WorldWideScience

Sample records for chromatid exchanges sce

  1. Evaluation of the persistence in the induction of Sister Chromatid Exchanges (SCE) by alkylating agents

    International Nuclear Information System (INIS)

    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)

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

    Directory of Open Access Journals (Sweden)

    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.

  3. Relationship of the demethylation of the DNA with the induction of the sister chromatid exchanges (SCE) In vivo

    International Nuclear Information System (INIS)

    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)

  4. Effects of hyperthermia and x irradiation on sister chromatid exchange (SCE) frequency in Chinese hamster ovary (CHO) cells

    International Nuclear Information System (INIS)

    The BrdUrd labeling method was used to evaluate the effects of hyperthermia, x irradiation, and the combined treatment on the incidence of sister chromatid exchange (SCE) in Chinese hamster ovary (CHO) cells. Cells cultured in McCoy's 5A media containing 10 μM 5-bromodeoxyuridine were synchronized after one cell cycle by mitotic shake-off. Early-G1 cells were heated by submerging culture flasks in a 44 +- 0.050C water bath for periods of 20, 40, and 60 min. By the same method, other cultures were x irradiated at doses of 100, 200, 400, and 600 rad. A third protocol involved combined treatment of 20 min at 440C followed immediately by one of the above radiation doses. A fourth protocol reversed the sequence of the combined treatment applying x irradiation (200 or 400 rad) followed immediately by hyperthermia. The data showed that hyperthermia and x irradiation both elevated the frequency of SCEs significantly whether applied separately or together. The combined treatment (heat: 20 min at 440C plus varying x-radiation doses) produced results suggestive of a synergistic interaction. The sequence of the heat and x irradiation did not appear to have a significant effect on the production of SCE

  5. Effect of tritiated compounds on sister-chromatid exchanges (SCE) in human lymphocytes in vitro

    International Nuclear Information System (INIS)

    Human lymphocytes treated in vitro with various activities of 3H-TdR and 3H-UdR were cultured to understand the effects of tritium on the cell cycle and the frequency of SCE. The results of these experiments indicated that both tritiated compounds make the frequency of SCE increase and the cell cycle delay. The frequency of SCE increased markedly with activity of 3H. With respect to delaying cell cycle, 3H-UdR was more effective than 3H-TdR. The average frequencies of SCE for 3H-UdR were higher than those for 3H-TdR. With the exception of 3.7 x 103 Bq/mL group and differences between other 3H-UdR groups and corresponding 3H-TdR group were significant (t test, p < 0.01). These results suggest that tritiated compounds may have the effect on the cell proliferating rate. The cell proliferating rate index (PRI) seems to be related with the frequency of SCE: the higher the frequency of SCE, the lower the PRI is

  6. Effect of cysteamine on sister chromatid exchange (SCE) induction by gamma rays

    International Nuclear Information System (INIS)

    The effect of different doses of cysteamine (3, 15 and 150 μg/g bw) on gamma ray-induced SCE was evaluated and compared with the responses obtained with regard to frequency of chromosomal aberrations, frequency of proliferating cells and the rate of cellular proliferating kinetics in mouse bone marrow cells in vivo. Groups of mice were either irradiated, treated with cysteamine and irradiated, only treated with cysteamine or left without treatment for determination of these parameters. The intraperitoneal administration of cysteamine preceding 1 Gy of gamma ray exposure, produces a dose dependent radioprotection on SCE-induction obtaining the greatest effect with 150 μg/g bw. However, this effect was not observed in the mitotic index nor in the average generation time. Chromosomic aberrations in animals irradiated after treatment with cysteamine were also detected. It was not observed any citotoxic or genotoxic effect produced by cysteamine per se. The results suggest that, under the experimental conditions of this study, the SCE are caused by free radicals produced by gamma radiation; not so, the additional damage indexes measured. (author)

  7. Genotoxicity of the anticonvulsant drug phenytoin (PHT): a follow-up study of PHT-untreated epileptic patients. I. Sister chromatid exchange (SCE) analysis.

    Science.gov (United States)

    Kaul, A; Goyle, S

    1999-01-01

    Phenytoin (PHT) is a widely prescribed antiepileptic drug. Its potential to interact with genetic material was investigated in a set of 30 epileptic patients (age 10-30 years) prior to and following the administration of PHT over a period of 9 months (grouped in a multiple of 3 months) and 40 control subjects in relation to age, sex, duration of drug therapy, and plasma concentration of PHT, using the sister chromatid exchange (SCE) frequency assay. Plasma levels of the phenytoin were measured by biochemical assay in epileptic patients before and after the PHT therapy. The peripheral blood lymphocytes were cultured and harvested at 72 h. The frequency of SCE was significantly higher (P genotoxic effect as expressed by the induction of increased SCE rates in treated epileptics, while disease does not play any role in inducing genetic damage as shown by no difference in SCE frequencies between control subjects and PHT-untreated epileptic patients. PMID:10321411

  8. Effect of chlorophyllin on frequency radiation-induced of sister chromatid exchanges (SCE) and other cytogenetic events in mice bone marrow cells In Vivo

    International Nuclear Information System (INIS)

    The effect of chlorophyllin on gamma radiation induced Sister chromatid exchanges (SCE) and on the mitotic index (IM) and average generation time was determined. Groups of mice were treated in one of the following regimens: (1) untreated, (2) treated with chlorophyllin only, (3) irradiated and (4) treated with chlorophyllin and irradiated intraperitoneal administration of chlorophyllin preceding gamma radiation exposure protected again SCE induction and diminution of IM. However, radioprotection was not reflected in the average generation time for the chlorophyllin per se acceleration the average generation time. The results suggest that, under the experimental conditions of the study the SCE and IM are caused by free radicals produced by radiation and wat the action mechanics of chlorophyllin is scavenger free radicals. (Author)

  9. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  10. Sister chromatid exchanges

    International Nuclear Information System (INIS)

    Sister chromatid exchanges (SCEs) are cytological manifestations of DNA double-strand breakage and rejoining at homologous sites between the two chromatids of a chromosome. The occurrence of SCEs was deduced from the transformation of small ring chromosomes to large ring chromosomes following cell division. Using tritiated thymidine as marker and microautoradiography for detection, others demonstrated the occurrence of SCEs from the silver grain pattern on the sister chromatids. This method was eventually replaced by cytochemical methods. One showed that if cells were grown in medium containing 5-bromo-deoxyuridine (BrdUrd) for two cycles, the sister chromatids can be distinguished by the differential quenching of the fluorescence of the fluorochrome Hoechst 33258. Reduced staining with Giemsa stain of the BrdUrd-incorporated chromatids was also found to be useful in differentiating sister chromatids. The authors review in this chapter only those studies which have implications on the origin of SCEs

  11. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  12. INDUCTION, ACCUMULATION, AND PERSISTENCE OF SISTER CHROMATID EXCHANGES IN WOMEN WITH BREAST CANCER RECEIVING CYCLOPHOSPHAMIDE, ANDRIAMYCIN, AND 5-FLUOROACIL CHEMOTHERAPY

    Science.gov (United States)

    The induction, stimulation, and persistence of sister chromatid exchanges (SCE's) and high SCE frequency cells (HFC's) was measured in peripheral lymphocytes of women with breast cancer before chemotherapy and on multiple occasions during and after therapy. Chemotherapy consisted...

  13. SCE enigma

    International Nuclear Information System (INIS)

    Exchange of two homologous DNA helices between sister chromatids can be graphically visualized in metaphase chromosomes by differential staining of chromatids. This ubiquitous phenomenon, SCE, represents an example of dynamic behavior of the genetic material. SCEs have given the great impact to those interested in not only the basic mechanism of DNA recombination but also environmental mutagenesis. This article overviews the accumulated experimental data on SCE formation, highlighting the methodology for SCE detection, induction of SCEs in vitro and in vivo, radiation-induced SCEs, the mechanistic aspects of SCE formation, SCE and DNA methylation, SCE and chromosomal aberration, and adaptive chromosomal DNA repair revealed by SCE studies. A biological role of SCE formation is considered to be the basic mechanism for generating genetic variation through gene magnification, rearrangement and amplification in the cells during the course of ontogenical and phylogenical differentiation. (author)

  14. Sister chromatid exchange analysis in lymphocytes of workers exposed to hexavalent chromium.

    OpenAIRE

    Nagaya, T.; Ishikawa, N.; Hata, H.

    1989-01-01

    To investigate the usefulness of sister chromatid exchange (SCE) analysis in lymphocytes as an indicator for mutagenic effects after in vivo exposure to hexavalent chromium (Cr), SCE frequency was analysed in lymphocytes of 44 Cr platers occupationally exposed to hexavalent Cr and 47 controls. Although urinary Cr analysis confirmed that the Cr platers were exposed to Cr, no effects of the exposure on SCE frequency were found. Smokers, both Cr platers and controls, had a significantly higher S...

  15. Chromosome aberrations and sister chromatid exchanges in Swedish paint industry workers

    Energy Technology Data Exchange (ETDEWEB)

    Haglund, U.; Lundberg, I.; Zech, L.

    1980-12-01

    Workers in the Swedish paint industry exposed to a mixture of organic solvents, mainly containing xylene or toluene, were investigated for genotoxic effects. No difference in the frequency of sister chromatid exchanges (SCE), 0.192 and 0.193 per chromosome, respectively, was noted in the peripheral lymphocytes of the exposed group of 17 workers and their matched reference group. No correlation was found between xylene or toluene exposure and SCE frequency nor between total solvent exposure and SCE frequency. The frequency of chromosome aberrations was also investigated for the five most exposed workers and their matched referents, and no difference was found. There was no correlation between SCE and chromosome breaks.

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

    Directory of Open Access Journals (Sweden)

    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.

  17. Influence of irradiation at different stages of mitotic cycle upon production of sister chromatid exchanges in cultured Chinese hamster cells

    International Nuclear Information System (INIS)

    Frequency of sister chromatid exchanges (SCE) and microexchanges in Chinese hamster cells has been studied by means of the method of differential staining of chromatids on irradiation at different stages of the mitotic cycle. It is shown that the irradiation enhances frequency of SCE and microexchanges if it is carried out before the end of DNA replication synthesis. Comparison of frequency depenedence of radiation-induced microexchanges and SCE at different stages of the mitotic cycle results in the conclusion that the microexchanges are none other than small SCE

  18. Influence of irradiation at different stages of mitotic cycle unon production of sister chromatid exchanges in cultured chinese hamster cells

    International Nuclear Information System (INIS)

    Frequency of.sister chromatid exchanges (SCE) and microexchanges in the chinese hamster cells was investigated by means of the method of differential colouring of chromatids on irradiation at different stages of the mitotic cycle. It is shown that the irradiation increases frequency of SCE and microexchanges if it is performed before the end of the replicative DNA synthesis. Comparison of frequency dependence of radiation-induced microexchanges and SCE at different stages of the mitotic cycle permits to conclude that the microexchanges are small SCE

  19. Sister Chromatid Exchange Frequency in Lymphocytes Cultured from Cotton Gin Workers

    OpenAIRE

    ATMACA, Münevver; BAĞCI, Hüseyin; AÇIKBAŞ, İbrahim; GÜMÜŞ, Dilihan; DÜZCAN, Füsun

    2004-01-01

    Genetic biomonitoring of human populations exposed to potential mutagens/carcinogens can be performed using different genetic markers. Sister chromatid exchange (SCE) is one of the most extensively used markers of the early biological effects of DNA damaging agents. In order to assess the genotoxicity associated with exposure to cotton dust, we determined SCE frequency in peripheral blood lymphocytes cultured from 20 cotton gin workers and 20 controls. Student’s-t test indicated an ...

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

    OpenAIRE

    Treetip Ratanavalachai; Sumon Thitiorul; Pranee Nandhasri

    2008-01-01

    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

  1. "Sister Chromatid Exchanges and Micronuclei in Lymphocyte of Nurses Handling Antineoplastic Drugs"

    Directory of Open Access Journals (Sweden)

    M Ansari-Lari

    2001-07-01

    Full Text Available Individuals handling antineoplastic drugs or their wastes may absorb these potent genotoxic agents. The effects of handling antineoplastic drugs were examined in a group of 24 nurses working in the hematology and oncology departments of two different university hospitals in Shiraz (Iran and in a group of 18 unexposed nurses as control group. The cytogenetic repercussions of exposure were assessed by examining sister chromatid exchanges (SCEs and micronuclei (Mn in circulating lymphocytes. A significant increased frequencies of SCE and Mn is observed in circulating lymphocytes. A significant increased frequencies of SCE and Mn is observed in nurses in daily contact with antineoplastic drugs as compared to control group.

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

    OpenAIRE

    Wang, Yisong; Erdmann, Natalie; Giannone, Richard J.; Wu, Jun; Gomez, Marla; Liu, Yie

    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...

  3. A study of sister chromatid exchange in patients with dental amalgam restorations

    OpenAIRE

    E Lakshmi Priya; K Ranganathan; Uma Devi K Rao; Elizabeth Joshua; Deepu George Mathew; Kavitha Wilson

    2014-01-01

    Study Background: Dental amalgam is still widely used as a restorative material in developing countries due to its low cost and ease of manipulation. The health risks associated with the components of this restorative material has always been a matter of concern. Our study was designed to address this question regarding dental amalgam. Objective: To study sister chromatid exchange (SCE) as an indicator of systemic genotoxicity, due to the exposure from the components of amalgam restoratio...

  4. Radiation-induced chromosome aberrations and sister chromatid exchanges in lymphocytes from patients with tuberous sclerosis

    International Nuclear Information System (INIS)

    Lymphocytes from four patients with tuberous sclerosis (TS) and four normal controls were studied for sister chromatid exchanges (SCEs) and chromosome aberrations in gamma-ray irradiated cultures. There was no significant difference between SCE frequencies of TS lymphocytes and those of control lymphocytes at all doses examined (1, 2, and 4 Gy). However, chromosome aberrations in TS lymphocytes were significantly higher than those in the normal controls at the highest dose (4 Gy) (p < 0.05). (author)

  5. KINETICS OF IN VIVO SISTER CHROMATID EXCHANGE INDUCTION IN MOUSE BONE MARROW CELLS BY ALKYLATING AGENTS: CYCLOPHOSPHAMIDE

    Science.gov (United States)

    Administration of cyclophosphamide (5, 10, 20 and 25 mg/kg body weight) to male CD-1 mice 2 hours after subcutaneous implantation of a 5-bromo-2'-deoxyuridine (BrdU) pellet (55 mg) resulted in a dose-dependent increase in sister chromatid exchanges (SCE) in bone marrow cells. Tre...

  6. Sister chromatid exchanges in X-ray irradiated blood lymphocytes from patients with hereditary diseases with radioresistant DNA synthesis

    International Nuclear Information System (INIS)

    X-ray irradiation induced sister chromatid exchanges (SCE) in blood lymphocytes from patient with Down's syndrome and adult progeria (in both the cases radioresistant DNA synthesis takes place). In normal lymphocytes (in which ionizing radiation inhibits the replicative synthesis of DNA) the rate of SCE rises with the rise of radiation dose. Thus, the rate of SCE in X-ray irradiated lymphocytes is in reverse dependence with radioresistance of replicative synthesis of DNA. The data obtained are explained in accordance with the replicative hypothesis of the SCE nature (Painter, 1980a): in cells of patients with Down's syndrome, xeroderma pigmentosum from 2 and progeria of adults the time of existence of partly replicated clusters of replicons is decreased due to radioresistant replicative synthesis of DNA, but the presence of partly replicated clusters of replicons in necessary for SCE formation. Therefore the rate of SCF in X-irradiated cells of these patients decreases

  7. Induction of sister chromatid exchanges in xeroderma pigmentosum cells after exposure to ultraviolet light

    International Nuclear Information System (INIS)

    The role of DNA repair mechanisms in the induction of sister chromatid exchanges (SCE) after exposure to ultraviolet radiation was investigated in xeroderma pigmentosum cells. Cells from different excision-deficient XP strains, representing the 5 complementation groups in XP, A, B, C, D and E, and from excision-proficient XP variant strains were irradiated with low doses of UVR (0-3.5 J/m2). The number of SCE was counted after two cycles in the presence of BUdR. In cells of the complementation groups A, B, C and D the number of SCE was significantly higher than in UV-exposed control cells. The frequencies of SCE in group E cells and in XP variant cells were not different from those in control cells. Treatment with caffeine (0-200 μg/ml) did not result in a different response of variant cells compared with normal cells. A simple correlation between SCE frequency and residual excision-repair activity was not observed. The response of the excision-repair deficient cells suggests that unrepaired damage, produced by UVR is involved in the production of SCE

  8. 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. PMID:24852491

  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. Sister chromatid exchanges induced by two radiosensitizing platinum compounds (cis-dichloro-bis isopropylamine trans dihydroxy platinum IV (CHIP) and cis platinum metronidazole2Cl2(FLAP] in CHO cells in vitro.

    OpenAIRE

    Bocian, E; Laverick, M.; Nias, A H

    1983-01-01

    Sister chromatid exchange (SCE) induction by two radiosensitizing platinum compounds (cis-dichloro-bis isopropylamine trans dihydroxy platinum IV (CHIP) and cis-platinum metronidazole2 Cl2 (FLAP] was studied in CHO cells in vitro. Both drugs induced SCE in a dose dependent manner. CHIP was a much more potent inducer of SCE than FLAP and produced almost 4 times as many SCE as FLAP at equimolar concentrations and twice as many at equitoxic dosage. Induction of SCE by a component of the FLAP mol...

  11. In vivo study on the replicative model validity of sister chromatid exchanges production

    International Nuclear Information System (INIS)

    The sister chromatid exchanges (SCE) frequency determination has been used as index of damage to DNA, however the biological meaning of this event is still ignored. Different models in order to explain the mechanism of their formation have been proposed and they could be contained in two categories: a) those that consider that the SCE is produced by means of discreet lesions to the DNA and that they occur in the place of the lesion, and b) those that propose that the SCE is caused by a group of lesions and that therefore the place in which they occur could not be associated with a lesion in particular. The model of Painter (1980) belongs to this last group. It suggests that the region of the DNA where the clusters are united, is the only place in which the exchange of double chain could happen during the synthesis of the DNA and makes the prediction that since the x rays retard the beginning of the duplication, the pretreatment with ionizing radiation would reduce the frequency of SCE induced by agents capable to block the lengthening of the chain of DNA, that are the most efficient SCE inducers. The objective of the present work was to establish the validity of this replicative model for the SCE formation, based in its prediction. The effect of the unilateral preexposition of mouse to gamma radiation was determined on the SCE induction by Mitomycin C (MMC), in cells of the femoral bone marrow In vivo. This strategy allows to determine the effect of the pretreatment in the same organism, minimizing the variability of the response between individuals. There was not a significant variability between the frequencies of SCE, basal and induced by gamma radiation or MMC in the same organism. The animals that received the gamma radiation pretreatment, showed a reduction of approximately the 30 % in the frequency of SCE, assuming an additive effect of the radiation with the MMC. These results coincide with the prediction of the model of Painter, however it is not

  12. Sister chromatid exchanges in the bone marrow cells of in vivo rats induced by gamma radiation and chemical mutagens

    International Nuclear Information System (INIS)

    Sister chromatid exchanges (SCE) in the bone marrow of in vivo rats induced by gamma radiation doses and by the chemical mutagens, mitomycin C (MMC), cyclophosphamide (CP), and sulphonate-methylmethane (SMM), were studied. The purpose was to evaluate the sensitivity and reproducibility of a simplified SCE in vivo detecting system developed in our laboratory and to compare the results obtained with those reported elsewhere. Simplification consisted in administering the amounts of 5-bromo-2'-deoxyuridine (BrdU) necessary to observe the SCE, after first adsorbing the BrdU in activated carbon and then injecting it interperitoneally, into the rats. The results were a longer time in vivo ADN incorporation without convulsions in the rats, and a reduction in the time course as compared to other methods. We observed a basal rate of 3.6+-0.37 SCE/cell and that: 0.44 Gy of gamma radiation induced 7.7+-0.73 SCE/cell; 1.6 μg/g of MMC induced 8.1+-1.20 SCE/cell; 5 μg/g of CP induced 8.25+-1.5 SCE/cell, 40 μg/g of SMM induced 22.0+-5 SCE/cell and 380 μg/g of sulphonate-ethylmethane induced 8.6+-1.2 SCE/cell. This showed that all the agents were capable of inducing SCE in the bone marrow cells of rats in vivo under our conditions. We noted a greater induced efficiency for gamma radiation than the obtained by other investigators and a relatively similar efficiency in the case of chemical mutagens as reported in other studies. (author)

  13. Effect of chlorophyllin on induction of exchanges in sister chromatids by gamma irradiation in mice spermatogonia in vivo

    International Nuclear Information System (INIS)

    Mouse were exposed to different doses of gamma radiation and the effect on Sister Chromatid Exchange (SCE) frequency in spermatogonias was evaluated. The effect was analyzed before and after Bromodeoxyuridine (BrdU) incorporation to determine the interference of such agent with the cellular response induced by radiation. The capacity of chlorophyllin (sodium and Copper salt derivative from chlorophyll) to reduce SCE induction by radiation in normal and BrdU radio sensitized spermatogonia was also determined. The results indicate that there was a significant increase in SCE frequency by gamma radiation exposure in these cells, such effect was higher irradiating after BrdU incorporation than before. This fact confirms previous observations that BrdU sensitizes some cells to SCE induction. With regard to the chlorophyllin effect, it was determined that this salt acts as a radioprotector reducing gamma-rays induced SCE before or after BrdU incorporation Total protection was obtained with 200 μg of chlorophyllin per g of body weight in both protocols. Under the experimental conditions this study there was no evidence of genotoxicity induced by chlorophyllin itself. The results suggest that this agent may act as a radioprotector by scavenging free radicals produced by gamma-radiation which cause DNA lesions that are involved in SCE formation. (Author)

  14. 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.

  15. Further environmental factors causing variations of SCE frequencies

    International Nuclear Information System (INIS)

    The frequencies of spontaneously occurring sister chromatid exchanges (=SCE) were determined in control persons, persons exposed to very low doses of ionizing radiation and employees of a rubber factory. Besides smoking habits and the usage of oral contraceptives, background ultraviolet (=UV) radiation seems to exert the most pronounced effect on SCE levels in control persons. (Author)

  16. Variation in sister chromatid exchange frequencies between human and pig whole blood, plasma leukocyte, and mononuclear leukocyte cultures

    International Nuclear Information System (INIS)

    Sister chromatid exchange (SCE) induction by ultraviolet (UV) light was studied in both human and pig whole blood cultures (WBC) and plasma leukocyte cultures (PLC). No variation in SCE frequency was observed between pig WBC and PLC in control as well as in treated cells. Conversely, SCE frequencies of human PLC were consistently higher than those of WBC in control and UV-exposed cells. Thus, red blood cells (RBCs) do not influence the sensitivity of lymphocytes to UV LIGHT exposure, and there must be some different culture condition(s) in the inducation of SCEs between human WBC and PLC but not in swine lymphocyte cultures. Since the BrdUrd/lymphocyte ratio of WBC was halved in PLC, the effect of BrdUrd concentration in inducing the SCE baseline frequency of PLC may be ruled out. Neither the cell separation technique nor polymorphonuclear leukocytes had a significant role in the elevated SCE frequency of human PLC or MLC. Experiments where human RBCs were titrated into human PLC showed that the induction of an elevated SCE frequency of PLC was suppressed in a dose-dependent manner by the presence of RBCs in the culture medium. Since the incorporation of pig or human RBCs into human PLC as well as into MLC reduced the SCE frequency to that of WBC, a common component and/or function existing in these cells is suggested. Analysis of different RBC components showed that RBCs, specifically RBC ghosts, release a diffusible but not dialyzable corrective factor into culture medium that is able to reduce the SCE frequencies of PLC

  17. Erythrocytes modulate cell cycle progression but not the baseline frequency of sister chromatid exchanges in pig lymphocytes

    OpenAIRE

    Miguel A. Reigosa; Sonia Soloneski; Garcia, Carlos F.; Larramendy, Marcelo L.

    1997-01-01

    The effect of co-culturing varying concentrations of pig and human red blood cells (RBCs) on the baseline frequency of sister chromatid exchanges (SCEs) and cell-cycle progression in pig plasma (PLCs) and whole blood leukocyte cultures (WBCs) was studied. No variation in SCE frequency was observed between pig control WBC and PLC. Addition of pig and human RBCs to pig PLCs did not modify the baseline frequency of SCEs. On the other hand, cell proliferation was slower in PLCs than in WBCs. The ...

  18. Correlation of drug-induced sister chromatid exchanges in vitro with in vivo tumor response

    International Nuclear Information System (INIS)

    A spontaneous hepatocarcinoma (HCa) grown in C/sub 3/Hf/Kam mice was used to investigate the ability of the in vitro sister chromatid exchange (SCE) assay to predict in vivo tumor sensitivity to 3 chemotherapeutic agents: melphalan, cis-Platinum, and BCNU. For HCa cells grown in monolayer culture, melphalan was the most efficient at inducing SCEs, followed by cis-Platinum, with BCNU inducing the least. According to in vitro cell survival curves, HCa was most sensitive to melphalan, less sensitive to cis-Platinum, and essentially resistant to BCNU. The relative antineoplastic effects of melphalan, cis-Platinum, and BCNU in vivo were compared by the response of artificial and spontaneous pulmonary metastases and solid tumors to these agents. BCNU had no effect on the number of artificial metastases, while there was a dose-dependent decrease in the number of lung nodules in mice treated with melphalan or cis-Platinum, with melphalan being the more effective. Spontaneous pulmonary metastases generated from HCa leg tumors were reduced in those mice treated with melphalan, unaffected by cis-Platinum, and increased by BCNU. In HCa leg tumors (5 to 6 mm in diameter), melphalan induced the longest growth delay, with cis-Platinum inducing less, and BCNU the least. Thus, the relative effects produced by these 3 drugs in vivo were the same as predicted by SCE assay in vitro

  19. 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. PMID:26970083

  20. DNA crosslinking, sister-chromatid exchange and specific-locus mutations.

    Science.gov (United States)

    Carrano, A V; Thompson, L H; Stetka, D G; Minkler, J L; Mazrimas, J A; Fong, S

    1979-11-01

    Chinese hamster ovary cells were treated with the DNA-crosslinking chemicals, mitomycin C (MMC) and porfiromycin (POR), and their monofunctional derivative decarbamoyl mitomycin C (DCMMC). After exposure, the cells were studied for the induction of sister-chromatid exchanges (SCEs) and mutations at the hypoxanthine phosphoribosyltransferase and adenine phosphoribosyltransferase loci. The frequency of SCEs varied significantly in successive sampling intervals, requiring the weighting of each interval by the percentage of second-division mitosis in that interval to obtain the mean SCE frequency for each dose. All 3 compounds were potent inducers of SCEs but weakly mutagenic. All 3 chemicals by concentration were approximately equally effective in inducing SCEs or mutations. When the induced SCEs and mutations were compared at equal levels of survival, DCMMC was slightly more effective than MMC or POR in inducing SCEs and somewhat less mutagenic. These results indicate that the DNA interstrand crosslink is not the major lesion responsible for the induction of SCE or mutation by these compounds. PMID:522865

  1. DNA crosslinking, sister-chromatid exchange and specific-locus mutations

    Energy Technology Data Exchange (ETDEWEB)

    Carrano, A.V.; Thompson, L.H.; Stetka, D.G.; Minkler, J.L.; Mazrimas, J.A.; Fong, S.

    1979-01-01

    Chinese hamster ovary cells were treated with the DNA-crosslinking chemicals, mitomycin C (MMC) and porfiromycin (POR), and their monofunctional derivative decarbamoyl mitomycin C (DCMMC). After exposure, the cells were studied for the induction of sister-chromatid exchanges (SCEs) and mutations at the hypoxanthine phosphoribosyltransferase and adenine phosphoribosyltransferase loci. The frequency of SCEs varied significantly in successive sampling intervals, requiring the weighting of each interval by the percentage of second-division mitosis in that interval to obtain the mean SCE frequency for each dose. All 3 compounds were potent inducers of SCEs but weakly mutagenic. All 3 chemicals by concentration were approximately equally effective in inducing SCEs or mutations. When the induced SCEs and mutations were compared at equal levels of survival, DCMMC was slightly more effective than MMC or POR in inducing SCEs and somewhat less mutagenic. These results indicate that the DNA interstrand crosslink is not the major lesion responsible for the induction of SCE or mutation by these compounds.

  2. 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.

  3. 40 CFR 79.65 - In vivo sister chromatid exchange assay.

    Science.gov (United States)

    2010-07-01

    ... references should be consulted. (1) 40 CFR 798.5915, In vivo Sister Chromatid Exchange Assay. (2) Kato, H... 40 Protection of Environment 16 2010-07-01 2010-07-01 false In vivo sister chromatid exchange... PROGRAMS (CONTINUED) REGISTRATION OF FUELS AND FUEL ADDITIVES Testing Requirements for Registration §...

  4. 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.

  5. Sister chromatid exchanges and micronuclei in lymphocytes of operating room personnel occupationally exposed to enfluorane and nitrous oxide.

    Science.gov (United States)

    Pasquini, R; Scassellati-Sforzolini, G; Fatigoni, C; Marcarelli, M; Monarca, S; Donato, F; Cencetti, S; Cerami, F M

    2001-01-01

    The objective of this article is to assess whether occupational exposure to anesthetics increases genotoxic risk. We investigated two cytogenetic biomarkers, sister chromatid exchanges (SCE) and micronuclei (MN), in the peripheral blood lymphocytes of 46 anesthesiologists (24 men), working in operating rooms and mostly exposed to enfluorane and nitrous oxide, and 66 controls (35 men), not exposed to chemicals and living in the same area. Contrary to what was expected, a lower frequency of SCE was found in male anesthesiologists than in controls. Smoking status was found to be positively associated with SCE frequency in each group, while no relation to age was evident. On the contrary, MN frequency was significantly higher in female, but not male, anesthesiologists than in controls. Age and smoking status did not modify the association. No relationship between MN frequency and duration of employment was found in anesthesiologists. Smoking status and mean number of cigarettes smoked per day in smokers were not associated with MN frequency in either anesthesiologists or in controls. MN analysis seems to be a sensitive index of possible genotoxic effects of occupational exposure to anesthesiologists, and women appear to be more susceptible to these effects than men. PMID:11394710

  6. RecA stimulates sister chromatid exchange and the fidelity of double-strand break repair, but not gene targeting, in plants transformed by Agrobacterium

    OpenAIRE

    Reiss, Bernd; Schubert, Ingo; Köpchen, Kerstin; Wendeler, Edelgard; Schell, Jeff; Puchta, Holger

    2000-01-01

    Expression of the bacterial RecA protein in plants stimulates homologous recombination in tobacco. Here we show that RecA plays a direct role in DNA strand exchange in vivo. The number of sister chromatid exchanges (SCEs) was increased 2.4-fold over wild type in transgenic tobacco plants expressing a nuclear-targeted RecA (nt-RecA) protein and could not be increased further by DNA damage, which caused a doubling of the baseline SCE frequency in wild-type plants. Although gene targeting requir...

  7. Effect of landfill leachate on cell cycle, micronucleus, and sister chromatid exchange in Triticum aestivum

    Energy Technology Data Exchange (ETDEWEB)

    Li Guangke; Yun Yang; Li Hongyan [Center of Environment Science and Engineering, College of Environment and Resource, Shanxi University, Taiyuan, Shanxi 030006 (China); Sang Nan [Center of Environment Science and Engineering, College of Environment and Resource, Shanxi University, Taiyuan, Shanxi 030006 (China)], E-mail: sangnan_lgkcarl@yahoo.com.cn

    2008-06-30

    With increasing use of municipal solid waste landfills for waste disposal, the leachate generated has become a serious environmental concern. Therefore, it is important to set up simple and accurate methods for monitoring leachate toxicity. In the present study, the physiological and genetic toxicity of the leachate, generated from Xingou Municipal Landfill in China, were investigated with Triticum aestivum (wheat) bioassay. The results indicate that the lower leachate concentrations stimulated the germination, growth and cell division, and did not induce obvious increase in micronucleus (MN) frequency in root tips; while the higher concentrations inhibited the processes, and significantly augmented the MN frequency in a concentration- and time-dependent manner. In addition, pycnotic cells (PNC) and sister chromatid exchange (SCE) occurred in root tips at all leachate concentrations tested, and the frequencies had positive relation with the treatment concentration and time. The results imply that components of leachate from the landfill may be genotoxic in plant cells, and exposure to leachate in the aquatic environment may pose a potential genotoxic risk to organisms. The results also suggest that the wheat bioassay is efficient, simple and reproducible in monitoring genotoxicity of the leachate.

  8. Effect of landfill leachate on cell cycle, micronucleus, and sister chromatid exchange in Triticum aestivum

    International Nuclear Information System (INIS)

    With increasing use of municipal solid waste landfills for waste disposal, the leachate generated has become a serious environmental concern. Therefore, it is important to set up simple and accurate methods for monitoring leachate toxicity. In the present study, the physiological and genetic toxicity of the leachate, generated from Xingou Municipal Landfill in China, were investigated with Triticum aestivum (wheat) bioassay. The results indicate that the lower leachate concentrations stimulated the germination, growth and cell division, and did not induce obvious increase in micronucleus (MN) frequency in root tips; while the higher concentrations inhibited the processes, and significantly augmented the MN frequency in a concentration- and time-dependent manner. In addition, pycnotic cells (PNC) and sister chromatid exchange (SCE) occurred in root tips at all leachate concentrations tested, and the frequencies had positive relation with the treatment concentration and time. The results imply that components of leachate from the landfill may be genotoxic in plant cells, and exposure to leachate in the aquatic environment may pose a potential genotoxic risk to organisms. The results also suggest that the wheat bioassay is efficient, simple and reproducible in monitoring genotoxicity of the leachate

  9. DNA-mediated transfer of a human DNA repair gene that controls sister chromatid exchange.

    OpenAIRE

    Thompson, L H; Brookman, K W; Minkler, J L; Fuscoe, J C; Henning, K A; Carrano, A V

    1985-01-01

    The Chinese hamster cell line mutant EM9, which has a reduced ability to repair DNA strand breaks, is noted for its highly elevated frequency of sister chromatid exchange, a property shared with cells from individuals with Bloom's syndrome. The defect in EM9 cells was corrected by fusion hybridization with normal human fibroblasts and by transfection with DNA from hybrid cells. The transformants showed normalization of sister chromatid exchange frequency but incomplete correction of the repai...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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 60Co gamma rays at a low dose rate of from 4.8 x 10-5 to 1.2 x 10-1 Gy (0.0048 to 12 rad)/h for 24 h. After irradiation, the larvae were exposed to 3 x 10-5M bromodeoxyuridine (BrdUrd) for 28 h (x-ray-irradiated larvae) or for 54 h (60Co-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 60Co 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

  12. Elastatinal and leupeptin: effects on u.v.-induced mutation and sister-chromatid exchanges in Chinese hamster cells

    International Nuclear Information System (INIS)

    Microbial protease inhibitors elastatinal and leupeptin were tested for cytotoxicity and for effects on spontaneous and u.v.-induced 6-thioguanine-resistant (6TGr) mutation and sister-chromatid exchange (SCE) in V79 Chinese hamster cells. Continuous treatment with elastatinal exhibited marked cytotoxicity, while leupeptin was almost non-cytotoxic. Elastatinal rapidly induced cytotoxic effects as a function of its concentration and time of exposure. Near maximum cytotoxicity was reached after exposure of 6-8 h and this was partially abolished by the presence of 2.5 micrograms cycloheximide per ml. Concentrations of either protease inhibitor which gave 60-80% survival had no appreciable effects on u.v. survival and frequencies of spontaneous and u.v.-induced 6TGr mutation and SCE. However, reconstruction experiments revealed that pretreatments of 6TGr and 6TGs (wild-type) cells with these inhibitors for 6 days tended to block metabolic co-operation in their co-cultures. Thus, elastatinal and leupeptin are neither clastogenic mutagenic by themselves, and do not alter mutation fixation and expression

  13. Sister chromatid exchange assay as a predictor of tumor chemoresponse.

    Science.gov (United States)

    Mourelatos, D

    2016-06-01

    Sister Chromatid Exchanges (SCEs) are known to enhance as a consequence of exposure to various mutagenic agents and appear to indicate DNA damaging effects and/or subsequent repair by homologous recombination (HR). DNA damage plays an interesting role in the majority of mechanisms underlying the effects of antitumor drugs, since the genetic activity of the plethora of these agents is due to their ability to damage the DNA. The DNA-effects of antitumor agents towards normal cells (genotoxicity) are great drawbacks of antitumor therapy and are connected to important adverse health effects in cancer patients undergoing chemotherapy. On the other hand, failure of chemotherapy in many cases is due to the DNA repair ability which cancer, like normal cells, also possess. As both DNA repair and genotoxic exposure are expected to vary among patients, correlating SCEs frequencies with only individual repair capacity may be feasible to predict. Cancer risk has not been observed to be associated with high SCEs levels. Since the administration of effective antitumor drugs with limited adverse effects is of great importance in the success of anticancer therapy, a lot of interest has been directed toward the development of methods and approaches that would enable the correct selection of appropriate drugs prior to the initiation of therapy on an individual basis. To this effect, more than 30 years ago, an investigation of the ability of the in vitro and the in vivo SCEs-assay to predict the in vitro and in vivo sensitivity of tumor cells to newly synthesized drugs or to those already in use began. In this short review a critical appraisal of the SCEs-assay as an important biomarker used for predicting cancer chemo-response as well as a summary of the key findings from several studies published within the last 20 years in this field is performed. PMID:27265374

  14. Characterization of the enhancing effect of caffeine on sister-chromatid exchanges induced by ultraviolet radiation in excision-proficient xeroderma pigmentosum lymphoblastoid cells

    International Nuclear Information System (INIS)

    Cells of some excision-proficient xeroderma pigmentosum (XP) cell lines are highly sensitive to post-UV caffeine treatment in terms of sister-chromatid exchange (SCE) induction as well as cell lethality. In the present study, the authors conducted a detailed investigation of the enhancing effect of caffeine on SCE frequency induced by UV in excision-proficient XP cells, and obtained the following results. (1). Continuous post-UV treatment with 1mM caffeine markedly enhances UV-induced SCEs and such enhanced SCEs occur with similar frequency during either the 1st or the 2nd cell cycle in the presence of caffeine and 5-bromodeoxyuridine (BrdUrd). (2) The high sensitivity of the cells to post-UV caffeine treatment persists for at least 2 days after UV when irradiated cells are held in either the proliferating of the nonproliferating state prior to the addition of BrdUrd. (3) Caffeine exerts its effect on cells in S phase. The most likely explanation for our findings is as follows. In excision-proficient XP cells, the cause of SCE formation such as UV-induced lesions or resulting perturbations of DNA replication persists untill the 2nd round or more of post-UV DNA replication. If caffeine is given as post-UV treatment, such abnormalities may be amplified, resulting in a synergistic increase in SCE frequency. (author). 21 refs.; 4 figs.; 4 tabs

  15. Repairability during G 1 phase of inducting lesions of sister chromatid exchange produced by mitomycin C in salivary gland cells of mice In Vivo

    International Nuclear Information System (INIS)

    The repairability of the injuries that lead to the formation of sister chromatid exchange (SCE) produced by mitomycin C (MMC) with a dose of 2.1 mg/g in vivo, during the G 1 phase in the first cycle of cellular division (before the incorporation of BrdU [5-bromo-2 deoxyurine] to the DNA), as well as during the G 1 phase of the second cycle of cellular division (after the incorporation of BrdU) were analyzed. A 35.1% decrease in the frequency of SCE produced by Mitomycin C was observed, in the early G 1 phase of the first division, with respect to the frequency of SCE induced in the later G 1 phase. When Mitomycin C is given to cells whose DNA is substituted with BrdU in only one of the chain's filaments such decrease is not observed. The results suggest that the injuries caused by MMC, which give place to the SCE, in cells of the salivary glands of the mouse in vivo, are partially repaired only when induced in DNA which has not been substituted with BrdU. (Author)

  16. The nature of high frequency sister chromatid exchange cells (HFCs).

    Science.gov (United States)

    Ponzanelli, I; Landi, S; Bernacchi, F; Barale, R

    1997-09-01

    We employed the three-way differential staining technique (TWD), which allows SCEs to be distinguished on a per generation basis by scoring third metaphases (M3), in order to study the spontaneous levels of SCEs in normal and high frequency cells (HFCs) that occurred in the first (S1), second (S2) and third (S3) S phases. Fifty one of 900 lymphocytes from 37 healthy donors were defined as HFCs by calculating the 95th percentile of the distribution of SCEs in S1 + S2. 'Normal' cells presented almost the same number of SCEs after the first, second and third cell cycles (SCE averages of 2.43, 2.04 and 3.53 respectively). In contrast, HFCs showed a higher SCE count in S1, which decreased rapidly through the cycles and reached baseline level at S3 (SCE averages of 7.18, 4.29 and 3.45 respectively). This would suggest that the lesions responsible for the higher SCE frequency in HFCs were effectively removed after two cell cycles and strongly support the hypothesis that HFCs are lymphocytes which accumulate higher levels of DNA lesions through time. PMID:9379910

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

    OpenAIRE

    Knaap, van der, J.A.; A.G.A.C.; Bergkamp; W.G.M.; Groot, de, C.P.G.M.; M.G.

    1987-01-01

    Methacrylamide is onderzocht in een test op chromosoomafwijkingen en een test op zuster-chromatide uitwisselingen (SCE's) in V79 Chinese hamster cellen in vitro ; vanwege lage toxiciteit konden hoge concentraties (tot 10 mg/ml, 117,4 mmol/l) worden getest. Methacrylamide induceerde een significate, concentratie gerelateerde toename in het aantal SCE's per cel vanaf 2,5 mg/ml (29,4 mmol/l) zowel in aan- als in afwezigheid van metabolische activering. Daarentegen zijn er onvoldoende a...

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

    OpenAIRE

    Knaap, van der, J.A.; A.G.A.C.; Bergkamp; W.G.M.; Groot, de, C.P.G.M.; M.G.

    1987-01-01

    Vinyltolueen induceert geen chromosoomafwijkingen in V79 Chinese hamster cellen, noch in aanwezigheid noch in afwezigheid van ratte S9 als systeem voor metabolische activering. In dezelfde cellen wordt wel een inductie van zuster chromatide uitwisselingen (SCE's) gevonden door vinyltolueen, maar alleen in aanwezigheid van metabolische activering. Er wordt verondersteld dat een tweetal metabolieten verantwoordelijk is voor de genotoxische werking van vinyltolueen.

  19. Inhibition of UV-induced sister chromatid exchanges in ICR 2A frog cells by pretreatment with γ-rays

    International Nuclear Information System (INIS)

    Exposure of ICR 2A frog cells to UV induced the formation of sister chromatid exchanges (SCEs). However, pretreatment of UV-irradiated cells with γ-rays resulted in a reduction in the level of SCEs, confirming the prediction made by the replication model for SCE induction. This effect was observed over a range of UV fluences (1-5 J/m/sup 2/) and γ-ray doses (50-500 rad). The depression in the yield of SCEs was greatest when the cells were UV-irradiated either immediately or 3 h after γ-irradiation. Following a 6 h incubation, the reduction was much less pronounced while at 48 h the level of SCEs was nearly identical to that of cells exposed to UV alone. This corresponds roughly to the kinetics of depression and recovery in DNA synthesis after γ-irradiation of ICR 2A cells. Hence, these results support the hypothesis that the depression of UV-induced SCEs was the result of a delay in replicon initiation caused by //i/-irradiation

  20. Frequency of sister chromatid exchange and chromosomal aberrations in asbestos cement workers.

    OpenAIRE

    Fatma, N; Jain, A. K.; Rahman, Q

    1991-01-01

    Exposure to asbestos minerals has been associated with a wide variety of adverse health effects including lung cancer, pleural mesothelioma, and cancer of other organs. It was shown previously that asbestos samples collected from a local asbestos factory enhanced sister chromatid exchanges (SCEs) and chromosomal aberrations in vitro using human lymphocytes. In the present study, 22 workers from the same factory and 12 controls were further investigated. Controls were matched for age, sex, and...

  1. "Sister Chromatid Exchanges and Micronuclei in Lymphocyte of Nurses Handling Antineoplastic Drugs"

    OpenAIRE

    Ansari-Lari, M; M.Saadat; Shahryari, M.; DD Farhud

    2001-01-01

    Individuals handling antineoplastic drugs or their wastes may absorb these potent genotoxic agents. The effects of handling antineoplastic drugs were examined in a group of 24 nurses working in the hematology and oncology departments of two different university hospitals in Shiraz (Iran) and in a group of 18 unexposed nurses as control group. The cytogenetic repercussions of exposure were assessed by examining sister chromatid exchanges (SCEs) and micronuclei (Mn) in circulating lymphocytes. ...

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

    OpenAIRE

    Knaap, van der, J.A.; A.G.A.C.; Bergkamp; W.G.M.; Groot, de, C.P.G.M.; M.G.

    1986-01-01

    Vinylacetaat bleek een clastogene werking te hebben in een test op chromosoomafwijkingen met Chinese hamstercellen in vitro vanaf 0,25 mmol/l zowel in aan- als in afwezigheid van een systeem voor metabolische activering (S9). Tevens induceerde vinylacetaat in deze cellen een sifnificante toename in het aantal zuster-chromatide uitwisselingen (SCE's) per cel, zowel in aan als in afwezigheid van een systeem voor metabolische activering (S9) bij concentraties van 0,03125 ul/ml (respectievel...

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

    OpenAIRE

    Knaap, van der, J.A.; A.G.A.C.; Bergkamp; W.G.M.; Groot, de, C.P.G.M.; 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 toename in het aantal zuster-chromatide uitwisselingen (SCE's) per cel, zowel in aan- als afwezigheid van een systeem voor metabolische activering (S9) bij concentraties van 0,6 en 1 mg/ml (respec...

  4. Photoreactivation of ultraviolet light-induced sister chromatid exchanges in potorous cells

    International Nuclear Information System (INIS)

    Exposure to visible light after UV-irradiation showed a remarkable effect on UV-induced sister chromatid exchanges (SCEs). After 6-h exposure to visible light (3 x 105 J/m2), two-thirds of the UV-induced SCEs were prevented, confirming Kato's findings. (Nature 249, 552-3, 1974) Exposure to visible light before UV irradiation had no effect. This effect of visible light on UV-induced CSEs was temperature dependent, suggesting the presence of enzymatic photoreactivation. (author)

  5. Cultured mouse embryos metabolize benzo[a]pyrene during early gestation: genetic differences detectable by sister chromatid exchange.

    OpenAIRE

    Galloway, S M; Perry, P E; Meneses, J. (Julio); Nebert, D W; Pedersen, R A

    1980-01-01

    Mouse embryos explanted at 7 1/2 or 8 1/2 days of gestation were cultured in medium containing benzo[a]pyrene and supplemented with 5-bromodeoxyuridine to allow detection of sister chromatid exchanges. The murine Ah locus regulates the inducible metabolism of polycyclic hydrocarbons such as benzo[a]pyrene. A high frequency of sister chromatid exchange was induced by benzo[a]pyrene in embryos from three Ah-"responsive" inbred strains (BALB/cDub, C3H/AnfCum, and C57BL/6N); there was little or n...

  6. Delayed SCE frequency of rat bone marrow cells after radon inhalation

    International Nuclear Information System (INIS)

    Cytogenetic tests can reflect in vivo cellular modifications during development of induced neoplasic lesions. These last years, a new experimental in vivo cytogenetic test has been widely developed: Sister chromatid exchanges (SCE) especially on bone marrow cells. This study establishes the relationships between SCE in the bone marrow of rat and post exposure time following whole body neutron irradiation and radon inhalation. From the observed data a two stages response is pointed out. The first stage is thought to correspond to direct DNA damage and is characterized by a short term increase of bone marrow SCE followed by a rapid decrease up to the control values. The second one is marked by a delayed increase of SCE followed by a plateau significantly higher than the control values. From neutron radon exposure and from previously observed data this second stage strongly suggests a modification of the whole organism induced by 'mutagen/carcinogen' modified target organs

  7. Effects of infliximab on sister chromatid exchanges and chromosomal aberration in patients with rheumatoid arthritis.

    Science.gov (United States)

    Atteritano, M; Mazzaferro, S; Mantuano, S; Bagnato, G L; Bagnato, G F

    2016-03-01

    The aim of this study was to evaluate in a 24-weeks the effect of anti-TNF-alpha, infliximab, on cytogenetic biomarkers in peripheral lymphocytes of patients with rheumatoid arthritis (RA). A total of 40 patients with RA met the criteria to be treated with methotrexate (15 mg/week) were evaluated. Twenty patients, randomly selected, were treated with infliximab in addition to methotrexate (group I), whereas the other 20 patients continued with only methotrexate treatment (group M). Twenty healthy volunteers matched for age, gender and smoking habits served as control group (group C). At baseline, sister chromatid exchange rate was 7.20 ± 2.21 in group I, 7.40 ± 1.60 in group M and 4.97 ± 1.32 in group C (P < 0.01 vs group I and M). After 24-weeks, sister chromatid exchange rate was 7.87 ± 2.54 in group I and 7.81 ± 1.95 in group M (P = ns). High frequency cells count was 4.9 % and 4.7 % in the groups I and M, respectively, at the end of the study (P = ns). The basal chromosomal aberration frequency was 4.90 % in group I and 5.20 % in groups M; after 24-weeks, this was 5.10 % in group I and 5.10 % in groups M (P = ns). Infliximab treatment, for 24 weeks, did not increase the cytogenetic biomarkers in patients with RA. Our data show that the use of infliximab has not a genotoxic effect in patients with RA. PMID:26012953

  8. 12-O-Tetradecanoyl-phorbol-13-acetate and its relationship to SCE induction in Syrian and Chinese hamster cells

    International Nuclear Information System (INIS)

    12-O-Tetradecanoyl-phorbol-13-acetate (TPA) in conditions that produce enhancement of ultraviolet light (UV) and x-irradiation Syrian hamster embryo cell (HEC) transformation did not cause further increase in the sister chromatid exchange (SCE) frequency induced by UV and x-irradiation, two physical carcinogens that differ in their mode of DNA interaction and efficiency of SCE induction. Several factors which might influence SCE induction by TPA were studied on HEC and Chinese hamster V79-4 cells. Heat-inactivated serum was used because of the possibility that a serum component may interfere with TPA ability to cause SCE. TPA effect on SCE was determined at the first and second division post treatment on cells exposed to different 5-bromodeoxyuridine (BrdUrd) concentrations. Independent of BrdUrd concentration (1-10μg/ml medium) and the number of cells divisions post treatment, TPA (0.01-2μg/ml medium) was ineffective in inducing SCE in exponentially and stationary HEC cultures cultivated in medium supplemented with heat-inactivated serum. Also, TPA did not increase the SCE frequency in V79-4 Chinese hamster cells cultured in heat-activated or noninactivated serum. Although SCE induction, a cellular response to carcinogen-induced DNA damage, may be important for the induction of transformation by environmental agents, the enhancement of transformation frequency caused by TPA occurs without further DNA alterations involved in SCE formation

  9. Onderzoek naar de inductie van chromosoomafwijkingen en "sister- chromatid exchanges" door 2,3-epoxypropylmethacrylaat met Chinese hamster cellen in vitro

    OpenAIRE

    Knaap, van der, J.A.; A.G.A.C.; Bergkamp; W.G.M.; Groot, de, C.P.G.M.; M.G.

    1986-01-01

    2,3-epoxypropylmethacrylaat of glycidylmethacrylaat bleek een clastogene werking te hebben in een test op chromosoomafwijkingen met Chinese hamster cellen in vitro, zowel in aan- als afwezigheid van een systeem voor metabolische activering (S9), bij concentraties vanaf 0,03 ul/ml (0,23 mmol/l). Tevens induceerde 2,3-epoxypropylmethacrylaat in deze cellen een significante toename in het aantal zuster-chromatide uitwisselingen (SCE's) per cel, zowel in afwezigheid van metabolische activeri...

  10. Inhibition of protein synthesis does not antagonize induction of UV-induced sister-chromatid exchange in xeroderma pigmentosum cells

    International Nuclear Information System (INIS)

    Cycloheximide strongly antagonizes the induction of sisterchromatid exchanges by ethyl methanesulfonate or mitomycin C in human skin fibroblast and xeroderma pigmentosum cells (group A). Analogous behavior has been observed in several other species including Chinese hamster and plant cells. This report documents an exception to that pattern: cycloheximide fails to antagonize UV-induced sister chromatid exchange in xeroderma pigmentosum cells, whereas it does in normal human skin fibroblast cells. A genetic defect in these cells is postulated to alter the UV-mediated DNA recombination process. (author)

  11. Erythrocytes modulate cell cycle progression but not the baseline frequency of sister chromatid exchanges in pig lymphocytes

    Directory of Open Access Journals (Sweden)

    Miguel A. Reigosa

    1997-09-01

    Full Text Available The effect of co-culturing varying concentrations of pig and human red blood cells (RBCs on the baseline frequency of sister chromatid exchanges (SCEs and cell-cycle progression in pig plasma (PLCs and whole blood leukocyte cultures (WBCs was studied. No variation in SCE frequency was observed between pig control WBC and PLC. Addition of pig and human RBCs to pig PLCs did not modify the baseline frequency of SCEs. On the other hand, cell proliferation was slower in PLCs than in WBCs. The addition of pig or human RBCs to PLCs accelerated the cell-cycle progression of pig lymphocytes. When RBCs were added to PLCs the concentration and time sequence of RBC incorporation affected the cell-cycle progression of swine lymphocytes. When doses of pig or human RBCs equivalent to those present in WBCs were added immediately after PLC stimulation, the cell-cycle kinetics were similar to those of WBCs. Shorter co-incubation periods or a reduction in the dose of RBCs made cell-cycle progression intermediate between PLC and WBC values. Thus, pig and human RBCs modulated the in vitro cell-cycle progression of pig lymphocytes in a time- and dose-dependent manner, and the low baseline frequency of SCEs of pig lymphocytes is independent of the presence or absence of erythrocytes in cultureFoi estudado o efeito de co-culturas com concentrações variadas de células sangüíneas vermelhas (RBCs suínas e humanas na freqüência basal de trocas de cromátides irmãs (SCEs e na progressão do ciclo celular em culturas de plasma de porco (PLCs e culturas leucocitárias do sangue total (WBCs. Não foi observada nenhuma variação na freqüências de SCEs entre os controles de WBC e PLC em porcos. A adição de RBCs de suínos e humanos a PLCs não modificou a freqüência basal de SCEs. Por outro lado, a proliferação celular foi mais lenta em PLCs que em WBCs. A adição de RBCs humanas ou suínas a PLCs acelerou a progressão do ciclo celular de linfócitos su

  12. Photoreactivation of UV induced cell killing, chromosome aberrations, sister chromatide exchanges, mutations and pyrimidine dimers in Xenopus laevis fibroblasts

    International Nuclear Information System (INIS)

    Fibroblasts from Xenopus laevis, which posses photoreactivating enzyme were used to study the influence of photoreactivating light on the frequency of pyrimidine dimers in DNA, chromosomal aberrations, sister chromatid exchanges, cell killing and the induction of gene mutations (ouabain-resistance) induced by 254 nm ultraviolet irradiation. The frequency of all biological endpoints studied were reduced following exposure to photoreactivating light parallel to the reduction in the frequencies of pyrimidine dimers (determined as endonuclease sensitive sites). However, there was not always an absolute quantitative relationship between the reduction in the frequency of pyrimidine dimers and the reduction in the biological effects. This probably reflects a fast fixation process for the biological effects prior to removal of the dimers by photoreactivation. (orig.)

  13. Induction of sister-chromatid exchanges in ICR 2A frog cells exposed to 254 nm UV wavelengths

    International Nuclear Information System (INIS)

    Exposure of ICR 2A frog cells to 254 nm UV induced the formation of sister-chromatid exchanges (SCEs) in a fluence-dependent manner. Cells were also exposed to the UV produced by a fluorescent sunlamp that was filtered through 8C Mylar in order to simulate the mid-UV (290-320 nm) portion of sunlight reaching the earth's surface. In this instance, SCEs were induced in a linear fashion at low fluences but reached a plateau at a low level of induced SCEs. In addition, pretreatment of cells with the solar UV followed by exposure to 254 nm UV resulted in a significantly lower level of SCEs than in cells exposed to 254 nm UV alone. (author)

  14. 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)

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

    International Nuclear Information System (INIS)

    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

  16. DNA single strand breakage, DNA adducts, and sister chromatid exchange in lymphocytes and phenanthrene and pyrene metabolites in urine of coke oven workers.

    OpenAIRE

    W. Popp; Vahrenholz, C.; Schell, C; Grimmer, G.; Dettbarn, G; Kraus, R.; Brauksiepe, A; Schmeling, B; Gutzeit, T; von Bülow, J; Norpoth, K

    1997-01-01

    OBJECTIVES: To investigate the specificity of biological monitoring variables (excretion of phenanthrene and pyrene metabolites in urine) and the usefulness of some biomarkers of effect (alkaline filter elution, 32P postlabelling assay, measurement of sister chromatid exchange) in workers exposed to polycyclic aromatic hydrocarbons (PAHs). METHODS: 29 coke oven workers and a standardised control group were investigated for frequencies of DNA single strand breakage, DNA protein cross links (al...

  17. Hypersensitivity to mutation and sister-chromatid-exchange induction in CHO cell mutants defective in incising DNA containing UV lesions

    International Nuclear Information System (INIS)

    Five UV-sensitive mutant strains of CHO cells representing different genetic complementation groups were analyzed for their ability to perform the incision step of nucleotide excision repair after UV exposure. The assay utilized inhibitors of DNA synthesis to accumulate the short-lived strand breaks resulting from repair incisions. After 6 J/m2, each of the mutants showed 2, the rate in AA8 was similar to that at 6 J/m2, but the rates in the mutants were significantly higher (approx. 20% of the rate of AA8). Thus by this incision assay the mutants were phenotypically indistinguishable. Each of the mutants were hypersensitive to mutation induction at both the hprt and aprt loci by a factor of 10, and in the one strain tested ouabain resistance was induced sevenfold more efficiently than in AA8 cells. Sister chromatid exchange was also induced with sevenfold increased efficiency in the two mutant strains examined. Thus, here CHO mutants resemble xeroderma pigmentosum cells in terms of their incision defects and their hypersensitivity to DNA damage by UV

  18. The chromosome damage induced by x-ray radiation doses. Comparison between dicentric chromosomes, micronuclei and Sister Chromatid Exchanges analyses

    International Nuclear Information System (INIS)

    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)

  19. Evaluation of radioprotection properties of propolis by chromosomal alterations, cell proliferation kinetics, mitotic index and sister chromatid exchange

    International Nuclear Information System (INIS)

    A consequence of ionizing radiation is the induction of chromosomal alterations. This causality relation involves that chromosomal alterations can be considered a good indicator of the radiological damage. Some chemical agents can modulate the tissue response to radiation. These compounds are useful because they show certain selectivity, protecting the healthy tissues (radioprotectors) or increasing the sensibility of tissues to radiations (radiosensibilizators). Propolis substance has showed radioprotection properties which are performed in the following study. Propolis is a product of extraordinary interest for both medicine and pharmaceutical industry, since it is assumed to show diverse beneficial health effects. Among many other attributes of EEP (propolis ethanolic extract), it exhibits antioxidant and radical free scavenger properties. In a previous study, human peripheral blood lymphocytes were exposed to 2 Gy of γ rays in presence and absence of EEP, and the analysis showed a reduction in the frequency of dicentrics and rings, with a maximum protection of 50%. The proposed concentration for radioprotection would be between 120-500 μg.ml-1. The cytotoxic effect has been evaluated analyzing the EEP effect in the cellular division cycle. Propolis ethanolic extract (EEP) has been obtained and samples of peripheral blood have been cultured in the presence of increasing concentrations of EEP. In order to quantify it, two indexes have been used, the mitotic index and cell proliferation index. For both indexes the cytotoxic effect takes place from 750 μg.ml-1 concentrations onwards. Similar results were obtained for the analysis of chromosomal aberrations. Finally, propolis effect in lymphocytes by sister chromatid exchange test has been presented for higher concentrations of EEP. (author)

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

    International Nuclear Information System (INIS)

    The SCE base level frequency and SCE levels induced by far-UV (254 nm) treatment of cells in early G1 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. (orig.)

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

    OpenAIRE

    Knaap, van der, J.A.; A.G.A.C.; Bergkamp; W.G.M.; Groot, de, C.P.G.M.; M.G.

    1987-01-01

    Divinylbenzeen induceert geen chromosoomafwijkingen in Chinese hamster cellen in vitro, noch in aanwezigheid noch in afwezigheid van een systeem voor metabolische activering ; divinylbenzeen induceert in deze cellen wel zusterchromatide uitwisselingen (SCE's) maar alleen in aanwezigheid van een systeem voor metabolische activering. Er zijn aanwijzingen dat tijdens de metabolische omzetting van divinylbenzeen, via een epoxide, onder speciale omstandigheden ook chromosoomafwijkingen kunnen...

  2. Use of a ring chromosome and pulsed-field gels to study interhomolog recombination, double-strand DNA breaks and sister-chromatid exchange in yeast

    International Nuclear Information System (INIS)

    The authors describe a system that uses pulsed-field gels for the physical detection of recombinant DNA molecules, double-strand DNA breaks (DSB) and sister-chromatid exchange in the yeast Saccharomyces cerevisiae. The system makes use of a circular variant of chromosome II (Chr. III). Meiotic recombination between this ring chromosome and a linear homolog produces new molecules of sizes distinguishable on gels from either parental molecule. They demonstrate that these recombinant molecules are not present either in strains with two linear Chr. III molecules or in rad50 mutants, which are defective in meiotic recombination. In conjunction with the molecular endpoints. They present data on the timing of commitment to meiotic recombination scored genetically. They have used x-rays to linearize circular Chr. III, both to develop a sensitive method for measuring frequency of DSB and as a means of detecting double-size circles originating in part from sister-chromatid exchange, which they find to be frequent during meiosis

  3. Cells from an immunodeficient patient (46BR) with a defect in DNA ligation are hypomutable but hypersensitive to the induction of sister chromatid exchanges

    International Nuclear Information System (INIS)

    A fibroblast cell strain, 46BR, derived from an immunodeficient patient is hypersensitive to the lethal effects of a wide range of DNA-damaging agents. It is also defective in strand-break rejoining after treatment with dimethyl sulfate and UV light. The present study shows that the cells have a defect in joining Okazaki-type fragments during DNA replication, supporting the interpretation that the basic defect is in ligation of DNA strands. The baseline level of sister chromatid exchange is slightly higher than in normal cells but it does not approach that of Bloom's syndrome or dyskeratosis congenita cells. Sensitivity to the induction of sister chromatid exchange and the hypersensitivity to the lethal effects of a set of DNA-damaging agents are correlated, implying that the basic defect influences both end points in similar manner. No 6-thioguanine-resistant mutants could be induced by either γ- or UV-irradiation in these cells, suggesting that error-prone repair pathways for damage induced by these agents may contain a common ligation step in human cells

  4. Gossypol induces DNA strand breaks in human fibroblasts and sister chromatid exchanges in human lymphocytes in vitro.

    OpenAIRE

    Nordenskjöld, M.; Lambert, B.

    1984-01-01

    The male contraceptive agent gossypol was found to induce a dose related increase of DNA strand breaks in human fibroblasts in vitro at concentrations of 5 to 40 micrograms/ml. The effect was reduced in the presence of 2% fetal calf serum. A weak but reproducible increase in the SCE frequency was found in human lymphocytes treated for 1 hour in serum-free medium with 0.04 to 4 micrograms/ml of gossypol.

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

    OpenAIRE

    Knaap, van der, J.A.; A.G.A.C.; Bergkamp; W.G.M.; Groot, de, C.P.G.M.; M.G.

    1986-01-01

    Methylmethacrylaat of methacrylzure-methyl-ester bleek een clastogene werking te hebben in een test op chromosoomafwijkingen met Chinese hamster cellen in vitro, zowel in afwezigheid van een systeem voor metabolische activering (S9), bij concentraties vanaf 3 ul/ml 28,2 mmol/l), als in aanwezigheid van metabolische activering (S9) bij concentraties vanaf 2 ul/ml (18,8 mmol/l). Tevens induceerde methylmethacrylaat in deze cellen een significante toename in het aantal zuster-chromatide uitwisse...

  6. Sister chromatid exchanges, hyperdiploidy and chromosomal rearrangements studied in cells from melanoma-prone individuals belonging to families with the dysplastic nevus syndrome.

    Science.gov (United States)

    Jaspers, N G; Roza-de Jongh, E J; Donselaar, I G; Van Velzen-Tillemans, J T; van Hemel, J O; Rümke, P; van der Kamp, A W

    1987-01-01

    Cytogenetic investigations were performed on 25 individuals belonging to six melanoma-prone families with multiple melanocytic lesions (the dysplastic nevus syndrome, DNS). Patients having DNS with or without a history of melanoma were compared with clinically normal relatives and unrelated normal controls. The results indicate normal frequencies of hyperdiploidy and spontaneous sister chromatid exchanges in the fibroblasts of all individuals studied. Karyotypic analyses were carried out on the members of one family. The patients with DNS had a normal constitutional karyotype. In lymphocytes or fibroblasts from five patients, however, increased frequencies of cells with random chromosomal rearrangements were observed. These abnormalities, mainly translocations and inversions, were not found in two of the patients' spouses and in six clinically normal relatives. In the fibroblast cultures considerable clonal selection of cytogenetically abnormal cells occurred. PMID:3791172

  7. Induction of chromosome aberrations, sister chromatid exchanges and specific locus mutations by radiation and chemicals, and the application of the studies to population monitoring and risk estimation

    International Nuclear Information System (INIS)

    The major portion of the research of the Mammalian Cytogenetics Group can be considered to be directed towards estimating the genetic risk, and potentially the carcinogenicity, of radiation and chemical exposures to man. The approach taken is to attempt to determine the mechanism of induction of chromosome aberrations, sister chromatid exchanges and specific locus mutations, and to apply the information obtained to the interpretation of data from currently used assay systems, or for the development of new, more sensitive, or more predictive, assays. This report is divided into several sections, each one representing a separate series of experiments. There is a logical progression to the sections, and there is a clear relationship between them. The sections are: (1) x-ray-induced chromosome aberrations and the involvement of repair of DNA base damage; (2) hypothesis for the mechanism of induction of chromosome aberrations; (3) the induction of chromosome aberrations in lymphocytes from Down's syndrome individuals; (4) the induction of chromosome aberrations by chemical agents; (5) interactive effects of radiation and chemical agents; (6) risk estimation and population monitoring; (7) the mechanism of induction of sister chromatid exchanges and specific locus mutations; and (8) studies with a transplantable mouse myeloid leukemia - an animal model. The intention of these studies is to improve our ability to extrapolate from data obtained with laboratory animals to the likely outcome in man, in order to provide estimates of the genetic, and potentially the carcinogenic, risk to man from exposures to radiation and chemical agents. There are several studies that have been recently initiated but are not reported here because of limited results so far. These particularly involve the development or improvement of assay systems to provide a greater predictive value or greater sensitivity

  8. A comparative investigation of DNA strand breaks, sister chromatid exchanges and K-ras gene mutations induced by cadmium salts in cultured human cells

    International Nuclear Information System (INIS)

    Cadmium (Cd) is a toxic heavy metal of continuing occupational and environmental concern with a wide variety of adverse effects. Several studies have shown that cadmium produces DNA strand breaks, DNA-protein cross-links, oxidative DNA damage, chromosomal aberrations, dysregulation of gene expression resulting in enhanced proliferation, depressed apoptosis and/or altered DNA repair. This study was undertaken to investigate the ability of cadmium chloride (CdCl2) and cadmium sulphate (CdSO4) to induce point mutations in codon 12 of the K-ras protooncogene assessed by polymerase chain reaction-single strand conformation polymorphisms (PCR-SSCP) and RFLP-enriched PCR methods. Also their genotoxic effects were analyzed by the comet assay and sister chromatid exchanges test. The human lung fibroblast cell line MRC-5 was used for the experiments. Sister chromatid exchanges assay (SCEs) frequencies were significantly increased in cells exposed to cadmium salts in relation to controls (p < 0.001). Despite the slow increment observed in the three comet parameters considered when cells were treated with cadmium chloride, significant differences between groups were only found in the variable comet moment (CM) (p < 0.005). On the other hand, when cells were exposed to cadmium sulphate, the Kruskal-Wallis test showed highly significant differences between groups for migration, tail moment and comet moment parameters (p < 0.001). Nevertheless, a null or weak point mutation induction in K-ras protooncogene was detected using polymerase chain reaction-low ionic strength-single strand conformation polymorphisms (PCR-LIS-SSCP) and RFLP-enriched PCR methods when cells were treated with cadmium salts. Thus, inorganic cadmium produces genotoxicity in human lung fibroblast MRC-5 cells, in the absence of significant point mutation of the K-ras gene

  9. Relationship of enhanced survival during confluent holding recovery in ultraviolet-irradiated human and mouse cells to chromosome aberrations, sister chromatid exchanges, and DNA repair

    International Nuclear Information System (INIS)

    The relationship among cellular recovery from ultraviolet light (UVL) damage, cytogenetic changes, and DNA repair was studied in density-inhibited cultures of mouse 10T1/2 cells and human diploid fibroblasts. Both cell types showed similar UVL sensitivites to cell killing and a similar enhancement in survival when subculture to a low density was delayed for 24-48 hr after irradiation (potential lethal damage repair). However, excision repair as measured by the loss of endonuclease-sensitive sites was biphasic and much slower in the mouse cells: 30% were removed in the first 24 hr compared with 60% removed in the first 5 hr in the human cells. More than five times as many excision-induced DNA strand breaks as measured by alkaline elution were detected in the human as compared with the mouse cells. DNA-protein crosslinks were removed with a T 1/2 of 30 hr after 10 J/m2 UVL. UVL induced few chromosomal aberrations in the human cells as compared with mouse cells. The frequency of induced sister chromatid exchanges and the pattern of their decline during recovery were similar in both cell types; the kinetics of this decline was similar to that observed for the removal of DNA-protein crosslinks, and slowly removed endonuclease-sensitive sites. Chromosome aberrations, however, correlated with rapidly removed endo sites and DNA strand breaks and appeared to reflect the number of residual pyrimidine dimers in DNA at the time of its replication

  10. Detection of a deuterium isotope effect in di- and trisubstituted alkylphenylnitrosoureas. An SCE study in Chinese hamster V79-E cells

    International Nuclear Information System (INIS)

    The genotoxicity of 1-methyl-3-phenyl-1-nitrosourea (MPNU), 1-methyl-3-(p-chlorophenyl)-1-nitrosourea (C1-MPNU), 1-ethyl-3-phenyl-1-nitrosourea (EPNU), 1,3-dimethyl-3-phenyl-1-nitrosourea (DMPNU) and their derivatives substituted by deuterium in different positions was studied using sister chromatid exchange (SCE) induction in Chinese hamster V79-E cells. Deuterium substitution in the 1-methyl group of MPNU (MPNU-d3) and C1-MPNU (C1-MPNU-d3) diminished the SCE-inducing capacity by 20-30% and by 30-40% in DMPNU (DMPNU-d3B). There was no altered SCE activity detected when the phenyl group of MPNU (MPNU-d5) or the 3-methyl group of DMPNU (DMPNU-d3A) was deuterium labeled. No isotope effect was detected in deuterated EPNU derivatives, presumably due to the instability of these compounds. It is surmised that the easier delocalization of the positive charge in the deuterated alkyl diazonium ion causes a diminished reactivity and therefore influences the type and amount of DNA alkylation. Furthermore, the experiments with DMPNU and its derivatives revealed that, in contrast to mono- and disubstituted nitrosoureas, the biological activities of these very stable trisubstituted nitrosoureas are strongly influenced by a serum factor in the culture fluid

  11. Induction of sister-chromatid exchanges and chromosome aberrations by γ-irradiated nucleic acid constituents in CHO cells

    International Nuclear Information System (INIS)

    Chinese hamster ovary (CHO) cells were exposed to different concentrations of hydrogen peroxide and to γ-irradiated, oxygenated solutions of thymine, thymidine and 2-deoxy-D-ribose. By using a modified Brd Zrd-labelling method sister-chromated exchanges (SCEs) and chromosomal aberrations were scored in the same cell population, one cycle after treatment. Irradiated, oxygenated solutions of 2-deoxy-D-ribose clearly induced SCEs and chromosomal aberrations. In comparison, hydrogen peroxide and irradiated solutions of thymine and thymidine were less effective in CHO cells. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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 500μl 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)(10μl) 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 μg, 100μg, and 200μg, 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

  14. Composition: S.C.E

    DEFF Research Database (Denmark)

    2012-01-01

    S.C.E. is a large collection of open compositions to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". This work is licensed under a Creative Commons "by-nc" License. You may for non-commercial purposes use and distribute...

  15. Chromatid interchanges at intrachromosomal telomeric DNA sequences

    International Nuclear Information System (INIS)

    Chinese hamster Don cells were exposed to X-rays, mitomycin C and teniposide (VM-26) to induce chromatid exchanges (quadriradials and triradials). After fluorescence in situ hybridization (FISH) of telomere sequences it was found that interstitial telomere-like DNA sequence arrays presented around five times more breakage-rearrangements than the genome overall. This high recombinogenic capacity was independent of the clastogen, suggesting that this susceptibility is not related to the initial mechanisms of DNA damage. (author)

  16. Analysis of chromosomal aberrations, sister-chromatid exchanges and micronuclei in peripheral lymphocytes of pharmacists before and after working with cytostatic drugs.

    Science.gov (United States)

    Roth, S; Norppa, H; Järventaus, H; Kyyrönen, P; Ahonen, M; Lehtomäki, J; Sainio, H; Sorsa, M

    1994-12-01

    The frequencies of chromosome aberrations, SCEs and micronuclei (cytokinesis-block method) in blood lymphocytes were compared among six nonsmoking female pharmacists before and after 1 year of working with cytostatic drugs. All possible precautions were taken to avoid exposure to cytostatics, including proper protective clothing and a monitored, negative-pressured working environment with vertical laminar flow cabinet. As referents, an age-matched group of six nonsmoking female hospital workers not dealing with cytostatics was simultaneously sampled twice with the same time interval. The pharmacists showed a marginally higher mean frequency of SCEs/cell (6.3; P = 0.049) after the working period than 1 year earlier (5.8). On the other hand, the referents, with no obvious exposure, had a higher mean number of cells with chromatid-type aberrations, gaps excluded, in the second sampling (2.0%; P = 0.048) than in the first one (0.5%). In addition, a slight (P = 0.055) trend towards a higher frequency of micronucleated binucleate cells was observed in the second sampling for both the exposed and control subjects. As such findings suggest technical variation in the cytogenetic parameters, the small difference observed in SCEs for the pharmacists between the two samplings was probably not related to the cytostatics exposure. No statistically significant differences were observed for any of the cytogenetic parameters in comparisons between the pharmacists and the referents. The findings suggest that caution should be exercised in comparing results obtained from two different samplings in prospective cytogenetic studies. PMID:7527908

  17. Antimicrobial Activity of Cefmenoxime (SCE-1365)

    OpenAIRE

    Stamm, John M.; Girolami, Roland L.; Shipkowitz, Nathan L.; Bower, Robert R.

    1981-01-01

    The in vitro activity of cefmenoxime (SCE-1365 or A-50912), a new semisynthetic cephalosporin antibiotic, was compared with those of cefazolin, cefoxitin, and cefamandole against a broad spectrum of 486 organisms and with that of cefotaxime against 114 organisms. Cefmenoxime and cefotaxime exhibited nearly equivalent activities against those organisms tested and were the most active of these cephalosporins against all aerobic and facultative organisms except Staphylococcus aureus. The minimum...

  18. Interchromosomal distribution of gamma ray-induced chromatid aberrations in Chinese hamster ovary cells

    International Nuclear Information System (INIS)

    Inter chromosomal distributions of breakpoints from chromatid-type aberrations induced by gamma rays in Chinese hamster ovary cells were analyzed. In most chromosomes the distribution was as expected from chromosome lengths for simple breaks or the respective relative corrected length in case of exchanges. There were deviations from expectation in a few chromosomes for chromatid breaks, interchanges, intra-arm intra changes and inter-arm intra changes. Especially interesting are the results concerning chromosomes 2 and 8, which were more often involved in exchanges than expected. An 'exchange phenotype' for these chromosomes is proposed and possible explanations for the nonrandom distribution of chromosome breakpoints are presented. (author)

  19. Mechanisms of sister chromatid recombination

    International Nuclear Information System (INIS)

    Studies using T948 as a model system have been carried out aimed at elucidating the mechanism of sister chromatid recombination (SCR). Characterization of U.V. light- and x-ray-induced SCR, the relationiship between SCR induction and DNA repair using rad mutations, and the relationship between SCR induction and the time of cell division using cdc mutations are presented. It has been supposed that SCR is induced at the phase of S-G2 following DNA replication, that postreplication break of DNA strands is strongly involved in the induction of SCR, and that induction type of SCR, i.e., conversion type or recombination type, is dependent upon the type of molecular damage of DNA. (Namekawa, K.)

  20. The induction of SCE and chromosomal aberrations with relation to specific base methylation of DNA in Chinese hamster cells by N-methyl-N-nitrosourea and dimethyl sulphate.

    Science.gov (United States)

    Connell, J R; Medcalf, A S

    1982-01-01

    Chinese hamster cells (V79) were treated, either as exponentially proliferating cultures or under conditions where they were density-inhibited, with various doses of the potent carcinogen N-methyl-N-nitrosourea (MNU) or the relatively weak carcinogen dimethylsulphate (DMS). The colony forming ability of these cells and the induced frequencies of sister chromatid exchanges (SCEs) and chromosomal aberrations were assayed. Following the exposure of density-inhibited cells to radio-labelled methylating agents (labelled in the methyl group) these phenomena were related to the levels of 7-methylguanine (7-meGua), O6-methylguanine (O6-meGua) and 3-methyladenine (3-me-Ade) in the DNA. At equitoxic doses MNU and DMS induced similar frequencies of SCEs and chromosomal aberrations. Since, at equitoxic doses, MNU produces approximately 20 times more O6-meGua in V79 cell DNA than does DMS, this indicates that the formation of O6-meGua in DNA is not a major cause of SCEs and chromosomal aberrations. DMS-induced SCEs may be mediated via the production of both 3-meAde and 7-meGua in the DNA; these two methylated purines may also be responsible for MNU-induced SCEs. Therefore, no one specific methylated purine was identified as being solely accountable for the formation of SCEs. Also, the repair of lesions in the DNA of non-replicating V79 cells leads to a reduction in the SCE frequency on their subsequent release from the density-inhibited state, suggesting that repair is not intimately responsible for their formation. No association was discernable between chromosomal aberrations and any of the three methylated purines studied. PMID:7094205

  1. Variation of the symmetrical/asymmetrical ratio in chromatid interchanges during the various phases of the cell cycle of human lymphocytes 'in vitro'

    International Nuclear Information System (INIS)

    Experiments have been performed to verify whether in a human euploid cell system, such as lymphocyte cultures in vitro, there is a differential pattern of induction of chromatid exchanges in the various phases of the cycle. (Auth.)

  2. 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)

  3. A matter of choice: the establishment of sister chromatid cohesion

    OpenAIRE

    Uhlmann, Frank

    2009-01-01

    Sister chromatid cohesion is the basis for the recognition of chromosomal DNA replication products for their bipolar segregation in mitosis. Fundamental to sister chromatid cohesion is the ring-shaped cohesin complex, which is loaded onto chromosomes long before the initiation of DNA replication and is thought to hold replicated sister chromatids together by topological embrace. What happens to cohesin when the replication fork approaches, and how cohesin recognizes newly synthesized sister c...

  4. 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.

  5. 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.

  6. Characterization of muntjac DNA

    International Nuclear Information System (INIS)

    Sister chromatid exchange (SCE) in muntjac chromosomes is generally proportional to the chromosomal DNA content, but the SCE frequency is reduced in the heterochromatic neck region of the X chromosome. The physical properties of muntjac DNA and the kinetics of repair of UV damage in muntjac heterochromatin and euchromatin were examined and compared with the distribution of sister chromatid exchange

  7. Characterization of muntjac DNA

    Energy Technology Data Exchange (ETDEWEB)

    Davis, R.C.

    1981-05-27

    Sister chromatid exchange (SCE) in muntjac chromosomes is generally proportional to the chromosomal DNA content, but the SCE frequency is reduced in the heterochromatic neck region of the X chromosome. The physical properties of muntjac DNA and the kinetics of repair of UV damage in muntjac heterochromatin and euchromatin were examined and compared with the distribution of sister chromatid exchange.

  8. SISTER CHROMATID EXCHANGE AND GENOTOXICITY MEASUREMENTS USING POLYCHAETE WORMS

    Science.gov (United States)

    Contaminants entering coastal marine environments may affect the genetic constitution of exposed organisms by causing shifts in gene pool composition through selective pressures or by acting directly on the genetic material to cause damage. he latter problem is referred to as gen...

  9. Microstructure and Properties of SCE-Al2O3/PES-MBAE Composite

    Directory of Open Access Journals (Sweden)

    Yufei Chen

    2014-01-01

    Full Text Available SCE-Al2O3 was the nano-Al2O3 modified by supercritical ethanol and the surface of SCE-Al2O3 was coated with active group. 4,4′-diaminodiphenylmethane bismaleimide (MBMI was used as matrix; 3,3′-diallyl bisphenol A (BBA and bisphenol-A diallyl ether (BBE were used as reactive diluent, polyethersulfone (PES as toughening agent, and SCE-Al2O3 as modifier; SCE-Al2O3/PES-MBAE nanocomposite was prepared through in situ sol-gel method. The mechanism of composite toughened by PES was observed and analyzed. FTIR indicated that the reaction between MBMI and allyl compound occurred and SCE-Al2O3 had doped into the polymer matrix. SEM showed that PES particle was inlaid in matrix and presented as a two-phase structure in matrix. The heat resistance, dielectric properties, and mechanical properties of SCE-Al2O3/PES-MBAE nanocomposites were evaluated. The results showed that with the incorporation of PES, although the toughness of the material improved, the heat resistance and dielectric properties of material declined, meanwhile. The adulteration of SCE-Al2O3 could remedy the harmful effect caused by PES, while the content of SCE-Al2O3 was reasonable. The decomposition temperature, dielectric constant, and dielectric loss of composite were 441.23°C, 3.63 (100 Hz, and 1.52 × 10−3 (100 Hz; the bending strength and impact strength were 129.22 MPa and 13.19 kJ/mm2, respectively, when the content of SCE-Al2O3 was 3 wt% and PES was 5 wt%.

  10. 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

  11. Identification of protein complexes required for efficient sister chromatid cohesion

    NARCIS (Netherlands)

    Mayer, Melanie L; Pot, Isabelle; Chang, Michael; Xu, Hong; Aneliunas, Victoria; Kwok, Teresa; Newitt, Rick; Aebersold, Ruedi; Boone, Charles; Brown, Grant W; Hieter, Philip

    2004-01-01

    Ctf8p is a component of Ctf18-RFC, an alternative replication factor C-like complex required for efficient sister chromatid cohesion in Saccharomyces cerevisiae. We performed synthetic genetic array (SGA) analysis with a ctf8 deletion strain as a primary screen to identify other nonessential genes r

  12. NREL/SCE High Penetration PV Integration Project: FY13 Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Mather, B. A.; Shah, S.; Norris, B. L.; Dise, J. H.; Yu, L.; Paradis, D.; Katiraei, F.; Seguin, R.; Costyk, D.; Woyak, J.; Jung, J.; Russell, K.; Broadwater, R.

    2014-06-01

    In 2010, the National Renewable Energy Laboratory (NREL), Southern California Edison (SCE), Quanta Technology, Satcon Technology Corporation, Electrical Distribution Design (EDD), and Clean Power Research (CPR) teamed to analyze the impacts of high penetration levels of photovoltaic (PV) systems interconnected onto the SCE distribution system. This project was designed specifically to benefit from the experience that SCE and the project team would gain during the installation of 500 megawatts (MW) of utility-scale PV systems (with 1-5 MW typical ratings) starting in 2010 and completing in 2015 within SCE's service territory through a program approved by the California Public Utility Commission (CPUC). This report provides the findings of the research completed under the project to date.

  13. NOAA Climate Data Record (CDR) of Northern Hemisphere (NH) Snow Cover Extent (SCE), Version 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This NOAA Climate Data Record (CDR) is a record for the Northern Hemisphere (NH) Snow Cover Extent (SCE) spanning from October 4, 1966 to present, updated monthly...

  14. 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)

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

    OpenAIRE

    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 double-strand breaks (DSBs) are considered particularly deleterious. The causative agents can be of endogenous origin, such as metabolically produced free radicals, and of exogenous origin, such a...

  16. Effect of lens tilt on SCE and filamentation characteristics of femtosecond pulses in air

    Science.gov (United States)

    Sreeja, S.; Prashant, T. Shuvan; Leela, Ch.; Kumar, V. Rakesh; Tewari, Surya P.; Venugopal Rao, S.; Kiran, P. Prem

    2012-06-01

    We present the evolution of SCE associated with filaments due to the tilt of focusing lens under tight focusing geometries. Transform limited femtosecond (fs) pulses (800 nm, 45 fs, 1 kHz repetition rate) were focused in ambient air using three different focusing geometries f/#6, f/#7.5, and f/#12 corresponding to numerical apertures (NA) of 0.08, 0.06, and 0.04, respectively. The focusing lens was tilted from zero up to 20 degrees. The filaments decayed into two shorter parts through tilting of the lens and the separation between shorter filaments increased with increasing lens tilt, in tune with earlier reports [Kamali et al., Opt. Commun. 282, 950-954 (2009)]. The separation between the filaments matched well with the predicted distances due to astigmatism induced in loose focusing geometries. However the deviation increased as we moved to the tighter focusing geometries. The SCE spectrum demonstrated an anomalous behaviour. The SCE spectrum was suppressed at larger tilt angles of 12 - 20°. However at lower tilt angles, up to 8°, the SCE was observed to be same to that measured without any tilt of the focusing lens. This behaviour is predominant with tighter focusing geometries of f/#6 and f/#7.5, wherein the SCE was observed to be higher at 4° and 8° in comparison with that observed at an angle of 0°. Systematic study of the focusing lens tilt on anomalous SCE spectra and filament characteristics in the tight focusing geometry are presented.

  17. Structural stability and endonuclease activity of a PI-SceI GFP-fusion protein

    Directory of Open Access Journals (Sweden)

    Alireza G. Senejani, J. Peter Gogarten

    2007-01-01

    Full Text Available Homing endonucleases are site-specific and rare cutting endonucleases often encoded by intron or intein containing genes. They lead to the rapid spread of the genetic element that hosts them by a process termed 'homing'; and ultimately the allele containing the element will be fixed in the population. PI-SceI, an endonuclease encoded as a protein insert or intein within the yeast V-ATPase catalytic subunit encoding gene (vma1, is among the best characterized homing endonucleases. The structures of the Sce VMA1 intein and of the intein bound to its target site are known. Extensive biochemical studies performed on the PI-SceI enzyme provide information useful to recognize critical amino acids involved in self-splicing and endonuclease functions of the protein. Here we describe an insertion of the Green Fluorescence Protein (GFP into a loop which is located between the endonuclease and splicing domains of the Sce VMA1 intein. The GFP is functional and the additional GFP domain does not prevent intein excision and endonuclease activity. However, the endonuclease activity of the newly engineered protein was different from the wild-type protein in that it required the presence of Mn2+ and not Mg2+ metal cations for activity.

  18. 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

  19. Kinetics of chromatid aberrations in G2 ataxia-telangiectasia cells exposed to X-rays and ara A

    International Nuclear Information System (INIS)

    The cytogenetic effects of X-rays alone or in combination with 9-β-D-arabinofuranosyladenine (ara A) were studied in an immortalized fibroblastic line of ataxia-telangiectasia (A-T) cells. It is postulated that the kinetics of disappearance (rejoining) of chromatid deletions with postirradiation incubation time reflects the underlying repair of dsb, and is inhibited by ara A. The rejoining kinetics for deletions in A-T was similar to that found in a previous study of normal human fibroblasts (Mozdarani and Bryant 1987). The number of deletions in X-irradiated A-T cells at 1.5 h before fixation was found to be higher by a factor of approximately 2 than that found previously in normals, indicating that in A-T a higher rate of conversion of dsb into chromatid deletions occurs. The frequency of exchanges induced in G2 A-T cells was similarly enhanced but, unlike the situation in normal cells, ara A was found to cause only a slight increase in this frequency. (author)

  20. Accelerating the SCE-UA Global Optimization Method Based on Multi-Core CPU and Many-Core GPU

    Directory of Open Access Journals (Sweden)

    Guangyuan Kan

    2016-01-01

    Full Text Available The famous global optimization SCE-UA method, which has been widely used in the field of environmental model parameter calibration, is an effective and robust method. However, the SCE-UA method has a high computational load which prohibits the application of SCE-UA to high dimensional and complex problems. In recent years, the hardware of computer, such as multi-core CPUs and many-core GPUs, improves significantly. These much more powerful new hardware and their software ecosystems provide an opportunity to accelerate the SCE-UA method. In this paper, we proposed two parallel SCE-UA methods and implemented them on Intel multi-core CPU and NVIDIA many-core GPU by OpenMP and CUDA Fortran, respectively. The Griewank benchmark function was adopted in this paper to test and compare the performances of the serial and parallel SCE-UA methods. According to the results of the comparison, some useful advises were given to direct how to properly use the parallel SCE-UA methods.

  1. I-SceI enzyme mediated integration (SEMI) for fast and efficient gene targeting in Trichoderma reesei.

    Science.gov (United States)

    Ouedraogo, Jean Paul; Arentshorst, Mark; Nikolaev, Igor; Barends, Sharief; Ram, Arthur F J

    2016-03-20

    We previously showed that creation of a double strand DNA break (DSB) by expressing I-SceI in an engineered Trichoderma reesei (Hypocrea jecorina) strain containing a I-SceI recognition site improved transformation and homologous integration efficiencies. In this study, we further improved homologous integration frequencies by combining I-SceI mediated double strand break with disruption of the tku70 gene. The inability of the tku70 mutant to repair a I-SceI mediated DSB via NHEJ was used to force integration of an expression cassette with homologous flanks surrounding the DSB site. Besides expressing I-SceI from a plasmid, we also show that adding I-SceI enzyme during transformation was successful to generate DSBs. The I-SceI enzyme mediated integration, or SEMI, in combination with a Δtku70 mutant has a synergistic effect on homologous recombination efficiencies as 90-100% of the transformants exhibited integration of the expression cassette at the homologous site. PMID:26860210

  2. Canine adenovirus type 2 vector generation via I-Sce1-mediated intracellular genome release.

    Directory of Open Access Journals (Sweden)

    Sandy Ibanes

    Full Text Available When canine adenovirus type 2 (CAdV-2, or also commonly referred to as CAV-2 vectors are injected into the brain parenchyma they preferentially transduce neurons, are capable of efficient axonal transport to afferent regions, and allow transgene expression for at last >1 yr. Yet, translating these data into a user-friendly vector platform has been limited because CAV-2 vector generation is challenging. Generation of E1-deleted adenovirus vectors often requires transfection of linear DNA fragments of >30 kb containing the vector genome into an E1-transcomplementing cell line. In contrast to human adenovirus type 5 vector generation, CAV-2 vector generation is less efficient due, in part, to a reduced ability to initiate replication and poor transfectibility of canine cells with large, linear DNA fragments. To improve CAV-2 vector generation, we generated an E1-transcomplementing cell line expressing the estrogen receptor (ER fused to I-SceI, a yeast meganuclease, and plasmids containing the I-SceI recognition sites flanking the CAV-2 vector genome. Using transfection of supercoiled plasmid and intracellular genome release via 4-OH-tamoxifen-induced nuclear translocation of I-SceI, we improved CAV-2 vector titers 1,000 fold, and in turn increased the efficacy of CAV-2 vector generation.

  3. Structural Damage Identification of Pipe Based on GA and SCE-UA Algorithm

    Directory of Open Access Journals (Sweden)

    Yaojin Bao

    2013-01-01

    Full Text Available Structure of offshore platform is very huge, which is easy to be with crack caused by a variety of environmental factors including winds, waves, and ice and threatened by some unexpected factors such as earthquake, typhoon, tsunami, and ship collision. Thus, as a main part of the jacket offshore platform, pipe is often with crack. However, it is difficult to detect the crack due to its unknown location. Genetic algorithm (GA and SCE-UA algorithm are used to detect crack in this paper, respectively. In the experiment, five damages of the pipe in the platform model can be intelligently identified by genetic algorithm (GA and SCE-UA. The network inputs are the differences between the strain mode shapes. The results of the two algorithms for structural damage diagnosis show that both of the two algorithms have high identification accuracy and good adaptability. Furthermore, the error of SCE-UA algorithm is smaller. The results also suggest that the structural damage of pipe can be identified by intelligent algorithm.

  4. Genotoxic monitoring of workers at a hazardous waste disposal site in Mexico.

    OpenAIRE

    Gonsebatt, M E; Salazar, A.M.; Montero, R; Díaz Barriga, F; Yáñez, L.; Gómez, H.; Ostrosky-Wegman, P

    1995-01-01

    Chromosomal aberration and sister chromatid exchange (SCE) frequencies were determined in lymphocytes cultured from 12 high-risk individuals working at a landfill for hazardous waste disposal. Cell proliferation kinetics (CPK) was also determined. Compared with 7 control individuals, no effects were observed with respect to SCE nor on CPK. However, the workers exhibited significantly higher frequencies of chromatid and chromosomal deletions, the magnitude of which was related with exposure ti...

  5. Satellite Based Probabilistic Snow Cover Extent Mapping (SCE) at Hydro-Québec

    Science.gov (United States)

    Teasdale, Mylène; De Sève, Danielle; Angers, Jean-François; Perreault, Luc

    2016-04-01

    Over 40% of Canada's water resources are in Quebec and Hydro-Quebec has developed potential to become one of the largest producers of hydroelectricity in the world, with a total installed capacity of 36,643 MW. The Hydro-Québec fleet park includes 27 large reservoirs with a combined storage capacity of 176 TWh, and 668 dams and 98 controls. Thus, over 98% of all electricity used to supply the domestic market comes from water resources and the excess output is sold on the wholesale markets. In this perspective the efficient management of water resources is needed and it is based primarily on a good river flow estimation including appropriate hydrological data. Snow on ground is one of the significant variables representing 30% to 40% of its annual energy reserve. More specifically, information on snow cover extent (SCE) and snow water equivalent (SWE) is crucial for hydrological forecasting, particularly in northern regions since the snowmelt provides the water that fills the reservoirs and is subsequently used for hydropower generation. For several years Hydro Quebec's research institute ( IREQ) developed several algorithms to map SCE and SWE. So far all the methods were deterministic. However, given the need to maximize the efficient use of all resources while ensuring reliability, the electrical systems must now be managed taking into account all risks. Since snow cover estimation is based on limited spatial information, it is important to quantify and handle its uncertainty in the hydrological forecasting system. This paper presents the first results of a probabilistic algorithm for mapping SCE by combining Bayesian mixture of probability distributions and multiple logistic regression models applied to passive microwave data. This approach allows assigning for each grid point, probabilities to the set of the mutually exclusive discrete outcomes: "snow" and "no snow". Its performance was evaluated using the Brier score since it is particularly appropriate to

  6. I-SceI-mediated double-strand DNA breaks stimulate efficient gene targeting in the industrial fungus Trichoderma reesei.

    Science.gov (United States)

    Ouedraogo, Jean Paul; Arentshorst, Mark; Nikolaev, Igor; Barends, Sharief; Ram, Arthur F J

    2015-12-01

    Targeted integration of expression cassettes for enzyme production in industrial microorganisms is desirable especially when enzyme variants are screened for improved enzymatic properties. However, currently used methods for targeted integration are inefficient and result in low transformation frequencies. In this study, we expressed the Saccharomyces cerevisiae I-SceI meganuclease to generate double-strand breaks at a defined locus in the Trichoderma reesei genome. We showed that the double-strand DNA breaks mediated by I-SceI can be efficiently repaired when an exogenous DNA cassette flanked by regions homologous to the I-SceI landing locus was added during transformation. Transformation efficiencies increased approximately sixfold compared to control transformation. Analysis of the transformants obtained via I-SceI-mediated gene targeting showed that about two thirds of the transformants resulted from a homologous recombination event at the predetermined locus. Counter selection of the transformants for the loss of the pyrG marker upon integration of the DNA cassette showed that almost all of the clones contained the cassette at the predetermined locus. Analysis of independently obtained transformants using targeted integration of a glucoamylase expression cassette demonstrated that glucoamylase production among the transformants was high and showing limited variation. In conclusion, the gene targeting system developed in this study significantly increases transformation efficiency as well as homologous recombination efficiency and omits the use of Δku70 strains. It is also suitable for high-throughput screening of enzyme variants or gene libraries in T. reesei. PMID:26272087

  7. Investigations into the molecular mechanism of chromatid breakage in the G2-phase of mammalian cells

    International Nuclear Information System (INIS)

    Chromatid breakage following irradiation of cells in the G2-phase of the cell cycle results from the induction of DNA double-strand breaks (dsb). The conversion of dsb into chromatid breaks (cb) has a genetic basis, seemingly different from that of dsb rejoining. The variation in extent of this conversion is exemplified by the stiking variation in frequency of cb in irradiated cycling T-lymphocytes between different normal individuals. Elevated cb frequency in lymphocytes of around 40% of breast cancer patients and their first-degree relatives suggests the presence of mutations in low penetrance cancer predisposing genes that also affect conversion of dsb to cb. Investigation of the mechanism of chromatid radiosensitivity using genetically engineered rodent cell lines containing unique dsb break sites indicate that a single isolated dsb is sufficient to cause a cb. The single-event nature of chromatid breakage is confirmed by the fact that cb are induced as a linear function of radiation dose. Moreover, we have recently shown that ultrasoft carbon-K X-rays also induce chromatid breakage. In this case the energy of the secondary electrons produced by carbon-K X-rays is too low to span more than one DNA double helix, thus further supporting our conclusion that a single dsb is responsible for the formation of a cb. Chromatid breakage is thought to involve a rearrangement between DNA strands at the crossover points of chromatin loop(s) triggered by the presence of a dsb within the loop structure. The occasional observation of 'looped-out' sections of chromatin at cb sites supports this hypothesis. The occurrence of 'colour-switches' between FPG stained chromatids at a proportion of break sites (e.g. about 16% in CHO cells) shows that a significant proportion of cb definitely result from chromatin rearrangements. Measurements of altered colour-switch ratio (csr) in mutant rodent and human cells (irs1 and AT cells respectively) also indicate a genetic basis for the

  8. Comparison of Performance between Genetic Algorithm and SCE-UA for Calibration of SCS-CN Surface Runoff Simulation

    Directory of Open Access Journals (Sweden)

    Ji-Hong Jeon

    2014-11-01

    Full Text Available Global optimization methods linked with simulation models are widely used for automated calibration and serve as useful tools for searching for cost-effective alternatives for environmental management. A genetic algorithm (GA and shuffled complex evolution (SCE-UA algorithm were linked with the Long-Term Hydrologic Impact Assessment (L-THIA model, which employs the curve number (SCS-CN method. The performance of the two optimization methods was compared by automatically calibrating L-THIA for monthly runoff from 10 watersheds in Indiana. The selected watershed areas ranged from 32.7 to 5844.1 km2. The SCS-CN values and total five-day rainfall for adjustment were optimized, and the objective function used was the Nash-Sutcliffe value (NS value. The GA method rapidly reached the optimal space until the 10th generating population (generation, and after the 10th generation solutions increased dispersion around the optimal space, called a cross hair pattern, because of mutation rate increase. The number of looping executions influenced the performance of model calibration for the SCE-UA and GA method. The GA method performed better for the case of fewer loop executions than the SCE-UA method. For most watersheds, calibration performance using GA was better than for SCE-UA until the 50th generation when the number of model loop executions was around 5150 (one generation has 100 individuals. However, after the 50th generation of the GA method, the SCE-UA method performed better for calibrating monthly runoff compared to the GA method. Optimized SCS-CN values for primary land use types were nearly the same for the two methods, but those for minor land use types and total five-day rainfall for AMC adjustment were somewhat different because those parameters did not significantly influence calculation of the objective function. The GA method is recommended for cases when model simulation takes a long time and the model user does not have sufficient time

  9. Shugoshin1 May Play Important Roles in Separation of Homologous Chromosomes and Sister Chromatids during Mouse Oocyte Meiosis

    OpenAIRE

    Shen Yin; Jun-Shu Ai; Li-Hong Shi; Liang Wei; Ju Yuan; Ying-Chun Ouyang; Yi Hou; Da-Yuan Chen; Heide Schatten; Qing-Yuan Sun

    2008-01-01

    BACKGROUND: Homologous chromosomes separate in meiosis I and sister chromatids separate in meiosis II, generating haploid gametes. To address the question why sister chromatids do not separate in meiosis I, we explored the roles of Shogoshin1 (Sgo1) in chromosome separation during oocyte meiosis. METHODOLOGY/PRINCIPAL FINDINGS: Sgo1 function was evaluated by exogenous overexpression to enhance its roles and RNAi to suppress its roles during two meioses of mouse oocytes. Immunocytochemistry an...

  10. Multiple Rad5 activities mediate sister chromatid recombination to bypass DNA damage at stalled replication forks.

    Science.gov (United States)

    Minca, Eugen C; Kowalski, David

    2010-06-11

    DNA damage that blocks replication is bypassed in order to complete chromosome duplication and preserve cell viability and genome stability. Rad5, a PCNA polyubiquitin ligase and DNA-dependent ATPase in yeast, is orthologous to putative tumor suppressors and controls error-free damage bypass by an unknown mechanism. To identify the mechanism in vivo, we investigated the roles of Rad5 and analyzed the DNA structures that form during damage bypass at site-specific stalled forks present at replication origins. Rad5 mediated the formation of recombination-dependent, X-shaped DNA structures containing Holliday junctions between sister chromatids. Mutants lacking these damage-induced chromatid junctions were defective in resolving stalled forks, restarting replication, and completing chromosome duplication. Rad5 polyubiquitin ligase and ATPase domains both contributed to replication fork recombination. Our results indicate that multiple activities of Rad5 function coordinately with homologous recombination factors to enable replication template switch events that join sister chromatids at stalled forks and bypass DNA damage. PMID:20541998

  11. Role of bromodeoxyuridine in the formation of SCE after γ-irradiation of human lymphocytes at the presynthetic stage of the cell cycle

    International Nuclear Information System (INIS)

    The formation of SCE was studied in human lymphocytes irradiated at the presynthetic stage of the cell cycle in the presence or absence of 5-bromodeoxyuridine. The results obtained showed that 5-bromodeoxyuridine present in the cultur medium at the time of exposure or during the postirradiation period increased the yield of SCE. It is suggested that 5-bromodeoxyuridine exerts its effect through interfering with DNA repair

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

    OpenAIRE

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

    2015-01-01

    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 p31comet. 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 line...

  13. 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...

  14. Genotoxic Evaluation of the Antibacterial Drug, Ciprofloxacin, in Cultured Lymphocytes of Patients with Urinary Tract Infection

    OpenAIRE

    İkbal, Mevlit; DOĞAN, Hasan; Odabaş, Hatice; PİRİM, İbrahim

    2004-01-01

    Ciprofloxacin is a quinolone carboxylic acid derivative and is commonly used in medicine. The genotoxicity of ciprofloxacin was evaluated in cultured human peripheral blood lymphocytes in patients with urinary tract infection. Sister chromatid exchange (SCE), mitotic index (MI) and replicative index (RI) were measured before and after ciprofloxacin therapy. Our results showed that SCE frequency significantly increased after ciprofloxacin therapy (P < 0.001), but MI and RI decreased (P &...

  15. Biomonitoring of genotoxic risk in radar facility workers: comparison of the comet assay with micronucleus assay and chromatid breakage assay

    International Nuclear Information System (INIS)

    Genotoxic risks of occupational exposure in a radar facility were evaluated by using alkaline comet assay, micronucleus assay and chromatid breakage assay on peripheral blood leukocytes in exposed subjects and corresponding controls. Results show that occupational exposure to microwave radiation correlates with an increase of genome damage in somatic cells. The levels of DNA damage in exposed subjects determined by using alkaline comet assay were increased compared to control and showed interindividual variations. Incidence of micronuclei was also significantly increased compared to baseline control values. After short exposure of cultured lymphocytes to bleomycin, cells of occupationally exposed subjects responded with high numbers of chromatid breaks. Although the level of chromosome damage generated by bleomycin varied greatly between individuals, in exposed subjects a significantly elevated number of chromatid breaks was observed. Our results support data reported in literature indicating that microwave radiation represents a potential DNA-damaging hazard. Alkaline comet assay is confirmed as a sensitive and highly reproducible technique for detection of primary DNA damage inflicted in somatic cells. Micronucleus assay was confirmed as reliable bio-markers of effect and chromatid breakage assay as sensitive bio-marker of individual cancer susceptibility. The results obtained also confirm the necessity to improve measures and to perform accurate health surveillance of individuals occupationally exposed to microwave radiation

  16. The Cohesin Subunit Rad21 Is Required for Synaptonemal Complex Maintenance, but Not Sister Chromatid Cohesion, during Drosophila Female Meiosis

    Science.gov (United States)

    Lehner, Christian F.; Heidmann, Stefan K.

    2014-01-01

    Replicated sister chromatids are held in close association from the time of their synthesis until their separation during the next mitosis. This association is mediated by the ring-shaped cohesin complex that appears to embrace the sister chromatids. Upon proteolytic cleavage of the α-kleisin cohesin subunit at the metaphase-to-anaphase transition by separase, sister chromatids are separated and segregated onto the daughter nuclei. The more complex segregation of chromosomes during meiosis is thought to depend on the replacement of the mitotic α-kleisin cohesin subunit Rad21/Scc1/Mcd1 by the meiotic paralog Rec8. In Drosophila, however, no clear Rec8 homolog has been identified so far. Therefore, we have analyzed the role of the mitotic Drosophila α-kleisin Rad21 during female meiosis. Inactivation of an engineered Rad21 variant by premature, ectopic cleavage during oogenesis results not only in loss of cohesin from meiotic chromatin, but also in precocious disassembly of the synaptonemal complex (SC). We demonstrate that the lateral SC component C(2)M can interact directly with Rad21, potentially explaining why Rad21 is required for SC maintenance. Intriguingly, the experimentally induced premature Rad21 elimination, as well as the expression of a Rad21 variant with destroyed separase consensus cleavage sites, do not interfere with chromosome segregation during meiosis, while successful mitotic divisions are completely prevented. Thus, chromatid cohesion during female meiosis does not depend on Rad21-containing cohesin. PMID:25101996

  17. Enhanced chromatid damage in blood lymphocytes after G2 phase x irradiation, a marker of the ataxia-telangiectasia gene

    International Nuclear Information System (INIS)

    An assay for ataxia-telangiectasia (A-T) heterozygotes, i.e., healthy carriers of the A-T gene(s), requiring only a small sample (3.5 mL) of peripheral blood, is described. Frequencies of chromatid aberrations in phytohemagglutinin-stimulated blood lymphocytes collected by demecolcine from 0.5 hour to 1.5 hours after x irradiation with 58 roentgens were twofold to threefold higher in A-T heterozygotes than in clinically normal controls and twofold to three-fold higher in A-T patients (homozygotes) than in A-T gene carriers. The persistence of chromatid breaks and gaps in lymphocytes following radiation-induced DNA damage during G2 suggests a deficiency or deficiencies in DNA repair that may be the defect at the molecular level that results in the enhanced radiosensitivity and cancer proneness characterizing A-T gene carriers and patients

  18. Securin and not CDK1/cyclin B1 regulates sister chromatid disjunction during meiosis II in mouse eggs.

    Science.gov (United States)

    Nabti, Ibtissem; Reis, Alexandra; Levasseur, Mark; Stemmann, Olaf; Jones, Keith T

    2008-09-15

    Mammalian eggs remain arrested at metaphase of the second meiotic division (metII) for an indeterminate time before fertilization. During this period, which can last several hours, the continued attachment of sister chromatids is thought to be achieved by inhibition of the protease separase. Separase is known to be inhibited by binding either securin or Maturation (M-Phase)-Promoting Factor, a heterodimer of CDK1/cyclin B1. However, the relative contribution of securin and CDK/cyclin B1 to sister chromatid attachment during metII arrest has not been assessed. Although there are conditions in which either CDK1/cyclinB1 activity or securin can prevent sister chromatid disjunction, principally by overexpression of non-degradable cyclin B1 or securin, we find here that separase activity is primarily regulated by securin and not CDK1/cyclin B1. Thus the CDK1 inhibitor roscovitine and an antibody we designed to block the interaction of CDK1/cyclin B1 with separase, both failed to induce sister disjunction. In contrast, securin morpholino knockdown specifically induced loss of sister attachment, that could be restored by securin cRNA rescue. During metII arrest separase appears primarily regulated by securin binding, not CDK1/cyclin B1. PMID:18639540

  19. Sister-chromatid exchange induction in Chinese hamster ovary cells by 8-methoxypsoralen and brief pulses of laser light

    International Nuclear Information System (INIS)

    Brief (-sup(%) M 8-methoxypsoralen. Additional laser pulses caused less than proportional further increments in SCEs, although the total yield of 8-methoxypsoralen adducts in similarly exposed solutions of isolated DNA increased linearly. Higher numbers of laser pulses induced detectable amounts of 8-methoxypsoralen-DNA crosslinks and distorted the DNA flow histogram of CHO cells in a manner consistent with retarded cell cycle traverse. (orig./AJ)

  20. 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.

  1. SCE 优化算法在地下水纳污能力计算中的应用--以北京西郊地区为例%Application of SCE algorithm in calculation of environmental carrying capacity groundwater

    Institute of Scientific and Technical Information of China (English)

    王新娟; 李阳; 孙颖; 李志萍

    2014-01-01

    在已建城近郊区地下水流模型的基础上,通过对模型概化梳理建立水源三厂地区溶质运移模型。采用SCE优化算法与溶质运移模型相耦合,计算一定时期内水源三厂区域可承纳的典型污染物最大允许排放量。经模拟计算,20年内不使水源三厂水质超标情况下,水源三厂保护区内,田村北、西冉村、北坞村东垃圾填埋场的最大NO3-(以N计)和Cl离子年排放量分别为:NO3-(以N计)浓度,北坞村东18.59 t/a、田村北42.29 t/a、西冉村21.45 t/a;Cl-浓度,北坞村东235.66 t/a、田村北441.13 t/a、西冉村290.13 t/a。计算结果为水源地污染预警预报系统的建立及其水源地的保护提供科学依据。%On the basis of groundwater flow model in the suburbs, the paper built the solute transport model of the third plant of water source in the western suburbs by generalizing the model.It calculated the maximum allowa ble emissions of the acceptable typical pollutants within a certain period by using the couple of SCE algorithm with the solute transport model.The result indicated that under the circumstance of water quality being no more than the class III water standard within twenty years, the maximum annual emissions of NO3-and Cl-of landfills in the north of Tiancun, Xirancun, and the east of Beiwucun in the protected area of the third plant of water source are as follows, the density of NO3-, the east of Beiwu-cun is 18.59t/a, the north of Tiancun is 42.29t/a, Xirancun is 21.45t/a;and the density of Cl-, the east of Beiwucun is 235.66t/a, the north of Tiancun is 441.13t/a, Xirancun is 290.13t/a.The result can provide the basis for the establishment of water pollution early-warning system and the protection of water source.

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

    OpenAIRE

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

    2014-01-01

    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 s...

  3. 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.

  4. 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.

  5. 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

  6. Recombinant chromosome 9 possibly derived from breakage and reunion of sister chromatids within a paracentric inversion loop.

    Science.gov (United States)

    Phelan, M C; Stevenson, R E; Anderson, E V

    1993-05-15

    Chromosomally unbalanced offspring resulting from the recombination of parental paracentric inversions are uncommon. We report on a 20-month-old boy with a partial duplication of 9p due to the recombination of a paternal paracentric inversion. The patient's recombinant chromosome was designated rec(9)(p13-->p24::p12-->p24::p12-->qter). The patient's father and paternal aunt have a paracentric inversion of chromosome 9:inv(9)(p13p24). Although several mechanisms have been proposed to explain the chromosome imbalance generated from paracentric inversions, none of the previously described mechanisms can account for the structure of the recombinant chromosome observed in the propositus. We propose an unusual mechanism of formation involving breakage and unequal reunion of sister chromatids within the inversion loop to explain the structure of the patient's recombinant chromosome. PMID:8488876

  7. Test of radiation damage enhancement due to incorporation of BrUdR into DNA using chromatid aberrations

    International Nuclear Information System (INIS)

    Monte Carlo track structure calculations, leading to an estimation of the magnitude of enhancement of radiation damage due to the incorporation of the halogenated pyrimidine, bromodeoxyuridine (BrUdR) a thymine analog, into DNA have been made. The increase in the yield of double strand breaks for various degrees of substitution in one (monofilarly) or both strands (bifilarly) have been calculated. To test these calculations, quantitative selected radiation-induced aberrations have been obtained in Chinese hamster (V79) fibroblast chromosomes having various patterns of BrUdR substitution following irradiation with 250 kV X rays. Free ''breaks'' and achromatic lesions ''gaps'' show no appreciable sensitizations, but breaks involved in chromatid interchanges show significant enhancement though of lower magnitude than theoretical predictions

  8. 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.

  9. Barter exchanges

    DEFF Research Database (Denmark)

    Sudzina, Frantisek

    Although barter is often perceived as something that proceeded money, barter is still used. The focus of the paper is on barter exchanges. Barter exchanges are used both in developing countries as well as in developed countries (including the U.S.). They are used by both organizations and...... individuals. They usually allow to exchange good but some include also services. Some exchanges allow only for bi-directional barter, i.e. when only two parties are involved in the exchange. But probably most of the barter exchanges use barter money; this makes it easier to exchange goods and services as the...

  10. In Vivo Cytogenetic Studies on Aspartame

    Directory of Open Access Journals (Sweden)

    Entissar S. AlSuhaibani

    2010-01-01

    Full Text Available Aspartame (a-Laspartyl-L-phenylalanine 1-methylester is a dipeptide low-calorie artificial sweetener that is widely used as a nonnutritive sweetener in foods and drinks. The safety of aspartame and its metabolic breakdown products (phenylalanine, aspartic acid and methanol was investigated in vivo using chromosomal aberration (CA test and sister chromatid exchange (SCE test in the bone marrow cells of mice. Swiss Albino male mice were exposed to aspartame (3.5, 35, 350 mg/kg body weight. Bone marrow cells isolated from femora were analyzed for chromosome aberrations and sister chromatid exchanges. Treatment with aspartame induced dose dependently chromosome aberrations at all concentrations while it did not induce sister chromatid exchanges. On the other hand, aspartame did not decrease the mitotic index (MI. However, statistical analysis of the results show that aspartame is not significantly genotoxic at low concentration.

  11. Cell-stage-specific enhancement by caffeine of the frequency of chromatid aberrations induced by X-rays in neutral ganglia of Drosophila melanogaster

    International Nuclear Information System (INIS)

    Caffeine (10-2 M) induced a high level of chromatid aberrations in neural ganglia of third-instar larvae of Drosophila melanogaster only when it was added to cells in late G2 and mitotic prophase. No aberrations were observed after treatment in late S-middle G2 or C-mitosis. We observed that, in these stages, caffeine strongly increased X-ray-induced damage (500 R). This potentiation was quantitatively similar. But it involved all types of aberration after treatment in C-mitosis, and essentially isochromatid deletions and chromatid exhanges after treatment in S-G2. Some hypotheses are put forth to explain the possible mechanism of action of caffeine in the potentiation of X-ray-induced damage. (orig.)

  12. Evaluation of genotoxic effects of the herbicide dicamba using in vivo and in vitro test systems

    International Nuclear Information System (INIS)

    The genotoxic effects of the herbicide dicamba have been studied by measuring (1) the unwinding rate of liver DNA from intraperitoneally treated rats (fluorimetric assay); (2) DNA repair as unscheduled DNA synthesis (UDS) induced in cultured human peripheral blood lymphocytes (HPBL); and (3) sister chromatid exchanges (SCE) in HPBL. Results show that dicamba is capable of inducing DNA damage since it significantly increases the unwinding rate of rat liver DNA in vivo and also induces UDS in HPBL in vitro in the presence of exogenous metabolic activation (S-9 mix). Furthermore, dicamba causes a very slight increase in SCE frequency in HPBL in vitro

  13. Cytogenetic studies in patients with uremia before hemodialysis (A preliminary study)

    OpenAIRE

    ÖZTAŞ, Sıtkı; KESKİNLER, Figen; TATAR, A. Gani; TURGUT, Kamuran; BATAT, İrfan

    2001-01-01

    This study has been planned to elucidate the effect of uremia on human genome. For this purpouse, on the mitotic metaphases obtained from the cultured periferic blood samples of 18 patient with uremia to be given hemodialysis treatment for the first time and 15 healthy control subjects. Sister Chromatid Exchange (SCE) rates, numeric and structural chromosomal anomalies have been screened. SCE rate in patients with uremia was 9,48$\\pm$0,29 per metaphase where it was observed as 6,51$\\pm$0,24 p...

  14. RSC Facilitates Rad59-Dependent Homologous Recombination between Sister Chromatids by Promoting Cohesin Loading at DNA Double-Strand Breaks ▿

    OpenAIRE

    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

    2011-01-01

    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 cont...

  15. 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)

    StephanSauer

    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

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

    OpenAIRE

    Parisi, S.; McKay, Michael; Molnar, M; Thompson, Anne; van der Spek, Peter; Drunen-Schoenmaker, E.; Kanaar, Roland; Lehmann, E.; Hoeijmakers, Jan; Kohli, J

    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 confer a number of meiotic phenotypes, including strong reduction of recombination frequencies in the central region of chromosome III, absence of linear element polymerization, reduced pairing of h...

  17. Biomarkers of environmental contaminants in field population of green mussel (Perna viridis) from Karnataka-Kerala coast (South West coast of India).

    OpenAIRE

    Krishnakumar, P.K.; Sasikumar, Geetha; Bhat, G. S.; Asokan, D.P.K.

    2006-01-01

    Biomarker: sister chromatid exchange (SCE); chromosomal aberration; micronucleus (MN); hemic neoplasia (HN), mutagenic activity; comet cells. Exposure/effect represented: exposure to trace metals (Fe, Cu, Ni, Cd, Cr, Zn, Pb, Mn) / DNA damage. Analytical technique: Toxic and essential elements in tissues were determined using AAS; metaphase chromosomes were viewed using light microscope (Olympus BX50) with image analysis facility; hemolymph was stained using the Schiff Feulgen-picromethyl blu...

  18. Cytogenetic Abnormalities of Hematopoietic Tissue in Retired Workers of the Ohkunojima Poison Gas Factory

    OpenAIRE

    Shakil, Fouzia A.; Kuramoto, Atsushi; Yamakido, Michio; Nishimoto, Yukio; Kamada, Nanao

    1993-01-01

    A high incidence of cancer of the respiratory tract has been reported among former workers in a poison gas manufacturing plant which operated on Ohkunojima from 1927 to 1945. This report provides evidence of a high incidence of chromosome abnormality and sister chromatid exchange (SCE) rate among the former workers, as well as cytogenetic changes in two patients among the former workers with chronic myelocytic leukemia (CML). A chromosome study of seven former workers with chronic bronchitis ...

  19. Rapid induction of Alternative Lengthening of Telomeres by depletion of the histone chaperone ASF1

    OpenAIRE

    O'Sullivan, Roderick J; Arnoult, Nausica; Daniel H Lackner; Oganesian, Liana; Haggblom, Candy; Corpet, Armelle; Almouzni, Genevieve; Karlseder, Jan

    2014-01-01

    The mechanism of activation of the Alternative Lengthening of Telomeres (ALT) pathway of mammalian chromosome end maintenance has remained an unresolved issue. We have discovered that co-depletion of the histone chaperones ASF1a and ASF1b in human cells induced all hallmarks of ALT in both primary and cancer cells. These included the formation of ALT associated PML bodies (APBs), extra-chromosomal telomeric DNA species an elevated frequency of telomeric sister chromatid exchanges (t-SCE) even...

  20. In Vivo Cytogenetic Studies on Aspartame

    OpenAIRE

    Entissar S. AlSuhaibani

    2010-01-01

    Aspartame (a-Laspartyl-L-phenylalanine 1-methylester) is a dipeptide low-calorie artificial sweetener that is widely used as a nonnutritive sweetener in foods and drinks. The safety of aspartame and its metabolic breakdown products (phenylalanine, aspartic acid and methanol) was investigated in vivo using chromosomal aberration (CA) test and sister chromatid exchange (SCE) test in the bone marrow cells of mice. Swiss Albino male mice were exposed to aspartame (3.5, 35, 350 mg/kg body weight)....

  1. Action of the poison of Apis mellifera bee and gamma radiation on bone marrow cells of Wistar rats and on lymphocytes of human peripheral blood

    International Nuclear Information System (INIS)

    ''In vivo'' and ''in vitro'' experiments are performed to determine the radioprotective action of the poison of Apis mellifera bees. The frequency of chromosome aberrations, induced by gamma radiation, is studied in two assays: ''in vivo'' in bone marrow cells from Wistar rats and ''in vitro'' in human peripheral blood lymphocyte cultures. The sister chromatid exchanges (SCE) are studied in the ''in vitro'' assays. (M.A.C.)

  2. 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

    2014-01-01

    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. PMID:25257309

  3. 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.

  4. The use of the differential staining of sister chromatids in the study of the cytogenetic radiation effects in human lymphocytes

    International Nuclear Information System (INIS)

    Differential staining of sister chromatides is performed, cells of the 1-st and the following mitoses are identified, chromosome aberrations are accounted, and statistic processing of data is performed. Venous blood of healthy donors is used as material for analysis. It is irradiated in flasks by 60Co gamma-quanta in the doses of 1, 1.5, 2, 3, 4, 5, 6, and 8 Gy. Lymphocytes of the peripheral blood are cultivated at 37 deg C in the medium containing antibiotics, phytohemaggluninin and 5-bromiurnedeoxyidine (BDU). The observed distributions of dicentrics in cells are compared with theoretic Poisson distribution. The dependence of frequency of dicentrics on radiation dose is studied by the method of regressive analysis. The importance of applying this technique in radiation cytogenetic investigations to increase the accuracy of chromosome aberration account in stimulated phytohemagglutinin cultures of lymphocytes of human peripheral blood and to study regularities of their elimination after cells pass the 1-st and the second mitoses, is shown

  5. 浸没燃烧蒸发(SCE)技术处理含氰含氨废水的研究%A Study of CN- and NH3 Contained Waste Water Treatment with SCE Method

    Institute of Scientific and Technical Information of China (English)

    吴丹; 付艳娥; 陈光强

    2012-01-01

    介绍采用SCE工艺,利用副产氢气做燃料,通过燃烧氧化的方法降低废水中氰根、氨氮、甲酸钠等有机物杂质的含量。经SCE方法处理后的废水有机物浓度降低,大大节约了废水处理中化学药剂的使用量。经试验表明,该工艺对废水中有机物的去除效果明显,处理结果稳定,不会引入杂质,出水经化学氧化后可以达到排放要求。%This thesis introduced a combustion and oxidation procedure to reduce content of CN, ammonia and NaCOOH and other organic impurity in waste water with using SCE method and by -product hydrogen gas as fuel. After SCE treatment, organic compounds content in waste water is reduced obviously. It can save using amount of chemicals in waste water treatment. Based on trials results, the SCE has great effect for removing organic compounds with stable treatment results and especially not introducing impurity in waste water. Treated waste water can reach discharge standard after chemical oxidation.

  6. 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

  7. β -carotene effect the induction of the sister chromatid exchanges (ICH) by gamma radiation in mouse radiosensibilized osseous marrow cells In vivo

    International Nuclear Information System (INIS)

    The effect of β- carotene over the ICH radioinduction in radiosensibilized with BrdU osseous marrow cells of mouse was determined In vivo. The treatment with 50 μg β 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 β- carotene does not have radioprotective activity, under conditions which was developed this experiment. (Author)

  8. Detection of genotoxicity in the marine environment: A preliminary feasibility study using primary mussel tissue culture

    Energy Technology Data Exchange (ETDEWEB)

    Cornet, Michel [UMR 5805 EPOC ' Environnements et Paleoenvironnements Oceaniques' , Universite Bordeaux 1, CNRS, Avenue des Facultes, 33405 Talence Cedex (France)]. E-mail: m.cornet@epoc.u-bordeaux1.fr

    2007-08-15

    The purpose of this study was to evaluate the feasibility and potential usefulness of primary cultures of somatic tissues from adult mussel by means of sister chromatid exchange induction (SCE). This research is an initial pilot study carried out with mussel mantle tissue using seawater artificially contaminated with cadmium and polluted seawater from the port of Arcachon. With regard to cadmium concentration, mean SCE numbers showed a progressive increase from 1.07 {+-} 0.18 per diploid cell in controls (i.e. cultures without contaminant) to 2.91 {+-} 0.42 per diploid cell for the highest concentration, 10{sup -4} M. With regard to the medium prepared with seawater from the port of Arcachon, the mean SCE number reached a value of 5.85 {+-} 0.85 per diploid cell. The analysis of SCEs induced by cadmium showed DNA responses even at the lowest concentration (i.e. 10{sup -7} M). The study demonstrates the feasibility of the sister chromatid exchange (SCE) approach based upon primary mussel tissue culture, for the genotoxicity testing of contaminated seawater. Highlights from this procedure are (1) the presence of an active cell proliferation, (2) the use whole-water samples, (3) the possibility of culturing without serum, (4) the absence of cell dissociation before culturing and (5) a cellular proliferation which can be obtained in cultures carried out in a medium containing seawater whose salinity is comprise between 28 and 35 per mille.

  9. Detection of genotoxicity in the marine environment: A preliminary feasibility study using primary mussel tissue culture

    International Nuclear Information System (INIS)

    The purpose of this study was to evaluate the feasibility and potential usefulness of primary cultures of somatic tissues from adult mussel by means of sister chromatid exchange induction (SCE). This research is an initial pilot study carried out with mussel mantle tissue using seawater artificially contaminated with cadmium and polluted seawater from the port of Arcachon. With regard to cadmium concentration, mean SCE numbers showed a progressive increase from 1.07 ± 0.18 per diploid cell in controls (i.e. cultures without contaminant) to 2.91 ± 0.42 per diploid cell for the highest concentration, 10-4 M. With regard to the medium prepared with seawater from the port of Arcachon, the mean SCE number reached a value of 5.85 ± 0.85 per diploid cell. The analysis of SCEs induced by cadmium showed DNA responses even at the lowest concentration (i.e. 10-7 M). The study demonstrates the feasibility of the sister chromatid exchange (SCE) approach based upon primary mussel tissue culture, for the genotoxicity testing of contaminated seawater. Highlights from this procedure are (1) the presence of an active cell proliferation, (2) the use whole-water samples, (3) the possibility of culturing without serum, (4) the absence of cell dissociation before culturing and (5) a cellular proliferation which can be obtained in cultures carried out in a medium containing seawater whose salinity is comprise between 28 and 35 per mille

  10. Chromosome fragility in Freemartin cattle

    Directory of Open Access Journals (Sweden)

    V. Barbieri

    2010-04-01

    Full Text Available The aim of the present study was to verify chromosome fragility in freemartin cattle using chromosome aberration (CA and sister chromatid exchange (SCE tests. A total of eighteen co-twins were investigated. Fourteen animals were identified as cytogenetically chimeric (2n=60, XX/XY while 4 were classified as normal. Freemartin cattle showed a higher percentage of aneuploid cells (18.64% and highly significant statistical differences (P < 0.001 in mean values of gaps (4.53 ± 2.05, chromatid breaks (0.26 ± 0.51, and significant statistical differences (P < 0.005 in mean values of chromosome breaks (0.12 ± 0.43 when compared to 10 control animals from single births (aneuploid cells, 11.20%; gaps, 2.01 ± 1.42; chromatid breaks, 0.05 ± 0.22; chromosome breaks, 0.02 ± 0.14.

  11. Heat exchanger

    International Nuclear Information System (INIS)

    A heat exchanger having primary and secondary conduits in heat-exchanging relationship is described comprising: at least one serpentine tube having parallel sections connected by reverse bends, the serpentine tube constituting one of the conduits; a group of open-ended tubes disposed adjacent to the parallel sections, the open-ended tubes constituting the other of the conduits, and forming a continuous mass of contacting tubes extending between and surrounding the serpentine tube sections; and means securing the mass of tubes together to form a predetermined cross-section of the entirety of the mass of open-ended tubes and tube sections

  12. Assessment in vitro of cytogenetic and genotoxic effects of propolis on human lymphocytes.

    Science.gov (United States)

    Montoro, A; Soriano, J M; Barquinero, J F; Almonacid, M; Montoro, A; Verdú, G; Sahuquillo, V; Villaescusa, J I; Sebastià, N

    2012-02-01

    We evaluated the genetic damage by ethanolic extract of propolis (EEP) induced to human lymphocytes which were exposed to increasing concentrations (0-2000μgml(-1)). The results indicated that EEP reduced significantly the mitotic index (MI) and proliferation index (PI) when high concentrations of EEP were used. Sister chromatid exchange (SCE) rates indicated that EEP could have genotoxic effects at high concentrations. Exposure of the cells to the amount of ethanol used as solvent did not alter either the MI and cell proliferation kinetics (CPK), or the rate of SCE. The results showed: (a) statistical increase in the percentage the cells with CAs and in the frequency of SCE at the highest concentrations, (b) a decrease in MI and in the CPK values was observed, (c) no effect was noticed in negative controls. In conclusion, it can be assumed that high concentrations of EEP have a cyto and genotoxic effect, in vitro, for human peripheral lymphocytes. PMID:22041523

  13. Children's exposure to environmental pollutants and biomarkers of genetic damage. II. Results of a comprehensive literature search and meta-analysis

    DEFF Research Database (Denmark)

    Neri, Monica; Ugolini, Donatella; Bonassi, Stefano;

    2005-01-01

    aberrations (CA) and micronuclei (MN) but not sister chromatid exchanges (SCE) were found consistently increased in children exposed to environmental pollutants. Meta-analysis of the studies reporting SCE in cord blood showed similar levels of SCE in exposed and in non-exposed newborns. Exposure to airborne......-DNA adducts were found in fetal than in maternal tissue, suggesting a specific susceptibility of the fetus to this class of ubiquitous environmental pollutants. According to these findings, future research and biomonitoring programs on children would greatly benefit from the inclusion of selected biomarkers...... pollutants, soil and drinking water contaminants, mostly increased CA and, to a lesser extent, MN levels in children. The effect of exposure to airborne urban pollutants was consistently reported by field studies measuring DNA, albumin and hemoglobin adducts. Prenatal (in utero) and postnatal exposure...

  14. 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.

  15. Heat exchanger

    International Nuclear Information System (INIS)

    A heat exchanger of the straight tube type is described in which different rates of thermal expansion between the straight tubes and the supply pipes furnishing fluid to those tubes do not result in tube failures. The supply pipes each contain a section which is of helical configuration

  16. Heat Exchanger

    International Nuclear Information System (INIS)

    A liquid metal heated tube and shell heat exchanger where straight tubes extend between upper and lower tube sheets. In order to prevent thermal stress problems, one tube sheet is fixed to the shell, and the other tube sheet is sealed to the shell by means of a flexible bellows. In the event of a catastrophic bellows failure, a housing that utilizes a packing gland sliding seal is used to enclose and back-up the bellows. Also, a key and slot arrangement is provided for preventing relative rotation between the shell and tube sheet which could damage the bellows and cause failure thereof. This exchanger is seen to be of use in sodium cooled reactors between the liquid sodium circuit on the steam generator

  17. Studies of DNA and chromosome damage in skin fibroblasts and blood lymphocytes from psoriasis patients treated with 8-methoxypsoralen and UVA irradiation

    International Nuclear Information System (INIS)

    Exposure of human lymphocytes and skin fibroblasts in vitro to a single, clinically used dose of PUVA, i.e., 0.1 micrograms/ml of 8-methoxypsoralen (8-MOP) plus 0.9-4 J/cm2 of longwave ultraviolet radiation (UVA), lead to the formation of DNA damage as determined by alkaline elution, and to chromosome aberrations and sister chromatid exchanges (SCE). When lymphocyte-enriched plasma was obtained from psoriasis patients 2 h after oral intake of 8-MOP and then UVA irradiated (1.8-3.6 J/cm2) in vitro, an increased frequency of chromosome aberrations and SCE was observed. Normal levels of chromosome aberrations and SCE were found in lymphocytes of psoriasis patients after 3-30 weeks of PUVA treatment in vivo. A small but statistically significant increase in the SCE frequency was observed in the lymphocytes of psoriasis patients treated for 1-6 years with PUVA (mean 18.0 SCE/cell) as compared with before PUVA (mean 15.8, p less than 0.05). Skin fibroblasts of psoriasis patients analyzed 5 years after the start of PUVA treatment showed a normal number of SCE but a high fraction of filter-retained DNA in the alkaline elution assay, suggesting the presence of cross-linked DNA

  18. 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

  19. Studies on mutagenic activity of 60Co γ-ray irradiated rape pollen

    International Nuclear Information System (INIS)

    In the present study on disinfection, the rape pollen was irradiated with 2.5 kGy 60Co γ-ray. Micronuclei, sister chromatid exchanges (SCE) of bone marrow cells and chromosomal aberrations of meiotic cells in mice were used as an indicater of chromosomal damage to study the mutagenicity of irradiated rape pollen. The results are as follows: (1) The frequency of micronuclei in polychromatic erythrocytes is 2.00 per mille; nucleated cells is 0.8 per mille in control group. In the numbers of polychromatic erythrocytes and nucleated cells with micronuclei, there is no obviously difference in irradiated and unirradiated groups. (2) SCE incidence of control group is 2.01 ± 0.12/cell. No significant difference in the frequency of SCE exists between non-irradiated rape pollen and the control groups. But the frequency of SCE in irradiated rape pollen group (3000 mg/kg/day x 7) is 2.36 ± 0.12/cell; high dose group (6000 mg/kg/day x 7) is 2.96 ± 0.14/cell. In comparison with control group, there is a significant difference. (3) The chromatid breaks, fragments, and univalents in primary spermatocytes have been obseved. The frequencies of chromosomal aberration showed no obviously difference among irradiated and non-irradiated rape pollen groups

  20. Exchange-correlation functionals via local interpolation along the adiabatic connection

    CERN Document Server

    Vuckovic, Stefan; Savin, Andreas; Teale, Andrew M; Gori-Giorgi, Paola

    2016-01-01

    The construction of density-functional approximations is explored by modeling the adiabatic connection em locally, using energy densities defined in terms of the electrostatic potential of the exchange-correlation hole. These local models are more amenable to the construction of size-consistent approximations than their global counterparts. In this work we use accurate input local ingredients to assess the accuracy of range of local interpolation models against accurate exchange-correlation energy densities. The importance of the strictly-correlated electrons (SCE) functional describing the strong coupling limit is emphasized, enabling the corresponding interpolated functionals to treat strong correlation effects. In addition to exploring the performance of such models numerically for the helium and beryllium isoelectronic series and the dissociation of the hydrogen molecule, an approximate analytic model is presented for the initial slope of the local adiabatic connection. Comparisons are made with approache...

  1. Düzenli Saç Boyası Kullanıcısı olan Sağlıklı Türk Kadınlarında SCE Sıklık Analizi

    OpenAIRE

    Ulucan, Hakan; Dündaröz, Ruşen; Denli, Metin; Gök, Faysal; Akın, Mehtap; Baltacı, Volkan

    2009-01-01

    SüleymanDemirel Üniversitesi TIP FAKÜLTESİ DERGİSİ: 2001 ; 8(2) Düzenli Saç Boyası Kullanıcısı olan Sağlıklı Türk Kadınlarında SCE Sıklık Analizi Hakan ULUCAN, Ruşen DÜNDARÖZ, Metin DENLİ, Faysal GÖK, Mehtap AKIN, Volkan BALTACI Özet Saç boyası sık kullanılan bir kozmetik ajan olmasına rağmen, DNA üzerine tok-sik etkisi yeterince açık değildir. Kadınlarca daha sık kullanıldığından, özellikle hamile- lik ve süt verme durumunda böyle bir toksik etki daha...

  2. 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.

  3. Natural ion exchangers

    International Nuclear Information System (INIS)

    Present article is devoted to natural ion exchangers. Ion exchange properties of minerals are described. Structural types of porous matrixes of natural ion exchangers are considered. Types of sorption centres in minerals are considered as well.

  4. The lethal response to Cdk1 inhibition depends on sister chromatid alignment errors generated by KIF4 and isoform 1 of PRC1.

    Science.gov (United States)

    Voets, Erik; Marsman, Judith; Demmers, Jeroen; Beijersbergen, Roderick; Wolthuis, Rob

    2015-01-01

    Cyclin-dependent kinase 1 (Cdk1) is absolutely essential for cell division. Complete ablation of Cdk1 precludes the entry of G2 phase cells into mitosis, and is early embryonic lethal in mice. Dampening Cdk1 activation, by reducing gene expression or upon treatment with cell-permeable Cdk1 inhibitors, is also detrimental for proliferating cells, but has been associated with defects in mitotic progression, and the formation of aneuploid daughter cells. Here, we used a large-scale RNAi screen to identify the human genes that critically determine the cellular toxicity of Cdk1 inhibition. We show that Cdk1 inhibition leads to fatal sister chromatid alignment errors and mitotic arrest in the spindle checkpoint. These problems start early in mitosis and are alleviated by depletion of isoform 1 of PRC1 (PRC1-1), by gene ablation of its binding partner KIF4, or by abrogation of KIF4 motor activity. Our results show that, normally, Cdk1 activity must rise above the level required for mitotic entry. This prevents KIF4-dependent PRC1-1 translocation to astral microtubule tips and safeguards proper chromosome congression. We conclude that cell death in response to Cdk1 inhibitors directly relates to chromosome alignment defects generated by insufficient repression of PRC1-1 and KIF4 during prometaphase. PMID:26423135

  5. 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...

  6. Cytogenetic monitoring of coal workers and patients with coal workers' pneumoconiosis in Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Ulker, O.C.; Ustundag, A.; Duydu, Y.; Yucesoy, B.; Karakaya, A. [Ankara University, Ankara (Turkey)

    2008-04-15

    Occupational exposure to coal dust causes coal workers' pneumoconiosis (CWP), which is a chronic inflammatory and fibrotic lung disease. Recently, chronic inflammation has been accepted as a crucial factor in the pathogenesis of neoplasia. The chronic inflammation provides dynamic setting for oxidative stress and formation of free radicals. Interaction of reactive oxygen species (ROS) with DNA augments the likelihood of DNA structural and transcriptional errors. The purpose of this study was to investigate the genotoxic risk in pneumoconiotic patients and in those with occupational exposure to coal dust. Therefore, sister chromatid exchange (SCE) and micronucleus (MN) tests were performed in Turkish CWP patients, coal workers, and an unexposed control group. Both SCE and MN frequencies in CWP patients were found significantly higher than in coal worker and unexposed groups. There were no differences between SCE and MN frequencies of coal worker and unexposed groups. On the other hand, no correlation between SCE frequency, duration of exposure, and age was observed in all three groups. There was also no effect of smoking on the frequencies of SCE and MN in the groups. Based on these results, it might be suggested that development of CWP leads to a significant induction of cytogenetic damage in peripheral lymphocytes of CWP patients. This is the first report on CWP patients with elevated cytogenetic endpoints. Further, a larger follow-up study is warranted.

  7. Genetic toxicity studies of organic chemicals found as contaminants in spacecraft cabin atmospheres

    Science.gov (United States)

    Torres, Joseph, Jr.

    1987-01-01

    Astronauts can be exposed during spaceflight to organic chemical contaminants in the spacecraft cabin atmosphere. Toxic exposures may cause lesions in the cellular DNA which are subsequently expressed as sister-chromatid exchanges (SCE). Analysis of SCE is a sensitive short term assay techinque to detect and quantitate exposures to DNA damaging (mutagenic) substances. The increase in SCE incidence over baseline (control) levels is generally proportional to the concentration of the mutagen and to the duration of exposure. The BHK-21 baby hamster kidney cell line was the in vitro test system used. Test organics were added to the culture media for 18 hrs, in concentrations ranging from one to 20 ppm. Acetaldehyde and carbon disulfide were chosen for this study since they have occurred as atmospheric contaminants in many of the STS flights, and have been reported to have toxic and mutagenic effects in various test systems. Glutaraldehyde was chosen because few data are available on the mutagenicity of this common fixative, which is carried on STS flights for use in biological experiments. Acetaldehyde was a very strong inducer of SCE at concentrations of 2 ppm and above. Glutaraldehyde and carbon disulfide failed to induce SCE.

  8. The Gravitational Heat Exchanger

    OpenAIRE

    De Aquino, Fran

    2015-01-01

    The heat exchangers are present in many sectors of the economy. They are widely used in Refrigerators, Air-conditioners, Engines, Refineries, etc. Here we show a heat exchanger that works based on the gravity control. This type of heat exchanger can be much more economic than the conventional heat exchangers.

  9. The possibility of exchange

    OpenAIRE

    AJ Julius

    2013-01-01

    I first characterize a moral mistake in coercion. The principle of independence with which I criticize coercion seems also to condemn exchange. I propose an account of exchange from which it follows that exchange upholds independence after all. In support of that account I argue that, of the accounts of exchange that occur to me, only this one has the consequence that, on general assumptions, a person can take part in exchange while acting, intending, and believing with sufficient reason. I a...

  10. Cytogenetic effects of aqueous extracts of the medicinal plant paico (chenopodium multifidum L.).

    Science.gov (United States)

    Gadano, A; Gurni, A; Nigro López, M; López, P; Gratti, A; van Baren, C; Ferraro, G; Carballo, M

    2000-01-01

    The cytogenetic effects of aqueous extracts of Chenopodium multifidum L. (Paico) were determined by addition of the extracts and fractions to human lymphocyte cultures. Toxicity was evaluated by analysis of chromosomal aberrations (CA), sister chromatid exchange (SCE), mitotic (MI) and replication (RI) indexes. The results showed an increase in CA frequency in cultures exposed to infusion decoction, no modification in the CPK values either in the decoction or in the infusion, and a decrease in the MI of lymphocyte cultures exposed to the decoction. These results suggested genotoxic effects of "Paico" aqueous extracts. PMID:21214432

  11. 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.

  12. Cytogenetic study of Ascaris trypsin inhibitor in cultured human lymphocytes with metabolic activation

    Indian Academy of Sciences (India)

    Joanna Blaszkowska; Wanda Bratkowska; Dobroslawa Lopaczynska; Tomasz Ferenc

    2009-04-01

    The trypsin inhibitor (ATI) isolated from gastrointestinal nematode Ascaris suum was tested in vitro for induction of chromosome aberrations and sister chromatid exchanges (SCE). Genotoxicity assessment of purified ATI was carried out on metaphase plates received from peripheral blood lymphocyte macroculture (48 h test of structural chromosome aberrations and 72 h test of SCE) with exogenous metabolic activation. ATI was tested in dose of 25, 50 and 100 μg per ml of culture. Kinetics of cell divisions were determined by the replication index (RI). The mitotic index (MI) was expressed as a number of metaphases per 1000 nuclei analysed. Analysis of chromosome aberrations showed that higher doses of ATI (50 and 100 /ml) significantly increased the frequency of chromosome aberrations (mainly of chromatid gaps and breaks) compared to the negative control. All concentrations of ATI caused a statistically significant reduction in the MI and RI. In comparison with the negative control, a significant increase in the SCE frequency was observed in all applied doses of ATI. Thus, in the presence of S9 activation, the Ascaris trypsin inhibitor showed potential clastogenic activity and inhibition of the dynamics of lymphocyte divisions.

  13. Genotoxic effects of copper sulfate in rabbits

    Directory of Open Access Journals (Sweden)

    Georgieva S.

    2013-01-01

    Full Text Available This study was carried out to determine the genotoxic effects of oral application of CuSO4 in rabbits by the chromosome aberration (CA and sister chromatid exchange (SCE tests. Ten male New Zealand rabbits (5 months old, weighing 3.5-4.0 kg were allocated into two groups. The first group received CuSO4 (5H2O in drinking water for 6 consecutive days. The second group was used as a control. On the 7th day, blood samples were taken from the ear marginal vein and the SCE and CA tests in peripheral lymphocytes were used as genotoxicity and mutagenicity endpoints, respectively. Results showed a significant increase in the frequencies of the aberrant cells (7.4±0.24, P<0.001 and CA (chromatid fragments 3.2±0.37, chromosome fragments 4.2±0.37, P<0.001, and total aberrations (7.4±0.24, P<0.001 after the treatment with CuSO4 when compared with the control group. The level of SCE per cell in the CuSO4-treated rabbits (9.66±0.062 was significantly higher than in rabbits from the control group. These findings show that copper exhibits a genotoxic and mutagenic potential in rabbits.

  14. UtilityTelecom_EXCHANGE

    Data.gov (United States)

    Vermont Center for Geographic Information — The UtilityTelecom_EXCHANGE represents Vermont Telephone Exchange boundaries as defined by the VT Public Service Board. The original data was created by UVM in...

  15. 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.

  16. In vivo mutagenicity studies in rats mice and Chinese hamsters fed irradiated foodstuffs - chicken, fish, dates, pulses, mangoes and cocoa beans

    International Nuclear Information System (INIS)

    Three in vivo genetic toxicity tests were performed in rats, mice and Chinese hamsters to detect possible mutagenic effects of irradiated chicken, dried dates, fish, cocoa beans, pulses and mangoes. The tests employed were the micronucleus test and sister-chromatid exchange (SCE) test for irradiated and unirradiated samples of all foodstuffs listed, and the spermatogonia test, (including SCE technique) in mice for irradiated and unirradiated chicken, fish and dates only. In the case of cocoa beans, the mutagenicity tests were performed on an additional test group fed beans fumigated with ethylene oxide. The different mammalian species used for the various experiments are given below. None of the tests provided any evidence of mutagenicity induced by irradiation in any of the foodstuffs studied. Moreover, these tests are currently considered to be the most sensitive in vivo mutagenicity tests in mammals. (orig.)

  17. In vitro genotoxic evaluation of the medicinal plant Chenopodium ambrosioides L.

    Science.gov (United States)

    Gadano, A; Gurni, A; López, P; Ferraro, G; Carballo, M

    2002-06-01

    Chenopodium ambrosioides (Chenopodiaceae) is an anthelmintic herb used in Latin-America's folk medicine. The aim of this work is to evaluate genetic damage induced by decoction and infusion of this plant which were assayed in different concentrations (1, 10, 100, 1000 microg/ml), by addition of the extract to human lymphocyte cell cultures. The endpoints evaluated were chromosomal aberrations (CA), sister chromatid exchanges (SCE), cell proliferation kinetics (CPK) and mitotic indexes (MI). The repeated measure analysis of variance was used for statistic evaluation of the results. The results showed (a) a statistical increase in the percentage of cells with CA and in the frequency of SCE when cultures were exposed to both preparations of Paico, (b) a decrease in MI of both preparations assayed, although no modification in the CPK values either in the infusion or in the decoction was observed. These results suggest a possible genotoxic effect of both preparations, probably due to different active principles. PMID:12020922

  18. Heat exchanger design

    OpenAIRE

    Loukota, Martin

    2014-01-01

    This bachelor thesis solves design of a heat exchanger for hot water boiler with gasification chamber for preheating the combustion air with the heat of the combustion products. Calculation values were experimentally measured. Thesis contains brief description of the shell and tube heat exchanger, stoichiometric combustion calculation, geometrical dimensions design of the heat exchanger, pressure loss and thermal performance calculation. It also includes drawings of the designed exchanger.

  19. Charge exchange system

    Science.gov (United States)

    Anderson, Oscar A.

    1978-01-01

    An improved charge exchange system for substantially reducing pumping requirements of excess gas in a controlled thermonuclear reactor high energy neutral beam injector. The charge exchange system utilizes a jet-type blanket which acts simultaneously as the charge exchange medium and as a shield for reflecting excess gas.

  20. 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

  1. Economic performance of the SCE Stirling dish

    International Nuclear Information System (INIS)

    In 1982 McDonnell Douglas Aerospace Space System (MDA-SS) and United Stirling AB of Sweden formed a joint venture to develop and market a solar Stirling dish unit. Eight modules were built and extensively tested from 1984 to 1988. Power production and daily energy-conversion efficiency as determined by field testing have been characterized and modeled in a computer program. Included in this simulation are models of mirror soiling rate, wind spillage loss, mirror washing and other maintenance outage time, operation and maintenance (O and M) costs and other cost models. An economic model of a hybrid (combustion) receiver has been included in the simulation for illustrating the value of using solar energy when available and other fuels such as methane, natural gas, hydrogen, etc. when solar energy is not available or adequate. This paper describes the simulation and presents comparisons of the simulation to test data. The simulation also estimates both the O and M expenses and levelized energy costs for different production volumes

  2. Economic performance of the SCE Stirling dish

    International Nuclear Information System (INIS)

    In 1982 McDonnell Douglas Aerospace (MDA) and United Stirling AB (USAB) of Sweden formed a joint venture to develop and market a solar Stirling dish system. Eight modules were built and extensively tested from 1984 to 1988. Power production and daily energy-conversion efficiency as determined by field testing were characterized and modeled into a computer program. Included in this simulation are models of mirror soiling rate, wind spillage loss, mirror washing, and other maintenance outage time, operation and maintenance (O and M) costs, and equipment purchase cost. An economic model of a hybrid (combustion) receiver has been included in the simulation for illustrating the value of using solar energy when available and other fuels such as methane, natural gas, hydrogen, etc. when solar energy is not available or adequate. This paper describes the simulation and presents comparisons of the simulation to test data. The simulation also estimates both the O and M expenses and levelized energy costs for different production volumes

  3. Evaluation of the genotoxic effects of a folk medicine, Petiveria alliacea (Anamu).

    Science.gov (United States)

    Hoyos, L S; Au, W W; Heo, M Y; Morris, D L; Legator, M S

    1992-07-01

    Crude extract from a plant known as Petiveria alliacea (Anamu) is used extensively as folk medicine in developing countries like Colombia, South America. Although the plant is known to contain toxic ingredients potential adverse health effects from its use have not been adequately evaluated. We investigated its genotoxic activities by conducting a sister chromatid exchange (SCE) assay using cells in vitro and in vivo. Lymphocytes from humans were treated at 24 h after initiation of culture for 6 h with alcohol extract from the folk medicine. Concentrations of 0, 10, 100, 250, 275, 500, 750, and 1000 micrograms/ml of the extract were used. Significant dose-dependent increase of SCE (3.7-7.4 SCE per cell) were observed (analysis of variances, p less than 0.01). Delay in cell proliferation but not inhibition of mitosis was also observed. In another experiment, mice were exposed once orally to 1x, 200x, 300x and 400x the human daily consumption dose of Anamu. The induction of sister chromatid exchanges in bone marrow cells were investigated. We observed a significant dose dependent increase of SCE compared with the saline control (2.15-4.53; p less than 0.01) and compared with the solvent control (3.04-4.53; p less than 0.01). Our data suggest, therefore, that the folk medicine contains mutagenic and potentially carcinogenic agents although the medicine is not a potent mutagen. Individuals who consume large amounts of this drug may be at risk for development of health problems. Further studies with cells from exposed individuals and from experimental animals should be conducted to provide a better evaluation of health risk from the use of this drug. PMID:1377342

  4. 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...

  5. Exchange Rate Regime Choice

    OpenAIRE

    2006-01-01

    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 synchronised effects of structural and external factors, remain permanently questioned throughout a complex process of exchange rate regime decision making. ...

  6. Exchange and Development

    OpenAIRE

    Peter A. Cornelisse; Erik Thorbecke

    2014-01-01

    The purpose of this paper is to present a framework explaining why different types of transactions occur in different settings- particularly in developing countries. The approach we propose is based on a new concept which we call “exchange-configuration”. The latter consists of three building blocks or elements: the item exchanged; the actors engaged in decisions related to the item being exchanged; and, the environment – physical, social, technological, and legal – within which the actors op...

  7. 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.

  8. The Amsterdam power exchange

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, M. [Price Waterhouse Coopers, Berlin (Germany)

    1998-09-01

    Continental Europe`s first electricity exchange is taking shape. While the Amsterdam Power Exchange (APX) still faces challenges, most of the critical issues have been resolved and concrete steps towards its implementation are being made. The emergence of a spot market for electricity represents a quantum leap in the European liberalization process. The exchange is a tool that will fundamentally alter the way utilities operate with implications beyond the boundaries of the Netherlands. (UK)

  9. Exchange Rate Economics

    OpenAIRE

    John Williamson

    2008-01-01

    The paper summarizes the current theory of how a floating exchange rate is determined, dividing the subject into what determines the steady state and what determines the transition to steady state. The inadequacies of this model are examined, and an alternative “behavioral” model, which recognizes that the foreign exchange market is populated by both fundamentalists and chartists is presented. It is argued that the main importance of understanding the foreign exchange market for development s...

  10. 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...

  11. 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...

  12. 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.

  13. Summary update of the Brookhaven tritium toxicity program with emphasis on recent cytogenetic and lifetime-shortening studies

    International Nuclear Information System (INIS)

    A number of years ago a multiparameter program to evaluate the toxicity of tritiated water (HTO) was undertaken in the Medical Department at Brookhaven National Laboratory. The results of most of these studies have been published and will receive brief attention. Emphasis will be placed on the unpublished studies involving the induction of sister chromatid exchanges (SCE's) in bone marrow of mice, new biochemical information, and preliminary results on lifetime-shortening and carcinogenesis. In brief, male Hale-Stoner Brookhaven (HSB) mice maintained on HTO concentrations ranging from 3.0 to 30.0 μCi/ml exhibited essentially the same number of SCE's per cell throughout their lifetime. Control mice showed a decrease in number of SCE's with age. The lack of a dose-response effect and the constant level of SCE's in HTO mice as compared to controls will be discussed. In the carcinogenesis study C57BL/6J male mice received various x-ray or HTO regimens. Mortality data from these and other studies in which CBA/Ca/BNL mice received single x-ray exposures or equivalent integrated dose exposures by single HTO injections will be discussed. 25 refs., 4 figs

  14. Evaluation of the genotoxic effects of chronic low-dose ionizing radiation exposure on nuclear medicine workers

    International Nuclear Information System (INIS)

    Introduction: Nuclear medicine workers are occupationally exposed to chronic ionizing radiation. It is known that ionizing radiation may have damaging effects on chromosomes. In the present study, we investigated the genotoxic effects of ionizing radiation on nuclear medicine workers. We used two different indicators of genotoxicity methods: sister chromatid exchange (SCE) and micronucleus (MN). Methods: The present research was carried out using 21 nuclear medicine workers (11 females and 10 males) during two periods: during normal working conditions and after a 1-month vacation. The radiation dose varied from 1.20 to 48.56 mSv, which accumulated during the occupational exposure time between two vacations. Peripheral blood samples were taken from each subject for two distinct lymphocyte cultures (SCE and MN) in each period. Results: In nearly all subjects, SCE values increased significantly during radiation exposure compared to the postvacation period (P<.05). Similarly, MN frequencies in most of the subjects increased significantly during radiation exposure compared to the postvacation period (P<.05). Conclusions: This study revealed that both SCE and MN frequencies in most of the subjects were significantly higher during exposure to ionizing radiation than after a 1-month vacation period. However, this genotoxic effect was reversible in most of the subjects.

  15. Differences in genotoxic activity of alpha-Ni3S2 on human lymphocytes from nickel-hypersensitized and nickel-unsensitized donors.

    Science.gov (United States)

    Arrouijal, F Z; Marzin, D; Hildebrand, H F; Pestel, J; Haguenoer, J M

    1992-05-01

    The genotoxic activity of alpha-Ni3S2 was assessed on human lymphocytes from nickel-hypersensitized (SSL) and nickel-unsensitized (USL) subjects. Three genotoxicity tests were performed: the sister chromatid exchange (SCE) test, the metaphase analysis test and the micronucleus test. (i) The SCE test (3-100 micrograms/ml) showed a weak but statistically significant increase in the number of SCE in both lymphocyte types with respect to controls, USL presenting a slightly higher SCE incidence but only at one concentration. (ii) The metaphase analysis test demonstrated a high dose-dependent clastogenic activity of alpha-Ni3S2 in both lymphocyte types. The frequency of chromosomal anomalies was significantly higher in USL than in SSL for all concentrations applied. (iii) The micronucleus test confirmed the dose-dependent clastogenic activity of alpha-Ni3S2 and the differences already observed between USL and SSL, i.e. the number of cells with micronuclei was statistically higher in USL. Finally, the incorporation study with alpha-63Ni3S2 showed a higher uptake of its solubilized fraction by USL. This allows an explanation of the different genotoxic action of nickel on the two cell types. In this study we demonstrated that hypersensitivity has an influence on the incorporation of alpha-Ni3S2 and subsequently on the different induction of chromosomal aberrations in human lymphocytes. PMID:1602972

  16. In vitro cytogenetic studies of organic chemicals found as contaminants in spacecraft cabin atmospheres

    Science.gov (United States)

    Torres, J.

    1986-01-01

    Astronauts can be exposed during spaceflight to organic chemical contaminants in the spacecraft cabin atmosphere. Toxic exposures may cause lesions in the cellular DNA which are subsequently expressed as sister-chromatid exchanges (SCE). Analysis of SCE is a sensitive short-term assay technique to detect and quantitate exposures to DNA-damaging (mutagenic) substances. The increase in SCE incidence over baseline (control) levels is generally proportional to the concentration of the mutagen and to the duration of exposure. Dichloromethane (methylene chloride) was chosen for this study since it occurred as an atmospheric contaminant in ten of the first 12 STS flights, and has been reported to have toxic and mutagenic effects in various test systems. Glutaraldehyde was chosen because relatively few data are available on the toxicity or mutagenicity of this common biological fixative, which is carried on STS flights for use in biological experiments. The BHK-21 baby hamster kidney cell line was the in vitro test system used in this study. Neither dichloromethane (10 ppm to 500 ppm) nor glutaraldehyde (1 ppm to 10 ppm) increased SCE levels following 20-hour exposure of BHK-21 cells to the test chemicals.

  17. Induction of SCEs and DNA fragmentation in bovine peripheral lymphocytes by in vitro exposure to tolylfluanid-based fungicide

    Directory of Open Access Journals (Sweden)

    Katarína Siviková

    2011-01-01

    Full Text Available The potential for genotoxic and cytotoxic effects of tolylfluanid-based fungicide (50% active agent was evaluated using sister chromatid exchange (SCE and proliferation indices (PI in cultured bovine peripheral lymphocytes. For the detection of possible genetic damage, DNA fragmentation assay was also applied. Bovine lymphocytes cultured for 72 h were treated with the fungicide at the final concentrations of 1.75, 3.5, 8.75, and 17.5 µg/mL for the last 24 and 48 h of culture without S9 metabolic activation, and during the last 2 h of culture with S9 metabolic activation. In the SCE assays no evidence for genotoxic activity of the fungicide was found in treatments of 24 h without and 2 h with S9. After the 24 h exposure to tolylfluanid, a weak decrease in the PI was observed. With the prolonged exposure time (48 h, dose dependence in the increase of SCE frequencies was observed. Moreover, after 48 h exposure slight fragmentation of DNA at the concentrations of 3.5 and 8.75 µg/mL was demonstrated. SCE quantification is the most widely used approach for the assessment of genotoxic/cytogenetic effects of chemical compounds. Positive results in the assay at 48 h exposure indicated a potential of the fungicide to increase frequency of chromosomal damage (replication injuries that is the confirmation of early effect of exposure.

  18. The C-terminal domain of the Bloom syndrome DNA helicase is essential for genomic stability

    Directory of Open Access Journals (Sweden)

    Noonan James P

    2001-07-01

    Full Text Available Abstract Background Bloom syndrome is a rare cancer-prone disorder in which the cells of affected persons have a high frequency of somatic mutation and genomic instability. Bloom syndrome cells have a distinctive high frequency of sister chromatid exchange and quadriradial formation. BLM, the protein altered in BS, is a member of the RecQ DNA helicase family, whose members share an average of 40% identity in the helicase domain and have divergent N-terminal and C-terminal flanking regions of variable lengths. The BLM DNA helicase has been shown to localize to the ND10 (nuclear domain 10 or PML (promyelocytic leukemia nuclear bodies, where it associates with TOPIIIα, and to the nucleolus. Results This report demonstrates that the N-terminal domain of BLM is responsible for localization of the protein to the nuclear bodies, while the C-terminal domain directs the protein to the nucleolus. Deletions of the N-terminal domain of BLM have little effect on sister chromatid exchange frequency and chromosome stability as compared to helicase and C-terminal mutations which can increase SCE frequency and chromosome abnormalities. Conclusion The helicase activity and the C-terminal domain of BLM are critical for maintaining genomic stability as measured by the sister chromatid exchange assay. The localization of BLM into the nucleolus by the C-terminal domain appears to be more important to genomic stability than localization in the nuclear bodies.

  19. Heat exchangers: operation problems

    International Nuclear Information System (INIS)

    The main operation problems for heat exchangers are fouling, corrosion, vibrations and mechanical resistance. Fouling and corrosion lead to an over dimensioning, energy consumption increase, corroded pieces change, shutdown costs. Vibrations are taken in account during the dimensioning phase of the heat exchangers. Mechanical resistance problems are, for the classical ones, described in regulation texts. (A.B.). 5 figs., 4 tabs

  20. Handicapping Social Exchange Theory.

    Science.gov (United States)

    Mishler, Barbara

    The economic theory of social exchange has some serious shortcomings when applied to minorities--especially the disabled. First, it assumes dyads comprise the basic unit where exchange occurs and that rewards and costs must occur at that level. Second, the model standardizes the experience of white, Western European and American males. The model…

  1. 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…

  2. 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.

  3. 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.

  4. Standardizing exchange formats

    International Nuclear Information System (INIS)

    An international network of co-operating data centres is described who maintain identical data bases which are simultaneously updated by an agreed data exchange procedure. The agreement covers ''data exchange formats'' which are compatible to the centres' internal data storage and retrieval systems which remain different, optimized at each centre to the available computer facilities and to the needs of the data users. Essential condition for the data exchange is an agreement on common procedures for the data exchange is an agreement on common procedures for the data compilation, including critical data analysis and validation. The systems described (''EXFOR'', ''ENDF'', ''CINDA'') are used for ''nuclear reaction data'', but the principles used for data compilation and exchange should be valid also for other data types. (author). 24 refs, 4 figs

  5. Differential radiosensitivity phenotypes of DNA-PKcs mutations affecting NHEJ and HRR systems following irradiation with gamma-rays or very low fluences of alpha particles.

    Directory of Open Access Journals (Sweden)

    Yu-Fen Lin

    Full Text Available We have examined cell-cycle dependence of chromosomal aberration induction and cell killing after high or low dose-rate γ irradiation in cells bearing DNA-PKcs mutations in the S2056 cluster, the T2609 cluster, or the kinase domain. We also compared sister chromatid exchanges (SCE production by very low fluences of α-particles in DNA-PKcs mutant cells, and in homologous recombination repair (HRR mutant cells including Rad51C, Rad51D, and Fancg/xrcc9. Generally, chromosomal aberrations and cell killing by γ-rays were similarly affected by mutations in DNA-PKcs, and these mutant cells were more sensitive in G1 than in S/G2 phase. In G1-irradiated DNA-PKcs mutant cells, both chromosome- and chromatid-type breaks and exchanges were in excess than wild-type cells. For cells irradiated in late S/G2 phase, mutant cells showed very high yields of chromatid breaks compared to wild-type cells. Few exchanges were seen in DNA-PKcs-null, Ku80-null, or DNA-PKcs kinase dead mutants, but exchanges in excess were detected in the S2506 or T2609 cluster mutants. SCE induction by very low doses of α-particles is resulted from bystander effects in cells not traversed by α-particles. SCE seen in wild-type cells was completely abolished in Rad51C- or Rad51D-deficient cells, but near normal in Fancg/xrcc9 cells. In marked contrast, very high levels of SCEs were observed in DNA-PKcs-null, DNA-PKcs kinase-dead and Ku80-null mutants. SCE induction was also abolished in T2609 cluster mutant cells, but was only slightly reduced in the S2056 cluster mutant cells. Since both non-homologous end-joining (NHEJ and HRR systems utilize initial DNA lesions as a substrate, these results suggest the possibility of a competitive interference phenomenon operating between NHEJ and at least the Rad51C/D components of HRR; the level of interaction between damaged DNA and a particular DNA-PK component may determine the level of interaction of such DNA with a relevant HRR component.

  6. 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

  7. 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.

  8. Exchange-Correlation Functionals via Local Interpolation along the Adiabatic Connection.

    Science.gov (United States)

    Vuckovic, Stefan; Irons, Tom J P; Savin, Andreas; Teale, Andrew M; Gori-Giorgi, Paola

    2016-06-14

    The construction of density-functional approximations is explored by modeling the adiabatic connection locally, using energy densities defined in terms of the electrostatic potential of the exchange-correlation hole. These local models are more amenable to the construction of size-consistent approximations than their global counterparts. In this work we use accurate input local ingredients to assess the accuracy of a range of local interpolation models against accurate exchange-correlation energy densities. The importance of the strictly correlated electrons (SCE) functional describing the strong coupling limit is emphasized, enabling the corresponding interpolated functionals to treat strong correlation effects. In addition to exploring the performance of such models numerically for the helium and beryllium isoelectronic series and the dissociation of the hydrogen molecule, an approximate analytic model is presented for the initial slope of the local adiabatic connection. Comparisons are made with approaches based on global models, and prospects for future approximations based on the local adiabatic connection are discussed. PMID:27116427

  9. Support for heat exchangers

    International Nuclear Information System (INIS)

    The very large heat exchangers which are typical of many nuclear power plants place great demands on their supports. The support here described is for a vertical heat exchanger. A convex Lubrit plate allows a certain amount of transverse and rotational movement of the heat exhanger relative to the foundation. Taps engaging in the support surface of the heat exchanger and between the support box and the concrete foundation ensure that relative movement is restricted to those surfaces where it is intended. A steel box structure embedded in the concrete foundation dissipates heat transferred through the support system and avoids overheating the concrete. Horizontal stays support the heat exchanger against the concrete walls. (JIW)

  10. 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...

  11. Central Data Exchange

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Central Data Exchange (CDX) enables fast, efficient and more accurate environmental data submissions from state and local governments, industry and tribes to...

  12. 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.

  13. 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...

  14. Opinion Exchange Dynamics

    OpenAIRE

    Mossel, Elchanan; Tamuz, Omer

    2014-01-01

    We survey a range of models of opinion exchange. From the introduction: "The exchange of opinions between individuals is a fundamental social interaction... Moreover, many models in this field are an excellent playground for mathematicians, especially those working in probability, algorithms and combinatorics. One of the goals of this survey is to introduce such models to mathematicians, and especially to those working in discrete mathematics, information theory, optimization and probability ...

  15. Cryptographic Combinatorial Securities Exchanges

    Science.gov (United States)

    Thorpe, Christopher; Parkes, David C.

    We present a useful new mechanism that facilitates the atomic exchange of many large baskets of securities in a combinatorial exchange. Cryptography prevents information about the securities in the baskets from being exploited, enhancing trust. Our exchange offers institutions who wish to trade large positions a new alternative to existing methods of block trading: they can reduce transaction costs by taking advantage of other institutions’ available liquidity, while third party liquidity providers guarantee execution—preserving their desired portfolio composition at all times. In our exchange, institutions submit encrypted orders which are crossed, leaving a “remainder”. The exchange proves facts about the portfolio risk of this remainder to third party liquidity providers without revealing the securities in the remainder, the knowledge of which could also be exploited. The third parties learn either (depending on the setting) the portfolio risk parameters of the remainder itself, or how their own portfolio risk would change if they were to incorporate the remainder into a portfolio they submit. In one setting, these third parties submit bids on the commission, and the winner supplies necessary liquidity for the entire exchange to clear. This guaranteed clearing, coupled with external price discovery from the primary markets for the securities, sidesteps difficult combinatorial optimization problems. This latter method of proving how taking on the remainder would change risk parameters of one’s own portfolio, without revealing the remainder’s contents or its own risk parameters, is a useful protocol of independent interest.

  16. Heat exchanger restart evaluation

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-03-18

    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 4A 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 identified tube. The leaking tube was removed and examined metallurgically to determine 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 summary herein.

  17. Heat exchanger restart evaluation

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-03-18

    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 4A 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 identified tube. The leaking tube was removed and examined metallurgically to determine 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.

  18. Heat exchanger restart evaluation

    International Nuclear Information System (INIS)

    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 4A 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 identified tube. The leaking tube was removed and examined metallurgically to determine 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

  19. On exchangeable multinomial distributions

    Science.gov (United States)

    George, E. Olusegun; Cheon, Kyeongmi; Yuan, Yilian; Szabo, Aniko

    2016-01-01

    We derive an expression for the joint distribution of exchangeable multinomial random variables, which generalizes the multinomial distribution based on independent trials while retaining some of its important properties. Unlike de Finneti's representation theorem for a binary sequence, the exchangeable multinomial distribution derived here does not require that the finite set of random variables under consideration be a subset of an infinite sequence. Using expressions for higher moments and correlations, we show that the covariance matrix for exchangeable multinomial data has a different form from that usually assumed in the literature, and we analyse data from developmental toxicology studies. The proposed analyses have been implemented in R and are available on CRAN in the CorrBin package.

  20. 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).

  1. Tubular heat exchanger

    International Nuclear Information System (INIS)

    The invention concerns a heat exchanger of which the tubes, placed in a long casing, cross the casing cover in a sealed manner. These tubes are fixed to the tube plate forming this cover or to the branch tubes it comprises by means of compression joints. These joints make it possible to do away with welds that are sources of defects and to improve the operational safety of the apparatus. An advantageous form of the heat exchanger under the invention includes a manifold for each thermal exchange fluid, and one end of each tube is connected to this manifold by a pipe that is itself connected to the tube by a threaded connection. The latter provides for easy disconnection of the pipe in order to introduce a probe for inspecting the state of the tubes

  2. 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.

  3. Alert Exchange Process Protocol

    Science.gov (United States)

    Groen, Frank

    2015-01-01

    The National Aeronautics and Space Administration of the United States of America (NASA), and the European Space Agency (ESA), and the Japanese Aerospace Exploration Agency (JAXA), acknowledging that NASA, ESA and JAXA have a mutual interest in exchanging Alerts and Alert Status Lists to enhance the information base for each system participant while fortifying the general level of cooperation between the policy agreement subscribers, and each Party will exchange Alert listings on regular basis and detailed Alert information on a need to know basis to the extent permitted by law.

  4. Microscale Regenerative Heat Exchanger

    Science.gov (United States)

    Moran, Matthew E.; Stelter, Stephan; Stelter, Manfred

    2006-01-01

    The device described herein is designed primarily for use as a regenerative heat exchanger in a miniature Stirling engine or Stirling-cycle heat pump. A regenerative heat exchanger (sometimes called, simply, a "regenerator" in the Stirling-engine art) is basically a thermal capacitor: Its role in the Stirling cycle is to alternately accept heat from, then deliver heat to, an oscillating flow of a working fluid between compression and expansion volumes, without introducing an excessive pressure drop. These volumes are at different temperatures, and conduction of heat between these volumes is undesirable because it reduces the energy-conversion efficiency of the Stirling cycle.

  5. Heat exchanger panel

    Science.gov (United States)

    Warburton, Robert E. (Inventor); Cuva, William J. (Inventor)

    2005-01-01

    The present invention relates to a heat exchanger panel which has broad utility in high temperature environments. The heat exchanger panel has a first panel, a second panel, and at least one fluid containment device positioned intermediate the first and second panels. At least one of the first panel and the second panel have at least one feature on an interior surface to accommodate the at least one fluid containment device. In a preferred embodiment, each of the first and second panels is formed from a high conductivity, high temperature composite material. Also, in a preferred embodiment, the first and second panels are joined together by one or more composite fasteners.

  6. 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.

  7. Technology Performance Exchange

    Energy Technology Data Exchange (ETDEWEB)

    2015-09-01

    To address the need for accessible, high-quality data, the Department of Energy has developed the Technology Performance Exchange (TPEx). TPEx enables technology suppliers, third-party testing laboratories, and other entities to share product performance data. These data are automatically transformed into a format that technology evaluators can easily use in their energy modeling assessments to inform procurement decisions.

  8. Global Foreign Exchange Turnover

    OpenAIRE

    Crystal Ossolinski; Andrew Zurawski

    2010-01-01

    The most recent six-monthly data on global foreign exchange turnover show a rebound in activity between April and October 2009 across all markets and major currency pairs. The broad-based increase in turnover is in line with the improvement in global economic and financial conditions since early 2009. Despite the rebound, turnover remains below the peak in early 2008.

  9. Heat exchanger vibration

    International Nuclear Information System (INIS)

    The heat exchangers of various types are common items of plant in the generation and transmission of electricity. The amount of attention given to the flow-induced vibrations of heat exchangers by designers is usually related to the operational history of similar items of plant. Consequently, if a particular design procedure yields items of plant which behave in a satisfactory manner during their operational life, there is little incentive to improve or refine the design procedure. On the other hand, failures of heat exchangers clearly indicate deficiencies in the design procedures or in the data available to the designer. When such failures are attributable to flow-induced vibrations, the identification of the mechanisms involved is a prime importance. Ideally, basic research work provides the background understanding and the techniques necessary to be able to identify the important mechanisms. In practice, the investigation of a flow-induced vibration problem may identify the presence of mechanisms but may not be able to quantify their effects adequately. In these circumstances the need for additional work is established and the objectives of the research programme emerge. The purpose of this paper is to outline the background to the current research programme at C.E.R.L. on heat exchanger vibration

  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 consumers…

  11. Chapter 11. Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rafferty, Kevin D.; Culver, Gene

    1998-01-01

    Most geothermal fluids, because of their elevated temperature, contain a variety of dissolved chemicals. These chemicals are frequently corrosive toward standard materials of construction. As a result, it is advisable in most cases to isolate the geothermal fluid from the process to which heat is being transferred. The task of heat transfer from the geothermal fluid to a closed process loop is most often handled by a plate heat exchanger. The two most common types used in geothermal applications are: bolted and brazed. For smaller systems, in geothermal resource areas of a specific character, downhole heat exchangers (DHEs) provide a unique means of heat extraction. These devices eliminate the requirement for physical removal of fluid from the well. For this reason, DHE-based systems avoid entirely the environmental and practical problems associated with fluid disposal. Shell and tube heat exchangers play only a minor role in low-temperature, direct-use systems. These units have been in common use in industrial applications for many years and, as a result, are well understood. For these reasons, shell and tube heat exchangers will not be covered in this chapter.

  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. The Chicago Climate Exchange

    International Nuclear Information System (INIS)

    About the organization and activities of the Chicago Climate Exchange (CCX). According to the author the CCX is the world's first and North America's only voluntary, legally binding integrated greenhouse gas reduction and trading system for all 6 GHG emission sources, with offset projects in North America and worldwide

  14. Chemical exchange program analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Waffelaert, Pascale

    2007-09-01

    As part of its EMS, Sandia performs an annual environmental aspects/impacts analysis. The purpose of this analysis is to identify the environmental aspects associated with Sandia's activities, products, and services and the potential environmental impacts associated with those aspects. Division and environmental programs established objectives and targets based on the environmental aspects associated with their operations. In 2007 the most significant aspect identified was Hazardous Materials (Use and Storage). The objective for Hazardous Materials (Use and Storage) was to improve chemical handling, storage, and on-site movement of hazardous materials. One of the targets supporting this objective was to develop an effective chemical exchange program, making a business case for it in FY07, and fully implementing a comprehensive chemical exchange program in FY08. A Chemical Exchange Program (CEP) team was formed to implement this target. The team consists of representatives from the Chemical Information System (CIS), Pollution Prevention (P2), the HWMF, Procurement and the Environmental Management System (EMS). The CEP Team performed benchmarking and conducted a life-cycle analysis of the current management of chemicals at SNL/NM and compared it to Chemical Exchange alternatives. Those alternatives are as follows: (1) Revive the 'Virtual' Chemical Exchange Program; (2) Re-implement a 'Physical' Chemical Exchange Program using a Chemical Information System; and (3) Transition to a Chemical Management Services System. The analysis and benchmarking study shows that the present management of chemicals at SNL/NM is significantly disjointed and a life-cycle or 'Cradle-to-Grave' approach to chemical management is needed. This approach must consider the purchasing and maintenance costs as well as the cost of ultimate disposal of the chemicals and materials. A chemical exchange is needed as a mechanism to re-apply chemicals on site. This

  15. Lithium Alkyl Exchange Equilibria

    International Nuclear Information System (INIS)

    Kinetic analyses of two types of exchange reactions of organo- lithium reagents, both alkyl and aryl types, RLi, have been made: (1) halogen-metal interchange with alkyl and aryl halides, R'X, and (2) hydrogen-metal interchange (commonly called metallation) with aromatic hydrocarbons, R'H. Rates of these RLi + R'X ⇄ RX + R'Li; (1) . RLi + R'H ⇄ RH+ R'Li (2) reactions have been determined, conditions under which the systems attain equilibrium have been established, and the positions of equilibrium measured, all as functions of the reactants, solvents and catalysts employed. Concerning halogen-lithium interchange between alkyl groups (1), the conclusion is reached that equilibration proceeds to yield the less sterically demanding alkyl group attached to lithium. The data show, for example, that isobutyllithium is much less stable than n-butyllithium, and again, that 2,6-dimethyl- phenyllithium is much less stable than phenyllithium. The exchange is general with iodides, occurs with some bromides and does not occur with chlorides. The exchange is quite slow in hydrocarbon media and is catalysed by relatively small amounts of ethers. In the presence of the optically active methyl ether of menthol, methyl iodide exchanges with racemic s-butyllithium to give optically active s-butyl iodide. In work with the second reaction, hydrogen-lithium interchange (2), nuclear magnetic resonance spectrometry has been used for rate studies. Catalysts (Lewis bases) have been evolved for establishing equilibria in rather unreactive systems, e.g. phenyllithium can be demonstrated to exchange with benzene by labelling the latter radioactivity. From the correlations of structure and reactivity found in this study, the conclusion is reached that the basic alkyllithium structure is dimeric, R2Li2 The arrangement of the groups within this dimer satisfactorily explain the special steric effects noted in organolithium reagent stability. (author)

  16. 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.

  17. Analytical applications of ion exchangers

    CERN Document Server

    Inczédy, J

    2013-01-01

    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

  18. Exchange Rate Risk and the Macroeconomics of Exchange Rate Determination

    OpenAIRE

    Rudiger Dornbusch

    1980-01-01

    This paper discusses the link between portfolio diversification models of exchange risk and the macroeconomics of exchange rate determination. A first part sets out the mean-variance model of portfolio choice for the case of two nominal assets with random real returns. From there the model is made "international" by a specification of the world inflation process. The concept of exchange risk is discussed in terms of the variability of the real exchange rate. The paper shows that when all rand...

  19. Heat exchanger with removable orifice

    International Nuclear Information System (INIS)

    A nuclear reactor steam generator heat exchanger is described which has orifices in the entrance openings of the heat exchange tubes which, although securely fastened to the tubes, can be easily removed by remote handling equipment. (U.K.)

  20. 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...

  1. 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.

  2. Plate heat exchanger

    International Nuclear Information System (INIS)

    The plate exchanger described includes a series of individual modules joined together, communicating in pairs to delimit two flow circuits separated by two fluids mutually exchanging calories. Each module includes at least one flat frame around a central cavity, at least two apertures made in the frame respectively for the inlet and oulet of the fluids crossing the cavity and at least one opening in the frame for the fluids to pass to a neighbouring module. The frames of the modules form a stack plane upon plane and are isolated by a thin leak-tight sheet parallel to the plane of the frames and separating the fluid substances in two superimposed frames. The heat transfer between these fluids occurs through this thin sheet from one module to the next in the stack

  3. Compact cryocooler heat exchangers

    International Nuclear Information System (INIS)

    Compact heat exchangers are subject to different constraints as a room temperature gas is cooled down by a cold stream returning from a JT valve (or a similar cryoprocess component). In particular, the optimization of exchangers for liquid helium systems has to cover a wide range in temperature and density of the fluid. In the present work we address the following thermodynamic questions: 1. The optimization of intermediate temperatures which optimize stage operation (a stage is assumed to have a constant cross section); 2. The optimum temperature difference available for best overall economic performance values. The results are viewed in the context of porous media concepts applied to rather low speeds of fluid flow in narrow passages. In this paper examples of fluid/solid constraints imposed in this non-classical low temperature area are presented

  4. Inverse indirect magnetic exchange

    OpenAIRE

    Schwabe, Andrej; Titvinidze, Irakli; Potthoff, Michael

    2013-01-01

    Magnetic moments strongly coupled to the spins of conduction electrons in a nanostructure can confine the conduction-electron motion due to scattering at almost localized Kondo singlets. We study the resulting local-moment formation in the conduction-electron system and the magnetic exchange coupling mediated by the Kondo singlets. Its distance dependence is oscillatory and induces robust ferro- or antiferromagnetic order in multi-impurity systems.

  5. 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...

  6. Membrane Based Heat Exchanger

    OpenAIRE

    Aarnes, Sofie Marie

    2012-01-01

    Reduction of the energy used to acclimatise buildings is a huge challenge simultaneously with the implementation of air tight low energy buildings. In residential buildings with several living units centralised air handling units are the most energy efficient system. However, in a centralised system there is important to avoid leakages of pollutions between the exhaust air and the supply air. This leads to that flat plate heat exchangers are used instead of the more energy efficient rotary he...

  7. Knowledge exchange at HKU

    OpenAIRE

    Bacon-shone, J

    2010-01-01

    This talk will explain the KE process in HKU and how we currently answer the following questions: * What is Knowledge Exchange and how is it different from Technology Transfer? * How to identify good KE? * How does good KE benefit the university and its reputation? * How to reward good KE at the individual, department and faculty level? * How to manage our stakeholder relationships from a KE perspective? John Bacon-Shone is currently Associate Director ...

  8. 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...

  9. Exchange currents in nuclear physics

    International Nuclear Information System (INIS)

    Starting from Adler's low-energy theorem for the soft pion production amplitudes the predictions of the meson exchange currents theory for the nuclear physics are discussed. The results are reformulated in terms of phenomenological lagrangians. This method allows one to pass naturally to the more realistic case of hard mesons. The predictions are critically compared with the existing experimental data. The main processes in which vector isovector exchange currents, vector isoscalar exchange currents and axial exchange currents take place are pointed out

  10. 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.

  11. Hydrogen isotope exchange reactions

    International Nuclear Information System (INIS)

    The two most widely used methods for following hydrogen isotope exchange reactions, namely dedeuteriation and detritiation, involve in the first place the synthesis of an appropriately labelled compound. Rates of dedeuteriation are usually followed by measuring changes in the 1H n.m.r. spectrum of the substrate (examples are given); the method not only gives the rate but also the site(s) of exchange. It is limited to rather slow reactions and is not as accurate as some of the other methods. The development of deuterium n.m.r. spectroscopy means that changes in the 2H n.m.r. spectrum can also be used to measure rates of dedeuteriation. The development of liquid scintillation counting greatly eased the problem of how to detect weak β emitters; the attractions of tritium as a tracer were thereby much enhanced. Nowadays the study of rates of detritiation constitutes one of the most versatile and accurate methods of following hydrogen isotope exchange. Examples of the technique are given. (U.K.)

  12. Soviets seek scientific exchange

    Science.gov (United States)

    GEOS-A, associated with the Soviet Union's Institute of Earth Physics, is seeking to promote exchange between Soviet and Western geophysicists. GEOS-A is a nonprofit, private organization formed by specialists from the U.S.S.R. Academy of Scientists.GEOS-A aims to promote the transfer of academic research results to industry and education. It also seeks to stimulate international scientific exchange and to support independent nongovernmental programs and expertise in geophysics and ecology. The organization would like to cooperate with Western universities in exchanging students and young scientists and in building scientific relationships between the two countries. This would include inviting students and young specialists for collaborative scientific research, consultations, language practice, and graduate study in any institute of the U.S.S.R. Academy of Sciences. Participants would live in rented private apartments in downtown Moscow for approximately one week to several months. All living expenses would be covered at a rate higher than the academy's standard one (unfortunately travel to and from the Soviet Union cannot be covered).

  13. 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.

  14. Heat exchanger tube tool

    International Nuclear Information System (INIS)

    Certain types of heat-exchangers have tubes opening through a tube sheet to a manifold having an access opening offset from alignment with the tube ends. A tool for inserting a device, such as for inspection or repair, is provided for use in such instances. The tool is formed by a flexible guide tube insertable through the access opening and having an inner end provided with a connector for connection with the opening of the tube in which the device is to be inserted, and an outer end which remains outside of the chamber, the guide tube having adequate length for this arrangement. A flexible transport hose for internally transporting the device slides inside of the guide tube. This hose is long enough to slide through the guide tube, into the heat-exchanger tube, and through the latter to the extent required for the use of the device. The guide tube must be bent to reach the end of the heat-exchanger tube and the latter may be constructed with a bend, the hose carrying anit-friction elements at interspaced locations along its length to make it possible for the hose to negotiate such bends while sliding to the location where the use of the device is required

  15. 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...

  16. 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.

  17. Genetic effects of methylmercury in human chromosomes: I. A cytogenetic study of people exposed through eating contaminated fish

    Energy Technology Data Exchange (ETDEWEB)

    Monsalve, M.V.; Chiappe, C.

    1987-01-01

    An analysis of chromosomal aberrations (structural and numerical) and sister chromatid exchange (SCE) was carried out on 16 people exposed to methylmercury through eating fish caught in Cartagena Bay (Colombia), an area of known methylmercury contamination. Fourteen people whose diet consisted mainly of fish caught in another, noncontaminated area of the Atlantic acted as controls. The results showed a significant difference between the experimental and control groups in methylmercury (MM) concentrations measured in hair and peripheral blood. Subsequently, significant differences between levels of organic mercury in blood and hair were found when all the individuals studied were classified in two groups according to their blood mercury levels. When achromatic lesions were included, the frequency of structural chromosome aberrations and groups (exposed and control). When the achromatic lesions were excluded from the analyses, these differences were not found. There was a significant correlation between SCE and age. This is the first report of a study on the frequency of SCE in a population exposed to methylmercury.

  18. Comparative study of the cytotoxic and genotoxic effects of titanium oxide and aluminium oxide nanoparticles in Chinese hamster ovary (CHO-K1) cells

    International Nuclear Information System (INIS)

    The aim of this study was to analyze the cytotoxicity and genotoxicity of titanium oxide (TiO2) and aluminium oxide (Al2O3) nanoparticles (NPs) on Chinese hamster ovary (CHO-K1) cells using neutral red (NR), mitochondrial activity (by MTT assay), sister chromatid exchange (SCE), micronucleus (MN) formation, and cell cycle kinetics techniques. Results showed a dose-related cytotoxic effect evidenced after 24 h by changes in lysosomal and mitochondrial dehydrogenase activity. Interestingly, transmission electronic microscopy (TEM) showed the formation of perinuclear vesicles in CHO-K1 cells after treatment with both NPs during 24 h but no NP was detected in the nuclei. Genotoxic effects were shown by MN frequencies which significantly increased at 0.5 and 1 μg/mL TiO2 and 0.5-10 μg/mL Al2O3. SCE frequencies were higher for cells treated with 1-5 μg/mL TiO2. The absence of metaphases evidenced cytotoxicity for higher concentrations of TiO2. No SCE induction was achieved after treatment with 1-25 μg/mL Al2O3. In conclusion, findings showed cytotoxic and genotoxic effects of TiO2 and Al2O3 NPs on CHO-K1 cells. Possible causes of controversial reports are discussed further on.

  19. Provocation and palliation of in vitro cellular aging

    International Nuclear Information System (INIS)

    Normal human fibroblast cell lines, obtained from a male neonate, were serially cultivated in vitro in MEM-H medium until senescence. One cell line was irradiated with Co60, 400 rad at population doublings of approximately 12, 24, and 32. In addition, one cell line was similarly irradiated after 30 minutes of preconditioning with 5 mM cysteamine and catalase. The cells were maintained to an average of 66 population doublings. Sister chromatid exchanges (SCE) were enumerated at critical periods and growth parameters were continuously evaluated. It as postulated that because the efficiency of DNA repair declines with age, free radical DNA damage may be more harmful to older cells. Also, DNA damage may effectively be retarded by exogenous compounds, in this case, cysteamine. It was demonstrated that the identical free radical insult does indeed cause more DNA damage, as determined by SCE frequency and growth potential, as a cell ages. Radiation-induced SCE-type damage was virtually eliminated by the addition of cysteamine and catalase. Reduction of final population doubling level was commensurate with the growth inhibition discussed

  20. Evaluation of antigenotoxic effects of carotenoids from green algae Chlorococcum humicola using human lymphocytes

    Institute of Scientific and Technical Information of China (English)

    Bhagavathy S; Sumathi P

    2012-01-01

    Objective:To identify the available phytochemicals and carotenoids in the selected green algae and evaluate the potential genotoxic/antigenotoxic effect using lymphocytes. Methods:Organic solvent extracts of Chlorococcum humicola (C. humicola) were used for the phytochemical analysis. The available carotenoids were assessed by HPLC, and LC-MS analysis. The genotoxicity was induced by the benzo(a)pyrene in the lymphocyte culture, the genotoxic and antigenotoxic effects of algal carotenoids with and without genotoxic inducer were evaluated by chromosomal aberration (CA), sister chromatid exchange (SCE) and micronucleus assay (MN). Results: The results of the analysis showed that the algae were rich in carotenoids and fatty acids. In the total carotenoids lutein,β-carotene and α-carotene were found to be present in higher concentration. The frequency of CA and SCE increased by benzo(a)pyrene were significantly decreased by the carotenoids (P<0.05 for CA, P<0.001 for SCE). The MN frequencies of the cells were significantly decreased by the treatment with carotenoids when compared with the positive controls (P<0.05). Conclusions:The findings of the present study demonstrate that, the green algae C. humicola is a rich source of bioactive compounds especially carotenoids which effectively fight against environmental genotoxic agents, the carotenoids itself is not a genotoxic substance and should be further considered for its beneficial effects.

  1. Increased chromosome damage in pediatric heart catheterization patients after diagnostic fluoroscopy and cineangiography

    International Nuclear Information System (INIS)

    Chromosome damage (CD) and sister chromatid exchange (SCE) levels were studied in lymphocytes from 30 pediatric heart catheterization patients receiving radiation during diagnostic fluoroscopy and cineangiography procedures. Forty-eight-hour CD and 72-hr SCE cultures were prepared from sequential samples taken from each patient: samples 1-3 via the catheter the same day (1) before exposure, (2) after fluoroscopy, and (3) after cineangiography; and sample 4 by venipuncture the next morning. Significant increases in CD (dicentrics, rings, and fragments), but not SCE, were observed. From a mean base level of 0.4% cells with CD, the CD levels increased 2-3-fold in samples 3 and 4 (p = .001). Rings only occurred in samples 3 and 4. While increased CD levels also correlated with increasing age, body surface area, and weight, partial correlations controlling for these factors clearly indicate that the CD effects are principally attributable to the radiological procedures (p = .001). Increased CD levels correlated with both the roentgen dose of cineangiography exposure (p = .002) and the volume of contrast medium (p = .000); however, partial correlations, controlling for either factor, indicate that the contrast medium was the principal factor (p = .006)

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

    OpenAIRE

    J. Saúl Lizondo

    1991-01-01

    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 e...

  3. The Dynamics of Multilateral Exchange

    Science.gov (United States)

    Hausken, Kjell; Moxnes, John F.

    The article formulates a dynamic mathematical model where arbitrarily many players produce, consume, exchange, loan, and deposit arbitrarily many goods over time to maximize utility. Consuming goods constitutes a benefit, and producing, exporting, and loaning away goods constitute a cost. Utilities are benefits minus costs, which depend on the exchange ratios and bargaining functions. Three-way exchange occurs when one player acquires, through exchange, one good from another player with the sole purpose of using this good to exchange against the desired good from a third player. Such a triple handshake is not merely a set of double handshakes since the player assigns no interest to the first good in his benefit function. Cognitive and organization costs increase dramatically for higher order exchanges. An exchange theory accounting for media of exchange follows from simple generalization of two-way exchange. The examples of r-way exchange are the triangle trade between Africa, the USA, and England in the 17th and 18th centuries, the hypothetical hypercycle involving RNAs as players and enzymes as goods, and reaction-diffusion processes. The emergence of exchange, and the role of trading agents are discussed. We simulate an example where two-way exchange gives zero production and zero utility, while three-way exchange causes considerable production and positive utility. Maximum utility for each player is reached when exchanges of the same order as the number of players in society are allowed. The article merges micro theory and macro theory within the social, natural, and physical sciences.

  4. Asymmetric exchange in flocks

    OpenAIRE

    Dadhichi, Lokrshi Prawar; Chajwa, Rahul; 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 ba...

  5. 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.

  6. Plate heat exchanger

    International Nuclear Information System (INIS)

    In a plate heat exchanger required to handle corrosive, toxic or radioactive fluids, wherein each plate has a peripheral recess or like formation adapted for receiving an elastomeric gasket, the plates are welded together in pairs by the method comprising the steps of inserting into the gasket recess of a first plate of said pair a metal packing piece and welding the second place (e.g. by a laser or electron beam weld running along the base of the recess) superimposing a second plate on to the first in contact with the packing piece and welding the second plate to the packing piece (e.g. by a laser or electron beam weld). The packing piece may be of hollow or solid cross section and is preferably of the same material (e.g. titanium or stainless steel) as the plates. In use a service fluid in heat exchange with the said corrosive etc. fluid is confined by peripheral and normally elastomeric gaskets. (author)

  7. 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.

  8. Ion exchange technology assessment report

    International Nuclear Information System (INIS)

    In the execution of its charter, the SRS Ion Exchange Technology Assessment Team has determined that ion exchange (IX) technology has evolved to the point where it should now be considered as a viable alternative to the SRS reference ITP/LW/PH process. The ion exchange media available today offer the ability to design ion exchange processing systems tailored to the unique physical and chemical properties of SRS soluble HLW's. The technical assessment of IX technology and its applicability to the processing of SRS soluble HLW has demonstrated that IX is unquestionably a viable technology. A task team was chartered to evaluate the technology of ion exchange and its potential for replacing the present In-Tank Precipitation and proposed Late Wash processes to remove Cs, Sr, and Pu from soluble salt solutions at the Savannah River Site. This report documents the ion exchange technology assessment and conclusions of the task team

  9. The Stability of Exchange Networks

    OpenAIRE

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

    2007-01-01

    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 happens to both the network structure and actor payoffs whenmyopic actors change their links in order to maximize their payoffs. We investigate the networks that are stable, the networks that are effici...

  10. Relative exchangeability with equivalence relations

    OpenAIRE

    Crane, Harry; Towsner, Henry

    2016-01-01

    We describe an Aldous--Hoover-type characterization of random relational structures that are exchangeable relative to a fixed structure which may have various equivalence relations. Our main theorem gives the common generalization of the results on relative exchangeability due to Ackerman \\cite{Ackerman2015} and Crane and Towsner \\cite{CraneTowsner2015} and hierarchical exchangeability results due to Austin and Panchenko \\cite{AustinPanchenko2014}.

  11. Diffusion-Exchange Weighted Imaging

    OpenAIRE

    Saadallah Ramadan

    2009-01-01

    A method has been developed whereby diffusion and exchange in micro cellular structures in the human brain are correlated to produce a new type of image contrast leading to determination of water exchange rates in vivo. The diffusion method relies on differential apparent diffusion coefficients as detectable nuclei exchange between adjacent compartments marked with different apparent diffusion coefficient values (e.g. intra- and extra-cellular compartments). A new pulse sequence was developed...

  12. Information exchange in paediatric care

    OpenAIRE

    Mårtenson Wikström, Eva

    2009-01-01

    Information exchange is an essential component for all involved in the paediatric care encounter. Despite this, most of the research about information exchange concerns adults and the significance of the child’s existence in the encounter have not been given sufficient attention. Therefore, the overall aims of this thesis were twofold. Firstly, the aim was to identify, describe and generate concepts in information exchange between minors, parents/guardians and health care professionals in pae...

  13. Cosmologies with Energy Exchange

    CERN Document Server

    Barrow, J D; Barrow, John D.

    2006-01-01

    We provide a simple mathematical description of the exchange of energy between two fluids in an expanding Friedmann universe with zero spatial curvature. The evolution can be reduced to a single non-linear differential equation which we solve in physically relevant cases and provide an analysis of all the possible evolutions. Particular power-law solutions exist for the expansion scale factor and are attractors at late times under particular conditions. We show how a number of problems studied in the literature, such as cosmological vacuum energy decay, particle annihilation, and the evolution of a population of evaporating black holes, correspond to simple particular cases of our model. In all cases we can determine the effects of the energy transfer on the expansion scale factor. We also consider the situation in the presence of anti-decaying fluids and so called phantom fluids which violate the dominant energy conditions.

  14. Redundancy of Exchangeable Estimators

    Directory of Open Access Journals (Sweden)

    Narayana P. Santhanam

    2014-10-01

    Full Text Available Exchangeable random partition processes are the basis for Bayesian approaches to statistical inference in large alphabet settings. On the other hand, the notion of the pattern of a sequence provides an information-theoretic framework for data compression in large alphabet scenarios. Because data compression and parameter estimation are intimately related, we study the redundancy of Bayes estimators coming from Poisson–Dirichlet priors (or “Chinese restaurant processes” and the Pitman–Yor prior. This provides an understanding of these estimators in the setting of unknown discrete alphabets from the perspective of universal compression. In particular, we identify relations between alphabet sizes and sample sizes where the redundancy is small, thereby characterizing useful regimes for these estimators.

  15. 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.

  16. Exchange bias theory

    International Nuclear Information System (INIS)

    Research on the exchange bias (EB) phenomenon has witnessed a flurry of activity during recent years, which stems from its use in magnetic sensors and as stabilizers in magnetic reading heads. EB was discovered in 1956 but it attracted only limited attention until these applications, closely related to giant magnetoresistance, were developed during the last decade. In this review, I initially give a short introduction, listing the most salient experimental results and what is required from an EB theory. Next, I indicate some of the obstacles in the road towards a satisfactory understanding of the phenomenon. The main body of the text reviews and critically discusses the activity that has flourished, mainly during the last 5 years, in the theoretical front. Finally, an evaluation of the progress made, and a critical assessment as to where we stand nowadays along the road to a satisfactory theory, is presented

  17. 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.

  18. Heat exchanger repair

    International Nuclear Information System (INIS)

    There are two ways to rapir heater tubes in tubular heat exchangers, partial replacement of tubes and a technique called sleeving. In the former case, the defective tube section is cut out, removed, and replaced by a new section butt welded to the old piece of tube which remained in place. In the sleeving technique, a tube sleeve is slid into the defective tube and, after expansion, welded to the original tube. In this case, the welding technique employed is not laser welding, as is often maintained in the literature, but TIG pulsation welding. The results of preliminary tests and the qualification of both processes are outlined in the article; an account is given also of the replacement of the tube sections when repairing condensate coolers. (orig.)

  19. 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

  20. The Radioecology Exchange

    International Nuclear Information System (INIS)

    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 dose estimations for

  1. 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.

  2. 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

  3. 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)

  4. 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…

  5. Electronic trading on futures exchanges

    OpenAIRE

    Asani Sarkar; Michelle Tozzi

    1998-01-01

    Although the open outcry method is still the best way to trade highly active contracts on futures exchanges, electronic systems can improve the efficiency and cost effectiveness of trading some types of futures and options. In recent years, the volume of electronic trades on futures exchanges has more than doubled, and it should continue to grow rapidly.

  6. Heat exchanger performance monitoring guidelines

    International Nuclear Information System (INIS)

    Fouling can occur in many heat exchanger applications in a way that impedes heat transfer and fluid flow and reduces the heat transfer or performance capability of the heat exchanger. Fouling may be significant for heat exchanger surfaces and flow paths in contact with plant service water. This report presents guidelines for performance monitoring of heat exchangers subject to fouling. Guidelines include selection of heat exchangers to monitor based on system function, safety function and system configuration. Five monitoring methods are discussed: the heat transfer, temperature monitoring, temperature effectiveness, delta P and periodic maintenance methods. Guidelines are included for selecting the appropriate monitoring methods and for implementing the selected methods. The report also includes a bibliography, example calculations, and technical notes applicable to the heat transfer method

  7. 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.

  8. 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

  9. 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.

  10. 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)

  11. 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.

  12. Exchange transfusion for severe malaria: A comparison of red cell exchange with whole blood exchange

    Directory of Open Access Journals (Sweden)

    Udani S

    2003-01-01

    Full Text Available Aim: To compare exchange transfusions done for severe malaria using the traditional whole blood exchange method with therapeutic red cell exchange (TREX done using a Cobe spectra cell separator. Methods: 6 children with acute, severe malaria and parasitic infestation rates (IR >50% with multi organ failure, were subjected to exchange transfusions. 3 had whole blood single volume exchanges and 3 had TREX using the Cobe-Spectra cell separator. The two groups were compared for difficulties encountered, time taken, complications, quantity of blood products used, metabolic and hematological derangements and fall in IR. Results: The TREX took less time per 100 ml of blood exchanged, resulted in a 24% more efficient decrease in the IR and required less donor plasma. 3/3 tolerated the TREX well whereas one child had complications of hypocalcemia and acidosis with the whole blood exchange. The rise in hemoglobin/hematocrit was comparable in both and the platelet count was not significantly altered in either group. There was no significant alteration in the DIC profile in either group. All 6 children recovered within comparable time frames. Conclusion: The TREX was safer, more efficacious and less time consuming. This procedure is recommended whenever available for red cell exchange in malaria.

  13. In vitro genotoxicity of chlorinated drinking water processed from humus-rich surface water

    Energy Technology Data Exchange (ETDEWEB)

    Liimatainen, A.; Grummt, T.

    1988-11-01

    Chlorination by-products of drinking waters are capable of inducing sister chromatid exchanges (SCE) and chromosome aberrations (CA) in vitro, in addition to their mutagenic activity in the Ames test. Finnish drinking waters, processed from humus-rich surface water using chlorine disinfection, have been found to be highly mutagenic in the Ames' test. The highest activities have been found in the acidic, non-volatile fraction of the water concentrates using tester strain TA100 without metabolic activation by S9mix. The mutagenicities have varied between 500 and 14,000 induced revertants per liter. These figures are one to two magnitudes higher than those reported elsewhere. The authors studied five Finnish drinking water samples for their potency to exert genotoxic effects, SCEs and CAs, in mammalian cells in vitro (human peripheral lymphocytes and Chinese hamster lung fibroblasts).

  14. Evaluation of DNA damage induced by norcantharidin in human cultured lymphocytes.

    Science.gov (United States)

    Khabour, Omar F; Enaya, Fatima M; Alzoubi, Karem; Al-Azzam, Sayer I

    2016-07-01

    Norcantharidin (NCTD) is currently used in the treatment of several cancers such as leukemia, melanoma and hepatoma. The mechanism of action of NCTD is suggested to involve induction of apoptosis of cancer cells via production of reactive oxygen species. In this study, the genotoxic effect of different concentrations of NCTD (1, 10 and 20 μm) in human lymphocytes was investigated using sister chromatid exchanges (SCEs) and chromosomal aberrations (CAs) assays. The results revealed that NCTD significantly increased the rate of SCEs (p  0.05). In addition, no significant differences were detected in the mitotic index or proliferative index at examined doses (up to 20 μm). In conclusion, NCTD is genotoxic to human cultured lymphocytes as measured by SCE assay. PMID:26599593

  15. No evidence for chromosome damage in psoriasis patients treated with psoralen and long-wave ultraviolet light

    International Nuclear Information System (INIS)

    Five psoriasis patients treated with 8-methoxypsoralen and UVA (PUVA) were studied by lymphocyte cultures at the 1st, 5th, 10th and 20th treatment and at a maintenance treatment 6 months later. Abnormal amounts of chromosome aberrations were not found, and the frequency of sister chromatid exchange (examined at the last treatment) was not increased. In vitro experiments with nanogram doses of psoralen (similar to plasma levels in patients) showed no increase in chromosome aberration or SCE frequency. The results may indicate that therapeutic doses of PUVA have no clastogenic effect, but other explanations are possible: a sufficient number of exposed cells were not present in the blood sample; the PUVA damage was eliminated by repair or cell death; or the damage was lost because the cells were harvested at 68 hours. (author)

  16. Somatic cell chromosome changes in a population exposed to low levels of ionizing radiation

    International Nuclear Information System (INIS)

    The analysis of chromosomes from the cells of 897 plutonium workers is reported. Within three years, the number of controls alone analyzed for this study approximated the largest plutonium cytogenetic studies today including workers plus controls (81 compared to 84 in a 1979 French study and 94 in a 1982 British report). The number of subjects analyzed in the first three years were: new employees - 245; new employees assigned to plutonium work areas - 7; workers with less than 3% of maximum permissible systemic burden (MPSB) - 35; workers with less than 50% MPSB - 274; workers with greater than 50% of MPSB - 65; follow-up familial congenital cytogenetics at worker request (through Medical) - 6; polymorphic/variant chromosome constitutions - 242; re-sampling of workers with elevated aberration yields - 26; cell sample study - 28; sister-chromatid-exchange (SCE) study - 23; beryllium workers at Rocky Flats - 10; Hanford worker analyses - 5). 20 refs., 3 figs., 5 tabs

  17. 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.

  18. Temperature dependence of exchange field in exchange-spring magnets

    International Nuclear Information System (INIS)

    Pr8Fe88B4 ribbons prepared by melt spinning have been investigated by x-ray diffraction, differential thermal analysis, thermomagnetic analysis, atom force microscopy, and superconducting quantum interface device magnetometer. The results show that the annealed ribbons consist of the Pr2Fe14B and α-Fe phases. The magnetization of soft α-Fe phase remains parallel to the magnetization of the hard Pr2Fe14B phase for fields less than the exchange field (Hex). The exchange field in exchange-spring magnets, determined from the demagnetization curves measured at various temperatures, increases with decreasing grain size and measure temperature. The temperature dependence of exchange field was analyzed qualitatively by the expression Hex=(AK)1/2/(Mst). [copyright] 2001 American Institute of Physics

  19. HEAT EXCHANGERS IN SEWAGE PIPES

    OpenAIRE

    Podobeková, Veronika; Peráčková, Jana

    2014-01-01

    The article discusses utilization of heat from waste water in sewage. During the year, temperature of water in sewage ranges between 10 °C and 20 °C and the heat from sewage could be used for heating, cooling and hot water preparation in building. The heat is extracted through a transfer surface area of the heat exchanger into the heat pump, which is able to utilize the low–potential energy. Different design and types of the heat exchangers in sewage are dealt with: heat exchangers embedded i...

  20. 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...

  1. Mass exchange processes with input

    International Nuclear Information System (INIS)

    We investigate a system of interacting clusters evolving through mass exchange and supplemented by input of small clusters. Three possibilities depending on the rate of exchange generically occur when input is homogeneous: continuous growth, gelation, and instantaneous gelation. We mostly study the growth regime using scaling methods. An exchange process with reaction rates equal to the product of reactant masses admits an exact solution which allows us to justify the validity of scaling approaches in this special case. We also investigate exchange processes with a localized input. We show that if the diffusion coefficients are mass-independent, the cluster mass distribution becomes stationary and develops an algebraic tail far away from the source. (paper)

  2. 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.

  3. Compact heat exchangers modeling: Condensation

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Cascales, J.R.; Vera-Garcia, F. [Technical University of Cartagena, Thermal and Fluid Engineering Department, C/Dr. Fleming, s/n 30202 Cartagena, Murcia (Spain); Gonzalvez-Macia, J.; Corberan-Salvador, J.M. [Technical University of Valencia, Applied Thermodynamic Department, Valencia (Spain); Johnson, M.W.; Kohler, G.T. [Modine Manufacturing Company, Commercial Products Group, Racine, WI (United States)

    2010-01-15

    A model for the analysis of compact heat exchangers working as either evaporators or condensers is presented. This paper will focus exclusively on condensation modeling. The model is based on cell discretization of the heat exchanger in such a way that cells are analyzed following the path imposed by the refrigerant flowing through the tubes. It has been implemented in a robust code developed for assisting with the design of compact heat exchangers and refrigeration systems. These heat exchangers consist of serpentine fins that are brazed to multi-port tubes with internal microchannels. This paper also investigates a number of correlations used for the calculation of the refrigerant side heat transfer coefficient. They are evaluated comparing the predicted data with the experimental data. The working fluids used in the experiments are R134a and R410A, and the secondary fluid is air. The experimental facility is briefly described and some conclusions are finally drawn. (author)

  4. Production, safety, exchange, and risk

    OpenAIRE

    Hausken, Kjell

    2011-01-01

    Two agents convert resources into safety investment and production while exchanging goods voluntarily. Safety investment ensures reduction of costly risk. High unit cost of safety effort reduces both productive effort and safety effort, which reduces income.

  5. Definition of Magnetic Exchange Length

    Energy Technology Data Exchange (ETDEWEB)

    Abo, GS; Hong, YK; Park, J; Lee, J; Lee, W; Choi, BC

    2013-08-01

    The magnetostatic exchange length is an important parameter in magnetics as it measures the relative strength of exchange and self-magnetostatic energies. Its use can be found in areas of magnetics including micromagnetics, soft and hard magnetic materials, and information storage. The exchange length is of primary importance because it governs the width of the transition between magnetic domains. Unfortunately, there is some confusion in the literature between the magnetostatic exchange length and a similar distance concerning magnetization reversal mechanisms in particles known as the characteristic length. This confusion is aggravated by the common usage of two different systems of units, SI and cgs. This paper attempts to clarify the situation and recommends equations in both systems of units.

  6. 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...

  7. 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...

  8. Genotoxicity assessment in patients with thalassemia minor.

    Science.gov (United States)

    Al-Sweedan, Suleimman A; Khabour, Omar; Isam, Ruba

    2012-05-15

    Thalassemia is an inherited blood disorder that affects both genders and results in reduced synthesis of hemoglobin, and thus causing anemia. Previous studies have shown that the severe form of this disease, thalassemia major, is associated with genotoxicity. This includes increases in the level of sister chromatid exchange (SCEs), chromosomal aberrations (CAs) and micronuclei. In this study, we assessed genotoxicity in the lymphocytes of thalassemia minor subjects using sister chromatid exchange (SCE) and chromosomal aberration (CA) assays. In addition, we investigated the level of oxidative DNA damage by measuring 8-hydroxy-2'-deoxyguanosine (8OHdG) biomarker in urine samples. Eighteen thalassemia minor subjects and eighteen matched normal healthy controls were volunteered in the study. In addition, seven thalassemia major patients were recruited as positive controls. The results showed increases in the frequency of SCEs (P0.05). Both SECs and CAs in thalassemia major patients were significantly higher compared to other groups (P0.05). In conclusion, our results showed that thalassemia minor is associated with genotoxicity to blood lymphocytes as indicated by SCEs assay. PMID:22414564

  9. Organometallic cation-exchanged phyllosilicates

    OpenAIRE

    Fleming, Shay

    1991-01-01

    Organotin (IV) complexes formed between 0 01 M dimethyltin dichloride solutions prepared at pH 2 6 and 4 0, and trimethyltin chloride prepared at pH 3 4, with Na- 119 montmori 1lonite clay have been characterised using Sn Mflssbauer spectroscopy, X-ray diffraction, thermogravimetric analysis and water sorption isotherms Following cation exchange, Mttssbauer spectroscopy identified two tin species in the dimethyltin (IV)-exchanged clay prepared at pH 2 6 A cis specie...

  10. Exchange rate determination in Vietnam

    OpenAIRE

    Thai-Ha Le

    2015-01-01

    This study investigates the determinants of the exchange rate in Vietnam and suggests policy implications. Gregory-Hansen cointegration tests and generalised variance decomposition (VDC) analysis were applied to monthly data from July 2004 to December 2013. The model was built based on the three popular approaches to exchange rate determination, which are purchasing power parity (PPP) approach, balance of payment (BOP) approach, and monetary and portfolio approach. This study finds that the p...

  11. On learning by exchanging advice

    OpenAIRE

    Eugénio da Costa Oliveira; Luís Nunes

    2003-01-01

    One of the main questions concerning learning in Multi-Agent Systems is: (How) can agents benefit from mutual interaction during the learning process?. This paper describes the study of an interactive advice-exchange mechanism as a possible way to improve agents' learning performance. The advice-exchange technique, discussed here, uses supervised learning (backpropagation), where reinforcement is not directly coming from the environment but is based on advice given by peers with better perfor...

  12. Risk, Uncertainty and Exchange Rates

    OpenAIRE

    Hodrick, Robert J

    1987-01-01

    This paper explores a new direction for empirical models of exchange rate determination. The motivation arises from two well documented facts, the failure of log-linear empirical exchange rate models of the 1970's and the variability of risk premiums in the forward market. Rational maximizing models of economic behavior imply that changes in the conditional variances of exogenous processes, such as future monetary policies, future government spending, and future rates of income growth, can ha...

  13. Gift Exchange in the Workplace

    OpenAIRE

    Dur, Robert

    2008-01-01

    textabstractWe develop a model of manager-employee relationships where employees care more for their manager when they are more convinced that their manager cares for them. Managers can signal their altruistic feelings towards their employees in two ways: by offering a generous wage and by giving attention. Contrary to the traditional gift-exchange hypothesis, we show that altruistic managers may offer lower wages and nevertheless build up better social-exchange relationships with their emplo...

  14. External evaluation of Innovation Exchange.

    OpenAIRE

    Lyon, Fergus

    2010-01-01

    From recruiters to estate agents to bankers,brokerage is big business. Within the private sector, innovation brokerage — bringing people together to innovate — is well developed. But what is the power of brokerage to drive social innovation and support much needed social change? These questions are at the heart of Innovation Exchange. Innovation Exchange is a pilot programme primarily funded by the Office of the Third Sector in the Cabinet Office. In its work to 31 March 2010, the Excha...

  15. 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....

  16. Knowledge Exchange, Matching, and Agglomeration

    OpenAIRE

    Marcus Berliant; Robert R. Reed III; Ping Wang

    2000-01-01

    Despite wide recognition of their significant role in explaining sustained growth and economic development, uncompensated knowledge spillovers have not yet been fully modeled with a microeconomic foundation. This paper illustrates the exchange of knowledge as well as its consequences for agglomerative activity in a general-equilibrium search-theoretic framework. Agents, possessing differentiated types of knowledge, search for partners to exchange ideas in order to improve production efficacy....

  17. Tritium Exchange in Biological Systems

    International Nuclear Information System (INIS)

    Whenever tritium-labelled water is employed as a test solute or tracer in biological systems, an appreciable exchange between tritium and labile hydrogen atoms occurs that frequently affects the nature and interpretation of experimental results. The studies reported here are concerned with the magnitude of the effect that tritium exchange introduces into measurements of total body water and water metabolism in animals and humans. Direct measurements of exchange were made in rats, guinea pigs, pigeons, and rabbits. Tritium-labelled water was administered intravenously or by mouth, and tritium space and turnover determined from the concentration of tritium in blood. The animals were then desiccated to constant weight in vacuo. The specific activity of water collected periodically during desiccation increased by 50% as a result of isotope effects. Water from combustion of dried rabbit tissues contained about 2% of the tritium originally given to the animal. Adipose tissue alone contained little or no exchange tritium. The dried tissues of the other animals were rehydrated with inactive water and the appearance of tritium in the water observed. The specific activity of the water increased in exponential fashion, i.e., 1-exp. (kt), with about 90% of exchange occurring with a half-time of 1 h, and the remaining 10% with a half-time of 10 h. The total tritium extracted accounted for 1.5 to 3.5% of the dose given to the animal, which agrees with the difference between the tritium space and total body water determined by desiccation. An indirect estimate of exchange in humans was derived from concurrent measurements of tritium and antipyrene spaces. The average difference of about 2% in water volume agrees with the direct estimates of exchanges in animals. It is evident that tritium space should be reduced by about 2% to identify it with total body water. The magnitude and relatively slow rate of exchange may also influence the interpretation of metabolic studies with

  18. Exchange Rate Regimes and Location

    OpenAIRE

    Ricci, Luca Antonio

    1997-01-01

    This paper investigates the effects of fixed versus flexible exchange rate regimes on location choices of firms and on the degree of specialization of countries. In a two-country two-differentiated-good monetary model, demand, supply, and monetary shocks arise after wages are set and prices are optimally chosen. The exchange rate performs then an adjustment role for firms located in the country relatively specialized in the good they produce, but it constitutes a factor of disturbance for the...

  19. Persistent, Nonfundamental Exchange Rate Fluctuations

    OpenAIRE

    Irasema Alonso

    2004-01-01

    A trading-post model of money is used to show how exchange rates can be affected by extrinsic uncertainty. With no uncertainty in fundamentals, we demonstrate that there exist equilibria where exchange rates as well as consumption allocations follow a stationary random process. The uctuations are permanent, and they affect economic welfare. These findings also apply when the currency supplies grow at different rates. Then, the only stationary equilibria in which both monies are valued are tho...

  20. A critical view to explanations for the maximal value of 50 % of genetic recombination Críticas a las explicaciones del máximo de 50 % de recombinación genética

    Directory of Open Access Journals (Sweden)

    CARLOS Y VALENZUELA

    2001-03-01

    Full Text Available The maximal value of 50 % of genetic recombination (RF = recombination fraction between two linked gene loci has been explained by two models: (i the restriction of crossovers to only two of the four chromatids of a tetrad (tetrad model; (ii the limit of the occurrence of an odd number of crossovers between two loci, when the expected number of crossovers tends to infinite (odd-even model. This article shows that (i is wrong. If tetrads were responsible for the maximal 50 % RF, sister chromatid exchanges (SCE should display a maximal 100 % RF. In mammalian CHO cells we found that SCE yield a maximal 50 % recombination. Also, we demonstrated that the maximal 50 % RF for tetrads occurs because the sum of odd order coefficients in the binomial distribution is equal to the sum of even order coefficients. At the end of meiosis the two chromatids of a chromosome that receives K crossovers are separated. Then K breaks should distribute into two chromatids. Thus, the expected number of breaks per chromatid distributes, when K is large, in 50 % of chromatids having an even number of breaks (RF = 0 and 50 % having an odd number (RF = 1, irrespective of tetrads, hexads, octads or more complex meiotic chromosome configurationsEl máximo de 50 % de recombinación genética (RF entre dos loci ligados ha sido explicado por dos modelos. (i la restricción de los entrecruzamientos a dos de las cuatro cromátidas de una tétrada (modelo de tétrada; (ii el límite de la ocurrencia de un número impar de entrecruzamientos entre los dos loci, cuando el número esperado de entrecruzamientos tiende a infinito (modelo par-impar. Este artículo muestra que (i es erróneo, ya que, si la tétrada fuera responsable del máximo de 50 % de RF, el intercambio de cromátidas hermanas (SCE debería alcazar el 100 % de recombinación y esto no se da en células CHO, en las que encontramos un máximo de 50 %. Además, demostramos que el máximo de 50 % RF para las t

  1. Inhibition of repair activity induced by γ-radiation, UV-rays and radiomimetics in the in vitro cultured cells of patients wiyh schizophrenia

    International Nuclear Information System (INIS)

    A study was made of the processes of repair, virus reactivation, and formation of sister chromatid exchages (SCE) in blood cells of patients with schizophrenia after the effect of γ-radiation and 4-nitroquinoline-1-oxide. These processes were estimated by 12 criteria. The mutagen-induced disturbances in the processes of repair and SCE formation were found in cells of patients with schizophrenia and were absent in the control cells of healthy donors

  2. Implications of S-phase exchanges for the mechanisms of radiosensitivity in trisomy 21

    International Nuclear Information System (INIS)

    Human lymphocytes obtained from four patients with Down syndrome and from two normal individuals were irradiated with X-rays during their S phase and examined for chromatid type aberrations. It is suggested that the significantly increased frequency of asymmetrical chromatid interchanges found in trisomic cells is related to an altered DNA repair system. This altered repair system is probably responsible for the increased frequency of chromosome aberrations that can be induced in these cells by x-rays and the increased tendency for leukemia observed in Down syndrome as well

  3. Conflict and Fairness in Social Exchange

    Science.gov (United States)

    Molm, Linda D.; Collett, Jessica L.; Schaefer, David R.

    2006-01-01

    Inherent to all social exchange relations are elements of both cooperation and competition. We develop and test a theoretical model which proposes that the relative salience of the competitive, conflictual elements of exchange mediate and explain the negative effects of negotiated exchange, as compared with reciprocal exchange, on actors'…

  4. 76 FR 56094 - Retail Foreign Exchange Transactions

    Science.gov (United States)

    2011-09-12

    .... Regulation of Off-Exchange Retail Foreign Exchange Transactions and Intermediaries, 75 FR 3281 (Jan. 20, 2010). \\13\\ Retail Foreign Exchange Transactions, 76 FR 22633 (Apr. 22, 2011). \\14\\ Id. \\15\\ Retail Foreign... proposed and final rules. \\16\\ Retail Foreign Exchange Transactions, 76 FR 22633 (Apr. 22, 2011)....

  5. 77 FR 62177 - Retail Foreign Exchange Transactions

    Science.gov (United States)

    2012-10-12

    ...\\ Retail Foreign Exchange Transactions, 76 FR 41375 (July 14, 2011). \\10\\ Retail Foreign Exchange...). \\53\\ Compare 12 CFR 48.3(b) with Retail Foreign Exchange Transactions, 76 FR 41375, 41377 (July 14... this NPR. \\55\\ Retail Foreign Exchange Transactions, 76 FR 56094 (Sept. 12, 2011). III. Request...

  6. 76 FR 22633 - Retail Foreign Exchange Transactions

    Science.gov (United States)

    2011-04-22

    ... delivery in connection with its line of business.\\20\\ In addition, the definition does not include... of Off-Exchange Retail Foreign Exchange Transactions and Intermediaries, 75 FR 55409 (Sept. 10, 2010... Act. Regulation of Off-Exchange Retail Foreign Exchange Transactions and Intermediaries, 75 FR...

  7. 78 FR 42439 - Retail Foreign Exchange Transactions

    Science.gov (United States)

    2013-07-16

    ... Broker-Dealers for Certain Forex Transactions, Exchange Act Release No. 61090 (Dec. 1, 2009), 74 FR 64776...''). \\2\\ See Investor Bulletin: Foreign Currency Exchange (Forex) Trading for Individual Investors (July... Retail Foreign Exchange Transactions, Exchange Act Release No. 64874 (July 13, 2011), 76 FR 41676...

  8. Ion exchange behaviour of polymeric zirconium cations

    International Nuclear Information System (INIS)

    Polymeric zirconium cations formed in weakly acid solutions (pH2) are taken up strongly into macroporous cation exchange resins, while uptake into normal cation exchange resins (pore diameter about 1 nm) is low. Macroporous cation exchange resins loaded with polymeric Zr cations are shown to function as ligand exchange sorbents. (Authors)

  9. Building Cohesion in Positively Connected Exchange Networks

    Science.gov (United States)

    Schaefer, David R.; Kornienko, Olga

    2009-01-01

    This research investigates the process through which individuals build cohesive relationships in positively connected exchange relations. Positive connections exist any time exchange in one relation must precede exchange in another. Such situations arise through gatekeeping, in generalized exchange contexts, and when resources diffuse across a…

  10. Listening to agent agendas in student exchanges

    DEFF Research Database (Denmark)

    Tarp, Gertrud

    2003-01-01

    The paper is based upon a research study of short-term student exchanges. The study took place from 1996-2000, and comprises seven classes of students from six Danish business schools. Short-term student exchanges in terms of EU funded exchanges and local school exchanges are means to develop the...

  11. A Colorful Ion Exchange Experiment

    Science.gov (United States)

    Mendes, Adélio

    1999-11-01

    A colorful ion-exchange experiment is described. The use of a resin with an adsorbed acid-base indicator allows students to follow the progress of the ion-exchange front along the column. In parallel, students can follow the ion-exchange breakthrough curve using a continuous conductometric cell at the column outlet. In the present example, K+ (KCl) exchanges with H+ (HCl) in a strong cationic resin (Amberlite IR 120). The adsorbed indicator is methyl violet. Sorption equilibrium is favorable to the K+ ions. Monovalent ions, used in this experiment, have the disadvantage of usually being colorless (except perhaps permanganate, but this is an extremely strong oxidant which attacks the resin). On the other hand, many divalent ions are colorful but the shape of the concentration front is hard to explain qualitatively as well as quantitatively. That is because the shape of the front depends on the total ionic concentration. However, color can be introduced in a monovalent ion-exchange system by adding an appropriate acid-base indicator to the resin. The text describes this experiment qualitatively. A simplified quantitative description, using the solute movement theory, can be found online.

  12. 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.

  13. 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...

  14. Expenditure Switching and Exchange Rate Policy

    OpenAIRE

    Charles Engel

    2002-01-01

    Nominal exchange rate changes can lead to 'expenditure switching' when they change relative international prices. A traditional argument for flexible nominal exchange rates posits that when prices are sticky in producers' currencies, nominal exchange rate movements can change relative prices between home and foreign goods. But if prices are fixed ex ante in consumers' currencies, nominal exchange rate flexibility cannot achieve any relative price adjustment. In that case nominal exchange rate...

  15. A Theory of Financial Exchange Organization.

    OpenAIRE

    Pirrong, Craig

    2000-01-01

    Although there has been extensive research on the economic functions of financial exchanges and the properties of prices determined on exchanges, there has been little research on their organization and governance. The heterogeneity of the suppliers of financial services who are members of financial exchanges explains salient features of exchange organization. When suppliers of financial services are heterogeneous, one expects to observe exchanges organized as not-for-profit firms, especially...

  16. OPTIMASI KINERJA HEAT EXCHANGER TABUNG KOSENTRIS

    OpenAIRE

    Didik Wahjudi

    2000-01-01

    Heat exchanger effectiveness is affected by some factors such as pipe shape, temperature, cold and hot air direction and velocity entering the heat exchanger. Research about heat exchanger has been done but the significance level of the heat exchanger effectiveness resulted is unknown. A designed experiment should be done to optimize the performance of concentric tube heat exchanger with measured significance level. From the analysis of result of previous experiment, factors that seem to affe...

  17. Adaptive predictive control of laboratory heat exchanger

    OpenAIRE

    Bobál, Vladimír; Kubalčík, Marek; Dostál, Petr; Novák, Jakub

    2014-01-01

    Heat exchange belongs to the class of basic thermal processes which occur in a range of industrial technologies, particularly in the energetic, chemical, polymer and rubber industry. The process of heat exchange is often implemented by through-flow heat exchangers. It is apparent that for an exact theoretical description of dynamics of heat exchange processes it is necessary to use partial differential equations. Heat exchange is namely a process with distributed parameters. It is also necess...

  18. Clearing Barter Exchange Markets: Kidney Exchange and Beyond

    NARCIS (Netherlands)

    K.M. Glorie (Kristiaan)

    2014-01-01

    markdownabstract__Abstract__ Advanced computer assisted markets, otherwise known as smart markets, are becoming an important part of our modern society. This dissertation considers smart barter exchange markets, which enable people to trade a wide range of goods: from shifts, to houses, to kidneys.

  19. Heat exchanger fouling and corrosion

    International Nuclear Information System (INIS)

    Fouling of heat transfer surfaces introduces perhaps the major uncertainty into the design and operation of heat exchange equipment. After a brief description of the various types of fouling the chapter goes on to review the current theories of fouling including the turbulent burst theory. Fouling in equipment involving boiling and evaporation is often more severe than in single phase heat exchangers and moreover, in aqueous systems, is frequently associated with corrosion. The reasons for this are identified and illustrated by reference to corrosion in nuclear power plant steam generators. Finally the modification of heat transfer and pressure drop characteristics by fouling layers is briefly reviewed

  20. Complete Convergence of Exchangeable Sequences

    Directory of Open Access Journals (Sweden)

    George Stoica

    2011-01-01

    Full Text Available We prove that exchangeable sequences converge completely in the Baum-Katz sense under the same conditions as i.i.d. sequences do. Problem statement: The research was needed as the rate of convergence in the law of large numbers for exchangeable sequences was previously obtained under restricted hypotheses. Approach: We applied powerful techniques involving inequalities for independent sequences of random variables. Results: We obtained the maximal rate of convergence and provided an example to show that our findings are sharp. Conclusion/Recommendations: The technique used in the paper may be adapted in the similar study for identically distributed sequences.

  1. Exchange of Parametric CAD Models

    Institute of Scientific and Technical Information of China (English)

    JIANG Hua; PRATT J Michael; SRIRAM D Ram

    2006-01-01

    A method to exchange digital CAD model construction history data using ISO10303 is presented. The primary intention of this research is to demonstrate the utility of ISO10303-108 in achieving parametric CAD model exchange between commercial CAD systems. ISO10303-108, still under development, has been used to represent geometric and dimensional constraints on the sketch profile. Schemas from Parts 42, 50 of ISO 10303 are also used. ISO10303-42 is adopted to represent geometric and topological information and ISO10303-50 is used to represent the mathematical expression.

  2. 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

  3. Monetary Exchange with Multilateral Matching

    DEFF Research Database (Denmark)

    Julien, Benoît; Kennes, John; King, Ian

    This paper analyzes monetary exchange in a search model allowing for multilateral matches to be formed, according to a standard urn-ballprocess. We consider three physical environments: indivisible goods and money, divisible goods and indivisible money, and divisible goods and money. We compare the...

  4. 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...

  5. Commodity exchanges - Function and operation

    International Nuclear Information System (INIS)

    The author discusses the potential impacts that a futures market may have on the international trade of uranium. The discussion first centers around the New York Mercantile Exchange. The following market aspects are discussed: long-term contracting; spot market; commoditization and pricing; and advantages, disadvantages, risks, and provisions of futures market contracts

  6. Exchange interactions in barium hexaferrite

    Czech Academy of Sciences Publication Activity Database

    Novák, Pavel; Rusz, J.

    2005-01-01

    Roč. 71, č. 18 (2005), 184433/1-184433/6. ISSN 1098-0121 R&D Projects: GA AV ČR(CZ) IAA1010214 Institutional research plan: CEZ:AV0Z10100521 Keywords : hexaferrites * exchange interaction * density functional theory Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.185, year: 2005

  7. Primer on nuclear exchange models

    Energy Technology Data Exchange (ETDEWEB)

    Hafemeister, David [Physics Department, Cal Poly University, San Luis Obispo, California (United States)

    2014-05-09

    Basic physics is applied to nuclear force exchange models between two nations. Ultimately, this scenario approach can be used to try and answer the age old question of 'how much is enough?' This work is based on Chapter 2 of Physics of Societal Issues: Calculations on National Security, Environment and Energy (Springer, 2007 and 2014)

  8. 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,…

  9. SPEEDUPtrademark ion exchange column model

    International Nuclear Information System (INIS)

    A transient model to describe the process of loading a solute onto the granular fixed bed in an ion exchange (IX) column has been developed using the SpeedUptrademark software package. SpeedUp offers the advantage of smooth integration into other existing SpeedUp flowsheet models. The mathematical algorithm of a porous particle diffusion model was adopted to account for convection, axial dispersion, film mass transfer, and pore diffusion. The method of orthogonal collocation on finite elements was employed to solve the governing transport equations. The model allows the use of a non-linear Langmuir isotherm based on an effective binary ionic exchange process. The SpeedUp column model was tested by comparing to the analytical solutions of three transport problems from the ion exchange literature. In addition, a sample calculation of a train of three crystalline silicotitanate (CST) IX columns in series was made using both the SpeedUp model and Purdue University's VERSE-LC code. All test cases showed excellent agreement between the SpeedUp model results and the test data. The model can be readily used for SuperLigtrademark ion exchange resins, once the experimental data are complete

  10. Heat exchanger staybolt acceptance criteria

    International Nuclear Information System (INIS)

    The structural integrity demonstration of the primary coolant piping system includes evaluating the structural capacity of each component against a large break or equivalent Double-Ended Guillotine Break. A large break at the inlet or outlet heads of the heat exchangers would occur if the restraint members of the heads become inactive. The structural integrity of the heads is demonstrated by showing the redundant capacity of the staybolts to restrain the head at design conditions and under seismic loadings. The Savannah River Site heat exchanger head is attached to the tubesheet by 84 staybolts. Access to the staybolts is limited due to a welded seal cap over the staybolts. An ultrasonic testing (UT) inspection technique to provide an in-situ examination of the staybolts has recently been developed at SRS. Examination of the staybolts will be performed to ensure their service condition and configuration is within acceptance limits. An acceptance criteria methodology has been developed to disposition flaws reported in the staybolt inspections while ensuring adequate restraint capacity of the staybolts to maintain integrity of the heat exchanger heads against collapse. The methodology includes an approach for the baseline and periodic inspections of the staybolts. The heat exchanger head is analyzed with a three-dimensional finite element model. The restraint provided by the staybolts is evaluated for several postulated cases of inactive or missing staybolts. Evaluation of specific, inactive staybolt configurations based on the UT results can be performed with the finite element model and fracture methodology in this report

  11. SPECTRAL ANALYSIS OF EXCHANGE RATES

    Directory of Open Access Journals (Sweden)

    ALEŠA LOTRIČ DOLINAR

    2013-06-01

    Full Text Available Using spectral analysis is very common in technical areas but rather unusual in economics and finance, where ARIMA and GARCH modeling are much more in use. To show that spectral analysis can be useful in determining hidden periodic components for high-frequency finance data as well, we use the example of foreign exchange rates

  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. Foreign Exchange Reserves: Bangladesh Perspective

    Directory of Open Access Journals (Sweden)

    Md Zahangir Alam

    2013-10-01

    Full Text Available This study is about foreign exchangereserves of Bangladesh. The mainpurpose of this study is to the influence of exchange rates on foreign exchangereserves to the Bangladesh context.  Both the primary and secondary data has been used inthis study. The primary data has been collected through a structuredquestionnaire from 50 respondents. The secondary data, namely Bangladeshforeign exchange reserves (FER, Bangladesh current account balance (CAB,Bangladesh capital andfinancial account balance (CFAB, and BDT/USD exchange rates (ER.  This study covers yearly data from July 01,1996 to June 30, 2005 and quarterly data from July 01, 2005 to June 30, 2012. Findingsof this study shows that out of the selected 16 factors affecting foreignexchange reserves, exchange rates occupy the first position, weighted averagescore (WAS being 4.56. Foreign exchange reserves (FER and current accountbalance (CAB have increased by 502.9087% and 1451.218%,whereas capital and financial account (CFAB has decreased by -649.024% on June30, 2012 compared to June 30, 1997. The influence of other factors heldconstant, as ER changes by 285.6894 units due to one unit change in FER, onaverage in the same direction which represents that ER has positive effect on theFER and this relationship is statistically significant.  62.1526 percentof the variation in FER is explained by ER. The outcomes of Breusch-Godfrey test (LM test, ARCHtest, and the Normality test are that there is a serial correlation among residuals, the variance of residuals is notconstant, and the residuals are not normally distributed.

  14. PARP Inhibitors in Clinical Use Induce Genomic Instability in Normal Human Cells

    Science.gov (United States)

    Ito, Shuhei; Murphy, Conleth G.; Doubrovina, Ekaterina; Jasin, Maria; Moynahan, Mary Ellen

    2016-01-01

    Poly(ADP-ribose) polymerases (PARPs) are the first proteins involved in cellular DNA repair pathways to be targeted by specific inhibitors for clinical benefit. Tumors harboring genetic defects in homologous recombination (HR), a DNA double-strand break (DSB) repair pathway, are hypersensitive to PARP inhibitors (PARPi). Early phase clinical trials with PARPi have been promising in patients with advanced BRCA1 or BRCA2-associated breast, ovary and prostate cancer and have led to limited approval for treatment of BRCA-deficient ovary cancer. Unlike HR-defective cells, HR-proficient cells manifest very low cytotoxicity when exposed to PARPi, although they mount a DNA damage response. However, the genotoxic effects on normal human cells when agents including PARPi disturb proficient cellular repair processes have not been substantially investigated. We quantified cytogenetic alterations of human cells, including primary lymphoid cells and non-tumorigenic and tumorigenic epithelial cell lines, exposed to PARPi at clinically relevant doses by both sister chromatid exchange (SCE) assays and chromosome spreading. As expected, both olaparib and veliparib effectively inhibited poly-ADP-ribosylation (PAR), and caused marked hypersensitivity in HR-deficient cells. Significant dose-dependent increases in SCEs were observed in normal and non-tumorigenic cells with minimal residual PAR activity. Clinically relevant doses of the FDA-approved olaparib led to a marked increase of SCEs (5-10-fold) and chromatid aberrations (2-6-fold). Furthermore, olaparib potentiated SCE induction by cisplatin in normal human cells. Our data have important implications for therapies with regard to sustained genotoxicity to normal cells. Genomic instability arising from PARPi warrants consideration, especially if these agents will be used in people with early stage cancers, in prevention strategies or for non-oncologic indications. PMID:27428646

  15. Exchange Reactions. Proceedings of the Symposium on Exchange Reactions

    International Nuclear Information System (INIS)

    The mechanisms and kinetics of chemical reactions are of great interest to chemists. The study of exchange reactions in particular helps to shed light on the dynamics of chemical change, providing an insight into the structures and the reactivities of the chemical species involved. The main theme of this meeting was the subject of oxidation-reduction reactions in which the net result is the transfer of one or more electrons between the different oxidation states of the same element. Other studies reported included the transfer of protons, atoms, complex ligands or organic radicals between molecules. Heterogeneous exchange, which is of importance in many cases of catalytic action, was also considered. For a long time isotopic tracers have formed the most convenient means of studying exchange reactions and today a considerable amount of work continues to be done with their aid. Consequently, several papers presented at this Symposium reported on work carried out by purely radiochemical tracer methods. In recognition, however, of the important role which nuclear magnetic resonance and electron spin resonance play in this field, in particular in the study of fast reactions, a number of reports on investigations in which these techniques had been used was included in the programme. By kind invitation of the United States Government the Symposium on Exchange Reactions was held from 31 May to 4 June at the Brookhaven National Laboratory, Upton, Long Island, N.Y., USA. It was attended by 46 participants from nine countries and one inter-governmental organization. The publication of these Proceedings makes the contents of the papers and the discussion available to a wider audience

  16. Clearing Barter Exchange Markets: Kidney Exchange and Beyond

    OpenAIRE

    Glorie, Kristiaan

    2014-01-01

    markdownabstract__Abstract__ Advanced computer assisted markets, otherwise known as smart markets, are becoming an important part of our modern society. This dissertation considers smart barter exchange markets, which enable people to trade a wide range of goods: from shifts, to houses, to kidneys. Centralized and computerized clearing is what makes these markets ‘smart’. The market clearing problem is to match demand and supply so as to maximize the gains of trade. Trades, in this regard, ne...

  17. 75 FR 34186 - Self-Regulatory Organizations; BATS Exchange, Inc.; EDGA Exchange, Inc.; EDGX Exchange, Inc...

    Science.gov (United States)

    2010-06-16

    .... These rules would require the Listing Markets to issue five-minute trading pauses for individual..., noting that ``trading pauses may reduce market volatility resulting from temporary supply-demand...; New York Stock Exchange LLC; NYSE Amex LLC; NYSE Arca, Inc.; The NASDAQ Stock Market LLC;...

  18. Assessment of adaptability of zebu cattle ( Bos indicus) breeds in two different climatic conditions: using cytogenetic techniques on genome integrity

    Science.gov (United States)

    Kumar, Anil; Waiz, Syma Ashraf; Sridhar Goud, T.; Tonk, R. K.; Grewal, Anita; Singh, S. V.; Yadav, B. R.; Upadhyay, R. C.

    2016-06-01

    The aim of this study was to evaluate the genome integrity so as to assess the adaptability of three breeds of indigenous cattle reared under arid and semi-arid regions of Rajasthan (Bikaner) and Haryana (Karnal) India. The cattle were of homogenous group (same age and sex) of indigenous breeds viz. Sahiwal, Tharparkar and Kankrej. A total of 100 animals were selected for this study from both climatic conditions. The sister chromatid exchanges (SCE's), chromosomal gaps and chromatid breaks were observed in metaphase plates of chromosome preparations obtained from in vitro culture of peripheral blood lymphocytes. The mean number of breaks and gaps in Sahiwal and Tharparkar of semi-arid zone were 8.56 ± 3.16, 6.4 ± 3.39 and 8.72 ± 2.04, 3.52 ± 6.29, respectively. Similarly, the mean number of breaks and gaps in Tharparkar and Kankrej cattle of arid zone were 5.26 ± 1.76, 2.74 ± 1.76 and 5.24 ± 1.84, 2.5 ± 1.26, respectively. The frequency of SCEs in chromosomes was found significantly higher ( P 0.05) was observed in the same zone. The analysis of frequency of CAs and SCEs revealed significant effects of environmental conditions on the genome integrity of animals, thereby indicating an association with their adaptability.

  19. A preliminary cytogenetic and hematological study of photocopying machine operators

    Directory of Open Access Journals (Sweden)

    Gadhia P

    2005-01-01

    Full Text Available The incidences of chromosomal aberrations(CAs as well as sister chromatid exchange frequencies (SCEs was evaluated from 12 photocopying machine operators working on an average 8-9 hours per day for more than five years. A complete blood picture of each individual was assessed with an automatic particle cell counter. Additionally, blood pressure was measured at the time of blood collection from all photocopying machine operators. For comparison, the control group included another 12 individuals matched according to age, sex, socioeconomic conditions as well as other personal habits. The observations of the present study are indicators of health hazard for, although small, there was a significant increase in the percentage of aberrant cells (P<0.05, total aberrations (P<0.01 as well as total aberrations excluding chromatid gaps (P<0.01 among photocopying machine operators when compared to controls. However, results on SCE analysis of photocopying operators revealed no significant difference from the controls. At the same time all photocopying operators exhibited normal hematological parameters as well as blood pressure values.

  20. Assessment of adaptability of zebu cattle ( Bos indicus) breeds in two different climatic conditions: using cytogenetic techniques on genome integrity

    Science.gov (United States)

    Kumar, Anil; Waiz, Syma Ashraf; Sridhar Goud, T.; Tonk, R. K.; Grewal, Anita; Singh, S. V.; Yadav, B. R.; Upadhyay, R. C.

    2016-06-01

    The aim of this study was to evaluate the genome integrity so as to assess the adaptability of three breeds of indigenous cattle reared under arid and semi-arid regions of Rajasthan (Bikaner) and Haryana (Karnal) India. The cattle were of homogenous group (same age and sex) of indigenous breeds viz. Sahiwal, Tharparkar and Kankrej. A total of 100 animals were selected for this study from both climatic conditions. The sister chromatid exchanges (SCE's), chromosomal gaps and chromatid breaks were observed in metaphase plates of chromosome preparations obtained from in vitro culture of peripheral blood lymphocytes. The mean number of breaks and gaps in Sahiwal and Tharparkar of semi-arid zone were 8.56 ± 3.16, 6.4 ± 3.39 and 8.72 ± 2.04, 3.52 ± 6.29, respectively. Similarly, the mean number of breaks and gaps in Tharparkar and Kankrej cattle of arid zone were 5.26 ± 1.76, 2.74 ± 1.76 and 5.24 ± 1.84, 2.5 ± 1.26, respectively. The frequency of SCEs in chromosomes was found significantly higher ( P differences ( P different zones, i.e. arid and semi-arid, whereas no significant difference ( P > 0.05) was observed in the same zone. The analysis of frequency of CAs and SCEs revealed significant effects of environmental conditions on the genome integrity of animals, thereby indicating an association with their adaptability.

  1. Flexible Exchange of Farming Device Data

    DEFF Research Database (Denmark)

    Iftikhar, Nadeem; Pedersen, Torben Bach

    2011-01-01

    A new trend in the farming business is to replace conventional farming devices with computerized farming devices. Accordingly, numerous computer-based farming devices for logging, processing and exchanging data have recently been installed on moving farm machinery such as tractors. The exchange...... of data generally takes place between the devices and farming systems, mostly installed at the premises of farmers, contractors, advisory services etc. In most cases, data exchange is based on farming data exchange standards and is bi-directional. Bi-directional data exchange allows different devices...... and systems to exchange data based on a predefined set of rules. In consequence, many hand-coded data exchange solutions have been developed in the farming business. Although efforts regarding incorporating data exchange standards have been made, their actual usage so far has been limited, due to the fact...

  2. Exchange Faculty Perspectives on International Collaborations

    OpenAIRE

    McHale, Donal

    2006-01-01

    The main purpose of the paper is to document key issues in developing successful transatlantic faculty exchanges and to document perspectives and key learnings’ emanating from the development and implementation of an international exchange process.

  3. Fouling analyses for heat exchangers of NPP

    International Nuclear Information System (INIS)

    Fouling of heat exchanges is generated by water-borne deposits, commonly known as foulants including particulate matter from the air, migrated corrosion produces; silt, clays, and sand suspended in water; organic contaminants; and boron based deposits in plants. This fouling is known to interfere with normal flow characteristics and reduce thermal efficiencies of heat exchangers. In order to analyze the fouling for heat exchangers of nuclear power plant, the fouling factor is introduced based on the ASME O and M codes and TEMA standards. This paper focuses on the fouling analyses for the heat exchangers of several primary systems; the RHR heat exchanger of the residual heat removal system, the letdown heat exchanger of the chemical and volume control system, and the CCW heat exchanger of the component cooling water system, Based on the results of the fouling levels for the three heat exchangers are assumed

  4. A quantum exchange bias model

    International Nuclear Information System (INIS)

    The origin of the exchange bias phenomenon is investigated on the basis of a quantum mechanical model. In particular, the mechanisms that determine the magnetic structure in the vicinity of an antiferromagnetic-ferromagnetic interface are reexamined. This way we establish how the breaking of translational invariance modifies quantum spin fluctuations. It is found that non-uniform fluctuations induce uncompensated spins in the antiferromagnet, which in turn give rise to a dipole field that couples to the magnetization of the ferromagnet. This coupling yields an exchange bias field that is of the order of magnitude of the one observed experimentally. A net surface magnetization should also be experimentally observable in a clean antiferromagnetic surface

  5. Value Appropriation in Business Exchange

    DEFF Research Database (Denmark)

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

    2014-01-01

    authors propose four areas with high potential for future research into value appropriation: network position effects, appropriation acts and behaviors, buyer-seller relationship effects, and appropriation over time. Practical implications – Boundary spanning managers acting in industrial markets must......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...... some initial guidance for managers. Design/methodology/approach – Literatures investigating value appropriation were identified by the means of a systematic review of the overall management literature. Findings – The authors provide an overview and comparison of the literatures and find that they apply...

  6. Metabolic exchanges within tumor microenvironment.

    Science.gov (United States)

    Chiarugi, Paola; Cirri, Paolo

    2016-09-28

    Tumor progression toward malignancy often requires a metabolic rewiring of cancer cells to meet changes in metabolic demand to forefront nutrient and oxygen withdrawal, together with strong anabolic requests to match high proliferation rate. Tumor microenvironment highly contributes to metabolic rewiring of cancer cells, fostering complete nutrient exploitation, favoring OXPHOS of lipids and glutamine at the expense of glycolysis and enhancing exchanges via extracellular microvesicles or exosomes of proteins, lipids and small RNAs among tumor and stromal cells. Noteworthy, the same molecular drivers of metabolic reprogramming within tumor and stroma are also able to elicit motility, survival and self-renewal on cancer cells, thereby sustaining successful escaping strategies to circumvent the hostile hypoxic, acidic and inflammatory environment. This review highlights the emerging role of nutrients and vesicle-mediated exchanges among tumor and stromal cells, defining their molecular pathways and offering new perspectives to develop treatments targeting this complex metabolic rewiring. PMID:26546872

  7. Groundwater–Surface Water Exchange

    DEFF Research Database (Denmark)

    Karan, Sachin

    The exchange of groundwater-surface water has been invetigated in the western part of Denmark. Holtum AA provides the framework for all the performed investigations. Several methods are used, primarily eld based measurements ombined with numerical models to achieve insight to the governing...... processes of interaction between groundwater and surface water. By using heat as a tracer it has been possible to use temperature directly as calibrationtargets in a groundwater and heat transport model. Thus, it is possible to use heat investigate the change in groundwater discharge in dynamic conditions...... by using simple temperature devices along a stream to delineate the areas of interest in regard to GW{SW exchange. Thus, at several locations in a stream a temperature data logger was placed in the water column and right at the streambed-water interface. By looking at the correlation of streambed...

  8. Energy exchanges in reconnection outflows

    CERN Document Server

    Lapenta, Giovanni; Newman, Davd L; Markidis, Stefano

    2016-01-01

    Reconnection outflows are highly energetic directed flows that interact with the ambient plasma or with flows from other reconnection regions. Under these conditions the flow becomes highly unstable and chaotic, as any flow jets interacting with a medium. We report here massively parallel simulations of the two cases of interaction between outflow jets and between a single outflow with an ambient plasma. We find in both case the development of a chaotic magnetic field, subject to secondary reconnection events that further complicate the topology of the field lines. The focus of the present analysis is on the energy balance. We compute each energy channel (electromagnetic, bulk, thermal, for each species) and find where the most energy is exchanged and in what form. The main finding is that the largest energy exchange is not at the reconnection site proper but in the regions where the outflowing jets are destabilized.

  9. Spin Exchange in Rydberg EIT

    Science.gov (United States)

    Nicholson, Travis; Thompson, Jeff; Liang, Qiyu; Cantu, Sergio; Venkatramani, Aditya; Pohl, Thomas; Choi, Soonwon; Lukin, Mikhail; Vuletic, Vladan

    2016-05-01

    The realization of strong optical nonlinearities between two photons has been a longstanding goal in quantum science. We achieve large single-photon-level nonlinearities with Rydberg EIT, which combines slow light techniques with strongly interacting Rydberg states. For two Rydberg atoms in the same state, a Van der Waals interaction is the dominant coupling mechanism. Inherently stronger dipole-dipole interactions are also possible between atoms in different Rydberg states. Using light storage and microwave resonances, we study the effect of dipole-dipole interactions in Rydberg EIT. We observe a coherent spin exchange effect for pairs of states dominated by dipole-dipole interactions. Spin exchange manifests as an increase in optical transmission through a cold Rubidium gas that is highly dissipative in the presence of Van der Waals interactions. We also observe a controlled π / 2 phase shift due to this effect, which paves the way for robust, universal all-optical quantum gates.

  10. Ultraviolet-induced chromosomal instability in cultured fibroblasts of heterozygote carriers for xeroderma pigmentosum

    International Nuclear Information System (INIS)

    Fibroblast cultures of seven patients with xeroderma pigmentosum (XP), 19 healthy sibs or parents of XP patients (XP-heterozygotes), and 24 healthy normal controls were studied for chromosome instability induced by ultraviolet rays (UV). We used a UV source that contained predominantly UV-A and UV-B at an intensity of 500 J/m2 and evaluated the induction of micronuclei (MN) and sister chromatid exchange (SCE). the XP homozygotes had a UV sensitivity that was clearly above that of all heterozygotes and normal controls. Heterozygotes had an increased rate of UV-induced MN (4.76 ± 1.96 vs. 1.82 ± 2.05, p less than 0.0001) and increased UV induction of SCE (13.21 ± 3.49 vs. 9.01 ± 1.25, p less than 0.001), as compared to normal controls. These data support epidemiologic findings that suggest that XP heterozygotes are particularly cancer prone. In addition, the determination of the UV sensitivity in vitro as described may be used for genetic counseling of asymptomatic relatives of XP patients

  11. Cytogenetic changes induced by the different types of drinking water in one HCC high incidence area of P. R of China

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A lot of epidemiological survey on the kinds of risk factors caused by the high incidence of Hepatocellular carcinoma (HCC) in Fusui county,P. R. Of China has been done,especially on relation ship between the different types of drinking water and the mortality of HCC. But the mechanism is no clear. In our study,we sampled the common type of drinking water (pond water,shallow well water,tap water) in Fusui county and did series of cytogenetic determinations such as Chromosomal aberration (CA),Micronuclei (MN) and Sister chromatid exchange (SCE). The changes of CA,MN and SCE related to types of drinking water were observed. There were linear correlation between the concentration of water sample and these changes. The results suggests that one of the reason for the high incidence of HCC in Fusui county may be the presence of mutagen and/or carcinogen existed in the drinking water. The dissimilarity of the different types of drinking water is due to different concentrations of mutagens and/or carcinogens. In brief, the results confirmed the theory of type of drinking water corresponding to incidence rate of HCC proposed by Delong Su on cytogenetics

  12. Glycidamide genotoxicity modulated by Caspases genes polymorphisms.

    Science.gov (United States)

    de Lima, João Pereira; Silva, Susana N; Rueff, José; Pingarilho, Marta

    2016-08-01

    Acrylamide (AA) is amongst acknowledged carcinogenic dietary factors. Its DNA-reactive metabolite is glycidamide (GA). The present study intended to correlate the role of key polymorphic genes of apoptosis (CASP7, CASP8, CASP9, CASP10, LTA and TNFRSF1B) with biomarkers of effect of DNA damage, namely the sister chromatid exchange assay (SCE) and the comet assay in whole blood cells exposed to GA. The aim was to assess as a proof of concept the role that pro-apoptotic effector proteins might have in the yields of genotoxic effects when those effector proteins are coded by polymorphic genes. Whole blood from a small group of volunteers was exposed to GA to assess DNA damage and the volunteers were genotyped for polymorphic genes related to apoptosis pathways. A relation between the induction of SCE and several variants of the polymorphism CASP8 rs1035142 G>T was observed. Also, a relation between the % tail DNA and the CASP10 I522L polymorphism was found. Furthermore, associations between % tail DNA and several SNP-SNP interactions of CASP8 and CASP10 were found. A possible correlation between DNA damage and the genetic susceptibility, bestowed by polymorphic genes in the apoptosis inducing pathways was verified. PMID:27062911

  13. Molecular mechanisms of alkylation sensitivity in Indian muntjac cell lines.

    Science.gov (United States)

    Musk, S R; Hatton, D H; Bouffler, S D; Margison, G P; Johnson, R T

    1989-07-01

    The responses of two Indian muntjac cell lines to two monofunctional alkylating agents were investigated. An SV40-transformed line (SVM) had an increased sensitivity to cell killing when compared to the other, euploid line (DM) after exposure both to methyl nitrosourea (MNU) and to dimethylsulphate (DMS) and also exhibited higher frequencies of sister chromatid exchanges (SCEs) following alkylation. The hypersensitivity of SVM to DMS correlates with the defective repair of single-strand breaks that results in the generation of long-lived breaks in the DNA following exposure, leading eventually to the formation of chromosome aberrations. In contrast no difference is seen in the formation of long-lived breaks in the DNA of SVM and DM after treatment with biologically relevant doses of MNU; in this case hypersensitivity may be due to the loss of O6-alkylguanine-DNA-alkyltransferase activity. The conclusion that the hypersensitivites of SVM to MNU and to DMS have different molecular bases is supported by transfection of SVM with plasmids containing the protein coding region of the Escherichia coli ada+ gene; subsequent expression within the cell corrects its hypersensitivity to the cytotoxic and SCE-inducing effects of MNU but has very little influence upon the lethality, SCE induction or the repair of long-lived DNA strand breaks after exposure to DMS. PMID:2544312

  14. WRNIP1 functions upstream of DNA polymerase η in the UV-induced DNA damage response

    International Nuclear Information System (INIS)

    Highlights: • The UV sensitivity of POLH−/− cells was suppressed by disruption of WRNIP1. • In WRNIP1−/−/−/POLH−/− cells, mutation frequencies and SCE after irradiation reduced. • WRNIP1 defect recovered rate of fork progression after irradiation in POLH−/− cells. • WRNIP1 functions upstream of Polη in the translesion DNA synthesis pathway. - Abstract: WRNIP1 (WRN-interacting protein 1) was first identified as a factor that interacts with WRN, the protein that is defective in Werner syndrome (WS). WRNIP1 associates with DNA polymerase η (Polη), but the biological significance of this interaction remains unknown. In this study, we analyzed the functional interaction between WRNIP1 and Polη by generating knockouts of both genes in DT40 chicken cells. Disruption of WRNIP1 in Polη-disrupted (POLH−/−) cells suppressed the phenotypes associated with the loss of Polη: sensitivity to ultraviolet light (UV), delayed repair of cyclobutane pyrimidine dimers (CPD), elevated frequency of mutation, elevated levels of UV-induced sister chromatid exchange (SCE), and reduced rate of fork progression after UV irradiation. These results suggest that WRNIP1 functions upstream of Polη in the response to UV irradiation

  15. Rad51C-deficient CL-V4B cells exhibit normal levels of mitomycin C-induced SCEs but reduced levels of UVC-induced SCEs

    International Nuclear Information System (INIS)

    The mechanisms of sister chromatid exchanges (SCEs) are not known. One hypothesis is that SCE is a manifestation of Rad51-dependent homologous recombination repair. In order to test this hypothesis, we have compared the frequencies of SCEs induced by mitomycin C (MMC) and 254 nm ultraviolet radiation (UVC) in wt V79B and the Rad51C-deficient CL-V4B cells. SCEs were analysed in the first (M1) and second (M2) post-treatment mitoses. In M1 MMC induced the same frequencies of SCEs in CL-V4B and V79B cells, while the UVC-induced SCE frequencies were lower in CL-V4B than V79B cells. In CL-V4B cells, MMC-induced SCEs were higher in M2 than in M1, suggesting that interstrand cross-links (ICL) are either not removed completely or are transformed into another form of DNA damage that persists until the next cell cycle. We suggest that SCEs may represent a mechanism to bypass MMC-induced ICL without their removal

  16. In vitro evaluation of the genotoxicity of a family of novel MeO-PEG-poly(D,L-lactic-co-glycolic acid)-PEG-OMe triblock copolymer and PLGA nanoparticles

    International Nuclear Information System (INIS)

    Despite the booming development of nanoparticle materials for pharmaceutical applications, studies on their genotoxicity are few. In our previous efforts to develop an intravenous nanoparticle material, a family of novel monomethoxy(polyethylene glycol)-poly(D,L-lactic-co-glycolic acid)-monomethoxy (PELGE) polymers was synthesized. The cytotoxicity and genotoxicity of nine kinds of selected blank PELGE and PLGA (poly(D,L-lactic and glycolic acid)) nanoparticles were evaluated using methyl thiazolyl tetrazolium (MTT), micronucleus (MN) and sister chromatid exchange (SCE) assays with or without the addition of a metabolic activation system (S9 mix), using Chinese hamster ovary (CHO) cells. The cytotoxicity of nanoparticles exhibited a dose-dependent response, with a concentration of 5 mg ml-1 being the turning point. The frequencies of MN observed in samples treated with various nanoparticles were not statistically different from those seen in the negative controls in the presence or absence of the S9 mix. Also, no cell cycle delay was observed. The numbers of SCE per cell observed in samples treated with five kinds of PELGE nanoparticles were significantly greater than those found in the negative controls with or without the S9 mix. The discrepancies found in the two assays suggest that the five kinds of nanoparticles may produce only a weakly clastogenic response.

  17. WRNIP1 functions upstream of DNA polymerase η in the UV-induced DNA damage response

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimura, Akari, E-mail: akari_yo@stu.musashino-u.ac.jp [Molecular Cell Biology Laboratory, Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585 (Japan); Kobayashi, Yume [Molecular Cell Biology Laboratory, Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585 (Japan); Tada, Shusuke [Department of Medical Biochemistry, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-shi, Chiba 274-8510 (Japan); Seki, Masayuki [Department of Biochemistry, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai-shi, Miyagi 981-8558 (Japan); Enomoto, Takemi [Molecular Cell Biology Laboratory, Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585 (Japan)

    2014-09-12

    Highlights: • The UV sensitivity of POLH{sup −/−} cells was suppressed by disruption of WRNIP1. • In WRNIP1{sup −/−/−}/POLH{sup −/−} cells, mutation frequencies and SCE after irradiation reduced. • WRNIP1 defect recovered rate of fork progression after irradiation in POLH{sup −/−} cells. • WRNIP1 functions upstream of Polη in the translesion DNA synthesis pathway. - Abstract: WRNIP1 (WRN-interacting protein 1) was first identified as a factor that interacts with WRN, the protein that is defective in Werner syndrome (WS). WRNIP1 associates with DNA polymerase η (Polη), but the biological significance of this interaction remains unknown. In this study, we analyzed the functional interaction between WRNIP1 and Polη by generating knockouts of both genes in DT40 chicken cells. Disruption of WRNIP1 in Polη-disrupted (POLH{sup −/−}) cells suppressed the phenotypes associated with the loss of Polη: sensitivity to ultraviolet light (UV), delayed repair of cyclobutane pyrimidine dimers (CPD), elevated frequency of mutation, elevated levels of UV-induced sister chromatid exchange (SCE), and reduced rate of fork progression after UV irradiation. These results suggest that WRNIP1 functions upstream of Polη in the response to UV irradiation.

  18. Cytotoxicity and genotoxicity of iron oxide nanoparticles: An in vitro biosafety study

    Directory of Open Access Journals (Sweden)

    Sonmez Erdal

    2016-01-01

    Full Text Available With the development of nanotechnology and the wide use of iron oxide nanoparticles, it has become necessary to assess the potential adverse biological effects of magnetite. This study investigated the cytotoxicity, genotoxicity and oxidative damage of different concentrations of magnetite (0 to 1000 mg/L in human whole blood cultures. After supplementation of magnetite, the blood samples were incubated for 72 h. Cell viability was assessed by the 3-(4,5-dimethyl-thiazol-2-yl 2,5-diphenyltetrazolium bromide (MTT and lactate dehydrogenase (LDH release assays. The total antioxidant capacity (TAC and total oxidant status (TOS were determined to evaluate the dose-dependent effects of magnetite on the oxidant/antioxidant balance and to evaluate the potential oxidative injury due to increased oxidative stress. Genotoxicity was estimated by by the sister chromatid exchange (SCE, micronuclei (MN and chromosome aberration (CA assays and determination of 8-oxo-2-deoxyguanosine (8-OH-dG levels. The results of MTT and LDH assays showed that the higher concentrations of magnetite (100, 150, 300, 500 and 1000 mg/L decreased cell viability. Concentrations of magnetite higher than 10 mg/L increased TOS levels and decreased TAC levels in human blood cells. Increasing concentrations of magnetite caused significant increases in MN, SCE and CA rates and 8-OH-dG levels. The obtained results showed that magnetite exerted dose-dependent effects on oxidative damage, genotoxicity and cytotoxicity in human blood cells.

  19. A cytogenetic study of cows from a highly industrial or an agricultural region.

    Science.gov (United States)

    Parada, R; Jaszczak, K

    1993-08-01

    An examination was made of the frequency of chromosomal aberrations and sister-chromatid exchange in the blood lymphocytes of cows from an industrial region (aluminium smelting plant, lignite quarries, briquette factory, electric plants, mechanical plants. The control group consisted of cows from an agricultural region. In cows from the industrial region a significantly higher level of chromosomal aberrations was observed than in cows from the agricultural region (5.82 +/- 0.46 vs. 2.11 +/- 0.31 per 100 cells). In older, 7-12-year-old cows from the industrial region a slightly higher level of chromosomal aberrations was observed, and a significantly higher level of gaps than in younger cows. The frequency of SCE in the blood lymphocytes of cows from the industrial region was also higher and reached 7.47 +/- 2.33 per cell, while in cows from the agricultural region it was only 6.38 +/- 1.88, but these differences were not significant statistically. However, significant differences were observed in the number of SCE between the age groups within the industrial region P < or = 0.001) in favour of the younger animals. The results obtained indicate that the industrial pollution emitted into the environment may have a genotoxic character. Thus cytogenetic examination of cattle may be a useful test for monitoring industrial pollution. PMID:7687027

  20. Argentine folk medicine: genotoxic effects of Chenopodiaceae family.

    Science.gov (United States)

    Gadano, A B; Gurni, A A; Carballo, M A

    2006-01-16

    Chenopodium ambrosioides L. and Chenopodium multifidum L. (Chenopodiaceae), common name: Paico, are medicinal plants. They are aromatic shrubs growing in South America. For centuries, they have been used due to its medicinal properties. However, there are few reports in literature about the genotoxic effects of these plants. There for, the aim of these work is the evaluation of genetic damage induced by decoction and infusion of this plants which were assayed in different concentrations (1, 10, 100, 1,000 microL extract/mL culture), by addition of the extract to human lymphocyte cell cultures, negative controls were included. The endpoints evaluated were chromosomal aberrations (CA), sister chromatid exchanges (SCE), cell proliferation kinetics (CPK) and mitotic index (MI). The repeated measure analysis of variance was used for statistic evaluation of the results. The results showed: (a) statistical increase in the percentage of cells with CA and in the frequency of SCE when cultures were exposed to both aromatic plants, (b) a decrease in MI of both Paicos assayed, although no modification in the CPK values was observed, (c) no effect was noticed in the analysis of Chenopodium album L., which was used as negative control of the essential oil. These results suggest a cyto and genotoxic effect of Chenopodium ambrosioides and Chenopodium multifidum aqueous extracts related to the essential oil of the plant (as Chenopodium album did not perform). PMID:16219440

  1. Radiation exposure: Cytogenetic tests. Chernobyl reactor accident

    International Nuclear Information System (INIS)

    Forty test subjects who, either during or after the reactor accident of Chernobyl (26th April 1986), stayed at a building site at Shlobin 150 km away, were examined for spontaneously occurring as well as mitomycin C-induced Sister Chromatid Exchanges (SCE). The building site staff, who underwent a whole-body radionuclide count upon their return to Austria (June through September 1986), were used for the cytogenetic tests. The demonstration of the SCE was made from whole-blood cultures by the fluorescence/Giemse technique. At last 20 Metaphases of the 2nd mitotic cycle were evaluated per person. The radiation doses of the test subjects were calculated by adding the external exposure determined on the building site, the estimated thyroid dose through I-131, and the measured incorporation of Cs-134 and Cs-137. The subjects were divided into two groups for statistical analysis: One was a more exposed group (proven stay at Shlobin between 26th April and 31st May 1986, mostly working in the open air) and the other a less exposed group for comparison (staying at Shlobin from 1st Juni 1986 and working mainly indoors). (orig.)

  2. Genotoxicity of water from the Songhua River, China, in 1994-1995 and 2002-2003: Potential risks for human health

    International Nuclear Information System (INIS)

    A previous study showed that the cancer mortalities are higher for residents who lived nearby the Songhua River heavily polluted by organic contamination. It is important to determine its risk of carcinogenic potential. Short-term genotoxic bio-assays using Salmonella, Sister Chromatid Exchange (SCE), and Micronuclei (MN) assays were employed to examine the genotoxic activity of ether extracts of water samples taken from the Songhua River. The results of the Salmonella bioassay indicated that there were indirect frame-shift mutagens in the water samples. A dose-response relationship for the SCE and MN assays was obtained. These results showed that organic extracts of water samples have genotoxic activity and the risk of carcinogenic potential to human health. The mutagenesis of water samples had changed compared to the results in 1994-1995. An increasing trend of risk of carcinogenic potential in the Songhua River after ten years should be noted and needs to be studied further. - Organic extracts of water samples taken from the Songhua River have genotoxic activity and the risk of carcinogenic potential to human health

  3. Genotoxicity of drinking water from Chao Lake

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Q.; Jiao, Q.C. [Nanjing Univ. (China). Dept. of Biological Science and Technology; Huang, X.M.; Jiang, J.P.; Cui, S.Q.; Yao, G.H.; Jiang, Z.R.; Zhao, H.K.; Wang, N.Y. [Anhui Antiepidemic Station, Hefei (China)

    1999-02-01

    Genotoxic activity appears to originate primarily from reactions of chlorine with humic substances in the source waters. Comparisons of extracts of settled versus chlorinated water have confirmed that chlorinating during water treatment produces mutagenic activity in the mutagenicity tests. Present work on XAD-2 extracts of raw, chlorinated (treated), and settled water from the Chao Lake region of China has involved a battery of mutagenicity assays for various genetic endpoints: the Salmonella test, the sister-chromatid exchange (SCE) induction in Chinese hamster lung (CHL) cells, and the micronucleus (MN) induction in the peripheral blood erythrocytes of silver carp. Extracts of raw and treated water but not the settled water are mutagenic in the Salmonella assay. On the other hand, extracts of three water samples show activity in the SCE and MN assays, especially the raw and treated water. These data show that contamination and chlorinating contribute mutagens to drinking water and suggest that the mammalian assays may be more sensitive for detecting mutagenicity in aquatic environment than the Salmonella test.

  4. The effects of {sup 99m}Tc-HMPAO-labelled leucocyte scan on human karyotype

    Energy Technology Data Exchange (ETDEWEB)

    Liberatore, Mauro; Prosperi, Daniela; Iurilli, Anna Paola [Section of Nuclear Medicine, Department of Experimental Medicine and Pathology, University of Rome ' ' La Sapienza' ' , Policlinico Umberto I, Viale Regina Elena 324, 00161, Rome (Italy); Poscente, Monica; Mancini, Barbara; Grammatico, Paola [Medical Genetics, Department of Experimental Medicine and Pathology Department, University of Rome ' ' La Sapienza' ' , Rome (Italy); Donnetti, Massimo [Section of Medical Physics, Department of Experimental Medicine and Pathology, University of Rome ' ' La Sapienza' ' , Rome (Italy)

    2003-10-01

    Technetium-99m hexamethylpropylene amine oxime (HMPAO) white blood cell scan (WBCS) requires separation and labelling of mixed leucocytes, which include particularly radiosensitive cells, lymphocytes. Lymphocytes labelled during the mixed leucocyte labelling procedure could represent a problem for patients owing to the possible induction of chromosomal aberrations. Lymphocytes labelled in mixed leucocyte preparations are probably killed by the high-dose radiation. Nevertheless, it has been reported that some of these lymphocytes can proliferate after in vitro stimulation. If these cells were to reproduce themselves in vivo, onset of, or increase over time in, chromosomal aberrations could occur on peripheral blood lymphocytes. The present study was performed on 21 patients who underwent WBCS for suspected infection/inflammation. Blood samples of these patients were submitted to cytogenetic study, comprising karyotype determination, evaluation of sister chromatid exchanges (SCE) and evaluation of induced chromosomal breakages or rearrangement rate (B/R). This study was performed 2 h before and 7 days and 6 months after the WBCS. The results demonstrated no statistically significant differences between SCE and B/R values before and after WBCS. No cause-effect relationship appeared to exist between WBCS and the onset of chromosomal aberrations in peripheral blood lymphocytes, at least during the first 6 months post WBCS and within the limits of this study's approach. The high-dose radiation administered to lymphocytes was almost certainly sufficient to kill these cells. (orig.)

  5. Evaluation of primary DNA damage, cytogenetic biomarkers and genetic polymorphisms for CYP1A1 and GSTM1 in road tunnel construction workers.

    Science.gov (United States)

    Villarini, M; Moretti, M; Fatigoni, C; Agea, E; Dominici, L; Mattioli, A; Volpi, R; Pasquini, R

    2008-01-01

    In tunnel construction workers, occupational exposure to dust (alpha-quartz and other particles from blasting), gases (nitrogen dioxide, NO(2)), diesel exhausts, and oil mist has been associated with lung function decline, induction of inflammatory reactions in the lungs with release of mediators that may influence blood coagulation, and increased risk of chronic obstructive pulmonary disease. The present molecular epidemiology study was designed to evaluate whether occupational exposure to indoor pollutants during road tunnel construction might result in genotoxic effects. A study group of 39 underground workers and a reference group of 34 unexposed subjects were examined. Primary and oxidative DNA damage, sister-chromatid exchanges (SCE), and micronuclei (MN) were measured in peripheral blood cells. The possible influences of polymorphisms in gene encoding for CYP1A1 and GSTM1 xenobiotic-metabolizing enzymes were also investigated. Exposure assessment was performed with detailed interviews and questionnaires. There were no significant differences in the level of primary and oxidative DNA damage and frequency of SCE between the tunnel workers and controls, whereas the frequency of MN showed a significant increase in exposed subjects compared to controls. No effects of CYP1A1 or GSTM1 variants were observed for the analyzed biomarkers. Since MN in peripheral blood lymphocytes are recognized as a predictive biomarker of cancer risk within a population of healthy subjects, the genotoxic risk of occupational exposure to various indoor environmental pollutants during road tunnel construction cannot be excluded by this biomonitoring study. PMID:18800292

  6. Electrodeposited conductive polypyrrole/polyaniline composite film for the corrosion protection of copper bipolar plates in proton exchange membrane fuel cells

    Science.gov (United States)

    Pan, T. J.; Zuo, X. W.; Wang, T.; Hu, J.; Chen, Z. D.; Ren, Y. J.

    2016-01-01

    A conductive composite coating consisting of an inner polypyrrole (PPY) layer and an outer polyaniline (PANI) layer is prepared on a copper substrate by an electrochemical synthesis. Potential application of these composite coatings in a proton exchange membrane fuel cell (PEMFC) is evaluated. The corrosion performance of the copper substrate without and with the polymer coatings in the acidic solutions containing H2SO4 (0.2 M), HCl (0.1 M) and HF (3 ppm) is investigated by electrochemical impedance spectroscopy, polarization and open-circuit potential measurements. The results indicate that both the bilayered PPY/PANI and the single PPY coating can increase the corrosion potential of copper substrate by more than 250 mV (SCE), and effectively decrease the corrosion current density by an order of magnitude in comparison with the uncoated copper substrate. Long-term test further confirms that the bilayered PPY/PANI coating with acceptable contact resistance provides better protection for the substrate than the single PPY coating. The bilayered structure with different ion-permselective nature may serve as an effective physical barrier to the inward penetration of corrosive species.

  7. Exchange, phenomenology and the Self

    OpenAIRE

    Galonska, Deniece; Yener, Efe Can; Sørensen, Karen Mallya; Olesen, Tine Lautrup

    2016-01-01

    The research project aims to investigate the ‘Self’ concerning the experience of being an international exchange student. As the research approaches the three participants as unique individuals, phenomenology provided a foundation regarding the ontological stance and a method. The philosophy of phenomenology and its different interview methods will be discussed, in relation to perspectives by Edmund Husserl and Martin Heidegger, with attention aimed at the question whether or not objectiv...

  8. The Exchange Rate Exposure Puzzle

    OpenAIRE

    Bartram, Söhnke M.; Bodnar, Gordon

    2005-01-01

    Based on basic financial models and reports in the business press, exchange rate movements are generally believed to affect the value of nonfinancial firms. In contrast, the empirical research on nonfinancial firms typically produces fewer significant exposures estimates than researchers ex-pect, independent of the sample studied and the methodology used, giving rise to a situation known as “the exposure puzzle”. This paper provides a survey of the existing research on the exposure phenomenon...

  9. Washi Painting Exchanges Promote Friendship

    Institute of Scientific and Technical Information of China (English)

    Chuan; You

    2014-01-01

    <正>Invited by the Sichuan Provincial People’s Association for Friendship with Foreign Countries(SIFA),a washi painting exchange delegation headed by Umeko Iwai,President of Rainbow Society of Japan,a Hiroshima-based non-profit organization,visited Sichuan Province from November 3 to 5,2013.Rice paper was invented in China in ancient times.When the paper-making

  10. Exchange Rate Choices of Microstates

    OpenAIRE

    Patrick A. Imam

    2010-01-01

    In this paper we first explain why most microstates (countries with less than 2 million inhabitants) have gained independence only in the last 30 years. Despite the higher costs and risks microstates face, their ability to better accommodate local preferences combined with a more integrated world economy probably explains why the benefits of independence have risen. We explain why microstates at independence have chosen either dollarization, currency board arrangements, or fixed exchange rate...

  11. Indeterminacy in foreign exchange markets

    Science.gov (United States)

    Pasquini, Michele; Serva, Maurizio

    2000-03-01

    We discuss price variations distributions in foreign exchange markets, characterizing them both in calendar and business time frameworks. The price dynamics is found to be the result of two distinct processes, a multi-variance diffusion and an error process. The presence of the latter, which dominates at short time scales, leads to indeterminacy principle in finance. Furthermore, dynamics does not allow for a scheme based on independent probability distributions, since volatility exhibits a strong correlation even at the shortest time scales.

  12. Indeterminacy in foreign exchange market

    OpenAIRE

    Michele Pasquini; Maurizio Serva

    1999-01-01

    We discuss price variations distributions in foreign exchange markets, characterizing them both in calendar and business time frameworks. The price dynamics is found to be the result of two distinct processes, a multi-variance diffusion and an error process. The presence of the latter, which dominates at short time scales, leads to indeterminacy principle in finance. Furthermore, dynamics does not allow for a scheme based on independent probability distributions, since volatility exhibits a s...

  13. Heat exchanger demonstration expert system

    Science.gov (United States)

    Bagby, D. G.; Cormier, R. A.

    1988-05-01

    A real-time expert system intended for detecting and diagnosing faults in a 20 kW microwave transmitter heat exchanger is described. The expert system was developed on a LISP machine, Incorporated (LMI), Lambda Plus computer using Process Intelligent Control (PICON) software. The Heat Exhanger Expert System was tested and debugged. Future applications and extensions of the expert system to transmitters, masers, and antenna subassemblies are discussed.

  14. Electrically controlled cesium ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Lilga, M. [Pacific Northwest Lab., Richland, WA (United States)

    1996-10-01

    Several sites within the DOE complex (Savannah River, Idaho, Oak Ridge and Hanford) have underground storage tanks containing high-level waste resulting from nuclear engineering activities. To facilitate final disposal of the tank waste, it is advantageous to separate and concentrate the radionuclides for final immobilization in a vitrified glass matrix. This task proposes a new approach for radionuclide separation by combining ion exchange (IX) and electrochemistry to provide a selective and economic separation method.

  15. The British foreign exchange reserves puzzle

    OpenAIRE

    Hüfner, Felix P.

    2000-01-01

    The British foreign exchange reserves decreased by 40 percent during the period August 1996-December 1999 although the Pound Sterling is considered a floating exchange rate since it left the EMS in 1992. Since changes in the level of foreign exchange reserves are usually taken as indicators for foreign exchange interventions in the economic literature we investigate the case of the British reserves in detail. While the Pound Sterling has appreciated strongly against the Deutsche Mark in this ...

  16. Test procedure for cation exchange chromatography

    International Nuclear Information System (INIS)

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction

  17. Membrane and plastic heat exchangers performance

    OpenAIRE

    Masud Behnia; Mohammad Shakir Nasif; Graham L. Morrison

    2005-01-01

    The performance of a membrane-based heat exchanger utilizing porous paper as the heat and moisture transfer media is presented. The measured performance is compared with a plastic film heat exchanger. This novel heat exchanger is used in ventilation energy recovery systems. The results show that the sensible effectiveness is higher than the latent effectiveness. When a similar experiment was conducted using a plastic film heat exchanger surface instead of paper, where only heat is transferred...

  18. Gasketed plate type heat exchanger design software

    OpenAIRE

    Gebremariam, Aklilu

    2016-01-01

    The purpose of this thesis was to make the design of gasketed plate type heat exchangers easier, simple, and accurate by reducing human error. Properly designed heat exchangers can provide more benefits and better safety in wide range of applications. Since the design of heat exchangers is so complicated and involves several steps, computer-aided design has come to be widely used. In this design, along with the knowledge of heat exchangers, the Visual Studio 2013 Professional and the programm...

  19. The magic of knowledge exchange

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    “If you have an apple and I have an apple and we exchange these apples then you and I will still each have one apple. But if you have an idea and I have an idea and we exchange these ideas, then each of us will have two ideas”. (George Bernard Shaw). The CERN Global Network is a new, ideal place for past and present members of the CERN community to share ideas and create new links.   On 29 April, CERN’s Knowledge and Technology Transfer (KTT) Group launched the CERN Global Network, a tool whose aim is to facilitate knowledge exchanges inside and outside CERN. "Among the greatest ambassadors of knowledge are people who have been trained and educated at CERN and also at other institutes: here is where the Global Network comes into play", says Rolf Heuer, CERN Director General. “During the first phase, the Network will be open to current and former members of the CERN personnel, that is, staff, fellows, apprentices, associates, students a...

  20. 225-B ion exchange piping design documentation

    Energy Technology Data Exchange (ETDEWEB)

    Prather, M.C. [ICF Kaiser Hanford Co., Richland, WA (United States)

    1996-02-01

    This document describes the interface between the planned permanent ion exchange piping system and the planned portable ion exchange system. This is part of the Waste Encapsulation and Storage Facility (WESF). In order to decouple this WESF from B-Plant and to improve recovery from a capsule leak, contaminated pool cell water will be recirculated through a portable ion exchange resin system.

  1. Trust and Transitions in Modes of Exchange

    Science.gov (United States)

    Cheshire, Coye; Gerbasi, Alexandra; Cook, Karen S.

    2010-01-01

    In this study, we investigate the relationship between uncertainty and trust in exogenous shifts in modes of social exchange (i.e., those that are not initiated by the individuals in a given exchange system). We explore how transitions from a high uncertainty environment (reciprocal exchange) to lower-uncertainty environments (nonbinding or…

  2. 225-B ion exchange piping design documentation

    International Nuclear Information System (INIS)

    This document describes the interface between the planned permanent ion exchange piping system and the planned portable ion exchange system. This is part of the Waste Encapsulation and Storage Facility (WESF). In order to decouple this WESF from B-Plant and to improve recovery from a capsule leak, contaminated pool cell water will be recirculated through a portable ion exchange resin system

  3. Power and Dependence in Intimate Exchange

    Science.gov (United States)

    van de Rijt, Arnout; Macy, Michael W.

    2006-01-01

    A division of labor is mediated by exchange of valued goods and services. We use social exchange theory to extend this principal to "labors of love." Sexual activity in a close personal relationship seems outside the domain of bargaining and exchange. Nevertheless, we explore the possibility that this most intimate of human relations is influenced…

  4. Cryogenic Heat Exchanger with Turbulent Flows

    Science.gov (United States)

    Amrit, Jay; Douay, Christelle; Dubois, Francis; Defresne, Gerard

    2012-01-01

    An evaporator-type cryogenic heat exchanger is designed and built for introducing fluid-solid heat exchange phenomena to undergraduates in a practical and efficient way. The heat exchanger functions at liquid nitrogen temperature and enables cooling of N[subscript 2] and He gases from room temperatures. We present first the experimental results of…

  5. Test procedure for anion exchange chromatography

    International Nuclear Information System (INIS)

    Plutonium from stored nitrate solutions will be sorbed onto anion exchange resins and converted to storable plutonium dioxide. Useful information will be simultaneously gained on the thermal stability and ion exchange capacity of four commercially available anion exchange resins over several years and under severe degradative conditions. This information will prove useful in predicting the safe and efficient lifetimes of these resins

  6. Fluidized bed heat exchanger utilizing angularly extending heat exchange tubes

    Science.gov (United States)

    Talmud, Fred M.; Garcia-Mallol, Juan-Antonio

    1980-01-01

    A fluidized bed heat exchanger in which air is passed through a bed of particulate material containing fuel disposed in a housing. A steam/water natural circulation system is provided and includes a steam drum disposed adjacent the fluidized bed and a series of tubes connected at one end to the steam drum. A portion of the tubes are connected to a water drum and in the path of the air and the gaseous products of combustion exiting from the bed. Another portion of the tubes pass through the bed and extend at an angle to the upper surface of the bed.

  7. Optimal counter-current exchange networks

    CERN Document Server

    Farr, Robert S

    2016-01-01

    We construct a general analysis for exchange devices linking their efficiency to the (potentially fractal) geometry of the exchange surface and supply network. For certain parameter ranges, we show that the optimal exchanger consists of densely packed pipes which span a thin sheet of large area, which may be crumpled into a fractal surface and supplied with a fractal network of pipes. We present the efficiencies of such fractal exchangers, showing factor gains compared to regular exchangers, using parameters relevant for systems such as pigeon lungs and salmon gills.

  8. MULTI-ITEM FAIR EXCHANGE SCHEME

    Institute of Scientific and Technical Information of China (English)

    Zheng Dong; Chen Kefei

    2002-01-01

    As more business is conduced over the Internet, the fair exchange problem assumes increasing importance. However, the problem of multi-party fair exchange has not been studied as widely as the more fundamental problem of 2-party fair exchange. Recently, Franklin and Tsudik proposed two protocols for n-party multi-item exchange on FC'98, SUCEX-1 and SUCES-2. This paper first gives an attack on the proposed protocol SUCEX-1, then presents two protocols for multi-item exchange, one is an improved protocol of SUCEX-1, another is the extension of protocol SUCEX-2.

  9. MULTI—ITEM FAIR EXCHANGE SCHEME

    Institute of Scientific and Technical Information of China (English)

    ZhengDong; ChenKefei

    2002-01-01

    As more ubsiness is conduced over the Internet,the fair exchange problem assumes increasing importance,However,the problem of multi-party fair exchange has not been studied as widely as the more fundamental problem of 2-party fair exchange,Recently,Franklin and Tsudik proposed two protocols for n-parth multi-item exchange on FC'98,SUCEX-1 and SUCES-2,This paper first gives an attack on the proposed protocol SUCEX-1,then presents two protocols for multi-item exchange,one is an improoved protocol of SUCEX-1,another is the extension of protocol SUCEX-2.

  10. Mathematical simulation of heat exchanger working conditions

    OpenAIRE

    Gavlas Stanislav; Ďurčanský Peter; Lenhard Richard; Jandačka Jozef

    2015-01-01

    One of the When designing a new heat exchanger it is necessary to consider all the conditions imposed on the exchanger and its desired properties. Most often the investigation of heat transfer is to find heat surface. When applying exchanger for proposed hot air engine, it will be a counter-flow heat exchanger of gas - gas type. Gas, which transfers the heat will be exhaust gas from the combustion of biomass. An important step in the design and verification is to analyze exchanger designed us...

  11. The determinants of exchange rate in Croatia

    Directory of Open Access Journals (Sweden)

    Manuel BENAZIC

    2016-06-01

    Full Text Available The dilemma for every country with an independent monetary policy is which kind of exchange rate arrangement should be applied. Through the exchange rate policy, countries can influence their economies, i.e. price stability and export competiveness. Croatia is a new EU member state, it has its own monetary policy and currency but it is on the way to euro introduction. Regarding the experiences from the beginning of the 1990s when Croatia was faced with serious monetary instabilities and hyperinflation, the goal of Croatian National Bank (CNB is to ensure price stability and one way to do so is through exchange rate policy. Croatia, as a small and open economy, has applied a managed floating exchange rate regime. The exchange rate is determined primarily by the foreign exchange supply and demand on the foreign exchange market, with occasional market interventions by the CNB. Therefore, in order to maintain exchange rate stability, policymakers must be able to recognize how changes in these factors affect changes in the exchange rate. This research aims to find a relationship among the main sources of foreign currency inflow and outflow and the level of exchange rate in Croatia. The analysis is carried out by using the bounds testing (ARDL approach for co-integration. The results indicate the existence of a stable co-integration relationship between the observed variables, whereby an increase in the majority of variables leads to an exchange rate appreciation.

  12. Does the Nominal Exchange Rate Regime Affect the Long Run Properties of Real Exchange Rates?

    OpenAIRE

    Dreger, Christian; Girardin, Eric

    2007-01-01

    This paper examines whether the behaviour of the real exchange rate is associated with a particular regime for the nominal exchange rate, like fixed and flexible exchange rate arrangements. The analysis is based on 16 annual real exchange rates and covers a long time span, 1870-2006. Four subperiods are distinguished and linked to exchange rate regimes: the Gold Standard, the interwar float, the Bretton Woods system and the managed float thereafter. Panel integration techniques are applied to...

  13. Fouling analyses of heat exchangers for PSR

    International Nuclear Information System (INIS)

    Fouling of heat exchangers is generated by water-borne deposits, commonly known as foulants including particulate matter from the air, migrated corrosion produces; silt, clays, and sand suspended in water; organic contaminants; and boron based deposits in plants. This fouling is known to interfere with normal flow characteristics and reduce thermal efficiencies of heat exchangers. This paper focuses on fouling analyses for six heat exchangers of two primary systems in two nuclear power plants; the regenerative heat exchangers of the chemical and volume control system and the component cooling water heat exchangers of the component cooling water system. To analyze the fouling for heat exchangers, fouling factor was introduced based on the ASME O and M codes and TEMA standards. Based on the results of the fouling analyses, the present thermal performances and fouling levels for the six heat exchangers were predicted

  14. PRTR ion exchange vault column sampling

    International Nuclear Information System (INIS)

    This report documents ion exchange column sampling and Non Destructive Assay (NDA) results from activities in 1994, for the Plutonium Recycle Test Reactor (PRTR) ion exchange vault. The objective was to obtain sufficient information to prepare disposal documentation for the ion exchange columns found in the PRTR Ion exchange vault. This activity also allowed for the monitoring of the liquid level in the lower vault. The sampling activity contained five separate activities: (1) Sampling an ion exchange column and analyzing the ion exchange media for purpose of waste disposal; (2) Gamma and neutron NDA testing on ion exchange columns located in the upper vault; (3) Lower vault liquid level measurement; (4) Radiological survey of the upper vault; and (5) Secure the vault pending waste disposal

  15. Topological gravity with exchange algebra

    OpenAIRE

    Aoyama, S.

    1993-01-01

    A topological gravity is obtained by twisting the effective $(2,0)$ super\\-gravity. We show that this topological gravity has an infinite number of BRST invariant quantities with conformal weight $0$. They are a tower of OSp$(2,2)$ multiplets and satisfy the classical exchange algebra of OSp$(2,2)$. We argue that these BRST invariant quantities become physical operators in the quantum theory and their correlation functions are braided according to the quantum OSp$(2,2)$ group. These propertie...

  16. Ion exchange purification of scandium

    Science.gov (United States)

    Herchenroeder, Laurie A.; Burkholder, Harvey R.

    1990-10-23

    An improvement in purification of scandium through ion exchange chromatography is disclosed in which the oxidation potential of the eluting solution is altered by the addition of potassium chlorate or ammonium chloride so that removal of contaminants is encouraged. The temperature, pH and concentration of the eluent HEDTA are controlled in order to maintain the scandium in the column while minimizing dilution of the scandium band. Recovery of scandium is improved by pumping dilute scandium over the column prior to stripping the scandium and precipitation. This eliminates the HEDTA ion and other monovalent cations contaminating the scandium band. This method maximizes recovery of scandium while maintaining purity.

  17. Heat exchanger with oscillating flow

    Science.gov (United States)

    Scotti, Stephen J. (Inventor); Blosser, Max L. (Inventor); Camarda, Charles J. (Inventor)

    1993-01-01

    Various heat exchange apparatuses are described in which an oscillating flow of primary coolant is used to dissipate an incident heat flux. The oscillating flow may be imparted by a reciprocating piston, a double action twin reciprocating piston, fluidic oscillators or electromagnetic pumps. The oscillating fluid flows through at least one conduit in either an open loop or a closed loop. A secondary flow of coolant may be used to flow over the outer walls of at least one conduit to remove heat transferred from the primary coolant to the walls of the conduit.

  18. Information transmission without energy exchange

    OpenAIRE

    Jonsson, Robert H.; Martin-Martinez, Eduardo; Kempf, Achim

    2014-01-01

    We show that it is possible to use a massless field in the vacuum to communicate in such a way that the signal travels arbitrarily slower than the speed of light and such that no energy is transmitted from the sender to the receiver. Instead, the receiver has to supply a signal-dependent amount of work to switch his detector on and off. Because of that, this kind of communication without energy exchange may be called "Quantum Collect Calling". This type of communication is related to Casimir-...

  19. EPR of exchange coupled systems

    CERN Document Server

    Bencini, Alessandro

    2012-01-01

    From chemistry to solid state physics to biology, the applications of Electron Paramagnetic Resonance (EPR) are relevant to many areas. This unified treatment is based on the spin Hamiltonian approach and makes extensive use of irreducible tensor techniques to analyze systems in which two or more spins are magnetically coupled. This edition contains a new Introduction by coauthor Dante Gatteschi, a pioneer and scholar of molecular magnetism.The first two chapters review the foundations of exchange interactions, followed by examinations of the spectra of pairs and clusters, relaxation in oligon

  20. International Scientific Exchanges in 2001

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In 2001, China Institute of Atomic Energy (CIAE) signed 4 agreements 、 memorandums and 10 technical contracts with some institutes and companies of Russia, Cambodia, Korea and Belgium. CIAE sent 277 scientists, engineers and technical visitors jointed academic exchanges. Among of them, there were 91 person-times attended international conferences and symposiums, 28 person-times went abroad on the studied tour, 158 person-times worked or were trained through collaboration as well as contract implementations, etc.In 2001, CIAE held 5 international conferences and training courses in Beijing. CIAE received 497 foreign visitors from more than 30 counties and regions, they gave more than 400

  1. Risk appetite and exchange rates

    OpenAIRE

    Tobias ADRIAN; Etula, Erkko; Shin, Hyun-song

    2015-01-01

    We present evidence that the growth of U.S.-dollar-denominated banking sector liabilities forecasts appreciations of the U.S. dollar, both in-sample and out-of-sample, against a large set of foreign currencies. We provide a theoretical foundation for a funding liquidity channel in a global banking model where exchange rates fluctuate as a function of banks' balance sheet capacity. We estimate prices of risk using a cross-sectional asset pricing approach and show that the U.S. dollar funding l...

  2. Risk appetite and exchange Rates

    OpenAIRE

    Tobias ADRIAN; Etula, Erkko; Shin, Hyun Song

    2009-01-01

    We present evidence that the growth of U.S.-dollar-denominated banking sector liabilities forecasts appreciations of the U.S. dollar, both in-sample and out-of-sample, against a large set of foreign currencies. We provide a theoretical foundation for a funding liquidity channel in a global banking model where exchange rates fluctuate as a function of banks’ balance sheet capacity. We estimate prices of risk using a cross-sectional asset pricing approach and show that the U.S. dollar funding l...

  3. Heat exchanges in coarsening systems

    International Nuclear Information System (INIS)

    This paper is a contribution to the understanding of the thermal properties of ageing systems where statistically independent degrees of freedom with greatly separated time scales are expected to coexist. Focusing on the prototypical case of quenched ferromagnets, where fast and slow modes can be respectively associated with fluctuations in the bulk of the coarsening domains and in their interfaces, we perform a set of numerical experiments specifically designed to compute the heat exchanges between different degrees of freedom. Our studies promote a scenario with fast modes acting as an equilibrium reservoir to which interfaces may release heat through a mechanism that allows fast and slow degrees to maintain their statistical properties independently

  4. Effects of BRCA2 deficiency on telomere recombination in non-ALT and ALT cells

    Directory of Open Access Journals (Sweden)

    Sapir Ester

    2011-12-01

    Full Text Available Abstract Background Recent studies suggest that BRCA2 affects telomere maintenance. Interestingly, anti cancer treatments that involve BRCA2 and telomerase individually are currently being explored. In the light of the above recent studies their combinatorial targeting may be justified in the development of future treatments. In order to investigate effects of BRCA2 that can be explored for this combinatorial targeting we focused on the analysis of recombination rates at telomeres by monitoring T-SCEs (Telomere Sister Chromatid Exchanges. Results We observed a significant increase in T-SCE frequencies in four BRCA2 defective human cell lines thus suggesting that BRCA2 suppresses recombination at telomeres. To test this hypothesis further we analyzed T-SCE frequencies in a set of Chinese hamster cell lines with or without functional BRCA2. Our results indicate that introduction of functional BRCA2 normalizes frequencies of T-SCEs thus supporting the notion that BRCA2 suppresses recombination at telomeres. Given that ALT (Alternative Lengthening of Telomeres positive cells maintain telomeres by recombination we investigated the effect of BRCA2 depletion in these cells. Our results show that this depletion causes a dramatic reduction in T-SCE frequencies in ALT positive cells, but not in non-ALT cells. Conclusion BRCA2 suppresses recombination at telomeres in cells that maintain them by conventional mechanisms. Furthermore, BRCA2 depletion in ALT positive cells reduces high levels of T-SCEs normally found in these cells. Our results could be potentially important for refining telomerase-based anti-cancer therapies.

  5. Comparative study of the cytotoxic and genotoxic effects of titanium oxide and aluminium oxide nanoparticles in Chinese hamster ovary (CHO-K1) cells

    Energy Technology Data Exchange (ETDEWEB)

    Di Virgilio, A.L. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Diag. 113 y 64, Correo 16, Suc. 4, La Plata (1900) (Argentina); Reigosa, M. [Instituto Multidisciplinario de Biologia Celular (IMBICE), Calle 526 y Camino Gral. Belgrano (entre 10 y 11), La Plata 1900 (Argentina); Arnal, P.M. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Diag. 113 y 64, Correo 16, Suc. 4, La Plata 1900 (Argentina); Fernandez Lorenzo de Mele, M., E-mail: mmele@inifta.unlp.edu.ar [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Diag. 113 y 64, Correo 16, Suc. 4, La Plata 1900 (Argentina)

    2010-05-15

    The aim of this study was to analyze the cytotoxicity and genotoxicity of titanium oxide (TiO{sub 2}) and aluminium oxide (Al{sub 2}O{sub 3}) nanoparticles (NPs) on Chinese hamster ovary (CHO-K1) cells using neutral red (NR), mitochondrial activity (by MTT assay), sister chromatid exchange (SCE), micronucleus (MN) formation, and cell cycle kinetics techniques. Results showed a dose-related cytotoxic effect evidenced after 24 h by changes in lysosomal and mitochondrial dehydrogenase activity. Interestingly, transmission electronic microscopy (TEM) showed the formation of perinuclear vesicles in CHO-K1 cells after treatment with both NPs during 24 h but no NP was detected in the nuclei. Genotoxic effects were shown by MN frequencies which significantly increased at 0.5 and 1 {mu}g/mL TiO{sub 2} and 0.5-10 {mu}g/mL Al{sub 2}O{sub 3}. SCE frequencies were higher for cells treated with 1-5 {mu}g/mL TiO{sub 2}. The absence of metaphases evidenced cytotoxicity for higher concentrations of TiO{sub 2}. No SCE induction was achieved after treatment with 1-25 {mu}g/mL Al{sub 2}O{sub 3}. In conclusion, findings showed cytotoxic and genotoxic effects of TiO{sub 2} and Al{sub 2}O{sub 3} NPs on CHO-K1 cells. Possible causes of controversial reports are discussed further on.

  6. In vivo synergistic cytogenetic effects of aminophylline on lymphocyte cultures from patients with lung cancer undergoing chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Mylonaki, Effie; Manika, Katerina [Pulmonary Department, “G.Papanikolaou” General Hospital, Aristotle University of Thessaloniki (Greece); Zarogoulidis, Paul, E-mail: pzarog@hotmail.com [Pulmonary Department, “G.Papanikolaou” General Hospital, Aristotle University of Thessaloniki (Greece); Domvri, Kalliopi; Voutsas, Vasilis; Zarogoulidis, Kostas [Pulmonary Department, “G.Papanikolaou” General Hospital, Aristotle University of Thessaloniki (Greece); Mourelatos, Dionysios [Biology and Genetics, Medical School, Aristotle University of Thessaloniki (Greece)

    2012-12-15

    Highlights: ► SCEs in vivo, a possible predictor of tumor chemoresponse. ► In vivo exposure to combined treatment, applying the SCE assay. ► Aminophylline enhances DNA instability induced by chemotherapy in vivo. ► In vivo synergistic effect of Aminophylline with the chemotherapeutic agents. - Abstract: Background: The anti-cancer and cytogenetic effects of aminophylline (AM) have been demonstrated in several clinical trials. The aim of the present study was to investigate the in vivo cytogenetic effects of AM in newly diagnosed patients with small cell (SCLC) and non-small cell lung cancer (NSCLC), receiving chemotherapy for the first time. Methods: Sister chromatid exchanges (SCEs) and proliferation rate index (PRI) were evaluated in peripheral blood lymphocyte cultures from six patients with SCLC and six patients with NSCLC after the in vitro addition of AM and after the in vivo administration of AM in patients receiving chemotherapy. Results: The in vitro addition of AM significantly increased SCEs only in SCLC patients (p < 0.001). The in vivo administration of AM after chemotherapy increased SCEs in both cancer types (SCLC: p < 0.001, NSCLC: p = 0.003) and this increase was synergistic, the rates of SCEs in the presence of AM were higher than the expected SCE values if the increases above background for chemotherapy and AM were independent and additive (SCLC: p < 0.001, NSCLC: p = 0.008). Although in both groups of patients cell division delays were observed after the combined chemotherapy plus in vivo AM treatment, the correlation between the magnitude of the SCE response and the PRI depression was not statistically significant (p > 0.05). Conclusions: These observations suggest that AM enhances the results of concurrently administered chemotherapy by synergistically increasing its cytogenetic effects in patients with lung cancer.

  7. Anticarcinogenic and antimutagenic activity of Alstonia scholaris on the albino mice bone marrow cells and peripheral human lymphocyte culture against methyl methane sulfonate induced genotoxicity

    Science.gov (United States)

    Ahmad, Md. Sultan; Ahmad, Sheeba; Ali, Afsar; Afzal, Mohammad

    2016-01-01

    Background: The use of medicinal plants in modern medicine for the prevention and treatment of cancer is an important aspect. For this reason, it is important to identify antitumor promoting agents present in medicinal plants commonly used by the human population. Materials and Methods: We used in vivo and in vitro methods using chromosomal aberrations (CAs), sister chromatid exchange (SCE) and replication index (RI) as markers, exposed by methyl methanesulfonate (MMS) as well as alcoholic extract of Alstonia scholaris in five increasing concentrations (200, 250, 300, 350 and 400 mg/kg body weight for in vivo and 150, 200, 250 and 300 μg/ml of culture) and of three different durations of 24, 48 and 72 h in the presence as well absence of S9 mix. Results: Extracts of Alstonia reduces the total aberrant cells ranges from 10.0% to 41.84% and frequencies of aberration in the aberrant cells ranges from 220 to 124 against 290 aberrations causes due to MMS in vivo. Similarly in the in vitro, it reduces CAs (39.62%, 32.83%, and 38.48%) and (45.31%, 44.46%, and 38.34%) at 24, 48, and 72 h of exposure respectively; in the absence as well as presence of liver S9 fraction. It also reduces SCE from 7.70 to 4.20 per cell and enhances RI from 1.45 to 1.64. Conclusion: Extracts of Alstonia significantly reduces the number of aberrant cells and frequency of aberration per cell at each concentration and duration of exposure in vivo; and CAs and SCE in vitro and enhances RI. PMID:27308264

  8. Exchange of astronomy teaching experiences

    Science.gov (United States)

    Ros, Rosa M.

    The Working Group of the European Association for Astronomy Education responsible for Teacher Training organises an annual Summer School for teachers under expert guidance. For a week the teachers participating can exchange experiences, increase their knowledge and discuss different ideas and perspectives. In general, the instructors are professional astronomers, professors and teachers from different countries. The papers presented offer very practical activities, paying special attention to didactic aspects, and take the form of general lectures to all 40 participants and workshops to reduced groups of 20 participants. There are also day and night observations, without expensive equipment or complicated procedures, that are easy to set up and based on topics that it is possible to use in the classroom. The Summer Schools promote a scientific astronomical education at all levels of astronomy teaching, reinforce the link between professional astronomers and teachers with experience of teaching astronomy, allow debates among the participants on their pedagogical activities already carried out in their own classroom and help them to organise activities outside it. Astronomy teachers need special training, access to specific research, to new educational materials and methods and the opportunity to exchange experiences. All these things are provided by the Summer School.

  9. Improved ceramic heat exchange material

    Science.gov (United States)

    Mccollister, H. L.

    1977-01-01

    Improved corrosion resistant ceramic materials that are suitable for use as regenerative heat exchangers for vehicular gas turbines is reported. Two glass-ceramic materials, C-144 and C-145, have superior durability towards sulfuric acid and sodium sulfate compared to lithium aluminosilicate (LAS) Corning heat exchange material 9455. Material C-144 is a leached LAS material whose major crystalline phase is silica keatite plus mullite, and C-145 is a LAS keatite solid solution (S.S.) material. In comparison to material 9455, material C-144 is two orders of magnitude better in dimensional stability to sulfuric acid at 300 C, and one order of magnitude better in stability to sodium sulfate at 1000 C. Material C-145 is initially two times better in stability to sulfuric acid, and about one order of magnitude better in stability to sodium sulfate. Both C-144 and C-145 have less than 300 ppm delta L/L thermal expansion from ambient to 1000 C, and good dimensional stability of less than approximately 100 ppm delta L/L after exposure to 1000 C for 100 hours. The glass-ceramic fabrication process produced a hexagonal honeycomb matrix having an 85% open frontal area, 50 micrometer wall thickness, and less than 5% porosity.

  10. Testing and analysis of immersed heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Farrington, R.B.; Bingham, C.E.

    1986-08-01

    The objectives were to determine the performance of four immersed, ''supply-side'' heat exchangers used in solar domestic-hot-water systems; to examine the effects of flow rate, temperature difference, and coil configuration on performance; and to develop a simple model to predict the performance of immersed heat exchangers. We tested four immersed heat exchangers: a smooth coil, a finned spiral, a single-wall bayonet, and a double-wall bayonet. We developed two analyticl models and a simple finite difference model. We experimentally verified that the performance of these heat exchangers depends on the flow rate through them; we also showed that the temperature difference between the heat exchanger's inlet and the storage tank can strongly affect a heat exchanger's performance. We also compared the effects of the heat exchanger's configuration and correlated Nusselt and Rayleigh numbers for each heat exchanger tested. The smooth coil had a higher effectiveness than the others, while the double-wall bayonet had a very low effectiveness. We still do not know the long-term effectiveness of heat exchangers regarding scale accumulation, nor do we know the effects of very low flow rates on a heat exchanger's performance.

  11. Inorganic ion exchangers for nuclear waste remediation

    Energy Technology Data Exchange (ETDEWEB)

    Clearfield, A.; Bortun, A.; Bortun, L.; Behrens, E. [Texas A& M Univ., College Station, TX (United States)

    1997-10-01

    The objective of this work is to provide a broad spectrum of inorganic ion exchangers that can be used for a range of applications and separations involving remediation of groundwater and tank wastes. The authors intend to scale-up the most promising exchangers, through partnership with AlliedSignal Inc., to provide samples for testing at various DOE sites. While much of the focus is on exchangers for removal of Cs{sup +} and Sr{sup 2+} from highly alkaline tank wastes, especially at Hanford, the authors have also synthesized exchangers for acid wastes, alkaline wastes, groundwater, and mercury, cobalt, and chromium removal. These exchangers are now available for use at DOE sites. Many of the ion exchangers described here are new, and others are improved versions of previously known exchangers. They are generally one of three types: (1) layered compounds, (2) framework or tunnel compounds, and (3) amorphous exchangers in which a gel exchanger is used to bind a fine powder into a bead for column use. Most of these exchangers can be regenerated and used again.

  12. Comparison of a Conventional Heat Exchangers with a New Designed Heat Exchanger Experimentally

    Directory of Open Access Journals (Sweden)

    Tansel Koyun

    2014-04-01

    Full Text Available In this study, the air-water heat exchanger designed have been experimentally compared to conventional heat exchangers with and without fin. The same parameters for the three heat exchangers (pump flow, heating power, etc... have been used. In the experiments, speed-flow adjustment has been made to supply heat transfer at an optimum. As a result, during the circulation of water in pipe of the air-water heat exchanger, the corrosion fouling factor has not been formed. In addition, the efficiency of the new designed heat exchanger has been found between fin and finless heat exchanger efficiencies. The results have been shown in the diagrams.

  13. Process for repairing a cryogenic heat exchanger

    International Nuclear Information System (INIS)

    The patent describes a method for repairing leakage-causing cracks and fissures in a cryogenic heat exchanger. It comprises: reducing the interior pressure of the heat exchanger to a level which does not exceed the external pressure upon the hear exchanger while maintaining the temperature of the heat exchanger at a low level relative to the ambient external temperature; applying a curable liquid filler composition to the surface of the heat exchanger proximal the leakage site for seepage into the cracks and fissures located at the leakage. The composition upon a relatively short period of cure at low temperature forming a solid material which fills the cracks and fissures; curing the filler composition; and, applying a sealant composition to the surface of the heat exchanger at the filled leakage site. The sealant composition having long-term sealing performance under cyrogenic conditions

  14. Needs Assessment for Exchange Students in Taiwan

    Directory of Open Access Journals (Sweden)

    Kentei Takaya

    2016-04-01

    Full Text Available With the growing mobility of international students in Asia and the Pacific, Taiwan has become actively involved in promoting international academic exchange. This research investigates the experience of exchange students from the Philippines and mainland China and examines their needs while studying in Taiwan. Qualitative in-depth interviews were conducted with exchange students from the Philippines and mainland China. The findings suggest that while exchange students from the Philippines and mainland China both encountered difficulties during their study in Taiwan, exchange students from the Philippines were inclined to encounter more difficulties compared to those from mainland China due to language difficulties. Based on the findings of this study, suggested support services for future exchange students in Taiwan are outlined to match the needs of students from both Chinese and non-Chinese-speaking backgrounds.

  15. Isotope separation by chemical exchange

    International Nuclear Information System (INIS)

    Nitrogen-15 and oxygen-18 enrichment by chemical exchange in the (NO/NO2) - (H2O/HNO3) system, using a laboratory-scale experimental plant and a cascade for production of two isotopes, is presented. The results obtained from the laboratory-scale plant indicate that optimal flow rate for 15N separation is 1.55 - 1.86 ml/cm2 · min at 8 - 10 M/l nitric acid and 63.4 mg at. oxygen/cm2 · min for 18O separation at 5.8 M/l nitric acid. The height equivalent to a theoretical plate (HETP) of 4.11 - 4.56 cm is in good agreement with other published data for 15N separation using exchange column with Helipak packing. The HETP of 7.74 - 10.58 cm for 18O separation is greater by 20 - 30 % than those presented by Saxena and Taylor for 'Helipak' column packing, but in good agreement with the HRTP published by Borisov et al. on 'Levina' column packing. The HETP obtained for 15N separation by the production plant is in the range 11.5 - 13.8 cm at a flow rate of 2.2 ml HNO3(10M/l)/cm2 · min for the first column and 4.4 - 4.7 cm at a flow rate of 1.66 ml HNO3(10M/l)/cm2 · min for the second column. The optimal flow rate for 18O separation by the production plant is about 63 mg at. oxygen/cm2 · min (1.01 ml HNO3/cm2 · min). Enrichment of 13C and 18O by chemical exchange of carbon dioxide with its monoethanolamine carbamate in methanol and di-n-butylamine carbamate in triethylamine has also been studied, and optimum operating conditions for the separation of 13C in a packed column was determined. The HETP obtained for the 13C in a packed column was determined. The HETP obtained for the 13C separation column is 3.62 - 8.26 cm at a flow rate of 1.1 - 4.0 mmol carbamate/cm2 · min using the same column packing as for 15N and 18O separation, that is, stainless steel triangular wire springs (2.3 x 2.3 x 0.2 mm). (author)

  16. Real Exchange Rate Misalignment in Azerbaijan

    OpenAIRE

    Hasanov, Fakhri; Huseynov, Fariz

    2009-01-01

    By using quarterly data from 2001-2007 and applying various approaches, we estimate real equilibrium exchange rate misalignment for Azerbaijani Manat (AZN) and find that AZN is slightly overvalued. Purchasing power parity approach does not explain the equilibrium exchange rate. However using behavioral and permanent equilibrium exchange rate approaches, we find that the relative productivity, terms of trade, trade openness, net foreign assets, government expenditures and oil prices are the ma...

  17. Execution methods in foreign exchange markets

    OpenAIRE

    Paola Gallardo; Alexandra Heath

    2009-01-01

    Over the past decade or so, the spread of electronic trading has brought about significant changes in the structure of the interbank foreign exchange markets and the relationship between foreign exchange dealers and their clients. This article looks at the way foreign exchange transactions are executed based on the BIS triennial survey data, and provides some quantitative estimates of the importance of electronic trading across transaction types, counterparties and economies.

  18. The Mirage of Fixed Exchange Rates

    OpenAIRE

    Maurice Obstfeld; Kenneth Rogoff

    1995-01-01

    This paper discusses the profound difficulties of maintaining fixed exchange rates in a world of expanding global capital markets. Contrary to popular wisdom, industrialized-country monetary authorities easily have the resources to defend exchange parities against virtually any private speculative attack. But if their commitment to use those resources lacks credibility with markets, the costs to the broader economy of defending an exchange-rate peg can be very high. The dynamic interplay betw...

  19. Sources of Exchange Rate Fluctuations in Thailand

    OpenAIRE

    Siriwutiset, Trin

    2006-01-01

    Exchange rate fluctuations play an important role in economic decision. The rise or falls in exchange rate are one of the most concerned issue in macroeconomics. This study aims to identify the sources of exchange rate fluctuations of the Thai Baht from various types of shocks between 1997:09 and 2002:08 by using VAR (Vector Autoregressive) model. The past empirical studies such as Flood and Rose (1995) argue that the prevailing structural models fail to predict most of the fluctuation ...

  20. Online Ad Assignment with an Ad Exchange

    OpenAIRE

    Dvořák, Wolfgang; Henzinger, Monika

    2016-01-01

    Ad exchanges are becoming an increasingly popular way to sell advertisement slots on the internet. An ad exchange is basically a spot market for ad impressions. A publisher who has already signed contracts reserving advertisement impressions on his pages can choose between assigning a new ad impression for a new page view to a contracted advertiser or to sell it at an ad exchange. This leads to an online revenue maximization problem for the publisher. Given a new impression to sell decide whe...

  1. Fertility as a process of social exchange

    OpenAIRE

    Patrick Heady

    2007-01-01

    By marrying and raising children, parents participate in a system of gift-exchange in which the gifts in question are human lives, and the parties to the exchange are the kinship groups recognised in the society concerned. Fertility reflects the attitudes of prospective parents to their place in the existing system of reproductive exchange, and the relationships of cooperation and authority which it implies - as well as their confidence in the system's continuing viability. It is shown tha...

  2. DETERMINANTS OF REAL EXCHANGE RATE IN ETHIOPIA

    OpenAIRE

    Dr. P.Nandeeswara Rao; Tassew Dufera Tolcha

    2016-01-01

    Real exchange rate has direct effects on trade particularly on international trade and has indirect effects on productions and employments, so it is crucial to understand the factors which determine its variations. This study analyses the main determinants of the real exchange rate and the dynamic adjustment of the real exchange rate following shocks to those determinants using yearly Ethiopian time series data covering the period 1971 to 2010. It begins with a review of literatures on Exchan...

  3. Exchange rate volatility and euro area imports

    OpenAIRE

    Anderton, Robert; Skudelny, Frauke

    2001-01-01

    This paper estimates an import demand function for the euro area vis--vis its main extra-area trading partners which takes into account the possible impact of both intra- and extra-euro area exchange rate uncertainty. We derive a theoretical model which captures various mechanisms by which exchange rate volatility may influence the demand for extra-euro area imports. If importers are risk averse, the model predicts not only a negative effect of exchange rate volatility, but also substitution ...

  4. Modelling of Multistream LNG Heat Exchangers

    OpenAIRE

    Soler Fossas, Joan

    2011-01-01

    The main goal of this thesis is to find out if a liquefied natural gas multistream heat exchanger numerical model is achievable. This should include several features usually neglected in nowadays available heat exchanger models, such as flow maldistribution, changes in fluid properties and heat exchanger dynamic behaviour. In order to accomplish that objective a simpler case is modelled. Efforts are put in achieving numerical stability.A counter flow natural gas and mixed refrigerant heat exc...

  5. A Computational Theory of Willingness to Exchange

    OpenAIRE

    Lunn, Pete; Lunn, Mary

    2014-01-01

    A new model of exchange is presented following Marr's conception of a "computational theory". The model combines assumptions from perceptual theory and economic theory to develop a highly generalised formal model. The approach departs from previous models by focussing not on how ownership alters preferences, but instead on difficulties inherent in the process of exchange in real markets. Agents treat their own perceptual uncertainty when valuing a potential exchange item as a signal regarding...

  6. Defining Service and Non-Service Exchanges

    OpenAIRE

    Sandeep Kayastha

    2011-01-01

    Clear-cut classification of exchanges into services and non-services is vital for governments to estimate contributions of service and other sectors to national incomes, for businesses to know their tax and tortious liabilities and for researchers to develop new theories and concepts of services. Unfortunately, the definitions and schema they use to classify exchanges have serious shortcomings. This paper proposes a legal approach to classify exchanges. Whereas existing definitions and schema...

  7. Comparing Forecast Performance of Exchange Rate Models

    OpenAIRE

    Lillie Lam; Laurence Fung; Ip-wing Yu

    2008-01-01

    Exchange-rate movement is regularly monitored by central banks for macroeconomic-analysis and market-surveillance purposes. Notwithstanding the pioneering study of Meese and Rogoff (1983), which shows the superiority of the random-walk model in out-of-sample exchange-rate forecast, there is some evidence that exchange-rate movement may be predictable at longer time horizons. This study compares the forecast performance of the Purchasing Power Parity model, Uncovered Interest Rate Parity model...

  8. Authenticated tree parity machine key exchange

    OpenAIRE

    Volkmer, Markus; Schaumburg, André

    2004-01-01

    The synchronisation of Tree Parity Machines (TPMs), has proven to provide a valuable alternative concept for secure symmetric key exchange. Yet, from a cryptographer's point of view, authentication is at least as important as a secure exchange of keys. Adding an authentication via hashing e.g. is straightforward but with no relation to Neural Cryptography. We consequently formulate an authenticated key exchange within this concept. Another alternative, integrating a Zero-Knowledge protocol in...

  9. Exchange of quantum states between coupled oscillators

    OpenAIRE

    Portes Jr., D.; Rodrigues, H.; Duarte, S. B.; Baseia, B.

    2007-01-01

    Exchange of quantum states between two interacting harmonic oscillator along their evolution time is discussed. It is analyzed the conditions for such exchange starting from a generic initial state and demonstrating that the effect occurs exactly only for the particular states C0|0>+Cn|N>, which includes the interesting qubits components |0>,|1>. It is also determined the relation between the coupling constant and characteristic frequencies of the oscillators to have the complete exchange.

  10. A Financial Model of Foreign Exchange Exposure

    OpenAIRE

    Christine R Hekman

    1985-01-01

    The paper describes a model of foreign exchange exposure. This is defined as the sensitivity of a specific investment's value in reference currency to changes in exchange rate forecasts. This sensitivity may result because some share of the investment cash flows are denominated in foreign currency. Alternatively, a share of cash flows denominated in reference currency which are affected by future exchange rates can also generate sensitivity.The model integrates a general corporate valuation f...

  11. Fuel exchanger for nuclear ships

    International Nuclear Information System (INIS)

    Purpose: To prevent enviromental contamination landing radioactive materials from the inside of a ship. Constitution: A provisional cabin having a shape covering a reactor hatch and a hatch cover is disposed on the upper deck of a ship body. A ceiling shutter is disposed to the cabin. A protection cylinder having a shutter and a filter fan is attached on the cabin. Materials to be discharged out of the ship are transported to a fuel exchange tower on land by using a crane while being contained in the protection cylinder with the shutter being closed. The protection cylinder is connected by means of a wire rope to a loop-wheel machine which disposed on the trolly of a crane. While the bellows through which the suspending wire for the discharged products passes is perforated, since the inside of the cylinder is depressurized by a filter fan, there is no air leakage through the perforation to the outside. (Ikeda, J.)

  12. Stratified economic exchange on networks

    CERN Document Server

    Herrera, J L; Tucci, K

    2010-01-01

    We investigate a model of stratified economic interactions between agents when the notion of spatial location is introduced. The agents are placed on a network with near-neighbor connections. Interactions between neighbors can occur only if the difference in their wealth is less than a threshold value that defines the width of the economic classes. By employing concepts from spatiotemporal dynamical systems, three types of patterns can be identified in the system as parameters are varied: laminar, intermittent and turbulent states. The transition from the laminar state to the turbulent state is characterized by the activity of the system, a quantity that measures the average exchange of wealth over long times. The degree of inequality in the wealth distribution for different parameter values is characterized by the Gini Coefficient. High levels of activity are associated to low values of the Gini coefficient. It is found that the topological properties of the network have little effect on the activity of the ...

  13. On the Foundations of Key Exchange

    OpenAIRE

    Brzuska, Christina

    2013-01-01

    Key exchange protocols allow two parties to agree on a shared secret over an untrusted channel. A huge number of scientific works on key exchange have been published since the discovery of the first key exchange protocol, designed in 1976 by Diffie and Hellman [DH76]. The most prominent of these works is the game-based security model by Bellare and Rogaway [BR93], published in 1993 and, today, known as the "golden standard" for the security of key exchange protocols. The main purpose of k...

  14. Efficient Three Party Key Exchange Protocol

    OpenAIRE

    H. K. Pathak; Manju Sanghi

    2012-01-01

    Key exchange protocols allow two or more parties communicating over a public network to establish a common secret key called a session key. In 1976, Diffie and Hellman proposed the first practical key exchange (DH key exchange) protocol.  In 2005, Abdalla and  Pointcheval suggested  a new variation  of the computational   DH assumption  called chosen based computational Diffie Hellman (CCDH)  and presented  simple password based authenticated  key exchange protocols.  Since then several three...

  15. Designing health insurance exchanges: key decisions.

    Science.gov (United States)

    Starc, Amanda; Kolstad, Jonathan T

    2012-02-01

    A cornerstone of health care reform is the establishment of state-level insurance exchanges where individuals and small businesses can purchase health insurance in an online marketplace. States are required to develop an exchange by 2014, or participate in a federal one. The exchanges will help people without employer-sponsored insurance find and choose a health plan to meet their needs. This Issue Brief reviews the experience of Massachusetts in developing a health insurance exchange and offers policymakers guidance on key features and likely consumer responses. PMID:22451998

  16. Data Exchange Management Information System (DEMIS)

    Data.gov (United States)

    Social Security Administration — DEMIS combines a database (Operational Data Store - ODS) of data exchange-related Management Information (MI) with the agency's querying and reporting utility, the...

  17. Micro tube heat exchangers for Space Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mezzo fabricates micro tube heat exchangers for a variety of applications, including aerospace, automotive racing, Department of Defense ground vehicles,...

  18. Foreign Exchange Risk in International Transactions

    Directory of Open Access Journals (Sweden)

    Florentina-Olivia Balu

    2007-03-01

    In this article we will focus on forward and futures contracts for managing foreign exchange risk. A forward is a contract to buy or sell currency at an agreed upon exchange rate at a specific date in the future. Futures are similar to forwards except that they’re traded on exchanges which specify settlement dates. Also we make some recommendations related to the foreign exchange risk-management practices that are useful for companies involved in international trade and for financial institutions interested in providing hedging products to these companies.

  19. Exchange interactions in Fe/Y multilayers

    International Nuclear Information System (INIS)

    The magnetization of Fe/Y multilayers has been measured as a function of temperature. A bulk-like T 3/2 temperature dependence of the magnetization is observed for all multilayers in the temperature range 5-300 K. The spin-wave constant B is found to decrease inversely with t Fe. A simple theoretical model with exchange interactions only, and with non-interacting magnons, has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction J b, surface exchange interaction J s and the interlayer exchange interaction J I for various Fe layer thicknesses have been obtained

  20. The response of the Johannesburg stock exchange to changes in exchange rate regimes

    OpenAIRE

    Paul-Francois Muzindutsi

    2013-01-01

    This paper used Granger Causality test and descriptive statistics analysis to examine the response of the South African stock market to different exchange rate regimes from 1978 to 2008. The analysis of the history of the exchange rate regimes in South Africa showed that the flexibility was introduced in 1979 but the exchange rate shocks of great magnitude appeared during the period of the free-floating exchange rate system (1995-2008). Results reported in this paper revealed that the respons...

  1. Exchange Rate Exposure and Exchange Rate Risk Management: The case of Japanese exporting firms

    OpenAIRE

    Ito, Takatoshi; KOIBUCHI Satoshi; SATO Kiyotaka; SHIMIZU Junko

    2013-01-01

    In this paper, we estimate Japanese firms' exchange rate exposure and investigate the impact of exchange rate risk management on them. By using the results of the questionnaire survey sent to all Tokyo Stock Exchange listed firms in 2009, we conduct empirical analysis to investigate whether each risk management tool—financial and operational hedging, the choice of invoice currency, and the price revision strategy (pass-through)—specifically affects their foreign exchange exposure. As a result...

  2. Experimental research on heat transfer in a coupled heat exchanger

    OpenAIRE

    Liu Yin; Ma Jing; Zhou Guang-Hui; Guan Ren-Bo

    2013-01-01

    The heat exchanger is a devise used for transferring thermal energy between two or more different temperatures. The widespreadly used heat exchanger can only achieve heat exchange between two substances. In this paper, a coupled heat exchanger is proposed, which includes a finned heat exchanger and a double pipe heat exchanger, for multiple heat exchange simultaneously. An experiment is conducted, showing that the average heating capacity increases more tha...

  3. Australian Universities' Strategic Goals of Student Exchange and Participation Rates in Outbound Exchange Programmes

    Science.gov (United States)

    Daly, Amanda; Barker, Michelle

    2010-01-01

    International student exchange programmes are acknowledged as one aspect of a broader suite of internationalisation strategies aimed at enhancing students' intercultural understanding and competence. The decision to participate in an exchange programme is dependent on both individual and contextual factors such as student exchange policies and…

  4. Exchange Studies as Actor-Networks: Following Korean Exchange Students in Swedish Higher Education

    Science.gov (United States)

    Ahn, Song-ee

    2011-01-01

    This article explores how Korean exchange students organized their studies during exchange programs in Swedish higher education. For most students, the programs became a disordered period in relation to their education. The value of exchange studies seems mainly to be extra-curricular. Drawing upon actor network theory, the article argues that the…

  5. {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)

  6. 76 FR 41676 - Retail Foreign Exchange Transactions

    Science.gov (United States)

    2011-07-15

    ... Transactions and Intermediaries, 75 FR 55410 (Sept. 10, 2010) (``Final CFTC Retail Forex Rule''). The CFTC had... rules. See Retail Foreign Exchange Transactions, 76 FR 40779 (July 12, 2011) (``Final FDIC Retail Forex.... See Exchange Act Release No. 63452 (Dec. 7, 2010), 75 FR 80174 (Dec. 21, 2010). Because...

  7. The Story of Foreign Trade and Exchange.

    Science.gov (United States)

    Fan, Cedric

    This comic-style booklet is one of a series of educational booklets published by the Federal Reserve Bank of New York. The booklet uses everyday language and lively illustrations to explain the benefits of international trade; the effects of tariffs and quotas; the significance of foreign exchange rates; how the foreign exchange market facilities…

  8. Explaining the Transition Between Exchange Rate Regimes

    OpenAIRE

    Masson, Paul; RUGE-MURCIA, Francisco J.

    2003-01-01

    This paper studies the transition between exchange rate regimes using a Markov chain model with time-varying transition probabilities. The probabilities are parameterized as nonlinear functions of variables suggested by the currency crisis and optimal currency area literature. Results using annual data indicate that inflation, and to a lesser extent, output growth and trade openness help explain the exchange rate regime transition dynamics.

  9. CAD-CAM data exchange pilot project

    Energy Technology Data Exchange (ETDEWEB)

    Hintz, J.; Williams, D.

    1986-03-01

    CAD-CAM data were exchanged between dissimilar CAD systems and the information was used to fabricate three parts. Problems were identified and solutions were proposed or implemented in the area of translation methods, data verification, CAD drawing conventions, and data handling. Additional software needed for productive data exchange has been identified.

  10. 12 CFR 614.4900 - Foreign exchange.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Foreign exchange. 614.4900 Section 614.4900... Cooperatives and Agricultural Credit Banks Financing International Trade § 614.4900 Foreign exchange. (a... speculative futures transactions by eligible borrowers in foreign currencies. The bank may engage, on...

  11. Pan-American Teletandem Language Exchange Project

    Science.gov (United States)

    Castillo-Scott, Aurora

    2015-01-01

    This paper describes a TeleTandem language exchange project between English speaking Spanish students at Georgia College, USA, and Spanish speaking English students at Universidad de Concepción, Chile. The aim of the project was to promote linguistic skills and intercultural competence through a TeleTandem exchange. Students used Skype and Google…

  12. Isotope exchange reactions in hydrogen mixtures

    International Nuclear Information System (INIS)

    The rates of isotopic exchange for the excited states of muonic hydrogen are calculated as functions of collision energy. Ground state population q1s for different collision energies, target densities and isotope concentrations is obtained. It is shown that for principal quantum numbers n > 5 the isotopic exchange still considerably influences the value of q1s. (author)

  13. Ion exchange in the nuclear industry

    International Nuclear Information System (INIS)

    Ion exchange is used in nearly every part of the nuclear fuel cycle -- from the purification of uranium from its ore to the final recovery of uranium and transmutation products. Ion exchange also plays a valuable role in the management of nuclear wastes generated in the fuel cycle

  14. Staff Exchange or Legal Alien Programs

    DEFF Research Database (Denmark)

    Jørgensen, Rune Nørgaard

    2016-01-01

    SRA would very much like to support the exchange of best practice between members throughout the year and the Membership Committee is presently looking into the opportunities for a Staff Exchange or Legal Alien Program. However the International Section has already had the chance to provide this...

  15. A formal model of fair exchange protocols

    Institute of Scientific and Technical Information of China (English)

    QING Sihan; LI Gaicheng

    2005-01-01

    Based on the study of existing fair exchange protocols, this paper sets up an accurate formal model by stepwise refinement. In the process of refinement an unreliable channel is employed to simulate an attack behavior. The model provides a novel formal definition of exchanged items, and presents the formal goals for fairness, accountability,etc., reflecting the inherent requirements for fair exchange protocols across-the-board. In order to check, prove, and design fair exchange protocols effectively and efficiently, the model puts forward a novel property of abuse-freeness which applies to all fair exchange protocols, gives a formal definition for trust strand of the third party, and presents general criteria of designing a secure and effective fair exchange protocol. Taking a typical fair exchange protocol as an example, this paper presents the analysis steps of fair exchange protocols appealing to our model. An unknown attack is uncovered. The analysis reveals the process of a complete attack, discovering deeper reasons for causing an attack.Finally, we modify the flawed protocol and the revised protocol ensures the desirable properties.

  16. Experimental evaluation of vibrations in heat exchangers

    International Nuclear Information System (INIS)

    Flow induced vibrations may produce damage of heat exchangers, condensers and steam generators tubes. To evaluate this problem a set of tests were developed to know the real support state of the tubes, which have great influence on the vibration response. This paper include a description of the tests and the results obtained applying them on a heat exchanger equipment. (author)

  17. Microsoft Exchange Server PowerShell cookbook

    CERN Document Server

    Andersson, Jonas

    2015-01-01

    This book is for messaging professionals who want to build real-world scripts with Windows PowerShell 5 and the Exchange Management Shell. If you are a network or systems administrator responsible for managing and maintaining Exchange Server 2013, you will find this highly useful.

  18. An approach for message exchange using archetypes.

    Science.gov (United States)

    Moraes, João L C; Souza, Wanderley L; Cavalini, Luciana T; Pires, Luís F; Prado, Antonio F

    2013-01-01

    The application of ICT on the whole range of health sector activities, known as e-health, can simplify the access to health care services and will only be acceptable for realistic scenarios if it supports efficient information exchange amongst the caregivers and their patients. The aim of this paper is present an approach for message exchange to realistic scenarios. PMID:23920910

  19. Heat Exchanger Lab for Chemical Engineering Undergraduates

    Science.gov (United States)

    Rajala, Jonathan W.; Evans, Edward A.; Chase, George G.

    2015-01-01

    Third year chemical engineering undergraduate students at The University of Akron designed and fabricated a heat exchanger for a stirred tank as part of a Chemical Engineering Laboratory course. The heat exchanger portion of this course was three weeks of the fifteen week long semester. Students applied concepts of scale-up and dimensional…

  20. Contrasting styles of oxygen isotope exchange

    OpenAIRE

    Valley, J. W.; Eiler, J. M.; Kohn, M.J.; Spicuzza, M.J; Baumgartner, L. P.; Elsenheimer, D.; Graham, C. M.

    1994-01-01

    Exchange of oxygen isotopes encrypts a sensitive record of the thermal evolution and fluid-exchange history of igneous and metamorphic rocks. Deciphering this record requires measurement of isotope ratios at an appropriate scale together with understanding of the processes involved: diffusion, recrystallization, new mineral growth, and fluid flow.