A CRITICAL STUDY IN THE COMPLEX-POLYMORPHOUS GENUS SCHIMA (THEACEAE)

 1. The author considers the genus Schima monotypic. Its only species, Schima wallichii (DC.) Korth., is subdivided into nine geographically separated subspecies and three varieties.These may be recognised sometimes by one dominating chax*acter,mostly, however, by a complex of characters.Several new combinations are made.2. Yet the variability of most of the subspecies is still often enormous and at first sight appears complex. Thus we may often encounter the polymorphy of the whole species in its subspecies again. It was the striking different percentage-numbers of(phenotypically) about the same characters which turned the scale in favour of the recognition of the subspecies, besides their geographic separation.The attempts made by the author to divide certain resulting complex-polymorphous subspecies into units of still lower rank and to trace correlations with peculiarities of environment such as different heights above sealevel, or with different stages in the age of the trees, failed. 3. On account of these negative results and the above mentioned different percentage-numbers for phenotypically about the same characters, the author came to the conclusion that the most probable explanation is that the variability within the subspecies is just due to Mendel-segregation and nothing else.It looks very much as if one is dealing here with the inheriting of striking characters, each caused by one or only a few polymeric factors, characters which hold their own, just as in panmictlcally propagated populations (by cross-pollination). This explanation, too,makes the striking fact that in some subspecies we find back phenotypically the whole, or part, of the polymorphy of the entire species more understandable, as well as the fact that individuals of different subspecies may agree phenotypically, whereas genotypically they belong to different races (subspecies), Moreover, all these phenomena strongly support the monotypic conception of the genus. 4. The author saw few examples from the area outside Indonesia. However,this does neither influence his monotypic conception of the genus, nor his method of dividing it into units of lower ranks. The study of the scanty amount of specimens,literature, and the drawings seen appeared more than sufficiently convincing. Yet he is not quite certain whether the correct rank was ascribed to some of the lower taxa involved. It would perhaps have been advisable to consider the variety superba and the continental parts of the subspecies oblata and monticola as distinct subspecies.Future consideration of this matter shall have to decide

Causal vs. Noncausal Description of Nonlinear Wave Mixing; Resolving the Damping-Sign Controversy

Frequency-domain nonlinear wave mixing processes may be described either using response functions whereby the signal is generated after all interactions with the incoming fields, or in terms of scattering amplitudes where all fields are treated symetrically with no specific time ordering. Closed Green's function expressions derived for the two types of signals have different analytical properties. The recent controversy regarding the sign of radiative damping in the linear (Kramers Heisenberg) formula is put in a broader context

Editorial

‘A new spring, and a new sound’, so begins a famous Dutch poem. Will the birds sing differently, as the poet wishes in the next line? BKI, now 178 years old—surely one of the longest-running journals of Southeast Asian studies in the world, and known around its original home, the KITLV (Royal Institute), as ‘the Old Dame’—starts 2022 with a remarkable new development. For this reason, the first issue of the year opens with an Editorial. After generations of sound and steady editing under the direction of two scholars, one in the role of Chief Editor and one as Managing Editor, from now on, BKI will be run by an expanded editorial team of seven scholars drawn both from the geographical region, Southeast Asia, and the disciplines in the humanities and social sciences that BKI is dedicated to examining..

Multipole nonlinearity of metamaterials

We report on the linear and nonlinear optical response of metamaterials evoked by first and second order multipoles. The analytical ground on which our approach bases permits for new insights into the functionality of metamaterials. For the sake of clarity we focus here on a key geometry, namely the split-ring resonator, although the introduced formalism can be applied to arbitrary structures. We derive the equations that describe linear and nonlinear light propagation where special emphasis is put on second harmonic generation. This contribution basically aims at stretching versatile and existing concepts to describe light propagation in nonlinear media towards the realm of metamaterials.Comment: 7 pages, 3 figure

Nonlinear optical spectroscopy of single, few, and many molecules; nonequilibrium Green's function QED approach

Nonlinear optical signals from an assembly of N noninteracting particles consist of an incoherent and a coherent component, whose magnitudes scale \sim N and \sim N(N-1), respectively. A unified microscopic description of both types of signals is developed using a quantum electrodynamical (QED) treatment of the optical fields. Closed nonequilibrium Green's function expressions are derived that incorporate both stimulated and spontaneous processes. General (n+1)-wave mixing experiments are discussed as an example of spontaneously generated signals. When performed on a single particle, such signals cannot be expressed in terms of the nth order polarization, as predicted by the semiclassical theory. Stimulated processes are shown to be purely incoherent in nature. Within the QED framework, heterodyne-detected wave mixing signals are simply viewed as incoherent stimulated emission, whereas homodyne signals are generated by coherent spontaneous emission.Comment: article: 33 pages (preprint format!) ''paper.tex'' figures: 17 figures (.eps) in folder ``figures'

Influence of damping on the vanishing of the electro-optic effect in chiral isotropic media

Using first principles, it is demonstrated that radiative damping alone cannot lead to a nonvanishing electro-optic effect in a chiral isotropic medium. This conclusion is in contrast with that obtained by a calculation in which damping effects are included using the standard phenomenological model. We show that these predictions differ because the phenomenological damping equations are valid only in regions where the frequencies of the applied electromagnetic fields are nearly resonant with the atomic transitions. We also show that collisional damping can lead to a nonvanishing electrooptic effect, but with a strength sufficiently weak that it is unlikely to be observable under realistic laboratory conditions

Equatorial and related non-equilibrium states in magnetization dynamics of ferromagnets: Generalization of Suhl's spin-wave instabilities

We investigate the nonlinear dynamics underlying the evolution of a 2-D nanoscale ferromagnetic film with uniaxial anisotropy in the presence of perpendicular pumping. Considering the associated Landau-Lifshitz spin evolution equation with Gilbert damping together with Maxwell equation for the demagnetization field, we study the dynamics in terms of the stereographic variable. We identify several new fixed points for suitable choice of external field in a rotating frame of reference. In particular, we identify explicit equatorial and related fixed points of the spin vector in the plane transverse to the anisotropy axis when the pumping frequency coincides with the amplitude of the static parallel field. We then study the linear stability of these novel fixed points under homogeneous and spin wave perturbations and obtain a generalized Suhl's instability criterion, giving the condition for exponential growth of P-modes under spin wave perturbations. Two parameter phase diagrams (in terms of amplitudes of static parallel and oscillatory perpendicular magnetic fields) for stability are obtained, which differ qualitatively from those for the conventional ferromagnetic resonance near thermal equilibrium and are amenable to experimental tests.Comment: 23 pages, 5 figures, To appear in Physica

Non-degenerate four-wave mixing in rubidium vapor: transient regime

We investigate the transient response of the generated light from Four-Wave Mixing (FWM) in the diamond configuration using a step-down field excitation. The transients show fast decay times and oscillations that depend on the detunings and intensities of the fields. A simplified model taking into account the thermal motion of the atoms, propagation, absorption and dispersion effects shows qualitative agreement with the experimental observations with the energy levels in rubidium (5S1/2, 5P1/2, 5P3/2 and 6S1/2). The atomic polarization comes from all the contributions of different velocity classes of atoms in the ensemble modifying dramatically the total transient behavior of the light from FWM.Comment: 11 pages, 11 figures, to be published in Physical Review