We compare the effects of spherical aberration on the penetration depth of single-photon and two-photon excitation for instances in which the aberration is caused by the refractive-index mismatch when a beam is focused through an interface. It is shown both theoretically and experimentally that two-photon fluorescence imaging experiences less spherical aberration and can thus propagate to a deeper depth within a thick medium.

Various malignant tumors of the liver, especially liver angiosarcoma, have been described after occupational exposure to vinyl chloride monomer. We present the case records and pathologic findings of two plastic industry workers who had been exposed to high concentrations of vinyl chloride. These workers developed hepatic neoplasms, angiosarcoma, or hemangiopericytoma. We discuss the histogenesis of these tumors; the common vascular origin and the mutual transformation of these two tumors suggest that the hemangiopericytoma may also have developed during occupational exposure to high concentrations of vinyl chloride monomer. ImagesFigure 1Figure 2

A quasi-classical three-step model for high-harmonic generation is presented. The results for the harmonic emission rate obtained using this model agree very well with the exact results. For an elliptically polarized laser field a staircase of plateaux is observed. Both the heights and the cut-off positions of these plateaux are explained. An analytical formula for the cut-off law is derived and applied to determine the cut-off of the harmonic spectrum for each of the observed plateaux. We also present the electron orbits, obtained as solutions of the classical equation of motion with the complex time.

We analyze the use of strong static electric and magnetic fields for controlling two intense laser-atom processes: laser-assisted x-ray-atom scattering and high-order harmonic generation. We find that x-rays scattered from atoms in the presence of both a strong laser field and a strong static electric field can be boosted in energy many-fold by absorption of energy from the laser field. The spectrum of scattered x-ray intensity vs. the number of laser photons absorbed exhibits a rich plateau structure, whose key features may be understood using a classical analysis. We find also that the intensities of high-order harmonics can be increased by orders of magnitude in the presence of strong static magnetic or parallel electric and magnetic fields and also that the static electric field can introduce additional plateaus and cutoffs. The maximum values of the harmonic intensity correspond to values of magnetic field for which the return time of the ionized electron wave packet to the atomic core under the infl...

Lelo, S.: Revised inventory of the butterflies of Bosnia and Herzegovina (Insecta: Lepidoptera: Hesperioidea, Papilionidea). Nat. Croat., Vol. 9, No. 2., 139–156, 2000, Zagreb. This work presents a third revision of the inventory of butterflies of Bosnia and Herzegovina according to the Karsholt – Razowski system. The revision was carried out from analysis of the scientific literature and published field observations from B-H. The presence of L. reali (Reissinger, 1989) has been verified personally by the author in the course of his own field research and subsequent laboratory investigations.