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  • Trp fluorescence  (3)
  • concept drift  (2)
  • Springer  (5)
  • American Geophysical Union
  • Cell Press
  • MDPI
  • Wiley
  • 1990-1994  (5)
  • 1935-1939
Collection
Keywords
Publisher
  • Springer  (5)
  • American Geophysical Union
  • Cell Press
  • MDPI
  • Wiley
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Tracking Drifting Concepts By Minimizing Disagreements (1994)
    Springer
    Machine learning 14 (1994), S. 27-45 
    Details
    ISSN: 0885-6125
    Keywords: Computational learning theory ; concept drift ; concept learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this paper we consider the problem of tracking a subset of a domain (called the target) which changes gradually over time. A single (unknown) probability distribution over the domain is used to generate random examples for the learning algorithm and measure the speed at which the target changes. Clearly, the more rapidly the target moves, the harder it is for the algorithm to maintain a good approximation of the target. Therefore we evaluate algorithms based on how much movement of the target can be tolerated between examples while predicting with accuracy ε Furthermore, the complexity of the class $$\mathcal{H}$$ of possible targets, as measured by d, its VC-dimension, also effects the difficulty of tracking the target concept. We show that if the problem of minimizing the number of disagreements with a sample from among concepts in a class $$\mathcal{H}$$ can be approximated to within a factor k, then there is a simple tracking algorithm for $$\mathcal{H}$$ which can achieve a probability ε of making a mistake if the target movement rate is at most a constant times $$ \in ^2 /(k(d + k)\ln \frac{1}{ \in })$$ , where d is the Vapnik-Chervonenkis dimension of $$\mathcal{H}$$ . Also, we show that if $$\mathcal{H}$$ is properly PAC-learnable, then there is an efficient (randomized) algorithm that with high probability approximately minimizes disagreements to within a factor of 7d + 1, yielding an efficient tracking algorithm for $$\mathcal{H}$$ which tolerates drift rates up to a constant times $$ \in ^2 /(d^2 \ln \frac{1}{ \in })$$ . In addition, we prove complementary results for the classes of halfspaces and axis-aligned hyperrectangles showing that the maximum rate of drift that any algorithm (even with unlimited computational power) can tolerate is a constant times ε2/d.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022694620923
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  • 2
    Electronic Resource
    Electronic Resource
    Tracking drifting concepts by minimizing disagreements (1994)
    Springer
    Machine learning 14 (1994), S. 27-45 
    Details
    ISSN: 0885-6125
    Keywords: Computational learning theory ; concept drift ; concept learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this paper we consider the problem of tracking a subset of a domain (called thetarget) which changes gradually over time. A single (unknown) probability distribution over the domain is used to generate random examples for the learning algorithm and measure the speed at which the target changes. Clearly, the more rapidly the target moves, the harder it is for the algorithm to maintain a good approximation of the target. Therefore we evaluate algorithms based on how much movement of the target can be tolerated between examples while predicting with accuracy ε. Furthermore, the complexity of the classH of possible targets, as measured byd, its VC-dimension, also effects the difficulty of tracking the target concept. We show that if the problem of minimizing the number of disagreements with a sample from among concepts in a classH can be approximated to within a factork, then there is a simple tracking algorithm forH which can achieve a probability ε of making a mistake if the target movement rate is at most a constant times ε2/(k(d +k) ln 1/ε), whered is the Vapnik-Chervonenkis dimension ofH. Also, we show that ifH is properly PAC-learnable, then there is an efficient (randomized) algorithm that with high probability approximately minimizes disagreements to within a factor of 7d + 1, yielding an efficient tracking algorithm forH which tolerates drift rates up to a constant times ε2/(d 2 ln 1/ε). In addition, we prove complementary results for the classes of halfspaces and axisaligned hyperrectangles showing that the maximum rate of drift that any algorithm (even with unlimited computational power) can tolerate is a constant times ε2/d.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00993161
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  • 3
    Electronic Resource
    Electronic Resource
    Energy transfer from tryptophan residues of proteins to 8-anilinonaphthalene-1-sulfonate (1994)
    Springer
    The protein journal 13 (1994), S. 635-640 
    Details
    ISSN: 1573-4943
    Keywords: Trp fluorescence ; energy transfer ; 8-anilinonaphthalene sulfonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The binding of the apolar fluorescent dye 8-anilinonaphthalene-1-sulfonate (ANS) to bovine serum albumin (BSA), phospholipase A2 (PLA2), ovalbumin, lysozyme, cobrotoxin and N-acetyltryptophanamide was used to assess the factors affecting the efficiency of energy transfer from Trp residues to the ANS molecule. We found that the efficiency of energy transfer from Trp residues to ANS was associated with the ability of proteins to enhance the ANS fluorescence. At the same molar concentration of protein, BSA enhanced ANS fluorescence most among these proteins; its Trp fluorescence was drastically quenched by the addition of ANS. Fluorescence enhancement of ANS in PLA2-ANS complex increased upon addition of Ca2+ or change of the buffer to acidicpH, resulting in a higher efficiency of energy transfer from Trp residues to ANS. There was limited ANS fluorescence enhancement with ovalbumin, lysozyme, cobrotoxin, and N-acetyltryptophanamide and a less efficient quenching in Trp fluorescence. The capabilities of proteins for binding with ANS correlated with the decrease in their Trp fluorescence being quenching by ANS. However, the microenvironment surrounding Trp residues of proteins did not affect the energy transfer. Based on these results, the factors that affected the energy transfer from Trp residues to ANS are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01890462
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  • 4
    Electronic Resource
    Electronic Resource
    Structural determinants of the intrinsic fluorescence emission in notexin and phospholipase A2 enzymes (1993)
    Springer
    The protein journal 12 (1993), S. 579-583 
    Details
    ISSN: 1573-4943
    Keywords: Notexin ; phospholipase A2 ; Trp fluorescence ; fluorescence quenching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Fluorescence measurements of the homologous proteins, notexin and PLA2 enzymes fromNaja naja atra, Naja nigricollis, and Hemachatus haemachatus venoms, showed that the wavelength of maximum emission and the quantum yield of their intrinsic fluorescence emission spectra were different. To verify the factors which affected their fluorescence characteristics, the dynamics of tryptophan residues in those homologous proteins were studied by quenching with acrylamide, iodide, and cesium. The degrees of exposure of tryptophanyl groups in notexin and PLA2 enzymes assessed by acrylamide quenching were found to be the major factor that determined their fluorescence characteristics. However, the positively charged groups surrounding tryptophan residues of PLA2 enzymes fromN. naja atra andN. nigricollis venoms might affect the quantum yield of their fluorophores. Tryptophan residues of notexin were in an environment with less fluctuation, which did not allow free diffusion of ionic quencher. This might render its typtophan residues to fluoresce at a shorter wavelength. These results suggested that the structural determinants affecting the intrinsic fluorescence emission of homologous proteins can be easily assessed by quenching studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01025122
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  • 5
    Electronic Resource
    Electronic Resource
    The essentiality of B chain in stabilizing the structure of the A chain in β1-bungarotoxin fromBungarus multicinctus venom (1994)
    Springer
    The protein journal 13 (1994), S. 233-236 
    Details
    ISSN: 1573-4943
    Keywords: Snake venom ; Trp fluorescence ; Β 1-bungarotoxin ; role of the B chain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The dynamic of Trp residue inΒ 1-bungarotoxin (gb 1-Bgt), the A chain ofΒ 1-Bgt and phospholipase A2 (PLA2) was assessed by fluorescence measurement. Acrylamide quenching studies showed that the exposure degree of the Trp in PLA2 is higher than the Trp inΒ 1-Bgt. The Trp ofΒ 1-Bgt had a higher accessibility for iodide, reflecting that the basic nature of the B chain might exert an attractive electrostatic force for iodide and increase the susceptibility of Trp in the A chain to iodide. Removal of the B chain ofΒ 1-Bgt did not significantly affect the exposure degree of Trp in the A chain. Alternatively, the polarity of the environment around the Trp and the hydrophobic character of ANS and substrate binding sites in the separated A chain changed. Measurement of Trp fluorescence with increasing temperature showed that the stability of structure ofΒ 1-Bgt was higher than those of the separated A chain and PLA2. These results suggest that the B chain might interact with the A chain and stabilize the conformation of the A chain inΒ 1-Bgt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01891981
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