Small Total Mass Research Articles

Airborne measurements of aerosols from burning biomass in Brazil related to the TRACE A experiment

Results are reported from an airborne campaign to investigate the impacts of burning biomass upon the loading of lower‐tropospheric aerosols and its composition over the Brazilian tropics. The flights, conducted as part of the NASA/Transport and Atmospheric Chemistry Near the Equator‐Atlantic (TRACE A) mission, started on September 1, 1992, when the dry (fire) season still prevailed in the central part of Brazil, and ended on September 29. Of the total number of burnings detected in Brazil by the advanced very high resolution radiometer (AVHRR)/NOAA satellite sensor, 74% were concentrated in the states of Amazonas, Maranhão, Mato Grosso, Pará, Roraima, and Tocantins during this period. Aerosol particles were sampled from a twin‐engine aircraft in transit and vertical profile flights were made up to 4,000 m altitude. Black carbon measurements made in real time and in areas of burning biomass peaked at ∼2,500 m above the ground, increasing to ∼12,000 ng/m3. In other areas these values were lower by 1 order of magnitude. A condensation nuclei counter measuring small particles (>0.014 μm) produced values ranging from 2,000 to 16,000/cm3for areas with low and high burning biomass, respectively. Deposition filters in a two‐stage cascade impactor, and Nuclepore filters collected aerosols for analysis of 13 elements through particle‐induced X ray emissions (PIXE). Primary elements associated with soil dust (Al, Si, Mn, Fe, Ni) prevailed in the aerosol coarse mode (>1 μm) while the fine mode aerosols were enriched in S, K, Br, and Rb, which are tracers normally associated with burning of biomass. The good correlation between fire spot counts, obtained via AVHRR aboard NOAA satellites, and black carbon, counts of small particles and total aerosol mass, suggests the determining of local concentrations of fire‐derived aerosol fire emissions by satellite to be a new and useful approach.

Classical splitting of fundamental strings.

We find exact solutions of the string equations of motion and constraints describing the {\em classical}\ splitting of a string into two. We show that for the same Cauchy data, the strings that split have {\bf smaller} action than the string without splitting. This phenomenon is already present in flat space-time. The mass, energy and momentum carried out by the strings are computed. We show that the splitting solution describes a natural decay process of one string of mass $M$ into two strings with a smaller total mass and some kinetic energy. The standard non-splitting solution is contained as a particular case. We also describe the splitting of a closed string in the background of a singular gravitational plane wave, and show how the presence of the strong gravitational field increases (and amplifies by an overall factor) the negative difference between the action of the splitting and non-splitting solutions.

On the Giant Octopus (Octopus giganteus) and the Bermuda Blob: Homage to A. E. Verrill.

We have obtained samples of two large carcasses. One washed up on a beach in St. Augustine, Florida, in 1896 and has been occasionally attributed to a species of gigantic octopus (Octopus giganteus). The other carcass washed up on Bermuda in 1988 and has remained unidentified, although its gross morphology, except for a much smaller total mass, was remarkably similar to the Florida carcass. We have subjected both samples to electron microscopic and biochemical analyses. Our results show that both carcasses are masses of virtually pure collagen. Furthermore, neither sample has the biochemical characteristics of invertebrate collagen, nor the collagen fiber arrangement of octopus mantle. Instead, they are large pieces of vertebrate skin, the Bermuda sample from a poikilotherm and the Florida sample from a huge homiotherm. We conclude that there is no evidence to support the existence of Octopus giganteus.

Characteristics of normal-crowned and pendula spruce (Picea abies (L.) Karst.) examined with reference to the definition of a crop tree ideotype.

Sixty-four 19-year-old Norway spruce trees were felled and the roots excavated during 1987 and 1988. The trees were open-pollinated progenies from a small stand located in southern Finland. Several characteristics of stem, crown, and roots were measured and analyzed on 36 pendula and 28 normal-crowned trees in the sample. Total fresh weight, stem fresh weight, and crown fresh weight were 47.6, 27.5, and 61.4% greater in normal-crowned trees than in pendula trees. The mean harvest index (including roots) of pendula spruce was 0.32 compared with a value of 0.27 for normal-crowned trees. This difference reflects the difference in crown biomass between the two groups of trees. The crown structure of pendula spruce appears to permit higher stand densities than is possible with normal-crowned spruce. Thus the results indicate that genetically narrow-crowned trees with a small total crown mass could provide useful basic material for selection of crop trees with a high stemwood production per hectare.

Perturbation Treatment of the Bethe-Salpeter Equation for Tightly Bound Fermion-Antifermion Systems

A perturbation theory is developed for the ladder approximation Bethe-Salpeter equation that describes bound spin-½ fermion-antifermion systems of small total mass. A new exact analytical solution for a zero-mass system is presented and the perturbation theory is applied to it. Some time-reversal properties of the equation are also examined.