With a phase microscope the phase shift of cells from type L 929 fibroblast and mitochondria from liver cells was measured. Compared to the total phase shift caused by the cell relative to vacuum (approximately 1400 nm) the single phase shift of the mitochondria (approximately 180 nm) is small. Only the nucleus and the membrane of the cell give a visibly different phase shift relative to the mean value of the cell. The Fraunhofer diffraction of the measured phase object is calculated. With a simplified scattering theory, i.e. Rayleigh-Gans Scattering, different phase objects are investigated and their differential cross section is discussed.

Successful laserinduced tumor therapy requires the knowledge of optical properties of tissue as well as ofthe thermal ones (specific heat capacity, thermal conductivity, thermal diffusivity). Therefore, a comprehensive review of one of those values, the specific heat capacity c, of different human and animal tissues is given measured calorimetrically by us or collected from the literature.A Differential Scanning Calorimeter (DSC) was used to determine the in vitro specific heat capacities of various healthy and tumorous human tissues. The influence of freezing in liquid nitrogen and ofthermal coagulation on the specific heat capacity was investigated.

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We show that the scattering amplitude of four open string scalars or tachyons on the world-volume of a Dp-brane in the bosonic string theory can be written in a universal form. The difference between this amplitude and the corresponding amplitude in the superstring theory is in an extra tachyonic pole. We show that in an α expansion and for slowly varying fields, the amplitude is consistent with the tachyonic DBI action in which the even part of the tachyon potential is V (T ) = e −( √ πT /α) 2 with α = 1 for bosonic theory and α = √ 2 for superstring theory.