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32  Mathematical Techniques of Fractional Order Systems



              TABLE 1.3 Variables and Parameters
              Unaltered Parameters

              α C                3               σ C          10 26
              α B                4               σ B          10 26
                                 0.2                            26
              β C                                σ z          10
              β B                0.02            σ T          10 26
              g CC               1.1             r CC         0.005
              g BC               20:5            r BC         0
              g CB               1.0             r CB         0
              g BB               0               r BB         0.2
              zð0Þ=zð0;xÞ        100             L T          100
              Local versus Nonlocal              Local        Nonlocal

              κ C                                0.0748       0.45
              κ B                                6:39 3 10 24  0:0048
                                                 0.005        0.004
              γ T
              Tð0Þ=Tð0;xÞ                        1
              Healthy versus Metastatic Bone     Healthy      Metastatic
              Cð0Þ=Cð0;xÞ                        11.76        15
              Bð0Þ=Bð0;xÞ                        231.72       316
              C ss                               1.16         5
              B ss                               231.72       316
              Source: From Ayati et al. (2010), used for the simulations and equations of local and non local
              models presented in this paper, except when explicitly said otherwise. Constant parameters,
              regardless of the simulation type, are presented in Unaltered Parameters section. Parameters that
              differ with local or nonlocal environments are presented in Local vs Local. Healthy or metastatic
              bone parameters are presented in Healthy vs Metastatic Bone.



            1.5  CONCLUSIONS
            This chapter introduced the concept of a variable order derivative, presenting
            the several different possible definitions, and stressing that these correspond
            to a different memory of past values of the order. This memory, which is
            independent of the memory of past values of the differentiated function, may
            not exist; or, if it exists, it may be weaker or stronger. These different defini-
            tions correspond to different manners of taking into account the changes in
            the differentiation order, and take place irrespective of the use of
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