bluuebunny/crossref_metadata_2025 huggingface dataset:
Oil and Ice in the Arctic Ocean: Possible Large-Scale Interactions
Authors: Campbell W. J. , Martin S.
Published: October 2006

The diffusion and transport mechanisms generated by the pack ice dynamics of the Beaufort Sea, combined with the slow rate of biodegradation of oil under Arctic conditions, would combine to diffuse an oil spill over the sea and eventually deposit the oil on the ice surface, where it would lower the natural albedo over a large area.
Sand Dollar: A Weight Belt for the Juvenile
Authors: Chia Fu-Shiang
Published: October 2006

Juvenile sand dollars (
Dendraster excentricus
) selectively ingest heavy sand grains from the substrate and store them in an intestinal diverticulum which may function as a weight belt, assisting the young animal to remain in the shifting sandy environment. The sand disappears from the diverticulum when the animal reaches the length of 30 millimeters.
Memory Disruption by Electrical Stimulation of Substantia Nigra, Pars Compacta
Authors: Routtenberg Aryeh , Holzman Nancy
Published: October 2006

Electrical stimulation of the substantia nigra, pars compacta, of albino rats while they were learning a simple foot shock task of withdrawal and response suppression disrupted retention of that task 24 hours after original learning. Stimulation in the reticular zone of the substantia nigra was without effect on retention performance. Stimulation through electrodes in the medial lemniscus, red nucleus, or brainstem regions surrounding the substantia nigra, pars compacta, was also ineffective. Original learning performance, measured as time to criterion, was unimpaired by the stimulation. Posttrial stimulation in the substantia nigra, pars compacta, but not in adjacent structures, also disrupted retention performance.
Nitrogen Fixation in Termites
Authors: Benemann John R.
Published: October 2006

Nitrogen fixation, measured by the reduction of acetylene to ethylene, was found in workers of the dry-wood termite
Kalotermes minor
. The soldiers and reproductive castes fixed little or no nitrogen. The fixation rates ranged between 24 and 566 micrograms of nitrogen fixed per month per gram (wet weight) of termite. Nitrogen fixation can be a significant source of nitrogen for these termites.
Evoked Potential Correlates of Signal Recognition between and within Modalities
Authors: Ford Judith M. , Roth Walton T. , Dirks Stanley J. , Kopell Bert S.
Published: October 2006

Electrical responses evoked by clicks, flashes, changes in noise level, and changes in light level were recorded from the scalps of human subjects set to detect one of the stimuli. An early negative component of the evoked responses reflects selection between sensory modalities, whereas the later positive component reflects a more complex intramodal discrimination.
Viability versus Fecundity Selection in the Slender Wild Oat,
Avena barbata
L.
Authors: Clegg M. T. , Allard R. W.
Published: October 2006

Estimates of relative selective values of different genotypes in natural populations of predominantly self-pollinated plants have consistently shown a net heterozygote advantage. Heterozygote advantage is further analyzed in the present study by estimating components of selective values corresponding approximately to viability and fecundity. The results show that a higher proportion of heterozygotes than of homozygotes survive from seedling to adult stages and that this viability selection accounts for the overall excess of heterozygotes.
Habituation: Regulation through Presynaptic Inhibition
Authors: Krasne Franklin B. , Bryan Joan S.
Published: October 2006

During tail-flip escape responses of crayfish, synaptic transmission at the habituation-prone synapses of the lateral giant reflex pathway is presynaptically inhibited. This prevents transmitter release and all subsequent postsynaptic actions and spares the reflex from becoming habituated to stimuli produced by an animal's own escape movements. These observations demonstrate the existence of a control circuit whose adaptive function is to regulate the malleability of inherently plastic synapses. They also suggest that regulation of plasticity could be a common use of presynaptic inhibition.
A Search for Far-Ultraviolet Emissions from the Lunar Atmosphere
Authors: Fastie Wm. G. , Feldman Paul D. , Henry Richard C. , Moos H. Warren , Barth Charles A. , Thomas Gary E. , Donahue Thomas M.
Published: October 2006

An ultraviolet spectrometer aboard the Apollo 17 orbiting spacecraft attempted to measure ultraviolet emissions from the lunar atmosphere. The only emissions observed were from a transient atmosphere introduced by the lunar landing engine. The absence of atomic hydrogen implies that solar wind protons are converted to hydrogen molecules at the lunar surface.
Dopamine Synthesis: Stimulation by a Hypothalamic Factor
Authors: Friedman Eitan , Friedman Jacob , Gershon Samuel
Published: October 2006

The effect of treatment with the factor that inhibits the release of melanocyte stimulating hormone (MSH) identified as 1-prolyl-1-leucylglycinamide (MIF) on brain catecholamine synthesis was examined in normal and hypophysectomized rats. The tripeptide induced a dose-related increase in striatal dopamine synthesis in slices obtained from treated normal animals but not in hypophysectomized animals. Hypothalamic norepinephrine synthesis was unaltered by MIF treatment in normal as well as in hypophysectomized rats. In addition, dopamine and norepinephrine syntheses were depressed in untreated hypophysectomized animals, as compared to normal controls. These results constitute the first direct demonstration of a central neurochemical effect of a hypothalamic factor.
Nitrification in Paleocene Shale
Authors: Power J. F. , Bond J. J. , Sandoval F. M. , Willis W. O.
Published: October 2006

Exchangeable ammonium nitrogen is present in Paleocene (Fort Union) shale below a depth of 10 meters in North Dakota and eastern Montana. Above 10 meters, exchangeable ammonium nitrogen is nitrified in situ. The lack of viable nitrifying organisms and the probable lack of oxygen prevent in situ nitrification below 10 meters. Shale samples incubated at 27°C under nonsterile conditions or shales exposed to atmospheric contamination exhibited active nitrification without additional treatment.
Thyroid Hormones: Effect of Physiological Concentrations on Cultured Cardiac Cells
Authors: Tsai Jir S. , Chen Amy
Published: October 2006

Cultured cardiac cells prepared from newborn rat heart will respond in vitro to physiological concentrations of L-triiodothyronine. The cells are grown in a culture medium that contains hypothyroid calf serum. A dose response relationship of L-triiodothyronine indicates that this system may be a useful model for elucidation of the mechanism of thyroid hormone effects on the heart.
Erythrocyte Deformation in Human Muscular Dystrophy
Authors: Matheson Dale W. , Howland John L.
Published: October 2006

Erythrocytes from patients with congenital muscular dystrophy exhibit dramatic surface deformation when observed with a scanning electron microscope. A similar alteration, but one affecting a smaller proportion of cells, occurs in the case of female carriers of the sex-linked Duchenne dystrophic condition. These observed changes in the erythrocyte surface may reflect a systemic defect in membrane properties.
Genetic Regulation of Chlorophyll Synthesis Analyzed with Mutants in Barley
Authors: von Wettstein Diter , Kahn Albert , Nielsen Ole F. , Gough Simon
Published: October 2006

Barley seedlings homozygous both for the xantha-l
35
and tigrina-d
12
mutation accumulate magnesium protopophyrins and other precursors of chlorophyllide constitutively in darkness. The homozygous double mutant xantha-f
10
, tigrina-O
34
produces protoporphyrin constitutively. These results provide evidence for the control of chlorophyllide synthesis in higher plants through the products of regulatory genes in the nucleus.
Carbonate Compensation Depth: Relation to Carbonate Solubility in Ocean Waters
Authors: Ben-Yaakov S. , Ruth E. , Kaplan I. R.
Published: October 2006

In situ calcium carbonate saturometry measurements suggest that the intermediate water masses of the central Pacific Ocean are close to saturation with respect to both calcite and local carbonate sediment. The carbonate compensation depth, located at about 3700 meters in this area, appears to represent a depth above which waters are essentially saturated with respect to calcite and below which waters deviate toward undersaturation with respect to calcite.
Phosphatases in Lake Water: Characterization of Enzymes from Phytoplankton and Zooplankton by Gel Filtration
Authors: Jansson Mats
Published: October 2006

Sephadex gel filtration was used to characterize phosphomonoesterases in two small lakes in northern Sweden. Two fractions, here termed phosphatase A and phosphatase B, were found both as free enzymes and associated with seston. The activity of phosphatase A was correlated with the presence of algal biomass. Phosphatase B, on the other hand, was derived from zooplankton. Phosphate served as an effective inhibitor of phosphatase A but had no such effect on phosphatase B. Both fractions had
p
H optima between 6.5 and 7.0.
Observations at Mercury Encounter by the Plasma Science Experiment on Mariner 10
Authors: Ogilvie K. W. , Scudder J. D. , Hartle R. E. , Siscoe G. L. , Bridge H. S. , Lazarus A. J. , Asbridge J. R. , Bame S. J. , Yeates C. M.
Published: October 2006

A fully developed bow shock and magnetosheath were observed near Mercury, providing unambiguous evidence for a strong interaction between Mercury and the solar wind. Inside the sheath there is a distinct region analogous to the magnetosphere or magnetotail of Earth, populated by electrons with lower density and higher temperature than the electrons observed in the solar wind or magnetosheath. At the time of encounter, conditions were such that a perpendicular shock was observed on the inbound leg and a parallel shock was observed on the outbound leg of the trajectory, and energetic plasma electron events were detected upstream from the outbound shock crossing. The interaction is most likely not atmospheric, but the data clearly indicate that the obstacle to solar wind flow is magnetic, either intrinsic or induced. The particle fluxes and energy spectra showed large variations while the spacecraft was inside the magnetosphere, and these variations could be either spatial or temporal.
Salt Fingers Observed in the Mediterranean Outflow
Authors: Williams Albert J.
Published: October 2006

Salt fingers, convection cells which constitute a possible mixing mechanism of the ocean, have now been observed in the Mediterranean outflow. The fingers, 6 millimeters in diameter and 24 centimeters long, were photographed below the salinity maximum of the outflow, in an interface 22 centimeters thick where temperature and salinity decreased 0.15°C and 0.03 per mil, respectively.
Earthquakes and the Rotation of the Earth
Authors: Anderson Don L.
Published: October 2006

A correlation exists between long-term variations in the length of the day, Chandler wobble amplitudes, and global seismic activity. These variations may be partially due to climatic changes and ultimately to explosive volcanic activity.
Asymmetric Adsorption of Alanine by Quartz
Authors: Bonner William A. , Kavasmaneck Percy R. , Martin Forrest S. , Flores Jose J.
Published: October 2006

Radioactive D- and L-alanine hydrochloride in 10
-5
molar dimethylformamide solution was adsorbed by
d
- and
l
-quartz to the extent of 20 to 30 percent, as shown by radioactivity loss.
d
-Quartz preferentially adsorbs D-alanine and
l
-quartz adsorbs L-alanine. The extent of asymmetric preferential adsorption is about 1.0 to 1.8 percent, at the 99.9 percent confidence level.
Secondary Calcification of the Planktonic Foraminifer
Neogloboquadrina pachyderma
as a Climatic Index
Authors: Srinivasan M. S. , Kennett J. P.
Published: October 2006

Oscillations in the ratio of two principal types of secondary calcification of the test surface in
Neogloboquadrina pachyderma
populations closely parallel paleoclimatic oscillations over the last 6 million years in a deep-sea core drilled in the temperate South Pacific. The nature of secondary calcification in fossil planktonic foraminifera represents a useful index in interpreting Cenozoic climates.
Isotope Separation in a "Seeded Beam"
Authors: Anderson J. B. , Davidovits P.
Published: October 2006

A new method of separating isotopes in a gaseous mixture is described. The method takes advantage of the differences in velocities of isotopic species in a molecular beam formed by expansion of the mixture with a light gas from a nozzle source. For the separation of the hexafluorides of uranium-235 and uranium-238 the technique has an estimated separative work factor about 500 times higher than the gaseous diffusion process and 100 times higher than the curved-jet method.
Vaporization of Solids: Evidence for a Zipper Mechanism in the Retarded Vaporization of Arsenic
Authors: Hultman Carl A. , Rosenblatt Gerd M.
Published: October 2006

Recent observations indicate that the rate of evaporation of elemental arsenic into a vacuum is determined by the rate of formation, at screw dislocations, of kinks in ledges of molecular height. Once formed, a kink advances along the ledge, which makes a continuous spiral ramp outward from the dislocation, until the ledge terminates. A kink advances by releasing As
4
molecules from the ledge. A given kink releases almost 10
6
As
4
molecules before the next kink is initiated.
Alaskan Thermokarst Terrain and Possible Martian Analog
Authors: Gatto Lawrence W. , Anderson Duwayne M.
Published: October 2006

A first-order analog to martian fretted terrain has been recognized on enhanced, ERTS-1 (Earth Resources Technology Satellite) imagery of Alaskan Arctic thermokarst terrain. The Alaskan analog displays flat-floored valleys and intervalley uplands characteristic of fretted terrain. The thermokarst terrain has formed in a manner similar to one of the processes postulated for the development of the martian fretted terrain.
Gravity Field of Jupiter from Pioneer 11 Tracking Data
Authors: Null George W. , Anderson John D. , Wong Sun Kuen
Published: October 2006

Significantly improved values of the zonal gravity harmonic coefficients J
39
J
4
, and J
6
of Jupiter have been obtained from a preliminary analysis of Pioneer 11 spacecraft Doppler data taken while the spacecraft was near Jupiter. The new results, which will have an important application as boundary conditions for theoretical models of Jupiter's interior are consistent with a planet in hydrostatic equilibrium.
Isolable Oxysulfuranes in Organic Chemistry
Authors: Martin J. C. , Perozzi Edmund F.
Published: October 2006

The development of synthetic methods for oxysulfuranes has made a wide range of isolable compounds of hypervalent sulfur available for study. Structure-reactivity correlations are now becoming evident as a result of such study. The fact that oxygen is dicoordinate makes it possible to synthesize cyclic oxysulfuranes and to use the pronounced changes of reactivity which accompany cyclization to design new, potentially useful sulfurane reagents stable enough to allow isolation.
Neoglyphea inopinata
: A Crustacean "Living Fossil" from the Philippines
Authors: Forest Jacques , de Saint Laurent Michèle , Chace Fenner A.
Published: October 2006

The discovery of an existing member of the Glypheidae, a family believed to have been extinct since the Eocene, may yield significant information on the evolution and classification of the decapod Crustacea. The single known specimen displays characters not apparent in fossil material, some of them perhaps representative of an ancestral decapod lineage, others reminiscent of the Astacidea and Thalassinidea.
Tournaments and Slavery in a Desert Ant
Authors: Hölldobler Bert
Published: October 2006

Many species of ants engage in physical fighting when territorial borders are challenged. In contrast, colonies of the honeypot ant species
Myrmecocystus mimicus
conduct ritualized tournaments, in which hundreds of ants perform highly stereotyped display fights. Opposing colonies summon their worker forces to the tournament area by means of an alarm-recruitment system. When one colony is considerably stronger than the other, the tournament quickly ends, and the weaker colony is raided and its ants "enslaved." This is the first example of intraspecific slavery recorded in ants.
Enhancement of Algal Growth and Productivity by Grazing Zooplankton
Authors: Porter Karen Glaus
Published: October 2006

Colonies of the common planktonic green alga,
Sphaerocystis schroeteri
, are only partially disrupted and assimilated by
Daphnia magna
a natural predator. The
Daphnia
break up the outer protective gelatinous sheath that surrounds
Sphaerocystis
colonies, but most of the algal cells emerge from
Daphnia
guts intact and in viable condition. During gut passage, these viable cells take up nutrients, such as phosphorus, both from algal remains and from
Daphnia
metabolites. This nutrient supply stimulates algal carbon fixation and cell division. Enhanced algal growth, observed after gut passage, can compensate for the minor losses to the population caused by grazing. Nutrients regenerated by grazers may produce the summer bloom of gelatinous green algae during the seasonal succession of lake phytoplankton.
Herbicide (2,4-D) Increases Insect and Pathogen Pests on Corn
Authors: Oka I. N. , Pimentel David
Published: October 2006

Corn leaf aphids, European corn borers, and southern corn leaf blight were more abundant on corn exposed to 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide than they were on unexposed corn. Protein levels were higher in corn plants that were exposed to several dosages of 2,4-D, and this may have favored the growth of pests.
Drug Tolerance in Biomembranes: A Spin Label Study of the Effects of Ethanol
Authors: Chin Jane H. , Goldstein Dora B.
Published: October 2006

Ethanol in vitro increased the fluidity of spin-labeled membranes from normal mice. Membranes from mice that had been subjected to long-term ethanol treatment were relatively resistant to this fluidizing effect. The data suggest that the membranes themselves had adapted to the drug, a novel form of drug tolerance.
Mars Climatology from Viking 1 After 20 Sols
Authors: Hess S. L. , Henry R. M. , Leovy C. B. , Ryan J. A. , Tillman J. E. , Chamberlain T. E. , Cole H. L. , Dutton R. G. , Greene G. C. , Simon W. E. , Mitchell J. L.
Published: October 2006

The results from the meteorology instruments on the Viking 1 lander are presented for the first 20 sols of operation. The daily patterns of temperature, wind, and pressure have been highly consistent during the period. Hence, these have been assembled into 20-sol composites and analyzed harmonically. Maximum temperature was 241.8°K and minimum 187.2°K. The composite wind vector has a mean diurnal magnitude of 2.4 meters per second with prevailing wind from the south and counterclockwise diurnal rotation. Pressure exhibits diurnal and semidiurnal oscillations. The diurnal is ascribed to a combination of effects, and the semidiurnal appears to be the solar semidiurnal tide. Similarities to Earth are discussed. A major finding is a continual secular decrease in diurnal mean pressure. This is ascribed to carbon dioxide deposition at the south polar cap.
The Environs of Viking 2 Lander
Authors: Shorthill Richard W. , Moore Henry J. , Hutton Robert E. , Scott Ronald F. , Spitzer Cary R.
Published: October 2006

Forty-six days after Viking 1 landed, Viking 2 landed in Utopia Planitia, about 6500 kilometers away from the landing site of Viking 1. Images show that in the immediate vicinity of the Viking 2 landing site the surface is covered with rocks, some of which are partially buried, and fine-grained materials. The surface sampler, the lander cameras, engineering sensors, and some data from the other lander experiments were used to investigate the properties of the surface. Lander 2 has a more homogeneous surface, more coarse-grained material, an extensive crust, small rocks or clods which seem to be difficult to collect, and more extensive erosion by the retro-engine exhaust gases than lander 1. A report on the physical properties of the martian surface based on data obtained through sol 58 on Viking 2 and a brief description of activities on Viking 1 after sol 36 are given.
Seawater-Based Crop Production: A Feasibility Study
Authors: Epstein Emanuel , Norlyn J. D.
Published: October 2006

Selections of barley,
Hordeum vulgare
, obtained from a composite cross by means of salinized solution culture, a salt-tolerant research line from Arizona, and three cultivars were grown in dune sand and irrigated with water from the Pacific Ocean. All lines grew and produced grain of good feed quality. There is evidence of considerable phenotypic plasticity and of marked genotypic diversity with respect to conditions of seawater culture. Rough estimates of yield approached half the national average for barley.
Disasters as a Necessary Part of Benefit-Cost Analyses
Authors: Mark R. K. , Stuart-Alexander D. E.
Published: October 2006

Benefit-cost analyses for water projects generally have not included the expected costs (residual risk) of low-probability disasters such as dam failures, impoundment-induced earthquakes, and landslides. Analysis of the history of these types of events demonstrates that dam failures are not uncommon and that the probability of a reservoir-triggered earthquake increases with increasing reservoir depth. Because the expected costs from such events can be significant and risk is project-specific, estimates should be made for each project. The cost of expected damage from a "high-risk" project in an urban area could be comparable to project benefits.
Clustering Hypothesis of Some High-Temperature Superconductors
Authors: Vandenberg J. M. , Matthias B. T.
Published: October 2006

Cluster formation in metallic crystal lattices is important for most high-temperature superconductors.
A Mutant of
Paramecium
Defective in Chemotaxis
Authors: Van Houten Judith
Published: October 2006

In an effort to study the sensory-motor pathway of chemotaxis in
Paramecium tetraurelia
, I have generated mutants defective in their responses to chemicals. One mutant in particular, d4-530, is repelled by sodium acetate, which attracts normal paramecia by klinokinesis. The mutant is repelled by the mechanism of orthokinesis. To my knowledge, this is the first report of orthokinesis in chemotaxis of paramecia.
Hot Spots for Growth Hormone Gene Deletions in Homologous Regions Outside of Alu Repeats
Authors: Vnencak-Jones Cindy L. , Phillips John A.
Published: October 2006

Familial growth hormone deficiency type 1A is an autosomal recessive disease caused by deletion of both growth hormone-1 (GH1) alleles. Ten patients from heterogeneous geographic origins showed differences in restriction fragment length polymorphism haplotypes in nondeleted regions that flanked GH1, suggesting that these deletions arose from independent unequal recombination events. Deoxyribonucleic acid (DNA) samples from nine of ten patients showed that crossovers occurred within 99% homologous, 594-base pair (bp) segments that flanked GH1. A DNA sample from one patient indicated that the crossover occurred within 454-bp segments that flanked GH1 and contained 274-bp repeats that are 98% homologous. Although Alu repeats, which are frequent sites of recombination, are adjacent to GH1, they were not involved in any of the recombination events studied. These results suggest that length and degree of DNA sequence homology are important in defining recombination sites that resulted in GH1 deletions.
Electric Discharges Inside Tornadoes
Authors: Watkins David C. , Cobine James D. , Vonnegut Bernard
Published: October 2006

Laboratory data on a vortex-stabilized arc suggest that its contribution to energy of a tornado would be small.
Larval Dispersal and Species Longevity in Lower Tertiary Gastropods
Authors: Hansen Thor A.
Published: October 2006

Species longevity in Lower Tertiary volutids (Gastropoda) is primarily controlled by a combination of developmental type and environmental tolerance. Larval dispersal may be an important factor in molluskan evolutionary rates.
Rhythms in Pheromone Production of the Male Boll Weevil
Authors: Gueldner R. C. , Wiygul Glenn
Published: October 2006

Male boll weevils,
Anthonomus grandis
held in a light regimen of 16 hours of light and 8 hours of darkness released pheromone rhythmically during the 24 hours. The amount released during peaks was typically 20 times the amount released in valleys. The ratio of the two alcohol components of the pheromone also showed a daily rhythm. Under continuous light, both the release of pheromone and the ratio of the two alcohol components were arrhythmic. In darkness, pheromone release was diminished more than tenfold over the 20-day test period.
Solar Biomass Energy: An Overview of U.S. Potential
Authors: Burwell C. C.
Published: October 2006

The U.S. annual biomass production for food, lumber, paper, and fiber, if used exclusively for energy, would provide 25 percent of current energy requirements. The collection of unharvested wood residues and cull trees for direct use as fuel for small nearby space-heating applications—especially for peak winter conditions—is an important near-term solar energy opportunity. Improved management of hundreds of millions of acres of productive forest land is an important opportunity for the long term. Harvest of cropland residues for energy values, new biomass production using intensive short-rotation silviculture, resubstitution of natural products for petroleum-based synthetics, and forest management for large-scale production of electricity and synthetic fuels are judged to be less appropriate directions for the U.S. energy system to take.
Reputational Ratings of Doctoral Programs
Authors: Hartnett Rodney T. , Clark Mary Jo , Baird Leonard L.
Published: October 2006

Peer ratings of the quality of doctoral program faculties were obtained in a 1975 national survey of chemistry, history, and psychology programs. The ratings were then compared to those obtained 6 and 11 years earlier by the American Council on Education. In general, the rankings obtained from the ratings proved to be highly stable over the 11-year period, particularly in chemistry and history.

Some ratings were also obtained for subspecialties within the three disciplines. Though it is clear that variations in quality among subspecialty faculties do exist and are important for individual program evaluations, it is unlikely that such subspecialty ratings would be feasible or useful in national surveys of the reputations of doctoral programs.

The ratings were found to be highly related to a number of research-oriented variables of departments (such as size, productivity, percentage of alumni holding academic positions at Ph.D.-granting universities), but unrelated or very weakly related to such features as the student-reported quality of teaching and degree of faculty concern for students, or faculty-reported degree of departmental effort toward the career development of junior members of the faculty.
Determination of Membrane Protein Structure by Rotational Resonance NMR: Bacteriorhodopsin
Authors: Creuzet F. , McDermott A. , Gebhard R. , van der Hoef K. , Spijker-Assink M. B. , Herzfeld J. , Lugtenburg J. , Levitt M. H. , Griffin R. G.
Published: October 2006

Rotationally resonant magnetization exchange, a new nuclear magnetic resonance (NMR) technique for measuring internuclear distances between like spins in solids, was used to determine the distance between the C-8 and C-18 carbons of retinal in two model compounds and in the membrane protein bacteriorhodopsin. Magnetization transfer between inequivalent spins with an isotropic shift separation, δ, is driven by magic angle spinning at a speed ω
r
that matches the rotational resonance condition δ =
n
ω
r
, where
n
is a small integer. The distances measured in this way for both the 6-s-
cis
- and 6-s-
trans
-retinoic acid model compounds agreed well with crystallographically known distances. In bacteriorhodopsin the exchange trajectory between C-8 and C-18 was in good agreement with the internuclear distance for a 6-s-
trans
configuration [4.2 angstroms (Å)] and inconsistent with that for a 6-s-
cis
configuration (3.1 Å). The results illustrate that rotational resonance can be used for structural studies in membrane proteins and in other situations where diffraction and solution NMR techniques yield limited information.
Atomic Hydrogen on Mars: Measurements at Solar Minimum
Authors: Levine Joel S. , McDougal David S. , Anderson Donald E. , Barker Edwin S.
Published: October 2006

The Copernicus Orbiting Astronomical Observatory was used to obtain measurements of Mars Lyman-α (1215.671-angstrom) emission at the solar minimum, which has resulted in the first information on atomic hydrogen concentrations in the upper atmosphere of Mars at the solar minimum. The Copernicus measurements, coupled with the Viking in situ measurements of the temperature (170° ± 30°K) of the upper atmosphere of Mars, indicate that the atomic hydrogen number density at the exobase of Mars (250 kilometers) is about 60 times greater than that deduced from Mariner 6 and 7 Lyman-α measurements obtained during a period of high solar activity. The Copernicus results are consistent with Hunten's hypothesis of the diffusion-limited escape of atomic hydrogen from Mars.
Breeding Patterns of Galápagos Penguins as an Indicator of Oceanographic Conditions
Authors: Boersma P. Dee
Published: October 2006

Surface water changes associated with El Niño have been known to affect deleteriously top carnivores along coastal South America. Data on the breeding strategies of Galápagos penguins and other seabirds indicate that the biological effects of El Niño extend much farther west. The breeding biology of these seabirds is adapted to frequent changes in productivity which are associated with El Niño.
Chemical Sensors Based on Controlled-Release Polymer Systems
Authors: Barnard Steven M. , Walt David R.
Published: October 2006

A novel chemical sensor has been developed in which the polymer ethylene-vinyl acetate is used as a controlled-release system to deliver reagents to the sensing region of an optical fiber for a homogeneous competitive immunoassay based on fluorescence energy transfer. A competition reaction is used to enable continuous measurements of the solution antigen concentration. More generally, the technique allows irreversible indicating chemistries to be used in the construction of chemical sensors that can measure continuously for long periods. Although the sensor configuration has not been optimized in all respects, data are presented for a model system in which a fluorescein-labeled antibody and Texas Red-labeled immunoglobulin G (IgG) are used.
Velocity Anomalies in Dilatant Rock
Authors: Scholz Christopher H.
Published: October 2006

Seismic velocities measured in rock deformed in the laboratory show excellent agreement with theoretical predictions of the effects of crack growth during dilatancy. Under appropriate conditions dilatancy was observed to produce a drop in the ratio of the seismic compressional velocity to the seismic shear velocity both by the mechanism of undersaturation and by a liquid-gas phase transition.
Directionality and Auditory Slit Function: A Theory of Hearing in Bushcrickets
Authors: Bailey Winston J. , Stephen R. O.
Published: October 2006

Female bushcrickets locate their mates by sound. Auditory acuity is mediated by the complex anatomy of the tympanal slits, associated trachea, and spiracle. By manipulating the acoustic properties of this system and measuring the neural output, a bilobed, highly directional mechanism associated with the slits is observed, confirming Autrum's original hypothesis.
Oceanic Residence Times of Dissolved Beryllium and Aluminum Deduced from Cosmogenic Tracers
10
Be and
26
Al
Authors: Yokoyama Yuji , Guichard François , Reyss Jean-Louis , Van Nguyen Huu
Published: October 2006

The residence times of the soluble fractions of beryllium and aluminum in seawater are estimated to be 1500 years or more. These residence times are estimated from a comparison of the annual deposition rates of cosmogenic beryllium-10 and aluminum-26 with the concentrations of beryllium-10 and aluminum-26 in seawater estimated from the specific activities of these radionuclides in an authigenic mineral assembly such as a manganese nodule. These residence times are greater by an order of magnitude than the mean residence times of beryllium and aluminum estimated from the geochemical balance.
Micropaleontology and Ocean Surface Climate
Authors: Weyl Peter K.
Published: October 2006

The interpretation of micropaleontological data based on the fossil remains of planktonic organisms requires an appropriate reference frame. The environmental changes that the plankton experience are a combination of geographic and seasonal factors, correlated by the average drift trajectories. Appropriate methods have been developed to study two drifts in the North Atlantic, one form the west-central Sargasso Sea to the Norwegian Sea and another around the subtropical Sargasso Gyre. The data on planktonic foraminifera from core tops can be used to relate the relative species distribution to the characteristics of the present sea surface. At any one location, the fossil assembly results from a superposition of plankton that have had varied time-temperature histories. To interpret the climatic and geologic history from downcore data will require an iterative technique. One assumes a surface climatology, determines the fossil record this would produce, and then compares this inference with available core data. The climatological assumptions are then modified until a satisfactory agreement is reached.
Transmission Electron Microscopy: Direct Observation of Crystal Structure in Refractory Ceramics
Authors: Shaw T. M. , Thomas G.
Published: October 2006

Using high-resolution multibeam interference techniques in the transmission electron microscope, images have been obtained that make possible a real-space structure analysis of a beryllium-silicon-nitrogen compound. The results illustrate the usefulness of lattice imaging in the analysis of local crystal structure in these technologically promising ceramic materials.
Shark Skin: Function in Locomotion
Authors: Wainwright S. A. , Vosburgh F. , Hebrank J. H.
Published: October 2006

Hydrostatic pressure under the skin of sharks varies with swimming speed. Stress in the skin varies with the internal pressure, and the skin stress controls skin stiffness. Locomotory muscles attach to the skin which is thus a whole-body exotendon whose mechanical advantage in transmitting muscular contraction is greater than that of the endoskeleton.
Intercellular Communication in Insect Development Is Hormonally Controlled
Authors: Caveney Stanley
Published: October 2006

Cellular coupling in the insect epidermis changes in a characteristic way during metamorphosis. In vitro, β-ecdysone mimics the initial phase of these changes by increasing electrical coupling. Both adenosine 3′,5′-monophosphate (cyclic AMP) and Ca
2+
reverse natural and β-ecdysone-stimulated changes, which suggests that ecdysone could work on communication through changes in cyclic AMP and Ca
2+
levels. The transient changes in intercellular communication before metamorphosis may reflect the timing of the signals that trigger proliferation and the generation of new spatial patterns in the epidermis.
Deep UV Photochemistry of Chemisorbed Monolayers: Patterned Coplanar Molecular Assemblies
Authors: Dulcey Charles S. , Georger Jacque H. , Krauthamer Victor , Stenger David A. , Fare Thomas L. , Calvert Jeffrey M.
Published: October 2006

Deep ultraviolet (UV) irradiation is shown to modify organosilane self-assembled monolayer (SAM) films by a photocleavage mechanism, which renders the surface amenable to further SAM modification. Patterned UV exposure creates alternating regions of intact SAM film and hydrophilic, reactive sites. The exposed regions can undergo a second chemisorption reaction to produce an assembly of SAMs in the same molecular plane with similar substrate attachment chemistry. The UV-patterned films are used as a template for selective buildup of fluorophores, metals, and biological cells.
Upwelling: Oceanic Structure at the Edge of the Arctic Ice Pack in Winter
Authors: Buckley J. R. , Gammelsrød T. , Johannessen J. A. , Johannessen O. M. , Røed L. P.
Published: October 2006

Observations taken on an expedition into the Arctic Ocean north of Spitsbergen indicated the existence of a region of wind-driven upwelling along the edge of the ice pack. Models underestimate the 12-kilometer width of the upwelling region.
Phycomyces
: Modification of Spiral Growth after Mechanical Conditioning of the Cell Wall
Authors: Gamow R. I. , Bottger B.
Published: October 2006

Mature stage IVb
Phycomyces
sporangiophores show left-handed spiral growth; that is, viewed from above, the sporangium rotates clockwise. Mechanical conditioning of the cell wall by the Instron technique increases the ratio of the rotational to the elongational growth rate. This result is in agreement with the fibril reorientation model of spiral growth, which suggests that cell wall microfibrils, initially oriented in a nearly transverse right-handed direction in the upper region of the growing zone, are displaced during growth toward the longitudinal axis, causing the observed left-handed spiral growth.
Terrestrial Ages of Four Allan Hills Meteorites: Consequences for Antarctic Ice
Authors: Fireman E. L. , Rancitelli L. A. , Kirsten T.
Published: October 2006

The terrestrial ages of three Allan Hills meteorites are between 3 × 10
4
and 3 × 10
5
years and one is (1.54
–0.28
+0.14
) × 10
6
years old. The Antarctic ice sheet is therefore older than (1.54
–0.28
+0.14
) × 10
6
years and the meteorite accumulation process at Allan Hills probably began between 3 × 10
4
and 3 × 10
5
years ago.
Predator Removal: Effect on Fisheries Yields in Lake Victoria (East Africa)
Authors: Marten Gerald G.
Published: October 2006

Lake Victoria's artisanal fishery has an overfishing problem. A possible solution is suggested by records showing that fish catches are best where predator populations have been reduced by fishing. It may be possible to remedy overfishing by increasing fishing effort, provided the additional effort is directed toward predators.
Orbiter Cloud Photopolarimeter Investigation
Authors: Travis L. D. , Coffeen D. L. , Hansen J. E. , Kawabata K. , Lacis A. A. , Lane W. A. , Limaye S. S. , Stone P. H.
Published: October 2006

The first polarization measurements of the orbiter cloud photopolarimeter have detected a planet-wide layer of submicrometer aerosols of substantial visible optical thickness, of the order of 0.05 to 0.1, in the lower stratosphere well above the main visible sulfuric acid cloud layer. Early images show a number of features observed by Mariner 10 in 1974, including planetary scale markings that propagate around the planet in the retrograde sense at roughly 100 meters per second and bright- and dark-rimmed cells suggesting convective activity at low latitudes. The polar regions are covered by bright clouds down to latitudes approximately 50 degrees, with both caps significantly brighter (relative to low latitudes) than the south polar cloud observed by Mariner 10. The cellular features, often organized into clusters with large horizontal scale, exist also at mid-latitudes, and include at least one case in which a cell cuts across the edge of the bright polar cloud of the northern hemisphere.
Energy Choices for the Next 15 Years: A View from Europe
Authors: Zaleski C. Pierre L.-
Published: October 2006

A European perception of the world energy situation and its likely evolution during the next two decades is presented. French energy policy is then discussed as a possible set of consistent choices that can be made to deal with the energy situation in a regional context for the next 15 years.
Economic Feasibility of Solar Water and Space Heating
Authors: Bezdek Roger H. , Hirshberg Alan S. , Babcock William H.
Published: October 2006

The economic feasibility in 1977 and 1978 of solar water and combined water and space heating is analyzed for single-family detached residences and multi-family apartment buildings in four representative U.S. cities: Boston, Massachusetts; Washington, D.C.; Grand Junction, Colorado; and Los Angeles, California. Three economic decision criteria are utilized: payback period, years to recovery of down payment, and years to net positive cash flow. The cost competitiveness of the solar systems compared to heating systems based on electricity, fuel oil, and natural gas is then discussed for each city, and the impact of the federal tax credit for solar energy systems is assessed. It is found that even without federal incentives some solar water and space heating systems are competitive. Enactment of the solar tax credit, however, greatly enhances their competitiveness. The implications of these findings for government tax and energy pricing policies are discussed.
Homoeologous Heterozygosity and Recombination in the Fern
Pteridium aquilinum
Authors: Chapman Robert H. , Klekowski Edward J. , Selander Robert K.
Published: October 2006

The bracken fern,
Pteridium aquilinum
, which can form completely homozygous zygotes in a single generation of self-fertilization, has a genetic system that allows the storage and release of genetic variability in spite of this homozygosity. Analysis of the distribution of electrophoretically demonstrable genetic markers demonstrates that this system is based on recombination between duplicated, unlinked loci.
Immunity to Antigens Associated with Primate C-Type Oncoviruses in Pregnant Women
Authors: Hirsch Martin S. , Kelly Ann P. , Chapin David S. , Fuller Thomas C. , Black Paul H. , Kurth Reinhard
Published: October 2006

Cell-mediated and humoral immune responses against antigens associated with primate C-type oncoviruses were evaluated in humans by microcytotoxicity and radioimmunoprecipitation assays. Five of six women tested sequentially during pregnancy developed selective cell-mediated reactivity against baboon endogenous virus (BEV)-infected human fibroblasts. Responsiveness peaked during the second and third trimesters and corresponded temporally with elevated antibody levels to BEV antigens. Similar cell-mediated reactivity was not observed in nonpregnant individuals. Selective cell-mediated reactivity directed against cells infected with the simian sarcoma virus-simian sarcoma associated virus complex (SSV-SSAV) was observed in four of 20 healthy adults (three of 14 nonpregnant, one of six pregnant). These observations suggest that cell-mediated reactivity against primate C-type oncoviruses is occasionally detected in healthy nonpregnant adults, but that during pregnancy both cell-mediated and humoral reactivity against BEV may become selectively expressed.
Inhibition of Bone Resorption in Vitro by a Cartilage-Derived Anticollagenase Factor
Authors: Horton John E. , Wezeman Frederick H. , Kuettner Klaus E.
Published: October 2006

A cartilage-derived factor containing a specific collagenous inhibitor was found to block reversibly parathyroid hormone-stimulated
45
Ca release from fetal rat bone in vitro. Morphologic and quantitative histometric examination revealed that this factor modulates osteoclastic activities.
Genetic Mapping of Xenotropic Leukemia Virus-Inducing Loci in Two Mouse Strains
Authors: Kozak Christine , Rowe Wallace P.
Published: October 2006

In genetic studies of C57BL/10 and BALB/c mice, inducibility of xenotropic murine leukemia virus from tissue cultures by treatment with 5-iododeoxyuridine shows single gene segregation ratios. In both strains, the virus-inducing loci are on chromosome 1, linked to the
Dip-1
isozyme locus, but the two may not be at allelic sites.
Alteration of Four Identified K
+
Currents in
Drosophila
Muscle by Mutations in
eag
Authors: Zhong Yi , Wu Chun-Fang
Published: October 2006

Voltage-clamp analysis of
Drosophila
larval muscle revealed that
ether à go-go
(
eag
) mutations affected all identified potassium currents, including those specifically eliminated by mutations in the
Shaker
or
slowpoke
gene. Together with DNA sequence analysis, the results suggest that the
eag
locus encodes a subunit common to different potassium channels. Thus, combinatorial assembly of polypeptides from different genes may contribute to potassium channel diversity.
Cloud Images from the Pioneer Venus Orbiter
Authors: Travis L. D. , Coffeen D. L. , Del Genio A. D. , Hansen J. E. , Kawabata K. , Lacis A. A. , Lane W. A. , Limaye S. S. , Rossow W. B. , Stone P. H.
Published: October 2006

Ultraviolet images of Venus over a 3-month period show marked evolution of the planetary scale features in the cloud patterns. The dark horizontal Y feature recurs quasi-periodically, at intervals of about 4 days, but it has also been absent for periods of several weeks. Bow-shaped features observed in Pioneer Venus images are farther upstream from the subsolar point than those in Mariner 10 images.
Measurements of Turbulence in the Venus Atmosphere Deduced from Pioneer Venus Multiprobe Radio Scintillations
Authors: Woo Richard , Armstrong J. W. , Kendall William B.
Published: October 2006

The 2.3-gigahertz log-amplitude fluctuations observed in the radio links of the Pioneer Venus entry probes during Venus encounter have been used to study turbulence in the Venus atmosphere. The deduced estimates of the upper bound of structure constant c
n
of the refractive index fluctuations (c
n
≲ 4 × 10
–8
cm
–1/3
) are inconsistent with similar entry probe measurements by Veneras 4 to 8 but are consistent with the radio occultation measurements by flyby (Mariners 5 and 10) and orbiting (Venera 9) spacecraft. The Pioneer Venus measurements therefore provide a resolution of the long-standing order of magnitude discrepancy between these earlier measurements of c
n
.
Magnesium Interaction with the Surface of Calcite in Seawater
Authors: Morse John W. , Mucci Alfonso , Walter Lynn M. , Kaminsky Manfred S.
Published: October 2006

Magnesian calcite overgrowth containing 4 (± 2) mole percent magnesium carbonate forms on calcite exposed to natural seawater near the ocean surface. This magnesian calcite is approximately 30 percent less soluble in seawater than pure calcite. The formation of the magnesian calcite of reduced solubility may have a major influence on calcite accumulation in deep sea sediments.
Atmospheric Sulfur Aerosol Concentrations and Characteristics from the South American Continent
Authors: Lawson Douglas R. , Winchester John W.
Published: October 2006

Aerosol samples collected from eight geographically distinct locations in South America during the austral winter of 1976 and summer of 1977 with six-stage cascade impactors show a tropospheric sulfur background concentration of about 50 nanograms per cubic meter of air in the fine-particle mode (< 1 micrometer in aerodynamic diameter). Time-sequence filter samples, taken concurrently at most locations, show an average non-sea spray related sulfur concentration of about 85 nanograms per cubic meter. These concentrations are substantially lower than most published nonurban values for the Northern Hemisphere obtained by similar sampling and analysis techniques and may represent a natural tropospheric background level of aerosol sulfur.
Recent Crustal Uplift in Yellowstone National Park
Authors: Pelton J. R. , Smith R. B.
Published: October 2006

Comparison of precise leveling measurements made in 1923 with those made in 1975, 1976, and 1977 reveals that the 600,000-year-old Yellowstone caldera is being uplifted relative to its surroundings. Maximum relative uplift since 1923 is in excess of 700 millimeters—about 14 millimeters vertically per year. The most likely cause of this rapid and unusually large surface deformation is a recent influx of molten or partially molten material to a location within the crust beneath Yellowstone National Park.