Orientation of Demagnetized Bees

The orientation of honey bee dances is affected by the earth's magnetic field. Honey bees possess localized, well-oriented, stable and superparamagnetic domains of magnetite. Four lines of evidence suggest that the superparamagnetic domains of bees are more likely to be involved in magnetic field detectors than the stable domains. (1) Although the stable domains vary widely in size and number between bees, approximately 2×10^8 superparamagnetic domains are found reliably in all bees, and are restricted to there latively narrow size range of 300–350 Å. This suggests that the superparamagnetic domains are more likely to have a biological function. (2) Behavioural observations of dances in null fields are difficult to reconcile with astable-domain detector but are clearly predicted by many superparamagnetic detector models. (3) When honey bees are demagnetized, their ability to orient to the earth's field is unaffected. This suggests that the detector either utilizes the super paramagnetic domains or depends on aligned anisotropic stable domains processed without regard to magneticpolarity. (4) Bees that have only superparamagnetic domains are able nevertheless to orient to the earth's magnetic field, a phenomenon which indicates that permanent domains may not be required for detection

Variation in Environmental Risk Perceptions and Information Sources among Three Communities in El Paso

The authors report the results of a pilot study of environmental risk and sources of environmental information in three socio-economically and culturally distinct communities in Texas

Revised time-of-flight calculations for high-latitude geomagnetic pulsations using a realistic magnetospheric magnetic field model

We present a simple time-of-flight analysis of Alfvén pulsations standing on closed terrestrial magnetic field lines. The technique employed in this study in order to calculate the characteristic period of such oscillations builds upon earlier time-of-flight estimates via the implementation of a more recent magnetospheric magnetic field model. In this case the model employed is the Tsyganenko (1996) field model, which includes realistic magnetospheric currents and the consequences of the partial penetration of the interplanetary magnetic field into the dayside magnetopause. By employing a simple description of magnetospheric plasma density, we are therefore able to estimate the period of standing Alfvén waves on geomagnetic field lines over a significantly wider range of latitudes and magnetic local times than in previous studies. Furthermore, we investigate the influence of changing season and upstream interplanetary conditions upon the period of such pulsations. Finally, the eigenfrequencies of magnetic field lines computed by the time-of-flight technique are compared with corresponding numerical solutions to the wave equation and experimentally observed pulsations on geomagnetic field lines

Toxic Phenolic Glycosides From \u3ci\u3ePopulus:\u3c/i\u3e Physiological Adaptations of the Western North American Tiger Swallowtail Butterfly, \u3ci\u3ePapilio Rutulus\u3c/i\u3e (Lepidoptera: Papilionidae)

The phenolic glycosides tremulacin and salicortin found in quaking aspen, Populus tremuloides, and other members of the Salicaceae, are known to be toxic to larvae of the Eastern tiger swallowtail butterfly, Papilio glaucus, but not to the Canadian tiger swallowtail, P. canadensis. Larvae of the western tiger swallowtail, P. rutulus, were not killed nor were their growth rates suppressed when fed a mixture of tremulacin and salicortin on black cherry leaves. When the Salicaceae adapted P. rutulus penultimate instar larvae were fed a combination of the two phenolic glycosides and the esterase inhibitor (DEF S,S,S-tributylphosphorotrithioate), growth was reduced more than 50OJo compared to controls, and half of the larvae died before completing the instaL Our results indicate that esterase detoxification mechanisms are involved in the western tiger swallowtail, P. rutulus, as is also known to be the case for the northern tiger swallowtail, P. canadensis. It is not known whether the same esterase isozyme is involved in both species. From an evolutionary perspective such information could help resolve whether the Salicaceae-adapted swallowtails species are a monophyletic group (perhaps due to isolation in the Beringial Pleistocene glacial refuge of Alaska)

Estimation of Standardized Effort in the Heterogeneous Gulf of Mexico Shrimp Fleet

In this paper we estimate nominal and standardized shrimping effort in the Gulf of Mexico for the years 1965 through 1993. We accomplish this by first developing a standardization method (model) and then an expansion method (model). The expansion model estimates nominal days fished for noninterview landings data. The standardization model converts nominal days fished to standard days fished. We then characterize the historical trends of the penaeid shrimp fishery byvessel configuration, relative fishing power, and nominal and standardized effort. Wherever possible, we provide comparison with previous estimates by the National Marine Fisheries Service, NOAA

Regenerative fuel cell study for satellites in GEO orbit

Summarized are the results of a 12-month study to identify high performance regenerative hydrogen-oxygen fuel cell concepts for geosynchronous satellite application. Emphasis was placed on concepts with the potential for high energy density (W-hr/lb) and passive means for water and heat management to maximize system reliability. Both polymer membrane and alkaline electrolyte fuel cells were considered, with emphasis on the alkaline cell because of its high performance, advanced state of development, and proven ability to operate in a launch and space environment. Three alkaline system concepts were studied. The first, the integrated design, utilized a configuration in which the fuel cell and electrolysis cells are alternately stacked inside a pressure vessel. Product water is transferred by diffusion during electrolysis and waste heat is conducted through the pressure wall, thus using completely passive means for transfer and control. The second alkaline system, the dedicated design, uses a separate fuel cell and electrolysis stack so that each unit can be optimized in size and weight based on its orbital operating period. The third design was a dual function stack configuration, in which each cell can operate in both fuel cell and electrolysis mode, thus eliminating the need for two separate stacks and associated equipment. Results indicate that using near term technology energy densities between 46 and 52 W-hr/lb can be achieved at efficiencies of 55 percent. System densities of 115 W-hr/lb are contemplated

"The Case Against Intergenerational Accounting: The Accounting Campaign Against Social Security and Medicare"

The Federal Accounting Standards Advisory Board (FASAB) has proposed subjecting the entire federal budget to "intergenerational accounting"--which purports to calculate the debt burden our generation will leave for future generations--and is soliciting comments on the recommendations of its two "exposure drafts." The authors of this brief find that intergenerational accounting is a deeply flawed and unsound concept that should play no role in federal government budgeting, and that arguments based on this concept do not support a case for cutting Social Security or Medicare. The FASAB exposure drafts have not made a persuasive argument about basic matters of accounting, say the authors. Federal budget accounting should not follow the same procedures adopted by households or business firms because the government operates in the public interest, with the power to tax and issue money. There is no evidence, nor any economic theory, behind the proposition that government spending needs to match receipts. Social Security and Medicare spending need not be politically constrained by tax receipts--there cannot be any "underfunding." What matters is the overall fiscal stance of the government, not the stance attributed to one part of the budget.