The South Seas of To-Day

The following is a chapter plus some text from the Introduction of a book published in 1926, describing a scientific expedition that cruised the Pacific in 1924. The group visited the Marquesas, Tahiti, and Rapa Iti before stopping, briefly, at Easter Island. What science was conducted is unclear. They did make a film record of the journey and the whereabouts ofthe footage they shot would be of interest, if it still exists. Of particular concern is the presence on Easter Island of a Ford automobile, described as "very, very old and decrepit ". This apparition, belonging to Mr. Edmunds, is a real mystery of Easter Island. How did it get to the island? And when?</p

The Underwater Photic Environment of a Small Arctic Lake

The underwater light field in a small arctic lake on Victoria Island, Northwest Territories, was examined. Downward radiance was found to be bimodal, with transmission peaks at 480 and 640 nanometres (nm, or .000000001 m). Upward radiance was similar near the surface, with peaks at 480 and 620 nm, but became unimodal with depth and shifted to 580 nm near the bottom. Diurnal variation in the underwater downward and upward irradiance of PAR (photosynthetically active radiation) was approximately two orders of magnitude. The spectral quality of light transmission also changed over this 24 hour period. Unimodal transmission of red light occurred in the early morning (1:00 and 5:00) and late evening (22:00), while bimodal transmission of blue-green and red light was observed during the day (9:00-17:30). Kd(Zm), the vertical attenuation coefficient for downward irradiance at the midpoint of the euphotic zone, was relatively insensitive to changes in solar elevation. Diurnal variation in the reflectance of PAR differed from the predicted by previous simulation models, while the inverse relationship between reflectance and the absorption coefficient was in agreement with these same models. Gilvin, humic material-dissolved iron complexes, algal fucoxanthin, chlorophyll a and tripton all contribute to the attenuation of light and are responsible for the unique underwater spectral transmission in Keyhole Lake.

Protective Efficacy of Individual CD8+ T Cell Specificities in Chronic Viral Infection.

Specific CD8(+) T cells (CTLs) play an important role in resolving protracted infection with hepatitis B and C virus in humans and lymphocytic choriomeningitis virus (LCMV) in mice. The contribution of individual CTL specificities to chronic virus control, as well as epitope-specific patterns in timing and persistence of antiviral selection pressure, remain, however, incompletely defined. To monitor and characterize the antiviral efficacy of individual CTL specificities throughout the course of chronic infection, we coinoculated mice with a mixture of wild-type LCMV and genetically engineered CTL epitope-deficient mutant virus. A quantitative longitudinal assessment of viral competition revealed that mice continuously exerted CTL selection pressure on the persisting virus population. The timing of selection pressure characterized individual epitope specificities, and its magnitude varied considerably between individual mice. This longitudinal assessment of "antiviral efficacy" provides a novel parameter to characterize CTL responses in chronic viral infection. It demonstrates remarkable perseverance of all antiviral CTL specificities studied, thus raising hope for therapeutic vaccination in the treatment of persistent viral diseases

Angular momentum I ground state probabilities of boson systems interacting by random interactions

In this paper we report our systematic calculations of angular momentum $I$ ground state probabilities ($P(I)$) of boson systems with spin $l$ in the presence of random two-body interactions. It is found that the P(0) dominance is usually not true for a system with an odd number of bosons, while it is valid for an even number of bosons, which indicates that the P(0) dominance is partly connected to the even number of identical particles. It is also noticed that the $P(I_{max})$'s of bosons with spin $l$ do not follow the 1/N ($N=l+1$, referring to the number of independent two-body matrix elements) relation. The properties of the $P(I)$'s obtained in boson systems with spin $l$ are discussed.Comment: 8 pages and 3 figure

Annulus Amplitudes and ZZ Branes in Minimal String Theory

We study the annulus amplitudes of (p,q) minimal string theory. Focusing on the ZZ-FZZT annulus amplitude as a target-space probe of the ZZ brane, we use it to confirm that the ZZ branes are localized in the strong-coupling region. Along the way we learn that the ZZ-FZZT open strings are fermions, even though our theory is bosonic! We also provide a geometrical interpretation of the annulus amplitudes in terms of the Riemann surface M_{p,q} that emerges from the FZZT branes. The ZZ-FZZT annulus amplitude measures the deformation of M_{p,q} due to the presence of background ZZ branes; each kind of ZZ-brane deforms only one A-period of the surface. Finally, we use the annulus amplitudes to argue that the ZZ branes can be regarded as "wrong-branch" tachyons which violate the bound \alpha<Q/2.Comment: 33 pages, new results in appendix, minor change