a cell cycle dominated by S-phase. Increased frequencies of CA were found for NHEJ and HR mutants. Gastrula embryos are unusual in that they are low in exchange induction, even after compromised HR. Gastrula embryos were radiation sensitive in the pUR288 shuttle vector assay, giving the highest mutation induction ever reported for this genetic toxicology model. On theoretical grounds, a delayed radiation response must be involved. The compromised developmental profile after doses up to 2.5Gy likely is caused by both apoptosis and later cell death due to large deletions. Our data indicate a distinct radiation-sensitive profile of gastrula embryos, including

  7. A novel mechanism for the establishment of sister chromatid cohesion by the ECO1 acetyltransferase.

    Science.gov (United States)

    Guacci, Vincent; Stricklin, Jeremiah; Bloom, Michelle S; Guō, Xuánzōng; Bhatter, Meghna; Koshland, Douglas

    2015-01-01

    Cohesin complex mediates cohesion between sister chromatids, which promotes high-fidelity chromosome segregation. Eco1p acetylates the cohesin subunit Smc3p during S phase to establish cohesion. The current model posits that this Eco1p-mediated acetylation promotes establishment by abrogating the ability of Wpl1p to destabilize cohesin binding to chromosomes. Here we present data from budding yeast that is incompatible with this Wpl1p-centric model. Two independent in vivo assays show that a wpl1∆ fails to suppress cohesion defects of eco1∆ cells. Moreover, a wpl1∆ also fails to suppress cohesion defects engendered by blocking just the essential Eco1p acetylation sites on Smc3p (K112, K113). Thus removing WPL1 inhibition is insufficient for generating cohesion without ECO1 activity. To elucidate how ECO1 promotes cohesion, we conducted a genetic screen and identified a cohesion activator mutation in the SMC3 head domain (D1189H). Smc3-D1189H partially restores cohesion in eco1∆ wpl1∆ or eco1 mutant cells but robustly restores cohesion in cells blocked for Smc3p K112 K113 acetylation. These data support two important conclusions. First, acetylation of the K112 K113 region by Eco1p promotes cohesion establishment by altering Smc3p head function independent of its ability to antagonize Wpl1p. Second, Eco1p targets other than Smc3p K112 K113 are necessary for efficient establishment.

  8. Optimization of collision/reaction gases for determination of 90Sr in atmospheric particulate matter by inductively coupled plasma tandem mass spectrometry after direct introduction of air via a gas-exchange device

    Science.gov (United States)

    Suzuki, Yoshinari; Ohara, Ryota; Matsunaga, Kirara

    2017-09-01

    Nuclear power plant accidents release radioactive strontium 90 (90Sr) into the environment. Monitoring of 90Sr, although important, is difficult and time consuming because it emits only beta radiation. We have developed a new analytical system that enables real-time analysis of 90Sr in atmospheric particulate matter with an analytical run time of only 10 min. Briefly, after passage of an air sample through an impactor, a small fraction of the sample is introduced into a gas-exchange device, where the air is replaced by Ar. Then the sample is directly introduced into an inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) system equipped with a collision/reaction cell to eliminate isobaric interferences on 90Sr from 90Zr+, 89Y1H+, and 90Y+. Experiments with various reaction gas conditions revealed that these interferences could be minimized under the following optimized conditions: 1.0 mL min- 1 O2, 10.0 mL min- 1 H2, and 1.0 mL min- 1 NH3. The estimated background equivalent concentration and estimated detection limit of the system were 9.7 × 10- 4 and 3.6 × 10- 4 ng m- 3, respectively, which are equivalent to 4.9 × 10- 6 and 1.8 × 10- 6 Bq cm- 3. Recoveries of Sr in PM2.5 measured by real-time analysis compared to those obtained by simultaneously collection on filter was 53 ± 23%, and using this recovery, the detection limit as PM2.5 was estimated to be 3.4 ± 1.5 × 10- 6 Bq cm- 3. That is, this system enabled detection of 90Sr at concentrations < 5 × 10- 6 Bq cm- 3 even considering the insufficient fusion/vaporization/ionization efficiency of Sr in PM2.5.

  9. Inductive Learning

    Institute of Scientific and Technical Information of China (English)

    吴信东

    1993-01-01

    Machine learning(ML)is a major subfield of artificial intelligence(AI).It has been seen as a feasible way of avoiding the knowledge bottleneck problem in knowledge-based systems development.Research on ML has concentrated in the main on inductive learning,a paradigm for inducing rules from unordered sets of exmaples.AQ11 and ID3,the two most widespred algorithms in ML,are both inductive.This paper first summarizes AQ11,ID3 and the newly-developed extension matrix approach based HCV algorithm;and then reviews the recent development of inductive learing and automatic knowledge acquisition from data bases.

  10. Chiasmata Promote Monopolar Attachment of Sister Chromatids and Their Co-Segregation toward the Proper Pole during Meiosis I

    Science.gov (United States)

    Ohba, Tatsunori; Hinohara, Yumi; Matsuhara, Hirotada; Yoshida, Masashi; Itabashi, Yuta; Murakami, Hiroshi; Yamamoto, Ayumu

    2011-01-01

    The chiasma is a structure that forms between a pair of homologous chromosomes by crossover recombination and physically links the homologous chromosomes during meiosis. Chiasmata are essential for the attachment of the homologous chromosomes to opposite spindle poles (bipolar attachment) and their subsequent segregation to the opposite poles during meiosis I. However, the overall function of chiasmata during meiosis is not fully understood. Here, we show that chiasmata also play a crucial role in the attachment of sister chromatids to the same spindle pole and in their co-segregation during meiosis I in fission yeast. Analysis of cells lacking chiasmata and the cohesin protector Sgo1 showed that loss of chiasmata causes frequent bipolar attachment of sister chromatids during anaphase. Furthermore, high time-resolution analysis of centromere dynamics in various types of chiasmate and achiasmate cells, including those lacking the DNA replication checkpoint factor Mrc1 or the meiotic centromere protein Moa1, showed the following three outcomes: (i) during the pre-anaphase stage, the bipolar attachment of sister chromatids occurs irrespective of chiasma formation; (ii) the chiasma contributes to the elimination of the pre-anaphase bipolar attachment; and (iii) when the bipolar attachment remains during anaphase, the chiasmata generate a bias toward the proper pole during poleward chromosome pulling that results in appropriate chromosome segregation. Based on these results, we propose that chiasmata play a pivotal role in the selection of proper attachments and provide a backup mechanism that promotes correct chromosome segregation when improper attachments remain during anaphase I. PMID:21423721

  11. Overexpression of SETβ, a protein localizing to centromeres, causes precocious separation of chromatids during the first meiosis of mouse oocytes.

    Science.gov (United States)

    Qi, Shu-Tao; Wang, Zhen-Bo; Ouyang, Ying-Chun; Zhang, Qing-Hua; Hu, Meng-Wen; Huang, Xin; Ge, Zhaojia; Guo, Lei; Wang, Ya-Peng; Hou, Yi; Schatten, Heide; Sun, Qing-Yuan

    2013-04-01

    Chromosome segregation in mammalian oocyte meiosis is an error-prone process, and any mistake in this process may result in aneuploidy, which is the main cause of infertility, abortion and many genetic diseases. It is now well known that shugoshin and protein phosphatase 2A (PP2A) play important roles in the protection of centromeric cohesion during the first meiosis. PP2A can antagonize the phosphorylation of rec8, a member of the cohesin complex, at the centromeres and thus prevent cleavage of rec8 and so maintain the cohesion of chromatids. SETβ is a protein that physically interacts with shugoshin and inhibits PP2A activity. We thus hypothesized that SETβ might regulate cohesion protection and chromosome segregation during oocyte meiotic maturation. Here we report for the first time the expression, subcellular localization and functions of SETβ during mouse oocyte meiosis. Immunoblotting analysis showed that the expression level of SETβ was stable from the germinal vesicle stage to the MII stage of oocyte meiosis. Immunofluorescence analysis showed SETβ accumulation in the nucleus at the germinal vesicle stage, whereas it was targeted mainly to the inner centromere area and faintly localized to the interchromatid axes from germinal vesicle breakdown to MI stages. At the MII stage, SETβ still localized to the inner centromere area, but could relocalize to kinetochores in a process perhaps dependent on the tension on the centromeres. SETβ partly colocalized with PP2A at the inner centromere area. Overexpression of SETβ in mouse oocytes caused precocious separation of sister chromatids, but depletion of SETβ by RNAi showed little effects on the meiotic maturation process. Taken together, our results suggest that SETβ, even though it localizes to centromeres, might not be essential for chromosome separation during mouse oocyte meiotic maturation, although its forced overexpression causes premature chromatid separation.

  12. Chiasmata promote monopolar attachment of sister chromatids and their co-segregation toward the proper pole during meiosis I.

    Directory of Open Access Journals (Sweden)

    Yukinobu Hirose

    2011-03-01

    Full Text Available The chiasma is a structure that forms between a pair of homologous chromosomes by crossover recombination and physically links the homologous chromosomes during meiosis. Chiasmata are essential for the attachment of the homologous chromosomes to opposite spindle poles (bipolar attachment and their subsequent segregation to the opposite poles during meiosis I. However, the overall function of chiasmata during meiosis is not fully understood. Here, we show that chiasmata also play a crucial role in the attachment of sister chromatids to the same spindle pole and in their co-segregation during meiosis I in fission yeast. Analysis of cells lacking chiasmata and the cohesin protector Sgo1 showed that loss of chiasmata causes frequent bipolar attachment of sister chromatids during anaphase. Furthermore, high time-resolution analysis of centromere dynamics in various types of chiasmate and achiasmate cells, including those lacking the DNA replication checkpoint factor Mrc1 or the meiotic centromere protein Moa1, showed the following three outcomes: (i during the pre-anaphase stage, the bipolar attachment of sister chromatids occurs irrespective of chiasma formation; (ii the chiasma contributes to the elimination of the pre-anaphase bipolar attachment; and (iii when the bipolar attachment remains during anaphase, the chiasmata generate a bias toward the proper pole during poleward chromosome pulling that results in appropriate chromosome segregation. Based on these results, we propose that chiasmata play a pivotal role in the selection of proper attachments and provide a backup mechanism that promotes correct chromosome segregation when improper attachments remain during anaphase I.

  13. Practicing induction:

    DEFF Research Database (Denmark)

    Sprogøe, Jonas; Rohde, Nicolas

    2009-01-01

    We claim that induction potentially triggers both individual and organizational learning and by drawing on practice-based theory we discuss how the interplay between individual and organization, what we call a generative dance, ignites both kinds of learning....

  14. Gravitational induction

    OpenAIRE

    Bini, Donato; Cherubini, Christian; Chicone, Carmen; Mashhoon, Bahram

    2008-01-01

    We study the linear post-Newtonian approximation to general relativity known as gravitoelectromagnetism (GEM); in particular, we examine the similarities and differences between GEM and electrodynamics. Notwithstanding some significant differences between them, we find that a special nonstationary metric in GEM can be employed to show {\\it explicitly} that it is possible to introduce gravitational induction within GEM in close analogy with Faraday's law of induction and Lenz's law in electrod...

  15. Unequal sister chromatid and homolog recombination at a tandem duplication of the A1 locus in maize.

    Science.gov (United States)

    Yandeau-Nelson, Marna D; Xia, Yiji; Li, Jin; Neuffer, M Gerald; Schnable, Patrick S

    2006-08-01

    Tandemly arrayed duplicate genes are prevalent. The maize A1-b haplotype is a tandem duplication that consists of the components, alpha and beta. The rate of meiotic unequal recombination at A1-b is ninefold higher when a homolog is present than when it is absent (i.e., hemizygote). When a sequence heterologous homolog is available, 94% of recombinants (264/281) are generated via recombination with the homolog rather than with the sister chromatid. In addition, 83% (220/264) of homolog recombination events involved alpha rather than beta. These results indicate that: (1) the homolog is the preferred template for unequal recombination and (2) pairing of the duplicated segments with the homolog does not occur randomly but instead favors a particular configuration. The choice of recombination template (i.e., homolog vs. sister chromatid) affects the distribution of recombination breakpoints within a1. Rates of unequal recombination at A1-b are similar to the rate of recombination between nonduplicated a1 alleles. Unequal recombination is therefore common and is likely to be responsible for the generation of genetic variability, even within inbred lines.

  16. Increased LOH due to Defective Sister Chromatid Cohesion Is due Primarily to Chromosomal Aneuploidy and not Recombination

    Directory of Open Access Journals (Sweden)

    Dror Sagi

    2017-10-01

    Full Text Available Loss of heterozygosity (LOH is an important factor in cancer, pathogenic fungi, and adaptation to changing environments. The sister chromatid cohesion process (SCC suppresses aneuploidy and therefore whole chromosome LOH. SCC is also important to channel recombinational repair to sister chromatids, thereby preventing LOH mediated by allelic recombination. There is, however, insufficient information about the relative roles that the SCC pathway plays in the different modes of LOH. Here, we found that the cohesin mutation mcd1-1, and other mutations in SCC, differentially affect the various types of LOH. The greatest effect, by three orders of magnitude, was on whole chromosome loss (CL. In contrast, there was little increase in recombination-mediated LOH, even for telomeric markers. Some of the LOH events that were increased by SCC mutations were complex, i.e., they were the result of several chromosome transactions. Although these events were independent of POL32, the most parsimonious way to explain the formation of at least some of them was break-induced replication through the centromere. Interestingly, the mcd1-1 pol32Δ double mutant showed a significant reduction in the rate of CL in comparison with the mcd1-1 single mutant. Our results show that defects in SCC allow the formation of complex LOH events that, in turn, can promote drug or pesticide resistance in diploid microbes that are pathogenic to humans or plants.

  17. Regulation of centromere localization of the Drosophila Shugoshin MEI-S332 and sister-chromatid cohesion in meiosis.

    Science.gov (United States)

    Nogueira, Cristina; Kashevsky, Helena; Pinto, Belinda; Clarke, Astrid; Orr-Weaver, Terry L

    2014-07-31

    The Shugoshin (Sgo) protein family helps to ensure proper chromosome segregation by protecting cohesion at the centromere by preventing cleavage of the cohesin complex. Some Sgo proteins also influence other aspects of kinetochore-microtubule attachments. Although many Sgo members require Aurora B kinase to localize to the centromere, factors controlling delocalization are poorly understood and diverse. Moreover, it is not clear how Sgo function is inactivated and whether this is distinct from delocalization. We investigated these questions in Drosophila melanogaster, an organism with superb chromosome cytology to monitor Sgo localization and quantitative assays to test its function in sister-chromatid segregation in meiosis. Previous research showed that in mitosis in cell culture, phosphorylation of the Drosophila Sgo, MEI-S332, by Aurora B promotes centromere localization, whereas Polo phosphorylation promotes delocalization. These studies also suggested that MEI-S332 can be inactivated independently of delocalization, a conclusion supported here by localization and function studies in meiosis. Phosphoresistant and phosphomimetic mutants for the Aurora B and Polo phosphorylation sites were examined for effects on MEI-S332 localization and chromosome segregation in meiosis. Strikingly, MEI-S332 with a phosphomimetic mutation in the Aurora B phosphorylation site prematurely dissociates from the centromeres in meiosis I. Despite the absence of MEI-S332 on meiosis II centromeres in male meiosis, sister chromatids segregate normally, demonstrating that detectable levels of this Sgo are not essential for chromosome congression, kinetochore biorientation, or spindle assembly. Copyright © 2014 Nogueira et al.

  18. The MCM-binding protein ETG1 aids sister chromatid cohesion required for postreplicative homologous recombination repair.

    Directory of Open Access Journals (Sweden)

    Naoki Takahashi

    2010-01-01

    Full Text Available The DNA replication process represents a source of DNA stress that causes potentially spontaneous genome damage. This effect might be strengthened by mutations in crucial replication factors, requiring the activation of DNA damage checkpoints to enable DNA repair before anaphase onset. Here, we demonstrate that depletion of the evolutionarily conserved minichromosome maintenance helicase-binding protein ETG1 of Arabidopsis thaliana resulted in a stringent late G2 cell cycle arrest. This arrest correlated with a partial loss of sister chromatid cohesion. The lack-of-cohesion phenotype was intensified in plants without functional CTF18, a replication fork factor needed for cohesion establishment. The synergistic effect of the etg1 and ctf18 mutants on sister chromatid cohesion strengthened the impact on plant growth of the replication stress caused by ETG1 deficiency because of inefficient DNA repair. We conclude that the ETG1 replication factor is required for efficient cohesion and that cohesion establishment is essential for proper development of plants suffering from endogenous DNA stress. Cohesion defects observed upon knockdown of its human counterpart suggest an equally important developmental role for the orthologous mammalian ETG1 protein.

  19. Rtt107 phosphorylation promotes localisation to DNA double-stranded breaks (DSBs and recombinational repair between sister chromatids.

    Directory of Open Access Journals (Sweden)

    Pranav Ullal

    Full Text Available Efficient repair of DNA double-stranded breaks (DSB requires a coordinated response at the site of lesion. Nucleolytic resection commits repair towards homologous recombination, which preferentially occurs between sister chromatids. DSB resection promotes recruitment of the Mec1 checkpoint kinase to the break. Rtt107 is a target of Mec1 and serves as a scaffold during repair. Rtt107 plays an important role during rescue of damaged replication forks, however whether Rtt107 contributes to the repair of DSBs is unknown. Here we show that Rtt107 is recruited to DSBs induced by the HO endonuclease. Rtt107 phosphorylation by Mec1 and its interaction with the Smc5-Smc6 complex are both required for Rtt107 loading to breaks, while Rtt107 regulators Slx4 and Rtt101 are not. We demonstrate that Rtt107 has an effect on the efficiency of sister chromatid recombination (SCR and propose that its recruitment to DSBs, together with the Smc5-Smc6 complex is important for repair through the SCR pathway.

  20. Induction Brazing

    DEFF Research Database (Denmark)

    Henningsen, Poul

    . The method has proven to give successful results in brazing tube-plate joints of copper-brass, copper-stainless steel, stainless steel-brass, and stainless steel-stainless steel. A new design of an adjustable flux concentrator for induction heating tube-to-plate joints is proposed and tested on a variety......Induction brazing is a fast and appropriate method for industrial joining of complex geometries and metal combinations. In all types of brazing processes it is important to heat the joint interface of the two materials to the same, high temperature. If one of the specimens is warmer than the other...... materials has large influence on the heating time and temperature distribution in induction heating. In order to ensure high and uniform temperature distribution near the interface of a joint between dissimilar materials the precise coil geometry and position is of great importance. The present report...

  1. Frequent and efficient use of the sister chromatid for DNA double-strand break repair during budding yeast meiosis.

    Directory of Open Access Journals (Sweden)

    Tamara Goldfarb

    Full Text Available Recombination between homologous chromosomes of different parental origin (homologs is necessary for their accurate segregation during meiosis. It has been suggested that meiotic inter-homolog recombination is promoted by a barrier to inter-sister-chromatid recombination, imposed by meiosis-specific components of the chromosome axis. Consistent with this, measures of Holliday junction-containing recombination intermediates (joint molecules [JMs] show a strong bias towards inter-homolog and against inter-sister JMs. However, recombination between sister chromatids also has an important role in meiosis. The genomes of diploid organisms in natural populations are highly polymorphic for insertions and deletions, and meiotic double-strand breaks (DSBs that form within such polymorphic regions must be repaired by inter-sister recombination. Efforts to study inter-sister recombination during meiosis, in particular to determine recombination frequencies and mechanisms, have been constrained by the inability to monitor the products of inter-sister recombination. We present here molecular-level studies of inter-sister recombination during budding yeast meiosis. We examined events initiated by DSBs in regions that lack corresponding sequences on the homolog, and show that these DSBs are efficiently repaired by inter-sister recombination. This occurs with the same timing as inter-homolog recombination, but with reduced (2- to 3-fold yields of JMs. Loss of the meiotic-chromosome-axis-associated kinase Mek1 accelerates inter-sister DSB repair and markedly increases inter-sister JM frequencies. Furthermore, inter-sister JMs formed in mek1Δ mutants are preferentially lost, while inter-homolog JMs are maintained. These findings indicate that inter-sister recombination occurs frequently during budding yeast meiosis, with the possibility that up to one-third of all recombination events occur between sister chromatids. We suggest that a Mek1-dependent reduction in

  2. Rec8p, a meiotic recombination and sister chromatid cohesion phosphoprotein of the Rad21p family conserved from fision yeast to humans.

    NARCIS (Netherlands)

    S. Parisi; M.J. McKay (Michael); M. Molnar; M.A. Thompson (Anne); P.J. van der Spek (Peter); E. van Drunen-Schoenmaker; R. Kanaar (Roland); E. Lehmann; J.H.J. Hoeijmakers (Jan); J. Kohli

    1999-01-01

    textabstractOur work and that of others defined mitosis-specific (Rad21 subfamily) and meiosis-specific (Rec8 subfamily) proteins involved in sister chromatid cohesion in several eukaryotes, including humans. Mutation of the fission yeast Schizosaccharomyces pombe rec8 gene was previously shown to

  3. Rec8p, a meiotic recombination and sister chromatid cohesion phosphoprotein of the Rad21p family conserved from fision yeast to humans.

    NARCIS (Netherlands)

    S. Parisi; M.J. McKay (Michael); M. Molnar; M.A. Thompson (Anne); P.J. van der Spek (Peter); E. van Drunen-Schoenmaker; R. Kanaar (Roland); E. Lehmann; J.H.J. Hoeijmakers (Jan); J. Kohli

    1999-01-01

    textabstractOur work and that of others defined mitosis-specific (Rad21 subfamily) and meiosis-specific (Rec8 subfamily) proteins involved in sister chromatid cohesion in several eukaryotes, including humans. Mutation of the fission yeast Schizosaccharomyces pombe rec8 gene was previously shown to c

  4. Induction practice -

    DEFF Research Database (Denmark)

    Rohde, Nicolas; Sprogøe, Jonas

    2007-01-01

    that induction potentially triggers both individual and organizational learning and by drawing on practice-based theory we discuss how the interplay between individual and the organization, what we call agenerative dance, ignites both kinds of learning. We focus on and describe the interplay , ignites both kinds...... of learning. We focus on and describe the interplay that takes place in particular induction events and analyze the "dance" through the lens of learning. The paper concludes with a brief discussion about the implications for practitioners and the challenges and future research prospects we have encountered....... We draw on an empirical enquiry in two organizational settings, a Danish management consulting company and a German retail bank....

  5. SGO1 maintains bovine meiotic and mitotic centromeric cohesions of sister chromatids and directly affects embryo development.

    Directory of Open Access Journals (Sweden)

    Feng-Xia Yin

    Full Text Available Shugoshin (SGO is a critical factor that enforces cohesion from segregation of paired sister chromatids during mitosis and meiosis. It has been studied mainly in invertebrates. Knowledge of SGO(s in a mammalian system has only been reported in the mouse and Hela cells. In this study, the functions of SGO1 in bovine oocytes during meiotic maturation, early embryonic development and somatic cell mitosis were investigated. The results showed that SGO1 was expressed from germinal vesicle (GV to the metaphase II stage. SGO1 accumulated on condensed and scattered chromosomes from pre-metaphase I to metaphase II. The over-expression of SGO1 did not interfere with the process of homologous chromosome separation, although once separated they were unable to move to the opposing spindle poles. This often resulted in the formation of oocytes with 60 replicated chromosomes. Depletion of SGO1 in GV oocytes affected chromosomal separation resulting in abnormal chromosome alignment at a significantly higher proportion than in control oocytes. Knockdown of SGO1 expression significantly decreased the embryonic developmental rate and quality. To further confirm the function(s of SGO1 during mitosis, bovine embryonic fibroblast cells were transfected with SGO1 siRNAs. SGO1 depletion induced the premature dissociation of chromosomal cohesion at the centromere and along the chromosome arm giving rise to abnormal appearing mitotic patterns. The results of this study infer that SGO1 is involved in the centromeric cohesion of sister chromatids and chromosomal movement towards the spindle poles. Depletion of SGO1 causes arrestment of cell division in meiosis and mitosis.

  6. Induction Brazing

    DEFF Research Database (Denmark)

    Henningsen, Poul

    , or if the hottest area is located outside the joint interface, a number of defects may appear: the braze metal may flow away from the joint, the flux may burn off, poor binding of the braze metal may appear or the braze metal may be overheated. Joint geometry as well as electro-magnetic properties of the work piece......Induction brazing is a fast and appropriate method for industrial joining of complex geometries and metal combinations. In all types of brazing processes it is important to heat the joint interface of the two materials to the same, high temperature. If one of the specimens is warmer than the other...

  7. Left-right symmetry breaking in mice by left-right dynein may occur via a biased chromatid segregation mechanism, without directly involving the Nodal gene

    Directory of Open Access Journals (Sweden)

    Stephan eSauer

    2012-11-01

    Full Text Available Ever since cloning the classic iv mutation identified the ‘left-right dynein’ (lrd gene in mice, most research on body laterality determination has focused on its function in motile cilia at the node embryonic organizer. This model is attractive, as it links chirality of cilia architecture to asymmetry development. However, lrd is also expressed in blastocysts and embryonic stem cells, where it was shown to bias the segregation of recombined sister chromatids away from each other in mitosis. These data suggested that lrd is part of a cellular mechanism that recognizes and selectively segregates sister chromatids based on their replication history: old ‘Watson’ vs. old ‘Crick’ strands. We previously proposed that the mouse left-right axis is established via an asymmetric cell division prior to/or during gastrulation. In this model, left-right dynein selectively segregates epigenetically differentiated sister chromatids harboring a hypothetical ‘left-right axis development 1’ (‘lra1’ gene during the left-right axis establishing cell division. Here, asymmetry development would be ultimately governed by the chirality of the cytoskeleton and the DNA molecule. Our model predicts that randomization of chromatid segregation in lrd mutants should produce embryos with 25% situs solitus, 25% situs inversus, and 50% embryonic death due to heterotaxia and isomerism. Here we confirmed this prediction by using two distinct lrd mutant alleles. Other than lrd, thus far Nodal gene is the most upstream function implicated in visceral organs laterality determination. We next tested whether the Nodal gene constitutes the lra1 gene hypothesized in the model by testing mutant’s effect on 50% embryonic lethality observed in lrd mutants. Since Nodal mutation did not suppress lethality, we conclude that Nodal is not equivalent to the lra1 gene. In summary, we describe the origin of 50% lethality in lrd mutant mice not yet explained by any other

  8. Regulation of the Drosophila Enhancer of split and invected-engrailed gene complexes by sister chromatid cohesion proteins.

    Directory of Open Access Journals (Sweden)

    Cheri A Schaaf

    Full Text Available The cohesin protein complex was first recognized for holding sister chromatids together and ensuring proper chromosome segregation. Cohesin also regulates gene expression, but the mechanisms are unknown. Cohesin associates preferentially with active genes, and is generally absent from regions in which histone H3 is methylated by the Enhancer of zeste [E(z] Polycomb group silencing protein. Here we show that transcription is hypersensitive to cohesin levels in two exceptional cases where cohesin and the E(z-mediated histone methylation simultaneously coat the entire Enhancer of split and invected-engrailed gene complexes in cells derived from Drosophila central nervous system. These gene complexes are modestly transcribed, and produce seven of the twelve transcripts that increase the most with cohesin knockdown genome-wide. Cohesin mutations alter eye development in the same manner as increased Enhancer of split activity, suggesting that similar regulation occurs in vivo. We propose that cohesin helps restrain transcription of these gene complexes, and that deregulation of similarly cohesin-hypersensitive genes may underlie developmental deficits in Cornelia de Lange syndrome.

  9. SNW1 enables sister chromatid cohesion by mediating the splicing of sororin and APC2 pre-mRNAs.

    Science.gov (United States)

    van der Lelij, Petra; Stocsits, Roman R; Ladurner, Rene; Petzold, Georg; Kreidl, Emanuel; Koch, Birgit; Schmitz, Julia; Neumann, Beate; Ellenberg, Jan; Peters, Jan-Michael

    2014-11-18

    Although splicing is essential for the expression of most eukaryotic genes, inactivation of splicing factors causes specific defects in mitosis. The molecular cause of this defect is unknown. Here, we show that the spliceosome subunits SNW1 and PRPF8 are essential for sister chromatid cohesion in human cells. A transcriptome-wide analysis revealed that SNW1 or PRPF8 depletion affects the splicing of specific introns in a subset of pre-mRNAs, including pre-mRNAs encoding the cohesion protein sororin and the APC/C subunit APC2. SNW1 depletion causes cohesion defects predominantly by reducing sororin levels, which causes destabilisation of cohesin on DNA. SNW1 depletion also reduces APC/C activity and contributes to cohesion defects indirectly by delaying mitosis and causing "cohesion fatigue". Simultaneous expression of sororin and APC2 from intron-less cDNAs restores cohesion in SNW1-depleted cells. These results indicate that the spliceosome is required for mitosis because it enables expression of genes essential for cohesion. Our transcriptome-wide identification of retained introns in SNW1- and PRPF8-depleted cells may help to understand the aetiology of diseases associated with splicing defects, such as retinosa pigmentosum and cancer.

  10. SA1 binds directly to DNA through its unique AT-hook to promote sister chromatid cohesion at telomeres.

    Science.gov (United States)

    Bisht, Kamlesh K; Daniloski, Zharko; Smith, Susan

    2013-08-01

    Sister chromatid cohesion relies on cohesin, a complex comprising a tri-partite ring and a peripheral subunit Scc3, which is found as two related isoforms SA1 and SA2 in vertebrates. There is a division of labor between the vertebrate cohesin complexes; SA1-cohesin is required at telomeres and SA2-cohesin at centromeres. Depletion of SA1 has dramatic consequences for telomere function and genome integrity, but the mechanism by which SA1-cohesin mediates cohesion at telomeres is not well understood. Here we dissect the individual contribution of SA1 and the ring subunits to telomere cohesion and show that telomeres rely heavily on SA1 and to a lesser extent on the ring for cohesion. Using chromatin immunoprecipitation we show that SA1 is highly enriched at telomeres, is decreased at mitosis when cohesion is resolved, and is increased when cohesion persists. Overexpression of SA1 alone was sufficient to induce cohesion at telomeres, independent of the cohesin ring and dependent on its unique (not found in SA2) N-terminal domain, which we show binds to telomeric DNA through an AT-hook motif. We suggest that a specialized cohesion mechanism may be required to accommodate the high level of DNA replication-associated repair at telomeres.

  11. Heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Craig, L.B.; Farma, A.J.

    1987-01-06

    This invention concerns a heat exchanger as used in a space heater, of the type in which hot exhaust gases transfer heat to water or the like flowing through a helical heat exchange coil. A significant improvement to the efficiency of the heat exchange occurring between the air and water is achieved by using a conduit for the water having external helical fluting such that the hot gases circulate along two paths, rather than only one. A preferred embodiment of such a heat exchanger includes a porous combustion element for producing radiant heat from a combustible gas, surrounded by a helical coil for effectively transferring the heat in the exhaust gas, flowing radially from the combustion element, to the water flowing through the coil. 4 figs.

  12. Induction of genomic instability in TK6 human lymphoblasts exposed to 137Cs gamma radiation: comparison to the induction by exposure to accelerated 56Fe particles

    Science.gov (United States)

    Evans, Helen H.; Horng, Min-Fen; Ricanati, Marlene; Diaz-Insua, M.; Jordan, Robert; Schwartz, Jeffrey L.

    2003-01-01

    The induction of genomic instability in TK6 human lymphoblasts by exposure to (137)Cs gamma radiation was investigated by measuring the frequency and characteristics of unstable clones isolated approximately 36 generations after exposure. Clones surviving irradiation and control clones were analyzed for 17 characteristics including chromosomal aberrations, growth defects, alterations in response to a second irradiation, and mutant frequencies at the thymidine kinase and Na(+)/K(+) ATPase loci. Putative unstable clones were defined as those that exhibited a significant alteration in one or more characteristics compared to the controls. The frequency and characteristics of the unstable clones were compared in clones exposed to (137)Cs gamma rays or (56)Fe particles. The majority of the unstable clones isolated after exposure to either gamma rays or (56)Fe particles exhibited chromosomal instability. Alterations in growth characteristics, radiation response and mutant frequencies occurred much less often than cytogenetic alterations in these unstable clones. The frequency and complexity of the unstable clones were greater after exposure to (56)Fe particles than to gamma rays. Unstable clones that survived 36 generations after exposure to gamma rays exhibited increases in the incidence of dicentric chromosomes but not of chromatid breaks, whereas unstable clones that survived 36 generations after exposure to (56)Fe particles exhibited increases in both chromatid and chromosome aberrations.

  13. New functions of Ctf18-RFC in preserving genome stability outside its role in sister chromatid cohesion.

    Science.gov (United States)

    Gellon, Lionel; Razidlo, David F; Gleeson, Olive; Verra, Lauren; Schulz, Danae; Lahue, Robert S; Freudenreich, Catherine H

    2011-02-10

    Expansion of DNA trinucleotide repeats causes at least 15 hereditary neurological diseases, and these repeats also undergo contraction and fragility. Current models to explain this genetic instability invoke erroneous DNA repair or aberrant replication. Here we show that CAG/CTG tracts are stabilized in Saccharomyces cerevisiae by the alternative clamp loader/unloader Ctf18-Dcc1-Ctf8-RFC complex (Ctf18-RFC). Mutants in Ctf18-RFC increased all three forms of triplet repeat instability--expansions, contractions, and fragility--with effect over a wide range of allele lengths from 20-155 repeats. Ctf18-RFC predominated among the three alternative clamp loaders, with mutants in Elg1-RFC or Rad24-RFC having less effect on trinucleotide repeats. Surprisingly, chl1, scc1-73, or scc2-4 mutants defective in sister chromatid cohesion (SCC) did not increase instability, suggesting that Ctf18-RFC protects triplet repeats independently of SCC. Instead, three results suggest novel roles for Ctf18-RFC in facilitating genomic stability. First, genetic instability in mutants of Ctf18-RFC was exacerbated by simultaneous deletion of the fork stabilizer Mrc1, but suppressed by deletion of the repair protein Rad52. Second, single-cell analysis showed that mutants in Ctf18-RFC had a slowed S phase and a striking G2/M accumulation, often with an abnormal multi-budded morphology. Third, ctf18 cells exhibit increased Rad52 foci in S phase, often persisting into G2, indicative of high levels of DNA damage. The presence of a repeat tract greatly magnified the ctf18 phenotypes. Together these results indicate that Ctf18-RFC has additional important functions in preserving genome stability, besides its role in SCC, which we propose include lesion bypass by replication forks and post-replication repair.

  14. New functions of Ctf18-RFC in preserving genome stability outside its role in sister chromatid cohesion.

    Directory of Open Access Journals (Sweden)

    Lionel Gellon

    Full Text Available Expansion of DNA trinucleotide repeats causes at least 15 hereditary neurological diseases, and these repeats also undergo contraction and fragility. Current models to explain this genetic instability invoke erroneous DNA repair or aberrant replication. Here we show that CAG/CTG tracts are stabilized in Saccharomyces cerevisiae by the alternative clamp loader/unloader Ctf18-Dcc1-Ctf8-RFC complex (Ctf18-RFC. Mutants in Ctf18-RFC increased all three forms of triplet repeat instability--expansions, contractions, and fragility--with effect over a wide range of allele lengths from 20-155 repeats. Ctf18-RFC predominated among the three alternative clamp loaders, with mutants in Elg1-RFC or Rad24-RFC having less effect on trinucleotide repeats. Surprisingly, chl1, scc1-73, or scc2-4 mutants defective in sister chromatid cohesion (SCC did not increase instability, suggesting that Ctf18-RFC protects triplet repeats independently of SCC. Instead, three results suggest novel roles for Ctf18-RFC in facilitating genomic stability. First, genetic instability in mutants of Ctf18-RFC was exacerbated by simultaneous deletion of the fork stabilizer Mrc1, but suppressed by deletion of the repair protein Rad52. Second, single-cell analysis showed that mutants in Ctf18-RFC had a slowed S phase and a striking G2/M accumulation, often with an abnormal multi-budded morphology. Third, ctf18 cells exhibit increased Rad52 foci in S phase, often persisting into G2, indicative of high levels of DNA damage. The presence of a repeat tract greatly magnified the ctf18 phenotypes. Together these results indicate that Ctf18-RFC has additional important functions in preserving genome stability, besides its role in SCC, which we propose include lesion bypass by replication forks and post-replication repair.

  15. Effect of aging on superovulation efficiency, aneuploidy rates, and sister chromatid cohesion in mice aged up to 15 months.

    Science.gov (United States)

    Merriman, Julie A; Jennings, Phoebe C; McLaughlin, Eileen A; Jones, Keith T

    2012-02-01

    Human eggs are highly aneuploid, with female age being the only known risk factor. Here this aging phenomenon was further studied in Swiss CD1 mice aged between 1 and 15 mo. The mean number of eggs ± SEM recovered from mice following superovulation peaked at 22.5 ± 3.8 eggs/oviduct in 3-mo-old females, decreasing markedly between 6 and 9 mo old, and was only 2.1 ± 0.2 eggs/oviduct by 15 mo. Measurement of aneuploidy in these eggs revealed a low rate, ∼3-4%, in mice aged 1 and 3 mo, rising to 12.5% by 9 mo old and to 37.5% at 12 mo. Fifteen-month-old mice had the highest rate of aneuploidy, peaking at 60%. The in situ chromosome counting technique used here allowed us to measure with accuracy the distance between the kinetochores in the sister chromatids of the eggs analyzed for aneuploidy. We observed that this distance increased in eggs from older females, from 0.38 ± 0.01 μm at 1 mo old to 0.82 ± 0.03 μm by 15 mo. Furthermore, in 3- to 12-mo-old females, aneuploid eggs had significantly larger interkinetochore distances than euploid eggs from the same age, and measurements were similar to eggs from the oldest mice. However, the association between aneuploidy and interkinetochore distance was not observed at the oldest, 15-mo age, despite such measurements being maximal. We conclude that in aging CD1 mice, a reduction in the ovulated egg number precedes a rise in aneuploidy and, furthermore, except at very advanced ages, increased interkinetochore distance is associated with aneuploidy.

  16. Intersection between the regulators of sister chromatid cohesion establishment and maintenance in budding yeast indicates a multi-step mechanism.

    Science.gov (United States)

    Noble, Daniel; Kenna, Margaret A; Dix, Melissa; Skibbens, Robert V; Unal, Elçin; Guacci, Vincent

    2006-11-01

    Sister chromatid cohesion is established during S phase and maintained until anaphase. The cohesin complex (Mcd1p/Scc1p, Smc1p, Smc3p Irr1p/Scc3p in budding yeast) serves a structural role as it is required at all times when cohesion exists. Pds5p colocalizes temporally and spatially with cohesin on chromosomes but is thought to serve as a regulator of cohesion maintenance during mitosis. In contrast, Ctf7p/Eco1p is required during S phase for establishment but is not required during mitosis. Here we provide genetic and biochemical evidence that the pathways of cohesion establishment and maintenance are intimately linked. Our results show that mutants in ctf7 and pds5 are synthetically lethal. Moreover, over-expression of either CTF7 or PDS5 exhibits reciprocal suppression of the other mutant's temperature sensitivity. The suppression by CTF7 is specific for pds5 mutants as CTF7 over-expression increases the temperature sensitivity of an mcd1 mutant but has no effect on smc1 or smc3 mutants. Three additional findings provide new insights into the process of cohesion establishment. First, over-expression of ctf7 alleles deficient in acetylase activity exhibit significantly reduced suppression of the pds5 mutant but exacerbated toxicity to the mcd1 mutant. Second, using chromosome spreads and chromatin immuno-precipitation, we find either cohesin complex or Pds5p chromosomal localization is altered in ctf7 mutants. Finally, biochemical analysis reveals that Ctf7p and Pds5p coimmunoprecipitate, which physically links these regulators of cohesion establishment and maintenance. We propose a model whereby Ctf7p and Pds5p cooperate to facilitate efficient establishment by mediating changes in cohesin complex on chromosomes after its deposition.

  17. Hydrogen exchange

    DEFF Research Database (Denmark)

    Jensen, Pernille Foged; Rand, Kasper Dyrberg

    2016-01-01

    Hydrogen exchange (HX) monitored by mass spectrometry (MS) is a powerful analytical method for investigation of protein conformation and dynamics. HX-MS monitors isotopic exchange of hydrogen in protein backbone amides and thus serves as a sensitive method for probing protein conformation...... and dynamics along the entire protein backbone. This chapter describes the exchange of backbone amide hydrogen which is highly quenchable as it is strongly dependent on the pH and temperature. The HX rates of backbone amide hydrogen are sensitive and very useful probes of protein conformation......, as they are distributed along the polypeptide backbone and form the fundamental hydrogen-bonding networks of basic secondary structure. The effect of pressure on HX in unstructured polypeptides (poly-dl-lysine and oxidatively unfolded ribonuclease A) and native folded proteins (lysozyme and ribonuclease A) was evaluated...

  18. 12. Chromosomal aberrations and sister chromatid exchanges in the symptomatic individuals exposed to arsenic through drinking water in West Bengal, India

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@In the seven districts of West Bengal, India arsenic in ground water has been found to be above the permissible limit. The concentrations of arsenic is ranging from 200-800 (g/l according to latest reports. More than 200,000 people have already shown different types of arsenical skin lesions in these seven districts of West Bengal. It has been regarded as the biggest arsenic calamity in the world. However, there is

  19. Exchange Options

    NARCIS (Netherlands)

    Jamshidian, Farshid

    2007-01-01

    The contract is described and market examples given. Essential theoretical developments are introduced and cited chronologically. The principles and techniques of hedging and unique pricing are illustrated for the two simplest nontrivial examples: the classical Black-Scholes/Merton/Margrabe exchange

  20. International Exchanges

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>On April 1st,2014,CPAPD Deputy Secretary General Ms.Chen Huaifan met with Mr.Djudjuk Juyoto Suntani,President of the World Peace Committee,Indonesia,who headed the delegation,in the CPAPD office.The two sides exchanged views on issues of common concern including cooperation between the two organizations and the inheritance of Chinese culture.

  1. Exchange Options

    NARCIS (Netherlands)

    Jamshidian, F.

    2007-01-01

    The contract is described and market examples given. Essential theoretical developments are introduced and cited chronologically. The principles and techniques of hedging and unique pricing are illustrated for the two simplest nontrivial examples: the classical Black-Scholes/Merton/Margrabe exchange

  2. Lexicographic Path Induction

    DEFF Research Database (Denmark)

    Schürmann, Carsten; Sarnat, Jeffrey

    2009-01-01

    Programming languages theory is full of problems that reduce to proving the consistency of a logic, such as the normalization of typed lambda-calculi, the decidability of equality in type theory, equivalence testing of traces in security, etc. Although the principle of transfinite induction...... an induction principle that combines the comfort of structural induction with the expressive strength of transfinite induction. Using lexicographic path induction, we give a consistency proof of Martin-Löf’s intuitionistic theory of inductive definitions. The consistency of Heyting arithmetic follows directly...

  3. Ion exchange equilibrium constants

    CERN Document Server

    Marcus, Y

    2013-01-01

    Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and

  4. Determination of aminopolycarboxylic acids at ultra-trace levels by means of online coupling ion exchange chromatography and inductively coupled plasma-mass spectrometry with indirect detection via their Pd²⁺-complexes.

    Science.gov (United States)

    Nette, David; Seubert, Andreas

    2015-07-16

    A new indirect IC-ICP-MS method for the determination of aminopolycarboxylic acids in water samples is described. It is based on the addition of an excess of Pd(II) to water samples. The analytes are forced into very strong and negatively charged palladium complexes, separated by ion exchange chromatography and detected by their palladium content, utilizing an on-line coupled ICP-MS. This method is suitable to determine the concentration of 8 aminopolycarboxylic acids (nitrilotriacetic acid (NTA), (2-carboxyethyl) iminodiacetic acid (β-ADA), methylglycinediacetic acid (MGDA), 2-hydroxyethyl) ethylenediamine triacetic acid (HEDTA), diethylene triamine pentaacetic acid (DTPA), ethylendiamine tetraacetic acid (EDTA), 1,3-diaminopropane tetraacetic acid (1,3-PDTA) and 1,2-diaminopropane tetraacetic acid (1,2-PDTA) at the ng kg(-1) level. The method is faster and easier than the established gas chromatography (GC)-method ISO 16588:2002 and up to two orders of magnitude more sensitive than the ion pair chromatography based method of DIN 38413-8. Analytic performance is superior to ISO 16588:2002 and the comparability is good. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Inductive Monitoring System (IMS)

    Data.gov (United States)

    National Aeronautics and Space Administration — IMS: Inductive Monitoring System The Inductive Monitoring System (IMS) is a tool that uses a data mining technique called clustering to extract models of normal...

  6. Inductive situation calculus

    OpenAIRE

    Denecker, Marc; Ternovska, Eugenia

    2004-01-01

    Temporal reasoning has always been a major test case for knowledge representation formalisms. In this paper, we develop an inductive variant of the situation calculus in ED-logic, classical logic extended with inductive definitions. This logic has been proposed recently and is an extension of classical logic. It allows for a uniform representation of various forms of definitions, including monotone inductive definitions and non-monotone forms of inductive definitions such as iterated inductio...

  7. Dynamics of Non-Classical Interval Exchanges

    CERN Document Server

    Gadre, Vaibhav S

    2009-01-01

    Train tracks with a single vertex are a generalization of interval exchange maps. Here, we consider non-classical interval exchanges: complete train tracks with a single vertex. These can be studied as a dynamical system by considering Rauzy induction in this context. This gives a refinement process on the parameter space similar to Kerckhoff's simplicial systems. We show that the refinement process gives an expansion that has a key dynamical property called uniform distortion. We use uniform distortion to prove normality of the expansion. Consequently we prove an analog of Keane's conjecture: almost every non-classical interval exchange is uniquely ergodic.

  8. Determination of aminopolycarboxylic acids at ultra-trace levels by means of online coupling ion exchange chromatography and inductively coupled plasma-mass spectrometry with indirect detection via their Pd{sup 2+}-complexes

    Energy Technology Data Exchange (ETDEWEB)

    Nette, David; Seubert, Andreas, E-mail: seubert@staff.uni-marburg.de

    2015-07-16

    Highlights: • 8 important APCA’s analyzed in one run instead of 3 in the previous method. • Pd{sup 2+} extents the methods applicability to 3 and more dentate amino carboxylic acids. • Separation system optimized for the isocratic determination of important APCA’s. • Thermodynamic stability of APCA–Pd{sup 2+} complexes is higher than for Fe{sup 3+} and In{sup 3+}. • Pd{sup 2+} is kinetically much slower than Fe{sup 3+} and In{sup 3+} and makes the method more rugged. - Abstract: A new indirect IC-ICP-MS method for the determination of aminopolycarboxylic acids in water samples is described. It is based on the addition of an excess of Pd(II) to water samples. The analytes are forced into very strong and negatively charged palladium complexes, separated by ion exchange chromatography and detected by their palladium content, utilizing an on-line coupled ICP-MS. This method is suitable to determine the concentration of 8 aminopolycarboxylic acids (nitrilotriacetic acid (NTA), (2-carboxyethyl) iminodiacetic acid (β-ADA), methylglycinediacetic acid (MGDA), 2-hydroxyethyl) ethylenediamine triacetic acid (HEDTA), diethylene triamine pentaacetic acid (DTPA), ethylendiamine tetraacetic acid (EDTA), 1,3-diaminopropane tetraacetic acid (1,3-PDTA) and 1,2-diaminopropane tetraacetic acid (1,2-PDTA) at the ng kg{sup −1} level. The method is faster and easier than the established gas chromatography (GC)-method ISO 16588:2002 [1] and up to two orders of magnitude more sensitive than the ion pair chromatography based method of DIN 38413-8. Analytic performance is superior to ISO 16588:2002 and the comparability is good.

  9. Optimization of an anion-exchange high performance liquid chromatography-inductively coupled plasma-mass spectrometric method for the speciation analysis of oxyanion-forming metals and metalloids in leachates from cement-based materials.

    Science.gov (United States)

    Mulugeta, Mesay; Wibetoe, Grethe; Engelsen, Christian J; Lund, Walter

    2010-10-01

    A method was developed for the speciation analysis of the oxyanions of As(III), As(V), Cr(VI), Mo(VI), Sb(III), Sb(V), Se(IV), Se(VI) and V(V) in leachates from cement-based materials, based on anion-exchange HPLC coupled with ICP-MS. The method was optimized in a two-step multivariate approach: the effect of sample pH and mobile phase composition on resolution, peak symmetry and analysis time was studied. Optimum conditions were then identified for the significant experimental factors by studying their interdependence. A mobile phase composition of 20 mM ammonium nitrate, 50 mM ammonium tartrate and pH 9.5 was found to be a compromise optimum for the separation of the target analytes using isocratic elution. The optimum condition provided separation of the analytes in less than 6 min, at a mobile phase flow rate of 1.0 mL/min. The signal intensities of the analytes were improved by adding 1% methanol to the mobile phase. The limit of detection of the method was in the range 0.2-2.2 μg/L for the various species. The effect of sample constituents was studied using spiked concrete leachates. The method was used to determine the target oxyanionic species in leachates generated from a concrete material in the pH range 3.5-12.4; CrO(4)(2-), MoO(4)(2-) and VO(4)(3-) were detected in most of the leachates.

  10. Hypotheses and Inductive Predictions

    NARCIS (Netherlands)

    ROMEYN, J.-W.

    2008-01-01

    ABSTRACT. This paper studies the use of hypotheses schemes in generating inductive predictions. After discussing Carnap–Hintikka inductive logic, hypotheses schemes are defined and illustrated with two partitions. One partition results in the Carnapian continuum of inductive methods, the other resul

  11. Hypotheses and Inductive Predictions

    NARCIS (Netherlands)

    ROMEYN, J.-W.

    2008-01-01

    ABSTRACT. This paper studies the use of hypotheses schemes in generating inductive predictions. After discussing Carnap–Hintikka inductive logic, hypotheses schemes are defined and illustrated with two partitions. One partition results in the Carnapian continuum of inductive methods, the other resul

  12. Inductive Reasoning and Writing

    Science.gov (United States)

    Rooks, Clay; Boyd, Robert

    2003-01-01

    Induction, properly understood, is not merely a game, nor is it a gimmick, nor is it an artificial way of explaining an element of reasoning. Proper understanding of inductive reasoning--and the various types of reasoning that the authors term inductive--enables the student to evaluate critically other people's writing and enhances the composition…

  13. International Exchanges

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    On October 12,2015,Mr.Zhu Rui,CPAPD Secretary General,chaired informal discussions with U.S.young experts and scholars on arms control and non-proliferation.The two sides exchanged views on international arms control,disarmament,non-proliferation and nuclear security,etc.During October 12 to 16,2015,at the invitation of the CPAPD,a four-member delegation from the Vietnam Peace Committee headed by its Vice-President Ms.Nguyen Thi Hoang Van

  14. Induction machine handbook

    CERN Document Server

    Boldea, Ion

    2002-01-01

    Often called the workhorse of industry, the advent of power electronics and advances in digital control are transforming the induction motor into the racehorse of industrial motion control. Now, the classic texts on induction machines are nearly three decades old, while more recent books on electric motors lack the necessary depth and detail on induction machines.The Induction Machine Handbook fills industry's long-standing need for a comprehensive treatise embracing the many intricate facets of induction machine analysis and design. Moving gradually from simple to complex and from standard to

  15. Segmented heat exchanger

    Science.gov (United States)

    Baldwin, Darryl Dean; Willi, Martin Leo; Fiveland, Scott Byron; Timmons, Kristine Ann

    2010-12-14

    A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

  16. The effect of temperature on photosynthetic induction under fluctuating light in Chrysanthemum morifolium

    DEFF Research Database (Denmark)

    Ozturk, Isik; Ottosen, Carl-Otto; Ritz, Christian

    2013-01-01

    to 35 A degrees C. The interaction effect of PAR and temperature on induction state was not significant. The rate of photosynthetic induction and the time required at which the induction reached its 90 % value (t (90)) was influenced by PAR significantly. The light history of a leaf had a significant......The photosynthetic response was investigated on Chrysanthemum morifolium under dynamic light conditions in the 20-35 A degrees C temperature range to evaluate the effect of climatic variables on photosynthetic induction. The plant material was grown under uniform, controlled conditions and its gas...... exchange was analyzed. The gas exchange measurements were used to investigate the rate of induction, momentary induction state, and the opening of stomata. At the varying temperature ranges and under dynamic light conditions, C. morifolium reached a quasi-steady-state induction equilibrium (ISeq...

  17. Drosophila TDP-43 RNA-Binding Protein Facilitates Association of Sister Chromatid Cohesion Proteins with Genes, Enhancers and Polycomb Response Elements.

    Directory of Open Access Journals (Sweden)

    Amanda Swain

    2016-09-01

    Full Text Available The cohesin protein complex mediates sister chromatid cohesion and participates in transcriptional control of genes that regulate growth and development. Substantial reduction of cohesin activity alters transcription of many genes without disrupting chromosome segregation. Drosophila Nipped-B protein loads cohesin onto chromosomes, and together Nipped-B and cohesin occupy essentially all active transcriptional enhancers and a large fraction of active genes. It is unknown why some active genes bind high levels of cohesin and some do not. Here we show that the TBPH and Lark RNA-binding proteins influence association of Nipped-B and cohesin with genes and gene regulatory sequences. In vitro, TBPH and Lark proteins specifically bind RNAs produced by genes occupied by Nipped-B and cohesin. By genomic chromatin immunoprecipitation these RNA-binding proteins also bind to chromosomes at cohesin-binding genes, enhancers, and Polycomb response elements (PREs. RNAi depletion reveals that TBPH facilitates association of Nipped-B and cohesin with genes and regulatory sequences. Lark reduces binding of Nipped-B and cohesin at many promoters and aids their association with several large enhancers. Conversely, Nipped-B facilitates TBPH and Lark association with genes and regulatory sequences, and interacts with TBPH and Lark in affinity chromatography and immunoprecipitation experiments. Blocking transcription does not ablate binding of Nipped-B and the RNA-binding proteins to chromosomes, indicating transcription is not required to maintain binding once established. These findings demonstrate that RNA-binding proteins help govern association of sister chromatid cohesion proteins with genes and enhancers.

  18. Inductive Logic and Statistics

    NARCIS (Netherlands)

    Romeijn, J. -W.

    2009-01-01

    This chapter concerns inductive logic in relation to mathematical statistics. I start by introducing a general notion of probabilistic induc- tive inference. Then I introduce Carnapian inductive logic, and I show that it can be related to Bayesian statistical inference via de Finetti's representatio

  19. Progress in Induction Linacs

    Energy Technology Data Exchange (ETDEWEB)

    Caporaso, G J

    2000-09-27

    This presentation will be a broad survey of progress in induction technology over the past four years. Much work has been done on accelerators for hydrodynamic test radiography and other applications. Solid-state pulsers have been developed which can provide unprecedented flexibility and precision in pulse format and accelerating voltage for both ion and electron induction machines. Induction linacs can now be built which can operate with MHz repetition rates. Solid-state technology has also made possible the development of fast kickers for precision control of high current beams. New insulator technology has been developed which will improve conventional induction linacs in addition to enabling a new class of high gradient induction linacs.

  20. Inductance loop and partial

    CERN Document Server

    Paul, Clayton R

    2010-01-01

    "Inductance is an unprecedented text, thoroughly discussing "loop" inductance as well as the increasingly important "partial" inductance. These concepts and their proper calculation are crucial in designing modern high-speed digital systems. World-renowned leader in electromagnetics Clayton Paul provides the knowledge and tools necessary to understand and calculate inductance." "With the present and increasing emphasis on high-speed digital systems and high-frequency analog systems, it is imperative that system designers develop an intimate understanding of the concepts and methods in this book. Inductance is a much-needed textbook designed for senior and graduate-level engineering students, as well as a hands-on guide for working engineers and professionals engaged in the design of high-speed digital and high-frequency analog systems."--Jacket.

  1. Handbook on heat exchangers

    Science.gov (United States)

    Bazhan, Pavel I.; Kanevets, Georgii E.; Seliverstov, Vladimir M.

    Essential data on heat exchange equipment used in ship, locomotive, automotive, and aircraft powerplants are presented in a systematic manner. The data cover the principal types and technical and performance characteristics of heat exchangers, fundamentals of the theory of heat exchange, calculation of heat transfer coefficients for different types of heat exchange apparatus, optimization of heat exchangers, computer-aided design of heat exchange equipment, testing techniques, and test result processing.

  2. Totalization Data Exchange (TDEX)

    Data.gov (United States)

    Social Security Administration — The Totalization Data Exchange (TDEX) process is an exchange between SSA and its foreign country partners to identify deaths of beneficiaries residing abroad. The...

  3. Exchange frequency in replica exchange molecular dynamics

    Science.gov (United States)

    Sindhikara, Daniel; Meng, Yilin; Roitberg, Adrian E.

    2008-01-01

    The effect of the exchange-attempt frequency on sampling efficiency is studied in replica exchange molecular dynamics (REMD). We show that sampling efficiency increases with increasing exchange-attempt frequency. This conclusion is contrary to a commonly expressed view in REMD. Five peptides (1-21 residues long) are studied with a spectrum of exchange-attempt rates. Convergence rates are gauged by comparing ensemble properties between fixed length test REMD simulations and longer reference simulations. To show the fundamental correlation between exchange frequency and convergence time, a simple model is designed and studied, displaying the same basic behavior of much more complex systems.

  4. Formation of DNA adducts and induction of mutagenic effects in rats following 4 weeks inhalation exposure to ethylene oxide as a basis for cancer risk assessment.

    Science.gov (United States)

    van Sittert, N J; Boogaard, P J; Natarajan, A T; Tates, A D; Ehrenberg, L G; Törnqvist, M A

    2000-01-17

    Ethylene oxide (EO) is mutagenic in various in vitro and in vivo test systems and carcinogenic in rodents. EO forms different adducts upon reaction with DNA, N7-(2-hydroxyethyl)guanine (N7-HEG) being the main adduct. The major objectives of this study were: (a) to determine the formation and persistence of N7-HEG adducts in liver DNA of adult male rats exposed to 0, 50, 100 and 200 ppm by inhalation (4 weeks, 5 days/week, 6 h/day) and (b) to assess dose-response relationships for Hprt gene mutations and various types of chromosomal changes in splenic lymphocytes.N7-HEG adducts were measured 5, 21, 35 and 49 days after cessation of exposure. By extrapolation, the mean concentrations of N7-HEG immediately after cessation of exposure ('day 0') to 50, 100 and 200 ppm were calculated as 310, 558 and 1202 adducts/10(8) nucleotides, respectively, while the mean concentration in control rats was 2.6 adducts/10(8) nucleotides. At 49 days, N7-HEG values had returned close to background levels. The mean levels of N-(2-hydroxyethylvaline) adducts in haemoglobin were also determined and amounted 61.7, 114 and 247 nmol/g globin, respectively. Statistically significant linear relationships were found between mean N7-HEG levels ('day 0') and Hprt mutant frequencies at expression times 21/22 and 49/50 days and between mean N7-HEG ('day 0') and sister-chromatid exchanges (SCEs) or high frequency cells (HFC) measured 5 days post-exposure. At day 21 post-exposure, SCEs and HFCs in-part persisted and were significantly correlated with persistent N7-HEG adducts. No statistically significant dose effect relationships were observed for induction of micronuclei, nor for chromosome breaks or translocations. In conclusion, this study indicates that following sub-chronic exposure, EO is only weakly mutagenic in adult rats. Using the data of this study to predict cancer risk in man resulting from low level EO exposures in conjunction with other published data, i.e., those on (a) genotoxic

  5. Direct reading inductance meter

    Science.gov (United States)

    Kolby, R. B. (Inventor)

    1977-01-01

    A direct reading inductance meter comprised of a crystal oscillator and an LC tuned oscillator is presented. The oscillators function respectively to generate a reference frequency, f(r), and to generate an initial frequency, f(0), which when mixed produce a difference equal to zero. Upon connecting an inductor of small unknown value in the LC circuit to change its resonant frequency to f(x), a difference frequency (f(r)-f(x)) is produced that is very nearly a linear function of the inductance of the inductor. The difference frequency is measured and displayed on a linear scale in units of inductance.

  6. Induction motor control design

    CERN Document Server

    Marino, Riccardo; Verrelli, Cristiano M

    2010-01-01

    ""Nonlinear and Adaptive Control Design for Induction Motors"" is a unified exposition of the most important steps and concerns in the design of estimation and control algorithms for induction motors. A single notation and modern nonlinear control terminology is used to make the book accessible to readers who are not experts in electric motors at the same time as giving a more theoretical control viewpoint to those who are. In order to increase readability, the book concentrates on the induction motor, eschewing the much more complex and less-well-understood control of asynchronous motors. The

  7. Properties of inductive reasoning.

    Science.gov (United States)

    Heit, E

    2000-12-01

    This paper reviews the main psychological phenomena of inductive reasoning, covering 25 years of experimental and model-based research, in particular addressing four questions. First, what makes a case or event generalizable to other cases? Second, what makes a set of cases generalizable? Third, what makes a property or predicate projectable? Fourth, how do psychological models of induction address these results? The key results in inductive reasoning are outlined, and several recent models, including a new Bayesian account, are evaluated with respect to these results. In addition, future directions for experimental and model-based work are proposed.

  8. Electromagnetic induction in Australia

    Science.gov (United States)

    Lilley, F. E. M.

    Electromagnetic induction at the terrestrial surface is a general and ubiquitous process. This note, which covers research on the subject in Australia, reflects the writer's own interest and refers particularly to induction by natural source fields in the period range of 1 minute to 1 day.Such source fields arise external to Earth, in the ionosphere and beyond, in the magnetosphere. The process of electromagnetic induction by these fields involves the flow through Earth of tens of thousands of amperes, over scale lengths of thousands of kilometers.

  9. Making Mathematical Induction Meaningful

    Science.gov (United States)

    Hirsch, Christian R.

    1976-01-01

    The author argues that the "least number principle" (well-ordering for positive integers) is more intuitively acceptable to high school students than mathematical induction which can be derived from it. (SD)

  10. Thermal kinetic inductance detector

    Energy Technology Data Exchange (ETDEWEB)

    Cecil, Thomas; Gades, Lisa; Miceli, Antonio; Quaranta, Orlando

    2016-12-20

    A microcalorimeter for radiation detection that uses superconducting kinetic inductance resonators as the thermometers. The detector is frequency-multiplexed which enables detector systems with a large number of pixels.

  11. Induction heating coupler

    Science.gov (United States)

    Fox, Robert L. (Inventor); Copeland, Carl E. (Inventor); Swaim, Robert J. (Inventor); Coultrip, Robert H. (Inventor); Johnston, David F. (Inventor); Phillips, W. Morris (Inventor); Johnson, Samuel D. (Inventor); Dinkins, James R. (Inventor); Buckley, John D. (Inventor)

    1994-01-01

    An induction heating device includes a handle having a hollow interior and two opposite ends, a wrist connected to one end of the handle, a U-shaped pole piece having two spaced apart ends, a tank circuit including an induction coil wrapped around the pole piece and a capacitor connected to the induction coil, a head connected to the wrist and including a housing for receiving the U-shaped pole piece, the two spaced apart ends of the pole piece extending outwardely beyond the housing, and a power source connected to the tank circuit. When the tank circuit is energized and a susceptor is placed in juxtaposition to the ends of the U-shaped pole piece, the susceptor is heated by induction heating due to magnetic flux passing between the two ends of the pole piece.

  12. Unification By Induction

    CERN Document Server

    Adewole, A I A

    2001-01-01

    We show that the problem of unifying electromagnetism with gravity has an elegant solution in classical physics through the phenomenon of induction. By studying the way that induction leads to the formation of electromagnetic fields, we identify the classical field equations which the unified field must satisfy and a corresponding set of constitutive equations for the medium sustaining the field. The unification problem is then reduced to the problem of finding the exact form of these constitutive equations for different media by experiments.

  13. Induction of the Proepicardium.

    Science.gov (United States)

    Maya-Ramos, Lisandro; Cleland, James; Bressan, Michael; Mikawa, Takashi

    2013-09-01

    The proepicardium is a transient extracardiac embryonic tissue that gives rise to the epicardium and a number of coronary vascular cell lineages. This important extracardiac tissue develops through multiple steps of inductive events, from specification of multiple cell lineages to morphogenesis. This article will review our current understanding of inductive events involved in patterning of the proepicardium precursor field, specification of cell types within the proepicardium, and their extension and attachment to the heart.

  14. Induction of the Proepicardium

    Directory of Open Access Journals (Sweden)

    Takashi Mikawa

    2013-07-01

    Full Text Available The proepicardium is a transient extracardiac embryonic tissue that gives rise to the epicardium and a number of coronary vascular cell lineages. This important extracardiac tissue develops through multiple steps of inductive events, from specification of multiple cell lineages to morphogenesis. This article will review our current understanding of inductive events involved in patterning of the proepicardium precursor field, specification of cell types within the proepicardium and their extension and attachment to the heart.

  15. Diophantine Correct Open Induction

    CERN Document Server

    Raffer, Sidney

    2010-01-01

    We give an induction-free axiom system for diophantine correct open induction. We relate the problem of whether a finitely generated ring of Puiseux polynomials is diophantine correct to a problem about the value-distribution of a tuple of semialgebraic functions with integer arguments. We use this result, and a theorem of Bergelson and Leibman on generalized polynomials, to identify a class of diophantine correct subrings of the field of descending Puiseux series with real coefficients.

  16. Induction Heating Systems

    Science.gov (United States)

    1991-01-01

    Induction heating technology, a magnetic non-deforming process, was developed by Langley researchers to join plastic and composite components in space. Under NASA license, Inductron Corporation uses the process to produce induction heating systems and equipment for numerous applications. The Torobonder, a portable system, comes with a number of interchangeable heads for aircraft repair. Other developments are the E Heating Head, the Toroid Joining Gun, and the Torobrazer. These products perform bonding applications more quickly, safely and efficiently than previous methods.

  17. Determination of gold,platinum and palladium in geological samples by inductively coupled plasma mass spectrometry after concentration with 717 anion exchange resin%717阴离子交换树脂富集-电感耦合等离子体质谱法测定地质样品中痕量金铂钯

    Institute of Scientific and Technical Information of China (English)

    李丹; 王锝; 李彪

    2011-01-01

    The adsorption property and separation conditions of 717 anion exchange resin to trace gold,platinum and palladium in geological samples were studied. The sample was dissolved with HCl+ aqua regia under heating in water bath. Only Mo in dissolved elements had interference with the determination of Pd, which could be eliminated using mathematical formula correction. When the flow rate of eluent was 2 mL/min, the enrichment effects of gold, platinum and palladium in 5 % HCl medium reached its best, and the recoveries were close to 100 %. After correcting the influence of coexisting ions, the national first-class certified reference materials were determined by inductively coupled plasma mass spectrometry, and the difference between determination results and certified values was satisfactory. The detection limit of method were 0. 6 ng/mL, 0. 5 ng/mL and 0. 7 ng/mL for Pd, Pt and Au, respectively. Five random geological samples were analyzed by this method in comparison with NiS fire assay-ICP-MS method. The determination results were consistent. The results of two methods were checked by double sample's variance F test, and there was no significant difference.%研究了717型阴离子交换树脂对地质样品中痕量金、铂、钯的吸附性能及分离条件.采用水浴加热,HCl+王水的方式溶解样品,溶出的干扰元素只有Mo对Pd的测定造成干扰,采用数学公式校正可消除此干扰.在5%的HCl介质中,洗脱剂流速为2 mL/min时,金、铂、钯的富集效果最佳,回收率接近100%.经对共存离子影响的校正,用电感耦合等离子体质谱法测定国家一级标准物质,其结果较认定值不超差.方法检出限为Pd 0.6 ng/mL,Pt 0.5ng/mL,Au 0.7ng/mL.随机选取5个地质样品用本法进行分析,同时与硫镍试金-ICP-MS法进行比较,结果一致.两组结果经双样本方差F检验,无显著性差异.

  18. Refining Inductive Types

    CERN Document Server

    Atkey, Robert; Ghani, Neil

    2012-01-01

    Dependently typed programming languages allow sophisticated properties of data to be expressed within the type system. Of particular use in dependently typed programming are indexed types that refine data by computationally useful information. For example, the N-indexed type of vectors refines lists by their lengths. Other data types may be refined in similar ways, but programmers must produce purpose-specific refinements on an ad hoc basis, developers must anticipate which refinements to include in libraries, and implementations must often store redundant information about data and their refinements. In this paper we show how to generically derive inductive characterisations of refinements of inductive types, and argue that these characterisations can alleviate some of the aforementioned difficulties associated with ad hoc refinements. Our characterisations also ensure that standard techniques for programming with and reasoning about inductive types are applicable to refinements, and that refinements can the...

  19. Ab initio Calculation of Intermolecular Dispersion Energy and Induction Energy of Nitramide Dimer

    Institute of Scientific and Technical Information of China (English)

    SONG, Hua-Jie(宋华杰); XIAO, He-Ming(肖鹤鸣); DONG, Hai-Shan(董海山); HUANG, Yi-Gang(黄奕刚); LONG, Xin-Ping(龙新平); TANG, Yei-Peng(汤业鹏)

    2004-01-01

    The dispersion energies, induction energies and their exchange counterparts (exchange-dispersion and exchange-induction energies) between two interacting nitramide molecules at several separations are derived based upon symmetry-adapted perturbation theory (SAPT). The results show that (1) the effect of intramonomer electron correlation on dispersion energies and induction energies for nitramide dimer system is remarkable especially in the region near the van der Waals minimum distance (0.42 nm). (2) At smaller separations the dispersion energies and the induction energies are largely quenched by their exchange counterparts, and this case in induction interaction is much more remarkable than in dispersion interaction. (3) Since at shorter distances there exists the strong short-range interaction due to electron transfer which quickly decays and even disappears at larger separations, the two different R-dependency formulae of induction energies were found: one is ca. R-12.7 at short distances, and the other ca. R-7.0 at large separations. The latter R-dependency is similar to that (ca. R-7.2) of dispersion. (4) In the case of strong polar interaction existing in nitramide dimer, the "true" induction correlation terms of higher order than tE(22)ind may be important.

  20. VT Telephone Exchange Boundaries

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The UtilityTelecom_EXCHANGE represents Vermont Telephone Exchange boundaries as defined by the VT Public Service Board. The original data was...

  1. Indiana Health Information Exchange

    Science.gov (United States)

    The Indiana Health Information Exchange is comprised of various Indiana health care institutions, established to help improve patient safety and is recognized as a best practice for health information exchange.

  2. Modeling Induction Motor Imbalances

    DEFF Research Database (Denmark)

    Armah, Kabenla; Jouffroy, Jerome; Duggen, Lars

    2016-01-01

    This paper gives a study into the development of a generalized model for a three-phase induction motor that offers flexibility of simulating balanced and unbalanced parameter scenarios. By analyzing the interaction of forces within the motor, we achieve our main objective of deriving the system...

  3. Learning and Inductive Inference

    Science.gov (United States)

    1982-07-01

    is also a paradigm example of induction as discussed by philosophers ( Carnap , 1950). Data compression is of practical value for storage and...IBelser, A. 0. Hlolzman, and A. Kent (Eds.., Eneyclopedia of computer science and technology (Vol. II). New York: Marcel Dekker, 24 51. " Carnap , R. 1950

  4. Iteration, Not Induction

    Science.gov (United States)

    Dobbs, David E.

    2009-01-01

    The main purpose of this note is to present and justify proof via iteration as an intuitive, creative and empowering method that is often available and preferable as an alternative to proofs via either mathematical induction or the well-ordering principle. The method of iteration depends only on the fact that any strictly decreasing sequence of…

  5. Teaching Mathematical Induction I.

    Science.gov (United States)

    Dubinsky, Ed

    1986-01-01

    A novel approach to teaching mathematical induction was used, based on a Piagetian theory of learning abstract mathematical concepts in which the learner uses reflective abstraction to construct new schemas out of old ones. Computer experiences are used to induce students to make the appropriate reflective abstractions. (MNS)

  6. Using Continuity Induction

    Science.gov (United States)

    Hathaway, Dan

    2011-01-01

    Here is a technique for proving the fundamental theorems of analysis that provides a unified way to pass from local properties to global properties on the real line, just as ordinary induction passes from local implication (if true for "k", the theorem is true for "k" + 1) to a global conclusion in the natural numbers.

  7. Training in Inductive Reasoning.

    Science.gov (United States)

    Tomic, Welko

    This study investigated the effects of K. J. Klauer's (1989) inductive reasoning training program of teaching children. Effects of training and the range of transfer of the training were assessed. The subjects were 34 third-grade Dutch children of average ability, matched on age, sex, and IQ. Children from the training condition (N=17) received…

  8. Decision Procedures for Proving Inductive Theorems without Induction

    OpenAIRE

    Aoto, Takahito; Stratulat, Sorin

    2014-01-01

    International audience; Automated inductive reasoning for term rewriting has been extensively studied in the literature. Classes of equations and term rewriting systems (TRSs) with decidable inductive validity have been identified and used to automatize the inductive reasoning. We give procedures for deciding the inductive validity of equations in some standard TRSs on natural numbers and lists. Contrary to previous decidability results, our procedures can automatically decide without involvi...

  9. Approximate strip exchanging.

    Science.gov (United States)

    Roy, Swapnoneel; Thakur, Ashok Kumar

    2008-01-01

    Genome rearrangements have been modelled by a variety of primitives such as reversals, transpositions, block moves and block interchanges. We consider such a genome rearrangement primitive Strip Exchanges. Given a permutation, the challenge is to sort it by using minimum number of strip exchanges. A strip exchanging move interchanges the positions of two chosen strips so that they merge with other strips. The strip exchange problem is to sort a permutation using minimum number of strip exchanges. We present here the first non-trivial 2-approximation algorithm to this problem. We also observe that sorting by strip-exchanges is fixed-parameter-tractable. Lastly we discuss the application of strip exchanges in a different area Optical Character Recognition (OCR) with an example.

  10. Chromatin dynamics during cell cycle mediate conversion of DNA damage into chromatid breaks and affect formation of chromosomal aberrations: Biological and clinical significance

    Energy Technology Data Exchange (ETDEWEB)

    Terzoudi, Georgia I.; Hatzi, Vasiliki I. [Institute of Radioisotopes and Radiodiagnostic Products, National Centre for Scientific Research ' Demokritos' , 15310 Ag. Paraskevi Attikis, Athens (Greece); Donta-Bakoyianni, Catherine [Oral Diagnosis and Radiology, University of Athens Dental School, Athens (Greece); Pantelias, Gabriel E., E-mail: gabriel@ipta.demokritos.gr [Institute of Radioisotopes and Radiodiagnostic Products, National Centre for Scientific Research ' Demokritos' , 15310 Ag. Paraskevi Attikis, Athens (Greece)

    2011-06-03

    The formation of diverse chromosomal aberrations following irradiation and the variability in radiosensitivity at different cell-cycle stages remain a long standing controversy, probably because most of the studies have focused on elucidating the enzymatic mechanisms involved using simple DNA substrates. Yet, recognition, processing and repair of DNA damage occur within the nucleoprotein complex of chromatin which is dynamic in nature, capable of rapid unfolding, disassembling, assembling and refolding. The present work reviews experimental work designed to investigate the impact of chromatin dynamics and chromosome conformation changes during cell-cycle in the formation of chromosomal aberrations. Using conventional cytogenetics and premature chromosome condensation to visualize interphase chromatin, the data presented support the hypothesis that chromatin dynamic changes during cell-cycle are important determinants in the conversion of sub-microscopic DNA lesions into chromatid breaks. Consequently, the type and yield of radiation-induced chromosomal aberrations at a given cell-cycle-stage depends on the combined effect of DNA repair processes and chromatin dynamics, which is cell-cycle-regulated and subject to up- or down-regulation following radiation exposure or genetic alterations. This new hypothesis is used to explain the variability in radiosensitivity observed at various cell-cycle-stages, among mutant cells and cells of different origin, or among different individuals, and to revisit unresolved issues and unanswered questions. In addition, it is used to better understand hypersensitivity of AT cells and to provide an improved predictive G2-assay for evaluating radiosensitivity at individual level. Finally, experimental data at single cell level obtained using hybrid cells suggest that the proposed hypothesis applies only to the irradiated component of the hybrid.

  11. Measurement of Self-Inductance.

    Science.gov (United States)

    Mak, S. Y.; Tao, P. K.

    1988-01-01

    Discusses four different methods for measuring self-inductance based on the definition of inductance, the alternative definition, phase difference and LC resonance. Provides circuit diagrams and typical oscilloscope traces. (YP)

  12. Phase-sensitive detection of both inductive and non-inductive ac voltages in ferromagnetic resonance

    Science.gov (United States)

    Weiler, Mathias; Shaw, Justin M.; Nembach, Hans T.; Schoen, Martin A.; Boone, Carl T.; Silva, Thomas J.

    2014-03-01

    Spin pumping causes significant damping in ultrathin ferromagnetic/normal metal (NM) multilayers via spin-current generation of both dc and ac character in the NM system. While the nonlinear dc component has been investigated in detail by utilization of the inverse spin Hall effect (iSHE) in NMs, much less is known about the linear ac component that is presumably much larger in the small-excitation limit. We measured generated ac voltages in a wide variety of Permalloy/NM multilayers via vector-network-analyzer ferromagnetic resonance. We employ a custom, impedance-matched, broadband microwave coupler that features a ferromagnetic thin film reference resonator to accurately compare ac voltage amplitudes and phases between varieties of multilayers. By use of the fact that inductive and ac iSHE signals are phase-shifted by π/2, we find that inductive signals are major contributors in all investigated samples. It is only by comparison of the phase and amplitude of the recorded ac voltages between multiple samples that we can extract the non-inductive contributions due to spin-currents. Voltages due to the ac iSHE in Permalloy(10nm)/platinum(5nm) bilayers are weaker than inductive signals, in agreement with calculations based upon recent theoretical predictions. M.W. acknowledges financial support by the German Academic Exchange service (DAAD).

  13. Determination of Lead Isotopic Ratios in Corals by Anion Exchange Resin Technique and High Resolution Inductively Coupled Plasma Mass Spectrometry%阴离子交换树脂分离富集/电感耦合等离子体质谱测定珊瑚中铅的同位素组成

    Institute of Scientific and Technical Information of China (English)

    戴洁; 瞿建国; 张经

    2012-01-01

    在自制微型离子交换柱的基础上,建立了阴离子交换树脂AG1-X8分离富集珊瑚中痕量元素Pb的前处理方法,并使用高分辨电感耦合等离子体质谱( HR - ICP - MS)测定了海南橙黄滨珊瑚(porites lutea)样品中的Pb同位素比值.从全程空白值、洗脱曲线、回收率和基体分离情况等方面考察了不同洗脱剂的洗脱效果,结果表明,采用0.50 mol/L HNO3时的洗脱效果最好,方法的全程空白值为18 pg,Pb的回收率为99.6%,在洗脱过程中无拖尾现象,且能与Ca、Sr、Mg、Fe、Mn、Zn、Ba和U等珊瑚中的基体元素成功分离,对上述基体元素的去除率均能达到99.8%以上.使用该方法测得海南珊瑚样品中的207pb/206 Pb、208Pb/206Pb比值分别为0.850 5、2.087 0,相对标准偏差(RSDs,n=21)分别为0.12%和0.11%.该法质量控制良好,表明建立的AG1-X8阴离子交换树脂分离富集/HR - ICP - MS测定珊瑚中Pb的同位素组成的方法可靠,可推广应用于其它复杂样品中铅同位素组成的测定.%A pretreatment method to enrich trace element Pb in corals was established with AG1-X8 anion exchange resin and self-made PTFE micro column, then Pb isotopic ratios in Hainan corals (porites lutea) in China was measured by high-resolution inductively coupled plasma mass spectrometry (HR - ICP - MS). Several parameters including procedural blank, elution curve, Pb recovery and matrix separation were compared among four different eluents, and the results showed 0. 50 mol/ L HNO3 was the best eluent, of which the procedural blank was 18 pg, and recovery of Pb was 99. 6% , besides, there was no tailing observed and more than 99. 8% of the matrix elements in corals such as Ca, Sr, Mg, Fe, Mn, U, Ba as well as Zn could be well separated from Pb during the eluting process. After eluted with 0. 50 mol/L HNO3 ,207Pb/206Pb and 208Pb/206Pb in Hainan corals was determined to be 0. 850 5 and 2. 087 0, with RSDs(n =21) of 0. 12% and 0. 11

  14. Mathematical Induction: A Pedagogical Discussion.

    Science.gov (United States)

    Ernest, Paul

    1984-01-01

    Discusses the nature of mathematical induction and what constitutes a correct proof by this method and common misconceptions of induction with recommendations for their remediation. The topic is also analyzed into behavioral skills and subjected to a conceptual analysis. Criteria for analyzing and evaluating textbook treatment of induction are…

  15. Inductive Reasoning: A Training Approach

    Science.gov (United States)

    Klauer, Karl Josef; Phye, Gary D.

    2008-01-01

    Researchers have examined inductive reasoning to identify different cognitive processes when participants deal with inductive problems. This article presents a prescriptive theory of inductive reasoning that identifies cognitive processing using a procedural strategy for making comparisons. It is hypothesized that training in the use of the…

  16. Induction motor control

    Science.gov (United States)

    Hansen, Irving G.

    Electromechanical actuators developed to date have commonly ultilized permanent magnet (PM) synchronous motors. More recently switched reluctance (SR) motors have been advocated due to their robust characteristics. Implications of work which utilized induction motors and advanced control techniques are discussed. When induction motors are operated from an energy source capable of controlling voltages and frequencies independently, drive characteristics are obtained which are superior to either PM or SR motors. By synthesizing the machine frequency from a high-frequency carrier (nominally 20 kHz), high efficiencies, low distortion, and rapid torque response are available. At this time multiple horsepower machine drives were demonstrated, and work is on-going to develop a 20 hp average, 40 hp peak class of aerospace actuators. This effort is based upon high-frequency power distribution and management techniques developed by NASA for Space Station Freedom.

  17. Inductive Supervised Quantum Learning

    Science.gov (United States)

    Monràs, Alex; Sentís, Gael; Wittek, Peter

    2017-05-01

    In supervised learning, an inductive learning algorithm extracts general rules from observed training instances, then the rules are applied to test instances. We show that this splitting of training and application arises naturally, in the classical setting, from a simple independence requirement with a physical interpretation of being nonsignaling. Thus, two seemingly different definitions of inductive learning happen to coincide. This follows from the properties of classical information that break down in the quantum setup. We prove a quantum de Finetti theorem for quantum channels, which shows that in the quantum case, the equivalence holds in the asymptotic setting, that is, for large numbers of test instances. This reveals a natural analogy between classical learning protocols and their quantum counterparts, justifying a similar treatment, and allowing us to inquire about standard elements in computational learning theory, such as structural risk minimization and sample complexity.

  18. Induction motor control

    Science.gov (United States)

    Hansen, Irving G.

    1990-01-01

    Electromechanical actuators developed to date have commonly ultilized permanent magnet (PM) synchronous motors. More recently switched reluctance (SR) motors have been advocated due to their robust characteristics. Implications of work which utilized induction motors and advanced control techniques are discussed. When induction motors are operated from an energy source capable of controlling voltages and frequencies independently, drive characteristics are obtained which are superior to either PM or SR motors. By synthesizing the machine frequency from a high-frequency carrier (nominally 20 kHz), high efficiencies, low distortion, and rapid torque response are available. At this time multiple horsepower machine drives were demonstrated, and work is on-going to develop a 20 hp average, 40 hp peak class of aerospace actuators. This effort is based upon high-frequency power distribution and management techniques developed by NASA for Space Station Freedom.

  19. Inductively commutated coilguns

    Energy Technology Data Exchange (ETDEWEB)

    Mongeau, P.P. (EML Research, Inc., Hudson, MA (US))

    1991-01-01

    In this paper the concept and relevance of power factor is presented in regards to high performance launchers. As the scale of launchers grows and as efforts to improve efficiency continue power factor considerations will become crucial in engineering design and ultimate launcher performance limits. The use of motion induced commutation to improve the power factor are discussed. Various approaches to inductive commutation are presented, including: the brush-commutated 9 MJ Coilgun, the solid state-switched coilgun and the quenchgun.

  20. Inductively commutated coilguns

    Science.gov (United States)

    Mongeau, Peter P.

    1991-01-01

    The concept and relevance of power factor is presented in the context of high-performance launchers. As the scale of launchers grows and efforts to improve efficiency continue, power factor considerations will become crucial in engineering design and ultimate launcher performance limits. The use of motion-induced commutation to improve the power factor are discussed. Various approaches to inductive commutation are presented, including the brush-commutated 9-MJ coilgun, the solid state-switched coilgun, and the quenchgun.

  1. Adaptively Compressed Exchange Operator

    CERN Document Server

    Lin, Lin

    2016-01-01

    The Fock exchange operator plays a central role in modern quantum chemistry. The large computational cost associated with the Fock exchange operator hinders Hartree-Fock calculations and Kohn-Sham density functional theory calculations with hybrid exchange-correlation functionals, even for systems consisting of hundreds of atoms. We develop the adaptively compressed exchange operator (ACE) formulation, which greatly reduces the computational cost associated with the Fock exchange operator without loss of accuracy. The ACE formulation does not depend on the size of the band gap, and thus can be applied to insulating, semiconducting as well as metallic systems. In an iterative framework for solving Hartree-Fock-like systems, the ACE formulation only requires moderate modification of the code, and can be potentially beneficial for all electronic structure software packages involving exchange calculations. Numerical results indicate that the ACE formulation can become advantageous even for small systems with tens...

  2. Laser Processed Heat Exchangers

    Science.gov (United States)

    Hansen, Scott

    2017-01-01

    The Laser Processed Heat Exchanger project will investigate the use of laser processed surfaces to reduce mass and volume in liquid/liquid heat exchangers as well as the replacement of the harmful and problematic coatings of the Condensing Heat Exchangers (CHX). For this project, two scale unit test articles will be designed, manufactured, and tested. These two units are a high efficiency liquid/liquid HX and a high reliability CHX.

  3. Microsoft Exchange 2013 cookbook

    CERN Document Server

    Van Horenbeeck, Michael

    2013-01-01

    This book is a practical, hands-on guide that provides the reader with a number of clear, step-by-step exercises.""Microsoft Exchange 2013 Cookbook"" is targeted at network administrators who deal with the Exchange server in their day-to-day jobs. It assumes you have some practical experience with previous versions of Exchange (although this is not a requirement), without being a subject matter expert.

  4. A taxonomy of inductive problems.

    Science.gov (United States)

    Kemp, Charles; Jern, Alan

    2014-02-01

    Inductive inferences about objects, features, categories, and relations have been studied for many years, but there are few attempts to chart the range of inductive problems that humans are able to solve. We present a taxonomy of inductive problems that helps to clarify the relationships between familiar inductive problems such as generalization, categorization, and identification, and that introduces new inductive problems for psychological investigation. Our taxonomy is founded on the idea that semantic knowledge is organized into systems of objects, features, categories, and relations, and we attempt to characterize all of the inductive problems that can arise when these systems are partially observed. Recent studies have begun to address some of the new problems in our taxonomy, and future work should aim to develop unified theories of inductive reasoning that explain how people solve all of the problems in the taxonomy.

  5. Usable optimistic fair exchange

    OpenAIRE

    Küpçü, Alptekin; Lysyanskaya, A.

    2012-01-01

    Fairly exchanging digital content is an everyday problem. It has been shown that fair exchange cannot be achieved without a trusted third party (called the Arbiter). Yet, even with a trusted party, it is still non-trivial to come up with an efficient solution, especially one that can be used in a p2p file sharing system with a high volume of data exchanged. We provide an efficient optimistic fair exchange mechanism for bartering digital files, where receiving a payment in return for a file (b...

  6. Exchange rate regime choice

    Directory of Open Access Journals (Sweden)

    Beker Emilija

    2006-01-01

    Full Text Available The choice of an adequate exchange rate regime proves to be a highly sensitive field within which the economic authorities present and confirm themselves. The advantages and disadvantages of fixed and flexible exchange rate regimes, which have been quite relativized from the conventional point of view, together with simultaneous, but not synchronized effects of structural and external factors, remain permanently questioned throughout a complex process of exchange rate regime decision making. The paper reflects the attempt of critical identification of the key exchange rate performances with emphasis on continuous non-uniformity and (uncertainty of shelf life of a relevant choice.

  7. Inductively Coupled Augmented Railgun

    CERN Document Server

    Bahder, Thomas B

    2011-01-01

    We derive the non-linear dynamical equations for an augmented electromagnetic railgun, whose augmentation circuit is inductively coupled to the gun circuit. We solve these differential equations numerically using example parameter values. We find a complicated interaction between the augmentation circuit, gun circuit, and mechanical degrees of freedom, leading to a complicated optimization problem. For certain values of parameters, we find that an augmented electromagnetic railgun has an armature kinetic energy that is 42% larger than the same railgun with no augmentation circuit. Optimizing the parameters may lead to further increase in performance.

  8. Low inductance gas switching.

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, Ray; Harjes, Henry Charles III; Wallace, Zachariah; Elizondo, Juan E.

    2007-10-01

    The laser trigger switch (LTS) is a key component in ZR-type pulsed power systems. In ZR, the pulse rise time through the LTS is > 200 ns and additional stages of pulse compression are required to achieve the desired <100 ns rise time. The inductance of the LTS ({approx}500nH) in large part determines the energy transfer time through the switch and there is much to be gained in improving system performance and reducing system costs by reducing this inductance. The current path through the cascade section of the ZR LTS is at a diameter of {approx} 6-inches which is certainly not optimal from an inductance point of view. The LTS connects components of much greater diameter (typically 4-5 feet). In this LDRD the viability of switch concepts in which the diameter of cascade section is greatly increased have been investigated. The key technical question to be answered was, will the desired multi-channel behavior be maintained in a cascade section of larger diameter. This LDRD proceeded in 2 distinct phases. The original plan for the LDRD was to develop a promising switch concept and then design, build, and test a moderate scale switch which would demonstrate the key features of the concept. In phase I, a switch concept which meet all electrical design criteria and had a calculated inductance of 150 nH was developed. A 1.5 MV test switch was designed and fabrication was initiated. The LDRD was then redirected due to budgetary concerns. The fabrication of the switch was halted and the focus of the LDRD was shifted to small scale experiments designed to answer the key technical question concerning multi-channel behavior. In phase II, the Multi-channel switch test bed (MCST) was designed and constructed. The purpose of MCST was to provide a versatile, fast turn around facility for the study the multi-channel electrical breakdown behavior of a ZR type cascade switch gap in a parameter space near that of a ZR LTS. Parameter scans on source impedance, gap tilt, gap spacing and

  9. Induction motor starting current

    Energy Technology Data Exchange (ETDEWEB)

    Arneaud, J.M.; Langman, R.A. [Tasmania Univ., Hobart, TAS (Australia)

    1995-12-31

    Large errors may occur if leakage path saturation is neglected when reduced-voltage test results are used to predict the direct-on-line starting current of induction motors. The results of applying three existing and two new methods for starting current prediction are compared with test data from 52 motors. A quantitative assessment is made of the probable reduction in error that would be achieved by increasing the number of available sets of reduced-voltage, locked rotor test results or by including slot design data. Guidelines are given for selecting an appropriate predictive method. (author). 4 tabs., 1 fig., 6 refs.

  10. Meiosis-specific cohesin component, Stag3 is essential for maintaining centromere chromatid cohesion, and required for DNA repair and synapsis between homologous chromosomes.

    Directory of Open Access Journals (Sweden)

    Jessica Hopkins

    2014-07-01

    Full Text Available Cohesins are important for chromosome structure and chromosome segregation during mitosis and meiosis. Cohesins are composed of two structural maintenance of chromosomes (SMC1-SMC3 proteins that form a V-shaped heterodimer structure, which is bridged by a α-kleisin protein and a stromal antigen (STAG protein. Previous studies in mouse have shown that there is one SMC1 protein (SMC1β, two α-kleisins (RAD21L and REC8 and one STAG protein (STAG3 that are meiosis-specific. During meiosis, homologous chromosomes must recombine with one another in the context of a tripartite structure known as the synaptonemal complex (SC. From interaction studies, it has been shown that there are at least four meiosis-specific forms of cohesin, which together with the mitotic cohesin complex, are lateral components of the SC. STAG3 is the only meiosis-specific subunit that is represented within all four meiosis-specific cohesin complexes. In Stag3 mutant germ cells, the protein level of other meiosis-specific cohesin subunits (SMC1β, RAD21L and REC8 is reduced, and their localization to chromosome axes is disrupted. In contrast, the mitotic cohesin complex remains intact and localizes robustly to the meiotic chromosome axes. The instability of meiosis-specific cohesins observed in Stag3 mutants results in aberrant DNA repair processes, and disruption of synapsis between homologous chromosomes. Furthermore, mutation of Stag3 results in perturbation of pericentromeric heterochromatin clustering, and disruption of centromere cohesion between sister chromatids during meiotic prophase. These defects result in early prophase I arrest and apoptosis in both male and female germ cells. The meiotic defects observed in Stag3 mutants are more severe when compared to single mutants for Smc1β, Rec8 and Rad21l, however they are not as severe as the Rec8, Rad21l double mutants. Taken together, our study demonstrates that STAG3 is required for the stability of all meiosis

  11. Meiosis-specific cohesin component, Stag3 is essential for maintaining centromere chromatid cohesion, and required for DNA repair and synapsis between homologous chromosomes.

    Science.gov (United States)

    Hopkins, Jessica; Hwang, Grace; Jacob, Justin; Sapp, Nicklas; Bedigian, Rick; Oka, Kazuhiro; Overbeek, Paul; Murray, Steve; Jordan, Philip W

    2014-07-01

    Cohesins are important for chromosome structure and chromosome segregation during mitosis and meiosis. Cohesins are composed of two structural maintenance of chromosomes (SMC1-SMC3) proteins that form a V-shaped heterodimer structure, which is bridged by a α-kleisin protein and a stromal antigen (STAG) protein. Previous studies in mouse have shown that there is one SMC1 protein (SMC1β), two α-kleisins (RAD21L and REC8) and one STAG protein (STAG3) that are meiosis-specific. During meiosis, homologous chromosomes must recombine with one another in the context of a tripartite structure known as the synaptonemal complex (SC). From interaction studies, it has been shown that there are at least four meiosis-specific forms of cohesin, which together with the mitotic cohesin complex, are lateral components of the SC. STAG3 is the only meiosis-specific subunit that is represented within all four meiosis-specific cohesin complexes. In Stag3 mutant germ cells, the protein level of other meiosis-specific cohesin subunits (SMC1β, RAD21L and REC8) is reduced, and their localization to chromosome axes is disrupted. In contrast, the mitotic cohesin complex remains intact and localizes robustly to the meiotic chromosome axes. The instability of meiosis-specific cohesins observed in Stag3 mutants results in aberrant DNA repair processes, and disruption of synapsis between homologous chromosomes. Furthermore, mutation of Stag3 results in perturbation of pericentromeric heterochromatin clustering, and disruption of centromere cohesion between sister chromatids during meiotic prophase. These defects result in early prophase I arrest and apoptosis in both male and female germ cells. The meiotic defects observed in Stag3 mutants are more severe when compared to single mutants for Smc1β, Rec8 and Rad21l, however they are not as severe as the Rec8, Rad21l double mutants. Taken together, our study demonstrates that STAG3 is required for the stability of all meiosis-specific cohesin

  12. Meiosis-specific cohesin component, Stag3 is essential for maintaining centromere chromatid cohesion, and required for DNA repair and synapsis between homologous chromosomes.

    Directory of Open Access Journals (Sweden)

    Jessica Hopkins

    2014-07-01

    Full Text Available Cohesins are important for chromosome structure and chromosome segregation during mitosis and meiosis. Cohesins are composed of two structural maintenance of chromosomes (SMC1-SMC3 proteins that form a V-shaped heterodimer structure, which is bridged by a α-kleisin protein and a stromal antigen (STAG protein. Previous studies in mouse have shown that there is one SMC1 protein (SMC1β, two α-kleisins (RAD21L and REC8 and one STAG protein (STAG3 that are meiosis-specific. During meiosis, homologous chromosomes must recombine with one another in the context of a tripartite structure known as the synaptonemal complex (SC. From interaction studies, it has been shown that there are at least four meiosis-specific forms of cohesin, which together with the mitotic cohesin complex, are lateral components of the SC. STAG3 is the only meiosis-specific subunit that is represented within all four meiosis-specific cohesin complexes. In Stag3 mutant germ cells, the protein level of other meiosis-specific cohesin subunits (SMC1β, RAD21L and REC8 is reduced, and their localization to chromosome axes is disrupted. In contrast, the mitotic cohesin complex remains intact and localizes robustly to the meiotic chromosome axes. The instability of meiosis-specific cohesins observed in Stag3 mutants results in aberrant DNA repair processes, and disruption of synapsis between homologous chromosomes. Furthermore, mutation of Stag3 results in perturbation of pericentromeric heterochromatin clustering, and disruption of centromere cohesion between sister chromatids during meiotic prophase. These defects result in early prophase I arrest and apoptosis in both male and female germ cells. The meiotic defects observed in Stag3 mutants are more severe when compared to single mutants for Smc1β, Rec8 and Rad21l, however they are not as severe as the Rec8, Rad21l double mutants. Taken together, our study demonstrates that STAG3 is required for the stability of all meiosis

  13. Optimization of Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Ivan Catton

    2010-10-01

    The objective of this research is to develop tools to design and optimize heat exchangers (HE) and compact heat exchangers (CHE) for intermediate loop heat transport systems found in the very high temperature reator (VHTR) and other Generation IV designs by addressing heat transfer surface augmentation and conjugate modeling. To optimize heat exchanger, a fast running model must be created that will allow for multiple designs to be compared quickly. To model a heat exchanger, volume averaging theory, VAT, is used. VAT allows for the conservation of mass, momentum and energy to be solved for point by point in a 3 dimensional computer model of a heat exchanger. The end product of this project is a computer code that can predict an optimal configuration for a heat exchanger given only a few constraints (input fluids, size, cost, etc.). As VAT computer code can be used to model characteristics )pumping power, temperatures, and cost) of heat exchangers more quickly than traditional CFD or experiment, optimization of every geometric parameter simultaneously can be made. Using design of experiment, DOE and genetric algorithms, GE, to optimize the results of the computer code will improve heat exchanger disign.

  14. Building Relationships through Exchange

    Science.gov (United States)

    Primavera, Angi; Hall, Ellen

    2011-01-01

    From the moment of birth, children form and develop relationships with others in their world based on exchange. Children recognize that engaging in such encounters offers them the opportunity to enter into a relationship with another individual and to nurture that relationship through the exchange of messages and gifts, items and ideas. At Boulder…

  15. Aberration Corrected Emittance Exchange

    CERN Document Server

    Nanni, Emilio A

    2015-01-01

    Full exploitation of emittance exchange (EEX) requires aberration-free performance of a complex imaging system including active radio-frequency (RF) elements which can add temporal distortions. We investigate the performance of an EEX line where the exchange occurs between two dimensions with normalized emittances which differ by orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dog-leg emittance exchange setup with a 5 cell RF deflector cavity. Aberration correction is performed on the four most dominant aberrations. These include temporal aberrations that are corrected with higher order magnetic optical elements located where longitudinal and transverse emittance are coupled. We demonstrate aberration-free performance of emittances differing by 4 orders of magnitude, i.e. an initial transverse emittance of $\\epsilon_x=1$ pm-rad is exchanged with a longitudinal emittance of $\\epsilon_z=10$ nm-rad.

  16. Pulsed inductive HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S; Demchuk, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

    2016-03-31

    We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H{sub 2} – F{sub 2}(NF{sub 3} or SF6{sub 6}) and He(Ne) – H{sub 2} – F{sub 2}(NF{sub 3} or SF{sub 6}) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%. (lasers)

  17. Vector control of induction machines

    CERN Document Server

    Robyns, Benoit

    2012-01-01

    After a brief introduction to the main law of physics and fundamental concepts inherent in electromechanical conversion, ""Vector Control of Induction Machines"" introduces the standard mathematical models for induction machines - whichever rotor technology is used - as well as several squirrel-cage induction machine vector-control strategies. The use of causal ordering graphs allows systematization of the design stage, as well as standardization of the structure of control devices. ""Vector Control of Induction Machines"" suggests a unique approach aimed at reducing parameter sensitivity for

  18. Induction Linac Pulsers

    Energy Technology Data Exchange (ETDEWEB)

    Faltens, Andris

    2011-01-07

    The pulsers used in most of the induction linacs evolved from the very large body of work that was done in the U.S. and Great Britain during the development of the pulsed magnetron for radar. The radar modulators started at {approx}100 kW and reached >10 MW by 1945. A typical pulse length was 1 {mu}s at a repetition rate of 1,000 pps. A very comprehensive account of the modulator development is Pulse Generators by Lebacqz and Glasoe, one of the Radiation Laboratory Series. There are many permutations of possible modulators, two of the choices being tube type and line type. In earlier notes I wrote that technically the vacuum tube pulser met all of our induction linac needs, in the sense that a number of tubes, in series and parallel if required, could produce our pulses, regulate their voltage, be useable in feed-forward correctors, and provide a low source impedance. At a lower speed, an FET array is similar, and we have obtained and tested a large array capable of >10 MW switching. A modulator with an electronically controlled output only needs a capacitor for energy storage and in a switched mode can transfer the energy from the capacitor to the load at high efficiency. Driving a full size Astron induction core and a simulated resistive 'beam load' we achieved >50% efficiency. These electronically controlled output pulses can produce the pulses we desire but are not used because of their high cost. The second choice, the line type pulser, visually comprises a closing switch and a distributed or a lumped element transmission line. The typical switch cannot open or stop conducting after the desired pulse has been produced, and consequently all of the initially stored energy is dissipated. This approximately halves the efficiency, and the original cost estimating program LIACEP used this factor of two, even though our circuits are usually worse, and even though our inveterate optimists often omit it. The 'missing' energy is that which is

  19. Anion exchange membrane

    Science.gov (United States)

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  20. Heat exchanger design handbook

    CERN Document Server

    Thulukkanam, Kuppan

    2013-01-01

    Completely revised and updated to reflect current advances in heat exchanger technology, Heat Exchanger Design Handbook, Second Edition includes enhanced figures and thermal effectiveness charts, tables, new chapter, and additional topics--all while keeping the qualities that made the first edition a centerpiece of information for practicing engineers, research, engineers, academicians, designers, and manufacturers involved in heat exchange between two or more fluids.See What's New in the Second Edition: Updated information on pressure vessel codes, manufacturer's association standards A new c

  1. Exchange Rate in Focus

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China announced the reform of its decade-old RMB exchange rate regime last July, linking the RMB to a basket of currencies rather than the U.S. dollar alone, and allowing the RMB to appreciate 2 percent against the U.S. currency. Since then, different viewpoints on the new regime have been voiced. The People's Bank of China, the central bank, said in a statement in late March that it would further improve the system, broadening the foreign exchange market, increasing the flexibility of the RMB exchange r...

  2. Cooling by Thermodynamic Induction

    Science.gov (United States)

    Patitsas, S. N.

    2017-03-01

    A method is described for cooling conductive channels to below ambient temperature. The thermodynamic induction principle dictates that the electrically biased channel will cool if the electrical conductance decreases with temperature. The extent of this cooling is calculated in detail for both cases of ballistic and conventional transport with specific calculations for carbon nanotubes and conventional metals, followed by discussions for semiconductors, graphene, and metal-insulator transition systems. A theorem is established for ballistic transport stating that net cooling is not possible. For conventional transport, net cooling is possible over a broad temperature range, with the range being size-dependent. A temperature clamping scheme for establishing a metastable nonequilibrium stationary state is detailed and followed with discussion of possible applications to on-chip thermoelectric cooling in integrated circuitry and quantum computer systems.

  3. Cooling by Thermodynamic Induction

    Science.gov (United States)

    Patitsas, S. N.

    2016-11-01

    A method is described for cooling conductive channels to below ambient temperature. The thermodynamic induction principle dictates that the electrically biased channel will cool if the electrical conductance decreases with temperature. The extent of this cooling is calculated in detail for both cases of ballistic and conventional transport with specific calculations for carbon nanotubes and conventional metals, followed by discussions for semiconductors, graphene, and metal-insulator transition systems. A theorem is established for ballistic transport stating that net cooling is not possible. For conventional transport, net cooling is possible over a broad temperature range, with the range being size-dependent. A temperature clamping scheme for establishing a metastable nonequilibrium stationary state is detailed and followed with discussion of possible applications to on-chip thermoelectric cooling in integrated circuitry and quantum computer systems.

  4. Kinetic inductance magnetometer.

    Science.gov (United States)

    Luomahaara, Juho; Vesterinen, Visa; Grönberg, Leif; Hassel, Juha

    2014-09-10

    Sensing ultra-low magnetic fields has various applications in the fields of science, medicine and industry. There is a growing need for a sensor that can be operated in ambient environments where magnetic shielding is limited or magnetic field manipulation is involved. To this end, here we demonstrate a new magnetometer with high sensitivity and wide dynamic range. The device is based on the current nonlinearity of superconducting material stemming from kinetic inductance. A further benefit of our approach is of extreme simplicity: the device is fabricated from a single layer of niobium nitride. Moreover, radio frequency multiplexing techniques can be applied, enabling the simultaneous readout of multiple sensors, for example, in biomagnetic measurements requiring data from large sensor arrays.

  5. Bayesian Causal Induction

    CERN Document Server

    Ortega, Pedro A

    2011-01-01

    Discovering causal relationships is a hard task, often hindered by the need for intervention, and often requiring large amounts of data to resolve statistical uncertainty. However, humans quickly arrive at useful causal relationships. One possible reason is that humans use strong prior knowledge; and rather than encoding hard causal relationships, they encode beliefs over causal structures, allowing for sound generalization from the observations they obtain from directly acting in the world. In this work we propose a Bayesian approach to causal induction which allows modeling beliefs over multiple causal hypotheses and predicting the behavior of the world under causal interventions. We then illustrate how this method extracts causal information from data containing interventions and observations.

  6. Inductive Position Sensor

    Science.gov (United States)

    Youngquist, Robert C. (Inventor); Simmons, Stephen M. (Inventor)

    2015-01-01

    An inductive position sensor uses three parallel inductors, each of which has an axial core that is an independent magnetic structure. A first support couples first and second inductors and separate them by a fixed distance. A second support coupled to a third inductor disposed between the first and second inductors. The first support and second support are configured for relative movement as distance changes from the third inductor to each of the first and second inductors. An oscillating current is supplied to the first and second inductors. A device measures a phase component of a source voltage generating the oscillating current and a phase component of voltage induced in the third inductor when the oscillating current is supplied to the first and second inductors such that the phase component of the voltage induced overlaps the phase component of the source voltage.

  7. Electromagnetic induction studies

    Science.gov (United States)

    Hermance, J. F.

    1983-04-01

    Recent developments in electromagnetic induction studies of the lithosphere and the asthenosphere are reviewed. Attention is given to geoelectrical studies of active tectonic areas in terms of the major zones of crustal extension, the basin and range province along western regions of North America, and the Rio Grande rift. Studies have also been performed of tectonic activity around Iceland, the Salton Trough and Cerro Prieto, and the subduction zones of the Cascade Mountains volcanic belt, where magnetotelluric and geomagnetic variation studies have been done. Geomagnetic variations experiments have been reported in the Central Appalachians, and submarine electromagnetic studies along the Juan de Fuca ridge. Controlled source electromagnetic and dc resistivity investigations have been carried out in Nevada, Hawaii, and in the Adirondacks Mountains. Laboratory examinations on the conductivity of representative materials over a broad range of temperature, pressure, and chemistry are described.

  8. Inductive Electron Heating Revisited

    Science.gov (United States)

    Tuszewski, M.

    1996-11-01

    Inductively Coupled Plasmas (ICPs) have been studied for over a century. Recently, ICPs have been rediscovered by the multi-billion dollar semiconductor industry as an important class of high-density, low-pressure plasma sources suitable for the manufacture of next-generation integrated circuits. Present low-pressure ICP development is among the most active areas of plasma research. However, this development remains largely empirical, a prohibitively expensive approach for upcoming 300-mm diameter wafers. Hence, there is an urgent need for basic ICP plasma physics research, including experimental characterization and predictive numerical modeling. Inductive radio frequency (rf) power absorption is fundamental to the ICP electron heating and the resulting plasma transport but remains poorly understood. For example, recent experimental measurements and supporting fluid calculationsfootnote M. Tuszewski, Phys. Rev. Lett. 77 in press (1996) on a commercial deposition tool prototype show that the induced rf magnetic fields in the source can cause an order of magnitude reduction in plasma conductivity and in electron heating power density. In some cases, the rf fields penetrate through the entire volume of the ICP discharges while existing models that neglect the induced rf magnetic fields predict rf absorption in a thin skin layer near the plasma surface. The rf magnetic fields also cause more subtle changes in the plasma density and in the electron temperature spatial distributions. These data will be presented and the role of basic research in the applied world of semiconductor manufacturing will be discussed. ^*This research was conducted under the auspices of the U.S. DOE, supported by funds provided by the University of California for discretionary research by Los Alamos National Laboratory.

  9. Data Exchange Inventory System (DEXI)

    Data.gov (United States)

    Social Security Administration — Enterprise tool used to identify data exchanges occurring between SSA and our trading partners. DEXI contains information on both incoming and outgoing exchanges and...

  10. Exchange Risk Management Policy

    CERN Document Server

    2005-01-01

    At the Finance Committee of March 2005, following a comment by the CERN Audit Committee, the Chairman invited the Management to prepare a document on exchange risk management policy. The Finance Committee is invited to take note of this document.

  11. NASA Earth Exchange (NEX)

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Earth Exchange (NEX) represents a new platform for the Earth science community that provides a mechanism for scientific collaboration and knowledge sharing....

  12. Active microchannel heat exchanger

    Science.gov (United States)

    Tonkovich, Anna Lee Y [Pasco, WA; Roberts, Gary L [West Richland, WA; Call, Charles J [Pasco, WA; Wegeng, Robert S [Richland, WA; Wang, Yong [Richland, WA

    2001-01-01

    The present invention is an active microchannel heat exchanger with an active heat source and with microchannel architecture. The microchannel heat exchanger has (a) an exothermic reaction chamber; (b) an exhaust chamber; and (c) a heat exchanger chamber in thermal contact with the exhaust chamber, wherein (d) heat from the exothermic reaction chamber is convected by an exothermic reaction exhaust through the exhaust chamber and by conduction through a containment wall to the working fluid in the heat exchanger chamber thereby raising a temperature of the working fluid. The invention is particularly useful as a liquid fuel vaporizer and/or a steam generator for fuel cell power systems, and as a heat source for sustaining endothermic chemical reactions and initiating exothermic reactions.

  13. Emittance exchange results

    Energy Technology Data Exchange (ETDEWEB)

    Fliller, R.P., III; /Brookhaven; Koeth, T.; /Rutgers U., Piscataway

    2009-09-01

    The promise of next-generation light sources depends on the availability of ultra-low emittance electron sources. One method of producing low transverse emittance beams is to generate a low longitudinal emittance beam and exchange it with a large transverse emittance. Experiments are underway at Fermilab's A0 Photoinjector and ANL's Argonne Wakefield Accelerator using the exchange scheme of Kim and Sessler. The experiment at the A0 Photoinjector exchanges a large longitudinal emittance with a small transverse emittance. AWA expects to exchange a large transverse emittance with a small longitudinal emittance. In this paper we discuss recent results at A0 and AWA and future plans for these experiments.

  14. Emittance Exchange Results

    Energy Technology Data Exchange (ETDEWEB)

    Fliller III,R.; Koeth, T.

    2009-05-04

    The promise of next-generation light sources depends on the availability of ultra-low emittance electron sources. One method of producing low transverse emittance beams is to generate a low longitudinal emittance beam and exchange it with a large transverse emittance. Experiments are underway at Fermilab's A0 Photoinjector and ANL's Argonne Wakefield Accelerator using the exchange scheme of Kim and Sessler. The experiment at the A0 Photoinjector exchanges a large longitudinal emittance with a small transverse emittance. AWA expects to exchange a large transverse emittance with a small longitudinal emittance. In this paper we discuss recent results at A0 and AWA and future plans for these experiments.

  15. Microplate Heat Exchanger Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a microplate heat exchanger for cryogenic cooling systems used for continuous flow distributed cooling systems, large focal plane arrays, multiple cooling...

  16. HUD Exchange Grantee Database

    Data.gov (United States)

    Department of Housing and Urban Development — The About Grantees section of the HUD Exchange brings up contact information, reports, award, jurisdiction, and location data for organizations that receive HUD...

  17. Compact, super heat exchanger

    Science.gov (United States)

    Fortini, A.; Kazaroff, J. M.

    1980-01-01

    Heat exchanger uses porous media to enhance heat transfer through walls of cooling channels, thereby lowering wall temperature. Porous media within cooling channel increases internal surface area from which heat can be transferred to coolant. Comparison data shows wall has lower temperature and coolant has higher temperature when porous medium is used within heat exchanger. Media can be sintered powedered metal, metal fibers, woven wire layers, or any porous metal having desired permeability and porosity.

  18. A Student Teamwork Induction Protocol

    Science.gov (United States)

    Kamau, Caroline; Spong, Abigail

    2015-01-01

    Faulty group processes have harmful effects on performance but there is little research about intervention protocols to pre-empt them in higher education. This naturalistic experiment compared a control cohort with an inducted cohort. The inducted cohort attended a workshop, consultations, elected a leader and used tools (a group log and group…

  19. Sampling Assumptions in Inductive Generalization

    Science.gov (United States)

    Navarro, Daniel J.; Dry, Matthew J.; Lee, Michael D.

    2012-01-01

    Inductive generalization, where people go beyond the data provided, is a basic cognitive capability, and it underpins theoretical accounts of learning, categorization, and decision making. To complete the inductive leap needed for generalization, people must make a key "sampling" assumption about how the available data were generated.…

  20. From Inductive Reasoning to Proof

    Science.gov (United States)

    Yopp, David A.

    2009-01-01

    Mathematical proof is an expression of deductive reasoning (drawing conclusions from previous assertions). However, it is often inductive reasoning (conclusions drawn on the basis of examples) that helps learners form their deductive arguments, or proof. In addition, not all inductive arguments generate more formal arguments. This article draws a…

  1. Non-inductive current drive

    NARCIS (Netherlands)

    Westerhof, E.

    2012-01-01

    This lecture addresses the various ways of non-inductive current generation. In particular, the topics covered include the bootstrap current, RF current drive, neutral beam current drive, alternative methods, and possible synergies between different ways of non-inductive current generation.

  2. NON-INDUCTIVE CURRENT DRIVE

    NARCIS (Netherlands)

    Westerhof, E.

    2010-01-01

    This lecture addresses the various ways of non-inductive current generation. In particular, the topics covered include the bootstrap current, RF current drive, neutral beam current drive, alternative methods, and possible synergies between different ways of non-inductive current generation.

  3. Private Health Insurance Exchanges

    Science.gov (United States)

    Buttorff, Christine; Nowak, Sarah; Syme, James; Eibner, Christine

    2017-01-01

    Abstract Private health insurance exchanges offer employer health insurance, combining online shopping, increased plan choice, benefit administration, and cost-containment strategies. This article examines how private exchanges function, how they may affect employers and employees, and the possible implications for the Affordable Care Act's (ACA's) Small Business Health Options Program (SHOP) Marketplaces. The authors found that private exchanges could encourage employees to select less-generous plans. This could expose employees to higher out-of-pocket costs, but premium contributions would drop substantially, so net spending would decrease. On the other hand, employee spending may increase if, in moving to private exchanges, employers decrease their health insurance contributions. Most employers can avoid the ACA's “Cadillac tax” by reducing the generosity of the plans they offer, regardless of whether they move to a private exchange. There is not yet enough evidence to determine whether the private exchanges will become prominent in the insurance market and how they will affect employers and their employees. PMID:28845340

  4. Misoprostol for induction of labor.

    Science.gov (United States)

    Stephenson, Megan L; Wing, Deborah A

    2015-10-01

    Labor-induction rates have increased considerably in the United States as well as around the world. With up to half of all induced labors requiring cervical ripening, prostaglandins have been utilized to increase induction success and achieve vaginal delivery. Misoprostol, a synthetic prostaglandin E1 analog has the ability to mimic the changes of spontaneous labor and has been used off label for over 30 years as a labor-induction agent. In the following article, cervical ripening and induction of labor with misoprostol will be discussed. The risks and benefits of misoprostol for ripening and induction and routes of administration will be reviewed, as well as future directions and new developments for its use.

  5. Induction: The Early Years of Teaching.

    Science.gov (United States)

    Guyton, Edi; Davis, Douglas; Colarusso, Ron; Grainger, Barbara

    2002-01-01

    Addresses the need for induction programs for beginning teachers and discusses the theoretical and research support for them. Develops the notion of induction as a community responsibility and describes a university-school induction consortium, a university induction program, an induction program at a middle school, and the role of the principal…

  6. Induction: The Early Years of Teaching.

    Science.gov (United States)

    Guyton, Edi; Davis, Douglas; Colarusso, Ron; Grainger, Barbara

    2002-01-01

    Addresses the need for induction programs for beginning teachers and discusses the theoretical and research support for them. Develops the notion of induction as a community responsibility and describes a university-school induction consortium, a university induction program, an induction program at a middle school, and the role of the principal…

  7. Inductively generating Euler diagrams.

    Science.gov (United States)

    Stapleton, Gem; Rodgers, Peter; Howse, John; Zhang, Leishi

    2011-01-01

    Euler diagrams have a wide variety of uses, from information visualization to logical reasoning. In all of their application areas, the ability to automatically layout Euler diagrams brings considerable benefits. In this paper, we present a novel approach to Euler diagram generation. We develop certain graphs associated with Euler diagrams in order to allow curves to be added by finding cycles in these graphs. This permits us to build Euler diagrams inductively, adding one curve at a time. Our technique is adaptable, allowing the easy specification, and enforcement, of sets of well-formedness conditions; we present a series of results that identify properties of cycles that correspond to the well-formedness conditions. This improves upon other contributions toward the automated generation of Euler diagrams which implicitly assume some fixed set of well-formedness conditions must hold. In addition, unlike most of these other generation methods, our technique allows any abstract description to be drawn as an Euler diagram. To establish the utility of the approach, a prototype implementation has been developed.

  8. Monitoring the exposure of rats to 2-acetylaminofluorene by the estimation of mutagenic activity in excreta, sister-chromatid exchanges in peripheral blood cells and DNA adducts in peripheral blood, liver and spleen

    NARCIS (Netherlands)

    Willems, M.I.; Raat, W.K.de; Baan, R.A.; Wilmer, J.W.G.M.; Lansbergen, M.J.; Lohman, P.H.M.

    1987-01-01

    The sensitivity of various methods suitable for biomonitoring the exposure to genotoxicants was compared in an animal model. The results were related to the presence of genotoxic effects in the target organ. Groups of male Wistar rats were given one oral dose of 0, 0.1, 1, 10 or 200 mg 2-acetylamino

  9. Exchanging Description Logic Knowledge Bases

    NARCIS (Netherlands)

    Arenas, M.; Botoeva, E.; Calvanese, D.; Ryzhikov, V.; Sherkhonov, E.

    2012-01-01

    In this paper, we study the problem of exchanging knowledge between a source and a target knowledge base (KB), connected through mappings. Differently from the traditional database exchange setting, which considers only the exchange of data, we are interested in exchanging implicit knowledge. As rep

  10. Antibody induction versus corticosteroid induction for liver transplant recipients

    DEFF Research Database (Denmark)

    Penninga, Luit; Wettergren, André; Wilson, Colin H

    2014-01-01

    BACKGROUND: Liver transplantation is an established treatment option for end-stage liver failure. To date, no consensus has been reached on the use of immunosuppressive T-cell specific antibody induction compared with corticosteroid induction of immunosuppression after liver transplantation....... OBJECTIVES: To assess the benefits and harms of T-cell specific antibody induction versus corticosteroid induction for prevention of acute rejection in liver transplant recipients. SEARCH METHODS: We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register...... of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Science Citation Index Expanded, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) on 30 September 2013 together with reference checking, citation searching, contact with trial authors and pharmaceutical companies...

  11. Heat exchanger restart evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, J.M.; Hirst, C.W.; Lentz, T.F.

    1992-02-28

    On December 24, 1991, the K-Reactor was in the shutdown mode with full AC process water flow and full cooling water flow. Safety rod testing was being performed as part of the power ascension testing program. The results of cooling water samples indicated tritium concentrations higher than allowable. Further sampling and testing confirmed a Process Water System to Cooling Water System leak in heat exchanger 4A (HX 4A). The heat exchanger was isolated and the plant shutdown. Heat exchanger 4kA was removed from the plant and moved to C-Area prior to performing examinations and diagnostic testing. This included locating and identifying the leaking tube or tubes, eddy current examination of the leaking tube and a number of adjacent tubes, visually inspecting the leaking tube from both the inside as well as the area surrounding the failure mechanism. In addition ten other tubes that either exhibited eddy current indications or would represent a baseline condition were removed from heat exchanger 4A for metallurgical examination. Additional analysis and review of heat exchanger leakage history was performed to determine if there are any patterns which can be used for predictive purposes. Compensatory actions have been taken to improve the sensitivity and response time to any future events of this type. The results of these actions are summarized herein.

  12. Optimal control of induction heating processes

    CERN Document Server

    Rapoport, Edgar

    2006-01-01

    This book introduces new approaches to solving optimal control problems in induction heating process applications. Optimal Control of Induction Heating Processes demonstrates how to apply and use new optimization techniques for different types of induction heating installations. Focusing on practical methods for solving real engineering optimization problems, the text features a variety of specific optimization examples for induction heater modes and designs, particularly those used in industrial applications. The book describes basic physical phenomena in induction heating and induction

  13. Overview of Bearingless Induction Motors

    Directory of Open Access Journals (Sweden)

    Xiaodong Sun

    2014-01-01

    Full Text Available Bearingless induction motors combining functions of both torque generation and noncontact magnetic suspension together have attracted more and more attention in the past decades due to their definite advantages of compactness, simple structure, less maintenance, no wear particles, high rotational speed, and so forth. This paper overviews the key technologies of the bearingless induction motors, with emphasis on motor topologies, mathematical models, and control strategies. Particularly, in the control issues, the vector control, independent control, direct torque control, nonlinear decoupling control, sensorless control, and so forth are investigated. In addition, several possible development trends of the bearingless induction motors are also discussed.

  14. Induction of formaldehyde contact sensitivity

    DEFF Research Database (Denmark)

    Andersen, Klaus Ejner; Boman, A; Vølund, A

    1985-01-01

    intradermal induction with 0.65% formaldehyde; in Stockholm it was 84% after induction with 0.34%. The data from the two laboratories could be described by parallel displaced dose response curves suggesting that the guinea pig strain used in Stockholm was significantly more susceptible to formaldehyde than......, and formaldehyde 1% and 0.1% was used for challenge. The incidence of contact sensitivity depended on the intradermal, but not on the topical induction dose. Statistical analyses showed a non-monotonous (non-linear) dose response relationship. The estimated maximal sensitization rate in Copenhagen was 80% after...

  15. Ion exchange phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, I.C.; Sposito, G.

    2011-05-01

    Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).

  16. Microgravity condensing heat exchanger

    Science.gov (United States)

    Thomas, Christopher M. (Inventor); Ma, Yonghui (Inventor); North, Andrew (Inventor); Weislogel, Mark M. (Inventor)

    2011-01-01

    A heat exchanger having a plurality of heat exchanging aluminum fins with hydrophilic condensing surfaces which are stacked and clamped between two cold plates. The cold plates are aligned radially along a plane extending through the axis of a cylindrical duct and hold the stacked and clamped portions of the heat exchanging fins along the axis of the cylindrical duct. The fins extend outwardly from the clamped portions along approximately radial planes. The spacing between fins is symmetric about the cold plates, and are somewhat more closely spaced as the angle they make with the cold plates approaches 90.degree.. Passageways extend through the fins between vertex spaces which provide capillary storage and communicate with passageways formed in the stacked and clamped portions of the fins, which communicate with water drains connected to a pump externally to the duct. Water with no entrained air is drawn from the capillary spaces.

  17. Tuning Exchange Anisotropy of Exchange-Biased System

    Institute of Scientific and Technical Information of China (English)

    XU Yan; HU Jing-Guo; R.L.Stamps

    2008-01-01

    Exchange anisotropy in FM/AFM bilayers has given a lot of static magnetization properties such as enhanced coercivity and magnetization loop shifts.These phenomena are primarily from the effective anisotropies intro-duced into a ferromagnet by exchange coupling with a strongly anisotropic antiferromagnet.These effective anisotropies can also be used to explain the dynamic consequences of exchange-biased bilayers.In this article,the dynamic con-sequences such as exchange-induced susceptibility,exchange-induced permeability,and the corresponding domain wall characteristics in the exchange-biased structures of ferromagnet/antiferromagnetl/antiferromagnet2 are studied.The results show that the second antiferromagnetic layer can largely affect the dynamic consequences of exchange-biased bilayers.Especially in the ease of critical temperature,the effects become more obvious.Practically,the exchange anisotropy of biased bilayer system can be tuned by exchange coupling with the second antiferromagnetic layer.

  18. Functional interpretation and inductive definitions

    CERN Document Server

    Avigad, Jeremy

    2008-01-01

    Extending G\\"odel's \\emph{Dialectica} interpretation, we provide a functional interpretation of classical theories of positive arithmetic inductive definitions, reducing them to theories of finite-type functionals defined using transfinite recursion on well-founded trees.

  19. Mathematical Induction in the Classroom

    Science.gov (United States)

    Avital, Shmuel; Hansen, Rodney T.

    1976-01-01

    This paper discusses the process of investigating a mathematical situation, making conjectures, formulating an equation, then using mathematical induction to show the result is valid. Several examples appropriate for secondary school level are given. (DT)

  20. A Note on Mathematical Induction

    Science.gov (United States)

    Brumfiel, Charles

    1974-01-01

    A classic problem involving the "misuse" of mathematical induction is presented. The error in the "proof" is then exposed. The generalization of this problem is presented as a false theorem which should serve to highlight the error. (LS)

  1. Adjustable Induction-Heating Coil

    Science.gov (United States)

    Ellis, Rod; Bartolotta, Paul

    1990-01-01

    Improved design for induction-heating work coil facilitates optimization of heating in different metal specimens. Three segments adjusted independently to obtain desired distribution of temperature. Reduces time needed to achieve required temperature profiles.

  2. Induction heating coupler and annealer

    Science.gov (United States)

    Fox, Robert L. (Inventor); Johnson, Samuel D. (Inventor); Copeland, Carl E. (Inventor); Coultrip, Robert H. (Inventor); Phillips, W. Morris (Inventor); Johnston, David F. (Inventor); Swaim, Robert J. (Inventor); Dinkins, James R. (Inventor)

    1994-01-01

    An induction heating device includes a handle having a hollow interior and two opposite ends, a wrist connected to one end of the handle, a U-shaped pole piece having- two spaced apart ends, a tank circuit including an induction coil wrapped around the pole piece and a capacitor connected to the induction coil, a head connected to the wrist and including a housing for receiving the U-shaped pole piece, the two spaced apart ends of the pole piece extending outwardly beyond the housing, and a power source connected to the tank circuit. When the tank circuit is energized and a susceptor is placed in juxtaposition to the ends of the U-shaped pole piece, the susceptor is heated by induction heating due to a magnetic flux passing between the two ends of the pole piece.

  3. ORGANIZATIONAL DEVELOPMENT ACTION: INDUCTION PROGRAM

    National Research Council Canada - National Science Library

    José G. VARGAS-HERNÁNDEZ

    2016-01-01

    .... Also, an induction program is presented as an intervention proposal of organization development, on the premise that this program is a first step in the solving of the existing low productivity problem...

  4. Inductance and hypergeometric functions. II

    DEFF Research Database (Denmark)

    Karlsson, Per W.

    2000-01-01

    A previously obtained integral for the self-inductance of a solenoid is further transformed. The resulting formula involves double Kampé de Fériet functions which are analytic continuations rather than power series.......A previously obtained integral for the self-inductance of a solenoid is further transformed. The resulting formula involves double Kampé de Fériet functions which are analytic continuations rather than power series....

  5. Automated Discovery of Inductive Theorems

    OpenAIRE

    McCasland, Roy; Bundy, Alan; Serge, Autexier

    2007-01-01

    Inductive mathematical theorems have, as a rule, historically been quite difficult to prove – both for mathematics students and for auto- mated theorem provers. That said, there has been considerable progress over the past several years, within the automated reasoning community, towards proving some of these theorems. However, little work has been done thus far towards automatically discovering them. In this paper we present our methods of discovering (as well as proving) inductive theorems, ...

  6. Inductive System Monitors Tasks

    Science.gov (United States)

    2008-01-01

    The Inductive Monitoring System (IMS) software developed at Ames Research Center uses artificial intelligence and data mining techniques to build system-monitoring knowledge bases from archived or simulated sensor data. This information is then used to detect unusual or anomalous behavior that may indicate an impending system failure. Currently helping analyze data from systems that help fly and maintain the space shuttle and the International Space Station (ISS), the IMS has also been employed by data classes are then used to build a monitoring knowledge base. In real time, IMS performs monitoring functions: determining and displaying the degree of deviation from nominal performance. IMS trend analyses can detect conditions that may indicate a failure or required system maintenance. The development of IMS was motivated by the difficulty of producing detailed diagnostic models of some system components due to complexity or unavailability of design information. Successful applications have ranged from real-time monitoring of aircraft engine and control systems to anomaly detection in space shuttle and ISS data. IMS was used on shuttle missions STS-121, STS-115, and STS-116 to search the Wing Leading Edge Impact Detection System (WLEIDS) data for signs of possible damaging impacts during launch. It independently verified findings of the WLEIDS Mission Evaluation Room (MER) analysts and indicated additional points of interest that were subsequently investigated by the MER team. In support of the Exploration Systems Mission Directorate, IMS is being deployed as an anomaly detection tool on ISS mission control consoles in the Johnson Space Center Mission Operations Directorate. IMS has been trained to detect faults in the ISS Control Moment Gyroscope (CMG) systems. In laboratory tests, it has already detected several minor anomalies in real-time CMG data. When tested on archived data, IMS was able to detect precursors of the CMG1 failure nearly 15 hours in advance of

  7. Exchangeable lower previsions

    CERN Document Server

    de Cooman, Gert; Miranda, Enrique; 10.3150/09-BEJ182

    2009-01-01

    We extend de Finetti's [Ann. Inst. H. Poincar\\'{e} 7 (1937) 1--68] notion of exchangeability to finite and countable sequences of variables, when a subject's beliefs about them are modelled using coherent lower previsions rather than (linear) previsions. We derive representation theorems in both the finite and countable cases, in terms of sampling without and with replacement, respectively.

  8. Baltic Exchange toodi Tallinna

    Index Scriptorium Estoniae

    2007-01-01

    Viimane osa merekonteineritesse kokkupakitud Londoni laevandus- ja merebörsi Baltic Exchange'i endise peakorteri detailidest jõudis 2007. a. juunis Tallinna. Hoone detailid ostnud ärimehed Heiti Hääl ja Eerik-Niiles Kross plaanivad leida hoonele koha Tallinna kesklinnas. E.-N. Krossi kommentaar

  9. Telephone Exchange Maintenance

    CERN Multimedia

    2005-01-01

    Urgent maintenance work on CERN telephone exchanges will be performed on 24 March from 6 a.m. to 8 a.m. Telephone services may be disrupted or even interrupted during this time. For more details, please contact us by email at Standard.Telephone@cern.ch.

  10. Currency Exchange Rates.

    Science.gov (United States)

    Siler, Carl R.

    This curriculum unit of the Muncie (Indiana) Southside High School is to simulate the dynamics of foreign currency exchange rates from the perspectives of: (1) a major U.S. corporation, ABB Power T & D Company, Inc., of Muncie, Indiana, a manufacturer of large power transformers for the domestic and foreign markets; and (2) individual…

  11. Microtube strip heat exchanger

    Science.gov (United States)

    Doty, F. D.

    1991-04-01

    During the last quarter, Doty Scientific, Inc. (DSI) continued to make progress on the microtube strip (MTS) heat exchangers. The team has begun a heat exchanger stress analysis; however, they have been concentrating the bulk of their analytical energies on a computational fluid dynmaics (CFD) model to determine the location and magnitude of shell-side flow maldistribution which decreases heat exchanger effectiveness. DSI received 120 fineblanked tubestrips from Southern Fineblanking (SFB) for manufacturing process development. Both SFB and NIST provided inspection reports of the tubestrips. DSI completed the tooling required to encapsulate a tube array and press tubestrips on the array. Pressing the tubestrips on tube arrays showed design deficiencies both in the tubestrip design and the tooling design. DSI has a number of revisions in process to correct these deficiencies. The research effort has identified a more economical fusible alloy for encapsulating the tube array, and determined the parameters required to successfully encapsulate the tube array with the new alloy. A more compact MTS heat exchanger bank was designed.

  12. Nature's Heat Exchangers.

    Science.gov (United States)

    Barnes, George

    1991-01-01

    Discusses the heat-transfer systems of different animals. Systems include heat conduction into the ground, heat transferred by convection, heat exchange in lizards, fish and polar animals, the carotid rete system, electromagnetic radiation from animals and people, and plant and animal fiber optics. (MDH)

  13. Antibody induction versus placebo, no induction, or another type of antibody induction for liver transplant recipients

    DEFF Research Database (Denmark)

    Penninga, Luit; Wettergren, André; Wilson, Colin H

    2014-01-01

    BACKGROUND: Liver transplantation is an established treatment option for end-stage liver failure. To date, no consensus has been reached on the use of immunosuppressive T-cell antibody induction for preventing rejection after liver transplantation. OBJECTIVES: To assess the benefits and harms...... of immunosuppressive T-cell specific antibody induction compared with placebo, no induction, or another type of T-cell specific antibody induction for prevention of acute rejection in liver transplant recipients. SEARCH METHODS: We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane...... Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Science Citation Index Expanded, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) until September 2013. SELECTION CRITERIA: Randomised clinical trials assessing immunosuppression with T...

  14. Counterflow Regolith Heat Exchanger

    Science.gov (United States)

    Zubrin, Robert; Jonscher, Peter

    2013-01-01

    A problem exists in reducing the total heating power required to extract oxygen from lunar regolith. All such processes require heating a great deal of soil, and the heat energy is wasted if it cannot be recycled from processed material back into new material. The counterflow regolith heat exchanger (CoRHE) is a device that transfers heat from hot regolith to cold regolith. The CoRHE is essentially a tube-in-tube heat exchanger with internal and external augers attached to the inner rotating tube to move the regolith. Hot regolith in the outer tube is moved in one direction by a right-hand - ed auger, and the cool regolith in the inner tube is moved in the opposite direction by a left-handed auger attached to the inside of the rotating tube. In this counterflow arrangement, a large fraction of the heat from the expended regolith is transferred to the new regolith. The spent regolith leaves the heat exchanger close to the temperature of the cold new regolith, and the new regolith is pre-heated close to the initial temperature of the spent regolith. Using the CoRHE can reduce the heating requirement of a lunar ISRU system by 80%, reducing the total power consumption by a factor of two. The unique feature of this system is that it allows for counterflow heat exchange to occur between solids, instead of liquids or gases, as is commonly done. In addition, in variants of this concept, the hydrogen reduction can be made to occur within the counterflow heat exchanger itself, enabling a simplified lunar ISRU (in situ resource utilization) system with excellent energy economy and continuous nonbatch mode operation.

  15. Analytical applications of ion exchangers

    CERN Document Server

    Inczédy, J

    1966-01-01

    Analytical Applications of Ion Exchangers presents the laboratory use of ion-exchange resins. This book discusses the development in the analytical application of ion exchangers. Organized into 10 chapters, this book begins with an overview of the history and significance of ion exchangers for technical purposes. This text then describes the properties of ion exchangers, which are large molecular water-insoluble polyelectrolytes having a cross-linked structure that contains ionic groups. Other chapters consider the theories concerning the operation of ion-exchange resins and investigate th

  16. [Ion specificity during ion exchange equilibrium in natural clinoptilolite].

    Science.gov (United States)

    He, Yun-Hua; Li, Hang; Liu, Xin-Min; Xiong, Hai-Ling

    2015-03-01

    Zeolites have been widely applied in soil improvement and environment protection. The study on ion specificity during ion exchange equilibrium is of important significance for better use of zeolites. The maximum adsorption capacities of alkali ions during ion exchange equilibrium in the clinoptilolite showed obvious specificity. For alkali metal ions with equivalent valence, the differences in adsorption capacity increased with the decrease of ionic concentration. These results cannot be well explained by the classical theories including coulomb force, ionic size, hydration, dispersion force, classic induction force and surface complexation. We found that the coupling of polarization effects resulted from the quantum fluctuation of diverse alkali metal ions and electric field near the zeolite surface should be the primary reason for specific ion effect during ion exchange in zeolite. The result of this coupling effect was that the difference in the ion dipole moment increased with the increase of surface potential, which further expanded the difference in the adsorption ability between zeolite surface and ions, resulting in different ion exchange adsorption ability at the solid/liquid interface. Due to the high surface charge density of zeolite, ionic size also played an important role in the distribution of ions in the double diffuse layer, which led to an interesting result that distinct differences in exchange adsorption ability of various alkali metal ions were only detected at high surface potential (the absolute value was greater than 0.2 V), which was different from the ion exchange equilibrium result on the surface with low charge density.

  17. Experimental and Numerical Study of the Radiant Induction-Unit and the Induction Radiant Air-Conditioning System

    Directory of Open Access Journals (Sweden)

    Qiang Si

    2016-12-01

    Full Text Available In this paper we proposed the novel air-conditioning system which combined induction ventilation and radiant air-conditioning. The indoor terminal device is the radiant induction-unit (RIDU. The RIDU is the induction unit combined with the pore radiant panel on which the copper pipes with rigid aluminum diffusion fins are installed. The two-stage evaporator chiller with the non-azeotropic mixture refrigerant is utilized in the system to reduce the initial investment in equipment. With the performance test and the steady state heat transfer model based on the theory of radiative heat transfer, the relationship between the induction ratio of the RIDU and the characteristic of the air supply was studied. Based on this, it is verified that the RIDU has a lower dew-point temperature and better anti-condensation performance than a traditional plate-type radiant panel. The characteristics of the radiation and convection heat transfer of the RIDU were studied. The total heat exchange of the RIDU can be 16.5% greater than that of the traditional plate-type radiant terminal.

  18. Estimation of physical parameters in induction motors

    DEFF Research Database (Denmark)

    Børsting, H.; Knudsen, Morten; Rasmussen, Henrik

    1994-01-01

    Parameter estimation in induction motors is a field of great interest, because accurate models are needed for robust dynamic control of induction motors......Parameter estimation in induction motors is a field of great interest, because accurate models are needed for robust dynamic control of induction motors...

  19. Kinetic inductance measured in a superconducting wire

    Science.gov (United States)

    Meservey, R. H.; Tedrow, P. M.

    1970-01-01

    Ultrasensitive technique to measure kinetic inductance has test specimen included as part of the inductance of a tank circuit of a tunnel diode oscillator. Frequency counter measures shift in frequency of oscillator, caused by changes in inductance. Frequency shift in tank circuit is proportional to change in kinetic inductance

  20. On the internal structures of inductive types

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The paper investigates the internal structures of hereditary inductive types in logical type theory. By defining a bisimulation equality on the inhabitants of each hereditary inductive type, one is able to show that the inhabitants of a hereditary inductive type satisfy the basic properties of sets. A hereditary inductive type can therefore be conceived as a universe of sets.

  1. On generic representation of implicit induction procedures

    NARCIS (Netherlands)

    Naidich, D.

    1996-01-01

    We develop a generic representation of implicit induction proof procedures within the cover set induction framework. Our work further develops the approach of cover set induction on propositional orderings. We show that in order to represent a substantially wide range of implicit induction procedure

  2. Induction, Space and Positive Ethics : Induction, Space, Ethics

    OpenAIRE

    Kirsh, Marvin

    2008-01-01

    4 pages, 0 figures, 1 reference; International audience; One may purport that ones' awareness of space for scientific purposes comes about from a potential awareness of its' absence that is derived from times when ones attention is not focused on it. Yet simply one might extract the notion that space and entailed properties of it are elemental —i.e. conceptually non reducible and that from which all emanates. The words non-ethical induction, entailing the existence of ethical induction, if co...

  3. EXCHANGE RATE - REGIMES AND POLICIES

    Directory of Open Access Journals (Sweden)

    Novak Lučić

    2014-12-01

    Full Text Available Exchange rate of one currency is the price of the currency expressed in units of other currency. It is formed by the interaction of supply and demand in the foreign exchange market. Given that the exchange rate has a direct impact on the competitiveness of a country in terms of features of its exports and imports, in its balance of payments, and indirectly the overall economic and social development, in addition to acting in market principles - supply and demand in the formation of the equilibrium exchange rate, exchange rate is subject to different, stronger or weaker, more or less, forms of intervention. In the search for the optimal exchange rate policy of the national currency, the monetary authorities are positioned between the two extremes - the complete abandonment of the exchange rate to the market laws of supply and demand, or fixing the exchange rate for any of the selected anchor currency.

  4. Data Exchange Inventory (DEXI) System

    Data.gov (United States)

    Social Security Administration — DEXI is an intranet application used by SSA users to track all incoming and outgoing data exchanges between SSA and our data exchange partners. Information such as...

  5. Flexible heating head for induction heating

    Science.gov (United States)

    Fox, Robert L. (Inventor); Johnson, Samuel D. (Inventor); Coultrip, Robert H. (Inventor); Phillips, W. Morris (Inventor)

    1993-01-01

    An induction heating head includes a length of wire having first and second opposite ends and being wound in a flat spiral shape to form an induction coil, a capacitor connected to the first and second ends of the wire, the induction coil and capacitor defining a tank circuit, and a flexible, elastomeric body molded to encase the induction coil. When a susceptor is placed in juxtaposition to the body, and the tank circuit is powered, the susceptor is inductively heated.

  6. Cyclic and Inductive Calculi are equivalent

    CERN Document Server

    Voicu, Razvan

    2011-01-01

    Brotherston and Simpson [citation] have formalized and investigated cyclic reasoning, reaching the important conclusion that it is at least as powerful as inductive reasoning (specifically, they showed that each inductive proof can be translated into a cyclic proof). We add to their investigation by proving the converse of this result, namely that each inductive proof can be translated into an inductive one. This, in effect, establishes the equivalence between first order cyclic and inductive calculi.

  7. Cyclic and Inductive Calculi are equivalent

    OpenAIRE

    Razvan VOICU; Li, Mengran

    2011-01-01

    Brotherston and Simpson [citation] have formalized and investigated cyclic reasoning, reaching the important conclusion that it is at least as powerful as inductive reasoning (specifically, they showed that each inductive proof can be translated into a cyclic proof). We add to their investigation by proving the converse of this result, namely that each inductive proof can be translated into an inductive one. This, in effect, establishes the equivalence between first order cyclic and inductive...

  8. Induction of labour.

    Science.gov (United States)

    Leduc, Dean; Biringer, Anne; Lee, Lily; Dy, Jessica

    2013-09-01

    Objectif : Analyser la littérature la plus récente afin de formuler des recommandations factuelles à l’intention des fournisseurs de soins obstétricaux au sujet du déclenchement du travail. Options : Mise en œuvre d’un déclenchement du travail dans le cadre d’une grossesse. Issues : Chronologie et méthode appropriées pour ce qui est du déclenchement, mode d’accouchement approprié et issues maternelles et périnatales optimales. Résultats : La littérature publiée a été récupérée par l’intermédiaire de recherches menées dans PubMed, CINAHL et The Cochrane Library en 2010, au moyen d’un vocabulaire contrôlé (p. ex. « labour », « induced », « labour induction », « cervical ripening ») et de mots clés (p. ex. « induce », « induction », « augmentation ») appropriés. Les résultats ont été restreints aux analyses systématiques, aux essais comparatifs randomisés / essais cliniques comparatifs et aux études observationnelles. Aucune restriction n’a été appliquée en matière de date ou de langue. Les recherches ont été mises à jour de façon régulière et intégrées à la directive clinique jusqu’à la fin de 2010. La littérature grise (non publiée) a été identifiée par l’intermédiaire de recherches menées dans les sites Web d’organismes s’intéressant à l’évaluation des technologies dans le domaine de la santé et d’organismes connexes, dans des collections de directives cliniques, dans des registres d’essais cliniques et auprès de sociétés de spécialité médicale nationales et internationales. Valeurs : La qualité des résultats est évaluée au moyen des critères décrits dans le rapport du Groupe d’étude canadien sur les soins de santé préventifs (Tableau 1). Validation : Les données, les déclarations sommaires et les recommandations que contient la présente directive clinique ont été vérifiées en les comparant à celles de directives

  9. 38 CFR 21.282 - Effective date of induction into a rehabilitation program; retroactive induction.

    Science.gov (United States)

    2010-07-01

    ... induction into a rehabilitation program; retroactive induction. 21.282 Section 21.282 Pensions, Bonuses, and... Vocational Rehabilitation and Employment Under 38 U.S.C. Chapter 31 Induction into A Rehabilitation Program § 21.282 Effective date of induction into a rehabilitation program; retroactive induction. (a)...

  10. The Exchange Rate Forecasting Puzzle

    OpenAIRE

    Francis Vitek

    2005-01-01

    We survey and update the empirical literature concerning the predictability of nominal exchange rates using structural macroeconomic models over the recent floating exchange rate period. In particular, we consider both flexible and sticky price versions of the monetary model of nominal exchange rate determination. In agreement with the existing empirical literature, we find that nominal exchange rate movements are difficult to forecast, with a random walk generally dominating the monetary mod...

  11. Geology Exchange Program

    Science.gov (United States)

    Because geology professors cannot bring ore deposits from around the globe into their classrooms, the next best thing is to take their students to the deposits, according to David Norman, an associate professor of geochemistry at New Mexico Tech and Angus Moore of the Royal School of Mines. They organized a new exchange program between the New Mexico Institute of Mining and Technology in Socorro, N.M., and the Royal School of Mines in London, England. In May, 14 students from England toured deposits in New Mexico, Arizona, Utah, and Colorado; in the photograph, Norman (on the right) describes a rock from a New Mexico ore deposit to some of the visitors from England. In early June a contingency from New Mexico Tech began studying deposits in England, Spain, and Portugal. Norman and Moore say that the exchange program may be expanded next year.

  12. Lipid exchange by ultracentrifugation

    DEFF Research Database (Denmark)

    Drachmann, Nikolaj Düring; Olesen, Claus

    2014-01-01

    Lipids play an important role in maintaining P-type ATPase structure and function, and often they are crucial for ATPase activity. When the P-type ATPases are in the membrane, they are surrounded by a mix of different lipids species with varying aliphatic chain lengths and saturation......, and the complex interplay between the lipids and the P-type ATPases are still not well understood. We here describe a robust method to exchange the majority of the lipids surrounding the ATPase after solubilisation and/or purification with a target lipid of interest. The method is based on an ultracentrifugation...... step, where the protein sample is spun through a dense buffer containing large excess of the target lipid, which results in an approximately 80-85 % lipid exchange. The method is a very gently technique that maintains protein folding during the process, hence allowing further characterization...

  13. ROOT HYDRAULIC CONDUCTIVITY AND PHOTOSYNTHETIC CAPACITY OF EUCALYPT CLONAL CUTTINGS WITH ROOT MALFORMATION INDUCTIONS

    Directory of Open Access Journals (Sweden)

    Fábio Afonso Mazzei Moura de Assis Figueiredo

    2014-06-01

    Full Text Available http://dx.doi.org/10.5902/1980509814566The gain reduction of wood biomass in trees has been assigned to root deformations even in the nursery phase. The objective of this work was the evaluation of the root system hydraulic conductivity, gas exchanges and photochemical efficiency of eucalypt clonal cuttings with and without root deformation inductions. The treatments were: 1 operational cuttings without root malformation inductions (grown according to the used methodology of Fibria Cellulose S.A.; 2 root deformation inductions. These inductions did not promote decrease in the root volume. However, the deformations brought reduction of the root system hydraulic conductivity. Lower photosynthetic rates were also observed along the day in the cuttings in the root deformed cuttings. This decreasing rate is connected to stomatal and non stomatal factors.

  14. Exchange rate rebounds after foreign exchange market interventions

    Science.gov (United States)

    Hoshikawa, Takeshi

    2017-03-01

    This study examined the rebounds in the exchange rate after foreign exchange intervention. When intervention is strongly effective, the exchange rate rebounds at next day. The effect of intervention is reduced slightly by the rebound after the intervention. The exchange rate might have been 67.12-77.47 yen to a US dollar without yen-selling/dollar-purchasing intervention of 74,691,100 million yen implemented by the Japanese government since 1991, in comparison to the actual exchange rate was 103.19 yen to the US dollar at the end of March 2014.

  15. Heat exchange apparatus

    Science.gov (United States)

    Degtiarenko, Pavel V.

    2003-08-12

    A heat exchange apparatus comprising a coolant conduit or heat sink having attached to its surface a first radial array of spaced-apart parallel plate fins or needles and a second radial array of spaced-apart parallel plate fins or needles thermally coupled to a body to be cooled and meshed with, but not contacting the first radial array of spaced-apart parallel plate fins or needles.

  16. Exchange Rate Predictions

    OpenAIRE

    Yablonskyy, Karen

    2012-01-01

    The aim of this thesis is to analyze the foreign exchange currency forecasting techniques. Moreover the central idea behind the topic is to develop the strategy of forecasting by choosing indicators and techniques to make own forecast on currency pair EUR/USD. This thesis work is a mixture of theory and practice analyses. The goal during the work on this project was to study different types of forecasting techniques and make own forecast, practice forecasting and trading on Forex platform, ba...

  17. Thermoelectric heat exchange element

    Science.gov (United States)

    Callas, James J.; Taher, Mahmoud A.

    2007-08-14

    A thermoelectric heat exchange module includes a first substrate including a heat receptive side and a heat donative side and a series of undulatory pleats. The module may also include a thermoelectric material layer having a ZT value of 1.0 or more disposed on at least one of the heat receptive side and the heat donative side, and an electrical contact may be in electrical communication with the thermoelectric material layer.

  18. Exchange Rate Predictions

    OpenAIRE

    Yablonskyy, Karen

    2012-01-01

    The aim of this thesis is to analyze the foreign exchange currency forecasting techniques. Moreover the central idea behind the topic is to develop the strategy of forecasting by choosing indicators and techniques to make own forecast on currency pair EUR/USD. This thesis work is a mixture of theory and practice analyses. The goal during the work on this project was to study different types of forecasting techniques and make own forecast, practice forecasting and trading on Forex platform, ba...

  19. Hydrogen Exchange Mass Spectrometry.

    Science.gov (United States)

    Mayne, Leland

    2016-01-01

    Hydrogen exchange (HX) methods can reveal much about the structure, energetics, and dynamics of proteins. The addition of mass spectrometry (MS) to an earlier fragmentation-separation HX analysis now extends HX studies to larger proteins at high structural resolution and can provide information not available before. This chapter discusses experimental aspects of HX labeling, especially with respect to the use of MS and the analysis of MS data.

  20. Thermoelectric heat exchange element

    Energy Technology Data Exchange (ETDEWEB)

    Callas, James J. (Peoria, IL); Taher, Mahmoud A. (Peoria, IL)

    2007-08-14

    A thermoelectric heat exchange module includes a first substrate including a heat receptive side and a heat donative side and a series of undulatory pleats. The module may also include a thermoelectric material layer having a ZT value of 1.0 or more disposed on at least one of the heat receptive side and the heat donative side, and an electrical contact may be in electrical communication with the thermoelectric material layer.

  1. On Exchange QB∞-Rings

    Institute of Scientific and Technical Information of China (English)

    Huanyin Chen

    2007-01-01

    In this paper, we introduce a new class of rings, the QB∞-rings. We investigate necessary and sufficient conditions under which an exchange ring is a QB∞-ring. The modules over an exchange QB∞-ring are studied. Also, we prove that every regular square matrix over an exchange QB∞-ring admits a diagonal reduction by pseudo-invertible matrices.

  2. O3 and NOx Exchange

    NARCIS (Netherlands)

    Loubet, B.; Castell, J.F.; Laville, P.; Personne, E.; Tuzet, A.; Ammann, C.; Emberson, L.; Ganzeveld, L.; Kowalski, A.S.; Merbold, L.; Stella, P.; Tuovinen, J.P.

    2015-01-01

    This discussion was based on the background document “Review on modelling atmosphere-biosphere exchange of Ozone and Nitrogen oxides”, which reviews the processes contributing to biosphere-atmosphere exchange of O3 and NOx, including stomatal and non-stomatal exchange of O3 and NO, NO2.

  3. The stability of exchange networks

    NARCIS (Netherlands)

    Doğan, G.; Assen, M. van; Rijt, A. van de; Buskens, V.W.

    2009-01-01

    Economic and sociological exchange theories predict divisions of exchange benefits given an assumed fixed network of exchange relations. Since network structure has been found to have a large impact on actors’ payoffs, actors have strong incentives for network change.Weanswer the question what happe

  4. Timing Foreign Exchange Markets

    Directory of Open Access Journals (Sweden)

    Samuel W. Malone

    2016-03-01

    Full Text Available To improve short-horizon exchange rate forecasts, we employ foreign exchange market risk factors as fundamentals, and Bayesian treed Gaussian process (BTGP models to handle non-linear, time-varying relationships between these fundamentals and exchange rates. Forecasts from the BTGP model conditional on the carry and dollar factors dominate random walk forecasts on accuracy and economic criteria in the Meese-Rogoff setting. Superior market timing ability for large moves, more than directional accuracy, drives the BTGP’s success. We explain how, through a model averaging Monte Carlo scheme, the BTGP is able to simultaneously exploit smoothness and rough breaks in between-variable dynamics. Either feature in isolation is unable to consistently outperform benchmarks throughout the full span of time in our forecasting exercises. Trading strategies based on ex ante BTGP forecasts deliver the highest out-of-sample risk-adjusted returns for the median currency, as well as for both predictable, traded risk factors.

  5. Scraped surface heat exchangers.

    Science.gov (United States)

    Rao, Chetan S; Hartel, Richard W

    2006-01-01

    Scraped surface heat exchangers (SSHEs) are commonly used in the food, chemical, and pharmaceutical industries for heat transfer, crystallization, and other continuous processes. They are ideally suited for products that are viscous, sticky, that contain particulate matter, or that need some degree of crystallization. Since these characteristics describe a vast majority of processed foods, SSHEs are especially suited for pumpable food products. During operation, the product is brought in contact with a heat transfer surface that is rapidly and continuously scraped, thereby exposing the surface to the passage of untreated product. In addition to maintaining high and uniform heat exchange, the scraper blades also provide simultaneous mixing and agitation. Heat exchange for sticky and viscous foods such as heavy salad dressings, margarine, chocolate, peanut butter, fondant, ice cream, and shortenings is possible only by using SSHEs. High heat transfer coefficients are achieved because the boundary layer is continuously replaced by fresh material. Moreover, the product is in contact with the heating surface for only a few seconds and high temperature gradients can be used without the danger of causing undesirable reactions. SSHEs are versatile in the use of heat transfer medium and the various unit operations that can be carried out simultaneously. This article critically reviews the current understanding of the operations and applications of SSHEs.

  6. The exchangeability of shape

    Directory of Open Access Journals (Sweden)

    Kaba Dramane

    2010-10-01

    Full Text Available Abstract Background Landmark based geometric morphometrics (GM allows the quantitative comparison of organismal shapes. When applied to systematics, it is able to score shape changes which often are undetectable by traditional morphological studies and even by classical morphometric approaches. It has thus become a fast and low cost candidate to identify cryptic species. Due to inherent mathematical properties, shape variables derived from one set of coordinates cannot be compared with shape variables derived from another set. Raw coordinates which produce these shape variables could be used for data exchange, however they contain measurement error. The latter may represent a significant obstacle when the objective is to distinguish very similar species. Results We show here that a single user derived dataset produces much less classification error than a multiple one. The question then becomes how to circumvent the lack of exchangeability of shape variables while preserving a single user dataset. A solution to this question could lead to the creation of a relatively fast and inexpensive systematic tool adapted for the recognition of cryptic species. Conclusions To preserve both exchangeability of shape and a single user derived dataset, our suggestion is to create a free access bank of reference images from which one can produce raw coordinates and use them for comparison with external specimens. Thus, we propose an alternative geometric descriptive system that separates 2-D data gathering and analyzes.

  7. Induction interview form in EDH

    CERN Document Server

    Information technology Department, AIS (Administrative Information Services) Group

    2007-01-01

    As part of the efforts to rationalise administrative procedures, the IT and HR Departments have developed a new EDH form for induction interviews, which can be accessed using the link below. In accordance with Administrative Circular No. 2 ('Recruitment, Appointment and possible developments regarding the contractual position of Staff Members', Rev. 3), the work and training objectives to be achieved during the probation period shall be specified in writing to all new staff members during an induction interview. The interview shall take place between the new staff member and his supervisor within six weeks of his taking up his duties at the latest. https://edh.cern.ch/Document/MAPS/Induction1) (or from the EDH desktop, by clicking on 'Other Tasks' and going to the 'HR & Training' heading) Please note that this form is to be used exclusively for new staff members. A separate EDH form will be developed for fellows.Information technology Department, AIS (Administrative Information Services) Group Human Re...

  8. Induction interview form in EDH

    CERN Document Server

    Information technology Department, AIS (Administrative Information Services) Group,

    2007-01-01

    As part of the efforts to rationalise administrative procedures, the IT and HR Departments have developed a new EDH form for induction interviews, which can be accessed using the link below. In accordance with Administrative Circular No. 2 ('Recruitment, Appointment and possible developments regarding the contractual position of Staff Members', Rev. 3), the work and training objectives to be achieved during the probation period shall be specified in writing to all new staff members during an induction interview. The interview shall take place between the new staff member and his supervisor within six weeks of him taking up his duties at the latest. https://edh.cern.ch/Document/MAPS/Induction (or from the EDH desktop, by clicking on 'Other Tasks' and going to the 'HR & Training' heading) Please note that this form is to be used exclusively for new staff members. A separate EDH form will be developed for fellows. Information technology Department, AIS (Administrative Information Services) Group Human...

  9. Experimental study on heat exchange of several types of exchangers

    Institute of Scientific and Technical Information of China (English)

    周志华; 赵振华; 于洋

    2009-01-01

    Aiming at the ground-coupled source heat pump that possesses the shortcomings of occupying larger land,this article studies the heat exchanged of heat exchanger in piling,and compares it with common heat exchangers buried directly. The result indicates that the heat exchanger makes the best use of structure of building,saves land,reduces the construction cost,and the heat exchanged is obviously more than exchangers buried directly. In winter condition,when W-shape pipe heat exchanger in pile foundation is 50 m deep and diameter is 800 mm,it transfers 1.2-1.3 times as large as the one of single U-shape buried directly at the flow rate of 0.6 m/s,whose borehole diameter is 300 mm. And in summer condition it does about 2.0-2.3 times as that of U-shape one.

  10. Closed inductively coupled plasma cell

    Science.gov (United States)

    Manning, Thomas J.; Palmer, Byron A.; Hof, Douglas E.

    1990-01-01

    A closed inductively coupled plasma cell generates a relatively high power, low noise plasma for use in spectroscopic studies. A variety of gases can be selected to form the plasma to minimize spectroscopic interference and to provide a electron density and temperature range for the sample to be analyzed. Grounded conductors are placed at the tube ends and axially displaced from the inductive coil, whereby the resulting electromagnetic field acts to elongate the plasma in the tube. Sample materials can be injected in the plasma to be excited for spectroscopy.

  11. Real Exchange Rate Targets, Nominal Exchange Rate Policies, and Inflation Real Exchange Rate Targets, Nominal Exchange Rate Policies, and Inflation

    Directory of Open Access Journals (Sweden)

    J. Saúl Lizondo

    1991-03-01

    Full Text Available Real Exchange Rate Targets, Nominal Exchange Rate Policies, and Inflation Thh paper examines the implications of some nominal exchange rate policies aimed or attaining a given real exchange rate target. A policy rule that sets the rate of nominal depreciation as a function of the departures of the real exchange rate from its target level is unable to achieve the target. In contrast, a policv rule that sets the change in the rate of depreciation as a function of those departures may lead the economy to the target, under certain conditions. However, this policy could also lead the economy to a process of accelerating inflation.

  12. Mastering Microsoft Exchange Server 2010

    CERN Document Server

    McBee, Jim

    2010-01-01

    A top-selling guide to Exchange Server-now fully updated for Exchange Server 2010. Keep your Microsoft messaging system up to date and protected with the very newest version, Exchange Server 2010, and this comprehensive guide. Whether you're upgrading from Exchange Server 2007 SP1 or earlier, installing for the first time, or migrating from another system, this step-by-step guide provides the hands-on instruction, practical application, and real-world advice you need.: Explains Microsoft Exchange Server 2010, the latest release of Microsoft's messaging system that protects against spam and vir

  13. Integrated Foreign Exchange Risk Management

    DEFF Research Database (Denmark)

    Aabo, Tom; Høg, Esben; Kuhn, Jochen

    Empirical research has focused on export as a proxy for the exchange rate exposure and the use of foreign exchange derivatives as the instrument to deal with this exposure. This empirical study applies an integrated foreign exchange risk management approach with a particular focus on the role...... of import in medium-sized, manufacturing firms in Denmark (a small, open economy). We find a strong, negative relation between import and foreign exchange derivatives usage on the aggregate level. Our findings are consistent with the notion that firms use import to match the foreign exchange exposure...... created by foreign sales activities....

  14. Integrated Foreign Exchange Risk Management

    DEFF Research Database (Denmark)

    Aabo, Tom; Høg, Esben; Kuhn, Jochen

    Empirical research has focused on export as a proxy for the exchange rate exposure and the use of foreign exchange derivatives as the instrument to deal with this exposure. This empirical study applies an integrated foreign exchange risk management approach with a particular focus on the role...... of import in medium-sized, manufacturing firms in Denmark (a small, open economy). We find a strong, negative relation between import and foreign exchange derivatives usage on the aggregate level. Our findings are consistent with the notion that firms use import to match the foreign exchange exposure...

  15. A comparison between vital capacity induction and tidal breathing induction techniques for the induction of anesthesia and compound A production

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-jie; LI Yue; SUN Bo; WANG Chang-song; GONG Yu-lei; ZHOU Yan-mei; LI En-you

    2010-01-01

    Background Vital capacity induction and tidal breathing induction are currently administered for inhalation induction of anesthesia with sevoflurane. The aim of this study was to compare them using sevoflurane with respect to induction time,complications of inhalation induction, and compound A production in adult patients.Methods Fifty-one women with American Society of Anesthesiologists physical status Ⅰ-Ⅱ undergoing mammary gland tumorectomy were randomly assigned to receive either vital capacity induction or tidal breathing induction with 8% sevoflurane at 6 L/min followed by laryngeal mask airway insertion. Induction times, complications of inhalation induction,and vital signs were recorded. Inspired concentrations of compound A were assayed and sofnolime temperatures were monitored at one-minute intervals after sevoflurane administration.Results The time to loss of eyelash reflex was significantly shorter with the vital capacity induction technique than with the tidal breathing induction technique ((43.8±13.4) seconds vs. (70.8±16.4) seconds, respectively; P <0.01).Cardiovascular stability was similar in both groups. The incidence of complications was significantly less with the vital capacity induction technique than with the tidal breathing induction technique (7.7% vs. 32%, respectively; P <0.01).However, the mean and maximum concentrations of compound A during induction were significantly higher in the vital capacity group than those in the tidal breathing group (P <0.05); compound A concentration at the beginning of anesthesia maintenance was (40.73±10.83) ppm in the vital capacity group and (29.45±7.51) ppm in tidal breathing group (P=0.019).Conclusion For inhalation induction of anesthesia, the vital capacity induction was faster and produced fewer complications than that for tidal breathing induction, but increased compound A production in the circuit system.

  16. Determination of soil organic phosphorus exchange sensitivity

    Science.gov (United States)

    Shand, Charles; Wendler, Renate; Lumsdon, David; Cooper, Pat; George, Timothy; Brown, Lawrie; Giles, Courtney; Stutter, Marc; Menezes-Blackburn, Daniel; Zhang, Hao; Wearing, Catherine; Haygarth, Philip; Blackwell, Martin; Darch, Tegan

    2015-04-01

    Soils contain both organic and inorganic phosphorus (P) species in varying proportions. Studies have shown that many soils contain substantial amounts of inositol hexaphosphate (IHP) and there is much interest worldwide in developing strategies to make some use of this recalcitrant resource for plant growth to reduce P fertilizer inputs. Little is known about the preference of ion exchange processes in the solubilisation of organic vs inorganic P forms in soils, an important first step in making P forms bioavailable. Although they do not possess biotic functions, resins provides a simple means to deplete P forms in soil allowing investigation of exchange selectivity between inorganic and organic P forms. The aim of our work was to determine new understanding of exchange selectivity in soils and provide insight into potential depletion and plant uptake of soil phosphorus, with emphasis on organic forms such as IHP. For our study we used a Cambisol sampled from an agricultural area (Tayport) near Dundee in Scotland. The soil had a high Olsen (0.5 M sodium bicarbonate at pH 8.5) extractable P status (84 mg P/kg) and P-31 nuclear magnetic resonance analysis of its NaOH/EDTA extract showed it contained a substantial proportion of IHP (21 % of total extractable P). For resin extraction we used anion exchange resin sheets (4.17 cm each side) in bicarbonate form to minimise pH related solubilisation effects. We used 3.5 g of soil in 75 ml of water and added 1, 2 or 3 resin squares. After equilibration the resin squares were removed and replaced with fresh resin squares a further 3 times. Phosphorus was recovered from the resin sheets by elution with 0.25 M sulphuric acid and analysed by inductively coupled plasma spectroscopy to determine total P, and colorimetrically with malachite green to determine inorganic P with the remainder assigned to organic P. The data showed that the resin preferentially removed inorganic P and even after four sequential extractions little or

  17. State Health Facts - State Decisions on Exchanges

    Data.gov (United States)

    U.S. Department of Health & Human Services — State Decisions For Creating Health Insurance Exchanges, including Exchange Decision, Federal Approval Status, Structure of Exchange, and Type of Exchange.

  18. Teaching the Photoelectric Effect Inductively

    Science.gov (United States)

    Sokolowski, Andrzej

    2013-01-01

    Research has shown that students have difficulty understanding the underlying process of the photoelectric effect. Thus, this study sought to utilize an inductively situated lesson for teaching the photoelectric effect, hypothesizing that this type of enquiry would help learners delve deeper into the principles of the phenomenon and provide a…

  19. Experiments with an Induction Cooker

    Science.gov (United States)

    Zilavy, Peter

    2009-01-01

    The induction cooker is a common appliance nowadays. How does it work? Why is it not possible to use aluminium utensils with it? What experiments can be carried out with it (at different levels) and not only in physics lessons? Searching for the answers to these and other questions is the purpose of this article. (Contains 5 figures.)

  20. Direct-reading inductance meter

    Science.gov (United States)

    Kolbly, R. B.

    1977-01-01

    Meter indicates from 30 nH to 3 micro H. Reference inductor of 15 micro H is made by winding 50 turns of Number 26 Formvar wire on Micrometal type 50-2 (or equivalent) core. Circuit eliminates requirement for complex instrument compensation prior to taking coil inductance measurement and thus is as easy to operate as common ohmmeter.

  1. Low-inductance bus lines

    Science.gov (United States)

    Kernick, A.

    1977-01-01

    Laminated bus strips and bifilar litz cable connectors for high-power rectifiers, thrisistors, and transistors provide low inductance and eliminate electromagnetic interference in high-power circuits. These techniques offer significant cost advantages because of ease of assembly and consistent high quality of product. Effectiveness makes general usage in static power conversion likely.

  2. Mathematical Induction: Deductive Logic Perspective

    Science.gov (United States)

    Dogan, Hamide

    2016-01-01

    Many studies mentioned the deductive nature of Mathematical Induction (MI) proofs but almost all fell short in explaining its potential role in the formation of the misconceptions reported in the literature. This paper is the first of its kind looking at the misconceptions from the perspective of the abstract of the deductive logic from one's…

  3. Dirac Induction for loop groups

    NARCIS (Netherlands)

    Posthuma, H.

    2011-01-01

    Using a coset version of the cubic Dirac operators for affine Lie algebras, we give an algebraic construction of the Dirac induction homomorphism for loop group representations. With this, we prove a homogeneous generalization of the Weyl-Kac character formula and show compatibility with Dirac induc

  4. Plasma-heating by induction

    Science.gov (United States)

    Harrington, K.; Thorpe, M. L.

    1969-01-01

    Induction-heated plasma torch operates with an input of 1 Mw of direct current of which 71 percent is transferred to the plasma and the remainder is consumed by electrical losses in the system. Continuous operation of the torch should be possible for as long as 5,000 hours.

  5. Inductive logic on conceptual spaces

    NARCIS (Netherlands)

    Sznajder, Marta

    2017-01-01

    This thesis investigates the question of how conceptual frameworks influence inductive reasoning. A conceptual framework is a collection of concepts used for a particular purpose; we can think of it as a semantic environment in which observations, or evidence, are recorded, and beliefs are formed an

  6. Teaching Inductive Reasoning with Puzzles

    Science.gov (United States)

    Wanko, Jeffrey J.

    2017-01-01

    Working with language-independent logic structures can help students develop both inductive and deductive reasoning skills. The Japanese publisher Nikoli (with resources available both in print and online) produces a treasure trove of language-independent logic puzzles. The Nikoli print resources are mostly in Japanese, creating the extra…

  7. Yeast Interacting Proteins Database: YDL089W, YML008C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available rDNA repeat stability; null mutant causes increase in unequal sister-chromatid exchange; GFP-fusion protein...peat stability; null mutant causes increase in unequal sister-chromatid exchange; GFP-fusion protein localiz

  8. Small particle heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, A.J.

    1978-06-01

    A dispersion of small absorbing particles forms an ideal system to collect radiant energy, transform it to heat, and efficiently transfer the heat to a surrounding fluid. If the heated fluid is a pressurized gas, it can be passed through an expansion turbine to create useful mechanical energy. The most obvious application of this technique is its use in a solar collection system. In this case, the incoming sunlight is used to heat a compressed gas in an engine utilizing a Brayton cycle. The solar collection system may utilize high concentration as provided by a central receiver or parabolic dish, medium concentration from a linear collector, or possibly no concentration using a flat plate collector, if precautions were taken to reduce the heat losses. The same concept may be applied generally to non-solar heat exchangers. These may be of the type used to heat a gas from a combustion source, or in general as a gas to gas heat exchanger. The latter application may be limited to rather high temperature. Each of the above applications is discussed. First, a description of the concept is applied to a solar central-tower system. The general principles are described, including the optical and physical characteristics of the particles, the confinement of the gas-particle mixture, and the system considerations; the latter include the amount and type of particles, the receiver efficiency and the generation of the particles. The same considerations are reviewed for applications to linear trough and flat plate receivers. Finally, the use of small particles in non-solar heat exchangers is considered.

  9. Cryogenic regenerative heat exchangers

    CERN Document Server

    Ackermann, Robert A

    1997-01-01

    An in-depth survey of regenerative heat exchangers, this book chronicles the development and recent commercialization of regenerative devices for cryogenic applications. Chapters cover historical background, concepts, practical applications, design data, and numerical solutions, providing the latest information for engineers to develop advanced cryogenic machines. The discussions include insights into the operation of a regenerator; descriptions of the cyclic and fluid temperature distributions in a regenerator; data for various matrix geometries and materials, including coarse and fine bronze, stainless steel-woven wire mesh screens, and lead spheres; and unique operating features of cryocoolers that produce deviations from ideal regenerator theory.

  10. Real exchange rate fluctuations, endogenous tradability and exchange rate regime

    OpenAIRE

    Kanda Naknoi

    2005-01-01

    This paper, empirically and theoretically, studies variance decomposition of real exchange rate. We find that deviations from the law of one price for traded goods drive most real exchange rates. However, the relative price of nontraded goods is also important for some countries maintaining stable exchange rate. We propose an explanation based on dynamics of comparative advantage. Our model predicts that comovement of terms of trade and productivity differentials of the nontraded and the expo...

  11. Synthesis of Heat Exchanger Network Considering Multipass Exchangers

    Institute of Scientific and Technical Information of China (English)

    李绍军; 姚平经

    2001-01-01

    Many methods have been proposed for synthesis of heat exchanger networks in recent years, most of which consider single pass exchangers. In this study some evolutionary rules have been proposed for synthesis of multipass exchanger networks. The method is based on the heuristic that optimal networks should feature maximum energy recovery and have the minimum number of shells. The effectiveness of the developed evolutionary rules is demonstrated through some literature examples.

  12. Capital Flows, Exchange Rate Flexibility, and the Real Exchange Rate

    OpenAIRE

    Jean-Louis Combes; Patrick Plane; Tidiane Kinda

    2011-01-01

    This paper analyzes the impact of capital inflows and exchange rate flexibility on the real exchange rate in developing countries based on panel cointegration techniques. The results show that public and private flows are associated with a real exchange rate appreciation. Among private flows, portfolio investment has the highest appreciation effect-almost seven times that of foreign direct investment or bank loans-and private transfers have the lowest effect. Using a de facto measure of excha...

  13. The effect of partner-directed emotion in social exchange decision-making

    Directory of Open Access Journals (Sweden)

    Iveta eEimontaite

    2013-07-01

    Full Text Available Despite the prevalence of studies examining economic decision-making as a purely rational phenomenon, common sense suggests that emotions affect our decision-making particularly in a social context. To address the influence of emotions on economic decision-making, we manipulated opponent-directed emotions prior to engaging participants in two social exchange decision-making games (the Trust Game and the Prisoner’s Dilemma. Participants played both games with three different (fictional partners and their tendency to defect was measured. Prior to playing each game, participants exchanged handwritten essays with their partners, and subsequently exchanged evaluations of each essay. The essays and evaluations, read by the participant, were designed to induce either anger, sympathy or a neutral emotional response towards the confederate with whom they would then play the social exchange games. Galvanic skin conductance level showed enhanced physiological arousal during anger induction compared to both neutral and sympathy conditions. In both social exchange games, participants were most likely to defect against their partner after anger induction and least likely to defect after sympathy induction, with the neutral condition eliciting intermediate defection rates. This pattern was found to be strongest in participants exhibiting low cognitive control (as measured by a Go/no-Go task. The findings indicate that emotions felt towards another individual alter how one chooses to interact with them, and that this influence depends both on the specific emotion induced and the cognitive control of the individual.

  14. The effect of partner-directed emotion in social exchange decision-making.

    Science.gov (United States)

    Eimontaite, Iveta; Nicolle, Antoinette; Schindler, Igor; Goel, Vinod

    2013-01-01

    Despite the prevalence of studies examining economic decision-making as a purely rational phenomenon, common sense suggests that emotions affect our decision-making particularly in a social context. To explore the influence of emotions on economic decision-making, we manipulated opponent-directed emotions prior to engaging participants in two social exchange decision-making games (the Trust Game and the Prisoner's Dilemma). Participants played both games with three different (fictional) partners and their tendency to defect was measured. Prior to playing each game, participants exchanged handwritten "essays" with their partners, and subsequently exchanged evaluations of each essay. The essays and evaluations, read by the participant, were designed to induce either anger, sympathy, or a neutral emotional response toward the confederate with whom they would then play the social exchange games. Galvanic skin conductance level (SCL) showed enhanced physiological arousal during anger induction compared to both the neutral and sympathy conditions. In both social exchange games, participants were most likely to defect against their partner after anger induction and least likely to defect after sympathy induction, with the neutral condition eliciting intermediate defection rates. This pattern was found to be strongest in participants exhibiting low cognitive control (as measured by a Go/no-Go task). The findings indicate that emotions felt toward another individual alter how one chooses to interact with them, and that this influence depends both on the specific emotion induced and the cognitive control of the individual.

  15. Programming with Inductive and Co-Inductive Types

    Science.gov (United States)

    1992-01-27

    Lecture Notes in Computer Science 389, eds. D. H. Pitt, D. E. Rydeheard, P. Dybjer, A. M. Pitts, and A. Poign6...University of Edinburgh. 1987. [5] Thierry Coquand and Christine Paulin. Inductively defined types. In COLOG-88, Lecture Notes in Computer Science 417, eds...Computer Science, Lecture Notes in Computer Science 283, eds. D. H. Pitt, A. Poing6, and D. E. Rydeheard, pages 140-157. September 1987. [9] Tatsuya

  16. Interfacing heat exchanger network synthesis and detailed heat exchanger design

    Energy Technology Data Exchange (ETDEWEB)

    Polley, G.T.; Panjeh Shahi, M.H. (Manchester Univ. (United Kingdom). Inst. of Science and Technology)

    1991-11-01

    Current heat exchanger network synthesis targeting and design procedures involve the use of assumed stream heat transfer coefficients. However, during detailed heat exchanger design, allowable pressure drops are often the most critical factors. The result can be big differences between the exchanger sizes and costs anticipated by the network designer and those realised by the exchanger designer. This in turn prejudices any optimisation attempted at the network design stage. In this paper it is shown how allowable pressure drop can be used as a basis of network design and consistency between expectation and realisation achieved. (author).

  17. Induction generator-induction motor wind-powered pumping system

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, M.S.; Lyra, R.O.C.; Silva, S.R. [CPDEE - UFMG, Belo Horizonte (Brazil)

    1997-12-31

    The energy storage matter plays an important role in wind-electric conversion systems for isolated applications. Having that in mind, two different approaches can be basically considered: either the immediate conversion of the generated electric energy, as in a water pumping system or electric energy storage for later use, as in a battery charging system. Due to some features such as no need of an external reactive power source and, sometimes, a gearbox, permanent-magnet synchronous generators have been broadly used in low rated power isolated systems. Despite that, system performance can be affected when the generator is feeding an inductive load (e.g., an induction motor) under variable-speed-variable-frequency operational conditions. Since there is no effective flux control, motor overload may occur at high wind speeds. Thus, good system performance can be obtained through additional control devices which may increase system cost. Although being rugged and cheap, induction machines always work as a reactive power drain; therefore, they demand an external reactive power source. Considering that, reactive static compensators appear as an attractive alternative to the cost x performance problem. In addition to that, different control strategies can be used so that system performance can be improved.

  18. Flux Tracking Control of Induction Motors

    Institute of Scientific and Technical Information of China (English)

    LanLin; XiaowuMu; ChunxiaBu

    2004-01-01

    This paper deals with flux tracking control of induction motors. Firstly,we analyze convergency of non-homogeneous linear time-varying systems and a sufficient condition is given. Finally, the flux regulator of induction motors is discussed.

  19. Inductance Scaling of a Helicoil Using ALEGRA

    Science.gov (United States)

    2013-05-01

    5066 The inductance scaling of several helicoil configurations are investigated using the March 2011 release of the Sandia magnetohydrodynamics (MHD...inductance scaling of several helicoil configurations are investigated using the March 2011 release of the Sandia magnetohydrodynamics (MHD) code

  20. Sequent calculus proof systems for inductive definitions

    OpenAIRE

    Brotherston, James

    2006-01-01

    Inductive definitions are the most natural means by which to represent many families of structures occurring in mathematics and computer science, and their corresponding induction / recursion principles provide the fundamental proof techniques by which to reason about such families. This thesis studies formal proof systems for inductive definitions, as needed, e.g., for inductive proof support in automated theorem proving tools. The systems are formulated as sequent calculi for...

  1. Fixed Exchange Rates and Trade

    OpenAIRE

    Michael W. Klein; Jay C. Shambaugh

    2004-01-01

    A classic argument for a fixed exchange rate is its promotion of trade. Empirical support for this, however, is mixed. While one branch of research consistently shows a small negative effect of exchange rate volatility on trade, another, more recent, branch presents evidence of a large positive impact of currency unions on trade. This paper helps resolve this disconnect. Our results, which use a new data-based classification of fixed exchange rate regimes, show a large, significant effect of ...

  2. Developing bulk exchange spring magnets

    Energy Technology Data Exchange (ETDEWEB)

    Mccall, Scott K.; Kuntz, Joshua D.

    2017-06-27

    A method of making a bulk exchange spring magnet by providing a magnetically soft material, providing a hard magnetic material, and producing a composite of said magnetically soft material and said hard magnetic material to make the bulk exchange spring magnet. The step of producing a composite of magnetically soft material and hard magnetic material is accomplished by electrophoretic deposition of the magnetically soft material and the hard magnetic material to make the bulk exchange spring magnet.

  3. Exchange Rates, Innovations and Forecasting

    OpenAIRE

    Wolff, Christian C

    1987-01-01

    In this paper an ex-post forecasting experiment is performed on the basis of a version of the "news" model of exchange rate determination. A general finding is that the "news" formulation of monetary exchange rate models leads to relatively accurate ex post exchange rate forecasts. Often the results compare favourably with those obtained from the naive random walk forecasting rule. Thus, the evidence presented in this paper supports the argument that the 1983 finding by Meese and Rogoff (that...

  4. Structured Statistical Models of Inductive Reasoning

    Science.gov (United States)

    Kemp, Charles; Tenenbaum, Joshua B.

    2009-01-01

    Everyday inductive inferences are often guided by rich background knowledge. Formal models of induction should aim to incorporate this knowledge and should explain how different kinds of knowledge lead to the distinctive patterns of reasoning found in different inductive contexts. This article presents a Bayesian framework that attempts to meet…

  5. Online Monitoring of Induction Motors

    Energy Technology Data Exchange (ETDEWEB)

    McJunkin, Timothy R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lybeck, Nancy Jean [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-01-01

    The online monitoring of active components project, under the Advanced Instrumentation, Information, and Control Technologies Pathway of the Light Water Reactor Sustainability Program, researched diagnostic and prognostic models for alternating current induction motors (IM). Idaho National Laboratory (INL) worked with the Electric Power Research Institute (EPRI) to augment and revise the fault signatures previously implemented in the Asset Fault Signature Database of EPRI’s Fleet Wide Prognostic and Health Management (FW PHM) Suite software. Induction Motor diagnostic models were researched using the experimental data collected by Idaho State University. Prognostic models were explored in the set of literature and through a limited experiment with 40HP to seek the Remaining Useful Life Database of the FW PHM Suite.

  6. Teaching the photoelectric effect inductively

    Science.gov (United States)

    Sokolowski, Andrzej

    2013-01-01

    Research has shown that students have difficulty understanding the underlying process of the photoelectric effect. Thus, this study sought to utilize an inductively situated lesson for teaching the photoelectric effect, hypothesizing that this type of enquiry would help learners delve deeper into the principles of the phenomenon and provide a better background for its quantification. The lesson was conducted with a group of fifteen high-school physics students and a computerized simulated experiment was utilized as the medium for instruction. Students’ responses to a qualitative question about the role of a battery in the photoelectric circuit supported the hypothesis that the lesson was a valuable learning experience. This paper presents an outline for the inductively reasoned learning process.

  7. Induction studies with satellite data

    DEFF Research Database (Denmark)

    Olsen, Nils

    1999-01-01

    analysis of the geomagnetic field is performed, and the Q-response, which is the transfer function between the internal (induced) and the external (inducing) expansion coefficients is determined for a specific frequency. In the second approach, known as the geomagnetic depth sounding method, the C....... This paper reviews and discusses the possibilities for induction studies using high-precision magnetic measurements from low-altitude satellites. The different methods and various transfer functions are presented, with special emphasis on the differences in analysing data from ground stations and from...... satellites. The results of several induction studies with scalar satellite data (from the POGO satellites) and with vector data (from the Magsat mission) demonstrate the ability to probe the Earth's conductivity from space. However, compared to the results obtained with ground data the satellite results...

  8. The performance of induction levitators

    Science.gov (United States)

    Eastham, J. F.; Rodger, D.

    1984-09-01

    The present investigation is concerned with the performance of induction levitators, which are employed in vehicles for contactless transport systems, utilizing magnetic levitation (Maglev). A small model (38 cm long) of an induction levitator is shown. The armature consists of a laminated 'u' shaped iron yoke. Around the limbs of the yoke are wound two primary excitation coils carrying single phase 50 Hz current. Eddy currents, induced in the conducting secondary, produce a force of repulsion between secondary and yoke. A lateral stabilizing force can also be obtained. A description is presented of a study of the characteristics of these forces. Attention is given of a finite element model and the application of the Galerkin weighted residual technique, experimental and calculated results, and a design study of two single phase levitators for a 50 tonne Maglev vehicle.

  9. Theoretical investigation of exchange bias

    Institute of Scientific and Technical Information of China (English)

    Xiong Zhi-Jie; Wang Huai-Yu; Ding Ze-Jun

    2007-01-01

    The exchange bias of bilayer magnetic films consisting of ferromagnetic (FM) and antiferromagnetic (AFM) layers in an uncompensated case is studied by use of the many-body Green's function method of quantum statistical theory.The effects of the layer thickness and temperature and the interfacial coupling strength on the exchange bias HE are investigated. The dependence of the exchange bias HE on the FM layer thickness and temperature is qualitatively in agreement with experimental results. When temperature varies, both the coercivity HC and HE decrease with the temperature increasing. For each FM thickness, there exists a least AFM thickness in which the exchange bias occurs,which is called pinning thickness.

  10. Mastering Microsoft Exchange Server 2013

    CERN Document Server

    Elfassy, David

    2013-01-01

    The bestselling guide to Exchange Server, fully updated for the newest version Microsoft Exchange Server 2013 is touted as a solution for lowering the total cost of ownership, whether deployed on-premises or in the cloud. Like the earlier editions, this comprehensive guide covers every aspect of installing, configuring, and managing this multifaceted collaboration system. It offers Windows systems administrators and consultants a complete tutorial and reference, ideal for anyone installing Exchange Server for the first time or those migrating from an earlier Exchange Server version.Microsoft

  11. Data Exchange in Grid Workflow

    Institute of Scientific and Technical Information of China (English)

    ZENG Hongwei; MIAO Huaikou

    2006-01-01

    In existing web services-based workflow, data exchanging across the web services is centralized, the workflow engine intermediates at each step of the application sequence.However, many grid applications, especially data intensive scientific applications, require exchanging large amount of data across the grid services.Having a central workfiow engine relay the data between the services would results in a bottleneck in these cases.This paper proposes a data exchange model for individual grid workflow and multiworkflows composition respectively.The model enables direct communication for large amounts of data between two grid services.To enable data to exchange among multiple workflows, the bridge data service is used.

  12. Inductive shearing of drilling pipe

    Energy Technology Data Exchange (ETDEWEB)

    Ludtka, Gerard M.; Wilgen, John; Kisner, Roger; Mcintyre, Timothy

    2016-04-19

    Induction shearing may be used to cut a drillpipe at an undersea well. Electromagnetic rings may be built into a blow-out preventer (BOP) at the seafloor. The electromagnetic rings create a magnetic field through the drillpipe and may transfer sufficient energy to change the state of the metal drillpipe to shear the drillpipe. After shearing the drillpipe, the drillpipe may be sealed to prevent further leakage of well contents.

  13. Induction and Mutually Obstructing Equilibria

    OpenAIRE

    Hahn, Dorothea; Liu, Mario

    2004-01-01

    A unified, consistent and simple view of the Faraday law of induction is presented, which consists of two points: discriminating the lab- from the rest-frame electric field and understanding it is the impossibility for both fields to vanish simultaneously, which generates and maintains the circular current. A number of illustrative examples are considered, including a mechano-electric pendulum to exhibit periodic and reversible conversion between electrical and mechanical energy.

  14. Inductive, Analogical, and Communicative Generalization

    Directory of Open Access Journals (Sweden)

    Adri Smaling

    2003-03-01

    Full Text Available Three forms of inductive generalization - statistical generalization, variation-based generalization and theory-carried generalization - are insufficient concerning case-to-case generalization, which is a form of analogical generalization. The quality of case-to-case generalization needs to be reinforced by setting up explicit analogical argumentation. To evaluate analogical argumentation six criteria are discussed. Good analogical reasoning is an indispensable support to forms of communicative generalization - receptive and responsive (participative generalization — as well as exemplary generalization.

  15. Inductive shearing of drilling pipe

    Science.gov (United States)

    Ludtka, Gerard M.; Wilgen, John; Kisner, Roger; Mcintyre, Timothy

    2016-04-19

    Induction shearing may be used to cut a drillpipe at an undersea well. Electromagnetic rings may be built into a blow-out preventer (BOP) at the seafloor. The electromagnetic rings create a magnetic field through the drillpipe and may transfer sufficient energy to change the state of the metal drillpipe to shear the drillpipe. After shearing the drillpipe, the drillpipe may be sealed to prevent further leakage of well contents.

  16. The law of electromagnetic induction

    Directory of Open Access Journals (Sweden)

    V.J. Kutkovetskyy

    2014-09-01

    Full Text Available Mathematical models of the electromagnetic induction law which do not take into account Faraday’s restrictions are not in full accordance with the physical phenomenon and so they are not laws. Their incomplete correspondence with real devices results in such "paradoxes" as unlimited magnetic field of unipolar generators, infinite sizes of inductors for DC and AC machines modeled, and so on.

  17. First-Year Undergraduate Induction: Who Attends and How Important Is Induction for First Year Attainment?

    Science.gov (United States)

    Murtagh, S.; Ridley, A.; Frings, D.; Kerr-Pertic, S.

    2017-01-01

    The first year of study in higher education is a time of major transition for students. While the importance of induction has been widely demonstrated, there is evidence to suggest that not all students benefit equally from participation in induction. This study examined attendance rates at induction, the relationship between induction attendance…

  18. The Radioecology Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, Catherine L.; Beresford, Nicholas A.; Patel, Sabera; Wells, Claire; Howard, Brenda J. [NERC Centre for Ecology and Hydrology, CEH Lancaster, Lancaster Environment Centre, Library Av., Bailrigg, Lancaster, LA1 4AP (United Kingdom); Mora, Juan Carlos; Real, Almudena [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avenida complutense 22, Madrid, 28040 (Spain); Beaugelin-Seiller, Karine; Gilbin, Rodolphe; Hinton, Thomas [IRSN-Institut de Radioprotection et de Surete Nucleaire, 31, Avenue de la Division Leclerc, 92260 Fontenay-Aux-Roses (France); Vesterbacka, Pia; Muikku, Maarit; Outola, Iisa [Radiation and Nuclear Safety Authority, P.O. Box 14, FI-00881 Helsinki (Finland); Skuterud, Lavrans; AlbumYtre-Eide, Martin [Norwegian Radiation Protection Authority, Grini Naeringspark 13, Oesteraas, 1332 (Norway); Bradshaw, Clare; Stark, Karolina; Jaeschke, Ben [Stockholms Universitet, Universitetsvaegen 10, Stockholm, 10691 (Sweden); Oughton, Deborah; Skipperud, Lindis [NMBU Norwegian University of Life Science P.O. Box 5003N-1432 Aas, Oslo (Norway); Vandenhove, Hildegarde; Vanhoudt, Nathalie [SCK.CEN, Studiecentrum voor Kernenergie/Centre d' Etude de l' Energie Nucleaire, Avenue Herrmann-Debroux 40, BE-1160 Brussels (Belgium); Willrodt, Christine; Steiner, Martin [Bundesamt fuer Strahlenschutz, Willy-Brandt-Strasse 5, 38226 Salzgitter (Germany)

    2014-07-01

    The Radioecology Exchange (www.radioecology-exchange.org) was created in 2011 under the EU FP7 STAR (Strategy for Allied Radioecology) network of excellence. The project aims to integrate the research efforts on radioecology of nine European organisations into a sustainable network. The web site (together with associated Twitter feeds and Facebook page) currently provides the gateway to project outputs and other on-line radiation protection and radioecological resources. In 2013, the EU FP7 COMET (Coordination and implementation of a pan-European instrument for radioecology) project commenced; it aims to strengthen research on the impact of radiation on man and the environment. COMET includes the STAR partners with the addition of one Japanese and two Ukrainian research institutes. As STAR and COMET interact closely together and with the European Radioecology Alliance (www.er-alliance.org/), the Radioecology Exchange will be modified to become an international 'hub' for information related to radioecology. Project specific information will be hosted on separate web sites www.star-radioecology.org and www.comet-radioecology.org. This paper will present an overview of the resources hosted on the Radioecology Exchange inviting other scientists to contribute. Highlighted aspects of the site include: Social media (News blog, Twitter, Facebook) - Items announcing project outputs, training courses, jobs, studentships etc. Virtual laboratory - Information which encourages integration through joint research and integrated use of data and sample materials. These pages will focus on three categories: (1) Methodological: descriptions and video clips of commonly used analytical methods and protocols and the procedures used in STAR and COMET; (2) Informative: databases made available by STAR/COMET partners together with details of sample archives held. Fact-sheets on radio-ecologically important radionuclides and 'topical descriptions' which show absorbed

  19. Asymmetric exchange in flocks

    CERN Document Server

    Dadhichi, Lokrshi Prawar; Maitra, Ananyo; Ramaswamy, Sriram

    2016-01-01

    As the constituents of a flock are polar, one expects a fore-aft asymmetry in their interactions. We show here that the resulting antisymmetric part of the "exchange coupling" between a bird and its neighbours, if large enough, destabilizes the flock through spontaneous turning of the birds. The same asymmetry also yields a natural mechanism for a difference between the speed of advection of information along the flock and the speed of the flock itself. We show that the absence of detailed balance, and not merely the breaking of Galilean invariance, is responsible for this difference. We delineate the conditions on parameters and wavenumber for the existence of the turning instability. Lastly we present an alternative perspective based on flow-alignment effects in an active liquid crystal with turning inertia in contact with a momentum sink.

  20. Hybrid Heat Exchangers

    Science.gov (United States)

    Tu, Jianping Gene; Shih, Wei

    2010-01-01

    A hybrid light-weight heat exchanger concept has been developed that uses high-conductivity carbon-carbon (C-C) composites as the heat-transfer fins and uses conventional high-temperature metals, such as Inconel, nickel, and titanium as the parting sheets to meet leakage and structural requirements. In order to maximize thermal conductivity, the majority of carbon fiber is aligned in the fin direction resulting in 300 W/m.K or higher conductivity in the fin directions. As a result of this fiber orientation, the coefficient of thermal expansion (CTE) of the C-C composite in both non-fiber directions matches well with the CTE of various high-temperature metal alloys. This allows the joining of fins and parting sheets by using high-temperature braze alloys.

  1. Determination of Trace Nickel in Bi-Based Superconductor Powder by Inductively Coupled Plasma Atomic Emission Spectroscopy after Separation with Anion Exchange Resin and Extraction with Methylbenzene%阴离子交换树脂分离甲苯萃取ICP-AES测定铋系超导粉中的痕量镍

    Institute of Scientific and Technical Information of China (English)

    范丽新; 李建强; 范慧俐; 孙建伶; 张霞; 包蕊; 陆青; 王杰

    2011-01-01

    A new method for the determination of trace nickel in superconductor powder by ICP-AES was proposed. The instrument parameters were optimized) and the matrix effects as well as the method of eliminating interferences were also studied sys-temically. The results showed that matrix interference in the superconductor powder was serious when the amount of matrix increased, and the repeatability as well as the accuracy was poor, so it was necessary to used separation and preconcentration to improve the accuracy and precision. In this experiment, Ni-diacetyl dioxime complexes were enriched by toluene extraction in alkaline condition after eliminating the interference of major element Bi and partial Pb, Sr, Ca and Cu by eluting with anion exchange resin, then the Ni-complexes were back extracted by diluted hydrochloric acid. The enrichment conditions were investigated in detail and the recovery rate of Ni was higher than 95%. Under the optimal condition, an artificial sample was analysed, the result showed that the found values were identical with reference values, and the RSD and detection limit were 1. 9% and 0.19 μg ? g-1, respectively. The method has been applied to the determination of trace nickel in Bi-based superconductor powder samples with satisfactory results.%建立了ICP-AES测定超导粉中痕量镍的新方法.优化了仪器工作参数,对超导前驱粉中痕量镍测定时的基体干扰及干扰消除方法进行了系统研究,结果表明:大量存在的基体元素产生严重基体效应,导致测定重现性及准确度变差,实验采用分离富集方法以提高测定结果的准确度和精密度.实验中首先用阴离子交换树脂,除去Bi3+及部分pb2+,Sr2+,Ca2+,Cu2十等基体元素;在碱性条件下再通过甲苯萃取镍与丁二酮肟的络合物、稀盐酸反萃取富集镍;对分离富集条件进行了优化.对模拟标准样品进行测定,分析结果与理论值一致,相对标准偏差为1.9%,方法检出限为0

  2. Inductance of rf-wave-heated plasmas.

    Science.gov (United States)

    Farshi, E; Todo, Y

    2003-03-14

    The inductance of rf-wave-heated plasmas is derived. This inductance represents the inductance of fast electrons located in a plateau during their acceleration due to electric field or deceleration due to collisions and electric field. This inductance has been calculated for small electric fields from the two-dimensional Fokker-Planck equation as the flux crossing the surface of critical energy mv(2)(ph)/2 in the velocity space. The new expression may be important for radio-frequency current drive ramp-up, current drive efficiency, current profile control, and so on in tokamaks. This inductance may be incorporated into transport codes that study plasma heating by rf waves.

  3. PERMANENT-MAGNET INDUCTION GENERATORS: AN OVERVIEW

    Directory of Open Access Journals (Sweden)

    K. S. S. RAMAKRISHNAN

    2011-06-01

    Full Text Available The advantage of using a permanent-magnet induction generator (PMIG instead of a conventional induction generator is its ability to suppress inrush current during system linking when synchronous input is performed. Induction machines excited with permanent-magnet (PM are called permanent-magnet induction generators. This paper presents an exhaustive survey of the literature discussing the classification of permanent-magnet machines, process of permanent-magnet excitation and voltage build-up, modelling, steady-state and performance analysis of the permanent-magnet induction generators.

  4. Modelling Of Chlorine Inductive Discharges

    Science.gov (United States)

    Chabert P.; Despiau-Pujo, E.

    2010-07-01

    III-V compounds such as GaAs, InP or GaN-based materials are increasingly important for their use in optoelectronic applications, especially in the telecommunications and light detection industries. Photonic devices including lasers, photodetectors or LEDs, require reliable etching processes characterized by high etch rate, profile control and low damage. Although many problems remain to be understood, inductively coupled discharges seem to be promising to etch such materials, using Cl2/Ar, Cl2/N2 and Cl2/H2 gas chemistries. Inductively coupled plasma (ICP) sources meet most of the requirements for efficient plasma processing such as high etch rates, high ion densities and low controllable ion energies. However, the presence of a negative ion population in the plasma alters the positive ion flux, reduces the electron density, changes the electron temperature, modifies the spatial structure of the discharge and can cause unstable operation. Several experimental studies and numerical simulation results have been published on inductively coupled Cl2/Ar plasmas but relatively few systematic comparisons of model predictions and experimental data have been reported in given reactor geometries under a wide range of op- erating conditions. Validation of numerical predictions is essential for chemically complex plasma processing and there is a need to benchmark the models with as many measurements as possible. In this paper, comparisons of 2D fluid simulations with experimental measurements of Ar/Cl2 plasmas in a low pressure ICP reactor are reported (Corr et al. 2008). The electron density, negative ion fraction and Cl atom density are investigated for various conditions of Ar/Cl2 ratio, gas pressure and applied RF power in H mode. Simulations show that the wall recombination coefficient of Cl atom (?) is a key parameter of the model and that neutral densities are very sensitive to its variations. The best agreement between model and experiment is obtained for ? = 0

  5. An induction linac developed for FEL application

    Science.gov (United States)

    de Mascureau, J.; Anthouard, Ph.; Bardy, J.; Eyharts, Ph.; Eyl, P.; Launspach, J.; Thevenot, M.; Villate, D.

    1992-07-01

    An induction linac is being studied and built at CESTA for FEL application. At first we studied the induction technology and namely the high-voltage (HV) generators and the induction cells. A HV generator designed to feed the cells with calibrated pulses (150 kV, 50 ns, δV/V magnetic switches. This generator is planned for kHz repetition-rate operation. A prototype induction cell has also been built and tested with a cable generator. An electron injector (1.5 MeV, 1.5kA) has been designed and is now under test: it uses ten induction cells and a thermionic dispenser cathode. Numerical codes have been developed and simulations have been compared with experimental results for HV generators, induction cells, and the injector. An induction accelerating module has been studied and we plan to have the accelerator working at 3 MeV in 1992.

  6. Liquid/liquid heat exchanger

    Science.gov (United States)

    Miller, C. G.

    1980-01-01

    Conceptual design for heat exchanger, utilizing two immiscible liquids with dissimilar specific gravities in direct contact, is more efficient mechanism of heat transfer than conventional heat exchangers with walls or membranes. Concept could be adapted for collection of heat from solar or geothermal sources.

  7. Educators Exchange: A Program Evaluation.

    Science.gov (United States)

    Armstrong, William B.

    The Educators Exchange Program (EEP) was established under a training and educational exchange agreement reached by California's San Diego Community College District (SDCCD) and the republic of Mexico. In the program, the District provided a 4-week technological training program to faculty at Centros de Capacitacion Tecnologica Industrial…

  8. Macroreticular chelating ion-exchangers.

    Science.gov (United States)

    Hirsch, R F; E Gancher, R; Russo, F R

    1970-06-01

    Two macroreticular chelating ion-exchangers have been prepared and characterized. One contains the iminodiacetate group and the second contains the arsonate group as the ion-exchanging site. The macroreticular resins show selectivities among metal ions similar to those of the commercially available naicroreticular chelating resins. Chromatographie separations on the new resins are rapid and sharp.

  9. Social exchange : Relations and networks

    NARCIS (Netherlands)

    Dijkstra, Jacob

    2015-01-01

    In this short paper, I review the literature on social exchange networks, with specific attention to theoretical and experimental research. I indicate how social exchange theory is rooted in general social theory and mention a few of its main links to social network analysis and empirical network re

  10. Exchange Rates and Old People.

    Science.gov (United States)

    Dowd, James J.

    1980-01-01

    Extends earlier work on aging as a process of exchange by focusing on the issue of exchange rates and how they are negotiated. Access to power resources declines with age, placing the old person in the position of negotiating from weakness. (Author)

  11. Value Appropriation in Business Exchange

    DEFF Research Database (Denmark)

    Ellegaard, Chris; Medlin, Christopher J.; Geersbro, Jens

    2014-01-01

    Purpose – Value appropriation is a central, yet neglected aspect in business exchange research. The purpose of the paper is to generate an overview of research on active value appropriation in business exchange and provide the foundation for further research into value appropriation, as well as s...

  12. EXCHANGE. Volume 9-92

    Energy Technology Data Exchange (ETDEWEB)

    Boltz, J.C. [ed.

    1992-09-01

    EXCHANGE is published monthly by the Idaho National Engineering Laboratory (INEL), a multidisciplinary facility operated for the US Department of Energy (DOE). The purpose of EXCHANGE is to inform computer users about about recent changes and innovations in both the mainframe and personal computer environments and how these changes can affect work being performed at DOE facilities.

  13. DN interaction from meson exchange

    NARCIS (Netherlands)

    Haidenbauer, J.; Krein, G.; Meiner, U. -G.; Tolos, L.

    A model of the DN interaction is presented which is developed in close analogy to the meson-exchange (K) over barN potential of the Julich group utilizing SU(4) symmetry constraints. The main ingredients of the interaction are provided by vector meson (rho, omega) exchange and higher-order box

  14. Next Generation Microchannel Heat Exchangers

    CERN Document Server

    Ohadi, Michael; Dessiatoun, Serguei; Cetegen, Edvin

    2013-01-01

    In Next Generation Microchannel Heat Exchangers, the authors’ focus on the new generation highly efficient heat exchangers and presentation of novel data and technical expertise not available in the open literature.  Next generation micro channels offer record high heat transfer coefficients with pressure drops much less than conventional micro channel heat exchangers. These inherent features promise fast penetration into many mew markets, including high heat flux cooling of electronics, waste heat recovery and energy efficiency enhancement applications, alternative energy systems, as well as applications in mass exchangers and chemical reactor systems. The combination of up to the minute research findings and technical know-how make this book very timely as the search for high performance heat and mass exchangers that can cut costs in materials consumption intensifies.

  15. Heat exchanger leakage problem location

    Directory of Open Access Journals (Sweden)

    Jícha Miroslav

    2012-04-01

    Full Text Available Recent compact heat exchangers are very often assembled from numerous parts joined together to separate heat transfer fluids and to form the required heat exchanger arrangement. Therefore, the leak tightness is very important property of the compact heat exchangers. Although, the compact heat exchangers have been produced for many years, there are still technological problems associated with manufacturing of the ideal connection between the individual parts, mainly encountered with special purpose heat exchangers, e.g. gas turbine recuperators. This paper describes a procedure used to identify the leakage location inside the prime surface gas turbine recuperator. For this purpose, an analytical model of the leaky gas turbine recuperator was created to assess its performance. The results obtained are compared with the experimental data which were acquired during the recuperator thermal performance analysis. The differences between these two data sets are used to indicate possible leakage areas.

  16. High Temperature Heat Exchanger Project

    Energy Technology Data Exchange (ETDEWEB)

    Anthony E. Hechanova, Ph.D.

    2008-09-30

    The UNLV Research Foundation assembled a research consortium for high temperature heat exchanger design and materials compatibility and performance comprised of university and private industry partners under the auspices of the US DOE-NE Nuclear Hydrogen Initiative in October 2003. The objectives of the consortium were to conduct investigations of candidate materials for high temperature heat exchanger componets in hydrogen production processes and design and perform prototypical testing of heat exchangers. The initial research of the consortium focused on the intermediate heat exchanger (located between the nuclear reactor and hydrogen production plan) and the components for the hydrogen iodine decomposition process and sulfuric acid decomposition process. These heat exchanger components were deemed the most challenging from a materials performance and compatibility perspective

  17. Heat exchanger leakage problem location

    Science.gov (United States)

    Hejčík, Jiří; Jícha, Miroslav

    2012-04-01

    Recent compact heat exchangers are very often assembled from numerous parts joined together to separate heat transfer fluids and to form the required heat exchanger arrangement. Therefore, the leak tightness is very important property of the compact heat exchangers. Although, the compact heat exchangers have been produced for many years, there are still technological problems associated with manufacturing of the ideal connection between the individual parts, mainly encountered with special purpose heat exchangers, e.g. gas turbine recuperators. This paper describes a procedure used to identify the leakage location inside the prime surface gas turbine recuperator. For this purpose, an analytical model of the leaky gas turbine recuperator was created to assess its performance. The results obtained are compared with the experimental data which were acquired during the recuperator thermal performance analysis. The differences between these two data sets are used to indicate possible leakage areas.

  18. Fault-Tolerant Heat Exchanger

    Science.gov (United States)

    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.

  19. Numerical Modelling of Induction Heating for a Molten Salts Pyrochemical Process

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Xuan-Tuyen; Feraud, Jean-Pierre; Ode, Denis [CEA Marcoule: DTEC/SGCS/LGCI Bat. 57 B17171, 30207 Bagnols/Ceze (France); Du Terrail Couvat, Yves [SIMaP, Grenoble INP, CNRS: ENSEEG, BP 75, 38402 Saint Martin d' Heres Cedex (France)

    2008-07-01

    Technological developments in the pyro-chemistry program are required to allow choices for a reprocessing experiment on 100 g of spent nuclear fuel. In this context, a special device must be designed for the solid/gas reaction phases followed by actinide extraction and stripping in molten salt. This paper discusses a modelling approach for designing an induction furnace. Using this numerical approach is a good way to improve thermal performance of the device in terms of magnetic/thermal coupling phenomena. The influence of current frequency is also studied to give another view of the possibilities of an induction furnace. Electromagnetic forces are taken into account in a computational fluid dynamics code derived from a specifically developed exchange library. Induction heating systems are an example of a typical multi-physics problem involving numerically coupled equations. (authors)

  20. Lessons for Inductive Germline Determination

    Science.gov (United States)

    Seervai, Riyad N.H.; Wessel, Gary M.

    2015-01-01

    SUMMARY Formation of the germline in an embryo marks a fresh round of reproductive potential, yet the developmental stage and location within the embryo where the primordial germ cells (PGCs) form differs wildly among species. In most animals, the germline is formed either by an inherited mechanism, in which maternal provisions within the oocyte drive localized germ-cell fate once acquired in the embryo, or an inductive mechanism that involves signaling between cells that directs germ-cell fate. The inherited mechanism has been widely studied in model organisms such as Drosophila melanogaster, Caenorhabditis elegans, Xenopus laevis, and Danio rerio. Given the rapid generation time and the effective adaptation for laboratory research of these organisms, it is not coincidental that research on these organisms has led the field in elucidating mechanisms for germline specification. The inductive mechanism, however, is less well understood and is studied primarily in the mouse (Mus musculus). In this review, we compare and contrast these two fundamental mechanisms for germline determination, beginning with the key molecular determinants that play a role in the formation of germ cells across all animal taxa. We next explore the current understanding of the inductive mechanism of germ-cell determination in mice, and evaluate the hypotheses for selective pressures on these contrasting mechanisms. We then discuss the hypothesis that the transition between these determination mechanisms, which has happened many times in phylogeny, is more of a continuum than a binary change. Finally, we propose an analogy between germline determination and sex determination in vertebrates—two of the milestones of reproduction and development—in which animals use contrasting strategies to activate similar pathways. PMID:23450642

  1. Lessons for inductive germline determination.

    Science.gov (United States)

    Seervai, Riyad N H; Wessel, Gary M

    2013-08-01

    Formation of the germline in an embryo marks a fresh round of reproductive potential, yet the developmental stage and location within the embryo where the primordial germ cells (PGCs) form differs wildly among species. In most animals, the germline is formed either by an inherited mechanism, in which maternal provisions within the oocyte drive localized germ-cell fate once acquired in the embryo, or an inductive mechanism that involves signaling between cells that directs germ-cell fate. The inherited mechanism has been widely studied in model organisms such as Drosophila melanogaster, Caenorhabditis elegans, Xenopus laevis, and Danio rerio. Given the rapid generation time and the effective adaptation for laboratory research of these organisms, it is not coincidental that research on these organisms has led the field in elucidating mechanisms for germline specification. The inductive mechanism, however, is less well understood and is studied primarily in the mouse (Mus musculus). In this review, we compare and contrast these two fundamental mechanisms for germline determination, beginning with the key molecular determinants that play a role in the formation of germ cells across all animal taxa. We next explore the current understanding of the inductive mechanism of germ-cell determination in mice, and evaluate the hypotheses for selective pressures on these contrasting mechanisms. We then discuss the hypothesis that the transition between these determination mechanisms, which has happened many times in phylogeny, is more of a continuum than a binary change. Finally, we propose an analogy between germline determination and sex determination in vertebrates-two of the milestones of reproduction and development-in which animals use contrasting strategies to activate similar pathways.

  2. Electrically switched ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Lilga, M.A. [Pacific Northwest National Lab., Richland, WA (United States); Schwartz, D.T.; Genders, D.

    1997-10-01

    A variety of waste types containing radioactive {sup 137}Cs are found throughout the DOE complex. These waste types include water in reactor cooling basins, radioactive high-level waste (HLW) in underground storage tanks, and groundwater. Safety and regulatory requirements and economics require the removal of radiocesium before these wastes can be permanently disposed of. Electrically Switched Ion Exchange (ESIX) is an approach for radioactive cesium separation that combines IX and electrochemistry to provide a selective, reversible, and economic separation method that also produces little or no secondary waste. In the ESIX process, an electroactive IX film is deposited electrochemically onto a high-surface area electrode, and ion uptake and elution are controlled directly by modulating the potential of the film. For cesium, the electroactive films under investigation are ferrocyanides, which are well known to have high selectivities for cesium in concentrated sodium solutions. When a cathode potential is applied to the film, Fe{sup +3} is reduced to the Fe{sup +2} state, and a cation must be intercalated into the film to maintain charge neutrality (i.e., Cs{sup +} is loaded). Conversely, if an anodic potential is applied, a cation must be released from the film (i.e., Cs{sup +} is unloaded). Therefore, to load the film with cesium, the film is simply reduced; to unload cesium, the film is oxidized.

  3. Energy-Exchange Project

    Energy Technology Data Exchange (ETDEWEB)

    1982-04-01

    The purpose of the study was to determine what energy savings can be achieved by coordinating the resources and requirements of two facilities, the 26th Ward Water Pollution Control Plant (WPCP) and a housing development named Starrett City with its own total energy system. It was determined that three energy exchange options were economically and technically feasible. These include: the transfer of digester gas produced at the 26th Ward to the boilers at the Starrett City's total energy plant (TEP); the transfer of hot water heated at the TEP to the 26th Ward for space and process heating; and the transfer of coal effluent waste water from the 26th Ward to the condenser cooling systems at the TEP. Technical information is presented to support the findings. The report addresses those tasks of the statement of work dedicated to data acquisition, analysis, and energy conservation strategies internal to the Starrett City TEP and the community it supplies as well as to the 26th Ward WPCP. (MCW)

  4. Elementary induction on abstract structures

    CERN Document Server

    Moschovakis, Yiannis N

    2008-01-01

    Hailed by the Bulletin of the American Mathematical Society as ""easy to use and a pleasure to read,"" this research monograph is recommended for students and professionals interested in model theory and definability theory. The sole prerequisite is a familiarity with the basics of logic, model theory, and set theory.The author, Professor of Mathematics at UCLA and Emeritus Professor of Mathematics,University of Athens, Greece, begins with a focus on the theory of inductive and hyperelementary sets. Subsequent chapters advance to acceptable structures and countable acceptable structures, concl

  5. Mathematical model of induction heating

    Science.gov (United States)

    Rak, Josef

    2017-07-01

    One of mathematical models of induction heating can be described by a parabolic differential equation with the specific Joule looses in the body. Advantage of this method is that the detailed knowledge of the 3D-magnetic field is not necessary and move of the body or the inductor can be easily implemented. The specific Joule looses can computed by solving the Fredholm integral equation of the second kind for the eddy current of density by the Nyström method with the singularity subtraction.

  6. Induction brazing of complex joints

    DEFF Research Database (Denmark)

    Henningsen, Poul; Zhang, Wenqi; Bay, Niels

    2003-01-01

    , or if the hottest area is located outside the joint interface, a number of defects may appear: the braze metal may flow away from the joint, the flux may burn off, poor binding of the braze metal may appear or the braze metal may be overheated. Joint geometry as well as electro-magnetic properties of the work piece......Induction brazing is a fast and appropriate method for industrial joining of complex geometries and metal combinations. In all types of brazing processes it is important to heat the joint interface of the two materials to the same, high temperature. If one of the specimens is warmer than the other...

  7. Induction brazing of complex joints

    DEFF Research Database (Denmark)

    Henningsen, Poul; Zhang, Wenqi; Bay, Niels

    2003-01-01

    Induction brazing is a fast and appropriate method for industrial joining of complex geometries and metal combinations. In all types of brazing processes it is important to heat the joint interface of the two materials to the same, high temperature. If one of the specimens is warmer than the other......, or if the hottest area is located outside the joint interface, a number of defects may appear: the braze metal may flow away from the joint, the flux may burn off, poor binding of the braze metal may appear or the braze metal may be overheated. Joint geometry as well as electro-magnetic properties of the work piece...

  8. Lipase Induction in Mucor hiemalis

    OpenAIRE

    Akhtar, M. Waheed; Mirza, A. Q.; Chughtai, M. I. D.

    1980-01-01

    The influence on lipase induction in Mucor hiemalis of different types of triglycerides containing mainly oleic acid (olive oil), erucic acid (mustard oil), or saturated fatty acids of 8 to 16 carbons (coconut oil) was studied. The fungus was grown in shake flasks in a fermentation medium containing peptone, minerals, and glucose or one of the oils as the carbon source. Maximum lipase was produced when the initial pH of the fermentation medium was kept at 4.0. Addition of Ca2+ to the medium d...

  9. Custom, contract, and kidney exchange.

    Science.gov (United States)

    Healy, Kieran; Krawiec, Kimberly D

    2012-01-01

    In this Essay, we examine a case in which the organizational and logistical demands of a novel form of organ exchange (the nonsimultaneous, extended, altruistic donor (NEAD) chain) do not map cleanly onto standard cultural schemas for either market or gift exchange, resulting in sociological ambiguity and legal uncertainty. In some ways, a NEAD chain resembles a form of generalized exchange, an ancient and widespread instance of the norm of reciprocity that can be thought of simply as the obligation to “pay it forward” rather than the obligation to reciprocate directly with the original giver. At the same time, a NEAD chain resembles a string of promises and commitments to deliver something in exchange for some valuable consideration--that is, a series of contracts. Neither of these salient "social imaginaries" of exchange--gift giving or formal contract--perfectly meets the practical demands of the NEAD system. As a result, neither contract nor generalized exchange drives the practice of NEAD chains. Rather, the majority of actual exchanges still resemble a simpler form of exchange: direct, simultaneous exchange between parties with no time delay or opportunity to back out. If NEAD chains are to reach their full promise for large-scale, nonsimultaneous organ transfer, legal uncertainties and sociological ambiguities must be finessed, both in the practices of the coordinating agencies and in the minds of NEAD-chain participants. This might happen either through the further elaboration of gift-like language and practices, or through a creative use of the cultural form and motivational vocabulary, but not necessarily the legal and institutional machinery, of contract.

  10. Effect of polyamine reagents on exchange capacity in ion exchangers

    Science.gov (United States)

    Petrova, T. I.; Dyachenko, F. V.; Bogatyreva, Yu. V.; Borodastov, A. K.; Ershova, I. S.

    2016-05-01

    Effect of compounds involved in complex reagents is described using Helamin 906H reagent as an example. The working exchange capacity of KU-2-8chs cation exchanger in hydrogen form and Amberlite IRA 900Cl anion exchanger in OH form remained almost unchanged when they were used repeatedly to purify water that contained Helamin 906H reagent; in addition, this capacity was the same upon filtration of water that did not contain this reagent. Leakage of total organic carbon was observed earlier than that of calcium ions upon filtration of the solution through the cation exchanger layer. The test results obtained in industrial conditions indicated that using H-OH filters to purify turbine condensate enables the decrease of the concentration of organic and other impurities therein.

  11. Supersonic induction plasma jet modeling

    Energy Technology Data Exchange (ETDEWEB)

    Selezneva, S.E. E-mail: svetlana2@hermes.usherbS_Selezneva2@hermes.usherb; Boulos, M.I

    2001-06-01

    Numerical simulations have been applied to study the argon plasma flow downstream of the induction plasma torch. It is shown that by means of the convergent-divergent nozzle adjustment and chamber pressure reduction, a supersonic plasma jet can be obtained. We investigate the supersonic and a more traditional subsonic plasma jets impinging onto a normal substrate. Comparing to the subsonic jet, the supersonic one is narrower and much faster. Near-substrate velocity and temperature boundary layers are thinner, so the heat flux near the stagnation point is higher in the supersonic jet. The supersonic plasma jet is characterized by the electron overpopulation and the domination of the recombination over the dissociation, resulting into the heating of the electron gas. Because of these processes, the supersonic induction plasma permits to separate spatially different functions (dissociation and ionization, transport and deposition) and to optimize each of them. The considered configuration can be advantageous in some industrial applications, such as plasma-assisted chemical vapor deposition of diamond and polymer-like films and in plasma spraying of nanoscaled powders.

  12. Inductive reasoning in Alzheimer's disease.

    Science.gov (United States)

    Smith, E E; Rhee, J; Dennis, K; Grossman, M

    2001-12-01

    We evaluated knowledge of basic level and superordinate semantic relations and the role of cognitive resources during inductive reasoning in probable Alzheimer's disease (AD). Nineteen mildly demented AD patients and 17 healthy control subjects judged the truthfulness of arguments with a premise and a conclusion that contain familiar concepts coupled with "blank" predicates, such as "Spiders contain phosphatidylcholine; therefore all insects contain phosphatidylcholine." Like healthy control subjects, AD patients were relatively insensitive to the typicality of the premise category when judging the strength of arguments with a conclusion containing a basic-level concept, but were relatively sensitive to typicality during judgments of arguments containing a superordinate in the conclusion. Moreover, AD patients resembled control subjects in judging arguments with an immediate superordinate in the conclusion compared to arguments with a distant superordinate. AD patients differed from control subjects because they could not take advantage of two premises in an argument containing basic-level concepts. We conclude that semantic knowledge is sufficiently preserved in AD to support inductive reasoning, but that limited cognitive resources may interfere with AD patients' ability to consider the entire spectrum of information available during semantic challenges.

  13. Exchange Rate Deregulation and Industrial Performance: An ...

    African Journals Online (AJOL)

    FIRST LADY

    Key Words: Exchange Rate, Deregulation, Industrial Performance, Co- integration ... and exchange risk there from. In fact ... factors underscore the importance of exchange rate to the economic well being of ..... Wearing. Apparel, Footwear,.

  14. Hear Exchange Assembly

    Science.gov (United States)

    Lowenstein, Andrew; Sibilia, Marc; Miller, Jeffrey; Tonon, Thomas S.

    2003-05-27

    A heat exchange assembly comprises a plurality of plates disposed in a spaced-apart arrangement, each of the plurality of plates includes a plurality of passages extending internally from a first end to a second end for directing flow of a heat transfer fluid in a first plane, a plurality of first end-piece members equaling the number of plates and a plurality of second end-piece members also equaling the number of plates, each of the first and second end-piece members including a recessed region adapted to fluidly connect and couple with the first and second ends of the plate, respectively, and further adapted to be affixed to respective adjacent first and second end-piece members in a stacked formation, and each of the first and second end-piece members further including at least one cavity for enabling entry of the heat transfer fluid into the plate, exit of the heat transfer fluid from the plate, or 180.degree. turning of the fluid within the plate to create a serpentine-like fluid flow path between points of entry and exit of the fluid, and at least two fluid conduits extending through the stacked plurality of first and second end-piece members for providing first fluid connections between the parallel fluid entry points of adjacent plates and a fluid supply inlet, and second fluid connections between the parallel fluid exit points of adjacent plates and a fluid discharge outlet so that the heat transfer fluid travels in parallel paths through each respective plate.

  15. Heat exchanger using graphite foam

    Science.gov (United States)

    Campagna, Michael Joseph; Callas, James John

    2012-09-25

    A heat exchanger is disclosed. The heat exchanger may have an inlet configured to receive a first fluid and an outlet configured to discharge the first fluid. The heat exchanger may further have at least one passageway configured to conduct the first fluid from the inlet to the outlet. The at least one passageway may be composed of a graphite foam and a layer of graphite material on the exterior of the graphite foam. The layer of graphite material may form at least a partial barrier between the first fluid and a second fluid external to the at least one passageway.

  16. Monitoring transients in low inductance circuits

    Science.gov (United States)

    Guilford, R.P.; Rosborough, J.R.

    1985-10-21

    The instant invention relates to methods of and apparatus for monitoring transients in low inductance circuits and to a probe utilized to practice said method and apparatus. More particularly, the instant invention relates to methods of and apparatus for monitoring low inductance circuits, wherein the low inductance circuits include a pair of flat cable transmission lines. The instant invention is further directed to a probe for use in monitoring pairs of flat cable transmission lines.

  17. The Automation Of Proof By Mathematical Induction

    OpenAIRE

    Bundy, Alan

    1999-01-01

    This paper is a chapter of the Handbook of Automated Reasoning edited by Voronkov and Robinson. It describes techniques for automated reasoning in theories containing rules of mathematical induction. Firstly, inductive reasoning is defined and its importance fore reasoning about any form of repitition is stressed. Then the special search problems that arise in inductive theories are explained followed by descriptions of the heuristic methods that have been devised to solve these problems. ...

  18. Productive Use of Failure in Inductive Proof

    OpenAIRE

    Ireland, A.; Bundy, Alan

    1996-01-01

    Proof by mathematical induction gives rise to various kinds of eureka steps, e.g., missing lemmata and generalization. Most inductive theorem provers rely upon user intervention in supplying the required eureka steps. In contrast, we present a novel theorem-proving architecture for supporting the automatic discovery of eureka steps. We build upon rippling, a search control heuristic designed for inductive reasoning. We show how the failure if rippling can be used in bridging gaps in the searc...

  19. Prostaglandin E, pessaries for induction of labour.

    Science.gov (United States)

    Pearce, J M; Shepherd, J H; Sims, C D

    1979-03-17

    Vaginal pessaries containing 3 mg of prostaglandin E2 were used to induce labour in 200 patients with variable induction features. Prostaglandin-induced labour was augmented where necessary by synthetic oxytocin. There was on failed induction. Only 23% of patients with favourable induction features and 53% of patients with unfavourable features needed oxytocin. There were no adverse fetal or maternal effects. The prostaglandin E2 pessary was as effective in inducing labour as 350 microgram extra-amniotic prostaglandin E2 in tylose in a comparable group of 200 patients in which there were 4 failed inductions.

  20. Inductive voltage divider modeling in Matlab

    Science.gov (United States)

    Andreev, S. A.; Kim, V. L.

    2017-01-01

    Inductive voltage dividers have the most appropriate metrological characteristics on alternative current and are widely used for converting physical signals. The model of a double-decade inductive voltage divider was designed with the help of Matlab/Simulink. The first decade is an inductive voltage divider with balanced winding, the second decade is a single-stage inductive voltage divider. In the paper, a new transfer function algorithm was given. The study shows errors and differences that appeared between the third degree reduced model and a twenty degree unreduced model. The obtained results of amplitude error differ no more than by 7 % between the reduced and unreduced model.

  1. Experimental demonstration of the induction synchrotron.

    Science.gov (United States)

    Takayama, Ken; Arakida, Yoshio; Dixit, Tanuja; Iwashita, Taiki; Kono, Tadaaki; Nakamura, Eiji; Otsuka, Kazunori; Shimosaki, Yoshito; Torikai, Kota; Wake, Masayoshi

    2007-02-01

    We report an experimental demonstration of the induction synchrotron, the concept of which has been proposed as a future accelerator for the second generation of neutrino factory or hadron collider. The induction synchrotron supports a superbunch and a superbunch permits more charge to be accelerated while observing the constraints of the transverse space-charge limit. By using a newly developed induction acceleration system instead of radio-wave acceleration devices, a single proton bunch injected from the 500 MeV booster ring and captured by the barrier bucket created by the induction step voltages was accelerated to 6 GeV in the KEK proton synchrotron.

  2. Microsoft Exchange Server 2010 -palvelinprojekti

    OpenAIRE

    Loise, Niklas

    2011-01-01

    Tämän opinnäytetyön tavoitteena on tutkia kuinka, hyvin Exchange Server 2010 -sähköpostijärjestelmä pystyy vastaamaan Päijät-Hämeen koulutuskonsernin työntekijöiden asettamiin vaatimuksiin ja korvaamaan vanhan Novell GroupWise 8 -järjestelmän. Työssä selvitetään Exchange 2010:n uudet ominaisuudet ja tärkeimmät toiminnot. Exchange Server 2010 on Microsoftin viimeisin viestintäpalvelinratkaisu, joka sisältää sähköposti-, kalenteri-, yhteystieto- ja vastaajaratkaisut. Exchange 2010 toimii W...

  3. Counterflow Regolith Heat Exchanger Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The counterflow regolith heat exchanger (CoRHE) is a device that transfers heat from hot regolith to cold regolith. The CoRHE is essentially a tube-in-tube heat...

  4. Quantum Exchangeable Sequences of Algebras

    CERN Document Server

    Curran, Stephen

    2008-01-01

    We extend the notion of quantum exchangeability, introduced by K\\"ostler and Speicher in arXiv:0807.0677, to sequences (\\rho_1,\\rho_2,...c) of homomorphisms from an algebra C into a noncommutative probability space (A,\\phi), and prove a free de Finetti theorem: an infinite quantum exchangeable sequence (\\rho_1,\\rho_2,...c) is freely independent and identically distributed with respect to a conditional expectation. As a corollary we obtain a free analogue of the Hewitt Savage zero-one law. As in the classical case, the theorem fails for finite sequences. We give a characterization of finite quantum exchangeable sequences, which can be viewed as a noncommutative analogue of sampling without replacement. We then give an approximation to how far a finite quantum exchangeable sequence is from being freely independent with amalgamation.

  5. Exchange couplings in magnetic films

    Institute of Scientific and Technical Information of China (English)

    Liu Wei; Liu Xiong-Hua; Cui Wei-Bin; Gong Wen-Jie; Zhang Zhi-Dong

    2013-01-01

    Recent advances in the study of exchange couplings in magnetic films are introduced.To provide a comprehensive understanding of exchange coupling,we have designed different bilayers,trilayers and multilayers,such as anisotropic hard/soft-magnetic multilayer films,ferromagnetic/antiferromagnetic/ferromagnetic trilayers,[Pt/Co]/NiFe/NiO heterostructures,Co/NiO and Co/NiO/Fe trilayers on an anodic aluminum oxide (AAO) template.The exchange-coupling interaction between soft-and hard-magnetic phases,interlayer and interfacial exchange couplings and magnetic and magnetotransport properties in these magnetic films have been investigated in detail by adjusting the magnetic anisotropy of ferromagnetic layers and by changing the thickness of the spacer layer,ferromagnetic layer,and antiferromagnetic layer.Some particular physical phenomena have been observed and explained.

  6. VLER Health Exchange by Area

    Data.gov (United States)

    Department of Veterans Affairs — “Connect Your Docs” through the Virtual Lifetime Electronic Record (VLER) Health Exchange program. This program gives VA and community health care providers secure...

  7. Identifiability, exchangeability and confounding revisited

    OpenAIRE

    Greenland, Sander; Robins, James Matthew

    2009-01-01

    In 1986 the International Journal of Epidemiology published "Identifiability, Exchangeability and Epidemiological Confounding". We review the article from the perspective of a quarter century after it was first drafted and relate it to subsequent developments on confounding, ignorability, and collapsibility.

  8. Yuan Exchange Rate 'Properly Adjusted'

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

      The currency exchange rate was "properly adjusted" this year and takes into account effects on the country's neighbors and the world, Premier Wen Jiabao said at a regional meeting in Malaysia.……

  9. Estimating Foreign Exchange Reserve Adequacy

    Directory of Open Access Journals (Sweden)

    Abdul Hakim

    2013-04-01

    Full Text Available Accumulating foreign exchange reserves, despite their cost and their impacts on other macroeconomics variables, provides some benefits. This paper models such foreign exchange reserves. To measure the adequacy of foreign exchange reserves for import, it uses total reserves-to-import ratio (TRM. The chosen independent variables are gross domestic product growth, exchange rates, opportunity cost, and a dummy variable separating the pre and post 1997 Asian financial crisis. To estimate the risky TRM value, this paper uses conditional Value-at-Risk (VaR, with the help of Glosten-Jagannathan-Runkle (GJR model to estimate the conditional volatility. The results suggest that all independent variables significantly influence TRM. They also suggest that the short and long run volatilities are evident, with the additional evidence of asymmetric effects of negative and positive past shocks. The VaR, which are calculated assuming both normal and t distributions, provide similar results, namely violations in 2005 and 2008.

  10. Pu Anion Exchange Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

    Taylor-Pashow, K. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-08

    This project seeks to improve the efficiency of the plutonium anion-exchange process for purifying Pu through the development of alternate ion-exchange media. The objective of the project in FY15 was to develop and test a porous foam monolith material that could serve as a replacement for the current anion-exchange resin, Reillex® HPQ, used at the Savannah River Site (SRS) for purifying Pu. The new material provides advantages in efficiency over the current resin by the elimination of diffusive mass transport through large granular resin beads. By replacing the large resin beads with a porous foam there is much more efficient contact between the Pu solution and the anion-exchange sites present on the material. Several samples of a polystyrene based foam grafted with poly(4-vinylpyridine) were prepared and the Pu sorption was tested in batch contact tests.

  11. Anion exchange polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yu Seung; Kim, Dae Sik; Lee, Kwan-Soo

    2013-07-23

    Solid anion exchange polymer electrolytes and compositions comprising chemical compounds comprising a polymeric core, a spacer A, and a guanidine base, wherein said chemical compound is uniformly dispersed in a suitable solvent and has the structure: ##STR00001## wherein: i) A is a spacer having the structure O, S, SO.sub.2, --NH--, --N(CH.sub.2).sub.n, wherein n=1-10, --(CH.sub.2).sub.n--CH.sub.3--, wherein n=1-10, SO.sub.2-Ph, CO-Ph, ##STR00002## wherein R.sub.5, R.sub.6, R.sub.7 and R.sub.8 each are independently --H, --NH.sub.2, F, Cl, Br, CN, or a C.sub.1-C.sub.6 alkyl group, or any combination of thereof; ii) R.sub.9, R.sub.10, R.sub.11, R.sub.12, or R.sub.13 each independently are --H, --CH.sub.3, --NH.sub.2, --NO, --CH.sub.nCH.sub.3 where n=1-6, HC.dbd.O--, NH.sub.2C.dbd.O--, --CH.sub.nCOOH where n=1-6, --(CH.sub.2).sub.n--C(NH.sub.2)--COOH where n=1-6, --CH--(COOH)--CH.sub.2--COOH, --CH.sub.2--CH(O--CH.sub.2CH.sub.3).sub.2, --(C.dbd.S)--NH.sub.2, --(C.dbd.NH)--N--(CH.sub.2).sub.nCH.sub.3, where n=0-6, --NH--(C.dbd.S)--SH, --CH.sub.2--(C.dbd.O)--O--C(CH.sub.3).sub.3, --O--(CH.sub.2).sub.n--CH--(NH.sub.2)--COOH, where n=1-6, --(CH.sub.2).sub.n--CH.dbd.CH wherein n=1-6, --(CH.sub.2).sub.n--CH--CN wherein n=1-6, an aromatic group such as a phenyl, benzyl, phenoxy, methylbenzyl, nitrogen-substituted benzyl or phenyl groups, a halide, or halide-substituted methyl groups; and iii) wherein the composition is suitable for use in a membrane electrode assembly.

  12. Universality in the stock exchange

    CERN Document Server

    Gonçalves, Rui

    2008-01-01

    We analyze the constituents stocks of the Dow Jones Industrial Average and the Standard & Poor's 100 index of the NYSE stock exchange market. Surprisingly, we discovered that the distribution of the fluctuations of the cubic root of the squared daily return are close to the universal non-parametric Bramwell-Holdsworth-Pinton (BHP) distribution. Since the BHP probability density function appears in several other dissimilar phenomena, our result reveals an universal feature of the stock exchange market.

  13. Shared Year Exchange in Nursing

    DEFF Research Database (Denmark)

    Vedsegaard, Helle Wendner; Wederkinck, Elisabeth

    2010-01-01

    Beskrivelse af Shared Year Exchange in Nursing, et udviklingsporjekt omhandlende udvikling, beskrivelse og implementering af et fælles studieår for sygeplejerskestuderende ved Metropol og La Trobe University Australien.......Beskrivelse af Shared Year Exchange in Nursing, et udviklingsporjekt omhandlende udvikling, beskrivelse og implementering af et fælles studieår for sygeplejerskestuderende ved Metropol og La Trobe University Australien....

  14. The Biological Effectiveness of Four Energies of Neon Ions for the Induction of Chromosome Damage in Human Lymphocytes

    Science.gov (United States)

    George, Kerry; Hada, Megumi; Cucinotta, F. A.

    2011-01-01

    Chromosomal aberrations were measured in human peripheral blood lymphocytes after in vitro exposure to neon ions at energies of 64, 89, 142, or 267. The corresponding LET values for these energies of neon ranged from 38-103 keV/micrometers and doses delivered were in the 10 to 80 cGy range. Chromosome exchanges were assessed in metaphase and G2 phase cells at first division after exposure using fluorescence in situ hybridization (FISH) with whole chromosome probes and dose response curves were generated for different types of chromosomal exchanges. The yields of total chromosome exchanges were similar for the 64, 89, and 142 MeV exposures, whereas the 267 MeV/u neon with LET of 38 keV/micrometers produced about half as many exchanges per unit dose. The induction of complex type chromosome exchanges (exchanges involving three or more breaks and two or more chromosomes) showed a clear LET dependence for all energies. The ratio of simple to complex type exchanges increased with LET from 18 to 51%. The relative biological effectiveness (RBE) was estimated from the initial slope of the dose response curve for chromosome damage with respect to gamma-rays. The RBE(sub max) values for total chromosome exchanges for the 64 MeV/u was around 30.

  15. Teaching Mathematical Induction: An Alternative Approach.

    Science.gov (United States)

    Allen, Lucas G.

    2001-01-01

    Describes experience using a new approach to teaching induction that was developed by the Mathematical Methods in High School Project. The basic idea behind the new approach is to use induction to prove that two formulas, one in recursive form and the other in a closed or explicit form, will always agree for whole numbers. (KHR)

  16. Eisenstein integrals and induction of relations

    NARCIS (Netherlands)

    Ban, E.P. van den

    2004-01-01

    A survey of joint work with Henrik Schlichtkrull on the induction of certain relations among (partial) Eisenstein integrals for the minimal principal series of a reductive symmetric space is given. The application of this principle of induction to the proof of the Fourier inversion formula in [11] a

  17. Induction methods used in low temperature physics

    NARCIS (Netherlands)

    van de Klundert, L.J.M.; de Rooij, C.; Caspari, M.; van der Marel, L.C.

    1975-01-01

    A study has been made of induction bridges used in low temperature physics. In Part 1 the design of a mutual inductance bridge of the Hartshorn type is discussed. This design is based on a critical analysis of impurity effects of the different parts of the Hartshorn bridge. With this equipment

  18. A Philosophical Treatise of Universal Induction

    Directory of Open Access Journals (Sweden)

    Samuel Rathmanner

    2011-06-01

    Full Text Available Understanding inductive reasoning is a problem that has engaged mankind for thousands of years. This problem is relevant to a wide range of fields and is integral to the philosophy of science. It has been tackled by many great minds ranging from philosophers to scientists to mathematicians, and more recently computer scientists. In this article we argue the case for Solomonoff Induction, a formal inductive framework which combines algorithmic information theory with the Bayesian framework. Although it achieves excellent theoretical results and is based on solid philosophical foundations, the requisite technical knowledge necessary for understanding this framework has caused it to remain largely unknown and unappreciated in the wider scientific community. The main contribution of this article is to convey Solomonoff induction and its related concepts in a generally accessible form with the aim of bridging this current technical gap. In the process we examine the major historical contributions that have led to the formulation of Solomonoff Induction as well as criticisms of Solomonoff and induction in general. In particular we examine how Solomonoff induction addresses many issues that have plagued other inductive systems, such as the black ravens paradox and the confirmation problem, and compare this approach with other recent approaches.

  19. A Framework of Mathematics Inductive Reasoning

    Science.gov (United States)

    Christou, Constantinos; Papageorgiou, Eleni

    2007-01-01

    Based on a synthesis of the literature in inductive reasoning, a framework for prescribing and assessing mathematics inductive reasoning of primary school students was formulated and validated. The major constructs incorporated in this framework were students' cognitive abilities of finding similarities and/or dissimilarities among attributes and…

  20. Turning Norton's Dome Against Material Induction

    Science.gov (United States)

    Dawid, Richard

    2015-09-01

    John Norton has proposed a position of "material induction" that denies the existence of a universal inductive inference schema behind scientific reasoning. In this vein, Norton has recently presented a "dome scenario" based on Newtonian physics that, in his understanding, is at variance with Bayesianism. The present note points out that a closer analysis of the dome scenario reveals incompatibilities with material inductivism itself.

  1. Math Activities that Encourage Inductive Thinking

    Science.gov (United States)

    Freeman, Christopher

    2005-01-01

    There are two kinds of logical reasoning: "inductive" and "deductive". Inductive reasoning proceeds from effect back to cause, from special case to general principle. Detectives use it, examining the clues and conjecturing the actions that caused them. On the other hand, deductive reasoning proceeds from cause to effect, from principle to…

  2. The Tower of Hanoi and Inductive Logic

    Science.gov (United States)

    Merrotsy, Peter

    2015-01-01

    In the "Australian Curriculum," the concept of mathematical induction is first met in the senior secondary subject Specialist Mathematics. This article details an example, the Tower of Hanoi problem, which provides an enactive introduction to the inductive process before moving to more abstract and cognitively demanding representations.…

  3. Nominal exchange rate flexibility and real exchange rate adjustment : evidence from dual exchange rates in developing countries

    OpenAIRE

    Cheung, Yin-Wong; Lai, Kon-Sun

    2005-01-01

    This study investigates whether exchange rate flexibility aids real exchange rate adjustment based on intra-period data on dual exchange rates from developing countries. Specifically, it analyzes whether the flexible parallel market rate produces faster or slower real exchange rate adjustment than the much less flexible official rate does. Half-life estimates of adjustment speeds are obtained using fractional time series analysis. We find no systematic evidence that greater exchange rate flex...

  4. Arsenic Induction of Metallothionein and Metallothionein Induction Against Arsenic Cytotoxicity.

    Science.gov (United States)

    Rahman, Mohammad Tariqur; De Ley, Marc

    Human exposure to arsenic (As) can lead to oxidative stress that can become evident in organs such as the skin, liver, kidneys and lungs. Several intracellular antioxidant defense mechanisms including glutathione (GSH) and metallothionein (MT) have been shown to minimize As cytotoxicity. The current review summarizes the involvement of MT as an intracellular defense mechanism against As cytotoxicity, mostly in blood. Zinc (Zn) and selenium (Se) supplements are also proposed as a possible remediation of As cytotoxicity. In vivo and in vitro studies on As toxicity were reviewed to summarize cytotoxic mechanisms of As. Intracellular antioxidant defense mechanisms of MT are linked in relation to As cytotoxicity. Arsenic uses a different route, compared to major metal MT inducers such as Zn, to enter/exit blood cells. A number of in vivo and in vitro studies showed that upregulated MT biosynthesis in blood components are related to toxic levels of As. Despite the cysteine residues in MT that aid to bind As, MT is not the preferred binding protein for As. Nonetheless, intracellular oxidative stress due to As toxicity can be minimized, if not eliminated, by MT. Thus MT induction by essential metals such as Zn and Se supplementation could be beneficial to fight against As toxicity.

  5. Reasoning about modular datatypes with Mendler induction

    Directory of Open Access Journals (Sweden)

    Paolo Torrini

    2015-09-01

    Full Text Available In functional programming, datatypes a la carte provide a convenient modular representation of recursive datatypes, based on their initial algebra semantics. Unfortunately it is highly challenging to implement this technique in proof assistants that are based on type theory, like Coq. The reason is that it involves type definitions, such as those of type-level fixpoint operators, that are not strictly positive. The known work-around of impredicative encodings is problematic, insofar as it impedes conventional inductive reasoning. Weak induction principles can be used instead, but they considerably complicate proofs. This paper proposes a novel and simpler technique to reason inductively about impredicative encodings, based on Mendler-style induction. This technique involves dispensing with dependent induction, ensuring that datatypes can be lifted to predicates and relying on relational formulations. A case study on proving subject reduction for structural operational semantics illustrates that the approach enables modular proofs, and that these proofs are essentially similar to conventional ones.

  6. 22 CFR 41.62 - Exchange visitors.

    Science.gov (United States)

    2010-04-01

    ... NATIONALITY ACT, AS AMENDED Students and Exchange Visitors § 41.62 Exchange visitors. (a) J-1 classification. An alien is classifiable as an exchange visitor if qualified under the provisions of INA 101(a) (15... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Exchange visitors. 41.62 Section 41.62 Foreign...

  7. Hartree potential dependent exchange functional

    CERN Document Server

    Constantin, L A; Della Sala, F

    2016-01-01

    We introduce a novel non-local ingredient for the construction of exchange density functionals: the reduced Hartree parameter, which is invariant under the uniform scaling of the density and represents the exact exchange enhancement factor for one- and two-electron systems. The reduced Hartree parameter is used together with the conventional meta-generalized gradient approximation (meta-GGA) semilocal ingredients (i.e. the electron density, its gradient and the kinetic energy density) to construct a new generation exchange functional, termed u-meta-GGA. This u-meta-GGA functional is exact for {the exchange of} any one- and two-electron systems, is size-consistent and non-empirical, satisfies the uniform density scaling relation, and recovers the modified gradient expansion derived from the semiclassical atom theory. For atoms, ions, jellium spheres, and molecules, it shows a good accuracy, being often better than meta-GGA exchange functionals. Our construction validates the use of the reduced Hartree ingredie...

  8. Fair Exchange in Strand Spaces

    Directory of Open Access Journals (Sweden)

    Joshua D. Guttman

    2009-10-01

    Full Text Available Many cryptographic protocols are intended to coordinate state changes among principals. Exchange protocols coordinate delivery of new values to the participants, e.g. additions to the set of values they possess. An exchange protocol is fair if it ensures that delivery of new values is balanced: If one participant obtains a new possession via the protocol, then all other participants will, too. Fair exchange requires progress assumptions, unlike some other protocol properties. The strand space model is a framework for design and verification of cryptographic protocols. A strand is a local behavior of a single principal in a single session of a protocol. A bundle is a partially ordered global execution built from protocol strands and adversary activities. The strand space model needs two additions for fair exchange protocols. First, we regard the state as a multiset of facts, and we allow strands to cause changes in this state via multiset rewriting. Second, progress assumptions stipulate that some channels are resilient-and guaranteed to deliver messages-and some principals are assumed not to stop at certain critical steps. This method leads to proofs of correctness that cleanly separate protocol properties, such as authentication and confidentiality, from invariants governing state evolution. G. Wang's recent fair exchange protocol illustrates the approach.

  9. Electrically Switched Cesium Ion Exchange

    Energy Technology Data Exchange (ETDEWEB)

    JPH Sukamto; ML Lilga; RK Orth

    1998-10-23

    This report discusses the results of work to develop Electrically Switched Ion Exchange (ESIX) for separations of ions from waste streams relevant to DOE site clean-up. ESIX combines ion exchange and electrochemistry to provide a selective, reversible method for radionuclide separation that lowers costs and minimizes secondary waste generation typically associated with conventional ion exchange. In the ESIX process, an electroactive ion exchange film is deposited onto. a high surface area electrode, and ion uptake and elution are controlled directly by modulating the potential of the film. As a result, the production of secondary waste is minimized, since the large volumes of solution associated with elution, wash, and regeneration cycles typical of standard ion exchange are not needed for the ESIX process. The document is presented in two parts: Part I, the Summary Report, discusses the objectives of the project, describes the ESIX concept and the approach taken, and summarizes the major results; Part II, the Technology Description, provides a technical description of the experimental procedures and in-depth discussions on modeling, case studies, and cost comparisons between ESIX and currently used technologies.

  10. Exchange-Correlation Effects for Noncovalent Interactions in Density Functional Theory.

    Science.gov (United States)

    Otero-de-la-Roza, A; DiLabio, Gino A; Johnson, Erin R

    2016-07-12

    In this article, we develop an understanding of how errors from exchange-correlation functionals affect the modeling of noncovalent interactions in dispersion-corrected density-functional theory. Computed CCSD(T) reference binding energies for a collection of small-molecule clusters are decomposed via a molecular many-body expansion and are used to benchmark density-functional approximations, including the effect of semilocal approximation, exact-exchange admixture, and range separation. Three sources of error are identified. Repulsion error arises from the choice of semilocal functional approximation. This error affects intermolecular repulsions and is present in all n-body exchange-repulsion energies with a sign that alternates with the order n of the interaction. Delocalization error is independent of the choice of semilocal functional but does depend on the exact exchange fraction. Delocalization error misrepresents the induction energies, leading to overbinding in all induction n-body terms, and underestimates the electrostatic contribution to the 2-body energies. Deformation error affects only monomer relaxation (deformation) energies and behaves similarly to bond-dissociation energy errors. Delocalization and deformation errors affect systems with significant intermolecular orbital interactions (e.g., hydrogen- and halogen-bonded systems), whereas repulsion error is ubiquitous. Many-body errors from the underlying exchange-correlation functional greatly exceed in general the magnitude of the many-body dispersion energy term. A functional built to accurately model noncovalent interactions must contain a dispersion correction, semilocal exchange, and correlation components that minimize the repulsion error independently and must also incorporate exact exchange in such a way that delocalization error is absent.

  11. Transendothelial lipoprotein exchange and microalbuminuria

    DEFF Research Database (Denmark)

    Jensen, Jan Skov; Feldt-Rasmussen, Bo; Jensen, Kurt Svarre

    2004-01-01

    OBJECTIVE: Microalbuminuria associates with increased risk of atherosclerosis in individuals without diabetes. We hypothesized that transendothelial lipoprotein exchange is elevated among such individuals, possibly explaining increased intimal lipoprotein accumulation and thus atherosclerosis....... METHODS: Using an in vivo isotope technique, transendothelial exchange of low density lipoprotein (LDL) was measured in 77 non-diabetic individuals. Autologous 131-iodinated LDL was reinjected intravenously, and the 1-h fractional escape rate was calculated as index of transendothelial exchange. RESULTS...... transformed) plasma insulin: beta=0.6 (95% CI: 0.1-1.1); R=0.22; Plipoproteins, LDL size, body mass index, plasma volume, and use of medicine, and it was unlikely caused by altered hepatic LDL receptor expression...

  12. Inductive cooling in quantum magnetomechanics

    Science.gov (United States)

    Romero-Sanchez, Erick; Twamley, Jason; Bowen, Warwick P.; Vanner, Michael R.

    Coupling to light or microwave fields allows quantum control of the motion of a mechanical oscillator, and offers prospects for precision sensing, quantum information systems, and tests of fundamental physics. In cavity electromechanics ground state cooling has been achieved using resolved sideband cooling. Here we present an alternative approach based on a magnetomechanical system that inductively couples an LC resonator to a mechanical oscillator. The experimental setup consists of a micro cantilever with a pyramidal magnetic tip attached at the end of the beam. The sharp end of the magnetic tip is positioned close to the planar microfabricated inductor of the LC resonator. The displacement in the position of the end of the cantilever generates a change in flux through the coil inducing an electromotive force in the circuit. The current in the LC resonator generates a magnetic field, and then a force between the tip and the coil. When they are strongly coupled and the mechanical resonance frequency ωm exceeds the electrical decay rate of the resonator γe, resolved sideband cooling can be used to cool the mechanics. We present estimations for the coupling rates and the experimental parameters required for these experiments. E. Romero acknowledges to CONACyT.

  13. Graph-based inductive reasoning.

    Science.gov (United States)

    Boumans, Marcel

    2016-10-01

    This article discusses methods of inductive inferences that are methods of visualizations designed in such a way that the "eye" can be employed as a reliable tool for judgment. The term "eye" is used as a stand-in for visual cognition and perceptual processing. In this paper "meaningfulness" has a particular meaning, namely accuracy, which is closeness to truth. Accuracy consists of precision and unbiasedness. Precision is dealt with by statistical methods, but for unbiasedness one needs expert judgment. The common view at the beginning of the twentieth century was to make the most efficient use of this kind of judgment by representing the data in shapes and forms in such a way that the "eye" can function as a reliable judge to reduce bias. The need for judgment of the "eye" is even more necessary when the background conditions of the observations are heterogeneous. Statistical procedures require a certain minimal level of homogeneity, but the "eye" does not. The "eye" is an adequate tool for assessing topological similarities when, due to heterogeneity of the data, metric assessment is not possible. In fact, graphical assessments precedes measurement, or to put it more forcefully, the graphic method is a necessary prerequisite for measurement.

  14. Induction technique in manufacturing preforms

    Science.gov (United States)

    Frauenhofer, M.; Ströhlein, T.; Fabig, S.; Böhm, S.; Herbeck, L.; Dilger, K.

    2008-09-01

    The prepreg technology is a state-of-the-art method to produce high-performance CFRP parts. Due to the high material prices, the restricted process rate, and limitations to the component complexity, in future, more and more parts will be assembled by using liquid composite moulding. Especially in the case of series larger than 100 parts per year, the LCM technology offers the best cost-effectiveness. This technology is based on resin injection into dry multilayer fibre textiles (preforms). The Institute of Joining and Welding (TU, Braunschweig), together with the Institute of Composite Structures and Adaptive Systems (DLR), has elaborated a new technology to speed up the preform process, which is the most labour-intensive step within the LCM process chain. A novel concept to consolidate binder-coated fabrics is under development. By applying the high energy transfer rate of induction technology, it is possible to heat up a preform with rates up to 50 K/s to melt the binder and consolidate the preform.

  15. Inflationary trispectrum from graviton exchange

    DEFF Research Database (Denmark)

    Seery, David; Sloth, Martin Snoager; Vernizzi, Filippo

    2009-01-01

    We compute the connected four-point correlation function of the primordial curvature perturbation generated during inflation with standard kinetic terms, where the correlation is established via exchange of a graviton between two pairs of scalar fluctuations. Any such correlation yields a contrib......We compute the connected four-point correlation function of the primordial curvature perturbation generated during inflation with standard kinetic terms, where the correlation is established via exchange of a graviton between two pairs of scalar fluctuations. Any such correlation yields...

  16. Proton exchange membrane fuel cells

    CERN Document Server

    Qi, Zhigang

    2013-01-01

    Preface Proton Exchange Membrane Fuel CellsFuel CellsTypes of Fuel CellsAdvantages of Fuel CellsProton Exchange Membrane Fuel CellsMembraneCatalystCatalyst LayerGas Diffusion MediumMicroporous LayerMembrane Electrode AssemblyPlateSingle CellStackSystemCell Voltage Monitoring Module (CVM)Fuel Supply Module (FSM)Air Supply Module (ASM)Exhaust Management Module (EMM)Heat Management Module (HMM)Water Management Module (WMM)Internal Power Supply Module (IPM)Power Conditioning Module (PCM)Communications Module (COM)Controls Module (CM)SummaryThermodynamics and KineticsTheoretical EfficiencyVoltagePo

  17. Common Knowledge in Email Exchanges

    CERN Document Server

    Sietsma, Floor

    2011-01-01

    We consider a framework in which a group of agents communicates by means of emails, with the possibility of replies, forwards and blind carbon copies (BCC). We study the epistemic consequences of such email exchanges by introducing an appropriate epistemic language and semantics. This allows us to determine when a group of agents acquires common knowledge of the formula expressing that an email was sent. We also show that in our framework from the epistemic point of view the BCC feature of emails cannot be simulated using messages without BCC recipients. Finally, we clarify the notion of a causal relationship between emails using the concept of properly terminating email exchanges.

  18. The Commodity and its Exchange

    DEFF Research Database (Denmark)

    Høst, Jeppe Engset

    2015-01-01

    This chapter examines fishing quota as a commodity in both a conceptual perspective and through ethnographic examples. Inspired by Marx’s ideas of the commodity, use-value, exchange-value, and ground rent, the chapter combines a theoretical approach with ethnographic material. The different aspects...... and the value of the quota are examined through the concrete exchange of fishing rights, and it is explained why quota trade can give rise to speculation and monopolies. In the final part of the chapter, it is argued that the value of transferable fishing quotas rely on a social relation between owners...

  19. Evaluating China's Exchange Rate Regime

    Institute of Scientific and Technical Information of China (English)

    Charlie Xiao Feng

    2008-01-01

    @@ In 1994 China established a de facto currency peg.1 The dollar-RMB exchange rate was fixed at 8.28.The People's Bank of China(PBC) allowed the rate a narrow band of around .01 to .02 percent in which it could shift daily.The exchange rate program did not become newsworthy until U.S.Treasury Secretary John Snow's visit in 2003.In fact as a study by Frankel and Wei (2007)showed, the RMB's forward was actually selling at a discount against the dollar prior to Secretary Snow's visit to China and his subsequent report, signaling that investors were anticipating RMB depreciation.

  20. CHANGES IN EXCHANGE RATE REGIMES

    Directory of Open Access Journals (Sweden)

    Carmen SANDU (TODERASCU

    2014-06-01

    Full Text Available The experience of recentyears showsthat it hasa fundamentalroleformation mechanismof the exchange rateinmacroeconomic stabilization. Global economiccrises, oil shockshave shownthe difficultyoffloatingsustainabilitybyparticipants in the system. EuropeanMonetary System, focused onconcertedfloatingcurrenciestoECU, was formedunder the conditionsin which somecountries have adoptedregional monetaryarrangements(EU countries, with suchbasescurrencyregimeshybridthat combinesspecific mechanismsto those offixedratefree floating. This paperaims to demonstratethe important role thatithasthe choice ofexchange rateregimeas abasic elementin thefoundationofmacroeconomic stabilizationinstruments. Consideredan expression of thestateof the domestic economyandinternationalcompetitiveness, the exchange rate is determined bya complex set ofexternal factorsorinternalstabilityisa prerequisite forthe crisis.

  1. Improvement of polyploidy induction in Eriocheir sinensis

    Institute of Scientific and Technical Information of China (English)

    CUI Zhaoxia; XIANG Jianhai; ZHOU Linghua; CAI Naner; SONG Linsheng

    2004-01-01

    An incubating temperature of 15 ℃ is used to induce triploidy in Eriocheir sinensis through inhibition of the release of polar body Ⅱ, and that of 18 ℃ to induce tetraploidy through inhibition of the first cleavage. Flow cytometry is used to identify the ploidy in different developmental stages. For induction of triploidy in fertilized eggs in vitro, the highest induction rate observed in blastula by cytochalasin B, 6-DMAP and KC1 is 49.1%, 51.7% and 77.5%,respectively. In the KCl treatment of pregnant crabs with the fertilized eggs, the highest triploid induction rate observed in the zoea is 85.3%. For induction of tetraploidy, the highest induction rate observed in the blastula by cytochaslasin B, 6-DMAP and KCl is 50.3%, 54.9% and 79.8% respectively. In the KC1 treatment of pregnant crabs with the fertilized eggs, the highest induction rate in zoea is 27.3%. Through this study such difficulty as in vitro culture is overcome. Triploid zoea Eriocheir sinensis has been developed for the first time. The induction rate of tetraploid zoea has also been greatly improved.

  2. Two frameworks for integrating knowledge in induction

    Science.gov (United States)

    Rosenbloom, Paul S.; Hirsh, Haym; Cohen, William W.; Smith, Benjamin D.

    1994-01-01

    The use of knowledge in inductive learning is critical for improving the quality of the concept definitions generated, reducing the number of examples required in order to learn effective concept definitions, and reducing the computation needed to find good concept definitions. Relevant knowledge may come in many forms (such as examples, descriptions, advice, and constraints) and from many sources (such as books, teachers, databases, and scientific instruments). How to extract the relevant knowledge from this plethora of possibilities, and then to integrate it together so as to appropriately affect the induction process is perhaps the key issue at this point in inductive learning. Here the focus is on the integration part of this problem; that is, how induction algorithms can, and do, utilize a range of extracted knowledge. Preliminary work on a transformational framework for defining knowledge-intensive inductive algorithms out of relatively knowledge-free algorithms is described, as is a more tentative problems-space framework that attempts to cover all induction algorithms within a single general approach. These frameworks help to organize what is known about current knowledge-intensive induction algorithms, and to point towards new algorithms.

  3. Instabilities in inductive discharges in reactive gases

    Science.gov (United States)

    Chabert, Pascal

    2002-10-01

    High-density inductively coupled plasmas (ICP) are routinely used for etching in the microelectronics industry. Since there is a substantial voltage across the non-resonant inductive coil, a fraction of the discharge power is deposited capacitively. The real inductive discharge can therefore exist in two different modes: the capacitive mode (E mode), for low power, and the inductive mode (H mode), for high power. As the power is increased, transitions from capacitive to inductive modes (E-H transitions) are observed. Tuszewski (Journal of Applied Physics, 1996) found that when operating with reactive gases containing negative ions the transition can be unstable, and a wide range of powers exist where the discharge oscillates between higher and lower electron density states. Later, Lieberman and co-workers (Lieberman et al., Applied Physics Letters 1999, and Chabert et al. Plasma Sources Sci. and Technol. 2001) proposed a model of this instability, based on particle and energy balance, showing the crucial role of negative ions in the instability process. This paper will present recent experimental and theoretical work in this area. Oscillations in the unsaturated radical (CF and CF2 in a CF4 inductive discharge) concentrations were measured during the instability by time-resolved laser induced fluorescence, showing that neutral species dynamics can be significant. On the theoretical side, conditions for the stability of inductive discharges with electronegative gases were derived from the model.

  4. Induction and repair of DNA damage measured by the comet assay in human T lymphocytes separated by immunomagnetic cell sorting.

    Science.gov (United States)

    Bausinger, Julia; Speit, Günter

    2014-11-01

    The comet assay is widely used in human biomonitoring to measure DNA damage in whole blood or isolated peripheral blood mononuclear cells (PBMC) as a marker of exposure to genotoxic agents. Cytogenetic assays with phytohemagglutinin (PHA)-stimulated cultured T lymphocytes are also frequently performed in human biomonitoring. Cytogenetic effects (micronuclei, chromosome aberrations, sister chromatid exchanges) may be induced in vivo but also occur ex vivo during the cultivation of lymphocytes as a consequence of DNA damage present in lymphocytes at the time of sampling. To better understand whether DNA damage measured by the comet assay in PBMC is representative for DNA damage in T cells, we comparatively investigated DNA damage and its repair in PBMC and T cells obtained by immunomagnetic cell sorting. PBMC cultures and T cell cultures were exposed to mutagens with different modes of genotoxic action and DNA damage was measured by the comet assay after the end of a 2h exposure and after 18h post-incubation. The mutagens tested were methyl methanesulfonate (MMS), (±)-anti-B[a]P-7,8-dihydrodiol-9,10-epoxide (BPDE), 4-nitroquinoline-1-oxide (4NQO), styrene oxide and potassium bromate. MMS and potassium bromate were also tested by the modified comet assay with formamido pyrimidine glycosylase (FPG) protein. The results indicate that the mutagens tested induce DNA damage in PBMC and T cells in the same range of concentrations and removal of induced DNA lesions occurs to a comparable extent. Based on these results, we conclude that the comet assay with PBMC is suited to predict DNA damage and its removal in T cells.

  5. Chromatid Painting for Chromosomal Inversion Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose the continued development of a novel approach to the detection of chromosomal inversions. Transmissible chromosome aberrations (translocations and...

  6. Chromatid Painting for Chromosomal Inversion Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a novel approach to the detection of chromosomal inversions. Transmissible chromosome aberrations (translocations and inversions) have profound genetic...

  7. Calculation of Leakage Inductance for High Frequency Transformers

    DEFF Research Database (Denmark)

    Ouyang, Ziwei; Jun, Zhang; Hurley, William Gerard

    2015-01-01

    Frequency dependent leakage inductance is often observed. High frequency eddy current effects cause a reduction in leakage inductance. The proximity effect between adjacent layers is responsible for the reduction of leakage inductance. This paper gives a detailed analysis of high frequency leakage...... inductance and proposes an accurate prediction methodology. High frequency leakage inductances in several interleaved winding configurations are also discussed. Interleaved winding configurations actually give a smaller degree of reduction of leakage induction at high frequency. Finite Element Analysis (FEA...

  8. Applied intelligent control of induction motor drives

    CERN Document Server

    Chan, Tze Fun

    2011-01-01

    Induction motors are the most important workhorses in industry. They are mostly used as constant-speed drives when fed from a voltage source of fixed frequency. Advent of advanced power electronic converters and powerful digital signal processors, however, has made possible the development of high performance, adjustable speed AC motor drives.This book aims to explore new areas of induction motor control based on artificial intelligence (AI) techniques in order to make the controller less sensitive to parameter changes. Selected AI techniques are applied for different induction motor control s.

  9. Generalized Rule Induction Based on Immune Algorithm

    Institute of Scientific and Technical Information of China (English)

    郑建国; 刘芳; 焦李成

    2002-01-01

    A generalized rule induction mechanism, immune algorithm, for knowledge bases is building an inheritance hierarchy of classes based on the content of their knowledge objects. This hierarchy facilitates group-related processing tasks such as answering set queries, discriminating between objects, finding similarities among objects, etc. Building this hierarchy is a difficult task for knowledge engineers. Conceptual induction may be used to automate or assist engineers in the creation of such a classification structure. This paper introduces a new conceptual rule induction method, which addresses the problem of clustering large amounts of structured objects. The conditions under which the method is applicable are discussed.

  10. Ion plating with an induction heating source

    Science.gov (United States)

    Spalvins, T.; Brainard, W. A.

    1976-01-01

    Induction heating is introduced as an evaporation heat source in ion plating. A bare induction coil without shielding can be directly used in the glow discharge region with no arcing. The only requirement is to utilize an rf inductive generator with low operating frequency of 75 kHz. Mechanical simplicity of the ion plating apparatus and ease of operation is a great asset for industrial applications; practically any metal such as nickel, iron, and the high temperature refractories can be evaporated and ion plated.

  11. Scalable conditional induction variables (CIV) analysis

    DEFF Research Database (Denmark)

    Oancea, Cosmin Eugen; Rauchwerger, Lawrence

    2015-01-01

    Subscripts using induction variables that cannot be expressed as a formula in terms of the enclosing-loop indices appear in the low-level implementation of common programming abstractions such as filter, or stack operations and pose significant challenges to automatic parallelization. Because...... the complexity of such induction variables is often due to their conditional evaluation across the iteration space of loops we name them Conditional Induction Variables (CIV). This paper presents a flow-sensitive technique that summarizes both such CIV-based and affine subscripts to program level, using the same...

  12. Nonadiabatic exchange dynamics during adiabatic frequency sweeps.

    Science.gov (United States)

    Barbara, Thomas M

    2016-04-01

    A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging.

  13. Lipase Induction in Mucor hiemalis.

    Science.gov (United States)

    Akhtar, M W; Mirza, A Q; Chughtai, M I

    1980-08-01

    The influence on lipase induction in Mucor hiemalis of different types of triglycerides containing mainly oleic acid (olive oil), erucic acid (mustard oil), or saturated fatty acids of 8 to 16 carbons (coconut oil) was studied. The fungus was grown in shake flasks in a fermentation medium containing peptone, minerals, and glucose or one of the oils as the carbon source. Maximum lipase was produced when the initial pH of the fermentation medium was kept at 4.0. Addition of Ca to the medium did not increase lipase production. The optimum pH for activity of both the mycelial and extracellular lipases was found to be 7.0. The fungus produced a significant amount of lipase in the presence of glucose, but the lipase activity increased markedly when olive oil was added to the medium at the beginning of the fermentation. Addition of olive oil at a later stage did not induce as much enzyme. Studies with washed mycelia showed that a greater amount of lipase was released when olive oil was present than when glucose was present. Among the various types of triglycerides used as the carbon source, olive oil was found to be most effective in inducing the lipase. Olive oil and mustard oil fatty acids inhibited the lipase more than those of coconut oil. The lipase induced by a particular type of triglyceride did not seem to be specific for the same triglyceride, nor was it inhibited specifically by it. Irrespective of the triglyceride used in the fermentation medium, the lipase produced was most active against coconut oil triglyceride, and this specificity, as shown by lipase activities in an n-heptane system, was not found to be due to a better emulsification of this oil. The lipase of M. hiemalis can be considered to be both constitutive and inducible.

  14. Energy Exchange NASA Opening Plenary

    Science.gov (United States)

    Marrs, Rick

    2017-01-01

    Rick Marrs, Deputy Assistant Administrator Office of Strategic Infrastructure NASA Headquarters will be speaking during the 2017 Energy Exchange opening plenary. His presentation showcases the NASA mission, sustainability at NASA, NASA's strategic Sustainability Performance Plan, Existing PV Partnerships, and NASA funded Solar Initiatives at KSC.

  15. Knowledge Exchange with Sistema Scotland

    Science.gov (United States)

    Allan, Julie; Moran, Nikki; Duffy, Celia; Loening, Gica

    2010-01-01

    This paper reports on a knowledge exchange project, funded by the Scottish Funding Council and undertaken by a group of researchers from three higher education institutions in Scotland and the project partner, Sistema Scotland. This newly established charity is attempting to implement a major programme of social change, developed in Venezuela,…

  16. The Commodity and its Exchange

    DEFF Research Database (Denmark)

    Høst, Jeppe Engset

    2015-01-01

    and the value of the quota are examined through the concrete exchange of fishing rights, and it is explained why quota trade can give rise to speculation and monopolies. In the final part of the chapter, it is argued that the value of transferable fishing quotas rely on a social relation between owners...... and nonowners of quota, as a form of monopoly rent....

  17. Fragmentary model of exchange interactions

    CERN Document Server

    Kotov, V M

    2000-01-01

    This article makes attempt to refusal from using neutrino for explanation continuous distribution of beta particle energy by conversion to characteristic exchange interaction particles in nucleolus. It is taking formulation for nuclear position with many different fragments. It is computing half-value period of spontaneous fission of heavy nucleolus. (author)

  18. "Bottle-Brush" Heat Exchanger

    Science.gov (United States)

    Tward, E.; Gatewood, J. R.

    1982-01-01

    Heat exchanger consists of a metal tube with wires extending inward from wall. Conduction of heat along wires improves heat transfer to gas or other filling. Fluid is heated throughout the cross section of tube. Suggested applications are refrigerators, heat engines, thermal instrumentation, and heat switches.

  19. Milk fouling in heat exchangers.

    NARCIS (Netherlands)

    Jeurnink, Th.J.M.

    1996-01-01

    The mechanisms of fouling of heat exchangers by milk were studied. Two major fouling mechanisms were indentified during the heat treatment of milk: (i) the formation and the subsequent deposition of activated serum protein molecules as a result of the heat denaturation; (ii) the precipitation of cal

  20. Baltic Exchange teper v Tallinne

    Index Scriptorium Estoniae

    2007-01-01

    Viimane osa merekonteineritesse kokkupakitud Londoni laevandus- ja merebörsi Baltic Exchange'i endise peakorteri detailidest jõudis 2007. a. juunis Tallinna. Hoone detailid ostnud ärimehed Heiti Hääl ja Eerik-Niiles Kross plaanivad leida hoonele koha Tallinna kesklinnas. E.-N. Krossi kommentaar