8,795 research outputs found
An analytical basis for assaying buried biological contamination Interim report
Assay techniques for determining biological contamination of spacecraft material
On Two Complementary Types of Total Time Derivative in Classical Field Theories and Maxwell's Equations
Close insight into mathematical and conceptual structure of classical field
theories shows serious inconsistencies in their common basis. In other words,
we claim in this work to have come across two severe mathematical blunders in
the very foundations of theoretical hydrodynamics. One of the defects concerns
the traditional treatment of time derivatives in Eulerian hydrodynamic
description. The other one resides in the conventional demonstration of the
so-called Convection Theorem. Both approaches are thought to be necessary for
cross-verification of the standard differential form of continuity equation.
Any revision of these fundamental results might have important implications for
all classical field theories. Rigorous reconsideration of time derivatives in
Eulerian description shows that it evokes Minkowski metric for any flow field
domain without any previous postulation. Mathematical approach is developed
within the framework of congruences for general 4-dimensional differentiable
manifold and the final result is formulated in form of a theorem. A modified
version of the Convection Theorem provides a necessary cross-verification for a
reconsidered differential form of continuity equation. Although the approach is
developed for one-component (scalar) flow field, it can be easily generalized
to any tensor field. Some possible implications for classical electrodynamics
are also explored.Comment: no figure
Grown organic matter as a fuel raw material resource
An extensive search was made on biomass production from the standpoint of climatic zones, water, nutrients, costs and energy requirements for many species. No exotic species were uncovered that gave hope for a bonanza of biomass production under culture, location, and management markedly different from those of existing agricultural concepts. A simulation analysis of biomass production was carried out for six species using conventional production methods, including their production costs and energy requirements. These estimates were compared with data on food, fiber, and feed production. The alternative possibility of using residues from food, feed, or lumber was evaluated. It was concluded that great doubt must be cast on the feasibility of producing grown organic matter for fuel, in competition with food, feed, or fiber. The feasibility of collecting residues may be nearer, but the competition for the residues for return to the soil or cellulosic production is formidable
The role of intermolecular coupling in the photophysics of disordered organic semiconductors: Aggregate emission in regioregular polythiophene
We address the role of excitonic coulping on the nature of photoexcitations
in the conjugated polymer regioregular poly(3-hexylthiophene). By means of
temperature-dependent absorption and photoluminescence spectroscopy, we show
that optical emission is overwhelmingly dominated by weakly coupled
H-aggregates. The relative absorbance of the 0-0 and 0-1 vibronic peaks
provides a powerfully simple means to extract the magnitude of the
intermolecular coupling energy, approximately 5 and 30 meV for films spun from
isodurene and chloroform solutions respectively.Comment: 10 pages, 4 figures, published in Phys. Rev. Let
Efficacy Of Three Attractant Blends Tested In Combination With Carbon Dioxide Against Natural Populations Of Mosquitoes And Biting Flies At The Lower Suwannee Wildlife Refuge
Synthetic blends of chemicals identified previously from human skin emanations were evaluated against mosquito and biting fly populations at the Lower Suwannee Wildlife Refuge near Cedar Key, FL. Mosquito MagnetTM-Experimental traps were baited with the Red (400 ml acetone:10 ml 1-hexen- 3-ol:10 ml 1-octen-3-ol), Blue (400 ml acetone:1 g/liter lactic acid:20 ml glycolic acid), or Green blend (400 ml acetone:1.5 g/liter lactic acid:20 ml dimethyl disulfide) plus CO2 or with CO2 alone (control). A relative index of efficacy was determined by dividing each mean blend trap catch by the mean control trap catch. Five mosquitoes (Aedes infirmatus, Ae. taeniorhynchus, Ae. triseriatus, Anopheles crucians, and Culex nigripalpus), 2 ceratopogonid (Culicoides floridensis and C. furens), and 1 tabanid (Diachlorus ferrugatus) and phlebotomine (Lutzomyia shannoni) species were trapped. The Red blend + CO2 treatment significantly increased collections of Ae. taeniorhynchus (3.4×), An. crucians (2.8×), total mosquitoes (2.7×), C. furens (17.6×), and L. shannoni (10.8×) compared with control traps. Traps baited with either the Blue or Green blends generally captured fewer insects than traps baited with the other 2 treatments. However, traps baited with the Green blend caught 7× as many C. furens as the control traps. Responses clearly varied according to species; therefore, ‘‘one size does not fit all’’ when it comes to attractant blends
The Aquatic Heteroptera (Hemiptera) of Marshes in the Florida Everglades
The Everglades is a large subtropical wetland that has been modified heavily by humans and now is undergoing restoration. Aquatic and semiaquatic Heteroptera (Hemiptera) in the infraorders Gerromorpha and Nepomorpha were collected in the Florida Everglades using standardized 1-m2throw-traps. Sampling efforts were conducted in marshes distributed from southern Everglades National Park, north throughout the Water Conservation Areas to Loxahatchee National Wildlife Refuge. In total, 12,833 individuals were identified representing 17 species in 13 genera and 8 families (Belostomatidae, Corixidae, Gerridae, Mesoveliidae, Naucoridae, Nepidae, Veliidae). The naucorid Pelocoris femoratus (Palisot de Beauvois) (Hemiptera: Naucoridae) was by far the most abundant species, whereas 2 other species, Belostoma lutarium (Stål) (Hemiptera: Belostomatidae) and Neogerris hesione Kirkaldy (Hemiptera: Gerridae), were widespread but less abundant. Two species, Abedus immaculatus (Say) (Hemiptera: Belostomatidae) and Pelocoris balius La Rivers (Hemiptera: Naucoridae) had localized distributions, whereas all other species were collected rarely. We discuss the abundance and distribution of species recorded, along with unique traits and the biology of the aquatic Heteroptera in the Everglades and implications for the restoration of the Everglades
Effect of Epoxy Impregnation on the Moe and Mor of Intact and Failed Yellow-Poplar (Liriodendron Tulipifera L.) Sapwood Beams
The effects of epoxy impregnation on the MOR and MOE of intact and failed yellow-poplar (Liriodendron tulipifera L.) clear sapwood beams were investigated. Both impregnated and unimpregnated specimens were partially failed in bending, impregnated to stabilize the cracks, and retested. The presence of induced cracks had a significant effect on the MOR of the material after impregnation or reimpregnation, but not on the MOE. Both the MOR and MOE of the failed, then impregnated material exceeded the values for unimpregnated yellow-poplar
Shoot growth of woody trees and shrubs is predicted by maximum plant height and associated traits
1. The rate of elongation and thickening of individual branches (shoots) varies across plant species. This variation is important for the outcome of competition and other plant-plant interactions. Here we compared rates of shoot growth across 44 species from tropical, warm temperate, and cool temperate forests of eastern Australia.2. Shoot growth rate was found to correlate with a suite of traits including the potential height of the species, xylem-specific conductivity, leaf size, leaf area per xylem cross-section, twig diameter (at 40 cm length), wood density and modulus of elasticity.3. Within this suite of traits, maximum plant height was the clearest correlate of growth rates, explaining 50 to 67% of the variation in growth overall (p p 4. Growth rates were not strongly correlated with leaf nitrogen or leaf mass per unit leaf area.5. Correlations between growth and maximum height arose both across latitude (47%, p p p p < 0.0001), reflecting intrinsic differences across species and sites
Combustion of LOX with H2(sub g) under subcritical, critical, and supercritical conditions (Task 1) and experimental observation of dense spray and mixing of impinging jets (Task 2)
The objective was to achieve a better understanding of the combustion processes of liquid oxygen and gaseous hydrogen under broad range of pressure covering subcritical, critical, and supercritical conditions. The scope of the experimental work falls into the following areas: (1) design of the overall experimental setup; (2) modification of an existing windowed high pressure chamber; (3) design of the LOX feeding system; (4) provision of the safety features in the test rig design; (5) LOX cleanliness requirements; (6) cold shock testing; (7) implementation of data acquisition systems; (8) preliminary tests for system checkout; (9) modification of LOX feeding system; and (10) evaporation tests. Progress in each area is discussed
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