Showing papers by "N. C. Wickramasinghe published in 1998"

Infrared Evidence for Panspermia: An Update

Abstract: Recent infrared spectroscopy of astronomical sources, particularly over the 2–4 μm and 8–13 μm wavebands, is re-examined in relation to the hypothesis of biological grains. The most relevant new observations provide further support for this hypothesis.

Search for living cells in stratospheric samples

Abstract: Air samples are to be collected at various altitude sin the stratosphere using balloons flown form Hyderabad, India. The samples will be passed through sterile micropore filters, after which the filters will be analyzed using voltage sensitive lipophilic dyes to detect the presence of either active or non-active cells. Organisms detected in this manner will be studied using static mass spectroscopy to establish isotropic ratios 13C/12C and D/H, which would distinguish between terrestrial and extraterrestrial cells.

Determination of Optical Spectra by a Modified Kramers Kronig Integral

Abstract: A new modified Kramers Kronig Integral is derived and shown to produce excellent results when k data is only known over a limited range. By considering the effect of resonance features simulated using the Dirac-Delta function, the new integral is shown to be more rapidly converging than both the conventional Kramers Kronig integral and a modified (Subtractive Kramers Kronig – SKK) integral introduced by Ahrenkiel (1971). The new integral does not require extensive extrapolation of reflectance data outside the measured region in order to produce reliable results. By extending the above procedure to include n data points, it is shown that at wavelength λ0, \[ n(λ_0)=\sum_{i=1}^{\rm n}(-1)^{\rm n+1}\prod_{\stackrel{j=1}{j ot=i}}^{\rm n} \frac{(λ_j^2-λ_0^2)}{(λ_i^2- λ_j^2)}n(λ_i)+\frac{2}{\pi}P\int_{0}^{\infty}(-1)^{\rm n+1} \frac{\prod_{i=1}^{\rm n}(λ_i^2-λ_0^2)}{\prod_{i=0}^{\rm n}(λ^2-λ_i^2)}λ k(λ)dλ \] with relative error given by, \[ R_n(λ_0)=\prod_{i=1}^{\rm n}\frac{λ_i^2- λ_0^2}{λ_Σ^2-λ_i^2} . \] This nth order expression should prove useful in establishing the internal self-consistency of data sets for which both optical coefficients have been theoretically derived.

Microdiamonds and the Ultraviolet Extinction of Starlight

Abstract: Nanometre-sized microdiamonds of the type recently discovered in meteorites could make up a significant fraction of interstellar carbon, and thus explain the observed excess of interstellar extinction at ultraviolet wavelengths.