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  • correlation functions  (3)
  • oxidative stress  (3)
  • Anther dimensions  (2)
  • Springer  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Letters in mathematical physics 42 (1997), S. 261-270 
    ISSN: 1573-0530
    Keywords: block renormalization group ; correlation functions ; ferminos.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract Inspired by a decomposition of the lattice Laplacian operator into massive terms (coming from the use of the block renormalization group transformation for bosonic systems), we establish a telescopic decomposition of the Dirac operator into massive terms, with a property named ‘orthogonality between scales’. Making a change of Grassmann variables and writing the initial fields in terms of the eigenfunctions of the operators related to this decomposition, we propose a multiscale structure for the generating function of interacting fermions. Due to the orthogonality property we obtain simple formulas, establishing a trivial link between the correlation functions and the effective potential theories. In particular, for the infrared analysis of some asymptotically free models, the two point correlation function is written as a dominant term (decaying at large distances as the free propagator) plus a correction with faster decay, and the study of both terms is straightforward once the effective potential theory is controlled.
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  • 2
    ISSN: 1572-9613
    Keywords: correlation functions ; fermions ; infrared analysis ; tridimensional Gross–Neveu model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a multiscale formalism for fermionic systems (with a smooth UV cutoff ) establishing a trivial link between the correlation functions and the effective potential flow, and study the k-point truncated functions of the tridimensional Gross–Neveu model. A new efficient method is used to bound these correlation functions and show polynomial tree decay for long distances. We are guided by a block lattice mechanism with a property of orthogonality between terms in different scales, which leads to simple formulas for the correlations.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 9 (1996), S. 228-232 
    ISSN: 1432-2145
    Keywords: Male transmission ; Anther dimensions ; Pollen dimensions ; Pistil dimensions ; Sesame ; Sesamum indicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Measurements of anther (length, width, depth), pollen grain (percent fertility, polar diameter, equatorial diameter, polar diameter/equatorial diameter ratio, volume) and pistil (stigma length, style length, ovary length, total pistil length, stigma width, style width, ovary width) were taken on 12 diverse sesame (Sesamum indicum L.) genotypes on each of four collection dates in 1994. Highly significant differences among genotype means were obtained for all characters except polar diameter. Highly significant differences among environment (collection date) means were found for ten of the 15 characters measured. Highly significant genotype x environment interactions were obtained for all characters except anther length. For the anther characters measured, relatively high repeatability values were found, ranging from 99.8% for length to 87.6% for depth. For the pollen grain characters measured, the repeatability values ranged from 67.6% for percent fertility to 23.1% for polar diameter. For the pistil characters measured, the repeatability values ranged from 94.0% for style width to 49.6% for total pistil length. These results indicate that genotype and environment influence anther, pollen grain and pistil characters. Variation in some of these morphological aspects could influence the consistency and interpretation of male transmission studies on both the applied and evolutionary levels.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 9 (1996), S. 228-232 
    ISSN: 1432-2145
    Keywords: Key words Male transmission ; Anther dimensions ; Pollen dimensions ; Pistil dimensions ; Sesame ; Sesamum indicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Measurements of anther (length, width, depth), pollen grain (percent fertility, polar diameter, equatorial diameter, polar diameter/equatorial diameter ratio, volume) and pistil (stigma length, style length, ovary length, total pistil length, stigma width, style width, ovary width) were taken on 12 diverse sesame (Sesamum indicum L.) genotypes on each of four collection dates in 1994. Highly significant differences among genotype means were obtained for all characters except polar diameter. Highly significant differences among environment (collection date) means were found for ten of the 15 characters measured. Highly significant geno- type × environment interactions were obtained for all characters except anther length. For the anther characters measured, relatively high repeatability values were found, ranging from 99.8% for length to 87.6% for depth. For the pollen grain characters measured, the repeatability values ranged from 67.6% for percent fertility to 23.1% for polar diameter. For the pistil characters measured, the repeatability values ranged from 94.0% for style width to 49.6% for total pistil length. These results indicate that genotype and environment influence anther, pollen grain and pistil characters. Variation in some of these morphological aspects could influence the consistency and interpretation of male transmission studies on both the applied and evolutionary levels.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 201 (1999), S. 17-24 
    ISSN: 1573-4919
    Keywords: Saccharomyces cerevisiae ; atomic force microscope ; bioscope ; organic synthesis ; molecular biology ; oxidative stress ; pore enlargement ; cell wall ; baker's yeast ; biotechnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract We imaged pores on the surface of the cell wall of three different industrial strains of Saccharomyces cerevisiae using atomic force microscopy. The pores could be enlarged using 10 mM diamide, an SH residue oxidant that attacks surface proteins. We found that two strains showed signs of oxidative damage via changes in density and diameter of the surface pores. We found that the German strain was resistant to diamide induced oxidative damage, even when the concentration of the oxidant was increased to 50 mM. The normal pore size found on the cell walls of American strains had diameters of about 200nm. Under conditions of oxidative stress the diameters changed to 400nm. This method may prove to be a useful rapid screening process (45-60 min) to determine which strains are oxidative resistant, as well as being able to screen for groups of yeast that are sensitive to oxidative stress. This rapid screening tool may have direct applications in molecular biology (transference of the genes to inside of living cells) and biotechnology (biotransformations reactions to produce chiral synthons in organic chemistry.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Molecular biology reports 24 (1997), S. 35-38 
    ISSN: 1573-4978
    Keywords: cadmium ; ubiquitin ; HSP70 ; glutathione ; protein mixed disulfides ; oxidative stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ubiquitin protein conjugates are commonly detected in neuronal brain inclusions of patients with neurodegenerative disorders. The failure to eliminate the ubiquitin-protein deposits in the degenerating neurons may result from changes in the activity of the ubiquitin/ATP-dependent proteolytic pathway. This proteolytic pathway plays a major role in the degradation of short lived, abnormal and denatured proteins. Cadmium is a potent cell poison and is known to affect the ubiquitin pathway and to cause oxidative stress. Increases in protein mixed-disulfides (Pr-SSG) and decreases in glutathione (GSH) are often used as markers of oxidative stress. To investigate the relationship between the ubiquitin pathway and cellular glutathione (GSH), we treated HT4 cells (a mouse neuronal cell line) and rat mesencephalic primary cultures with different concentrations of the heavy metal. We observed marked increases in Pr-SSG as well as decreases in GSH, after exposure of HT4 cells or primary mesencephalic cultures to Cd2+. Furthermore, our results show that Cd2+ induced the accumulation of ubiquitinated proteins. Detection was by Western blotting of total cell extracts probed with antibodies that recognize ubiquitin-protein conjugates. These results suggest that the ubiquitin-pathway is closely involved in the cell response to cadmium-mediated oxidative stress. Abbreviations: GSH – glutathione; GSSG – glutathione disulfide; Pr-SSG – protein mixed disulfides.
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  • 7
    ISSN: 1573-4978
    Keywords: cadmium ; hydrogen peroxide ; oxidative stress ; ubiquitin pathway ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One of the hallmarks of neurodegeneration is the accumulation of ubiquitinated proteins in intraneuronal inclusions in the cytosol, endosomes/lysosomes and nuclei of affected cells. The relationship between inclusion production and cell viability is not well understood. On the one hand inclusions may be beneficial and result from an attempt of the cell to isolate a subclass of ubiquitinated proteins that are not effectively degraded. On the other hand, the inclusions may impede normal cell function contributing to cell death. To address this issue we treated mouse neuronal HT4 cells with three toxic agents cadmium, zinc and H2O2, and investigated their effects on glutathione homeostasis, on accumulation of ubiquitinated proteins and on cell viability. The three treatments induce oxidative stress manifested by decreases in glutathione (GSH) and/or increases in protein mixed disulfides (PrSSG). After an overnight recovery period in the absence of treatment, GSH and PrSSG were restored to almost normal levels. However, the levels of ubiquitinated proteins were significantly increased, and cell viability was sharply reduced. These results suggest that the ubiquitin-proteasome pathway is recruited for removal of proteins that are oxidatively modified. However, if the ubiquitinated proteins are not efficiently degraded, they accumulate in the cell and contribute to a decrease in cell viability.
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  • 8
    ISSN: 1572-9613
    Keywords: Orthogonality between scales ; correlation functions ; block renormalization group ; dipole gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Exact formulas for the correlation functions of lattice scalar field models in Zd,d⩾3, such as the dipole gas and anharmonic crystal are derived in terms of the effective action generated aftern applications of the block renormalization group transformation. Utilizing the orthogonality between different momentum scales (relations due to the wavelets implicit in the structure of the block renormalization group transformation), the formulas are quite simple, isolate the dominant term, and, in the thermodynamic andn→∞ limits, reduce the analysis to local estimates of the effective action. Based on a large-small field analysis, the two-point function is determined and it is shown how to extend the results to general correlations. The results proved here show the usefulness of the “orthogonality-of-scales” property for the study of correlation functions.
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