Polymer Knot in Solution near the θ Point

2020 ◽  
Vol 124 (13) ◽  
pp. 2723-2729 ◽  
Author(s):  
Xiaofei Xu ◽  
Xiangxiang Gao
Keyword(s):  
2019 ◽  
Vol 35 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Noboru Iwata ◽  
Akizumi Tsutsumi ◽  
Takafumi Wakita ◽  
Ryuichi Kumagai ◽  
Hiroyuki Noguchi ◽  
...  

Abstract. To investigate the effect of response alternatives/scoring procedures on the measurement properties of the Center for Epidemiologic Studies Depression Scale (CES-D) which has the four response alternatives, a polytomous item response theory (IRT) model was applied to the responses of 2,061 workers and university students (1,640 males, 421 females). Test information functions derived from the polytomous IRT analyses on the CES-D data with various scoring procedures indicated that: (1) the CES-D with its standard (0-1-2-3) scoring procedure should be useful for screening to detect subjects with “at high-risk” of depression if the θ point showing the highest information corresponds to the cut-off point, because of its extremely higher information; (2) the CES-D with the 0-1-1-2 scoring procedure could cover wider range of depressive severity, suggesting that this scoring procedure might be useful in cases where more exhaustive discrimination in symptomatology is of interest; and (3) the revised version of CES-D with replacing original positive items into negatively revised items outperformed the original version. These findings have never been demonstrated by the classical test theory analyses, and thus the utility of this kind of psychometric testing should be warranted to further investigation for the standard measures of psychological assessment.


1990 ◽  
Vol 23 (11) ◽  
pp. 3013-3019 ◽  
Author(s):  
James Patton Downey ◽  
Jeffrey Kovac

2020 ◽  
Vol 102 (3) ◽  
Author(s):  
Simone Franchini ◽  
Riccardo Balzan
Keyword(s):  

1967 ◽  
Vol 40 (1) ◽  
pp. 1-35 ◽  
Author(s):  
D. Patterson

Abstract An excellent new text, “Macromolecules in Solution,” by A. Morawetz emphasizes advances in polymer solution thermodynamics since publication of standard texts such as those of Tompa and Flory. Detailed development of the subject from 1950 may be followed in articles on polymers in Annual Reviews of Physical Chemistry, and particularly in the articles appearing every three years specially devoted to solution properties: Flory and Krigbaum (1951), Wall and Hiller (1954), Hermans (1957), Casassa (1960) and Hughes and von Frankenberg (1963). The articles on solutions of non-electrolytes are, of course, always of general interest and often deal directly with polymer solutions or mixtures of chain molecules. Because of this very satisfactory situation, the author has decided that the best thing is to review in more detail the single topic which is most interesting to him. This is the thermodynamics of non-dilute solutions where it is usually supposed that the quasi-lattice theories of the 40's are quite adequate at concentrations greater than about 10 per cent. For fifteen years or so, interest has centered on very dilute polymer solutions and the dimensions of isolated polymer molecules, particularly at temperatures near the θ point. Increasingly difficult mathematical problems have followed the McMillan-Mayer comparison of solutions and imperfect gases first applied to polymer solutions by Zimm and Stockmayer. Polymer solution thermodynamics seems to have moved far beyond the intuitive questions of Meyer as to why a polymer solution differs from an ideal solution or from a mixture of a monomeric solute and solvent. However, certain results, apparently not very widely known, make one feel that such qualitative questions are not out of date and that the thermodynamics of concentrated polymer solutions may be open to much further development.


1990 ◽  
Vol 01 (01) ◽  
pp. 119-145 ◽  
Author(s):  
HAGAI MEIROVITCH

We discuss the statistical properties of the scanning simulation method for macromolecules and its variant, the double scanning method. We summarize results (in particular critical exponents and transition temperatures) obtained for a wide range of models, branched polymers, polymers adsorbed on a surface and polymers at their collapse transition (the Flory θ-point). We describe application of the methods for studying the stability of polypeptides and discuss plans for future work.


1990 ◽  
Vol 41 (6) ◽  
pp. 3074-3080 ◽  
Author(s):  
Dominique Maes ◽  
Carlo Vanderzande
Keyword(s):  

1984 ◽  
Vol 81 (3) ◽  
pp. 1504-1506 ◽  
Author(s):  
Hiroyuki Ito ◽  
Osamu Koyama ◽  
Akio Chiba

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